//===- SLPVectorizer.cpp - A bottom up SLP Vectorizer ---------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This pass implements the Bottom Up SLP vectorizer. It detects consecutive
// stores that can be put together into vector-stores. Next, it attempts to
// construct vectorizable tree using the use-def chains. If a profitable tree
// was found, the SLP vectorizer performs vectorization on the tree.
//
// The pass is inspired by the work described in the paper:
//  "Loop-Aware SLP in GCC" by Ira Rosen, Dorit Nuzman, Ayal Zaks.
//
//===----------------------------------------------------------------------===//

#include "llvm/Transforms/Vectorize/SLPVectorizer.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/DenseSet.h"
#include "llvm/ADT/PriorityQueue.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/ScopeExit.h"
#include "llvm/ADT/SetOperations.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/ADT/SmallBitVector.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallSet.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/iterator.h"
#include "llvm/ADT/iterator_range.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Analysis/AssumptionCache.h"
#include "llvm/Analysis/CodeMetrics.h"
#include "llvm/Analysis/ConstantFolding.h"
#include "llvm/Analysis/DemandedBits.h"
#include "llvm/Analysis/GlobalsModRef.h"
#include "llvm/Analysis/IVDescriptors.h"
#include "llvm/Analysis/LoopAccessAnalysis.h"
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/Analysis/MemoryLocation.h"
#include "llvm/Analysis/OptimizationRemarkEmitter.h"
#include "llvm/Analysis/ScalarEvolution.h"
#include "llvm/Analysis/ScalarEvolutionExpressions.h"
#include "llvm/Analysis/TargetLibraryInfo.h"
#include "llvm/Analysis/TargetTransformInfo.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/Analysis/VectorUtils.h"
#include "llvm/IR/Attributes.h"
#include "llvm/IR/BasicBlock.h"
#include "llvm/IR/Constant.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/Dominators.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/InstrTypes.h"
#include "llvm/IR/Instruction.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/Intrinsics.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/Operator.h"
#include "llvm/IR/PatternMatch.h"
#include "llvm/IR/Type.h"
#include "llvm/IR/Use.h"
#include "llvm/IR/User.h"
#include "llvm/IR/Value.h"
#include "llvm/IR/ValueHandle.h"
#ifdef EXPENSIVE_CHECKS
#include "llvm/IR/Verifier.h"
#endif
#include "llvm/Pass.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/DOTGraphTraits.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/GraphWriter.h"
#include "llvm/Support/InstructionCost.h"
#include "llvm/Support/KnownBits.h"
#include "llvm/Support/MathExtras.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Transforms/Utils/InjectTLIMappings.h"
#include "llvm/Transforms/Utils/Local.h"
#include "llvm/Transforms/Utils/LoopUtils.h"
#include "llvm/Transforms/Utils/ScalarEvolutionExpander.h"
#include <algorithm>
#include <cassert>
#include <cstdint>
#include <iterator>
#include <memory>
#include <optional>
#include <set>
#include <string>
#include <tuple>
#include <utility>

using namespace llvm;
using namespace llvm::PatternMatch;
using namespace slpvectorizer;

#define SV_NAME "slp-vectorizer"
#define DEBUG_TYPE "SLP"

STATISTIC(NumVectorInstructions, "Number of vector instructions generated");

static cl::opt<bool>
    RunSLPVectorization("vectorize-slp", cl::init(true), cl::Hidden,
                        cl::desc("Run the SLP vectorization passes"));

static cl::opt<bool>
    SLPReVec("slp-revec", cl::init(false), cl::Hidden,
             cl::desc("Enable vectorization for wider vector utilization"));

static cl::opt<int>
    SLPCostThreshold("slp-threshold", cl::init(0), cl::Hidden,
                     cl::desc("Only vectorize if you gain more than this "
                              "number "));

static cl::opt<bool> SLPSkipEarlyProfitabilityCheck(
    "slp-skip-early-profitability-check", cl::init(false), cl::Hidden,
    cl::desc("When true, SLP vectorizer bypasses profitability checks based on "
             "heuristics and makes vectorization decision via cost modeling."));

static cl::opt<bool>
ShouldVectorizeHor("slp-vectorize-hor", cl::init(true), cl::Hidden,
                   cl::desc("Attempt to vectorize horizontal reductions"));

static cl::opt<bool> ShouldStartVectorizeHorAtStore(
    "slp-vectorize-hor-store", cl::init(false), cl::Hidden,
    cl::desc(
        "Attempt to vectorize horizontal reductions feeding into a store"));

static cl::opt<int>
MaxVectorRegSizeOption("slp-max-reg-size", cl::init(128), cl::Hidden,
    cl::desc("Attempt to vectorize for this register size in bits"));

static cl::opt<unsigned>
MaxVFOption("slp-max-vf", cl::init(0), cl::Hidden,
    cl::desc("Maximum SLP vectorization factor (0=unlimited)"));

/// Limits the size of scheduling regions in a block.
/// It avoid long compile times for _very_ large blocks where vector
/// instructions are spread over a wide range.
/// This limit is way higher than needed by real-world functions.
static cl::opt<int>
ScheduleRegionSizeBudget("slp-schedule-budget", cl::init(100000), cl::Hidden,
    cl::desc("Limit the size of the SLP scheduling region per block"));

static cl::opt<int> MinVectorRegSizeOption(
    "slp-min-reg-size", cl::init(128), cl::Hidden,
    cl::desc("Attempt to vectorize for this register size in bits"));

static cl::opt<unsigned> RecursionMaxDepth(
    "slp-recursion-max-depth", cl::init(12), cl::Hidden,
    cl::desc("Limit the recursion depth when building a vectorizable tree"));

static cl::opt<unsigned> MinTreeSize(
    "slp-min-tree-size", cl::init(3), cl::Hidden,
    cl::desc("Only vectorize small trees if they are fully vectorizable"));

// The maximum depth that the look-ahead score heuristic will explore.
// The higher this value, the higher the compilation time overhead.
static cl::opt<int> LookAheadMaxDepth(
    "slp-max-look-ahead-depth", cl::init(2), cl::Hidden,
    cl::desc("The maximum look-ahead depth for operand reordering scores"));

// The maximum depth that the look-ahead score heuristic will explore
// when it probing among candidates for vectorization tree roots.
// The higher this value, the higher the compilation time overhead but unlike
// similar limit for operands ordering this is less frequently used, hence
// impact of higher value is less noticeable.
static cl::opt<int> RootLookAheadMaxDepth(
    "slp-max-root-look-ahead-depth", cl::init(2), cl::Hidden,
    cl::desc("The maximum look-ahead depth for searching best rooting option"));

static cl::opt<unsigned> MinProfitableStridedLoads(
    "slp-min-strided-loads", cl::init(2), cl::Hidden,
    cl::desc("The minimum number of loads, which should be considered strided, "
             "if the stride is > 1 or is runtime value"));

static cl::opt<unsigned> MaxProfitableLoadStride(
    "slp-max-stride", cl::init(8), cl::Hidden,
    cl::desc("The maximum stride, considered to be profitable."));

static cl::opt<bool>
    ViewSLPTree("view-slp-tree", cl::Hidden,
                cl::desc("Display the SLP trees with Graphviz"));

static cl::opt<bool> VectorizeNonPowerOf2(
    "slp-vectorize-non-power-of-2", cl::init(false), cl::Hidden,
    cl::desc("Try to vectorize with non-power-of-2 number of elements."));

// Limit the number of alias checks. The limit is chosen so that
// it has no negative effect on the llvm benchmarks.
static const unsigned AliasedCheckLimit = 10;

// Limit of the number of uses for potentially transformed instructions/values,
// used in checks to avoid compile-time explode.
static constexpr int UsesLimit = 64;

// Another limit for the alias checks: The maximum distance between load/store
// instructions where alias checks are done.
// This limit is useful for very large basic blocks.
static const unsigned MaxMemDepDistance = 160;

/// If the ScheduleRegionSizeBudget is exhausted, we allow small scheduling
/// regions to be handled.
static const int MinScheduleRegionSize = 16;

/// Maximum allowed number of operands in the PHI nodes.
static const unsigned MaxPHINumOperands = 128;

/// Predicate for the element types that the SLP vectorizer supports.
///
/// The most important thing to filter here are types which are invalid in LLVM
/// vectors. We also filter target specific types which have absolutely no
/// meaningful vectorization path such as x86_fp80 and ppc_f128. This just
/// avoids spending time checking the cost model and realizing that they will
/// be inevitably scalarized.
static bool isValidElementType(Type *Ty) {
  // TODO: Support ScalableVectorType.
  if (SLPReVec && isa<FixedVectorType>(Ty))
    Ty = Ty->getScalarType();
  return VectorType::isValidElementType(Ty) && !Ty->isX86_FP80Ty() &&
         !Ty->isPPC_FP128Ty();
}

/// Returns the type of the given value/instruction \p V. If it is store,
/// returns the type of its value operand, for Cmp - the types of the compare
/// operands and for insertelement - the type os the inserted operand.
/// Otherwise, just the type of the value is returned.
template <typename T> static Type *getValueType(T *V) {
  if (auto *SI = dyn_cast<StoreInst>(V))
    return SI->getValueOperand()->getType();
  if (auto *CI = dyn_cast<CmpInst>(V))
    return CI->getOperand(0)->getType();
  if (auto *IE = dyn_cast<InsertElementInst>(V))
    return IE->getOperand(1)->getType();
  return V->getType();
}

/// \returns the number of elements for Ty.
static unsigned getNumElements(Type *Ty) {
  assert(!isa<ScalableVectorType>(Ty) &&
         "ScalableVectorType is not supported.");
  if (auto *VecTy = dyn_cast<FixedVectorType>(Ty))
    return VecTy->getNumElements();
  return 1;
}

/// \returns the vector type of ScalarTy based on vectorization factor.
static FixedVectorType *getWidenedType(Type *ScalarTy, unsigned VF) {
  return FixedVectorType::get(ScalarTy->getScalarType(),
                              VF * getNumElements(ScalarTy));
}

static void transformScalarShuffleIndiciesToVector(unsigned VecTyNumElements,
                                                   SmallVectorImpl<int> &Mask) {
  // The ShuffleBuilder implementation use shufflevector to splat an "element".
  // But the element have different meaning for SLP (scalar) and REVEC
  // (vector). We need to expand Mask into masks which shufflevector can use
  // directly.
  SmallVector<int> NewMask(Mask.size() * VecTyNumElements);
  for (unsigned I : seq<unsigned>(Mask.size()))
    for (auto [J, MaskV] : enumerate(MutableArrayRef(NewMask).slice(
             I * VecTyNumElements, VecTyNumElements)))
      MaskV = Mask[I] == PoisonMaskElem ? PoisonMaskElem
                                        : Mask[I] * VecTyNumElements + J;
  Mask.swap(NewMask);
}

/// \returns the number of groups of shufflevector
/// A group has the following features
/// 1. All of value in a group are shufflevector.
/// 2. The mask of all shufflevector is isExtractSubvectorMask.
/// 3. The mask of all shufflevector uses all of the elements of the source.
/// e.g., it is 1 group (%0)
/// %1 = shufflevector <16 x i8> %0, <16 x i8> poison,
///    <8 x i32> <i32 0, i32 1, i32 2, i32 3, i32 4, i32 5, i32 6, i32 7>
/// %2 = shufflevector <16 x i8> %0, <16 x i8> poison,
///    <8 x i32> <i32 8, i32 9, i32 10, i32 11, i32 12, i32 13, i32 14, i32 15>
/// it is 2 groups (%3 and %4)
/// %5 = shufflevector <8 x i16> %3, <8 x i16> poison,
///    <4 x i32> <i32 0, i32 1, i32 2, i32 3>
/// %6 = shufflevector <8 x i16> %3, <8 x i16> poison,
///    <4 x i32> <i32 4, i32 5, i32 6, i32 7>
/// %7 = shufflevector <8 x i16> %4, <8 x i16> poison,
///    <4 x i32> <i32 0, i32 1, i32 2, i32 3>
/// %8 = shufflevector <8 x i16> %4, <8 x i16> poison,
///    <4 x i32> <i32 4, i32 5, i32 6, i32 7>
/// it is 0 group
/// %12 = shufflevector <8 x i16> %10, <8 x i16> poison,
///     <4 x i32> <i32 0, i32 1, i32 2, i32 3>
/// %13 = shufflevector <8 x i16> %11, <8 x i16> poison,
///     <4 x i32> <i32 0, i32 1, i32 2, i32 3>
static unsigned getShufflevectorNumGroups(ArrayRef<Value *> VL) {
  if (VL.empty())
    return 0;
  if (!all_of(VL, IsaPred<ShuffleVectorInst>))
    return 0;
  auto *SV = cast<ShuffleVectorInst>(VL.front());
  unsigned SVNumElements =
      cast<FixedVectorType>(SV->getOperand(0)->getType())->getNumElements();
  unsigned ShuffleMaskSize = SV->getShuffleMask().size();
  unsigned GroupSize = SVNumElements / ShuffleMaskSize;
  if (GroupSize == 0 || (VL.size() % GroupSize) != 0)
    return 0;
  unsigned NumGroup = 0;
  for (size_t I = 0, E = VL.size(); I != E; I += GroupSize) {
    auto *SV = cast<ShuffleVectorInst>(VL[I]);
    Value *Src = SV->getOperand(0);
    ArrayRef<Value *> Group = VL.slice(I, GroupSize);
    SmallBitVector ExpectedIndex(GroupSize);
    if (!all_of(Group, [&](Value *V) {
          auto *SV = cast<ShuffleVectorInst>(V);
          // From the same source.
          if (SV->getOperand(0) != Src)
            return false;
          int Index;
          if (!SV->isExtractSubvectorMask(Index))
            return false;
          ExpectedIndex.set(Index / ShuffleMaskSize);
          return true;
        }))
      return 0;
    if (!ExpectedIndex.all())
      return 0;
    ++NumGroup;
  }
  assert(NumGroup == (VL.size() / GroupSize) && "Unexpected number of groups");
  return NumGroup;
}

/// \returns a shufflevector mask which is used to vectorize shufflevectors
/// e.g.,
/// %5 = shufflevector <8 x i16> %3, <8 x i16> poison,
///    <4 x i32> <i32 0, i32 1, i32 2, i32 3>
/// %6 = shufflevector <8 x i16> %3, <8 x i16> poison,
///    <4 x i32> <i32 4, i32 5, i32 6, i32 7>
/// %7 = shufflevector <8 x i16> %4, <8 x i16> poison,
///    <4 x i32> <i32 0, i32 1, i32 2, i32 3>
/// %8 = shufflevector <8 x i16> %4, <8 x i16> poison,
///    <4 x i32> <i32 4, i32 5, i32 6, i32 7>
/// the result is
/// <0, 1, 2, 3, 12, 13, 14, 15, 16, 17, 18, 19, 28, 29, 30, 31>
static SmallVector<int> calculateShufflevectorMask(ArrayRef<Value *> VL) {
  assert(getShufflevectorNumGroups(VL) && "Not supported shufflevector usage.");
  auto *SV = cast<ShuffleVectorInst>(VL.front());
  unsigned SVNumElements =
      cast<FixedVectorType>(SV->getOperand(0)->getType())->getNumElements();
  SmallVector<int> Mask;
  unsigned AccumulateLength = 0;
  for (Value *V : VL) {
    auto *SV = cast<ShuffleVectorInst>(V);
    for (int M : SV->getShuffleMask())
      Mask.push_back(M == PoisonMaskElem ? PoisonMaskElem
                                         : AccumulateLength + M);
    AccumulateLength += SVNumElements;
  }
  return Mask;
}

/// \returns True if the value is a constant (but not globals/constant
/// expressions).
static bool isConstant(Value *V) {
  return isa<Constant>(V) && !isa<ConstantExpr, GlobalValue>(V);
}

/// Checks if \p V is one of vector-like instructions, i.e. undef,
/// insertelement/extractelement with constant indices for fixed vector type or
/// extractvalue instruction.
static bool isVectorLikeInstWithConstOps(Value *V) {
  if (!isa<InsertElementInst, ExtractElementInst>(V) &&
      !isa<ExtractValueInst, UndefValue>(V))
    return false;
  auto *I = dyn_cast<Instruction>(V);
  if (!I || isa<ExtractValueInst>(I))
    return true;
  if (!isa<FixedVectorType>(I->getOperand(0)->getType()))
    return false;
  if (isa<ExtractElementInst>(I))
    return isConstant(I->getOperand(1));
  assert(isa<InsertElementInst>(V) && "Expected only insertelement.");
  return isConstant(I->getOperand(2));
}

/// Returns power-of-2 number of elements in a single register (part), given the
/// total number of elements \p Size and number of registers (parts) \p
/// NumParts.
static unsigned getPartNumElems(unsigned Size, unsigned NumParts) {
  return PowerOf2Ceil(divideCeil(Size, NumParts));
}

/// Returns correct remaining number of elements, considering total amount \p
/// Size, (power-of-2 number) of elements in a single register \p PartNumElems
/// and current register (part) \p Part.
static unsigned getNumElems(unsigned Size, unsigned PartNumElems,
                            unsigned Part) {
  return std::min<unsigned>(PartNumElems, Size - Part * PartNumElems);
}

#if !defined(NDEBUG)
/// Print a short descriptor of the instruction bundle suitable for debug output.
static std::string shortBundleName(ArrayRef<Value *> VL, int Idx = -1) {
  std::string Result;
  raw_string_ostream OS(Result);
  if (Idx >= 0)
    OS << "Idx: " << Idx << ", ";
  OS << "n=" << VL.size() << " [" << *VL.front() << ", ..]";
  return Result;
}
#endif

/// \returns true if all of the instructions in \p VL are in the same block or
/// false otherwise.
static bool allSameBlock(ArrayRef<Value *> VL) {
  Instruction *I0 = dyn_cast<Instruction>(VL[0]);
  if (!I0)
    return false;
  if (all_of(VL, isVectorLikeInstWithConstOps))
    return true;

  BasicBlock *BB = I0->getParent();
  for (int I = 1, E = VL.size(); I < E; I++) {
    auto *II = dyn_cast<Instruction>(VL[I]);
    if (!II)
      return false;

    if (BB != II->getParent())
      return false;
  }
  return true;
}

/// \returns True if all of the values in \p VL are constants (but not
/// globals/constant expressions).
static bool allConstant(ArrayRef<Value *> VL) {
  // Constant expressions and globals can't be vectorized like normal integer/FP
  // constants.
  return all_of(VL, isConstant);
}

/// \returns True if all of the values in \p VL are identical or some of them
/// are UndefValue.
static bool isSplat(ArrayRef<Value *> VL) {
  Value *FirstNonUndef = nullptr;
  for (Value *V : VL) {
    if (isa<UndefValue>(V))
      continue;
    if (!FirstNonUndef) {
      FirstNonUndef = V;
      continue;
    }
    if (V != FirstNonUndef)
      return false;
  }
  return FirstNonUndef != nullptr;
}

/// \returns True if \p I is commutative, handles CmpInst and BinaryOperator.
static bool isCommutative(Instruction *I) {
  if (auto *Cmp = dyn_cast<CmpInst>(I))
    return Cmp->isCommutative();
  if (auto *BO = dyn_cast<BinaryOperator>(I))
    return BO->isCommutative() ||
           (BO->getOpcode() == Instruction::Sub &&
            !BO->hasNUsesOrMore(UsesLimit) &&
            all_of(
                BO->uses(),
                [](const Use &U) {
                  // Commutative, if icmp eq/ne sub, 0
                  ICmpInst::Predicate Pred;
                  if (match(U.getUser(),
                            m_ICmp(Pred, m_Specific(U.get()), m_Zero())) &&
                      (Pred == ICmpInst::ICMP_EQ || Pred == ICmpInst::ICMP_NE))
                    return true;
                  // Commutative, if abs(sub nsw, true) or abs(sub, false).
                  ConstantInt *Flag;
                  return match(U.getUser(),
                               m_Intrinsic<Intrinsic::abs>(
                                   m_Specific(U.get()), m_ConstantInt(Flag))) &&
                         (!cast<Instruction>(U.get())->hasNoSignedWrap() ||
                          Flag->isOne());
                })) ||
           (BO->getOpcode() == Instruction::FSub &&
            !BO->hasNUsesOrMore(UsesLimit) &&
            all_of(BO->uses(), [](const Use &U) {
              return match(U.getUser(),
                           m_Intrinsic<Intrinsic::fabs>(m_Specific(U.get())));
            }));
  return I->isCommutative();
}

template <typename T>
static std::optional<unsigned> getInsertExtractIndex(const Value *Inst,
                                                     unsigned Offset) {
  static_assert(std::is_same_v<T, InsertElementInst> ||
                    std::is_same_v<T, ExtractElementInst>,
                "unsupported T");
  int Index = Offset;
  if (const auto *IE = dyn_cast<T>(Inst)) {
    const auto *VT = dyn_cast<FixedVectorType>(IE->getType());
    if (!VT)
      return std::nullopt;
    const auto *CI = dyn_cast<ConstantInt>(IE->getOperand(2));
    if (!CI)
      return std::nullopt;
    if (CI->getValue().uge(VT->getNumElements()))
      return std::nullopt;
    Index *= VT->getNumElements();
    Index += CI->getZExtValue();
    return Index;
  }
  return std::nullopt;
}

/// \returns inserting or extracting index of InsertElement, ExtractElement or
/// InsertValue instruction, using Offset as base offset for index.
/// \returns std::nullopt if the index is not an immediate.
static std::optional<unsigned> getElementIndex(const Value *Inst,
                                               unsigned Offset = 0) {
  if (auto Index = getInsertExtractIndex<InsertElementInst>(Inst, Offset))
    return Index;
  if (auto Index = getInsertExtractIndex<ExtractElementInst>(Inst, Offset))
    return Index;

  int Index = Offset;

  const auto *IV = dyn_cast<InsertValueInst>(Inst);
  if (!IV)
    return std::nullopt;

  Type *CurrentType = IV->getType();
  for (unsigned I : IV->indices()) {
    if (const auto *ST = dyn_cast<StructType>(CurrentType)) {
      Index *= ST->getNumElements();
      CurrentType = ST->getElementType(I);
    } else if (const auto *AT = dyn_cast<ArrayType>(CurrentType)) {
      Index *= AT->getNumElements();
      CurrentType = AT->getElementType();
    } else {
      return std::nullopt;
    }
    Index += I;
  }
  return Index;
}

namespace {
/// Specifies the way the mask should be analyzed for undefs/poisonous elements
/// in the shuffle mask.
enum class UseMask {
  FirstArg, ///< The mask is expected to be for permutation of 1-2 vectors,
            ///< check for the mask elements for the first argument (mask
            ///< indices are in range [0:VF)).
  SecondArg, ///< The mask is expected to be for permutation of 2 vectors, check
             ///< for the mask elements for the second argument (mask indices
             ///< are in range [VF:2*VF))
  UndefsAsMask ///< Consider undef mask elements (-1) as placeholders for
               ///< future shuffle elements and mark them as ones as being used
               ///< in future. Non-undef elements are considered as unused since
               ///< they're already marked as used in the mask.
};
} // namespace

/// Prepares a use bitset for the given mask either for the first argument or
/// for the second.
static SmallBitVector buildUseMask(int VF, ArrayRef<int> Mask,
                                   UseMask MaskArg) {
  SmallBitVector UseMask(VF, true);
  for (auto [Idx, Value] : enumerate(Mask)) {
    if (Value == PoisonMaskElem) {
      if (MaskArg == UseMask::UndefsAsMask)
        UseMask.reset(Idx);
      continue;
    }
    if (MaskArg == UseMask::FirstArg && Value < VF)
      UseMask.reset(Value);
    else if (MaskArg == UseMask::SecondArg && Value >= VF)
      UseMask.reset(Value - VF);
  }
  return UseMask;
}

/// Checks if the given value is actually an undefined constant vector.
/// Also, if the \p UseMask is not empty, tries to check if the non-masked
/// elements actually mask the insertelement buildvector, if any.
template <bool IsPoisonOnly = false>
static SmallBitVector isUndefVector(const Value *V,
                                    const SmallBitVector &UseMask = {}) {
  SmallBitVector Res(UseMask.empty() ? 1 : UseMask.size(), true);
  using T = std::conditional_t<IsPoisonOnly, PoisonValue, UndefValue>;
  if (isa<T>(V))
    return Res;
  auto *VecTy = dyn_cast<FixedVectorType>(V->getType());
  if (!VecTy)
    return Res.reset();
  auto *C = dyn_cast<Constant>(V);
  if (!C) {
    if (!UseMask.empty()) {
      const Value *Base = V;
      while (auto *II = dyn_cast<InsertElementInst>(Base)) {
        Base = II->getOperand(0);
        if (isa<T>(II->getOperand(1)))
          continue;
        std::optional<unsigned> Idx = getElementIndex(II);
        if (!Idx) {
          Res.reset();
          return Res;
        }
        if (*Idx < UseMask.size() && !UseMask.test(*Idx))
          Res.reset(*Idx);
      }
      // TODO: Add analysis for shuffles here too.
      if (V == Base) {
        Res.reset();
      } else {
        SmallBitVector SubMask(UseMask.size(), false);
        Res &= isUndefVector<IsPoisonOnly>(Base, SubMask);
      }
    } else {
      Res.reset();
    }
    return Res;
  }
  for (unsigned I = 0, E = VecTy->getNumElements(); I != E; ++I) {
    if (Constant *Elem = C->getAggregateElement(I))
      if (!isa<T>(Elem) &&
          (UseMask.empty() || (I < UseMask.size() && !UseMask.test(I))))
        Res.reset(I);
  }
  return Res;
}

/// Checks if the vector of instructions can be represented as a shuffle, like:
/// %x0 = extractelement <4 x i8> %x, i32 0
/// %x3 = extractelement <4 x i8> %x, i32 3
/// %y1 = extractelement <4 x i8> %y, i32 1
/// %y2 = extractelement <4 x i8> %y, i32 2
/// %x0x0 = mul i8 %x0, %x0
/// %x3x3 = mul i8 %x3, %x3
/// %y1y1 = mul i8 %y1, %y1
/// %y2y2 = mul i8 %y2, %y2
/// %ins1 = insertelement <4 x i8> poison, i8 %x0x0, i32 0
/// %ins2 = insertelement <4 x i8> %ins1, i8 %x3x3, i32 1
/// %ins3 = insertelement <4 x i8> %ins2, i8 %y1y1, i32 2
/// %ins4 = insertelement <4 x i8> %ins3, i8 %y2y2, i32 3
/// ret <4 x i8> %ins4
/// can be transformed into:
/// %1 = shufflevector <4 x i8> %x, <4 x i8> %y, <4 x i32> <i32 0, i32 3, i32 5,
///                                                         i32 6>
/// %2 = mul <4 x i8> %1, %1
/// ret <4 x i8> %2
/// Mask will return the Shuffle Mask equivalent to the extracted elements.
/// TODO: Can we split off and reuse the shuffle mask detection from
/// ShuffleVectorInst/getShuffleCost?
static std::optional<TargetTransformInfo::ShuffleKind>
isFixedVectorShuffle(ArrayRef<Value *> VL, SmallVectorImpl<int> &Mask) {
  const auto *It = find_if(VL, IsaPred<ExtractElementInst>);
  if (It == VL.end())
    return std::nullopt;
  unsigned Size =
      std::accumulate(VL.begin(), VL.end(), 0u, [](unsigned S, Value *V) {
        auto *EI = dyn_cast<ExtractElementInst>(V);
        if (!EI)
          return S;
        auto *VTy = dyn_cast<FixedVectorType>(EI->getVectorOperandType());
        if (!VTy)
          return S;
        return std::max(S, VTy->getNumElements());
      });

  Value *Vec1 = nullptr;
  Value *Vec2 = nullptr;
  bool HasNonUndefVec = any_of(VL, [](Value *V) {
    auto *EE = dyn_cast<ExtractElementInst>(V);
    if (!EE)
      return false;
    Value *Vec = EE->getVectorOperand();
    if (isa<UndefValue>(Vec))
      return false;
    return isGuaranteedNotToBePoison(Vec);
  });
  enum ShuffleMode { Unknown, Select, Permute };
  ShuffleMode CommonShuffleMode = Unknown;
  Mask.assign(VL.size(), PoisonMaskElem);
  for (unsigned I = 0, E = VL.size(); I < E; ++I) {
    // Undef can be represented as an undef element in a vector.
    if (isa<UndefValue>(VL[I]))
      continue;
    auto *EI = cast<ExtractElementInst>(VL[I]);
    if (isa<ScalableVectorType>(EI->getVectorOperandType()))
      return std::nullopt;
    auto *Vec = EI->getVectorOperand();
    // We can extractelement from undef or poison vector.
    if (isUndefVector</*isPoisonOnly=*/true>(Vec).all())
      continue;
    // All vector operands must have the same number of vector elements.
    if (isa<UndefValue>(Vec)) {
      Mask[I] = I;
    } else {
      if (isa<UndefValue>(EI->getIndexOperand()))
        continue;
      auto *Idx = dyn_cast<ConstantInt>(EI->getIndexOperand());
      if (!Idx)
        return std::nullopt;
      // Undefined behavior if Idx is negative or >= Size.
      if (Idx->getValue().uge(Size))
        continue;
      unsigned IntIdx = Idx->getValue().getZExtValue();
      Mask[I] = IntIdx;
    }
    if (isUndefVector(Vec).all() && HasNonUndefVec)
      continue;
    // For correct shuffling we have to have at most 2 different vector operands
    // in all extractelement instructions.
    if (!Vec1 || Vec1 == Vec) {
      Vec1 = Vec;
    } else if (!Vec2 || Vec2 == Vec) {
      Vec2 = Vec;
      Mask[I] += Size;
    } else {
      return std::nullopt;
    }
    if (CommonShuffleMode == Permute)
      continue;
    // If the extract index is not the same as the operation number, it is a
    // permutation.
    if (Mask[I] % Size != I) {
      CommonShuffleMode = Permute;
      continue;
    }
    CommonShuffleMode = Select;
  }
  // If we're not crossing lanes in different vectors, consider it as blending.
  if (CommonShuffleMode == Select && Vec2)
    return TargetTransformInfo::SK_Select;
  // If Vec2 was never used, we have a permutation of a single vector, otherwise
  // we have permutation of 2 vectors.
  return Vec2 ? TargetTransformInfo::SK_PermuteTwoSrc
              : TargetTransformInfo::SK_PermuteSingleSrc;
}

/// \returns True if Extract{Value,Element} instruction extracts element Idx.
static std::optional<unsigned> getExtractIndex(Instruction *E) {
  unsigned Opcode = E->getOpcode();
  assert((Opcode == Instruction::ExtractElement ||
          Opcode == Instruction::ExtractValue) &&
         "Expected extractelement or extractvalue instruction.");
  if (Opcode == Instruction::ExtractElement) {
    auto *CI = dyn_cast<ConstantInt>(E->getOperand(1));
    if (!CI)
      return std::nullopt;
    return CI->getZExtValue();
  }
  auto *EI = cast<ExtractValueInst>(E);
  if (EI->getNumIndices() != 1)
    return std::nullopt;
  return *EI->idx_begin();
}

namespace {

/// Main data required for vectorization of instructions.
struct InstructionsState {
  /// The very first instruction in the list with the main opcode.
  Value *OpValue = nullptr;

  /// The main/alternate instruction.
  Instruction *MainOp = nullptr;
  Instruction *AltOp = nullptr;

  /// The main/alternate opcodes for the list of instructions.
  unsigned getOpcode() const {
    return MainOp ? MainOp->getOpcode() : 0;
  }

  unsigned getAltOpcode() const {
    return AltOp ? AltOp->getOpcode() : 0;
  }

  /// Some of the instructions in the list have alternate opcodes.
  bool isAltShuffle() const { return AltOp != MainOp; }

  bool isOpcodeOrAlt(Instruction *I) const {
    unsigned CheckedOpcode = I->getOpcode();
    return getOpcode() == CheckedOpcode || getAltOpcode() == CheckedOpcode;
  }

  InstructionsState() = delete;
  InstructionsState(Value *OpValue, Instruction *MainOp, Instruction *AltOp)
      : OpValue(OpValue), MainOp(MainOp), AltOp(AltOp) {}
};

} // end anonymous namespace

/// \returns true if \p Opcode is allowed as part of the main/alternate
/// instruction for SLP vectorization.
///
/// Example of unsupported opcode is SDIV that can potentially cause UB if the
/// "shuffled out" lane would result in division by zero.
static bool isValidForAlternation(unsigned Opcode) {
  if (Instruction::isIntDivRem(Opcode))
    return false;

  return true;
}

static InstructionsState getSameOpcode(ArrayRef<Value *> VL,
                                       const TargetLibraryInfo &TLI,
                                       unsigned BaseIndex = 0);

/// Checks if the provided operands of 2 cmp instructions are compatible, i.e.
/// compatible instructions or constants, or just some other regular values.
static bool areCompatibleCmpOps(Value *BaseOp0, Value *BaseOp1, Value *Op0,
                                Value *Op1, const TargetLibraryInfo &TLI) {
  return (isConstant(BaseOp0) && isConstant(Op0)) ||
         (isConstant(BaseOp1) && isConstant(Op1)) ||
         (!isa<Instruction>(BaseOp0) && !isa<Instruction>(Op0) &&
          !isa<Instruction>(BaseOp1) && !isa<Instruction>(Op1)) ||
         BaseOp0 == Op0 || BaseOp1 == Op1 ||
         getSameOpcode({BaseOp0, Op0}, TLI).getOpcode() ||
         getSameOpcode({BaseOp1, Op1}, TLI).getOpcode();
}

/// \returns true if a compare instruction \p CI has similar "look" and
/// same predicate as \p BaseCI, "as is" or with its operands and predicate
/// swapped, false otherwise.
static bool isCmpSameOrSwapped(const CmpInst *BaseCI, const CmpInst *CI,
                               const TargetLibraryInfo &TLI) {
  assert(BaseCI->getOperand(0)->getType() == CI->getOperand(0)->getType() &&
         "Assessing comparisons of different types?");
  CmpInst::Predicate BasePred = BaseCI->getPredicate();
  CmpInst::Predicate Pred = CI->getPredicate();
  CmpInst::Predicate SwappedPred = CmpInst::getSwappedPredicate(Pred);

  Value *BaseOp0 = BaseCI->getOperand(0);
  Value *BaseOp1 = BaseCI->getOperand(1);
  Value *Op0 = CI->getOperand(0);
  Value *Op1 = CI->getOperand(1);

  return (BasePred == Pred &&
          areCompatibleCmpOps(BaseOp0, BaseOp1, Op0, Op1, TLI)) ||
         (BasePred == SwappedPred &&
          areCompatibleCmpOps(BaseOp0, BaseOp1, Op1, Op0, TLI));
}

/// \returns analysis of the Instructions in \p VL described in
/// InstructionsState, the Opcode that we suppose the whole list
/// could be vectorized even if its structure is diverse.
static InstructionsState getSameOpcode(ArrayRef<Value *> VL,
                                       const TargetLibraryInfo &TLI,
                                       unsigned BaseIndex) {
  // Make sure these are all Instructions.
  if (llvm::any_of(VL, [](Value *V) { return !isa<Instruction>(V); }))
    return InstructionsState(VL[BaseIndex], nullptr, nullptr);

  bool IsCastOp = isa<CastInst>(VL[BaseIndex]);
  bool IsBinOp = isa<BinaryOperator>(VL[BaseIndex]);
  bool IsCmpOp = isa<CmpInst>(VL[BaseIndex]);
  CmpInst::Predicate BasePred =
      IsCmpOp ? cast<CmpInst>(VL[BaseIndex])->getPredicate()
              : CmpInst::BAD_ICMP_PREDICATE;
  unsigned Opcode = cast<Instruction>(VL[BaseIndex])->getOpcode();
  unsigned AltOpcode = Opcode;
  unsigned AltIndex = BaseIndex;

  bool SwappedPredsCompatible = [&]() {
    if (!IsCmpOp)
      return false;
    SetVector<unsigned> UniquePreds, UniqueNonSwappedPreds;
    UniquePreds.insert(BasePred);
    UniqueNonSwappedPreds.insert(BasePred);
    for (Value *V : VL) {
      auto *I = dyn_cast<CmpInst>(V);
      if (!I)
        return false;
      CmpInst::Predicate CurrentPred = I->getPredicate();
      CmpInst::Predicate SwappedCurrentPred =
          CmpInst::getSwappedPredicate(CurrentPred);
      UniqueNonSwappedPreds.insert(CurrentPred);
      if (!UniquePreds.contains(CurrentPred) &&
          !UniquePreds.contains(SwappedCurrentPred))
        UniquePreds.insert(CurrentPred);
    }
    // Total number of predicates > 2, but if consider swapped predicates
    // compatible only 2, consider swappable predicates as compatible opcodes,
    // not alternate.
    return UniqueNonSwappedPreds.size() > 2 && UniquePreds.size() == 2;
  }();
  // Check for one alternate opcode from another BinaryOperator.
  // TODO - generalize to support all operators (types, calls etc.).
  auto *IBase = cast<Instruction>(VL[BaseIndex]);
  Intrinsic::ID BaseID = 0;
  SmallVector<VFInfo> BaseMappings;
  if (auto *CallBase = dyn_cast<CallInst>(IBase)) {
    BaseID = getVectorIntrinsicIDForCall(CallBase, &TLI);
    BaseMappings = VFDatabase(*CallBase).getMappings(*CallBase);
    if (!isTriviallyVectorizable(BaseID) && BaseMappings.empty())
      return InstructionsState(VL[BaseIndex], nullptr, nullptr);
  }
  for (int Cnt = 0, E = VL.size(); Cnt < E; Cnt++) {
    auto *I = cast<Instruction>(VL[Cnt]);
    unsigned InstOpcode = I->getOpcode();
    if (IsBinOp && isa<BinaryOperator>(I)) {
      if (InstOpcode == Opcode || InstOpcode == AltOpcode)
        continue;
      if (Opcode == AltOpcode && isValidForAlternation(InstOpcode) &&
          isValidForAlternation(Opcode)) {
        AltOpcode = InstOpcode;
        AltIndex = Cnt;
        continue;
      }
    } else if (IsCastOp && isa<CastInst>(I)) {
      Value *Op0 = IBase->getOperand(0);
      Type *Ty0 = Op0->getType();
      Value *Op1 = I->getOperand(0);
      Type *Ty1 = Op1->getType();
      if (Ty0 == Ty1) {
        if (InstOpcode == Opcode || InstOpcode == AltOpcode)
          continue;
        if (Opcode == AltOpcode) {
          assert(isValidForAlternation(Opcode) &&
                 isValidForAlternation(InstOpcode) &&
                 "Cast isn't safe for alternation, logic needs to be updated!");
          AltOpcode = InstOpcode;
          AltIndex = Cnt;
          continue;
        }
      }
    } else if (auto *Inst = dyn_cast<CmpInst>(VL[Cnt]); Inst && IsCmpOp) {
      auto *BaseInst = cast<CmpInst>(VL[BaseIndex]);
      Type *Ty0 = BaseInst->getOperand(0)->getType();
      Type *Ty1 = Inst->getOperand(0)->getType();
      if (Ty0 == Ty1) {
        assert(InstOpcode == Opcode && "Expected same CmpInst opcode.");
        // Check for compatible operands. If the corresponding operands are not
        // compatible - need to perform alternate vectorization.
        CmpInst::Predicate CurrentPred = Inst->getPredicate();
        CmpInst::Predicate SwappedCurrentPred =
            CmpInst::getSwappedPredicate(CurrentPred);

        if ((E == 2 || SwappedPredsCompatible) &&
            (BasePred == CurrentPred || BasePred == SwappedCurrentPred))
          continue;

        if (isCmpSameOrSwapped(BaseInst, Inst, TLI))
          continue;
        auto *AltInst = cast<CmpInst>(VL[AltIndex]);
        if (AltIndex != BaseIndex) {
          if (isCmpSameOrSwapped(AltInst, Inst, TLI))
            continue;
        } else if (BasePred != CurrentPred) {
          assert(
              isValidForAlternation(InstOpcode) &&
              "CmpInst isn't safe for alternation, logic needs to be updated!");
          AltIndex = Cnt;
          continue;
        }
        CmpInst::Predicate AltPred = AltInst->getPredicate();
        if (BasePred == CurrentPred || BasePred == SwappedCurrentPred ||
            AltPred == CurrentPred || AltPred == SwappedCurrentPred)
          continue;
      }
    } else if (InstOpcode == Opcode || InstOpcode == AltOpcode) {
      if (auto *Gep = dyn_cast<GetElementPtrInst>(I)) {
        if (Gep->getNumOperands() != 2 ||
            Gep->getOperand(0)->getType() != IBase->getOperand(0)->getType())
          return InstructionsState(VL[BaseIndex], nullptr, nullptr);
      } else if (auto *EI = dyn_cast<ExtractElementInst>(I)) {
        if (!isVectorLikeInstWithConstOps(EI))
          return InstructionsState(VL[BaseIndex], nullptr, nullptr);
      } else if (auto *LI = dyn_cast<LoadInst>(I)) {
        auto *BaseLI = cast<LoadInst>(IBase);
        if (!LI->isSimple() || !BaseLI->isSimple())
          return InstructionsState(VL[BaseIndex], nullptr, nullptr);
      } else if (auto *Call = dyn_cast<CallInst>(I)) {
        auto *CallBase = cast<CallInst>(IBase);
        if (Call->getCalledFunction() != CallBase->getCalledFunction())
          return InstructionsState(VL[BaseIndex], nullptr, nullptr);
        if (Call->hasOperandBundles() && (!CallBase->hasOperandBundles() ||
            !std::equal(Call->op_begin() + Call->getBundleOperandsStartIndex(),
                        Call->op_begin() + Call->getBundleOperandsEndIndex(),
                        CallBase->op_begin() +
                            CallBase->getBundleOperandsStartIndex())))
          return InstructionsState(VL[BaseIndex], nullptr, nullptr);
        Intrinsic::ID ID = getVectorIntrinsicIDForCall(Call, &TLI);
        if (ID != BaseID)
          return InstructionsState(VL[BaseIndex], nullptr, nullptr);
        if (!ID) {
          SmallVector<VFInfo> Mappings = VFDatabase(*Call).getMappings(*Call);
          if (Mappings.size() != BaseMappings.size() ||
              Mappings.front().ISA != BaseMappings.front().ISA ||
              Mappings.front().ScalarName != BaseMappings.front().ScalarName ||
              Mappings.front().VectorName != BaseMappings.front().VectorName ||
              Mappings.front().Shape.VF != BaseMappings.front().Shape.VF ||
              Mappings.front().Shape.Parameters !=
                  BaseMappings.front().Shape.Parameters)
            return InstructionsState(VL[BaseIndex], nullptr, nullptr);
        }
      }
      continue;
    }
    return InstructionsState(VL[BaseIndex], nullptr, nullptr);
  }

  return InstructionsState(VL[BaseIndex], cast<Instruction>(VL[BaseIndex]),
                           cast<Instruction>(VL[AltIndex]));
}

/// \returns true if all of the values in \p VL have the same type or false
/// otherwise.
static bool allSameType(ArrayRef<Value *> VL) {
  Type *Ty = VL.front()->getType();
  return all_of(VL.drop_front(), [&](Value *V) { return V->getType() == Ty; });
}

/// \returns True if in-tree use also needs extract. This refers to
/// possible scalar operand in vectorized instruction.
static bool doesInTreeUserNeedToExtract(Value *Scalar, Instruction *UserInst,
                                        TargetLibraryInfo *TLI) {
  if (!UserInst)
    return false;
  unsigned Opcode = UserInst->getOpcode();
  switch (Opcode) {
  case Instruction::Load: {
    LoadInst *LI = cast<LoadInst>(UserInst);
    return (LI->getPointerOperand() == Scalar);
  }
  case Instruction::Store: {
    StoreInst *SI = cast<StoreInst>(UserInst);
    return (SI->getPointerOperand() == Scalar);
  }
  case Instruction::Call: {
    CallInst *CI = cast<CallInst>(UserInst);
    Intrinsic::ID ID = getVectorIntrinsicIDForCall(CI, TLI);
    return any_of(enumerate(CI->args()), [&](auto &&Arg) {
      return isVectorIntrinsicWithScalarOpAtArg(ID, Arg.index()) &&
             Arg.value().get() == Scalar;
    });
  }
  default:
    return false;
  }
}

/// \returns the AA location that is being access by the instruction.
static MemoryLocation getLocation(Instruction *I) {
  if (StoreInst *SI = dyn_cast<StoreInst>(I))
    return MemoryLocation::get(SI);
  if (LoadInst *LI = dyn_cast<LoadInst>(I))
    return MemoryLocation::get(LI);
  return MemoryLocation();
}

/// \returns True if the instruction is not a volatile or atomic load/store.
static bool isSimple(Instruction *I) {
  if (LoadInst *LI = dyn_cast<LoadInst>(I))
    return LI->isSimple();
  if (StoreInst *SI = dyn_cast<StoreInst>(I))
    return SI->isSimple();
  if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(I))
    return !MI->isVolatile();
  return true;
}

/// Shuffles \p Mask in accordance with the given \p SubMask.
/// \param ExtendingManyInputs Supports reshuffling of the mask with not only
/// one but two input vectors.
static void addMask(SmallVectorImpl<int> &Mask, ArrayRef<int> SubMask,
                    bool ExtendingManyInputs = false) {
  if (SubMask.empty())
    return;
  assert(
      (!ExtendingManyInputs || SubMask.size() > Mask.size() ||
       // Check if input scalars were extended to match the size of other node.
       (SubMask.size() == Mask.size() &&
        std::all_of(std::next(Mask.begin(), Mask.size() / 2), Mask.end(),
                    [](int Idx) { return Idx == PoisonMaskElem; }))) &&
      "SubMask with many inputs support must be larger than the mask.");
  if (Mask.empty()) {
    Mask.append(SubMask.begin(), SubMask.end());
    return;
  }
  SmallVector<int> NewMask(SubMask.size(), PoisonMaskElem);
  int TermValue = std::min(Mask.size(), SubMask.size());
  for (int I = 0, E = SubMask.size(); I < E; ++I) {
    if (SubMask[I] == PoisonMaskElem ||
        (!ExtendingManyInputs &&
         (SubMask[I] >= TermValue || Mask[SubMask[I]] >= TermValue)))
      continue;
    NewMask[I] = Mask[SubMask[I]];
  }
  Mask.swap(NewMask);
}

/// Order may have elements assigned special value (size) which is out of
/// bounds. Such indices only appear on places which correspond to undef values
/// (see canReuseExtract for details) and used in order to avoid undef values
/// have effect on operands ordering.
/// The first loop below simply finds all unused indices and then the next loop
/// nest assigns these indices for undef values positions.
/// As an example below Order has two undef positions and they have assigned
/// values 3 and 7 respectively:
/// before:  6 9 5 4 9 2 1 0
/// after:   6 3 5 4 7 2 1 0
static void fixupOrderingIndices(MutableArrayRef<unsigned> Order) {
  const unsigned Sz = Order.size();
  SmallBitVector UnusedIndices(Sz, /*t=*/true);
  SmallBitVector MaskedIndices(Sz);
  for (unsigned I = 0; I < Sz; ++I) {
    if (Order[I] < Sz)
      UnusedIndices.reset(Order[I]);
    else
      MaskedIndices.set(I);
  }
  if (MaskedIndices.none())
    return;
  assert(UnusedIndices.count() == MaskedIndices.count() &&
         "Non-synced masked/available indices.");
  int Idx = UnusedIndices.find_first();
  int MIdx = MaskedIndices.find_first();
  while (MIdx >= 0) {
    assert(Idx >= 0 && "Indices must be synced.");
    Order[MIdx] = Idx;
    Idx = UnusedIndices.find_next(Idx);
    MIdx = MaskedIndices.find_next(MIdx);
  }
}

/// \returns a bitset for selecting opcodes. false for Opcode0 and true for
/// Opcode1.
SmallBitVector getAltInstrMask(ArrayRef<Value *> VL, unsigned Opcode0,
                               unsigned Opcode1) {
  Type *ScalarTy = VL[0]->getType();
  unsigned ScalarTyNumElements = getNumElements(ScalarTy);
  SmallBitVector OpcodeMask(VL.size() * ScalarTyNumElements, false);
  for (unsigned Lane : seq<unsigned>(VL.size()))
    if (cast<Instruction>(VL[Lane])->getOpcode() == Opcode1)
      OpcodeMask.set(Lane * ScalarTyNumElements,
                     Lane * ScalarTyNumElements + ScalarTyNumElements);
  return OpcodeMask;
}

namespace llvm {

static void inversePermutation(ArrayRef<unsigned> Indices,
                               SmallVectorImpl<int> &Mask) {
  Mask.clear();
  const unsigned E = Indices.size();
  Mask.resize(E, PoisonMaskElem);
  for (unsigned I = 0; I < E; ++I)
    Mask[Indices[I]] = I;
}

/// Reorders the list of scalars in accordance with the given \p Mask.
static void reorderScalars(SmallVectorImpl<Value *> &Scalars,
                           ArrayRef<int> Mask) {
  assert(!Mask.empty() && "Expected non-empty mask.");
  SmallVector<Value *> Prev(Scalars.size(),
                            PoisonValue::get(Scalars.front()->getType()));
  Prev.swap(Scalars);
  for (unsigned I = 0, E = Prev.size(); I < E; ++I)
    if (Mask[I] != PoisonMaskElem)
      Scalars[Mask[I]] = Prev[I];
}

/// Checks if the provided value does not require scheduling. It does not
/// require scheduling if this is not an instruction or it is an instruction
/// that does not read/write memory and all operands are either not instructions
/// or phi nodes or instructions from different blocks.
static bool areAllOperandsNonInsts(Value *V) {
  auto *I = dyn_cast<Instruction>(V);
  if (!I)
    return true;
  return !mayHaveNonDefUseDependency(*I) &&
    all_of(I->operands(), [I](Value *V) {
      auto *IO = dyn_cast<Instruction>(V);
      if (!IO)
        return true;
      return isa<PHINode>(IO) || IO->getParent() != I->getParent();
    });
}

/// Checks if the provided value does not require scheduling. It does not
/// require scheduling if this is not an instruction or it is an instruction
/// that does not read/write memory and all users are phi nodes or instructions
/// from the different blocks.
static bool isUsedOutsideBlock(Value *V) {
  auto *I = dyn_cast<Instruction>(V);
  if (!I)
    return true;
  // Limits the number of uses to save compile time.
  return !I->mayReadOrWriteMemory() && !I->hasNUsesOrMore(UsesLimit) &&
         all_of(I->users(), [I](User *U) {
           auto *IU = dyn_cast<Instruction>(U);
           if (!IU)
             return true;
           return IU->getParent() != I->getParent() || isa<PHINode>(IU);
         });
}

/// Checks if the specified value does not require scheduling. It does not
/// require scheduling if all operands and all users do not need to be scheduled
/// in the current basic block.
static bool doesNotNeedToBeScheduled(Value *V) {
  return areAllOperandsNonInsts(V) && isUsedOutsideBlock(V);
}

/// Checks if the specified array of instructions does not require scheduling.
/// It is so if all either instructions have operands that do not require
/// scheduling or their users do not require scheduling since they are phis or
/// in other basic blocks.
static bool doesNotNeedToSchedule(ArrayRef<Value *> VL) {
  return !VL.empty() &&
         (all_of(VL, isUsedOutsideBlock) || all_of(VL, areAllOperandsNonInsts));
}

namespace slpvectorizer {

/// Bottom Up SLP Vectorizer.
class BoUpSLP {
  struct TreeEntry;
  struct ScheduleData;
  class ShuffleCostEstimator;
  class ShuffleInstructionBuilder;

public:
  /// Tracks the state we can represent the loads in the given sequence.
  enum class LoadsState {
    Gather,
    Vectorize,
    ScatterVectorize,
    StridedVectorize
  };

  using ValueList = SmallVector<Value *, 8>;
  using InstrList = SmallVector<Instruction *, 16>;
  using ValueSet = SmallPtrSet<Value *, 16>;
  using StoreList = SmallVector<StoreInst *, 8>;
  using ExtraValueToDebugLocsMap =
      MapVector<Value *, SmallVector<Instruction *, 2>>;
  using OrdersType = SmallVector<unsigned, 4>;

  BoUpSLP(Function *Func, ScalarEvolution *Se, TargetTransformInfo *Tti,
          TargetLibraryInfo *TLi, AAResults *Aa, LoopInfo *Li,
          DominatorTree *Dt, AssumptionCache *AC, DemandedBits *DB,
          const DataLayout *DL, OptimizationRemarkEmitter *ORE)
      : BatchAA(*Aa), F(Func), SE(Se), TTI(Tti), TLI(TLi), LI(Li), DT(Dt),
        AC(AC), DB(DB), DL(DL), ORE(ORE),
        Builder(Se->getContext(), TargetFolder(*DL)) {
    CodeMetrics::collectEphemeralValues(F, AC, EphValues);
    // Use the vector register size specified by the target unless overridden
    // by a command-line option.
    // TODO: It would be better to limit the vectorization factor based on
    //       data type rather than just register size. For example, x86 AVX has
    //       256-bit registers, but it does not support integer operations
    //       at that width (that requires AVX2).
    if (MaxVectorRegSizeOption.getNumOccurrences())
      MaxVecRegSize = MaxVectorRegSizeOption;
    else
      MaxVecRegSize =
          TTI->getRegisterBitWidth(TargetTransformInfo::RGK_FixedWidthVector)
              .getFixedValue();

    if (MinVectorRegSizeOption.getNumOccurrences())
      MinVecRegSize = MinVectorRegSizeOption;
    else
      MinVecRegSize = TTI->getMinVectorRegisterBitWidth();
  }

  /// Vectorize the tree that starts with the elements in \p VL.
  /// Returns the vectorized root.
  Value *vectorizeTree();

  /// Vectorize the tree but with the list of externally used values \p
  /// ExternallyUsedValues. Values in this MapVector can be replaced but the
  /// generated extractvalue instructions.
  Value *
  vectorizeTree(const ExtraValueToDebugLocsMap &ExternallyUsedValues,
                Instruction *ReductionRoot = nullptr);

  /// \returns the cost incurred by unwanted spills and fills, caused by
  /// holding live values over call sites.
  InstructionCost getSpillCost() const;

  /// \returns the vectorization cost of the subtree that starts at \p VL.
  /// A negative number means that this is profitable.
  InstructionCost getTreeCost(ArrayRef<Value *> VectorizedVals = {});

  /// Construct a vectorizable tree that starts at \p Roots, ignoring users for
  /// the purpose of scheduling and extraction in the \p UserIgnoreLst.
  void buildTree(ArrayRef<Value *> Roots,
                 const SmallDenseSet<Value *> &UserIgnoreLst);

  /// Construct a vectorizable tree that starts at \p Roots.
  void buildTree(ArrayRef<Value *> Roots);

  /// Returns whether the root node has in-tree uses.
  bool doesRootHaveInTreeUses() const {
    return !VectorizableTree.empty() &&
           !VectorizableTree.front()->UserTreeIndices.empty();
  }

  /// Return the scalars of the root node.
  ArrayRef<Value *> getRootNodeScalars() const {
    assert(!VectorizableTree.empty() && "No graph to get the first node from");
    return VectorizableTree.front()->Scalars;
  }

  /// Checks if the root graph node can be emitted with narrower bitwidth at
  /// codegen and returns it signedness, if so.
  bool isSignedMinBitwidthRootNode() const {
    return MinBWs.at(VectorizableTree.front().get()).second;
  }

  /// Builds external uses of the vectorized scalars, i.e. the list of
  /// vectorized scalars to be extracted, their lanes and their scalar users. \p
  /// ExternallyUsedValues contains additional list of external uses to handle
  /// vectorization of reductions.
  void
  buildExternalUses(const ExtraValueToDebugLocsMap &ExternallyUsedValues = {});

  /// Transforms graph nodes to target specific representations, if profitable.
  void transformNodes();

  /// Clear the internal data structures that are created by 'buildTree'.
  void deleteTree() {
    VectorizableTree.clear();
    ScalarToTreeEntry.clear();
    MultiNodeScalars.clear();
    MustGather.clear();
    NonScheduledFirst.clear();
    EntryToLastInstruction.clear();
    GatheredLoadsEntriesFirst = NoGatheredLoads;
    ExternalUses.clear();
    ExternalUsesAsOriginalScalar.clear();
    for (auto &Iter : BlocksSchedules) {
      BlockScheduling *BS = Iter.second.get();
      BS->clear();
    }
    MinBWs.clear();
    ReductionBitWidth = 0;
    CastMaxMinBWSizes.reset();
    ExtraBitWidthNodes.clear();
    InstrElementSize.clear();
    UserIgnoreList = nullptr;
    PostponedGathers.clear();
    ValueToGatherNodes.clear();
  }

  unsigned getTreeSize() const {
    return GatheredLoadsEntriesFirst == NoGatheredLoads
               ? VectorizableTree.size()
               : GatheredLoadsEntriesFirst;
  }

  /// Perform LICM and CSE on the newly generated gather sequences.
  void optimizeGatherSequence();

  /// Does this non-empty order represent an identity order?  Identity
  /// should be represented as an empty order, so this is used to
  /// decide if we can canonicalize a computed order.  Undef elements
  /// (represented as size) are ignored.
  bool isIdentityOrder(ArrayRef<unsigned> Order) const {
    assert(!Order.empty() && "expected non-empty order");
    const unsigned Sz = Order.size();
    return all_of(enumerate(Order), [&](const auto &P) {
      return P.value() == P.index() || P.value() == Sz;
    });
  }

  /// Checks if the specified gather tree entry \p TE can be represented as a
  /// shuffled vector entry + (possibly) permutation with other gathers. It
  /// implements the checks only for possibly ordered scalars (Loads,
  /// ExtractElement, ExtractValue), which can be part of the graph.
  std::optional<OrdersType> findReusedOrderedScalars(const TreeEntry &TE);

  /// Sort loads into increasing pointers offsets to allow greater clustering.
  std::optional<OrdersType> findPartiallyOrderedLoads(const TreeEntry &TE);

  /// Gets reordering data for the given tree entry. If the entry is vectorized
  /// - just return ReorderIndices, otherwise check if the scalars can be
  /// reordered and return the most optimal order.
  /// \return std::nullopt if ordering is not important, empty order, if
  /// identity order is important, or the actual order.
  /// \param TopToBottom If true, include the order of vectorized stores and
  /// insertelement nodes, otherwise skip them.
  std::optional<OrdersType> getReorderingData(const TreeEntry &TE,
                                              bool TopToBottom);

  /// Reorders the current graph to the most profitable order starting from the
  /// root node to the leaf nodes. The best order is chosen only from the nodes
  /// of the same size (vectorization factor). Smaller nodes are considered
  /// parts of subgraph with smaller VF and they are reordered independently. We
  /// can make it because we still need to extend smaller nodes to the wider VF
  /// and we can merge reordering shuffles with the widening shuffles.
  void reorderTopToBottom();

  /// Reorders the current graph to the most profitable order starting from
  /// leaves to the root. It allows to rotate small subgraphs and reduce the
  /// number of reshuffles if the leaf nodes use the same order. In this case we
  /// can merge the orders and just shuffle user node instead of shuffling its
  /// operands. Plus, even the leaf nodes have different orders, it allows to
  /// sink reordering in the graph closer to the root node and merge it later
  /// during analysis.
  void reorderBottomToTop(bool IgnoreReorder = false);

  /// \return The vector element size in bits to use when vectorizing the
  /// expression tree ending at \p V. If V is a store, the size is the width of
  /// the stored value. Otherwise, the size is the width of the largest loaded
  /// value reaching V. This method is used by the vectorizer to calculate
  /// vectorization factors.
  unsigned getVectorElementSize(Value *V);

  /// Compute the minimum type sizes required to represent the entries in a
  /// vectorizable tree.
  void computeMinimumValueSizes();

  // \returns maximum vector register size as set by TTI or overridden by cl::opt.
  unsigned getMaxVecRegSize() const {
    return MaxVecRegSize;
  }

  // \returns minimum vector register size as set by cl::opt.
  unsigned getMinVecRegSize() const {
    return MinVecRegSize;
  }

  unsigned getMinVF(unsigned Sz) const {
    return std::max(2U, getMinVecRegSize() / Sz);
  }

  unsigned getMaximumVF(unsigned ElemWidth, unsigned Opcode) const {
    unsigned MaxVF = MaxVFOption.getNumOccurrences() ?
      MaxVFOption : TTI->getMaximumVF(ElemWidth, Opcode);
    return MaxVF ? MaxVF : UINT_MAX;
  }

  /// Check if homogeneous aggregate is isomorphic to some VectorType.
  /// Accepts homogeneous multidimensional aggregate of scalars/vectors like
  /// {[4 x i16], [4 x i16]}, { <2 x float>, <2 x float> },
  /// {{{i16, i16}, {i16, i16}}, {{i16, i16}, {i16, i16}}} and so on.
  ///
  /// \returns number of elements in vector if isomorphism exists, 0 otherwise.
  unsigned canMapToVector(Type *T) const;

  /// \returns True if the VectorizableTree is both tiny and not fully
  /// vectorizable. We do not vectorize such trees.
  bool isTreeTinyAndNotFullyVectorizable(bool ForReduction = false) const;

  /// Assume that a legal-sized 'or'-reduction of shifted/zexted loaded values
  /// can be load combined in the backend. Load combining may not be allowed in
  /// the IR optimizer, so we do not want to alter the pattern. For example,
  /// partially transforming a scalar bswap() pattern into vector code is
  /// effectively impossible for the backend to undo.
  /// TODO: If load combining is allowed in the IR optimizer, this analysis
  ///       may not be necessary.
  bool isLoadCombineReductionCandidate(RecurKind RdxKind) const;

  /// Assume that a vector of stores of bitwise-or/shifted/zexted loaded values
  /// can be load combined in the backend. Load combining may not be allowed in
  /// the IR optimizer, so we do not want to alter the pattern. For example,
  /// partially transforming a scalar bswap() pattern into vector code is
  /// effectively impossible for the backend to undo.
  /// TODO: If load combining is allowed in the IR optimizer, this analysis
  ///       may not be necessary.
  bool isLoadCombineCandidate(ArrayRef<Value *> Stores) const;

  /// Checks if the given array of loads can be represented as a vectorized,
  /// scatter or just simple gather.
  /// \param VL list of loads.
  /// \param VL0 main load value.
  /// \param Order returned order of load instructions.
  /// \param PointerOps returned list of pointer operands.
  /// \param BestVF return best vector factor, if recursive check found better
  /// vectorization sequences rather than masked gather.
  /// \param TryRecursiveCheck used to check if long masked gather can be
  /// represented as a serie of loads/insert subvector, if profitable.
  LoadsState canVectorizeLoads(ArrayRef<Value *> VL, const Value *VL0,
                               SmallVectorImpl<unsigned> &Order,
                               SmallVectorImpl<Value *> &PointerOps,
                               unsigned *BestVF = nullptr,
                               bool TryRecursiveCheck = true) const;

  /// Registers non-vectorizable sequence of loads
  template <typename T> void registerNonVectorizableLoads(ArrayRef<T *> VL) {
    ListOfKnonwnNonVectorizableLoads.insert(hash_value(VL));
  }

  /// Checks if the given loads sequence is known as not vectorizable
  template <typename T>
  bool areKnownNonVectorizableLoads(ArrayRef<T *> VL) const {
    return ListOfKnonwnNonVectorizableLoads.contains(hash_value(VL));
  }

  OptimizationRemarkEmitter *getORE() { return ORE; }

  /// This structure holds any data we need about the edges being traversed
  /// during buildTree_rec(). We keep track of:
  /// (i) the user TreeEntry index, and
  /// (ii) the index of the edge.
  struct EdgeInfo {
    EdgeInfo() = default;
    EdgeInfo(TreeEntry *UserTE, unsigned EdgeIdx)
        : UserTE(UserTE), EdgeIdx(EdgeIdx) {}
    /// The user TreeEntry.
    TreeEntry *UserTE = nullptr;
    /// The operand index of the use.
    unsigned EdgeIdx = UINT_MAX;
#ifndef NDEBUG
    friend inline raw_ostream &operator<<(raw_ostream &OS,
                                          const BoUpSLP::EdgeInfo &EI) {
      EI.dump(OS);
      return OS;
    }
    /// Debug print.
    void dump(raw_ostream &OS) const {
      OS << "{User:" << (UserTE ? std::to_string(UserTE->Idx) : "null")
         << " EdgeIdx:" << EdgeIdx << "}";
    }
    LLVM_DUMP_METHOD void dump() const { dump(dbgs()); }
#endif
    bool operator == (const EdgeInfo &Other) const {
      return UserTE == Other.UserTE && EdgeIdx == Other.EdgeIdx;
    }
  };

  /// A helper class used for scoring candidates for two consecutive lanes.
  class LookAheadHeuristics {
    const TargetLibraryInfo &TLI;
    const DataLayout &DL;
    ScalarEvolution &SE;
    const BoUpSLP &R;
    int NumLanes; // Total number of lanes (aka vectorization factor).
    int MaxLevel; // The maximum recursion depth for accumulating score.

  public:
    LookAheadHeuristics(const TargetLibraryInfo &TLI, const DataLayout &DL,
                        ScalarEvolution &SE, const BoUpSLP &R, int NumLanes,
                        int MaxLevel)
        : TLI(TLI), DL(DL), SE(SE), R(R), NumLanes(NumLanes),
          MaxLevel(MaxLevel) {}

    // The hard-coded scores listed here are not very important, though it shall
    // be higher for better matches to improve the resulting cost. When
    // computing the scores of matching one sub-tree with another, we are
    // basically counting the number of values that are matching. So even if all
    // scores are set to 1, we would still get a decent matching result.
    // However, sometimes we have to break ties. For example we may have to
    // choose between matching loads vs matching opcodes. This is what these
    // scores are helping us with: they provide the order of preference. Also,
    // this is important if the scalar is externally used or used in another
    // tree entry node in the different lane.

    /// Loads from consecutive memory addresses, e.g. load(A[i]), load(A[i+1]).
    static const int ScoreConsecutiveLoads = 4;
    /// The same load multiple times. This should have a better score than
    /// `ScoreSplat` because it in x86 for a 2-lane vector we can represent it
    /// with `movddup (%reg), xmm0` which has a throughput of 0.5 versus 0.5 for
    /// a vector load and 1.0 for a broadcast.
    static const int ScoreSplatLoads = 3;
    /// Loads from reversed memory addresses, e.g. load(A[i+1]), load(A[i]).
    static const int ScoreReversedLoads = 3;
    /// A load candidate for masked gather.
    static const int ScoreMaskedGatherCandidate = 1;
    /// ExtractElementInst from same vector and consecutive indexes.
    static const int ScoreConsecutiveExtracts = 4;
    /// ExtractElementInst from same vector and reversed indices.
    static const int ScoreReversedExtracts = 3;
    /// Constants.
    static const int ScoreConstants = 2;
    /// Instructions with the same opcode.
    static const int ScoreSameOpcode = 2;
    /// Instructions with alt opcodes (e.g, add + sub).
    static const int ScoreAltOpcodes = 1;
    /// Identical instructions (a.k.a. splat or broadcast).
    static const int ScoreSplat = 1;
    /// Matching with an undef is preferable to failing.
    static const int ScoreUndef = 1;
    /// Score for failing to find a decent match.
    static const int ScoreFail = 0;
    /// Score if all users are vectorized.
    static const int ScoreAllUserVectorized = 1;

    /// \returns the score of placing \p V1 and \p V2 in consecutive lanes.
    /// \p U1 and \p U2 are the users of \p V1 and \p V2.
    /// Also, checks if \p V1 and \p V2 are compatible with instructions in \p
    /// MainAltOps.
    int getShallowScore(Value *V1, Value *V2, Instruction *U1, Instruction *U2,
                        ArrayRef<Value *> MainAltOps) const {
      if (!isValidElementType(V1->getType()) ||
          !isValidElementType(V2->getType()))
        return LookAheadHeuristics::ScoreFail;

      if (V1 == V2) {
        if (isa<LoadInst>(V1)) {
          // Retruns true if the users of V1 and V2 won't need to be extracted.
          auto AllUsersAreInternal = [U1, U2, this](Value *V1, Value *V2) {
            // Bail out if we have too many uses to save compilation time.
            if (V1->hasNUsesOrMore(UsesLimit) || V2->hasNUsesOrMore(UsesLimit))
              return false;

            auto AllUsersVectorized = [U1, U2, this](Value *V) {
              return llvm::all_of(V->users(), [U1, U2, this](Value *U) {
                return U == U1 || U == U2 || R.getTreeEntry(U) != nullptr;
              });
            };
            return AllUsersVectorized(V1) && AllUsersVectorized(V2);
          };
          // A broadcast of a load can be cheaper on some targets.
          if (R.TTI->isLegalBroadcastLoad(V1->getType(),
                                          ElementCount::getFixed(NumLanes)) &&
              ((int)V1->getNumUses() == NumLanes ||
               AllUsersAreInternal(V1, V2)))
            return LookAheadHeuristics::ScoreSplatLoads;
        }
        return LookAheadHeuristics::ScoreSplat;
      }

      auto CheckSameEntryOrFail = [&]() {
        if (const TreeEntry *TE1 = R.getTreeEntry(V1);
            TE1 && TE1 == R.getTreeEntry(V2))
          return LookAheadHeuristics::ScoreSplatLoads;
        return LookAheadHeuristics::ScoreFail;
      };

      auto *LI1 = dyn_cast<LoadInst>(V1);
      auto *LI2 = dyn_cast<LoadInst>(V2);
      if (LI1 && LI2) {
        if (LI1->getParent() != LI2->getParent() || !LI1->isSimple() ||
            !LI2->isSimple())
          return CheckSameEntryOrFail();

        std::optional<int> Dist = getPointersDiff(
            LI1->getType(), LI1->getPointerOperand(), LI2->getType(),
            LI2->getPointerOperand(), DL, SE, /*StrictCheck=*/true);
        if (!Dist || *Dist == 0) {
          if (getUnderlyingObject(LI1->getPointerOperand()) ==
                  getUnderlyingObject(LI2->getPointerOperand()) &&
              R.TTI->isLegalMaskedGather(
                  getWidenedType(LI1->getType(), NumLanes), LI1->getAlign()))
            return LookAheadHeuristics::ScoreMaskedGatherCandidate;
          return CheckSameEntryOrFail();
        }
        // The distance is too large - still may be profitable to use masked
        // loads/gathers.
        if (std::abs(*Dist) > NumLanes / 2)
          return LookAheadHeuristics::ScoreMaskedGatherCandidate;
        // This still will detect consecutive loads, but we might have "holes"
        // in some cases. It is ok for non-power-2 vectorization and may produce
        // better results. It should not affect current vectorization.
        return (*Dist > 0) ? LookAheadHeuristics::ScoreConsecutiveLoads
                           : LookAheadHeuristics::ScoreReversedLoads;
      }

      auto *C1 = dyn_cast<Constant>(V1);
      auto *C2 = dyn_cast<Constant>(V2);
      if (C1 && C2)
        return LookAheadHeuristics::ScoreConstants;

      // Extracts from consecutive indexes of the same vector better score as
      // the extracts could be optimized away.
      Value *EV1;
      ConstantInt *Ex1Idx;
      if (match(V1, m_ExtractElt(m_Value(EV1), m_ConstantInt(Ex1Idx)))) {
        // Undefs are always profitable for extractelements.
        // Compiler can easily combine poison and extractelement <non-poison> or
        // undef and extractelement <poison>. But combining undef +
        // extractelement <non-poison-but-may-produce-poison> requires some
        // extra operations.
        if (isa<UndefValue>(V2))
          return (isa<PoisonValue>(V2) || isUndefVector(EV1).all())
                     ? LookAheadHeuristics::ScoreConsecutiveExtracts
                     : LookAheadHeuristics::ScoreSameOpcode;
        Value *EV2 = nullptr;
        ConstantInt *Ex2Idx = nullptr;
        if (match(V2,
                  m_ExtractElt(m_Value(EV2), m_CombineOr(m_ConstantInt(Ex2Idx),
                                                         m_Undef())))) {
          // Undefs are always profitable for extractelements.
          if (!Ex2Idx)
            return LookAheadHeuristics::ScoreConsecutiveExtracts;
          if (isUndefVector(EV2).all() && EV2->getType() == EV1->getType())
            return LookAheadHeuristics::ScoreConsecutiveExtracts;
          if (EV2 == EV1) {
            int Idx1 = Ex1Idx->getZExtValue();
            int Idx2 = Ex2Idx->getZExtValue();
            int Dist = Idx2 - Idx1;
            // The distance is too large - still may be profitable to use
            // shuffles.
            if (std::abs(Dist) == 0)
              return LookAheadHeuristics::ScoreSplat;
            if (std::abs(Dist) > NumLanes / 2)
              return LookAheadHeuristics::ScoreSameOpcode;
            return (Dist > 0) ? LookAheadHeuristics::ScoreConsecutiveExtracts
                              : LookAheadHeuristics::ScoreReversedExtracts;
          }
          return LookAheadHeuristics::ScoreAltOpcodes;
        }
        return CheckSameEntryOrFail();
      }

      auto *I1 = dyn_cast<Instruction>(V1);
      auto *I2 = dyn_cast<Instruction>(V2);
      if (I1 && I2) {
        if (I1->getParent() != I2->getParent())
          return CheckSameEntryOrFail();
        SmallVector<Value *, 4> Ops(MainAltOps);
        Ops.push_back(I1);
        Ops.push_back(I2);
        InstructionsState S = getSameOpcode(Ops, TLI);
        // Note: Only consider instructions with <= 2 operands to avoid
        // complexity explosion.
        if (S.getOpcode() &&
            (S.MainOp->getNumOperands() <= 2 || !MainAltOps.empty() ||
             !S.isAltShuffle()) &&
            all_of(Ops, [&S](Value *V) {
              return cast<Instruction>(V)->getNumOperands() ==
                     S.MainOp->getNumOperands();
            }))
          return S.isAltShuffle() ? LookAheadHeuristics::ScoreAltOpcodes
                                  : LookAheadHeuristics::ScoreSameOpcode;
      }

      if (isa<UndefValue>(V2))
        return LookAheadHeuristics::ScoreUndef;

      return CheckSameEntryOrFail();
    }

    /// Go through the operands of \p LHS and \p RHS recursively until
    /// MaxLevel, and return the cummulative score. \p U1 and \p U2 are
    /// the users of \p LHS and \p RHS (that is \p LHS and \p RHS are operands
    /// of \p U1 and \p U2), except at the beginning of the recursion where
    /// these are set to nullptr.
    ///
    /// For example:
    /// \verbatim
    ///  A[0]  B[0]  A[1]  B[1]  C[0] D[0]  B[1] A[1]
    ///     \ /         \ /         \ /        \ /
    ///      +           +           +          +
    ///     G1          G2          G3         G4
    /// \endverbatim
    /// The getScoreAtLevelRec(G1, G2) function will try to match the nodes at
    /// each level recursively, accumulating the score. It starts from matching
    /// the additions at level 0, then moves on to the loads (level 1). The
    /// score of G1 and G2 is higher than G1 and G3, because {A[0],A[1]} and
    /// {B[0],B[1]} match with LookAheadHeuristics::ScoreConsecutiveLoads, while
    /// {A[0],C[0]} has a score of LookAheadHeuristics::ScoreFail.
    /// Please note that the order of the operands does not matter, as we
    /// evaluate the score of all profitable combinations of operands. In
    /// other words the score of G1 and G4 is the same as G1 and G2. This
    /// heuristic is based on ideas described in:
    ///   Look-ahead SLP: Auto-vectorization in the presence of commutative
    ///   operations, CGO 2018 by Vasileios Porpodas, Rodrigo C. O. Rocha,
    ///   Luís F. W. Góes
    int getScoreAtLevelRec(Value *LHS, Value *RHS, Instruction *U1,
                           Instruction *U2, int CurrLevel,
                           ArrayRef<Value *> MainAltOps) const {

      // Get the shallow score of V1 and V2.
      int ShallowScoreAtThisLevel =
          getShallowScore(LHS, RHS, U1, U2, MainAltOps);

      // If reached MaxLevel,
      //  or if V1 and V2 are not instructions,
      //  or if they are SPLAT,
      //  or if they are not consecutive,
      //  or if profitable to vectorize loads or extractelements, early return
      //  the current cost.
      auto *I1 = dyn_cast<Instruction>(LHS);
      auto *I2 = dyn_cast<Instruction>(RHS);
      if (CurrLevel == MaxLevel || !(I1 && I2) || I1 == I2 ||
          ShallowScoreAtThisLevel == LookAheadHeuristics::ScoreFail ||
          (((isa<LoadInst>(I1) && isa<LoadInst>(I2)) ||
            (I1->getNumOperands() > 2 && I2->getNumOperands() > 2) ||
            (isa<ExtractElementInst>(I1) && isa<ExtractElementInst>(I2))) &&
           ShallowScoreAtThisLevel))
        return ShallowScoreAtThisLevel;
      assert(I1 && I2 && "Should have early exited.");

      // Contains the I2 operand indexes that got matched with I1 operands.
      SmallSet<unsigned, 4> Op2Used;

      // Recursion towards the operands of I1 and I2. We are trying all possible
      // operand pairs, and keeping track of the best score.
      for (unsigned OpIdx1 = 0, NumOperands1 = I1->getNumOperands();
           OpIdx1 != NumOperands1; ++OpIdx1) {
        // Try to pair op1I with the best operand of I2.
        int MaxTmpScore = 0;
        unsigned MaxOpIdx2 = 0;
        bool FoundBest = false;
        // If I2 is commutative try all combinations.
        unsigned FromIdx = isCommutative(I2) ? 0 : OpIdx1;
        unsigned ToIdx = isCommutative(I2)
                             ? I2->getNumOperands()
                             : std::min(I2->getNumOperands(), OpIdx1 + 1);
        assert(FromIdx <= ToIdx && "Bad index");
        for (unsigned OpIdx2 = FromIdx; OpIdx2 != ToIdx; ++OpIdx2) {
          // Skip operands already paired with OpIdx1.
          if (Op2Used.count(OpIdx2))
            continue;
          // Recursively calculate the cost at each level
          int TmpScore =
              getScoreAtLevelRec(I1->getOperand(OpIdx1), I2->getOperand(OpIdx2),
                                 I1, I2, CurrLevel + 1, {});
          // Look for the best score.
          if (TmpScore > LookAheadHeuristics::ScoreFail &&
              TmpScore > MaxTmpScore) {
            MaxTmpScore = TmpScore;
            MaxOpIdx2 = OpIdx2;
            FoundBest = true;
          }
        }
        if (FoundBest) {
          // Pair {OpIdx1, MaxOpIdx2} was found to be best. Never revisit it.
          Op2Used.insert(MaxOpIdx2);
          ShallowScoreAtThisLevel += MaxTmpScore;
        }
      }
      return ShallowScoreAtThisLevel;
    }
  };
  /// A helper data structure to hold the operands of a vector of instructions.
  /// This supports a fixed vector length for all operand vectors.
  class VLOperands {
    /// For each operand we need (i) the value, and (ii) the opcode that it
    /// would be attached to if the expression was in a left-linearized form.
    /// This is required to avoid illegal operand reordering.
    /// For example:
    /// \verbatim
    ///                         0 Op1
    ///                         |/
    /// Op1 Op2   Linearized    + Op2
    ///   \ /     ---------->   |/
    ///    -                    -
    ///
    /// Op1 - Op2            (0 + Op1) - Op2
    /// \endverbatim
    ///
    /// Value Op1 is attached to a '+' operation, and Op2 to a '-'.
    ///
    /// Another way to think of this is to track all the operations across the
    /// path from the operand all the way to the root of the tree and to
    /// calculate the operation that corresponds to this path. For example, the
    /// path from Op2 to the root crosses the RHS of the '-', therefore the
    /// corresponding operation is a '-' (which matches the one in the
    /// linearized tree, as shown above).
    ///
    /// For lack of a better term, we refer to this operation as Accumulated
    /// Path Operation (APO).
    struct OperandData {
      OperandData() = default;
      OperandData(Value *V, bool APO, bool IsUsed)
          : V(V), APO(APO), IsUsed(IsUsed) {}
      /// The operand value.
      Value *V = nullptr;
      /// TreeEntries only allow a single opcode, or an alternate sequence of
      /// them (e.g, +, -). Therefore, we can safely use a boolean value for the
      /// APO. It is set to 'true' if 'V' is attached to an inverse operation
      /// in the left-linearized form (e.g., Sub/Div), and 'false' otherwise
      /// (e.g., Add/Mul)
      bool APO = false;
      /// Helper data for the reordering function.
      bool IsUsed = false;
    };

    /// During operand reordering, we are trying to select the operand at lane
    /// that matches best with the operand at the neighboring lane. Our
    /// selection is based on the type of value we are looking for. For example,
    /// if the neighboring lane has a load, we need to look for a load that is
    /// accessing a consecutive address. These strategies are summarized in the
    /// 'ReorderingMode' enumerator.
    enum class ReorderingMode {
      Load,     ///< Matching loads to consecutive memory addresses
      Opcode,   ///< Matching instructions based on opcode (same or alternate)
      Constant, ///< Matching constants
      Splat,    ///< Matching the same instruction multiple times (broadcast)
      Failed,   ///< We failed to create a vectorizable group
    };

    using OperandDataVec = SmallVector<OperandData, 2>;

    /// A vector of operand vectors.
    SmallVector<OperandDataVec, 4> OpsVec;

    const TargetLibraryInfo &TLI;
    const DataLayout &DL;
    ScalarEvolution &SE;
    const BoUpSLP &R;
    const Loop *L = nullptr;

    /// \returns the operand data at \p OpIdx and \p Lane.
    OperandData &getData(unsigned OpIdx, unsigned Lane) {
      return OpsVec[OpIdx][Lane];
    }

    /// \returns the operand data at \p OpIdx and \p Lane. Const version.
    const OperandData &getData(unsigned OpIdx, unsigned Lane) const {
      return OpsVec[OpIdx][Lane];
    }

    /// Clears the used flag for all entries.
    void clearUsed() {
      for (unsigned OpIdx = 0, NumOperands = getNumOperands();
           OpIdx != NumOperands; ++OpIdx)
        for (unsigned Lane = 0, NumLanes = getNumLanes(); Lane != NumLanes;
             ++Lane)
          OpsVec[OpIdx][Lane].IsUsed = false;
    }

    /// Swap the operand at \p OpIdx1 with that one at \p OpIdx2.
    void swap(unsigned OpIdx1, unsigned OpIdx2, unsigned Lane) {
      std::swap(OpsVec[OpIdx1][Lane], OpsVec[OpIdx2][Lane]);
    }

    /// \param Lane lane of the operands under analysis.
    /// \param OpIdx operand index in \p Lane lane we're looking the best
    /// candidate for.
    /// \param Idx operand index of the current candidate value.
    /// \returns The additional score due to possible broadcasting of the
    /// elements in the lane. It is more profitable to have power-of-2 unique
    /// elements in the lane, it will be vectorized with higher probability
    /// after removing duplicates. Currently the SLP vectorizer supports only
    /// vectorization of the power-of-2 number of unique scalars.
    int getSplatScore(unsigned Lane, unsigned OpIdx, unsigned Idx,
                      const SmallBitVector &UsedLanes) const {
      Value *IdxLaneV = getData(Idx, Lane).V;
      if (!isa<Instruction>(IdxLaneV) || IdxLaneV == getData(OpIdx, Lane).V ||
          isa<ExtractElementInst>(IdxLaneV))
        return 0;
      SmallDenseMap<Value *, unsigned, 4> Uniques;
      for (unsigned Ln : seq<unsigned>(getNumLanes())) {
        if (Ln == Lane)
          continue;
        Value *OpIdxLnV = getData(OpIdx, Ln).V;
        if (!isa<Instruction>(OpIdxLnV))
          return 0;
        Uniques.try_emplace(OpIdxLnV, Ln);
      }
      unsigned UniquesCount = Uniques.size();
      auto IdxIt = Uniques.find(IdxLaneV);
      unsigned UniquesCntWithIdxLaneV =
          IdxIt != Uniques.end() ? UniquesCount : UniquesCount + 1;
      Value *OpIdxLaneV = getData(OpIdx, Lane).V;
      auto OpIdxIt = Uniques.find(OpIdxLaneV);
      unsigned UniquesCntWithOpIdxLaneV =
          OpIdxIt != Uniques.end() ? UniquesCount : UniquesCount + 1;
      if (UniquesCntWithIdxLaneV == UniquesCntWithOpIdxLaneV)
        return 0;
      return std::min(bit_ceil(UniquesCntWithOpIdxLaneV) -
                          UniquesCntWithOpIdxLaneV,
                      UniquesCntWithOpIdxLaneV -
                          bit_floor(UniquesCntWithOpIdxLaneV)) -
             ((IdxIt != Uniques.end() && UsedLanes.test(IdxIt->second))
                  ? UniquesCntWithIdxLaneV - bit_floor(UniquesCntWithIdxLaneV)
                  : bit_ceil(UniquesCntWithIdxLaneV) - UniquesCntWithIdxLaneV);
    }

    /// \param Lane lane of the operands under analysis.
    /// \param OpIdx operand index in \p Lane lane we're looking the best
    /// candidate for.
    /// \param Idx operand index of the current candidate value.
    /// \returns The additional score for the scalar which users are all
    /// vectorized.
    int getExternalUseScore(unsigned Lane, unsigned OpIdx, unsigned Idx) const {
      Value *IdxLaneV = getData(Idx, Lane).V;
      Value *OpIdxLaneV = getData(OpIdx, Lane).V;
      // Do not care about number of uses for vector-like instructions
      // (extractelement/extractvalue with constant indices), they are extracts
      // themselves and already externally used. Vectorization of such
      // instructions does not add extra extractelement instruction, just may
      // remove it.
      if (isVectorLikeInstWithConstOps(IdxLaneV) &&
          isVectorLikeInstWithConstOps(OpIdxLaneV))
        return LookAheadHeuristics::ScoreAllUserVectorized;
      auto *IdxLaneI = dyn_cast<Instruction>(IdxLaneV);
      if (!IdxLaneI || !isa<Instruction>(OpIdxLaneV))
        return 0;
      return R.areAllUsersVectorized(IdxLaneI)
                 ? LookAheadHeuristics::ScoreAllUserVectorized
                 : 0;
    }

    /// Score scaling factor for fully compatible instructions but with
    /// different number of external uses. Allows better selection of the
    /// instructions with less external uses.
    static const int ScoreScaleFactor = 10;

    /// \Returns the look-ahead score, which tells us how much the sub-trees
    /// rooted at \p LHS and \p RHS match, the more they match the higher the
    /// score. This helps break ties in an informed way when we cannot decide on
    /// the order of the operands by just considering the immediate
    /// predecessors.
    int getLookAheadScore(Value *LHS, Value *RHS, ArrayRef<Value *> MainAltOps,
                          int Lane, unsigned OpIdx, unsigned Idx,
                          bool &IsUsed, const SmallBitVector &UsedLanes) {
      LookAheadHeuristics LookAhead(TLI, DL, SE, R, getNumLanes(),
                                    LookAheadMaxDepth);
      // Keep track of the instruction stack as we recurse into the operands
      // during the look-ahead score exploration.
      int Score =
          LookAhead.getScoreAtLevelRec(LHS, RHS, /*U1=*/nullptr, /*U2=*/nullptr,
                                       /*CurrLevel=*/1, MainAltOps);
      if (Score) {
        int SplatScore = getSplatScore(Lane, OpIdx, Idx, UsedLanes);
        if (Score <= -SplatScore) {
          // Failed score.
          Score = 0;
        } else {
          Score += SplatScore;
          // Scale score to see the difference between different operands
          // and similar operands but all vectorized/not all vectorized
          // uses. It does not affect actual selection of the best
          // compatible operand in general, just allows to select the
          // operand with all vectorized uses.
          Score *= ScoreScaleFactor;
          Score += getExternalUseScore(Lane, OpIdx, Idx);
          IsUsed = true;
        }
      }
      return Score;
    }

    /// Best defined scores per lanes between the passes. Used to choose the
    /// best operand (with the highest score) between the passes.
    /// The key - {Operand Index, Lane}.
    /// The value - the best score between the passes for the lane and the
    /// operand.
    SmallDenseMap<std::pair<unsigned, unsigned>, unsigned, 8>
        BestScoresPerLanes;

    // Search all operands in Ops[*][Lane] for the one that matches best
    // Ops[OpIdx][LastLane] and return its opreand index.
    // If no good match can be found, return std::nullopt.
    std::optional<unsigned>
    getBestOperand(unsigned OpIdx, int Lane, int LastLane,
                   ArrayRef<ReorderingMode> ReorderingModes,
                   ArrayRef<Value *> MainAltOps,
                   const SmallBitVector &UsedLanes) {
      unsigned NumOperands = getNumOperands();

      // The operand of the previous lane at OpIdx.
      Value *OpLastLane = getData(OpIdx, LastLane).V;

      // Our strategy mode for OpIdx.
      ReorderingMode RMode = ReorderingModes[OpIdx];
      if (RMode == ReorderingMode::Failed)
        return std::nullopt;

      // The linearized opcode of the operand at OpIdx, Lane.
      bool OpIdxAPO = getData(OpIdx, Lane).APO;

      // The best operand index and its score.
      // Sometimes we have more than one option (e.g., Opcode and Undefs), so we
      // are using the score to differentiate between the two.
      struct BestOpData {
        std::optional<unsigned> Idx;
        unsigned Score = 0;
      } BestOp;
      BestOp.Score =
          BestScoresPerLanes.try_emplace(std::make_pair(OpIdx, Lane), 0)
              .first->second;

      // Track if the operand must be marked as used. If the operand is set to
      // Score 1 explicitly (because of non power-of-2 unique scalars, we may
      // want to reestimate the operands again on the following iterations).
      bool IsUsed = RMode == ReorderingMode::Splat ||
                    RMode == ReorderingMode::Constant ||
                    RMode == ReorderingMode::Load;
      // Iterate through all unused operands and look for the best.
      for (unsigned Idx = 0; Idx != NumOperands; ++Idx) {
        // Get the operand at Idx and Lane.
        OperandData &OpData = getData(Idx, Lane);
        Value *Op = OpData.V;
        bool OpAPO = OpData.APO;

        // Skip already selected operands.
        if (OpData.IsUsed)
          continue;

        // Skip if we are trying to move the operand to a position with a
        // different opcode in the linearized tree form. This would break the
        // semantics.
        if (OpAPO != OpIdxAPO)
          continue;

        // Look for an operand that matches the current mode.
        switch (RMode) {
        case ReorderingMode::Load:
        case ReorderingMode::Opcode: {
          bool LeftToRight = Lane > LastLane;
          Value *OpLeft = (LeftToRight) ? OpLastLane : Op;
          Value *OpRight = (LeftToRight) ? Op : OpLastLane;
          int Score = getLookAheadScore(OpLeft, OpRight, MainAltOps, Lane,
                                        OpIdx, Idx, IsUsed, UsedLanes);
          if (Score > static_cast<int>(BestOp.Score) ||
              (Score > 0 && Score == static_cast<int>(BestOp.Score) &&
               Idx == OpIdx)) {
            BestOp.Idx = Idx;
            BestOp.Score = Score;
            BestScoresPerLanes[std::make_pair(OpIdx, Lane)] = Score;
          }
          break;
        }
        case ReorderingMode::Constant:
          if (isa<Constant>(Op) ||
              (!BestOp.Score && L && L->isLoopInvariant(Op))) {
            BestOp.Idx = Idx;
            if (isa<Constant>(Op)) {
              BestOp.Score = LookAheadHeuristics::ScoreConstants;
              BestScoresPerLanes[std::make_pair(OpIdx, Lane)] =
                  LookAheadHeuristics::ScoreConstants;
            }
            if (isa<UndefValue>(Op) || !isa<Constant>(Op))
              IsUsed = false;
          }
          break;
        case ReorderingMode::Splat:
          if (Op == OpLastLane || (!BestOp.Score && isa<Constant>(Op))) {
            IsUsed = Op == OpLastLane;
            if (Op == OpLastLane) {
              BestOp.Score = LookAheadHeuristics::ScoreSplat;
              BestScoresPerLanes[std::make_pair(OpIdx, Lane)] =
                  LookAheadHeuristics::ScoreSplat;
            }
            BestOp.Idx = Idx;
          }
          break;
        case ReorderingMode::Failed:
          llvm_unreachable("Not expected Failed reordering mode.");
        }
      }

      if (BestOp.Idx) {
        getData(*BestOp.Idx, Lane).IsUsed = IsUsed;
        return BestOp.Idx;
      }
      // If we could not find a good match return std::nullopt.
      return std::nullopt;
    }

    /// Helper for reorderOperandVecs.
    /// \returns the lane that we should start reordering from. This is the one
    /// which has the least number of operands that can freely move about or
    /// less profitable because it already has the most optimal set of operands.
    unsigned getBestLaneToStartReordering() const {
      unsigned Min = UINT_MAX;
      unsigned SameOpNumber = 0;
      // std::pair<unsigned, unsigned> is used to implement a simple voting
      // algorithm and choose the lane with the least number of operands that
      // can freely move about or less profitable because it already has the
      // most optimal set of operands. The first unsigned is a counter for
      // voting, the second unsigned is the counter of lanes with instructions
      // with same/alternate opcodes and same parent basic block.
      MapVector<unsigned, std::pair<unsigned, unsigned>> HashMap;
      // Try to be closer to the original results, if we have multiple lanes
      // with same cost. If 2 lanes have the same cost, use the one with the
      // lowest index.
      for (int I = getNumLanes(); I > 0; --I) {
        unsigned Lane = I - 1;
        OperandsOrderData NumFreeOpsHash =
            getMaxNumOperandsThatCanBeReordered(Lane);
        // Compare the number of operands that can move and choose the one with
        // the least number.
        if (NumFreeOpsHash.NumOfAPOs < Min) {
          Min = NumFreeOpsHash.NumOfAPOs;
          SameOpNumber = NumFreeOpsHash.NumOpsWithSameOpcodeParent;
          HashMap.clear();
          HashMap[NumFreeOpsHash.Hash] = std::make_pair(1, Lane);
        } else if (NumFreeOpsHash.NumOfAPOs == Min &&
                   NumFreeOpsHash.NumOpsWithSameOpcodeParent < SameOpNumber) {
          // Select the most optimal lane in terms of number of operands that
          // should be moved around.
          SameOpNumber = NumFreeOpsHash.NumOpsWithSameOpcodeParent;
          HashMap[NumFreeOpsHash.Hash] = std::make_pair(1, Lane);
        } else if (NumFreeOpsHash.NumOfAPOs == Min &&
                   NumFreeOpsHash.NumOpsWithSameOpcodeParent == SameOpNumber) {
          auto *It = HashMap.find(NumFreeOpsHash.Hash);
          if (It == HashMap.end())
            HashMap[NumFreeOpsHash.Hash] = std::make_pair(1, Lane);
          else
            ++It->second.first;
        }
      }
      // Select the lane with the minimum counter.
      unsigned BestLane = 0;
      unsigned CntMin = UINT_MAX;
      for (const auto &Data : reverse(HashMap)) {
        if (Data.second.first < CntMin) {
          CntMin = Data.second.first;
          BestLane = Data.second.second;
        }
      }
      return BestLane;
    }

    /// Data structure that helps to reorder operands.
    struct OperandsOrderData {
      /// The best number of operands with the same APOs, which can be
      /// reordered.
      unsigned NumOfAPOs = UINT_MAX;
      /// Number of operands with the same/alternate instruction opcode and
      /// parent.
      unsigned NumOpsWithSameOpcodeParent = 0;
      /// Hash for the actual operands ordering.
      /// Used to count operands, actually their position id and opcode
      /// value. It is used in the voting mechanism to find the lane with the
      /// least number of operands that can freely move about or less profitable
      /// because it already has the most optimal set of operands. Can be
      /// replaced with SmallVector<unsigned> instead but hash code is faster
      /// and requires less memory.
      unsigned Hash = 0;
    };
    /// \returns the maximum number of operands that are allowed to be reordered
    /// for \p Lane and the number of compatible instructions(with the same
    /// parent/opcode). This is used as a heuristic for selecting the first lane
    /// to start operand reordering.
    OperandsOrderData getMaxNumOperandsThatCanBeReordered(unsigned Lane) const {
      unsigned CntTrue = 0;
      unsigned NumOperands = getNumOperands();
      // Operands with the same APO can be reordered. We therefore need to count
      // how many of them we have for each APO, like this: Cnt[APO] = x.
      // Since we only have two APOs, namely true and false, we can avoid using
      // a map. Instead we can simply count the number of operands that
      // correspond to one of them (in this case the 'true' APO), and calculate
      // the other by subtracting it from the total number of operands.
      // Operands with the same instruction opcode and parent are more
      // profitable since we don't need to move them in many cases, with a high
      // probability such lane already can be vectorized effectively.
      bool AllUndefs = true;
      unsigned NumOpsWithSameOpcodeParent = 0;
      Instruction *OpcodeI = nullptr;
      BasicBlock *Parent = nullptr;
      unsigned Hash = 0;
      for (unsigned OpIdx = 0; OpIdx != NumOperands; ++OpIdx) {
        const OperandData &OpData = getData(OpIdx, Lane);
        if (OpData.APO)
          ++CntTrue;
        // Use Boyer-Moore majority voting for finding the majority opcode and
        // the number of times it occurs.
        if (auto *I = dyn_cast<Instruction>(OpData.V)) {
          if (!OpcodeI || !getSameOpcode({OpcodeI, I}, TLI).getOpcode() ||
              I->getParent() != Parent) {
            if (NumOpsWithSameOpcodeParent == 0) {
              NumOpsWithSameOpcodeParent = 1;
              OpcodeI = I;
              Parent = I->getParent();
            } else {
              --NumOpsWithSameOpcodeParent;
            }
          } else {
            ++NumOpsWithSameOpcodeParent;
          }
        }
        Hash = hash_combine(
            Hash, hash_value((OpIdx + 1) * (OpData.V->getValueID() + 1)));
        AllUndefs = AllUndefs && isa<UndefValue>(OpData.V);
      }
      if (AllUndefs)
        return {};
      OperandsOrderData Data;
      Data.NumOfAPOs = std::max(CntTrue, NumOperands - CntTrue);
      Data.NumOpsWithSameOpcodeParent = NumOpsWithSameOpcodeParent;
      Data.Hash = Hash;
      return Data;
    }

    /// Go through the instructions in VL and append their operands.
    void appendOperandsOfVL(ArrayRef<Value *> VL) {
      assert(!VL.empty() && "Bad VL");
      assert((empty() || VL.size() == getNumLanes()) &&
             "Expected same number of lanes");
      assert(isa<Instruction>(VL[0]) && "Expected instruction");
      unsigned NumOperands = cast<Instruction>(VL[0])->getNumOperands();
      constexpr unsigned IntrinsicNumOperands = 2;
      if (isa<IntrinsicInst>(VL[0]))
        NumOperands = IntrinsicNumOperands;
      OpsVec.resize(NumOperands);
      unsigned NumLanes = VL.size();
      for (unsigned OpIdx = 0; OpIdx != NumOperands; ++OpIdx) {
        OpsVec[OpIdx].resize(NumLanes);
        for (unsigned Lane = 0; Lane != NumLanes; ++Lane) {
          assert(isa<Instruction>(VL[Lane]) && "Expected instruction");
          // Our tree has just 3 nodes: the root and two operands.
          // It is therefore trivial to get the APO. We only need to check the
          // opcode of VL[Lane] and whether the operand at OpIdx is the LHS or
          // RHS operand. The LHS operand of both add and sub is never attached
          // to an inversese operation in the linearized form, therefore its APO
          // is false. The RHS is true only if VL[Lane] is an inverse operation.

          // Since operand reordering is performed on groups of commutative
          // operations or alternating sequences (e.g., +, -), we can safely
          // tell the inverse operations by checking commutativity.
          bool IsInverseOperation = !isCommutative(cast<Instruction>(VL[Lane]));
          bool APO = (OpIdx == 0) ? false : IsInverseOperation;
          OpsVec[OpIdx][Lane] = {cast<Instruction>(VL[Lane])->getOperand(OpIdx),
                                 APO, false};
        }
      }
    }

    /// \returns the number of operands.
    unsigned getNumOperands() const { return OpsVec.size(); }

    /// \returns the number of lanes.
    unsigned getNumLanes() const { return OpsVec[0].size(); }

    /// \returns the operand value at \p OpIdx and \p Lane.
    Value *getValue(unsigned OpIdx, unsigned Lane) const {
      return getData(OpIdx, Lane).V;
    }

    /// \returns true if the data structure is empty.
    bool empty() const { return OpsVec.empty(); }

    /// Clears the data.
    void clear() { OpsVec.clear(); }

    /// \Returns true if there are enough operands identical to \p Op to fill
    /// the whole vector (it is mixed with constants or loop invariant values).
    /// Note: This modifies the 'IsUsed' flag, so a cleanUsed() must follow.
    bool shouldBroadcast(Value *Op, unsigned OpIdx, unsigned Lane) {
      bool OpAPO = getData(OpIdx, Lane).APO;
      bool IsInvariant = L && L->isLoopInvariant(Op);
      unsigned Cnt = 0;
      for (unsigned Ln = 0, Lns = getNumLanes(); Ln != Lns; ++Ln) {
        if (Ln == Lane)
          continue;
        // This is set to true if we found a candidate for broadcast at Lane.
        bool FoundCandidate = false;
        for (unsigned OpI = 0, OpE = getNumOperands(); OpI != OpE; ++OpI) {
          OperandData &Data = getData(OpI, Ln);
          if (Data.APO != OpAPO || Data.IsUsed)
            continue;
          Value *OpILane = getValue(OpI, Lane);
          bool IsConstantOp = isa<Constant>(OpILane);
          // Consider the broadcast candidate if:
          // 1. Same value is found in one of the operands.
          if (Data.V == Op ||
              // 2. The operand in the given lane is not constant but there is a
              // constant operand in another lane (which can be moved to the
              // given lane). In this case we can represent it as a simple
              // permutation of constant and broadcast.
              (!IsConstantOp &&
               ((Lns > 2 && isa<Constant>(Data.V)) ||
                // 2.1. If we have only 2 lanes, need to check that value in the
                // next lane does not build same opcode sequence.
                (Lns == 2 &&
                 !getSameOpcode({Op, getValue((OpI + 1) % OpE, Ln)}, TLI)
                      .getOpcode() &&
                 isa<Constant>(Data.V)))) ||
              // 3. The operand in the current lane is loop invariant (can be
              // hoisted out) and another operand is also a loop invariant
              // (though not a constant). In this case the whole vector can be
              // hoisted out.
              // FIXME: need to teach the cost model about this case for better
              // estimation.
              (IsInvariant && !isa<Constant>(Data.V) &&
               !getSameOpcode({Op, Data.V}, TLI).getOpcode() &&
               L->isLoopInvariant(Data.V))) {
            FoundCandidate = true;
            Data.IsUsed = Data.V == Op;
            if (Data.V == Op)
              ++Cnt;
            break;
          }
        }
        if (!FoundCandidate)
          return false;
      }
      return getNumLanes() == 2 || Cnt > 1;
    }

    /// Checks if there is at least single compatible operand in lanes other
    /// than \p Lane, compatible with the operand \p Op.
    bool canBeVectorized(Instruction *Op, unsigned OpIdx, unsigned Lane) const {
      bool OpAPO = getData(OpIdx, Lane).APO;
      for (unsigned Ln = 0, Lns = getNumLanes(); Ln != Lns; ++Ln) {
        if (Ln == Lane)
          continue;
        if (any_of(seq<unsigned>(getNumOperands()), [&](unsigned OpI) {
              const OperandData &Data = getData(OpI, Ln);
              if (Data.APO != OpAPO || Data.IsUsed)
                return true;
              Value *OpILn = getValue(OpI, Ln);
              return (L && L->isLoopInvariant(OpILn)) ||
                     (getSameOpcode({Op, OpILn}, TLI).getOpcode() &&
                      Op->getParent() == cast<Instruction>(OpILn)->getParent());
            }))
          return true;
      }
      return false;
    }

  public:
    /// Initialize with all the operands of the instruction vector \p RootVL.
    VLOperands(ArrayRef<Value *> RootVL, const BoUpSLP &R)
        : TLI(*R.TLI), DL(*R.DL), SE(*R.SE), R(R),
          L(R.LI->getLoopFor(
              (cast<Instruction>(RootVL.front())->getParent()))) {
      // Append all the operands of RootVL.
      appendOperandsOfVL(RootVL);
    }

    /// \Returns a value vector with the operands across all lanes for the
    /// opearnd at \p OpIdx.
    ValueList getVL(unsigned OpIdx) const {
      ValueList OpVL(OpsVec[OpIdx].size());
      assert(OpsVec[OpIdx].size() == getNumLanes() &&
             "Expected same num of lanes across all operands");
      for (unsigned Lane = 0, Lanes = getNumLanes(); Lane != Lanes; ++Lane)
        OpVL[Lane] = OpsVec[OpIdx][Lane].V;
      return OpVL;
    }

    // Performs operand reordering for 2 or more operands.
    // The original operands are in OrigOps[OpIdx][Lane].
    // The reordered operands are returned in 'SortedOps[OpIdx][Lane]'.
    void reorder() {
      unsigned NumOperands = getNumOperands();
      unsigned NumLanes = getNumLanes();
      // Each operand has its own mode. We are using this mode to help us select
      // the instructions for each lane, so that they match best with the ones
      // we have selected so far.
      SmallVector<ReorderingMode, 2> ReorderingModes(NumOperands);

      // This is a greedy single-pass algorithm. We are going over each lane
      // once and deciding on the best order right away with no back-tracking.
      // However, in order to increase its effectiveness, we start with the lane
      // that has operands that can move the least. For example, given the
      // following lanes:
      //  Lane 0 : A[0] = B[0] + C[0]   // Visited 3rd
      //  Lane 1 : A[1] = C[1] - B[1]   // Visited 1st
      //  Lane 2 : A[2] = B[2] + C[2]   // Visited 2nd
      //  Lane 3 : A[3] = C[3] - B[3]   // Visited 4th
      // we will start at Lane 1, since the operands of the subtraction cannot
      // be reordered. Then we will visit the rest of the lanes in a circular
      // fashion. That is, Lanes 2, then Lane 0, and finally Lane 3.

      // Find the first lane that we will start our search from.
      unsigned FirstLane = getBestLaneToStartReordering();

      // Initialize the modes.
      for (unsigned OpIdx = 0; OpIdx != NumOperands; ++OpIdx) {
        Value *OpLane0 = getValue(OpIdx, FirstLane);
        // Keep track if we have instructions with all the same opcode on one
        // side.
        if (isa<LoadInst>(OpLane0))
          ReorderingModes[OpIdx] = ReorderingMode::Load;
        else if (auto *OpILane0 = dyn_cast<Instruction>(OpLane0)) {
          // Check if OpLane0 should be broadcast.
          if (shouldBroadcast(OpLane0, OpIdx, FirstLane) ||
              !canBeVectorized(OpILane0, OpIdx, FirstLane))
            ReorderingModes[OpIdx] = ReorderingMode::Splat;
          else
            ReorderingModes[OpIdx] = ReorderingMode::Opcode;
        } else if (isa<Constant>(OpLane0))
          ReorderingModes[OpIdx] = ReorderingMode::Constant;
        else if (isa<Argument>(OpLane0))
          // Our best hope is a Splat. It may save some cost in some cases.
          ReorderingModes[OpIdx] = ReorderingMode::Splat;
        else
          // NOTE: This should be unreachable.
          ReorderingModes[OpIdx] = ReorderingMode::Failed;
      }

      // Check that we don't have same operands. No need to reorder if operands
      // are just perfect diamond or shuffled diamond match. Do not do it only
      // for possible broadcasts or non-power of 2 number of scalars (just for
      // now).
      auto &&SkipReordering = [this]() {
        SmallPtrSet<Value *, 4> UniqueValues;
        ArrayRef<OperandData> Op0 = OpsVec.front();
        for (const OperandData &Data : Op0)
          UniqueValues.insert(Data.V);
        for (ArrayRef<OperandData> Op : drop_begin(OpsVec, 1)) {
          if (any_of(Op, [&UniqueValues](const OperandData &Data) {
                return !UniqueValues.contains(Data.V);
              }))
            return false;
        }
        // TODO: Check if we can remove a check for non-power-2 number of
        // scalars after full support of non-power-2 vectorization.
        return UniqueValues.size() != 2 && has_single_bit(UniqueValues.size());
      };

      // If the initial strategy fails for any of the operand indexes, then we
      // perform reordering again in a second pass. This helps avoid assigning
      // high priority to the failed strategy, and should improve reordering for
      // the non-failed operand indexes.
      for (int Pass = 0; Pass != 2; ++Pass) {
        // Check if no need to reorder operands since they're are perfect or
        // shuffled diamond match.
        // Need to do it to avoid extra external use cost counting for
        // shuffled matches, which may cause regressions.
        if (SkipReordering())
          break;
        // Skip the second pass if the first pass did not fail.
        bool StrategyFailed = false;
        // Mark all operand data as free to use.
        clearUsed();
        // We keep the original operand order for the FirstLane, so reorder the
        // rest of the lanes. We are visiting the nodes in a circular fashion,
        // using FirstLane as the center point and increasing the radius
        // distance.
        SmallVector<SmallVector<Value *, 2>> MainAltOps(NumOperands);
        for (unsigned I = 0; I < NumOperands; ++I)
          MainAltOps[I].push_back(getData(I, FirstLane).V);

        SmallBitVector UsedLanes(NumLanes);
        UsedLanes.set(FirstLane);
        for (unsigned Distance = 1; Distance != NumLanes; ++Distance) {
          // Visit the lane on the right and then the lane on the left.
          for (int Direction : {+1, -1}) {
            int Lane = FirstLane + Direction * Distance;
            if (Lane < 0 || Lane >= (int)NumLanes)
              continue;
            UsedLanes.set(Lane);
            int LastLane = Lane - Direction;
            assert(LastLane >= 0 && LastLane < (int)NumLanes &&
                   "Out of bounds");
            // Look for a good match for each operand.
            for (unsigned OpIdx = 0; OpIdx != NumOperands; ++OpIdx) {
              // Search for the operand that matches SortedOps[OpIdx][Lane-1].
              std::optional<unsigned> BestIdx =
                  getBestOperand(OpIdx, Lane, LastLane, ReorderingModes,
                                 MainAltOps[OpIdx], UsedLanes);
              // By not selecting a value, we allow the operands that follow to
              // select a better matching value. We will get a non-null value in
              // the next run of getBestOperand().
              if (BestIdx) {
                // Swap the current operand with the one returned by
                // getBestOperand().
                swap(OpIdx, *BestIdx, Lane);
              } else {
                // Enable the second pass.
                StrategyFailed = true;
              }
              // Try to get the alternate opcode and follow it during analysis.
              if (MainAltOps[OpIdx].size() != 2) {
                OperandData &AltOp = getData(OpIdx, Lane);
                InstructionsState OpS =
                    getSameOpcode({MainAltOps[OpIdx].front(), AltOp.V}, TLI);
                if (OpS.getOpcode() && OpS.isAltShuffle())
                  MainAltOps[OpIdx].push_back(AltOp.V);
              }
            }
          }
        }
        // Skip second pass if the strategy did not fail.
        if (!StrategyFailed)
          break;
      }
    }

#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
    LLVM_DUMP_METHOD static StringRef getModeStr(ReorderingMode RMode) {
      switch (RMode) {
      case ReorderingMode::Load:
        return "Load";
      case ReorderingMode::Opcode:
        return "Opcode";
      case ReorderingMode::Constant:
        return "Constant";
      case ReorderingMode::Splat:
        return "Splat";
      case ReorderingMode::Failed:
        return "Failed";
      }
      llvm_unreachable("Unimplemented Reordering Type");
    }

    LLVM_DUMP_METHOD static raw_ostream &printMode(ReorderingMode RMode,
                                                   raw_ostream &OS) {
      return OS << getModeStr(RMode);
    }

    /// Debug print.
    LLVM_DUMP_METHOD static void dumpMode(ReorderingMode RMode) {
      printMode(RMode, dbgs());
    }

    friend raw_ostream &operator<<(raw_ostream &OS, ReorderingMode RMode) {
      return printMode(RMode, OS);
    }

    LLVM_DUMP_METHOD raw_ostream &print(raw_ostream &OS) const {
      const unsigned Indent = 2;
      unsigned Cnt = 0;
      for (const OperandDataVec &OpDataVec : OpsVec) {
        OS << "Operand " << Cnt++ << "\n";
        for (const OperandData &OpData : OpDataVec) {
          OS.indent(Indent) << "{";
          if (Value *V = OpData.V)
            OS << *V;
          else
            OS << "null";
          OS << ", APO:" << OpData.APO << "}\n";
        }
        OS << "\n";
      }
      return OS;
    }

    /// Debug print.
    LLVM_DUMP_METHOD void dump() const { print(dbgs()); }
#endif
  };

  /// Evaluate each pair in \p Candidates and return index into \p Candidates
  /// for a pair which have highest score deemed to have best chance to form
  /// root of profitable tree to vectorize. Return std::nullopt if no candidate
  /// scored above the LookAheadHeuristics::ScoreFail. \param Limit Lower limit
  /// of the cost, considered to be good enough score.
  std::optional<int>
  findBestRootPair(ArrayRef<std::pair<Value *, Value *>> Candidates,
                   int Limit = LookAheadHeuristics::ScoreFail) const {
    LookAheadHeuristics LookAhead(*TLI, *DL, *SE, *this, /*NumLanes=*/2,
                                  RootLookAheadMaxDepth);
    int BestScore = Limit;
    std::optional<int> Index;
    for (int I : seq<int>(0, Candidates.size())) {
      int Score = LookAhead.getScoreAtLevelRec(Candidates[I].first,
                                               Candidates[I].second,
                                               /*U1=*/nullptr, /*U2=*/nullptr,
                                               /*CurrLevel=*/1, {});
      if (Score > BestScore) {
        BestScore = Score;
        Index = I;
      }
    }
    return Index;
  }

  /// Checks if the instruction is marked for deletion.
  bool isDeleted(Instruction *I) const { return DeletedInstructions.count(I); }

  /// Removes an instruction from its block and eventually deletes it.
  /// It's like Instruction::eraseFromParent() except that the actual deletion
  /// is delayed until BoUpSLP is destructed.
  void eraseInstruction(Instruction *I) {
    DeletedInstructions.insert(I);
  }

  /// Remove instructions from the parent function and clear the operands of \p
  /// DeadVals instructions, marking for deletion trivially dead operands.
  template <typename T>
  void removeInstructionsAndOperands(ArrayRef<T *> DeadVals) {
    SmallVector<WeakTrackingVH> DeadInsts;
    for (T *V : DeadVals) {
      auto *I = cast<Instruction>(V);
      DeletedInstructions.insert(I);
    }
    DenseSet<Value *> Processed;
    for (T *V : DeadVals) {
      if (!V || !Processed.insert(V).second)
        continue;
      auto *I = cast<Instruction>(V);
      salvageDebugInfo(*I);
      SmallVector<const TreeEntry *> Entries;
      if (const TreeEntry *Entry = getTreeEntry(I)) {
        Entries.push_back(Entry);
        auto It = MultiNodeScalars.find(I);
        if (It != MultiNodeScalars.end())
          Entries.append(It->second.begin(), It->second.end());
      }
      for (Use &U : I->operands()) {
        if (auto *OpI = dyn_cast_if_present<Instruction>(U.get());
            OpI && !DeletedInstructions.contains(OpI) && OpI->hasOneUser() &&
            wouldInstructionBeTriviallyDead(OpI, TLI) &&
            (Entries.empty() || none_of(Entries, [&](const TreeEntry *Entry) {
               return Entry->VectorizedValue == OpI;
             })))
          DeadInsts.push_back(OpI);
      }
      I->dropAllReferences();
    }
    for (T *V : DeadVals) {
      auto *I = cast<Instruction>(V);
      if (!I->getParent())
        continue;
      assert((I->use_empty() || all_of(I->uses(),
                                       [&](Use &U) {
                                         return isDeleted(
                                             cast<Instruction>(U.getUser()));
                                       })) &&
             "trying to erase instruction with users.");
      I->removeFromParent();
      SE->forgetValue(I);
    }
    // Process the dead instruction list until empty.
    while (!DeadInsts.empty()) {
      Value *V = DeadInsts.pop_back_val();
      Instruction *VI = cast_or_null<Instruction>(V);
      if (!VI || !VI->getParent())
        continue;
      assert(isInstructionTriviallyDead(VI, TLI) &&
             "Live instruction found in dead worklist!");
      assert(VI->use_empty() && "Instructions with uses are not dead.");

      // Don't lose the debug info while deleting the instructions.
      salvageDebugInfo(*VI);

      // Null out all of the instruction's operands to see if any operand
      // becomes dead as we go.
      for (Use &OpU : VI->operands()) {
        Value *OpV = OpU.get();
        if (!OpV)
          continue;
        OpU.set(nullptr);

        if (!OpV->use_empty())
          continue;

        // If the operand is an instruction that became dead as we nulled out
        // the operand, and if it is 'trivially' dead, delete it in a future
        // loop iteration.
        if (auto *OpI = dyn_cast<Instruction>(OpV))
          if (!DeletedInstructions.contains(OpI) &&
              isInstructionTriviallyDead(OpI, TLI))
            DeadInsts.push_back(OpI);
      }

      VI->removeFromParent();
      DeletedInstructions.insert(VI);
      SE->forgetValue(VI);
    }
  }

  /// Checks if the instruction was already analyzed for being possible
  /// reduction root.
  bool isAnalyzedReductionRoot(Instruction *I) const {
    return AnalyzedReductionsRoots.count(I);
  }
  /// Register given instruction as already analyzed for being possible
  /// reduction root.
  void analyzedReductionRoot(Instruction *I) {
    AnalyzedReductionsRoots.insert(I);
  }
  /// Checks if the provided list of reduced values was checked already for
  /// vectorization.
  bool areAnalyzedReductionVals(ArrayRef<Value *> VL) const {
    return AnalyzedReductionVals.contains(hash_value(VL));
  }
  /// Adds the list of reduced values to list of already checked values for the
  /// vectorization.
  void analyzedReductionVals(ArrayRef<Value *> VL) {
    AnalyzedReductionVals.insert(hash_value(VL));
  }
  /// Clear the list of the analyzed reduction root instructions.
  void clearReductionData() {
    AnalyzedReductionsRoots.clear();
    AnalyzedReductionVals.clear();
    AnalyzedMinBWVals.clear();
  }
  /// Checks if the given value is gathered in one of the nodes.
  bool isAnyGathered(const SmallDenseSet<Value *> &Vals) const {
    return any_of(MustGather, [&](Value *V) { return Vals.contains(V); });
  }
  /// Checks if the given value is gathered in one of the nodes.
  bool isGathered(const Value *V) const {
    return MustGather.contains(V);
  }
  /// Checks if the specified value was not schedule.
  bool isNotScheduled(const Value *V) const {
    return NonScheduledFirst.contains(V);
  }

  /// Check if the value is vectorized in the tree.
  bool isVectorized(Value *V) const { return getTreeEntry(V); }

  ~BoUpSLP();

private:
  /// Determine if a node \p E in can be demoted to a smaller type with a
  /// truncation. We collect the entries that will be demoted in ToDemote.
  /// \param E Node for analysis
  /// \param ToDemote indices of the nodes to be demoted.
  bool collectValuesToDemote(const TreeEntry &E, bool IsProfitableToDemoteRoot,
                             unsigned &BitWidth,
                             SmallVectorImpl<unsigned> &ToDemote,
                             DenseSet<const TreeEntry *> &Visited,
                             unsigned &MaxDepthLevel,
                             bool &IsProfitableToDemote,
                             bool IsTruncRoot) const;

  /// Check if the operands on the edges \p Edges of the \p UserTE allows
  /// reordering (i.e. the operands can be reordered because they have only one
  /// user and reordarable).
  /// \param ReorderableGathers List of all gather nodes that require reordering
  /// (e.g., gather of extractlements or partially vectorizable loads).
  /// \param GatherOps List of gather operand nodes for \p UserTE that require
  /// reordering, subset of \p NonVectorized.
  bool
  canReorderOperands(TreeEntry *UserTE,
                     SmallVectorImpl<std::pair<unsigned, TreeEntry *>> &Edges,
                     ArrayRef<TreeEntry *> ReorderableGathers,
                     SmallVectorImpl<TreeEntry *> &GatherOps);

  /// Checks if the given \p TE is a gather node with clustered reused scalars
  /// and reorders it per given \p Mask.
  void reorderNodeWithReuses(TreeEntry &TE, ArrayRef<int> Mask) const;

  /// Returns vectorized operand \p OpIdx of the node \p UserTE from the graph,
  /// if any. If it is not vectorized (gather node), returns nullptr.
  TreeEntry *getVectorizedOperand(TreeEntry *UserTE, unsigned OpIdx) {
    ArrayRef<Value *> VL = UserTE->getOperand(OpIdx);
    TreeEntry *TE = nullptr;
    const auto *It = find_if(VL, [&](Value *V) {
      TE = getTreeEntry(V);
      if (TE && is_contained(TE->UserTreeIndices, EdgeInfo(UserTE, OpIdx)))
        return true;
      auto It = MultiNodeScalars.find(V);
      if (It != MultiNodeScalars.end()) {
        for (TreeEntry *E : It->second) {
          if (is_contained(E->UserTreeIndices, EdgeInfo(UserTE, OpIdx))) {
            TE = E;
            return true;
          }
        }
      }
      return false;
    });
    if (It != VL.end()) {
      assert(TE->isSame(VL) && "Expected same scalars.");
      return TE;
    }
    return nullptr;
  }

  /// Returns vectorized operand \p OpIdx of the node \p UserTE from the graph,
  /// if any. If it is not vectorized (gather node), returns nullptr.
  const TreeEntry *getVectorizedOperand(const TreeEntry *UserTE,
                                        unsigned OpIdx) const {
    return const_cast<BoUpSLP *>(this)->getVectorizedOperand(
        const_cast<TreeEntry *>(UserTE), OpIdx);
  }

  /// Checks if all users of \p I are the part of the vectorization tree.
  bool areAllUsersVectorized(
      Instruction *I,
      const SmallDenseSet<Value *> *VectorizedVals = nullptr) const;

  /// Return information about the vector formed for the specified index
  /// of a vector of (the same) instruction.
  TargetTransformInfo::OperandValueInfo getOperandInfo(ArrayRef<Value *> Ops);

  /// \ returns the graph entry for the \p Idx operand of the \p E entry.
  const TreeEntry *getOperandEntry(const TreeEntry *E, unsigned Idx) const;

  /// Gets the root instruction for the given node. If the node is a strided
  /// load/store node with the reverse order, the root instruction is the last
  /// one.
  Instruction *getRootEntryInstruction(const TreeEntry &Entry) const;

  /// \returns Cast context for the given graph node.
  TargetTransformInfo::CastContextHint
  getCastContextHint(const TreeEntry &TE) const;

  /// \returns the cost of the vectorizable entry.
  InstructionCost getEntryCost(const TreeEntry *E,
                               ArrayRef<Value *> VectorizedVals,
                               SmallPtrSetImpl<Value *> &CheckedExtracts);

  /// This is the recursive part of buildTree.
  void buildTree_rec(ArrayRef<Value *> Roots, unsigned Depth,
                     const EdgeInfo &EI);

  /// \returns true if the ExtractElement/ExtractValue instructions in \p VL can
  /// be vectorized to use the original vector (or aggregate "bitcast" to a
  /// vector) and sets \p CurrentOrder to the identity permutation; otherwise
  /// returns false, setting \p CurrentOrder to either an empty vector or a
  /// non-identity permutation that allows to reuse extract instructions.
  /// \param ResizeAllowed indicates whether it is allowed to handle subvector
  /// extract order.
  bool canReuseExtract(ArrayRef<Value *> VL, Value *OpValue,
                       SmallVectorImpl<unsigned> &CurrentOrder,
                       bool ResizeAllowed = false) const;

  /// Vectorize a single entry in the tree.
  /// \param PostponedPHIs true, if need to postpone emission of phi nodes to
  /// avoid issues with def-use order.
  Value *vectorizeTree(TreeEntry *E, bool PostponedPHIs);

  /// Returns vectorized operand node, that matches the order of the scalars
  /// operand number \p NodeIdx in entry \p E.
  TreeEntry *getMatchedVectorizedOperand(const TreeEntry *E, unsigned NodeIdx);
  const TreeEntry *getMatchedVectorizedOperand(const TreeEntry *E,
                                               unsigned NodeIdx) const {
    return const_cast<BoUpSLP *>(this)->getMatchedVectorizedOperand(E, NodeIdx);
  }

  /// Vectorize a single entry in the tree, the \p Idx-th operand of the entry
  /// \p E.
  /// \param PostponedPHIs true, if need to postpone emission of phi nodes to
  /// avoid issues with def-use order.
  Value *vectorizeOperand(TreeEntry *E, unsigned NodeIdx, bool PostponedPHIs);

  /// Create a new vector from a list of scalar values.  Produces a sequence
  /// which exploits values reused across lanes, and arranges the inserts
  /// for ease of later optimization.
  template <typename BVTy, typename ResTy, typename... Args>
  ResTy processBuildVector(const TreeEntry *E, Type *ScalarTy, Args &...Params);

  /// Create a new vector from a list of scalar values.  Produces a sequence
  /// which exploits values reused across lanes, and arranges the inserts
  /// for ease of later optimization.
  Value *createBuildVector(const TreeEntry *E, Type *ScalarTy,
                           bool PostponedPHIs);

  /// Returns the instruction in the bundle, which can be used as a base point
  /// for scheduling. Usually it is the last instruction in the bundle, except
  /// for the case when all operands are external (in this case, it is the first
  /// instruction in the list).
  Instruction &getLastInstructionInBundle(const TreeEntry *E);

  /// Tries to find extractelement instructions with constant indices from fixed
  /// vector type and gather such instructions into a bunch, which highly likely
  /// might be detected as a shuffle of 1 or 2 input vectors. If this attempt
  /// was successful, the matched scalars are replaced by poison values in \p VL
  /// for future analysis.
  std::optional<TargetTransformInfo::ShuffleKind>
  tryToGatherSingleRegisterExtractElements(MutableArrayRef<Value *> VL,
                                           SmallVectorImpl<int> &Mask) const;

  /// Tries to find extractelement instructions with constant indices from fixed
  /// vector type and gather such instructions into a bunch, which highly likely
  /// might be detected as a shuffle of 1 or 2 input vectors. If this attempt
  /// was successful, the matched scalars are replaced by poison values in \p VL
  /// for future analysis.
  SmallVector<std::optional<TargetTransformInfo::ShuffleKind>>
  tryToGatherExtractElements(SmallVectorImpl<Value *> &VL,
                             SmallVectorImpl<int> &Mask,
                             unsigned NumParts) const;

  /// Checks if the gathered \p VL can be represented as a single register
  /// shuffle(s) of previous tree entries.
  /// \param TE Tree entry checked for permutation.
  /// \param VL List of scalars (a subset of the TE scalar), checked for
  /// permutations. Must form single-register vector.
  /// \param ForOrder Tries to fetch the best candidates for ordering info. Also
  /// commands to build the mask using the original vector value, without
  /// relying on the potential reordering.
  /// \returns ShuffleKind, if gathered values can be represented as shuffles of
  /// previous tree entries. \p Part of \p Mask is filled with the shuffle mask.
  std::optional<TargetTransformInfo::ShuffleKind>
  isGatherShuffledSingleRegisterEntry(
      const TreeEntry *TE, ArrayRef<Value *> VL, MutableArrayRef<int> Mask,
      SmallVectorImpl<const TreeEntry *> &Entries, unsigned Part,
      bool ForOrder);

  /// Checks if the gathered \p VL can be represented as multi-register
  /// shuffle(s) of previous tree entries.
  /// \param TE Tree entry checked for permutation.
  /// \param VL List of scalars (a subset of the TE scalar), checked for
  /// permutations.
  /// \param ForOrder Tries to fetch the best candidates for ordering info. Also
  /// commands to build the mask using the original vector value, without
  /// relying on the potential reordering.
  /// \returns per-register series of ShuffleKind, if gathered values can be
  /// represented as shuffles of previous tree entries. \p Mask is filled with
  /// the shuffle mask (also on per-register base).
  SmallVector<std::optional<TargetTransformInfo::ShuffleKind>>
  isGatherShuffledEntry(
      const TreeEntry *TE, ArrayRef<Value *> VL, SmallVectorImpl<int> &Mask,
      SmallVectorImpl<SmallVector<const TreeEntry *>> &Entries,
      unsigned NumParts, bool ForOrder = false);

  /// \returns the scalarization cost for this list of values. Assuming that
  /// this subtree gets vectorized, we may need to extract the values from the
  /// roots. This method calculates the cost of extracting the values.
  /// \param ForPoisonSrc true if initial vector is poison, false otherwise.
  InstructionCost getGatherCost(ArrayRef<Value *> VL, bool ForPoisonSrc,
                                Type *ScalarTy) const;

  /// Set the Builder insert point to one after the last instruction in
  /// the bundle
  void setInsertPointAfterBundle(const TreeEntry *E);

  /// \returns a vector from a collection of scalars in \p VL. if \p Root is not
  /// specified, the starting vector value is poison.
  Value *gather(ArrayRef<Value *> VL, Value *Root, Type *ScalarTy);

  /// \returns whether the VectorizableTree is fully vectorizable and will
  /// be beneficial even the tree height is tiny.
  bool isFullyVectorizableTinyTree(bool ForReduction) const;

  /// Run through the list of all gathered loads in the graph and try to find
  /// vector loads/masked gathers instead of regular gathers. Later these loads
  /// are reshufled to build final gathered nodes.
  void tryToVectorizeGatheredLoads(
      ArrayRef<SmallVector<std::pair<LoadInst *, int>>> GatheredLoads);

  /// Reorder commutative or alt operands to get better probability of
  /// generating vectorized code.
  static void reorderInputsAccordingToOpcode(ArrayRef<Value *> VL,
                                             SmallVectorImpl<Value *> &Left,
                                             SmallVectorImpl<Value *> &Right,
                                             const BoUpSLP &R);

  /// Helper for `findExternalStoreUsersReorderIndices()`. It iterates over the
  /// users of \p TE and collects the stores. It returns the map from the store
  /// pointers to the collected stores.
  DenseMap<Value *, SmallVector<StoreInst *>>
  collectUserStores(const BoUpSLP::TreeEntry *TE) const;

  /// Helper for `findExternalStoreUsersReorderIndices()`. It checks if the
  /// stores in \p StoresVec can form a vector instruction. If so it returns
  /// true and populates \p ReorderIndices with the shuffle indices of the
  /// stores when compared to the sorted vector.
  bool canFormVector(ArrayRef<StoreInst *> StoresVec,
                     OrdersType &ReorderIndices) const;

  /// Iterates through the users of \p TE, looking for scalar stores that can be
  /// potentially vectorized in a future SLP-tree. If found, it keeps track of
  /// their order and builds an order index vector for each store bundle. It
  /// returns all these order vectors found.
  /// We run this after the tree has formed, otherwise we may come across user
  /// instructions that are not yet in the tree.
  SmallVector<OrdersType, 1>
  findExternalStoreUsersReorderIndices(TreeEntry *TE) const;

  struct TreeEntry {
    using VecTreeTy = SmallVector<std::unique_ptr<TreeEntry>, 8>;
    TreeEntry(VecTreeTy &Container) : Container(Container) {}

    /// \returns Common mask for reorder indices and reused scalars.
    SmallVector<int> getCommonMask() const {
      SmallVector<int> Mask;
      inversePermutation(ReorderIndices, Mask);
      ::addMask(Mask, ReuseShuffleIndices);
      return Mask;
    }

    /// \returns true if the scalars in VL are equal to this entry.
    bool isSame(ArrayRef<Value *> VL) const {
      auto &&IsSame = [VL](ArrayRef<Value *> Scalars, ArrayRef<int> Mask) {
        if (Mask.size() != VL.size() && VL.size() == Scalars.size())
          return std::equal(VL.begin(), VL.end(), Scalars.begin());
        return VL.size() == Mask.size() &&
               std::equal(VL.begin(), VL.end(), Mask.begin(),
                          [Scalars](Value *V, int Idx) {
                            return (isa<UndefValue>(V) &&
                                    Idx == PoisonMaskElem) ||
                                   (Idx != PoisonMaskElem && V == Scalars[Idx]);
                          });
      };
      if (!ReorderIndices.empty()) {
        // TODO: implement matching if the nodes are just reordered, still can
        // treat the vector as the same if the list of scalars matches VL
        // directly, without reordering.
        SmallVector<int> Mask;
        inversePermutation(ReorderIndices, Mask);
        if (VL.size() == Scalars.size())
          return IsSame(Scalars, Mask);
        if (VL.size() == ReuseShuffleIndices.size()) {
          ::addMask(Mask, ReuseShuffleIndices);
          return IsSame(Scalars, Mask);
        }
        return false;
      }
      return IsSame(Scalars, ReuseShuffleIndices);
    }

    bool isOperandGatherNode(const EdgeInfo &UserEI) const {
      return isGather() && !UserTreeIndices.empty() &&
             UserTreeIndices.front().EdgeIdx == UserEI.EdgeIdx &&
             UserTreeIndices.front().UserTE == UserEI.UserTE;
    }

    /// \returns true if current entry has same operands as \p TE.
    bool hasEqualOperands(const TreeEntry &TE) const {
      if (TE.getNumOperands() != getNumOperands())
        return false;
      SmallBitVector Used(getNumOperands());
      for (unsigned I = 0, E = getNumOperands(); I < E; ++I) {
        unsigned PrevCount = Used.count();
        for (unsigned K = 0; K < E; ++K) {
          if (Used.test(K))
            continue;
          if (getOperand(K) == TE.getOperand(I)) {
            Used.set(K);
            break;
          }
        }
        // Check if we actually found the matching operand.
        if (PrevCount == Used.count())
          return false;
      }
      return true;
    }

    /// \return Final vectorization factor for the node. Defined by the total
    /// number of vectorized scalars, including those, used several times in the
    /// entry and counted in the \a ReuseShuffleIndices, if any.
    unsigned getVectorFactor() const {
      if (!ReuseShuffleIndices.empty())
        return ReuseShuffleIndices.size();
      return Scalars.size();
    };

    /// Checks if the current node is a gather node.
    bool isGather() const {return State == NeedToGather; }

    /// A vector of scalars.
    ValueList Scalars;

    /// The Scalars are vectorized into this value. It is initialized to Null.
    WeakTrackingVH VectorizedValue = nullptr;

    /// New vector phi instructions emitted for the vectorized phi nodes.
    PHINode *PHI = nullptr;

    /// Do we need to gather this sequence or vectorize it
    /// (either with vector instruction or with scatter/gather
    /// intrinsics for store/load)?
    enum EntryState {
      Vectorize,         ///< The node is regularly vectorized.
      ScatterVectorize,  ///< Masked scatter/gather node.
      StridedVectorize,  ///< Strided loads (and stores)
      NeedToGather,      ///< Gather/buildvector node.
      CombinedVectorize, ///< Vectorized node, combined with its user into more
                         ///< complex node like select/cmp to minmax, mul/add to
                         ///< fma, etc. Must be used for the following nodes in
                         ///< the pattern, not the very first one.
    };
    EntryState State;

    /// List of combined opcodes supported by the vectorizer.
    enum CombinedOpcode {
      NotCombinedOp = -1,
      MinMax = Instruction::OtherOpsEnd + 1,
    };
    CombinedOpcode CombinedOp = NotCombinedOp;

    /// Does this sequence require some shuffling?
    SmallVector<int, 4> ReuseShuffleIndices;

    /// Does this entry require reordering?
    SmallVector<unsigned, 4> ReorderIndices;

    /// Points back to the VectorizableTree.
    ///
    /// Only used for Graphviz right now.  Unfortunately GraphTrait::NodeRef has
    /// to be a pointer and needs to be able to initialize the child iterator.
    /// Thus we need a reference back to the container to translate the indices
    /// to entries.
    VecTreeTy &Container;

    /// The TreeEntry index containing the user of this entry.  We can actually
    /// have multiple users so the data structure is not truly a tree.
    SmallVector<EdgeInfo, 1> UserTreeIndices;

    /// The index of this treeEntry in VectorizableTree.
    int Idx = -1;

    /// For gather/buildvector/alt opcode (TODO) nodes, which are combined from
    /// other nodes as a series of insertvector instructions.
    SmallVector<std::pair<unsigned, unsigned>, 0> CombinedEntriesWithIndices;

  private:
    /// The operands of each instruction in each lane Operands[op_index][lane].
    /// Note: This helps avoid the replication of the code that performs the
    /// reordering of operands during buildTree_rec() and vectorizeTree().
    SmallVector<ValueList, 2> Operands;

    /// The main/alternate instruction.
    Instruction *MainOp = nullptr;
    Instruction *AltOp = nullptr;

  public:
    /// Set this bundle's \p OpIdx'th operand to \p OpVL.
    void setOperand(unsigned OpIdx, ArrayRef<Value *> OpVL) {
      if (Operands.size() < OpIdx + 1)
        Operands.resize(OpIdx + 1);
      assert(Operands[OpIdx].empty() && "Already resized?");
      assert(OpVL.size() <= Scalars.size() &&
             "Number of operands is greater than the number of scalars.");
      Operands[OpIdx].resize(OpVL.size());
      copy(OpVL, Operands[OpIdx].begin());
    }

    /// Set the operands of this bundle in their original order.
    void setOperandsInOrder() {
      assert(Operands.empty() && "Already initialized?");
      auto *I0 = cast<Instruction>(Scalars[0]);
      Operands.resize(I0->getNumOperands());
      unsigned NumLanes = Scalars.size();
      for (unsigned OpIdx = 0, NumOperands = I0->getNumOperands();
           OpIdx != NumOperands; ++OpIdx) {
        Operands[OpIdx].resize(NumLanes);
        for (unsigned Lane = 0; Lane != NumLanes; ++Lane) {
          auto *I = cast<Instruction>(Scalars[Lane]);
          assert(I->getNumOperands() == NumOperands &&
                 "Expected same number of operands");
          Operands[OpIdx][Lane] = I->getOperand(OpIdx);
        }
      }
    }

    /// Reorders operands of the node to the given mask \p Mask.
    void reorderOperands(ArrayRef<int> Mask) {
      for (ValueList &Operand : Operands)
        reorderScalars(Operand, Mask);
    }

    /// \returns the \p OpIdx operand of this TreeEntry.
    ValueList &getOperand(unsigned OpIdx) {
      assert(OpIdx < Operands.size() && "Off bounds");
      return Operands[OpIdx];
    }

    /// \returns the \p OpIdx operand of this TreeEntry.
    ArrayRef<Value *> getOperand(unsigned OpIdx) const {
      assert(OpIdx < Operands.size() && "Off bounds");
      return Operands[OpIdx];
    }

    /// \returns the number of operands.
    unsigned getNumOperands() const { return Operands.size(); }

    /// \return the single \p OpIdx operand.
    Value *getSingleOperand(unsigned OpIdx) const {
      assert(OpIdx < Operands.size() && "Off bounds");
      assert(!Operands[OpIdx].empty() && "No operand available");
      return Operands[OpIdx][0];
    }

    /// Some of the instructions in the list have alternate opcodes.
    bool isAltShuffle() const { return MainOp != AltOp; }

    bool isOpcodeOrAlt(Instruction *I) const {
      unsigned CheckedOpcode = I->getOpcode();
      return (getOpcode() == CheckedOpcode ||
              getAltOpcode() == CheckedOpcode);
    }

    /// Chooses the correct key for scheduling data. If \p Op has the same (or
    /// alternate) opcode as \p OpValue, the key is \p Op. Otherwise the key is
    /// \p OpValue.
    Value *isOneOf(Value *Op) const {
      auto *I = dyn_cast<Instruction>(Op);
      if (I && isOpcodeOrAlt(I))
        return Op;
      return MainOp;
    }

    void setOperations(const InstructionsState &S) {
      MainOp = S.MainOp;
      AltOp = S.AltOp;
    }

    Instruction *getMainOp() const {
      return MainOp;
    }

    Instruction *getAltOp() const {
      return AltOp;
    }

    /// The main/alternate opcodes for the list of instructions.
    unsigned getOpcode() const {
      return MainOp ? MainOp->getOpcode() : 0;
    }

    unsigned getAltOpcode() const {
      return AltOp ? AltOp->getOpcode() : 0;
    }

    /// When ReuseReorderShuffleIndices is empty it just returns position of \p
    /// V within vector of Scalars. Otherwise, try to remap on its reuse index.
    int findLaneForValue(Value *V) const {
      unsigned FoundLane = getVectorFactor();
      for (auto *It = find(Scalars, V), *End = Scalars.end(); It != End;
           std::advance(It, 1)) {
        if (*It != V)
          continue;
        FoundLane = std::distance(Scalars.begin(), It);
        assert(FoundLane < Scalars.size() && "Couldn't find extract lane");
        if (!ReorderIndices.empty())
          FoundLane = ReorderIndices[FoundLane];
        assert(FoundLane < Scalars.size() && "Couldn't find extract lane");
        if (ReuseShuffleIndices.empty())
          break;
        if (auto *RIt = find(ReuseShuffleIndices, FoundLane);
            RIt != ReuseShuffleIndices.end()) {
          FoundLane = std::distance(ReuseShuffleIndices.begin(), RIt);
          break;
        }
      }
      assert(FoundLane < getVectorFactor() && "Unable to find given value.");
      return FoundLane;
    }

    /// Build a shuffle mask for graph entry which represents a merge of main
    /// and alternate operations.
    void
    buildAltOpShuffleMask(const function_ref<bool(Instruction *)> IsAltOp,
                          SmallVectorImpl<int> &Mask,
                          SmallVectorImpl<Value *> *OpScalars = nullptr,
                          SmallVectorImpl<Value *> *AltScalars = nullptr) const;

    /// Return true if this is a non-power-of-2 node.
    bool isNonPowOf2Vec() const {
      bool IsNonPowerOf2 = !has_single_bit(Scalars.size());
      assert((!IsNonPowerOf2 || ReuseShuffleIndices.empty()) &&
             "Reshuffling not supported with non-power-of-2 vectors yet.");
      return IsNonPowerOf2;
    }

#ifndef NDEBUG
    /// Debug printer.
    LLVM_DUMP_METHOD void dump() const {
      dbgs() << Idx << ".\n";
      for (unsigned OpI = 0, OpE = Operands.size(); OpI != OpE; ++OpI) {
        dbgs() << "Operand " << OpI << ":\n";
        for (const Value *V : Operands[OpI])
          dbgs().indent(2) << *V << "\n";
      }
      dbgs() << "Scalars: \n";
      for (Value *V : Scalars)
        dbgs().indent(2) << *V << "\n";
      dbgs() << "State: ";
      switch (State) {
      case Vectorize:
        dbgs() << "Vectorize\n";
        break;
      case ScatterVectorize:
        dbgs() << "ScatterVectorize\n";
        break;
      case StridedVectorize:
        dbgs() << "StridedVectorize\n";
        break;
      case NeedToGather:
        dbgs() << "NeedToGather\n";
        break;
      case CombinedVectorize:
        dbgs() << "CombinedVectorize\n";
        break;
      }
      dbgs() << "MainOp: ";
      if (MainOp)
        dbgs() << *MainOp << "\n";
      else
        dbgs() << "NULL\n";
      dbgs() << "AltOp: ";
      if (AltOp)
        dbgs() << *AltOp << "\n";
      else
        dbgs() << "NULL\n";
      dbgs() << "VectorizedValue: ";
      if (VectorizedValue)
        dbgs() << *VectorizedValue << "\n";
      else
        dbgs() << "NULL\n";
      dbgs() << "ReuseShuffleIndices: ";
      if (ReuseShuffleIndices.empty())
        dbgs() << "Empty";
      else
        for (int ReuseIdx : ReuseShuffleIndices)
          dbgs() << ReuseIdx << ", ";
      dbgs() << "\n";
      dbgs() << "ReorderIndices: ";
      for (unsigned ReorderIdx : ReorderIndices)
        dbgs() << ReorderIdx << ", ";
      dbgs() << "\n";
      dbgs() << "UserTreeIndices: ";
      for (const auto &EInfo : UserTreeIndices)
        dbgs() << EInfo << ", ";
      dbgs() << "\n";
    }
#endif
  };

#ifndef NDEBUG
  void dumpTreeCosts(const TreeEntry *E, InstructionCost ReuseShuffleCost,
                     InstructionCost VecCost, InstructionCost ScalarCost,
                     StringRef Banner) const {
    dbgs() << "SLP: " << Banner << ":\n";
    E->dump();
    dbgs() << "SLP: Costs:\n";
    dbgs() << "SLP:     ReuseShuffleCost = " << ReuseShuffleCost << "\n";
    dbgs() << "SLP:     VectorCost = " << VecCost << "\n";
    dbgs() << "SLP:     ScalarCost = " << ScalarCost << "\n";
    dbgs() << "SLP:     ReuseShuffleCost + VecCost - ScalarCost = "
           << ReuseShuffleCost + VecCost - ScalarCost << "\n";
  }
#endif

  /// Create a new VectorizableTree entry.
  TreeEntry *newTreeEntry(ArrayRef<Value *> VL,
                          std::optional<ScheduleData *> Bundle,
                          const InstructionsState &S,
                          const EdgeInfo &UserTreeIdx,
                          ArrayRef<int> ReuseShuffleIndices = {},
                          ArrayRef<unsigned> ReorderIndices = {}) {
    TreeEntry::EntryState EntryState =
        Bundle ? TreeEntry::Vectorize : TreeEntry::NeedToGather;
    return newTreeEntry(VL, EntryState, Bundle, S, UserTreeIdx,
                        ReuseShuffleIndices, ReorderIndices);
  }

  TreeEntry *newTreeEntry(ArrayRef<Value *> VL,
                          TreeEntry::EntryState EntryState,
                          std::optional<ScheduleData *> Bundle,
                          const InstructionsState &S,
                          const EdgeInfo &UserTreeIdx,
                          ArrayRef<int> ReuseShuffleIndices = {},
                          ArrayRef<unsigned> ReorderIndices = {}) {
    assert(((!Bundle && EntryState == TreeEntry::NeedToGather) ||
            (Bundle && EntryState != TreeEntry::NeedToGather)) &&
           "Need to vectorize gather entry?");
    // Gathered loads still gathered? Do not create entry, use the original one.
    if (GatheredLoadsEntriesFirst != NoGatheredLoads &&
        EntryState == TreeEntry::NeedToGather &&
        S.getOpcode() == Instruction::Load && UserTreeIdx.EdgeIdx == UINT_MAX &&
        !UserTreeIdx.UserTE)
      return nullptr;
    VectorizableTree.push_back(std::make_unique<TreeEntry>(VectorizableTree));
    TreeEntry *Last = VectorizableTree.back().get();
    Last->Idx = VectorizableTree.size() - 1;
    Last->State = EntryState;
    // FIXME: Remove once support for ReuseShuffleIndices has been implemented
    // for non-power-of-two vectors.
    assert((has_single_bit(VL.size()) || ReuseShuffleIndices.empty()) &&
           "Reshuffling scalars not yet supported for nodes with padding");
    Last->ReuseShuffleIndices.append(ReuseShuffleIndices.begin(),
                                     ReuseShuffleIndices.end());
    if (ReorderIndices.empty()) {
      Last->Scalars.assign(VL.begin(), VL.end());
      Last->setOperations(S);
    } else {
      // Reorder scalars and build final mask.
      Last->Scalars.assign(VL.size(), nullptr);
      transform(ReorderIndices, Last->Scalars.begin(),
                [VL](unsigned Idx) -> Value * {
                  if (Idx >= VL.size())
                    return UndefValue::get(VL.front()->getType());
                  return VL[Idx];
                });
      InstructionsState S = getSameOpcode(Last->Scalars, *TLI);
      Last->setOperations(S);
      Last->ReorderIndices.append(ReorderIndices.begin(), ReorderIndices.end());
    }
    if (!Last->isGather()) {
      for (Value *V : VL) {
        const TreeEntry *TE = getTreeEntry(V);
        assert((!TE || TE == Last || doesNotNeedToBeScheduled(V)) &&
               "Scalar already in tree!");
        if (TE) {
          if (TE != Last)
            MultiNodeScalars.try_emplace(V).first->getSecond().push_back(Last);
          continue;
        }
        ScalarToTreeEntry[V] = Last;
      }
      // Update the scheduler bundle to point to this TreeEntry.
      ScheduleData *BundleMember = *Bundle;
      assert((BundleMember || isa<PHINode>(S.MainOp) ||
              isVectorLikeInstWithConstOps(S.MainOp) ||
              doesNotNeedToSchedule(VL)) &&
             "Bundle and VL out of sync");
      if (BundleMember) {
        for (Value *V : VL) {
          if (doesNotNeedToBeScheduled(V))
            continue;
          if (!BundleMember)
            continue;
          BundleMember->TE = Last;
          BundleMember = BundleMember->NextInBundle;
        }
      }
      assert(!BundleMember && "Bundle and VL out of sync");
    } else {
      // Build a map for gathered scalars to the nodes where they are used.
      bool AllConstsOrCasts = true;
      for (Value *V : VL)
        if (!isConstant(V)) {
          auto *I = dyn_cast<CastInst>(V);
          AllConstsOrCasts &= I && I->getType()->isIntegerTy();
          if (UserTreeIdx.EdgeIdx != UINT_MAX || !UserTreeIdx.UserTE ||
              !UserTreeIdx.UserTE->isGather())
            ValueToGatherNodes.try_emplace(V).first->getSecond().insert(Last);
        }
      if (AllConstsOrCasts)
        CastMaxMinBWSizes =
            std::make_pair(std::numeric_limits<unsigned>::max(), 1);
      MustGather.insert(VL.begin(), VL.end());
    }

    if (UserTreeIdx.UserTE)
      Last->UserTreeIndices.push_back(UserTreeIdx);
    return Last;
  }

  /// -- Vectorization State --
  /// Holds all of the tree entries.
  TreeEntry::VecTreeTy VectorizableTree;

#ifndef NDEBUG
  /// Debug printer.
  LLVM_DUMP_METHOD void dumpVectorizableTree() const {
    for (unsigned Id = 0, IdE = VectorizableTree.size(); Id != IdE; ++Id) {
      VectorizableTree[Id]->dump();
      dbgs() << "\n";
    }
  }
#endif

  TreeEntry *getTreeEntry(Value *V) { return ScalarToTreeEntry.lookup(V); }

  const TreeEntry *getTreeEntry(Value *V) const {
    return ScalarToTreeEntry.lookup(V);
  }

  /// Check that the operand node of alternate node does not generate
  /// buildvector sequence. If it is, then probably not worth it to build
  /// alternate shuffle, if number of buildvector operands + alternate
  /// instruction > than the number of buildvector instructions.
  /// \param S the instructions state of the analyzed values.
  /// \param VL list of the instructions with alternate opcodes.
  bool areAltOperandsProfitable(const InstructionsState &S,
                                ArrayRef<Value *> VL) const;

  /// Checks if the specified list of the instructions/values can be vectorized
  /// and fills required data before actual scheduling of the instructions.
  TreeEntry::EntryState getScalarsVectorizationState(
      InstructionsState &S, ArrayRef<Value *> VL, bool IsScatterVectorizeUserTE,
      OrdersType &CurrentOrder, SmallVectorImpl<Value *> &PointerOps);

  /// Maps a specific scalar to its tree entry.
  SmallDenseMap<Value *, TreeEntry *> ScalarToTreeEntry;

  /// List of scalars, used in several vectorize nodes, and the list of the
  /// nodes.
  SmallDenseMap<Value *, SmallVector<TreeEntry *>> MultiNodeScalars;

  /// Maps a value to the proposed vectorizable size.
  SmallDenseMap<Value *, unsigned> InstrElementSize;

  /// A list of scalars that we found that we need to keep as scalars.
  ValueSet MustGather;

  /// A set of first non-schedulable values.
  ValueSet NonScheduledFirst;

  /// A map between the vectorized entries and the last instructions in the
  /// bundles. The bundles are built in use order, not in the def order of the
  /// instructions. So, we cannot rely directly on the last instruction in the
  /// bundle being the last instruction in the program order during
  /// vectorization process since the basic blocks are affected, need to
  /// pre-gather them before.
  DenseMap<const TreeEntry *, Instruction *> EntryToLastInstruction;

  /// List of gather nodes, depending on other gather/vector nodes, which should
  /// be emitted after the vector instruction emission process to correctly
  /// handle order of the vector instructions and shuffles.
  SetVector<const TreeEntry *> PostponedGathers;

  using ValueToGatherNodesMap =
      DenseMap<Value *, SmallPtrSet<const TreeEntry *, 4>>;
  ValueToGatherNodesMap ValueToGatherNodes;

  /// The index of the first gathered load entry in the VectorizeTree.
  constexpr static int NoGatheredLoads = -1;
  int GatheredLoadsEntriesFirst = NoGatheredLoads;

  /// This POD struct describes one external user in the vectorized tree.
  struct ExternalUser {
    ExternalUser(Value *S, llvm::User *U, int L)
        : Scalar(S), User(U), Lane(L) {}

    // Which scalar in our function.
    Value *Scalar;

    // Which user that uses the scalar.
    llvm::User *User;

    // Which lane does the scalar belong to.
    int Lane;
  };
  using UserList = SmallVector<ExternalUser, 16>;

  /// Checks if two instructions may access the same memory.
  ///
  /// \p Loc1 is the location of \p Inst1. It is passed explicitly because it
  /// is invariant in the calling loop.
  bool isAliased(const MemoryLocation &Loc1, Instruction *Inst1,
                 Instruction *Inst2) {
    if (!Loc1.Ptr || !isSimple(Inst1) || !isSimple(Inst2))
      return true;
    // First check if the result is already in the cache.
    AliasCacheKey Key = std::make_pair(Inst1, Inst2);
    auto It = AliasCache.find(Key);
    if (It != AliasCache.end())
      return It->second;
    bool Aliased = isModOrRefSet(BatchAA.getModRefInfo(Inst2, Loc1));
    // Store the result in the cache.
    AliasCache.try_emplace(Key, Aliased);
    AliasCache.try_emplace(std::make_pair(Inst2, Inst1), Aliased);
    return Aliased;
  }

  using AliasCacheKey = std::pair<Instruction *, Instruction *>;

  /// Cache for alias results.
  /// TODO: consider moving this to the AliasAnalysis itself.
  DenseMap<AliasCacheKey, bool> AliasCache;

  // Cache for pointerMayBeCaptured calls inside AA.  This is preserved
  // globally through SLP because we don't perform any action which
  // invalidates capture results.
  BatchAAResults BatchAA;

  /// Temporary store for deleted instructions. Instructions will be deleted
  /// eventually when the BoUpSLP is destructed.  The deferral is required to
  /// ensure that there are no incorrect collisions in the AliasCache, which
  /// can happen if a new instruction is allocated at the same address as a
  /// previously deleted instruction.
  DenseSet<Instruction *> DeletedInstructions;

  /// Set of the instruction, being analyzed already for reductions.
  SmallPtrSet<Instruction *, 16> AnalyzedReductionsRoots;

  /// Set of hashes for the list of reduction values already being analyzed.
  DenseSet<size_t> AnalyzedReductionVals;

  /// Values, already been analyzed for mininmal bitwidth and found to be
  /// non-profitable.
  DenseSet<Value *> AnalyzedMinBWVals;

  /// A list of values that need to extracted out of the tree.
  /// This list holds pairs of (Internal Scalar : External User). External User
  /// can be nullptr, it means that this Internal Scalar will be used later,
  /// after vectorization.
  UserList ExternalUses;

  /// A list of GEPs which can be reaplced by scalar GEPs instead of
  /// extractelement instructions.
  SmallPtrSet<Value *, 4> ExternalUsesAsOriginalScalar;

  /// Values used only by @llvm.assume calls.
  SmallPtrSet<const Value *, 32> EphValues;

  /// Holds all of the instructions that we gathered, shuffle instructions and
  /// extractelements.
  SetVector<Instruction *> GatherShuffleExtractSeq;

  /// A list of blocks that we are going to CSE.
  DenseSet<BasicBlock *> CSEBlocks;

  /// List of hashes of vector of loads, which are known to be non vectorizable.
  DenseSet<size_t> ListOfKnonwnNonVectorizableLoads;

  /// Contains all scheduling relevant data for an instruction.
  /// A ScheduleData either represents a single instruction or a member of an
  /// instruction bundle (= a group of instructions which is combined into a
  /// vector instruction).
  struct ScheduleData {
    // The initial value for the dependency counters. It means that the
    // dependencies are not calculated yet.
    enum { InvalidDeps = -1 };

    ScheduleData() = default;

    void init(int BlockSchedulingRegionID, Instruction *I) {
      FirstInBundle = this;
      NextInBundle = nullptr;
      NextLoadStore = nullptr;
      IsScheduled = false;
      SchedulingRegionID = BlockSchedulingRegionID;
      clearDependencies();
      Inst = I;
      TE = nullptr;
    }

    /// Verify basic self consistency properties
    void verify() {
      if (hasValidDependencies()) {
        assert(UnscheduledDeps <= Dependencies && "invariant");
      } else {
        assert(UnscheduledDeps == Dependencies && "invariant");
      }

      if (IsScheduled) {
        assert(isSchedulingEntity() &&
                "unexpected scheduled state");
        for (const ScheduleData *BundleMember = this; BundleMember;
             BundleMember = BundleMember->NextInBundle) {
          assert(BundleMember->hasValidDependencies() &&
                 BundleMember->UnscheduledDeps == 0 &&
                 "unexpected scheduled state");
          assert((BundleMember == this || !BundleMember->IsScheduled) &&
                 "only bundle is marked scheduled");
        }
      }

      assert(Inst->getParent() == FirstInBundle->Inst->getParent() &&
             "all bundle members must be in same basic block");
    }

    /// Returns true if the dependency information has been calculated.
    /// Note that depenendency validity can vary between instructions within
    /// a single bundle.
    bool hasValidDependencies() const { return Dependencies != InvalidDeps; }

    /// Returns true for single instructions and for bundle representatives
    /// (= the head of a bundle).
    bool isSchedulingEntity() const { return FirstInBundle == this; }

    /// Returns true if it represents an instruction bundle and not only a
    /// single instruction.
    bool isPartOfBundle() const {
      return NextInBundle != nullptr || FirstInBundle != this || TE;
    }

    /// Returns true if it is ready for scheduling, i.e. it has no more
    /// unscheduled depending instructions/bundles.
    bool isReady() const {
      assert(isSchedulingEntity() &&
             "can't consider non-scheduling entity for ready list");
      return unscheduledDepsInBundle() == 0 && !IsScheduled;
    }

    /// Modifies the number of unscheduled dependencies for this instruction,
    /// and returns the number of remaining dependencies for the containing
    /// bundle.
    int incrementUnscheduledDeps(int Incr) {
      assert(hasValidDependencies() &&
             "increment of unscheduled deps would be meaningless");
      UnscheduledDeps += Incr;
      return FirstInBundle->unscheduledDepsInBundle();
    }

    /// Sets the number of unscheduled dependencies to the number of
    /// dependencies.
    void resetUnscheduledDeps() {
      UnscheduledDeps = Dependencies;
    }

    /// Clears all dependency information.
    void clearDependencies() {
      Dependencies = InvalidDeps;
      resetUnscheduledDeps();
      MemoryDependencies.clear();
      ControlDependencies.clear();
    }

    int unscheduledDepsInBundle() const {
      assert(isSchedulingEntity() && "only meaningful on the bundle");
      int Sum = 0;
      for (const ScheduleData *BundleMember = this; BundleMember;
           BundleMember = BundleMember->NextInBundle) {
        if (BundleMember->UnscheduledDeps == InvalidDeps)
          return InvalidDeps;
        Sum += BundleMember->UnscheduledDeps;
      }
      return Sum;
    }

    void dump(raw_ostream &os) const {
      if (!isSchedulingEntity()) {
        os << "/ " << *Inst;
      } else if (NextInBundle) {
        os << '[' << *Inst;
        ScheduleData *SD = NextInBundle;
        while (SD) {
          os << ';' << *SD->Inst;
          SD = SD->NextInBundle;
        }
        os << ']';
      } else {
        os << *Inst;
      }
    }

    Instruction *Inst = nullptr;

    /// The TreeEntry that this instruction corresponds to.
    TreeEntry *TE = nullptr;

    /// Points to the head in an instruction bundle (and always to this for
    /// single instructions).
    ScheduleData *FirstInBundle = nullptr;

    /// Single linked list of all instructions in a bundle. Null if it is a
    /// single instruction.
    ScheduleData *NextInBundle = nullptr;

    /// Single linked list of all memory instructions (e.g. load, store, call)
    /// in the block - until the end of the scheduling region.
    ScheduleData *NextLoadStore = nullptr;

    /// The dependent memory instructions.
    /// This list is derived on demand in calculateDependencies().
    SmallVector<ScheduleData *, 4> MemoryDependencies;

    /// List of instructions which this instruction could be control dependent
    /// on.  Allowing such nodes to be scheduled below this one could introduce
    /// a runtime fault which didn't exist in the original program.
    /// ex: this is a load or udiv following a readonly call which inf loops
    SmallVector<ScheduleData *, 4> ControlDependencies;

    /// This ScheduleData is in the current scheduling region if this matches
    /// the current SchedulingRegionID of BlockScheduling.
    int SchedulingRegionID = 0;

    /// Used for getting a "good" final ordering of instructions.
    int SchedulingPriority = 0;

    /// The number of dependencies. Constitutes of the number of users of the
    /// instruction plus the number of dependent memory instructions (if any).
    /// This value is calculated on demand.
    /// If InvalidDeps, the number of dependencies is not calculated yet.
    int Dependencies = InvalidDeps;

    /// The number of dependencies minus the number of dependencies of scheduled
    /// instructions. As soon as this is zero, the instruction/bundle gets ready
    /// for scheduling.
    /// Note that this is negative as long as Dependencies is not calculated.
    int UnscheduledDeps = InvalidDeps;

    /// True if this instruction is scheduled (or considered as scheduled in the
    /// dry-run).
    bool IsScheduled = false;
  };

#ifndef NDEBUG
  friend inline raw_ostream &operator<<(raw_ostream &os,
                                        const BoUpSLP::ScheduleData &SD) {
    SD.dump(os);
    return os;
  }
#endif

  friend struct GraphTraits<BoUpSLP *>;
  friend struct DOTGraphTraits<BoUpSLP *>;

  /// Contains all scheduling data for a basic block.
  /// It does not schedules instructions, which are not memory read/write
  /// instructions and their operands are either constants, or arguments, or
  /// phis, or instructions from others blocks, or their users are phis or from
  /// the other blocks. The resulting vector instructions can be placed at the
  /// beginning of the basic block without scheduling (if operands does not need
  /// to be scheduled) or at the end of the block (if users are outside of the
  /// block). It allows to save some compile time and memory used by the
  /// compiler.
  /// ScheduleData is assigned for each instruction in between the boundaries of
  /// the tree entry, even for those, which are not part of the graph. It is
  /// required to correctly follow the dependencies between the instructions and
  /// their correct scheduling. The ScheduleData is not allocated for the
  /// instructions, which do not require scheduling, like phis, nodes with
  /// extractelements/insertelements only or nodes with instructions, with
  /// uses/operands outside of the block.
  struct BlockScheduling {
    BlockScheduling(BasicBlock *BB)
        : BB(BB), ChunkSize(BB->size()), ChunkPos(ChunkSize) {}

    void clear() {
      ReadyInsts.clear();
      ScheduleStart = nullptr;
      ScheduleEnd = nullptr;
      FirstLoadStoreInRegion = nullptr;
      LastLoadStoreInRegion = nullptr;
      RegionHasStackSave = false;

      // Reduce the maximum schedule region size by the size of the
      // previous scheduling run.
      ScheduleRegionSizeLimit -= ScheduleRegionSize;
      if (ScheduleRegionSizeLimit < MinScheduleRegionSize)
        ScheduleRegionSizeLimit = MinScheduleRegionSize;
      ScheduleRegionSize = 0;

      // Make a new scheduling region, i.e. all existing ScheduleData is not
      // in the new region yet.
      ++SchedulingRegionID;
    }

    ScheduleData *getScheduleData(Instruction *I) {
      if (BB != I->getParent())
        // Avoid lookup if can't possibly be in map.
        return nullptr;
      ScheduleData *SD = ScheduleDataMap.lookup(I);
      if (SD && isInSchedulingRegion(SD))
        return SD;
      return nullptr;
    }

    ScheduleData *getScheduleData(Value *V) {
      if (auto *I = dyn_cast<Instruction>(V))
        return getScheduleData(I);
      return nullptr;
    }

    bool isInSchedulingRegion(ScheduleData *SD) const {
      return SD->SchedulingRegionID == SchedulingRegionID;
    }

    /// Marks an instruction as scheduled and puts all dependent ready
    /// instructions into the ready-list.
    template <typename ReadyListType>
    void schedule(ScheduleData *SD, ReadyListType &ReadyList) {
      SD->IsScheduled = true;
      LLVM_DEBUG(dbgs() << "SLP:   schedule " << *SD << "\n");

      for (ScheduleData *BundleMember = SD; BundleMember;
           BundleMember = BundleMember->NextInBundle) {

        // Handle the def-use chain dependencies.

        // Decrement the unscheduled counter and insert to ready list if ready.
        auto &&DecrUnsched = [this, &ReadyList](Instruction *I) {
          ScheduleData *OpDef = getScheduleData(I);
          if (OpDef && OpDef->hasValidDependencies() &&
              OpDef->incrementUnscheduledDeps(-1) == 0) {
            // There are no more unscheduled dependencies after
            // decrementing, so we can put the dependent instruction
            // into the ready list.
            ScheduleData *DepBundle = OpDef->FirstInBundle;
            assert(!DepBundle->IsScheduled &&
                   "already scheduled bundle gets ready");
            ReadyList.insert(DepBundle);
            LLVM_DEBUG(dbgs()
                       << "SLP:    gets ready (def): " << *DepBundle << "\n");
          }
        };

        // If BundleMember is a vector bundle, its operands may have been
        // reordered during buildTree(). We therefore need to get its operands
        // through the TreeEntry.
        if (TreeEntry *TE = BundleMember->TE) {
          // Need to search for the lane since the tree entry can be reordered.
          int Lane = std::distance(TE->Scalars.begin(),
                                   find(TE->Scalars, BundleMember->Inst));
          assert(Lane >= 0 && "Lane not set");

          // Since vectorization tree is being built recursively this assertion
          // ensures that the tree entry has all operands set before reaching
          // this code. Couple of exceptions known at the moment are extracts
          // where their second (immediate) operand is not added. Since
          // immediates do not affect scheduler behavior this is considered
          // okay.
          auto *In = BundleMember->Inst;
          assert(
              In &&
              (isa<ExtractValueInst, ExtractElementInst, IntrinsicInst>(In) ||
               In->getNumOperands() == TE->getNumOperands()) &&
              "Missed TreeEntry operands?");
          (void)In; // fake use to avoid build failure when assertions disabled

          for (unsigned OpIdx = 0, NumOperands = TE->getNumOperands();
               OpIdx != NumOperands; ++OpIdx)
            if (auto *I = dyn_cast<Instruction>(TE->getOperand(OpIdx)[Lane]))
              DecrUnsched(I);
        } else {
          // If BundleMember is a stand-alone instruction, no operand reordering
          // has taken place, so we directly access its operands.
          for (Use &U : BundleMember->Inst->operands())
            if (auto *I = dyn_cast<Instruction>(U.get()))
              DecrUnsched(I);
        }
        // Handle the memory dependencies.
        for (ScheduleData *MemoryDepSD : BundleMember->MemoryDependencies) {
          if (MemoryDepSD->hasValidDependencies() &&
              MemoryDepSD->incrementUnscheduledDeps(-1) == 0) {
            // There are no more unscheduled dependencies after decrementing,
            // so we can put the dependent instruction into the ready list.
            ScheduleData *DepBundle = MemoryDepSD->FirstInBundle;
            assert(!DepBundle->IsScheduled &&
                   "already scheduled bundle gets ready");
            ReadyList.insert(DepBundle);
            LLVM_DEBUG(dbgs()
                       << "SLP:    gets ready (mem): " << *DepBundle << "\n");
          }
        }
        // Handle the control dependencies.
        for (ScheduleData *DepSD : BundleMember->ControlDependencies) {
          if (DepSD->incrementUnscheduledDeps(-1) == 0) {
            // There are no more unscheduled dependencies after decrementing,
            // so we can put the dependent instruction into the ready list.
            ScheduleData *DepBundle = DepSD->FirstInBundle;
            assert(!DepBundle->IsScheduled &&
                   "already scheduled bundle gets ready");
            ReadyList.insert(DepBundle);
            LLVM_DEBUG(dbgs()
                       << "SLP:    gets ready (ctl): " << *DepBundle << "\n");
          }
        }
      }
    }

    /// Verify basic self consistency properties of the data structure.
    void verify() {
      if (!ScheduleStart)
        return;

      assert(ScheduleStart->getParent() == ScheduleEnd->getParent() &&
             ScheduleStart->comesBefore(ScheduleEnd) &&
             "Not a valid scheduling region?");

      for (auto *I = ScheduleStart; I != ScheduleEnd; I = I->getNextNode()) {
        auto *SD = getScheduleData(I);
        if (!SD)
          continue;
        assert(isInSchedulingRegion(SD) &&
               "primary schedule data not in window?");
        assert(isInSchedulingRegion(SD->FirstInBundle) &&
               "entire bundle in window!");
        SD->verify();
      }

      for (auto *SD : ReadyInsts) {
        assert(SD->isSchedulingEntity() && SD->isReady() &&
               "item in ready list not ready?");
        (void)SD;
      }
    }

    /// Put all instructions into the ReadyList which are ready for scheduling.
    template <typename ReadyListType>
    void initialFillReadyList(ReadyListType &ReadyList) {
      for (auto *I = ScheduleStart; I != ScheduleEnd; I = I->getNextNode()) {
        ScheduleData *SD = getScheduleData(I);
        if (SD && SD->isSchedulingEntity() && SD->hasValidDependencies() &&
            SD->isReady()) {
          ReadyList.insert(SD);
          LLVM_DEBUG(dbgs()
                     << "SLP:    initially in ready list: " << *SD << "\n");
        }
      }
    }

    /// Build a bundle from the ScheduleData nodes corresponding to the
    /// scalar instruction for each lane.
    ScheduleData *buildBundle(ArrayRef<Value *> VL);

    /// Checks if a bundle of instructions can be scheduled, i.e. has no
    /// cyclic dependencies. This is only a dry-run, no instructions are
    /// actually moved at this stage.
    /// \returns the scheduling bundle. The returned Optional value is not
    /// std::nullopt if \p VL is allowed to be scheduled.
    std::optional<ScheduleData *>
    tryScheduleBundle(ArrayRef<Value *> VL, BoUpSLP *SLP,
                      const InstructionsState &S);

    /// Un-bundles a group of instructions.
    void cancelScheduling(ArrayRef<Value *> VL, Value *OpValue);

    /// Allocates schedule data chunk.
    ScheduleData *allocateScheduleDataChunks();

    /// Extends the scheduling region so that V is inside the region.
    /// \returns true if the region size is within the limit.
    bool extendSchedulingRegion(Value *V, const InstructionsState &S);

    /// Initialize the ScheduleData structures for new instructions in the
    /// scheduling region.
    void initScheduleData(Instruction *FromI, Instruction *ToI,
                          ScheduleData *PrevLoadStore,
                          ScheduleData *NextLoadStore);

    /// Updates the dependency information of a bundle and of all instructions/
    /// bundles which depend on the original bundle.
    void calculateDependencies(ScheduleData *SD, bool InsertInReadyList,
                               BoUpSLP *SLP);

    /// Sets all instruction in the scheduling region to un-scheduled.
    void resetSchedule();

    BasicBlock *BB;

    /// Simple memory allocation for ScheduleData.
    SmallVector<std::unique_ptr<ScheduleData[]>> ScheduleDataChunks;

    /// The size of a ScheduleData array in ScheduleDataChunks.
    int ChunkSize;

    /// The allocator position in the current chunk, which is the last entry
    /// of ScheduleDataChunks.
    int ChunkPos;

    /// Attaches ScheduleData to Instruction.
    /// Note that the mapping survives during all vectorization iterations, i.e.
    /// ScheduleData structures are recycled.
    DenseMap<Instruction *, ScheduleData *> ScheduleDataMap;

    /// The ready-list for scheduling (only used for the dry-run).
    SetVector<ScheduleData *> ReadyInsts;

    /// The first instruction of the scheduling region.
    Instruction *ScheduleStart = nullptr;

    /// The first instruction _after_ the scheduling region.
    Instruction *ScheduleEnd = nullptr;

    /// The first memory accessing instruction in the scheduling region
    /// (can be null).
    ScheduleData *FirstLoadStoreInRegion = nullptr;

    /// The last memory accessing instruction in the scheduling region
    /// (can be null).
    ScheduleData *LastLoadStoreInRegion = nullptr;

    /// Is there an llvm.stacksave or llvm.stackrestore in the scheduling
    /// region?  Used to optimize the dependence calculation for the
    /// common case where there isn't.
    bool RegionHasStackSave = false;

    /// The current size of the scheduling region.
    int ScheduleRegionSize = 0;

    /// The maximum size allowed for the scheduling region.
    int ScheduleRegionSizeLimit = ScheduleRegionSizeBudget;

    /// The ID of the scheduling region. For a new vectorization iteration this
    /// is incremented which "removes" all ScheduleData from the region.
    /// Make sure that the initial SchedulingRegionID is greater than the
    /// initial SchedulingRegionID in ScheduleData (which is 0).
    int SchedulingRegionID = 1;
  };

  /// Attaches the BlockScheduling structures to basic blocks.
  MapVector<BasicBlock *, std::unique_ptr<BlockScheduling>> BlocksSchedules;

  /// Performs the "real" scheduling. Done before vectorization is actually
  /// performed in a basic block.
  void scheduleBlock(BlockScheduling *BS);

  /// List of users to ignore during scheduling and that don't need extracting.
  const SmallDenseSet<Value *> *UserIgnoreList = nullptr;

  /// A DenseMapInfo implementation for holding DenseMaps and DenseSets of
  /// sorted SmallVectors of unsigned.
  struct OrdersTypeDenseMapInfo {
    static OrdersType getEmptyKey() {
      OrdersType V;
      V.push_back(~1U);
      return V;
    }

    static OrdersType getTombstoneKey() {
      OrdersType V;
      V.push_back(~2U);
      return V;
    }

    static unsigned getHashValue(const OrdersType &V) {
      return static_cast<unsigned>(hash_combine_range(V.begin(), V.end()));
    }

    static bool isEqual(const OrdersType &LHS, const OrdersType &RHS) {
      return LHS == RHS;
    }
  };

  // Analysis and block reference.
  Function *F;
  ScalarEvolution *SE;
  TargetTransformInfo *TTI;
  TargetLibraryInfo *TLI;
  LoopInfo *LI;
  DominatorTree *DT;
  AssumptionCache *AC;
  DemandedBits *DB;
  const DataLayout *DL;
  OptimizationRemarkEmitter *ORE;

  unsigned MaxVecRegSize; // This is set by TTI or overridden by cl::opt.
  unsigned MinVecRegSize; // Set by cl::opt (default: 128).

  /// Instruction builder to construct the vectorized tree.
  IRBuilder<TargetFolder> Builder;

  /// A map of scalar integer values to the smallest bit width with which they
  /// can legally be represented. The values map to (width, signed) pairs,
  /// where "width" indicates the minimum bit width and "signed" is True if the
  /// value must be signed-extended, rather than zero-extended, back to its
  /// original width.
  DenseMap<const TreeEntry *, std::pair<uint64_t, bool>> MinBWs;

  /// Final size of the reduced vector, if the current graph represents the
  /// input for the reduction and it was possible to narrow the size of the
  /// reduction.
  unsigned ReductionBitWidth = 0;

  /// If the tree contains any zext/sext/trunc nodes, contains max-min pair of
  /// type sizes, used in the tree.
  std::optional<std::pair<unsigned, unsigned>> CastMaxMinBWSizes;

  /// Indices of the vectorized nodes, which supposed to be the roots of the new
  /// bitwidth analysis attempt, like trunc, IToFP or ICmp.
  DenseSet<unsigned> ExtraBitWidthNodes;
};

} // end namespace slpvectorizer

template <> struct GraphTraits<BoUpSLP *> {
  using TreeEntry = BoUpSLP::TreeEntry;

  /// NodeRef has to be a pointer per the GraphWriter.
  using NodeRef = TreeEntry *;

  using ContainerTy = BoUpSLP::TreeEntry::VecTreeTy;

  /// Add the VectorizableTree to the index iterator to be able to return
  /// TreeEntry pointers.
  struct ChildIteratorType
      : public iterator_adaptor_base<
            ChildIteratorType, SmallVector<BoUpSLP::EdgeInfo, 1>::iterator> {
    ContainerTy &VectorizableTree;

    ChildIteratorType(SmallVector<BoUpSLP::EdgeInfo, 1>::iterator W,
                      ContainerTy &VT)
        : ChildIteratorType::iterator_adaptor_base(W), VectorizableTree(VT) {}

    NodeRef operator*() { return I->UserTE; }
  };

  static NodeRef getEntryNode(BoUpSLP &R) {
    return R.VectorizableTree[0].get();
  }

  static ChildIteratorType child_begin(NodeRef N) {
    return {N->UserTreeIndices.begin(), N->Container};
  }

  static ChildIteratorType child_end(NodeRef N) {
    return {N->UserTreeIndices.end(), N->Container};
  }

  /// For the node iterator we just need to turn the TreeEntry iterator into a
  /// TreeEntry* iterator so that it dereferences to NodeRef.
  class nodes_iterator {
    using ItTy = ContainerTy::iterator;
    ItTy It;

  public:
    nodes_iterator(const ItTy &It2) : It(It2) {}
    NodeRef operator*() { return It->get(); }
    nodes_iterator operator++() {
      ++It;
      return *this;
    }
    bool operator!=(const nodes_iterator &N2) const { return N2.It != It; }
  };

  static nodes_iterator nodes_begin(BoUpSLP *R) {
    return nodes_iterator(R->VectorizableTree.begin());
  }

  static nodes_iterator nodes_end(BoUpSLP *R) {
    return nodes_iterator(R->VectorizableTree.end());
  }

  static unsigned size(BoUpSLP *R) { return R->VectorizableTree.size(); }
};

template <> struct DOTGraphTraits<BoUpSLP *> : public DefaultDOTGraphTraits {
  using TreeEntry = BoUpSLP::TreeEntry;

  DOTGraphTraits(bool IsSimple = false) : DefaultDOTGraphTraits(IsSimple) {}

  std::string getNodeLabel(const TreeEntry *Entry, const BoUpSLP *R) {
    std::string Str;
    raw_string_ostream OS(Str);
    OS << Entry->Idx << ".\n";
    if (isSplat(Entry->Scalars))
      OS << "<splat> ";
    for (auto *V : Entry->Scalars) {
      OS << *V;
      if (llvm::any_of(R->ExternalUses, [&](const BoUpSLP::ExternalUser &EU) {
            return EU.Scalar == V;
          }))
        OS << " <extract>";
      OS << "\n";
    }
    return Str;
  }

  static std::string getNodeAttributes(const TreeEntry *Entry,
                                       const BoUpSLP *) {
    if (Entry->isGather())
      return "color=red";
    if (Entry->State == TreeEntry::ScatterVectorize ||
        Entry->State == TreeEntry::StridedVectorize)
      return "color=blue";
    return "";
  }
};

} // end namespace llvm

BoUpSLP::~BoUpSLP() {
  SmallVector<WeakTrackingVH> DeadInsts;
  for (auto *I : DeletedInstructions) {
    if (!I->getParent()) {
      // Temporarily insert instruction back to erase them from parent and
      // memory later.
      if (isa<PHINode>(I))
        // Phi nodes must be the very first instructions in the block.
        I->insertBefore(F->getEntryBlock(),
                        F->getEntryBlock().getFirstNonPHIIt());
      else
        I->insertBefore(F->getEntryBlock().getTerminator());
      continue;
    }
    for (Use &U : I->operands()) {
      auto *Op = dyn_cast<Instruction>(U.get());
      if (Op && !DeletedInstructions.count(Op) && Op->hasOneUser() &&
          wouldInstructionBeTriviallyDead(Op, TLI))
        DeadInsts.emplace_back(Op);
    }
    I->dropAllReferences();
  }
  for (auto *I : DeletedInstructions) {
    assert(I->use_empty() &&
           "trying to erase instruction with users.");
    I->eraseFromParent();
  }

  // Cleanup any dead scalar code feeding the vectorized instructions
  RecursivelyDeleteTriviallyDeadInstructions(DeadInsts, TLI);

#ifdef EXPENSIVE_CHECKS
  // If we could guarantee that this call is not extremely slow, we could
  // remove the ifdef limitation (see PR47712).
  assert(!verifyFunction(*F, &dbgs()));
#endif
}

/// Reorders the given \p Reuses mask according to the given \p Mask. \p Reuses
/// contains original mask for the scalars reused in the node. Procedure
/// transform this mask in accordance with the given \p Mask.
static void reorderReuses(SmallVectorImpl<int> &Reuses, ArrayRef<int> Mask) {
  assert(!Mask.empty() && Reuses.size() == Mask.size() &&
         "Expected non-empty mask.");
  SmallVector<int> Prev(Reuses.begin(), Reuses.end());
  Prev.swap(Reuses);
  for (unsigned I = 0, E = Prev.size(); I < E; ++I)
    if (Mask[I] != PoisonMaskElem)
      Reuses[Mask[I]] = Prev[I];
}

/// Reorders the given \p Order according to the given \p Mask. \p Order - is
/// the original order of the scalars. Procedure transforms the provided order
/// in accordance with the given \p Mask. If the resulting \p Order is just an
/// identity order, \p Order is cleared.
static void reorderOrder(SmallVectorImpl<unsigned> &Order, ArrayRef<int> Mask,
                         bool BottomOrder = false) {
  assert(!Mask.empty() && "Expected non-empty mask.");
  unsigned Sz = Mask.size();
  if (BottomOrder) {
    SmallVector<unsigned> PrevOrder;
    if (Order.empty()) {
      PrevOrder.resize(Sz);
      std::iota(PrevOrder.begin(), PrevOrder.end(), 0);
    } else {
      PrevOrder.swap(Order);
    }
    Order.assign(Sz, Sz);
    for (unsigned I = 0; I < Sz; ++I)
      if (Mask[I] != PoisonMaskElem)
        Order[I] = PrevOrder[Mask[I]];
    if (all_of(enumerate(Order), [&](const auto &Data) {
          return Data.value() == Sz || Data.index() == Data.value();
        })) {
      Order.clear();
      return;
    }
    fixupOrderingIndices(Order);
    return;
  }
  SmallVector<int> MaskOrder;
  if (Order.empty()) {
    MaskOrder.resize(Sz);
    std::iota(MaskOrder.begin(), MaskOrder.end(), 0);
  } else {
    inversePermutation(Order, MaskOrder);
  }
  reorderReuses(MaskOrder, Mask);
  if (ShuffleVectorInst::isIdentityMask(MaskOrder, Sz)) {
    Order.clear();
    return;
  }
  Order.assign(Sz, Sz);
  for (unsigned I = 0; I < Sz; ++I)
    if (MaskOrder[I] != PoisonMaskElem)
      Order[MaskOrder[I]] = I;
  fixupOrderingIndices(Order);
}

std::optional<BoUpSLP::OrdersType>
BoUpSLP::findReusedOrderedScalars(const BoUpSLP::TreeEntry &TE) {
  assert(TE.isGather() && "Expected gather node only.");
  // Try to find subvector extract/insert patterns and reorder only such
  // patterns.
  SmallVector<Value *> GatheredScalars(TE.Scalars.begin(), TE.Scalars.end());
  Type *ScalarTy = GatheredScalars.front()->getType();
  int NumScalars = GatheredScalars.size();
  if (!isValidElementType(ScalarTy))
    return std::nullopt;
  auto *VecTy = getWidenedType(ScalarTy, NumScalars);
  int NumParts = TTI->getNumberOfParts(VecTy);
  if (NumParts == 0 || NumParts >= NumScalars)
    NumParts = 1;
  SmallVector<int> ExtractMask;
  SmallVector<int> Mask;
  SmallVector<SmallVector<const TreeEntry *>> Entries;
  SmallVector<std::optional<TargetTransformInfo::ShuffleKind>> ExtractShuffles =
      tryToGatherExtractElements(GatheredScalars, ExtractMask, NumParts);
  SmallVector<std::optional<TargetTransformInfo::ShuffleKind>> GatherShuffles =
      isGatherShuffledEntry(&TE, GatheredScalars, Mask, Entries, NumParts,
                            /*ForOrder=*/true);
  // No shuffled operands - ignore.
  if (GatherShuffles.empty() && ExtractShuffles.empty())
    return std::nullopt;
  OrdersType CurrentOrder(NumScalars, NumScalars);
  if (GatherShuffles.size() == 1 &&
      *GatherShuffles.front() == TTI::SK_PermuteSingleSrc &&
      Entries.front().front()->isSame(TE.Scalars)) {
    // Perfect match in the graph, will reuse the previously vectorized
    // node. Cost is 0.
    std::iota(CurrentOrder.begin(), CurrentOrder.end(), 0);
    return CurrentOrder;
  }
  auto IsSplatMask = [](ArrayRef<int> Mask) {
    int SingleElt = PoisonMaskElem;
    return all_of(Mask, [&](int I) {
      if (SingleElt == PoisonMaskElem && I != PoisonMaskElem)
        SingleElt = I;
      return I == PoisonMaskElem || I == SingleElt;
    });
  };
  // Exclusive broadcast mask - ignore.
  if ((ExtractShuffles.empty() && IsSplatMask(Mask) &&
       (Entries.size() != 1 ||
        Entries.front().front()->ReorderIndices.empty())) ||
      (GatherShuffles.empty() && IsSplatMask(ExtractMask)))
    return std::nullopt;
  SmallBitVector ShuffledSubMasks(NumParts);
  auto TransformMaskToOrder = [&](MutableArrayRef<unsigned> CurrentOrder,
                                  ArrayRef<int> Mask, int PartSz, int NumParts,
                                  function_ref<unsigned(unsigned)> GetVF) {
    for (int I : seq<int>(0, NumParts)) {
      if (ShuffledSubMasks.test(I))
        continue;
      const int VF = GetVF(I);
      if (VF == 0)
        continue;
      unsigned Limit = getNumElems(CurrentOrder.size(), PartSz, I);
      MutableArrayRef<unsigned> Slice = CurrentOrder.slice(I * PartSz, Limit);
      // Shuffle of at least 2 vectors - ignore.
      if (any_of(Slice, [&](int I) { return I != NumScalars; })) {
        std::fill(Slice.begin(), Slice.end(), NumScalars);
        ShuffledSubMasks.set(I);
        continue;
      }
      // Try to include as much elements from the mask as possible.
      int FirstMin = INT_MAX;
      int SecondVecFound = false;
      for (int K : seq<int>(Limit)) {
        int Idx = Mask[I * PartSz + K];
        if (Idx == PoisonMaskElem) {
          Value *V = GatheredScalars[I * PartSz + K];
          if (isConstant(V) && !isa<PoisonValue>(V)) {
            SecondVecFound = true;
            break;
          }
          continue;
        }
        if (Idx < VF) {
          if (FirstMin > Idx)
            FirstMin = Idx;
        } else {
          SecondVecFound = true;
          break;
        }
      }
      FirstMin = (FirstMin / PartSz) * PartSz;
      // Shuffle of at least 2 vectors - ignore.
      if (SecondVecFound) {
        std::fill(Slice.begin(), Slice.end(), NumScalars);
        ShuffledSubMasks.set(I);
        continue;
      }
      for (int K : seq<int>(Limit)) {
        int Idx = Mask[I * PartSz + K];
        if (Idx == PoisonMaskElem)
          continue;
        Idx -= FirstMin;
        if (Idx >= PartSz) {
          SecondVecFound = true;
          break;
        }
        if (CurrentOrder[I * PartSz + Idx] >
                static_cast<unsigned>(I * PartSz + K) &&
            CurrentOrder[I * PartSz + Idx] !=
                static_cast<unsigned>(I * PartSz + Idx))
          CurrentOrder[I * PartSz + Idx] = I * PartSz + K;
      }
      // Shuffle of at least 2 vectors - ignore.
      if (SecondVecFound) {
        std::fill(Slice.begin(), Slice.end(), NumScalars);
        ShuffledSubMasks.set(I);
        continue;
      }
    }
  };
  int PartSz = getPartNumElems(NumScalars, NumParts);
  if (!ExtractShuffles.empty())
    TransformMaskToOrder(
        CurrentOrder, ExtractMask, PartSz, NumParts, [&](unsigned I) {
          if (!ExtractShuffles[I])
            return 0U;
          unsigned VF = 0;
          unsigned Sz = getNumElems(TE.getVectorFactor(), PartSz, I);
          for (unsigned Idx : seq<unsigned>(Sz)) {
            int K = I * PartSz + Idx;
            if (ExtractMask[K] == PoisonMaskElem)
              continue;
            if (!TE.ReuseShuffleIndices.empty())
              K = TE.ReuseShuffleIndices[K];
            if (!TE.ReorderIndices.empty())
              K = std::distance(TE.ReorderIndices.begin(),
                                find(TE.ReorderIndices, K));
            auto *EI = dyn_cast<ExtractElementInst>(TE.Scalars[K]);
            if (!EI)
              continue;
            VF = std::max(VF, cast<VectorType>(EI->getVectorOperandType())
                                  ->getElementCount()
                                  .getKnownMinValue());
          }
          return VF;
        });
  // Check special corner case - single shuffle of the same entry.
  if (GatherShuffles.size() == 1 && NumParts != 1) {
    if (ShuffledSubMasks.any())
      return std::nullopt;
    PartSz = NumScalars;
    NumParts = 1;
  }
  if (!Entries.empty())
    TransformMaskToOrder(CurrentOrder, Mask, PartSz, NumParts, [&](unsigned I) {
      if (!GatherShuffles[I])
        return 0U;
      return std::max(Entries[I].front()->getVectorFactor(),
                      Entries[I].back()->getVectorFactor());
    });
  int NumUndefs =
      count_if(CurrentOrder, [&](int Idx) { return Idx == NumScalars; });
  if (ShuffledSubMasks.all() || (NumScalars > 2 && NumUndefs >= NumScalars / 2))
    return std::nullopt;
  return std::move(CurrentOrder);
}

static bool arePointersCompatible(Value *Ptr1, Value *Ptr2,
                                  const TargetLibraryInfo &TLI,
                                  bool CompareOpcodes = true) {
  if (getUnderlyingObject(Ptr1) != getUnderlyingObject(Ptr2))
    return false;
  auto *GEP1 = dyn_cast<GetElementPtrInst>(Ptr1);
  if (!GEP1)
    return false;
  auto *GEP2 = dyn_cast<GetElementPtrInst>(Ptr2);
  if (!GEP2)
    return false;
  return GEP1->getNumOperands() == 2 && GEP2->getNumOperands() == 2 &&
         ((isConstant(GEP1->getOperand(1)) &&
           isConstant(GEP2->getOperand(1))) ||
          !CompareOpcodes ||
          getSameOpcode({GEP1->getOperand(1), GEP2->getOperand(1)}, TLI)
              .getOpcode());
}

/// Calculates minimal alignment as a common alignment.
template <typename T>
static Align computeCommonAlignment(ArrayRef<Value *> VL) {
  Align CommonAlignment = cast<T>(VL.front())->getAlign();
  for (Value *V : VL.drop_front())
    CommonAlignment = std::min(CommonAlignment, cast<T>(V)->getAlign());
  return CommonAlignment;
}

/// Check if \p Order represents reverse order.
static bool isReverseOrder(ArrayRef<unsigned> Order) {
  unsigned Sz = Order.size();
  return !Order.empty() && all_of(enumerate(Order), [&](const auto &Pair) {
    return Pair.value() == Sz || Sz - Pair.index() - 1 == Pair.value();
  });
}

/// Checks if the provided list of pointers \p Pointers represents the strided
/// pointers for type ElemTy. If they are not, std::nullopt is returned.
/// Otherwise, if \p Inst is not specified, just initialized optional value is
/// returned to show that the pointers represent strided pointers. If \p Inst
/// specified, the runtime stride is materialized before the given \p Inst.
/// \returns std::nullopt if the pointers are not pointers with the runtime
/// stride, nullptr or actual stride value, otherwise.
static std::optional<Value *>
calculateRtStride(ArrayRef<Value *> PointerOps, Type *ElemTy,
                  const DataLayout &DL, ScalarEvolution &SE,
                  SmallVectorImpl<unsigned> &SortedIndices,
                  Instruction *Inst = nullptr) {
  SmallVector<const SCEV *> SCEVs;
  const SCEV *PtrSCEVLowest = nullptr;
  const SCEV *PtrSCEVHighest = nullptr;
  // Find lower/upper pointers from the PointerOps (i.e. with lowest and highest
  // addresses).
  for (Value *Ptr : PointerOps) {
    const SCEV *PtrSCEV = SE.getSCEV(Ptr);
    if (!PtrSCEV)
      return std::nullopt;
    SCEVs.push_back(PtrSCEV);
    if (!PtrSCEVLowest && !PtrSCEVHighest) {
      PtrSCEVLowest = PtrSCEVHighest = PtrSCEV;
      continue;
    }
    const SCEV *Diff = SE.getMinusSCEV(PtrSCEV, PtrSCEVLowest);
    if (isa<SCEVCouldNotCompute>(Diff))
      return std::nullopt;
    if (Diff->isNonConstantNegative()) {
      PtrSCEVLowest = PtrSCEV;
      continue;
    }
    const SCEV *Diff1 = SE.getMinusSCEV(PtrSCEVHighest, PtrSCEV);
    if (isa<SCEVCouldNotCompute>(Diff1))
      return std::nullopt;
    if (Diff1->isNonConstantNegative()) {
      PtrSCEVHighest = PtrSCEV;
      continue;
    }
  }
  // Dist = PtrSCEVHighest - PtrSCEVLowest;
  const SCEV *Dist = SE.getMinusSCEV(PtrSCEVHighest, PtrSCEVLowest);
  if (isa<SCEVCouldNotCompute>(Dist))
    return std::nullopt;
  int Size = DL.getTypeStoreSize(ElemTy);
  auto TryGetStride = [&](const SCEV *Dist,
                          const SCEV *Multiplier) -> const SCEV * {
    if (const auto *M = dyn_cast<SCEVMulExpr>(Dist)) {
      if (M->getOperand(0) == Multiplier)
        return M->getOperand(1);
      if (M->getOperand(1) == Multiplier)
        return M->getOperand(0);
      return nullptr;
    }
    if (Multiplier == Dist)
      return SE.getConstant(Dist->getType(), 1);
    return SE.getUDivExactExpr(Dist, Multiplier);
  };
  // Stride_in_elements = Dist / element_size * (num_elems - 1).
  const SCEV *Stride = nullptr;
  if (Size != 1 || SCEVs.size() > 2) {
    const SCEV *Sz = SE.getConstant(Dist->getType(), Size * (SCEVs.size() - 1));
    Stride = TryGetStride(Dist, Sz);
    if (!Stride)
      return std::nullopt;
  }
  if (!Stride || isa<SCEVConstant>(Stride))
    return std::nullopt;
  // Iterate through all pointers and check if all distances are
  // unique multiple of Stride.
  using DistOrdPair = std::pair<int64_t, int>;
  auto Compare = llvm::less_first();
  std::set<DistOrdPair, decltype(Compare)> Offsets(Compare);
  int Cnt = 0;
  bool IsConsecutive = true;
  for (const SCEV *PtrSCEV : SCEVs) {
    unsigned Dist = 0;
    if (PtrSCEV != PtrSCEVLowest) {
      const SCEV *Diff = SE.getMinusSCEV(PtrSCEV, PtrSCEVLowest);
      const SCEV *Coeff = TryGetStride(Diff, Stride);
      if (!Coeff)
        return std::nullopt;
      const auto *SC = dyn_cast<SCEVConstant>(Coeff);
      if (!SC || isa<SCEVCouldNotCompute>(SC))
        return std::nullopt;
      if (!SE.getMinusSCEV(PtrSCEV, SE.getAddExpr(PtrSCEVLowest,
                                                  SE.getMulExpr(Stride, SC)))
               ->isZero())
        return std::nullopt;
      Dist = SC->getAPInt().getZExtValue();
    }
    // If the strides are not the same or repeated, we can't vectorize.
    if ((Dist / Size) * Size != Dist || (Dist / Size) >= SCEVs.size())
      return std::nullopt;
    auto Res = Offsets.emplace(Dist, Cnt);
    if (!Res.second)
      return std::nullopt;
    // Consecutive order if the inserted element is the last one.
    IsConsecutive = IsConsecutive && std::next(Res.first) == Offsets.end();
    ++Cnt;
  }
  if (Offsets.size() != SCEVs.size())
    return std::nullopt;
  SortedIndices.clear();
  if (!IsConsecutive) {
    // Fill SortedIndices array only if it is non-consecutive.
    SortedIndices.resize(PointerOps.size());
    Cnt = 0;
    for (const std::pair<int64_t, int> &Pair : Offsets) {
      SortedIndices[Cnt] = Pair.second;
      ++Cnt;
    }
  }
  if (!Inst)
    return nullptr;
  SCEVExpander Expander(SE, DL, "strided-load-vec");
  return Expander.expandCodeFor(Stride, Stride->getType(), Inst);
}

static std::pair<InstructionCost, InstructionCost>
getGEPCosts(const TargetTransformInfo &TTI, ArrayRef<Value *> Ptrs,
            Value *BasePtr, unsigned Opcode, TTI::TargetCostKind CostKind,
            Type *ScalarTy, VectorType *VecTy);

/// Returns the cost of the shuffle instructions with the given \p Kind, vector
/// type \p Tp and optional \p Mask. Adds SLP-specifc cost estimation for insert
/// subvector pattern.
static InstructionCost
getShuffleCost(const TargetTransformInfo &TTI, TTI::ShuffleKind Kind,
               VectorType *Tp, ArrayRef<int> Mask = {},
               TTI::TargetCostKind CostKind = TTI::TCK_RecipThroughput,
               int Index = 0, VectorType *SubTp = nullptr,
               ArrayRef<const Value *> Args = {}) {
  if (Kind != TTI::SK_PermuteTwoSrc)
    return TTI.getShuffleCost(Kind, Tp, Mask, CostKind, Index, SubTp, Args);
  int NumSrcElts = Tp->getElementCount().getKnownMinValue();
  int NumSubElts;
  if (Mask.size() > 2 && ShuffleVectorInst::isInsertSubvectorMask(
                             Mask, NumSrcElts, NumSubElts, Index)) {
    if (Index + NumSubElts > NumSrcElts &&
        Index + NumSrcElts <= static_cast<int>(Mask.size()))
      return TTI.getShuffleCost(
          TTI::SK_InsertSubvector,
          getWidenedType(Tp->getElementType(), Mask.size()), Mask,
          TTI::TCK_RecipThroughput, Index, Tp);
  }
  return TTI.getShuffleCost(Kind, Tp, Mask, CostKind, Index, SubTp, Args);
}

BoUpSLP::LoadsState
BoUpSLP::canVectorizeLoads(ArrayRef<Value *> VL, const Value *VL0,
                           SmallVectorImpl<unsigned> &Order,
                           SmallVectorImpl<Value *> &PointerOps,
                           unsigned *BestVF, bool TryRecursiveCheck) const {
  // Check that a vectorized load would load the same memory as a scalar
  // load. For example, we don't want to vectorize loads that are smaller
  // than 8-bit. Even though we have a packed struct {<i2, i2, i2, i2>} LLVM
  // treats loading/storing it as an i8 struct. If we vectorize loads/stores
  // from such a struct, we read/write packed bits disagreeing with the
  // unvectorized version.
  if (BestVF)
    *BestVF = 0;
  if (areKnownNonVectorizableLoads(VL))
    return LoadsState::Gather;
  Type *ScalarTy = VL0->getType();

  if (DL->getTypeSizeInBits(ScalarTy) != DL->getTypeAllocSizeInBits(ScalarTy))
    return LoadsState::Gather;

  // Make sure all loads in the bundle are simple - we can't vectorize
  // atomic or volatile loads.
  PointerOps.clear();
  const unsigned Sz = VL.size();
  PointerOps.resize(Sz);
  auto *POIter = PointerOps.begin();
  for (Value *V : VL) {
    auto *L = cast<LoadInst>(V);
    if (!L->isSimple())
      return LoadsState::Gather;
    *POIter = L->getPointerOperand();
    ++POIter;
  }

  Order.clear();
  // Check the order of pointer operands or that all pointers are the same.
  bool IsSorted = sortPtrAccesses(PointerOps, ScalarTy, *DL, *SE, Order);

  auto *VecTy = getWidenedType(ScalarTy, Sz);
  Align CommonAlignment = computeCommonAlignment<LoadInst>(VL);
  if (!IsSorted) {
    if (Sz > MinProfitableStridedLoads && TTI->isTypeLegal(VecTy)) {
      if (TTI->isLegalStridedLoadStore(VecTy, CommonAlignment) &&
          calculateRtStride(PointerOps, ScalarTy, *DL, *SE, Order))
        return LoadsState::StridedVectorize;
    }

    if (!TTI->isLegalMaskedGather(VecTy, CommonAlignment) ||
        TTI->forceScalarizeMaskedGather(VecTy, CommonAlignment))
      return LoadsState::Gather;

    if (!all_of(PointerOps, [&](Value *P) {
          return arePointersCompatible(P, PointerOps.front(), *TLI);
        }))
      return LoadsState::Gather;

  } else {
    Value *Ptr0;
    Value *PtrN;
    if (Order.empty()) {
      Ptr0 = PointerOps.front();
      PtrN = PointerOps.back();
    } else {
      Ptr0 = PointerOps[Order.front()];
      PtrN = PointerOps[Order.back()];
    }
    std::optional<int> Diff =
        getPointersDiff(ScalarTy, Ptr0, ScalarTy, PtrN, *DL, *SE);
    // Check that the sorted loads are consecutive.
    if (static_cast<unsigned>(*Diff) == Sz - 1)
      return LoadsState::Vectorize;
    if (!TTI->isLegalMaskedGather(VecTy, CommonAlignment) ||
        TTI->forceScalarizeMaskedGather(VecTy, CommonAlignment))
      return LoadsState::Gather;
    // Simple check if not a strided access - clear order.
    bool IsPossibleStrided = *Diff % (Sz - 1) == 0;
    // Try to generate strided load node if:
    // 1. Target with strided load support is detected.
    // 2. The number of loads is greater than MinProfitableStridedLoads,
    // or the potential stride <= MaxProfitableLoadStride and the
    // potential stride is power-of-2 (to avoid perf regressions for the very
    // small number of loads) and max distance > number of loads, or potential
    // stride is -1.
    // 3. The loads are ordered, or number of unordered loads <=
    // MaxProfitableUnorderedLoads, or loads are in reversed order.
    // (this check is to avoid extra costs for very expensive shuffles).
    // 4. Any pointer operand is an instruction with the users outside of the
    // current graph (for masked gathers extra extractelement instructions
    // might be required).
    auto IsAnyPointerUsedOutGraph =
        IsPossibleStrided && any_of(PointerOps, [&](Value *V) {
          return isa<Instruction>(V) && any_of(V->users(), [&](User *U) {
                   return !getTreeEntry(U) && !MustGather.contains(U);
                 });
        });
    const unsigned AbsoluteDiff = std::abs(*Diff);
    if (IsPossibleStrided && (IsAnyPointerUsedOutGraph ||
                              ((Sz > MinProfitableStridedLoads ||
                                (AbsoluteDiff <= MaxProfitableLoadStride * Sz &&
                                 has_single_bit(AbsoluteDiff))) &&
                               AbsoluteDiff > Sz) ||
                              *Diff == -(static_cast<int>(Sz) - 1))) {
      int Stride = *Diff / static_cast<int>(Sz - 1);
      if (*Diff == Stride * static_cast<int>(Sz - 1)) {
        Align Alignment =
            cast<LoadInst>(Order.empty() ? VL.front() : VL[Order.front()])
                ->getAlign();
        if (TTI->isLegalStridedLoadStore(VecTy, Alignment)) {
          // Iterate through all pointers and check if all distances are
          // unique multiple of Dist.
          SmallSet<int, 4> Dists;
          for (Value *Ptr : PointerOps) {
            int Dist = 0;
            if (Ptr == PtrN)
              Dist = *Diff;
            else if (Ptr != Ptr0)
              Dist = *getPointersDiff(ScalarTy, Ptr0, ScalarTy, Ptr, *DL, *SE);
            // If the strides are not the same or repeated, we can't
            // vectorize.
            if (((Dist / Stride) * Stride) != Dist ||
                !Dists.insert(Dist).second)
              break;
          }
          if (Dists.size() == Sz)
            return LoadsState::StridedVectorize;
        }
      }
    }
  }
  // Correctly identify compare the cost of loads + shuffles rather than
  // strided/masked gather loads. Returns true if vectorized + shuffles
  // representation is better than just gather.
  auto CheckForShuffledLoads = [&, &TTI = *TTI](Align CommonAlignment,
                                                unsigned *BestVF,
                                                bool ProfitableGatherPointers) {
    if (BestVF)
      *BestVF = 0;
    // Compare masked gather cost and loads + insert subvector costs.
    TTI::TargetCostKind CostKind = TTI::TCK_RecipThroughput;
    auto [ScalarGEPCost, VectorGEPCost] =
        getGEPCosts(TTI, PointerOps, PointerOps.front(),
                    Instruction::GetElementPtr, CostKind, ScalarTy, VecTy);
    // Estimate the cost of masked gather GEP. If not a splat, roughly
    // estimate as a buildvector, otherwise estimate as splat.
    APInt DemandedElts = APInt::getAllOnes(VecTy->getNumElements());
    VectorType *PtrVecTy =
        getWidenedType(PointerOps.front()->getType()->getScalarType(),
                       VecTy->getNumElements());
    if (static_cast<unsigned>(count_if(
            PointerOps, IsaPred<GetElementPtrInst>)) < PointerOps.size() - 1 ||
        any_of(PointerOps, [&](Value *V) {
          return getUnderlyingObject(V) !=
                 getUnderlyingObject(PointerOps.front());
        }))
      VectorGEPCost += TTI.getScalarizationOverhead(
          PtrVecTy, DemandedElts, /*Insert=*/true, /*Extract=*/false, CostKind);
    else
      VectorGEPCost +=
          TTI.getScalarizationOverhead(
              PtrVecTy, APInt::getOneBitSet(VecTy->getNumElements(), 0),
              /*Insert=*/true, /*Extract=*/false, CostKind) +
          ::getShuffleCost(TTI, TTI::SK_Broadcast, PtrVecTy, {}, CostKind);
    // The cost of scalar loads.
    InstructionCost ScalarLoadsCost =
        std::accumulate(VL.begin(), VL.end(), InstructionCost(),
                        [&](InstructionCost C, Value *V) {
                          return C + TTI.getInstructionCost(
                                         cast<Instruction>(V), CostKind);
                        }) +
        ScalarGEPCost;
    // The cost of masked gather.
    InstructionCost MaskedGatherCost =
        TTI.getGatherScatterOpCost(
            Instruction::Load, VecTy, cast<LoadInst>(VL0)->getPointerOperand(),
            /*VariableMask=*/false, CommonAlignment, CostKind) +
        (ProfitableGatherPointers ? 0 : VectorGEPCost);
    InstructionCost GatherCost =
        TTI.getScalarizationOverhead(VecTy, DemandedElts, /*Insert=*/true,
                                     /*Extract=*/false, CostKind) +
        ScalarLoadsCost;
    // The list of loads is small or perform partial check already - directly
    // compare masked gather cost and gather cost.
    constexpr unsigned ListLimit = 4;
    if (!TryRecursiveCheck || VL.size() < ListLimit)
      return MaskedGatherCost - GatherCost >= -SLPCostThreshold;

    // FIXME: The following code has not been updated for non-power-of-2
    // vectors.  The splitting logic here does not cover the original
    // vector if the vector factor is not a power of two.  FIXME
    if (!has_single_bit(VL.size()))
      return false;

    unsigned Sz = DL->getTypeSizeInBits(ScalarTy);
    unsigned MinVF = getMinVF(2 * Sz);
    DemandedElts.clearAllBits();
    // Iterate through possible vectorization factors and check if vectorized +
    // shuffles is better than just gather.
    for (unsigned VF = VL.size() / 2; VF >= MinVF; VF /= 2) {
      SmallVector<LoadsState> States;
      for (unsigned Cnt = 0, End = VL.size(); Cnt + VF <= End; Cnt += VF) {
        ArrayRef<Value *> Slice = VL.slice(Cnt, VF);
        SmallVector<unsigned> Order;
        SmallVector<Value *> PointerOps;
        LoadsState LS =
            canVectorizeLoads(Slice, Slice.front(), Order, PointerOps, BestVF,
                              /*TryRecursiveCheck=*/false);
        // Check that the sorted loads are consecutive.
        if (LS == LoadsState::Gather) {
          if (BestVF) {
            DemandedElts.setAllBits();
            break;
          }
          DemandedElts.setBits(Cnt, Cnt + VF);
          continue;
        }
        // If need the reorder - consider as high-cost masked gather for now.
        if ((LS == LoadsState::Vectorize ||
             LS == LoadsState::StridedVectorize) &&
            !Order.empty() && !isReverseOrder(Order))
          LS = LoadsState::ScatterVectorize;
        States.push_back(LS);
      }
      if (DemandedElts.isAllOnes())
        // All loads gathered - try smaller VF.
        continue;
      // Can be vectorized later as a serie of loads/insertelements.
      InstructionCost VecLdCost = 0;
      if (!DemandedElts.isZero()) {
        VecLdCost =
            TTI.getScalarizationOverhead(VecTy, DemandedElts, /*Insert=*/true,
                                         /*Extract=*/false, CostKind) +
            ScalarGEPCost;
        for (unsigned Idx : seq<unsigned>(VL.size()))
          if (DemandedElts[Idx])
            VecLdCost +=
                TTI.getInstructionCost(cast<Instruction>(VL[Idx]), CostKind);
      }
      auto *SubVecTy = getWidenedType(ScalarTy, VF);
      for (auto [I, LS] : enumerate(States)) {
        auto *LI0 = cast<LoadInst>(VL[I * VF]);
        InstructionCost VectorGEPCost =
            (LS == LoadsState::ScatterVectorize && ProfitableGatherPointers)
                ? 0
                : getGEPCosts(TTI, ArrayRef(PointerOps).slice(I * VF, VF),
                              LI0->getPointerOperand(),
                              Instruction::GetElementPtr, CostKind, ScalarTy,
                              SubVecTy)
                      .second;
        if (LS == LoadsState::ScatterVectorize) {
          if (static_cast<unsigned>(
                  count_if(PointerOps, IsaPred<GetElementPtrInst>)) <
                  PointerOps.size() - 1 ||
              any_of(PointerOps, [&](Value *V) {
                return getUnderlyingObject(V) !=
                       getUnderlyingObject(PointerOps.front());
              }))
            VectorGEPCost += TTI.getScalarizationOverhead(
                SubVecTy, APInt::getAllOnes(VF),
                /*Insert=*/true, /*Extract=*/false, CostKind);
          else
            VectorGEPCost += TTI.getScalarizationOverhead(
                                 SubVecTy, APInt::getOneBitSet(VF, 0),
                                 /*Insert=*/true, /*Extract=*/false, CostKind) +
                             ::getShuffleCost(TTI, TTI::SK_Broadcast, SubVecTy,
                                              {}, CostKind);
        }
        switch (LS) {
        case LoadsState::Vectorize:
          VecLdCost +=
              TTI.getMemoryOpCost(Instruction::Load, SubVecTy, LI0->getAlign(),
                                  LI0->getPointerAddressSpace(), CostKind,
                                  TTI::OperandValueInfo()) +
              VectorGEPCost;
          break;
        case LoadsState::StridedVectorize:
          VecLdCost += TTI.getStridedMemoryOpCost(Instruction::Load, SubVecTy,
                                                  LI0->getPointerOperand(),
                                                  /*VariableMask=*/false,
                                                  CommonAlignment, CostKind) +
                       VectorGEPCost;
          break;
        case LoadsState::ScatterVectorize:
          VecLdCost += TTI.getGatherScatterOpCost(Instruction::Load, SubVecTy,
                                                  LI0->getPointerOperand(),
                                                  /*VariableMask=*/false,
                                                  CommonAlignment, CostKind) +
                       VectorGEPCost;
          break;
        case LoadsState::Gather:
          // Gathers are already calculated - ignore.
          continue;
        }
        SmallVector<int> ShuffleMask(VL.size());
        for (int Idx : seq<int>(0, VL.size()))
          ShuffleMask[Idx] = Idx / VF == I ? VL.size() + Idx % VF : Idx;
        if (I > 0)
          VecLdCost +=
              ::getShuffleCost(TTI, TTI::SK_InsertSubvector, VecTy, ShuffleMask,
                               CostKind, I * VF, SubVecTy);
      }
      // If masked gather cost is higher - better to vectorize, so
      // consider it as a gather node. It will be better estimated
      // later.
      if (MaskedGatherCost >= VecLdCost &&
          VecLdCost - GatherCost < -SLPCostThreshold) {
        if (BestVF)
          *BestVF = VF;
        return true;
      }
    }
    return MaskedGatherCost - GatherCost >= -SLPCostThreshold;
  };
  // TODO: need to improve analysis of the pointers, if not all of them are
  // GEPs or have > 2 operands, we end up with a gather node, which just
  // increases the cost.
  Loop *L = LI->getLoopFor(cast<LoadInst>(VL0)->getParent());
  bool ProfitableGatherPointers =
      L && Sz > 2 && static_cast<unsigned>(count_if(PointerOps, [L](Value *V) {
                       return L->isLoopInvariant(V);
                     })) <= Sz / 2;
  if (ProfitableGatherPointers || all_of(PointerOps, [IsSorted](Value *P) {
        auto *GEP = dyn_cast<GetElementPtrInst>(P);
        return (IsSorted && !GEP && doesNotNeedToBeScheduled(P)) ||
               (GEP && GEP->getNumOperands() == 2 &&
                isa<Constant, Instruction>(GEP->getOperand(1)));
      })) {
    // Check if potential masked gather can be represented as series
    // of loads + insertsubvectors.
    // If masked gather cost is higher - better to vectorize, so
    // consider it as a gather node. It will be better estimated
    // later.
    if (!TryRecursiveCheck || !CheckForShuffledLoads(CommonAlignment, BestVF,
                                                     ProfitableGatherPointers))
      return LoadsState::ScatterVectorize;
  }

  return LoadsState::Gather;
}

static bool clusterSortPtrAccesses(ArrayRef<Value *> VL, Type *ElemTy,
                                   const DataLayout &DL, ScalarEvolution &SE,
                                   SmallVectorImpl<unsigned> &SortedIndices) {
  assert(llvm::all_of(
             VL, [](const Value *V) { return V->getType()->isPointerTy(); }) &&
         "Expected list of pointer operands.");
  // Map from bases to a vector of (Ptr, Offset, OrigIdx), which we insert each
  // Ptr into, sort and return the sorted indices with values next to one
  // another.
  MapVector<Value *, SmallVector<std::tuple<Value *, int, unsigned>>> Bases;
  Bases[VL[0]].push_back(std::make_tuple(VL[0], 0U, 0U));

  unsigned Cnt = 1;
  for (Value *Ptr : VL.drop_front()) {
    bool Found = any_of(Bases, [&](auto &Base) {
      std::optional<int> Diff =
          getPointersDiff(ElemTy, Base.first, ElemTy, Ptr, DL, SE,
                          /*StrictCheck=*/true);
      if (!Diff)
        return false;

      Base.second.emplace_back(Ptr, *Diff, Cnt++);
      return true;
    });

    if (!Found) {
      // If we haven't found enough to usefully cluster, return early.
      if (Bases.size() > VL.size() / 2 - 1)
        return false;

      // Not found already - add a new Base
      Bases[Ptr].emplace_back(Ptr, 0, Cnt++);
    }
  }

  // For each of the bases sort the pointers by Offset and check if any of the
  // base become consecutively allocated.
  bool AnyConsecutive = false;
  for (auto &Base : Bases) {
    auto &Vec = Base.second;
    if (Vec.size() > 1) {
      llvm::stable_sort(Vec, [](const std::tuple<Value *, int, unsigned> &X,
                                const std::tuple<Value *, int, unsigned> &Y) {
        return std::get<1>(X) < std::get<1>(Y);
      });
      int InitialOffset = std::get<1>(Vec[0]);
      AnyConsecutive |= all_of(enumerate(Vec), [InitialOffset](const auto &P) {
        return std::get<1>(P.value()) == int(P.index()) + InitialOffset;
      });
    }
  }

  // Fill SortedIndices array only if it looks worth-while to sort the ptrs.
  SortedIndices.clear();
  if (!AnyConsecutive)
    return false;

  // If we have a better order, also sort the base pointers by increasing
  // (variable) values if possible, to try and keep the order more regular. In
  // order to create a valid strict-weak order we cluster by the Root of gep
  // chains and sort within each.
  SmallVector<std::tuple<Value *, Value *, Value *>> SortedBases;
  for (auto &Base : Bases) {
    Value *Strip = Base.first->stripInBoundsConstantOffsets();
    Value *Root = Strip;
    while (auto *Gep = dyn_cast<GetElementPtrInst>(Root))
      Root = Gep->getOperand(0);
    SortedBases.emplace_back(Base.first, Strip, Root);
  }
  auto *Begin = SortedBases.begin();
  auto *End = SortedBases.end();
  while (Begin != End) {
    Value *Root = std::get<2>(*Begin);
    auto *Mid = std::stable_partition(
        Begin, End, [&Root](auto V) { return std::get<2>(V) == Root; });
    DenseMap<Value *, DenseMap<Value *, bool>> LessThan;
    for (auto *I = Begin; I < Mid; ++I)
      LessThan.try_emplace(std::get<1>(*I));
    for (auto *I = Begin; I < Mid; ++I) {
      Value *V = std::get<1>(*I);
      while (auto *Gep = dyn_cast<GetElementPtrInst>(V)) {
        V = Gep->getOperand(0);
        if (LessThan.contains(V))
          LessThan[V][std::get<1>(*I)] = true;
      }
    }
    std::stable_sort(Begin, Mid, [&LessThan](auto &V1, auto &V2) {
      return LessThan[std::get<1>(V1)][std::get<1>(V2)];
    });
    Begin = Mid;
  }

  // Collect the final order of sorted indices
  for (auto Base : SortedBases)
    for (auto &T : Bases[std::get<0>(Base)])
      SortedIndices.push_back(std::get<2>(T));

  assert(SortedIndices.size() == VL.size() &&
         "Expected SortedIndices to be the size of VL");
  return true;
}

std::optional<BoUpSLP::OrdersType>
BoUpSLP::findPartiallyOrderedLoads(const BoUpSLP::TreeEntry &TE) {
  assert(TE.isGather() && "Expected gather node only.");
  Type *ScalarTy = TE.Scalars[0]->getType();

  SmallVector<Value *> Ptrs;
  Ptrs.reserve(TE.Scalars.size());
  for (Value *V : TE.Scalars) {
    auto *L = dyn_cast<LoadInst>(V);
    if (!L || !L->isSimple())
      return std::nullopt;
    Ptrs.push_back(L->getPointerOperand());
  }

  BoUpSLP::OrdersType Order;
  if (clusterSortPtrAccesses(Ptrs, ScalarTy, *DL, *SE, Order))
    return std::move(Order);
  return std::nullopt;
}

/// Check if two insertelement instructions are from the same buildvector.
static bool areTwoInsertFromSameBuildVector(
    InsertElementInst *VU, InsertElementInst *V,
    function_ref<Value *(InsertElementInst *)> GetBaseOperand) {
  // Instructions must be from the same basic blocks.
  if (VU->getParent() != V->getParent())
    return false;
  // Checks if 2 insertelements are from the same buildvector.
  if (VU->getType() != V->getType())
    return false;
  // Multiple used inserts are separate nodes.
  if (!VU->hasOneUse() && !V->hasOneUse())
    return false;
  auto *IE1 = VU;
  auto *IE2 = V;
  std::optional<unsigned> Idx1 = getElementIndex(IE1);
  std::optional<unsigned> Idx2 = getElementIndex(IE2);
  if (Idx1 == std::nullopt || Idx2 == std::nullopt)
    return false;
  // Go through the vector operand of insertelement instructions trying to find
  // either VU as the original vector for IE2 or V as the original vector for
  // IE1.
  SmallBitVector ReusedIdx(
      cast<VectorType>(VU->getType())->getElementCount().getKnownMinValue());
  bool IsReusedIdx = false;
  do {
    if (IE2 == VU && !IE1)
      return VU->hasOneUse();
    if (IE1 == V && !IE2)
      return V->hasOneUse();
    if (IE1 && IE1 != V) {
      unsigned Idx1 = getElementIndex(IE1).value_or(*Idx2);
      IsReusedIdx |= ReusedIdx.test(Idx1);
      ReusedIdx.set(Idx1);
      if ((IE1 != VU && !IE1->hasOneUse()) || IsReusedIdx)
        IE1 = nullptr;
      else
        IE1 = dyn_cast_or_null<InsertElementInst>(GetBaseOperand(IE1));
    }
    if (IE2 && IE2 != VU) {
      unsigned Idx2 = getElementIndex(IE2).value_or(*Idx1);
      IsReusedIdx |= ReusedIdx.test(Idx2);
      ReusedIdx.set(Idx2);
      if ((IE2 != V && !IE2->hasOneUse()) || IsReusedIdx)
        IE2 = nullptr;
      else
        IE2 = dyn_cast_or_null<InsertElementInst>(GetBaseOperand(IE2));
    }
  } while (!IsReusedIdx && (IE1 || IE2));
  return false;
}

std::optional<BoUpSLP::OrdersType>
BoUpSLP::getReorderingData(const TreeEntry &TE, bool TopToBottom) {
  // No need to reorder if need to shuffle reuses, still need to shuffle the
  // node.
  if (!TE.ReuseShuffleIndices.empty()) {
    // FIXME: Support ReuseShuffleIndices for non-power-of-two vectors.
    assert(!TE.isNonPowOf2Vec() &&
           "Reshuffling scalars not yet supported for nodes with padding");

    if (isSplat(TE.Scalars))
      return std::nullopt;
    // Check if reuse shuffle indices can be improved by reordering.
    // For this, check that reuse mask is "clustered", i.e. each scalar values
    // is used once in each submask of size <number_of_scalars>.
    // Example: 4 scalar values.
    // ReuseShuffleIndices mask: 0, 1, 2, 3, 3, 2, 0, 1 - clustered.
    //                           0, 1, 2, 3, 3, 3, 1, 0 - not clustered, because
    //                           element 3 is used twice in the second submask.
    unsigned Sz = TE.Scalars.size();
    if (TE.isGather()) {
      if (std::optional<OrdersType> CurrentOrder =
              findReusedOrderedScalars(TE)) {
        SmallVector<int> Mask;
        fixupOrderingIndices(*CurrentOrder);
        inversePermutation(*CurrentOrder, Mask);
        ::addMask(Mask, TE.ReuseShuffleIndices);
        OrdersType Res(TE.getVectorFactor(), TE.getVectorFactor());
        unsigned Sz = TE.Scalars.size();
        for (int K = 0, E = TE.getVectorFactor() / Sz; K < E; ++K) {
          for (auto [I, Idx] : enumerate(ArrayRef(Mask).slice(K * Sz, Sz)))
            if (Idx != PoisonMaskElem)
              Res[Idx + K * Sz] = I + K * Sz;
        }
        return std::move(Res);
      }
    }
    if (Sz == 2 && TE.getVectorFactor() == 4 &&
        TTI->getNumberOfParts(getWidenedType(TE.Scalars.front()->getType(),
                                             2 * TE.getVectorFactor())) == 1)
      return std::nullopt;
    if (!ShuffleVectorInst::isOneUseSingleSourceMask(TE.ReuseShuffleIndices,
                                                     Sz)) {
      SmallVector<int> ReorderMask(Sz, PoisonMaskElem);
      if (TE.ReorderIndices.empty())
        std::iota(ReorderMask.begin(), ReorderMask.end(), 0);
      else
        inversePermutation(TE.ReorderIndices, ReorderMask);
      ::addMask(ReorderMask, TE.ReuseShuffleIndices);
      unsigned VF = ReorderMask.size();
      OrdersType ResOrder(VF, VF);
      unsigned NumParts = divideCeil(VF, Sz);
      SmallBitVector UsedVals(NumParts);
      for (unsigned I = 0; I < VF; I += Sz) {
        int Val = PoisonMaskElem;
        unsigned UndefCnt = 0;
        unsigned Limit = std::min(Sz, VF - I);
        if (any_of(ArrayRef(ReorderMask).slice(I, Limit),
                   [&](int Idx) {
                     if (Val == PoisonMaskElem && Idx != PoisonMaskElem)
                       Val = Idx;
                     if (Idx == PoisonMaskElem)
                       ++UndefCnt;
                     return Idx != PoisonMaskElem && Idx != Val;
                   }) ||
            Val >= static_cast<int>(NumParts) || UsedVals.test(Val) ||
            UndefCnt > Sz / 2)
          return std::nullopt;
        UsedVals.set(Val);
        for (unsigned K = 0; K < NumParts; ++K)
          ResOrder[Val + Sz * K] = I + K;
      }
      return std::move(ResOrder);
    }
    unsigned VF = TE.getVectorFactor();
    // Try build correct order for extractelement instructions.
    SmallVector<int> ReusedMask(TE.ReuseShuffleIndices.begin(),
                                TE.ReuseShuffleIndices.end());
    if (TE.getOpcode() == Instruction::ExtractElement && !TE.isAltShuffle() &&
        all_of(TE.Scalars, [Sz](Value *V) {
          std::optional<unsigned> Idx = getExtractIndex(cast<Instruction>(V));
          return Idx && *Idx < Sz;
        })) {
      SmallVector<int> ReorderMask(Sz, PoisonMaskElem);
      if (TE.ReorderIndices.empty())
        std::iota(ReorderMask.begin(), ReorderMask.end(), 0);
      else
        inversePermutation(TE.ReorderIndices, ReorderMask);
      for (unsigned I = 0; I < VF; ++I) {
        int &Idx = ReusedMask[I];
        if (Idx == PoisonMaskElem)
          continue;
        Value *V = TE.Scalars[ReorderMask[Idx]];
        std::optional<unsigned> EI = getExtractIndex(cast<Instruction>(V));
        Idx = std::distance(ReorderMask.begin(), find(ReorderMask, *EI));
      }
    }
    // Build the order of the VF size, need to reorder reuses shuffles, they are
    // always of VF size.
    OrdersType ResOrder(VF);
    std::iota(ResOrder.begin(), ResOrder.end(), 0);
    auto *It = ResOrder.begin();
    for (unsigned K = 0; K < VF; K += Sz) {
      OrdersType CurrentOrder(TE.ReorderIndices);
      SmallVector<int> SubMask{ArrayRef(ReusedMask).slice(K, Sz)};
      if (SubMask.front() == PoisonMaskElem)
        std::iota(SubMask.begin(), SubMask.end(), 0);
      reorderOrder(CurrentOrder, SubMask);
      transform(CurrentOrder, It, [K](unsigned Pos) { return Pos + K; });
      std::advance(It, Sz);
    }
    if (TE.isGather() && all_of(enumerate(ResOrder), [](const auto &Data) {
          return Data.index() == Data.value();
        }))
      return std::nullopt; // No need to reorder.
    return std::move(ResOrder);
  }
  if (TE.State == TreeEntry::StridedVectorize && !TopToBottom &&
      any_of(TE.UserTreeIndices,
             [](const EdgeInfo &EI) {
               return !Instruction::isBinaryOp(EI.UserTE->getOpcode());
             }) &&
      (TE.ReorderIndices.empty() || isReverseOrder(TE.ReorderIndices)))
    return std::nullopt;
  if ((TE.State == TreeEntry::Vectorize ||
       TE.State == TreeEntry::StridedVectorize) &&
      (isa<LoadInst, ExtractElementInst, ExtractValueInst>(TE.getMainOp()) ||
       (TopToBottom && isa<StoreInst, InsertElementInst>(TE.getMainOp()))) &&
      !TE.isAltShuffle())
    return TE.ReorderIndices;
  if (TE.State == TreeEntry::Vectorize && TE.getOpcode() == Instruction::PHI) {
    if (!TE.ReorderIndices.empty())
      return TE.ReorderIndices;

    auto PHICompare = [&](unsigned I1, unsigned I2) {
      Value *V1 = TE.Scalars[I1];
      Value *V2 = TE.Scalars[I2];
      if (V1 == V2 || (V1->getNumUses() == 0 && V2->getNumUses() == 0))
        return false;
      if (V1->getNumUses() < V2->getNumUses())
        return true;
      if (V1->getNumUses() > V2->getNumUses())
        return false;
      auto *FirstUserOfPhi1 = cast<Instruction>(*V1->user_begin());
      auto *FirstUserOfPhi2 = cast<Instruction>(*V2->user_begin());
      if (auto *IE1 = dyn_cast<InsertElementInst>(FirstUserOfPhi1))
        if (auto *IE2 = dyn_cast<InsertElementInst>(FirstUserOfPhi2)) {
          if (!areTwoInsertFromSameBuildVector(
                  IE1, IE2,
                  [](InsertElementInst *II) { return II->getOperand(0); }))
            return I1 < I2;
          return getElementIndex(IE1) < getElementIndex(IE2);
        }
      if (auto *EE1 = dyn_cast<ExtractElementInst>(FirstUserOfPhi1))
        if (auto *EE2 = dyn_cast<ExtractElementInst>(FirstUserOfPhi2)) {
          if (EE1->getOperand(0) != EE2->getOperand(0))
            return I1 < I2;
          return getElementIndex(EE1) < getElementIndex(EE2);
        }
      return I1 < I2;
    };
    DenseMap<unsigned, unsigned> PhiToId;
    SmallVector<unsigned> Phis(TE.Scalars.size());
    std::iota(Phis.begin(), Phis.end(), 0);
    OrdersType ResOrder(TE.Scalars.size());
    for (unsigned Id = 0, Sz = TE.Scalars.size(); Id < Sz; ++Id)
      PhiToId[Id] = Id;
    stable_sort(Phis, PHICompare);
    for (unsigned Id = 0, Sz = Phis.size(); Id < Sz; ++Id)
      ResOrder[Id] = PhiToId[Phis[Id]];
    if (isIdentityOrder(ResOrder))
      return std::nullopt; // No need to reorder.
    return std::move(ResOrder);
  }
  if (TE.isGather() && !TE.isAltShuffle() && allSameType(TE.Scalars)) {
    // TODO: add analysis of other gather nodes with extractelement
    // instructions and other values/instructions, not only undefs.
    if ((TE.getOpcode() == Instruction::ExtractElement ||
         (all_of(TE.Scalars, IsaPred<UndefValue, ExtractElementInst>) &&
          any_of(TE.Scalars, IsaPred<ExtractElementInst>))) &&
        all_of(TE.Scalars, [](Value *V) {
          auto *EE = dyn_cast<ExtractElementInst>(V);
          return !EE || isa<FixedVectorType>(EE->getVectorOperandType());
        })) {
      // Check that gather of extractelements can be represented as
      // just a shuffle of a single vector.
      OrdersType CurrentOrder;
      bool Reuse = canReuseExtract(TE.Scalars, TE.getMainOp(), CurrentOrder,
                                   /*ResizeAllowed=*/true);
      if (Reuse || !CurrentOrder.empty())
        return std::move(CurrentOrder);
    }
    // If the gather node is <undef, v, .., poison> and
    // insertelement poison, v, 0 [+ permute]
    // is cheaper than
    // insertelement poison, v, n - try to reorder.
    // If rotating the whole graph, exclude the permute cost, the whole graph
    // might be transformed.
    int Sz = TE.Scalars.size();
    if (isSplat(TE.Scalars) && !allConstant(TE.Scalars) &&
        count_if(TE.Scalars, IsaPred<UndefValue>) == Sz - 1) {
      const auto *It =
          find_if(TE.Scalars, [](Value *V) { return !isConstant(V); });
      if (It == TE.Scalars.begin())
        return OrdersType();
      auto *Ty = getWidenedType(TE.Scalars.front()->getType(), Sz);
      if (It != TE.Scalars.end()) {
        OrdersType Order(Sz, Sz);
        unsigned Idx = std::distance(TE.Scalars.begin(), It);
        Order[Idx] = 0;
        fixupOrderingIndices(Order);
        SmallVector<int> Mask;
        inversePermutation(Order, Mask);
        InstructionCost PermuteCost =
            TopToBottom
                ? 0
                : ::getShuffleCost(*TTI, TTI::SK_PermuteSingleSrc, Ty, Mask);
        InstructionCost InsertFirstCost = TTI->getVectorInstrCost(
            Instruction::InsertElement, Ty, TTI::TCK_RecipThroughput, 0,
            PoisonValue::get(Ty), *It);
        InstructionCost InsertIdxCost = TTI->getVectorInstrCost(
            Instruction::InsertElement, Ty, TTI::TCK_RecipThroughput, Idx,
            PoisonValue::get(Ty), *It);
        if (InsertFirstCost + PermuteCost < InsertIdxCost) {
          OrdersType Order(Sz, Sz);
          Order[Idx] = 0;
          return std::move(Order);
        }
      }
    }
    if (isSplat(TE.Scalars))
      return std::nullopt;
    if (TE.Scalars.size() >= 3)
      if (std::optional<OrdersType> Order = findPartiallyOrderedLoads(TE))
        return Order;
    // Check if can include the order of vectorized loads. For masked gathers do
    // extra analysis later, so include such nodes into a special list.
    if (TE.isGather() && TE.getOpcode() == Instruction::Load) {
      SmallVector<Value *> PointerOps;
      OrdersType CurrentOrder;
      LoadsState Res = canVectorizeLoads(TE.Scalars, TE.Scalars.front(),
                                         CurrentOrder, PointerOps);
      if (Res == LoadsState::Vectorize || Res == LoadsState::StridedVectorize)
        return std::move(CurrentOrder);
    }
    // FIXME: Remove the non-power-of-two check once findReusedOrderedScalars
    // has been auditted for correctness with non-power-of-two vectors.
    if (!TE.isNonPowOf2Vec())
      if (std::optional<OrdersType> CurrentOrder = findReusedOrderedScalars(TE))
        return CurrentOrder;
  }
  return std::nullopt;
}

/// Checks if the given mask is a "clustered" mask with the same clusters of
/// size \p Sz, which are not identity submasks.
static bool isRepeatedNonIdentityClusteredMask(ArrayRef<int> Mask,
                                               unsigned Sz) {
  ArrayRef<int> FirstCluster = Mask.slice(0, Sz);
  if (ShuffleVectorInst::isIdentityMask(FirstCluster, Sz))
    return false;
  for (unsigned I = Sz, E = Mask.size(); I < E; I += Sz) {
    ArrayRef<int> Cluster = Mask.slice(I, Sz);
    if (Cluster != FirstCluster)
      return false;
  }
  return true;
}

void BoUpSLP::reorderNodeWithReuses(TreeEntry &TE, ArrayRef<int> Mask) const {
  // Reorder reuses mask.
  reorderReuses(TE.ReuseShuffleIndices, Mask);
  const unsigned Sz = TE.Scalars.size();
  // For vectorized and non-clustered reused no need to do anything else.
  if (!TE.isGather() ||
      !ShuffleVectorInst::isOneUseSingleSourceMask(TE.ReuseShuffleIndices,
                                                   Sz) ||
      !isRepeatedNonIdentityClusteredMask(TE.ReuseShuffleIndices, Sz))
    return;
  SmallVector<int> NewMask;
  inversePermutation(TE.ReorderIndices, NewMask);
  addMask(NewMask, TE.ReuseShuffleIndices);
  // Clear reorder since it is going to be applied to the new mask.
  TE.ReorderIndices.clear();
  // Try to improve gathered nodes with clustered reuses, if possible.
  ArrayRef<int> Slice = ArrayRef(NewMask).slice(0, Sz);
  SmallVector<unsigned> NewOrder(Slice);
  inversePermutation(NewOrder, NewMask);
  reorderScalars(TE.Scalars, NewMask);
  // Fill the reuses mask with the identity submasks.
  for (auto *It = TE.ReuseShuffleIndices.begin(),
            *End = TE.ReuseShuffleIndices.end();
       It != End; std::advance(It, Sz))
    std::iota(It, std::next(It, Sz), 0);
}

static void combineOrders(MutableArrayRef<unsigned> Order,
                          ArrayRef<unsigned> SecondaryOrder) {
  assert((SecondaryOrder.empty() || Order.size() == SecondaryOrder.size()) &&
         "Expected same size of orders");
  unsigned Sz = Order.size();
  SmallBitVector UsedIndices(Sz);
  for (unsigned Idx : seq<unsigned>(0, Sz)) {
    if (Order[Idx] != Sz)
      UsedIndices.set(Order[Idx]);
  }
  if (SecondaryOrder.empty()) {
    for (unsigned Idx : seq<unsigned>(0, Sz))
      if (Order[Idx] == Sz && !UsedIndices.test(Idx))
        Order[Idx] = Idx;
  } else {
    for (unsigned Idx : seq<unsigned>(0, Sz))
      if (SecondaryOrder[Idx] != Sz && Order[Idx] == Sz &&
          !UsedIndices.test(SecondaryOrder[Idx]))
        Order[Idx] = SecondaryOrder[Idx];
  }
}

void BoUpSLP::reorderTopToBottom() {
  // Maps VF to the graph nodes.
  DenseMap<unsigned, SetVector<TreeEntry *>> VFToOrderedEntries;
  // ExtractElement gather nodes which can be vectorized and need to handle
  // their ordering.
  DenseMap<const TreeEntry *, OrdersType> GathersToOrders;

  // Phi nodes can have preferred ordering based on their result users
  DenseMap<const TreeEntry *, OrdersType> PhisToOrders;

  // AltShuffles can also have a preferred ordering that leads to fewer
  // instructions, e.g., the addsub instruction in x86.
  DenseMap<const TreeEntry *, OrdersType> AltShufflesToOrders;

  // Maps a TreeEntry to the reorder indices of external users.
  DenseMap<const TreeEntry *, SmallVector<OrdersType, 1>>
      ExternalUserReorderMap;
  // Find all reorderable nodes with the given VF.
  // Currently the are vectorized stores,loads,extracts + some gathering of
  // extracts.
  for_each(VectorizableTree, [&, &TTIRef = *TTI](
                                 const std::unique_ptr<TreeEntry> &TE) {
    // Look for external users that will probably be vectorized.
    SmallVector<OrdersType, 1> ExternalUserReorderIndices =
        findExternalStoreUsersReorderIndices(TE.get());
    if (!ExternalUserReorderIndices.empty()) {
      VFToOrderedEntries[TE->getVectorFactor()].insert(TE.get());
      ExternalUserReorderMap.try_emplace(TE.get(),
                                         std::move(ExternalUserReorderIndices));
    }

    // Patterns like [fadd,fsub] can be combined into a single instruction in
    // x86. Reordering them into [fsub,fadd] blocks this pattern. So we need
    // to take into account their order when looking for the most used order.
    if (TE->isAltShuffle()) {
      VectorType *VecTy =
          getWidenedType(TE->Scalars[0]->getType(), TE->Scalars.size());
      unsigned Opcode0 = TE->getOpcode();
      unsigned Opcode1 = TE->getAltOpcode();
      SmallBitVector OpcodeMask(getAltInstrMask(TE->Scalars, Opcode0, Opcode1));
      // If this pattern is supported by the target then we consider the order.
      if (TTIRef.isLegalAltInstr(VecTy, Opcode0, Opcode1, OpcodeMask)) {
        VFToOrderedEntries[TE->getVectorFactor()].insert(TE.get());
        AltShufflesToOrders.try_emplace(TE.get(), OrdersType());
      }
      // TODO: Check the reverse order too.
    }

    if (std::optional<OrdersType> CurrentOrder =
            getReorderingData(*TE, /*TopToBottom=*/true)) {
      // Do not include ordering for nodes used in the alt opcode vectorization,
      // better to reorder them during bottom-to-top stage. If follow the order
      // here, it causes reordering of the whole graph though actually it is
      // profitable just to reorder the subgraph that starts from the alternate
      // opcode vectorization node. Such nodes already end-up with the shuffle
      // instruction and it is just enough to change this shuffle rather than
      // rotate the scalars for the whole graph.
      unsigned Cnt = 0;
      const TreeEntry *UserTE = TE.get();
      while (UserTE && Cnt < RecursionMaxDepth) {
        if (UserTE->UserTreeIndices.size() != 1)
          break;
        if (all_of(UserTE->UserTreeIndices, [](const EdgeInfo &EI) {
              return EI.UserTE->State == TreeEntry::Vectorize &&
                     EI.UserTE->isAltShuffle() && EI.UserTE->Idx != 0;
            }))
          return;
        UserTE = UserTE->UserTreeIndices.back().UserTE;
        ++Cnt;
      }
      VFToOrderedEntries[TE->getVectorFactor()].insert(TE.get());
      if (!(TE->State == TreeEntry::Vectorize ||
            TE->State == TreeEntry::StridedVectorize) ||
          !TE->ReuseShuffleIndices.empty())
        GathersToOrders.try_emplace(TE.get(), *CurrentOrder);
      if (TE->State == TreeEntry::Vectorize &&
          TE->getOpcode() == Instruction::PHI)
        PhisToOrders.try_emplace(TE.get(), *CurrentOrder);
    }
  });

  // Reorder the graph nodes according to their vectorization factor.
  for (unsigned VF = VectorizableTree.front()->getVectorFactor(); VF > 1;
       VF = bit_ceil(VF) / 2) {
    auto It = VFToOrderedEntries.find(VF);
    if (It == VFToOrderedEntries.end())
      continue;
    // Try to find the most profitable order. We just are looking for the most
    // used order and reorder scalar elements in the nodes according to this
    // mostly used order.
    ArrayRef<TreeEntry *> OrderedEntries = It->second.getArrayRef();
    // All operands are reordered and used only in this node - propagate the
    // most used order to the user node.
    MapVector<OrdersType, unsigned,
              DenseMap<OrdersType, unsigned, OrdersTypeDenseMapInfo>>
        OrdersUses;
    SmallPtrSet<const TreeEntry *, 4> VisitedOps;
    for (const TreeEntry *OpTE : OrderedEntries) {
      // No need to reorder this nodes, still need to extend and to use shuffle,
      // just need to merge reordering shuffle and the reuse shuffle.
      if (!OpTE->ReuseShuffleIndices.empty() && !GathersToOrders.count(OpTE))
        continue;
      // Count number of orders uses.
      const auto &Order = [OpTE, &GathersToOrders, &AltShufflesToOrders,
                           &PhisToOrders]() -> const OrdersType & {
        if (OpTE->isGather() || !OpTE->ReuseShuffleIndices.empty()) {
          auto It = GathersToOrders.find(OpTE);
          if (It != GathersToOrders.end())
            return It->second;
        }
        if (OpTE->isAltShuffle()) {
          auto It = AltShufflesToOrders.find(OpTE);
          if (It != AltShufflesToOrders.end())
            return It->second;
        }
        if (OpTE->State == TreeEntry::Vectorize &&
            OpTE->getOpcode() == Instruction::PHI) {
          auto It = PhisToOrders.find(OpTE);
          if (It != PhisToOrders.end())
            return It->second;
        }
        return OpTE->ReorderIndices;
      }();
      // First consider the order of the external scalar users.
      auto It = ExternalUserReorderMap.find(OpTE);
      if (It != ExternalUserReorderMap.end()) {
        const auto &ExternalUserReorderIndices = It->second;
        // If the OpTE vector factor != number of scalars - use natural order,
        // it is an attempt to reorder node with reused scalars but with
        // external uses.
        if (OpTE->getVectorFactor() != OpTE->Scalars.size()) {
          OrdersUses.insert(std::make_pair(OrdersType(), 0)).first->second +=
              ExternalUserReorderIndices.size();
        } else {
          for (const OrdersType &ExtOrder : ExternalUserReorderIndices)
            ++OrdersUses.insert(std::make_pair(ExtOrder, 0)).first->second;
        }
        // No other useful reorder data in this entry.
        if (Order.empty())
          continue;
      }
      // Stores actually store the mask, not the order, need to invert.
      if (OpTE->State == TreeEntry::Vectorize && !OpTE->isAltShuffle() &&
          OpTE->getOpcode() == Instruction::Store && !Order.empty()) {
        SmallVector<int> Mask;
        inversePermutation(Order, Mask);
        unsigned E = Order.size();
        OrdersType CurrentOrder(E, E);
        transform(Mask, CurrentOrder.begin(), [E](int Idx) {
          return Idx == PoisonMaskElem ? E : static_cast<unsigned>(Idx);
        });
        fixupOrderingIndices(CurrentOrder);
        ++OrdersUses.insert(std::make_pair(CurrentOrder, 0)).first->second;
      } else {
        ++OrdersUses.insert(std::make_pair(Order, 0)).first->second;
      }
    }
    if (OrdersUses.empty())
      continue;
    // Choose the most used order.
    unsigned IdentityCnt = 0;
    unsigned FilledIdentityCnt = 0;
    OrdersType IdentityOrder(VF, VF);
    for (auto &Pair : OrdersUses) {
      if (Pair.first.empty() || isIdentityOrder(Pair.first)) {
        if (!Pair.first.empty())
          FilledIdentityCnt += Pair.second;
        IdentityCnt += Pair.second;
        combineOrders(IdentityOrder, Pair.first);
      }
    }
    MutableArrayRef<unsigned> BestOrder = IdentityOrder;
    unsigned Cnt = IdentityCnt;
    for (auto &Pair : OrdersUses) {
      // Prefer identity order. But, if filled identity found (non-empty order)
      // with same number of uses, as the new candidate order, we can choose
      // this candidate order.
      if (Cnt < Pair.second ||
          (Cnt == IdentityCnt && IdentityCnt == FilledIdentityCnt &&
           Cnt == Pair.second && !BestOrder.empty() &&
           isIdentityOrder(BestOrder))) {
        combineOrders(Pair.first, BestOrder);
        BestOrder = Pair.first;
        Cnt = Pair.second;
      } else {
        combineOrders(BestOrder, Pair.first);
      }
    }
    // Set order of the user node.
    if (isIdentityOrder(BestOrder))
      continue;
    fixupOrderingIndices(BestOrder);
    SmallVector<int> Mask;
    inversePermutation(BestOrder, Mask);
    SmallVector<int> MaskOrder(BestOrder.size(), PoisonMaskElem);
    unsigned E = BestOrder.size();
    transform(BestOrder, MaskOrder.begin(), [E](unsigned I) {
      return I < E ? static_cast<int>(I) : PoisonMaskElem;
    });
    // Do an actual reordering, if profitable.
    for (std::unique_ptr<TreeEntry> &TE : VectorizableTree) {
      // Just do the reordering for the nodes with the given VF.
      if (TE->Scalars.size() != VF) {
        if (TE->ReuseShuffleIndices.size() == VF) {
          // Need to reorder the reuses masks of the operands with smaller VF to
          // be able to find the match between the graph nodes and scalar
          // operands of the given node during vectorization/cost estimation.
          assert(all_of(TE->UserTreeIndices,
                        [VF, &TE](const EdgeInfo &EI) {
                          return EI.UserTE->Scalars.size() == VF ||
                                 EI.UserTE->Scalars.size() ==
                                     TE->Scalars.size();
                        }) &&
                 "All users must be of VF size.");
          // Update ordering of the operands with the smaller VF than the given
          // one.
          reorderNodeWithReuses(*TE, Mask);
        }
        continue;
      }
      if ((TE->State == TreeEntry::Vectorize ||
           TE->State == TreeEntry::StridedVectorize) &&
          isa<ExtractElementInst, ExtractValueInst, LoadInst, StoreInst,
              InsertElementInst>(TE->getMainOp()) &&
          !TE->isAltShuffle()) {
        // Build correct orders for extract{element,value}, loads and
        // stores.
        reorderOrder(TE->ReorderIndices, Mask);
        if (isa<InsertElementInst, StoreInst>(TE->getMainOp()))
          TE->reorderOperands(Mask);
      } else {
        // Reorder the node and its operands.
        TE->reorderOperands(Mask);
        assert(TE->ReorderIndices.empty() &&
               "Expected empty reorder sequence.");
        reorderScalars(TE->Scalars, Mask);
      }
      if (!TE->ReuseShuffleIndices.empty()) {
        // Apply reversed order to keep the original ordering of the reused
        // elements to avoid extra reorder indices shuffling.
        OrdersType CurrentOrder;
        reorderOrder(CurrentOrder, MaskOrder);
        SmallVector<int> NewReuses;
        inversePermutation(CurrentOrder, NewReuses);
        addMask(NewReuses, TE->ReuseShuffleIndices);
        TE->ReuseShuffleIndices.swap(NewReuses);
      }
    }
  }
}

bool BoUpSLP::canReorderOperands(
    TreeEntry *UserTE, SmallVectorImpl<std::pair<unsigned, TreeEntry *>> &Edges,
    ArrayRef<TreeEntry *> ReorderableGathers,
    SmallVectorImpl<TreeEntry *> &GatherOps) {
  for (unsigned I = 0, E = UserTE->getNumOperands(); I < E; ++I) {
    if (any_of(Edges, [I](const std::pair<unsigned, TreeEntry *> &OpData) {
          return OpData.first == I &&
                 (OpData.second->State == TreeEntry::Vectorize ||
                  OpData.second->State == TreeEntry::StridedVectorize);
        }))
      continue;
    if (TreeEntry *TE = getVectorizedOperand(UserTE, I)) {
      // Do not reorder if operand node is used by many user nodes.
      if (any_of(TE->UserTreeIndices,
                 [UserTE](const EdgeInfo &EI) { return EI.UserTE != UserTE; }))
        return false;
      // Add the node to the list of the ordered nodes with the identity
      // order.
      Edges.emplace_back(I, TE);
      // Add ScatterVectorize nodes to the list of operands, where just
      // reordering of the scalars is required. Similar to the gathers, so
      // simply add to the list of gathered ops.
      // If there are reused scalars, process this node as a regular vectorize
      // node, just reorder reuses mask.
      if (TE->State != TreeEntry::Vectorize &&
          TE->State != TreeEntry::StridedVectorize &&
          TE->ReuseShuffleIndices.empty() && TE->ReorderIndices.empty())
        GatherOps.push_back(TE);
      continue;
    }
    TreeEntry *Gather = nullptr;
    if (count_if(ReorderableGathers,
                 [&Gather, UserTE, I](TreeEntry *TE) {
                   assert(TE->State != TreeEntry::Vectorize &&
                          TE->State != TreeEntry::StridedVectorize &&
                          "Only non-vectorized nodes are expected.");
                   if (any_of(TE->UserTreeIndices,
                              [UserTE, I](const EdgeInfo &EI) {
                                return EI.UserTE == UserTE && EI.EdgeIdx == I;
                              })) {
                     assert(TE->isSame(UserTE->getOperand(I)) &&
                            "Operand entry does not match operands.");
                     Gather = TE;
                     return true;
                   }
                   return false;
                 }) > 1 &&
        !allConstant(UserTE->getOperand(I)))
      return false;
    if (Gather)
      GatherOps.push_back(Gather);
  }
  return true;
}

void BoUpSLP::reorderBottomToTop(bool IgnoreReorder) {
  SetVector<TreeEntry *> OrderedEntries;
  DenseSet<const TreeEntry *> GathersToOrders;
  // Find all reorderable leaf nodes with the given VF.
  // Currently the are vectorized loads,extracts without alternate operands +
  // some gathering of extracts.
  SmallVector<TreeEntry *> NonVectorized;
  for (const std::unique_ptr<TreeEntry> &TE : VectorizableTree) {
    if (TE->State != TreeEntry::Vectorize &&
        TE->State != TreeEntry::StridedVectorize)
      NonVectorized.push_back(TE.get());
    if (std::optional<OrdersType> CurrentOrder =
            getReorderingData(*TE, /*TopToBottom=*/false)) {
      OrderedEntries.insert(TE.get());
      if (!(TE->State == TreeEntry::Vectorize ||
            TE->State == TreeEntry::StridedVectorize) ||
          !TE->ReuseShuffleIndices.empty())
        GathersToOrders.insert(TE.get());
    }
  }

  // 1. Propagate order to the graph nodes, which use only reordered nodes.
  // I.e., if the node has operands, that are reordered, try to make at least
  // one operand order in the natural order and reorder others + reorder the
  // user node itself.
  SmallPtrSet<const TreeEntry *, 4> Visited;
  while (!OrderedEntries.empty()) {
    // 1. Filter out only reordered nodes.
    // 2. If the entry has multiple uses - skip it and jump to the next node.
    DenseMap<TreeEntry *, SmallVector<std::pair<unsigned, TreeEntry *>>> Users;
    SmallVector<TreeEntry *> Filtered;
    for (TreeEntry *TE : OrderedEntries) {
      if (!(TE->State == TreeEntry::Vectorize ||
            TE->State == TreeEntry::StridedVectorize ||
            (TE->isGather() && GathersToOrders.contains(TE))) ||
          TE->UserTreeIndices.empty() || !TE->ReuseShuffleIndices.empty() ||
          !all_of(drop_begin(TE->UserTreeIndices),
                  [TE](const EdgeInfo &EI) {
                    return EI.UserTE == TE->UserTreeIndices.front().UserTE;
                  }) ||
          !Visited.insert(TE).second) {
        Filtered.push_back(TE);
        continue;
      }
      // Build a map between user nodes and their operands order to speedup
      // search. The graph currently does not provide this dependency directly.
      for (EdgeInfo &EI : TE->UserTreeIndices)
        Users[EI.UserTE].emplace_back(EI.EdgeIdx, TE);
    }
    // Erase filtered entries.
    for (TreeEntry *TE : Filtered)
      OrderedEntries.remove(TE);
    SmallVector<
        std::pair<TreeEntry *, SmallVector<std::pair<unsigned, TreeEntry *>>>>
        UsersVec(Users.begin(), Users.end());
    sort(UsersVec, [](const auto &Data1, const auto &Data2) {
      return Data1.first->Idx > Data2.first->Idx;
    });
    for (auto &Data : UsersVec) {
      // Check that operands are used only in the User node.
      SmallVector<TreeEntry *> GatherOps;
      if (!canReorderOperands(Data.first, Data.second, NonVectorized,
                              GatherOps)) {
        for (const std::pair<unsigned, TreeEntry *> &Op : Data.second)
          OrderedEntries.remove(Op.second);
        continue;
      }
      // All operands are reordered and used only in this node - propagate the
      // most used order to the user node.
      MapVector<OrdersType, unsigned,
                DenseMap<OrdersType, unsigned, OrdersTypeDenseMapInfo>>
          OrdersUses;
      // Do the analysis for each tree entry only once, otherwise the order of
      // the same node my be considered several times, though might be not
      // profitable.
      SmallPtrSet<const TreeEntry *, 4> VisitedOps;
      SmallPtrSet<const TreeEntry *, 4> VisitedUsers;
      for (const auto &Op : Data.second) {
        TreeEntry *OpTE = Op.second;
        if (!VisitedOps.insert(OpTE).second)
          continue;
        if (!OpTE->ReuseShuffleIndices.empty() && !GathersToOrders.count(OpTE))
          continue;
        const auto Order = [&]() -> const OrdersType {
          if (OpTE->isGather() || !OpTE->ReuseShuffleIndices.empty())
            return getReorderingData(*OpTE, /*TopToBottom=*/false)
                .value_or(OrdersType(1));
          return OpTE->ReorderIndices;
        }();
        // The order is partially ordered, skip it in favor of fully non-ordered
        // orders.
        if (Order.size() == 1)
          continue;
        unsigned NumOps = count_if(
            Data.second, [OpTE](const std::pair<unsigned, TreeEntry *> &P) {
              return P.second == OpTE;
            });
        // Stores actually store the mask, not the order, need to invert.
        if (OpTE->State == TreeEntry::Vectorize && !OpTE->isAltShuffle() &&
            OpTE->getOpcode() == Instruction::Store && !Order.empty()) {
          SmallVector<int> Mask;
          inversePermutation(Order, Mask);
          unsigned E = Order.size();
          OrdersType CurrentOrder(E, E);
          transform(Mask, CurrentOrder.begin(), [E](int Idx) {
            return Idx == PoisonMaskElem ? E : static_cast<unsigned>(Idx);
          });
          fixupOrderingIndices(CurrentOrder);
          OrdersUses.insert(std::make_pair(CurrentOrder, 0)).first->second +=
              NumOps;
        } else {
          OrdersUses.insert(std::make_pair(Order, 0)).first->second += NumOps;
        }
        auto Res = OrdersUses.insert(std::make_pair(OrdersType(), 0));
        const auto AllowsReordering = [&](const TreeEntry *TE) {
          if (!TE->ReorderIndices.empty() || !TE->ReuseShuffleIndices.empty() ||
              (TE->State == TreeEntry::Vectorize && TE->isAltShuffle()) ||
              (IgnoreReorder && TE->Idx == 0))
            return true;
          if (TE->isGather()) {
            if (GathersToOrders.contains(TE))
              return !getReorderingData(*TE, /*TopToBottom=*/false)
                          .value_or(OrdersType(1))
                          .empty();
            return true;
          }
          return false;
        };
        for (const EdgeInfo &EI : OpTE->UserTreeIndices) {
          TreeEntry *UserTE = EI.UserTE;
          if (!VisitedUsers.insert(UserTE).second)
            continue;
          // May reorder user node if it requires reordering, has reused
          // scalars, is an alternate op vectorize node or its op nodes require
          // reordering.
          if (AllowsReordering(UserTE))
            continue;
          // Check if users allow reordering.
          // Currently look up just 1 level of operands to avoid increase of
          // the compile time.
          // Profitable to reorder if definitely more operands allow
          // reordering rather than those with natural order.
          ArrayRef<std::pair<unsigned, TreeEntry *>> Ops = Users[UserTE];
          if (static_cast<unsigned>(count_if(
                  Ops, [UserTE, &AllowsReordering](
                           const std::pair<unsigned, TreeEntry *> &Op) {
                    return AllowsReordering(Op.second) &&
                           all_of(Op.second->UserTreeIndices,
                                  [UserTE](const EdgeInfo &EI) {
                                    return EI.UserTE == UserTE;
                                  });
                  })) <= Ops.size() / 2)
            ++Res.first->second;
        }
      }
      if (OrdersUses.empty()) {
        for (const std::pair<unsigned, TreeEntry *> &Op : Data.second)
          OrderedEntries.remove(Op.second);
        continue;
      }
      // Choose the most used order.
      unsigned IdentityCnt = 0;
      unsigned VF = Data.second.front().second->getVectorFactor();
      OrdersType IdentityOrder(VF, VF);
      for (auto &Pair : OrdersUses) {
        if (Pair.first.empty() || isIdentityOrder(Pair.first)) {
          IdentityCnt += Pair.second;
          combineOrders(IdentityOrder, Pair.first);
        }
      }
      MutableArrayRef<unsigned> BestOrder = IdentityOrder;
      unsigned Cnt = IdentityCnt;
      for (auto &Pair : OrdersUses) {
        // Prefer identity order. But, if filled identity found (non-empty
        // order) with same number of uses, as the new candidate order, we can
        // choose this candidate order.
        if (Cnt < Pair.second) {
          combineOrders(Pair.first, BestOrder);
          BestOrder = Pair.first;
          Cnt = Pair.second;
        } else {
          combineOrders(BestOrder, Pair.first);
        }
      }
      // Set order of the user node.
      if (isIdentityOrder(BestOrder)) {
        for (const std::pair<unsigned, TreeEntry *> &Op : Data.second)
          OrderedEntries.remove(Op.second);
        continue;
      }
      fixupOrderingIndices(BestOrder);
      // Erase operands from OrderedEntries list and adjust their orders.
      VisitedOps.clear();
      SmallVector<int> Mask;
      inversePermutation(BestOrder, Mask);
      SmallVector<int> MaskOrder(BestOrder.size(), PoisonMaskElem);
      unsigned E = BestOrder.size();
      transform(BestOrder, MaskOrder.begin(), [E](unsigned I) {
        return I < E ? static_cast<int>(I) : PoisonMaskElem;
      });
      for (const std::pair<unsigned, TreeEntry *> &Op : Data.second) {
        TreeEntry *TE = Op.second;
        OrderedEntries.remove(TE);
        if (!VisitedOps.insert(TE).second)
          continue;
        if (TE->ReuseShuffleIndices.size() == BestOrder.size()) {
          reorderNodeWithReuses(*TE, Mask);
          continue;
        }
        // Gathers are processed separately.
        if (TE->State != TreeEntry::Vectorize &&
            TE->State != TreeEntry::StridedVectorize &&
            (TE->State != TreeEntry::ScatterVectorize ||
             TE->ReorderIndices.empty()))
          continue;
        assert((BestOrder.size() == TE->ReorderIndices.size() ||
                TE->ReorderIndices.empty()) &&
               "Non-matching sizes of user/operand entries.");
        reorderOrder(TE->ReorderIndices, Mask);
        if (IgnoreReorder && TE == VectorizableTree.front().get())
          IgnoreReorder = false;
      }
      // For gathers just need to reorder its scalars.
      for (TreeEntry *Gather : GatherOps) {
        assert(Gather->ReorderIndices.empty() &&
               "Unexpected reordering of gathers.");
        if (!Gather->ReuseShuffleIndices.empty()) {
          // Just reorder reuses indices.
          reorderReuses(Gather->ReuseShuffleIndices, Mask);
          continue;
        }
        reorderScalars(Gather->Scalars, Mask);
        OrderedEntries.remove(Gather);
      }
      // Reorder operands of the user node and set the ordering for the user
      // node itself.
      if (Data.first->State != TreeEntry::Vectorize ||
          !isa<ExtractElementInst, ExtractValueInst, LoadInst>(
              Data.first->getMainOp()) ||
          Data.first->isAltShuffle())
        Data.first->reorderOperands(Mask);
      if (!isa<InsertElementInst, StoreInst>(Data.first->getMainOp()) ||
          Data.first->isAltShuffle() ||
          Data.first->State == TreeEntry::StridedVectorize) {
        reorderScalars(Data.first->Scalars, Mask);
        reorderOrder(Data.first->ReorderIndices, MaskOrder,
                     /*BottomOrder=*/true);
        if (Data.first->ReuseShuffleIndices.empty() &&
            !Data.first->ReorderIndices.empty() &&
            !Data.first->isAltShuffle()) {
          // Insert user node to the list to try to sink reordering deeper in
          // the graph.
          OrderedEntries.insert(Data.first);
        }
      } else {
        reorderOrder(Data.first->ReorderIndices, Mask);
      }
    }
  }
  // If the reordering is unnecessary, just remove the reorder.
  if (IgnoreReorder && !VectorizableTree.front()->ReorderIndices.empty() &&
      VectorizableTree.front()->ReuseShuffleIndices.empty())
    VectorizableTree.front()->ReorderIndices.clear();
}

Instruction *BoUpSLP::getRootEntryInstruction(const TreeEntry &Entry) const {
  if ((Entry.getOpcode() == Instruction::Store ||
       Entry.getOpcode() == Instruction::Load) &&
      Entry.State == TreeEntry::StridedVectorize &&
      !Entry.ReorderIndices.empty() && isReverseOrder(Entry.ReorderIndices))
    return dyn_cast<Instruction>(Entry.Scalars[Entry.ReorderIndices.front()]);
  return dyn_cast<Instruction>(Entry.Scalars.front());
}

void BoUpSLP::buildExternalUses(
    const ExtraValueToDebugLocsMap &ExternallyUsedValues) {
  DenseMap<Value *, unsigned> ScalarToExtUses;
  // Collect the values that we need to extract from the tree.
  for (auto &TEPtr : VectorizableTree) {
    TreeEntry *Entry = TEPtr.get();

    // No need to handle users of gathered values.
    if (Entry->isGather())
      continue;

    // For each lane:
    for (int Lane = 0, LE = Entry->Scalars.size(); Lane != LE; ++Lane) {
      Value *Scalar = Entry->Scalars[Lane];
      if (!isa<Instruction>(Scalar))
        continue;
      // All uses must be replaced already? No need to do it again.
      auto It = ScalarToExtUses.find(Scalar);
      if (It != ScalarToExtUses.end() && !ExternalUses[It->second].User)
        continue;

      // Check if the scalar is externally used as an extra arg.
      const auto *ExtI = ExternallyUsedValues.find(Scalar);
      if (ExtI != ExternallyUsedValues.end()) {
        int FoundLane = Entry->findLaneForValue(Scalar);
        LLVM_DEBUG(dbgs() << "SLP: Need to extract: Extra arg from lane "
                          << FoundLane << " from " << *Scalar << ".\n");
        ScalarToExtUses.try_emplace(Scalar, ExternalUses.size());
        ExternalUses.emplace_back(Scalar, nullptr, FoundLane);
        continue;
      }
      for (User *U : Scalar->users()) {
        LLVM_DEBUG(dbgs() << "SLP: Checking user:" << *U << ".\n");

        Instruction *UserInst = dyn_cast<Instruction>(U);
        if (!UserInst || isDeleted(UserInst))
          continue;

        // Ignore users in the user ignore list.
        if (UserIgnoreList && UserIgnoreList->contains(UserInst))
          continue;

        // Skip in-tree scalars that become vectors
        if (TreeEntry *UseEntry = getTreeEntry(U)) {
          // Some in-tree scalars will remain as scalar in vectorized
          // instructions. If that is the case, the one in FoundLane will
          // be used.
          if (UseEntry->State == TreeEntry::ScatterVectorize ||
              !doesInTreeUserNeedToExtract(
                  Scalar, getRootEntryInstruction(*UseEntry), TLI)) {
            LLVM_DEBUG(dbgs() << "SLP: \tInternal user will be removed:" << *U
                              << ".\n");
            assert(!UseEntry->isGather() && "Bad state");
            continue;
          }
          U = nullptr;
          if (It != ScalarToExtUses.end()) {
            ExternalUses[It->second].User = nullptr;
            break;
          }
        }

        if (U && Scalar->hasNUsesOrMore(UsesLimit))
          U = nullptr;
        int FoundLane = Entry->findLaneForValue(Scalar);
        LLVM_DEBUG(dbgs() << "SLP: Need to extract:" << *UserInst
                          << " from lane " << FoundLane << " from " << *Scalar
                          << ".\n");
        It = ScalarToExtUses.try_emplace(Scalar, ExternalUses.size()).first;
        ExternalUses.emplace_back(Scalar, U, FoundLane);
        if (!U)
          break;
      }
    }
  }
}

DenseMap<Value *, SmallVector<StoreInst *>>
BoUpSLP::collectUserStores(const BoUpSLP::TreeEntry *TE) const {
  DenseMap<Value *, SmallVector<StoreInst *>> PtrToStoresMap;
  for (unsigned Lane : seq<unsigned>(0, TE->Scalars.size())) {
    Value *V = TE->Scalars[Lane];
    // Don't iterate over the users of constant data.
    if (isa<ConstantData>(V))
      continue;
    // To save compilation time we don't visit if we have too many users.
    if (V->hasNUsesOrMore(UsesLimit))
      break;

    // Collect stores per pointer object.
    for (User *U : V->users()) {
      auto *SI = dyn_cast<StoreInst>(U);
      // Test whether we can handle the store. V might be a global, which could
      // be used in a different function.
      if (SI == nullptr || !SI->isSimple() || SI->getFunction() != F ||
          !isValidElementType(SI->getValueOperand()->getType()))
        continue;
      // Skip entry if already
      if (getTreeEntry(U))
        continue;

      Value *Ptr = getUnderlyingObject(SI->getPointerOperand());
      auto &StoresVec = PtrToStoresMap[Ptr];
      // For now just keep one store per pointer object per lane.
      // TODO: Extend this to support multiple stores per pointer per lane
      if (StoresVec.size() > Lane)
        continue;
      // Skip if in different BBs.
      if (!StoresVec.empty() &&
          SI->getParent() != StoresVec.back()->getParent())
        continue;
      // Make sure that the stores are of the same type.
      if (!StoresVec.empty() &&
          SI->getValueOperand()->getType() !=
              StoresVec.back()->getValueOperand()->getType())
        continue;
      StoresVec.push_back(SI);
    }
  }
  return PtrToStoresMap;
}

bool BoUpSLP::canFormVector(ArrayRef<StoreInst *> StoresVec,
                            OrdersType &ReorderIndices) const {
  // We check whether the stores in StoreVec can form a vector by sorting them
  // and checking whether they are consecutive.

  // To avoid calling getPointersDiff() while sorting we create a vector of
  // pairs {store, offset from first} and sort this instead.
  SmallVector<std::pair<StoreInst *, int>> StoreOffsetVec(StoresVec.size());
  StoreInst *S0 = StoresVec[0];
  StoreOffsetVec[0] = {S0, 0};
  Type *S0Ty = S0->getValueOperand()->getType();
  Value *S0Ptr = S0->getPointerOperand();
  for (unsigned Idx : seq<unsigned>(1, StoresVec.size())) {
    StoreInst *SI = StoresVec[Idx];
    std::optional<int> Diff =
        getPointersDiff(S0Ty, S0Ptr, SI->getValueOperand()->getType(),
                        SI->getPointerOperand(), *DL, *SE,
                        /*StrictCheck=*/true);
    // We failed to compare the pointers so just abandon this StoresVec.
    if (!Diff)
      return false;
    StoreOffsetVec[Idx] = {StoresVec[Idx], *Diff};
  }

  // Sort the vector based on the pointers. We create a copy because we may
  // need the original later for calculating the reorder (shuffle) indices.
  stable_sort(StoreOffsetVec, [](const std::pair<StoreInst *, int> &Pair1,
                                 const std::pair<StoreInst *, int> &Pair2) {
    int Offset1 = Pair1.second;
    int Offset2 = Pair2.second;
    return Offset1 < Offset2;
  });

  // Check if the stores are consecutive by checking if their difference is 1.
  for (unsigned Idx : seq<unsigned>(1, StoreOffsetVec.size()))
    if (StoreOffsetVec[Idx].second != StoreOffsetVec[Idx - 1].second + 1)
      return false;

  // Calculate the shuffle indices according to their offset against the sorted
  // StoreOffsetVec.
  ReorderIndices.reserve(StoresVec.size());
  for (StoreInst *SI : StoresVec) {
    unsigned Idx = find_if(StoreOffsetVec,
                           [SI](const std::pair<StoreInst *, int> &Pair) {
                             return Pair.first == SI;
                           }) -
                   StoreOffsetVec.begin();
    ReorderIndices.push_back(Idx);
  }
  // Identity order (e.g., {0,1,2,3}) is modeled as an empty OrdersType in
  // reorderTopToBottom() and reorderBottomToTop(), so we are following the
  // same convention here.
  if (isIdentityOrder(ReorderIndices))
    ReorderIndices.clear();

  return true;
}

#ifndef NDEBUG
LLVM_DUMP_METHOD static void dumpOrder(const BoUpSLP::OrdersType &Order) {
  for (unsigned Idx : Order)
    dbgs() << Idx << ", ";
  dbgs() << "\n";
}
#endif

SmallVector<BoUpSLP::OrdersType, 1>
BoUpSLP::findExternalStoreUsersReorderIndices(TreeEntry *TE) const {
  unsigned NumLanes = TE->Scalars.size();

  DenseMap<Value *, SmallVector<StoreInst *>> PtrToStoresMap =
      collectUserStores(TE);

  // Holds the reorder indices for each candidate store vector that is a user of
  // the current TreeEntry.
  SmallVector<OrdersType, 1> ExternalReorderIndices;

  // Now inspect the stores collected per pointer and look for vectorization
  // candidates. For each candidate calculate the reorder index vector and push
  // it into `ExternalReorderIndices`
  for (const auto &Pair : PtrToStoresMap) {
    auto &StoresVec = Pair.second;
    // If we have fewer than NumLanes stores, then we can't form a vector.
    if (StoresVec.size() != NumLanes)
      continue;

    // If the stores are not consecutive then abandon this StoresVec.
    OrdersType ReorderIndices;
    if (!canFormVector(StoresVec, ReorderIndices))
      continue;

    // We now know that the scalars in StoresVec can form a vector instruction,
    // so set the reorder indices.
    ExternalReorderIndices.push_back(ReorderIndices);
  }
  return ExternalReorderIndices;
}

void BoUpSLP::buildTree(ArrayRef<Value *> Roots,
                        const SmallDenseSet<Value *> &UserIgnoreLst) {
  deleteTree();
  UserIgnoreList = &UserIgnoreLst;
  if (!allSameType(Roots))
    return;
  buildTree_rec(Roots, 0, EdgeInfo());
}

void BoUpSLP::buildTree(ArrayRef<Value *> Roots) {
  deleteTree();
  if (!allSameType(Roots))
    return;
  buildTree_rec(Roots, 0, EdgeInfo());
}

/// Tries to find subvector of loads and builds new vector of only loads if can
/// be profitable.
static void gatherPossiblyVectorizableLoads(
    const BoUpSLP &R, ArrayRef<Value *> VL, const DataLayout &DL,
    ScalarEvolution &SE, const TargetTransformInfo &TTI,
    SmallVectorImpl<SmallVector<std::pair<LoadInst *, int>>> &GatheredLoads,
    bool AddNew = true) {
  if (VL.empty())
    return;
  Type *ScalarTy = getValueType(VL.front());
  if (!isValidElementType(ScalarTy))
    return;
  const int NumScalars = VL.size();
  int NumParts = 1;
  if (NumScalars > 1) {
    auto *VecTy = getWidenedType(ScalarTy, NumScalars);
    NumParts = TTI.getNumberOfParts(VecTy);
    if (NumParts == 0 || NumParts >= NumScalars)
      NumParts = 1;
  }
  unsigned VF = PowerOf2Ceil(NumScalars / NumParts);
  SmallVector<SmallVector<std::pair<LoadInst *, int>>> ClusteredLoads;
  for (int I : seq<int>(NumParts)) {
    for (Value *V :
         VL.slice(I * VF, std::min<unsigned>(VF, VL.size() - I * VF))) {
      auto *LI = dyn_cast<LoadInst>(V);
      if (!LI)
        continue;
      if (R.isDeleted(LI) || R.isVectorized(LI) || !LI->isSimple())
        continue;
      bool IsFound = false;
      for (auto &Data : ClusteredLoads) {
        if (LI->getParent() != Data.front().first->getParent())
          continue;
        std::optional<int> Dist =
            getPointersDiff(LI->getType(), LI->getPointerOperand(),
                            Data.front().first->getType(),
                            Data.front().first->getPointerOperand(), DL, SE,
                            /*StrictCheck=*/true);
        if (Dist && all_of(Data, [&](const std::pair<LoadInst *, int> &Pair) {
              IsFound |= Pair.first == LI;
              return IsFound || Pair.second != *Dist;
            })) {
          if (!IsFound)
            Data.emplace_back(LI, *Dist);
          IsFound = true;
          break;
        }
      }
      if (!IsFound)
        ClusteredLoads.emplace_back().emplace_back(LI, 0);
    }
  }
  auto FindMatchingLoads =
      [&](ArrayRef<std::pair<LoadInst *, int>> Loads,
          SmallVectorImpl<SmallVector<std::pair<LoadInst *, int>>>
              &GatheredLoads,
          SetVector<unsigned> &ToAdd, SetVector<unsigned> &Repeated,
          int &Offset, unsigned &Start) {
        if (Loads.empty())
          return GatheredLoads.end();
        SmallVector<std::pair<int, int>> Res;
        LoadInst *LI = Loads.front().first;
        for (auto [Idx, Data] : enumerate(GatheredLoads)) {
          if (Idx < Start)
            continue;
          ToAdd.clear();
          if (LI->getParent() != Data.front().first->getParent())
            continue;
          std::optional<int> Dist =
              getPointersDiff(LI->getType(), LI->getPointerOperand(),
                              Data.front().first->getType(),
                              Data.front().first->getPointerOperand(), DL, SE,
                              /*StrictCheck=*/true);
          if (Dist) {
            // Found matching gathered loads - check if all loads are unique or
            // can be effectively vectorized.
            unsigned NumUniques = 0;
            for (auto [Cnt, Pair] : enumerate(Loads)) {
              bool Used = any_of(
                  Data, [&, &P = Pair](const std::pair<LoadInst *, int> &PD) {
                    return PD.first == P.first;
                  });
              if (!Used &&
                  none_of(Data,
                          [&, &P = Pair](const std::pair<LoadInst *, int> &PD) {
                            return *Dist + P.second == PD.second;
                          })) {
                ++NumUniques;
                ToAdd.insert(Cnt);
              } else if (Used) {
                Repeated.insert(Cnt);
              }
            }
            if (NumUniques > 0 &&
                (Loads.size() == NumUniques ||
                 (Loads.size() - NumUniques >= 2 &&
                  Loads.size() - NumUniques >= Loads.size() / 2 &&
                  (has_single_bit(Data.size() + NumUniques) ||
                   bit_ceil(Data.size()) <
                       bit_ceil(Data.size() + NumUniques))))) {
              Offset = *Dist;
              Start = Idx + 1;
              return std::next(GatheredLoads.begin(), Idx);
            }
          }
        }
        ToAdd.clear();
        return GatheredLoads.end();
      };
  for (ArrayRef<std::pair<LoadInst *, int>> Data : ClusteredLoads) {
    unsigned Start = 0;
    SetVector<unsigned> ToAdd, LocalToAdd, Repeated;
    int Offset = 0;
    auto *It = FindMatchingLoads(Data, GatheredLoads, LocalToAdd, Repeated,
                                 Offset, Start);
    while (It != GatheredLoads.end()) {
      assert(!LocalToAdd.empty() && "Expected some elements to add.");
      for (unsigned Idx : LocalToAdd)
        It->emplace_back(Data[Idx].first, Data[Idx].second + Offset);
      ToAdd.insert(LocalToAdd.begin(), LocalToAdd.end());
      It = FindMatchingLoads(Data, GatheredLoads, LocalToAdd, Repeated, Offset,
                             Start);
    }
    if (any_of(seq<unsigned>(Data.size()), [&](unsigned Idx) {
          return !ToAdd.contains(Idx) && !Repeated.contains(Idx);
        })) {
      auto AddNewLoads =
          [&](SmallVectorImpl<std::pair<LoadInst *, int>> &Loads) {
            for (unsigned Idx : seq<unsigned>(Data.size())) {
              if (ToAdd.contains(Idx) || Repeated.contains(Idx))
                continue;
              Loads.push_back(Data[Idx]);
            }
          };
      if (!AddNew) {
        LoadInst *LI = Data.front().first;
        It = find_if(
            GatheredLoads, [&](ArrayRef<std::pair<LoadInst *, int>> PD) {
              return PD.front().first->getParent() == LI->getParent() &&
                     PD.front().first->getType() == LI->getType();
            });
        while (It != GatheredLoads.end()) {
          AddNewLoads(*It);
          It = std::find_if(
              std::next(It), GatheredLoads.end(),
              [&](ArrayRef<std::pair<LoadInst *, int>> PD) {
                return PD.front().first->getParent() == LI->getParent() &&
                       PD.front().first->getType() == LI->getType();
              });
        }
      }
      GatheredLoads.emplace_back().append(Data.begin(), Data.end());
      AddNewLoads(GatheredLoads.emplace_back());
    }
  }
}

void BoUpSLP::tryToVectorizeGatheredLoads(
    ArrayRef<SmallVector<std::pair<LoadInst *, int>>> GatheredLoads) {
  GatheredLoadsEntriesFirst = VectorizableTree.size();

  // Sort loads by distance.
  auto LoadSorter = [](const std::pair<LoadInst *, int> &L1,
                       const std::pair<LoadInst *, int> &L2) {
    return L1.second > L2.second;
  };

  auto IsMaskedGatherSupported = [&](ArrayRef<LoadInst *> Loads) {
    ArrayRef<Value *> Values(reinterpret_cast<Value *const *>(Loads.begin()),
                             Loads.size());
    Align Alignment = computeCommonAlignment<LoadInst>(Values);
    auto *Ty = getWidenedType(Loads.front()->getType(), Loads.size());
    return TTI->isLegalMaskedGather(Ty, Alignment) &&
           !TTI->forceScalarizeMaskedGather(Ty, Alignment);
  };

  auto GetVectorizedRanges = [this](ArrayRef<LoadInst *> Loads,
                                    BoUpSLP::ValueSet &VectorizedLoads,
                                    SmallVectorImpl<LoadInst *> &NonVectorized,
                                    bool Final, unsigned MaxVF) {
    SmallVector<std::pair<ArrayRef<Value *>, LoadsState>> Results;
    unsigned StartIdx = 0;
    SmallVector<int> CandidateVFs;
    if (VectorizeNonPowerOf2 && has_single_bit(MaxVF + 1))
      CandidateVFs.push_back(MaxVF);
    for (int NumElts = bit_floor(MaxVF); NumElts > 1; NumElts /= 2) {
      CandidateVFs.push_back(NumElts);
      if (VectorizeNonPowerOf2 && NumElts > 2)
        CandidateVFs.push_back(NumElts - 1);
    }

    if (Final && CandidateVFs.empty())
      return Results;

    unsigned BestVF = Final ? CandidateVFs.back() : 0;
    for (unsigned NumElts : CandidateVFs) {
      if (Final && NumElts > BestVF)
        continue;
      SmallVector<unsigned> MaskedGatherVectorized;
      for (unsigned Cnt = StartIdx, E = Loads.size(); Cnt + NumElts <= E;
           ++Cnt) {
        ArrayRef<LoadInst *> Slice = ArrayRef(Loads).slice(Cnt, NumElts);
        if (VectorizedLoads.count(Slice.front()) ||
            VectorizedLoads.count(Slice.back()) ||
            areKnownNonVectorizableLoads(Slice))
          continue;
        // Check if it is profitable to try vectorizing gathered loads. It is
        // profitable if we have more than 3 consecutive loads or if we have
        // less but all users are vectorized or deleted.
        bool AllowToVectorize =
            NumElts >= 3 ||
            any_of(ValueToGatherNodes.at(Slice.front()),
                   [=](const TreeEntry *TE) {
                     return TE->Scalars.size() == 2 &&
                            ((TE->Scalars.front() == Slice.front() &&
                              TE->Scalars.back() == Slice.back()) ||
                             (TE->Scalars.front() == Slice.back() &&
                              TE->Scalars.back() == Slice.front()));
                   });
        // Check if it is profitable to vectorize 2-elements loads.
        if (NumElts == 2) {
          bool IsLegalBroadcastLoad = TTI->isLegalBroadcastLoad(
              Slice.front()->getType(), ElementCount::getFixed(NumElts));
          auto CheckIfAllowed = [=](ArrayRef<LoadInst *> Slice) {
            for (LoadInst *LI : Slice) {
              // If single use/user - allow to vectorize.
              if (LI->hasOneUse())
                continue;
              // 1. Check if number of uses equals number of users.
              // 2. All users are deleted.
              // 3. The load broadcasts are not allowed or the load is not
              // broadcasted.
              if (std::distance(LI->user_begin(), LI->user_end()) !=
                      LI->getNumUses())
                return false;
              if (!IsLegalBroadcastLoad)
                continue;
              if (LI->hasNUsesOrMore(UsesLimit))
                return false;
              for (User *U : LI->users()) {
                if (auto *UI = dyn_cast<Instruction>(U); UI && isDeleted(UI))
                  continue;
                if (const TreeEntry *UTE = getTreeEntry(U)) {
                  for (int I : seq<int>(UTE->getNumOperands())) {
                    if (all_of(UTE->getOperand(I),
                               [LI](Value *V) { return V == LI; }))
                      // Found legal broadcast - do not vectorize.
                      return false;
                  }
                }
              }
            }
            return true;
          };
          AllowToVectorize = CheckIfAllowed(Slice);
        }
        if (AllowToVectorize) {
          SmallVector<Value *> PointerOps;
          OrdersType CurrentOrder;
          // Try to build vector load.
          ArrayRef<Value *> Values(
              reinterpret_cast<Value *const *>(Slice.begin()), Slice.size());
          LoadsState LS = canVectorizeLoads(Values, Slice.front(), CurrentOrder,
                                            PointerOps, &BestVF);
          if (LS != LoadsState::Gather ||
              (BestVF > 1 && static_cast<unsigned>(NumElts) == 2 * BestVF)) {
            if (LS == LoadsState::ScatterVectorize) {
              if (MaskedGatherVectorized.empty() ||
                  Cnt >= MaskedGatherVectorized.back() + NumElts)
                MaskedGatherVectorized.push_back(Cnt);
              continue;
            }
            if (LS != LoadsState::Gather) {
              Results.emplace_back(Values, LS);
              VectorizedLoads.insert(Slice.begin(), Slice.end());
              // If we vectorized initial block, no need to try to vectorize it
              // again.
              if (Cnt == StartIdx)
                StartIdx += NumElts;
            }
            // Check if the whole array was vectorized already - exit.
            if (StartIdx >= Loads.size())
              break;
            // Erase last masked gather candidate, if another candidate within
            // the range is found to be better.
            if (!MaskedGatherVectorized.empty() &&
                Cnt < MaskedGatherVectorized.back() + NumElts)
              MaskedGatherVectorized.pop_back();
            Cnt += NumElts - 1;
            continue;
          }
        }
        if (!AllowToVectorize || BestVF == 0)
          registerNonVectorizableLoads(Slice);
      }
      // Mark masked gathers candidates as vectorized, if any.
      for (unsigned Cnt : MaskedGatherVectorized) {
        ArrayRef<LoadInst *> Slice = ArrayRef(Loads).slice(Cnt, NumElts);
        ArrayRef<Value *> Values(
            reinterpret_cast<Value *const *>(Slice.begin()), Slice.size());
        Results.emplace_back(Values, LoadsState::ScatterVectorize);
        VectorizedLoads.insert(Slice.begin(), Slice.end());
        // If we vectorized initial block, no need to try to vectorize it again.
        if (Cnt == StartIdx)
          StartIdx += NumElts;
      }
    }
    for (LoadInst *LI : Loads) {
      if (!VectorizedLoads.contains(LI))
        NonVectorized.push_back(LI);
    }
    return Results;
  };
  auto ProcessGatheredLoads =
      [&](ArrayRef<SmallVector<std::pair<LoadInst *, int>>> GatheredLoads,
          bool Final = false) {
        SmallVector<LoadInst *> NonVectorized;
        for (ArrayRef<std::pair<LoadInst *, int>> LoadsDists : GatheredLoads) {
          if (LoadsDists.size() <= 1) {
            NonVectorized.push_back(LoadsDists.back().first);
            continue;
          }
          SmallVector<std::pair<LoadInst *, int>> LocalLoadsDists(LoadsDists);
          SmallVector<LoadInst *> OriginalLoads(LocalLoadsDists.size());
          transform(
              LoadsDists, OriginalLoads.begin(),
              [](const std::pair<LoadInst *, int> &L) { return L.first; });
          stable_sort(LocalLoadsDists, LoadSorter);
          SmallVector<LoadInst *> Loads;
          unsigned MaxConsecutiveDistance = 0;
          unsigned CurrentConsecutiveDist = 1;
          int LastDist = LocalLoadsDists.front().second;
          bool AllowMaskedGather = IsMaskedGatherSupported(OriginalLoads);
          for (const std::pair<LoadInst *, int> &L : LocalLoadsDists) {
            if (getTreeEntry(L.first))
              continue;
            assert(LastDist >= L.second &&
                   "Expected first distance always not less than second");
            if (static_cast<unsigned>(LastDist - L.second) ==
                CurrentConsecutiveDist) {
              ++CurrentConsecutiveDist;
              MaxConsecutiveDistance =
                  std::max(MaxConsecutiveDistance, CurrentConsecutiveDist);
              Loads.push_back(L.first);
              continue;
            }
            if (!AllowMaskedGather && CurrentConsecutiveDist == 1 &&
                !Loads.empty())
              Loads.pop_back();
            CurrentConsecutiveDist = 1;
            LastDist = L.second;
            Loads.push_back(L.first);
          }
          if (Loads.size() <= 1)
            continue;
          if (AllowMaskedGather)
            MaxConsecutiveDistance = Loads.size();
          else if (MaxConsecutiveDistance < 2)
            continue;
          BoUpSLP::ValueSet VectorizedLoads;
          SmallVector<LoadInst *> SortedNonVectorized;
          SmallVector<std::pair<ArrayRef<Value *>, LoadsState>> Results =
              GetVectorizedRanges(Loads, VectorizedLoads, SortedNonVectorized,
                                  Final, MaxConsecutiveDistance);
          if (!Results.empty() && !SortedNonVectorized.empty() &&
              OriginalLoads.size() == Loads.size() &&
              MaxConsecutiveDistance == Loads.size() &&
              all_of(Results,
                     [](const std::pair<ArrayRef<Value *>, LoadsState> &P) {
                       return P.second == LoadsState::ScatterVectorize;
                     })) {
            VectorizedLoads.clear();
            SmallVector<LoadInst *> UnsortedNonVectorized;
            SmallVector<std::pair<ArrayRef<Value *>, LoadsState>>
                UnsortedResults =
                    GetVectorizedRanges(OriginalLoads, VectorizedLoads,
                                        UnsortedNonVectorized, Final,
                                        OriginalLoads.size());
            if (SortedNonVectorized.size() >= UnsortedNonVectorized.size()) {
              SortedNonVectorized.swap(UnsortedNonVectorized);
              Results.swap(UnsortedResults);
            }
          }
          for (auto [Slice, _] : Results) {
            LLVM_DEBUG(dbgs() << "SLP: Trying to vectorize gathered loads ("
                              << Slice.size() << ")\n");
            if (any_of(Slice, [&](Value *V) { return getTreeEntry(V); })) {
              for (Value *L : Slice)
                if (!getTreeEntry(L))
                  SortedNonVectorized.push_back(cast<LoadInst>(L));
              continue;
            }

            // Select maximum VF as a maximum of user gathered nodes and
            // distance between scalar loads in these nodes.
            unsigned MaxVF = Slice.size();
            unsigned UserMaxVF = 0;
            if (MaxVF == 2) {
              UserMaxVF = MaxVF;
            } else {
              std::optional<unsigned> CommonVF = 0;
              DenseMap<const TreeEntry *, unsigned> EntryToPosition;
              for (auto [Idx, V] : enumerate(Slice)) {
                for (const TreeEntry *E : ValueToGatherNodes.at(V)) {
                  UserMaxVF = std::max<unsigned>(UserMaxVF, E->Scalars.size());
                  unsigned Pos =
                      EntryToPosition.try_emplace(E, Idx).first->second;
                  UserMaxVF = std::max<unsigned>(UserMaxVF, Idx - Pos + 1);
                  if (CommonVF) {
                    if (*CommonVF == 0) {
                      CommonVF = E->Scalars.size();
                      continue;
                    }
                    if (*CommonVF != E->Scalars.size())
                      CommonVF.reset();
                  }
                }
              }
              // Try to build long masked gather loads.
              UserMaxVF = bit_ceil(UserMaxVF);
            }
            for (unsigned VF = MaxVF; VF >= 2; VF /= 2) {
              bool IsVectorized = true;
              for (unsigned I = 0, E = Slice.size(); I < E; I += VF) {
                ArrayRef<Value *> SubSlice =
                    Slice.slice(I, std::min(VF, E - I));
                if (getTreeEntry(SubSlice.front()))
                  continue;
                unsigned Sz = VectorizableTree.size();
                buildTree_rec(SubSlice, 0, EdgeInfo());
                if (Sz == VectorizableTree.size()) {
                  IsVectorized = false;
                  continue;
                }
              }
              if (IsVectorized)
                break;
            }
          }
          NonVectorized.append(SortedNonVectorized);
        }
        return NonVectorized;
      };
  SmallVector<LoadInst *> NonVectorized = ProcessGatheredLoads(GatheredLoads);
  if (!GatheredLoads.empty() && !NonVectorized.empty() &&
      std::accumulate(
          GatheredLoads.begin(), GatheredLoads.end(), 0u,
          [](unsigned S, ArrayRef<std::pair<LoadInst *, int>> LoadsDists) {
            return S + LoadsDists.size();
          }) != NonVectorized.size() &&
      IsMaskedGatherSupported(NonVectorized)) {
    SmallVector<SmallVector<std::pair<LoadInst *, int>>> FinalGatheredLoads;
    for (LoadInst *LI : NonVectorized) {
      // Reinsert non-vectorized loads to other list of loads with the same
      // base pointers.
      gatherPossiblyVectorizableLoads(*this, LI, *DL, *SE, *TTI,
                                      FinalGatheredLoads,
                                      /*AddNew=*/false);
    }
    // Final attempt to vectorize non-vectorized loads.
    (void)ProcessGatheredLoads(FinalGatheredLoads, /*Final=*/true);
  }
  // If no new entries created, consider it as no gathered loads entries must be
  // handled.
  if (static_cast<unsigned>(GatheredLoadsEntriesFirst) ==
      VectorizableTree.size())
    GatheredLoadsEntriesFirst = NoGatheredLoads;
}

/// \return true if the specified list of values has only one instruction that
/// requires scheduling, false otherwise.
#ifndef NDEBUG
static bool needToScheduleSingleInstruction(ArrayRef<Value *> VL) {
  Value *NeedsScheduling = nullptr;
  for (Value *V : VL) {
    if (doesNotNeedToBeScheduled(V))
      continue;
    if (!NeedsScheduling) {
      NeedsScheduling = V;
      continue;
    }
    return false;
  }
  return NeedsScheduling;
}
#endif

/// Generates key/subkey pair for the given value to provide effective sorting
/// of the values and better detection of the vectorizable values sequences. The
/// keys/subkeys can be used for better sorting of the values themselves (keys)
/// and in values subgroups (subkeys).
static std::pair<size_t, size_t> generateKeySubkey(
    Value *V, const TargetLibraryInfo *TLI,
    function_ref<hash_code(size_t, LoadInst *)> LoadsSubkeyGenerator,
    bool AllowAlternate) {
  hash_code Key = hash_value(V->getValueID() + 2);
  hash_code SubKey = hash_value(0);
  // Sort the loads by the distance between the pointers.
  if (auto *LI = dyn_cast<LoadInst>(V)) {
    Key = hash_combine(LI->getType(), hash_value(Instruction::Load), Key);
    if (LI->isSimple())
      SubKey = hash_value(LoadsSubkeyGenerator(Key, LI));
    else
      Key = SubKey = hash_value(LI);
  } else if (isVectorLikeInstWithConstOps(V)) {
    // Sort extracts by the vector operands.
    if (isa<ExtractElementInst, UndefValue>(V))
      Key = hash_value(Value::UndefValueVal + 1);
    if (auto *EI = dyn_cast<ExtractElementInst>(V)) {
      if (!isUndefVector(EI->getVectorOperand()).all() &&
          !isa<UndefValue>(EI->getIndexOperand()))
        SubKey = hash_value(EI->getVectorOperand());
    }
  } else if (auto *I = dyn_cast<Instruction>(V)) {
    // Sort other instructions just by the opcodes except for CMPInst.
    // For CMP also sort by the predicate kind.
    if ((isa<BinaryOperator, CastInst>(I)) &&
        isValidForAlternation(I->getOpcode())) {
      if (AllowAlternate)
        Key = hash_value(isa<BinaryOperator>(I) ? 1 : 0);
      else
        Key = hash_combine(hash_value(I->getOpcode()), Key);
      SubKey = hash_combine(
          hash_value(I->getOpcode()), hash_value(I->getType()),
          hash_value(isa<BinaryOperator>(I)
                         ? I->getType()
                         : cast<CastInst>(I)->getOperand(0)->getType()));
      // For casts, look through the only operand to improve compile time.
      if (isa<CastInst>(I)) {
        std::pair<size_t, size_t> OpVals =
            generateKeySubkey(I->getOperand(0), TLI, LoadsSubkeyGenerator,
                              /*AllowAlternate=*/true);
        Key = hash_combine(OpVals.first, Key);
        SubKey = hash_combine(OpVals.first, SubKey);
      }
    } else if (auto *CI = dyn_cast<CmpInst>(I)) {
      CmpInst::Predicate Pred = CI->getPredicate();
      if (CI->isCommutative())
        Pred = std::min(Pred, CmpInst::getInversePredicate(Pred));
      CmpInst::Predicate SwapPred = CmpInst::getSwappedPredicate(Pred);
      SubKey = hash_combine(hash_value(I->getOpcode()), hash_value(Pred),
                            hash_value(SwapPred),
                            hash_value(CI->getOperand(0)->getType()));
    } else if (auto *Call = dyn_cast<CallInst>(I)) {
      Intrinsic::ID ID = getVectorIntrinsicIDForCall(Call, TLI);
      if (isTriviallyVectorizable(ID)) {
        SubKey = hash_combine(hash_value(I->getOpcode()), hash_value(ID));
      } else if (!VFDatabase(*Call).getMappings(*Call).empty()) {
        SubKey = hash_combine(hash_value(I->getOpcode()),
                              hash_value(Call->getCalledFunction()));
      } else {
        Key = hash_combine(hash_value(Call), Key);
        SubKey = hash_combine(hash_value(I->getOpcode()), hash_value(Call));
      }
      for (const CallBase::BundleOpInfo &Op : Call->bundle_op_infos())
        SubKey = hash_combine(hash_value(Op.Begin), hash_value(Op.End),
                              hash_value(Op.Tag), SubKey);
    } else if (auto *Gep = dyn_cast<GetElementPtrInst>(I)) {
      if (Gep->getNumOperands() == 2 && isa<ConstantInt>(Gep->getOperand(1)))
        SubKey = hash_value(Gep->getPointerOperand());
      else
        SubKey = hash_value(Gep);
    } else if (BinaryOperator::isIntDivRem(I->getOpcode()) &&
               !isa<ConstantInt>(I->getOperand(1))) {
      // Do not try to vectorize instructions with potentially high cost.
      SubKey = hash_value(I);
    } else {
      SubKey = hash_value(I->getOpcode());
    }
    Key = hash_combine(hash_value(I->getParent()), Key);
  }
  return std::make_pair(Key, SubKey);
}

/// Checks if the specified instruction \p I is an alternate operation for
/// the given \p MainOp and \p AltOp instructions.
static bool isAlternateInstruction(const Instruction *I,
                                   const Instruction *MainOp,
                                   const Instruction *AltOp,
                                   const TargetLibraryInfo &TLI);

bool BoUpSLP::areAltOperandsProfitable(const InstructionsState &S,
                                       ArrayRef<Value *> VL) const {
  unsigned Opcode0 = S.getOpcode();
  unsigned Opcode1 = S.getAltOpcode();
  SmallBitVector OpcodeMask(getAltInstrMask(VL, Opcode0, Opcode1));
  // If this pattern is supported by the target then consider it profitable.
  if (TTI->isLegalAltInstr(getWidenedType(S.MainOp->getType(), VL.size()),
                           Opcode0, Opcode1, OpcodeMask))
    return true;
  SmallVector<ValueList> Operands;
  for (unsigned I : seq<unsigned>(0, S.MainOp->getNumOperands())) {
    Operands.emplace_back();
    // Prepare the operand vector.
    for (Value *V : VL)
      Operands.back().push_back(cast<Instruction>(V)->getOperand(I));
  }
  if (Operands.size() == 2) {
    // Try find best operands candidates.
    for (unsigned I : seq<unsigned>(0, VL.size() - 1)) {
      SmallVector<std::pair<Value *, Value *>> Candidates(3);
      Candidates[0] = std::make_pair(Operands[0][I], Operands[0][I + 1]);
      Candidates[1] = std::make_pair(Operands[0][I], Operands[1][I + 1]);
      Candidates[2] = std::make_pair(Operands[1][I], Operands[0][I + 1]);
      std::optional<int> Res = findBestRootPair(Candidates);
      switch (Res.value_or(0)) {
      case 0:
        break;
      case 1:
        std::swap(Operands[0][I + 1], Operands[1][I + 1]);
        break;
      case 2:
        std::swap(Operands[0][I], Operands[1][I]);
        break;
      default:
        llvm_unreachable("Unexpected index.");
      }
    }
  }
  DenseSet<unsigned> UniqueOpcodes;
  constexpr unsigned NumAltInsts = 3; // main + alt + shuffle.
  unsigned NonInstCnt = 0;
  // Estimate number of instructions, required for the vectorized node and for
  // the buildvector node.
  unsigned UndefCnt = 0;
  // Count the number of extra shuffles, required for vector nodes.
  unsigned ExtraShuffleInsts = 0;
  // Check that operands do not contain same values and create either perfect
  // diamond match or shuffled match.
  if (Operands.size() == 2) {
    // Do not count same operands twice.
    if (Operands.front() == Operands.back()) {
      Operands.erase(Operands.begin());
    } else if (!allConstant(Operands.front()) &&
               all_of(Operands.front(), [&](Value *V) {
                 return is_contained(Operands.back(), V);
               })) {
      Operands.erase(Operands.begin());
      ++ExtraShuffleInsts;
    }
  }
  const Loop *L = LI->getLoopFor(S.MainOp->getParent());
  // Vectorize node, if:
  // 1. at least single operand is constant or splat.
  // 2. Operands have many loop invariants (the instructions are not loop
  // invariants).
  // 3. At least single unique operands is supposed to vectorized.
  return none_of(Operands,
                 [&](ArrayRef<Value *> Op) {
                   if (allConstant(Op) ||
                       (!isSplat(Op) && allSameBlock(Op) && allSameType(Op) &&
                        getSameOpcode(Op, *TLI).MainOp))
                     return false;
                   DenseMap<Value *, unsigned> Uniques;
                   for (Value *V : Op) {
                     if (isa<Constant, ExtractElementInst>(V) ||
                         getTreeEntry(V) || (L && L->isLoopInvariant(V))) {
                       if (isa<UndefValue>(V))
                         ++UndefCnt;
                       continue;
                     }
                     auto Res = Uniques.try_emplace(V, 0);
                     // Found first duplicate - need to add shuffle.
                     if (!Res.second && Res.first->second == 1)
                       ++ExtraShuffleInsts;
                     ++Res.first->getSecond();
                     if (auto *I = dyn_cast<Instruction>(V))
                       UniqueOpcodes.insert(I->getOpcode());
                     else if (Res.second)
                       ++NonInstCnt;
                   }
                   return none_of(Uniques, [&](const auto &P) {
                     return P.first->hasNUsesOrMore(P.second + 1) &&
                            none_of(P.first->users(), [&](User *U) {
                              return getTreeEntry(U) || Uniques.contains(U);
                            });
                   });
                 }) ||
         // Do not vectorize node, if estimated number of vector instructions is
         // more than estimated number of buildvector instructions. Number of
         // vector operands is number of vector instructions + number of vector
         // instructions for operands (buildvectors). Number of buildvector
         // instructions is just number_of_operands * number_of_scalars.
         (UndefCnt < (VL.size() - 1) * S.MainOp->getNumOperands() &&
          (UniqueOpcodes.size() + NonInstCnt + ExtraShuffleInsts +
           NumAltInsts) < S.MainOp->getNumOperands() * VL.size());
}

BoUpSLP::TreeEntry::EntryState BoUpSLP::getScalarsVectorizationState(
    InstructionsState &S, ArrayRef<Value *> VL, bool IsScatterVectorizeUserTE,
    OrdersType &CurrentOrder, SmallVectorImpl<Value *> &PointerOps) {
  assert(S.MainOp && "Expected instructions with same/alternate opcodes only.");

  if (S.MainOp->getType()->isFloatingPointTy() &&
      TTI->isFPVectorizationPotentiallyUnsafe() && any_of(VL, [](Value *V) {
        auto *I = dyn_cast<Instruction>(V);
        return I && (I->isBinaryOp() || isa<CallInst>(I)) && !I->isFast();
      }))
    return TreeEntry::NeedToGather;

  unsigned ShuffleOrOp =
      S.isAltShuffle() ? (unsigned)Instruction::ShuffleVector : S.getOpcode();
  auto *VL0 = cast<Instruction>(S.OpValue);
  switch (ShuffleOrOp) {
  case Instruction::PHI: {
    // Too many operands - gather, most probably won't be vectorized.
    if (VL0->getNumOperands() > MaxPHINumOperands)
      return TreeEntry::NeedToGather;
    // Check for terminator values (e.g. invoke).
    for (Value *V : VL)
      for (Value *Incoming : cast<PHINode>(V)->incoming_values()) {
        Instruction *Term = dyn_cast<Instruction>(Incoming);
        if (Term && Term->isTerminator()) {
          LLVM_DEBUG(dbgs()
                     << "SLP: Need to swizzle PHINodes (terminator use).\n");
          return TreeEntry::NeedToGather;
        }
      }

    return TreeEntry::Vectorize;
  }
  case Instruction::ExtractValue:
  case Instruction::ExtractElement: {
    bool Reuse = canReuseExtract(VL, VL0, CurrentOrder);
    // FIXME: Vectorizing is not supported yet for non-power-of-2 ops.
    if (!has_single_bit(VL.size()))
      return TreeEntry::NeedToGather;
    if (Reuse || !CurrentOrder.empty())
      return TreeEntry::Vectorize;
    LLVM_DEBUG(dbgs() << "SLP: Gather extract sequence.\n");
    return TreeEntry::NeedToGather;
  }
  case Instruction::InsertElement: {
    // Check that we have a buildvector and not a shuffle of 2 or more
    // different vectors.
    ValueSet SourceVectors;
    for (Value *V : VL) {
      SourceVectors.insert(cast<Instruction>(V)->getOperand(0));
      assert(getElementIndex(V) != std::nullopt &&
             "Non-constant or undef index?");
    }

    if (count_if(VL, [&SourceVectors](Value *V) {
          return !SourceVectors.contains(V);
        }) >= 2) {
      // Found 2nd source vector - cancel.
      LLVM_DEBUG(dbgs() << "SLP: Gather of insertelement vectors with "
                           "different source vectors.\n");
      return TreeEntry::NeedToGather;
    }

    if (any_of(VL, [&SourceVectors](Value *V) {
          // The last InsertElement can have multiple uses.
          return SourceVectors.contains(V) && !V->hasOneUse();
        })) {
      assert(SLPReVec && "Only supported by REVEC.");
      LLVM_DEBUG(dbgs() << "SLP: Gather of insertelement vectors with "
                           "multiple uses.\n");
      return TreeEntry::NeedToGather;
    }

    return TreeEntry::Vectorize;
  }
  case Instruction::Load: {
    // Check that a vectorized load would load the same memory as a scalar
    // load. For example, we don't want to vectorize loads that are smaller
    // than 8-bit. Even though we have a packed struct {<i2, i2, i2, i2>} LLVM
    // treats loading/storing it as an i8 struct. If we vectorize loads/stores
    // from such a struct, we read/write packed bits disagreeing with the
    // unvectorized version.
    switch (canVectorizeLoads(VL, VL0, CurrentOrder, PointerOps)) {
    case LoadsState::Vectorize:
      return TreeEntry::Vectorize;
    case LoadsState::ScatterVectorize:
      return TreeEntry::ScatterVectorize;
    case LoadsState::StridedVectorize:
      return TreeEntry::StridedVectorize;
    case LoadsState::Gather:
#ifndef NDEBUG
      Type *ScalarTy = VL0->getType();
      if (DL->getTypeSizeInBits(ScalarTy) !=
          DL->getTypeAllocSizeInBits(ScalarTy))
        LLVM_DEBUG(dbgs() << "SLP: Gathering loads of non-packed type.\n");
      else if (any_of(VL,
                      [](Value *V) { return !cast<LoadInst>(V)->isSimple(); }))
        LLVM_DEBUG(dbgs() << "SLP: Gathering non-simple loads.\n");
      else
        LLVM_DEBUG(dbgs() << "SLP: Gathering non-consecutive loads.\n");
#endif // NDEBUG
      registerNonVectorizableLoads(VL);
      return TreeEntry::NeedToGather;
    }
    llvm_unreachable("Unexpected state of loads");
  }
  case Instruction::ZExt:
  case Instruction::SExt:
  case Instruction::FPToUI:
  case Instruction::FPToSI:
  case Instruction::FPExt:
  case Instruction::PtrToInt:
  case Instruction::IntToPtr:
  case Instruction::SIToFP:
  case Instruction::UIToFP:
  case Instruction::Trunc:
  case Instruction::FPTrunc:
  case Instruction::BitCast: {
    Type *SrcTy = VL0->getOperand(0)->getType();
    for (Value *V : VL) {
      Type *Ty = cast<Instruction>(V)->getOperand(0)->getType();
      if (Ty != SrcTy || !isValidElementType(Ty)) {
        LLVM_DEBUG(
            dbgs() << "SLP: Gathering casts with different src types.\n");
        return TreeEntry::NeedToGather;
      }
    }
    return TreeEntry::Vectorize;
  }
  case Instruction::ICmp:
  case Instruction::FCmp: {
    // Check that all of the compares have the same predicate.
    CmpInst::Predicate P0 = cast<CmpInst>(VL0)->getPredicate();
    CmpInst::Predicate SwapP0 = CmpInst::getSwappedPredicate(P0);
    Type *ComparedTy = VL0->getOperand(0)->getType();
    for (Value *V : VL) {
      CmpInst *Cmp = cast<CmpInst>(V);
      if ((Cmp->getPredicate() != P0 && Cmp->getPredicate() != SwapP0) ||
          Cmp->getOperand(0)->getType() != ComparedTy) {
        LLVM_DEBUG(dbgs() << "SLP: Gathering cmp with different predicate.\n");
        return TreeEntry::NeedToGather;
      }
    }
    return TreeEntry::Vectorize;
  }
  case Instruction::Select:
  case Instruction::FNeg:
  case Instruction::Add:
  case Instruction::FAdd:
  case Instruction::Sub:
  case Instruction::FSub:
  case Instruction::Mul:
  case Instruction::FMul:
  case Instruction::UDiv:
  case Instruction::SDiv:
  case Instruction::FDiv:
  case Instruction::URem:
  case Instruction::SRem:
  case Instruction::FRem:
  case Instruction::Shl:
  case Instruction::LShr:
  case Instruction::AShr:
  case Instruction::And:
  case Instruction::Or:
  case Instruction::Xor:
  case Instruction::Freeze:
    return TreeEntry::Vectorize;
  case Instruction::GetElementPtr: {
    // We don't combine GEPs with complicated (nested) indexing.
    for (Value *V : VL) {
      auto *I = dyn_cast<GetElementPtrInst>(V);
      if (!I)
        continue;
      if (I->getNumOperands() != 2) {
        LLVM_DEBUG(dbgs() << "SLP: not-vectorizable GEP (nested indexes).\n");
        return TreeEntry::NeedToGather;
      }
    }

    // We can't combine several GEPs into one vector if they operate on
    // different types.
    Type *Ty0 = cast<GEPOperator>(VL0)->getSourceElementType();
    for (Value *V : VL) {
      auto *GEP = dyn_cast<GEPOperator>(V);
      if (!GEP)
        continue;
      Type *CurTy = GEP->getSourceElementType();
      if (Ty0 != CurTy) {
        LLVM_DEBUG(dbgs() << "SLP: not-vectorizable GEP (different types).\n");
        return TreeEntry::NeedToGather;
      }
    }

    // We don't combine GEPs with non-constant indexes.
    Type *Ty1 = VL0->getOperand(1)->getType();
    for (Value *V : VL) {
      auto *I = dyn_cast<GetElementPtrInst>(V);
      if (!I)
        continue;
      auto *Op = I->getOperand(1);
      if ((!IsScatterVectorizeUserTE && !isa<ConstantInt>(Op)) ||
          (Op->getType() != Ty1 &&
           ((IsScatterVectorizeUserTE && !isa<ConstantInt>(Op)) ||
            Op->getType()->getScalarSizeInBits() >
                DL->getIndexSizeInBits(
                    V->getType()->getPointerAddressSpace())))) {
        LLVM_DEBUG(
            dbgs() << "SLP: not-vectorizable GEP (non-constant indexes).\n");
        return TreeEntry::NeedToGather;
      }
    }

    return TreeEntry::Vectorize;
  }
  case Instruction::Store: {
    // Check if the stores are consecutive or if we need to swizzle them.
    llvm::Type *ScalarTy = cast<StoreInst>(VL0)->getValueOperand()->getType();
    // Avoid types that are padded when being allocated as scalars, while
    // being packed together in a vector (such as i1).
    if (DL->getTypeSizeInBits(ScalarTy) !=
        DL->getTypeAllocSizeInBits(ScalarTy)) {
      LLVM_DEBUG(dbgs() << "SLP: Gathering stores of non-packed type.\n");
      return TreeEntry::NeedToGather;
    }
    // Make sure all stores in the bundle are simple - we can't vectorize
    // atomic or volatile stores.
    for (Value *V : VL) {
      auto *SI = cast<StoreInst>(V);
      if (!SI->isSimple()) {
        LLVM_DEBUG(dbgs() << "SLP: Gathering non-simple stores.\n");
        return TreeEntry::NeedToGather;
      }
      PointerOps.push_back(SI->getPointerOperand());
    }

    // Check the order of pointer operands.
    if (llvm::sortPtrAccesses(PointerOps, ScalarTy, *DL, *SE, CurrentOrder)) {
      Value *Ptr0;
      Value *PtrN;
      if (CurrentOrder.empty()) {
        Ptr0 = PointerOps.front();
        PtrN = PointerOps.back();
      } else {
        Ptr0 = PointerOps[CurrentOrder.front()];
        PtrN = PointerOps[CurrentOrder.back()];
      }
      std::optional<int> Dist =
          getPointersDiff(ScalarTy, Ptr0, ScalarTy, PtrN, *DL, *SE);
      // Check that the sorted pointer operands are consecutive.
      if (static_cast<unsigned>(*Dist) == VL.size() - 1)
        return TreeEntry::Vectorize;
    }

    LLVM_DEBUG(dbgs() << "SLP: Non-consecutive store.\n");
    return TreeEntry::NeedToGather;
  }
  case Instruction::Call: {
    // Check if the calls are all to the same vectorizable intrinsic or
    // library function.
    CallInst *CI = cast<CallInst>(VL0);
    Intrinsic::ID ID = getVectorIntrinsicIDForCall(CI, TLI);

    VFShape Shape = VFShape::get(
        CI->getFunctionType(),
        ElementCount::getFixed(static_cast<unsigned int>(VL.size())),
        false /*HasGlobalPred*/);
    Function *VecFunc = VFDatabase(*CI).getVectorizedFunction(Shape);

    if (!VecFunc && !isTriviallyVectorizable(ID)) {
      LLVM_DEBUG(dbgs() << "SLP: Non-vectorizable call.\n");
      return TreeEntry::NeedToGather;
    }
    Function *F = CI->getCalledFunction();
    unsigned NumArgs = CI->arg_size();
    SmallVector<Value *, 4> ScalarArgs(NumArgs, nullptr);
    for (unsigned J = 0; J != NumArgs; ++J)
      if (isVectorIntrinsicWithScalarOpAtArg(ID, J))
        ScalarArgs[J] = CI->getArgOperand(J);
    for (Value *V : VL) {
      CallInst *CI2 = dyn_cast<CallInst>(V);
      if (!CI2 || CI2->getCalledFunction() != F ||
          getVectorIntrinsicIDForCall(CI2, TLI) != ID ||
          (VecFunc &&
           VecFunc != VFDatabase(*CI2).getVectorizedFunction(Shape)) ||
          !CI->hasIdenticalOperandBundleSchema(*CI2)) {
        LLVM_DEBUG(dbgs() << "SLP: mismatched calls:" << *CI << "!=" << *V
                          << "\n");
        return TreeEntry::NeedToGather;
      }
      // Some intrinsics have scalar arguments and should be same in order for
      // them to be vectorized.
      for (unsigned J = 0; J != NumArgs; ++J) {
        if (isVectorIntrinsicWithScalarOpAtArg(ID, J)) {
          Value *A1J = CI2->getArgOperand(J);
          if (ScalarArgs[J] != A1J) {
            LLVM_DEBUG(dbgs()
                       << "SLP: mismatched arguments in call:" << *CI
                       << " argument " << ScalarArgs[J] << "!=" << A1J << "\n");
            return TreeEntry::NeedToGather;
          }
        }
      }
      // Verify that the bundle operands are identical between the two calls.
      if (CI->hasOperandBundles() &&
          !std::equal(CI->op_begin() + CI->getBundleOperandsStartIndex(),
                      CI->op_begin() + CI->getBundleOperandsEndIndex(),
                      CI2->op_begin() + CI2->getBundleOperandsStartIndex())) {
        LLVM_DEBUG(dbgs() << "SLP: mismatched bundle operands in calls:" << *CI
                          << "!=" << *V << '\n');
        return TreeEntry::NeedToGather;
      }
    }

    return TreeEntry::Vectorize;
  }
  case Instruction::ShuffleVector: {
    if (!S.isAltShuffle()) {
      // REVEC can support non alternate shuffle.
      if (SLPReVec && getShufflevectorNumGroups(VL))
        return TreeEntry::Vectorize;
      // If this is not an alternate sequence of opcode like add-sub
      // then do not vectorize this instruction.
      LLVM_DEBUG(dbgs() << "SLP: ShuffleVector are not vectorized.\n");
      return TreeEntry::NeedToGather;
    }
    if (!SLPSkipEarlyProfitabilityCheck && !areAltOperandsProfitable(S, VL)) {
      LLVM_DEBUG(
          dbgs()
          << "SLP: ShuffleVector not vectorized, operands are buildvector and "
             "the whole alt sequence is not profitable.\n");
      return TreeEntry::NeedToGather;
    }

    return TreeEntry::Vectorize;
  }
  default:
    LLVM_DEBUG(dbgs() << "SLP: Gathering unknown instruction.\n");
    return TreeEntry::NeedToGather;
  }
}

namespace {
/// Allows to correctly handle operands of the phi nodes based on the \p Main
/// PHINode order of incoming basic blocks/values.
class PHIHandler {
  DominatorTree &DT;
  PHINode *Main = nullptr;
  SmallVector<Value *> Phis;
  SmallVector<SmallVector<Value *>> Operands;

public:
  PHIHandler() = delete;
  PHIHandler(DominatorTree &DT, PHINode *Main, ArrayRef<Value *> Phis)
      : DT(DT), Main(Main), Phis(Phis),
        Operands(Main->getNumIncomingValues(),
                 SmallVector<Value *>(Phis.size(), nullptr)) {}
  void buildOperands() {
    constexpr unsigned FastLimit = 4;
    if (Main->getNumIncomingValues() <= FastLimit) {
      for (unsigned I : seq<unsigned>(0, Main->getNumIncomingValues())) {
        BasicBlock *InBB = Main->getIncomingBlock(I);
        if (!DT.isReachableFromEntry(InBB)) {
          Operands[I].assign(Phis.size(), PoisonValue::get(Main->getType()));
          continue;
        }
        // Prepare the operand vector.
        for (auto [Idx, V] : enumerate(Phis)) {
          auto *P = cast<PHINode>(V);
          if (P->getIncomingBlock(I) == InBB)
            Operands[I][Idx] = P->getIncomingValue(I);
          else
            Operands[I][Idx] = P->getIncomingValueForBlock(InBB);
        }
      }
      return;
    }
    SmallDenseMap<BasicBlock *, SmallVector<unsigned>, 4> Blocks;
    for (unsigned I : seq<unsigned>(0, Main->getNumIncomingValues())) {
      BasicBlock *InBB = Main->getIncomingBlock(I);
      if (!DT.isReachableFromEntry(InBB)) {
        Operands[I].assign(Phis.size(), PoisonValue::get(Main->getType()));
        continue;
      }
      Blocks.try_emplace(InBB).first->second.push_back(I);
    }
    for (auto [Idx, V] : enumerate(Phis)) {
      auto *P = cast<PHINode>(V);
      for (unsigned I : seq<unsigned>(0, P->getNumIncomingValues())) {
        BasicBlock *InBB = P->getIncomingBlock(I);
        if (InBB == Main->getIncomingBlock(I)) {
          if (isa_and_nonnull<PoisonValue>(Operands[I][Idx]))
            continue;
          Operands[I][Idx] = P->getIncomingValue(I);
          continue;
        }
        auto It = Blocks.find(InBB);
        if (It == Blocks.end())
          continue;
        Operands[It->second.front()][Idx] = P->getIncomingValue(I);
      }
    }
    for (const auto &P : Blocks) {
      if (P.getSecond().size() <= 1)
        continue;
      unsigned BasicI = P.getSecond().front();
      for (unsigned I : ArrayRef(P.getSecond()).drop_front()) {
        assert(all_of(enumerate(Operands[I]),
                      [&](const auto &Data) {
                        return !Data.value() ||
                               Data.value() == Operands[BasicI][Data.index()];
                      }) &&
               "Expected empty operands list.");
        Operands[I] = Operands[BasicI];
      }
    }
  }
  ArrayRef<Value *> getOperands(unsigned I) const { return Operands[I]; }
};
} // namespace

void BoUpSLP::buildTree_rec(ArrayRef<Value *> VL, unsigned Depth,
                            const EdgeInfo &UserTreeIdx) {
  assert((allConstant(VL) || allSameType(VL)) && "Invalid types!");

  SmallVector<int> ReuseShuffleIndices;
  SmallVector<Value *> UniqueValues;
  SmallVector<Value *> NonUniqueValueVL;
  auto TryToFindDuplicates = [&](const InstructionsState &S,
                                 bool DoNotFail = false) {
    // Check that every instruction appears once in this bundle.
    DenseMap<Value *, unsigned> UniquePositions(VL.size());
    for (Value *V : VL) {
      if (isConstant(V)) {
        ReuseShuffleIndices.emplace_back(
            isa<UndefValue>(V) ? PoisonMaskElem : UniqueValues.size());
        UniqueValues.emplace_back(V);
        continue;
      }
      auto Res = UniquePositions.try_emplace(V, UniqueValues.size());
      ReuseShuffleIndices.emplace_back(Res.first->second);
      if (Res.second)
        UniqueValues.emplace_back(V);
    }
    size_t NumUniqueScalarValues = UniqueValues.size();
    if (NumUniqueScalarValues == VL.size()) {
      ReuseShuffleIndices.clear();
    } else {
      // FIXME: Reshuffing scalars is not supported yet for non-power-of-2 ops.
      if ((UserTreeIdx.UserTE && UserTreeIdx.UserTE->isNonPowOf2Vec()) ||
          !llvm::has_single_bit(VL.size())) {
        LLVM_DEBUG(dbgs() << "SLP: Reshuffling scalars not yet supported "
                             "for nodes with padding.\n");
        newTreeEntry(VL, std::nullopt /*not vectorized*/, S, UserTreeIdx);
        return false;
      }
      LLVM_DEBUG(dbgs() << "SLP: Shuffle for reused scalars.\n");
      if (NumUniqueScalarValues <= 1 ||
          (UniquePositions.size() == 1 && all_of(UniqueValues,
                                                 [](Value *V) {
                                                   return isa<UndefValue>(V) ||
                                                          !isConstant(V);
                                                 })) ||
          !llvm::has_single_bit<uint32_t>(NumUniqueScalarValues)) {
        if (DoNotFail && UniquePositions.size() > 1 &&
            NumUniqueScalarValues > 1 && S.MainOp->isSafeToRemove() &&
            all_of(UniqueValues, [=](Value *V) {
              return isa<ExtractElementInst>(V) ||
                     areAllUsersVectorized(cast<Instruction>(V),
                                           UserIgnoreList);
            })) {
          unsigned PWSz = PowerOf2Ceil(UniqueValues.size());
          if (PWSz == VL.size()) {
            ReuseShuffleIndices.clear();
          } else {
            NonUniqueValueVL.assign(UniqueValues.begin(), UniqueValues.end());
            NonUniqueValueVL.append(PWSz - UniqueValues.size(),
                                    UniqueValues.back());
            VL = NonUniqueValueVL;
          }
          return true;
        }
        LLVM_DEBUG(dbgs() << "SLP: Scalar used twice in bundle.\n");
        newTreeEntry(VL, std::nullopt /*not vectorized*/, S, UserTreeIdx);
        return false;
      }
      VL = UniqueValues;
    }
    return true;
  };

  InstructionsState S = getSameOpcode(VL, *TLI);

  // Don't go into catchswitch blocks, which can happen with PHIs.
  // Such blocks can only have PHIs and the catchswitch.  There is no
  // place to insert a shuffle if we need to, so just avoid that issue.
  if (S.MainOp &&
      isa<CatchSwitchInst>(S.MainOp->getParent()->getTerminator())) {
    LLVM_DEBUG(dbgs() << "SLP: bundle in catchswitch block.\n");
    newTreeEntry(VL, std::nullopt /*not vectorized*/, S, UserTreeIdx);
    return;
  }

  // Check if this is a duplicate of another entry.
  if (S.getOpcode()) {
    if (TreeEntry *E = getTreeEntry(S.OpValue)) {
      LLVM_DEBUG(dbgs() << "SLP: \tChecking bundle: " << *S.OpValue << ".\n");
      if (GatheredLoadsEntriesFirst != NoGatheredLoads || !E->isSame(VL)) {
        auto It = MultiNodeScalars.find(S.OpValue);
        if (It != MultiNodeScalars.end()) {
          auto *TEIt = find_if(It->getSecond(),
                               [&](TreeEntry *ME) { return ME->isSame(VL); });
          if (TEIt != It->getSecond().end())
            E = *TEIt;
          else
            E = nullptr;
        } else {
          E = nullptr;
        }
      }
      if (!E) {
        if (!doesNotNeedToBeScheduled(S.OpValue)) {
          LLVM_DEBUG(dbgs() << "SLP: Gathering due to partial overlap.\n");
          if (TryToFindDuplicates(S))
            newTreeEntry(VL, std::nullopt /*not vectorized*/, S, UserTreeIdx,
                         ReuseShuffleIndices);
          return;
        }
        SmallPtrSet<const TreeEntry *, 4> Nodes;
        Nodes.insert(getTreeEntry(S.OpValue));
        for (const TreeEntry *E : MultiNodeScalars.lookup(S.OpValue))
          Nodes.insert(E);
        SmallPtrSet<Value *, 8> Values(VL.begin(), VL.end());
        if (any_of(Nodes, [&](const TreeEntry *E) {
              return all_of(E->Scalars,
                            [&](Value *V) { return Values.contains(V); });
            })) {
          LLVM_DEBUG(dbgs() << "SLP: Gathering due to full overlap.\n");
          if (TryToFindDuplicates(S))
            newTreeEntry(VL, std::nullopt /*not vectorized*/, S, UserTreeIdx,
                         ReuseShuffleIndices);
          return;
        }
      } else {
        // Record the reuse of the tree node.  FIXME, currently this is only
        // used to properly draw the graph rather than for the actual
        // vectorization.
        E->UserTreeIndices.push_back(UserTreeIdx);
        LLVM_DEBUG(dbgs() << "SLP: Perfect diamond merge at " << *S.OpValue
                          << ".\n");
        return;
      }
    }
  }

  // Gather if we hit the RecursionMaxDepth, unless this is a load (or z/sext of
  // a load), in which case peek through to include it in the tree, without
  // ballooning over-budget.
  if (Depth >= RecursionMaxDepth &&
      !(S.MainOp && isa<Instruction>(S.MainOp) && S.MainOp == S.AltOp &&
        VL.size() >= 4 &&
        (match(S.MainOp, m_Load(m_Value())) || all_of(VL, [&S](const Value *I) {
           return match(I,
                        m_OneUse(m_ZExtOrSExt(m_OneUse(m_Load(m_Value()))))) &&
                  cast<Instruction>(I)->getOpcode() ==
                      cast<Instruction>(S.MainOp)->getOpcode();
         })))) {
    LLVM_DEBUG(dbgs() << "SLP: Gathering due to max recursion depth.\n");
    if (TryToFindDuplicates(S))
      newTreeEntry(VL, std::nullopt /*not vectorized*/, S, UserTreeIdx,
                   ReuseShuffleIndices);
    return;
  }

  // Don't handle scalable vectors
  if (S.getOpcode() == Instruction::ExtractElement &&
      isa<ScalableVectorType>(
          cast<ExtractElementInst>(S.OpValue)->getVectorOperandType())) {
    LLVM_DEBUG(dbgs() << "SLP: Gathering due to scalable vector type.\n");
    if (TryToFindDuplicates(S))
      newTreeEntry(VL, std::nullopt /*not vectorized*/, S, UserTreeIdx,
                   ReuseShuffleIndices);
    return;
  }

  // Don't handle vectors.
  if (!SLPReVec && getValueType(S.OpValue)->isVectorTy()) {
    LLVM_DEBUG(dbgs() << "SLP: Gathering due to vector type.\n");
    newTreeEntry(VL, std::nullopt /*not vectorized*/, S, UserTreeIdx);
    return;
  }

  // If all of the operands are identical or constant we have a simple solution.
  // If we deal with insert/extract instructions, they all must have constant
  // indices, otherwise we should gather them, not try to vectorize.
  // If alternate op node with 2 elements with gathered operands - do not
  // vectorize.
  auto &&NotProfitableForVectorization = [&S, this,
                                          Depth](ArrayRef<Value *> VL) {
    if (!S.getOpcode() || !S.isAltShuffle() || VL.size() > 2)
      return false;
    if (VectorizableTree.size() < MinTreeSize)
      return false;
    if (Depth >= RecursionMaxDepth - 1)
      return true;
    // Check if all operands are extracts, part of vector node or can build a
    // regular vectorize node.
    SmallVector<unsigned, 2> InstsCount(VL.size(), 0);
    for (Value *V : VL) {
      auto *I = cast<Instruction>(V);
      InstsCount.push_back(count_if(I->operand_values(), [](Value *Op) {
        return isa<Instruction>(Op) || isVectorLikeInstWithConstOps(Op);
      }));
    }
    bool IsCommutative = isCommutative(S.MainOp) || isCommutative(S.AltOp);
    if ((IsCommutative &&
         std::accumulate(InstsCount.begin(), InstsCount.end(), 0) < 2) ||
        (!IsCommutative &&
         all_of(InstsCount, [](unsigned ICnt) { return ICnt < 2; })))
      return true;
    assert(VL.size() == 2 && "Expected only 2 alternate op instructions.");
    SmallVector<SmallVector<std::pair<Value *, Value *>>> Candidates;
    auto *I1 = cast<Instruction>(VL.front());
    auto *I2 = cast<Instruction>(VL.back());
    for (int Op = 0, E = S.MainOp->getNumOperands(); Op < E; ++Op)
      Candidates.emplace_back().emplace_back(I1->getOperand(Op),
                                             I2->getOperand(Op));
    if (static_cast<unsigned>(count_if(
            Candidates, [this](ArrayRef<std::pair<Value *, Value *>> Cand) {
              return findBestRootPair(Cand, LookAheadHeuristics::ScoreSplat);
            })) >= S.MainOp->getNumOperands() / 2)
      return false;
    if (S.MainOp->getNumOperands() > 2)
      return true;
    if (IsCommutative) {
      // Check permuted operands.
      Candidates.clear();
      for (int Op = 0, E = S.MainOp->getNumOperands(); Op < E; ++Op)
        Candidates.emplace_back().emplace_back(I1->getOperand(Op),
                                               I2->getOperand((Op + 1) % E));
      if (any_of(
              Candidates, [this](ArrayRef<std::pair<Value *, Value *>> Cand) {
                return findBestRootPair(Cand, LookAheadHeuristics::ScoreSplat);
              }))
        return false;
    }
    return true;
  };
  SmallVector<unsigned> SortedIndices;
  BasicBlock *BB = nullptr;
  bool IsScatterVectorizeUserTE =
      UserTreeIdx.UserTE &&
      UserTreeIdx.UserTE->State == TreeEntry::ScatterVectorize;
  bool AreAllSameBlock = S.getOpcode() && allSameBlock(VL);
  bool AreScatterAllGEPSameBlock =
      (IsScatterVectorizeUserTE && S.OpValue->getType()->isPointerTy() &&
       VL.size() > 2 &&
       all_of(VL,
              [&BB](Value *V) {
                auto *I = dyn_cast<GetElementPtrInst>(V);
                if (!I)
                  return doesNotNeedToBeScheduled(V);
                if (!BB)
                  BB = I->getParent();
                return BB == I->getParent() && I->getNumOperands() == 2;
              }) &&
       BB &&
       sortPtrAccesses(VL, UserTreeIdx.UserTE->getMainOp()->getType(), *DL, *SE,
                       SortedIndices));
  bool AreAllSameInsts = AreAllSameBlock || AreScatterAllGEPSameBlock;
  if (!AreAllSameInsts || (!S.getOpcode() && allConstant(VL)) || isSplat(VL) ||
      (isa<InsertElementInst, ExtractValueInst, ExtractElementInst>(
           S.OpValue) &&
       !all_of(VL, isVectorLikeInstWithConstOps)) ||
      NotProfitableForVectorization(VL)) {
    LLVM_DEBUG(dbgs() << "SLP: Gathering due to C,S,B,O, small shuffle. \n");
    if (TryToFindDuplicates(S))
      newTreeEntry(VL, std::nullopt /*not vectorized*/, S, UserTreeIdx,
                   ReuseShuffleIndices);
    return;
  }

  // Don't vectorize ephemeral values.
  if (S.getOpcode() && !EphValues.empty()) {
    for (Value *V : VL) {
      if (EphValues.count(V)) {
        LLVM_DEBUG(dbgs() << "SLP: The instruction (" << *V
                          << ") is ephemeral.\n");
        newTreeEntry(VL, std::nullopt /*not vectorized*/, S, UserTreeIdx);
        return;
      }
    }
  }

  // We now know that this is a vector of instructions of the same type from
  // the same block.

  // Check that none of the instructions in the bundle are already in the tree.
  for (Value *V : VL) {
    if ((!IsScatterVectorizeUserTE && !isa<Instruction>(V)) ||
        doesNotNeedToBeScheduled(V))
      continue;
    if (getTreeEntry(V)) {
      LLVM_DEBUG(dbgs() << "SLP: The instruction (" << *V
                        << ") is already in tree.\n");
      if (TryToFindDuplicates(S))
        newTreeEntry(VL, std::nullopt /*not vectorized*/, S, UserTreeIdx,
                     ReuseShuffleIndices);
      return;
    }
  }

  // The reduction nodes (stored in UserIgnoreList) also should stay scalar.
  if (UserIgnoreList && !UserIgnoreList->empty()) {
    for (Value *V : VL) {
      if (UserIgnoreList->contains(V)) {
        LLVM_DEBUG(dbgs() << "SLP: Gathering due to gathered scalar.\n");
        if (TryToFindDuplicates(S))
          newTreeEntry(VL, std::nullopt /*not vectorized*/, S, UserTreeIdx,
                       ReuseShuffleIndices);
        return;
      }
    }
  }

  // Special processing for sorted pointers for ScatterVectorize node with
  // constant indeces only.
  if (!AreAllSameBlock && AreScatterAllGEPSameBlock) {
    assert(S.OpValue->getType()->isPointerTy() &&
           count_if(VL, IsaPred<GetElementPtrInst>) >= 2 &&
           "Expected pointers only.");
    // Reset S to make it GetElementPtr kind of node.
    const auto *It = find_if(VL, IsaPred<GetElementPtrInst>);
    assert(It != VL.end() && "Expected at least one GEP.");
    S = getSameOpcode(*It, *TLI);
  }

  // Check that all of the users of the scalars that we want to vectorize are
  // schedulable.
  auto *VL0 = cast<Instruction>(S.OpValue);
  BB = VL0->getParent();

  if (S.MainOp && !DT->isReachableFromEntry(BB)) {
    // Don't go into unreachable blocks. They may contain instructions with
    // dependency cycles which confuse the final scheduling.
    LLVM_DEBUG(dbgs() << "SLP: bundle in unreachable block.\n");
    newTreeEntry(VL, std::nullopt /*not vectorized*/, S, UserTreeIdx);
    return;
  }

  // Check that every instruction appears once in this bundle.
  if (!TryToFindDuplicates(S, /*DoNotFail=*/true))
    return;

  // Perform specific checks for each particular instruction kind.
  OrdersType CurrentOrder;
  SmallVector<Value *> PointerOps;
  TreeEntry::EntryState State = getScalarsVectorizationState(
      S, VL, IsScatterVectorizeUserTE, CurrentOrder, PointerOps);
  if (State == TreeEntry::NeedToGather) {
    newTreeEntry(VL, std::nullopt /*not vectorized*/, S, UserTreeIdx,
                 ReuseShuffleIndices);
    return;
  }

  auto &BSRef = BlocksSchedules[BB];
  if (!BSRef)
    BSRef = std::make_unique<BlockScheduling>(BB);

  BlockScheduling &BS = *BSRef;

  std::optional<ScheduleData *> Bundle =
      BS.tryScheduleBundle(UniqueValues, this, S);
#ifdef EXPENSIVE_CHECKS
  // Make sure we didn't break any internal invariants
  BS.verify();
#endif
  if (!Bundle) {
    LLVM_DEBUG(dbgs() << "SLP: We are not able to schedule this bundle!\n");
    assert((!BS.getScheduleData(VL0) ||
            !BS.getScheduleData(VL0)->isPartOfBundle()) &&
           "tryScheduleBundle should cancelScheduling on failure");
    newTreeEntry(VL, std::nullopt /*not vectorized*/, S, UserTreeIdx,
                 ReuseShuffleIndices);
    NonScheduledFirst.insert(VL.front());
    if (S.getOpcode() == Instruction::Load &&
        BS.ScheduleRegionSize < BS.ScheduleRegionSizeLimit)
      registerNonVectorizableLoads(VL);
    return;
  }
  LLVM_DEBUG(dbgs() << "SLP: We are able to schedule this bundle.\n");

  unsigned ShuffleOrOp = S.isAltShuffle() ?
                (unsigned) Instruction::ShuffleVector : S.getOpcode();
  auto CreateOperandNodes = [&](TreeEntry *TE, const auto &Operands) {
    // Postpone PHI nodes creation
    SmallVector<unsigned> PHIOps;
    for (unsigned I : seq<unsigned>(Operands.size())) {
      ArrayRef<Value *> Op = Operands[I];
      if (Op.empty())
        continue;
      InstructionsState S = getSameOpcode(Op, *TLI);
      if (S.getOpcode() != Instruction::PHI || S.isAltShuffle())
        buildTree_rec(Op, Depth + 1, {TE, I});
      else
        PHIOps.push_back(I);
    }
    for (unsigned I : PHIOps)
      buildTree_rec(Operands[I], Depth + 1, {TE, I});
  };
  switch (ShuffleOrOp) {
    case Instruction::PHI: {
      auto *PH = cast<PHINode>(VL0);

      TreeEntry *TE =
          newTreeEntry(VL, Bundle, S, UserTreeIdx, ReuseShuffleIndices);
      LLVM_DEBUG(dbgs() << "SLP: added a vector of PHINodes.\n");

      // Keeps the reordered operands to avoid code duplication.
      PHIHandler Handler(*DT, PH, VL);
      Handler.buildOperands();
      for (unsigned I : seq<unsigned>(PH->getNumOperands()))
        TE->setOperand(I, Handler.getOperands(I));
      SmallVector<ArrayRef<Value *>> Operands(PH->getNumOperands());
      for (unsigned I : seq<unsigned>(PH->getNumOperands()))
        Operands[I] = Handler.getOperands(I);
      CreateOperandNodes(TE, Operands);
      return;
    }
    case Instruction::ExtractValue:
    case Instruction::ExtractElement: {
      if (CurrentOrder.empty()) {
        LLVM_DEBUG(dbgs() << "SLP: Reusing or shuffling extract sequence.\n");
      } else {
        LLVM_DEBUG({
          dbgs() << "SLP: Reusing or shuffling of reordered extract sequence "
                    "with order";
          for (unsigned Idx : CurrentOrder)
            dbgs() << " " << Idx;
          dbgs() << "\n";
        });
        fixupOrderingIndices(CurrentOrder);
      }
      // Insert new order with initial value 0, if it does not exist,
      // otherwise return the iterator to the existing one.
      newTreeEntry(VL, Bundle /*vectorized*/, S, UserTreeIdx,
                   ReuseShuffleIndices, CurrentOrder);
      // This is a special case, as it does not gather, but at the same time
      // we are not extending buildTree_rec() towards the operands.
      ValueList Op0;
      Op0.assign(VL.size(), VL0->getOperand(0));
      VectorizableTree.back()->setOperand(0, Op0);
      return;
    }
    case Instruction::InsertElement: {
      assert(ReuseShuffleIndices.empty() && "All inserts should be unique");

      auto OrdCompare = [](const std::pair<int, int> &P1,
                           const std::pair<int, int> &P2) {
        return P1.first > P2.first;
      };
      PriorityQueue<std::pair<int, int>, SmallVector<std::pair<int, int>>,
                    decltype(OrdCompare)>
          Indices(OrdCompare);
      for (int I = 0, E = VL.size(); I < E; ++I) {
        unsigned Idx = *getElementIndex(VL[I]);
        Indices.emplace(Idx, I);
      }
      OrdersType CurrentOrder(VL.size(), VL.size());
      bool IsIdentity = true;
      for (int I = 0, E = VL.size(); I < E; ++I) {
        CurrentOrder[Indices.top().second] = I;
        IsIdentity &= Indices.top().second == I;
        Indices.pop();
      }
      if (IsIdentity)
        CurrentOrder.clear();
      TreeEntry *TE = newTreeEntry(VL, Bundle /*vectorized*/, S, UserTreeIdx,
                                   {}, CurrentOrder);
      LLVM_DEBUG(dbgs() << "SLP: added inserts bundle.\n");

      TE->setOperandsInOrder();
      buildTree_rec(TE->getOperand(1), Depth + 1, {TE, 1});
      return;
    }
    case Instruction::Load: {
      // Check that a vectorized load would load the same memory as a scalar
      // load. For example, we don't want to vectorize loads that are smaller
      // than 8-bit. Even though we have a packed struct {<i2, i2, i2, i2>} LLVM
      // treats loading/storing it as an i8 struct. If we vectorize loads/stores
      // from such a struct, we read/write packed bits disagreeing with the
      // unvectorized version.
      TreeEntry *TE = nullptr;
      fixupOrderingIndices(CurrentOrder);
      switch (State) {
      case TreeEntry::Vectorize:
        TE = newTreeEntry(VL, Bundle /*vectorized*/, S, UserTreeIdx,
                          ReuseShuffleIndices, CurrentOrder);
        if (CurrentOrder.empty())
          LLVM_DEBUG(dbgs() << "SLP: added a vector of loads.\n");
        else
          LLVM_DEBUG(dbgs() << "SLP: added a vector of jumbled loads.\n");
        TE->setOperandsInOrder();
        break;
      case TreeEntry::StridedVectorize:
        // Vectorizing non-consecutive loads with `llvm.masked.gather`.
        TE = newTreeEntry(VL, TreeEntry::StridedVectorize, Bundle, S,
                          UserTreeIdx, ReuseShuffleIndices, CurrentOrder);
        TE->setOperandsInOrder();
        LLVM_DEBUG(dbgs() << "SLP: added a vector of strided loads.\n");
        break;
      case TreeEntry::ScatterVectorize:
        // Vectorizing non-consecutive loads with `llvm.masked.gather`.
        TE = newTreeEntry(VL, TreeEntry::ScatterVectorize, Bundle, S,
                          UserTreeIdx, ReuseShuffleIndices);
        TE->setOperandsInOrder();
        buildTree_rec(PointerOps, Depth + 1, {TE, 0});
        LLVM_DEBUG(dbgs() << "SLP: added a vector of non-consecutive loads.\n");
        break;
      case TreeEntry::CombinedVectorize:
      case TreeEntry::NeedToGather:
        llvm_unreachable("Unexpected loads state.");
      }
      return;
    }
    case Instruction::ZExt:
    case Instruction::SExt:
    case Instruction::FPToUI:
    case Instruction::FPToSI:
    case Instruction::FPExt:
    case Instruction::PtrToInt:
    case Instruction::IntToPtr:
    case Instruction::SIToFP:
    case Instruction::UIToFP:
    case Instruction::Trunc:
    case Instruction::FPTrunc:
    case Instruction::BitCast: {
      auto [PrevMaxBW, PrevMinBW] = CastMaxMinBWSizes.value_or(
          std::make_pair(std::numeric_limits<unsigned>::min(),
                         std::numeric_limits<unsigned>::max()));
      if (ShuffleOrOp == Instruction::ZExt ||
          ShuffleOrOp == Instruction::SExt) {
        CastMaxMinBWSizes = std::make_pair(
            std::max<unsigned>(DL->getTypeSizeInBits(VL0->getType()),
                               PrevMaxBW),
            std::min<unsigned>(
                DL->getTypeSizeInBits(VL0->getOperand(0)->getType()),
                PrevMinBW));
      } else if (ShuffleOrOp == Instruction::Trunc) {
        CastMaxMinBWSizes = std::make_pair(
            std::max<unsigned>(
                DL->getTypeSizeInBits(VL0->getOperand(0)->getType()),
                PrevMaxBW),
            std::min<unsigned>(DL->getTypeSizeInBits(VL0->getType()),
                               PrevMinBW));
      }
      TreeEntry *TE = newTreeEntry(VL, Bundle /*vectorized*/, S, UserTreeIdx,
                                   ReuseShuffleIndices);
      LLVM_DEBUG(dbgs() << "SLP: added a vector of casts.\n");

      TE->setOperandsInOrder();
      for (unsigned I : seq<unsigned>(0, VL0->getNumOperands()))
        buildTree_rec(TE->getOperand(I), Depth + 1, {TE, I});
      if (ShuffleOrOp == Instruction::Trunc) {
        ExtraBitWidthNodes.insert(getOperandEntry(TE, 0)->Idx);
      } else if (ShuffleOrOp == Instruction::SIToFP ||
                 ShuffleOrOp == Instruction::UIToFP) {
        unsigned NumSignBits =
            ComputeNumSignBits(VL0->getOperand(0), *DL, 0, AC, nullptr, DT);
        if (auto *OpI = dyn_cast<Instruction>(VL0->getOperand(0))) {
          APInt Mask = DB->getDemandedBits(OpI);
          NumSignBits = std::max(NumSignBits, Mask.countl_zero());
        }
        if (NumSignBits * 2 >=
            DL->getTypeSizeInBits(VL0->getOperand(0)->getType()))
          ExtraBitWidthNodes.insert(getOperandEntry(TE, 0)->Idx);
      }
      return;
    }
    case Instruction::ICmp:
    case Instruction::FCmp: {
      // Check that all of the compares have the same predicate.
      CmpInst::Predicate P0 = cast<CmpInst>(VL0)->getPredicate();
      TreeEntry *TE = newTreeEntry(VL, Bundle /*vectorized*/, S, UserTreeIdx,
                                   ReuseShuffleIndices);
      LLVM_DEBUG(dbgs() << "SLP: added a vector of compares.\n");

      ValueList Left, Right;
      if (cast<CmpInst>(VL0)->isCommutative()) {
        // Commutative predicate - collect + sort operands of the instructions
        // so that each side is more likely to have the same opcode.
        assert(P0 == CmpInst::getSwappedPredicate(P0) &&
               "Commutative Predicate mismatch");
        reorderInputsAccordingToOpcode(VL, Left, Right, *this);
      } else {
        // Collect operands - commute if it uses the swapped predicate.
        for (Value *V : VL) {
          auto *Cmp = cast<CmpInst>(V);
          Value *LHS = Cmp->getOperand(0);
          Value *RHS = Cmp->getOperand(1);
          if (Cmp->getPredicate() != P0)
            std::swap(LHS, RHS);
          Left.push_back(LHS);
          Right.push_back(RHS);
        }
      }
      TE->setOperand(0, Left);
      TE->setOperand(1, Right);
      buildTree_rec(Left, Depth + 1, {TE, 0});
      buildTree_rec(Right, Depth + 1, {TE, 1});
      if (ShuffleOrOp == Instruction::ICmp) {
        unsigned NumSignBits0 =
            ComputeNumSignBits(VL0->getOperand(0), *DL, 0, AC, nullptr, DT);
        if (NumSignBits0 * 2 >=
            DL->getTypeSizeInBits(VL0->getOperand(0)->getType()))
          ExtraBitWidthNodes.insert(getOperandEntry(TE, 0)->Idx);
        unsigned NumSignBits1 =
            ComputeNumSignBits(VL0->getOperand(1), *DL, 0, AC, nullptr, DT);
        if (NumSignBits1 * 2 >=
            DL->getTypeSizeInBits(VL0->getOperand(1)->getType()))
          ExtraBitWidthNodes.insert(getOperandEntry(TE, 1)->Idx);
      }
      return;
    }
    case Instruction::Select:
    case Instruction::FNeg:
    case Instruction::Add:
    case Instruction::FAdd:
    case Instruction::Sub:
    case Instruction::FSub:
    case Instruction::Mul:
    case Instruction::FMul:
    case Instruction::UDiv:
    case Instruction::SDiv:
    case Instruction::FDiv:
    case Instruction::URem:
    case Instruction::SRem:
    case Instruction::FRem:
    case Instruction::Shl:
    case Instruction::LShr:
    case Instruction::AShr:
    case Instruction::And:
    case Instruction::Or:
    case Instruction::Xor:
    case Instruction::Freeze: {
      TreeEntry *TE = newTreeEntry(VL, Bundle /*vectorized*/, S, UserTreeIdx,
                                   ReuseShuffleIndices);
      LLVM_DEBUG(dbgs() << "SLP: added a vector of un/bin op.\n");

      // Sort operands of the instructions so that each side is more likely to
      // have the same opcode.
      if (isa<BinaryOperator>(VL0) && isCommutative(VL0)) {
        ValueList Left, Right;
        reorderInputsAccordingToOpcode(VL, Left, Right, *this);
        TE->setOperand(0, Left);
        TE->setOperand(1, Right);
        buildTree_rec(Left, Depth + 1, {TE, 0});
        buildTree_rec(Right, Depth + 1, {TE, 1});
        return;
      }

      TE->setOperandsInOrder();
      for (unsigned I : seq<unsigned>(0, VL0->getNumOperands()))
        buildTree_rec(TE->getOperand(I), Depth + 1, {TE, I});
      return;
    }
    case Instruction::GetElementPtr: {
      TreeEntry *TE = newTreeEntry(VL, Bundle /*vectorized*/, S, UserTreeIdx,
                                   ReuseShuffleIndices);
      LLVM_DEBUG(dbgs() << "SLP: added a vector of GEPs.\n");
      SmallVector<ValueList, 2> Operands(2);
      // Prepare the operand vector for pointer operands.
      for (Value *V : VL) {
        auto *GEP = dyn_cast<GetElementPtrInst>(V);
        if (!GEP) {
          Operands.front().push_back(V);
          continue;
        }
        Operands.front().push_back(GEP->getPointerOperand());
      }
      TE->setOperand(0, Operands.front());
      // Need to cast all indices to the same type before vectorization to
      // avoid crash.
      // Required to be able to find correct matches between different gather
      // nodes and reuse the vectorized values rather than trying to gather them
      // again.
      int IndexIdx = 1;
      Type *VL0Ty = VL0->getOperand(IndexIdx)->getType();
      Type *Ty = all_of(VL,
                        [VL0Ty, IndexIdx](Value *V) {
                          auto *GEP = dyn_cast<GetElementPtrInst>(V);
                          if (!GEP)
                            return true;
                          return VL0Ty == GEP->getOperand(IndexIdx)->getType();
                        })
                     ? VL0Ty
                     : DL->getIndexType(cast<GetElementPtrInst>(VL0)
                                            ->getPointerOperandType()
                                            ->getScalarType());
      // Prepare the operand vector.
      for (Value *V : VL) {
        auto *I = dyn_cast<GetElementPtrInst>(V);
        if (!I) {
          Operands.back().push_back(
              ConstantInt::get(Ty, 0, /*isSigned=*/false));
          continue;
        }
        auto *Op = I->getOperand(IndexIdx);
        auto *CI = dyn_cast<ConstantInt>(Op);
        if (!CI)
          Operands.back().push_back(Op);
        else
          Operands.back().push_back(ConstantFoldIntegerCast(
              CI, Ty, CI->getValue().isSignBitSet(), *DL));
      }
      TE->setOperand(IndexIdx, Operands.back());

      for (unsigned I = 0, Ops = Operands.size(); I < Ops; ++I)
        buildTree_rec(Operands[I], Depth + 1, {TE, I});
      return;
    }
    case Instruction::Store: {
      bool Consecutive = CurrentOrder.empty();
      if (!Consecutive)
        fixupOrderingIndices(CurrentOrder);
      TreeEntry *TE = newTreeEntry(VL, Bundle /*vectorized*/, S, UserTreeIdx,
                                   ReuseShuffleIndices, CurrentOrder);
      TE->setOperandsInOrder();
      buildTree_rec(TE->getOperand(0), Depth + 1, {TE, 0});
      if (Consecutive)
        LLVM_DEBUG(dbgs() << "SLP: added a vector of stores.\n");
      else
        LLVM_DEBUG(dbgs() << "SLP: added a vector of jumbled stores.\n");
      return;
    }
    case Instruction::Call: {
      // Check if the calls are all to the same vectorizable intrinsic or
      // library function.
      CallInst *CI = cast<CallInst>(VL0);
      Intrinsic::ID ID = getVectorIntrinsicIDForCall(CI, TLI);

      TreeEntry *TE = newTreeEntry(VL, Bundle /*vectorized*/, S, UserTreeIdx,
                                   ReuseShuffleIndices);
      // Sort operands of the instructions so that each side is more likely to
      // have the same opcode.
      if (isCommutative(VL0)) {
        ValueList Left, Right;
        reorderInputsAccordingToOpcode(VL, Left, Right, *this);
        TE->setOperand(0, Left);
        TE->setOperand(1, Right);
        SmallVector<ValueList> Operands;
        for (unsigned I : seq<unsigned>(2, CI->arg_size())) {
          Operands.emplace_back();
          if (isVectorIntrinsicWithScalarOpAtArg(ID, I))
            continue;
          for (Value *V : VL) {
            auto *CI2 = cast<CallInst>(V);
            Operands.back().push_back(CI2->getArgOperand(I));
          }
          TE->setOperand(I, Operands.back());
        }
        buildTree_rec(Left, Depth + 1, {TE, 0});
        buildTree_rec(Right, Depth + 1, {TE, 1});
        for (unsigned I : seq<unsigned>(2, CI->arg_size())) {
          if (Operands[I - 2].empty())
            continue;
          buildTree_rec(Operands[I - 2], Depth + 1, {TE, I});
        }
        return;
      }
      TE->setOperandsInOrder();
      for (unsigned I : seq<unsigned>(0, CI->arg_size())) {
        // For scalar operands no need to create an entry since no need to
        // vectorize it.
        if (isVectorIntrinsicWithScalarOpAtArg(ID, I))
          continue;
        ValueList Operands;
        // Prepare the operand vector.
        for (Value *V : VL) {
          auto *CI2 = cast<CallInst>(V);
          Operands.push_back(CI2->getArgOperand(I));
        }
        buildTree_rec(Operands, Depth + 1, {TE, I});
      }
      return;
    }
    case Instruction::ShuffleVector: {
      TreeEntry *TE = newTreeEntry(VL, Bundle /*vectorized*/, S, UserTreeIdx,
                                   ReuseShuffleIndices);
      LLVM_DEBUG(dbgs() << "SLP: added a ShuffleVector op.\n");

      // Reorder operands if reordering would enable vectorization.
      auto *CI = dyn_cast<CmpInst>(VL0);
      if (isa<BinaryOperator>(VL0) || CI) {
        ValueList Left, Right;
        if (!CI || all_of(VL, [](Value *V) {
              return cast<CmpInst>(V)->isCommutative();
            })) {
          reorderInputsAccordingToOpcode(VL, Left, Right, *this);
        } else {
          auto *MainCI = cast<CmpInst>(S.MainOp);
          auto *AltCI = cast<CmpInst>(S.AltOp);
          CmpInst::Predicate MainP = MainCI->getPredicate();
          CmpInst::Predicate AltP = AltCI->getPredicate();
          assert(MainP != AltP &&
                 "Expected different main/alternate predicates.");
          // Collect operands - commute if it uses the swapped predicate or
          // alternate operation.
          for (Value *V : VL) {
            auto *Cmp = cast<CmpInst>(V);
            Value *LHS = Cmp->getOperand(0);
            Value *RHS = Cmp->getOperand(1);

            if (isAlternateInstruction(Cmp, MainCI, AltCI, *TLI)) {
              if (AltP == CmpInst::getSwappedPredicate(Cmp->getPredicate()))
                std::swap(LHS, RHS);
            } else {
              if (MainP == CmpInst::getSwappedPredicate(Cmp->getPredicate()))
                std::swap(LHS, RHS);
            }
            Left.push_back(LHS);
            Right.push_back(RHS);
          }
        }
        TE->setOperand(0, Left);
        TE->setOperand(1, Right);
        buildTree_rec(Left, Depth + 1, {TE, 0});
        buildTree_rec(Right, Depth + 1, {TE, 1});
        return;
      }

      TE->setOperandsInOrder();
      for (unsigned I : seq<unsigned>(0, VL0->getNumOperands()))
        buildTree_rec(TE->getOperand(I), Depth + 1, {TE, I});
      return;
    }
    default:
      break;
  }
  llvm_unreachable("Unexpected vectorization of the instructions.");
}

unsigned BoUpSLP::canMapToVector(Type *T) const {
  unsigned N = 1;
  Type *EltTy = T;

  while (isa<StructType, ArrayType, FixedVectorType>(EltTy)) {
    if (EltTy->isEmptyTy())
      return 0;
    if (auto *ST = dyn_cast<StructType>(EltTy)) {
      // Check that struct is homogeneous.
      for (const auto *Ty : ST->elements())
        if (Ty != *ST->element_begin())
          return 0;
      N *= ST->getNumElements();
      EltTy = *ST->element_begin();
    } else if (auto *AT = dyn_cast<ArrayType>(EltTy)) {
      N *= AT->getNumElements();
      EltTy = AT->getElementType();
    } else {
      auto *VT = cast<FixedVectorType>(EltTy);
      N *= VT->getNumElements();
      EltTy = VT->getElementType();
    }
  }

  if (!isValidElementType(EltTy))
    return 0;
  uint64_t VTSize = DL->getTypeStoreSizeInBits(getWidenedType(EltTy, N));
  if (VTSize < MinVecRegSize || VTSize > MaxVecRegSize ||
      VTSize != DL->getTypeStoreSizeInBits(T))
    return 0;
  return N;
}

bool BoUpSLP::canReuseExtract(ArrayRef<Value *> VL, Value *OpValue,
                              SmallVectorImpl<unsigned> &CurrentOrder,
                              bool ResizeAllowed) const {
  const auto *It = find_if(VL, IsaPred<ExtractElementInst, ExtractValueInst>);
  assert(It != VL.end() && "Expected at least one extract instruction.");
  auto *E0 = cast<Instruction>(*It);
  assert(
      all_of(VL, IsaPred<UndefValue, ExtractElementInst, ExtractValueInst>) &&
      "Invalid opcode");
  // Check if all of the extracts come from the same vector and from the
  // correct offset.
  Value *Vec = E0->getOperand(0);

  CurrentOrder.clear();

  // We have to extract from a vector/aggregate with the same number of elements.
  unsigned NElts;
  if (E0->getOpcode() == Instruction::ExtractValue) {
    NElts = canMapToVector(Vec->getType());
    if (!NElts)
      return false;
    // Check if load can be rewritten as load of vector.
    LoadInst *LI = dyn_cast<LoadInst>(Vec);
    if (!LI || !LI->isSimple() || !LI->hasNUses(VL.size()))
      return false;
  } else {
    NElts = cast<FixedVectorType>(Vec->getType())->getNumElements();
  }

  unsigned E = VL.size();
  if (!ResizeAllowed && NElts != E)
    return false;
  SmallVector<int> Indices(E, PoisonMaskElem);
  unsigned MinIdx = NElts, MaxIdx = 0;
  for (auto [I, V] : enumerate(VL)) {
    auto *Inst = dyn_cast<Instruction>(V);
    if (!Inst)
      continue;
    if (Inst->getOperand(0) != Vec)
      return false;
    if (auto *EE = dyn_cast<ExtractElementInst>(Inst))
      if (isa<UndefValue>(EE->getIndexOperand()))
        continue;
    std::optional<unsigned> Idx = getExtractIndex(Inst);
    if (!Idx)
      return false;
    const unsigned ExtIdx = *Idx;
    if (ExtIdx >= NElts)
      continue;
    Indices[I] = ExtIdx;
    if (MinIdx > ExtIdx)
      MinIdx = ExtIdx;
    if (MaxIdx < ExtIdx)
      MaxIdx = ExtIdx;
  }
  if (MaxIdx - MinIdx + 1 > E)
    return false;
  if (MaxIdx + 1 <= E)
    MinIdx = 0;

  // Check that all of the indices extract from the correct offset.
  bool ShouldKeepOrder = true;
  // Assign to all items the initial value E + 1 so we can check if the extract
  // instruction index was used already.
  // Also, later we can check that all the indices are used and we have a
  // consecutive access in the extract instructions, by checking that no
  // element of CurrentOrder still has value E + 1.
  CurrentOrder.assign(E, E);
  for (unsigned I = 0; I < E; ++I) {
    if (Indices[I] == PoisonMaskElem)
      continue;
    const unsigned ExtIdx = Indices[I] - MinIdx;
    if (CurrentOrder[ExtIdx] != E) {
      CurrentOrder.clear();
      return false;
    }
    ShouldKeepOrder &= ExtIdx == I;
    CurrentOrder[ExtIdx] = I;
  }
  if (ShouldKeepOrder)
    CurrentOrder.clear();

  return ShouldKeepOrder;
}

bool BoUpSLP::areAllUsersVectorized(
    Instruction *I, const SmallDenseSet<Value *> *VectorizedVals) const {
  return (I->hasOneUse() && (!VectorizedVals || VectorizedVals->contains(I))) ||
         all_of(I->users(), [this](User *U) {
           return ScalarToTreeEntry.contains(U) ||
                  isVectorLikeInstWithConstOps(U) ||
                  (isa<ExtractElementInst>(U) && MustGather.contains(U));
         });
}

static std::pair<InstructionCost, InstructionCost>
getVectorCallCosts(CallInst *CI, FixedVectorType *VecTy,
                   TargetTransformInfo *TTI, TargetLibraryInfo *TLI,
                   ArrayRef<Type *> ArgTys) {
  Intrinsic::ID ID = getVectorIntrinsicIDForCall(CI, TLI);

  // Calculate the cost of the scalar and vector calls.
  FastMathFlags FMF;
  if (auto *FPCI = dyn_cast<FPMathOperator>(CI))
    FMF = FPCI->getFastMathFlags();
  SmallVector<const Value *> Arguments(CI->args());
  IntrinsicCostAttributes CostAttrs(ID, VecTy, Arguments, ArgTys, FMF,
                                    dyn_cast<IntrinsicInst>(CI));
  auto IntrinsicCost =
    TTI->getIntrinsicInstrCost(CostAttrs, TTI::TCK_RecipThroughput);

  auto Shape = VFShape::get(CI->getFunctionType(),
                            ElementCount::getFixed(VecTy->getNumElements()),
                            false /*HasGlobalPred*/);
  Function *VecFunc = VFDatabase(*CI).getVectorizedFunction(Shape);
  auto LibCost = IntrinsicCost;
  if (!CI->isNoBuiltin() && VecFunc) {
    // Calculate the cost of the vector library call.
    // If the corresponding vector call is cheaper, return its cost.
    LibCost =
        TTI->getCallInstrCost(nullptr, VecTy, ArgTys, TTI::TCK_RecipThroughput);
  }
  return {IntrinsicCost, LibCost};
}

void BoUpSLP::TreeEntry::buildAltOpShuffleMask(
    const function_ref<bool(Instruction *)> IsAltOp, SmallVectorImpl<int> &Mask,
    SmallVectorImpl<Value *> *OpScalars,
    SmallVectorImpl<Value *> *AltScalars) const {
  unsigned Sz = Scalars.size();
  Mask.assign(Sz, PoisonMaskElem);
  SmallVector<int> OrderMask;
  if (!ReorderIndices.empty())
    inversePermutation(ReorderIndices, OrderMask);
  for (unsigned I = 0; I < Sz; ++I) {
    unsigned Idx = I;
    if (!ReorderIndices.empty())
      Idx = OrderMask[I];
    auto *OpInst = cast<Instruction>(Scalars[Idx]);
    if (IsAltOp(OpInst)) {
      Mask[I] = Sz + Idx;
      if (AltScalars)
        AltScalars->push_back(OpInst);
    } else {
      Mask[I] = Idx;
      if (OpScalars)
        OpScalars->push_back(OpInst);
    }
  }
  if (!ReuseShuffleIndices.empty()) {
    SmallVector<int> NewMask(ReuseShuffleIndices.size(), PoisonMaskElem);
    transform(ReuseShuffleIndices, NewMask.begin(), [&Mask](int Idx) {
      return Idx != PoisonMaskElem ? Mask[Idx] : PoisonMaskElem;
    });
    Mask.swap(NewMask);
  }
}

static bool isAlternateInstruction(const Instruction *I,
                                   const Instruction *MainOp,
                                   const Instruction *AltOp,
                                   const TargetLibraryInfo &TLI) {
  if (auto *MainCI = dyn_cast<CmpInst>(MainOp)) {
    auto *AltCI = cast<CmpInst>(AltOp);
    CmpInst::Predicate MainP = MainCI->getPredicate();
    CmpInst::Predicate AltP = AltCI->getPredicate();
    assert(MainP != AltP && "Expected different main/alternate predicates.");
    auto *CI = cast<CmpInst>(I);
    if (isCmpSameOrSwapped(MainCI, CI, TLI))
      return false;
    if (isCmpSameOrSwapped(AltCI, CI, TLI))
      return true;
    CmpInst::Predicate P = CI->getPredicate();
    CmpInst::Predicate SwappedP = CmpInst::getSwappedPredicate(P);

    assert((MainP == P || AltP == P || MainP == SwappedP || AltP == SwappedP) &&
           "CmpInst expected to match either main or alternate predicate or "
           "their swap.");
    (void)AltP;
    return MainP != P && MainP != SwappedP;
  }
  return I->getOpcode() == AltOp->getOpcode();
}

TTI::OperandValueInfo BoUpSLP::getOperandInfo(ArrayRef<Value *> Ops) {
  assert(!Ops.empty());
  const auto *Op0 = Ops.front();

  const bool IsConstant = all_of(Ops, [](Value *V) {
    // TODO: We should allow undef elements here
    return isConstant(V) && !isa<UndefValue>(V);
  });
  const bool IsUniform = all_of(Ops, [=](Value *V) {
    // TODO: We should allow undef elements here
    return V == Op0;
  });
  const bool IsPowerOfTwo = all_of(Ops, [](Value *V) {
    // TODO: We should allow undef elements here
    if (auto *CI = dyn_cast<ConstantInt>(V))
      return CI->getValue().isPowerOf2();
    return false;
  });
  const bool IsNegatedPowerOfTwo = all_of(Ops, [](Value *V) {
    // TODO: We should allow undef elements here
    if (auto *CI = dyn_cast<ConstantInt>(V))
      return CI->getValue().isNegatedPowerOf2();
    return false;
  });

  TTI::OperandValueKind VK = TTI::OK_AnyValue;
  if (IsConstant && IsUniform)
    VK = TTI::OK_UniformConstantValue;
  else if (IsConstant)
    VK = TTI::OK_NonUniformConstantValue;
  else if (IsUniform)
    VK = TTI::OK_UniformValue;

  TTI::OperandValueProperties VP = TTI::OP_None;
  VP = IsPowerOfTwo ? TTI::OP_PowerOf2 : VP;
  VP = IsNegatedPowerOfTwo ? TTI::OP_NegatedPowerOf2 : VP;

  return {VK, VP};
}

namespace {
/// The base class for shuffle instruction emission and shuffle cost estimation.
class BaseShuffleAnalysis {
protected:
  Type *ScalarTy = nullptr;

  BaseShuffleAnalysis(Type *ScalarTy) : ScalarTy(ScalarTy) {}

  /// V is expected to be a vectorized value.
  /// When REVEC is disabled, there is no difference between VF and
  /// VNumElements.
  /// When REVEC is enabled, VF is VNumElements / ScalarTyNumElements.
  /// e.g., if ScalarTy is <4 x Ty> and V1 is <8 x Ty>, 2 is returned instead
  /// of 8.
  unsigned getVF(Value *V) const {
    assert(V && "V cannot be nullptr");
    assert(isa<FixedVectorType>(V->getType()) &&
           "V does not have FixedVectorType");
    assert(ScalarTy && "ScalarTy cannot be nullptr");
    unsigned ScalarTyNumElements = getNumElements(ScalarTy);
    unsigned VNumElements =
        cast<FixedVectorType>(V->getType())->getNumElements();
    assert(VNumElements > ScalarTyNumElements &&
           "the number of elements of V is not large enough");
    assert(VNumElements % ScalarTyNumElements == 0 &&
           "the number of elements of V is not a vectorized value");
    return VNumElements / ScalarTyNumElements;
  }

  /// Checks if the mask is an identity mask.
  /// \param IsStrict if is true the function returns false if mask size does
  /// not match vector size.
  static bool isIdentityMask(ArrayRef<int> Mask, const FixedVectorType *VecTy,
                             bool IsStrict) {
    int Limit = Mask.size();
    int VF = VecTy->getNumElements();
    int Index = -1;
    if (VF == Limit && ShuffleVectorInst::isIdentityMask(Mask, Limit))
      return true;
    if (!IsStrict) {
      // Consider extract subvector starting from index 0.
      if (ShuffleVectorInst::isExtractSubvectorMask(Mask, VF, Index) &&
          Index == 0)
        return true;
      // All VF-size submasks are identity (e.g.
      // <poison,poison,poison,poison,0,1,2,poison,poison,1,2,3> etc. for VF 4).
      if (Limit % VF == 0 && all_of(seq<int>(0, Limit / VF), [=](int Idx) {
            ArrayRef<int> Slice = Mask.slice(Idx * VF, VF);
            return all_of(Slice, [](int I) { return I == PoisonMaskElem; }) ||
                   ShuffleVectorInst::isIdentityMask(Slice, VF);
          }))
        return true;
    }
    return false;
  }

  /// Tries to combine 2 different masks into single one.
  /// \param LocalVF Vector length of the permuted input vector. \p Mask may
  /// change the size of the vector, \p LocalVF is the original size of the
  /// shuffled vector.
  static void combineMasks(unsigned LocalVF, SmallVectorImpl<int> &Mask,
                           ArrayRef<int> ExtMask) {
    unsigned VF = Mask.size();
    SmallVector<int> NewMask(ExtMask.size(), PoisonMaskElem);
    for (int I = 0, Sz = ExtMask.size(); I < Sz; ++I) {
      if (ExtMask[I] == PoisonMaskElem)
        continue;
      int MaskedIdx = Mask[ExtMask[I] % VF];
      NewMask[I] =
          MaskedIdx == PoisonMaskElem ? PoisonMaskElem : MaskedIdx % LocalVF;
    }
    Mask.swap(NewMask);
  }

  /// Looks through shuffles trying to reduce final number of shuffles in the
  /// code. The function looks through the previously emitted shuffle
  /// instructions and properly mark indices in mask as undef.
  /// For example, given the code
  /// \code
  /// %s1 = shufflevector <2 x ty> %0, poison, <1, 0>
  /// %s2 = shufflevector <2 x ty> %1, poison, <1, 0>
  /// \endcode
  /// and if need to emit shuffle of %s1 and %s2 with mask <1, 0, 3, 2>, it will
  /// look through %s1 and %s2 and select vectors %0 and %1 with mask
  /// <0, 1, 2, 3> for the shuffle.
  /// If 2 operands are of different size, the smallest one will be resized and
  /// the mask recalculated properly.
  /// For example, given the code
  /// \code
  /// %s1 = shufflevector <2 x ty> %0, poison, <1, 0, 1, 0>
  /// %s2 = shufflevector <2 x ty> %1, poison, <1, 0, 1, 0>
  /// \endcode
  /// and if need to emit shuffle of %s1 and %s2 with mask <1, 0, 5, 4>, it will
  /// look through %s1 and %s2 and select vectors %0 and %1 with mask
  /// <0, 1, 2, 3> for the shuffle.
  /// So, it tries to transform permutations to simple vector merge, if
  /// possible.
  /// \param V The input vector which must be shuffled using the given \p Mask.
  /// If the better candidate is found, \p V is set to this best candidate
  /// vector.
  /// \param Mask The input mask for the shuffle. If the best candidate is found
  /// during looking-through-shuffles attempt, it is updated accordingly.
  /// \param SinglePermute true if the shuffle operation is originally a
  /// single-value-permutation. In this case the look-through-shuffles procedure
  /// may look for resizing shuffles as the best candidates.
  /// \return true if the shuffle results in the non-resizing identity shuffle
  /// (and thus can be ignored), false - otherwise.
  static bool peekThroughShuffles(Value *&V, SmallVectorImpl<int> &Mask,
                                  bool SinglePermute) {
    Value *Op = V;
    ShuffleVectorInst *IdentityOp = nullptr;
    SmallVector<int> IdentityMask;
    while (auto *SV = dyn_cast<ShuffleVectorInst>(Op)) {
      // Exit if not a fixed vector type or changing size shuffle.
      auto *SVTy = dyn_cast<FixedVectorType>(SV->getType());
      if (!SVTy)
        break;
      // Remember the identity or broadcast mask, if it is not a resizing
      // shuffle. If no better candidates are found, this Op and Mask will be
      // used in the final shuffle.
      if (isIdentityMask(Mask, SVTy, /*IsStrict=*/false)) {
        if (!IdentityOp || !SinglePermute ||
            (isIdentityMask(Mask, SVTy, /*IsStrict=*/true) &&
             !ShuffleVectorInst::isZeroEltSplatMask(IdentityMask,
                                                    IdentityMask.size()))) {
          IdentityOp = SV;
          // Store current mask in the IdentityMask so later we did not lost
          // this info if IdentityOp is selected as the best candidate for the
          // permutation.
          IdentityMask.assign(Mask);
        }
      }
      // Remember the broadcast mask. If no better candidates are found, this Op
      // and Mask will be used in the final shuffle.
      // Zero splat can be used as identity too, since it might be used with
      // mask <0, 1, 2, ...>, i.e. identity mask without extra reshuffling.
      // E.g. if need to shuffle the vector with the mask <3, 1, 2, 0>, which is
      // expensive, the analysis founds out, that the source vector is just a
      // broadcast, this original mask can be transformed to identity mask <0,
      // 1, 2, 3>.
      // \code
      // %0 = shuffle %v, poison, zeroinitalizer
      // %res = shuffle %0, poison, <3, 1, 2, 0>
      // \endcode
      // may be transformed to
      // \code
      // %0 = shuffle %v, poison, zeroinitalizer
      // %res = shuffle %0, poison, <0, 1, 2, 3>
      // \endcode
      if (SV->isZeroEltSplat()) {
        IdentityOp = SV;
        IdentityMask.assign(Mask);
      }
      int LocalVF = Mask.size();
      if (auto *SVOpTy =
              dyn_cast<FixedVectorType>(SV->getOperand(0)->getType()))
        LocalVF = SVOpTy->getNumElements();
      SmallVector<int> ExtMask(Mask.size(), PoisonMaskElem);
      for (auto [Idx, I] : enumerate(Mask)) {
        if (I == PoisonMaskElem ||
            static_cast<unsigned>(I) >= SV->getShuffleMask().size())
          continue;
        ExtMask[Idx] = SV->getMaskValue(I);
      }
      bool IsOp1Undef =
          isUndefVector(SV->getOperand(0),
                        buildUseMask(LocalVF, ExtMask, UseMask::FirstArg))
              .all();
      bool IsOp2Undef =
          isUndefVector(SV->getOperand(1),
                        buildUseMask(LocalVF, ExtMask, UseMask::SecondArg))
              .all();
      if (!IsOp1Undef && !IsOp2Undef) {
        // Update mask and mark undef elems.
        for (int &I : Mask) {
          if (I == PoisonMaskElem)
            continue;
          if (SV->getMaskValue(I % SV->getShuffleMask().size()) ==
              PoisonMaskElem)
            I = PoisonMaskElem;
        }
        break;
      }
      SmallVector<int> ShuffleMask(SV->getShuffleMask());
      combineMasks(LocalVF, ShuffleMask, Mask);
      Mask.swap(ShuffleMask);
      if (IsOp2Undef)
        Op = SV->getOperand(0);
      else
        Op = SV->getOperand(1);
    }
    if (auto *OpTy = dyn_cast<FixedVectorType>(Op->getType());
        !OpTy || !isIdentityMask(Mask, OpTy, SinglePermute) ||
        ShuffleVectorInst::isZeroEltSplatMask(Mask, Mask.size())) {
      if (IdentityOp) {
        V = IdentityOp;
        assert(Mask.size() == IdentityMask.size() &&
               "Expected masks of same sizes.");
        // Clear known poison elements.
        for (auto [I, Idx] : enumerate(Mask))
          if (Idx == PoisonMaskElem)
            IdentityMask[I] = PoisonMaskElem;
        Mask.swap(IdentityMask);
        auto *Shuffle = dyn_cast<ShuffleVectorInst>(V);
        return SinglePermute &&
               (isIdentityMask(Mask, cast<FixedVectorType>(V->getType()),
                               /*IsStrict=*/true) ||
                (Shuffle && Mask.size() == Shuffle->getShuffleMask().size() &&
                 Shuffle->isZeroEltSplat() &&
                 ShuffleVectorInst::isZeroEltSplatMask(Mask, Mask.size())));
      }
      V = Op;
      return false;
    }
    V = Op;
    return true;
  }

  /// Smart shuffle instruction emission, walks through shuffles trees and
  /// tries to find the best matching vector for the actual shuffle
  /// instruction.
  template <typename T, typename ShuffleBuilderTy>
  static T createShuffle(Value *V1, Value *V2, ArrayRef<int> Mask,
                         ShuffleBuilderTy &Builder) {
    assert(V1 && "Expected at least one vector value.");
    if (V2)
      Builder.resizeToMatch(V1, V2);
    int VF = Mask.size();
    if (auto *FTy = dyn_cast<FixedVectorType>(V1->getType()))
      VF = FTy->getNumElements();
    if (V2 &&
        !isUndefVector(V2, buildUseMask(VF, Mask, UseMask::SecondArg)).all()) {
      // Peek through shuffles.
      Value *Op1 = V1;
      Value *Op2 = V2;
      int VF =
          cast<VectorType>(V1->getType())->getElementCount().getKnownMinValue();
      SmallVector<int> CombinedMask1(Mask.size(), PoisonMaskElem);
      SmallVector<int> CombinedMask2(Mask.size(), PoisonMaskElem);
      for (int I = 0, E = Mask.size(); I < E; ++I) {
        if (Mask[I] < VF)
          CombinedMask1[I] = Mask[I];
        else
          CombinedMask2[I] = Mask[I] - VF;
      }
      Value *PrevOp1;
      Value *PrevOp2;
      do {
        PrevOp1 = Op1;
        PrevOp2 = Op2;
        (void)peekThroughShuffles(Op1, CombinedMask1, /*SinglePermute=*/false);
        (void)peekThroughShuffles(Op2, CombinedMask2, /*SinglePermute=*/false);
        // Check if we have 2 resizing shuffles - need to peek through operands
        // again.
        if (auto *SV1 = dyn_cast<ShuffleVectorInst>(Op1))
          if (auto *SV2 = dyn_cast<ShuffleVectorInst>(Op2)) {
            SmallVector<int> ExtMask1(Mask.size(), PoisonMaskElem);
            for (auto [Idx, I] : enumerate(CombinedMask1)) {
                if (I == PoisonMaskElem)
                continue;
                ExtMask1[Idx] = SV1->getMaskValue(I);
            }
            SmallBitVector UseMask1 = buildUseMask(
                cast<FixedVectorType>(SV1->getOperand(1)->getType())
                    ->getNumElements(),
                ExtMask1, UseMask::SecondArg);
            SmallVector<int> ExtMask2(CombinedMask2.size(), PoisonMaskElem);
            for (auto [Idx, I] : enumerate(CombinedMask2)) {
                if (I == PoisonMaskElem)
                continue;
                ExtMask2[Idx] = SV2->getMaskValue(I);
            }
            SmallBitVector UseMask2 = buildUseMask(
                cast<FixedVectorType>(SV2->getOperand(1)->getType())
                    ->getNumElements(),
                ExtMask2, UseMask::SecondArg);
            if (SV1->getOperand(0)->getType() ==
                    SV2->getOperand(0)->getType() &&
                SV1->getOperand(0)->getType() != SV1->getType() &&
                isUndefVector(SV1->getOperand(1), UseMask1).all() &&
                isUndefVector(SV2->getOperand(1), UseMask2).all()) {
              Op1 = SV1->getOperand(0);
              Op2 = SV2->getOperand(0);
              SmallVector<int> ShuffleMask1(SV1->getShuffleMask());
              int LocalVF = ShuffleMask1.size();
              if (auto *FTy = dyn_cast<FixedVectorType>(Op1->getType()))
                LocalVF = FTy->getNumElements();
              combineMasks(LocalVF, ShuffleMask1, CombinedMask1);
              CombinedMask1.swap(ShuffleMask1);
              SmallVector<int> ShuffleMask2(SV2->getShuffleMask());
              LocalVF = ShuffleMask2.size();
              if (auto *FTy = dyn_cast<FixedVectorType>(Op2->getType()))
                LocalVF = FTy->getNumElements();
              combineMasks(LocalVF, ShuffleMask2, CombinedMask2);
              CombinedMask2.swap(ShuffleMask2);
            }
          }
      } while (PrevOp1 != Op1 || PrevOp2 != Op2);
      Builder.resizeToMatch(Op1, Op2);
      VF = std::max(cast<VectorType>(Op1->getType())
                        ->getElementCount()
                        .getKnownMinValue(),
                    cast<VectorType>(Op2->getType())
                        ->getElementCount()
                        .getKnownMinValue());
      for (int I = 0, E = Mask.size(); I < E; ++I) {
        if (CombinedMask2[I] != PoisonMaskElem) {
          assert(CombinedMask1[I] == PoisonMaskElem &&
                 "Expected undefined mask element");
          CombinedMask1[I] = CombinedMask2[I] + (Op1 == Op2 ? 0 : VF);
        }
      }
      if (Op1 == Op2 &&
          (ShuffleVectorInst::isIdentityMask(CombinedMask1, VF) ||
           (ShuffleVectorInst::isZeroEltSplatMask(CombinedMask1, VF) &&
            isa<ShuffleVectorInst>(Op1) &&
            cast<ShuffleVectorInst>(Op1)->getShuffleMask() ==
                ArrayRef(CombinedMask1))))
        return Builder.createIdentity(Op1);
      return Builder.createShuffleVector(
          Op1, Op1 == Op2 ? PoisonValue::get(Op1->getType()) : Op2,
          CombinedMask1);
    }
    if (isa<PoisonValue>(V1))
      return Builder.createPoison(
          cast<VectorType>(V1->getType())->getElementType(), Mask.size());
    SmallVector<int> NewMask(Mask);
    bool IsIdentity = peekThroughShuffles(V1, NewMask, /*SinglePermute=*/true);
    assert(V1 && "Expected non-null value after looking through shuffles.");

    if (!IsIdentity)
      return Builder.createShuffleVector(V1, NewMask);
    return Builder.createIdentity(V1);
  }
};
} // namespace

/// Calculate the scalar and the vector costs from vectorizing set of GEPs.
static std::pair<InstructionCost, InstructionCost>
getGEPCosts(const TargetTransformInfo &TTI, ArrayRef<Value *> Ptrs,
            Value *BasePtr, unsigned Opcode, TTI::TargetCostKind CostKind,
            Type *ScalarTy, VectorType *VecTy) {
  InstructionCost ScalarCost = 0;
  InstructionCost VecCost = 0;
  // Here we differentiate two cases: (1) when Ptrs represent a regular
  // vectorization tree node (as they are pointer arguments of scattered
  // loads) or (2) when Ptrs are the arguments of loads or stores being
  // vectorized as plane wide unit-stride load/store since all the
  // loads/stores are known to be from/to adjacent locations.
  if (Opcode == Instruction::Load || Opcode == Instruction::Store) {
    // Case 2: estimate costs for pointer related costs when vectorizing to
    // a wide load/store.
    // Scalar cost is estimated as a set of pointers with known relationship
    // between them.
    // For vector code we will use BasePtr as argument for the wide load/store
    // but we also need to account all the instructions which are going to
    // stay in vectorized code due to uses outside of these scalar
    // loads/stores.
    ScalarCost = TTI.getPointersChainCost(
        Ptrs, BasePtr, TTI::PointersChainInfo::getUnitStride(), ScalarTy,
        CostKind);

    SmallVector<const Value *> PtrsRetainedInVecCode;
    for (Value *V : Ptrs) {
      if (V == BasePtr) {
        PtrsRetainedInVecCode.push_back(V);
        continue;
      }
      auto *Ptr = dyn_cast<GetElementPtrInst>(V);
      // For simplicity assume Ptr to stay in vectorized code if it's not a
      // GEP instruction. We don't care since it's cost considered free.
      // TODO: We should check for any uses outside of vectorizable tree
      // rather than just single use.
      if (!Ptr || !Ptr->hasOneUse())
        PtrsRetainedInVecCode.push_back(V);
    }

    if (PtrsRetainedInVecCode.size() == Ptrs.size()) {
      // If all pointers stay in vectorized code then we don't have
      // any savings on that.
      return std::make_pair(TTI::TCC_Free, TTI::TCC_Free);
    }
    VecCost = TTI.getPointersChainCost(PtrsRetainedInVecCode, BasePtr,
                                       TTI::PointersChainInfo::getKnownStride(),
                                       VecTy, CostKind);
  } else {
    // Case 1: Ptrs are the arguments of loads that we are going to transform
    // into masked gather load intrinsic.
    // All the scalar GEPs will be removed as a result of vectorization.
    // For any external uses of some lanes extract element instructions will
    // be generated (which cost is estimated separately).
    TTI::PointersChainInfo PtrsInfo =
        all_of(Ptrs,
               [](const Value *V) {
                 auto *Ptr = dyn_cast<GetElementPtrInst>(V);
                 return Ptr && !Ptr->hasAllConstantIndices();
               })
            ? TTI::PointersChainInfo::getUnknownStride()
            : TTI::PointersChainInfo::getKnownStride();

    ScalarCost =
        TTI.getPointersChainCost(Ptrs, BasePtr, PtrsInfo, ScalarTy, CostKind);
    auto *BaseGEP = dyn_cast<GEPOperator>(BasePtr);
    if (!BaseGEP) {
      auto *It = find_if(Ptrs, IsaPred<GEPOperator>);
      if (It != Ptrs.end())
        BaseGEP = cast<GEPOperator>(*It);
    }
    if (BaseGEP) {
      SmallVector<const Value *> Indices(BaseGEP->indices());
      VecCost = TTI.getGEPCost(BaseGEP->getSourceElementType(),
                               BaseGEP->getPointerOperand(), Indices, VecTy,
                               CostKind);
    }
  }

  return std::make_pair(ScalarCost, VecCost);
}

void BoUpSLP::transformNodes() {
  constexpr TTI::TargetCostKind CostKind = TTI::TCK_RecipThroughput;
  // The tree may grow here, so iterate over nodes, built before.
  for (unsigned Idx : seq<unsigned>(VectorizableTree.size())) {
    TreeEntry &E = *VectorizableTree[Idx];
    if (E.isGather()) {
      ArrayRef<Value *> VL = E.Scalars;
      const unsigned Sz = getVectorElementSize(VL.front());
      unsigned MinVF = getMinVF(2 * Sz);
      if (VL.size() <= 2 ||
          (E.getOpcode() &&
           (E.isAltShuffle() || E.getOpcode() != Instruction::Load)))
        continue;
      // Try to find vectorizable sequences and transform them into a series of
      // insertvector instructions.
      unsigned StartIdx = 0;
      unsigned End = VL.size();
      for (unsigned VF = VL.size() / 2; VF >= MinVF; VF /= 2) {
        for (unsigned Cnt = StartIdx; Cnt + VF <= End; Cnt += VF) {
          ArrayRef<Value *> Slice = VL.slice(Cnt, VF);
          // If any instruction is vectorized already - do not try again.
          if (getTreeEntry(Slice.front()) || getTreeEntry(Slice.back()))
            continue;
          InstructionsState S = getSameOpcode(Slice, *TLI);
          if (!S.getOpcode() || S.isAltShuffle() ||
              (S.getOpcode() != Instruction::Load &&
               any_of(Slice, [&](Value *V) {
                 return !areAllUsersVectorized(cast<Instruction>(V),
                                               UserIgnoreList);
               })))
            continue;
          unsigned PrevSize = VectorizableTree.size();
          buildTree_rec(Slice, 0, EdgeInfo(&E, UINT_MAX));
          if (PrevSize + 1 == VectorizableTree.size() &&
              VectorizableTree[PrevSize]->isGather()) {
            VectorizableTree.pop_back();
            continue;
          }
          E.CombinedEntriesWithIndices.emplace_back(PrevSize, Cnt);
          if (StartIdx == Cnt)
            StartIdx = Cnt + VF;
          if (End == Cnt + VF)
            End = Cnt;
        }
      }
    }
    switch (E.getOpcode()) {
    case Instruction::Load: {
      // No need to reorder masked gather loads, just reorder the scalar
      // operands.
      if (E.State != TreeEntry::Vectorize)
        break;
      Type *ScalarTy = E.getMainOp()->getType();
      auto *VecTy = getWidenedType(ScalarTy, E.Scalars.size());
      Align CommonAlignment = computeCommonAlignment<LoadInst>(E.Scalars);
      // Check if profitable to represent consecutive load + reverse as strided
      // load with stride -1.
      if (isReverseOrder(E.ReorderIndices) &&
          TTI->isLegalStridedLoadStore(VecTy, CommonAlignment)) {
        SmallVector<int> Mask;
        inversePermutation(E.ReorderIndices, Mask);
        auto *BaseLI = cast<LoadInst>(E.Scalars.back());
        InstructionCost OriginalVecCost =
            TTI->getMemoryOpCost(Instruction::Load, VecTy, BaseLI->getAlign(),
                                 BaseLI->getPointerAddressSpace(), CostKind,
                                 TTI::OperandValueInfo()) +
            ::getShuffleCost(*TTI, TTI::SK_Reverse, VecTy, Mask, CostKind);
        InstructionCost StridedCost = TTI->getStridedMemoryOpCost(
            Instruction::Load, VecTy, BaseLI->getPointerOperand(),
            /*VariableMask=*/false, CommonAlignment, CostKind, BaseLI);
        if (StridedCost < OriginalVecCost)
          // Strided load is more profitable than consecutive load + reverse -
          // transform the node to strided load.
          E.State = TreeEntry::StridedVectorize;
      }
      break;
    }
    case Instruction::Store: {
      Type *ScalarTy =
          cast<StoreInst>(E.getMainOp())->getValueOperand()->getType();
      auto *VecTy = getWidenedType(ScalarTy, E.Scalars.size());
      Align CommonAlignment = computeCommonAlignment<StoreInst>(E.Scalars);
      // Check if profitable to represent consecutive load + reverse as strided
      // load with stride -1.
      if (isReverseOrder(E.ReorderIndices) &&
          TTI->isLegalStridedLoadStore(VecTy, CommonAlignment)) {
        SmallVector<int> Mask;
        inversePermutation(E.ReorderIndices, Mask);
        auto *BaseSI = cast<StoreInst>(E.Scalars.back());
        InstructionCost OriginalVecCost =
            TTI->getMemoryOpCost(Instruction::Store, VecTy, BaseSI->getAlign(),
                                 BaseSI->getPointerAddressSpace(), CostKind,
                                 TTI::OperandValueInfo()) +
            ::getShuffleCost(*TTI, TTI::SK_Reverse, VecTy, Mask, CostKind);
        InstructionCost StridedCost = TTI->getStridedMemoryOpCost(
            Instruction::Store, VecTy, BaseSI->getPointerOperand(),
            /*VariableMask=*/false, CommonAlignment, CostKind, BaseSI);
        if (StridedCost < OriginalVecCost)
          // Strided store is more profitable than reverse + consecutive store -
          // transform the node to strided store.
          E.State = TreeEntry::StridedVectorize;
      }
      break;
    }
    case Instruction::Select: {
      if (E.State != TreeEntry::Vectorize)
        break;
      auto [MinMaxID, SelectOnly] = canConvertToMinOrMaxIntrinsic(E.Scalars);
      if (MinMaxID == Intrinsic::not_intrinsic)
        break;
      // This node is a minmax node.
      E.CombinedOp = TreeEntry::MinMax;
      TreeEntry *CondEntry = const_cast<TreeEntry *>(getOperandEntry(&E, 0));
      if (SelectOnly && CondEntry->UserTreeIndices.size() == 1 &&
          CondEntry->State == TreeEntry::Vectorize) {
        // The condition node is part of the combined minmax node.
        CondEntry->State = TreeEntry::CombinedVectorize;
      }
      break;
    }
    default:
      break;
    }
  }

  // Single load node - exit.
  if (VectorizableTree.size() <= 1 &&
      VectorizableTree.front()->getOpcode() == Instruction::Load)
    return;
  // Small graph with small VF - exit.
  constexpr unsigned SmallTree = 3;
  constexpr unsigned SmallVF = 2;
  if ((VectorizableTree.size() <= SmallTree &&
       VectorizableTree.front()->Scalars.size() == SmallVF) ||
      (VectorizableTree.size() <= 2 && UserIgnoreList))
    return;

  // A list of loads to be gathered during the vectorization process. We can
  // try to vectorize them at the end, if profitable.
  SmallVector<SmallVector<std::pair<LoadInst *, int>>> GatheredLoads;

  for (std::unique_ptr<TreeEntry> &TE : VectorizableTree) {
    TreeEntry &E = *TE;
    if (E.isGather() &&
        (E.getOpcode() == Instruction::Load ||
         (!E.getOpcode() && any_of(E.Scalars,
                                   [&](Value *V) {
                                     return isa<LoadInst>(V) &&
                                            !isVectorized(V) &&
                                            !isDeleted(cast<Instruction>(V));
                                   }))) &&
        !isSplat(E.Scalars))
      gatherPossiblyVectorizableLoads(*this, E.Scalars, *DL, *SE, *TTI,
                                      GatheredLoads);
  }
  // Try to vectorize gathered loads if this is not just a gather of loads.
  if (!GatheredLoads.empty())
    tryToVectorizeGatheredLoads(GatheredLoads);
}

/// Merges shuffle masks and emits final shuffle instruction, if required. It
/// supports shuffling of 2 input vectors. It implements lazy shuffles emission,
/// when the actual shuffle instruction is generated only if this is actually
/// required. Otherwise, the shuffle instruction emission is delayed till the
/// end of the process, to reduce the number of emitted instructions and further
/// analysis/transformations.
class BoUpSLP::ShuffleCostEstimator : public BaseShuffleAnalysis {
  bool IsFinalized = false;
  SmallVector<int> CommonMask;
  SmallVector<PointerUnion<Value *, const TreeEntry *>, 2> InVectors;
  const TargetTransformInfo &TTI;
  InstructionCost Cost = 0;
  SmallDenseSet<Value *> VectorizedVals;
  BoUpSLP &R;
  SmallPtrSetImpl<Value *> &CheckedExtracts;
  constexpr static TTI::TargetCostKind CostKind = TTI::TCK_RecipThroughput;
  /// While set, still trying to estimate the cost for the same nodes and we
  /// can delay actual cost estimation (virtual shuffle instruction emission).
  /// May help better estimate the cost if same nodes must be permuted + allows
  /// to move most of the long shuffles cost estimation to TTI.
  bool SameNodesEstimated = true;

  static Constant *getAllOnesValue(const DataLayout &DL, Type *Ty) {
    if (Ty->getScalarType()->isPointerTy()) {
      Constant *Res = ConstantExpr::getIntToPtr(
          ConstantInt::getAllOnesValue(
              IntegerType::get(Ty->getContext(),
                               DL.getTypeStoreSizeInBits(Ty->getScalarType()))),
          Ty->getScalarType());
      if (auto *VTy = dyn_cast<VectorType>(Ty))
        Res = ConstantVector::getSplat(VTy->getElementCount(), Res);
      return Res;
    }
    return Constant::getAllOnesValue(Ty);
  }

  InstructionCost getBuildVectorCost(ArrayRef<Value *> VL, Value *Root) {
    if ((!Root && allConstant(VL)) || all_of(VL, IsaPred<UndefValue>))
      return TTI::TCC_Free;
    auto *VecTy = getWidenedType(ScalarTy, VL.size());
    InstructionCost GatherCost = 0;
    SmallVector<Value *> Gathers(VL);
    if (!Root && isSplat(VL)) {
      // Found the broadcasting of the single scalar, calculate the cost as
      // the broadcast.
      const auto *It = find_if_not(VL, IsaPred<UndefValue>);
      assert(It != VL.end() && "Expected at least one non-undef value.");
      // Add broadcast for non-identity shuffle only.
      bool NeedShuffle =
          count(VL, *It) > 1 &&
          (VL.front() != *It || !all_of(VL.drop_front(), IsaPred<UndefValue>));
      if (!NeedShuffle)
        return TTI.getVectorInstrCost(Instruction::InsertElement, VecTy,
                                      CostKind, std::distance(VL.begin(), It),
                                      PoisonValue::get(VecTy), *It);

      SmallVector<int> ShuffleMask(VL.size(), PoisonMaskElem);
      transform(VL, ShuffleMask.begin(), [](Value *V) {
        return isa<PoisonValue>(V) ? PoisonMaskElem : 0;
      });
      InstructionCost InsertCost =
          TTI.getVectorInstrCost(Instruction::InsertElement, VecTy, CostKind, 0,
                                 PoisonValue::get(VecTy), *It);
      return InsertCost + ::getShuffleCost(TTI,
                                           TargetTransformInfo::SK_Broadcast,
                                           VecTy, ShuffleMask, CostKind,
                                           /*Index=*/0, /*SubTp=*/nullptr,
                                           /*Args=*/*It);
    }
    return GatherCost +
           (all_of(Gathers, IsaPred<UndefValue>)
                ? TTI::TCC_Free
                : R.getGatherCost(Gathers, !Root && VL.equals(Gathers),
                                  ScalarTy));
  };

  /// Compute the cost of creating a vector containing the extracted values from
  /// \p VL.
  InstructionCost
  computeExtractCost(ArrayRef<Value *> VL, ArrayRef<int> Mask,
                     ArrayRef<std::optional<TTI::ShuffleKind>> ShuffleKinds,
                     unsigned NumParts) {
    assert(VL.size() > NumParts && "Unexpected scalarized shuffle.");
    unsigned NumElts =
        std::accumulate(VL.begin(), VL.end(), 0, [](unsigned Sz, Value *V) {
          auto *EE = dyn_cast<ExtractElementInst>(V);
          if (!EE)
            return Sz;
          auto *VecTy = dyn_cast<FixedVectorType>(EE->getVectorOperandType());
          if (!VecTy)
            return Sz;
          return std::max(Sz, VecTy->getNumElements());
        });
    // FIXME: this must be moved to TTI for better estimation.
    unsigned EltsPerVector = getPartNumElems(VL.size(), NumParts);
    auto CheckPerRegistersShuffle = [&](MutableArrayRef<int> Mask,
                                        SmallVectorImpl<unsigned> &Indices)
        -> std::optional<TTI::ShuffleKind> {
      if (NumElts <= EltsPerVector)
        return std::nullopt;
      int OffsetReg0 =
          alignDown(std::accumulate(Mask.begin(), Mask.end(), INT_MAX,
                                    [](int S, int I) {
                                      if (I == PoisonMaskElem)
                                        return S;
                                      return std::min(S, I);
                                    }),
                    EltsPerVector);
      int OffsetReg1 = OffsetReg0;
      DenseSet<int> RegIndices;
      // Check that if trying to permute same single/2 input vectors.
      TTI::ShuffleKind ShuffleKind = TTI::SK_PermuteSingleSrc;
      int FirstRegId = -1;
      Indices.assign(1, OffsetReg0);
      for (auto [Pos, I] : enumerate(Mask)) {
        if (I == PoisonMaskElem)
          continue;
        int Idx = I - OffsetReg0;
        int RegId =
            (Idx / NumElts) * NumParts + (Idx % NumElts) / EltsPerVector;
        if (FirstRegId < 0)
          FirstRegId = RegId;
        RegIndices.insert(RegId);
        if (RegIndices.size() > 2)
          return std::nullopt;
        if (RegIndices.size() == 2) {
          ShuffleKind = TTI::SK_PermuteTwoSrc;
          if (Indices.size() == 1) {
            OffsetReg1 = alignDown(
                std::accumulate(
                    std::next(Mask.begin(), Pos), Mask.end(), INT_MAX,
                    [&](int S, int I) {
                      if (I == PoisonMaskElem)
                        return S;
                      int RegId = ((I - OffsetReg0) / NumElts) * NumParts +
                                  ((I - OffsetReg0) % NumElts) / EltsPerVector;
                      if (RegId == FirstRegId)
                        return S;
                      return std::min(S, I);
                    }),
                EltsPerVector);
            Indices.push_back(OffsetReg1 % NumElts);
          }
          Idx = I - OffsetReg1;
        }
        I = (Idx % NumElts) % EltsPerVector +
            (RegId == FirstRegId ? 0 : EltsPerVector);
      }
      return ShuffleKind;
    };
    InstructionCost Cost = 0;

    // Process extracts in blocks of EltsPerVector to check if the source vector
    // operand can be re-used directly. If not, add the cost of creating a
    // shuffle to extract the values into a vector register.
    for (unsigned Part : seq<unsigned>(NumParts)) {
      if (!ShuffleKinds[Part])
        continue;
      ArrayRef<int> MaskSlice = Mask.slice(
          Part * EltsPerVector, getNumElems(Mask.size(), EltsPerVector, Part));
      SmallVector<int> SubMask(EltsPerVector, PoisonMaskElem);
      copy(MaskSlice, SubMask.begin());
      SmallVector<unsigned, 2> Indices;
      std::optional<TTI::ShuffleKind> RegShuffleKind =
          CheckPerRegistersShuffle(SubMask, Indices);
      if (!RegShuffleKind) {
        if (*ShuffleKinds[Part] != TTI::SK_PermuteSingleSrc ||
            !ShuffleVectorInst::isIdentityMask(
                MaskSlice, std::max<unsigned>(NumElts, MaskSlice.size())))
          Cost +=
              ::getShuffleCost(TTI, *ShuffleKinds[Part],
                               getWidenedType(ScalarTy, NumElts), MaskSlice);
        continue;
      }
      if (*RegShuffleKind != TTI::SK_PermuteSingleSrc ||
          !ShuffleVectorInst::isIdentityMask(SubMask, EltsPerVector)) {
        Cost +=
            ::getShuffleCost(TTI, *RegShuffleKind,
                             getWidenedType(ScalarTy, EltsPerVector), SubMask);
      }
      for (unsigned Idx : Indices) {
        assert((Idx + EltsPerVector) <= alignTo(NumElts, EltsPerVector) &&
               "SK_ExtractSubvector index out of range");
        Cost += ::getShuffleCost(
            TTI, TTI::SK_ExtractSubvector,
            getWidenedType(ScalarTy, alignTo(NumElts, EltsPerVector)), {},
            CostKind, Idx, getWidenedType(ScalarTy, EltsPerVector));
      }
      // Second attempt to check, if just a permute is better estimated than
      // subvector extract.
      SubMask.assign(NumElts, PoisonMaskElem);
      copy(MaskSlice, SubMask.begin());
      InstructionCost OriginalCost = ::getShuffleCost(
          TTI, *ShuffleKinds[Part], getWidenedType(ScalarTy, NumElts), SubMask);
      if (OriginalCost < Cost)
        Cost = OriginalCost;
    }
    return Cost;
  }
  /// Transforms mask \p CommonMask per given \p Mask to make proper set after
  /// shuffle emission.
  static void transformMaskAfterShuffle(MutableArrayRef<int> CommonMask,
                                        ArrayRef<int> Mask) {
    for (unsigned Idx = 0, Sz = CommonMask.size(); Idx < Sz; ++Idx)
      if (Mask[Idx] != PoisonMaskElem)
        CommonMask[Idx] = Idx;
  }
  /// Adds the cost of reshuffling \p E1 and \p E2 (if present), using given
  /// mask \p Mask, register number \p Part, that includes \p SliceSize
  /// elements.
  void estimateNodesPermuteCost(const TreeEntry &E1, const TreeEntry *E2,
                                ArrayRef<int> Mask, unsigned Part,
                                unsigned SliceSize) {
    if (SameNodesEstimated) {
      // Delay the cost estimation if the same nodes are reshuffling.
      // If we already requested the cost of reshuffling of E1 and E2 before, no
      // need to estimate another cost with the sub-Mask, instead include this
      // sub-Mask into the CommonMask to estimate it later and avoid double cost
      // estimation.
      if ((InVectors.size() == 2 &&
           InVectors.front().get<const TreeEntry *>() == &E1 &&
           InVectors.back().get<const TreeEntry *>() == E2) ||
          (!E2 && InVectors.front().get<const TreeEntry *>() == &E1)) {
        unsigned Limit = getNumElems(Mask.size(), SliceSize, Part);
        assert(all_of(ArrayRef(CommonMask).slice(Part * SliceSize, Limit),
                      [](int Idx) { return Idx == PoisonMaskElem; }) &&
               "Expected all poisoned elements.");
        ArrayRef<int> SubMask = ArrayRef(Mask).slice(Part * SliceSize, Limit);
        copy(SubMask, std::next(CommonMask.begin(), SliceSize * Part));
        return;
      }
      // Found non-matching nodes - need to estimate the cost for the matched
      // and transform mask.
      Cost += createShuffle(InVectors.front(),
                            InVectors.size() == 1 ? nullptr : InVectors.back(),
                            CommonMask);
      transformMaskAfterShuffle(CommonMask, CommonMask);
    }
    SameNodesEstimated = false;
    if (!E2 && InVectors.size() == 1) {
      unsigned VF = E1.getVectorFactor();
      if (Value *V1 = InVectors.front().dyn_cast<Value *>()) {
        VF = std::max(VF,
                      cast<FixedVectorType>(V1->getType())->getNumElements());
      } else {
        const auto *E = InVectors.front().get<const TreeEntry *>();
        VF = std::max(VF, E->getVectorFactor());
      }
      for (unsigned Idx = 0, Sz = CommonMask.size(); Idx < Sz; ++Idx)
        if (Mask[Idx] != PoisonMaskElem && CommonMask[Idx] == PoisonMaskElem)
          CommonMask[Idx] = Mask[Idx] + VF;
      Cost += createShuffle(InVectors.front(), &E1, CommonMask);
      transformMaskAfterShuffle(CommonMask, CommonMask);
    } else {
      Cost += createShuffle(&E1, E2, Mask);
      transformMaskAfterShuffle(CommonMask, Mask);
    }
  }

  class ShuffleCostBuilder {
    const TargetTransformInfo &TTI;

    static bool isEmptyOrIdentity(ArrayRef<int> Mask, unsigned VF) {
      int Index = -1;
      return Mask.empty() ||
             (VF == Mask.size() &&
              ShuffleVectorInst::isIdentityMask(Mask, VF)) ||
             (ShuffleVectorInst::isExtractSubvectorMask(Mask, VF, Index) &&
              Index == 0);
    }

  public:
    ShuffleCostBuilder(const TargetTransformInfo &TTI) : TTI(TTI) {}
    ~ShuffleCostBuilder() = default;
    InstructionCost createShuffleVector(Value *V1, Value *,
                                        ArrayRef<int> Mask) const {
      // Empty mask or identity mask are free.
      unsigned VF =
          cast<VectorType>(V1->getType())->getElementCount().getKnownMinValue();
      if (isEmptyOrIdentity(Mask, VF))
        return TTI::TCC_Free;
      return ::getShuffleCost(TTI, TTI::SK_PermuteTwoSrc,
                              cast<VectorType>(V1->getType()), Mask);
    }
    InstructionCost createShuffleVector(Value *V1, ArrayRef<int> Mask) const {
      // Empty mask or identity mask are free.
      unsigned VF =
          cast<VectorType>(V1->getType())->getElementCount().getKnownMinValue();
      if (isEmptyOrIdentity(Mask, VF))
        return TTI::TCC_Free;
      return ::getShuffleCost(TTI, TTI::SK_PermuteSingleSrc,
                              cast<VectorType>(V1->getType()), Mask);
    }
    InstructionCost createIdentity(Value *) const { return TTI::TCC_Free; }
    InstructionCost createPoison(Type *Ty, unsigned VF) const {
      return TTI::TCC_Free;
    }
    void resizeToMatch(Value *&, Value *&) const {}
  };

  /// Smart shuffle instruction emission, walks through shuffles trees and
  /// tries to find the best matching vector for the actual shuffle
  /// instruction.
  InstructionCost
  createShuffle(const PointerUnion<Value *, const TreeEntry *> &P1,
                const PointerUnion<Value *, const TreeEntry *> &P2,
                ArrayRef<int> Mask) {
    ShuffleCostBuilder Builder(TTI);
    SmallVector<int> CommonMask(Mask);
    Value *V1 = P1.dyn_cast<Value *>(), *V2 = P2.dyn_cast<Value *>();
    unsigned CommonVF = Mask.size();
    InstructionCost ExtraCost = 0;
    auto GetNodeMinBWAffectedCost = [&](const TreeEntry &E,
                                        unsigned VF) -> InstructionCost {
      if (E.isGather() && allConstant(E.Scalars))
        return TTI::TCC_Free;
      Type *EScalarTy = E.Scalars.front()->getType();
      bool IsSigned = true;
      if (auto It = R.MinBWs.find(&E); It != R.MinBWs.end()) {
        EScalarTy = IntegerType::get(EScalarTy->getContext(), It->second.first);
        IsSigned = It->second.second;
      }
      if (EScalarTy != ScalarTy) {
        unsigned CastOpcode = Instruction::Trunc;
        unsigned DstSz = R.DL->getTypeSizeInBits(ScalarTy);
        unsigned SrcSz = R.DL->getTypeSizeInBits(EScalarTy);
        if (DstSz > SrcSz)
          CastOpcode = IsSigned ? Instruction::SExt : Instruction::ZExt;
        return TTI.getCastInstrCost(CastOpcode, getWidenedType(ScalarTy, VF),
                                    getWidenedType(EScalarTy, VF),
                                    TTI::CastContextHint::None, CostKind);
      }
      return TTI::TCC_Free;
    };
    auto GetValueMinBWAffectedCost = [&](const Value *V) -> InstructionCost {
      if (isa<Constant>(V))
        return TTI::TCC_Free;
      auto *VecTy = cast<VectorType>(V->getType());
      Type *EScalarTy = VecTy->getElementType();
      if (EScalarTy != ScalarTy) {
        bool IsSigned = !isKnownNonNegative(V, SimplifyQuery(*R.DL));
        unsigned CastOpcode = Instruction::Trunc;
        unsigned DstSz = R.DL->getTypeSizeInBits(ScalarTy);
        unsigned SrcSz = R.DL->getTypeSizeInBits(EScalarTy);
        if (DstSz > SrcSz)
          CastOpcode = IsSigned ? Instruction::SExt : Instruction::ZExt;
        return TTI.getCastInstrCost(
            CastOpcode, VectorType::get(ScalarTy, VecTy->getElementCount()),
            VecTy, TTI::CastContextHint::None, CostKind);
      }
      return TTI::TCC_Free;
    };
    if (!V1 && !V2 && !P2.isNull()) {
      // Shuffle 2 entry nodes.
      const TreeEntry *E = P1.get<const TreeEntry *>();
      unsigned VF = E->getVectorFactor();
      const TreeEntry *E2 = P2.get<const TreeEntry *>();
      CommonVF = std::max(VF, E2->getVectorFactor());
      assert(all_of(Mask,
                    [=](int Idx) {
                      return Idx < 2 * static_cast<int>(CommonVF);
                    }) &&
             "All elements in mask must be less than 2 * CommonVF.");
      if (E->Scalars.size() == E2->Scalars.size()) {
        SmallVector<int> EMask = E->getCommonMask();
        SmallVector<int> E2Mask = E2->getCommonMask();
        if (!EMask.empty() || !E2Mask.empty()) {
          for (int &Idx : CommonMask) {
            if (Idx == PoisonMaskElem)
              continue;
            if (Idx < static_cast<int>(CommonVF) && !EMask.empty())
              Idx = EMask[Idx];
            else if (Idx >= static_cast<int>(CommonVF))
              Idx = (E2Mask.empty() ? Idx - CommonVF : E2Mask[Idx - CommonVF]) +
                    E->Scalars.size();
          }
        }
        CommonVF = E->Scalars.size();
        ExtraCost += GetNodeMinBWAffectedCost(*E, CommonVF) +
                     GetNodeMinBWAffectedCost(*E2, CommonVF);
      } else {
        ExtraCost += GetNodeMinBWAffectedCost(*E, E->getVectorFactor()) +
                     GetNodeMinBWAffectedCost(*E2, E2->getVectorFactor());
      }
      V1 = Constant::getNullValue(getWidenedType(ScalarTy, CommonVF));
      V2 = getAllOnesValue(*R.DL, getWidenedType(ScalarTy, CommonVF));
    } else if (!V1 && P2.isNull()) {
      // Shuffle single entry node.
      const TreeEntry *E = P1.get<const TreeEntry *>();
      unsigned VF = E->getVectorFactor();
      CommonVF = VF;
      assert(
          all_of(Mask,
                 [=](int Idx) { return Idx < static_cast<int>(CommonVF); }) &&
          "All elements in mask must be less than CommonVF.");
      if (E->Scalars.size() == Mask.size() && VF != Mask.size()) {
        SmallVector<int> EMask = E->getCommonMask();
        assert(!EMask.empty() && "Expected non-empty common mask.");
        for (int &Idx : CommonMask) {
          if (Idx != PoisonMaskElem)
            Idx = EMask[Idx];
        }
        CommonVF = E->Scalars.size();
      }
      ExtraCost += GetNodeMinBWAffectedCost(*E, CommonVF);
      V1 = Constant::getNullValue(getWidenedType(ScalarTy, CommonVF));
      // Not identity/broadcast? Try to see if the original vector is better.
      if (!E->ReorderIndices.empty() && CommonVF == E->ReorderIndices.size() &&
          CommonVF == CommonMask.size() &&
          any_of(enumerate(CommonMask),
                 [](const auto &&P) {
                   return P.value() != PoisonMaskElem &&
                          static_cast<unsigned>(P.value()) != P.index();
                 }) &&
          any_of(CommonMask,
                 [](int Idx) { return Idx != PoisonMaskElem && Idx != 0; })) {
        SmallVector<int> ReorderMask;
        inversePermutation(E->ReorderIndices, ReorderMask);
        ::addMask(CommonMask, ReorderMask);
      }
    } else if (V1 && P2.isNull()) {
      // Shuffle single vector.
      ExtraCost += GetValueMinBWAffectedCost(V1);
      CommonVF = getVF(V1);
      assert(
          all_of(Mask,
                 [=](int Idx) { return Idx < static_cast<int>(CommonVF); }) &&
          "All elements in mask must be less than CommonVF.");
    } else if (V1 && !V2) {
      // Shuffle vector and tree node.
      unsigned VF = getVF(V1);
      const TreeEntry *E2 = P2.get<const TreeEntry *>();
      CommonVF = std::max(VF, E2->getVectorFactor());
      assert(all_of(Mask,
                    [=](int Idx) {
                      return Idx < 2 * static_cast<int>(CommonVF);
                    }) &&
             "All elements in mask must be less than 2 * CommonVF.");
      if (E2->Scalars.size() == VF && VF != CommonVF) {
        SmallVector<int> E2Mask = E2->getCommonMask();
        assert(!E2Mask.empty() && "Expected non-empty common mask.");
        for (int &Idx : CommonMask) {
          if (Idx == PoisonMaskElem)
            continue;
          if (Idx >= static_cast<int>(CommonVF))
            Idx = E2Mask[Idx - CommonVF] + VF;
        }
        CommonVF = VF;
      }
      ExtraCost += GetValueMinBWAffectedCost(V1);
      V1 = Constant::getNullValue(getWidenedType(ScalarTy, CommonVF));
      ExtraCost += GetNodeMinBWAffectedCost(
          *E2, std::min(CommonVF, E2->getVectorFactor()));
      V2 = getAllOnesValue(*R.DL, getWidenedType(ScalarTy, CommonVF));
    } else if (!V1 && V2) {
      // Shuffle vector and tree node.
      unsigned VF = getVF(V2);
      const TreeEntry *E1 = P1.get<const TreeEntry *>();
      CommonVF = std::max(VF, E1->getVectorFactor());
      assert(all_of(Mask,
                    [=](int Idx) {
                      return Idx < 2 * static_cast<int>(CommonVF);
                    }) &&
             "All elements in mask must be less than 2 * CommonVF.");
      if (E1->Scalars.size() == VF && VF != CommonVF) {
        SmallVector<int> E1Mask = E1->getCommonMask();
        assert(!E1Mask.empty() && "Expected non-empty common mask.");
        for (int &Idx : CommonMask) {
          if (Idx == PoisonMaskElem)
            continue;
          if (Idx >= static_cast<int>(CommonVF))
            Idx = E1Mask[Idx - CommonVF] + VF;
          else
            Idx = E1Mask[Idx];
        }
        CommonVF = VF;
      }
      ExtraCost += GetNodeMinBWAffectedCost(
          *E1, std::min(CommonVF, E1->getVectorFactor()));
      V1 = Constant::getNullValue(getWidenedType(ScalarTy, CommonVF));
      ExtraCost += GetValueMinBWAffectedCost(V2);
      V2 = getAllOnesValue(*R.DL, getWidenedType(ScalarTy, CommonVF));
    } else {
      assert(V1 && V2 && "Expected both vectors.");
      unsigned VF = getVF(V1);
      CommonVF = std::max(VF, getVF(V2));
      assert(all_of(Mask,
                    [=](int Idx) {
                      return Idx < 2 * static_cast<int>(CommonVF);
                    }) &&
             "All elements in mask must be less than 2 * CommonVF.");
      ExtraCost +=
          GetValueMinBWAffectedCost(V1) + GetValueMinBWAffectedCost(V2);
      if (V1->getType() != V2->getType()) {
        V1 = Constant::getNullValue(getWidenedType(ScalarTy, CommonVF));
        V2 = getAllOnesValue(*R.DL, getWidenedType(ScalarTy, CommonVF));
      } else {
        if (cast<VectorType>(V1->getType())->getElementType() != ScalarTy)
          V1 = Constant::getNullValue(getWidenedType(ScalarTy, CommonVF));
        if (cast<VectorType>(V2->getType())->getElementType() != ScalarTy)
          V2 = getAllOnesValue(*R.DL, getWidenedType(ScalarTy, CommonVF));
      }
    }
    if (auto *VecTy = dyn_cast<FixedVectorType>(ScalarTy)) {
      assert(SLPReVec && "FixedVectorType is not expected.");
      transformScalarShuffleIndiciesToVector(VecTy->getNumElements(),
                                             CommonMask);
    }
    InVectors.front() =
        Constant::getNullValue(getWidenedType(ScalarTy, CommonMask.size()));
    if (InVectors.size() == 2)
      InVectors.pop_back();
    return ExtraCost + BaseShuffleAnalysis::createShuffle<InstructionCost>(
                           V1, V2, CommonMask, Builder);
  }

public:
  ShuffleCostEstimator(Type *ScalarTy, TargetTransformInfo &TTI,
                       ArrayRef<Value *> VectorizedVals, BoUpSLP &R,
                       SmallPtrSetImpl<Value *> &CheckedExtracts)
      : BaseShuffleAnalysis(ScalarTy), TTI(TTI),
        VectorizedVals(VectorizedVals.begin(), VectorizedVals.end()), R(R),
        CheckedExtracts(CheckedExtracts) {}
  Value *adjustExtracts(const TreeEntry *E, MutableArrayRef<int> Mask,
                        ArrayRef<std::optional<TTI::ShuffleKind>> ShuffleKinds,
                        unsigned NumParts, bool &UseVecBaseAsInput) {
    UseVecBaseAsInput = false;
    if (Mask.empty())
      return nullptr;
    Value *VecBase = nullptr;
    ArrayRef<Value *> VL = E->Scalars;
    // If the resulting type is scalarized, do not adjust the cost.
    if (NumParts == VL.size())
      return nullptr;
    // Check if it can be considered reused if same extractelements were
    // vectorized already.
    bool PrevNodeFound = any_of(
        ArrayRef(R.VectorizableTree).take_front(E->Idx),
        [&](const std::unique_ptr<TreeEntry> &TE) {
          return ((!TE->isAltShuffle() &&
                   TE->getOpcode() == Instruction::ExtractElement) ||
                  TE->isGather()) &&
                 all_of(enumerate(TE->Scalars), [&](auto &&Data) {
                   return VL.size() > Data.index() &&
                          (Mask[Data.index()] == PoisonMaskElem ||
                           isa<UndefValue>(VL[Data.index()]) ||
                           Data.value() == VL[Data.index()]);
                 });
        });
    SmallPtrSet<Value *, 4> UniqueBases;
    unsigned SliceSize = getPartNumElems(VL.size(), NumParts);
    for (unsigned Part : seq<unsigned>(NumParts)) {
      unsigned Limit = getNumElems(VL.size(), SliceSize, Part);
      ArrayRef<int> SubMask = Mask.slice(Part * SliceSize, Limit);
      for (auto [I, V] : enumerate(VL.slice(Part * SliceSize, Limit))) {
        // Ignore non-extractelement scalars.
        if (isa<UndefValue>(V) ||
            (!SubMask.empty() && SubMask[I] == PoisonMaskElem))
          continue;
        // If all users of instruction are going to be vectorized and this
        // instruction itself is not going to be vectorized, consider this
        // instruction as dead and remove its cost from the final cost of the
        // vectorized tree.
        // Also, avoid adjusting the cost for extractelements with multiple uses
        // in different graph entries.
        auto *EE = cast<ExtractElementInst>(V);
        VecBase = EE->getVectorOperand();
        UniqueBases.insert(VecBase);
        const TreeEntry *VE = R.getTreeEntry(V);
        if (!CheckedExtracts.insert(V).second ||
            !R.areAllUsersVectorized(cast<Instruction>(V), &VectorizedVals) ||
            any_of(EE->users(),
                   [&](User *U) {
                     return isa<GetElementPtrInst>(U) &&
                            !R.areAllUsersVectorized(cast<Instruction>(U),
                                                     &VectorizedVals);
                   }) ||
            (VE && VE != E))
          continue;
        std::optional<unsigned> EEIdx = getExtractIndex(EE);
        if (!EEIdx)
          continue;
        unsigned Idx = *EEIdx;
        // Take credit for instruction that will become dead.
        if (EE->hasOneUse() || !PrevNodeFound) {
          Instruction *Ext = EE->user_back();
          if (isa<SExtInst, ZExtInst>(Ext) &&
              all_of(Ext->users(), IsaPred<GetElementPtrInst>)) {
            // Use getExtractWithExtendCost() to calculate the cost of
            // extractelement/ext pair.
            Cost -=
                TTI.getExtractWithExtendCost(Ext->getOpcode(), Ext->getType(),
                                             EE->getVectorOperandType(), Idx);
            // Add back the cost of s|zext which is subtracted separately.
            Cost += TTI.getCastInstrCost(
                Ext->getOpcode(), Ext->getType(), EE->getType(),
                TTI::getCastContextHint(Ext), CostKind, Ext);
            continue;
          }
        }
        Cost -= TTI.getVectorInstrCost(*EE, EE->getVectorOperandType(),
                                       CostKind, Idx);
      }
    }
    // Check that gather of extractelements can be represented as just a
    // shuffle of a single/two vectors the scalars are extracted from.
    // Found the bunch of extractelement instructions that must be gathered
    // into a vector and can be represented as a permutation elements in a
    // single input vector or of 2 input vectors.
    // Done for reused if same extractelements were vectorized already.
    if (!PrevNodeFound)
      Cost += computeExtractCost(VL, Mask, ShuffleKinds, NumParts);
    InVectors.assign(1, E);
    CommonMask.assign(Mask.begin(), Mask.end());
    transformMaskAfterShuffle(CommonMask, CommonMask);
    SameNodesEstimated = false;
    if (NumParts != 1 && UniqueBases.size() != 1) {
      UseVecBaseAsInput = true;
      VecBase =
          Constant::getNullValue(getWidenedType(ScalarTy, CommonMask.size()));
    }
    return VecBase;
  }
  /// Checks if the specified entry \p E needs to be delayed because of its
  /// dependency nodes.
  std::optional<InstructionCost>
  needToDelay(const TreeEntry *,
              ArrayRef<SmallVector<const TreeEntry *>>) const {
    // No need to delay the cost estimation during analysis.
    return std::nullopt;
  }
  void add(const TreeEntry &E1, const TreeEntry &E2, ArrayRef<int> Mask) {
    if (&E1 == &E2) {
      assert(all_of(Mask,
                    [&](int Idx) {
                      return Idx < static_cast<int>(E1.getVectorFactor());
                    }) &&
             "Expected single vector shuffle mask.");
      add(E1, Mask);
      return;
    }
    if (InVectors.empty()) {
      CommonMask.assign(Mask.begin(), Mask.end());
      InVectors.assign({&E1, &E2});
      return;
    }
    assert(!CommonMask.empty() && "Expected non-empty common mask.");
    auto *MaskVecTy = getWidenedType(ScalarTy, Mask.size());
    unsigned NumParts = TTI.getNumberOfParts(MaskVecTy);
    if (NumParts == 0 || NumParts >= Mask.size())
      NumParts = 1;
    unsigned SliceSize = getPartNumElems(Mask.size(), NumParts);
    const auto *It =
        find_if(Mask, [](int Idx) { return Idx != PoisonMaskElem; });
    unsigned Part = std::distance(Mask.begin(), It) / SliceSize;
    estimateNodesPermuteCost(E1, &E2, Mask, Part, SliceSize);
  }
  void add(const TreeEntry &E1, ArrayRef<int> Mask) {
    if (InVectors.empty()) {
      CommonMask.assign(Mask.begin(), Mask.end());
      InVectors.assign(1, &E1);
      return;
    }
    assert(!CommonMask.empty() && "Expected non-empty common mask.");
    auto *MaskVecTy = getWidenedType(ScalarTy, Mask.size());
    unsigned NumParts = TTI.getNumberOfParts(MaskVecTy);
    if (NumParts == 0 || NumParts >= Mask.size())
      NumParts = 1;
    unsigned SliceSize = getPartNumElems(Mask.size(), NumParts);
    const auto *It =
        find_if(Mask, [](int Idx) { return Idx != PoisonMaskElem; });
    unsigned Part = std::distance(Mask.begin(), It) / SliceSize;
    estimateNodesPermuteCost(E1, nullptr, Mask, Part, SliceSize);
    if (!SameNodesEstimated && InVectors.size() == 1)
      InVectors.emplace_back(&E1);
  }
  /// Adds 2 input vectors and the mask for their shuffling.
  void add(Value *V1, Value *V2, ArrayRef<int> Mask) {
    // May come only for shuffling of 2 vectors with extractelements, already
    // handled in adjustExtracts.
    assert(InVectors.size() == 1 &&
           all_of(enumerate(CommonMask),
                  [&](auto P) {
                    if (P.value() == PoisonMaskElem)
                      return Mask[P.index()] == PoisonMaskElem;
                    auto *EI =
                        cast<ExtractElementInst>(InVectors.front()
                                                     .get<const TreeEntry *>()
                                                     ->Scalars[P.index()]);
                    return EI->getVectorOperand() == V1 ||
                           EI->getVectorOperand() == V2;
                  }) &&
           "Expected extractelement vectors.");
  }
  /// Adds another one input vector and the mask for the shuffling.
  void add(Value *V1, ArrayRef<int> Mask, bool ForExtracts = false) {
    if (InVectors.empty()) {
      assert(CommonMask.empty() && !ForExtracts &&
             "Expected empty input mask/vectors.");
      CommonMask.assign(Mask.begin(), Mask.end());
      InVectors.assign(1, V1);
      return;
    }
    if (ForExtracts) {
      // No need to add vectors here, already handled them in adjustExtracts.
      assert(InVectors.size() == 1 &&
             InVectors.front().is<const TreeEntry *>() && !CommonMask.empty() &&
             all_of(enumerate(CommonMask),
                    [&](auto P) {
                      Value *Scalar = InVectors.front()
                                          .get<const TreeEntry *>()
                                          ->Scalars[P.index()];
                      if (P.value() == PoisonMaskElem)
                        return P.value() == Mask[P.index()] ||
                               isa<UndefValue>(Scalar);
                      if (isa<Constant>(V1))
                        return true;
                      auto *EI = cast<ExtractElementInst>(Scalar);
                      return EI->getVectorOperand() == V1;
                    }) &&
             "Expected only tree entry for extractelement vectors.");
      return;
    }
    assert(!InVectors.empty() && !CommonMask.empty() &&
           "Expected only tree entries from extracts/reused buildvectors.");
    unsigned VF = getVF(V1);
    if (InVectors.size() == 2) {
      Cost += createShuffle(InVectors.front(), InVectors.back(), CommonMask);
      transformMaskAfterShuffle(CommonMask, CommonMask);
      VF = std::max<unsigned>(VF, CommonMask.size());
    } else if (const auto *InTE =
                   InVectors.front().dyn_cast<const TreeEntry *>()) {
      VF = std::max(VF, InTE->getVectorFactor());
    } else {
      VF = std::max(
          VF, cast<FixedVectorType>(InVectors.front().get<Value *>()->getType())
                  ->getNumElements());
    }
    InVectors.push_back(V1);
    for (unsigned Idx = 0, Sz = CommonMask.size(); Idx < Sz; ++Idx)
      if (Mask[Idx] != PoisonMaskElem && CommonMask[Idx] == PoisonMaskElem)
        CommonMask[Idx] = Mask[Idx] + VF;
  }
  Value *gather(ArrayRef<Value *> VL, unsigned MaskVF = 0,
                Value *Root = nullptr) {
    Cost += getBuildVectorCost(VL, Root);
    if (!Root) {
      // FIXME: Need to find a way to avoid use of getNullValue here.
      SmallVector<Constant *> Vals;
      unsigned VF = VL.size();
      if (MaskVF != 0)
        VF = std::min(VF, MaskVF);
      for (Value *V : VL.take_front(VF)) {
        if (isa<UndefValue>(V)) {
          Vals.push_back(cast<Constant>(V));
          continue;
        }
        Vals.push_back(Constant::getNullValue(V->getType()));
      }
      if (auto *VecTy = dyn_cast<FixedVectorType>(Vals.front()->getType())) {
        assert(SLPReVec && "FixedVectorType is not expected.");
        // When REVEC is enabled, we need to expand vector types into scalar
        // types.
        unsigned VecTyNumElements = VecTy->getNumElements();
        SmallVector<Constant *> NewVals(VF * VecTyNumElements, nullptr);
        for (auto [I, V] : enumerate(Vals)) {
          Type *ScalarTy = V->getType()->getScalarType();
          Constant *NewVal;
          if (isa<PoisonValue>(V))
            NewVal = PoisonValue::get(ScalarTy);
          else if (isa<UndefValue>(V))
            NewVal = UndefValue::get(ScalarTy);
          else
            NewVal = Constant::getNullValue(ScalarTy);
          std::fill_n(NewVals.begin() + I * VecTyNumElements, VecTyNumElements,
                      NewVal);
        }
        Vals.swap(NewVals);
      }
      return ConstantVector::get(Vals);
    }
    return ConstantVector::getSplat(
        ElementCount::getFixed(
            cast<FixedVectorType>(Root->getType())->getNumElements()),
        getAllOnesValue(*R.DL, ScalarTy->getScalarType()));
  }
  InstructionCost createFreeze(InstructionCost Cost) { return Cost; }
  /// Finalize emission of the shuffles.
  InstructionCost
  finalize(ArrayRef<int> ExtMask,
           ArrayRef<std::pair<const TreeEntry *, unsigned>> SubVectors,
           unsigned VF = 0,
           function_ref<void(Value *&, SmallVectorImpl<int> &)> Action = {}) {
    IsFinalized = true;
    if (Action) {
      const PointerUnion<Value *, const TreeEntry *> &Vec = InVectors.front();
      if (InVectors.size() == 2)
        Cost += createShuffle(Vec, InVectors.back(), CommonMask);
      else
        Cost += createShuffle(Vec, nullptr, CommonMask);
      for (unsigned Idx = 0, Sz = CommonMask.size(); Idx < Sz; ++Idx)
        if (CommonMask[Idx] != PoisonMaskElem)
          CommonMask[Idx] = Idx;
      assert(VF > 0 &&
             "Expected vector length for the final value before action.");
      Value *V = Vec.get<Value *>();
      Action(V, CommonMask);
      InVectors.front() = V;
    }
    if (!SubVectors.empty()) {
      const PointerUnion<Value *, const TreeEntry *> &Vec = InVectors.front();
      if (InVectors.size() == 2)
        Cost += createShuffle(Vec, InVectors.back(), CommonMask);
      else
        Cost += createShuffle(Vec, nullptr, CommonMask);
      for (unsigned Idx = 0, Sz = CommonMask.size(); Idx < Sz; ++Idx)
        if (CommonMask[Idx] != PoisonMaskElem)
          CommonMask[Idx] = Idx;
      for (auto [E, Idx] : SubVectors) {
        Type *EScalarTy = E->Scalars.front()->getType();
        bool IsSigned = true;
        if (auto It = R.MinBWs.find(E); It != R.MinBWs.end()) {
          EScalarTy =
              IntegerType::get(EScalarTy->getContext(), It->second.first);
          IsSigned = It->second.second;
        }
        if (ScalarTy != EScalarTy) {
          unsigned CastOpcode = Instruction::Trunc;
          unsigned DstSz = R.DL->getTypeSizeInBits(ScalarTy);
          unsigned SrcSz = R.DL->getTypeSizeInBits(EScalarTy);
          if (DstSz > SrcSz)
            CastOpcode = IsSigned ? Instruction::SExt : Instruction::ZExt;
          Cost += TTI.getCastInstrCost(
              CastOpcode, getWidenedType(ScalarTy, E->getVectorFactor()),
              getWidenedType(EScalarTy, E->getVectorFactor()),
              TTI::CastContextHint::Normal, CostKind);
        }
        Cost += ::getShuffleCost(
            TTI, TTI::SK_InsertSubvector,
            getWidenedType(ScalarTy, CommonMask.size()), {}, CostKind, Idx,
            getWidenedType(ScalarTy, E->getVectorFactor()));
        if (!CommonMask.empty()) {
          std::iota(std::next(CommonMask.begin(), Idx),
                    std::next(CommonMask.begin(), Idx + E->getVectorFactor()),
                    Idx);
        }
      }
    }

    ::addMask(CommonMask, ExtMask, /*ExtendingManyInputs=*/true);
    if (CommonMask.empty()) {
      assert(InVectors.size() == 1 && "Expected only one vector with no mask");
      return Cost;
    }
    return Cost +
           createShuffle(InVectors.front(),
                         InVectors.size() == 2 ? InVectors.back() : nullptr,
                         CommonMask);
  }

  ~ShuffleCostEstimator() {
    assert((IsFinalized || CommonMask.empty()) &&
           "Shuffle construction must be finalized.");
  }
};

const BoUpSLP::TreeEntry *BoUpSLP::getOperandEntry(const TreeEntry *E,
                                                   unsigned Idx) const {
  if (const TreeEntry *VE = getMatchedVectorizedOperand(E, Idx))
    return VE;
  const auto *It =
      find_if(VectorizableTree, [&](const std::unique_ptr<TreeEntry> &TE) {
        return TE->isGather() &&
               find_if(TE->UserTreeIndices, [&](const EdgeInfo &EI) {
                 return EI.EdgeIdx == Idx && EI.UserTE == E;
               }) != TE->UserTreeIndices.end();
      });
  assert(It != VectorizableTree.end() && "Expected vectorizable entry.");
  return It->get();
}

TTI::CastContextHint BoUpSLP::getCastContextHint(const TreeEntry &TE) const {
  if (TE.State == TreeEntry::ScatterVectorize ||
      TE.State == TreeEntry::StridedVectorize)
    return TTI::CastContextHint::GatherScatter;
  if (TE.State == TreeEntry::Vectorize && TE.getOpcode() == Instruction::Load &&
      !TE.isAltShuffle()) {
    if (TE.ReorderIndices.empty())
      return TTI::CastContextHint::Normal;
    SmallVector<int> Mask;
    inversePermutation(TE.ReorderIndices, Mask);
    if (ShuffleVectorInst::isReverseMask(Mask, Mask.size()))
      return TTI::CastContextHint::Reversed;
  }
  return TTI::CastContextHint::None;
}

/// Builds the arguments types vector for the given call instruction with the
/// given \p ID for the specified vector factor.
static SmallVector<Type *> buildIntrinsicArgTypes(const CallInst *CI,
                                                  const Intrinsic::ID ID,
                                                  const unsigned VF,
                                                  unsigned MinBW) {
  SmallVector<Type *> ArgTys;
  for (auto [Idx, Arg] : enumerate(CI->args())) {
    if (ID != Intrinsic::not_intrinsic) {
      if (isVectorIntrinsicWithScalarOpAtArg(ID, Idx)) {
        ArgTys.push_back(Arg->getType());
        continue;
      }
      if (MinBW > 0) {
        ArgTys.push_back(
            getWidenedType(IntegerType::get(CI->getContext(), MinBW), VF));
        continue;
      }
    }
    ArgTys.push_back(getWidenedType(Arg->getType(), VF));
  }
  return ArgTys;
}

InstructionCost
BoUpSLP::getEntryCost(const TreeEntry *E, ArrayRef<Value *> VectorizedVals,
                      SmallPtrSetImpl<Value *> &CheckedExtracts) {
  ArrayRef<Value *> VL = E->Scalars;

  Type *ScalarTy = getValueType(VL[0]);
  if (!isValidElementType(ScalarTy))
    return InstructionCost::getInvalid();
  TTI::TargetCostKind CostKind = TTI::TCK_RecipThroughput;

  // If we have computed a smaller type for the expression, update VecTy so
  // that the costs will be accurate.
  auto It = MinBWs.find(E);
  Type *OrigScalarTy = ScalarTy;
  if (It != MinBWs.end()) {
    auto *VecTy = dyn_cast<FixedVectorType>(ScalarTy);
    ScalarTy = IntegerType::get(F->getContext(), It->second.first);
    if (VecTy)
      ScalarTy = getWidenedType(ScalarTy, VecTy->getNumElements());
  }
  auto *VecTy = getWidenedType(ScalarTy, VL.size());
  unsigned EntryVF = E->getVectorFactor();
  auto *FinalVecTy = getWidenedType(ScalarTy, EntryVF);

  bool NeedToShuffleReuses = !E->ReuseShuffleIndices.empty();
  if (E->isGather()) {
    if (allConstant(VL))
      return 0;
    if (isa<InsertElementInst>(VL[0]))
      return InstructionCost::getInvalid();
    if (isa<CmpInst>(VL.front()))
      ScalarTy = VL.front()->getType();
    return processBuildVector<ShuffleCostEstimator, InstructionCost>(
        E, ScalarTy, *TTI, VectorizedVals, *this, CheckedExtracts);
  }
  InstructionCost CommonCost = 0;
  SmallVector<int> Mask;
  bool IsReverseOrder = isReverseOrder(E->ReorderIndices);
  if (!E->ReorderIndices.empty() &&
      (E->State != TreeEntry::StridedVectorize || !IsReverseOrder)) {
    SmallVector<int> NewMask;
    if (E->getOpcode() == Instruction::Store) {
      // For stores the order is actually a mask.
      NewMask.resize(E->ReorderIndices.size());
      copy(E->ReorderIndices, NewMask.begin());
    } else {
      inversePermutation(E->ReorderIndices, NewMask);
    }
    ::addMask(Mask, NewMask);
  }
  if (NeedToShuffleReuses)
    ::addMask(Mask, E->ReuseShuffleIndices);
  if (!Mask.empty() && !ShuffleVectorInst::isIdentityMask(Mask, Mask.size()))
    CommonCost =
        ::getShuffleCost(*TTI, TTI::SK_PermuteSingleSrc, FinalVecTy, Mask);
  assert((E->State == TreeEntry::Vectorize ||
          E->State == TreeEntry::ScatterVectorize ||
          E->State == TreeEntry::StridedVectorize) &&
         "Unhandled state");
  assert(E->getOpcode() &&
         ((allSameType(VL) && allSameBlock(VL)) ||
          (E->getOpcode() == Instruction::GetElementPtr &&
           E->getMainOp()->getType()->isPointerTy())) &&
         "Invalid VL");
  Instruction *VL0 = E->getMainOp();
  unsigned ShuffleOrOp =
      E->isAltShuffle() ? (unsigned)Instruction::ShuffleVector : E->getOpcode();
  if (E->CombinedOp != TreeEntry::NotCombinedOp)
    ShuffleOrOp = E->CombinedOp;
  SetVector<Value *> UniqueValues(VL.begin(), VL.end());
  const unsigned Sz = UniqueValues.size();
  SmallBitVector UsedScalars(Sz, false);
  for (unsigned I = 0; I < Sz; ++I) {
    if (getTreeEntry(UniqueValues[I]) == E)
      continue;
    UsedScalars.set(I);
  }
  auto GetCastContextHint = [&](Value *V) {
    if (const TreeEntry *OpTE = getTreeEntry(V))
      return getCastContextHint(*OpTE);
    InstructionsState SrcState = getSameOpcode(E->getOperand(0), *TLI);
    if (SrcState.getOpcode() == Instruction::Load && !SrcState.isAltShuffle())
      return TTI::CastContextHint::GatherScatter;
    return TTI::CastContextHint::None;
  };
  auto GetCostDiff =
      [=](function_ref<InstructionCost(unsigned)> ScalarEltCost,
          function_ref<InstructionCost(InstructionCost)> VectorCost) {
        // Calculate the cost of this instruction.
        InstructionCost ScalarCost = 0;
        if (isa<CastInst, CallInst>(VL0)) {
          // For some of the instructions no need to calculate cost for each
          // particular instruction, we can use the cost of the single
          // instruction x total number of scalar instructions.
          ScalarCost = (Sz - UsedScalars.count()) * ScalarEltCost(0);
        } else {
          for (unsigned I = 0; I < Sz; ++I) {
            if (UsedScalars.test(I))
              continue;
            ScalarCost += ScalarEltCost(I);
          }
        }

        InstructionCost VecCost = VectorCost(CommonCost);
        // Check if the current node must be resized, if the parent node is not
        // resized.
        if (!UnaryInstruction::isCast(E->getOpcode()) && E->Idx != 0 &&
            (E->getOpcode() != Instruction::Load ||
             !E->UserTreeIndices.empty())) {
          const EdgeInfo &EI = E->UserTreeIndices.front();
          if ((EI.UserTE->getOpcode() != Instruction::Select ||
               EI.EdgeIdx != 0) &&
              It != MinBWs.end()) {
            auto UserBWIt = MinBWs.find(EI.UserTE);
            Type *UserScalarTy =
                EI.UserTE->getOperand(EI.EdgeIdx).front()->getType();
            if (UserBWIt != MinBWs.end())
              UserScalarTy = IntegerType::get(ScalarTy->getContext(),
                                              UserBWIt->second.first);
            if (ScalarTy != UserScalarTy) {
              unsigned BWSz = DL->getTypeSizeInBits(ScalarTy);
              unsigned SrcBWSz = DL->getTypeSizeInBits(UserScalarTy);
              unsigned VecOpcode;
              auto *UserVecTy =
                  getWidenedType(UserScalarTy, E->getVectorFactor());
              if (BWSz > SrcBWSz)
                VecOpcode = Instruction::Trunc;
              else
                VecOpcode =
                    It->second.second ? Instruction::SExt : Instruction::ZExt;
              TTI::CastContextHint CCH = GetCastContextHint(VL0);
              VecCost += TTI->getCastInstrCost(VecOpcode, UserVecTy, VecTy, CCH,
                                               CostKind);
            }
          }
        }
        LLVM_DEBUG(dumpTreeCosts(E, CommonCost, VecCost - CommonCost,
                                 ScalarCost, "Calculated costs for Tree"));
        return VecCost - ScalarCost;
      };
  // Calculate cost difference from vectorizing set of GEPs.
  // Negative value means vectorizing is profitable.
  auto GetGEPCostDiff = [=](ArrayRef<Value *> Ptrs, Value *BasePtr) {
    assert((E->State == TreeEntry::Vectorize ||
            E->State == TreeEntry::StridedVectorize) &&
           "Entry state expected to be Vectorize or StridedVectorize here.");
    InstructionCost ScalarCost = 0;
    InstructionCost VecCost = 0;
    std::tie(ScalarCost, VecCost) = getGEPCosts(
        *TTI, Ptrs, BasePtr, E->getOpcode(), CostKind, OrigScalarTy, VecTy);
    LLVM_DEBUG(dumpTreeCosts(E, 0, VecCost, ScalarCost,
                             "Calculated GEPs cost for Tree"));

    return VecCost - ScalarCost;
  };

  auto GetMinMaxCost = [&](Type *Ty, Instruction *VI = nullptr) {
    auto [MinMaxID, SelectOnly] = canConvertToMinOrMaxIntrinsic(VI ? VI : VL);
    if (MinMaxID == Intrinsic::not_intrinsic)
      return InstructionCost::getInvalid();
    Type *CanonicalType = Ty;
    if (CanonicalType->isPtrOrPtrVectorTy())
      CanonicalType = CanonicalType->getWithNewType(IntegerType::get(
          CanonicalType->getContext(),
          DL->getTypeSizeInBits(CanonicalType->getScalarType())));

    IntrinsicCostAttributes CostAttrs(MinMaxID, CanonicalType,
                                      {CanonicalType, CanonicalType});
    InstructionCost IntrinsicCost =
        TTI->getIntrinsicInstrCost(CostAttrs, CostKind);
    // If the selects are the only uses of the compares, they will be
    // dead and we can adjust the cost by removing their cost.
    if (VI && SelectOnly) {
      assert(!Ty->isVectorTy() && "Expected only for scalar type.");
      auto *CI = cast<CmpInst>(VI->getOperand(0));
      IntrinsicCost -=
          TTI->getCmpSelInstrCost(CI->getOpcode(), Ty, Builder.getInt1Ty(),
                                  CI->getPredicate(), CostKind, CI);
    }
    return IntrinsicCost;
  };
  switch (ShuffleOrOp) {
  case Instruction::PHI: {
    // Count reused scalars.
    InstructionCost ScalarCost = 0;
    SmallPtrSet<const TreeEntry *, 4> CountedOps;
    for (Value *V : UniqueValues) {
      auto *PHI = dyn_cast<PHINode>(V);
      if (!PHI)
        continue;

      ValueList Operands(PHI->getNumIncomingValues(), nullptr);
      for (unsigned I = 0, N = PHI->getNumIncomingValues(); I < N; ++I) {
        Value *Op = PHI->getIncomingValue(I);
        Operands[I] = Op;
      }
      if (const TreeEntry *OpTE = getTreeEntry(Operands.front()))
        if (OpTE->isSame(Operands) && CountedOps.insert(OpTE).second)
          if (!OpTE->ReuseShuffleIndices.empty())
            ScalarCost += TTI::TCC_Basic * (OpTE->ReuseShuffleIndices.size() -
                                            OpTE->Scalars.size());
    }

    return CommonCost - ScalarCost;
  }
  case Instruction::ExtractValue:
  case Instruction::ExtractElement: {
    auto GetScalarCost = [&](unsigned Idx) {
      auto *I = cast<Instruction>(UniqueValues[Idx]);
      VectorType *SrcVecTy;
      if (ShuffleOrOp == Instruction::ExtractElement) {
        auto *EE = cast<ExtractElementInst>(I);
        SrcVecTy = EE->getVectorOperandType();
      } else {
        auto *EV = cast<ExtractValueInst>(I);
        Type *AggregateTy = EV->getAggregateOperand()->getType();
        unsigned NumElts;
        if (auto *ATy = dyn_cast<ArrayType>(AggregateTy))
          NumElts = ATy->getNumElements();
        else
          NumElts = AggregateTy->getStructNumElements();
        SrcVecTy = getWidenedType(OrigScalarTy, NumElts);
      }
      if (I->hasOneUse()) {
        Instruction *Ext = I->user_back();
        if ((isa<SExtInst>(Ext) || isa<ZExtInst>(Ext)) &&
            all_of(Ext->users(), IsaPred<GetElementPtrInst>)) {
          // Use getExtractWithExtendCost() to calculate the cost of
          // extractelement/ext pair.
          InstructionCost Cost = TTI->getExtractWithExtendCost(
              Ext->getOpcode(), Ext->getType(), SrcVecTy, *getExtractIndex(I));
          // Subtract the cost of s|zext which is subtracted separately.
          Cost -= TTI->getCastInstrCost(
              Ext->getOpcode(), Ext->getType(), I->getType(),
              TTI::getCastContextHint(Ext), CostKind, Ext);
          return Cost;
        }
      }
      return TTI->getVectorInstrCost(Instruction::ExtractElement, SrcVecTy,
                                     CostKind, *getExtractIndex(I));
    };
    auto GetVectorCost = [](InstructionCost CommonCost) { return CommonCost; };
    return GetCostDiff(GetScalarCost, GetVectorCost);
  }
  case Instruction::InsertElement: {
    assert(E->ReuseShuffleIndices.empty() &&
           "Unique insertelements only are expected.");
    auto *SrcVecTy = cast<FixedVectorType>(VL0->getType());
    unsigned const NumElts = SrcVecTy->getNumElements();
    unsigned const NumScalars = VL.size();

    unsigned NumOfParts = TTI->getNumberOfParts(SrcVecTy);

    SmallVector<int> InsertMask(NumElts, PoisonMaskElem);
    unsigned OffsetBeg = *getElementIndex(VL.front());
    unsigned OffsetEnd = OffsetBeg;
    InsertMask[OffsetBeg] = 0;
    for (auto [I, V] : enumerate(VL.drop_front())) {
      unsigned Idx = *getElementIndex(V);
      if (OffsetBeg > Idx)
        OffsetBeg = Idx;
      else if (OffsetEnd < Idx)
        OffsetEnd = Idx;
      InsertMask[Idx] = I + 1;
    }
    unsigned VecScalarsSz = PowerOf2Ceil(NumElts);
    if (NumOfParts > 0)
      VecScalarsSz = PowerOf2Ceil((NumElts + NumOfParts - 1) / NumOfParts);
    unsigned VecSz = (1 + OffsetEnd / VecScalarsSz - OffsetBeg / VecScalarsSz) *
                     VecScalarsSz;
    unsigned Offset = VecScalarsSz * (OffsetBeg / VecScalarsSz);
    unsigned InsertVecSz = std::min<unsigned>(
        PowerOf2Ceil(OffsetEnd - OffsetBeg + 1),
        ((OffsetEnd - OffsetBeg + VecScalarsSz) / VecScalarsSz) * VecScalarsSz);
    bool IsWholeSubvector =
        OffsetBeg == Offset && ((OffsetEnd + 1) % VecScalarsSz == 0);
    // Check if we can safely insert a subvector. If it is not possible, just
    // generate a whole-sized vector and shuffle the source vector and the new
    // subvector.
    if (OffsetBeg + InsertVecSz > VecSz) {
      // Align OffsetBeg to generate correct mask.
      OffsetBeg = alignDown(OffsetBeg, VecSz, Offset);
      InsertVecSz = VecSz;
    }

    APInt DemandedElts = APInt::getZero(NumElts);
    // TODO: Add support for Instruction::InsertValue.
    SmallVector<int> Mask;
    if (!E->ReorderIndices.empty()) {
      inversePermutation(E->ReorderIndices, Mask);
      Mask.append(InsertVecSz - Mask.size(), PoisonMaskElem);
    } else {
      Mask.assign(VecSz, PoisonMaskElem);
      std::iota(Mask.begin(), std::next(Mask.begin(), InsertVecSz), 0);
    }
    bool IsIdentity = true;
    SmallVector<int> PrevMask(InsertVecSz, PoisonMaskElem);
    Mask.swap(PrevMask);
    for (unsigned I = 0; I < NumScalars; ++I) {
      unsigned InsertIdx = *getElementIndex(VL[PrevMask[I]]);
      DemandedElts.setBit(InsertIdx);
      IsIdentity &= InsertIdx - OffsetBeg == I;
      Mask[InsertIdx - OffsetBeg] = I;
    }
    assert(Offset < NumElts && "Failed to find vector index offset");

    InstructionCost Cost = 0;
    Cost -= TTI->getScalarizationOverhead(SrcVecTy, DemandedElts,
                                          /*Insert*/ true, /*Extract*/ false,
                                          CostKind);

    // First cost - resize to actual vector size if not identity shuffle or
    // need to shift the vector.
    // Do not calculate the cost if the actual size is the register size and
    // we can merge this shuffle with the following SK_Select.
    auto *InsertVecTy = getWidenedType(ScalarTy, InsertVecSz);
    if (!IsIdentity)
      Cost += ::getShuffleCost(*TTI, TargetTransformInfo::SK_PermuteSingleSrc,
                               InsertVecTy, Mask);
    auto *FirstInsert = cast<Instruction>(*find_if(E->Scalars, [E](Value *V) {
      return !is_contained(E->Scalars, cast<Instruction>(V)->getOperand(0));
    }));
    // Second cost - permutation with subvector, if some elements are from the
    // initial vector or inserting a subvector.
    // TODO: Implement the analysis of the FirstInsert->getOperand(0)
    // subvector of ActualVecTy.
    SmallBitVector InMask =
        isUndefVector(FirstInsert->getOperand(0),
                      buildUseMask(NumElts, InsertMask, UseMask::UndefsAsMask));
    if (!InMask.all() && NumScalars != NumElts && !IsWholeSubvector) {
      if (InsertVecSz != VecSz) {
        auto *ActualVecTy = getWidenedType(ScalarTy, VecSz);
        Cost += ::getShuffleCost(*TTI, TTI::SK_InsertSubvector, ActualVecTy, {},
                                 CostKind, OffsetBeg - Offset, InsertVecTy);
      } else {
        for (unsigned I = 0, End = OffsetBeg - Offset; I < End; ++I)
          Mask[I] = InMask.test(I) ? PoisonMaskElem : I;
        for (unsigned I = OffsetBeg - Offset, End = OffsetEnd - Offset;
             I <= End; ++I)
          if (Mask[I] != PoisonMaskElem)
            Mask[I] = I + VecSz;
        for (unsigned I = OffsetEnd + 1 - Offset; I < VecSz; ++I)
          Mask[I] =
              ((I >= InMask.size()) || InMask.test(I)) ? PoisonMaskElem : I;
        Cost +=
            ::getShuffleCost(*TTI, TTI::SK_PermuteTwoSrc, InsertVecTy, Mask);
      }
    }
    return Cost;
  }
  case Instruction::ZExt:
  case Instruction::SExt:
  case Instruction::FPToUI:
  case Instruction::FPToSI:
  case Instruction::FPExt:
  case Instruction::PtrToInt:
  case Instruction::IntToPtr:
  case Instruction::SIToFP:
  case Instruction::UIToFP:
  case Instruction::Trunc:
  case Instruction::FPTrunc:
  case Instruction::BitCast: {
    auto SrcIt = MinBWs.find(getOperandEntry(E, 0));
    Type *SrcScalarTy = VL0->getOperand(0)->getType();
    auto *SrcVecTy = getWidenedType(SrcScalarTy, VL.size());
    unsigned Opcode = ShuffleOrOp;
    unsigned VecOpcode = Opcode;
    if (!ScalarTy->isFPOrFPVectorTy() && !SrcScalarTy->isFPOrFPVectorTy() &&
        (SrcIt != MinBWs.end() || It != MinBWs.end())) {
      // Check if the values are candidates to demote.
      unsigned SrcBWSz = DL->getTypeSizeInBits(SrcScalarTy->getScalarType());
      if (SrcIt != MinBWs.end()) {
        SrcBWSz = SrcIt->second.first;
        unsigned SrcScalarTyNumElements = getNumElements(SrcScalarTy);
        SrcScalarTy = IntegerType::get(F->getContext(), SrcBWSz);
        SrcVecTy =
            getWidenedType(SrcScalarTy, VL.size() * SrcScalarTyNumElements);
      }
      unsigned BWSz = DL->getTypeSizeInBits(ScalarTy->getScalarType());
      if (BWSz == SrcBWSz) {
        VecOpcode = Instruction::BitCast;
      } else if (BWSz < SrcBWSz) {
        VecOpcode = Instruction::Trunc;
      } else if (It != MinBWs.end()) {
        assert(BWSz > SrcBWSz && "Invalid cast!");
        VecOpcode = It->second.second ? Instruction::SExt : Instruction::ZExt;
      } else if (SrcIt != MinBWs.end()) {
        assert(BWSz > SrcBWSz && "Invalid cast!");
        VecOpcode =
            SrcIt->second.second ? Instruction::SExt : Instruction::ZExt;
      }
    } else if (VecOpcode == Instruction::SIToFP && SrcIt != MinBWs.end() &&
               !SrcIt->second.second) {
      VecOpcode = Instruction::UIToFP;
    }
    auto GetScalarCost = [&](unsigned Idx) -> InstructionCost {
      auto *VI = cast<Instruction>(UniqueValues[Idx]);
      return TTI->getCastInstrCost(Opcode, VL0->getType(),
                                   VL0->getOperand(0)->getType(),
                                   TTI::getCastContextHint(VI), CostKind, VI);
    };
    auto GetVectorCost = [=](InstructionCost CommonCost) {
      // Do not count cost here if minimum bitwidth is in effect and it is just
      // a bitcast (here it is just a noop).
      if (VecOpcode != Opcode && VecOpcode == Instruction::BitCast)
        return CommonCost;
      auto *VI = VL0->getOpcode() == Opcode ? VL0 : nullptr;
      TTI::CastContextHint CCH = GetCastContextHint(VL0->getOperand(0));
      return CommonCost +
             TTI->getCastInstrCost(VecOpcode, VecTy, SrcVecTy, CCH, CostKind,
                                   VecOpcode == Opcode ? VI : nullptr);
    };
    return GetCostDiff(GetScalarCost, GetVectorCost);
  }
  case Instruction::FCmp:
  case Instruction::ICmp:
  case Instruction::Select: {
    CmpInst::Predicate VecPred, SwappedVecPred;
    auto MatchCmp = m_Cmp(VecPred, m_Value(), m_Value());
    if (match(VL0, m_Select(MatchCmp, m_Value(), m_Value())) ||
        match(VL0, MatchCmp))
      SwappedVecPred = CmpInst::getSwappedPredicate(VecPred);
    else
      SwappedVecPred = VecPred = ScalarTy->isFloatingPointTy()
                                     ? CmpInst::BAD_FCMP_PREDICATE
                                     : CmpInst::BAD_ICMP_PREDICATE;
    auto GetScalarCost = [&](unsigned Idx) {
      auto *VI = cast<Instruction>(UniqueValues[Idx]);
      CmpInst::Predicate CurrentPred = ScalarTy->isFloatingPointTy()
                                           ? CmpInst::BAD_FCMP_PREDICATE
                                           : CmpInst::BAD_ICMP_PREDICATE;
      auto MatchCmp = m_Cmp(CurrentPred, m_Value(), m_Value());
      if ((!match(VI, m_Select(MatchCmp, m_Value(), m_Value())) &&
           !match(VI, MatchCmp)) ||
          (CurrentPred != VecPred && CurrentPred != SwappedVecPred))
        VecPred = SwappedVecPred = ScalarTy->isFloatingPointTy()
                                       ? CmpInst::BAD_FCMP_PREDICATE
                                       : CmpInst::BAD_ICMP_PREDICATE;

      InstructionCost ScalarCost = TTI->getCmpSelInstrCost(
          E->getOpcode(), OrigScalarTy, Builder.getInt1Ty(), CurrentPred,
          CostKind, VI);
      InstructionCost IntrinsicCost = GetMinMaxCost(OrigScalarTy, VI);
      if (IntrinsicCost.isValid())
        ScalarCost = IntrinsicCost;

      return ScalarCost;
    };
    auto GetVectorCost = [&](InstructionCost CommonCost) {
      auto *MaskTy = getWidenedType(Builder.getInt1Ty(), VL.size());

      InstructionCost VecCost = TTI->getCmpSelInstrCost(
          E->getOpcode(), VecTy, MaskTy, VecPred, CostKind, VL0);
      if (auto *SI = dyn_cast<SelectInst>(VL0)) {
        auto *CondType =
            getWidenedType(SI->getCondition()->getType(), VL.size());
        unsigned CondNumElements = CondType->getNumElements();
        unsigned VecTyNumElements = getNumElements(VecTy);
        assert(VecTyNumElements >= CondNumElements &&
               VecTyNumElements % CondNumElements == 0 &&
               "Cannot vectorize Instruction::Select");
        if (CondNumElements != VecTyNumElements) {
          // When the return type is i1 but the source is fixed vector type, we
          // need to duplicate the condition value.
          VecCost += ::getShuffleCost(
              *TTI, TTI::SK_PermuteSingleSrc, CondType,
              createReplicatedMask(VecTyNumElements / CondNumElements,
                                   CondNumElements));
        }
      }
      return VecCost + CommonCost;
    };
    return GetCostDiff(GetScalarCost, GetVectorCost);
  }
  case TreeEntry::MinMax: {
    auto GetScalarCost = [&](unsigned Idx) {
      return GetMinMaxCost(OrigScalarTy);
    };
    auto GetVectorCost = [&](InstructionCost CommonCost) {
      InstructionCost VecCost = GetMinMaxCost(VecTy);
      return VecCost + CommonCost;
    };
    return GetCostDiff(GetScalarCost, GetVectorCost);
  }
  case Instruction::FNeg:
  case Instruction::Add:
  case Instruction::FAdd:
  case Instruction::Sub:
  case Instruction::FSub:
  case Instruction::Mul:
  case Instruction::FMul:
  case Instruction::UDiv:
  case Instruction::SDiv:
  case Instruction::FDiv:
  case Instruction::URem:
  case Instruction::SRem:
  case Instruction::FRem:
  case Instruction::Shl:
  case Instruction::LShr:
  case Instruction::AShr:
  case Instruction::And:
  case Instruction::Or:
  case Instruction::Xor: {
    auto GetScalarCost = [&](unsigned Idx) {
      auto *VI = cast<Instruction>(UniqueValues[Idx]);
      unsigned OpIdx = isa<UnaryOperator>(VI) ? 0 : 1;
      TTI::OperandValueInfo Op1Info = TTI::getOperandInfo(VI->getOperand(0));
      TTI::OperandValueInfo Op2Info =
          TTI::getOperandInfo(VI->getOperand(OpIdx));
      SmallVector<const Value *> Operands(VI->operand_values());
      return TTI->getArithmeticInstrCost(ShuffleOrOp, OrigScalarTy, CostKind,
                                         Op1Info, Op2Info, Operands, VI);
    };
    auto GetVectorCost = [=](InstructionCost CommonCost) {
      if (ShuffleOrOp == Instruction::And && It != MinBWs.end()) {
        for (unsigned I : seq<unsigned>(0, E->getNumOperands())) {
          ArrayRef<Value *> Ops = E->getOperand(I);
          if (all_of(Ops, [&](Value *Op) {
                auto *CI = dyn_cast<ConstantInt>(Op);
                return CI && CI->getValue().countr_one() >= It->second.first;
              }))
            return CommonCost;
        }
      }
      unsigned OpIdx = isa<UnaryOperator>(VL0) ? 0 : 1;
      TTI::OperandValueInfo Op1Info = getOperandInfo(E->getOperand(0));
      TTI::OperandValueInfo Op2Info = getOperandInfo(E->getOperand(OpIdx));
      return TTI->getArithmeticInstrCost(ShuffleOrOp, VecTy, CostKind, Op1Info,
                                         Op2Info, {}, nullptr, TLI) +
             CommonCost;
    };
    return GetCostDiff(GetScalarCost, GetVectorCost);
  }
  case Instruction::GetElementPtr: {
    return CommonCost + GetGEPCostDiff(VL, VL0);
  }
  case Instruction::Load: {
    auto GetScalarCost = [&](unsigned Idx) {
      auto *VI = cast<LoadInst>(UniqueValues[Idx]);
      return TTI->getMemoryOpCost(Instruction::Load, OrigScalarTy,
                                  VI->getAlign(), VI->getPointerAddressSpace(),
                                  CostKind, TTI::OperandValueInfo(), VI);
    };
    auto *LI0 = cast<LoadInst>(VL0);
    auto GetVectorCost = [&](InstructionCost CommonCost) {
      InstructionCost VecLdCost;
      if (E->State == TreeEntry::Vectorize) {
        VecLdCost = TTI->getMemoryOpCost(
            Instruction::Load, VecTy, LI0->getAlign(),
            LI0->getPointerAddressSpace(), CostKind, TTI::OperandValueInfo());
      } else if (E->State == TreeEntry::StridedVectorize) {
        Align CommonAlignment =
            computeCommonAlignment<LoadInst>(UniqueValues.getArrayRef());
        VecLdCost = TTI->getStridedMemoryOpCost(
            Instruction::Load, VecTy, LI0->getPointerOperand(),
            /*VariableMask=*/false, CommonAlignment, CostKind);
      } else {
        assert(E->State == TreeEntry::ScatterVectorize && "Unknown EntryState");
        Align CommonAlignment =
            computeCommonAlignment<LoadInst>(UniqueValues.getArrayRef());
        VecLdCost = TTI->getGatherScatterOpCost(
            Instruction::Load, VecTy, LI0->getPointerOperand(),
            /*VariableMask=*/false, CommonAlignment, CostKind);
      }
      return VecLdCost + CommonCost;
    };

    InstructionCost Cost = GetCostDiff(GetScalarCost, GetVectorCost);
    // If this node generates masked gather load then it is not a terminal node.
    // Hence address operand cost is estimated separately.
    if (E->State == TreeEntry::ScatterVectorize)
      return Cost;

    // Estimate cost of GEPs since this tree node is a terminator.
    SmallVector<Value *> PointerOps(VL.size());
    for (auto [I, V] : enumerate(VL))
      PointerOps[I] = cast<LoadInst>(V)->getPointerOperand();
    return Cost + GetGEPCostDiff(PointerOps, LI0->getPointerOperand());
  }
  case Instruction::Store: {
    bool IsReorder = !E->ReorderIndices.empty();
    auto GetScalarCost = [=](unsigned Idx) {
      auto *VI = cast<StoreInst>(VL[Idx]);
      TTI::OperandValueInfo OpInfo = TTI::getOperandInfo(VI->getValueOperand());
      return TTI->getMemoryOpCost(Instruction::Store, OrigScalarTy,
                                  VI->getAlign(), VI->getPointerAddressSpace(),
                                  CostKind, OpInfo, VI);
    };
    auto *BaseSI =
        cast<StoreInst>(IsReorder ? VL[E->ReorderIndices.front()] : VL0);
    auto GetVectorCost = [=](InstructionCost CommonCost) {
      // We know that we can merge the stores. Calculate the cost.
      InstructionCost VecStCost;
      if (E->State == TreeEntry::StridedVectorize) {
        Align CommonAlignment =
            computeCommonAlignment<StoreInst>(UniqueValues.getArrayRef());
        VecStCost = TTI->getStridedMemoryOpCost(
            Instruction::Store, VecTy, BaseSI->getPointerOperand(),
            /*VariableMask=*/false, CommonAlignment, CostKind);
      } else {
        assert(E->State == TreeEntry::Vectorize &&
               "Expected either strided or consecutive stores.");
        TTI::OperandValueInfo OpInfo = getOperandInfo(E->getOperand(0));
        VecStCost = TTI->getMemoryOpCost(
            Instruction::Store, VecTy, BaseSI->getAlign(),
            BaseSI->getPointerAddressSpace(), CostKind, OpInfo);
      }
      return VecStCost + CommonCost;
    };
    SmallVector<Value *> PointerOps(VL.size());
    for (auto [I, V] : enumerate(VL)) {
      unsigned Idx = IsReorder ? E->ReorderIndices[I] : I;
      PointerOps[Idx] = cast<StoreInst>(V)->getPointerOperand();
    }

    return GetCostDiff(GetScalarCost, GetVectorCost) +
           GetGEPCostDiff(PointerOps, BaseSI->getPointerOperand());
  }
  case Instruction::Call: {
    auto GetScalarCost = [&](unsigned Idx) {
      auto *CI = cast<CallInst>(UniqueValues[Idx]);
      Intrinsic::ID ID = getVectorIntrinsicIDForCall(CI, TLI);
      if (ID != Intrinsic::not_intrinsic) {
        IntrinsicCostAttributes CostAttrs(ID, *CI, 1);
        return TTI->getIntrinsicInstrCost(CostAttrs, CostKind);
      }
      return TTI->getCallInstrCost(CI->getCalledFunction(),
                                   CI->getFunctionType()->getReturnType(),
                                   CI->getFunctionType()->params(), CostKind);
    };
    auto GetVectorCost = [=](InstructionCost CommonCost) {
      auto *CI = cast<CallInst>(VL0);
      Intrinsic::ID ID = getVectorIntrinsicIDForCall(CI, TLI);
      SmallVector<Type *> ArgTys =
          buildIntrinsicArgTypes(CI, ID, VecTy->getNumElements(),
                                 It != MinBWs.end() ? It->second.first : 0);
      auto VecCallCosts = getVectorCallCosts(CI, VecTy, TTI, TLI, ArgTys);
      return std::min(VecCallCosts.first, VecCallCosts.second) + CommonCost;
    };
    return GetCostDiff(GetScalarCost, GetVectorCost);
  }
  case Instruction::ShuffleVector: {
    if (!SLPReVec || E->isAltShuffle())
      assert(E->isAltShuffle() &&
             ((Instruction::isBinaryOp(E->getOpcode()) &&
               Instruction::isBinaryOp(E->getAltOpcode())) ||
              (Instruction::isCast(E->getOpcode()) &&
               Instruction::isCast(E->getAltOpcode())) ||
              (isa<CmpInst>(VL0) && isa<CmpInst>(E->getAltOp()))) &&
             "Invalid Shuffle Vector Operand");
    // Try to find the previous shuffle node with the same operands and same
    // main/alternate ops.
    auto TryFindNodeWithEqualOperands = [=]() {
      for (const std::unique_ptr<TreeEntry> &TE : VectorizableTree) {
        if (TE.get() == E)
          break;
        if (TE->isAltShuffle() &&
            ((TE->getOpcode() == E->getOpcode() &&
              TE->getAltOpcode() == E->getAltOpcode()) ||
             (TE->getOpcode() == E->getAltOpcode() &&
              TE->getAltOpcode() == E->getOpcode())) &&
            TE->hasEqualOperands(*E))
          return true;
      }
      return false;
    };
    auto GetScalarCost = [&](unsigned Idx) {
      auto *VI = cast<Instruction>(UniqueValues[Idx]);
      assert(E->isOpcodeOrAlt(VI) && "Unexpected main/alternate opcode");
      (void)E;
      return TTI->getInstructionCost(VI, CostKind);
    };
    // Need to clear CommonCost since the final shuffle cost is included into
    // vector cost.
    auto GetVectorCost = [&, &TTIRef = *TTI](InstructionCost) {
      // VecCost is equal to sum of the cost of creating 2 vectors
      // and the cost of creating shuffle.
      InstructionCost VecCost = 0;
      if (TryFindNodeWithEqualOperands()) {
        LLVM_DEBUG({
          dbgs() << "SLP: diamond match for alternate node found.\n";
          E->dump();
        });
        // No need to add new vector costs here since we're going to reuse
        // same main/alternate vector ops, just do different shuffling.
      } else if (Instruction::isBinaryOp(E->getOpcode())) {
        VecCost =
            TTIRef.getArithmeticInstrCost(E->getOpcode(), VecTy, CostKind);
        VecCost +=
            TTIRef.getArithmeticInstrCost(E->getAltOpcode(), VecTy, CostKind);
      } else if (auto *CI0 = dyn_cast<CmpInst>(VL0)) {
        auto *MaskTy = getWidenedType(Builder.getInt1Ty(), VL.size());
        VecCost = TTIRef.getCmpSelInstrCost(E->getOpcode(), VecTy, MaskTy,
                                            CI0->getPredicate(), CostKind, VL0);
        VecCost += TTIRef.getCmpSelInstrCost(
            E->getOpcode(), VecTy, MaskTy,
            cast<CmpInst>(E->getAltOp())->getPredicate(), CostKind,
            E->getAltOp());
      } else {
        Type *SrcSclTy = E->getMainOp()->getOperand(0)->getType();
        auto *SrcTy = getWidenedType(SrcSclTy, VL.size());
        if (SrcSclTy->isIntegerTy() && ScalarTy->isIntegerTy()) {
          auto SrcIt = MinBWs.find(getOperandEntry(E, 0));
          unsigned BWSz = DL->getTypeSizeInBits(ScalarTy);
          unsigned SrcBWSz =
              DL->getTypeSizeInBits(E->getMainOp()->getOperand(0)->getType());
          if (SrcIt != MinBWs.end()) {
            SrcBWSz = SrcIt->second.first;
            SrcSclTy = IntegerType::get(SrcSclTy->getContext(), SrcBWSz);
            SrcTy = getWidenedType(SrcSclTy, VL.size());
          }
          if (BWSz <= SrcBWSz) {
            if (BWSz < SrcBWSz)
              VecCost =
                  TTIRef.getCastInstrCost(Instruction::Trunc, VecTy, SrcTy,
                                          TTI::CastContextHint::None, CostKind);
            LLVM_DEBUG({
              dbgs()
                  << "SLP: alternate extension, which should be truncated.\n";
              E->dump();
            });
            return VecCost;
          }
        }
        VecCost = TTIRef.getCastInstrCost(E->getOpcode(), VecTy, SrcTy,
                                          TTI::CastContextHint::None, CostKind);
        VecCost +=
            TTIRef.getCastInstrCost(E->getAltOpcode(), VecTy, SrcTy,
                                    TTI::CastContextHint::None, CostKind);
      }
      SmallVector<int> Mask;
      E->buildAltOpShuffleMask(
          [&](Instruction *I) {
            assert(E->isOpcodeOrAlt(I) && "Unexpected main/alternate opcode");
            return isAlternateInstruction(I, E->getMainOp(), E->getAltOp(),
                                          *TLI);
          },
          Mask);
      VecCost += ::getShuffleCost(TTIRef, TargetTransformInfo::SK_PermuteTwoSrc,
                                  FinalVecTy, Mask, CostKind);
      // Patterns like [fadd,fsub] can be combined into a single instruction
      // in x86. Reordering them into [fsub,fadd] blocks this pattern. So we
      // need to take into account their order when looking for the most used
      // order.
      unsigned Opcode0 = E->getOpcode();
      unsigned Opcode1 = E->getAltOpcode();
      SmallBitVector OpcodeMask(getAltInstrMask(E->Scalars, Opcode0, Opcode1));
      // If this pattern is supported by the target then we consider the
      // order.
      if (TTIRef.isLegalAltInstr(VecTy, Opcode0, Opcode1, OpcodeMask)) {
        InstructionCost AltVecCost = TTIRef.getAltInstrCost(
            VecTy, Opcode0, Opcode1, OpcodeMask, CostKind);
        return AltVecCost < VecCost ? AltVecCost : VecCost;
      }
      // TODO: Check the reverse order too.
      return VecCost;
    };
    if (SLPReVec && !E->isAltShuffle())
      return GetCostDiff(
          GetScalarCost, [&](InstructionCost) -> InstructionCost {
            // If a group uses mask in order, the shufflevector can be
            // eliminated by instcombine. Then the cost is 0.
            assert(isa<ShuffleVectorInst>(VL.front()) &&
                   "Not supported shufflevector usage.");
            auto *SV = cast<ShuffleVectorInst>(VL.front());
            unsigned SVNumElements =
                cast<FixedVectorType>(SV->getOperand(0)->getType())
                    ->getNumElements();
            unsigned GroupSize = SVNumElements / SV->getShuffleMask().size();
            for (size_t I = 0, End = VL.size(); I != End; I += GroupSize) {
              ArrayRef<Value *> Group = VL.slice(I, GroupSize);
              int NextIndex = 0;
              if (!all_of(Group, [&](Value *V) {
                    assert(isa<ShuffleVectorInst>(V) &&
                           "Not supported shufflevector usage.");
                    auto *SV = cast<ShuffleVectorInst>(V);
                    int Index;
                    [[maybe_unused]] bool isExtractSubvectorMask =
                        SV->isExtractSubvectorMask(Index);
                    assert(isExtractSubvectorMask &&
                           "Not supported shufflevector usage.");
                    if (NextIndex != Index)
                      return false;
                    NextIndex += SV->getShuffleMask().size();
                    return true;
                  }))
                return ::getShuffleCost(
                    *TTI, TargetTransformInfo::SK_PermuteSingleSrc, VecTy,
                    calculateShufflevectorMask(E->Scalars));
            }
            return TTI::TCC_Free;
          });
    return GetCostDiff(GetScalarCost, GetVectorCost);
  }
  case Instruction::Freeze:
    return CommonCost;
  default:
    llvm_unreachable("Unknown instruction");
  }
}

bool BoUpSLP::isFullyVectorizableTinyTree(bool ForReduction) const {
  LLVM_DEBUG(dbgs() << "SLP: Check whether the tree with height "
                    << VectorizableTree.size() << " is fully vectorizable .\n");

  auto &&AreVectorizableGathers = [this](const TreeEntry *TE, unsigned Limit) {
    SmallVector<int> Mask;
    return TE->isGather() &&
           !any_of(TE->Scalars,
                   [this](Value *V) { return EphValues.contains(V); }) &&
           (allConstant(TE->Scalars) || isSplat(TE->Scalars) ||
            TE->Scalars.size() < Limit ||
            ((TE->getOpcode() == Instruction::ExtractElement ||
              all_of(TE->Scalars, IsaPred<ExtractElementInst, UndefValue>)) &&
             isFixedVectorShuffle(TE->Scalars, Mask)) ||
            (TE->getOpcode() == Instruction::Load && !TE->isAltShuffle()) ||
            any_of(TE->Scalars, IsaPred<LoadInst>));
  };

  // We only handle trees of heights 1 and 2.
  if (VectorizableTree.size() == 1 &&
      (VectorizableTree[0]->State == TreeEntry::Vectorize ||
       VectorizableTree[0]->State == TreeEntry::StridedVectorize ||
       (ForReduction &&
        AreVectorizableGathers(VectorizableTree[0].get(),
                               VectorizableTree[0]->Scalars.size()) &&
        VectorizableTree[0]->getVectorFactor() > 2)))
    return true;

  if (VectorizableTree.size() != 2)
    return false;

  // Handle splat and all-constants stores. Also try to vectorize tiny trees
  // with the second gather nodes if they have less scalar operands rather than
  // the initial tree element (may be profitable to shuffle the second gather)
  // or they are extractelements, which form shuffle.
  SmallVector<int> Mask;
  if (VectorizableTree[0]->State == TreeEntry::Vectorize &&
      AreVectorizableGathers(VectorizableTree[1].get(),
                             VectorizableTree[0]->Scalars.size()))
    return true;

  // Gathering cost would be too much for tiny trees.
  if (VectorizableTree[0]->isGather() ||
      (VectorizableTree[1]->isGather() &&
       VectorizableTree[0]->State != TreeEntry::ScatterVectorize &&
       VectorizableTree[0]->State != TreeEntry::StridedVectorize))
    return false;

  return true;
}

static bool isLoadCombineCandidateImpl(Value *Root, unsigned NumElts,
                                       TargetTransformInfo *TTI,
                                       bool MustMatchOrInst) {
  // Look past the root to find a source value. Arbitrarily follow the
  // path through operand 0 of any 'or'. Also, peek through optional
  // shift-left-by-multiple-of-8-bits.
  Value *ZextLoad = Root;
  const APInt *ShAmtC;
  bool FoundOr = false;
  while (!isa<ConstantExpr>(ZextLoad) &&
         (match(ZextLoad, m_Or(m_Value(), m_Value())) ||
          (match(ZextLoad, m_Shl(m_Value(), m_APInt(ShAmtC))) &&
           ShAmtC->urem(8) == 0))) {
    auto *BinOp = cast<BinaryOperator>(ZextLoad);
    ZextLoad = BinOp->getOperand(0);
    if (BinOp->getOpcode() == Instruction::Or)
      FoundOr = true;
  }
  // Check if the input is an extended load of the required or/shift expression.
  Value *Load;
  if ((MustMatchOrInst && !FoundOr) || ZextLoad == Root ||
      !match(ZextLoad, m_ZExt(m_Value(Load))) || !isa<LoadInst>(Load))
    return false;

  // Require that the total load bit width is a legal integer type.
  // For example, <8 x i8> --> i64 is a legal integer on a 64-bit target.
  // But <16 x i8> --> i128 is not, so the backend probably can't reduce it.
  Type *SrcTy = Load->getType();
  unsigned LoadBitWidth = SrcTy->getIntegerBitWidth() * NumElts;
  if (!TTI->isTypeLegal(IntegerType::get(Root->getContext(), LoadBitWidth)))
    return false;

  // Everything matched - assume that we can fold the whole sequence using
  // load combining.
  LLVM_DEBUG(dbgs() << "SLP: Assume load combining for tree starting at "
             << *(cast<Instruction>(Root)) << "\n");

  return true;
}

bool BoUpSLP::isLoadCombineReductionCandidate(RecurKind RdxKind) const {
  if (RdxKind != RecurKind::Or)
    return false;

  unsigned NumElts = VectorizableTree[0]->Scalars.size();
  Value *FirstReduced = VectorizableTree[0]->Scalars[0];
  return isLoadCombineCandidateImpl(FirstReduced, NumElts, TTI,
                                    /* MatchOr */ false);
}

bool BoUpSLP::isLoadCombineCandidate(ArrayRef<Value *> Stores) const {
  // Peek through a final sequence of stores and check if all operations are
  // likely to be load-combined.
  unsigned NumElts = Stores.size();
  for (Value *Scalar : Stores) {
    Value *X;
    if (!match(Scalar, m_Store(m_Value(X), m_Value())) ||
        !isLoadCombineCandidateImpl(X, NumElts, TTI, /* MatchOr */ true))
      return false;
  }
  return true;
}

bool BoUpSLP::isTreeTinyAndNotFullyVectorizable(bool ForReduction) const {
  // No need to vectorize inserts of gathered values.
  if (VectorizableTree.size() == 2 &&
      isa<InsertElementInst>(VectorizableTree[0]->Scalars[0]) &&
      VectorizableTree[1]->isGather() &&
      (VectorizableTree[1]->getVectorFactor() <= 2 ||
       !(isSplat(VectorizableTree[1]->Scalars) ||
         allConstant(VectorizableTree[1]->Scalars))))
    return true;

  // If the graph includes only PHI nodes and gathers, it is defnitely not
  // profitable for the vectorization, we can skip it, if the cost threshold is
  // default. The cost of vectorized PHI nodes is almost always 0 + the cost of
  // gathers/buildvectors.
  constexpr int Limit = 4;
  if (!ForReduction && !SLPCostThreshold.getNumOccurrences() &&
      !VectorizableTree.empty() &&
      all_of(VectorizableTree, [&](const std::unique_ptr<TreeEntry> &TE) {
        return (TE->isGather() &&
                TE->getOpcode() != Instruction::ExtractElement &&
                count_if(TE->Scalars, IsaPred<ExtractElementInst>) <= Limit) ||
               TE->getOpcode() == Instruction::PHI;
      }))
    return true;

  // We can vectorize the tree if its size is greater than or equal to the
  // minimum size specified by the MinTreeSize command line option.
  if (VectorizableTree.size() >= MinTreeSize)
    return false;

  // If we have a tiny tree (a tree whose size is less than MinTreeSize), we
  // can vectorize it if we can prove it fully vectorizable.
  if (isFullyVectorizableTinyTree(ForReduction))
    return false;

  // Check if any of the gather node forms an insertelement buildvector
  // somewhere.
  bool IsAllowedSingleBVNode =
      VectorizableTree.size() > 1 ||
      (VectorizableTree.size() == 1 && VectorizableTree.front()->getOpcode() &&
       !VectorizableTree.front()->isAltShuffle() &&
       VectorizableTree.front()->getOpcode() != Instruction::PHI &&
       VectorizableTree.front()->getOpcode() != Instruction::GetElementPtr &&
       allSameBlock(VectorizableTree.front()->Scalars));
  if (any_of(VectorizableTree, [&](const std::unique_ptr<TreeEntry> &TE) {
        return TE->isGather() && all_of(TE->Scalars, [&](Value *V) {
                 return isa<ExtractElementInst, UndefValue>(V) ||
                        (IsAllowedSingleBVNode &&
                         !V->hasNUsesOrMore(UsesLimit) &&
                         any_of(V->users(), IsaPred<InsertElementInst>));
               });
      }))
    return false;

  assert(VectorizableTree.empty()
             ? ExternalUses.empty()
             : true && "We shouldn't have any external users");

  // Otherwise, we can't vectorize the tree. It is both tiny and not fully
  // vectorizable.
  return true;
}

InstructionCost BoUpSLP::getSpillCost() const {
  // Walk from the bottom of the tree to the top, tracking which values are
  // live. When we see a call instruction that is not part of our tree,
  // query TTI to see if there is a cost to keeping values live over it
  // (for example, if spills and fills are required).
  unsigned BundleWidth = VectorizableTree.front()->Scalars.size();
  InstructionCost Cost = 0;

  SmallPtrSet<Instruction *, 4> LiveValues;
  Instruction *PrevInst = nullptr;

  // The entries in VectorizableTree are not necessarily ordered by their
  // position in basic blocks. Collect them and order them by dominance so later
  // instructions are guaranteed to be visited first. For instructions in
  // different basic blocks, we only scan to the beginning of the block, so
  // their order does not matter, as long as all instructions in a basic block
  // are grouped together. Using dominance ensures a deterministic order.
  SmallVector<Instruction *, 16> OrderedScalars;
  for (const auto &TEPtr : VectorizableTree) {
    if (TEPtr->State != TreeEntry::Vectorize)
      continue;
    Instruction *Inst = dyn_cast<Instruction>(TEPtr->Scalars[0]);
    if (!Inst)
      continue;
    OrderedScalars.push_back(Inst);
  }
  llvm::sort(OrderedScalars, [&](Instruction *A, Instruction *B) {
    auto *NodeA = DT->getNode(A->getParent());
    auto *NodeB = DT->getNode(B->getParent());
    assert(NodeA && "Should only process reachable instructions");
    assert(NodeB && "Should only process reachable instructions");
    assert((NodeA == NodeB) == (NodeA->getDFSNumIn() == NodeB->getDFSNumIn()) &&
           "Different nodes should have different DFS numbers");
    if (NodeA != NodeB)
      return NodeA->getDFSNumIn() > NodeB->getDFSNumIn();
    return B->comesBefore(A);
  });

  for (Instruction *Inst : OrderedScalars) {
    if (!PrevInst) {
      PrevInst = Inst;
      continue;
    }

    // Update LiveValues.
    LiveValues.erase(PrevInst);
    for (auto &J : PrevInst->operands()) {
      if (isa<Instruction>(&*J) && getTreeEntry(&*J))
        LiveValues.insert(cast<Instruction>(&*J));
    }

    LLVM_DEBUG({
      dbgs() << "SLP: #LV: " << LiveValues.size();
      for (auto *X : LiveValues)
        dbgs() << " " << X->getName();
      dbgs() << ", Looking at ";
      Inst->dump();
    });

    // Now find the sequence of instructions between PrevInst and Inst.
    unsigned NumCalls = 0;
    BasicBlock::reverse_iterator InstIt = ++Inst->getIterator().getReverse(),
                                 PrevInstIt =
                                     PrevInst->getIterator().getReverse();
    while (InstIt != PrevInstIt) {
      if (PrevInstIt == PrevInst->getParent()->rend()) {
        PrevInstIt = Inst->getParent()->rbegin();
        continue;
      }

      auto NoCallIntrinsic = [this](Instruction *I) {
        if (auto *II = dyn_cast<IntrinsicInst>(I)) {
          if (II->isAssumeLikeIntrinsic())
            return true;
          FastMathFlags FMF;
          SmallVector<Type *, 4> Tys;
          for (auto &ArgOp : II->args())
            Tys.push_back(ArgOp->getType());
          if (auto *FPMO = dyn_cast<FPMathOperator>(II))
            FMF = FPMO->getFastMathFlags();
          IntrinsicCostAttributes ICA(II->getIntrinsicID(), II->getType(), Tys,
                                      FMF);
          InstructionCost IntrCost =
              TTI->getIntrinsicInstrCost(ICA, TTI::TCK_RecipThroughput);
          InstructionCost CallCost = TTI->getCallInstrCost(
              nullptr, II->getType(), Tys, TTI::TCK_RecipThroughput);
          if (IntrCost < CallCost)
            return true;
        }
        return false;
      };

      // Debug information does not impact spill cost.
      if (isa<CallBase>(&*PrevInstIt) && !NoCallIntrinsic(&*PrevInstIt) &&
          &*PrevInstIt != PrevInst)
        NumCalls++;

      ++PrevInstIt;
    }

    if (NumCalls) {
      SmallVector<Type *, 4> V;
      for (auto *II : LiveValues) {
        auto *ScalarTy = II->getType();
        if (auto *VectorTy = dyn_cast<FixedVectorType>(ScalarTy))
          ScalarTy = VectorTy->getElementType();
        V.push_back(getWidenedType(ScalarTy, BundleWidth));
      }
      Cost += NumCalls * TTI->getCostOfKeepingLiveOverCall(V);
    }

    PrevInst = Inst;
  }

  return Cost;
}

/// Checks if the \p IE1 instructions is followed by \p IE2 instruction in the
/// buildvector sequence.
static bool isFirstInsertElement(const InsertElementInst *IE1,
                                 const InsertElementInst *IE2) {
  if (IE1 == IE2)
    return false;
  const auto *I1 = IE1;
  const auto *I2 = IE2;
  const InsertElementInst *PrevI1;
  const InsertElementInst *PrevI2;
  unsigned Idx1 = *getElementIndex(IE1);
  unsigned Idx2 = *getElementIndex(IE2);
  do {
    if (I2 == IE1)
      return true;
    if (I1 == IE2)
      return false;
    PrevI1 = I1;
    PrevI2 = I2;
    if (I1 && (I1 == IE1 || I1->hasOneUse()) &&
        getElementIndex(I1).value_or(Idx2) != Idx2)
      I1 = dyn_cast<InsertElementInst>(I1->getOperand(0));
    if (I2 && ((I2 == IE2 || I2->hasOneUse())) &&
        getElementIndex(I2).value_or(Idx1) != Idx1)
      I2 = dyn_cast<InsertElementInst>(I2->getOperand(0));
  } while ((I1 && PrevI1 != I1) || (I2 && PrevI2 != I2));
  llvm_unreachable("Two different buildvectors not expected.");
}

namespace {
/// Returns incoming Value *, if the requested type is Value * too, or a default
/// value, otherwise.
struct ValueSelect {
  template <typename U>
  static std::enable_if_t<std::is_same_v<Value *, U>, Value *> get(Value *V) {
    return V;
  }
  template <typename U>
  static std::enable_if_t<!std::is_same_v<Value *, U>, U> get(Value *) {
    return U();
  }
};
} // namespace

/// Does the analysis of the provided shuffle masks and performs the requested
/// actions on the vectors with the given shuffle masks. It tries to do it in
/// several steps.
/// 1. If the Base vector is not undef vector, resizing the very first mask to
/// have common VF and perform action for 2 input vectors (including non-undef
/// Base). Other shuffle masks are combined with the resulting after the 1 stage
/// and processed as a shuffle of 2 elements.
/// 2. If the Base is undef vector and have only 1 shuffle mask, perform the
/// action only for 1 vector with the given mask, if it is not the identity
/// mask.
/// 3. If > 2 masks are used, perform the remaining shuffle actions for 2
/// vectors, combing the masks properly between the steps.
template <typename T>
static T *performExtractsShuffleAction(
    MutableArrayRef<std::pair<T *, SmallVector<int>>> ShuffleMask, Value *Base,
    function_ref<unsigned(T *)> GetVF,
    function_ref<std::pair<T *, bool>(T *, ArrayRef<int>, bool)> ResizeAction,
    function_ref<T *(ArrayRef<int>, ArrayRef<T *>)> Action) {
  assert(!ShuffleMask.empty() && "Empty list of shuffles for inserts.");
  SmallVector<int> Mask(ShuffleMask.begin()->second);
  auto VMIt = std::next(ShuffleMask.begin());
  T *Prev = nullptr;
  SmallBitVector UseMask =
      buildUseMask(Mask.size(), Mask, UseMask::UndefsAsMask);
  SmallBitVector IsBaseUndef = isUndefVector(Base, UseMask);
  if (!IsBaseUndef.all()) {
    // Base is not undef, need to combine it with the next subvectors.
    std::pair<T *, bool> Res =
        ResizeAction(ShuffleMask.begin()->first, Mask, /*ForSingleMask=*/false);
    SmallBitVector IsBasePoison = isUndefVector<true>(Base, UseMask);
    for (unsigned Idx = 0, VF = Mask.size(); Idx < VF; ++Idx) {
      if (Mask[Idx] == PoisonMaskElem)
        Mask[Idx] = IsBasePoison.test(Idx) ? PoisonMaskElem : Idx;
      else
        Mask[Idx] = (Res.second ? Idx : Mask[Idx]) + VF;
    }
    auto *V = ValueSelect::get<T *>(Base);
    (void)V;
    assert((!V || GetVF(V) == Mask.size()) &&
           "Expected base vector of VF number of elements.");
    Prev = Action(Mask, {nullptr, Res.first});
  } else if (ShuffleMask.size() == 1) {
    // Base is undef and only 1 vector is shuffled - perform the action only for
    // single vector, if the mask is not the identity mask.
    std::pair<T *, bool> Res = ResizeAction(ShuffleMask.begin()->first, Mask,
                                            /*ForSingleMask=*/true);
    if (Res.second)
      // Identity mask is found.
      Prev = Res.first;
    else
      Prev = Action(Mask, {ShuffleMask.begin()->first});
  } else {
    // Base is undef and at least 2 input vectors shuffled - perform 2 vectors
    // shuffles step by step, combining shuffle between the steps.
    unsigned Vec1VF = GetVF(ShuffleMask.begin()->first);
    unsigned Vec2VF = GetVF(VMIt->first);
    if (Vec1VF == Vec2VF) {
      // No need to resize the input vectors since they are of the same size, we
      // can shuffle them directly.
      ArrayRef<int> SecMask = VMIt->second;
      for (unsigned I = 0, VF = Mask.size(); I < VF; ++I) {
        if (SecMask[I] != PoisonMaskElem) {
          assert(Mask[I] == PoisonMaskElem && "Multiple uses of scalars.");
          Mask[I] = SecMask[I] + Vec1VF;
        }
      }
      Prev = Action(Mask, {ShuffleMask.begin()->first, VMIt->first});
    } else {
      // Vectors of different sizes - resize and reshuffle.
      std::pair<T *, bool> Res1 = ResizeAction(ShuffleMask.begin()->first, Mask,
                                               /*ForSingleMask=*/false);
      std::pair<T *, bool> Res2 =
          ResizeAction(VMIt->first, VMIt->second, /*ForSingleMask=*/false);
      ArrayRef<int> SecMask = VMIt->second;
      for (unsigned I = 0, VF = Mask.size(); I < VF; ++I) {
        if (Mask[I] != PoisonMaskElem) {
          assert(SecMask[I] == PoisonMaskElem && "Multiple uses of scalars.");
          if (Res1.second)
            Mask[I] = I;
        } else if (SecMask[I] != PoisonMaskElem) {
          assert(Mask[I] == PoisonMaskElem && "Multiple uses of scalars.");
          Mask[I] = (Res2.second ? I : SecMask[I]) + VF;
        }
      }
      Prev = Action(Mask, {Res1.first, Res2.first});
    }
    VMIt = std::next(VMIt);
  }
  bool IsBaseNotUndef = !IsBaseUndef.all();
  (void)IsBaseNotUndef;
  // Perform requested actions for the remaining masks/vectors.
  for (auto E = ShuffleMask.end(); VMIt != E; ++VMIt) {
    // Shuffle other input vectors, if any.
    std::pair<T *, bool> Res =
        ResizeAction(VMIt->first, VMIt->second, /*ForSingleMask=*/false);
    ArrayRef<int> SecMask = VMIt->second;
    for (unsigned I = 0, VF = Mask.size(); I < VF; ++I) {
      if (SecMask[I] != PoisonMaskElem) {
        assert((Mask[I] == PoisonMaskElem || IsBaseNotUndef) &&
               "Multiple uses of scalars.");
        Mask[I] = (Res.second ? I : SecMask[I]) + VF;
      } else if (Mask[I] != PoisonMaskElem) {
        Mask[I] = I;
      }
    }
    Prev = Action(Mask, {Prev, Res.first});
  }
  return Prev;
}

namespace {
/// Data type for handling buildvector sequences with the reused scalars from
/// other tree entries.
template <typename T> struct ShuffledInsertData {
  /// List of insertelements to be replaced by shuffles.
  SmallVector<InsertElementInst *> InsertElements;
  /// The parent vectors and shuffle mask for the given list of inserts.
  MapVector<T, SmallVector<int>> ValueMasks;
};
} // namespace

InstructionCost BoUpSLP::getTreeCost(ArrayRef<Value *> VectorizedVals) {
  InstructionCost Cost = 0;
  LLVM_DEBUG(dbgs() << "SLP: Calculating cost for tree of size "
                    << VectorizableTree.size() << ".\n");

  unsigned BundleWidth = VectorizableTree[0]->Scalars.size();

  SmallPtrSet<Value *, 4> CheckedExtracts;
  for (unsigned I = 0, E = VectorizableTree.size(); I < E; ++I) {
    TreeEntry &TE = *VectorizableTree[I];
    // No need to count the cost for combined entries, they are combined and
    // just skip their cost.
    if (TE.State == TreeEntry::CombinedVectorize) {
      LLVM_DEBUG(
          dbgs() << "SLP: Skipping cost for combined node that starts with "
                 << *TE.Scalars[0] << ".\n";
          TE.dump(); dbgs() << "SLP: Current total cost = " << Cost << "\n");
      continue;
    }
    if (TE.isGather()) {
      if (const TreeEntry *E = getTreeEntry(TE.getMainOp());
          E && E->getVectorFactor() == TE.getVectorFactor() &&
          E->isSame(TE.Scalars)) {
        // Some gather nodes might be absolutely the same as some vectorizable
        // nodes after reordering, need to handle it.
        LLVM_DEBUG(dbgs() << "SLP: Adding cost 0 for bundle "
                          << shortBundleName(TE.Scalars, TE.Idx) << ".\n"
                          << "SLP: Current total cost = " << Cost << "\n");
        continue;
      }
    }

    // Exclude cost of gather loads nodes which are not used. These nodes were
    // built as part of the final attempt to vectorize gathered loads.
    assert((!TE.isGather() || TE.Idx == 0 || !TE.UserTreeIndices.empty()) &&
           "Expected gather nodes with users only.");

    InstructionCost C = getEntryCost(&TE, VectorizedVals, CheckedExtracts);
    Cost += C;
    LLVM_DEBUG(dbgs() << "SLP: Adding cost " << C << " for bundle "
                      << shortBundleName(TE.Scalars, TE.Idx) << ".\n"
                      << "SLP: Current total cost = " << Cost << "\n");
  }

  SmallPtrSet<Value *, 16> ExtractCostCalculated;
  InstructionCost ExtractCost = 0;
  SmallVector<ShuffledInsertData<const TreeEntry *>> ShuffledInserts;
  SmallVector<APInt> DemandedElts;
  SmallDenseSet<Value *, 4> UsedInserts;
  DenseSet<std::pair<const TreeEntry *, Type *>> VectorCasts;
  std::optional<DenseMap<Value *, unsigned>> ValueToExtUses;
  DenseMap<const TreeEntry *, DenseSet<Value *>> ExtractsCount;
  for (ExternalUser &EU : ExternalUses) {
    // Uses by ephemeral values are free (because the ephemeral value will be
    // removed prior to code generation, and so the extraction will be
    // removed as well) as well as uses in unreachable blocks or in landing pads
    // (rarely executed).
    if (EphValues.count(EU.User) ||
        (EU.User &&
         (!DT->isReachableFromEntry(cast<Instruction>(EU.User)->getParent()) ||
          cast<Instruction>(EU.User)->getParent()->isLandingPad())))
      continue;

    // We only add extract cost once for the same scalar.
    if (!isa_and_nonnull<InsertElementInst>(EU.User) &&
        !ExtractCostCalculated.insert(EU.Scalar).second)
      continue;

    // No extract cost for vector "scalar"
    if (isa<FixedVectorType>(EU.Scalar->getType()))
      continue;

    // If found user is an insertelement, do not calculate extract cost but try
    // to detect it as a final shuffled/identity match.
    if (auto *VU = dyn_cast_or_null<InsertElementInst>(EU.User);
        VU && VU->getOperand(1) == EU.Scalar) {
      if (auto *FTy = dyn_cast<FixedVectorType>(VU->getType())) {
        if (!UsedInserts.insert(VU).second)
          continue;
        std::optional<unsigned> InsertIdx = getElementIndex(VU);
        if (InsertIdx) {
          const TreeEntry *ScalarTE = getTreeEntry(EU.Scalar);
          auto *It = find_if(
              ShuffledInserts,
              [this, VU](const ShuffledInsertData<const TreeEntry *> &Data) {
                // Checks if 2 insertelements are from the same buildvector.
                InsertElementInst *VecInsert = Data.InsertElements.front();
                return areTwoInsertFromSameBuildVector(
                    VU, VecInsert, [this](InsertElementInst *II) -> Value * {
                      Value *Op0 = II->getOperand(0);
                      if (getTreeEntry(II) && !getTreeEntry(Op0))
                        return nullptr;
                      return Op0;
                    });
              });
          int VecId = -1;
          if (It == ShuffledInserts.end()) {
            auto &Data = ShuffledInserts.emplace_back();
            Data.InsertElements.emplace_back(VU);
            DemandedElts.push_back(APInt::getZero(FTy->getNumElements()));
            VecId = ShuffledInserts.size() - 1;
            auto It = MinBWs.find(ScalarTE);
            if (It != MinBWs.end() &&
                VectorCasts
                    .insert(std::make_pair(ScalarTE, FTy->getElementType()))
                    .second) {
              unsigned BWSz = It->second.first;
              unsigned DstBWSz = DL->getTypeSizeInBits(FTy->getElementType());
              unsigned VecOpcode;
              if (DstBWSz < BWSz)
                VecOpcode = Instruction::Trunc;
              else
                VecOpcode =
                    It->second.second ? Instruction::SExt : Instruction::ZExt;
              TTI::TargetCostKind CostKind = TTI::TCK_RecipThroughput;
              InstructionCost C = TTI->getCastInstrCost(
                  VecOpcode, FTy,
                  getWidenedType(IntegerType::get(FTy->getContext(), BWSz),
                                 FTy->getNumElements()),
                  TTI::CastContextHint::None, CostKind);
              LLVM_DEBUG(dbgs() << "SLP: Adding cost " << C
                                << " for extending externally used vector with "
                                   "non-equal minimum bitwidth.\n");
              Cost += C;
            }
          } else {
            if (isFirstInsertElement(VU, It->InsertElements.front()))
              It->InsertElements.front() = VU;
            VecId = std::distance(ShuffledInserts.begin(), It);
          }
          int InIdx = *InsertIdx;
          SmallVectorImpl<int> &Mask =
              ShuffledInserts[VecId].ValueMasks[ScalarTE];
          if (Mask.empty())
            Mask.assign(FTy->getNumElements(), PoisonMaskElem);
          Mask[InIdx] = EU.Lane;
          DemandedElts[VecId].setBit(InIdx);
          continue;
        }
      }
    }

    TTI::TargetCostKind CostKind = TTI::TCK_RecipThroughput;
    // If we plan to rewrite the tree in a smaller type, we will need to sign
    // extend the extracted value back to the original type. Here, we account
    // for the extract and the added cost of the sign extend if needed.
    InstructionCost ExtraCost = TTI::TCC_Free;
    auto *VecTy = getWidenedType(EU.Scalar->getType(), BundleWidth);
    const TreeEntry *Entry = getTreeEntry(EU.Scalar);
    auto It = MinBWs.find(Entry);
    if (It != MinBWs.end()) {
      auto *MinTy = IntegerType::get(F->getContext(), It->second.first);
      unsigned Extend =
          It->second.second ? Instruction::SExt : Instruction::ZExt;
      VecTy = getWidenedType(MinTy, BundleWidth);
      ExtraCost = TTI->getExtractWithExtendCost(Extend, EU.Scalar->getType(),
                                                VecTy, EU.Lane);
    } else {
      ExtraCost = TTI->getVectorInstrCost(Instruction::ExtractElement, VecTy,
                                          CostKind, EU.Lane);
    }
    // Leave the scalar instructions as is if they are cheaper than extracts.
    if (Entry->Idx != 0 || Entry->getOpcode() == Instruction::GetElementPtr ||
        Entry->getOpcode() == Instruction::Load) {
      // Checks if the user of the external scalar is phi in loop body.
      auto IsPhiInLoop = [&](const ExternalUser &U) {
        if (auto *Phi = dyn_cast_if_present<PHINode>(U.User)) {
          auto *I = cast<Instruction>(U.Scalar);
          const Loop *L = LI->getLoopFor(Phi->getParent());
          return L && (Phi->getParent() == I->getParent() ||
                       L == LI->getLoopFor(I->getParent()));
        }
        return false;
      };
      if (!ValueToExtUses) {
        ValueToExtUses.emplace();
        for_each(enumerate(ExternalUses), [&](const auto &P) {
          // Ignore phis in loops.
          if (IsPhiInLoop(P.value()))
            return;

          ValueToExtUses->try_emplace(P.value().Scalar, P.index());
        });
      }
      // Can use original instruction, if no operands vectorized or they are
      // marked as externally used already.
      auto *Inst = cast<Instruction>(EU.Scalar);
      bool CanBeUsedAsScalar = all_of(Inst->operands(), [&](Value *V) {
        if (!getTreeEntry(V)) {
          // Some extractelements might be not vectorized, but
          // transformed into shuffle and removed from the function,
          // consider it here.
          if (auto *EE = dyn_cast<ExtractElementInst>(V))
            return !EE->hasOneUse() || !MustGather.contains(EE);
          return true;
        }
        return ValueToExtUses->contains(V);
      });
      if (CanBeUsedAsScalar) {
        InstructionCost ScalarCost = TTI->getInstructionCost(Inst, CostKind);
        bool KeepScalar = ScalarCost <= ExtraCost;
        // Try to keep original scalar if the user is the phi node from the same
        // block as the root phis, currently vectorized. It allows to keep
        // better ordering info of PHIs, being vectorized currently.
        bool IsProfitablePHIUser =
            (KeepScalar || (ScalarCost - ExtraCost <= TTI::TCC_Basic &&
                            VectorizableTree.front()->Scalars.size() > 2)) &&
            VectorizableTree.front()->getOpcode() == Instruction::PHI &&
            !Inst->hasNUsesOrMore(UsesLimit) &&
            none_of(Inst->users(),
                    [&](User *U) {
                      auto *PHIUser = dyn_cast<PHINode>(U);
                      return (!PHIUser ||
                              PHIUser->getParent() !=
                                  cast<Instruction>(
                                      VectorizableTree.front()->getMainOp())
                                      ->getParent()) &&
                             !getTreeEntry(U);
                    }) &&
            count_if(Entry->Scalars, [&](Value *V) {
              return ValueToExtUses->contains(V);
            }) <= 2;
        if (IsProfitablePHIUser) {
          KeepScalar = true;
        } else if (KeepScalar && ScalarCost != TTI::TCC_Free &&
                   ExtraCost - ScalarCost <= TTI::TCC_Basic &&
                   (GatheredLoadsEntriesFirst == NoGatheredLoads ||
                    Entry->Idx < GatheredLoadsEntriesFirst)) {
          unsigned ScalarUsesCount = count_if(Entry->Scalars, [&](Value *V) {
            return ValueToExtUses->contains(V);
          });
          auto It = ExtractsCount.find(Entry);
          if (It != ExtractsCount.end()) {
            assert(ScalarUsesCount >= It->getSecond().size() &&
                   "Expected total number of external uses not less than "
                   "number of scalar uses.");
            ScalarUsesCount -= It->getSecond().size();
          }
          // Keep original scalar if number of externally used instructions in
          // the same entry is not power of 2. It may help to do some extra
          // vectorization for now.
          KeepScalar = ScalarUsesCount <= 1 || !has_single_bit(ScalarUsesCount);
        }
        if (KeepScalar) {
          ExternalUsesAsOriginalScalar.insert(EU.Scalar);
          for_each(Inst->operands(), [&](Value *V) {
            auto It = ValueToExtUses->find(V);
            if (It != ValueToExtUses->end()) {
              // Replace all uses to avoid compiler crash.
              ExternalUses[It->second].User = nullptr;
            }
          });
          ExtraCost = ScalarCost;
          if (!IsPhiInLoop(EU))
            ExtractsCount[Entry].insert(Inst);
        }
      }
    }

    ExtractCost += ExtraCost;
  }
  // Add reduced value cost, if resized.
  if (!VectorizedVals.empty()) {
    const TreeEntry &Root = *VectorizableTree.front();
    auto BWIt = MinBWs.find(&Root);
    if (BWIt != MinBWs.end()) {
      Type *DstTy = Root.Scalars.front()->getType();
      unsigned OriginalSz = DL->getTypeSizeInBits(DstTy);
      unsigned SrcSz =
          ReductionBitWidth == 0 ? BWIt->second.first : ReductionBitWidth;
      if (OriginalSz != SrcSz) {
        unsigned Opcode = Instruction::Trunc;
        if (OriginalSz > SrcSz)
          Opcode = BWIt->second.second ? Instruction::SExt : Instruction::ZExt;
        Type *SrcTy = IntegerType::get(DstTy->getContext(), SrcSz);
        Cost += TTI->getCastInstrCost(Opcode, DstTy, SrcTy,
                                      TTI::CastContextHint::None,
                                      TTI::TCK_RecipThroughput);
      }
    }
  }

  InstructionCost SpillCost = getSpillCost();
  Cost += SpillCost + ExtractCost;
  auto &&ResizeToVF = [this, &Cost](const TreeEntry *TE, ArrayRef<int> Mask,
                                    bool) {
    InstructionCost C = 0;
    unsigned VF = Mask.size();
    unsigned VecVF = TE->getVectorFactor();
    if (VF != VecVF &&
        (any_of(Mask, [VF](int Idx) { return Idx >= static_cast<int>(VF); }) ||
         !ShuffleVectorInst::isIdentityMask(Mask, VF))) {
      SmallVector<int> OrigMask(VecVF, PoisonMaskElem);
      std::copy(Mask.begin(), std::next(Mask.begin(), std::min(VF, VecVF)),
                OrigMask.begin());
      C = ::getShuffleCost(*TTI, TTI::SK_PermuteSingleSrc,
                           getWidenedType(TE->getMainOp()->getType(), VecVF),
                           OrigMask);
      LLVM_DEBUG(
          dbgs() << "SLP: Adding cost " << C
                 << " for final shuffle of insertelement external users.\n";
          TE->dump(); dbgs() << "SLP: Current total cost = " << Cost << "\n");
      Cost += C;
      return std::make_pair(TE, true);
    }
    return std::make_pair(TE, false);
  };
  // Calculate the cost of the reshuffled vectors, if any.
  for (int I = 0, E = ShuffledInserts.size(); I < E; ++I) {
    Value *Base = ShuffledInserts[I].InsertElements.front()->getOperand(0);
    auto Vector = ShuffledInserts[I].ValueMasks.takeVector();
    unsigned VF = 0;
    auto EstimateShufflesCost = [&](ArrayRef<int> Mask,
                                    ArrayRef<const TreeEntry *> TEs) {
      assert((TEs.size() == 1 || TEs.size() == 2) &&
             "Expected exactly 1 or 2 tree entries.");
      if (TEs.size() == 1) {
        if (VF == 0)
          VF = TEs.front()->getVectorFactor();
        auto *FTy = getWidenedType(TEs.back()->Scalars.front()->getType(), VF);
        if (!ShuffleVectorInst::isIdentityMask(Mask, VF) &&
            !all_of(enumerate(Mask), [=](const auto &Data) {
              return Data.value() == PoisonMaskElem ||
                     (Data.index() < VF &&
                      static_cast<int>(Data.index()) == Data.value());
            })) {
          InstructionCost C =
              ::getShuffleCost(*TTI, TTI::SK_PermuteSingleSrc, FTy, Mask);
          LLVM_DEBUG(dbgs() << "SLP: Adding cost " << C
                            << " for final shuffle of insertelement "
                               "external users.\n";
                     TEs.front()->dump();
                     dbgs() << "SLP: Current total cost = " << Cost << "\n");
          Cost += C;
        }
      } else {
        if (VF == 0) {
          if (TEs.front() &&
              TEs.front()->getVectorFactor() == TEs.back()->getVectorFactor())
            VF = TEs.front()->getVectorFactor();
          else
            VF = Mask.size();
        }
        auto *FTy = getWidenedType(TEs.back()->Scalars.front()->getType(), VF);
        InstructionCost C =
            ::getShuffleCost(*TTI, TTI::SK_PermuteTwoSrc, FTy, Mask);
        LLVM_DEBUG(dbgs() << "SLP: Adding cost " << C
                          << " for final shuffle of vector node and external "
                             "insertelement users.\n";
                   if (TEs.front()) { TEs.front()->dump(); } TEs.back()->dump();
                   dbgs() << "SLP: Current total cost = " << Cost << "\n");
        Cost += C;
      }
      VF = Mask.size();
      return TEs.back();
    };
    (void)performExtractsShuffleAction<const TreeEntry>(
        MutableArrayRef(Vector.data(), Vector.size()), Base,
        [](const TreeEntry *E) { return E->getVectorFactor(); }, ResizeToVF,
        EstimateShufflesCost);
    InstructionCost InsertCost = TTI->getScalarizationOverhead(
        cast<FixedVectorType>(
            ShuffledInserts[I].InsertElements.front()->getType()),
        DemandedElts[I],
        /*Insert*/ true, /*Extract*/ false, TTI::TCK_RecipThroughput);
    Cost -= InsertCost;
  }

  // Add the cost for reduced value resize (if required).
  if (ReductionBitWidth != 0) {
    assert(UserIgnoreList && "Expected reduction tree.");
    const TreeEntry &E = *VectorizableTree.front();
    auto It = MinBWs.find(&E);
    if (It != MinBWs.end() && It->second.first != ReductionBitWidth) {
      unsigned SrcSize = It->second.first;
      unsigned DstSize = ReductionBitWidth;
      unsigned Opcode = Instruction::Trunc;
      if (SrcSize < DstSize)
        Opcode = It->second.second ? Instruction::SExt : Instruction::ZExt;
      auto *SrcVecTy =
          getWidenedType(Builder.getIntNTy(SrcSize), E.getVectorFactor());
      auto *DstVecTy =
          getWidenedType(Builder.getIntNTy(DstSize), E.getVectorFactor());
      TTI::CastContextHint CCH = getCastContextHint(E);
      InstructionCost CastCost;
      switch (E.getOpcode()) {
      case Instruction::SExt:
      case Instruction::ZExt:
      case Instruction::Trunc: {
        const TreeEntry *OpTE = getOperandEntry(&E, 0);
        CCH = getCastContextHint(*OpTE);
        break;
      }
      default:
        break;
      }
      CastCost += TTI->getCastInstrCost(Opcode, DstVecTy, SrcVecTy, CCH,
                                        TTI::TCK_RecipThroughput);
      Cost += CastCost;
      LLVM_DEBUG(dbgs() << "SLP: Adding cost " << CastCost
                        << " for final resize for reduction from " << SrcVecTy
                        << " to " << DstVecTy << "\n";
                 dbgs() << "SLP: Current total cost = " << Cost << "\n");
    }
  }

#ifndef NDEBUG
  SmallString<256> Str;
  {
    raw_svector_ostream OS(Str);
    OS << "SLP: Spill Cost = " << SpillCost << ".\n"
       << "SLP: Extract Cost = " << ExtractCost << ".\n"
       << "SLP: Total Cost = " << Cost << ".\n";
  }
  LLVM_DEBUG(dbgs() << Str);
  if (ViewSLPTree)
    ViewGraph(this, "SLP" + F->getName(), false, Str);
#endif

  return Cost;
}

/// Tries to find extractelement instructions with constant indices from fixed
/// vector type and gather such instructions into a bunch, which highly likely
/// might be detected as a shuffle of 1 or 2 input vectors. If this attempt was
/// successful, the matched scalars are replaced by poison values in \p VL for
/// future analysis.
std::optional<TTI::ShuffleKind>
BoUpSLP::tryToGatherSingleRegisterExtractElements(
    MutableArrayRef<Value *> VL, SmallVectorImpl<int> &Mask) const {
  // Scan list of gathered scalars for extractelements that can be represented
  // as shuffles.
  MapVector<Value *, SmallVector<int>> VectorOpToIdx;
  SmallVector<int> UndefVectorExtracts;
  for (int I = 0, E = VL.size(); I < E; ++I) {
    auto *EI = dyn_cast<ExtractElementInst>(VL[I]);
    if (!EI) {
      if (isa<UndefValue>(VL[I]))
        UndefVectorExtracts.push_back(I);
      continue;
    }
    auto *VecTy = dyn_cast<FixedVectorType>(EI->getVectorOperandType());
    if (!VecTy || !isa<ConstantInt, UndefValue>(EI->getIndexOperand()))
      continue;
    std::optional<unsigned> Idx = getExtractIndex(EI);
    // Undefined index.
    if (!Idx) {
      UndefVectorExtracts.push_back(I);
      continue;
    }
    if (Idx >= VecTy->getNumElements()) {
      UndefVectorExtracts.push_back(I);
      continue;
    }
    SmallBitVector ExtractMask(VecTy->getNumElements(), true);
    ExtractMask.reset(*Idx);
    if (isUndefVector(EI->getVectorOperand(), ExtractMask).all()) {
      UndefVectorExtracts.push_back(I);
      continue;
    }
    VectorOpToIdx[EI->getVectorOperand()].push_back(I);
  }
  // Sort the vector operands by the maximum number of uses in extractelements.
  SmallVector<std::pair<Value *, SmallVector<int>>> Vectors =
      VectorOpToIdx.takeVector();
  stable_sort(Vectors, [](const auto &P1, const auto &P2) {
    return P1.second.size() > P2.second.size();
  });
  // Find the best pair of the vectors or a single vector.
  const int UndefSz = UndefVectorExtracts.size();
  unsigned SingleMax = 0;
  unsigned PairMax = 0;
  if (!Vectors.empty()) {
    SingleMax = Vectors.front().second.size() + UndefSz;
    if (Vectors.size() > 1) {
      auto *ItNext = std::next(Vectors.begin());
      PairMax = SingleMax + ItNext->second.size();
    }
  }
  if (SingleMax == 0 && PairMax == 0 && UndefSz == 0)
    return std::nullopt;
  // Check if better to perform a shuffle of 2 vectors or just of a single
  // vector.
  SmallVector<Value *> SavedVL(VL.begin(), VL.end());
  SmallVector<Value *> GatheredExtracts(
      VL.size(), PoisonValue::get(VL.front()->getType()));
  if (SingleMax >= PairMax && SingleMax) {
    for (int Idx : Vectors.front().second)
      std::swap(GatheredExtracts[Idx], VL[Idx]);
  } else if (!Vectors.empty()) {
    for (unsigned Idx : {0, 1})
      for (int Idx : Vectors[Idx].second)
        std::swap(GatheredExtracts[Idx], VL[Idx]);
  }
  // Add extracts from undefs too.
  for (int Idx : UndefVectorExtracts)
    std::swap(GatheredExtracts[Idx], VL[Idx]);
  // Check that gather of extractelements can be represented as just a
  // shuffle of a single/two vectors the scalars are extracted from.
  std::optional<TTI::ShuffleKind> Res =
      isFixedVectorShuffle(GatheredExtracts, Mask);
  if (!Res || all_of(Mask, [](int Idx) { return Idx == PoisonMaskElem; })) {
    // TODO: try to check other subsets if possible.
    // Restore the original VL if attempt was not successful.
    copy(SavedVL, VL.begin());
    return std::nullopt;
  }
  // Restore unused scalars from mask, if some of the extractelements were not
  // selected for shuffle.
  for (int I = 0, E = GatheredExtracts.size(); I < E; ++I) {
    if (Mask[I] == PoisonMaskElem && !isa<PoisonValue>(GatheredExtracts[I]) &&
        isa<UndefValue>(GatheredExtracts[I])) {
      std::swap(VL[I], GatheredExtracts[I]);
      continue;
    }
    auto *EI = dyn_cast<ExtractElementInst>(VL[I]);
    if (!EI || !isa<FixedVectorType>(EI->getVectorOperandType()) ||
        !isa<ConstantInt, UndefValue>(EI->getIndexOperand()) ||
        is_contained(UndefVectorExtracts, I))
      continue;
  }
  return Res;
}

/// Tries to find extractelement instructions with constant indices from fixed
/// vector type and gather such instructions into a bunch, which highly likely
/// might be detected as a shuffle of 1 or 2 input vectors. If this attempt was
/// successful, the matched scalars are replaced by poison values in \p VL for
/// future analysis.
SmallVector<std::optional<TTI::ShuffleKind>>
BoUpSLP::tryToGatherExtractElements(SmallVectorImpl<Value *> &VL,
                                    SmallVectorImpl<int> &Mask,
                                    unsigned NumParts) const {
  assert(NumParts > 0 && "NumParts expected be greater than or equal to 1.");
  SmallVector<std::optional<TTI::ShuffleKind>> ShufflesRes(NumParts);
  Mask.assign(VL.size(), PoisonMaskElem);
  unsigned SliceSize = getPartNumElems(VL.size(), NumParts);
  for (unsigned Part : seq<unsigned>(NumParts)) {
    // Scan list of gathered scalars for extractelements that can be represented
    // as shuffles.
    MutableArrayRef<Value *> SubVL = MutableArrayRef(VL).slice(
        Part * SliceSize, getNumElems(VL.size(), SliceSize, Part));
    SmallVector<int> SubMask;
    std::optional<TTI::ShuffleKind> Res =
        tryToGatherSingleRegisterExtractElements(SubVL, SubMask);
    ShufflesRes[Part] = Res;
    copy(SubMask, std::next(Mask.begin(), Part * SliceSize));
  }
  if (none_of(ShufflesRes, [](const std::optional<TTI::ShuffleKind> &Res) {
        return Res.has_value();
      }))
    ShufflesRes.clear();
  return ShufflesRes;
}

std::optional<TargetTransformInfo::ShuffleKind>
BoUpSLP::isGatherShuffledSingleRegisterEntry(
    const TreeEntry *TE, ArrayRef<Value *> VL, MutableArrayRef<int> Mask,
    SmallVectorImpl<const TreeEntry *> &Entries, unsigned Part, bool ForOrder) {
  Entries.clear();
  // TODO: currently checking only for Scalars in the tree entry, need to count
  // reused elements too for better cost estimation.
  const EdgeInfo &TEUseEI = TE == VectorizableTree.front().get()
                                ? EdgeInfo(const_cast<TreeEntry *>(TE), 0)
                                : TE->UserTreeIndices.front();
  const Instruction *TEInsertPt = &getLastInstructionInBundle(TEUseEI.UserTE);
  const BasicBlock *TEInsertBlock = nullptr;
  // Main node of PHI entries keeps the correct order of operands/incoming
  // blocks.
  if (auto *PHI = dyn_cast<PHINode>(TEUseEI.UserTE->getMainOp())) {
    TEInsertBlock = PHI->getIncomingBlock(TEUseEI.EdgeIdx);
    TEInsertPt = TEInsertBlock->getTerminator();
  } else {
    TEInsertBlock = TEInsertPt->getParent();
  }
  if (!DT->isReachableFromEntry(TEInsertBlock))
    return std::nullopt;
  auto *NodeUI = DT->getNode(TEInsertBlock);
  assert(NodeUI && "Should only process reachable instructions");
  SmallPtrSet<Value *, 4> GatheredScalars(VL.begin(), VL.end());
  auto CheckOrdering = [&](const Instruction *InsertPt) {
    // Argument InsertPt is an instruction where vector code for some other
    // tree entry (one that shares one or more scalars with TE) is going to be
    // generated. This lambda returns true if insertion point of vector code
    // for the TE dominates that point (otherwise dependency is the other way
    // around). The other node is not limited to be of a gather kind. Gather
    // nodes are not scheduled and their vector code is inserted before their
    // first user. If user is PHI, that is supposed to be at the end of a
    // predecessor block. Otherwise it is the last instruction among scalars of
    // the user node. So, instead of checking dependency between instructions
    // themselves, we check dependency between their insertion points for vector
    // code (since each scalar instruction ends up as a lane of a vector
    // instruction).
    const BasicBlock *InsertBlock = InsertPt->getParent();
    auto *NodeEUI = DT->getNode(InsertBlock);
    if (!NodeEUI)
      return false;
    assert((NodeUI == NodeEUI) ==
               (NodeUI->getDFSNumIn() == NodeEUI->getDFSNumIn()) &&
           "Different nodes should have different DFS numbers");
    // Check the order of the gather nodes users.
    if (TEInsertPt->getParent() != InsertBlock &&
        (DT->dominates(NodeUI, NodeEUI) || !DT->dominates(NodeEUI, NodeUI)))
      return false;
    if (TEInsertPt->getParent() == InsertBlock &&
        TEInsertPt->comesBefore(InsertPt))
      return false;
    return true;
  };
  // Find all tree entries used by the gathered values. If no common entries
  // found - not a shuffle.
  // Here we build a set of tree nodes for each gathered value and trying to
  // find the intersection between these sets. If we have at least one common
  // tree node for each gathered value - we have just a permutation of the
  // single vector. If we have 2 different sets, we're in situation where we
  // have a permutation of 2 input vectors.
  SmallVector<SmallPtrSet<const TreeEntry *, 4>> UsedTEs;
  DenseMap<Value *, int> UsedValuesEntry;
  for (Value *V : VL) {
    if (isConstant(V))
      continue;
    // Build a list of tree entries where V is used.
    SmallPtrSet<const TreeEntry *, 4> VToTEs;
    for (const TreeEntry *TEPtr : ValueToGatherNodes.find(V)->second) {
      if (TEPtr == TE)
        continue;
      assert(any_of(TEPtr->Scalars,
                    [&](Value *V) { return GatheredScalars.contains(V); }) &&
             "Must contain at least single gathered value.");
      assert(TEPtr->UserTreeIndices.size() == 1 &&
             "Expected only single user of a gather node.");
      const EdgeInfo &UseEI = TEPtr->UserTreeIndices.front();

      PHINode *UserPHI = dyn_cast<PHINode>(UseEI.UserTE->getMainOp());
      const Instruction *InsertPt =
          UserPHI ? UserPHI->getIncomingBlock(UseEI.EdgeIdx)->getTerminator()
                  : &getLastInstructionInBundle(UseEI.UserTE);
      if (TEInsertPt == InsertPt) {
        // If 2 gathers are operands of the same entry (regardless of whether
        // user is PHI or else), compare operands indices, use the earlier one
        // as the base.
        if (TEUseEI.UserTE == UseEI.UserTE && TEUseEI.EdgeIdx < UseEI.EdgeIdx)
          continue;
        // If the user instruction is used for some reason in different
        // vectorized nodes - make it depend on index.
        if (TEUseEI.UserTE != UseEI.UserTE &&
            TEUseEI.UserTE->Idx < UseEI.UserTE->Idx)
          continue;
      }

      // Check if the user node of the TE comes after user node of TEPtr,
      // otherwise TEPtr depends on TE.
      if ((TEInsertBlock != InsertPt->getParent() ||
           TEUseEI.EdgeIdx < UseEI.EdgeIdx || TEUseEI.UserTE != UseEI.UserTE) &&
          !CheckOrdering(InsertPt))
        continue;
      VToTEs.insert(TEPtr);
    }
    if (const TreeEntry *VTE = getTreeEntry(V)) {
      if (ForOrder && VTE->Idx < GatheredLoadsEntriesFirst) {
        if (VTE->State != TreeEntry::Vectorize) {
          auto It = MultiNodeScalars.find(V);
          if (It == MultiNodeScalars.end())
            continue;
          VTE = *It->getSecond().begin();
          // Iterate through all vectorized nodes.
          auto *MIt = find_if(It->getSecond(), [](const TreeEntry *MTE) {
            return MTE->State == TreeEntry::Vectorize;
          });
          if (MIt == It->getSecond().end())
            continue;
          VTE = *MIt;
        }
      }
      Instruction &LastBundleInst = getLastInstructionInBundle(VTE);
      if (&LastBundleInst == TEInsertPt || !CheckOrdering(&LastBundleInst))
        continue;
      VToTEs.insert(VTE);
    }
    if (VToTEs.empty())
      continue;
    if (UsedTEs.empty()) {
      // The first iteration, just insert the list of nodes to vector.
      UsedTEs.push_back(VToTEs);
      UsedValuesEntry.try_emplace(V, 0);
    } else {
      // Need to check if there are any previously used tree nodes which use V.
      // If there are no such nodes, consider that we have another one input
      // vector.
      SmallPtrSet<const TreeEntry *, 4> SavedVToTEs(VToTEs);
      unsigned Idx = 0;
      for (SmallPtrSet<const TreeEntry *, 4> &Set : UsedTEs) {
        // Do we have a non-empty intersection of previously listed tree entries
        // and tree entries using current V?
        set_intersect(VToTEs, Set);
        if (!VToTEs.empty()) {
          // Yes, write the new subset and continue analysis for the next
          // scalar.
          Set.swap(VToTEs);
          break;
        }
        VToTEs = SavedVToTEs;
        ++Idx;
      }
      // No non-empty intersection found - need to add a second set of possible
      // source vectors.
      if (Idx == UsedTEs.size()) {
        // If the number of input vectors is greater than 2 - not a permutation,
        // fallback to the regular gather.
        // TODO: support multiple reshuffled nodes.
        if (UsedTEs.size() == 2)
          continue;
        UsedTEs.push_back(SavedVToTEs);
        Idx = UsedTEs.size() - 1;
      }
      UsedValuesEntry.try_emplace(V, Idx);
    }
  }

  if (UsedTEs.empty()) {
    Entries.clear();
    return std::nullopt;
  }

  unsigned VF = 0;
  if (UsedTEs.size() == 1) {
    // Keep the order to avoid non-determinism.
    SmallVector<const TreeEntry *> FirstEntries(UsedTEs.front().begin(),
                                                UsedTEs.front().end());
    sort(FirstEntries, [](const TreeEntry *TE1, const TreeEntry *TE2) {
      return TE1->Idx < TE2->Idx;
    });
    // Try to find the perfect match in another gather node at first.
    auto *It = find_if(FirstEntries, [=](const TreeEntry *EntryPtr) {
      return EntryPtr->isSame(VL) || EntryPtr->isSame(TE->Scalars);
    });
    if (It != FirstEntries.end() &&
        ((*It)->getVectorFactor() == VL.size() ||
         ((*It)->getVectorFactor() == TE->Scalars.size() &&
          TE->ReuseShuffleIndices.size() == VL.size() &&
          (*It)->isSame(TE->Scalars)))) {
      Entries.push_back(*It);
      if ((*It)->getVectorFactor() == VL.size()) {
        std::iota(std::next(Mask.begin(), Part * VL.size()),
                  std::next(Mask.begin(), (Part + 1) * VL.size()), 0);
      } else {
        SmallVector<int> CommonMask = TE->getCommonMask();
        copy(CommonMask, Mask.begin());
      }
      // Clear undef scalars.
      for (int I = 0, Sz = VL.size(); I < Sz; ++I)
        if (isa<PoisonValue>(VL[I]))
          Mask[I] = PoisonMaskElem;
      return TargetTransformInfo::SK_PermuteSingleSrc;
    }
    // No perfect match, just shuffle, so choose the first tree node from the
    // tree.
    Entries.push_back(FirstEntries.front());
  } else {
    // Try to find nodes with the same vector factor.
    assert(UsedTEs.size() == 2 && "Expected at max 2 permuted entries.");
    // Keep the order of tree nodes to avoid non-determinism.
    DenseMap<int, const TreeEntry *> VFToTE;
    for (const TreeEntry *TE : UsedTEs.front()) {
      unsigned VF = TE->getVectorFactor();
      auto It = VFToTE.find(VF);
      if (It != VFToTE.end()) {
        if (It->second->Idx > TE->Idx)
          It->getSecond() = TE;
        continue;
      }
      VFToTE.try_emplace(VF, TE);
    }
    // Same, keep the order to avoid non-determinism.
    SmallVector<const TreeEntry *> SecondEntries(UsedTEs.back().begin(),
                                                 UsedTEs.back().end());
    sort(SecondEntries, [](const TreeEntry *TE1, const TreeEntry *TE2) {
      return TE1->Idx < TE2->Idx;
    });
    for (const TreeEntry *TE : SecondEntries) {
      auto It = VFToTE.find(TE->getVectorFactor());
      if (It != VFToTE.end()) {
        VF = It->first;
        Entries.push_back(It->second);
        Entries.push_back(TE);
        break;
      }
    }
    // No 2 source vectors with the same vector factor - just choose 2 with max
    // index.
    if (Entries.empty()) {
      Entries.push_back(*llvm::max_element(
          UsedTEs.front(), [](const TreeEntry *TE1, const TreeEntry *TE2) {
            return TE1->Idx < TE2->Idx;
          }));
      Entries.push_back(SecondEntries.front());
      VF = std::max(Entries.front()->getVectorFactor(),
                    Entries.back()->getVectorFactor());
    }
  }

  bool IsSplatOrUndefs = isSplat(VL) || all_of(VL, IsaPred<UndefValue>);
  // Checks if the 2 PHIs are compatible in terms of high possibility to be
  // vectorized.
  auto AreCompatiblePHIs = [&](Value *V, Value *V1) {
    auto *PHI = cast<PHINode>(V);
    auto *PHI1 = cast<PHINode>(V1);
    // Check that all incoming values are compatible/from same parent (if they
    // are instructions).
    // The incoming values are compatible if they all are constants, or
    // instruction with the same/alternate opcodes from the same basic block.
    for (int I = 0, E = PHI->getNumIncomingValues(); I < E; ++I) {
      Value *In = PHI->getIncomingValue(I);
      Value *In1 = PHI1->getIncomingValue(I);
      if (isConstant(In) && isConstant(In1))
        continue;
      if (!getSameOpcode({In, In1}, *TLI).getOpcode())
        return false;
      if (cast<Instruction>(In)->getParent() !=
          cast<Instruction>(In1)->getParent())
        return false;
    }
    return true;
  };
  // Check if the value can be ignored during analysis for shuffled gathers.
  // We suppose it is better to ignore instruction, which do not form splats,
  // are not vectorized/not extractelements (these instructions will be handled
  // by extractelements processing) or may form vector node in future.
  auto MightBeIgnored = [=](Value *V) {
    auto *I = dyn_cast<Instruction>(V);
    return I && !IsSplatOrUndefs && !ScalarToTreeEntry.count(I) &&
           !isVectorLikeInstWithConstOps(I) &&
           !areAllUsersVectorized(I, UserIgnoreList) && isSimple(I);
  };
  // Check that the neighbor instruction may form a full vector node with the
  // current instruction V. It is possible, if they have same/alternate opcode
  // and same parent basic block.
  auto NeighborMightBeIgnored = [&](Value *V, int Idx) {
    Value *V1 = VL[Idx];
    bool UsedInSameVTE = false;
    auto It = UsedValuesEntry.find(V1);
    if (It != UsedValuesEntry.end())
      UsedInSameVTE = It->second == UsedValuesEntry.find(V)->second;
    return V != V1 && MightBeIgnored(V1) && !UsedInSameVTE &&
           getSameOpcode({V, V1}, *TLI).getOpcode() &&
           cast<Instruction>(V)->getParent() ==
               cast<Instruction>(V1)->getParent() &&
           (!isa<PHINode>(V1) || AreCompatiblePHIs(V, V1));
  };
  // Build a shuffle mask for better cost estimation and vector emission.
  SmallBitVector UsedIdxs(Entries.size());
  SmallVector<std::pair<unsigned, int>> EntryLanes;
  for (int I = 0, E = VL.size(); I < E; ++I) {
    Value *V = VL[I];
    auto It = UsedValuesEntry.find(V);
    if (It == UsedValuesEntry.end())
      continue;
    // Do not try to shuffle scalars, if they are constants, or instructions
    // that can be vectorized as a result of the following vector build
    // vectorization.
    if (isConstant(V) || (MightBeIgnored(V) &&
                          ((I > 0 && NeighborMightBeIgnored(V, I - 1)) ||
                           (I != E - 1 && NeighborMightBeIgnored(V, I + 1)))))
      continue;
    unsigned Idx = It->second;
    EntryLanes.emplace_back(Idx, I);
    UsedIdxs.set(Idx);
  }
  // Iterate through all shuffled scalars and select entries, which can be used
  // for final shuffle.
  SmallVector<const TreeEntry *> TempEntries;
  for (unsigned I = 0, Sz = Entries.size(); I < Sz; ++I) {
    if (!UsedIdxs.test(I))
      continue;
    // Fix the entry number for the given scalar. If it is the first entry, set
    // Pair.first to 0, otherwise to 1 (currently select at max 2 nodes).
    // These indices are used when calculating final shuffle mask as the vector
    // offset.
    for (std::pair<unsigned, int> &Pair : EntryLanes)
      if (Pair.first == I)
        Pair.first = TempEntries.size();
    TempEntries.push_back(Entries[I]);
  }
  Entries.swap(TempEntries);
  if (EntryLanes.size() == Entries.size() &&
      !VL.equals(ArrayRef(TE->Scalars)
                     .slice(Part * VL.size(),
                            std::min<int>(VL.size(), TE->Scalars.size())))) {
    // We may have here 1 or 2 entries only. If the number of scalars is equal
    // to the number of entries, no need to do the analysis, it is not very
    // profitable. Since VL is not the same as TE->Scalars, it means we already
    // have some shuffles before. Cut off not profitable case.
    Entries.clear();
    return std::nullopt;
  }
  // Build the final mask, check for the identity shuffle, if possible.
  bool IsIdentity = Entries.size() == 1;
  // Pair.first is the offset to the vector, while Pair.second is the index of
  // scalar in the list.
  for (const std::pair<unsigned, int> &Pair : EntryLanes) {
    unsigned Idx = Part * VL.size() + Pair.second;
    Mask[Idx] =
        Pair.first * VF +
        (ForOrder ? std::distance(
                        Entries[Pair.first]->Scalars.begin(),
                        find(Entries[Pair.first]->Scalars, VL[Pair.second]))
                  : Entries[Pair.first]->findLaneForValue(VL[Pair.second]));
    IsIdentity &= Mask[Idx] == Pair.second;
  }
  switch (Entries.size()) {
  case 1:
    if (IsIdentity || EntryLanes.size() > 1 || VL.size() <= 2)
      return TargetTransformInfo::SK_PermuteSingleSrc;
    break;
  case 2:
    if (EntryLanes.size() > 2 || VL.size() <= 2)
      return TargetTransformInfo::SK_PermuteTwoSrc;
    break;
  default:
    break;
  }
  Entries.clear();
  // Clear the corresponding mask elements.
  std::fill(std::next(Mask.begin(), Part * VL.size()),
            std::next(Mask.begin(), (Part + 1) * VL.size()), PoisonMaskElem);
  return std::nullopt;
}

SmallVector<std::optional<TargetTransformInfo::ShuffleKind>>
BoUpSLP::isGatherShuffledEntry(
    const TreeEntry *TE, ArrayRef<Value *> VL, SmallVectorImpl<int> &Mask,
    SmallVectorImpl<SmallVector<const TreeEntry *>> &Entries, unsigned NumParts,
    bool ForOrder) {
  assert(NumParts > 0 && NumParts < VL.size() &&
         "Expected positive number of registers.");
  Entries.clear();
  // No need to check for the topmost gather node.
  if (TE == VectorizableTree.front().get() &&
      (GatheredLoadsEntriesFirst == NoGatheredLoads ||
       none_of(ArrayRef(VectorizableTree).drop_front(),
               [](const std::unique_ptr<TreeEntry> &TE) {
                 return !TE->isGather();
               })))
    return {};
  // FIXME: Gathering for non-power-of-2 nodes not implemented yet.
  if (TE->isNonPowOf2Vec())
    return {};
  Mask.assign(VL.size(), PoisonMaskElem);
  assert((TE->UserTreeIndices.size() == 1 ||
          TE == VectorizableTree.front().get()) &&
         "Expected only single user of the gather node.");
  assert(VL.size() % NumParts == 0 &&
         "Number of scalars must be divisible by NumParts.");
  unsigned SliceSize = getPartNumElems(VL.size(), NumParts);
  SmallVector<std::optional<TTI::ShuffleKind>> Res;
  for (unsigned Part : seq<unsigned>(NumParts)) {
    ArrayRef<Value *> SubVL =
        VL.slice(Part * SliceSize, getNumElems(VL.size(), SliceSize, Part));
    SmallVectorImpl<const TreeEntry *> &SubEntries = Entries.emplace_back();
    std::optional<TTI::ShuffleKind> SubRes =
        isGatherShuffledSingleRegisterEntry(TE, SubVL, Mask, SubEntries, Part,
                                            ForOrder);
    if (!SubRes)
      SubEntries.clear();
    Res.push_back(SubRes);
    if (SubEntries.size() == 1 && *SubRes == TTI::SK_PermuteSingleSrc &&
        SubEntries.front()->getVectorFactor() == VL.size() &&
        (SubEntries.front()->isSame(TE->Scalars) ||
         SubEntries.front()->isSame(VL))) {
      SmallVector<const TreeEntry *> LocalSubEntries;
      LocalSubEntries.swap(SubEntries);
      Entries.clear();
      Res.clear();
      std::iota(Mask.begin(), Mask.end(), 0);
      // Clear undef scalars.
      for (int I = 0, Sz = VL.size(); I < Sz; ++I)
        if (isa<PoisonValue>(VL[I]))
          Mask[I] = PoisonMaskElem;
      Entries.emplace_back(1, LocalSubEntries.front());
      Res.push_back(TargetTransformInfo::SK_PermuteSingleSrc);
      return Res;
    }
  }
  if (all_of(Res,
             [](const std::optional<TTI::ShuffleKind> &SK) { return !SK; })) {
    Entries.clear();
    return {};
  }
  return Res;
}

InstructionCost BoUpSLP::getGatherCost(ArrayRef<Value *> VL, bool ForPoisonSrc,
                                       Type *ScalarTy) const {
  auto *VecTy = getWidenedType(ScalarTy, VL.size());
  bool DuplicateNonConst = false;
  // Find the cost of inserting/extracting values from the vector.
  // Check if the same elements are inserted several times and count them as
  // shuffle candidates.
  APInt ShuffledElements = APInt::getZero(VL.size());
  DenseMap<Value *, unsigned> UniqueElements;
  constexpr TTI::TargetCostKind CostKind = TTI::TCK_RecipThroughput;
  InstructionCost Cost;
  auto EstimateInsertCost = [&](unsigned I, Value *V) {
    if (V->getType() != ScalarTy) {
      Cost += TTI->getCastInstrCost(Instruction::Trunc, ScalarTy, V->getType(),
                                    TTI::CastContextHint::None, CostKind);
      V = nullptr;
    }
    if (!ForPoisonSrc)
      Cost +=
          TTI->getVectorInstrCost(Instruction::InsertElement, VecTy, CostKind,
                                  I, Constant::getNullValue(VecTy), V);
  };
  SmallVector<int> ShuffleMask(VL.size(), PoisonMaskElem);
  for (unsigned I = 0, E = VL.size(); I < E; ++I) {
    Value *V = VL[I];
    // No need to shuffle duplicates for constants.
    if ((ForPoisonSrc && isConstant(V)) || isa<UndefValue>(V)) {
      ShuffledElements.setBit(I);
      ShuffleMask[I] = isa<PoisonValue>(V) ? PoisonMaskElem : I;
      continue;
    }

    auto Res = UniqueElements.try_emplace(V, I);
    if (Res.second) {
      EstimateInsertCost(I, V);
      ShuffleMask[I] = I;
      continue;
    }

    DuplicateNonConst = true;
    ShuffledElements.setBit(I);
    ShuffleMask[I] = Res.first->second;
  }
  if (ForPoisonSrc) {
    if (isa<FixedVectorType>(ScalarTy)) {
      assert(SLPReVec && "Only supported by REVEC.");
      // We don't need to insert elements one by one. Instead, we can insert the
      // entire vector into the destination.
      Cost = 0;
      unsigned ScalarTyNumElements = getNumElements(ScalarTy);
      for (unsigned I : seq<unsigned>(VL.size()))
        if (!ShuffledElements[I])
          Cost += TTI->getShuffleCost(
              TTI::SK_InsertSubvector, VecTy, std::nullopt, CostKind,
              I * ScalarTyNumElements, cast<FixedVectorType>(ScalarTy));
    } else {
      Cost = TTI->getScalarizationOverhead(VecTy, ~ShuffledElements,
                                           /*Insert*/ true,
                                           /*Extract*/ false, CostKind);
    }
  }
  if (DuplicateNonConst)
    Cost += ::getShuffleCost(*TTI, TargetTransformInfo::SK_PermuteSingleSrc,
                             VecTy, ShuffleMask);
  return Cost;
}

// Perform operand reordering on the instructions in VL and return the reordered
// operands in Left and Right.
void BoUpSLP::reorderInputsAccordingToOpcode(ArrayRef<Value *> VL,
                                             SmallVectorImpl<Value *> &Left,
                                             SmallVectorImpl<Value *> &Right,
                                             const BoUpSLP &R) {
  if (VL.empty())
    return;
  VLOperands Ops(VL, R);
  // Reorder the operands in place.
  Ops.reorder();
  Left = Ops.getVL(0);
  Right = Ops.getVL(1);
}

Instruction &BoUpSLP::getLastInstructionInBundle(const TreeEntry *E) {
  auto &Res = EntryToLastInstruction.try_emplace(E).first->second;
  if (Res)
    return *Res;
  // Get the basic block this bundle is in. All instructions in the bundle
  // should be in this block (except for extractelement-like instructions with
  // constant indices or gathered loads).
  auto *Front = E->getMainOp();
  auto *BB = Front->getParent();
  assert(((GatheredLoadsEntriesFirst != NoGatheredLoads &&
           E->getOpcode() == Instruction::Load && E->isGather() &&
           E->Idx < GatheredLoadsEntriesFirst) ||
          all_of(E->Scalars,
                 [=](Value *V) -> bool {
                   if (E->getOpcode() == Instruction::GetElementPtr &&
                       !isa<GetElementPtrInst>(V))
                     return true;
                   auto *I = cast<Instruction>(V);
                   return !E->isOpcodeOrAlt(I) || I->getParent() == BB ||
                          isVectorLikeInstWithConstOps(I);
                 })) &&
         "Expected gathered loads or GEPs or instructions from same basic "
         "block.");

  auto FindLastInst = [&]() {
    Instruction *LastInst = Front;
    for (Value *V : E->Scalars) {
      auto *I = dyn_cast<Instruction>(V);
      if (!I)
        continue;
      if (LastInst->getParent() == I->getParent()) {
        if (LastInst->comesBefore(I))
          LastInst = I;
        continue;
      }
      assert(((E->getOpcode() == Instruction::GetElementPtr &&
               !isa<GetElementPtrInst>(I)) ||
              (isVectorLikeInstWithConstOps(LastInst) &&
               isVectorLikeInstWithConstOps(I)) ||
              (GatheredLoadsEntriesFirst != NoGatheredLoads &&
               E->getOpcode() == Instruction::Load && E->isGather() &&
               E->Idx < GatheredLoadsEntriesFirst)) &&
             "Expected vector-like or non-GEP in GEP node insts only.");
      if (!DT->isReachableFromEntry(LastInst->getParent())) {
        LastInst = I;
        continue;
      }
      if (!DT->isReachableFromEntry(I->getParent()))
        continue;
      auto *NodeA = DT->getNode(LastInst->getParent());
      auto *NodeB = DT->getNode(I->getParent());
      assert(NodeA && "Should only process reachable instructions");
      assert(NodeB && "Should only process reachable instructions");
      assert((NodeA == NodeB) ==
                 (NodeA->getDFSNumIn() == NodeB->getDFSNumIn()) &&
             "Different nodes should have different DFS numbers");
      if (NodeA->getDFSNumIn() < NodeB->getDFSNumIn())
        LastInst = I;
    }
    BB = LastInst->getParent();
    return LastInst;
  };

  auto FindFirstInst = [&]() {
    Instruction *FirstInst = Front;
    for (Value *V : E->Scalars) {
      auto *I = dyn_cast<Instruction>(V);
      if (!I)
        continue;
      if (FirstInst->getParent() == I->getParent()) {
        if (I->comesBefore(FirstInst))
          FirstInst = I;
        continue;
      }
      assert(((E->getOpcode() == Instruction::GetElementPtr &&
              !isa<GetElementPtrInst>(I)) ||
             (isVectorLikeInstWithConstOps(FirstInst) &&
              isVectorLikeInstWithConstOps(I))) &&
                 "Expected vector-like or non-GEP in GEP node insts only.");
      if (!DT->isReachableFromEntry(FirstInst->getParent())) {
        FirstInst = I;
        continue;
      }
      if (!DT->isReachableFromEntry(I->getParent()))
        continue;
      auto *NodeA = DT->getNode(FirstInst->getParent());
      auto *NodeB = DT->getNode(I->getParent());
      assert(NodeA && "Should only process reachable instructions");
      assert(NodeB && "Should only process reachable instructions");
      assert((NodeA == NodeB) ==
                 (NodeA->getDFSNumIn() == NodeB->getDFSNumIn()) &&
             "Different nodes should have different DFS numbers");
      if (NodeA->getDFSNumIn() > NodeB->getDFSNumIn())
        FirstInst = I;
    }
    return FirstInst;
  };

  // Set insertpoint for gathered loads to the very first load.
  if (GatheredLoadsEntriesFirst != NoGatheredLoads &&
      E->Idx >= GatheredLoadsEntriesFirst && !E->isGather() &&
      E->getOpcode() == Instruction::Load) {
    Res = FindFirstInst();
    return *Res;
  }

  // Set the insert point to the beginning of the basic block if the entry
  // should not be scheduled.
  if (doesNotNeedToSchedule(E->Scalars) ||
      (!E->isGather() && all_of(E->Scalars, isVectorLikeInstWithConstOps))) {
    if ((E->getOpcode() == Instruction::GetElementPtr &&
         any_of(E->Scalars,
                [](Value *V) {
                  return !isa<GetElementPtrInst>(V) && isa<Instruction>(V);
                })) ||
        all_of(E->Scalars,
               [](Value *V) {
                 return !isVectorLikeInstWithConstOps(V) &&
                        isUsedOutsideBlock(V);
               }) ||
        (E->isGather() && E->Idx == 0 && all_of(E->Scalars, [](Value *V) {
           return isa<ExtractElementInst, UndefValue>(V) ||
                  areAllOperandsNonInsts(V);
         })))
      Res = FindLastInst();
    else
      Res = FindFirstInst();
    return *Res;
  }

  // Find the last instruction. The common case should be that BB has been
  // scheduled, and the last instruction is VL.back(). So we start with
  // VL.back() and iterate over schedule data until we reach the end of the
  // bundle. The end of the bundle is marked by null ScheduleData.
  if (BlocksSchedules.count(BB)) {
    Value *V = E->isOneOf(E->Scalars.back());
    if (doesNotNeedToBeScheduled(V))
      V = *find_if_not(E->Scalars, doesNotNeedToBeScheduled);
    auto *Bundle = BlocksSchedules[BB]->getScheduleData(V);
    if (Bundle && Bundle->isPartOfBundle())
      for (; Bundle; Bundle = Bundle->NextInBundle)
        Res = Bundle->Inst;
  }

  // LastInst can still be null at this point if there's either not an entry
  // for BB in BlocksSchedules or there's no ScheduleData available for
  // VL.back(). This can be the case if buildTree_rec aborts for various
  // reasons (e.g., the maximum recursion depth is reached, the maximum region
  // size is reached, etc.). ScheduleData is initialized in the scheduling
  // "dry-run".
  //
  // If this happens, we can still find the last instruction by brute force. We
  // iterate forwards from Front (inclusive) until we either see all
  // instructions in the bundle or reach the end of the block. If Front is the
  // last instruction in program order, LastInst will be set to Front, and we
  // will visit all the remaining instructions in the block.
  //
  // One of the reasons we exit early from buildTree_rec is to place an upper
  // bound on compile-time. Thus, taking an additional compile-time hit here is
  // not ideal. However, this should be exceedingly rare since it requires that
  // we both exit early from buildTree_rec and that the bundle be out-of-order
  // (causing us to iterate all the way to the end of the block).
  if (!Res)
    Res = FindLastInst();
  assert(Res && "Failed to find last instruction in bundle");
  return *Res;
}

void BoUpSLP::setInsertPointAfterBundle(const TreeEntry *E) {
  auto *Front = E->getMainOp();
  Instruction *LastInst = &getLastInstructionInBundle(E);
  assert(LastInst && "Failed to find last instruction in bundle");
  BasicBlock::iterator LastInstIt = LastInst->getIterator();
  // If the instruction is PHI, set the insert point after all the PHIs.
  bool IsPHI = isa<PHINode>(LastInst);
  if (IsPHI)
    LastInstIt = LastInst->getParent()->getFirstNonPHIIt();
  if (IsPHI || (!E->isGather() && doesNotNeedToSchedule(E->Scalars))) {
    Builder.SetInsertPoint(LastInst->getParent(), LastInstIt);
  } else {
    // Set the insertion point after the last instruction in the bundle. Set the
    // debug location to Front.
    Builder.SetInsertPoint(
        LastInst->getParent(),
        LastInst->getNextNonDebugInstruction()->getIterator());
  }
  Builder.SetCurrentDebugLocation(Front->getDebugLoc());
}

Value *BoUpSLP::gather(ArrayRef<Value *> VL, Value *Root, Type *ScalarTy) {
  // List of instructions/lanes from current block and/or the blocks which are
  // part of the current loop. These instructions will be inserted at the end to
  // make it possible to optimize loops and hoist invariant instructions out of
  // the loops body with better chances for success.
  SmallVector<std::pair<Value *, unsigned>, 4> PostponedInsts;
  SmallSet<int, 4> PostponedIndices;
  Loop *L = LI->getLoopFor(Builder.GetInsertBlock());
  auto &&CheckPredecessor = [](BasicBlock *InstBB, BasicBlock *InsertBB) {
    SmallPtrSet<BasicBlock *, 4> Visited;
    while (InsertBB && InsertBB != InstBB && Visited.insert(InsertBB).second)
      InsertBB = InsertBB->getSinglePredecessor();
    return InsertBB && InsertBB == InstBB;
  };
  for (int I = 0, E = VL.size(); I < E; ++I) {
    if (auto *Inst = dyn_cast<Instruction>(VL[I]))
      if ((CheckPredecessor(Inst->getParent(), Builder.GetInsertBlock()) ||
           getTreeEntry(Inst) ||
           (L && (!Root || L->isLoopInvariant(Root)) && L->contains(Inst))) &&
          PostponedIndices.insert(I).second)
        PostponedInsts.emplace_back(Inst, I);
  }

  auto &&CreateInsertElement = [this](Value *Vec, Value *V, unsigned Pos,
                                      Type *Ty) {
    Value *Scalar = V;
    if (Scalar->getType() != Ty) {
      assert(Scalar->getType()->isIntOrIntVectorTy() &&
             Ty->isIntOrIntVectorTy() && "Expected integer types only.");
      Value *V = Scalar;
      if (auto *CI = dyn_cast<CastInst>(Scalar);
          isa_and_nonnull<SExtInst, ZExtInst>(CI)) {
        Value *Op = CI->getOperand(0);
        if (auto *IOp = dyn_cast<Instruction>(Op);
            !IOp || !(isDeleted(IOp) || getTreeEntry(IOp)))
          V = Op;
      }
      Scalar = Builder.CreateIntCast(
          V, Ty, !isKnownNonNegative(Scalar, SimplifyQuery(*DL)));
    }

    Instruction *InsElt;
    if (auto *VecTy = dyn_cast<FixedVectorType>(Scalar->getType())) {
      assert(SLPReVec && "FixedVectorType is not expected.");
      Vec = InsElt = Builder.CreateInsertVector(
          Vec->getType(), Vec, Scalar,
          Builder.getInt64(Pos * VecTy->getNumElements()));
      auto *II = dyn_cast<IntrinsicInst>(InsElt);
      if (!II || II->getIntrinsicID() != Intrinsic::vector_insert)
        return Vec;
    } else {
      Vec = Builder.CreateInsertElement(Vec, Scalar, Builder.getInt32(Pos));
      InsElt = dyn_cast<InsertElementInst>(Vec);
      if (!InsElt)
        return Vec;
    }
    GatherShuffleExtractSeq.insert(InsElt);
    CSEBlocks.insert(InsElt->getParent());
    // Add to our 'need-to-extract' list.
    if (isa<Instruction>(V)) {
      if (TreeEntry *Entry = getTreeEntry(V)) {
        // Find which lane we need to extract.
        User *UserOp = nullptr;
        if (Scalar != V) {
          if (auto *SI = dyn_cast<Instruction>(Scalar))
            UserOp = SI;
        } else {
          UserOp = InsElt;
        }
        if (UserOp) {
          unsigned FoundLane = Entry->findLaneForValue(V);
          ExternalUses.emplace_back(V, UserOp, FoundLane);
        }
      }
    }
    return Vec;
  };
  auto *VecTy = getWidenedType(ScalarTy, VL.size());
  Value *Vec = Root ? Root : PoisonValue::get(VecTy);
  SmallVector<int> NonConsts;
  // Insert constant values at first.
  for (int I = 0, E = VL.size(); I < E; ++I) {
    if (PostponedIndices.contains(I))
      continue;
    if (!isConstant(VL[I])) {
      NonConsts.push_back(I);
      continue;
    }
    if (Root) {
      if (!isa<UndefValue>(VL[I])) {
        NonConsts.push_back(I);
        continue;
      }
      if (isa<PoisonValue>(VL[I]))
        continue;
      if (auto *SV = dyn_cast<ShuffleVectorInst>(Root)) {
        if (SV->getMaskValue(I) == PoisonMaskElem)
          continue;
      }
    }
    Vec = CreateInsertElement(Vec, VL[I], I, ScalarTy);
  }
  // Insert non-constant values.
  for (int I : NonConsts)
    Vec = CreateInsertElement(Vec, VL[I], I, ScalarTy);
  // Append instructions, which are/may be part of the loop, in the end to make
  // it possible to hoist non-loop-based instructions.
  for (const std::pair<Value *, unsigned> &Pair : PostponedInsts)
    Vec = CreateInsertElement(Vec, Pair.first, Pair.second, ScalarTy);

  return Vec;
}

/// Merges shuffle masks and emits final shuffle instruction, if required. It
/// supports shuffling of 2 input vectors. It implements lazy shuffles emission,
/// when the actual shuffle instruction is generated only if this is actually
/// required. Otherwise, the shuffle instruction emission is delayed till the
/// end of the process, to reduce the number of emitted instructions and further
/// analysis/transformations.
/// The class also will look through the previously emitted shuffle instructions
/// and properly mark indices in mask as undef.
/// For example, given the code
/// \code
/// %s1 = shufflevector <2 x ty> %0, poison, <1, 0>
/// %s2 = shufflevector <2 x ty> %1, poison, <1, 0>
/// \endcode
/// and if need to emit shuffle of %s1 and %s2 with mask <1, 0, 3, 2>, it will
/// look through %s1 and %s2 and emit
/// \code
/// %res = shufflevector <2 x ty> %0, %1, <0, 1, 2, 3>
/// \endcode
/// instead.
/// If 2 operands are of different size, the smallest one will be resized and
/// the mask recalculated properly.
/// For example, given the code
/// \code
/// %s1 = shufflevector <2 x ty> %0, poison, <1, 0, 1, 0>
/// %s2 = shufflevector <2 x ty> %1, poison, <1, 0, 1, 0>
/// \endcode
/// and if need to emit shuffle of %s1 and %s2 with mask <1, 0, 5, 4>, it will
/// look through %s1 and %s2 and emit
/// \code
/// %res = shufflevector <2 x ty> %0, %1, <0, 1, 2, 3>
/// \endcode
/// instead.
class BoUpSLP::ShuffleInstructionBuilder final : public BaseShuffleAnalysis {
  bool IsFinalized = false;
  /// Combined mask for all applied operands and masks. It is built during
  /// analysis and actual emission of shuffle vector instructions.
  SmallVector<int> CommonMask;
  /// List of operands for the shuffle vector instruction. It hold at max 2
  /// operands, if the 3rd is going to be added, the first 2 are combined into
  /// shuffle with \p CommonMask mask, the first operand sets to be the
  /// resulting shuffle and the second operand sets to be the newly added
  /// operand. The \p CommonMask is transformed in the proper way after that.
  SmallVector<Value *, 2> InVectors;
  IRBuilderBase &Builder;
  BoUpSLP &R;

  class ShuffleIRBuilder {
    IRBuilderBase &Builder;
    /// Holds all of the instructions that we gathered.
    SetVector<Instruction *> &GatherShuffleExtractSeq;
    /// A list of blocks that we are going to CSE.
    DenseSet<BasicBlock *> &CSEBlocks;
    /// Data layout.
    const DataLayout &DL;

  public:
    ShuffleIRBuilder(IRBuilderBase &Builder,
                     SetVector<Instruction *> &GatherShuffleExtractSeq,
                     DenseSet<BasicBlock *> &CSEBlocks, const DataLayout &DL)
        : Builder(Builder), GatherShuffleExtractSeq(GatherShuffleExtractSeq),
          CSEBlocks(CSEBlocks), DL(DL) {}
    ~ShuffleIRBuilder() = default;
    /// Creates shufflevector for the 2 operands with the given mask.
    Value *createShuffleVector(Value *V1, Value *V2, ArrayRef<int> Mask) {
      if (V1->getType() != V2->getType()) {
        assert(V1->getType()->isIntOrIntVectorTy() &&
               V1->getType()->isIntOrIntVectorTy() &&
               "Expected integer vector types only.");
        if (V1->getType() != V2->getType()) {
          if (cast<VectorType>(V2->getType())
                  ->getElementType()
                  ->getIntegerBitWidth() < cast<VectorType>(V1->getType())
                                               ->getElementType()
                                               ->getIntegerBitWidth())
            V2 = Builder.CreateIntCast(
                V2, V1->getType(), !isKnownNonNegative(V2, SimplifyQuery(DL)));
          else
            V1 = Builder.CreateIntCast(
                V1, V2->getType(), !isKnownNonNegative(V1, SimplifyQuery(DL)));
        }
      }
      Value *Vec = Builder.CreateShuffleVector(V1, V2, Mask);
      if (auto *I = dyn_cast<Instruction>(Vec)) {
        GatherShuffleExtractSeq.insert(I);
        CSEBlocks.insert(I->getParent());
      }
      return Vec;
    }
    /// Creates permutation of the single vector operand with the given mask, if
    /// it is not identity mask.
    Value *createShuffleVector(Value *V1, ArrayRef<int> Mask) {
      if (Mask.empty())
        return V1;
      unsigned VF = Mask.size();
      unsigned LocalVF = cast<FixedVectorType>(V1->getType())->getNumElements();
      if (VF == LocalVF && ShuffleVectorInst::isIdentityMask(Mask, VF))
        return V1;
      Value *Vec = Builder.CreateShuffleVector(V1, Mask);
      if (auto *I = dyn_cast<Instruction>(Vec)) {
        GatherShuffleExtractSeq.insert(I);
        CSEBlocks.insert(I->getParent());
      }
      return Vec;
    }
    Value *createIdentity(Value *V) { return V; }
    Value *createPoison(Type *Ty, unsigned VF) {
      return PoisonValue::get(getWidenedType(Ty, VF));
    }
    /// Resizes 2 input vector to match the sizes, if the they are not equal
    /// yet. The smallest vector is resized to the size of the larger vector.
    void resizeToMatch(Value *&V1, Value *&V2) {
      if (V1->getType() == V2->getType())
        return;
      int V1VF = cast<FixedVectorType>(V1->getType())->getNumElements();
      int V2VF = cast<FixedVectorType>(V2->getType())->getNumElements();
      int VF = std::max(V1VF, V2VF);
      int MinVF = std::min(V1VF, V2VF);
      SmallVector<int> IdentityMask(VF, PoisonMaskElem);
      std::iota(IdentityMask.begin(), std::next(IdentityMask.begin(), MinVF),
                0);
      Value *&Op = MinVF == V1VF ? V1 : V2;
      Op = Builder.CreateShuffleVector(Op, IdentityMask);
      if (auto *I = dyn_cast<Instruction>(Op)) {
        GatherShuffleExtractSeq.insert(I);
        CSEBlocks.insert(I->getParent());
      }
      if (MinVF == V1VF)
        V1 = Op;
      else
        V2 = Op;
    }
  };

  /// Smart shuffle instruction emission, walks through shuffles trees and
  /// tries to find the best matching vector for the actual shuffle
  /// instruction.
  Value *createShuffle(Value *V1, Value *V2, ArrayRef<int> Mask) {
    assert(V1 && "Expected at least one vector value.");
    ShuffleIRBuilder ShuffleBuilder(Builder, R.GatherShuffleExtractSeq,
                                    R.CSEBlocks, *R.DL);
    return BaseShuffleAnalysis::createShuffle<Value *>(V1, V2, Mask,
                                                       ShuffleBuilder);
  }

  /// Transforms mask \p CommonMask per given \p Mask to make proper set after
  /// shuffle emission.
  static void transformMaskAfterShuffle(MutableArrayRef<int> CommonMask,
                                        ArrayRef<int> Mask) {
    for (unsigned Idx = 0, Sz = CommonMask.size(); Idx < Sz; ++Idx)
      if (Mask[Idx] != PoisonMaskElem)
        CommonMask[Idx] = Idx;
  }

  /// Cast value \p V to the vector type with the same number of elements, but
  /// the base type \p ScalarTy.
  Value *castToScalarTyElem(Value *V,
                            std::optional<bool> IsSigned = std::nullopt) {
    auto *VecTy = cast<VectorType>(V->getType());
    assert(getNumElements(VecTy) % getNumElements(ScalarTy) == 0);
    if (VecTy->getElementType() == ScalarTy->getScalarType())
      return V;
    return Builder.CreateIntCast(
        V, VectorType::get(ScalarTy->getScalarType(), VecTy->getElementCount()),
        IsSigned.value_or(!isKnownNonNegative(V, SimplifyQuery(*R.DL))));
  }

public:
  ShuffleInstructionBuilder(Type *ScalarTy, IRBuilderBase &Builder, BoUpSLP &R)
      : BaseShuffleAnalysis(ScalarTy), Builder(Builder), R(R) {}

  /// Adjusts extractelements after reusing them.
  Value *adjustExtracts(const TreeEntry *E, MutableArrayRef<int> Mask,
                        ArrayRef<std::optional<TTI::ShuffleKind>> ShuffleKinds,
                        unsigned NumParts, bool &UseVecBaseAsInput) {
    UseVecBaseAsInput = false;
    SmallPtrSet<Value *, 4> UniqueBases;
    Value *VecBase = nullptr;
    for (int I = 0, Sz = Mask.size(); I < Sz; ++I) {
      int Idx = Mask[I];
      if (Idx == PoisonMaskElem)
        continue;
      auto *EI = cast<ExtractElementInst>(E->Scalars[I]);
      VecBase = EI->getVectorOperand();
      if (const TreeEntry *TE = R.getTreeEntry(VecBase))
        VecBase = TE->VectorizedValue;
      assert(VecBase && "Expected vectorized value.");
      UniqueBases.insert(VecBase);
      // If the only one use is vectorized - can delete the extractelement
      // itself.
      if (!EI->hasOneUse() || (NumParts != 1 && count(E->Scalars, EI) > 1) ||
          any_of(EI->users(), [&](User *U) {
            const TreeEntry *UTE = R.getTreeEntry(U);
            return !UTE || R.MultiNodeScalars.contains(U) ||
                   (isa<GetElementPtrInst>(U) &&
                    !R.areAllUsersVectorized(cast<Instruction>(U))) ||
                   count_if(R.VectorizableTree,
                            [&](const std::unique_ptr<TreeEntry> &TE) {
                              return any_of(TE->UserTreeIndices,
                                            [&](const EdgeInfo &Edge) {
                                              return Edge.UserTE == UTE;
                                            }) &&
                                     is_contained(TE->Scalars, EI);
                            }) != 1;
          }))
        continue;
      R.eraseInstruction(EI);
    }
    if (NumParts == 1 || UniqueBases.size() == 1) {
      assert(VecBase && "Expected vectorized value.");
      return castToScalarTyElem(VecBase);
    }
    UseVecBaseAsInput = true;
    auto TransformToIdentity = [](MutableArrayRef<int> Mask) {
      for (auto [I, Idx] : enumerate(Mask))
        if (Idx != PoisonMaskElem)
          Idx = I;
    };
    // Perform multi-register vector shuffle, joining them into a single virtual
    // long vector.
    // Need to shuffle each part independently and then insert all this parts
    // into a long virtual vector register, forming the original vector.
    Value *Vec = nullptr;
    SmallVector<int> VecMask(Mask.size(), PoisonMaskElem);
    unsigned SliceSize = getPartNumElems(E->Scalars.size(), NumParts);
    for (unsigned Part : seq<unsigned>(NumParts)) {
      unsigned Limit = getNumElems(E->Scalars.size(), SliceSize, Part);
      ArrayRef<Value *> VL =
          ArrayRef(E->Scalars).slice(Part * SliceSize, Limit);
      MutableArrayRef<int> SubMask = Mask.slice(Part * SliceSize, Limit);
      constexpr int MaxBases = 2;
      SmallVector<Value *, MaxBases> Bases(MaxBases);
      auto VLMask = zip(VL, SubMask);
      const unsigned VF = std::accumulate(
          VLMask.begin(), VLMask.end(), 0U, [&](unsigned S, const auto &D) {
            if (std::get<1>(D) == PoisonMaskElem)
              return S;
            Value *VecOp =
                cast<ExtractElementInst>(std::get<0>(D))->getVectorOperand();
            if (const TreeEntry *TE = R.getTreeEntry(VecOp))
              VecOp = TE->VectorizedValue;
            assert(VecOp && "Expected vectorized value.");
            const unsigned Size =
                cast<FixedVectorType>(VecOp->getType())->getNumElements();
            return std::max(S, Size);
          });
      for (const auto [V, I] : VLMask) {
        if (I == PoisonMaskElem)
          continue;
        Value *VecOp = cast<ExtractElementInst>(V)->getVectorOperand();
        if (const TreeEntry *TE = R.getTreeEntry(VecOp))
          VecOp = TE->VectorizedValue;
        assert(VecOp && "Expected vectorized value.");
        VecOp = castToScalarTyElem(VecOp);
        Bases[I / VF] = VecOp;
      }
      if (!Bases.front())
        continue;
      Value *SubVec;
      if (Bases.back()) {
        SubVec = createShuffle(Bases.front(), Bases.back(), SubMask);
        TransformToIdentity(SubMask);
      } else {
        SubVec = Bases.front();
      }
      if (!Vec) {
        Vec = SubVec;
        assert((Part == 0 || all_of(seq<unsigned>(0, Part),
                                    [&](unsigned P) {
                                      ArrayRef<int> SubMask =
                                          Mask.slice(P * SliceSize,
                                                     getNumElems(Mask.size(),
                                                                 SliceSize, P));
                                      return all_of(SubMask, [](int Idx) {
                                        return Idx == PoisonMaskElem;
                                      });
                                    })) &&
               "Expected first part or all previous parts masked.");
        copy(SubMask, std::next(VecMask.begin(), Part * SliceSize));
      } else {
        unsigned NewVF =
            cast<FixedVectorType>(Vec->getType())->getNumElements();
        if (Vec->getType() != SubVec->getType()) {
          unsigned SubVecVF =
              cast<FixedVectorType>(SubVec->getType())->getNumElements();
          NewVF = std::max(NewVF, SubVecVF);
        }
        // Adjust SubMask.
        for (int &Idx : SubMask)
          if (Idx != PoisonMaskElem)
            Idx += NewVF;
        copy(SubMask, std::next(VecMask.begin(), Part * SliceSize));
        Vec = createShuffle(Vec, SubVec, VecMask);
        TransformToIdentity(VecMask);
      }
    }
    copy(VecMask, Mask.begin());
    return Vec;
  }
  /// Checks if the specified entry \p E needs to be delayed because of its
  /// dependency nodes.
  std::optional<Value *>
  needToDelay(const TreeEntry *E,
              ArrayRef<SmallVector<const TreeEntry *>> Deps) const {
    // No need to delay emission if all deps are ready.
    if (all_of(Deps, [](ArrayRef<const TreeEntry *> TEs) {
          return all_of(
              TEs, [](const TreeEntry *TE) { return TE->VectorizedValue; });
        }))
      return std::nullopt;
    // Postpone gather emission, will be emitted after the end of the
    // process to keep correct order.
    auto *ResVecTy = getWidenedType(ScalarTy, E->getVectorFactor());
    return Builder.CreateAlignedLoad(
        ResVecTy,
        PoisonValue::get(PointerType::getUnqual(ScalarTy->getContext())),
        MaybeAlign());
  }
  /// Adds 2 input vectors (in form of tree entries) and the mask for their
  /// shuffling.
  void add(const TreeEntry &E1, const TreeEntry &E2, ArrayRef<int> Mask) {
    Value *V1 = E1.VectorizedValue;
    if (V1->getType()->isIntOrIntVectorTy())
      V1 = castToScalarTyElem(V1, any_of(E1.Scalars, [&](Value *V) {
                                return !isKnownNonNegative(
                                    V, SimplifyQuery(*R.DL));
                              }));
    Value *V2 = E2.VectorizedValue;
    if (V2->getType()->isIntOrIntVectorTy())
      V2 = castToScalarTyElem(V2, any_of(E2.Scalars, [&](Value *V) {
                                return !isKnownNonNegative(
                                    V, SimplifyQuery(*R.DL));
                              }));
    add(V1, V2, Mask);
  }
  /// Adds single input vector (in form of tree entry) and the mask for its
  /// shuffling.
  void add(const TreeEntry &E1, ArrayRef<int> Mask) {
    Value *V1 = E1.VectorizedValue;
    if (V1->getType()->isIntOrIntVectorTy())
      V1 = castToScalarTyElem(V1, any_of(E1.Scalars, [&](Value *V) {
                                return !isKnownNonNegative(
                                    V, SimplifyQuery(*R.DL));
                              }));
    add(V1, Mask);
  }
  /// Adds 2 input vectors and the mask for their shuffling.
  void add(Value *V1, Value *V2, ArrayRef<int> Mask) {
    assert(V1 && V2 && !Mask.empty() && "Expected non-empty input vectors.");
    assert(isa<FixedVectorType>(V1->getType()) &&
           isa<FixedVectorType>(V2->getType()) &&
           "castToScalarTyElem expects V1 and V2 to be FixedVectorType");
    V1 = castToScalarTyElem(V1);
    V2 = castToScalarTyElem(V2);
    if (InVectors.empty()) {
      InVectors.push_back(V1);
      InVectors.push_back(V2);
      CommonMask.assign(Mask.begin(), Mask.end());
      return;
    }
    Value *Vec = InVectors.front();
    if (InVectors.size() == 2) {
      Vec = createShuffle(Vec, InVectors.back(), CommonMask);
      transformMaskAfterShuffle(CommonMask, CommonMask);
    } else if (cast<FixedVectorType>(Vec->getType())->getNumElements() !=
               Mask.size()) {
      Vec = createShuffle(Vec, nullptr, CommonMask);
      transformMaskAfterShuffle(CommonMask, CommonMask);
    }
    V1 = createShuffle(V1, V2, Mask);
    for (unsigned Idx = 0, Sz = CommonMask.size(); Idx < Sz; ++Idx)
      if (Mask[Idx] != PoisonMaskElem)
        CommonMask[Idx] = Idx + Sz;
    InVectors.front() = Vec;
    if (InVectors.size() == 2)
      InVectors.back() = V1;
    else
      InVectors.push_back(V1);
  }
  /// Adds another one input vector and the mask for the shuffling.
  void add(Value *V1, ArrayRef<int> Mask, bool = false) {
    assert(isa<FixedVectorType>(V1->getType()) &&
           "castToScalarTyElem expects V1 to be FixedVectorType");
    V1 = castToScalarTyElem(V1);
    if (InVectors.empty()) {
      InVectors.push_back(V1);
      CommonMask.assign(Mask.begin(), Mask.end());
      return;
    }
    const auto *It = find(InVectors, V1);
    if (It == InVectors.end()) {
      if (InVectors.size() == 2 ||
          InVectors.front()->getType() != V1->getType()) {
        Value *V = InVectors.front();
        if (InVectors.size() == 2) {
          V = createShuffle(InVectors.front(), InVectors.back(), CommonMask);
          transformMaskAfterShuffle(CommonMask, CommonMask);
        } else if (cast<FixedVectorType>(V->getType())->getNumElements() !=
                   CommonMask.size()) {
          V = createShuffle(InVectors.front(), nullptr, CommonMask);
          transformMaskAfterShuffle(CommonMask, CommonMask);
        }
        unsigned VF = std::max(CommonMask.size(), Mask.size());
        for (unsigned Idx = 0, Sz = CommonMask.size(); Idx < Sz; ++Idx)
          if (CommonMask[Idx] == PoisonMaskElem && Mask[Idx] != PoisonMaskElem)
            CommonMask[Idx] =
                V->getType() != V1->getType()
                    ? Idx + VF
                    : Mask[Idx] + cast<FixedVectorType>(V1->getType())
                                      ->getNumElements();
        if (V->getType() != V1->getType())
          V1 = createShuffle(V1, nullptr, Mask);
        InVectors.front() = V;
        if (InVectors.size() == 2)
          InVectors.back() = V1;
        else
          InVectors.push_back(V1);
        return;
      }
      // Check if second vector is required if the used elements are already
      // used from the first one.
      for (unsigned Idx = 0, Sz = CommonMask.size(); Idx < Sz; ++Idx)
        if (Mask[Idx] != PoisonMaskElem && CommonMask[Idx] == PoisonMaskElem) {
          InVectors.push_back(V1);
          break;
        }
    }
    int VF = getVF(V1);
    for (unsigned Idx = 0, Sz = CommonMask.size(); Idx < Sz; ++Idx)
      if (Mask[Idx] != PoisonMaskElem && CommonMask[Idx] == PoisonMaskElem)
        CommonMask[Idx] = Mask[Idx] + (It == InVectors.begin() ? 0 : VF);
  }
  /// Adds another one input vector and the mask for the shuffling.
  void addOrdered(Value *V1, ArrayRef<unsigned> Order) {
    SmallVector<int> NewMask;
    inversePermutation(Order, NewMask);
    add(V1, NewMask);
  }
  Value *gather(ArrayRef<Value *> VL, unsigned MaskVF = 0,
                Value *Root = nullptr) {
    return R.gather(VL, Root, ScalarTy);
  }
  Value *createFreeze(Value *V) { return Builder.CreateFreeze(V); }
  /// Finalize emission of the shuffles.
  /// \param Action the action (if any) to be performed before final applying of
  /// the \p ExtMask mask.
  Value *
  finalize(ArrayRef<int> ExtMask,
           ArrayRef<std::pair<const TreeEntry *, unsigned>> SubVectors,
           unsigned VF = 0,
           function_ref<void(Value *&, SmallVectorImpl<int> &)> Action = {}) {
    IsFinalized = true;
    SmallVector<int> NewExtMask(ExtMask);
    if (auto *VecTy = dyn_cast<FixedVectorType>(ScalarTy)) {
      assert(SLPReVec && "FixedVectorType is not expected.");
      transformScalarShuffleIndiciesToVector(VecTy->getNumElements(),
                                             CommonMask);
      transformScalarShuffleIndiciesToVector(VecTy->getNumElements(),
                                             NewExtMask);
      ExtMask = NewExtMask;
    }
    if (Action) {
      Value *Vec = InVectors.front();
      if (InVectors.size() == 2) {
        Vec = createShuffle(Vec, InVectors.back(), CommonMask);
        InVectors.pop_back();
      } else {
        Vec = createShuffle(Vec, nullptr, CommonMask);
      }
      for (unsigned Idx = 0, Sz = CommonMask.size(); Idx < Sz; ++Idx)
        if (CommonMask[Idx] != PoisonMaskElem)
          CommonMask[Idx] = Idx;
      assert(VF > 0 &&
             "Expected vector length for the final value before action.");
      unsigned VecVF = cast<FixedVectorType>(Vec->getType())->getNumElements();
      if (VecVF < VF) {
        SmallVector<int> ResizeMask(VF, PoisonMaskElem);
        std::iota(ResizeMask.begin(), std::next(ResizeMask.begin(), VecVF), 0);
        Vec = createShuffle(Vec, nullptr, ResizeMask);
      }
      Action(Vec, CommonMask);
      InVectors.front() = Vec;
    }
    if (!SubVectors.empty()) {
      Value *Vec = InVectors.front();
      if (InVectors.size() == 2) {
        Vec = createShuffle(Vec, InVectors.back(), CommonMask);
        InVectors.pop_back();
      } else {
        Vec = createShuffle(Vec, nullptr, CommonMask);
      }
      for (unsigned Idx = 0, Sz = CommonMask.size(); Idx < Sz; ++Idx)
        if (CommonMask[Idx] != PoisonMaskElem)
          CommonMask[Idx] = Idx;
      for (auto [E, Idx] : SubVectors) {
        Value *V = castToScalarTyElem(E->VectorizedValue);
        Vec = Builder.CreateInsertVector(Vec->getType(), Vec, V,
                                         Builder.getInt64(Idx));
        if (!CommonMask.empty()) {
          std::iota(std::next(CommonMask.begin(), Idx),
                    std::next(CommonMask.begin(), Idx + E->getVectorFactor()),
                    Idx);
        }
      }
      InVectors.front() = Vec;
    }

    if (!ExtMask.empty()) {
      if (CommonMask.empty()) {
        CommonMask.assign(ExtMask.begin(), ExtMask.end());
      } else {
        SmallVector<int> NewMask(ExtMask.size(), PoisonMaskElem);
        for (int I = 0, Sz = ExtMask.size(); I < Sz; ++I) {
          if (ExtMask[I] == PoisonMaskElem)
            continue;
          NewMask[I] = CommonMask[ExtMask[I]];
        }
        CommonMask.swap(NewMask);
      }
    }
    if (CommonMask.empty()) {
      assert(InVectors.size() == 1 && "Expected only one vector with no mask");
      return InVectors.front();
    }
    if (InVectors.size() == 2)
      return createShuffle(InVectors.front(), InVectors.back(), CommonMask);
    return createShuffle(InVectors.front(), nullptr, CommonMask);
  }

  ~ShuffleInstructionBuilder() {
    assert((IsFinalized || CommonMask.empty()) &&
           "Shuffle construction must be finalized.");
  }
};

BoUpSLP::TreeEntry *BoUpSLP::getMatchedVectorizedOperand(const TreeEntry *E,
                                                         unsigned NodeIdx) {
  ArrayRef<Value *> VL = E->getOperand(NodeIdx);
  InstructionsState S = getSameOpcode(VL, *TLI);
  // Special processing for GEPs bundle, which may include non-gep values.
  if (!S.getOpcode() && VL.front()->getType()->isPointerTy()) {
    const auto *It = find_if(VL, IsaPred<GetElementPtrInst>);
    if (It != VL.end())
      S = getSameOpcode(*It, *TLI);
  }
  if (!S.getOpcode())
    return nullptr;
  auto CheckSameVE = [&](const TreeEntry *VE) {
    return VE->isSame(VL) &&
           (any_of(VE->UserTreeIndices,
                   [E, NodeIdx](const EdgeInfo &EI) {
                     return EI.UserTE == E && EI.EdgeIdx == NodeIdx;
                   }) ||
            any_of(VectorizableTree,
                   [E, NodeIdx, VE](const std::unique_ptr<TreeEntry> &TE) {
                     return TE->isOperandGatherNode(
                                {const_cast<TreeEntry *>(E), NodeIdx}) &&
                            VE->isSame(TE->Scalars);
                   }));
  };
  TreeEntry *VE = getTreeEntry(S.OpValue);
  if (VE && CheckSameVE(VE))
    return VE;
  auto It = MultiNodeScalars.find(S.OpValue);
  if (It != MultiNodeScalars.end()) {
    auto *I = find_if(It->getSecond(), [&](const TreeEntry *TE) {
      return TE != VE && CheckSameVE(TE);
    });
    if (I != It->getSecond().end())
      return *I;
  }
  return nullptr;
}

Value *BoUpSLP::vectorizeOperand(TreeEntry *E, unsigned NodeIdx,
                                 bool PostponedPHIs) {
  ValueList &VL = E->getOperand(NodeIdx);
  const unsigned VF = VL.size();
  if (TreeEntry *VE = getMatchedVectorizedOperand(E, NodeIdx)) {
    auto FinalShuffle = [&](Value *V, ArrayRef<int> Mask) {
      // V may be affected by MinBWs.
      // We want ShuffleInstructionBuilder to correctly support REVEC. The key
      // factor is the number of elements, not their type.
      Type *ScalarTy = cast<VectorType>(V->getType())->getElementType();
      unsigned NumElements = getNumElements(VL.front()->getType());
      ShuffleInstructionBuilder ShuffleBuilder(
          NumElements != 1 ? FixedVectorType::get(ScalarTy, NumElements)
                           : ScalarTy,
          Builder, *this);
      ShuffleBuilder.add(V, Mask);
      SmallVector<std::pair<const TreeEntry *, unsigned>> SubVectors(
          E->CombinedEntriesWithIndices.size());
      transform(E->CombinedEntriesWithIndices, SubVectors.begin(),
                [&](const auto &P) {
                  return std::make_pair(VectorizableTree[P.first].get(),
                                        P.second);
                });
      return ShuffleBuilder.finalize({}, SubVectors);
    };
    Value *V = vectorizeTree(VE, PostponedPHIs);
    if (VF * getNumElements(VL[0]->getType()) !=
        cast<FixedVectorType>(V->getType())->getNumElements()) {
      if (!VE->ReuseShuffleIndices.empty()) {
        // Reshuffle to get only unique values.
        // If some of the scalars are duplicated in the vectorization
        // tree entry, we do not vectorize them but instead generate a
        // mask for the reuses. But if there are several users of the
        // same entry, they may have different vectorization factors.
        // This is especially important for PHI nodes. In this case, we
        // need to adapt the resulting instruction for the user
        // vectorization factor and have to reshuffle it again to take
        // only unique elements of the vector. Without this code the
        // function incorrectly returns reduced vector instruction with
        // the same elements, not with the unique ones.

        // block:
        // %phi = phi <2 x > { .., %entry} {%shuffle, %block}
        // %2 = shuffle <2 x > %phi, poison, <4 x > <1, 1, 0, 0>
        // ... (use %2)
        // %shuffle = shuffle <2 x> %2, poison, <2 x> {2, 0}
        // br %block
        SmallVector<int> Mask(VF, PoisonMaskElem);
        for (auto [I, V] : enumerate(VL)) {
          if (isa<PoisonValue>(V))
            continue;
          Mask[I] = VE->findLaneForValue(V);
        }
        V = FinalShuffle(V, Mask);
      } else {
        assert(VF < cast<FixedVectorType>(V->getType())->getNumElements() &&
               "Expected vectorization factor less "
               "than original vector size.");
        SmallVector<int> UniformMask(VF, 0);
        std::iota(UniformMask.begin(), UniformMask.end(), 0);
        V = FinalShuffle(V, UniformMask);
      }
    }
    // Need to update the operand gather node, if actually the operand is not a
    // vectorized node, but the buildvector/gather node, which matches one of
    // the vectorized nodes.
    if (find_if(VE->UserTreeIndices, [&](const EdgeInfo &EI) {
          return EI.UserTE == E && EI.EdgeIdx == NodeIdx;
        }) == VE->UserTreeIndices.end()) {
      auto *It =
          find_if(VectorizableTree, [&](const std::unique_ptr<TreeEntry> &TE) {
            return TE->isGather() && TE->UserTreeIndices.front().UserTE == E &&
                   TE->UserTreeIndices.front().EdgeIdx == NodeIdx;
          });
      assert(It != VectorizableTree.end() && "Expected gather node operand.");
      (*It)->VectorizedValue = V;
    }
    return V;
  }

  // Find the corresponding gather entry and vectorize it.
  // Allows to be more accurate with tree/graph transformations, checks for the
  // correctness of the transformations in many cases.
  auto *I = find_if(VectorizableTree,
                    [E, NodeIdx](const std::unique_ptr<TreeEntry> &TE) {
                      return TE->isOperandGatherNode({E, NodeIdx});
                    });
  assert(I != VectorizableTree.end() && "Gather node is not in the graph.");
  assert(I->get()->UserTreeIndices.size() == 1 &&
         "Expected only single user for the gather node.");
  assert(I->get()->isSame(VL) && "Expected same list of scalars.");
  return vectorizeTree(I->get(), PostponedPHIs);
}

template <typename BVTy, typename ResTy, typename... Args>
ResTy BoUpSLP::processBuildVector(const TreeEntry *E, Type *ScalarTy,
                                  Args &...Params) {
  assert(E->isGather() && "Expected gather node.");
  unsigned VF = E->getVectorFactor();

  bool NeedFreeze = false;
  SmallVector<int> ReuseShuffleIndices(E->ReuseShuffleIndices.begin(),
                                       E->ReuseShuffleIndices.end());
  SmallVector<Value *> GatheredScalars(E->Scalars.begin(), E->Scalars.end());
  // Clear values, to be replaced by insertvector instructions.
  for (auto [EIdx, Idx] : E->CombinedEntriesWithIndices)
    for_each(MutableArrayRef(GatheredScalars)
                 .slice(Idx, VectorizableTree[EIdx]->getVectorFactor()),
             [&](Value *&V) { V = PoisonValue::get(V->getType()); });
  SmallVector<std::pair<const TreeEntry *, unsigned>> SubVectors(
      E->CombinedEntriesWithIndices.size());
  transform(E->CombinedEntriesWithIndices, SubVectors.begin(),
            [&](const auto &P) {
              return std::make_pair(VectorizableTree[P.first].get(), P.second);
            });
  // Build a mask out of the reorder indices and reorder scalars per this
  // mask.
  SmallVector<int> ReorderMask;
  inversePermutation(E->ReorderIndices, ReorderMask);
  if (!ReorderMask.empty())
    reorderScalars(GatheredScalars, ReorderMask);
  auto FindReusedSplat = [&](MutableArrayRef<int> Mask, unsigned InputVF,
                             unsigned I, unsigned SliceSize) {
    if (!isSplat(E->Scalars) || none_of(E->Scalars, [](Value *V) {
          return isa<UndefValue>(V) && !isa<PoisonValue>(V);
        }))
      return false;
    TreeEntry *UserTE = E->UserTreeIndices.back().UserTE;
    unsigned EdgeIdx = E->UserTreeIndices.back().EdgeIdx;
    if (UserTE->getNumOperands() != 2)
      return false;
    auto *It =
        find_if(VectorizableTree, [=](const std::unique_ptr<TreeEntry> &TE) {
          return find_if(TE->UserTreeIndices, [=](const EdgeInfo &EI) {
                   return EI.UserTE == UserTE && EI.EdgeIdx != EdgeIdx;
                 }) != TE->UserTreeIndices.end();
        });
    if (It == VectorizableTree.end())
      return false;
    int Idx;
    if ((Mask.size() < InputVF &&
         ShuffleVectorInst::isExtractSubvectorMask(Mask, InputVF, Idx) &&
         Idx == 0) ||
        (Mask.size() == InputVF &&
         ShuffleVectorInst::isIdentityMask(Mask, Mask.size()))) {
      std::iota(
          std::next(Mask.begin(), I * SliceSize),
          std::next(Mask.begin(),
                    I * SliceSize + getNumElems(Mask.size(), SliceSize, I)),
          0);
    } else {
      unsigned IVal =
          *find_if_not(Mask, [](int Idx) { return Idx == PoisonMaskElem; });
      std::fill(
          std::next(Mask.begin(), I * SliceSize),
          std::next(Mask.begin(),
                    I * SliceSize + getNumElems(Mask.size(), SliceSize, I)),
          IVal);
    }
    return true;
  };
  BVTy ShuffleBuilder(ScalarTy, Params...);
  ResTy Res = ResTy();
  SmallVector<int> Mask;
  SmallVector<int> ExtractMask(GatheredScalars.size(), PoisonMaskElem);
  SmallVector<std::optional<TTI::ShuffleKind>> ExtractShuffles;
  Value *ExtractVecBase = nullptr;
  bool UseVecBaseAsInput = false;
  SmallVector<std::optional<TargetTransformInfo::ShuffleKind>> GatherShuffles;
  SmallVector<SmallVector<const TreeEntry *>> Entries;
  Type *OrigScalarTy = GatheredScalars.front()->getType();
  auto *VecTy = getWidenedType(ScalarTy, GatheredScalars.size());
  unsigned NumParts = TTI->getNumberOfParts(VecTy);
  if (NumParts == 0 || NumParts >= GatheredScalars.size())
    NumParts = 1;
  if (!all_of(GatheredScalars, IsaPred<UndefValue>)) {
    // Check for gathered extracts.
    bool Resized = false;
    ExtractShuffles =
        tryToGatherExtractElements(GatheredScalars, ExtractMask, NumParts);
    if (!ExtractShuffles.empty()) {
      SmallVector<const TreeEntry *> ExtractEntries;
      for (auto [Idx, I] : enumerate(ExtractMask)) {
        if (I == PoisonMaskElem)
          continue;
        if (const auto *TE = getTreeEntry(
                cast<ExtractElementInst>(E->Scalars[Idx])->getVectorOperand()))
          ExtractEntries.push_back(TE);
      }
      if (std::optional<ResTy> Delayed =
              ShuffleBuilder.needToDelay(E, ExtractEntries)) {
        // Delay emission of gathers which are not ready yet.
        PostponedGathers.insert(E);
        // Postpone gather emission, will be emitted after the end of the
        // process to keep correct order.
        return *Delayed;
      }
      if (Value *VecBase = ShuffleBuilder.adjustExtracts(
              E, ExtractMask, ExtractShuffles, NumParts, UseVecBaseAsInput)) {
        ExtractVecBase = VecBase;
        if (auto *VecBaseTy = dyn_cast<FixedVectorType>(VecBase->getType()))
          if (VF == VecBaseTy->getNumElements() &&
              GatheredScalars.size() != VF) {
            Resized = true;
            GatheredScalars.append(VF - GatheredScalars.size(),
                                   PoisonValue::get(OrigScalarTy));
          }
      }
    }
    // Gather extracts after we check for full matched gathers only.
    if (!ExtractShuffles.empty() || E->getOpcode() != Instruction::Load ||
        ((E->getOpcode() == Instruction::Load ||
          any_of(E->Scalars, IsaPred<LoadInst>)) &&
         any_of(E->Scalars,
                [this](Value *V) {
                  return isa<LoadInst>(V) && getTreeEntry(V);
                })) ||
        E->isAltShuffle() ||
        all_of(E->Scalars, [this](Value *V) { return getTreeEntry(V); }) ||
        isSplat(E->Scalars) ||
        (E->Scalars != GatheredScalars && GatheredScalars.size() <= 2)) {
      GatherShuffles =
          isGatherShuffledEntry(E, GatheredScalars, Mask, Entries, NumParts);
    }
    if (!GatherShuffles.empty()) {
      if (std::optional<ResTy> Delayed =
              ShuffleBuilder.needToDelay(E, Entries)) {
        // Delay emission of gathers which are not ready yet.
        PostponedGathers.insert(E);
        // Postpone gather emission, will be emitted after the end of the
        // process to keep correct order.
        return *Delayed;
      }
      if (GatherShuffles.size() == 1 &&
          *GatherShuffles.front() == TTI::SK_PermuteSingleSrc &&
          Entries.front().front()->isSame(E->Scalars)) {
        // Perfect match in the graph, will reuse the previously vectorized
        // node. Cost is 0.
        LLVM_DEBUG(dbgs() << "SLP: perfect diamond match for gather bundle "
                          << shortBundleName(E->Scalars, E->Idx) << ".\n");
        // Restore the mask for previous partially matched values.
        Mask.resize(E->Scalars.size());
        const TreeEntry *FrontTE = Entries.front().front();
        if (FrontTE->ReorderIndices.empty() &&
            ((FrontTE->ReuseShuffleIndices.empty() &&
              E->Scalars.size() == FrontTE->Scalars.size()) ||
             (E->Scalars.size() == FrontTE->ReuseShuffleIndices.size()))) {
          std::iota(Mask.begin(), Mask.end(), 0);
        } else {
          for (auto [I, V] : enumerate(E->Scalars)) {
            if (isa<PoisonValue>(V)) {
              Mask[I] = PoisonMaskElem;
              continue;
            }
            Mask[I] = FrontTE->findLaneForValue(V);
          }
        }
        ShuffleBuilder.add(*FrontTE, Mask);
        Res = ShuffleBuilder.finalize(E->getCommonMask(), SubVectors);
        return Res;
      }
      if (!Resized) {
        if (GatheredScalars.size() != VF &&
            any_of(Entries, [&](ArrayRef<const TreeEntry *> TEs) {
              return any_of(TEs, [&](const TreeEntry *TE) {
                return TE->getVectorFactor() == VF;
              });
            }))
          GatheredScalars.append(VF - GatheredScalars.size(),
                                 PoisonValue::get(OrigScalarTy));
      }
      // Remove shuffled elements from list of gathers.
      for (int I = 0, Sz = Mask.size(); I < Sz; ++I) {
        if (Mask[I] != PoisonMaskElem)
          GatheredScalars[I] = PoisonValue::get(OrigScalarTy);
      }
    }
  }
  auto TryPackScalars = [&](SmallVectorImpl<Value *> &Scalars,
                            SmallVectorImpl<int> &ReuseMask,
                            bool IsRootPoison) {
    // For splats with can emit broadcasts instead of gathers, so try to find
    // such sequences.
    bool IsSplat = IsRootPoison && isSplat(Scalars) &&
                   (Scalars.size() > 2 || Scalars.front() == Scalars.back());
    Scalars.append(VF - Scalars.size(), PoisonValue::get(OrigScalarTy));
    SmallVector<int> UndefPos;
    DenseMap<Value *, unsigned> UniquePositions;
    // Gather unique non-const values and all constant values.
    // For repeated values, just shuffle them.
    int NumNonConsts = 0;
    int SinglePos = 0;
    for (auto [I, V] : enumerate(Scalars)) {
      if (isa<UndefValue>(V)) {
        if (!isa<PoisonValue>(V)) {
          ReuseMask[I] = I;
          UndefPos.push_back(I);
        }
        continue;
      }
      if (isConstant(V)) {
        ReuseMask[I] = I;
        continue;
      }
      ++NumNonConsts;
      SinglePos = I;
      Value *OrigV = V;
      Scalars[I] = PoisonValue::get(OrigScalarTy);
      if (IsSplat) {
        Scalars.front() = OrigV;
        ReuseMask[I] = 0;
      } else {
        const auto Res = UniquePositions.try_emplace(OrigV, I);
        Scalars[Res.first->second] = OrigV;
        ReuseMask[I] = Res.first->second;
      }
    }
    if (NumNonConsts == 1) {
      // Restore single insert element.
      if (IsSplat) {
        ReuseMask.assign(VF, PoisonMaskElem);
        std::swap(Scalars.front(), Scalars[SinglePos]);
        if (!UndefPos.empty() && UndefPos.front() == 0)
          Scalars.front() = UndefValue::get(OrigScalarTy);
      }
      ReuseMask[SinglePos] = SinglePos;
    } else if (!UndefPos.empty() && IsSplat) {
      // For undef values, try to replace them with the simple broadcast.
      // We can do it if the broadcasted value is guaranteed to be
      // non-poisonous, or by freezing the incoming scalar value first.
      auto *It = find_if(Scalars, [this, E](Value *V) {
        return !isa<UndefValue>(V) &&
               (getTreeEntry(V) || isGuaranteedNotToBePoison(V) ||
                (E->UserTreeIndices.size() == 1 &&
                 any_of(V->uses(), [E](const Use &U) {
                   // Check if the value already used in the same operation in
                   // one of the nodes already.
                   return E->UserTreeIndices.front().EdgeIdx !=
                              U.getOperandNo() &&
                          is_contained(
                              E->UserTreeIndices.front().UserTE->Scalars,
                              U.getUser());
                 })));
      });
      if (It != Scalars.end()) {
        // Replace undefs by the non-poisoned scalars and emit broadcast.
        int Pos = std::distance(Scalars.begin(), It);
        for (int I : UndefPos) {
          // Set the undef position to the non-poisoned scalar.
          ReuseMask[I] = Pos;
          // Replace the undef by the poison, in the mask it is replaced by
          // non-poisoned scalar already.
          if (I != Pos)
            Scalars[I] = PoisonValue::get(OrigScalarTy);
        }
      } else {
        // Replace undefs by the poisons, emit broadcast and then emit
        // freeze.
        for (int I : UndefPos) {
          ReuseMask[I] = PoisonMaskElem;
          if (isa<UndefValue>(Scalars[I]))
            Scalars[I] = PoisonValue::get(OrigScalarTy);
        }
        NeedFreeze = true;
      }
    }
  };
  if (!ExtractShuffles.empty() || !GatherShuffles.empty()) {
    bool IsNonPoisoned = true;
    bool IsUsedInExpr = true;
    Value *Vec1 = nullptr;
    if (!ExtractShuffles.empty()) {
      // Gather of extractelements can be represented as just a shuffle of
      // a single/two vectors the scalars are extracted from.
      // Find input vectors.
      Value *Vec2 = nullptr;
      for (unsigned I = 0, Sz = ExtractMask.size(); I < Sz; ++I) {
        if (!Mask.empty() && Mask[I] != PoisonMaskElem)
          ExtractMask[I] = PoisonMaskElem;
      }
      if (UseVecBaseAsInput) {
        Vec1 = ExtractVecBase;
      } else {
        for (unsigned I = 0, Sz = ExtractMask.size(); I < Sz; ++I) {
          if (ExtractMask[I] == PoisonMaskElem)
            continue;
          if (isa<UndefValue>(E->Scalars[I]))
            continue;
          auto *EI = cast<ExtractElementInst>(E->Scalars[I]);
          Value *VecOp = EI->getVectorOperand();
          if (const auto *TE = getTreeEntry(VecOp))
            if (TE->VectorizedValue)
              VecOp = TE->VectorizedValue;
          if (!Vec1) {
            Vec1 = VecOp;
          } else if (Vec1 != VecOp) {
            assert((!Vec2 || Vec2 == VecOp) &&
                   "Expected only 1 or 2 vectors shuffle.");
            Vec2 = VecOp;
          }
        }
      }
      if (Vec2) {
        IsUsedInExpr = false;
        IsNonPoisoned &=
            isGuaranteedNotToBePoison(Vec1) && isGuaranteedNotToBePoison(Vec2);
        ShuffleBuilder.add(Vec1, Vec2, ExtractMask);
      } else if (Vec1) {
        IsUsedInExpr &= FindReusedSplat(
            ExtractMask,
            cast<FixedVectorType>(Vec1->getType())->getNumElements(), 0,
            ExtractMask.size());
        ShuffleBuilder.add(Vec1, ExtractMask, /*ForExtracts=*/true);
        IsNonPoisoned &= isGuaranteedNotToBePoison(Vec1);
      } else {
        IsUsedInExpr = false;
        ShuffleBuilder.add(PoisonValue::get(VecTy), ExtractMask,
                           /*ForExtracts=*/true);
      }
    }
    if (!GatherShuffles.empty()) {
      unsigned SliceSize = getPartNumElems(E->Scalars.size(), NumParts);
      SmallVector<int> VecMask(Mask.size(), PoisonMaskElem);
      for (const auto [I, TEs] : enumerate(Entries)) {
        if (TEs.empty()) {
          assert(!GatherShuffles[I] &&
                 "No shuffles with empty entries list expected.");
          continue;
        }
        assert((TEs.size() == 1 || TEs.size() == 2) &&
               "Expected shuffle of 1 or 2 entries.");
        unsigned Limit = getNumElems(Mask.size(), SliceSize, I);
        auto SubMask = ArrayRef(Mask).slice(I * SliceSize, Limit);
        VecMask.assign(VecMask.size(), PoisonMaskElem);
        copy(SubMask, std::next(VecMask.begin(), I * SliceSize));
        if (TEs.size() == 1) {
          IsUsedInExpr &= FindReusedSplat(
              VecMask, TEs.front()->getVectorFactor(), I, SliceSize);
          ShuffleBuilder.add(*TEs.front(), VecMask);
          if (TEs.front()->VectorizedValue)
            IsNonPoisoned &=
                isGuaranteedNotToBePoison(TEs.front()->VectorizedValue);
        } else {
          IsUsedInExpr = false;
          ShuffleBuilder.add(*TEs.front(), *TEs.back(), VecMask);
          if (TEs.front()->VectorizedValue && TEs.back()->VectorizedValue)
            IsNonPoisoned &=
                isGuaranteedNotToBePoison(TEs.front()->VectorizedValue) &&
                isGuaranteedNotToBePoison(TEs.back()->VectorizedValue);
        }
      }
    }
    // Try to figure out best way to combine values: build a shuffle and insert
    // elements or just build several shuffles.
    // Insert non-constant scalars.
    SmallVector<Value *> NonConstants(GatheredScalars);
    int EMSz = ExtractMask.size();
    int MSz = Mask.size();
    // Try to build constant vector and shuffle with it only if currently we
    // have a single permutation and more than 1 scalar constants.
    bool IsSingleShuffle = ExtractShuffles.empty() || GatherShuffles.empty();
    bool IsIdentityShuffle =
        ((UseVecBaseAsInput ||
          all_of(ExtractShuffles,
                 [](const std::optional<TTI::ShuffleKind> &SK) {
                   return SK.value_or(TTI::SK_PermuteTwoSrc) ==
                          TTI::SK_PermuteSingleSrc;
                 })) &&
         none_of(ExtractMask, [&](int I) { return I >= EMSz; }) &&
         ShuffleVectorInst::isIdentityMask(ExtractMask, EMSz)) ||
        (!GatherShuffles.empty() &&
         all_of(GatherShuffles,
                [](const std::optional<TTI::ShuffleKind> &SK) {
                  return SK.value_or(TTI::SK_PermuteTwoSrc) ==
                         TTI::SK_PermuteSingleSrc;
                }) &&
         none_of(Mask, [&](int I) { return I >= MSz; }) &&
         ShuffleVectorInst::isIdentityMask(Mask, MSz));
    bool EnoughConstsForShuffle =
        IsSingleShuffle &&
        (none_of(GatheredScalars,
                 [](Value *V) {
                   return isa<UndefValue>(V) && !isa<PoisonValue>(V);
                 }) ||
         any_of(GatheredScalars,
                [](Value *V) {
                  return isa<Constant>(V) && !isa<UndefValue>(V);
                })) &&
        (!IsIdentityShuffle ||
         (GatheredScalars.size() == 2 &&
          any_of(GatheredScalars,
                 [](Value *V) { return !isa<UndefValue>(V); })) ||
         count_if(GatheredScalars, [](Value *V) {
           return isa<Constant>(V) && !isa<PoisonValue>(V);
         }) > 1);
    // NonConstants array contains just non-constant values, GatheredScalars
    // contains only constant to build final vector and then shuffle.
    for (int I = 0, Sz = GatheredScalars.size(); I < Sz; ++I) {
      if (EnoughConstsForShuffle && isa<Constant>(GatheredScalars[I]))
        NonConstants[I] = PoisonValue::get(OrigScalarTy);
      else
        GatheredScalars[I] = PoisonValue::get(OrigScalarTy);
    }
    // Generate constants for final shuffle and build a mask for them.
    if (!all_of(GatheredScalars, IsaPred<PoisonValue>)) {
      SmallVector<int> BVMask(GatheredScalars.size(), PoisonMaskElem);
      TryPackScalars(GatheredScalars, BVMask, /*IsRootPoison=*/true);
      Value *BV = ShuffleBuilder.gather(GatheredScalars, BVMask.size());
      ShuffleBuilder.add(BV, BVMask);
    }
    if (all_of(NonConstants, [=](Value *V) {
          return isa<PoisonValue>(V) ||
                 (IsSingleShuffle && ((IsIdentityShuffle &&
                  IsNonPoisoned) || IsUsedInExpr) && isa<UndefValue>(V));
        }))
      Res = ShuffleBuilder.finalize(E->ReuseShuffleIndices, SubVectors);
    else
      Res = ShuffleBuilder.finalize(
          E->ReuseShuffleIndices, SubVectors, E->Scalars.size(),
          [&](Value *&Vec, SmallVectorImpl<int> &Mask) {
            TryPackScalars(NonConstants, Mask, /*IsRootPoison=*/false);
            Vec = ShuffleBuilder.gather(NonConstants, Mask.size(), Vec);
          });
  } else if (!allConstant(GatheredScalars)) {
    // Gather unique scalars and all constants.
    SmallVector<int> ReuseMask(GatheredScalars.size(), PoisonMaskElem);
    TryPackScalars(GatheredScalars, ReuseMask, /*IsRootPoison=*/true);
    Value *BV = ShuffleBuilder.gather(GatheredScalars, ReuseMask.size());
    ShuffleBuilder.add(BV, ReuseMask);
    Res = ShuffleBuilder.finalize(E->ReuseShuffleIndices, SubVectors);
  } else {
    // Gather all constants.
    SmallVector<int> Mask(GatheredScalars.size(), PoisonMaskElem);
    for (auto [I, V] : enumerate(GatheredScalars)) {
      if (!isa<PoisonValue>(V))
        Mask[I] = I;
    }
    Value *BV = ShuffleBuilder.gather(GatheredScalars);
    ShuffleBuilder.add(BV, Mask);
    Res = ShuffleBuilder.finalize(E->ReuseShuffleIndices, SubVectors);
  }

  if (NeedFreeze)
    Res = ShuffleBuilder.createFreeze(Res);
  return Res;
}

Value *BoUpSLP::createBuildVector(const TreeEntry *E, Type *ScalarTy,
                                  bool PostponedPHIs) {
  for (auto [EIdx, _] : E->CombinedEntriesWithIndices)
    (void)vectorizeTree(VectorizableTree[EIdx].get(), PostponedPHIs);
  return processBuildVector<ShuffleInstructionBuilder, Value *>(E, ScalarTy,
                                                                Builder, *this);
}

Value *BoUpSLP::vectorizeTree(TreeEntry *E, bool PostponedPHIs) {
  IRBuilderBase::InsertPointGuard Guard(Builder);

  if (E->VectorizedValue &&
      (E->State != TreeEntry::Vectorize || E->getOpcode() != Instruction::PHI ||
       E->isAltShuffle())) {
    LLVM_DEBUG(dbgs() << "SLP: Diamond merged for " << *E->Scalars[0] << ".\n");
    return E->VectorizedValue;
  }

  Value *V = E->Scalars.front();
  Type *ScalarTy = V->getType();
  if (!isa<CmpInst>(V))
    ScalarTy = getValueType(V);
  auto It = MinBWs.find(E);
  if (It != MinBWs.end()) {
    auto *VecTy = dyn_cast<FixedVectorType>(ScalarTy);
    ScalarTy = IntegerType::get(F->getContext(), It->second.first);
    if (VecTy)
      ScalarTy = getWidenedType(ScalarTy, VecTy->getNumElements());
  }
  auto *VecTy = getWidenedType(ScalarTy, E->Scalars.size());
  if (E->isGather()) {
    // Set insert point for non-reduction initial nodes.
    if (E->getMainOp() && E->Idx == 0 && !UserIgnoreList)
      setInsertPointAfterBundle(E);
    Value *Vec = createBuildVector(E, ScalarTy, PostponedPHIs);
    E->VectorizedValue = Vec;
    return Vec;
  }

  bool IsReverseOrder = isReverseOrder(E->ReorderIndices);
  auto FinalShuffle = [&](Value *V, const TreeEntry *E) {
    ShuffleInstructionBuilder ShuffleBuilder(ScalarTy, Builder, *this);
    if (E->getOpcode() == Instruction::Store &&
        E->State == TreeEntry::Vectorize) {
      ArrayRef<int> Mask =
          ArrayRef(reinterpret_cast<const int *>(E->ReorderIndices.begin()),
                   E->ReorderIndices.size());
      ShuffleBuilder.add(V, Mask);
    } else if (E->State == TreeEntry::StridedVectorize && IsReverseOrder) {
      ShuffleBuilder.addOrdered(V, {});
    } else {
      ShuffleBuilder.addOrdered(V, E->ReorderIndices);
    }
    SmallVector<std::pair<const TreeEntry *, unsigned>> SubVectors(
        E->CombinedEntriesWithIndices.size());
    transform(
        E->CombinedEntriesWithIndices, SubVectors.begin(), [&](const auto &P) {
          return std::make_pair(VectorizableTree[P.first].get(), P.second);
        });
    return ShuffleBuilder.finalize(E->ReuseShuffleIndices, SubVectors);
  };

  assert(!E->isGather() && "Unhandled state");
  unsigned ShuffleOrOp =
      E->isAltShuffle() ? (unsigned)Instruction::ShuffleVector : E->getOpcode();
  Instruction *VL0 = E->getMainOp();
  auto GetOperandSignedness = [&](unsigned Idx) {
    const TreeEntry *OpE = getOperandEntry(E, Idx);
    bool IsSigned = false;
    auto It = MinBWs.find(OpE);
    if (It != MinBWs.end())
      IsSigned = It->second.second;
    else
      IsSigned = any_of(OpE->Scalars, [&](Value *R) {
        return !isKnownNonNegative(R, SimplifyQuery(*DL));
      });
    return IsSigned;
  };
  switch (ShuffleOrOp) {
    case Instruction::PHI: {
      assert((E->ReorderIndices.empty() || !E->ReuseShuffleIndices.empty() ||
              E != VectorizableTree.front().get() ||
              !E->UserTreeIndices.empty()) &&
             "PHI reordering is free.");
      if (PostponedPHIs && E->VectorizedValue)
        return E->VectorizedValue;
      auto *PH = cast<PHINode>(VL0);
      Builder.SetInsertPoint(PH->getParent(),
                             PH->getParent()->getFirstNonPHIIt());
      Builder.SetCurrentDebugLocation(PH->getDebugLoc());
      if (PostponedPHIs || !E->VectorizedValue) {
        PHINode *NewPhi = Builder.CreatePHI(VecTy, PH->getNumIncomingValues());
        E->PHI = NewPhi;
        Value *V = NewPhi;

        // Adjust insertion point once all PHI's have been generated.
        Builder.SetInsertPoint(PH->getParent(),
                               PH->getParent()->getFirstInsertionPt());
        Builder.SetCurrentDebugLocation(PH->getDebugLoc());

        V = FinalShuffle(V, E);

        E->VectorizedValue = V;
        if (PostponedPHIs)
          return V;
      }
      PHINode *NewPhi = cast<PHINode>(E->PHI);
      // If phi node is fully emitted - exit.
      if (NewPhi->getNumIncomingValues() != 0)
        return NewPhi;

      // PHINodes may have multiple entries from the same block. We want to
      // visit every block once.
      SmallPtrSet<BasicBlock *, 4> VisitedBBs;

      for (unsigned I : seq<unsigned>(0, PH->getNumIncomingValues())) {
        ValueList Operands;
        BasicBlock *IBB = PH->getIncomingBlock(I);

        // Stop emission if all incoming values are generated.
        if (NewPhi->getNumIncomingValues() == PH->getNumIncomingValues()) {
          LLVM_DEBUG(dbgs() << "SLP: Diamond merged for " << *VL0 << ".\n");
          return NewPhi;
        }

        if (!VisitedBBs.insert(IBB).second) {
          NewPhi->addIncoming(NewPhi->getIncomingValueForBlock(IBB), IBB);
          continue;
        }

        Builder.SetInsertPoint(IBB->getTerminator());
        Builder.SetCurrentDebugLocation(PH->getDebugLoc());
        Value *Vec = vectorizeOperand(E, I, /*PostponedPHIs=*/true);
        if (VecTy != Vec->getType()) {
          assert((It != MinBWs.end() || getOperandEntry(E, I)->isGather() ||
                  MinBWs.contains(getOperandEntry(E, I))) &&
                 "Expected item in MinBWs.");
          Vec = Builder.CreateIntCast(Vec, VecTy, GetOperandSignedness(I));
        }
        NewPhi->addIncoming(Vec, IBB);
      }

      assert(NewPhi->getNumIncomingValues() == PH->getNumIncomingValues() &&
             "Invalid number of incoming values");
      assert(E->VectorizedValue && "Expected vectorized value.");
      return E->VectorizedValue;
    }

    case Instruction::ExtractElement: {
      Value *V = E->getSingleOperand(0);
      if (const TreeEntry *TE = getTreeEntry(V))
        V = TE->VectorizedValue;
      setInsertPointAfterBundle(E);
      V = FinalShuffle(V, E);
      E->VectorizedValue = V;
      return V;
    }
    case Instruction::ExtractValue: {
      auto *LI = cast<LoadInst>(E->getSingleOperand(0));
      Builder.SetInsertPoint(LI);
      Value *Ptr = LI->getPointerOperand();
      LoadInst *V = Builder.CreateAlignedLoad(VecTy, Ptr, LI->getAlign());
      Value *NewV = propagateMetadata(V, E->Scalars);
      NewV = FinalShuffle(NewV, E);
      E->VectorizedValue = NewV;
      return NewV;
    }
    case Instruction::InsertElement: {
      assert(E->ReuseShuffleIndices.empty() && "All inserts should be unique");
      Builder.SetInsertPoint(cast<Instruction>(E->Scalars.back()));
      Value *V = vectorizeOperand(E, 1, PostponedPHIs);
      ArrayRef<Value *> Op = E->getOperand(1);
      Type *ScalarTy = Op.front()->getType();
      if (cast<VectorType>(V->getType())->getElementType() != ScalarTy) {
        assert(ScalarTy->isIntegerTy() && "Expected item in MinBWs.");
        std::pair<unsigned, bool> Res = MinBWs.lookup(getOperandEntry(E, 1));
        assert(Res.first > 0 && "Expected item in MinBWs.");
        V = Builder.CreateIntCast(
            V,
            getWidenedType(
                ScalarTy,
                cast<FixedVectorType>(V->getType())->getNumElements()),
            Res.second);
      }

      // Create InsertVector shuffle if necessary
      auto *FirstInsert = cast<Instruction>(*find_if(E->Scalars, [E](Value *V) {
        return !is_contained(E->Scalars, cast<Instruction>(V)->getOperand(0));
      }));
      const unsigned NumElts =
          cast<FixedVectorType>(FirstInsert->getType())->getNumElements();
      const unsigned NumScalars = E->Scalars.size();

      unsigned Offset = *getElementIndex(VL0);
      assert(Offset < NumElts && "Failed to find vector index offset");

      // Create shuffle to resize vector
      SmallVector<int> Mask;
      if (!E->ReorderIndices.empty()) {
        inversePermutation(E->ReorderIndices, Mask);
        Mask.append(NumElts - NumScalars, PoisonMaskElem);
      } else {
        Mask.assign(NumElts, PoisonMaskElem);
        std::iota(Mask.begin(), std::next(Mask.begin(), NumScalars), 0);
      }
      // Create InsertVector shuffle if necessary
      bool IsIdentity = true;
      SmallVector<int> PrevMask(NumElts, PoisonMaskElem);
      Mask.swap(PrevMask);
      for (unsigned I = 0; I < NumScalars; ++I) {
        Value *Scalar = E->Scalars[PrevMask[I]];
        unsigned InsertIdx = *getElementIndex(Scalar);
        IsIdentity &= InsertIdx - Offset == I;
        Mask[InsertIdx - Offset] = I;
      }
      if (!IsIdentity || NumElts != NumScalars) {
        Value *V2 = nullptr;
        bool IsVNonPoisonous = isGuaranteedNotToBePoison(V) && !isConstant(V);
        SmallVector<int> InsertMask(Mask);
        if (NumElts != NumScalars && Offset == 0) {
          // Follow all insert element instructions from the current buildvector
          // sequence.
          InsertElementInst *Ins = cast<InsertElementInst>(VL0);
          do {
            std::optional<unsigned> InsertIdx = getElementIndex(Ins);
            if (!InsertIdx)
              break;
            if (InsertMask[*InsertIdx] == PoisonMaskElem)
              InsertMask[*InsertIdx] = *InsertIdx;
            if (!Ins->hasOneUse())
              break;
            Ins = dyn_cast_or_null<InsertElementInst>(
                Ins->getUniqueUndroppableUser());
          } while (Ins);
          SmallBitVector UseMask =
              buildUseMask(NumElts, InsertMask, UseMask::UndefsAsMask);
          SmallBitVector IsFirstPoison =
              isUndefVector<true>(FirstInsert->getOperand(0), UseMask);
          SmallBitVector IsFirstUndef =
              isUndefVector(FirstInsert->getOperand(0), UseMask);
          if (!IsFirstPoison.all()) {
            unsigned Idx = 0;
            for (unsigned I = 0; I < NumElts; I++) {
              if (InsertMask[I] == PoisonMaskElem && !IsFirstPoison.test(I) &&
                  IsFirstUndef.test(I)) {
                if (IsVNonPoisonous) {
                  InsertMask[I] = I < NumScalars ? I : 0;
                  continue;
                }
                if (!V2)
                  V2 = UndefValue::get(V->getType());
                if (Idx >= NumScalars)
                  Idx = NumScalars - 1;
                InsertMask[I] = NumScalars + Idx;
                ++Idx;
              } else if (InsertMask[I] != PoisonMaskElem &&
                         Mask[I] == PoisonMaskElem) {
                InsertMask[I] = PoisonMaskElem;
              }
            }
          } else {
            InsertMask = Mask;
          }
        }
        if (!V2)
          V2 = PoisonValue::get(V->getType());
        V = Builder.CreateShuffleVector(V, V2, InsertMask);
        if (auto *I = dyn_cast<Instruction>(V)) {
          GatherShuffleExtractSeq.insert(I);
          CSEBlocks.insert(I->getParent());
        }
      }

      SmallVector<int> InsertMask(NumElts, PoisonMaskElem);
      for (unsigned I = 0; I < NumElts; I++) {
        if (Mask[I] != PoisonMaskElem)
          InsertMask[Offset + I] = I;
      }
      SmallBitVector UseMask =
          buildUseMask(NumElts, InsertMask, UseMask::UndefsAsMask);
      SmallBitVector IsFirstUndef =
          isUndefVector(FirstInsert->getOperand(0), UseMask);
      if ((!IsIdentity || Offset != 0 || !IsFirstUndef.all()) &&
          NumElts != NumScalars) {
        if (IsFirstUndef.all()) {
          if (!ShuffleVectorInst::isIdentityMask(InsertMask, NumElts)) {
            SmallBitVector IsFirstPoison =
                isUndefVector<true>(FirstInsert->getOperand(0), UseMask);
            if (!IsFirstPoison.all()) {
              for (unsigned I = 0; I < NumElts; I++) {
                if (InsertMask[I] == PoisonMaskElem && !IsFirstPoison.test(I))
                  InsertMask[I] = I + NumElts;
              }
            }
            V = Builder.CreateShuffleVector(
                V,
                IsFirstPoison.all() ? PoisonValue::get(V->getType())
                                    : FirstInsert->getOperand(0),
                InsertMask, cast<Instruction>(E->Scalars.back())->getName());
            if (auto *I = dyn_cast<Instruction>(V)) {
              GatherShuffleExtractSeq.insert(I);
              CSEBlocks.insert(I->getParent());
            }
          }
        } else {
          SmallBitVector IsFirstPoison =
              isUndefVector<true>(FirstInsert->getOperand(0), UseMask);
          for (unsigned I = 0; I < NumElts; I++) {
            if (InsertMask[I] == PoisonMaskElem)
              InsertMask[I] = IsFirstPoison.test(I) ? PoisonMaskElem : I;
            else
              InsertMask[I] += NumElts;
          }
          V = Builder.CreateShuffleVector(
              FirstInsert->getOperand(0), V, InsertMask,
              cast<Instruction>(E->Scalars.back())->getName());
          if (auto *I = dyn_cast<Instruction>(V)) {
            GatherShuffleExtractSeq.insert(I);
            CSEBlocks.insert(I->getParent());
          }
        }
      }

      ++NumVectorInstructions;
      E->VectorizedValue = V;
      return V;
    }
    case Instruction::ZExt:
    case Instruction::SExt:
    case Instruction::FPToUI:
    case Instruction::FPToSI:
    case Instruction::FPExt:
    case Instruction::PtrToInt:
    case Instruction::IntToPtr:
    case Instruction::SIToFP:
    case Instruction::UIToFP:
    case Instruction::Trunc:
    case Instruction::FPTrunc:
    case Instruction::BitCast: {
      setInsertPointAfterBundle(E);

      Value *InVec = vectorizeOperand(E, 0, PostponedPHIs);
      if (E->VectorizedValue) {
        LLVM_DEBUG(dbgs() << "SLP: Diamond merged for " << *VL0 << ".\n");
        return E->VectorizedValue;
      }

      auto *CI = cast<CastInst>(VL0);
      Instruction::CastOps VecOpcode = CI->getOpcode();
      Type *SrcScalarTy = cast<VectorType>(InVec->getType())->getElementType();
      auto SrcIt = MinBWs.find(getOperandEntry(E, 0));
      if (!ScalarTy->isFPOrFPVectorTy() && !SrcScalarTy->isFPOrFPVectorTy() &&
          (SrcIt != MinBWs.end() || It != MinBWs.end() ||
           SrcScalarTy != CI->getOperand(0)->getType()->getScalarType())) {
        // Check if the values are candidates to demote.
        unsigned SrcBWSz = DL->getTypeSizeInBits(SrcScalarTy);
        if (SrcIt != MinBWs.end())
          SrcBWSz = SrcIt->second.first;
        unsigned BWSz = DL->getTypeSizeInBits(ScalarTy->getScalarType());
        if (BWSz == SrcBWSz) {
          VecOpcode = Instruction::BitCast;
        } else if (BWSz < SrcBWSz) {
          VecOpcode = Instruction::Trunc;
        } else if (It != MinBWs.end()) {
          assert(BWSz > SrcBWSz && "Invalid cast!");
          VecOpcode = It->second.second ? Instruction::SExt : Instruction::ZExt;
        } else if (SrcIt != MinBWs.end()) {
          assert(BWSz > SrcBWSz && "Invalid cast!");
          VecOpcode =
              SrcIt->second.second ? Instruction::SExt : Instruction::ZExt;
        }
      } else if (VecOpcode == Instruction::SIToFP && SrcIt != MinBWs.end() &&
                 !SrcIt->second.second) {
        VecOpcode = Instruction::UIToFP;
      }
      Value *V = (VecOpcode != ShuffleOrOp && VecOpcode == Instruction::BitCast)
                     ? InVec
                     : Builder.CreateCast(VecOpcode, InVec, VecTy);
      V = FinalShuffle(V, E);

      E->VectorizedValue = V;
      ++NumVectorInstructions;
      return V;
    }
    case Instruction::FCmp:
    case Instruction::ICmp: {
      setInsertPointAfterBundle(E);

      Value *L = vectorizeOperand(E, 0, PostponedPHIs);
      if (E->VectorizedValue) {
        LLVM_DEBUG(dbgs() << "SLP: Diamond merged for " << *VL0 << ".\n");
        return E->VectorizedValue;
      }
      Value *R = vectorizeOperand(E, 1, PostponedPHIs);
      if (E->VectorizedValue) {
        LLVM_DEBUG(dbgs() << "SLP: Diamond merged for " << *VL0 << ".\n");
        return E->VectorizedValue;
      }
      if (L->getType() != R->getType()) {
        assert((getOperandEntry(E, 0)->isGather() ||
                getOperandEntry(E, 1)->isGather() ||
                MinBWs.contains(getOperandEntry(E, 0)) ||
                MinBWs.contains(getOperandEntry(E, 1))) &&
               "Expected item in MinBWs.");
        if (cast<VectorType>(L->getType())
                ->getElementType()
                ->getIntegerBitWidth() < cast<VectorType>(R->getType())
                                             ->getElementType()
                                             ->getIntegerBitWidth()) {
          Type *CastTy = R->getType();
          L = Builder.CreateIntCast(L, CastTy, GetOperandSignedness(0));
        } else {
          Type *CastTy = L->getType();
          R = Builder.CreateIntCast(R, CastTy, GetOperandSignedness(1));
        }
      }

      CmpInst::Predicate P0 = cast<CmpInst>(VL0)->getPredicate();
      Value *V = Builder.CreateCmp(P0, L, R);
      propagateIRFlags(V, E->Scalars, VL0);
      // Do not cast for cmps.
      VecTy = cast<FixedVectorType>(V->getType());
      V = FinalShuffle(V, E);

      E->VectorizedValue = V;
      ++NumVectorInstructions;
      return V;
    }
    case Instruction::Select: {
      setInsertPointAfterBundle(E);

      Value *Cond = vectorizeOperand(E, 0, PostponedPHIs);
      if (E->VectorizedValue) {
        LLVM_DEBUG(dbgs() << "SLP: Diamond merged for " << *VL0 << ".\n");
        return E->VectorizedValue;
      }
      Value *True = vectorizeOperand(E, 1, PostponedPHIs);
      if (E->VectorizedValue) {
        LLVM_DEBUG(dbgs() << "SLP: Diamond merged for " << *VL0 << ".\n");
        return E->VectorizedValue;
      }
      Value *False = vectorizeOperand(E, 2, PostponedPHIs);
      if (E->VectorizedValue) {
        LLVM_DEBUG(dbgs() << "SLP: Diamond merged for " << *VL0 << ".\n");
        return E->VectorizedValue;
      }
      if (True->getType() != VecTy || False->getType() != VecTy) {
        assert((It != MinBWs.end() || getOperandEntry(E, 1)->isGather() ||
                getOperandEntry(E, 2)->isGather() ||
                MinBWs.contains(getOperandEntry(E, 1)) ||
                MinBWs.contains(getOperandEntry(E, 2))) &&
               "Expected item in MinBWs.");
        if (True->getType() != VecTy)
          True = Builder.CreateIntCast(True, VecTy, GetOperandSignedness(1));
        if (False->getType() != VecTy)
          False = Builder.CreateIntCast(False, VecTy, GetOperandSignedness(2));
      }

      unsigned CondNumElements = getNumElements(Cond->getType());
      unsigned TrueNumElements = getNumElements(True->getType());
      assert(TrueNumElements >= CondNumElements &&
             TrueNumElements % CondNumElements == 0 &&
             "Cannot vectorize Instruction::Select");
      assert(TrueNumElements == getNumElements(False->getType()) &&
             "Cannot vectorize Instruction::Select");
      if (CondNumElements != TrueNumElements) {
        // When the return type is i1 but the source is fixed vector type, we
        // need to duplicate the condition value.
        Cond = Builder.CreateShuffleVector(
            Cond, createReplicatedMask(TrueNumElements / CondNumElements,
                                       CondNumElements));
      }
      assert(getNumElements(Cond->getType()) == TrueNumElements &&
             "Cannot vectorize Instruction::Select");
      Value *V = Builder.CreateSelect(Cond, True, False);
      V = FinalShuffle(V, E);

      E->VectorizedValue = V;
      ++NumVectorInstructions;
      return V;
    }
    case Instruction::FNeg: {
      setInsertPointAfterBundle(E);

      Value *Op = vectorizeOperand(E, 0, PostponedPHIs);

      if (E->VectorizedValue) {
        LLVM_DEBUG(dbgs() << "SLP: Diamond merged for " << *VL0 << ".\n");
        return E->VectorizedValue;
      }

      Value *V = Builder.CreateUnOp(
          static_cast<Instruction::UnaryOps>(E->getOpcode()), Op);
      propagateIRFlags(V, E->Scalars, VL0);
      if (auto *I = dyn_cast<Instruction>(V))
        V = propagateMetadata(I, E->Scalars);

      V = FinalShuffle(V, E);

      E->VectorizedValue = V;
      ++NumVectorInstructions;

      return V;
    }
    case Instruction::Freeze: {
      setInsertPointAfterBundle(E);

      Value *Op = vectorizeOperand(E, 0, PostponedPHIs);

      if (E->VectorizedValue) {
        LLVM_DEBUG(dbgs() << "SLP: Diamond merged for " << *VL0 << ".\n");
        return E->VectorizedValue;
      }

      Value *V = Builder.CreateFreeze(Op);
      V = FinalShuffle(V, E);

      E->VectorizedValue = V;
      ++NumVectorInstructions;

      return V;
    }
    case Instruction::Add:
    case Instruction::FAdd:
    case Instruction::Sub:
    case Instruction::FSub:
    case Instruction::Mul:
    case Instruction::FMul:
    case Instruction::UDiv:
    case Instruction::SDiv:
    case Instruction::FDiv:
    case Instruction::URem:
    case Instruction::SRem:
    case Instruction::FRem:
    case Instruction::Shl:
    case Instruction::LShr:
    case Instruction::AShr:
    case Instruction::And:
    case Instruction::Or:
    case Instruction::Xor: {
      setInsertPointAfterBundle(E);

      Value *LHS = vectorizeOperand(E, 0, PostponedPHIs);
      if (E->VectorizedValue) {
        LLVM_DEBUG(dbgs() << "SLP: Diamond merged for " << *VL0 << ".\n");
        return E->VectorizedValue;
      }
      Value *RHS = vectorizeOperand(E, 1, PostponedPHIs);
      if (E->VectorizedValue) {
        LLVM_DEBUG(dbgs() << "SLP: Diamond merged for " << *VL0 << ".\n");
        return E->VectorizedValue;
      }
      if (ShuffleOrOp == Instruction::And && It != MinBWs.end()) {
        for (unsigned I : seq<unsigned>(0, E->getNumOperands())) {
          ArrayRef<Value *> Ops = E->getOperand(I);
          if (all_of(Ops, [&](Value *Op) {
                auto *CI = dyn_cast<ConstantInt>(Op);
                return CI && CI->getValue().countr_one() >= It->second.first;
              })) {
            V = FinalShuffle(I == 0 ? RHS : LHS, E);
            E->VectorizedValue = V;
            ++NumVectorInstructions;
            return V;
          }
        }
      }
      if (LHS->getType() != VecTy || RHS->getType() != VecTy) {
        assert((It != MinBWs.end() || getOperandEntry(E, 0)->isGather() ||
                getOperandEntry(E, 1)->isGather() ||
                MinBWs.contains(getOperandEntry(E, 0)) ||
                MinBWs.contains(getOperandEntry(E, 1))) &&
               "Expected item in MinBWs.");
        if (LHS->getType() != VecTy)
          LHS = Builder.CreateIntCast(LHS, VecTy, GetOperandSignedness(0));
        if (RHS->getType() != VecTy)
          RHS = Builder.CreateIntCast(RHS, VecTy, GetOperandSignedness(1));
      }

      Value *V = Builder.CreateBinOp(
          static_cast<Instruction::BinaryOps>(E->getOpcode()), LHS,
          RHS);
      propagateIRFlags(V, E->Scalars, VL0, It == MinBWs.end());
      if (auto *I = dyn_cast<Instruction>(V)) {
        V = propagateMetadata(I, E->Scalars);
        // Drop nuw flags for abs(sub(commutative), true).
        if (!MinBWs.contains(E) && ShuffleOrOp == Instruction::Sub &&
            any_of(E->Scalars, [](Value *V) {
              return isCommutative(cast<Instruction>(V));
            }))
          I->setHasNoUnsignedWrap(/*b=*/false);
      }

      V = FinalShuffle(V, E);

      E->VectorizedValue = V;
      ++NumVectorInstructions;

      return V;
    }
    case Instruction::Load: {
      // Loads are inserted at the head of the tree because we don't want to
      // sink them all the way down past store instructions.
      setInsertPointAfterBundle(E);

      LoadInst *LI = cast<LoadInst>(VL0);
      Instruction *NewLI;
      Value *PO = LI->getPointerOperand();
      if (E->State == TreeEntry::Vectorize) {
        NewLI = Builder.CreateAlignedLoad(VecTy, PO, LI->getAlign());
      } else if (E->State == TreeEntry::StridedVectorize) {
        Value *Ptr0 = cast<LoadInst>(E->Scalars.front())->getPointerOperand();
        Value *PtrN = cast<LoadInst>(E->Scalars.back())->getPointerOperand();
        PO = IsReverseOrder ? PtrN : Ptr0;
        std::optional<int> Diff = getPointersDiff(
            VL0->getType(), Ptr0, VL0->getType(), PtrN, *DL, *SE);
        Type *StrideTy = DL->getIndexType(PO->getType());
        Value *StrideVal;
        if (Diff) {
          int Stride = *Diff / (static_cast<int>(E->Scalars.size()) - 1);
          StrideVal =
              ConstantInt::get(StrideTy, (IsReverseOrder ? -1 : 1) * Stride *
                                             DL->getTypeAllocSize(ScalarTy));
        } else {
          SmallVector<Value *> PointerOps(E->Scalars.size(), nullptr);
          transform(E->Scalars, PointerOps.begin(), [](Value *V) {
            return cast<LoadInst>(V)->getPointerOperand();
          });
          OrdersType Order;
          std::optional<Value *> Stride =
              calculateRtStride(PointerOps, ScalarTy, *DL, *SE, Order,
                                &*Builder.GetInsertPoint());
          Value *NewStride =
              Builder.CreateIntCast(*Stride, StrideTy, /*isSigned=*/true);
          StrideVal = Builder.CreateMul(
              NewStride,
              ConstantInt::get(
                  StrideTy,
                  (IsReverseOrder ? -1 : 1) *
                      static_cast<int>(DL->getTypeAllocSize(ScalarTy))));
        }
        Align CommonAlignment = computeCommonAlignment<LoadInst>(E->Scalars);
        auto *Inst = Builder.CreateIntrinsic(
            Intrinsic::experimental_vp_strided_load,
            {VecTy, PO->getType(), StrideTy},
            {PO, StrideVal, Builder.getAllOnesMask(VecTy->getElementCount()),
             Builder.getInt32(E->Scalars.size())});
        Inst->addParamAttr(
            /*ArgNo=*/0,
            Attribute::getWithAlignment(Inst->getContext(), CommonAlignment));
        NewLI = Inst;
      } else {
        assert(E->State == TreeEntry::ScatterVectorize && "Unhandled state");
        Value *VecPtr = vectorizeOperand(E, 0, PostponedPHIs);
        if (E->VectorizedValue) {
          LLVM_DEBUG(dbgs() << "SLP: Diamond merged for " << *VL0 << ".\n");
          return E->VectorizedValue;
        }
        if (isa<FixedVectorType>(ScalarTy)) {
          assert(SLPReVec && "FixedVectorType is not expected.");
          // CreateMaskedGather expects VecTy and VecPtr have same size. We need
          // to expand VecPtr if ScalarTy is a vector type.
          unsigned ScalarTyNumElements =
              cast<FixedVectorType>(ScalarTy)->getNumElements();
          unsigned VecTyNumElements =
              cast<FixedVectorType>(VecTy)->getNumElements();
          assert(VecTyNumElements % ScalarTyNumElements == 0 &&
                 "Cannot expand getelementptr.");
          unsigned VF = VecTyNumElements / ScalarTyNumElements;
          SmallVector<Constant *> Indices(VecTyNumElements);
          transform(seq(VecTyNumElements), Indices.begin(), [=](unsigned I) {
            return Builder.getInt64(I % ScalarTyNumElements);
          });
          VecPtr = Builder.CreateGEP(
              VecTy->getElementType(),
              Builder.CreateShuffleVector(
                  VecPtr, createReplicatedMask(ScalarTyNumElements, VF)),
              ConstantVector::get(Indices));
        }
        // Use the minimum alignment of the gathered loads.
        Align CommonAlignment = computeCommonAlignment<LoadInst>(E->Scalars);
        NewLI = Builder.CreateMaskedGather(VecTy, VecPtr, CommonAlignment);
      }
      Value *V = propagateMetadata(NewLI, E->Scalars);

      V = FinalShuffle(V, E);
      E->VectorizedValue = V;
      ++NumVectorInstructions;
      return V;
    }
    case Instruction::Store: {
      auto *SI = cast<StoreInst>(VL0);

      setInsertPointAfterBundle(E);

      Value *VecValue = vectorizeOperand(E, 0, PostponedPHIs);
      if (VecValue->getType() != VecTy)
        VecValue =
            Builder.CreateIntCast(VecValue, VecTy, GetOperandSignedness(0));
      VecValue = FinalShuffle(VecValue, E);

      Value *Ptr = SI->getPointerOperand();
      Instruction *ST;
      if (E->State == TreeEntry::Vectorize) {
        ST = Builder.CreateAlignedStore(VecValue, Ptr, SI->getAlign());
      } else {
        assert(E->State == TreeEntry::StridedVectorize &&
               "Expected either strided or consecutive stores.");
        if (!E->ReorderIndices.empty()) {
          SI = cast<StoreInst>(E->Scalars[E->ReorderIndices.front()]);
          Ptr = SI->getPointerOperand();
        }
        Align CommonAlignment = computeCommonAlignment<StoreInst>(E->Scalars);
        Type *StrideTy = DL->getIndexType(SI->getPointerOperandType());
        auto *Inst = Builder.CreateIntrinsic(
            Intrinsic::experimental_vp_strided_store,
            {VecTy, Ptr->getType(), StrideTy},
            {VecValue, Ptr,
             ConstantInt::get(
                 StrideTy, -static_cast<int>(DL->getTypeAllocSize(ScalarTy))),
             Builder.getAllOnesMask(VecTy->getElementCount()),
             Builder.getInt32(E->Scalars.size())});
        Inst->addParamAttr(
            /*ArgNo=*/1,
            Attribute::getWithAlignment(Inst->getContext(), CommonAlignment));
        ST = Inst;
      }

      Value *V = propagateMetadata(ST, E->Scalars);

      E->VectorizedValue = V;
      ++NumVectorInstructions;
      return V;
    }
    case Instruction::GetElementPtr: {
      auto *GEP0 = cast<GetElementPtrInst>(VL0);
      setInsertPointAfterBundle(E);

      Value *Op0 = vectorizeOperand(E, 0, PostponedPHIs);
      if (E->VectorizedValue) {
        LLVM_DEBUG(dbgs() << "SLP: Diamond merged for " << *VL0 << ".\n");
        return E->VectorizedValue;
      }

      SmallVector<Value *> OpVecs;
      for (int J = 1, N = GEP0->getNumOperands(); J < N; ++J) {
        Value *OpVec = vectorizeOperand(E, J, PostponedPHIs);
        if (E->VectorizedValue) {
          LLVM_DEBUG(dbgs() << "SLP: Diamond merged for " << *VL0 << ".\n");
          return E->VectorizedValue;
        }
        OpVecs.push_back(OpVec);
      }

      Value *V = Builder.CreateGEP(GEP0->getSourceElementType(), Op0, OpVecs);
      if (Instruction *I = dyn_cast<GetElementPtrInst>(V)) {
        SmallVector<Value *> GEPs;
        for (Value *V : E->Scalars) {
          if (isa<GetElementPtrInst>(V))
            GEPs.push_back(V);
        }
        V = propagateMetadata(I, GEPs);
      }

      V = FinalShuffle(V, E);

      E->VectorizedValue = V;
      ++NumVectorInstructions;

      return V;
    }
    case Instruction::Call: {
      CallInst *CI = cast<CallInst>(VL0);
      setInsertPointAfterBundle(E);

      Intrinsic::ID ID = getVectorIntrinsicIDForCall(CI, TLI);

      SmallVector<Type *> ArgTys =
          buildIntrinsicArgTypes(CI, ID, VecTy->getNumElements(),
                                 It != MinBWs.end() ? It->second.first : 0);
      auto VecCallCosts = getVectorCallCosts(CI, VecTy, TTI, TLI, ArgTys);
      bool UseIntrinsic = ID != Intrinsic::not_intrinsic &&
                          VecCallCosts.first <= VecCallCosts.second;

      Value *ScalarArg = nullptr;
      SmallVector<Value *> OpVecs;
      SmallVector<Type *, 2> TysForDecl;
      // Add return type if intrinsic is overloaded on it.
      if (UseIntrinsic && isVectorIntrinsicWithOverloadTypeAtArg(ID, -1))
        TysForDecl.push_back(VecTy);
      auto *CEI = cast<CallInst>(VL0);
      for (unsigned I : seq<unsigned>(0, CI->arg_size())) {
        ValueList OpVL;
        // Some intrinsics have scalar arguments. This argument should not be
        // vectorized.
        if (UseIntrinsic && isVectorIntrinsicWithScalarOpAtArg(ID, I)) {
          ScalarArg = CEI->getArgOperand(I);
          // if decided to reduce bitwidth of abs intrinsic, it second argument
          // must be set false (do not return poison, if value issigned min).
          if (ID == Intrinsic::abs && It != MinBWs.end() &&
              It->second.first < DL->getTypeSizeInBits(CEI->getType()))
            ScalarArg = Builder.getFalse();
          OpVecs.push_back(ScalarArg);
          if (isVectorIntrinsicWithOverloadTypeAtArg(ID, I))
            TysForDecl.push_back(ScalarArg->getType());
          continue;
        }

        Value *OpVec = vectorizeOperand(E, I, PostponedPHIs);
        if (E->VectorizedValue) {
          LLVM_DEBUG(dbgs() << "SLP: Diamond merged for " << *VL0 << ".\n");
          return E->VectorizedValue;
        }
        ScalarArg = CEI->getArgOperand(I);
        if (cast<VectorType>(OpVec->getType())->getElementType() !=
                ScalarArg->getType()->getScalarType() &&
            It == MinBWs.end()) {
          auto *CastTy =
              getWidenedType(ScalarArg->getType(), VecTy->getNumElements());
          OpVec = Builder.CreateIntCast(OpVec, CastTy, GetOperandSignedness(I));
        } else if (It != MinBWs.end()) {
          OpVec = Builder.CreateIntCast(OpVec, VecTy, GetOperandSignedness(I));
        }
        LLVM_DEBUG(dbgs() << "SLP: OpVec[" << I << "]: " << *OpVec << "\n");
        OpVecs.push_back(OpVec);
        if (UseIntrinsic && isVectorIntrinsicWithOverloadTypeAtArg(ID, I))
          TysForDecl.push_back(OpVec->getType());
      }

      Function *CF;
      if (!UseIntrinsic) {
        VFShape Shape =
            VFShape::get(CI->getFunctionType(),
                         ElementCount::getFixed(
                             static_cast<unsigned>(VecTy->getNumElements())),
                         false /*HasGlobalPred*/);
        CF = VFDatabase(*CI).getVectorizedFunction(Shape);
      } else {
        CF = Intrinsic::getDeclaration(F->getParent(), ID, TysForDecl);
      }

      SmallVector<OperandBundleDef, 1> OpBundles;
      CI->getOperandBundlesAsDefs(OpBundles);
      Value *V = Builder.CreateCall(CF, OpVecs, OpBundles);

      propagateIRFlags(V, E->Scalars, VL0);
      V = FinalShuffle(V, E);

      E->VectorizedValue = V;
      ++NumVectorInstructions;
      return V;
    }
    case Instruction::ShuffleVector: {
      Value *V;
      if (SLPReVec && !E->isAltShuffle()) {
        assert(E->ReuseShuffleIndices.empty() &&
               "Not support ReuseShuffleIndices yet.");
        assert(E->ReorderIndices.empty() && "Not support ReorderIndices yet.");
        setInsertPointAfterBundle(E);
        Value *Src = vectorizeOperand(E, 0, PostponedPHIs);
        if (E->VectorizedValue) {
          LLVM_DEBUG(dbgs() << "SLP: Diamond merged for " << *VL0 << ".\n");
          return E->VectorizedValue;
        }
        assert(isa<ShuffleVectorInst>(Src) &&
               "Not supported shufflevector usage.");
        auto *SVSrc = cast<ShuffleVectorInst>(Src);
        assert(isa<PoisonValue>(SVSrc->getOperand(1)) &&
               "Not supported shufflevector usage.");
        SmallVector<int> ThisMask(calculateShufflevectorMask(E->Scalars));
        SmallVector<int> NewMask(ThisMask.size());
        transform(ThisMask, NewMask.begin(),
                  [&SVSrc](int Mask) { return SVSrc->getShuffleMask()[Mask]; });
        V = Builder.CreateShuffleVector(SVSrc->getOperand(0), NewMask);
        propagateIRFlags(V, E->Scalars, VL0);
      } else {
        assert(E->isAltShuffle() &&
               ((Instruction::isBinaryOp(E->getOpcode()) &&
                 Instruction::isBinaryOp(E->getAltOpcode())) ||
                (Instruction::isCast(E->getOpcode()) &&
                 Instruction::isCast(E->getAltOpcode())) ||
                (isa<CmpInst>(VL0) && isa<CmpInst>(E->getAltOp()))) &&
               "Invalid Shuffle Vector Operand");

        Value *LHS = nullptr, *RHS = nullptr;
        if (Instruction::isBinaryOp(E->getOpcode()) || isa<CmpInst>(VL0)) {
          setInsertPointAfterBundle(E);
          LHS = vectorizeOperand(E, 0, PostponedPHIs);
          if (E->VectorizedValue) {
            LLVM_DEBUG(dbgs() << "SLP: Diamond merged for " << *VL0 << ".\n");
            return E->VectorizedValue;
          }
          RHS = vectorizeOperand(E, 1, PostponedPHIs);
        } else {
          setInsertPointAfterBundle(E);
          LHS = vectorizeOperand(E, 0, PostponedPHIs);
        }
        if (E->VectorizedValue) {
          LLVM_DEBUG(dbgs() << "SLP: Diamond merged for " << *VL0 << ".\n");
          return E->VectorizedValue;
        }
        if (LHS && RHS &&
            ((Instruction::isBinaryOp(E->getOpcode()) &&
              (LHS->getType() != VecTy || RHS->getType() != VecTy)) ||
             (isa<CmpInst>(VL0) && LHS->getType() != RHS->getType()))) {
          assert((It != MinBWs.end() ||
                  getOperandEntry(E, 0)->State == TreeEntry::NeedToGather ||
                  getOperandEntry(E, 1)->State == TreeEntry::NeedToGather ||
                  MinBWs.contains(getOperandEntry(E, 0)) ||
                  MinBWs.contains(getOperandEntry(E, 1))) &&
                 "Expected item in MinBWs.");
          Type *CastTy = VecTy;
          if (isa<CmpInst>(VL0) && LHS->getType() != RHS->getType()) {
            if (cast<VectorType>(LHS->getType())
                    ->getElementType()
                    ->getIntegerBitWidth() < cast<VectorType>(RHS->getType())
                                                 ->getElementType()
                                                 ->getIntegerBitWidth())
              CastTy = RHS->getType();
            else
              CastTy = LHS->getType();
          }
          if (LHS->getType() != CastTy)
            LHS = Builder.CreateIntCast(LHS, CastTy, GetOperandSignedness(0));
          if (RHS->getType() != CastTy)
            RHS = Builder.CreateIntCast(RHS, CastTy, GetOperandSignedness(1));
        }

        Value *V0, *V1;
        if (Instruction::isBinaryOp(E->getOpcode())) {
          V0 = Builder.CreateBinOp(
              static_cast<Instruction::BinaryOps>(E->getOpcode()), LHS, RHS);
          V1 = Builder.CreateBinOp(
              static_cast<Instruction::BinaryOps>(E->getAltOpcode()), LHS, RHS);
        } else if (auto *CI0 = dyn_cast<CmpInst>(VL0)) {
          V0 = Builder.CreateCmp(CI0->getPredicate(), LHS, RHS);
          auto *AltCI = cast<CmpInst>(E->getAltOp());
          CmpInst::Predicate AltPred = AltCI->getPredicate();
          V1 = Builder.CreateCmp(AltPred, LHS, RHS);
        } else {
          if (LHS->getType()->isIntOrIntVectorTy() && ScalarTy->isIntegerTy()) {
            unsigned SrcBWSz = DL->getTypeSizeInBits(
                cast<VectorType>(LHS->getType())->getElementType());
            unsigned BWSz = DL->getTypeSizeInBits(ScalarTy);
            if (BWSz <= SrcBWSz) {
              if (BWSz < SrcBWSz)
                LHS = Builder.CreateIntCast(LHS, VecTy, It->second.first);
              assert(LHS->getType() == VecTy &&
                     "Expected same type as operand.");
              if (auto *I = dyn_cast<Instruction>(LHS))
                LHS = propagateMetadata(I, E->Scalars);
              LHS = FinalShuffle(LHS, E);
              E->VectorizedValue = LHS;
              ++NumVectorInstructions;
              return LHS;
            }
          }
          V0 = Builder.CreateCast(
              static_cast<Instruction::CastOps>(E->getOpcode()), LHS, VecTy);
          V1 = Builder.CreateCast(
              static_cast<Instruction::CastOps>(E->getAltOpcode()), LHS, VecTy);
        }
        // Add V0 and V1 to later analysis to try to find and remove matching
        // instruction, if any.
        for (Value *V : {V0, V1}) {
          if (auto *I = dyn_cast<Instruction>(V)) {
            GatherShuffleExtractSeq.insert(I);
            CSEBlocks.insert(I->getParent());
          }
        }

        // Create shuffle to take alternate operations from the vector.
        // Also, gather up main and alt scalar ops to propagate IR flags to
        // each vector operation.
        ValueList OpScalars, AltScalars;
        SmallVector<int> Mask;
        E->buildAltOpShuffleMask(
            [E, this](Instruction *I) {
              assert(E->isOpcodeOrAlt(I) && "Unexpected main/alternate opcode");
              return isAlternateInstruction(I, E->getMainOp(), E->getAltOp(),
                                            *TLI);
            },
            Mask, &OpScalars, &AltScalars);

        propagateIRFlags(V0, OpScalars, E->getMainOp(), It == MinBWs.end());
        propagateIRFlags(V1, AltScalars, E->getAltOp(), It == MinBWs.end());
        auto DropNuwFlag = [&](Value *Vec, unsigned Opcode) {
          // Drop nuw flags for abs(sub(commutative), true).
          if (auto *I = dyn_cast<Instruction>(Vec);
              I && Opcode == Instruction::Sub && !MinBWs.contains(E) &&
              any_of(E->Scalars, [](Value *V) {
                auto *IV = cast<Instruction>(V);
                return IV->getOpcode() == Instruction::Sub &&
                       isCommutative(cast<Instruction>(IV));
              }))
            I->setHasNoUnsignedWrap(/*b=*/false);
        };
        DropNuwFlag(V0, E->getOpcode());
        DropNuwFlag(V1, E->getAltOpcode());

        if (auto *VecTy = dyn_cast<FixedVectorType>(ScalarTy)) {
          assert(SLPReVec && "FixedVectorType is not expected.");
          transformScalarShuffleIndiciesToVector(VecTy->getNumElements(), Mask);
        }
        V = Builder.CreateShuffleVector(V0, V1, Mask);
      }
      if (auto *I = dyn_cast<Instruction>(V)) {
        V = propagateMetadata(I, E->Scalars);
        GatherShuffleExtractSeq.insert(I);
        CSEBlocks.insert(I->getParent());
      }

      E->VectorizedValue = V;
      ++NumVectorInstructions;

      return V;
    }
    default:
      llvm_unreachable("unknown inst");
  }
  return nullptr;
}

Value *BoUpSLP::vectorizeTree() {
  ExtraValueToDebugLocsMap ExternallyUsedValues;
  return vectorizeTree(ExternallyUsedValues);
}

Value *
BoUpSLP::vectorizeTree(const ExtraValueToDebugLocsMap &ExternallyUsedValues,
                       Instruction *ReductionRoot) {
  // All blocks must be scheduled before any instructions are inserted.
  for (auto &BSIter : BlocksSchedules) {
    scheduleBlock(BSIter.second.get());
  }
  // Clean Entry-to-LastInstruction table. It can be affected after scheduling,
  // need to rebuild it.
  EntryToLastInstruction.clear();

  if (ReductionRoot)
    Builder.SetInsertPoint(ReductionRoot->getParent(),
                           ReductionRoot->getIterator());
  else
    Builder.SetInsertPoint(&F->getEntryBlock(), F->getEntryBlock().begin());

  // Emit gathered loads first to emit better code for the users of those
  // gathered loads.
  for (const std::unique_ptr<TreeEntry> &TE : VectorizableTree) {
    if (GatheredLoadsEntriesFirst != NoGatheredLoads &&
        TE->Idx >= GatheredLoadsEntriesFirst &&
        (!TE->isGather() || !TE->UserTreeIndices.empty())) {
      assert((!TE->UserTreeIndices.empty() ||
              (TE->getOpcode() == Instruction::Load && !TE->isGather())) &&
             "Expected gathered load node.");
      (void)vectorizeTree(TE.get(), /*PostponedPHIs=*/false);
    }
  }
  // Postpone emission of PHIs operands to avoid cyclic dependencies issues.
  (void)vectorizeTree(VectorizableTree[0].get(), /*PostponedPHIs=*/true);
  for (const std::unique_ptr<TreeEntry> &TE : VectorizableTree)
    if (TE->State == TreeEntry::Vectorize &&
        TE->getOpcode() == Instruction::PHI && !TE->isAltShuffle() &&
        TE->VectorizedValue)
      (void)vectorizeTree(TE.get(), /*PostponedPHIs=*/false);
  // Run through the list of postponed gathers and emit them, replacing the temp
  // emitted allocas with actual vector instructions.
  ArrayRef<const TreeEntry *> PostponedNodes = PostponedGathers.getArrayRef();
  DenseMap<Value *, SmallVector<TreeEntry *>> PostponedValues;
  for (const TreeEntry *E : PostponedNodes) {
    auto *TE = const_cast<TreeEntry *>(E);
    if (auto *VecTE = getTreeEntry(TE->Scalars.front()))
      if (VecTE->isSame(TE->UserTreeIndices.front().UserTE->getOperand(
              TE->UserTreeIndices.front().EdgeIdx)) &&
          VecTE->isSame(TE->Scalars))
        // Found gather node which is absolutely the same as one of the
        // vectorized nodes. It may happen after reordering.
        continue;
    auto *PrevVec = cast<Instruction>(TE->VectorizedValue);
    TE->VectorizedValue = nullptr;
    auto *UserI =
        cast<Instruction>(TE->UserTreeIndices.front().UserTE->VectorizedValue);
    // If user is a PHI node, its vector code have to be inserted right before
    // block terminator. Since the node was delayed, there were some unresolved
    // dependencies at the moment when stab instruction was emitted. In a case
    // when any of these dependencies turn out an operand of another PHI, coming
    // from this same block, position of a stab instruction will become invalid.
    // The is because source vector that supposed to feed this gather node was
    // inserted at the end of the block [after stab instruction]. So we need
    // to adjust insertion point again to the end of block.
    if (isa<PHINode>(UserI)) {
      // Insert before all users.
      Instruction *InsertPt = PrevVec->getParent()->getTerminator();
      for (User *U : PrevVec->users()) {
        if (U == UserI)
          continue;
        auto *UI = dyn_cast<Instruction>(U);
        if (!UI || isa<PHINode>(UI) || UI->getParent() != InsertPt->getParent())
          continue;
        if (UI->comesBefore(InsertPt))
          InsertPt = UI;
      }
      Builder.SetInsertPoint(InsertPt);
    } else {
      Builder.SetInsertPoint(PrevVec);
    }
    Builder.SetCurrentDebugLocation(UserI->getDebugLoc());
    Value *Vec = vectorizeTree(TE, /*PostponedPHIs=*/false);
    if (Vec->getType() != PrevVec->getType()) {
      assert(Vec->getType()->isIntOrIntVectorTy() &&
             PrevVec->getType()->isIntOrIntVectorTy() &&
             "Expected integer vector types only.");
      std::optional<bool> IsSigned;
      for (Value *V : TE->Scalars) {
        if (const TreeEntry *BaseTE = getTreeEntry(V)) {
          auto It = MinBWs.find(BaseTE);
          if (It != MinBWs.end()) {
            IsSigned = IsSigned.value_or(false) || It->second.second;
            if (*IsSigned)
              break;
          }
          for (const TreeEntry *MNTE : MultiNodeScalars.lookup(V)) {
            auto It = MinBWs.find(MNTE);
            if (It != MinBWs.end()) {
              IsSigned = IsSigned.value_or(false) || It->second.second;
              if (*IsSigned)
                break;
            }
          }
          if (IsSigned.value_or(false))
            break;
          // Scan through gather nodes.
          for (const TreeEntry *BVE : ValueToGatherNodes.lookup(V)) {
            auto It = MinBWs.find(BVE);
            if (It != MinBWs.end()) {
              IsSigned = IsSigned.value_or(false) || It->second.second;
              if (*IsSigned)
                break;
            }
          }
          if (IsSigned.value_or(false))
            break;
          if (auto *EE = dyn_cast<ExtractElementInst>(V)) {
            IsSigned =
                IsSigned.value_or(false) ||
                !isKnownNonNegative(EE->getVectorOperand(), SimplifyQuery(*DL));
            continue;
          }
          if (IsSigned.value_or(false))
            break;
        }
      }
      if (IsSigned.value_or(false)) {
        // Final attempt - check user node.
        auto It = MinBWs.find(TE->UserTreeIndices.front().UserTE);
        if (It != MinBWs.end())
          IsSigned = It->second.second;
      }
      assert(IsSigned &&
             "Expected user node or perfect diamond match in MinBWs.");
      Vec = Builder.CreateIntCast(Vec, PrevVec->getType(), *IsSigned);
    }
    PrevVec->replaceAllUsesWith(Vec);
    PostponedValues.try_emplace(Vec).first->second.push_back(TE);
    // Replace the stub vector node, if it was used before for one of the
    // buildvector nodes already.
    auto It = PostponedValues.find(PrevVec);
    if (It != PostponedValues.end()) {
      for (TreeEntry *VTE : It->getSecond())
        VTE->VectorizedValue = Vec;
    }
    eraseInstruction(PrevVec);
  }

  LLVM_DEBUG(dbgs() << "SLP: Extracting " << ExternalUses.size()
                    << " values .\n");

  SmallVector<ShuffledInsertData<Value *>> ShuffledInserts;
  // Maps vector instruction to original insertelement instruction
  DenseMap<Value *, InsertElementInst *> VectorToInsertElement;
  // Maps extract Scalar to the corresponding extractelement instruction in the
  // basic block. Only one extractelement per block should be emitted.
  DenseMap<Value *, DenseMap<BasicBlock *, std::pair<Value *, Value *>>>
      ScalarToEEs;
  SmallDenseSet<Value *, 4> UsedInserts;
  DenseMap<std::pair<Value *, Type *>, Value *> VectorCasts;
  SmallDenseSet<Value *, 4> ScalarsWithNullptrUser;
  SmallDenseSet<ExtractElementInst *, 4> IgnoredExtracts;
  // Extract all of the elements with the external uses.
  for (const auto &ExternalUse : ExternalUses) {
    Value *Scalar = ExternalUse.Scalar;
    llvm::User *User = ExternalUse.User;

    // Skip users that we already RAUW. This happens when one instruction
    // has multiple uses of the same value.
    if (User && !is_contained(Scalar->users(), User))
      continue;
    TreeEntry *E = getTreeEntry(Scalar);
    assert(E && "Invalid scalar");
    assert(!E->isGather() && "Extracting from a gather list");
    // Non-instruction pointers are not deleted, just skip them.
    if (E->getOpcode() == Instruction::GetElementPtr &&
        !isa<GetElementPtrInst>(Scalar))
      continue;

    Value *Vec = E->VectorizedValue;
    assert(Vec && "Can't find vectorizable value");

    Value *Lane = Builder.getInt32(ExternalUse.Lane);
    auto ExtractAndExtendIfNeeded = [&](Value *Vec) {
      if (Scalar->getType() != Vec->getType()) {
        Value *Ex = nullptr;
        Value *ExV = nullptr;
        auto *Inst = dyn_cast<Instruction>(Scalar);
        bool ReplaceInst = Inst && ExternalUsesAsOriginalScalar.contains(Inst);
        auto It = ScalarToEEs.find(Scalar);
        if (It != ScalarToEEs.end()) {
          // No need to emit many extracts, just move the only one in the
          // current block.
          auto EEIt = It->second.find(ReplaceInst ? Inst->getParent()
                                                  : Builder.GetInsertBlock());
          if (EEIt != It->second.end()) {
            Value *PrevV = EEIt->second.first;
            if (auto *I = dyn_cast<Instruction>(PrevV);
                I && !ReplaceInst &&
                Builder.GetInsertPoint() != Builder.GetInsertBlock()->end() &&
                Builder.GetInsertPoint()->comesBefore(I)) {
              I->moveBefore(*Builder.GetInsertPoint()->getParent(),
                            Builder.GetInsertPoint());
              if (auto *CI = dyn_cast<Instruction>(EEIt->second.second))
                CI->moveAfter(I);
            }
            Ex = PrevV;
            ExV = EEIt->second.second ? EEIt->second.second : Ex;
          }
        }
        if (!Ex) {
          // "Reuse" the existing extract to improve final codegen.
          if (ReplaceInst) {
            // Leave the instruction as is, if it cheaper extracts and all
            // operands are scalar.
            if (auto *EE = dyn_cast<ExtractElementInst>(Inst)) {
              IgnoredExtracts.insert(EE);
              Ex = EE;
            } else {
              auto *CloneInst = Inst->clone();
              CloneInst->insertBefore(Inst);
              if (Inst->hasName())
                CloneInst->takeName(Inst);
              Ex = CloneInst;
            }
          } else if (auto *ES = dyn_cast<ExtractElementInst>(Scalar);
                     ES && isa<Instruction>(Vec)) {
            Value *V = ES->getVectorOperand();
            auto *IVec = cast<Instruction>(Vec);
            if (const TreeEntry *ETE = getTreeEntry(V))
              V = ETE->VectorizedValue;
            if (auto *IV = dyn_cast<Instruction>(V);
                !IV || IV == Vec || IV->getParent() != IVec->getParent() ||
                IV->comesBefore(IVec))
              Ex = Builder.CreateExtractElement(V, ES->getIndexOperand());
            else
              Ex = Builder.CreateExtractElement(Vec, Lane);
          } else if (auto *VecTy =
                         dyn_cast<FixedVectorType>(Scalar->getType())) {
            assert(SLPReVec && "FixedVectorType is not expected.");
            unsigned VecTyNumElements = VecTy->getNumElements();
            // When REVEC is enabled, we need to extract a vector.
            // Note: The element size of Scalar may be different from the
            // element size of Vec.
            Ex = Builder.CreateExtractVector(
                FixedVectorType::get(Vec->getType()->getScalarType(),
                                     VecTyNumElements),
                Vec, Builder.getInt64(ExternalUse.Lane * VecTyNumElements));
          } else {
            Ex = Builder.CreateExtractElement(Vec, Lane);
          }
          // If necessary, sign-extend or zero-extend ScalarRoot
          // to the larger type.
          ExV = Ex;
          if (Scalar->getType() != Ex->getType())
            ExV = Builder.CreateIntCast(Ex, Scalar->getType(),
                                        MinBWs.find(E)->second.second);
          auto *I = dyn_cast<Instruction>(Ex);
          ScalarToEEs[Scalar].try_emplace(I ? I->getParent()
                                            : &F->getEntryBlock(),
                                          std::make_pair(Ex, ExV));
        }
        // The then branch of the previous if may produce constants, since 0
        // operand might be a constant.
        if (auto *ExI = dyn_cast<Instruction>(Ex);
            ExI && !isa<PHINode>(ExI) && !mayHaveNonDefUseDependency(*ExI)) {
          GatherShuffleExtractSeq.insert(ExI);
          CSEBlocks.insert(ExI->getParent());
        }
        return ExV;
      }
      assert(isa<FixedVectorType>(Scalar->getType()) &&
             isa<InsertElementInst>(Scalar) &&
             "In-tree scalar of vector type is not insertelement?");
      auto *IE = cast<InsertElementInst>(Scalar);
      VectorToInsertElement.try_emplace(Vec, IE);
      return Vec;
    };
    // If User == nullptr, the Scalar remains as scalar in vectorized
    // instructions or is used as extra arg. Generate ExtractElement instruction
    // and update the record for this scalar in ExternallyUsedValues.
    if (!User) {
      if (!ScalarsWithNullptrUser.insert(Scalar).second)
        continue;
      assert((ExternallyUsedValues.count(Scalar) ||
              Scalar->hasNUsesOrMore(UsesLimit) ||
              ExternalUsesAsOriginalScalar.contains(Scalar) ||
              any_of(Scalar->users(),
                     [&](llvm::User *U) {
                       if (ExternalUsesAsOriginalScalar.contains(U))
                         return true;
                       TreeEntry *UseEntry = getTreeEntry(U);
                       return UseEntry &&
                              (UseEntry->State == TreeEntry::Vectorize ||
                               UseEntry->State ==
                                   TreeEntry::StridedVectorize) &&
                              (E->State == TreeEntry::Vectorize ||
                               E->State == TreeEntry::StridedVectorize) &&
                              doesInTreeUserNeedToExtract(
                                  Scalar, getRootEntryInstruction(*UseEntry),
                                  TLI);
                     })) &&
             "Scalar with nullptr User must be registered in "
             "ExternallyUsedValues map or remain as scalar in vectorized "
             "instructions");
      if (auto *VecI = dyn_cast<Instruction>(Vec)) {
        if (auto *PHI = dyn_cast<PHINode>(VecI)) {
          if (PHI->getParent()->isLandingPad())
            Builder.SetInsertPoint(
                PHI->getParent(),
                std::next(
                    PHI->getParent()->getLandingPadInst()->getIterator()));
          else
            Builder.SetInsertPoint(PHI->getParent(),
                                   PHI->getParent()->getFirstNonPHIIt());
        } else {
          Builder.SetInsertPoint(VecI->getParent(),
                                 std::next(VecI->getIterator()));
        }
      } else {
        Builder.SetInsertPoint(&F->getEntryBlock(), F->getEntryBlock().begin());
      }
      Value *NewInst = ExtractAndExtendIfNeeded(Vec);
      // Required to update internally referenced instructions.
      if (Scalar != NewInst) {
        assert((!isa<ExtractElementInst>(Scalar) ||
                !IgnoredExtracts.contains(cast<ExtractElementInst>(Scalar))) &&
               "Extractelements should not be replaced.");
        Scalar->replaceAllUsesWith(NewInst);
      }
      continue;
    }

    if (auto *VU = dyn_cast<InsertElementInst>(User);
        VU && VU->getOperand(1) == Scalar) {
      // Skip if the scalar is another vector op or Vec is not an instruction.
      if (!Scalar->getType()->isVectorTy() && isa<Instruction>(Vec)) {
        if (auto *FTy = dyn_cast<FixedVectorType>(User->getType())) {
          if (!UsedInserts.insert(VU).second)
            continue;
          // Need to use original vector, if the root is truncated.
          auto BWIt = MinBWs.find(E);
          if (BWIt != MinBWs.end() && Vec->getType() != VU->getType()) {
            auto *ScalarTy = FTy->getElementType();
            auto Key = std::make_pair(Vec, ScalarTy);
            auto VecIt = VectorCasts.find(Key);
            if (VecIt == VectorCasts.end()) {
              IRBuilderBase::InsertPointGuard Guard(Builder);
              if (auto *IVec = dyn_cast<PHINode>(Vec)) {
                if (IVec->getParent()->isLandingPad())
                  Builder.SetInsertPoint(IVec->getParent(),
                                         std::next(IVec->getParent()
                                                       ->getLandingPadInst()
                                                       ->getIterator()));
                else
                  Builder.SetInsertPoint(
                      IVec->getParent()->getFirstNonPHIOrDbgOrLifetime());
              } else if (auto *IVec = dyn_cast<Instruction>(Vec)) {
                Builder.SetInsertPoint(IVec->getNextNonDebugInstruction());
              }
              Vec = Builder.CreateIntCast(
                  Vec,
                  getWidenedType(
                      ScalarTy,
                      cast<FixedVectorType>(Vec->getType())->getNumElements()),
                  BWIt->second.second);
              VectorCasts.try_emplace(Key, Vec);
            } else {
              Vec = VecIt->second;
            }
          }

          std::optional<unsigned> InsertIdx = getElementIndex(VU);
          if (InsertIdx) {
            auto *It = find_if(
                ShuffledInserts, [VU](const ShuffledInsertData<Value *> &Data) {
                  // Checks if 2 insertelements are from the same buildvector.
                  InsertElementInst *VecInsert = Data.InsertElements.front();
                  return areTwoInsertFromSameBuildVector(
                      VU, VecInsert,
                      [](InsertElementInst *II) { return II->getOperand(0); });
                });
            unsigned Idx = *InsertIdx;
            if (It == ShuffledInserts.end()) {
              (void)ShuffledInserts.emplace_back();
              It = std::next(ShuffledInserts.begin(),
                             ShuffledInserts.size() - 1);
            }
            SmallVectorImpl<int> &Mask = It->ValueMasks[Vec];
            if (Mask.empty())
              Mask.assign(FTy->getNumElements(), PoisonMaskElem);
            Mask[Idx] = ExternalUse.Lane;
            It->InsertElements.push_back(cast<InsertElementInst>(User));
            continue;
          }
        }
      }
    }

    // Generate extracts for out-of-tree users.
    // Find the insertion point for the extractelement lane.
    if (auto *VecI = dyn_cast<Instruction>(Vec)) {
      if (PHINode *PH = dyn_cast<PHINode>(User)) {
        for (unsigned I : seq<unsigned>(0, PH->getNumIncomingValues())) {
          if (PH->getIncomingValue(I) == Scalar) {
            Instruction *IncomingTerminator =
                PH->getIncomingBlock(I)->getTerminator();
            if (isa<CatchSwitchInst>(IncomingTerminator)) {
              Builder.SetInsertPoint(VecI->getParent(),
                                     std::next(VecI->getIterator()));
            } else {
              Builder.SetInsertPoint(PH->getIncomingBlock(I)->getTerminator());
            }
            Value *NewInst = ExtractAndExtendIfNeeded(Vec);
            PH->setOperand(I, NewInst);
          }
        }
      } else {
        Builder.SetInsertPoint(cast<Instruction>(User));
        Value *NewInst = ExtractAndExtendIfNeeded(Vec);
        User->replaceUsesOfWith(Scalar, NewInst);
      }
    } else {
      Builder.SetInsertPoint(&F->getEntryBlock(), F->getEntryBlock().begin());
      Value *NewInst = ExtractAndExtendIfNeeded(Vec);
      User->replaceUsesOfWith(Scalar, NewInst);
    }

    LLVM_DEBUG(dbgs() << "SLP: Replaced:" << *User << ".\n");
  }

  auto CreateShuffle = [&](Value *V1, Value *V2, ArrayRef<int> Mask) {
    SmallVector<int> CombinedMask1(Mask.size(), PoisonMaskElem);
    SmallVector<int> CombinedMask2(Mask.size(), PoisonMaskElem);
    int VF = cast<FixedVectorType>(V1->getType())->getNumElements();
    for (int I = 0, E = Mask.size(); I < E; ++I) {
      if (Mask[I] < VF)
        CombinedMask1[I] = Mask[I];
      else
        CombinedMask2[I] = Mask[I] - VF;
    }
    ShuffleInstructionBuilder ShuffleBuilder(
        cast<VectorType>(V1->getType())->getElementType(), Builder, *this);
    ShuffleBuilder.add(V1, CombinedMask1);
    if (V2)
      ShuffleBuilder.add(V2, CombinedMask2);
    return ShuffleBuilder.finalize({}, {});
  };

  auto &&ResizeToVF = [&CreateShuffle](Value *Vec, ArrayRef<int> Mask,
                                       bool ForSingleMask) {
    unsigned VF = Mask.size();
    unsigned VecVF = cast<FixedVectorType>(Vec->getType())->getNumElements();
    if (VF != VecVF) {
      if (any_of(Mask, [VF](int Idx) { return Idx >= static_cast<int>(VF); })) {
        Vec = CreateShuffle(Vec, nullptr, Mask);
        return std::make_pair(Vec, true);
      }
      if (!ForSingleMask) {
        SmallVector<int> ResizeMask(VF, PoisonMaskElem);
        for (unsigned I = 0; I < VF; ++I) {
          if (Mask[I] != PoisonMaskElem)
            ResizeMask[Mask[I]] = Mask[I];
        }
        Vec = CreateShuffle(Vec, nullptr, ResizeMask);
      }
    }

    return std::make_pair(Vec, false);
  };
  // Perform shuffling of the vectorize tree entries for better handling of
  // external extracts.
  for (int I = 0, E = ShuffledInserts.size(); I < E; ++I) {
    // Find the first and the last instruction in the list of insertelements.
    sort(ShuffledInserts[I].InsertElements, isFirstInsertElement);
    InsertElementInst *FirstInsert = ShuffledInserts[I].InsertElements.front();
    InsertElementInst *LastInsert = ShuffledInserts[I].InsertElements.back();
    Builder.SetInsertPoint(LastInsert);
    auto Vector = ShuffledInserts[I].ValueMasks.takeVector();
    Value *NewInst = performExtractsShuffleAction<Value>(
        MutableArrayRef(Vector.data(), Vector.size()),
        FirstInsert->getOperand(0),
        [](Value *Vec) {
          return cast<VectorType>(Vec->getType())
              ->getElementCount()
              .getKnownMinValue();
        },
        ResizeToVF,
        [FirstInsert, &CreateShuffle](ArrayRef<int> Mask,
                                      ArrayRef<Value *> Vals) {
          assert((Vals.size() == 1 || Vals.size() == 2) &&
                 "Expected exactly 1 or 2 input values.");
          if (Vals.size() == 1) {
            // Do not create shuffle if the mask is a simple identity
            // non-resizing mask.
            if (Mask.size() != cast<FixedVectorType>(Vals.front()->getType())
                                   ->getNumElements() ||
                !ShuffleVectorInst::isIdentityMask(Mask, Mask.size()))
              return CreateShuffle(Vals.front(), nullptr, Mask);
            return Vals.front();
          }
          return CreateShuffle(Vals.front() ? Vals.front()
                                            : FirstInsert->getOperand(0),
                               Vals.back(), Mask);
        });
    auto It = ShuffledInserts[I].InsertElements.rbegin();
    // Rebuild buildvector chain.
    InsertElementInst *II = nullptr;
    if (It != ShuffledInserts[I].InsertElements.rend())
      II = *It;
    SmallVector<Instruction *> Inserts;
    while (It != ShuffledInserts[I].InsertElements.rend()) {
      assert(II && "Must be an insertelement instruction.");
      if (*It == II)
        ++It;
      else
        Inserts.push_back(cast<Instruction>(II));
      II = dyn_cast<InsertElementInst>(II->getOperand(0));
    }
    for (Instruction *II : reverse(Inserts)) {
      II->replaceUsesOfWith(II->getOperand(0), NewInst);
      if (auto *NewI = dyn_cast<Instruction>(NewInst))
        if (II->getParent() == NewI->getParent() && II->comesBefore(NewI))
          II->moveAfter(NewI);
      NewInst = II;
    }
    LastInsert->replaceAllUsesWith(NewInst);
    for (InsertElementInst *IE : reverse(ShuffledInserts[I].InsertElements)) {
      IE->replaceUsesOfWith(IE->getOperand(0),
                            PoisonValue::get(IE->getOperand(0)->getType()));
      IE->replaceUsesOfWith(IE->getOperand(1),
                            PoisonValue::get(IE->getOperand(1)->getType()));
      eraseInstruction(IE);
    }
    CSEBlocks.insert(LastInsert->getParent());
  }

  SmallVector<Instruction *> RemovedInsts;
  // For each vectorized value:
  for (auto &TEPtr : VectorizableTree) {
    TreeEntry *Entry = TEPtr.get();

    // No need to handle users of gathered values.
    if (Entry->isGather())
      continue;

    assert(Entry->VectorizedValue && "Can't find vectorizable value");

    // For each lane:
    for (int Lane = 0, LE = Entry->Scalars.size(); Lane != LE; ++Lane) {
      Value *Scalar = Entry->Scalars[Lane];

      if (Entry->getOpcode() == Instruction::GetElementPtr &&
          !isa<GetElementPtrInst>(Scalar))
        continue;
      if (auto *EE = dyn_cast<ExtractElementInst>(Scalar);
          EE && IgnoredExtracts.contains(EE))
        continue;
#ifndef NDEBUG
      Type *Ty = Scalar->getType();
      if (!Ty->isVoidTy()) {
        for (User *U : Scalar->users()) {
          LLVM_DEBUG(dbgs() << "SLP: \tvalidating user:" << *U << ".\n");

          // It is legal to delete users in the ignorelist.
          assert((getTreeEntry(U) ||
                  (UserIgnoreList && UserIgnoreList->contains(U)) ||
                  (isa_and_nonnull<Instruction>(U) &&
                   isDeleted(cast<Instruction>(U)))) &&
                 "Deleting out-of-tree value");
        }
      }
#endif
      LLVM_DEBUG(dbgs() << "SLP: \tErasing scalar:" << *Scalar << ".\n");
      auto *I = cast<Instruction>(Scalar);
      RemovedInsts.push_back(I);
    }
  }

  // Merge the DIAssignIDs from the about-to-be-deleted instructions into the
  // new vector instruction.
  if (auto *V = dyn_cast<Instruction>(VectorizableTree[0]->VectorizedValue))
    V->mergeDIAssignID(RemovedInsts);

  // Clear up reduction references, if any.
  if (UserIgnoreList) {
    for (Instruction *I : RemovedInsts) {
      const TreeEntry *IE = getTreeEntry(I);
      if (IE->Idx != 0 &&
          !(VectorizableTree.front()->isGather() && isa<LoadInst>(I) &&
            !IE->UserTreeIndices.empty() &&
            any_of(IE->UserTreeIndices,
                   [&](const EdgeInfo &EI) {
                     return EI.UserTE == VectorizableTree.front().get() &&
                            EI.EdgeIdx == UINT_MAX;
                   })) &&
          !(GatheredLoadsEntriesFirst != NoGatheredLoads &&
            IE->Idx >= GatheredLoadsEntriesFirst &&
            VectorizableTree.front()->isGather() &&
            is_contained(VectorizableTree.front()->Scalars, I)))
        continue;
      SmallVector<SelectInst *> LogicalOpSelects;
      I->replaceUsesWithIf(PoisonValue::get(I->getType()), [&](Use &U) {
        // Do not replace condition of the logical op in form select <cond>.
        bool IsPoisoningLogicalOp = isa<SelectInst>(U.getUser()) &&
                                    (match(U.getUser(), m_LogicalAnd()) ||
                                     match(U.getUser(), m_LogicalOr())) &&
                                    U.getOperandNo() == 0;
        if (IsPoisoningLogicalOp) {
          LogicalOpSelects.push_back(cast<SelectInst>(U.getUser()));
          return false;
        }
        return UserIgnoreList->contains(U.getUser());
      });
      // Replace conditions of the poisoning logical ops with the non-poison
      // constant value.
      for (SelectInst *SI : LogicalOpSelects)
        SI->setCondition(Constant::getNullValue(SI->getCondition()->getType()));
    }
  }
  // Retain to-be-deleted instructions for some debug-info bookkeeping and alias
  // cache correctness.
  // NOTE: removeInstructionAndOperands only marks the instruction for deletion
  // - instructions are not deleted until later.
  removeInstructionsAndOperands(ArrayRef(RemovedInsts));

  Builder.ClearInsertionPoint();
  InstrElementSize.clear();

  const TreeEntry &RootTE = *VectorizableTree.front();
  Value *Vec = RootTE.VectorizedValue;
  if (auto It = MinBWs.find(&RootTE); ReductionBitWidth != 0 &&
                                      It != MinBWs.end() &&
                                      ReductionBitWidth != It->second.first) {
    IRBuilder<>::InsertPointGuard Guard(Builder);
    Builder.SetInsertPoint(ReductionRoot->getParent(),
                           ReductionRoot->getIterator());
    Vec = Builder.CreateIntCast(
        Vec,
        VectorType::get(Builder.getIntNTy(ReductionBitWidth),
                        cast<VectorType>(Vec->getType())->getElementCount()),
        It->second.second);
  }
  return Vec;
}

void BoUpSLP::optimizeGatherSequence() {
  LLVM_DEBUG(dbgs() << "SLP: Optimizing " << GatherShuffleExtractSeq.size()
                    << " gather sequences instructions.\n");
  // LICM InsertElementInst sequences.
  for (Instruction *I : GatherShuffleExtractSeq) {
    if (isDeleted(I))
      continue;

    // Check if this block is inside a loop.
    Loop *L = LI->getLoopFor(I->getParent());
    if (!L)
      continue;

    // Check if it has a preheader.
    BasicBlock *PreHeader = L->getLoopPreheader();
    if (!PreHeader)
      continue;

    // If the vector or the element that we insert into it are
    // instructions that are defined in this basic block then we can't
    // hoist this instruction.
    if (any_of(I->operands(), [L](Value *V) {
          auto *OpI = dyn_cast<Instruction>(V);
          return OpI && L->contains(OpI);
        }))
      continue;

    // We can hoist this instruction. Move it to the pre-header.
    I->moveBefore(PreHeader->getTerminator());
    CSEBlocks.insert(PreHeader);
  }

  // Make a list of all reachable blocks in our CSE queue.
  SmallVector<const DomTreeNode *, 8> CSEWorkList;
  CSEWorkList.reserve(CSEBlocks.size());
  for (BasicBlock *BB : CSEBlocks)
    if (DomTreeNode *N = DT->getNode(BB)) {
      assert(DT->isReachableFromEntry(N));
      CSEWorkList.push_back(N);
    }

  // Sort blocks by domination. This ensures we visit a block after all blocks
  // dominating it are visited.
  llvm::sort(CSEWorkList, [](const DomTreeNode *A, const DomTreeNode *B) {
    assert((A == B) == (A->getDFSNumIn() == B->getDFSNumIn()) &&
           "Different nodes should have different DFS numbers");
    return A->getDFSNumIn() < B->getDFSNumIn();
  });

  // Less defined shuffles can be replaced by the more defined copies.
  // Between two shuffles one is less defined if it has the same vector operands
  // and its mask indeces are the same as in the first one or undefs. E.g.
  // shuffle %0, poison, <0, 0, 0, undef> is less defined than shuffle %0,
  // poison, <0, 0, 0, 0>.
  auto &&IsIdenticalOrLessDefined = [this](Instruction *I1, Instruction *I2,
                                           SmallVectorImpl<int> &NewMask) {
    if (I1->getType() != I2->getType())
      return false;
    auto *SI1 = dyn_cast<ShuffleVectorInst>(I1);
    auto *SI2 = dyn_cast<ShuffleVectorInst>(I2);
    if (!SI1 || !SI2)
      return I1->isIdenticalTo(I2);
    if (SI1->isIdenticalTo(SI2))
      return true;
    for (int I = 0, E = SI1->getNumOperands(); I < E; ++I)
      if (SI1->getOperand(I) != SI2->getOperand(I))
        return false;
    // Check if the second instruction is more defined than the first one.
    NewMask.assign(SI2->getShuffleMask().begin(), SI2->getShuffleMask().end());
    ArrayRef<int> SM1 = SI1->getShuffleMask();
    // Count trailing undefs in the mask to check the final number of used
    // registers.
    unsigned LastUndefsCnt = 0;
    for (int I = 0, E = NewMask.size(); I < E; ++I) {
      if (SM1[I] == PoisonMaskElem)
        ++LastUndefsCnt;
      else
        LastUndefsCnt = 0;
      if (NewMask[I] != PoisonMaskElem && SM1[I] != PoisonMaskElem &&
          NewMask[I] != SM1[I])
        return false;
      if (NewMask[I] == PoisonMaskElem)
        NewMask[I] = SM1[I];
    }
    // Check if the last undefs actually change the final number of used vector
    // registers.
    return SM1.size() - LastUndefsCnt > 1 &&
           TTI->getNumberOfParts(SI1->getType()) ==
               TTI->getNumberOfParts(
                   getWidenedType(SI1->getType()->getElementType(),
                                  SM1.size() - LastUndefsCnt));
  };
  // Perform O(N^2) search over the gather/shuffle sequences and merge identical
  // instructions. TODO: We can further optimize this scan if we split the
  // instructions into different buckets based on the insert lane.
  SmallVector<Instruction *, 16> Visited;
  for (auto I = CSEWorkList.begin(), E = CSEWorkList.end(); I != E; ++I) {
    assert(*I &&
           (I == CSEWorkList.begin() || !DT->dominates(*I, *std::prev(I))) &&
           "Worklist not sorted properly!");
    BasicBlock *BB = (*I)->getBlock();
    // For all instructions in blocks containing gather sequences:
    for (Instruction &In : llvm::make_early_inc_range(*BB)) {
      if (isDeleted(&In))
        continue;
      if (!isa<InsertElementInst, ExtractElementInst, ShuffleVectorInst>(&In) &&
          !GatherShuffleExtractSeq.contains(&In))
        continue;

      // Check if we can replace this instruction with any of the
      // visited instructions.
      bool Replaced = false;
      for (Instruction *&V : Visited) {
        SmallVector<int> NewMask;
        if (IsIdenticalOrLessDefined(&In, V, NewMask) &&
            DT->dominates(V->getParent(), In.getParent())) {
          In.replaceAllUsesWith(V);
          eraseInstruction(&In);
          if (auto *SI = dyn_cast<ShuffleVectorInst>(V))
            if (!NewMask.empty())
              SI->setShuffleMask(NewMask);
          Replaced = true;
          break;
        }
        if (isa<ShuffleVectorInst>(In) && isa<ShuffleVectorInst>(V) &&
            GatherShuffleExtractSeq.contains(V) &&
            IsIdenticalOrLessDefined(V, &In, NewMask) &&
            DT->dominates(In.getParent(), V->getParent())) {
          In.moveAfter(V);
          V->replaceAllUsesWith(&In);
          eraseInstruction(V);
          if (auto *SI = dyn_cast<ShuffleVectorInst>(&In))
            if (!NewMask.empty())
              SI->setShuffleMask(NewMask);
          V = &In;
          Replaced = true;
          break;
        }
      }
      if (!Replaced) {
        assert(!is_contained(Visited, &In));
        Visited.push_back(&In);
      }
    }
  }
  CSEBlocks.clear();
  GatherShuffleExtractSeq.clear();
}

BoUpSLP::ScheduleData *
BoUpSLP::BlockScheduling::buildBundle(ArrayRef<Value *> VL) {
  ScheduleData *Bundle = nullptr;
  ScheduleData *PrevInBundle = nullptr;
  for (Value *V : VL) {
    if (doesNotNeedToBeScheduled(V))
      continue;
    ScheduleData *BundleMember = getScheduleData(V);
    assert(BundleMember &&
           "no ScheduleData for bundle member "
           "(maybe not in same basic block)");
    assert(BundleMember->isSchedulingEntity() &&
           "bundle member already part of other bundle");
    if (PrevInBundle) {
      PrevInBundle->NextInBundle = BundleMember;
    } else {
      Bundle = BundleMember;
    }

    // Group the instructions to a bundle.
    BundleMember->FirstInBundle = Bundle;
    PrevInBundle = BundleMember;
  }
  assert(Bundle && "Failed to find schedule bundle");
  return Bundle;
}

// Groups the instructions to a bundle (which is then a single scheduling entity)
// and schedules instructions until the bundle gets ready.
std::optional<BoUpSLP::ScheduleData *>
BoUpSLP::BlockScheduling::tryScheduleBundle(ArrayRef<Value *> VL, BoUpSLP *SLP,
                                            const InstructionsState &S) {
  // No need to schedule PHIs, insertelement, extractelement and extractvalue
  // instructions.
  if (isa<PHINode>(S.OpValue) || isVectorLikeInstWithConstOps(S.OpValue) ||
      doesNotNeedToSchedule(VL))
    return nullptr;

  // Initialize the instruction bundle.
  Instruction *OldScheduleEnd = ScheduleEnd;
  LLVM_DEBUG(dbgs() << "SLP:  bundle: " << *S.OpValue << "\n");

  auto TryScheduleBundleImpl = [this, OldScheduleEnd, SLP](bool ReSchedule,
                                                         ScheduleData *Bundle) {
    // The scheduling region got new instructions at the lower end (or it is a
    // new region for the first bundle). This makes it necessary to
    // recalculate all dependencies.
    // It is seldom that this needs to be done a second time after adding the
    // initial bundle to the region.
    if (ScheduleEnd != OldScheduleEnd) {
      for (auto *I = ScheduleStart; I != ScheduleEnd; I = I->getNextNode())
        if (ScheduleData *SD = getScheduleData(I))
          SD->clearDependencies();
      ReSchedule = true;
    }
    if (Bundle) {
      LLVM_DEBUG(dbgs() << "SLP: try schedule bundle " << *Bundle
                        << " in block " << BB->getName() << "\n");
      calculateDependencies(Bundle, /*InsertInReadyList=*/true, SLP);
    }

    if (ReSchedule) {
      resetSchedule();
      initialFillReadyList(ReadyInsts);
    }

    // Now try to schedule the new bundle or (if no bundle) just calculate
    // dependencies. As soon as the bundle is "ready" it means that there are no
    // cyclic dependencies and we can schedule it. Note that's important that we
    // don't "schedule" the bundle yet (see cancelScheduling).
    while (((!Bundle && ReSchedule) || (Bundle && !Bundle->isReady())) &&
           !ReadyInsts.empty()) {
      ScheduleData *Picked = ReadyInsts.pop_back_val();
      assert(Picked->isSchedulingEntity() && Picked->isReady() &&
             "must be ready to schedule");
      schedule(Picked, ReadyInsts);
    }
  };

  // Make sure that the scheduling region contains all
  // instructions of the bundle.
  for (Value *V : VL) {
    if (doesNotNeedToBeScheduled(V))
      continue;
    if (!extendSchedulingRegion(V, S)) {
      // If the scheduling region got new instructions at the lower end (or it
      // is a new region for the first bundle). This makes it necessary to
      // recalculate all dependencies.
      // Otherwise the compiler may crash trying to incorrectly calculate
      // dependencies and emit instruction in the wrong order at the actual
      // scheduling.
      TryScheduleBundleImpl(/*ReSchedule=*/false, nullptr);
      return std::nullopt;
    }
  }

  bool ReSchedule = false;
  for (Value *V : VL) {
    if (doesNotNeedToBeScheduled(V))
      continue;
    ScheduleData *BundleMember = getScheduleData(V);
    assert(BundleMember &&
           "no ScheduleData for bundle member (maybe not in same basic block)");

    // Make sure we don't leave the pieces of the bundle in the ready list when
    // whole bundle might not be ready.
    ReadyInsts.remove(BundleMember);

    if (!BundleMember->IsScheduled)
      continue;
    // A bundle member was scheduled as single instruction before and now
    // needs to be scheduled as part of the bundle. We just get rid of the
    // existing schedule.
    LLVM_DEBUG(dbgs() << "SLP:  reset schedule because " << *BundleMember
                      << " was already scheduled\n");
    ReSchedule = true;
  }

  auto *Bundle = buildBundle(VL);
  TryScheduleBundleImpl(ReSchedule, Bundle);
  if (!Bundle->isReady()) {
    cancelScheduling(VL, S.OpValue);
    return std::nullopt;
  }
  return Bundle;
}

void BoUpSLP::BlockScheduling::cancelScheduling(ArrayRef<Value *> VL,
                                                Value *OpValue) {
  if (isa<PHINode>(OpValue) || isVectorLikeInstWithConstOps(OpValue) ||
      doesNotNeedToSchedule(VL))
    return;

  if (doesNotNeedToBeScheduled(OpValue))
    OpValue = *find_if_not(VL, doesNotNeedToBeScheduled);
  ScheduleData *Bundle = getScheduleData(OpValue);
  LLVM_DEBUG(dbgs() << "SLP:  cancel scheduling of " << *Bundle << "\n");
  assert(!Bundle->IsScheduled &&
         "Can't cancel bundle which is already scheduled");
  assert(Bundle->isSchedulingEntity() &&
         (Bundle->isPartOfBundle() || needToScheduleSingleInstruction(VL)) &&
         "tried to unbundle something which is not a bundle");

  // Remove the bundle from the ready list.
  if (Bundle->isReady())
    ReadyInsts.remove(Bundle);

  // Un-bundle: make single instructions out of the bundle.
  ScheduleData *BundleMember = Bundle;
  while (BundleMember) {
    assert(BundleMember->FirstInBundle == Bundle && "corrupt bundle links");
    BundleMember->FirstInBundle = BundleMember;
    ScheduleData *Next = BundleMember->NextInBundle;
    BundleMember->NextInBundle = nullptr;
    BundleMember->TE = nullptr;
    if (BundleMember->unscheduledDepsInBundle() == 0) {
      ReadyInsts.insert(BundleMember);
    }
    BundleMember = Next;
  }
}

BoUpSLP::ScheduleData *BoUpSLP::BlockScheduling::allocateScheduleDataChunks() {
  // Allocate a new ScheduleData for the instruction.
  if (ChunkPos >= ChunkSize) {
    ScheduleDataChunks.push_back(std::make_unique<ScheduleData[]>(ChunkSize));
    ChunkPos = 0;
  }
  return &(ScheduleDataChunks.back()[ChunkPos++]);
}

bool BoUpSLP::BlockScheduling::extendSchedulingRegion(
    Value *V, const InstructionsState &S) {
  Instruction *I = dyn_cast<Instruction>(V);
  assert(I && "bundle member must be an instruction");
  assert(!isa<PHINode>(I) && !isVectorLikeInstWithConstOps(I) &&
         !doesNotNeedToBeScheduled(I) &&
         "phi nodes/insertelements/extractelements/extractvalues don't need to "
         "be scheduled");
  if (getScheduleData(I))
    return true;
  if (!ScheduleStart) {
    // It's the first instruction in the new region.
    initScheduleData(I, I->getNextNode(), nullptr, nullptr);
    ScheduleStart = I;
    ScheduleEnd = I->getNextNode();
    assert(ScheduleEnd && "tried to vectorize a terminator?");
    LLVM_DEBUG(dbgs() << "SLP:  initialize schedule region to " << *I << "\n");
    return true;
  }
  // Search up and down at the same time, because we don't know if the new
  // instruction is above or below the existing scheduling region.
  // Ignore debug info (and other "AssumeLike" intrinsics) so that's not counted
  // against the budget. Otherwise debug info could affect codegen.
  BasicBlock::reverse_iterator UpIter =
      ++ScheduleStart->getIterator().getReverse();
  BasicBlock::reverse_iterator UpperEnd = BB->rend();
  BasicBlock::iterator DownIter = ScheduleEnd->getIterator();
  BasicBlock::iterator LowerEnd = BB->end();
  auto IsAssumeLikeIntr = [](const Instruction &I) {
    if (auto *II = dyn_cast<IntrinsicInst>(&I))
      return II->isAssumeLikeIntrinsic();
    return false;
  };
  UpIter = std::find_if_not(UpIter, UpperEnd, IsAssumeLikeIntr);
  DownIter = std::find_if_not(DownIter, LowerEnd, IsAssumeLikeIntr);
  while (UpIter != UpperEnd && DownIter != LowerEnd && &*UpIter != I &&
         &*DownIter != I) {
    if (++ScheduleRegionSize > ScheduleRegionSizeLimit) {
      LLVM_DEBUG(dbgs() << "SLP:  exceeded schedule region size limit\n");
      return false;
    }

    ++UpIter;
    ++DownIter;

    UpIter = std::find_if_not(UpIter, UpperEnd, IsAssumeLikeIntr);
    DownIter = std::find_if_not(DownIter, LowerEnd, IsAssumeLikeIntr);
  }
  if (DownIter == LowerEnd || (UpIter != UpperEnd && &*UpIter == I)) {
    assert(I->getParent() == ScheduleStart->getParent() &&
           "Instruction is in wrong basic block.");
    initScheduleData(I, ScheduleStart, nullptr, FirstLoadStoreInRegion);
    ScheduleStart = I;
    LLVM_DEBUG(dbgs() << "SLP:  extend schedule region start to " << *I
                      << "\n");
    return true;
  }
  assert((UpIter == UpperEnd || (DownIter != LowerEnd && &*DownIter == I)) &&
         "Expected to reach top of the basic block or instruction down the "
         "lower end.");
  assert(I->getParent() == ScheduleEnd->getParent() &&
         "Instruction is in wrong basic block.");
  initScheduleData(ScheduleEnd, I->getNextNode(), LastLoadStoreInRegion,
                   nullptr);
  ScheduleEnd = I->getNextNode();
  assert(ScheduleEnd && "tried to vectorize a terminator?");
  LLVM_DEBUG(dbgs() << "SLP:  extend schedule region end to " << *I << "\n");
  return true;
}

void BoUpSLP::BlockScheduling::initScheduleData(Instruction *FromI,
                                                Instruction *ToI,
                                                ScheduleData *PrevLoadStore,
                                                ScheduleData *NextLoadStore) {
  ScheduleData *CurrentLoadStore = PrevLoadStore;
  for (Instruction *I = FromI; I != ToI; I = I->getNextNode()) {
    // No need to allocate data for non-schedulable instructions.
    if (doesNotNeedToBeScheduled(I))
      continue;
    ScheduleData *SD = ScheduleDataMap.lookup(I);
    if (!SD) {
      SD = allocateScheduleDataChunks();
      ScheduleDataMap[I] = SD;
    }
    assert(!isInSchedulingRegion(SD) &&
           "new ScheduleData already in scheduling region");
    SD->init(SchedulingRegionID, I);

    if (I->mayReadOrWriteMemory() &&
        (!isa<IntrinsicInst>(I) ||
         (cast<IntrinsicInst>(I)->getIntrinsicID() != Intrinsic::sideeffect &&
          cast<IntrinsicInst>(I)->getIntrinsicID() !=
              Intrinsic::pseudoprobe))) {
      // Update the linked list of memory accessing instructions.
      if (CurrentLoadStore) {
        CurrentLoadStore->NextLoadStore = SD;
      } else {
        FirstLoadStoreInRegion = SD;
      }
      CurrentLoadStore = SD;
    }

    if (match(I, m_Intrinsic<Intrinsic::stacksave>()) ||
        match(I, m_Intrinsic<Intrinsic::stackrestore>()))
      RegionHasStackSave = true;
  }
  if (NextLoadStore) {
    if (CurrentLoadStore)
      CurrentLoadStore->NextLoadStore = NextLoadStore;
  } else {
    LastLoadStoreInRegion = CurrentLoadStore;
  }
}

void BoUpSLP::BlockScheduling::calculateDependencies(ScheduleData *SD,
                                                     bool InsertInReadyList,
                                                     BoUpSLP *SLP) {
  assert(SD->isSchedulingEntity());

  SmallVector<ScheduleData *, 10> WorkList;
  WorkList.push_back(SD);

  while (!WorkList.empty()) {
    ScheduleData *SD = WorkList.pop_back_val();
    for (ScheduleData *BundleMember = SD; BundleMember;
         BundleMember = BundleMember->NextInBundle) {
      assert(isInSchedulingRegion(BundleMember));
      if (BundleMember->hasValidDependencies())
        continue;

      LLVM_DEBUG(dbgs() << "SLP:       update deps of " << *BundleMember
                 << "\n");
      BundleMember->Dependencies = 0;
      BundleMember->resetUnscheduledDeps();

      // Handle def-use chain dependencies.
      for (User *U : BundleMember->Inst->users()) {
        if (ScheduleData *UseSD = getScheduleData(cast<Instruction>(U))) {
          BundleMember->Dependencies++;
          ScheduleData *DestBundle = UseSD->FirstInBundle;
          if (!DestBundle->IsScheduled)
            BundleMember->incrementUnscheduledDeps(1);
          if (!DestBundle->hasValidDependencies())
            WorkList.push_back(DestBundle);
        }
      }

      auto MakeControlDependent = [&](Instruction *I) {
        auto *DepDest = getScheduleData(I);
        assert(DepDest && "must be in schedule window");
        DepDest->ControlDependencies.push_back(BundleMember);
        BundleMember->Dependencies++;
        ScheduleData *DestBundle = DepDest->FirstInBundle;
        if (!DestBundle->IsScheduled)
          BundleMember->incrementUnscheduledDeps(1);
        if (!DestBundle->hasValidDependencies())
          WorkList.push_back(DestBundle);
      };

      // Any instruction which isn't safe to speculate at the beginning of the
      // block is control dependend on any early exit or non-willreturn call
      // which proceeds it.
      if (!isGuaranteedToTransferExecutionToSuccessor(BundleMember->Inst)) {
        for (Instruction *I = BundleMember->Inst->getNextNode();
             I != ScheduleEnd; I = I->getNextNode()) {
          if (isSafeToSpeculativelyExecute(I, &*BB->begin(), SLP->AC))
            continue;

          // Add the dependency
          MakeControlDependent(I);

          if (!isGuaranteedToTransferExecutionToSuccessor(I))
            // Everything past here must be control dependent on I.
            break;
        }
      }

      if (RegionHasStackSave) {
        // If we have an inalloc alloca instruction, it needs to be scheduled
        // after any preceeding stacksave.  We also need to prevent any alloca
        // from reordering above a preceeding stackrestore.
        if (match(BundleMember->Inst, m_Intrinsic<Intrinsic::stacksave>()) ||
            match(BundleMember->Inst, m_Intrinsic<Intrinsic::stackrestore>())) {
          for (Instruction *I = BundleMember->Inst->getNextNode();
               I != ScheduleEnd; I = I->getNextNode()) {
            if (match(I, m_Intrinsic<Intrinsic::stacksave>()) ||
                match(I, m_Intrinsic<Intrinsic::stackrestore>()))
              // Any allocas past here must be control dependent on I, and I
              // must be memory dependend on BundleMember->Inst.
              break;

            if (!isa<AllocaInst>(I))
              continue;

            // Add the dependency
            MakeControlDependent(I);
          }
        }

        // In addition to the cases handle just above, we need to prevent
        // allocas and loads/stores from moving below a stacksave or a
        // stackrestore. Avoiding moving allocas below stackrestore is currently
        // thought to be conservatism. Moving loads/stores below a stackrestore
        // can lead to incorrect code.
        if (isa<AllocaInst>(BundleMember->Inst) ||
            BundleMember->Inst->mayReadOrWriteMemory()) {
          for (Instruction *I = BundleMember->Inst->getNextNode();
               I != ScheduleEnd; I = I->getNextNode()) {
            if (!match(I, m_Intrinsic<Intrinsic::stacksave>()) &&
                !match(I, m_Intrinsic<Intrinsic::stackrestore>()))
              continue;

            // Add the dependency
            MakeControlDependent(I);
            break;
          }
        }
      }

      // Handle the memory dependencies (if any).
      ScheduleData *DepDest = BundleMember->NextLoadStore;
      if (!DepDest)
        continue;
      Instruction *SrcInst = BundleMember->Inst;
      assert(SrcInst->mayReadOrWriteMemory() &&
             "NextLoadStore list for non memory effecting bundle?");
      MemoryLocation SrcLoc = getLocation(SrcInst);
      bool SrcMayWrite = BundleMember->Inst->mayWriteToMemory();
      unsigned NumAliased = 0;
      unsigned DistToSrc = 1;

      for (; DepDest; DepDest = DepDest->NextLoadStore) {
        assert(isInSchedulingRegion(DepDest));

        // We have two limits to reduce the complexity:
        // 1) AliasedCheckLimit: It's a small limit to reduce calls to
        //    SLP->isAliased (which is the expensive part in this loop).
        // 2) MaxMemDepDistance: It's for very large blocks and it aborts
        //    the whole loop (even if the loop is fast, it's quadratic).
        //    It's important for the loop break condition (see below) to
        //    check this limit even between two read-only instructions.
        if (DistToSrc >= MaxMemDepDistance ||
            ((SrcMayWrite || DepDest->Inst->mayWriteToMemory()) &&
             (NumAliased >= AliasedCheckLimit ||
              SLP->isAliased(SrcLoc, SrcInst, DepDest->Inst)))) {

          // We increment the counter only if the locations are aliased
          // (instead of counting all alias checks). This gives a better
          // balance between reduced runtime and accurate dependencies.
          NumAliased++;

          DepDest->MemoryDependencies.push_back(BundleMember);
          BundleMember->Dependencies++;
          ScheduleData *DestBundle = DepDest->FirstInBundle;
          if (!DestBundle->IsScheduled) {
            BundleMember->incrementUnscheduledDeps(1);
          }
          if (!DestBundle->hasValidDependencies()) {
            WorkList.push_back(DestBundle);
          }
        }

        // Example, explaining the loop break condition: Let's assume our
        // starting instruction is i0 and MaxMemDepDistance = 3.
        //
        //                      +--------v--v--v
        //             i0,i1,i2,i3,i4,i5,i6,i7,i8
        //             +--------^--^--^
        //
        // MaxMemDepDistance let us stop alias-checking at i3 and we add
        // dependencies from i0 to i3,i4,.. (even if they are not aliased).
        // Previously we already added dependencies from i3 to i6,i7,i8
        // (because of MaxMemDepDistance). As we added a dependency from
        // i0 to i3, we have transitive dependencies from i0 to i6,i7,i8
        // and we can abort this loop at i6.
        if (DistToSrc >= 2 * MaxMemDepDistance)
          break;
        DistToSrc++;
      }
    }
    if (InsertInReadyList && SD->isReady()) {
      ReadyInsts.insert(SD);
      LLVM_DEBUG(dbgs() << "SLP:     gets ready on update: " << *SD->Inst
                        << "\n");
    }
  }
}

void BoUpSLP::BlockScheduling::resetSchedule() {
  assert(ScheduleStart &&
         "tried to reset schedule on block which has not been scheduled");
  for (Instruction *I = ScheduleStart; I != ScheduleEnd; I = I->getNextNode()) {
    if (ScheduleData *SD = getScheduleData(I)) {
      assert(isInSchedulingRegion(SD) &&
             "ScheduleData not in scheduling region");
      SD->IsScheduled = false;
      SD->resetUnscheduledDeps();
    }
  }
  ReadyInsts.clear();
}

void BoUpSLP::scheduleBlock(BlockScheduling *BS) {
  if (!BS->ScheduleStart)
    return;

  LLVM_DEBUG(dbgs() << "SLP: schedule block " << BS->BB->getName() << "\n");

  // A key point - if we got here, pre-scheduling was able to find a valid
  // scheduling of the sub-graph of the scheduling window which consists
  // of all vector bundles and their transitive users.  As such, we do not
  // need to reschedule anything *outside of* that subgraph.

  BS->resetSchedule();

  // For the real scheduling we use a more sophisticated ready-list: it is
  // sorted by the original instruction location. This lets the final schedule
  // be as  close as possible to the original instruction order.
  // WARNING: If changing this order causes a correctness issue, that means
  // there is some missing dependence edge in the schedule data graph.
  struct ScheduleDataCompare {
    bool operator()(ScheduleData *SD1, ScheduleData *SD2) const {
      return SD2->SchedulingPriority < SD1->SchedulingPriority;
    }
  };
  std::set<ScheduleData *, ScheduleDataCompare> ReadyInsts;

  // Ensure that all dependency data is updated (for nodes in the sub-graph)
  // and fill the ready-list with initial instructions.
  int Idx = 0;
  for (auto *I = BS->ScheduleStart; I != BS->ScheduleEnd;
       I = I->getNextNode()) {
    if (ScheduleData *SD = BS->getScheduleData(I)) {
      TreeEntry *SDTE = getTreeEntry(SD->Inst);
      (void)SDTE;
      assert((isVectorLikeInstWithConstOps(SD->Inst) ||
              SD->isPartOfBundle() ==
                  (SDTE && !doesNotNeedToSchedule(SDTE->Scalars))) &&
             "scheduler and vectorizer bundle mismatch");
      SD->FirstInBundle->SchedulingPriority = Idx++;

      if (SD->isSchedulingEntity() && SD->isPartOfBundle())
        BS->calculateDependencies(SD, false, this);
    }
  }
  BS->initialFillReadyList(ReadyInsts);

  Instruction *LastScheduledInst = BS->ScheduleEnd;

  // Do the "real" scheduling.
  while (!ReadyInsts.empty()) {
    ScheduleData *Picked = *ReadyInsts.begin();
    ReadyInsts.erase(ReadyInsts.begin());

    // Move the scheduled instruction(s) to their dedicated places, if not
    // there yet.
    for (ScheduleData *BundleMember = Picked; BundleMember;
         BundleMember = BundleMember->NextInBundle) {
      Instruction *PickedInst = BundleMember->Inst;
      if (PickedInst->getNextNonDebugInstruction() != LastScheduledInst)
        PickedInst->moveAfter(LastScheduledInst->getPrevNode());
      LastScheduledInst = PickedInst;
    }

    BS->schedule(Picked, ReadyInsts);
  }

  // Check that we didn't break any of our invariants.
#ifdef EXPENSIVE_CHECKS
  BS->verify();
#endif

#if !defined(NDEBUG) || defined(EXPENSIVE_CHECKS)
  // Check that all schedulable entities got scheduled
  for (auto *I = BS->ScheduleStart; I != BS->ScheduleEnd; I = I->getNextNode()) {
    ScheduleData *SD = BS->getScheduleData(I);
    if (SD && SD->isSchedulingEntity() && SD->hasValidDependencies())
      assert(SD->IsScheduled && "must be scheduled at this point");
  }
#endif

  // Avoid duplicate scheduling of the block.
  BS->ScheduleStart = nullptr;
}

unsigned BoUpSLP::getVectorElementSize(Value *V) {
  // If V is a store, just return the width of the stored value (or value
  // truncated just before storing) without traversing the expression tree.
  // This is the common case.
  if (auto *Store = dyn_cast<StoreInst>(V))
    return DL->getTypeSizeInBits(Store->getValueOperand()->getType());

  if (auto *IEI = dyn_cast<InsertElementInst>(V))
    return getVectorElementSize(IEI->getOperand(1));

  auto E = InstrElementSize.find(V);
  if (E != InstrElementSize.end())
    return E->second;

  // If V is not a store, we can traverse the expression tree to find loads
  // that feed it. The type of the loaded value may indicate a more suitable
  // width than V's type. We want to base the vector element size on the width
  // of memory operations where possible.
  SmallVector<std::tuple<Instruction *, BasicBlock *, unsigned>> Worklist;
  SmallPtrSet<Instruction *, 16> Visited;
  if (auto *I = dyn_cast<Instruction>(V)) {
    Worklist.emplace_back(I, I->getParent(), 0);
    Visited.insert(I);
  }

  // Traverse the expression tree in bottom-up order looking for loads. If we
  // encounter an instruction we don't yet handle, we give up.
  auto Width = 0u;
  Value *FirstNonBool = nullptr;
  while (!Worklist.empty()) {
    auto [I, Parent, Level] = Worklist.pop_back_val();

    // We should only be looking at scalar instructions here. If the current
    // instruction has a vector type, skip.
    auto *Ty = I->getType();
    if (isa<VectorType>(Ty))
      continue;
    if (Ty != Builder.getInt1Ty() && !FirstNonBool)
      FirstNonBool = I;
    if (Level > RecursionMaxDepth)
      continue;

    // If the current instruction is a load, update MaxWidth to reflect the
    // width of the loaded value.
    if (isa<LoadInst, ExtractElementInst, ExtractValueInst>(I))
      Width = std::max<unsigned>(Width, DL->getTypeSizeInBits(Ty));

    // Otherwise, we need to visit the operands of the instruction. We only
    // handle the interesting cases from buildTree here. If an operand is an
    // instruction we haven't yet visited and from the same basic block as the
    // user or the use is a PHI node, we add it to the worklist.
    else if (isa<PHINode, CastInst, GetElementPtrInst, CmpInst, SelectInst,
                 BinaryOperator, UnaryOperator>(I)) {
      for (Use &U : I->operands()) {
        if (auto *J = dyn_cast<Instruction>(U.get()))
          if (Visited.insert(J).second &&
              (isa<PHINode>(I) || J->getParent() == Parent)) {
            Worklist.emplace_back(J, J->getParent(), Level + 1);
            continue;
          }
        if (!FirstNonBool && U.get()->getType() != Builder.getInt1Ty())
          FirstNonBool = U.get();
      }
    } else {
      break;
    }
  }

  // If we didn't encounter a memory access in the expression tree, or if we
  // gave up for some reason, just return the width of V. Otherwise, return the
  // maximum width we found.
  if (!Width) {
    if (V->getType() == Builder.getInt1Ty() && FirstNonBool)
      V = FirstNonBool;
    Width = DL->getTypeSizeInBits(V->getType());
  }

  for (Instruction *I : Visited)
    InstrElementSize[I] = Width;

  return Width;
}

bool BoUpSLP::collectValuesToDemote(
    const TreeEntry &E, bool IsProfitableToDemoteRoot, unsigned &BitWidth,
    SmallVectorImpl<unsigned> &ToDemote, DenseSet<const TreeEntry *> &Visited,
    unsigned &MaxDepthLevel, bool &IsProfitableToDemote,
    bool IsTruncRoot) const {
  // We can always demote constants.
  if (all_of(E.Scalars, IsaPred<Constant>))
    return true;

  unsigned OrigBitWidth =
      DL->getTypeSizeInBits(E.Scalars.front()->getType()->getScalarType());
  if (OrigBitWidth == BitWidth) {
    MaxDepthLevel = 1;
    return true;
  }

  // If the value is not a vectorized instruction in the expression and not used
  // by the insertelement instruction and not used in multiple vector nodes, it
  // cannot be demoted.
  bool IsSignedNode = any_of(E.Scalars, [&](Value *R) {
    return !isKnownNonNegative(R, SimplifyQuery(*DL));
  });
  auto IsPotentiallyTruncated = [&](Value *V, unsigned &BitWidth) -> bool {
    if (MultiNodeScalars.contains(V))
      return false;
    // For lat shuffle of sext/zext with many uses need to check the extra bit
    // for unsigned values, otherwise may have incorrect casting for reused
    // scalars.
    bool IsSignedVal = !isKnownNonNegative(V, SimplifyQuery(*DL));
    if ((!IsSignedNode || IsSignedVal) && OrigBitWidth > BitWidth) {
      APInt Mask = APInt::getBitsSetFrom(OrigBitWidth, BitWidth);
      if (MaskedValueIsZero(V, Mask, SimplifyQuery(*DL)))
        return true;
    }
    unsigned NumSignBits = ComputeNumSignBits(V, *DL, 0, AC, nullptr, DT);
    unsigned BitWidth1 = OrigBitWidth - NumSignBits;
    if (IsSignedNode)
      ++BitWidth1;
    if (auto *I = dyn_cast<Instruction>(V)) {
      APInt Mask = DB->getDemandedBits(I);
      unsigned BitWidth2 =
          std::max<unsigned>(1, Mask.getBitWidth() - Mask.countl_zero());
      while (!IsSignedNode && BitWidth2 < OrigBitWidth) {
        APInt Mask = APInt::getBitsSetFrom(OrigBitWidth, BitWidth2 - 1);
        if (MaskedValueIsZero(V, Mask, SimplifyQuery(*DL)))
          break;
        BitWidth2 *= 2;
      }
      BitWidth1 = std::min(BitWidth1, BitWidth2);
    }
    BitWidth = std::max(BitWidth, BitWidth1);
    return BitWidth > 0 && OrigBitWidth >= (BitWidth * 2);
  };
  using namespace std::placeholders;
  auto FinalAnalysis = [&]() {
    if (!IsProfitableToDemote)
      return false;
    bool Res = all_of(
        E.Scalars, std::bind(IsPotentiallyTruncated, _1, std::ref(BitWidth)));
    // Demote gathers.
    if (Res && E.isGather()) {
      // Check possible extractelement instructions bases and final vector
      // length.
      SmallPtrSet<Value *, 4> UniqueBases;
      for (Value *V : E.Scalars) {
        auto *EE = dyn_cast<ExtractElementInst>(V);
        if (!EE)
          continue;
        UniqueBases.insert(EE->getVectorOperand());
      }
      const unsigned VF = E.Scalars.size();
      Type *OrigScalarTy = E.Scalars.front()->getType();
      if (UniqueBases.size() <= 2 ||
          TTI->getNumberOfParts(getWidenedType(OrigScalarTy, VF)) ==
              TTI->getNumberOfParts(getWidenedType(
                  IntegerType::get(OrigScalarTy->getContext(), BitWidth), VF)))
        ToDemote.push_back(E.Idx);
    }
    return Res;
  };
  if (E.isGather() || !Visited.insert(&E).second ||
      any_of(E.Scalars, [&](Value *V) {
        return all_of(V->users(), [&](User *U) {
          return isa<InsertElementInst>(U) && !getTreeEntry(U);
        });
      }))
    return FinalAnalysis();

  if (any_of(E.Scalars, [&](Value *V) {
        return !all_of(V->users(), [=](User *U) {
          return getTreeEntry(U) ||
                 (E.Idx == 0 && UserIgnoreList &&
                  UserIgnoreList->contains(U)) ||
                 (!isa<CmpInst>(U) && U->getType()->isSized() &&
                  !U->getType()->isScalableTy() &&
                  DL->getTypeSizeInBits(U->getType()) <= BitWidth);
        }) && !IsPotentiallyTruncated(V, BitWidth);
      }))
    return false;

  auto ProcessOperands = [&](ArrayRef<const TreeEntry *> Operands,
                             bool &NeedToExit) {
    NeedToExit = false;
    unsigned InitLevel = MaxDepthLevel;
    for (const TreeEntry *Op : Operands) {
      unsigned Level = InitLevel;
      if (!collectValuesToDemote(*Op, IsProfitableToDemoteRoot, BitWidth,
                                 ToDemote, Visited, Level, IsProfitableToDemote,
                                 IsTruncRoot)) {
        if (!IsProfitableToDemote)
          return false;
        NeedToExit = true;
        if (!FinalAnalysis())
          return false;
        continue;
      }
      MaxDepthLevel = std::max(MaxDepthLevel, Level);
    }
    return true;
  };
  auto AttemptCheckBitwidth =
      [&](function_ref<bool(unsigned, unsigned)> Checker, bool &NeedToExit) {
        // Try all bitwidth < OrigBitWidth.
        NeedToExit = false;
        unsigned BestFailBitwidth = 0;
        for (; BitWidth < OrigBitWidth; BitWidth *= 2) {
          if (Checker(BitWidth, OrigBitWidth))
            return true;
          if (BestFailBitwidth == 0 && FinalAnalysis())
            BestFailBitwidth = BitWidth;
        }
        if (BitWidth >= OrigBitWidth) {
          if (BestFailBitwidth == 0) {
            BitWidth = OrigBitWidth;
            return false;
          }
          MaxDepthLevel = 1;
          BitWidth = BestFailBitwidth;
          NeedToExit = true;
          return true;
        }
        return false;
      };
  auto TryProcessInstruction =
      [&](unsigned &BitWidth, ArrayRef<const TreeEntry *> Operands = {},
          function_ref<bool(unsigned, unsigned)> Checker = {}) {
        if (Operands.empty()) {
          if (!IsTruncRoot)
            MaxDepthLevel = 1;
          (void)for_each(E.Scalars, std::bind(IsPotentiallyTruncated, _1,
                                              std::ref(BitWidth)));
        } else {
          // Several vectorized uses? Check if we can truncate it, otherwise -
          // exit.
          if (E.UserTreeIndices.size() > 1 &&
              !all_of(E.Scalars, std::bind(IsPotentiallyTruncated, _1,
                                           std::ref(BitWidth))))
            return false;
          bool NeedToExit = false;
          if (Checker && !AttemptCheckBitwidth(Checker, NeedToExit))
            return false;
          if (NeedToExit)
            return true;
          if (!ProcessOperands(Operands, NeedToExit))
            return false;
          if (NeedToExit)
            return true;
        }

        ++MaxDepthLevel;
        // Record the entry that we can demote.
        ToDemote.push_back(E.Idx);
        return IsProfitableToDemote;
      };
  switch (E.getOpcode()) {

  // We can always demote truncations and extensions. Since truncations can
  // seed additional demotion, we save the truncated value.
  case Instruction::Trunc:
    if (IsProfitableToDemoteRoot)
      IsProfitableToDemote = true;
    return TryProcessInstruction(BitWidth);
  case Instruction::ZExt:
  case Instruction::SExt:
    IsProfitableToDemote = true;
    return TryProcessInstruction(BitWidth);

  // We can demote certain binary operations if we can demote both of their
  // operands.
  case Instruction::Add:
  case Instruction::Sub:
  case Instruction::Mul:
  case Instruction::And:
  case Instruction::Or:
  case Instruction::Xor: {
    return TryProcessInstruction(
        BitWidth, {getOperandEntry(&E, 0), getOperandEntry(&E, 1)});
  }
  case Instruction::Shl: {
    // If we are truncating the result of this SHL, and if it's a shift of an
    // inrange amount, we can always perform a SHL in a smaller type.
    auto ShlChecker = [&](unsigned BitWidth, unsigned) {
      return all_of(E.Scalars, [&](Value *V) {
        auto *I = cast<Instruction>(V);
        KnownBits AmtKnownBits = computeKnownBits(I->getOperand(1), *DL);
        return AmtKnownBits.getMaxValue().ult(BitWidth);
      });
    };
    return TryProcessInstruction(
        BitWidth, {getOperandEntry(&E, 0), getOperandEntry(&E, 1)}, ShlChecker);
  }
  case Instruction::LShr: {
    // If this is a truncate of a logical shr, we can truncate it to a smaller
    // lshr iff we know that the bits we would otherwise be shifting in are
    // already zeros.
    auto LShrChecker = [&](unsigned BitWidth, unsigned OrigBitWidth) {
      return all_of(E.Scalars, [&](Value *V) {
        auto *I = cast<Instruction>(V);
        KnownBits AmtKnownBits = computeKnownBits(I->getOperand(1), *DL);
        APInt ShiftedBits = APInt::getBitsSetFrom(OrigBitWidth, BitWidth);
        return AmtKnownBits.getMaxValue().ult(BitWidth) &&
               MaskedValueIsZero(I->getOperand(0), ShiftedBits,
                                 SimplifyQuery(*DL));
      });
    };
    return TryProcessInstruction(
        BitWidth, {getOperandEntry(&E, 0), getOperandEntry(&E, 1)},
        LShrChecker);
  }
  case Instruction::AShr: {
    // If this is a truncate of an arithmetic shr, we can truncate it to a
    // smaller ashr iff we know that all the bits from the sign bit of the
    // original type and the sign bit of the truncate type are similar.
    auto AShrChecker = [&](unsigned BitWidth, unsigned OrigBitWidth) {
      return all_of(E.Scalars, [&](Value *V) {
        auto *I = cast<Instruction>(V);
        KnownBits AmtKnownBits = computeKnownBits(I->getOperand(1), *DL);
        unsigned ShiftedBits = OrigBitWidth - BitWidth;
        return AmtKnownBits.getMaxValue().ult(BitWidth) &&
               ShiftedBits < ComputeNumSignBits(I->getOperand(0), *DL, 0, AC,
                                                nullptr, DT);
      });
    };
    return TryProcessInstruction(
        BitWidth, {getOperandEntry(&E, 0), getOperandEntry(&E, 1)},
        AShrChecker);
  }
  case Instruction::UDiv:
  case Instruction::URem: {
    // UDiv and URem can be truncated if all the truncated bits are zero.
    auto Checker = [&](unsigned BitWidth, unsigned OrigBitWidth) {
      assert(BitWidth <= OrigBitWidth && "Unexpected bitwidths!");
      return all_of(E.Scalars, [&](Value *V) {
        auto *I = cast<Instruction>(V);
        APInt Mask = APInt::getBitsSetFrom(OrigBitWidth, BitWidth);
        return MaskedValueIsZero(I->getOperand(0), Mask, SimplifyQuery(*DL)) &&
               MaskedValueIsZero(I->getOperand(1), Mask, SimplifyQuery(*DL));
      });
    };
    return TryProcessInstruction(
        BitWidth, {getOperandEntry(&E, 0), getOperandEntry(&E, 1)}, Checker);
  }

  // We can demote selects if we can demote their true and false values.
  case Instruction::Select: {
    return TryProcessInstruction(
        BitWidth, {getOperandEntry(&E, 1), getOperandEntry(&E, 2)});
  }

  // We can demote phis if we can demote all their incoming operands. Note that
  // we don't need to worry about cycles since we ensure single use above.
  case Instruction::PHI: {
    const unsigned NumOps = E.getNumOperands();
    SmallVector<const TreeEntry *> Ops(NumOps);
    transform(seq<unsigned>(0, NumOps), Ops.begin(),
              std::bind(&BoUpSLP::getOperandEntry, this, &E, _1));

    return TryProcessInstruction(BitWidth, Ops);
  }

  case Instruction::Call: {
    auto *IC = dyn_cast<IntrinsicInst>(E.getMainOp());
    if (!IC)
      break;
    Intrinsic::ID ID = getVectorIntrinsicIDForCall(IC, TLI);
    if (ID != Intrinsic::abs && ID != Intrinsic::smin &&
        ID != Intrinsic::smax && ID != Intrinsic::umin && ID != Intrinsic::umax)
      break;
    SmallVector<const TreeEntry *, 2> Operands(1, getOperandEntry(&E, 0));
    function_ref<bool(unsigned, unsigned)> CallChecker;
    auto CompChecker = [&](unsigned BitWidth, unsigned OrigBitWidth) {
      assert(BitWidth <= OrigBitWidth && "Unexpected bitwidths!");
      return all_of(E.Scalars, [&](Value *V) {
        auto *I = cast<Instruction>(V);
        if (ID == Intrinsic::umin || ID == Intrinsic::umax) {
          APInt Mask = APInt::getBitsSetFrom(OrigBitWidth, BitWidth);
          return MaskedValueIsZero(I->getOperand(0), Mask,
                                   SimplifyQuery(*DL)) &&
                 MaskedValueIsZero(I->getOperand(1), Mask, SimplifyQuery(*DL));
        }
        assert((ID == Intrinsic::smin || ID == Intrinsic::smax) &&
               "Expected min/max intrinsics only.");
        unsigned SignBits = OrigBitWidth - BitWidth;
        APInt Mask = APInt::getBitsSetFrom(OrigBitWidth, BitWidth - 1);
        unsigned Op0SignBits = ComputeNumSignBits(I->getOperand(0), *DL, 0, AC,
                                              nullptr, DT);
        unsigned Op1SignBits = ComputeNumSignBits(I->getOperand(1), *DL, 0, AC,
                                              nullptr, DT);
        return SignBits <= Op0SignBits &&
               ((SignBits != Op0SignBits &&
                 !isKnownNonNegative(I->getOperand(0), SimplifyQuery(*DL))) ||
                MaskedValueIsZero(I->getOperand(0), Mask,
                                  SimplifyQuery(*DL))) &&
               SignBits <= Op1SignBits &&
               ((SignBits != Op1SignBits &&
                 !isKnownNonNegative(I->getOperand(1), SimplifyQuery(*DL))) ||
                MaskedValueIsZero(I->getOperand(1), Mask, SimplifyQuery(*DL)));
      });
    };
    if (ID != Intrinsic::abs) {
      Operands.push_back(getOperandEntry(&E, 1));
      CallChecker = CompChecker;
    }
    InstructionCost BestCost =
        std::numeric_limits<InstructionCost::CostType>::max();
    unsigned BestBitWidth = BitWidth;
    unsigned VF = E.Scalars.size();
    // Choose the best bitwidth based on cost estimations.
    auto Checker = [&](unsigned BitWidth, unsigned) {
      unsigned MinBW = PowerOf2Ceil(BitWidth);
      SmallVector<Type *> ArgTys = buildIntrinsicArgTypes(IC, ID, VF, MinBW);
      auto VecCallCosts = getVectorCallCosts(
          IC, getWidenedType(IntegerType::get(IC->getContext(), MinBW), VF),
          TTI, TLI, ArgTys);
      InstructionCost Cost = std::min(VecCallCosts.first, VecCallCosts.second);
      if (Cost < BestCost) {
        BestCost = Cost;
        BestBitWidth = BitWidth;
      }
      return false;
    };
    [[maybe_unused]] bool NeedToExit;
    (void)AttemptCheckBitwidth(Checker, NeedToExit);
    BitWidth = BestBitWidth;
    return TryProcessInstruction(BitWidth, Operands, CallChecker);
  }

  // Otherwise, conservatively give up.
  default:
    break;
  }
  MaxDepthLevel = 1;
  return FinalAnalysis();
}

static RecurKind getRdxKind(Value *V);

void BoUpSLP::computeMinimumValueSizes() {
  // We only attempt to truncate integer expressions.
  bool IsStoreOrInsertElt =
      VectorizableTree.front()->getOpcode() == Instruction::Store ||
      VectorizableTree.front()->getOpcode() == Instruction::InsertElement;
  if ((IsStoreOrInsertElt || UserIgnoreList) &&
      ExtraBitWidthNodes.size() <= 1 &&
      (!CastMaxMinBWSizes || CastMaxMinBWSizes->second == 0 ||
       CastMaxMinBWSizes->first / CastMaxMinBWSizes->second <= 2))
    return;

  unsigned NodeIdx = 0;
  if (IsStoreOrInsertElt && !VectorizableTree.front()->isGather())
    NodeIdx = 1;

  // Ensure the roots of the vectorizable tree don't form a cycle.
  if (VectorizableTree[NodeIdx]->isGather() ||
      (NodeIdx == 0 && !VectorizableTree[NodeIdx]->UserTreeIndices.empty()) ||
      (NodeIdx != 0 && any_of(VectorizableTree[NodeIdx]->UserTreeIndices,
                              [NodeIdx](const EdgeInfo &EI) {
                                return EI.UserTE->Idx >
                                       static_cast<int>(NodeIdx);
                              })))
    return;

  // The first value node for store/insertelement is sext/zext/trunc? Skip it,
  // resize to the final type.
  bool IsTruncRoot = false;
  bool IsProfitableToDemoteRoot = !IsStoreOrInsertElt;
  SmallVector<unsigned> RootDemotes;
  if (NodeIdx != 0 &&
      VectorizableTree[NodeIdx]->State == TreeEntry::Vectorize &&
      VectorizableTree[NodeIdx]->getOpcode() == Instruction::Trunc) {
    assert(IsStoreOrInsertElt && "Expected store/insertelement seeded graph.");
    IsTruncRoot = true;
    RootDemotes.push_back(NodeIdx);
    IsProfitableToDemoteRoot = true;
    ++NodeIdx;
  }

  // Analyzed the reduction already and not profitable - exit.
  if (AnalyzedMinBWVals.contains(VectorizableTree[NodeIdx]->Scalars.front()))
    return;

  SmallVector<unsigned> ToDemote;
  auto ComputeMaxBitWidth = [&](const TreeEntry &E, bool IsTopRoot,
                                bool IsProfitableToDemoteRoot, unsigned Opcode,
                                unsigned Limit, bool IsTruncRoot,
                                bool IsSignedCmp) -> unsigned {
    ToDemote.clear();
    // Check if the root is trunc and the next node is gather/buildvector, then
    // keep trunc in scalars, which is free in most cases.
    if (E.isGather() && IsTruncRoot && E.UserTreeIndices.size() == 1 &&
        E.Idx > (IsStoreOrInsertElt ? 2 : 1) &&
        all_of(E.Scalars, [&](Value *V) {
          return V->hasOneUse() || isa<Constant>(V) ||
                 (!V->hasNUsesOrMore(UsesLimit) &&
                  none_of(V->users(), [&](User *U) {
                    const TreeEntry *TE = getTreeEntry(U);
                    const TreeEntry *UserTE = E.UserTreeIndices.back().UserTE;
                    if (TE == UserTE || !TE)
                      return false;
                    if (!isa<CastInst, BinaryOperator, FreezeInst, PHINode,
                             SelectInst>(U) ||
                        !isa<CastInst, BinaryOperator, FreezeInst, PHINode,
                             SelectInst>(UserTE->getMainOp()))
                      return true;
                    unsigned UserTESz = DL->getTypeSizeInBits(
                        UserTE->Scalars.front()->getType());
                    auto It = MinBWs.find(TE);
                    if (It != MinBWs.end() && It->second.first > UserTESz)
                      return true;
                    return DL->getTypeSizeInBits(U->getType()) > UserTESz;
                  }));
        })) {
      ToDemote.push_back(E.Idx);
      const TreeEntry *UserTE = E.UserTreeIndices.back().UserTE;
      auto It = MinBWs.find(UserTE);
      if (It != MinBWs.end())
        return It->second.first;
      unsigned MaxBitWidth =
          DL->getTypeSizeInBits(UserTE->Scalars.front()->getType());
      MaxBitWidth = bit_ceil(MaxBitWidth);
      if (MaxBitWidth < 8 && MaxBitWidth > 1)
        MaxBitWidth = 8;
      return MaxBitWidth;
    }

    unsigned VF = E.getVectorFactor();
    Type *ScalarTy = E.Scalars.front()->getType();
    unsigned ScalarTyNumElements = getNumElements(ScalarTy);
    auto *TreeRootIT = dyn_cast<IntegerType>(ScalarTy->getScalarType());
    if (!TreeRootIT || !Opcode)
      return 0u;

    if (any_of(E.Scalars,
               [&](Value *V) { return AnalyzedMinBWVals.contains(V); }))
      return 0u;

    unsigned NumParts = TTI->getNumberOfParts(
        getWidenedType(TreeRootIT, VF * ScalarTyNumElements));

    // The maximum bit width required to represent all the values that can be
    // demoted without loss of precision. It would be safe to truncate the roots
    // of the expression to this width.
    unsigned MaxBitWidth = 1u;

    // True if the roots can be zero-extended back to their original type,
    // rather than sign-extended. We know that if the leading bits are not
    // demanded, we can safely zero-extend. So we initialize IsKnownPositive to
    // True.
    // Determine if the sign bit of all the roots is known to be zero. If not,
    // IsKnownPositive is set to False.
    bool IsKnownPositive = !IsSignedCmp && all_of(E.Scalars, [&](Value *R) {
      KnownBits Known = computeKnownBits(R, *DL);
      return Known.isNonNegative();
    });

    // We first check if all the bits of the roots are demanded. If they're not,
    // we can truncate the roots to this narrower type.
    for (Value *Root : E.Scalars) {
      unsigned NumSignBits = ComputeNumSignBits(Root, *DL, 0, AC, nullptr, DT);
      TypeSize NumTypeBits =
          DL->getTypeSizeInBits(Root->getType()->getScalarType());
      unsigned BitWidth1 = NumTypeBits - NumSignBits;
      // If we can't prove that the sign bit is zero, we must add one to the
      // maximum bit width to account for the unknown sign bit. This preserves
      // the existing sign bit so we can safely sign-extend the root back to the
      // original type. Otherwise, if we know the sign bit is zero, we will
      // zero-extend the root instead.
      //
      // FIXME: This is somewhat suboptimal, as there will be cases where adding
      //        one to the maximum bit width will yield a larger-than-necessary
      //        type. In general, we need to add an extra bit only if we can't
      //        prove that the upper bit of the original type is equal to the
      //        upper bit of the proposed smaller type. If these two bits are
      //        the same (either zero or one) we know that sign-extending from
      //        the smaller type will result in the same value. Here, since we
      //        can't yet prove this, we are just making the proposed smaller
      //        type larger to ensure correctness.
      if (!IsKnownPositive)
        ++BitWidth1;

      APInt Mask = DB->getDemandedBits(cast<Instruction>(Root));
      unsigned BitWidth2 = Mask.getBitWidth() - Mask.countl_zero();
      MaxBitWidth =
          std::max<unsigned>(std::min(BitWidth1, BitWidth2), MaxBitWidth);
    }

    if (MaxBitWidth < 8 && MaxBitWidth > 1)
      MaxBitWidth = 8;

    // If the original type is large, but reduced type does not improve the reg
    // use - ignore it.
    if (NumParts > 1 &&
        NumParts ==
            TTI->getNumberOfParts(getWidenedType(
                IntegerType::get(F->getContext(), bit_ceil(MaxBitWidth)), VF)))
      return 0u;

    bool IsProfitableToDemote = Opcode == Instruction::Trunc ||
                                Opcode == Instruction::SExt ||
                                Opcode == Instruction::ZExt || NumParts > 1;
    // Conservatively determine if we can actually truncate the roots of the
    // expression. Collect the values that can be demoted in ToDemote and
    // additional roots that require investigating in Roots.
    DenseSet<const TreeEntry *> Visited;
    unsigned MaxDepthLevel = IsTruncRoot ? Limit : 1;
    bool NeedToDemote = IsProfitableToDemote;

    if (!collectValuesToDemote(E, IsProfitableToDemoteRoot, MaxBitWidth,
                               ToDemote, Visited, MaxDepthLevel, NeedToDemote,
                               IsTruncRoot) ||
        (MaxDepthLevel <= Limit &&
         !(((Opcode == Instruction::SExt || Opcode == Instruction::ZExt) &&
            (!IsTopRoot || !(IsStoreOrInsertElt || UserIgnoreList) ||
             DL->getTypeSizeInBits(TreeRootIT) /
                     DL->getTypeSizeInBits(cast<Instruction>(E.Scalars.front())
                                               ->getOperand(0)
                                               ->getType()) >
                 2)))))
      return 0u;
    // Round MaxBitWidth up to the next power-of-two.
    MaxBitWidth = bit_ceil(MaxBitWidth);

    return MaxBitWidth;
  };

  // If we can truncate the root, we must collect additional values that might
  // be demoted as a result. That is, those seeded by truncations we will
  // modify.
  // Add reduction ops sizes, if any.
  if (UserIgnoreList &&
      isa<IntegerType>(VectorizableTree.front()->Scalars.front()->getType())) {
    for (Value *V : *UserIgnoreList) {
      auto NumSignBits = ComputeNumSignBits(V, *DL, 0, AC, nullptr, DT);
      auto NumTypeBits = DL->getTypeSizeInBits(V->getType());
      unsigned BitWidth1 = NumTypeBits - NumSignBits;
      if (!isKnownNonNegative(V, SimplifyQuery(*DL)))
        ++BitWidth1;
      unsigned BitWidth2 = BitWidth1;
      if (!RecurrenceDescriptor::isIntMinMaxRecurrenceKind(::getRdxKind(V))) {
        auto Mask = DB->getDemandedBits(cast<Instruction>(V));
        BitWidth2 = Mask.getBitWidth() - Mask.countl_zero();
      }
      ReductionBitWidth =
          std::max(std::min(BitWidth1, BitWidth2), ReductionBitWidth);
    }
    if (ReductionBitWidth < 8 && ReductionBitWidth > 1)
      ReductionBitWidth = 8;

    ReductionBitWidth = bit_ceil(ReductionBitWidth);
  }
  bool IsTopRoot = NodeIdx == 0;
  while (NodeIdx < VectorizableTree.size() &&
         VectorizableTree[NodeIdx]->State == TreeEntry::Vectorize &&
         VectorizableTree[NodeIdx]->getOpcode() == Instruction::Trunc) {
    RootDemotes.push_back(NodeIdx);
    ++NodeIdx;
    IsTruncRoot = true;
  }
  bool IsSignedCmp = false;
  while (NodeIdx < VectorizableTree.size()) {
    ArrayRef<Value *> TreeRoot = VectorizableTree[NodeIdx]->Scalars;
    unsigned Limit = 2;
    unsigned Opcode = VectorizableTree[NodeIdx]->getOpcode();
    if (IsTopRoot &&
        ReductionBitWidth ==
            DL->getTypeSizeInBits(
                VectorizableTree.front()->Scalars.front()->getType()))
      Limit = 3;
    unsigned MaxBitWidth = ComputeMaxBitWidth(
        *VectorizableTree[NodeIdx], IsTopRoot, IsProfitableToDemoteRoot, Opcode,
        Limit, IsTruncRoot, IsSignedCmp);
    if (ReductionBitWidth != 0 && (IsTopRoot || !RootDemotes.empty())) {
      if (MaxBitWidth != 0 && ReductionBitWidth < MaxBitWidth)
        ReductionBitWidth = bit_ceil(MaxBitWidth);
      else if (MaxBitWidth == 0)
        ReductionBitWidth = 0;
    }

    for (unsigned Idx : RootDemotes) {
      if (all_of(VectorizableTree[Idx]->Scalars, [&](Value *V) {
            uint32_t OrigBitWidth =
                DL->getTypeSizeInBits(V->getType()->getScalarType());
            if (OrigBitWidth > MaxBitWidth) {
              APInt Mask = APInt::getBitsSetFrom(OrigBitWidth, MaxBitWidth);
              return MaskedValueIsZero(V, Mask, SimplifyQuery(*DL));
            }
            return false;
          }))
        ToDemote.push_back(Idx);
    }
    RootDemotes.clear();
    IsTopRoot = false;
    IsProfitableToDemoteRoot = true;

    if (ExtraBitWidthNodes.empty()) {
      NodeIdx = VectorizableTree.size();
    } else {
      unsigned NewIdx = 0;
      do {
        NewIdx = *ExtraBitWidthNodes.begin();
        ExtraBitWidthNodes.erase(ExtraBitWidthNodes.begin());
      } while (NewIdx <= NodeIdx && !ExtraBitWidthNodes.empty());
      NodeIdx = NewIdx;
      IsTruncRoot =
          NodeIdx < VectorizableTree.size() &&
          any_of(VectorizableTree[NodeIdx]->UserTreeIndices,
                 [](const EdgeInfo &EI) {
                   return EI.EdgeIdx == 0 &&
                          EI.UserTE->getOpcode() == Instruction::Trunc &&
                          !EI.UserTE->isAltShuffle();
                 });
      IsSignedCmp =
          NodeIdx < VectorizableTree.size() &&
          any_of(VectorizableTree[NodeIdx]->UserTreeIndices,
                 [&](const EdgeInfo &EI) {
                   return EI.UserTE->getOpcode() == Instruction::ICmp &&
                          any_of(EI.UserTE->Scalars, [&](Value *V) {
                            auto *IC = dyn_cast<ICmpInst>(V);
                            return IC &&
                                   (IC->isSigned() ||
                                    !isKnownNonNegative(IC->getOperand(0),
                                                        SimplifyQuery(*DL)) ||
                                    !isKnownNonNegative(IC->getOperand(1),
                                                        SimplifyQuery(*DL)));
                          });
                 });
    }

    // If the maximum bit width we compute is less than the with of the roots'
    // type, we can proceed with the narrowing. Otherwise, do nothing.
    if (MaxBitWidth == 0 ||
        MaxBitWidth >=
            cast<IntegerType>(TreeRoot.front()->getType()->getScalarType())
                ->getBitWidth()) {
      if (UserIgnoreList)
        AnalyzedMinBWVals.insert(TreeRoot.begin(), TreeRoot.end());
      continue;
    }

    // Finally, map the values we can demote to the maximum bit with we
    // computed.
    for (unsigned Idx : ToDemote) {
      TreeEntry *TE = VectorizableTree[Idx].get();
      if (MinBWs.contains(TE))
        continue;
      bool IsSigned = any_of(TE->Scalars, [&](Value *R) {
                        return !isKnownNonNegative(R, SimplifyQuery(*DL));
                      });
      MinBWs.try_emplace(TE, MaxBitWidth, IsSigned);
    }
  }
}

PreservedAnalyses SLPVectorizerPass::run(Function &F, FunctionAnalysisManager &AM) {
  auto *SE = &AM.getResult<ScalarEvolutionAnalysis>(F);
  auto *TTI = &AM.getResult<TargetIRAnalysis>(F);
  auto *TLI = AM.getCachedResult<TargetLibraryAnalysis>(F);
  auto *AA = &AM.getResult<AAManager>(F);
  auto *LI = &AM.getResult<LoopAnalysis>(F);
  auto *DT = &AM.getResult<DominatorTreeAnalysis>(F);
  auto *AC = &AM.getResult<AssumptionAnalysis>(F);
  auto *DB = &AM.getResult<DemandedBitsAnalysis>(F);
  auto *ORE = &AM.getResult<OptimizationRemarkEmitterAnalysis>(F);

  bool Changed = runImpl(F, SE, TTI, TLI, AA, LI, DT, AC, DB, ORE);
  if (!Changed)
    return PreservedAnalyses::all();

  PreservedAnalyses PA;
  PA.preserveSet<CFGAnalyses>();
  return PA;
}

bool SLPVectorizerPass::runImpl(Function &F, ScalarEvolution *SE_,
                                TargetTransformInfo *TTI_,
                                TargetLibraryInfo *TLI_, AAResults *AA_,
                                LoopInfo *LI_, DominatorTree *DT_,
                                AssumptionCache *AC_, DemandedBits *DB_,
                                OptimizationRemarkEmitter *ORE_) {
  if (!RunSLPVectorization)
    return false;
  SE = SE_;
  TTI = TTI_;
  TLI = TLI_;
  AA = AA_;
  LI = LI_;
  DT = DT_;
  AC = AC_;
  DB = DB_;
  DL = &F.getDataLayout();

  Stores.clear();
  GEPs.clear();
  bool Changed = false;

  // If the target claims to have no vector registers don't attempt
  // vectorization.
  if (!TTI->getNumberOfRegisters(TTI->getRegisterClassForType(true))) {
    LLVM_DEBUG(
        dbgs() << "SLP: Didn't find any vector registers for target, abort.\n");
    return false;
  }

  // Don't vectorize when the attribute NoImplicitFloat is used.
  if (F.hasFnAttribute(Attribute::NoImplicitFloat))
    return false;

  LLVM_DEBUG(dbgs() << "SLP: Analyzing blocks in " << F.getName() << ".\n");

  // Use the bottom up slp vectorizer to construct chains that start with
  // store instructions.
  BoUpSLP R(&F, SE, TTI, TLI, AA, LI, DT, AC, DB, DL, ORE_);

  // A general note: the vectorizer must use BoUpSLP::eraseInstruction() to
  // delete instructions.

  // Update DFS numbers now so that we can use them for ordering.
  DT->updateDFSNumbers();

  // Scan the blocks in the function in post order.
  for (auto *BB : post_order(&F.getEntryBlock())) {
    // Start new block - clear the list of reduction roots.
    R.clearReductionData();
    collectSeedInstructions(BB);

    // Vectorize trees that end at stores.
    if (!Stores.empty()) {
      LLVM_DEBUG(dbgs() << "SLP: Found stores for " << Stores.size()
                        << " underlying objects.\n");
      Changed |= vectorizeStoreChains(R);
    }

    // Vectorize trees that end at reductions.
    Changed |= vectorizeChainsInBlock(BB, R);

    // Vectorize the index computations of getelementptr instructions. This
    // is primarily intended to catch gather-like idioms ending at
    // non-consecutive loads.
    if (!GEPs.empty()) {
      LLVM_DEBUG(dbgs() << "SLP: Found GEPs for " << GEPs.size()
                        << " underlying objects.\n");
      Changed |= vectorizeGEPIndices(BB, R);
    }
  }

  if (Changed) {
    R.optimizeGatherSequence();
    LLVM_DEBUG(dbgs() << "SLP: vectorized \"" << F.getName() << "\"\n");
  }
  return Changed;
}

std::optional<bool>
SLPVectorizerPass::vectorizeStoreChain(ArrayRef<Value *> Chain, BoUpSLP &R,
                                       unsigned Idx, unsigned MinVF,
                                       unsigned &Size) {
  Size = 0;
  LLVM_DEBUG(dbgs() << "SLP: Analyzing a store chain of length " << Chain.size()
                    << "\n");
  const unsigned Sz = R.getVectorElementSize(Chain[0]);
  unsigned VF = Chain.size();

  if (!has_single_bit(Sz) || !has_single_bit(VF) || VF < 2 || VF < MinVF) {
    // Check if vectorizing with a non-power-of-2 VF should be considered. At
    // the moment, only consider cases where VF + 1 is a power-of-2, i.e. almost
    // all vector lanes are used.
    if (!VectorizeNonPowerOf2 || (VF < MinVF && VF + 1 != MinVF))
      return false;
  }

  LLVM_DEBUG(dbgs() << "SLP: Analyzing " << VF << " stores at offset " << Idx
                    << "\n");

  SetVector<Value *> ValOps;
  for (Value *V : Chain)
    ValOps.insert(cast<StoreInst>(V)->getValueOperand());
  // Operands are not same/alt opcodes or non-power-of-2 uniques - exit.
  InstructionsState S = getSameOpcode(ValOps.getArrayRef(), *TLI);
  if (all_of(ValOps, IsaPred<Instruction>) && ValOps.size() > 1) {
    DenseSet<Value *> Stores(Chain.begin(), Chain.end());
    bool IsPowerOf2 =
        has_single_bit(ValOps.size()) ||
        (VectorizeNonPowerOf2 && has_single_bit(ValOps.size() + 1));
    if ((!IsPowerOf2 && S.getOpcode() && S.getOpcode() != Instruction::Load &&
         (!S.MainOp->isSafeToRemove() ||
          any_of(ValOps.getArrayRef(),
                 [&](Value *V) {
                   return !isa<ExtractElementInst>(V) &&
                          (V->getNumUses() > Chain.size() ||
                           any_of(V->users(), [&](User *U) {
                             return !Stores.contains(U);
                           }));
                 }))) ||
        (ValOps.size() > Chain.size() / 2 && !S.getOpcode())) {
      Size = (!IsPowerOf2 && S.getOpcode()) ? 1 : 2;
      return false;
    }
  }
  if (R.isLoadCombineCandidate(Chain))
    return true;
  R.buildTree(Chain);
  // Check if tree tiny and store itself or its value is not vectorized.
  if (R.isTreeTinyAndNotFullyVectorizable()) {
    if (R.isGathered(Chain.front()) ||
        R.isNotScheduled(cast<StoreInst>(Chain.front())->getValueOperand()))
      return std::nullopt;
    Size = R.getTreeSize();
    return false;
  }
  R.reorderTopToBottom();
  R.reorderBottomToTop();
  R.transformNodes();
  R.buildExternalUses();

  R.computeMinimumValueSizes();

  Size = R.getTreeSize();
  if (S.getOpcode() == Instruction::Load)
    Size = 2; // cut off masked gather small trees
  InstructionCost Cost = R.getTreeCost();

  LLVM_DEBUG(dbgs() << "SLP: Found cost = " << Cost << " for VF=" << VF << "\n");
  if (Cost < -SLPCostThreshold) {
    LLVM_DEBUG(dbgs() << "SLP: Decided to vectorize cost = " << Cost << "\n");

    using namespace ore;

    R.getORE()->emit(OptimizationRemark(SV_NAME, "StoresVectorized",
                                        cast<StoreInst>(Chain[0]))
                     << "Stores SLP vectorized with cost " << NV("Cost", Cost)
                     << " and with tree size "
                     << NV("TreeSize", R.getTreeSize()));

    R.vectorizeTree();
    return true;
  }

  return false;
}

/// Checks if the quadratic mean deviation is less than 90% of the mean size.
static bool checkTreeSizes(ArrayRef<std::pair<unsigned, unsigned>> Sizes,
                           bool First) {
  unsigned Num = 0;
  uint64_t Sum = std::accumulate(
      Sizes.begin(), Sizes.end(), static_cast<uint64_t>(0),
      [&](uint64_t V, const std::pair<unsigned, unsigned> &Val) {
        unsigned Size = First ? Val.first : Val.second;
        if (Size == 1)
          return V;
        ++Num;
        return V + Size;
      });
  if (Num == 0)
    return true;
  uint64_t Mean = Sum / Num;
  if (Mean == 0)
    return true;
  uint64_t Dev = std::accumulate(
                     Sizes.begin(), Sizes.end(), static_cast<uint64_t>(0),
                     [&](uint64_t V, const std::pair<unsigned, unsigned> &Val) {
                       unsigned P = First ? Val.first : Val.second;
                       if (P == 1)
                         return V;
                       return V + (P - Mean) * (P - Mean);
                     }) /
                 Num;
  return Dev * 81 / (Mean * Mean) == 0;
}

bool SLPVectorizerPass::vectorizeStores(
    ArrayRef<StoreInst *> Stores, BoUpSLP &R,
    DenseSet<std::tuple<Value *, Value *, Value *, Value *, unsigned>>
        &Visited) {
  // We may run into multiple chains that merge into a single chain. We mark the
  // stores that we vectorized so that we don't visit the same store twice.
  BoUpSLP::ValueSet VectorizedStores;
  bool Changed = false;

  struct StoreDistCompare {
    bool operator()(const std::pair<unsigned, int> &Op1,
                    const std::pair<unsigned, int> &Op2) const {
      return Op1.second < Op2.second;
    }
  };
  // A set of pairs (index of store in Stores array ref, Distance of the store
  // address relative to base store address in units).
  using StoreIndexToDistSet =
      std::set<std::pair<unsigned, int>, StoreDistCompare>;
  auto TryToVectorize = [&](const StoreIndexToDistSet &Set) {
    int PrevDist = -1;
    BoUpSLP::ValueList Operands;
    // Collect the chain into a list.
    for (auto [Idx, Data] : enumerate(Set)) {
      if (Operands.empty() || Data.second - PrevDist == 1) {
        Operands.push_back(Stores[Data.first]);
        PrevDist = Data.second;
        if (Idx != Set.size() - 1)
          continue;
      }
      auto E = make_scope_exit([&, &DataVar = Data]() {
        Operands.clear();
        Operands.push_back(Stores[DataVar.first]);
        PrevDist = DataVar.second;
      });

      if (Operands.size() <= 1 ||
          !Visited
               .insert({Operands.front(),
                        cast<StoreInst>(Operands.front())->getValueOperand(),
                        Operands.back(),
                        cast<StoreInst>(Operands.back())->getValueOperand(),
                        Operands.size()})
               .second)
        continue;

      unsigned MaxVecRegSize = R.getMaxVecRegSize();
      unsigned EltSize = R.getVectorElementSize(Operands[0]);
      unsigned MaxElts = llvm::bit_floor(MaxVecRegSize / EltSize);

      unsigned MaxVF =
          std::min(R.getMaximumVF(EltSize, Instruction::Store), MaxElts);
      unsigned MaxRegVF = MaxVF;
      auto *Store = cast<StoreInst>(Operands[0]);
      Type *StoreTy = Store->getValueOperand()->getType();
      Type *ValueTy = StoreTy;
      if (auto *Trunc = dyn_cast<TruncInst>(Store->getValueOperand()))
        ValueTy = Trunc->getSrcTy();
      if (ValueTy == StoreTy &&
          R.getVectorElementSize(Store->getValueOperand()) <= EltSize)
        MaxVF = std::min<unsigned>(MaxVF, bit_floor(Operands.size()));
      unsigned MinVF = std::max<unsigned>(
          2, PowerOf2Ceil(TTI->getStoreMinimumVF(
                 R.getMinVF(DL->getTypeStoreSizeInBits(StoreTy)), StoreTy,
                 ValueTy)));

      if (MaxVF < MinVF) {
        LLVM_DEBUG(dbgs() << "SLP: Vectorization infeasible as MaxVF (" << MaxVF
                          << ") < "
                          << "MinVF (" << MinVF << ")\n");
        continue;
      }

      unsigned NonPowerOf2VF = 0;
      if (VectorizeNonPowerOf2) {
        // First try vectorizing with a non-power-of-2 VF. At the moment, only
        // consider cases where VF + 1 is a power-of-2, i.e. almost all vector
        // lanes are used.
        unsigned CandVF =
            std::clamp<unsigned>(Operands.size(), MaxVF, MaxRegVF);
        if (has_single_bit(CandVF + 1))
          NonPowerOf2VF = CandVF;
      }

      unsigned Sz = 1 + Log2_32(MaxVF) - Log2_32(MinVF);
      SmallVector<unsigned> CandidateVFs(Sz + (NonPowerOf2VF > 0 ? 1 : 0));
      unsigned Size = MinVF;
      for_each(reverse(CandidateVFs), [&](unsigned &VF) {
        VF = Size > MaxVF ? NonPowerOf2VF : Size;
        Size *= 2;
      });
      unsigned End = Operands.size();
      unsigned Repeat = 0;
      constexpr unsigned MaxAttempts = 4;
      OwningArrayRef<std::pair<unsigned, unsigned>> RangeSizes(Operands.size());
      for_each(RangeSizes, [](std::pair<unsigned, unsigned> &P) {
        P.first = P.second = 1;
      });
      DenseMap<Value *, std::pair<unsigned, unsigned>> NonSchedulable;
      auto IsNotVectorized = [](bool First,
                                const std::pair<unsigned, unsigned> &P) {
        return First ? P.first > 0 : P.second > 0;
      };
      auto IsVectorized = [](bool First,
                             const std::pair<unsigned, unsigned> &P) {
        return First ? P.first == 0 : P.second == 0;
      };
      auto VFIsProfitable = [](bool First, unsigned Size,
                               const std::pair<unsigned, unsigned> &P) {
        return First ? Size >= P.first : Size >= P.second;
      };
      auto FirstSizeSame = [](unsigned Size,
                              const std::pair<unsigned, unsigned> &P) {
        return Size == P.first;
      };
      while (true) {
        ++Repeat;
        bool RepeatChanged = false;
        bool AnyProfitableGraph = false;
        for (unsigned Size : CandidateVFs) {
          AnyProfitableGraph = false;
          unsigned StartIdx = std::distance(
              RangeSizes.begin(),
              find_if(RangeSizes, std::bind(IsNotVectorized, Size >= MaxRegVF,
                                            std::placeholders::_1)));
          while (StartIdx < End) {
            unsigned EndIdx =
                std::distance(RangeSizes.begin(),
                              find_if(RangeSizes.drop_front(StartIdx),
                                      std::bind(IsVectorized, Size >= MaxRegVF,
                                                std::placeholders::_1)));
            unsigned Sz = EndIdx >= End ? End : EndIdx;
            for (unsigned Cnt = StartIdx; Cnt + Size <= Sz;) {
              if (!checkTreeSizes(RangeSizes.slice(Cnt, Size),
                                  Size >= MaxRegVF)) {
                ++Cnt;
                continue;
              }
              ArrayRef<Value *> Slice = ArrayRef(Operands).slice(Cnt, Size);
              assert(all_of(Slice,
                            [&](Value *V) {
                              return cast<StoreInst>(V)
                                         ->getValueOperand()
                                         ->getType() ==
                                     cast<StoreInst>(Slice.front())
                                         ->getValueOperand()
                                         ->getType();
                            }) &&
                     "Expected all operands of same type.");
              if (!NonSchedulable.empty()) {
                auto [NonSchedSizeMax, NonSchedSizeMin] =
                    NonSchedulable.lookup(Slice.front());
                if (NonSchedSizeMax > 0 && NonSchedSizeMin <= Size) {
                  Cnt += NonSchedSizeMax;
                  continue;
                }
              }
              unsigned TreeSize;
              std::optional<bool> Res =
                  vectorizeStoreChain(Slice, R, Cnt, MinVF, TreeSize);
              if (!Res) {
                NonSchedulable
                    .try_emplace(Slice.front(), std::make_pair(Size, Size))
                    .first->getSecond()
                    .second = Size;
              } else if (*Res) {
                // Mark the vectorized stores so that we don't vectorize them
                // again.
                VectorizedStores.insert(Slice.begin(), Slice.end());
                // Mark the vectorized stores so that we don't vectorize them
                // again.
                AnyProfitableGraph = RepeatChanged = Changed = true;
                // If we vectorized initial block, no need to try to vectorize
                // it again.
                for_each(RangeSizes.slice(Cnt, Size),
                         [](std::pair<unsigned, unsigned> &P) {
                           P.first = P.second = 0;
                         });
                if (Cnt < StartIdx + MinVF) {
                  for_each(RangeSizes.slice(StartIdx, Cnt - StartIdx),
                           [](std::pair<unsigned, unsigned> &P) {
                             P.first = P.second = 0;
                           });
                  StartIdx = Cnt + Size;
                }
                if (Cnt > Sz - Size - MinVF) {
                  for_each(RangeSizes.slice(Cnt + Size, Sz - (Cnt + Size)),
                           [](std::pair<unsigned, unsigned> &P) {
                             P.first = P.second = 0;
                           });
                  if (Sz == End)
                    End = Cnt;
                  Sz = Cnt;
                }
                Cnt += Size;
                continue;
              }
              if (Size > 2 && Res &&
                  !all_of(RangeSizes.slice(Cnt, Size),
                          std::bind(VFIsProfitable, Size >= MaxRegVF, TreeSize,
                                    std::placeholders::_1))) {
                Cnt += Size;
                continue;
              }
              // Check for the very big VFs that we're not rebuilding same
              // trees, just with larger number of elements.
              if (Size > MaxRegVF && TreeSize > 1 &&
                  all_of(RangeSizes.slice(Cnt, Size),
                         std::bind(FirstSizeSame, TreeSize,
                                   std::placeholders::_1))) {
                Cnt += Size;
                while (Cnt != Sz && RangeSizes[Cnt].first == TreeSize)
                  ++Cnt;
                continue;
              }
              if (TreeSize > 1)
                for_each(RangeSizes.slice(Cnt, Size),
                         [&](std::pair<unsigned, unsigned> &P) {
                           if (Size >= MaxRegVF)
                             P.second = std::max(P.second, TreeSize);
                           else
                             P.first = std::max(P.first, TreeSize);
                         });
              ++Cnt;
              AnyProfitableGraph = true;
            }
            if (StartIdx >= End)
              break;
            if (Sz - StartIdx < Size && Sz - StartIdx >= MinVF)
              AnyProfitableGraph = true;
            StartIdx = std::distance(
                RangeSizes.begin(),
                find_if(RangeSizes.drop_front(Sz),
                        std::bind(IsNotVectorized, Size >= MaxRegVF,
                                  std::placeholders::_1)));
          }
          if (!AnyProfitableGraph && Size >= MaxRegVF)
            break;
        }
        // All values vectorized - exit.
        if (all_of(RangeSizes, [](const std::pair<unsigned, unsigned> &P) {
              return P.first == 0 && P.second == 0;
            }))
          break;
        // Check if tried all attempts or no need for the last attempts at all.
        if (Repeat >= MaxAttempts ||
            (Repeat > 1 && (RepeatChanged || !AnyProfitableGraph)))
          break;
        constexpr unsigned StoresLimit = 64;
        const unsigned MaxTotalNum = bit_floor(std::min<unsigned>(
            Operands.size(),
            static_cast<unsigned>(
                End -
                std::distance(
                    RangeSizes.begin(),
                    find_if(RangeSizes, std::bind(IsNotVectorized, true,
                                                  std::placeholders::_1))) +
                1)));
        unsigned VF = PowerOf2Ceil(CandidateVFs.front()) * 2;
        if (VF > MaxTotalNum || VF >= StoresLimit)
          break;
        for_each(RangeSizes, [&](std::pair<unsigned, unsigned> &P) {
          if (P.first != 0)
            P.first = std::max(P.second, P.first);
        });
        // Last attempt to vectorize max number of elements, if all previous
        // attempts were unsuccessful because of the cost issues.
        CandidateVFs.clear();
        CandidateVFs.push_back(VF);
      }
    }
  };

  // Stores pair (first: index of the store into Stores array ref, address of
  // which taken as base, second: sorted set of pairs {index, dist}, which are
  // indices of stores in the set and their store location distances relative to
  // the base address).

  // Need to store the index of the very first store separately, since the set
  // may be reordered after the insertion and the first store may be moved. This
  // container allows to reduce number of calls of getPointersDiff() function.
  SmallVector<std::pair<unsigned, StoreIndexToDistSet>> SortedStores;
  // Inserts the specified store SI with the given index Idx to the set of the
  // stores. If the store with the same distance is found already - stop
  // insertion, try to vectorize already found stores. If some stores from this
  // sequence were not vectorized - try to vectorize them with the new store
  // later. But this logic is applied only to the stores, that come before the
  // previous store with the same distance.
  // Example:
  // 1. store x, %p
  // 2. store y, %p+1
  // 3. store z, %p+2
  // 4. store a, %p
  // 5. store b, %p+3
  // - Scan this from the last to first store. The very first bunch of stores is
  // {5, {{4, -3}, {2, -2}, {3, -1}, {5, 0}}} (the element in SortedStores
  // vector).
  // - The next store in the list - #1 - has the same distance from store #5 as
  // the store #4.
  // - Try to vectorize sequence of stores 4,2,3,5.
  // - If all these stores are vectorized - just drop them.
  // - If some of them are not vectorized (say, #3 and #5), do extra analysis.
  // - Start new stores sequence.
  // The new bunch of stores is {1, {1, 0}}.
  // - Add the stores from previous sequence, that were not vectorized.
  // Here we consider the stores in the reversed order, rather they are used in
  // the IR (Stores are reversed already, see vectorizeStoreChains() function).
  // Store #3 can be added -> comes after store #4 with the same distance as
  // store #1.
  // Store #5 cannot be added - comes before store #4.
  // This logic allows to improve the compile time, we assume that the stores
  // after previous store with the same distance most likely have memory
  // dependencies and no need to waste compile time to try to vectorize them.
  // - Try to vectorize the sequence {1, {1, 0}, {3, 2}}.
  auto FillStoresSet = [&](unsigned Idx, StoreInst *SI) {
    for (std::pair<unsigned, StoreIndexToDistSet> &Set : SortedStores) {
      std::optional<int> Diff = getPointersDiff(
          Stores[Set.first]->getValueOperand()->getType(),
          Stores[Set.first]->getPointerOperand(),
          SI->getValueOperand()->getType(), SI->getPointerOperand(), *DL, *SE,
          /*StrictCheck=*/true);
      if (!Diff)
        continue;
      auto It = Set.second.find(std::make_pair(Idx, *Diff));
      if (It == Set.second.end()) {
        Set.second.emplace(Idx, *Diff);
        return;
      }
      // Try to vectorize the first found set to avoid duplicate analysis.
      TryToVectorize(Set.second);
      StoreIndexToDistSet PrevSet;
      PrevSet.swap(Set.second);
      Set.first = Idx;
      Set.second.emplace(Idx, 0);
      // Insert stores that followed previous match to try to vectorize them
      // with this store.
      unsigned StartIdx = It->first + 1;
      SmallBitVector UsedStores(Idx - StartIdx);
      // Distances to previously found dup store (or this store, since they
      // store to the same addresses).
      SmallVector<int> Dists(Idx - StartIdx, 0);
      for (const std::pair<unsigned, int> &Pair : reverse(PrevSet)) {
        // Do not try to vectorize sequences, we already tried.
        if (Pair.first <= It->first ||
            VectorizedStores.contains(Stores[Pair.first]))
          break;
        unsigned BI = Pair.first - StartIdx;
        UsedStores.set(BI);
        Dists[BI] = Pair.second - It->second;
      }
      for (unsigned I = StartIdx; I < Idx; ++I) {
        unsigned BI = I - StartIdx;
        if (UsedStores.test(BI))
          Set.second.emplace(I, Dists[BI]);
      }
      return;
    }
    auto &Res = SortedStores.emplace_back();
    Res.first = Idx;
    Res.second.emplace(Idx, 0);
  };
  Type *PrevValTy = nullptr;
  for (auto [I, SI] : enumerate(Stores)) {
    if (R.isDeleted(SI))
      continue;
    if (!PrevValTy)
      PrevValTy = SI->getValueOperand()->getType();
    // Check that we do not try to vectorize stores of different types.
    if (PrevValTy != SI->getValueOperand()->getType()) {
      for (auto &Set : SortedStores)
        TryToVectorize(Set.second);
      SortedStores.clear();
      PrevValTy = SI->getValueOperand()->getType();
    }
    FillStoresSet(I, SI);
  }

  // Final vectorization attempt.
  for (auto &Set : SortedStores)
    TryToVectorize(Set.second);

  return Changed;
}

void SLPVectorizerPass::collectSeedInstructions(BasicBlock *BB) {
  // Initialize the collections. We will make a single pass over the block.
  Stores.clear();
  GEPs.clear();

  // Visit the store and getelementptr instructions in BB and organize them in
  // Stores and GEPs according to the underlying objects of their pointer
  // operands.
  for (Instruction &I : *BB) {
    // Ignore store instructions that are volatile or have a pointer operand
    // that doesn't point to a scalar type.
    if (auto *SI = dyn_cast<StoreInst>(&I)) {
      if (!SI->isSimple())
        continue;
      if (!isValidElementType(SI->getValueOperand()->getType()))
        continue;
      Stores[getUnderlyingObject(SI->getPointerOperand())].push_back(SI);
    }

    // Ignore getelementptr instructions that have more than one index, a
    // constant index, or a pointer operand that doesn't point to a scalar
    // type.
    else if (auto *GEP = dyn_cast<GetElementPtrInst>(&I)) {
      if (GEP->getNumIndices() != 1)
        continue;
      Value *Idx = GEP->idx_begin()->get();
      if (isa<Constant>(Idx))
        continue;
      if (!isValidElementType(Idx->getType()))
        continue;
      if (GEP->getType()->isVectorTy())
        continue;
      GEPs[GEP->getPointerOperand()].push_back(GEP);
    }
  }
}

bool SLPVectorizerPass::tryToVectorizeList(ArrayRef<Value *> VL, BoUpSLP &R,
                                           bool MaxVFOnly) {
  if (VL.size() < 2)
    return false;

  LLVM_DEBUG(dbgs() << "SLP: Trying to vectorize a list of length = "
                    << VL.size() << ".\n");

  // Check that all of the parts are instructions of the same type,
  // we permit an alternate opcode via InstructionsState.
  InstructionsState S = getSameOpcode(VL, *TLI);
  if (!S.getOpcode())
    return false;

  Instruction *I0 = cast<Instruction>(S.OpValue);
  // Make sure invalid types (including vector type) are rejected before
  // determining vectorization factor for scalar instructions.
  for (Value *V : VL) {
    Type *Ty = V->getType();
    if (!isa<InsertElementInst>(V) && !isValidElementType(Ty)) {
      // NOTE: the following will give user internal llvm type name, which may
      // not be useful.
      R.getORE()->emit([&]() {
        std::string TypeStr;
        llvm::raw_string_ostream rso(TypeStr);
        Ty->print(rso);
        return OptimizationRemarkMissed(SV_NAME, "UnsupportedType", I0)
               << "Cannot SLP vectorize list: type "
               << TypeStr + " is unsupported by vectorizer";
      });
      return false;
    }
  }

  unsigned Sz = R.getVectorElementSize(I0);
  unsigned MinVF = R.getMinVF(Sz);
  unsigned MaxVF = std::max<unsigned>(llvm::bit_floor(VL.size()), MinVF);
  MaxVF = std::min(R.getMaximumVF(Sz, S.getOpcode()), MaxVF);
  if (MaxVF < 2) {
    R.getORE()->emit([&]() {
      return OptimizationRemarkMissed(SV_NAME, "SmallVF", I0)
             << "Cannot SLP vectorize list: vectorization factor "
             << "less than 2 is not supported";
    });
    return false;
  }

  bool Changed = false;
  bool CandidateFound = false;
  InstructionCost MinCost = SLPCostThreshold.getValue();
  Type *ScalarTy = getValueType(VL[0]);

  unsigned NextInst = 0, MaxInst = VL.size();
  for (unsigned VF = MaxVF; NextInst + 1 < MaxInst && VF >= MinVF; VF /= 2) {
    // No actual vectorization should happen, if number of parts is the same as
    // provided vectorization factor (i.e. the scalar type is used for vector
    // code during codegen).
    auto *VecTy = getWidenedType(ScalarTy, VF);
    if (TTI->getNumberOfParts(VecTy) == VF)
      continue;
    for (unsigned I = NextInst; I < MaxInst; ++I) {
      unsigned ActualVF = std::min(MaxInst - I, VF);

      if (!has_single_bit(ActualVF))
        continue;

      if (MaxVFOnly && ActualVF < MaxVF)
        break;
      if ((VF > MinVF && ActualVF <= VF / 2) || (VF == MinVF && ActualVF < 2))
        break;

      ArrayRef<Value *> Ops = VL.slice(I, ActualVF);
      // Check that a previous iteration of this loop did not delete the Value.
      if (llvm::any_of(Ops, [&R](Value *V) {
            auto *I = dyn_cast<Instruction>(V);
            return I && R.isDeleted(I);
          }))
        continue;

      LLVM_DEBUG(dbgs() << "SLP: Analyzing " << ActualVF << " operations "
                        << "\n");

      R.buildTree(Ops);
      if (R.isTreeTinyAndNotFullyVectorizable())
        continue;
      R.reorderTopToBottom();
      R.reorderBottomToTop(
          /*IgnoreReorder=*/!isa<InsertElementInst>(Ops.front()) &&
          !R.doesRootHaveInTreeUses());
      R.transformNodes();
      R.buildExternalUses();

      R.computeMinimumValueSizes();
      InstructionCost Cost = R.getTreeCost();
      CandidateFound = true;
      MinCost = std::min(MinCost, Cost);

      LLVM_DEBUG(dbgs() << "SLP: Found cost = " << Cost
                        << " for VF=" << ActualVF << "\n");
      if (Cost < -SLPCostThreshold) {
        LLVM_DEBUG(dbgs() << "SLP: Vectorizing list at cost:" << Cost << ".\n");
        R.getORE()->emit(OptimizationRemark(SV_NAME, "VectorizedList",
                                                    cast<Instruction>(Ops[0]))
                                 << "SLP vectorized with cost " << ore::NV("Cost", Cost)
                                 << " and with tree size "
                                 << ore::NV("TreeSize", R.getTreeSize()));

        R.vectorizeTree();
        // Move to the next bundle.
        I += VF - 1;
        NextInst = I + 1;
        Changed = true;
      }
    }
  }

  if (!Changed && CandidateFound) {
    R.getORE()->emit([&]() {
      return OptimizationRemarkMissed(SV_NAME, "NotBeneficial", I0)
             << "List vectorization was possible but not beneficial with cost "
             << ore::NV("Cost", MinCost) << " >= "
             << ore::NV("Treshold", -SLPCostThreshold);
    });
  } else if (!Changed) {
    R.getORE()->emit([&]() {
      return OptimizationRemarkMissed(SV_NAME, "NotPossible", I0)
             << "Cannot SLP vectorize list: vectorization was impossible"
             << " with available vectorization factors";
    });
  }
  return Changed;
}

bool SLPVectorizerPass::tryToVectorize(Instruction *I, BoUpSLP &R) {
  if (!I)
    return false;

  if (!isa<BinaryOperator, CmpInst>(I) || isa<VectorType>(I->getType()))
    return false;

  Value *P = I->getParent();

  // Vectorize in current basic block only.
  auto *Op0 = dyn_cast<Instruction>(I->getOperand(0));
  auto *Op1 = dyn_cast<Instruction>(I->getOperand(1));
  if (!Op0 || !Op1 || Op0->getParent() != P || Op1->getParent() != P)
    return false;

  // First collect all possible candidates
  SmallVector<std::pair<Value *, Value *>, 4> Candidates;
  Candidates.emplace_back(Op0, Op1);

  auto *A = dyn_cast<BinaryOperator>(Op0);
  auto *B = dyn_cast<BinaryOperator>(Op1);
  // Try to skip B.
  if (A && B && B->hasOneUse()) {
    auto *B0 = dyn_cast<BinaryOperator>(B->getOperand(0));
    auto *B1 = dyn_cast<BinaryOperator>(B->getOperand(1));
    if (B0 && B0->getParent() == P)
      Candidates.emplace_back(A, B0);
    if (B1 && B1->getParent() == P)
      Candidates.emplace_back(A, B1);
  }
  // Try to skip A.
  if (B && A && A->hasOneUse()) {
    auto *A0 = dyn_cast<BinaryOperator>(A->getOperand(0));
    auto *A1 = dyn_cast<BinaryOperator>(A->getOperand(1));
    if (A0 && A0->getParent() == P)
      Candidates.emplace_back(A0, B);
    if (A1 && A1->getParent() == P)
      Candidates.emplace_back(A1, B);
  }

  if (Candidates.size() == 1)
    return tryToVectorizeList({Op0, Op1}, R);

  // We have multiple options. Try to pick the single best.
  std::optional<int> BestCandidate = R.findBestRootPair(Candidates);
  if (!BestCandidate)
    return false;
  return tryToVectorizeList(
      {Candidates[*BestCandidate].first, Candidates[*BestCandidate].second}, R);
}

namespace {

/// Model horizontal reductions.
///
/// A horizontal reduction is a tree of reduction instructions that has values
/// that can be put into a vector as its leaves. For example:
///
/// mul mul mul mul
///  \  /    \  /
///   +       +
///    \     /
///       +
/// This tree has "mul" as its leaf values and "+" as its reduction
/// instructions. A reduction can feed into a store or a binary operation
/// feeding a phi.
///    ...
///    \  /
///     +
///     |
///  phi +=
///
///  Or:
///    ...
///    \  /
///     +
///     |
///   *p =
///
class HorizontalReduction {
  using ReductionOpsType = SmallVector<Value *, 16>;
  using ReductionOpsListType = SmallVector<ReductionOpsType, 2>;
  ReductionOpsListType ReductionOps;
  /// List of possibly reduced values.
  SmallVector<SmallVector<Value *>> ReducedVals;
  /// Maps reduced value to the corresponding reduction operation.
  DenseMap<Value *, SmallVector<Instruction *>> ReducedValsToOps;
  WeakTrackingVH ReductionRoot;
  /// The type of reduction operation.
  RecurKind RdxKind;
  /// Checks if the optimization of original scalar identity operations on
  /// matched horizontal reductions is enabled and allowed.
  bool IsSupportedHorRdxIdentityOp = false;

  static bool isCmpSelMinMax(Instruction *I) {
    return match(I, m_Select(m_Cmp(), m_Value(), m_Value())) &&
           RecurrenceDescriptor::isMinMaxRecurrenceKind(getRdxKind(I));
  }

  // And/or are potentially poison-safe logical patterns like:
  // select x, y, false
  // select x, true, y
  static bool isBoolLogicOp(Instruction *I) {
    return isa<SelectInst>(I) &&
           (match(I, m_LogicalAnd()) || match(I, m_LogicalOr()));
  }

  /// Checks if instruction is associative and can be vectorized.
  static bool isVectorizable(RecurKind Kind, Instruction *I) {
    if (Kind == RecurKind::None)
      return false;

    // Integer ops that map to select instructions or intrinsics are fine.
    if (RecurrenceDescriptor::isIntMinMaxRecurrenceKind(Kind) ||
        isBoolLogicOp(I))
      return true;

    if (Kind == RecurKind::FMax || Kind == RecurKind::FMin) {
      // FP min/max are associative except for NaN and -0.0. We do not
      // have to rule out -0.0 here because the intrinsic semantics do not
      // specify a fixed result for it.
      return I->getFastMathFlags().noNaNs();
    }

    if (Kind == RecurKind::FMaximum || Kind == RecurKind::FMinimum)
      return true;

    return I->isAssociative();
  }

  static Value *getRdxOperand(Instruction *I, unsigned Index) {
    // Poison-safe 'or' takes the form: select X, true, Y
    // To make that work with the normal operand processing, we skip the
    // true value operand.
    // TODO: Change the code and data structures to handle this without a hack.
    if (getRdxKind(I) == RecurKind::Or && isa<SelectInst>(I) && Index == 1)
      return I->getOperand(2);
    return I->getOperand(Index);
  }

  /// Creates reduction operation with the current opcode.
  static Value *createOp(IRBuilderBase &Builder, RecurKind Kind, Value *LHS,
                         Value *RHS, const Twine &Name, bool UseSelect) {
    unsigned RdxOpcode = RecurrenceDescriptor::getOpcode(Kind);
    switch (Kind) {
    case RecurKind::Or:
      if (UseSelect &&
          LHS->getType() == CmpInst::makeCmpResultType(LHS->getType()))
        return Builder.CreateSelect(LHS, Builder.getTrue(), RHS, Name);
      return Builder.CreateBinOp((Instruction::BinaryOps)RdxOpcode, LHS, RHS,
                                 Name);
    case RecurKind::And:
      if (UseSelect &&
          LHS->getType() == CmpInst::makeCmpResultType(LHS->getType()))
        return Builder.CreateSelect(LHS, RHS, Builder.getFalse(), Name);
      return Builder.CreateBinOp((Instruction::BinaryOps)RdxOpcode, LHS, RHS,
                                 Name);
    case RecurKind::Add:
    case RecurKind::Mul:
    case RecurKind::Xor:
    case RecurKind::FAdd:
    case RecurKind::FMul:
      return Builder.CreateBinOp((Instruction::BinaryOps)RdxOpcode, LHS, RHS,
                                 Name);
    case RecurKind::FMax:
      return Builder.CreateBinaryIntrinsic(Intrinsic::maxnum, LHS, RHS);
    case RecurKind::FMin:
      return Builder.CreateBinaryIntrinsic(Intrinsic::minnum, LHS, RHS);
    case RecurKind::FMaximum:
      return Builder.CreateBinaryIntrinsic(Intrinsic::maximum, LHS, RHS);
    case RecurKind::FMinimum:
      return Builder.CreateBinaryIntrinsic(Intrinsic::minimum, LHS, RHS);
    case RecurKind::SMax:
      if (UseSelect) {
        Value *Cmp = Builder.CreateICmpSGT(LHS, RHS, Name);
        return Builder.CreateSelect(Cmp, LHS, RHS, Name);
      }
      return Builder.CreateBinaryIntrinsic(Intrinsic::smax, LHS, RHS);
    case RecurKind::SMin:
      if (UseSelect) {
        Value *Cmp = Builder.CreateICmpSLT(LHS, RHS, Name);
        return Builder.CreateSelect(Cmp, LHS, RHS, Name);
      }
      return Builder.CreateBinaryIntrinsic(Intrinsic::smin, LHS, RHS);
    case RecurKind::UMax:
      if (UseSelect) {
        Value *Cmp = Builder.CreateICmpUGT(LHS, RHS, Name);
        return Builder.CreateSelect(Cmp, LHS, RHS, Name);
      }
      return Builder.CreateBinaryIntrinsic(Intrinsic::umax, LHS, RHS);
    case RecurKind::UMin:
      if (UseSelect) {
        Value *Cmp = Builder.CreateICmpULT(LHS, RHS, Name);
        return Builder.CreateSelect(Cmp, LHS, RHS, Name);
      }
      return Builder.CreateBinaryIntrinsic(Intrinsic::umin, LHS, RHS);
    default:
      llvm_unreachable("Unknown reduction operation.");
    }
  }

  /// Creates reduction operation with the current opcode with the IR flags
  /// from \p ReductionOps, dropping nuw/nsw flags.
  static Value *createOp(IRBuilderBase &Builder, RecurKind RdxKind, Value *LHS,
                         Value *RHS, const Twine &Name,
                         const ReductionOpsListType &ReductionOps) {
    bool UseSelect = ReductionOps.size() == 2 ||
                     // Logical or/and.
                     (ReductionOps.size() == 1 &&
                      any_of(ReductionOps.front(), IsaPred<SelectInst>));
    assert((!UseSelect || ReductionOps.size() != 2 ||
            isa<SelectInst>(ReductionOps[1][0])) &&
           "Expected cmp + select pairs for reduction");
    Value *Op = createOp(Builder, RdxKind, LHS, RHS, Name, UseSelect);
    if (RecurrenceDescriptor::isIntMinMaxRecurrenceKind(RdxKind)) {
      if (auto *Sel = dyn_cast<SelectInst>(Op)) {
        propagateIRFlags(Sel->getCondition(), ReductionOps[0], nullptr,
                         /*IncludeWrapFlags=*/false);
        propagateIRFlags(Op, ReductionOps[1], nullptr,
                         /*IncludeWrapFlags=*/false);
        return Op;
      }
    }
    propagateIRFlags(Op, ReductionOps[0], nullptr, /*IncludeWrapFlags=*/false);
    return Op;
  }

public:
  static RecurKind getRdxKind(Value *V) {
    auto *I = dyn_cast<Instruction>(V);
    if (!I)
      return RecurKind::None;
    if (match(I, m_Add(m_Value(), m_Value())))
      return RecurKind::Add;
    if (match(I, m_Mul(m_Value(), m_Value())))
      return RecurKind::Mul;
    if (match(I, m_And(m_Value(), m_Value())) ||
        match(I, m_LogicalAnd(m_Value(), m_Value())))
      return RecurKind::And;
    if (match(I, m_Or(m_Value(), m_Value())) ||
        match(I, m_LogicalOr(m_Value(), m_Value())))
      return RecurKind::Or;
    if (match(I, m_Xor(m_Value(), m_Value())))
      return RecurKind::Xor;
    if (match(I, m_FAdd(m_Value(), m_Value())))
      return RecurKind::FAdd;
    if (match(I, m_FMul(m_Value(), m_Value())))
      return RecurKind::FMul;

    if (match(I, m_Intrinsic<Intrinsic::maxnum>(m_Value(), m_Value())))
      return RecurKind::FMax;
    if (match(I, m_Intrinsic<Intrinsic::minnum>(m_Value(), m_Value())))
      return RecurKind::FMin;

    if (match(I, m_Intrinsic<Intrinsic::maximum>(m_Value(), m_Value())))
      return RecurKind::FMaximum;
    if (match(I, m_Intrinsic<Intrinsic::minimum>(m_Value(), m_Value())))
      return RecurKind::FMinimum;
    // This matches either cmp+select or intrinsics. SLP is expected to handle
    // either form.
    // TODO: If we are canonicalizing to intrinsics, we can remove several
    //       special-case paths that deal with selects.
    if (match(I, m_SMax(m_Value(), m_Value())))
      return RecurKind::SMax;
    if (match(I, m_SMin(m_Value(), m_Value())))
      return RecurKind::SMin;
    if (match(I, m_UMax(m_Value(), m_Value())))
      return RecurKind::UMax;
    if (match(I, m_UMin(m_Value(), m_Value())))
      return RecurKind::UMin;

    if (auto *Select = dyn_cast<SelectInst>(I)) {
      // Try harder: look for min/max pattern based on instructions producing
      // same values such as: select ((cmp Inst1, Inst2), Inst1, Inst2).
      // During the intermediate stages of SLP, it's very common to have
      // pattern like this (since optimizeGatherSequence is run only once
      // at the end):
      // %1 = extractelement <2 x i32> %a, i32 0
      // %2 = extractelement <2 x i32> %a, i32 1
      // %cond = icmp sgt i32 %1, %2
      // %3 = extractelement <2 x i32> %a, i32 0
      // %4 = extractelement <2 x i32> %a, i32 1
      // %select = select i1 %cond, i32 %3, i32 %4
      CmpInst::Predicate Pred;
      Instruction *L1;
      Instruction *L2;

      Value *LHS = Select->getTrueValue();
      Value *RHS = Select->getFalseValue();
      Value *Cond = Select->getCondition();

      // TODO: Support inverse predicates.
      if (match(Cond, m_Cmp(Pred, m_Specific(LHS), m_Instruction(L2)))) {
        if (!isa<ExtractElementInst>(RHS) ||
            !L2->isIdenticalTo(cast<Instruction>(RHS)))
          return RecurKind::None;
      } else if (match(Cond, m_Cmp(Pred, m_Instruction(L1), m_Specific(RHS)))) {
        if (!isa<ExtractElementInst>(LHS) ||
            !L1->isIdenticalTo(cast<Instruction>(LHS)))
          return RecurKind::None;
      } else {
        if (!isa<ExtractElementInst>(LHS) || !isa<ExtractElementInst>(RHS))
          return RecurKind::None;
        if (!match(Cond, m_Cmp(Pred, m_Instruction(L1), m_Instruction(L2))) ||
            !L1->isIdenticalTo(cast<Instruction>(LHS)) ||
            !L2->isIdenticalTo(cast<Instruction>(RHS)))
          return RecurKind::None;
      }

      switch (Pred) {
      default:
        return RecurKind::None;
      case CmpInst::ICMP_SGT:
      case CmpInst::ICMP_SGE:
        return RecurKind::SMax;
      case CmpInst::ICMP_SLT:
      case CmpInst::ICMP_SLE:
        return RecurKind::SMin;
      case CmpInst::ICMP_UGT:
      case CmpInst::ICMP_UGE:
        return RecurKind::UMax;
      case CmpInst::ICMP_ULT:
      case CmpInst::ICMP_ULE:
        return RecurKind::UMin;
      }
    }
    return RecurKind::None;
  }

  /// Get the index of the first operand.
  static unsigned getFirstOperandIndex(Instruction *I) {
    return isCmpSelMinMax(I) ? 1 : 0;
  }

private:
  /// Total number of operands in the reduction operation.
  static unsigned getNumberOfOperands(Instruction *I) {
    return isCmpSelMinMax(I) ? 3 : 2;
  }

  /// Checks if the instruction is in basic block \p BB.
  /// For a cmp+sel min/max reduction check that both ops are in \p BB.
  static bool hasSameParent(Instruction *I, BasicBlock *BB) {
    if (isCmpSelMinMax(I) || isBoolLogicOp(I)) {
      auto *Sel = cast<SelectInst>(I);
      auto *Cmp = dyn_cast<Instruction>(Sel->getCondition());
      return Sel->getParent() == BB && Cmp && Cmp->getParent() == BB;
    }
    return I->getParent() == BB;
  }

  /// Expected number of uses for reduction operations/reduced values.
  static bool hasRequiredNumberOfUses(bool IsCmpSelMinMax, Instruction *I) {
    if (IsCmpSelMinMax) {
      // SelectInst must be used twice while the condition op must have single
      // use only.
      if (auto *Sel = dyn_cast<SelectInst>(I))
        return Sel->hasNUses(2) && Sel->getCondition()->hasOneUse();
      return I->hasNUses(2);
    }

    // Arithmetic reduction operation must be used once only.
    return I->hasOneUse();
  }

  /// Initializes the list of reduction operations.
  void initReductionOps(Instruction *I) {
    if (isCmpSelMinMax(I))
      ReductionOps.assign(2, ReductionOpsType());
    else
      ReductionOps.assign(1, ReductionOpsType());
  }

  /// Add all reduction operations for the reduction instruction \p I.
  void addReductionOps(Instruction *I) {
    if (isCmpSelMinMax(I)) {
      ReductionOps[0].emplace_back(cast<SelectInst>(I)->getCondition());
      ReductionOps[1].emplace_back(I);
    } else {
      ReductionOps[0].emplace_back(I);
    }
  }

  static bool isGoodForReduction(ArrayRef<Value *> Data) {
    int Sz = Data.size();
    auto *I = dyn_cast<Instruction>(Data.front());
    return Sz > 1 || isConstant(Data.front()) ||
           (I && !isa<LoadInst>(I) && isValidForAlternation(I->getOpcode()));
  }

public:
  HorizontalReduction() = default;

  /// Try to find a reduction tree.
  bool matchAssociativeReduction(BoUpSLP &R, Instruction *Root,
                                 ScalarEvolution &SE, const DataLayout &DL,
                                 const TargetLibraryInfo &TLI) {
    RdxKind = HorizontalReduction::getRdxKind(Root);
    if (!isVectorizable(RdxKind, Root))
      return false;

    // Analyze "regular" integer/FP types for reductions - no target-specific
    // types or pointers.
    Type *Ty = Root->getType();
    if (!isValidElementType(Ty) || Ty->isPointerTy())
      return false;

    // Though the ultimate reduction may have multiple uses, its condition must
    // have only single use.
    if (auto *Sel = dyn_cast<SelectInst>(Root))
      if (!Sel->getCondition()->hasOneUse())
        return false;

    ReductionRoot = Root;

    // Iterate through all the operands of the possible reduction tree and
    // gather all the reduced values, sorting them by their value id.
    BasicBlock *BB = Root->getParent();
    bool IsCmpSelMinMax = isCmpSelMinMax(Root);
    SmallVector<std::pair<Instruction *, unsigned>> Worklist(
        1, std::make_pair(Root, 0));
    // Checks if the operands of the \p TreeN instruction are also reduction
    // operations or should be treated as reduced values or an extra argument,
    // which is not part of the reduction.
    auto CheckOperands = [&](Instruction *TreeN,
                             SmallVectorImpl<Value *> &PossibleReducedVals,
                             SmallVectorImpl<Instruction *> &ReductionOps,
                             unsigned Level) {
      for (int I : reverse(seq<int>(getFirstOperandIndex(TreeN),
                                    getNumberOfOperands(TreeN)))) {
        Value *EdgeVal = getRdxOperand(TreeN, I);
        ReducedValsToOps[EdgeVal].push_back(TreeN);
        auto *EdgeInst = dyn_cast<Instruction>(EdgeVal);
        // If the edge is not an instruction, or it is different from the main
        // reduction opcode or has too many uses - possible reduced value.
        // Also, do not try to reduce const values, if the operation is not
        // foldable.
        if (!EdgeInst || Level > RecursionMaxDepth ||
            getRdxKind(EdgeInst) != RdxKind ||
            IsCmpSelMinMax != isCmpSelMinMax(EdgeInst) ||
            !hasRequiredNumberOfUses(IsCmpSelMinMax, EdgeInst) ||
            !isVectorizable(RdxKind, EdgeInst) ||
            (R.isAnalyzedReductionRoot(EdgeInst) &&
             all_of(EdgeInst->operands(), IsaPred<Constant>))) {
          PossibleReducedVals.push_back(EdgeVal);
          continue;
        }
        ReductionOps.push_back(EdgeInst);
      }
    };
    // Try to regroup reduced values so that it gets more profitable to try to
    // reduce them. Values are grouped by their value ids, instructions - by
    // instruction op id and/or alternate op id, plus do extra analysis for
    // loads (grouping them by the distabce between pointers) and cmp
    // instructions (grouping them by the predicate).
    MapVector<size_t, MapVector<size_t, MapVector<Value *, unsigned>>>
        PossibleReducedVals;
    initReductionOps(Root);
    DenseMap<Value *, SmallVector<LoadInst *>> LoadsMap;
    SmallSet<size_t, 2> LoadKeyUsed;

    auto GenerateLoadsSubkey = [&](size_t Key, LoadInst *LI) {
      Key = hash_combine(hash_value(LI->getParent()), Key);
      Value *Ptr = getUnderlyingObject(LI->getPointerOperand());
      if (LoadKeyUsed.contains(Key)) {
        auto LIt = LoadsMap.find(Ptr);
        if (LIt != LoadsMap.end()) {
          for (LoadInst *RLI : LIt->second) {
            if (getPointersDiff(RLI->getType(), RLI->getPointerOperand(),
                                LI->getType(), LI->getPointerOperand(), DL, SE,
                                /*StrictCheck=*/true))
              return hash_value(RLI->getPointerOperand());
          }
          for (LoadInst *RLI : LIt->second) {
            if (arePointersCompatible(RLI->getPointerOperand(),
                                      LI->getPointerOperand(), TLI)) {
              hash_code SubKey = hash_value(RLI->getPointerOperand());
              return SubKey;
            }
          }
          if (LIt->second.size() > 2) {
            hash_code SubKey =
                hash_value(LIt->second.back()->getPointerOperand());
            return SubKey;
          }
        }
      }
      LoadKeyUsed.insert(Key);
      LoadsMap.try_emplace(Ptr).first->second.push_back(LI);
      return hash_value(LI->getPointerOperand());
    };

    while (!Worklist.empty()) {
      auto [TreeN, Level] = Worklist.pop_back_val();
      SmallVector<Value *> PossibleRedVals;
      SmallVector<Instruction *> PossibleReductionOps;
      CheckOperands(TreeN, PossibleRedVals, PossibleReductionOps, Level);
      addReductionOps(TreeN);
      // Add reduction values. The values are sorted for better vectorization
      // results.
      for (Value *V : PossibleRedVals) {
        size_t Key, Idx;
        std::tie(Key, Idx) = generateKeySubkey(V, &TLI, GenerateLoadsSubkey,
                                               /*AllowAlternate=*/false);
        ++PossibleReducedVals[Key][Idx]
              .insert(std::make_pair(V, 0))
              .first->second;
      }
      for (Instruction *I : reverse(PossibleReductionOps))
        Worklist.emplace_back(I, I->getParent() == BB ? 0 : Level + 1);
    }
    auto PossibleReducedValsVect = PossibleReducedVals.takeVector();
    // Sort values by the total number of values kinds to start the reduction
    // from the longest possible reduced values sequences.
    for (auto &PossibleReducedVals : PossibleReducedValsVect) {
      auto PossibleRedVals = PossibleReducedVals.second.takeVector();
      SmallVector<SmallVector<Value *>> PossibleRedValsVect;
      for (auto It = PossibleRedVals.begin(), E = PossibleRedVals.end();
           It != E; ++It) {
        PossibleRedValsVect.emplace_back();
        auto RedValsVect = It->second.takeVector();
        stable_sort(RedValsVect, llvm::less_second());
        for (const std::pair<Value *, unsigned> &Data : RedValsVect)
          PossibleRedValsVect.back().append(Data.second, Data.first);
      }
      stable_sort(PossibleRedValsVect, [](const auto &P1, const auto &P2) {
        return P1.size() > P2.size();
      });
      int NewIdx = -1;
      for (ArrayRef<Value *> Data : PossibleRedValsVect) {
        if (NewIdx < 0 ||
            (!isGoodForReduction(Data) &&
             (!isa<LoadInst>(Data.front()) ||
              !isa<LoadInst>(ReducedVals[NewIdx].front()) ||
              getUnderlyingObject(
                  cast<LoadInst>(Data.front())->getPointerOperand()) !=
                  getUnderlyingObject(
                      cast<LoadInst>(ReducedVals[NewIdx].front())
                          ->getPointerOperand())))) {
          NewIdx = ReducedVals.size();
          ReducedVals.emplace_back();
        }
        ReducedVals[NewIdx].append(Data.rbegin(), Data.rend());
      }
    }
    // Sort the reduced values by number of same/alternate opcode and/or pointer
    // operand.
    stable_sort(ReducedVals, [](ArrayRef<Value *> P1, ArrayRef<Value *> P2) {
      return P1.size() > P2.size();
    });
    return true;
  }

  /// Attempt to vectorize the tree found by matchAssociativeReduction.
  Value *tryToReduce(BoUpSLP &V, const DataLayout &DL, TargetTransformInfo *TTI,
                     const TargetLibraryInfo &TLI) {
    const unsigned ReductionLimit = VectorizeNonPowerOf2 ? 3 : 4;
    constexpr unsigned RegMaxNumber = 4;
    constexpr unsigned RedValsMaxNumber = 128;
    // If there are a sufficient number of reduction values, reduce
    // to a nearby power-of-2. We can safely generate oversized
    // vectors and rely on the backend to split them to legal sizes.
    if (unsigned NumReducedVals = std::accumulate(
            ReducedVals.begin(), ReducedVals.end(), 0,
            [](unsigned Num, ArrayRef<Value *> Vals) -> unsigned {
              if (!isGoodForReduction(Vals))
                return Num;
              return Num + Vals.size();
            });
        NumReducedVals < ReductionLimit &&
        all_of(ReducedVals, [](ArrayRef<Value *> RedV) {
           return RedV.size() < 2 || !allConstant(RedV) || !isSplat(RedV);
         })) {
      for (ReductionOpsType &RdxOps : ReductionOps)
        for (Value *RdxOp : RdxOps)
          V.analyzedReductionRoot(cast<Instruction>(RdxOp));
      return nullptr;
    }

    IRBuilder<TargetFolder> Builder(ReductionRoot->getContext(),
                                    TargetFolder(DL));
    Builder.SetInsertPoint(cast<Instruction>(ReductionRoot));

    // Track the reduced values in case if they are replaced by extractelement
    // because of the vectorization.
    DenseMap<Value *, WeakTrackingVH> TrackedVals(ReducedVals.size() *
                                                  ReducedVals.front().size());

    // The compare instruction of a min/max is the insertion point for new
    // instructions and may be replaced with a new compare instruction.
    auto &&GetCmpForMinMaxReduction = [](Instruction *RdxRootInst) {
      assert(isa<SelectInst>(RdxRootInst) &&
             "Expected min/max reduction to have select root instruction");
      Value *ScalarCond = cast<SelectInst>(RdxRootInst)->getCondition();
      assert(isa<Instruction>(ScalarCond) &&
             "Expected min/max reduction to have compare condition");
      return cast<Instruction>(ScalarCond);
    };

    // Return new VectorizedTree, based on previous value.
    auto GetNewVectorizedTree = [&](Value *VectorizedTree, Value *Res) {
      if (VectorizedTree) {
        // Update the final value in the reduction.
        Builder.SetCurrentDebugLocation(
            cast<Instruction>(ReductionOps.front().front())->getDebugLoc());
        if ((isa<PoisonValue>(VectorizedTree) && !isa<PoisonValue>(Res)) ||
            (isGuaranteedNotToBePoison(Res) &&
             !isGuaranteedNotToBePoison(VectorizedTree))) {
          auto It = ReducedValsToOps.find(Res);
          if (It != ReducedValsToOps.end() &&
              any_of(It->getSecond(),
                     [](Instruction *I) { return isBoolLogicOp(I); }))
            std::swap(VectorizedTree, Res);
        }

        return createOp(Builder, RdxKind, VectorizedTree, Res, "op.rdx",
                        ReductionOps);
      }
      // Initialize the final value in the reduction.
      return Res;
    };
    bool AnyBoolLogicOp = any_of(ReductionOps.back(), [](Value *V) {
      return isBoolLogicOp(cast<Instruction>(V));
    });
    SmallDenseSet<Value *> IgnoreList(ReductionOps.size() *
                                      ReductionOps.front().size());
    for (ReductionOpsType &RdxOps : ReductionOps)
      for (Value *RdxOp : RdxOps) {
        if (!RdxOp)
          continue;
        IgnoreList.insert(RdxOp);
      }
    // Intersect the fast-math-flags from all reduction operations.
    FastMathFlags RdxFMF;
    RdxFMF.set();
    for (Value *U : IgnoreList)
      if (auto *FPMO = dyn_cast<FPMathOperator>(U))
        RdxFMF &= FPMO->getFastMathFlags();
    bool IsCmpSelMinMax = isCmpSelMinMax(cast<Instruction>(ReductionRoot));

    // Need to track reduced vals, they may be changed during vectorization of
    // subvectors.
    for (ArrayRef<Value *> Candidates : ReducedVals)
      for (Value *V : Candidates)
        TrackedVals.try_emplace(V, V);

    auto At = [](MapVector<Value *, unsigned> &MV, Value *V) -> unsigned & {
      auto *It = MV.find(V);
      assert(It != MV.end() && "Unable to find given key.");
      return It->second;
    };

    DenseMap<Value *, unsigned> VectorizedVals(ReducedVals.size());
    // List of the values that were reduced in other trees as part of gather
    // nodes and thus requiring extract if fully vectorized in other trees.
    SmallPtrSet<Value *, 4> RequiredExtract;
    Value *VectorizedTree = nullptr;
    bool CheckForReusedReductionOps = false;
    // Try to vectorize elements based on their type.
    SmallVector<InstructionsState> States;
    for (ArrayRef<Value *> RV : ReducedVals)
      States.push_back(getSameOpcode(RV, TLI));
    for (unsigned I = 0, E = ReducedVals.size(); I < E; ++I) {
      ArrayRef<Value *> OrigReducedVals = ReducedVals[I];
      InstructionsState S = States[I];
      SmallVector<Value *> Candidates;
      Candidates.reserve(2 * OrigReducedVals.size());
      DenseMap<Value *, Value *> TrackedToOrig(2 * OrigReducedVals.size());
      for (unsigned Cnt = 0, Sz = OrigReducedVals.size(); Cnt < Sz; ++Cnt) {
        Value *RdxVal = TrackedVals.at(OrigReducedVals[Cnt]);
        // Check if the reduction value was not overriden by the extractelement
        // instruction because of the vectorization and exclude it, if it is not
        // compatible with other values.
        // Also check if the instruction was folded to constant/other value.
        auto *Inst = dyn_cast<Instruction>(RdxVal);
        if ((Inst && isVectorLikeInstWithConstOps(Inst) &&
             (!S.getOpcode() || !S.isOpcodeOrAlt(Inst))) ||
            (S.getOpcode() && !Inst))
          continue;
        Candidates.push_back(RdxVal);
        TrackedToOrig.try_emplace(RdxVal, OrigReducedVals[Cnt]);
      }
      bool ShuffledExtracts = false;
      // Try to handle shuffled extractelements.
      if (S.getOpcode() == Instruction::ExtractElement && !S.isAltShuffle() &&
          I + 1 < E) {
        SmallVector<Value *> CommonCandidates(Candidates);
        for (Value *RV : ReducedVals[I + 1]) {
          Value *RdxVal = TrackedVals.at(RV);
          // Check if the reduction value was not overriden by the
          // extractelement instruction because of the vectorization and
          // exclude it, if it is not compatible with other values.
          auto *Inst = dyn_cast<ExtractElementInst>(RdxVal);
          if (!Inst)
            continue;
          CommonCandidates.push_back(RdxVal);
          TrackedToOrig.try_emplace(RdxVal, RV);
        }
        SmallVector<int> Mask;
        if (isFixedVectorShuffle(CommonCandidates, Mask)) {
          ++I;
          Candidates.swap(CommonCandidates);
          ShuffledExtracts = true;
        }
      }

      // Emit code for constant values.
      if (Candidates.size() > 1 && allConstant(Candidates)) {
        Value *Res = Candidates.front();
        Value *OrigV = TrackedToOrig.at(Candidates.front());
        ++VectorizedVals.try_emplace(OrigV).first->getSecond();
        for (Value *VC : ArrayRef(Candidates).drop_front()) {
          Res = createOp(Builder, RdxKind, Res, VC, "const.rdx", ReductionOps);
          Value *OrigV = TrackedToOrig.at(VC);
          ++VectorizedVals.try_emplace(OrigV).first->getSecond();
          if (auto *ResI = dyn_cast<Instruction>(Res))
            V.analyzedReductionRoot(ResI);
        }
        VectorizedTree = GetNewVectorizedTree(VectorizedTree, Res);
        continue;
      }

      unsigned NumReducedVals = Candidates.size();
      if (NumReducedVals < ReductionLimit &&
          (NumReducedVals < 2 || !isSplat(Candidates)))
        continue;

      // Check if we support repeated scalar values processing (optimization of
      // original scalar identity operations on matched horizontal reductions).
      IsSupportedHorRdxIdentityOp = RdxKind != RecurKind::Mul &&
                                    RdxKind != RecurKind::FMul &&
                                    RdxKind != RecurKind::FMulAdd;
      // Gather same values.
      MapVector<Value *, unsigned> SameValuesCounter;
      if (IsSupportedHorRdxIdentityOp)
        for (Value *V : Candidates) {
          Value *OrigV = TrackedToOrig.at(V);
          ++SameValuesCounter.try_emplace(OrigV).first->second;
        }
      // Used to check if the reduced values used same number of times. In this
      // case the compiler may produce better code. E.g. if reduced values are
      // aabbccdd (8 x values), then the first node of the tree will have a node
      // for 4 x abcd + shuffle <4 x abcd>, <0, 0, 1, 1, 2, 2, 3, 3>.
      // Plus, the final reduction will be performed on <8 x aabbccdd>.
      // Instead compiler may build <4 x abcd> tree immediately, + reduction (4
      // x abcd) * 2.
      // Currently it only handles add/fadd/xor. and/or/min/max do not require
      // this analysis, other operations may require an extra estimation of
      // the profitability.
      bool SameScaleFactor = false;
      bool OptReusedScalars = IsSupportedHorRdxIdentityOp &&
                              SameValuesCounter.size() != Candidates.size();
      if (OptReusedScalars) {
        SameScaleFactor =
            (RdxKind == RecurKind::Add || RdxKind == RecurKind::FAdd ||
             RdxKind == RecurKind::Xor) &&
            all_of(drop_begin(SameValuesCounter),
                   [&SameValuesCounter](const std::pair<Value *, unsigned> &P) {
                     return P.second == SameValuesCounter.front().second;
                   });
        Candidates.resize(SameValuesCounter.size());
        transform(SameValuesCounter, Candidates.begin(),
                  [&](const auto &P) { return TrackedVals.at(P.first); });
        NumReducedVals = Candidates.size();
        // Have a reduction of the same element.
        if (NumReducedVals == 1) {
          Value *OrigV = TrackedToOrig.at(Candidates.front());
          unsigned Cnt = At(SameValuesCounter, OrigV);
          Value *RedVal =
              emitScaleForReusedOps(Candidates.front(), Builder, Cnt);
          VectorizedTree = GetNewVectorizedTree(VectorizedTree, RedVal);
          VectorizedVals.try_emplace(OrigV, Cnt);
          continue;
        }
      }

      unsigned MaxVecRegSize = V.getMaxVecRegSize();
      unsigned EltSize = V.getVectorElementSize(Candidates[0]);
      const unsigned MaxElts = std::clamp<unsigned>(
          llvm::bit_floor(MaxVecRegSize / EltSize), RedValsMaxNumber,
          RegMaxNumber * RedValsMaxNumber);

      unsigned ReduxWidth = NumReducedVals;
      if (!VectorizeNonPowerOf2 || !has_single_bit(ReduxWidth + 1))
        ReduxWidth = bit_floor(ReduxWidth);
      ReduxWidth = std::min(ReduxWidth, MaxElts);

      unsigned Start = 0;
      unsigned Pos = Start;
      // Restarts vectorization attempt with lower vector factor.
      unsigned PrevReduxWidth = ReduxWidth;
      bool CheckForReusedReductionOpsLocal = false;
      auto &&AdjustReducedVals = [&Pos, &Start, &ReduxWidth, NumReducedVals,
                                  &CheckForReusedReductionOpsLocal,
                                  &PrevReduxWidth, &V,
                                  &IgnoreList](bool IgnoreVL = false) {
        bool IsAnyRedOpGathered = !IgnoreVL && V.isAnyGathered(IgnoreList);
        if (!CheckForReusedReductionOpsLocal && PrevReduxWidth == ReduxWidth) {
          // Check if any of the reduction ops are gathered. If so, worth
          // trying again with less number of reduction ops.
          CheckForReusedReductionOpsLocal |= IsAnyRedOpGathered;
        }
        ++Pos;
        if (Pos < NumReducedVals - ReduxWidth + 1)
          return IsAnyRedOpGathered;
        Pos = Start;
        ReduxWidth = bit_ceil(ReduxWidth) / 2;
        return IsAnyRedOpGathered;
      };
      bool AnyVectorized = false;
      while (Pos < NumReducedVals - ReduxWidth + 1 &&
             ReduxWidth >= ReductionLimit) {
        // Dependency in tree of the reduction ops - drop this attempt, try
        // later.
        if (CheckForReusedReductionOpsLocal && PrevReduxWidth != ReduxWidth &&
            Start == 0) {
          CheckForReusedReductionOps = true;
          break;
        }
        PrevReduxWidth = ReduxWidth;
        ArrayRef<Value *> VL(std::next(Candidates.begin(), Pos), ReduxWidth);
        // Beeing analyzed already - skip.
        if (V.areAnalyzedReductionVals(VL)) {
          (void)AdjustReducedVals(/*IgnoreVL=*/true);
          continue;
        }
        // Early exit if any of the reduction values were deleted during
        // previous vectorization attempts.
        if (any_of(VL, [&V](Value *RedVal) {
              auto *RedValI = dyn_cast<Instruction>(RedVal);
              if (!RedValI)
                return false;
              return V.isDeleted(RedValI);
            }))
          break;
        V.buildTree(VL, IgnoreList);
        if (V.isTreeTinyAndNotFullyVectorizable(/*ForReduction=*/true)) {
          if (!AdjustReducedVals())
            V.analyzedReductionVals(VL);
          continue;
        }
        if (V.isLoadCombineReductionCandidate(RdxKind)) {
          if (!AdjustReducedVals())
            V.analyzedReductionVals(VL);
          continue;
        }
        V.reorderTopToBottom();
        // No need to reorder the root node at all.
        V.reorderBottomToTop(/*IgnoreReorder=*/true);
        // Keep extracted other reduction values, if they are used in the
        // vectorization trees.
        BoUpSLP::ExtraValueToDebugLocsMap LocalExternallyUsedValues;
        // The reduction root is used as the insertion point for new
        // instructions, so set it as externally used to prevent it from being
        // deleted.
        LocalExternallyUsedValues[ReductionRoot];
        for (unsigned Cnt = 0, Sz = ReducedVals.size(); Cnt < Sz; ++Cnt) {
          if (Cnt == I || (ShuffledExtracts && Cnt == I - 1))
            continue;
          for (Value *V : ReducedVals[Cnt])
            if (isa<Instruction>(V))
              LocalExternallyUsedValues[TrackedVals[V]];
        }
        if (!IsSupportedHorRdxIdentityOp) {
          // Number of uses of the candidates in the vector of values.
          assert(SameValuesCounter.empty() &&
                 "Reused values counter map is not empty");
          for (unsigned Cnt = 0; Cnt < NumReducedVals; ++Cnt) {
            if (Cnt >= Pos && Cnt < Pos + ReduxWidth)
              continue;
            Value *V = Candidates[Cnt];
            Value *OrigV = TrackedToOrig.at(V);
            ++SameValuesCounter.try_emplace(OrigV).first->second;
          }
        }
        SmallPtrSet<Value *, 4> VLScalars(VL.begin(), VL.end());
        // Gather externally used values.
        SmallPtrSet<Value *, 4> Visited;
        for (unsigned Cnt = 0; Cnt < NumReducedVals; ++Cnt) {
          if (Cnt >= Pos && Cnt < Pos + ReduxWidth)
            continue;
          Value *RdxVal = Candidates[Cnt];
          if (auto It = TrackedVals.find(RdxVal); It != TrackedVals.end())
            RdxVal = It->second;
          if (!Visited.insert(RdxVal).second)
            continue;
          // Check if the scalar was vectorized as part of the vectorization
          // tree but not the top node.
          if (!VLScalars.contains(RdxVal) && V.isVectorized(RdxVal)) {
            LocalExternallyUsedValues[RdxVal];
            continue;
          }
          Value *OrigV = TrackedToOrig.at(RdxVal);
          unsigned NumOps =
              VectorizedVals.lookup(OrigV) + At(SameValuesCounter, OrigV);
          if (NumOps != ReducedValsToOps.at(OrigV).size())
            LocalExternallyUsedValues[RdxVal];
        }
        // Do not need the list of reused scalars in regular mode anymore.
        if (!IsSupportedHorRdxIdentityOp)
          SameValuesCounter.clear();
        for (Value *RdxVal : VL)
          if (RequiredExtract.contains(RdxVal))
            LocalExternallyUsedValues[RdxVal];
        V.transformNodes();
        V.buildExternalUses(LocalExternallyUsedValues);

        V.computeMinimumValueSizes();

        // Estimate cost.
        InstructionCost TreeCost = V.getTreeCost(VL);
        InstructionCost ReductionCost =
            getReductionCost(TTI, VL, IsCmpSelMinMax, ReduxWidth, RdxFMF);
        InstructionCost Cost = TreeCost + ReductionCost;
        LLVM_DEBUG(dbgs() << "SLP: Found cost = " << Cost
                          << " for reduction\n");
        if (!Cost.isValid())
          break;
        if (Cost >= -SLPCostThreshold) {
          V.getORE()->emit([&]() {
            return OptimizationRemarkMissed(SV_NAME, "HorSLPNotBeneficial",
                                            ReducedValsToOps.at(VL[0]).front())
                   << "Vectorizing horizontal reduction is possible "
                   << "but not beneficial with cost " << ore::NV("Cost", Cost)
                   << " and threshold "
                   << ore::NV("Threshold", -SLPCostThreshold);
          });
          if (!AdjustReducedVals())
            V.analyzedReductionVals(VL);
          continue;
        }

        LLVM_DEBUG(dbgs() << "SLP: Vectorizing horizontal reduction at cost:"
                          << Cost << ". (HorRdx)\n");
        V.getORE()->emit([&]() {
          return OptimizationRemark(SV_NAME, "VectorizedHorizontalReduction",
                                    ReducedValsToOps.at(VL[0]).front())
                 << "Vectorized horizontal reduction with cost "
                 << ore::NV("Cost", Cost) << " and with tree size "
                 << ore::NV("TreeSize", V.getTreeSize());
        });

        Builder.setFastMathFlags(RdxFMF);

        // Emit a reduction. If the root is a select (min/max idiom), the insert
        // point is the compare condition of that select.
        Instruction *RdxRootInst = cast<Instruction>(ReductionRoot);
        Instruction *InsertPt = RdxRootInst;
        if (IsCmpSelMinMax)
          InsertPt = GetCmpForMinMaxReduction(RdxRootInst);

        // Vectorize a tree.
        Value *VectorizedRoot =
            V.vectorizeTree(LocalExternallyUsedValues, InsertPt);
        // Update TrackedToOrig mapping, since the tracked values might be
        // updated.
        for (Value *RdxVal : Candidates) {
          Value *OrigVal = TrackedToOrig.at(RdxVal);
          Value *TransformedRdxVal = TrackedVals.at(OrigVal);
          if (TransformedRdxVal != RdxVal)
            TrackedToOrig.try_emplace(TransformedRdxVal, OrigVal);
        }

        Builder.SetInsertPoint(InsertPt);

        // To prevent poison from leaking across what used to be sequential,
        // safe, scalar boolean logic operations, the reduction operand must be
        // frozen.
        if ((isBoolLogicOp(RdxRootInst) ||
             (AnyBoolLogicOp && VL.size() != TrackedVals.size())) &&
            !isGuaranteedNotToBePoison(VectorizedRoot))
          VectorizedRoot = Builder.CreateFreeze(VectorizedRoot);

        // Emit code to correctly handle reused reduced values, if required.
        if (OptReusedScalars && !SameScaleFactor) {
          VectorizedRoot = emitReusedOps(VectorizedRoot, Builder, V,
                                         SameValuesCounter, TrackedToOrig);
        }

        Value *ReducedSubTree;
        Type *ScalarTy = VL.front()->getType();
        if (isa<FixedVectorType>(ScalarTy)) {
          assert(SLPReVec && "FixedVectorType is not expected.");
          unsigned ScalarTyNumElements = getNumElements(ScalarTy);
          ReducedSubTree = PoisonValue::get(FixedVectorType::get(
              VectorizedRoot->getType()->getScalarType(), ScalarTyNumElements));
          for (unsigned I : seq<unsigned>(ScalarTyNumElements)) {
            // Do reduction for each lane.
            // e.g., do reduce add for
            // VL[0] = <4 x Ty> <a, b, c, d>
            // VL[1] = <4 x Ty> <e, f, g, h>
            // Lane[0] = <2 x Ty> <a, e>
            // Lane[1] = <2 x Ty> <b, f>
            // Lane[2] = <2 x Ty> <c, g>
            // Lane[3] = <2 x Ty> <d, h>
            // result[0] = reduce add Lane[0]
            // result[1] = reduce add Lane[1]
            // result[2] = reduce add Lane[2]
            // result[3] = reduce add Lane[3]
            SmallVector<int, 16> Mask =
                createStrideMask(I, ScalarTyNumElements, VL.size());
            Value *Lane = Builder.CreateShuffleVector(VectorizedRoot, Mask);
            ReducedSubTree = Builder.CreateInsertElement(
                ReducedSubTree, emitReduction(Lane, Builder, TTI), I);
          }
        } else {
          ReducedSubTree = emitReduction(VectorizedRoot, Builder, TTI);
        }
        if (ReducedSubTree->getType() != VL.front()->getType()) {
          assert(ReducedSubTree->getType() != VL.front()->getType() &&
                 "Expected different reduction type.");
          ReducedSubTree =
              Builder.CreateIntCast(ReducedSubTree, VL.front()->getType(),
                                    V.isSignedMinBitwidthRootNode());
        }

        // Improved analysis for add/fadd/xor reductions with same scale factor
        // for all operands of reductions. We can emit scalar ops for them
        // instead.
        if (OptReusedScalars && SameScaleFactor)
          ReducedSubTree = emitScaleForReusedOps(
              ReducedSubTree, Builder, SameValuesCounter.front().second);

        VectorizedTree = GetNewVectorizedTree(VectorizedTree, ReducedSubTree);
        // Count vectorized reduced values to exclude them from final reduction.
        for (Value *RdxVal : VL) {
          Value *OrigV = TrackedToOrig.at(RdxVal);
          if (IsSupportedHorRdxIdentityOp) {
            VectorizedVals.try_emplace(OrigV, At(SameValuesCounter, OrigV));
            continue;
          }
          ++VectorizedVals.try_emplace(OrigV).first->getSecond();
          if (!V.isVectorized(RdxVal))
            RequiredExtract.insert(RdxVal);
        }
        Pos += ReduxWidth;
        Start = Pos;
        ReduxWidth = llvm::bit_floor(NumReducedVals - Pos);
        AnyVectorized = true;
      }
      if (OptReusedScalars && !AnyVectorized) {
        for (const std::pair<Value *, unsigned> &P : SameValuesCounter) {
          Value *RdxVal = TrackedVals.at(P.first);
          Value *RedVal = emitScaleForReusedOps(RdxVal, Builder, P.second);
          VectorizedTree = GetNewVectorizedTree(VectorizedTree, RedVal);
          VectorizedVals.try_emplace(P.first, P.second);
        }
        continue;
      }
    }
    if (VectorizedTree) {
      // Reorder operands of bool logical op in the natural order to avoid
      // possible problem with poison propagation. If not possible to reorder
      // (both operands are originally RHS), emit an extra freeze instruction
      // for the LHS operand.
      // I.e., if we have original code like this:
      // RedOp1 = select i1 ?, i1 LHS, i1 false
      // RedOp2 = select i1 RHS, i1 ?, i1 false

      // Then, we swap LHS/RHS to create a new op that matches the poison
      // semantics of the original code.

      // If we have original code like this and both values could be poison:
      // RedOp1 = select i1 ?, i1 LHS, i1 false
      // RedOp2 = select i1 ?, i1 RHS, i1 false

      // Then, we must freeze LHS in the new op.
      auto FixBoolLogicalOps = [&, VectorizedTree](Value *&LHS, Value *&RHS,
                                                   Instruction *RedOp1,
                                                   Instruction *RedOp2,
                                                   bool InitStep) {
        if (!AnyBoolLogicOp)
          return;
        if (isBoolLogicOp(RedOp1) &&
            ((!InitStep && LHS == VectorizedTree) ||
             getRdxOperand(RedOp1, 0) == LHS || isGuaranteedNotToBePoison(LHS)))
          return;
        if (isBoolLogicOp(RedOp2) && ((!InitStep && RHS == VectorizedTree) ||
                                      getRdxOperand(RedOp2, 0) == RHS ||
                                      isGuaranteedNotToBePoison(RHS))) {
          std::swap(LHS, RHS);
          return;
        }
        if (LHS != VectorizedTree)
          LHS = Builder.CreateFreeze(LHS);
      };
      // Finish the reduction.
      // Need to add extra arguments and not vectorized possible reduction
      // values.
      // Try to avoid dependencies between the scalar remainders after
      // reductions.
      auto FinalGen =
          [&](ArrayRef<std::pair<Instruction *, Value *>> InstVals,
              bool InitStep) {
            unsigned Sz = InstVals.size();
            SmallVector<std::pair<Instruction *, Value *>> ExtraReds(Sz / 2 +
                                                                     Sz % 2);
            for (unsigned I = 0, E = (Sz / 2) * 2; I < E; I += 2) {
              Instruction *RedOp = InstVals[I + 1].first;
              Builder.SetCurrentDebugLocation(RedOp->getDebugLoc());
              Value *RdxVal1 = InstVals[I].second;
              Value *StableRdxVal1 = RdxVal1;
              auto It1 = TrackedVals.find(RdxVal1);
              if (It1 != TrackedVals.end())
                StableRdxVal1 = It1->second;
              Value *RdxVal2 = InstVals[I + 1].second;
              Value *StableRdxVal2 = RdxVal2;
              auto It2 = TrackedVals.find(RdxVal2);
              if (It2 != TrackedVals.end())
                StableRdxVal2 = It2->second;
              // To prevent poison from leaking across what used to be
              // sequential, safe, scalar boolean logic operations, the
              // reduction operand must be frozen.
              FixBoolLogicalOps(StableRdxVal1, StableRdxVal2, InstVals[I].first,
                                RedOp, InitStep);
              Value *ExtraRed = createOp(Builder, RdxKind, StableRdxVal1,
                                         StableRdxVal2, "op.rdx", ReductionOps);
              ExtraReds[I / 2] = std::make_pair(InstVals[I].first, ExtraRed);
            }
            if (Sz % 2 == 1)
              ExtraReds[Sz / 2] = InstVals.back();
            return ExtraReds;
          };
      SmallVector<std::pair<Instruction *, Value *>> ExtraReductions;
      ExtraReductions.emplace_back(cast<Instruction>(ReductionRoot),
                                   VectorizedTree);
      SmallPtrSet<Value *, 8> Visited;
      for (ArrayRef<Value *> Candidates : ReducedVals) {
        for (Value *RdxVal : Candidates) {
          if (!Visited.insert(RdxVal).second)
            continue;
          unsigned NumOps = VectorizedVals.lookup(RdxVal);
          for (Instruction *RedOp :
               ArrayRef(ReducedValsToOps.at(RdxVal)).drop_back(NumOps))
            ExtraReductions.emplace_back(RedOp, RdxVal);
        }
      }
      // Iterate through all not-vectorized reduction values/extra arguments.
      bool InitStep = true;
      while (ExtraReductions.size() > 1) {
        SmallVector<std::pair<Instruction *, Value *>> NewReds =
            FinalGen(ExtraReductions, InitStep);
        ExtraReductions.swap(NewReds);
        InitStep = false;
      }
      VectorizedTree = ExtraReductions.front().second;

      ReductionRoot->replaceAllUsesWith(VectorizedTree);

      // The original scalar reduction is expected to have no remaining
      // uses outside the reduction tree itself.  Assert that we got this
      // correct, replace internal uses with undef, and mark for eventual
      // deletion.
#ifndef NDEBUG
      SmallSet<Value *, 4> IgnoreSet;
      for (ArrayRef<Value *> RdxOps : ReductionOps)
        IgnoreSet.insert(RdxOps.begin(), RdxOps.end());
#endif
      for (ArrayRef<Value *> RdxOps : ReductionOps) {
        for (Value *Ignore : RdxOps) {
          if (!Ignore)
            continue;
#ifndef NDEBUG
          for (auto *U : Ignore->users()) {
            assert(IgnoreSet.count(U) &&
                   "All users must be either in the reduction ops list.");
          }
#endif
          if (!Ignore->use_empty()) {
            Value *P = PoisonValue::get(Ignore->getType());
            Ignore->replaceAllUsesWith(P);
          }
        }
        V.removeInstructionsAndOperands(RdxOps);
      }
    } else if (!CheckForReusedReductionOps) {
      for (ReductionOpsType &RdxOps : ReductionOps)
        for (Value *RdxOp : RdxOps)
          V.analyzedReductionRoot(cast<Instruction>(RdxOp));
    }
    return VectorizedTree;
  }

private:
  /// Calculate the cost of a reduction.
  InstructionCost getReductionCost(TargetTransformInfo *TTI,
                                   ArrayRef<Value *> ReducedVals,
                                   bool IsCmpSelMinMax, unsigned ReduxWidth,
                                   FastMathFlags FMF) {
    TTI::TargetCostKind CostKind = TTI::TCK_RecipThroughput;
    Type *ScalarTy = ReducedVals.front()->getType();
    FixedVectorType *VectorTy = getWidenedType(ScalarTy, ReduxWidth);
    InstructionCost VectorCost = 0, ScalarCost;
    // If all of the reduced values are constant, the vector cost is 0, since
    // the reduction value can be calculated at the compile time.
    bool AllConsts = allConstant(ReducedVals);
    auto EvaluateScalarCost = [&](function_ref<InstructionCost()> GenCostFn) {
      InstructionCost Cost = 0;
      // Scalar cost is repeated for N-1 elements.
      int Cnt = ReducedVals.size();
      for (Value *RdxVal : ReducedVals) {
        if (Cnt == 1)
          break;
        --Cnt;
        if (RdxVal->hasNUsesOrMore(IsCmpSelMinMax ? 3 : 2)) {
          Cost += GenCostFn();
          continue;
        }
        InstructionCost ScalarCost = 0;
        for (User *U : RdxVal->users()) {
          auto *RdxOp = cast<Instruction>(U);
          if (hasRequiredNumberOfUses(IsCmpSelMinMax, RdxOp)) {
            ScalarCost += TTI->getInstructionCost(RdxOp, CostKind);
            continue;
          }
          ScalarCost = InstructionCost::getInvalid();
          break;
        }
        if (ScalarCost.isValid())
          Cost += ScalarCost;
        else
          Cost += GenCostFn();
      }
      return Cost;
    };
    switch (RdxKind) {
    case RecurKind::Add:
    case RecurKind::Mul:
    case RecurKind::Or:
    case RecurKind::And:
    case RecurKind::Xor:
    case RecurKind::FAdd:
    case RecurKind::FMul: {
      unsigned RdxOpcode = RecurrenceDescriptor::getOpcode(RdxKind);
      if (!AllConsts) {
        if (auto *VecTy = dyn_cast<FixedVectorType>(ScalarTy)) {
          assert(SLPReVec && "FixedVectorType is not expected.");
          unsigned ScalarTyNumElements = VecTy->getNumElements();
          for (unsigned I : seq<unsigned>(ReducedVals.size())) {
            VectorCost += TTI->getShuffleCost(
                TTI::SK_PermuteSingleSrc, VectorTy,
                createStrideMask(I, ScalarTyNumElements, ReducedVals.size()));
            VectorCost += TTI->getArithmeticReductionCost(RdxOpcode, VecTy, FMF,
                                                          CostKind);
          }
          VectorCost += TTI->getScalarizationOverhead(
              VecTy, APInt::getAllOnes(ScalarTyNumElements), /*Insert*/ true,
              /*Extract*/ false, TTI::TCK_RecipThroughput);
        } else {
          VectorCost = TTI->getArithmeticReductionCost(RdxOpcode, VectorTy, FMF,
                                                       CostKind);
        }
      }
      ScalarCost = EvaluateScalarCost([&]() {
        return TTI->getArithmeticInstrCost(RdxOpcode, ScalarTy, CostKind);
      });
      break;
    }
    case RecurKind::FMax:
    case RecurKind::FMin:
    case RecurKind::FMaximum:
    case RecurKind::FMinimum:
    case RecurKind::SMax:
    case RecurKind::SMin:
    case RecurKind::UMax:
    case RecurKind::UMin: {
      Intrinsic::ID Id = getMinMaxReductionIntrinsicOp(RdxKind);
      if (!AllConsts)
        VectorCost = TTI->getMinMaxReductionCost(Id, VectorTy, FMF, CostKind);
      ScalarCost = EvaluateScalarCost([&]() {
        IntrinsicCostAttributes ICA(Id, ScalarTy, {ScalarTy, ScalarTy}, FMF);
        return TTI->getIntrinsicInstrCost(ICA, CostKind);
      });
      break;
    }
    default:
      llvm_unreachable("Expected arithmetic or min/max reduction operation");
    }

    LLVM_DEBUG(dbgs() << "SLP: Adding cost " << VectorCost - ScalarCost
                      << " for reduction of " << shortBundleName(ReducedVals)
                      << " (It is a splitting reduction)\n");
    return VectorCost - ScalarCost;
  }

  /// Emit a horizontal reduction of the vectorized value.
  Value *emitReduction(Value *VectorizedValue, IRBuilderBase &Builder,
                       const TargetTransformInfo *TTI) {
    assert(VectorizedValue && "Need to have a vectorized tree node");
    assert(RdxKind != RecurKind::FMulAdd &&
           "A call to the llvm.fmuladd intrinsic is not handled yet");

    ++NumVectorInstructions;
    return createSimpleReduction(Builder, VectorizedValue, RdxKind);
  }

  /// Emits optimized code for unique scalar value reused \p Cnt times.
  Value *emitScaleForReusedOps(Value *VectorizedValue, IRBuilderBase &Builder,
                               unsigned Cnt) {
    assert(IsSupportedHorRdxIdentityOp &&
           "The optimization of matched scalar identity horizontal reductions "
           "must be supported.");
    if (Cnt == 1)
      return VectorizedValue;
    switch (RdxKind) {
    case RecurKind::Add: {
      // res = mul vv, n
      Value *Scale = ConstantInt::get(VectorizedValue->getType(), Cnt);
      LLVM_DEBUG(dbgs() << "SLP: Add (to-mul) " << Cnt << "of "
                        << VectorizedValue << ". (HorRdx)\n");
      return Builder.CreateMul(VectorizedValue, Scale);
    }
    case RecurKind::Xor: {
      // res = n % 2 ? 0 : vv
      LLVM_DEBUG(dbgs() << "SLP: Xor " << Cnt << "of " << VectorizedValue
                        << ". (HorRdx)\n");
      if (Cnt % 2 == 0)
        return Constant::getNullValue(VectorizedValue->getType());
      return VectorizedValue;
    }
    case RecurKind::FAdd: {
      // res = fmul v, n
      Value *Scale = ConstantFP::get(VectorizedValue->getType(), Cnt);
      LLVM_DEBUG(dbgs() << "SLP: FAdd (to-fmul) " << Cnt << "of "
                        << VectorizedValue << ". (HorRdx)\n");
      return Builder.CreateFMul(VectorizedValue, Scale);
    }
    case RecurKind::And:
    case RecurKind::Or:
    case RecurKind::SMax:
    case RecurKind::SMin:
    case RecurKind::UMax:
    case RecurKind::UMin:
    case RecurKind::FMax:
    case RecurKind::FMin:
    case RecurKind::FMaximum:
    case RecurKind::FMinimum:
      // res = vv
      return VectorizedValue;
    case RecurKind::Mul:
    case RecurKind::FMul:
    case RecurKind::FMulAdd:
    case RecurKind::IAnyOf:
    case RecurKind::FAnyOf:
    case RecurKind::None:
      llvm_unreachable("Unexpected reduction kind for repeated scalar.");
    }
    return nullptr;
  }

  /// Emits actual operation for the scalar identity values, found during
  /// horizontal reduction analysis.
  Value *emitReusedOps(Value *VectorizedValue, IRBuilderBase &Builder,
                       BoUpSLP &R,
                       const MapVector<Value *, unsigned> &SameValuesCounter,
                       const DenseMap<Value *, Value *> &TrackedToOrig) {
    assert(IsSupportedHorRdxIdentityOp &&
           "The optimization of matched scalar identity horizontal reductions "
           "must be supported.");
    ArrayRef<Value *> VL = R.getRootNodeScalars();
    auto *VTy = cast<FixedVectorType>(VectorizedValue->getType());
    if (VTy->getElementType() != VL.front()->getType()) {
      VectorizedValue = Builder.CreateIntCast(
          VectorizedValue,
          getWidenedType(VL.front()->getType(), VTy->getNumElements()),
          R.isSignedMinBitwidthRootNode());
    }
    switch (RdxKind) {
    case RecurKind::Add: {
      // root = mul prev_root, <1, 1, n, 1>
      SmallVector<Constant *> Vals;
      for (Value *V : VL) {
        unsigned Cnt = SameValuesCounter.lookup(TrackedToOrig.at(V));
        Vals.push_back(ConstantInt::get(V->getType(), Cnt, /*IsSigned=*/false));
      }
      auto *Scale = ConstantVector::get(Vals);
      LLVM_DEBUG(dbgs() << "SLP: Add (to-mul) " << Scale << "of "
                        << VectorizedValue << ". (HorRdx)\n");
      return Builder.CreateMul(VectorizedValue, Scale);
    }
    case RecurKind::And:
    case RecurKind::Or:
      // No need for multiple or/and(s).
      LLVM_DEBUG(dbgs() << "SLP: And/or of same " << VectorizedValue
                        << ". (HorRdx)\n");
      return VectorizedValue;
    case RecurKind::SMax:
    case RecurKind::SMin:
    case RecurKind::UMax:
    case RecurKind::UMin:
    case RecurKind::FMax:
    case RecurKind::FMin:
    case RecurKind::FMaximum:
    case RecurKind::FMinimum:
      // No need for multiple min/max(s) of the same value.
      LLVM_DEBUG(dbgs() << "SLP: Max/min of same " << VectorizedValue
                        << ". (HorRdx)\n");
      return VectorizedValue;
    case RecurKind::Xor: {
      // Replace values with even number of repeats with 0, since
      // x xor x = 0.
      // root = shuffle prev_root, zeroinitalizer, <0, 1, 2, vf, 4, vf, 5, 6,
      // 7>, if elements 4th and 6th elements have even number of repeats.
      SmallVector<int> Mask(
          cast<FixedVectorType>(VectorizedValue->getType())->getNumElements(),
          PoisonMaskElem);
      std::iota(Mask.begin(), Mask.end(), 0);
      bool NeedShuffle = false;
      for (unsigned I = 0, VF = VL.size(); I < VF; ++I) {
        Value *V = VL[I];
        unsigned Cnt = SameValuesCounter.lookup(TrackedToOrig.at(V));
        if (Cnt % 2 == 0) {
          Mask[I] = VF;
          NeedShuffle = true;
        }
      }
      LLVM_DEBUG(dbgs() << "SLP: Xor <"; for (int I
                                              : Mask) dbgs()
                                         << I << " ";
                 dbgs() << "> of " << VectorizedValue << ". (HorRdx)\n");
      if (NeedShuffle)
        VectorizedValue = Builder.CreateShuffleVector(
            VectorizedValue,
            ConstantVector::getNullValue(VectorizedValue->getType()), Mask);
      return VectorizedValue;
    }
    case RecurKind::FAdd: {
      // root = fmul prev_root, <1.0, 1.0, n.0, 1.0>
      SmallVector<Constant *> Vals;
      for (Value *V : VL) {
        unsigned Cnt = SameValuesCounter.lookup(TrackedToOrig.at(V));
        Vals.push_back(ConstantFP::get(V->getType(), Cnt));
      }
      auto *Scale = ConstantVector::get(Vals);
      return Builder.CreateFMul(VectorizedValue, Scale);
    }
    case RecurKind::Mul:
    case RecurKind::FMul:
    case RecurKind::FMulAdd:
    case RecurKind::IAnyOf:
    case RecurKind::FAnyOf:
    case RecurKind::None:
      llvm_unreachable("Unexpected reduction kind for reused scalars.");
    }
    return nullptr;
  }
};
} // end anonymous namespace

/// Gets recurrence kind from the specified value.
static RecurKind getRdxKind(Value *V) {
  return HorizontalReduction::getRdxKind(V);
}
static std::optional<unsigned> getAggregateSize(Instruction *InsertInst) {
  if (auto *IE = dyn_cast<InsertElementInst>(InsertInst))
    return cast<FixedVectorType>(IE->getType())->getNumElements();

  unsigned AggregateSize = 1;
  auto *IV = cast<InsertValueInst>(InsertInst);
  Type *CurrentType = IV->getType();
  do {
    if (auto *ST = dyn_cast<StructType>(CurrentType)) {
      for (auto *Elt : ST->elements())
        if (Elt != ST->getElementType(0)) // check homogeneity
          return std::nullopt;
      AggregateSize *= ST->getNumElements();
      CurrentType = ST->getElementType(0);
    } else if (auto *AT = dyn_cast<ArrayType>(CurrentType)) {
      AggregateSize *= AT->getNumElements();
      CurrentType = AT->getElementType();
    } else if (auto *VT = dyn_cast<FixedVectorType>(CurrentType)) {
      AggregateSize *= VT->getNumElements();
      return AggregateSize;
    } else if (CurrentType->isSingleValueType()) {
      return AggregateSize;
    } else {
      return std::nullopt;
    }
  } while (true);
}

static void findBuildAggregate_rec(Instruction *LastInsertInst,
                                   TargetTransformInfo *TTI,
                                   SmallVectorImpl<Value *> &BuildVectorOpds,
                                   SmallVectorImpl<Value *> &InsertElts,
                                   unsigned OperandOffset) {
  do {
    Value *InsertedOperand = LastInsertInst->getOperand(1);
    std::optional<unsigned> OperandIndex =
        getElementIndex(LastInsertInst, OperandOffset);
    if (!OperandIndex)
      return;
    if (isa<InsertElementInst, InsertValueInst>(InsertedOperand)) {
      findBuildAggregate_rec(cast<Instruction>(InsertedOperand), TTI,
                             BuildVectorOpds, InsertElts, *OperandIndex);

    } else {
      BuildVectorOpds[*OperandIndex] = InsertedOperand;
      InsertElts[*OperandIndex] = LastInsertInst;
    }
    LastInsertInst = dyn_cast<Instruction>(LastInsertInst->getOperand(0));
  } while (LastInsertInst != nullptr &&
           isa<InsertValueInst, InsertElementInst>(LastInsertInst) &&
           LastInsertInst->hasOneUse());
}

/// Recognize construction of vectors like
///  %ra = insertelement <4 x float> poison, float %s0, i32 0
///  %rb = insertelement <4 x float> %ra, float %s1, i32 1
///  %rc = insertelement <4 x float> %rb, float %s2, i32 2
///  %rd = insertelement <4 x float> %rc, float %s3, i32 3
///  starting from the last insertelement or insertvalue instruction.
///
/// Also recognize homogeneous aggregates like {<2 x float>, <2 x float>},
/// {{float, float}, {float, float}}, [2 x {float, float}] and so on.
/// See llvm/test/Transforms/SLPVectorizer/X86/pr42022.ll for examples.
///
/// Assume LastInsertInst is of InsertElementInst or InsertValueInst type.
///
/// \return true if it matches.
static bool findBuildAggregate(Instruction *LastInsertInst,
                               TargetTransformInfo *TTI,
                               SmallVectorImpl<Value *> &BuildVectorOpds,
                               SmallVectorImpl<Value *> &InsertElts) {

  assert((isa<InsertElementInst>(LastInsertInst) ||
          isa<InsertValueInst>(LastInsertInst)) &&
         "Expected insertelement or insertvalue instruction!");

  assert((BuildVectorOpds.empty() && InsertElts.empty()) &&
         "Expected empty result vectors!");

  std::optional<unsigned> AggregateSize = getAggregateSize(LastInsertInst);
  if (!AggregateSize)
    return false;
  BuildVectorOpds.resize(*AggregateSize);
  InsertElts.resize(*AggregateSize);

  findBuildAggregate_rec(LastInsertInst, TTI, BuildVectorOpds, InsertElts, 0);
  llvm::erase(BuildVectorOpds, nullptr);
  llvm::erase(InsertElts, nullptr);
  if (BuildVectorOpds.size() >= 2)
    return true;

  return false;
}

/// Try and get a reduction instruction from a phi node.
///
/// Given a phi node \p P in a block \p ParentBB, consider possible reductions
/// if they come from either \p ParentBB or a containing loop latch.
///
/// \returns A candidate reduction value if possible, or \code nullptr \endcode
/// if not possible.
static Instruction *getReductionInstr(const DominatorTree *DT, PHINode *P,
                                      BasicBlock *ParentBB, LoopInfo *LI) {
  // There are situations where the reduction value is not dominated by the
  // reduction phi. Vectorizing such cases has been reported to cause
  // miscompiles. See PR25787.
  auto DominatedReduxValue = [&](Value *R) {
    return isa<Instruction>(R) &&
           DT->dominates(P->getParent(), cast<Instruction>(R)->getParent());
  };

  Instruction *Rdx = nullptr;

  // Return the incoming value if it comes from the same BB as the phi node.
  if (P->getIncomingBlock(0) == ParentBB) {
    Rdx = dyn_cast<Instruction>(P->getIncomingValue(0));
  } else if (P->getIncomingBlock(1) == ParentBB) {
    Rdx = dyn_cast<Instruction>(P->getIncomingValue(1));
  }

  if (Rdx && DominatedReduxValue(Rdx))
    return Rdx;

  // Otherwise, check whether we have a loop latch to look at.
  Loop *BBL = LI->getLoopFor(ParentBB);
  if (!BBL)
    return nullptr;
  BasicBlock *BBLatch = BBL->getLoopLatch();
  if (!BBLatch)
    return nullptr;

  // There is a loop latch, return the incoming value if it comes from
  // that. This reduction pattern occasionally turns up.
  if (P->getIncomingBlock(0) == BBLatch) {
    Rdx = dyn_cast<Instruction>(P->getIncomingValue(0));
  } else if (P->getIncomingBlock(1) == BBLatch) {
    Rdx = dyn_cast<Instruction>(P->getIncomingValue(1));
  }

  if (Rdx && DominatedReduxValue(Rdx))
    return Rdx;

  return nullptr;
}

static bool matchRdxBop(Instruction *I, Value *&V0, Value *&V1) {
  if (match(I, m_BinOp(m_Value(V0), m_Value(V1))))
    return true;
  if (match(I, m_Intrinsic<Intrinsic::maxnum>(m_Value(V0), m_Value(V1))))
    return true;
  if (match(I, m_Intrinsic<Intrinsic::minnum>(m_Value(V0), m_Value(V1))))
    return true;
  if (match(I, m_Intrinsic<Intrinsic::maximum>(m_Value(V0), m_Value(V1))))
    return true;
  if (match(I, m_Intrinsic<Intrinsic::minimum>(m_Value(V0), m_Value(V1))))
    return true;
  if (match(I, m_Intrinsic<Intrinsic::smax>(m_Value(V0), m_Value(V1))))
    return true;
  if (match(I, m_Intrinsic<Intrinsic::smin>(m_Value(V0), m_Value(V1))))
    return true;
  if (match(I, m_Intrinsic<Intrinsic::umax>(m_Value(V0), m_Value(V1))))
    return true;
  if (match(I, m_Intrinsic<Intrinsic::umin>(m_Value(V0), m_Value(V1))))
    return true;
  return false;
}

/// We could have an initial reduction that is not an add.
///  r *= v1 + v2 + v3 + v4
/// In such a case start looking for a tree rooted in the first '+'.
/// \Returns the new root if found, which may be nullptr if not an instruction.
static Instruction *tryGetSecondaryReductionRoot(PHINode *Phi,
                                                 Instruction *Root) {
  assert((isa<BinaryOperator>(Root) || isa<SelectInst>(Root) ||
          isa<IntrinsicInst>(Root)) &&
         "Expected binop, select, or intrinsic for reduction matching");
  Value *LHS =
      Root->getOperand(HorizontalReduction::getFirstOperandIndex(Root));
  Value *RHS =
      Root->getOperand(HorizontalReduction::getFirstOperandIndex(Root) + 1);
  if (LHS == Phi)
    return dyn_cast<Instruction>(RHS);
  if (RHS == Phi)
    return dyn_cast<Instruction>(LHS);
  return nullptr;
}

/// \p Returns the first operand of \p I that does not match \p Phi. If
/// operand is not an instruction it returns nullptr.
static Instruction *getNonPhiOperand(Instruction *I, PHINode *Phi) {
  Value *Op0 = nullptr;
  Value *Op1 = nullptr;
  if (!matchRdxBop(I, Op0, Op1))
    return nullptr;
  return dyn_cast<Instruction>(Op0 == Phi ? Op1 : Op0);
}

/// \Returns true if \p I is a candidate instruction for reduction vectorization.
static bool isReductionCandidate(Instruction *I) {
  bool IsSelect = match(I, m_Select(m_Value(), m_Value(), m_Value()));
  Value *B0 = nullptr, *B1 = nullptr;
  bool IsBinop = matchRdxBop(I, B0, B1);
  return IsBinop || IsSelect;
}

bool SLPVectorizerPass::vectorizeHorReduction(
    PHINode *P, Instruction *Root, BasicBlock *BB, BoUpSLP &R, TargetTransformInfo *TTI,
    SmallVectorImpl<WeakTrackingVH> &PostponedInsts) {
  if (!ShouldVectorizeHor)
    return false;
  bool TryOperandsAsNewSeeds = P && isa<BinaryOperator>(Root);

  if (Root->getParent() != BB || isa<PHINode>(Root))
    return false;

  // If we can find a secondary reduction root, use that instead.
  auto SelectRoot = [&]() {
    if (TryOperandsAsNewSeeds && isReductionCandidate(Root) &&
        HorizontalReduction::getRdxKind(Root) != RecurKind::None)
      if (Instruction *NewRoot = tryGetSecondaryReductionRoot(P, Root))
        return NewRoot;
    return Root;
  };

  // Start analysis starting from Root instruction. If horizontal reduction is
  // found, try to vectorize it. If it is not a horizontal reduction or
  // vectorization is not possible or not effective, and currently analyzed
  // instruction is a binary operation, try to vectorize the operands, using
  // pre-order DFS traversal order. If the operands were not vectorized, repeat
  // the same procedure considering each operand as a possible root of the
  // horizontal reduction.
  // Interrupt the process if the Root instruction itself was vectorized or all
  // sub-trees not higher that RecursionMaxDepth were analyzed/vectorized.
  // If a horizintal reduction was not matched or vectorized we collect
  // instructions for possible later attempts for vectorization.
  std::queue<std::pair<Instruction *, unsigned>> Stack;
  Stack.emplace(SelectRoot(), 0);
  SmallPtrSet<Value *, 8> VisitedInstrs;
  bool Res = false;
  auto &&TryToReduce = [this, TTI, &R](Instruction *Inst) -> Value * {
    if (R.isAnalyzedReductionRoot(Inst))
      return nullptr;
    if (!isReductionCandidate(Inst))
      return nullptr;
    HorizontalReduction HorRdx;
    if (!HorRdx.matchAssociativeReduction(R, Inst, *SE, *DL, *TLI))
      return nullptr;
    return HorRdx.tryToReduce(R, *DL, TTI, *TLI);
  };
  auto TryAppendToPostponedInsts = [&](Instruction *FutureSeed) {
    if (TryOperandsAsNewSeeds && FutureSeed == Root) {
      FutureSeed = getNonPhiOperand(Root, P);
      if (!FutureSeed)
        return false;
    }
    // Do not collect CmpInst or InsertElementInst/InsertValueInst as their
    // analysis is done separately.
    if (!isa<CmpInst, InsertElementInst, InsertValueInst>(FutureSeed))
      PostponedInsts.push_back(FutureSeed);
    return true;
  };

  while (!Stack.empty()) {
    Instruction *Inst;
    unsigned Level;
    std::tie(Inst, Level) = Stack.front();
    Stack.pop();
    // Do not try to analyze instruction that has already been vectorized.
    // This may happen when we vectorize instruction operands on a previous
    // iteration while stack was populated before that happened.
    if (R.isDeleted(Inst))
      continue;
    if (Value *VectorizedV = TryToReduce(Inst)) {
      Res = true;
      if (auto *I = dyn_cast<Instruction>(VectorizedV)) {
        // Try to find another reduction.
        Stack.emplace(I, Level);
        continue;
      }
      if (R.isDeleted(Inst))
        continue;
    } else {
      // We could not vectorize `Inst` so try to use it as a future seed.
      if (!TryAppendToPostponedInsts(Inst)) {
        assert(Stack.empty() && "Expected empty stack");
        break;
      }
    }

    // Try to vectorize operands.
    // Continue analysis for the instruction from the same basic block only to
    // save compile time.
    if (++Level < RecursionMaxDepth)
      for (auto *Op : Inst->operand_values())
        if (VisitedInstrs.insert(Op).second)
          if (auto *I = dyn_cast<Instruction>(Op))
            // Do not try to vectorize CmpInst operands,  this is done
            // separately.
            if (!isa<PHINode, CmpInst, InsertElementInst, InsertValueInst>(I) &&
                !R.isDeleted(I) && I->getParent() == BB)
              Stack.emplace(I, Level);
  }
  return Res;
}

bool SLPVectorizerPass::vectorizeRootInstruction(PHINode *P, Instruction *Root,
                                                 BasicBlock *BB, BoUpSLP &R,
                                                 TargetTransformInfo *TTI) {
  SmallVector<WeakTrackingVH> PostponedInsts;
  bool Res = vectorizeHorReduction(P, Root, BB, R, TTI, PostponedInsts);
  Res |= tryToVectorize(PostponedInsts, R);
  return Res;
}

bool SLPVectorizerPass::tryToVectorize(ArrayRef<WeakTrackingVH> Insts,
                                       BoUpSLP &R) {
  bool Res = false;
  for (Value *V : Insts)
    if (auto *Inst = dyn_cast<Instruction>(V); Inst && !R.isDeleted(Inst))
      Res |= tryToVectorize(Inst, R);
  return Res;
}

bool SLPVectorizerPass::vectorizeInsertValueInst(InsertValueInst *IVI,
                                                 BasicBlock *BB, BoUpSLP &R,
                                                 bool MaxVFOnly) {
  if (!R.canMapToVector(IVI->getType()))
    return false;

  SmallVector<Value *, 16> BuildVectorOpds;
  SmallVector<Value *, 16> BuildVectorInsts;
  if (!findBuildAggregate(IVI, TTI, BuildVectorOpds, BuildVectorInsts))
    return false;

  if (MaxVFOnly && BuildVectorOpds.size() == 2) {
    R.getORE()->emit([&]() {
      return OptimizationRemarkMissed(SV_NAME, "NotPossible", IVI)
             << "Cannot SLP vectorize list: only 2 elements of buildvalue, "
                "trying reduction first.";
    });
    return false;
  }
  LLVM_DEBUG(dbgs() << "SLP: array mappable to vector: " << *IVI << "\n");
  // Aggregate value is unlikely to be processed in vector register.
  return tryToVectorizeList(BuildVectorOpds, R, MaxVFOnly);
}

bool SLPVectorizerPass::vectorizeInsertElementInst(InsertElementInst *IEI,
                                                   BasicBlock *BB, BoUpSLP &R,
                                                   bool MaxVFOnly) {
  SmallVector<Value *, 16> BuildVectorInsts;
  SmallVector<Value *, 16> BuildVectorOpds;
  SmallVector<int> Mask;
  if (!findBuildAggregate(IEI, TTI, BuildVectorOpds, BuildVectorInsts) ||
      (llvm::all_of(BuildVectorOpds, IsaPred<ExtractElementInst, UndefValue>) &&
       isFixedVectorShuffle(BuildVectorOpds, Mask)))
    return false;

  if (MaxVFOnly && BuildVectorInsts.size() == 2) {
    R.getORE()->emit([&]() {
      return OptimizationRemarkMissed(SV_NAME, "NotPossible", IEI)
             << "Cannot SLP vectorize list: only 2 elements of buildvector, "
                "trying reduction first.";
    });
    return false;
  }
  LLVM_DEBUG(dbgs() << "SLP: array mappable to vector: " << *IEI << "\n");
  return tryToVectorizeList(BuildVectorInsts, R, MaxVFOnly);
}

template <typename T>
static bool tryToVectorizeSequence(
    SmallVectorImpl<T *> &Incoming, function_ref<bool(T *, T *)> Comparator,
    function_ref<bool(T *, T *)> AreCompatible,
    function_ref<bool(ArrayRef<T *>, bool)> TryToVectorizeHelper,
    bool MaxVFOnly, BoUpSLP &R) {
  bool Changed = false;
  // Sort by type, parent, operands.
  stable_sort(Incoming, Comparator);

  // Try to vectorize elements base on their type.
  SmallVector<T *> Candidates;
  SmallVector<T *> VL;
  for (auto *IncIt = Incoming.begin(), *E = Incoming.end(); IncIt != E;
       VL.clear()) {
    // Look for the next elements with the same type, parent and operand
    // kinds.
    auto *I = dyn_cast<Instruction>(*IncIt);
    if (!I || R.isDeleted(I)) {
      ++IncIt;
      continue;
    }
    auto *SameTypeIt = IncIt;
    while (SameTypeIt != E && (!isa<Instruction>(*SameTypeIt) ||
                               R.isDeleted(cast<Instruction>(*SameTypeIt)) ||
                               AreCompatible(*SameTypeIt, *IncIt))) {
      auto *I = dyn_cast<Instruction>(*SameTypeIt);
      ++SameTypeIt;
      if (I && !R.isDeleted(I))
        VL.push_back(cast<T>(I));
    }

    // Try to vectorize them.
    unsigned NumElts = VL.size();
    LLVM_DEBUG(dbgs() << "SLP: Trying to vectorize starting at nodes ("
                      << NumElts << ")\n");
    // The vectorization is a 3-state attempt:
    // 1. Try to vectorize instructions with the same/alternate opcodes with the
    // size of maximal register at first.
    // 2. Try to vectorize remaining instructions with the same type, if
    // possible. This may result in the better vectorization results rather than
    // if we try just to vectorize instructions with the same/alternate opcodes.
    // 3. Final attempt to try to vectorize all instructions with the
    // same/alternate ops only, this may result in some extra final
    // vectorization.
    if (NumElts > 1 && TryToVectorizeHelper(ArrayRef(VL), MaxVFOnly)) {
      // Success start over because instructions might have been changed.
      Changed = true;
      VL.swap(Candidates);
      Candidates.clear();
      for (T *V : VL) {
        if (auto *I = dyn_cast<Instruction>(V); I && !R.isDeleted(I))
          Candidates.push_back(V);
      }
    } else {
      /// \Returns the minimum number of elements that we will attempt to
      /// vectorize.
      auto GetMinNumElements = [&R](Value *V) {
        unsigned EltSize = R.getVectorElementSize(V);
        return std::max(2U, R.getMaxVecRegSize() / EltSize);
      };
      if (NumElts < GetMinNumElements(*IncIt) &&
          (Candidates.empty() ||
           Candidates.front()->getType() == (*IncIt)->getType())) {
        for (T *V : VL) {
          if (auto *I = dyn_cast<Instruction>(V); I && !R.isDeleted(I))
            Candidates.push_back(V);
        }
      }
    }
    // Final attempt to vectorize instructions with the same types.
    if (Candidates.size() > 1 &&
        (SameTypeIt == E || (*SameTypeIt)->getType() != (*IncIt)->getType())) {
      if (TryToVectorizeHelper(Candidates, /*MaxVFOnly=*/false)) {
        // Success start over because instructions might have been changed.
        Changed = true;
      } else if (MaxVFOnly) {
        // Try to vectorize using small vectors.
        SmallVector<T *> VL;
        for (auto *It = Candidates.begin(), *End = Candidates.end(); It != End;
             VL.clear()) {
          auto *I = dyn_cast<Instruction>(*It);
          if (!I || R.isDeleted(I)) {
            ++It;
            continue;
          }
          auto *SameTypeIt = It;
          while (SameTypeIt != End &&
                 (!isa<Instruction>(*SameTypeIt) ||
                  R.isDeleted(cast<Instruction>(*SameTypeIt)) ||
                  AreCompatible(*SameTypeIt, *It))) {
            auto *I = dyn_cast<Instruction>(*SameTypeIt);
            ++SameTypeIt;
            if (I && !R.isDeleted(I))
              VL.push_back(cast<T>(I));
          }
          unsigned NumElts = VL.size();
          if (NumElts > 1 && TryToVectorizeHelper(ArrayRef(VL),
                                                  /*MaxVFOnly=*/false))
            Changed = true;
          It = SameTypeIt;
        }
      }
      Candidates.clear();
    }

    // Start over at the next instruction of a different type (or the end).
    IncIt = SameTypeIt;
  }
  return Changed;
}

/// Compare two cmp instructions. If IsCompatibility is true, function returns
/// true if 2 cmps have same/swapped predicates and mos compatible corresponding
/// operands. If IsCompatibility is false, function implements strict weak
/// ordering relation between two cmp instructions, returning true if the first
/// instruction is "less" than the second, i.e. its predicate is less than the
/// predicate of the second or the operands IDs are less than the operands IDs
/// of the second cmp instruction.
template <bool IsCompatibility>
static bool compareCmp(Value *V, Value *V2, TargetLibraryInfo &TLI,
                       const DominatorTree &DT) {
  assert(isValidElementType(V->getType()) &&
         isValidElementType(V2->getType()) &&
         "Expected valid element types only.");
  if (V == V2)
    return IsCompatibility;
  auto *CI1 = cast<CmpInst>(V);
  auto *CI2 = cast<CmpInst>(V2);
  if (CI1->getOperand(0)->getType()->getTypeID() <
      CI2->getOperand(0)->getType()->getTypeID())
    return !IsCompatibility;
  if (CI1->getOperand(0)->getType()->getTypeID() >
      CI2->getOperand(0)->getType()->getTypeID())
    return false;
  if (CI1->getOperand(0)->getType()->getScalarSizeInBits() <
      CI2->getOperand(0)->getType()->getScalarSizeInBits())
    return !IsCompatibility;
  if (CI1->getOperand(0)->getType()->getScalarSizeInBits() >
      CI2->getOperand(0)->getType()->getScalarSizeInBits())
    return false;
  CmpInst::Predicate Pred1 = CI1->getPredicate();
  CmpInst::Predicate Pred2 = CI2->getPredicate();
  CmpInst::Predicate SwapPred1 = CmpInst::getSwappedPredicate(Pred1);
  CmpInst::Predicate SwapPred2 = CmpInst::getSwappedPredicate(Pred2);
  CmpInst::Predicate BasePred1 = std::min(Pred1, SwapPred1);
  CmpInst::Predicate BasePred2 = std::min(Pred2, SwapPred2);
  if (BasePred1 < BasePred2)
    return !IsCompatibility;
  if (BasePred1 > BasePred2)
    return false;
  // Compare operands.
  bool CI1Preds = Pred1 == BasePred1;
  bool CI2Preds = Pred2 == BasePred1;
  for (int I = 0, E = CI1->getNumOperands(); I < E; ++I) {
    auto *Op1 = CI1->getOperand(CI1Preds ? I : E - I - 1);
    auto *Op2 = CI2->getOperand(CI2Preds ? I : E - I - 1);
    if (Op1 == Op2)
      continue;
    if (Op1->getValueID() < Op2->getValueID())
      return !IsCompatibility;
    if (Op1->getValueID() > Op2->getValueID())
      return false;
    if (auto *I1 = dyn_cast<Instruction>(Op1))
      if (auto *I2 = dyn_cast<Instruction>(Op2)) {
        if (IsCompatibility) {
          if (I1->getParent() != I2->getParent())
            return false;
        } else {
          // Try to compare nodes with same parent.
          DomTreeNodeBase<BasicBlock> *NodeI1 = DT.getNode(I1->getParent());
          DomTreeNodeBase<BasicBlock> *NodeI2 = DT.getNode(I2->getParent());
          if (!NodeI1)
            return NodeI2 != nullptr;
          if (!NodeI2)
            return false;
          assert((NodeI1 == NodeI2) ==
                     (NodeI1->getDFSNumIn() == NodeI2->getDFSNumIn()) &&
                 "Different nodes should have different DFS numbers");
          if (NodeI1 != NodeI2)
            return NodeI1->getDFSNumIn() < NodeI2->getDFSNumIn();
        }
        InstructionsState S = getSameOpcode({I1, I2}, TLI);
        if (S.getOpcode() && (IsCompatibility || !S.isAltShuffle()))
          continue;
        if (IsCompatibility)
          return false;
        if (I1->getOpcode() != I2->getOpcode())
          return I1->getOpcode() < I2->getOpcode();
      }
  }
  return IsCompatibility;
}

template <typename ItT>
bool SLPVectorizerPass::vectorizeCmpInsts(iterator_range<ItT> CmpInsts,
                                          BasicBlock *BB, BoUpSLP &R) {
  bool Changed = false;
  // Try to find reductions first.
  for (CmpInst *I : CmpInsts) {
    if (R.isDeleted(I))
      continue;
    for (Value *Op : I->operands())
      if (auto *RootOp = dyn_cast<Instruction>(Op))
        Changed |= vectorizeRootInstruction(nullptr, RootOp, BB, R, TTI);
  }
  // Try to vectorize operands as vector bundles.
  for (CmpInst *I : CmpInsts) {
    if (R.isDeleted(I))
      continue;
    Changed |= tryToVectorize(I, R);
  }
  // Try to vectorize list of compares.
  // Sort by type, compare predicate, etc.
  auto CompareSorter = [&](Value *V, Value *V2) {
    if (V == V2)
      return false;
    return compareCmp<false>(V, V2, *TLI, *DT);
  };

  auto AreCompatibleCompares = [&](Value *V1, Value *V2) {
    if (V1 == V2)
      return true;
    return compareCmp<true>(V1, V2, *TLI, *DT);
  };

  SmallVector<Value *> Vals;
  for (Instruction *V : CmpInsts)
    if (!R.isDeleted(V) && isValidElementType(getValueType(V)))
      Vals.push_back(V);
  if (Vals.size() <= 1)
    return Changed;
  Changed |= tryToVectorizeSequence<Value>(
      Vals, CompareSorter, AreCompatibleCompares,
      [this, &R](ArrayRef<Value *> Candidates, bool MaxVFOnly) {
        // Exclude possible reductions from other blocks.
        bool ArePossiblyReducedInOtherBlock = any_of(Candidates, [](Value *V) {
          return any_of(V->users(), [V](User *U) {
            auto *Select = dyn_cast<SelectInst>(U);
            return Select &&
                   Select->getParent() != cast<Instruction>(V)->getParent();
          });
        });
        if (ArePossiblyReducedInOtherBlock)
          return false;
        return tryToVectorizeList(Candidates, R, MaxVFOnly);
      },
      /*MaxVFOnly=*/true, R);
  return Changed;
}

bool SLPVectorizerPass::vectorizeInserts(InstSetVector &Instructions,
                                         BasicBlock *BB, BoUpSLP &R) {
  assert(all_of(Instructions, IsaPred<InsertElementInst, InsertValueInst>) &&
         "This function only accepts Insert instructions");
  bool OpsChanged = false;
  SmallVector<WeakTrackingVH> PostponedInsts;
  for (auto *I : reverse(Instructions)) {
    // pass1 - try to match and vectorize a buildvector sequence for MaxVF only.
    if (R.isDeleted(I) || isa<CmpInst>(I))
      continue;
    if (auto *LastInsertValue = dyn_cast<InsertValueInst>(I)) {
      OpsChanged |=
          vectorizeInsertValueInst(LastInsertValue, BB, R, /*MaxVFOnly=*/true);
    } else if (auto *LastInsertElem = dyn_cast<InsertElementInst>(I)) {
      OpsChanged |=
          vectorizeInsertElementInst(LastInsertElem, BB, R, /*MaxVFOnly=*/true);
    }
    // pass2 - try to vectorize reductions only
    if (R.isDeleted(I))
      continue;
    OpsChanged |= vectorizeHorReduction(nullptr, I, BB, R, TTI, PostponedInsts);
    if (R.isDeleted(I) || isa<CmpInst>(I))
      continue;
    // pass3 - try to match and vectorize a buildvector sequence.
    if (auto *LastInsertValue = dyn_cast<InsertValueInst>(I)) {
      OpsChanged |=
          vectorizeInsertValueInst(LastInsertValue, BB, R, /*MaxVFOnly=*/false);
    } else if (auto *LastInsertElem = dyn_cast<InsertElementInst>(I)) {
      OpsChanged |= vectorizeInsertElementInst(LastInsertElem, BB, R,
                                               /*MaxVFOnly=*/false);
    }
  }
  // Now try to vectorize postponed instructions.
  OpsChanged |= tryToVectorize(PostponedInsts, R);

  Instructions.clear();
  return OpsChanged;
}

bool SLPVectorizerPass::vectorizeChainsInBlock(BasicBlock *BB, BoUpSLP &R) {
  bool Changed = false;
  SmallVector<Value *, 4> Incoming;
  SmallPtrSet<Value *, 16> VisitedInstrs;
  // Maps phi nodes to the non-phi nodes found in the use tree for each phi
  // node. Allows better to identify the chains that can be vectorized in the
  // better way.
  DenseMap<Value *, SmallVector<Value *, 4>> PHIToOpcodes;
  auto PHICompare = [this, &PHIToOpcodes](Value *V1, Value *V2) {
    assert(isValidElementType(V1->getType()) &&
           isValidElementType(V2->getType()) &&
           "Expected vectorizable types only.");
    // It is fine to compare type IDs here, since we expect only vectorizable
    // types, like ints, floats and pointers, we don't care about other type.
    if (V1->getType()->getTypeID() < V2->getType()->getTypeID())
      return true;
    if (V1->getType()->getTypeID() > V2->getType()->getTypeID())
      return false;
    if (V1->getType()->getScalarSizeInBits() <
        V2->getType()->getScalarSizeInBits())
      return true;
    if (V1->getType()->getScalarSizeInBits() >
        V2->getType()->getScalarSizeInBits())
      return false;
    ArrayRef<Value *> Opcodes1 = PHIToOpcodes[V1];
    ArrayRef<Value *> Opcodes2 = PHIToOpcodes[V2];
    if (Opcodes1.size() < Opcodes2.size())
      return true;
    if (Opcodes1.size() > Opcodes2.size())
      return false;
    for (int I = 0, E = Opcodes1.size(); I < E; ++I) {
      {
        // Instructions come first.
        auto *I1 = dyn_cast<Instruction>(Opcodes1[I]);
        auto *I2 = dyn_cast<Instruction>(Opcodes2[I]);
        if (I1 && I2) {
          DomTreeNodeBase<BasicBlock> *NodeI1 = DT->getNode(I1->getParent());
          DomTreeNodeBase<BasicBlock> *NodeI2 = DT->getNode(I2->getParent());
          if (!NodeI1)
            return NodeI2 != nullptr;
          if (!NodeI2)
            return false;
          assert((NodeI1 == NodeI2) ==
                     (NodeI1->getDFSNumIn() == NodeI2->getDFSNumIn()) &&
                 "Different nodes should have different DFS numbers");
          if (NodeI1 != NodeI2)
            return NodeI1->getDFSNumIn() < NodeI2->getDFSNumIn();
          InstructionsState S = getSameOpcode({I1, I2}, *TLI);
          if (S.getOpcode() && !S.isAltShuffle())
            continue;
          return I1->getOpcode() < I2->getOpcode();
        }
        if (I1)
          return true;
        if (I2)
          return false;
      }
      {
        // Non-undef constants come next.
        bool C1 = isa<Constant>(Opcodes1[I]) && !isa<UndefValue>(Opcodes1[I]);
        bool C2 = isa<Constant>(Opcodes2[I]) && !isa<UndefValue>(Opcodes2[I]);
        if (C1 && C2)
          continue;
        if (C1)
          return true;
        if (C2)
          return false;
      }
      bool U1 = isa<UndefValue>(Opcodes1[I]);
      bool U2 = isa<UndefValue>(Opcodes2[I]);
      {
        // Non-constant non-instructions come next.
        if (!U1 && !U2) {
          auto ValID1 = Opcodes1[I]->getValueID();
          auto ValID2 = Opcodes2[I]->getValueID();
          if (ValID1 == ValID2)
            continue;
          if (ValID1 < ValID2)
            return true;
          if (ValID1 > ValID2)
            return false;
        }
        if (!U1)
          return true;
        if (!U2)
          return false;
      }
      // Undefs come last.
      assert(U1 && U2 && "The only thing left should be undef & undef.");
    }
    return false;
  };
  auto AreCompatiblePHIs = [&PHIToOpcodes, this, &R](Value *V1, Value *V2) {
    if (V1 == V2)
      return true;
    if (V1->getType() != V2->getType())
      return false;
    ArrayRef<Value *> Opcodes1 = PHIToOpcodes[V1];
    ArrayRef<Value *> Opcodes2 = PHIToOpcodes[V2];
    if (Opcodes1.size() != Opcodes2.size())
      return false;
    for (int I = 0, E = Opcodes1.size(); I < E; ++I) {
      // Undefs are compatible with any other value.
      if (isa<UndefValue>(Opcodes1[I]) || isa<UndefValue>(Opcodes2[I]))
        continue;
      if (auto *I1 = dyn_cast<Instruction>(Opcodes1[I]))
        if (auto *I2 = dyn_cast<Instruction>(Opcodes2[I])) {
          if (R.isDeleted(I1) || R.isDeleted(I2))
            return false;
          if (I1->getParent() != I2->getParent())
            return false;
          InstructionsState S = getSameOpcode({I1, I2}, *TLI);
          if (S.getOpcode())
            continue;
          return false;
        }
      if (isa<Constant>(Opcodes1[I]) && isa<Constant>(Opcodes2[I]))
        continue;
      if (Opcodes1[I]->getValueID() != Opcodes2[I]->getValueID())
        return false;
    }
    return true;
  };

  bool HaveVectorizedPhiNodes = false;
  do {
    // Collect the incoming values from the PHIs.
    Incoming.clear();
    for (Instruction &I : *BB) {
      auto *P = dyn_cast<PHINode>(&I);
      if (!P || P->getNumIncomingValues() > MaxPHINumOperands)
        break;

      // No need to analyze deleted, vectorized and non-vectorizable
      // instructions.
      if (!VisitedInstrs.count(P) && !R.isDeleted(P) &&
          isValidElementType(P->getType()))
        Incoming.push_back(P);
    }

    if (Incoming.size() <= 1)
      break;

    // Find the corresponding non-phi nodes for better matching when trying to
    // build the tree.
    for (Value *V : Incoming) {
      SmallVectorImpl<Value *> &Opcodes =
          PHIToOpcodes.try_emplace(V).first->getSecond();
      if (!Opcodes.empty())
        continue;
      SmallVector<Value *, 4> Nodes(1, V);
      SmallPtrSet<Value *, 4> Visited;
      while (!Nodes.empty()) {
        auto *PHI = cast<PHINode>(Nodes.pop_back_val());
        if (!Visited.insert(PHI).second)
          continue;
        for (Value *V : PHI->incoming_values()) {
          if (auto *PHI1 = dyn_cast<PHINode>((V))) {
            Nodes.push_back(PHI1);
            continue;
          }
          Opcodes.emplace_back(V);
        }
      }
    }

    HaveVectorizedPhiNodes = tryToVectorizeSequence<Value>(
        Incoming, PHICompare, AreCompatiblePHIs,
        [this, &R](ArrayRef<Value *> Candidates, bool MaxVFOnly) {
          return tryToVectorizeList(Candidates, R, MaxVFOnly);
        },
        /*MaxVFOnly=*/true, R);
    Changed |= HaveVectorizedPhiNodes;
    if (HaveVectorizedPhiNodes && any_of(PHIToOpcodes, [&](const auto &P) {
          auto *PHI = dyn_cast<PHINode>(P.first);
          return !PHI || R.isDeleted(PHI);
        }))
      PHIToOpcodes.clear();
    VisitedInstrs.insert(Incoming.begin(), Incoming.end());
  } while (HaveVectorizedPhiNodes);

  VisitedInstrs.clear();

  InstSetVector PostProcessInserts;
  SmallSetVector<CmpInst *, 8> PostProcessCmps;
  // Vectorizes Inserts in `PostProcessInserts` and if `VecctorizeCmps` is true
  // also vectorizes `PostProcessCmps`.
  auto VectorizeInsertsAndCmps = [&](bool VectorizeCmps) {
    bool Changed = vectorizeInserts(PostProcessInserts, BB, R);
    if (VectorizeCmps) {
      Changed |= vectorizeCmpInsts(reverse(PostProcessCmps), BB, R);
      PostProcessCmps.clear();
    }
    PostProcessInserts.clear();
    return Changed;
  };
  // Returns true if `I` is in `PostProcessInserts` or `PostProcessCmps`.
  auto IsInPostProcessInstrs = [&](Instruction *I) {
    if (auto *Cmp = dyn_cast<CmpInst>(I))
      return PostProcessCmps.contains(Cmp);
    return isa<InsertElementInst, InsertValueInst>(I) &&
           PostProcessInserts.contains(I);
  };
  // Returns true if `I` is an instruction without users, like terminator, or
  // function call with ignored return value, store. Ignore unused instructions
  // (basing on instruction type, except for CallInst and InvokeInst).
  auto HasNoUsers = [](Instruction *I) {
    return I->use_empty() &&
           (I->getType()->isVoidTy() || isa<CallInst, InvokeInst>(I));
  };
  for (BasicBlock::iterator It = BB->begin(), E = BB->end(); It != E; ++It) {
    // Skip instructions with scalable type. The num of elements is unknown at
    // compile-time for scalable type.
    if (isa<ScalableVectorType>(It->getType()))
      continue;

    // Skip instructions marked for the deletion.
    if (R.isDeleted(&*It))
      continue;
    // We may go through BB multiple times so skip the one we have checked.
    if (!VisitedInstrs.insert(&*It).second) {
      if (HasNoUsers(&*It) &&
          VectorizeInsertsAndCmps(/*VectorizeCmps=*/It->isTerminator())) {
        // We would like to start over since some instructions are deleted
        // and the iterator may become invalid value.
        Changed = true;
        It = BB->begin();
        E = BB->end();
      }
      continue;
    }

    if (isa<DbgInfoIntrinsic>(It))
      continue;

    // Try to vectorize reductions that use PHINodes.
    if (PHINode *P = dyn_cast<PHINode>(It)) {
      // Check that the PHI is a reduction PHI.
      if (P->getNumIncomingValues() == 2) {
        // Try to match and vectorize a horizontal reduction.
        Instruction *Root = getReductionInstr(DT, P, BB, LI);
        if (Root && vectorizeRootInstruction(P, Root, BB, R, TTI)) {
          Changed = true;
          It = BB->begin();
          E = BB->end();
          continue;
        }
      }
      // Try to vectorize the incoming values of the PHI, to catch reductions
      // that feed into PHIs.
      for (unsigned I : seq<unsigned>(P->getNumIncomingValues())) {
        // Skip if the incoming block is the current BB for now. Also, bypass
        // unreachable IR for efficiency and to avoid crashing.
        // TODO: Collect the skipped incoming values and try to vectorize them
        // after processing BB.
        if (BB == P->getIncomingBlock(I) ||
            !DT->isReachableFromEntry(P->getIncomingBlock(I)))
          continue;

        // Postponed instructions should not be vectorized here, delay their
        // vectorization.
        if (auto *PI = dyn_cast<Instruction>(P->getIncomingValue(I));
            PI && !IsInPostProcessInstrs(PI)) {
          bool Res = vectorizeRootInstruction(nullptr, PI,
                                              P->getIncomingBlock(I), R, TTI);
          Changed |= Res;
          if (Res && R.isDeleted(P)) {
            It = BB->begin();
            E = BB->end();
            break;
          }
        }
      }
      continue;
    }

    if (HasNoUsers(&*It)) {
      bool OpsChanged = false;
      auto *SI = dyn_cast<StoreInst>(It);
      bool TryToVectorizeRoot = ShouldStartVectorizeHorAtStore || !SI;
      if (SI) {
        auto *I = Stores.find(getUnderlyingObject(SI->getPointerOperand()));
        // Try to vectorize chain in store, if this is the only store to the
        // address in the block.
        // TODO: This is just a temporarily solution to save compile time. Need
        // to investigate if we can safely turn on slp-vectorize-hor-store
        // instead to allow lookup for reduction chains in all non-vectorized
        // stores (need to check side effects and compile time).
        TryToVectorizeRoot |= (I == Stores.end() || I->second.size() == 1) &&
                              SI->getValueOperand()->hasOneUse();
      }
      if (TryToVectorizeRoot) {
        for (auto *V : It->operand_values()) {
          // Postponed instructions should not be vectorized here, delay their
          // vectorization.
          if (auto *VI = dyn_cast<Instruction>(V);
              VI && !IsInPostProcessInstrs(VI))
            // Try to match and vectorize a horizontal reduction.
            OpsChanged |= vectorizeRootInstruction(nullptr, VI, BB, R, TTI);
        }
      }
      // Start vectorization of post-process list of instructions from the
      // top-tree instructions to try to vectorize as many instructions as
      // possible.
      OpsChanged |=
          VectorizeInsertsAndCmps(/*VectorizeCmps=*/It->isTerminator());
      if (OpsChanged) {
        // We would like to start over since some instructions are deleted
        // and the iterator may become invalid value.
        Changed = true;
        It = BB->begin();
        E = BB->end();
        continue;
      }
    }

    if (isa<InsertElementInst, InsertValueInst>(It))
      PostProcessInserts.insert(&*It);
    else if (isa<CmpInst>(It))
      PostProcessCmps.insert(cast<CmpInst>(&*It));
  }

  return Changed;
}

bool SLPVectorizerPass::vectorizeGEPIndices(BasicBlock *BB, BoUpSLP &R) {
  auto Changed = false;
  for (auto &Entry : GEPs) {
    // If the getelementptr list has fewer than two elements, there's nothing
    // to do.
    if (Entry.second.size() < 2)
      continue;

    LLVM_DEBUG(dbgs() << "SLP: Analyzing a getelementptr list of length "
                      << Entry.second.size() << ".\n");

    // Process the GEP list in chunks suitable for the target's supported
    // vector size. If a vector register can't hold 1 element, we are done. We
    // are trying to vectorize the index computations, so the maximum number of
    // elements is based on the size of the index expression, rather than the
    // size of the GEP itself (the target's pointer size).
    auto *It = find_if(Entry.second, [&](GetElementPtrInst *GEP) {
      return !R.isDeleted(GEP);
    });
    if (It == Entry.second.end())
      continue;
    unsigned MaxVecRegSize = R.getMaxVecRegSize();
    unsigned EltSize = R.getVectorElementSize(*(*It)->idx_begin());
    if (MaxVecRegSize < EltSize)
      continue;

    unsigned MaxElts = MaxVecRegSize / EltSize;
    for (unsigned BI = 0, BE = Entry.second.size(); BI < BE; BI += MaxElts) {
      auto Len = std::min<unsigned>(BE - BI, MaxElts);
      ArrayRef<GetElementPtrInst *> GEPList(&Entry.second[BI], Len);

      // Initialize a set a candidate getelementptrs. Note that we use a
      // SetVector here to preserve program order. If the index computations
      // are vectorizable and begin with loads, we want to minimize the chance
      // of having to reorder them later.
      SetVector<Value *> Candidates(GEPList.begin(), GEPList.end());

      // Some of the candidates may have already been vectorized after we
      // initially collected them or their index is optimized to constant value.
      // If so, they are marked as deleted, so remove them from the set of
      // candidates.
      Candidates.remove_if([&R](Value *I) {
        return R.isDeleted(cast<Instruction>(I)) ||
               isa<Constant>(cast<GetElementPtrInst>(I)->idx_begin()->get());
      });

      // Remove from the set of candidates all pairs of getelementptrs with
      // constant differences. Such getelementptrs are likely not good
      // candidates for vectorization in a bottom-up phase since one can be
      // computed from the other. We also ensure all candidate getelementptr
      // indices are unique.
      for (int I = 0, E = GEPList.size(); I < E && Candidates.size() > 1; ++I) {
        auto *GEPI = GEPList[I];
        if (!Candidates.count(GEPI))
          continue;
        const SCEV *SCEVI = SE->getSCEV(GEPList[I]);
        for (int J = I + 1; J < E && Candidates.size() > 1; ++J) {
          auto *GEPJ = GEPList[J];
          const SCEV *SCEVJ = SE->getSCEV(GEPList[J]);
          if (isa<SCEVConstant>(SE->getMinusSCEV(SCEVI, SCEVJ))) {
            Candidates.remove(GEPI);
            Candidates.remove(GEPJ);
          } else if (GEPI->idx_begin()->get() == GEPJ->idx_begin()->get()) {
            Candidates.remove(GEPJ);
          }
        }
      }

      // We break out of the above computation as soon as we know there are
      // fewer than two candidates remaining.
      if (Candidates.size() < 2)
        continue;

      // Add the single, non-constant index of each candidate to the bundle. We
      // ensured the indices met these constraints when we originally collected
      // the getelementptrs.
      SmallVector<Value *, 16> Bundle(Candidates.size());
      auto BundleIndex = 0u;
      for (auto *V : Candidates) {
        auto *GEP = cast<GetElementPtrInst>(V);
        auto *GEPIdx = GEP->idx_begin()->get();
        assert(GEP->getNumIndices() == 1 && !isa<Constant>(GEPIdx));
        Bundle[BundleIndex++] = GEPIdx;
      }

      // Try and vectorize the indices. We are currently only interested in
      // gather-like cases of the form:
      //
      // ... = g[a[0] - b[0]] + g[a[1] - b[1]] + ...
      //
      // where the loads of "a", the loads of "b", and the subtractions can be
      // performed in parallel. It's likely that detecting this pattern in a
      // bottom-up phase will be simpler and less costly than building a
      // full-blown top-down phase beginning at the consecutive loads.
      Changed |= tryToVectorizeList(Bundle, R);
    }
  }
  return Changed;
}

bool SLPVectorizerPass::vectorizeStoreChains(BoUpSLP &R) {
  bool Changed = false;
  // Sort by type, base pointers and values operand. Value operands must be
  // compatible (have the same opcode, same parent), otherwise it is
  // definitely not profitable to try to vectorize them.
  auto &&StoreSorter = [this](StoreInst *V, StoreInst *V2) {
    if (V->getValueOperand()->getType()->getTypeID() <
        V2->getValueOperand()->getType()->getTypeID())
      return true;
    if (V->getValueOperand()->getType()->getTypeID() >
        V2->getValueOperand()->getType()->getTypeID())
      return false;
    if (V->getPointerOperandType()->getTypeID() <
        V2->getPointerOperandType()->getTypeID())
      return true;
    if (V->getPointerOperandType()->getTypeID() >
        V2->getPointerOperandType()->getTypeID())
      return false;
    if (V->getValueOperand()->getType()->getScalarSizeInBits() <
        V2->getValueOperand()->getType()->getScalarSizeInBits())
      return true;
    if (V->getValueOperand()->getType()->getScalarSizeInBits() >
        V2->getValueOperand()->getType()->getScalarSizeInBits())
      return false;
    // UndefValues are compatible with all other values.
    if (isa<UndefValue>(V->getValueOperand()) ||
        isa<UndefValue>(V2->getValueOperand()))
      return false;
    if (auto *I1 = dyn_cast<Instruction>(V->getValueOperand()))
      if (auto *I2 = dyn_cast<Instruction>(V2->getValueOperand())) {
        DomTreeNodeBase<llvm::BasicBlock> *NodeI1 =
            DT->getNode(I1->getParent());
        DomTreeNodeBase<llvm::BasicBlock> *NodeI2 =
            DT->getNode(I2->getParent());
        assert(NodeI1 && "Should only process reachable instructions");
        assert(NodeI2 && "Should only process reachable instructions");
        assert((NodeI1 == NodeI2) ==
                   (NodeI1->getDFSNumIn() == NodeI2->getDFSNumIn()) &&
               "Different nodes should have different DFS numbers");
        if (NodeI1 != NodeI2)
          return NodeI1->getDFSNumIn() < NodeI2->getDFSNumIn();
        InstructionsState S = getSameOpcode({I1, I2}, *TLI);
        if (S.getOpcode())
          return false;
        return I1->getOpcode() < I2->getOpcode();
      }
    if (isa<Constant>(V->getValueOperand()) &&
        isa<Constant>(V2->getValueOperand()))
      return false;
    return V->getValueOperand()->getValueID() <
           V2->getValueOperand()->getValueID();
  };

  auto &&AreCompatibleStores = [this](StoreInst *V1, StoreInst *V2) {
    if (V1 == V2)
      return true;
    if (V1->getValueOperand()->getType() != V2->getValueOperand()->getType())
      return false;
    if (V1->getPointerOperandType() != V2->getPointerOperandType())
      return false;
    // Undefs are compatible with any other value.
    if (isa<UndefValue>(V1->getValueOperand()) ||
        isa<UndefValue>(V2->getValueOperand()))
      return true;
    if (auto *I1 = dyn_cast<Instruction>(V1->getValueOperand()))
      if (auto *I2 = dyn_cast<Instruction>(V2->getValueOperand())) {
        if (I1->getParent() != I2->getParent())
          return false;
        InstructionsState S = getSameOpcode({I1, I2}, *TLI);
        return S.getOpcode() > 0;
      }
    if (isa<Constant>(V1->getValueOperand()) &&
        isa<Constant>(V2->getValueOperand()))
      return true;
    return V1->getValueOperand()->getValueID() ==
           V2->getValueOperand()->getValueID();
  };

  // Attempt to sort and vectorize each of the store-groups.
  DenseSet<std::tuple<Value *, Value *, Value *, Value *, unsigned>> Attempted;
  for (auto &Pair : Stores) {
    if (Pair.second.size() < 2)
      continue;

    LLVM_DEBUG(dbgs() << "SLP: Analyzing a store chain of length "
                      << Pair.second.size() << ".\n");

    if (!isValidElementType(Pair.second.front()->getValueOperand()->getType()))
      continue;

    // Reverse stores to do bottom-to-top analysis. This is important if the
    // values are stores to the same addresses several times, in this case need
    // to follow the stores order (reversed to meet the memory dependecies).
    SmallVector<StoreInst *> ReversedStores(Pair.second.rbegin(),
                                            Pair.second.rend());
    Changed |= tryToVectorizeSequence<StoreInst>(
        ReversedStores, StoreSorter, AreCompatibleStores,
        [&](ArrayRef<StoreInst *> Candidates, bool) {
          return vectorizeStores(Candidates, R, Attempted);
        },
        /*MaxVFOnly=*/false, R);
  }
  return Changed;
}