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//===- 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/Optional.h"
#include "llvm/ADT/PostOrderIterator.h"
#include "llvm/ADT/STLExtras.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/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/DebugLoc.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/NoFolder.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"
#include "llvm/IR/Verifier.h"
#include "llvm/InitializePasses.h"
#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/LoopUtils.h"
#include "llvm/Transforms/Vectorize.h"
#include <algorithm>
#include <cassert>
#include <cstdint>
#include <iterator>
#include <memory>
#include <set>
#include <string>
#include <tuple>
#include <utility>
#include <vector>
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");
cl::opt<bool> RunSLPVectorization("vectorize-slp", cl::init(true), cl::Hidden,
cl::desc("Run the SLP vectorization passes"));
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>
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)"));
static cl::opt<int>
MaxStoreLookup("slp-max-store-lookup", cl::init(32), cl::Hidden,
cl::desc("Maximum depth of the lookup for consecutive stores."));
/// 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 Look-ahead heuristic goes through the users of the bundle to calculate
// the users cost in getExternalUsesCost(). To avoid compilation time increase
// we limit the number of users visited to this value.
static cl::opt<unsigned> LookAheadUsersBudget(
"slp-look-ahead-users-budget", cl::init(2), cl::Hidden,
cl::desc("The maximum number of users to visit while visiting the "
"predecessors. This prevents compilation time increase."));
static cl::opt<bool>
ViewSLPTree("view-slp-tree", cl::Hidden,
cl::desc("Display the SLP trees with Graphviz"));
// 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;
// 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;
/// 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) {
return VectorType::isValidElementType(Ty) && !Ty->isX86_FP80Ty() &&
!Ty->isPPC_FP128Ty();
}
/// \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;
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.
for (Value *i : VL)
if (!isa<Constant>(i) || isa<ConstantExpr>(i) || isa<GlobalValue>(i))
return false;
return true;
}
/// \returns True if all of the values in \p VL are identical.
static bool isSplat(ArrayRef<Value *> VL) {
for (unsigned i = 1, e = VL.size(); i < e; ++i)
if (VL[i] != VL[0])
return false;
return true;
}
/// \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();
// TODO: This should check for generic Instruction::isCommutative(), but
// we need to confirm that the caller code correctly handles Intrinsics
// for example (does not have 2 operands).
return false;
}
/// 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
/// We convert this initially to something 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
/// %1 = insertelement <4 x i8> poison, i8 %x0, i32 0
/// %2 = insertelement <4 x i8> %1, i8 %x3, i32 1
/// %3 = insertelement <4 x i8> %2, i8 %y1, i32 2
/// %4 = insertelement <4 x i8> %3, i8 %y2, i32 3
/// %5 = mul <4 x i8> %4, %4
/// %6 = extractelement <4 x i8> %5, i32 0
/// %ins1 = insertelement <4 x i8> poison, i8 %6, i32 0
/// %7 = extractelement <4 x i8> %5, i32 1
/// %ins2 = insertelement <4 x i8> %ins1, i8 %7, i32 1
/// %8 = extractelement <4 x i8> %5, i32 2
/// %ins3 = insertelement <4 x i8> %ins2, i8 %8, i32 2
/// %9 = extractelement <4 x i8> %5, i32 3
/// %ins4 = insertelement <4 x i8> %ins3, i8 %9, i32 3
/// ret <4 x i8> %ins4
/// InstCombiner transforms this into a shuffle and vector mul
/// Mask will return the Shuffle Mask equivalent to the extracted elements.
/// TODO: Can we split off and reuse the shuffle mask detection from
/// TargetTransformInfo::getInstructionThroughput?
static Optional<TargetTransformInfo::ShuffleKind>
isShuffle(ArrayRef<Value *> VL, SmallVectorImpl<int> &Mask) {
auto *EI0 = cast<ExtractElementInst>(VL[0]);
unsigned Size =
cast<FixedVectorType>(EI0->getVectorOperandType())->getNumElements();
Value *Vec1 = nullptr;
Value *Vec2 = nullptr;
enum ShuffleMode { Unknown, Select, Permute };
ShuffleMode CommonShuffleMode = Unknown;
for (unsigned I = 0, E = VL.size(); I < E; ++I) {
auto *EI = cast<ExtractElementInst>(VL[I]);
auto *Vec = EI->getVectorOperand();
// All vector operands must have the same number of vector elements.
if (cast<FixedVectorType>(Vec->getType())->getNumElements() != Size)
return None;
auto *Idx = dyn_cast<ConstantInt>(EI->getIndexOperand());
if (!Idx)
return None;
// Undefined behavior if Idx is negative or >= Size.
if (Idx->getValue().uge(Size)) {
Mask.push_back(UndefMaskElem);
continue;
}
unsigned IntIdx = Idx->getValue().getZExtValue();
Mask.push_back(IntIdx);
// We can extractelement from undef or poison vector.
if (isa<UndefValue>(Vec))
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;
else
return None;
if (CommonShuffleMode == Permute)
continue;
// If the extract index is not the same as the operation number, it is a
// permutation.
if (IntIdx != 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;
}
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 getOpcode() != getAltOpcode(); }
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
/// 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.
static Value *isOneOf(const InstructionsState &S, Value *Op) {
auto *I = dyn_cast<Instruction>(Op);
if (I && S.isOpcodeOrAlt(I))
return Op;
return S.OpValue;
}
/// \returns true if \p Opcode is allowed as part of 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;
}
/// \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,
unsigned BaseIndex = 0) {
// 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]);
unsigned Opcode = cast<Instruction>(VL[BaseIndex])->getOpcode();
unsigned AltOpcode = Opcode;
unsigned AltIndex = BaseIndex;
// Check for one alternate opcode from another BinaryOperator.
// TODO - generalize to support all operators (types, calls etc.).
for (int Cnt = 0, E = VL.size(); Cnt < E; Cnt++) {
unsigned InstOpcode = cast<Instruction>(VL[Cnt])->getOpcode();
if (IsBinOp && isa<BinaryOperator>(VL[Cnt])) {
if (InstOpcode == Opcode || InstOpcode == AltOpcode)
continue;
if (Opcode == AltOpcode && isValidForAlternation(InstOpcode) &&
isValidForAlternation(Opcode)) {
AltOpcode = InstOpcode;
AltIndex = Cnt;
continue;
}
} else if (IsCastOp && isa<CastInst>(VL[Cnt])) {
Type *Ty0 = cast<Instruction>(VL[BaseIndex])->getOperand(0)->getType();
Type *Ty1 = cast<Instruction>(VL[Cnt])->getOperand(0)->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 (InstOpcode == Opcode || InstOpcode == AltOpcode)
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[0]->getType();
for (int i = 1, e = VL.size(); i < e; i++)
if (VL[i]->getType() != Ty)
return false;
return true;
}
/// \returns True if Extract{Value,Element} instruction extracts element Idx.
static 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 None;
return CI->getZExtValue();
}
ExtractValueInst *EI = cast<ExtractValueInst>(E);
if (EI->getNumIndices() != 1)
return None;
return *EI->idx_begin();
}
/// \returns True if in-tree use also needs extract. This refers to
/// possible scalar operand in vectorized instruction.
static bool InTreeUserNeedToExtract(Value *Scalar, Instruction *UserInst,
TargetLibraryInfo *TLI) {
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);
for (unsigned i = 0, e = CI->getNumArgOperands(); i != e; ++i) {
if (hasVectorInstrinsicScalarOpd(ID, i))
return (CI->getArgOperand(i) == Scalar);
}
LLVM_FALLTHROUGH;
}
default:
return false;
}
}
/// \returns the AA location that is being access by the instruction.
static MemoryLocation getLocation(Instruction *I, AAResults *AA) {
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;
}
namespace llvm {
static void inversePermutation(ArrayRef<unsigned> Indices,
SmallVectorImpl<int> &Mask) {
Mask.clear();
const unsigned E = Indices.size();
Mask.resize(E, E + 1);
for (unsigned I = 0; I < E; ++I)
Mask[Indices[I]] = I;
}
namespace slpvectorizer {
/// Bottom Up SLP Vectorizer.
class BoUpSLP {
struct TreeEntry;
struct ScheduleData;
public:
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)
: F(Func), SE(Se), TTI(Tti), TLI(TLi), AA(Aa), LI(Li), DT(Dt), AC(AC),
DB(DB), DL(DL), ORE(ORE), Builder(Se->getContext()) {
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)
.getFixedSize();
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(ExtraValueToDebugLocsMap &ExternallyUsedValues);
/// \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();
/// 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,
ArrayRef<Value *> UserIgnoreLst = None);
/// Construct a vectorizable tree that starts at \p Roots, ignoring users for
/// the purpose of scheduling and extraction in the \p UserIgnoreLst taking
/// into account (and updating it, if required) list of externally used
/// values stored in \p ExternallyUsedValues.
void buildTree(ArrayRef<Value *> Roots,
ExtraValueToDebugLocsMap &ExternallyUsedValues,
ArrayRef<Value *> UserIgnoreLst = None);
/// Clear the internal data structures that are created by 'buildTree'.
void deleteTree() {
VectorizableTree.clear();
ScalarToTreeEntry.clear();
MustGather.clear();
ExternalUses.clear();
NumOpsWantToKeepOrder.clear();
NumOpsWantToKeepOriginalOrder = 0;
for (auto &Iter : BlocksSchedules) {
BlockScheduling *BS = Iter.second.get();
BS->clear();
}
MinBWs.clear();
}
unsigned getTreeSize() const { return VectorizableTree.size(); }
/// Perform LICM and CSE on the newly generated gather sequences.
void optimizeGatherSequence();
/// \returns The best order of instructions for vectorization.
Optional<ArrayRef<unsigned>> bestOrder() const {
assert(llvm::all_of(
NumOpsWantToKeepOrder,
[this](const decltype(NumOpsWantToKeepOrder)::value_type &D) {
return D.getFirst().size() ==
VectorizableTree[0]->Scalars.size();
}) &&
"All orders must have the same size as number of instructions in "
"tree node.");
auto I = std::max_element(
NumOpsWantToKeepOrder.begin(), NumOpsWantToKeepOrder.end(),
[](const decltype(NumOpsWantToKeepOrder)::value_type &D1,
const decltype(NumOpsWantToKeepOrder)::value_type &D2) {
return D1.second < D2.second;
});
if (I == NumOpsWantToKeepOrder.end() ||
I->getSecond() <= NumOpsWantToKeepOriginalOrder)
return None;
return makeArrayRef(I->getFirst());
}
/// Builds the correct order for root instructions.
/// If some leaves have the same instructions to be vectorized, we may
/// incorrectly evaluate the best order for the root node (it is built for the
/// vector of instructions without repeated instructions and, thus, has less
/// elements than the root node). This function builds the correct order for
/// the root node.
/// For example, if the root node is \<a+b, a+c, a+d, f+e\>, then the leaves
/// are \<a, a, a, f\> and \<b, c, d, e\>. When we try to vectorize the first
/// leaf, it will be shrink to \<a, b\>. If instructions in this leaf should
/// be reordered, the best order will be \<1, 0\>. We need to extend this
/// order for the root node. For the root node this order should look like
/// \<3, 0, 1, 2\>. This function extends the order for the reused
/// instructions.
void findRootOrder(OrdersType &Order) {
// If the leaf has the same number of instructions to vectorize as the root
// - order must be set already.
unsigned RootSize = VectorizableTree[0]->Scalars.size();
if (Order.size() == RootSize)
return;
SmallVector<unsigned, 4> RealOrder(Order.size());
std::swap(Order, RealOrder);
SmallVector<int, 4> Mask;
inversePermutation(RealOrder, Mask);
Order.assign(Mask.begin(), Mask.end());
// The leaf has less number of instructions - need to find the true order of
// the root.
// Scan the nodes starting from the leaf back to the root.
const TreeEntry *PNode = VectorizableTree.back().get();
SmallVector<const TreeEntry *, 4> Nodes(1, PNode);
SmallPtrSet<const TreeEntry *, 4> Visited;
while (!Nodes.empty() && Order.size() != RootSize) {
const TreeEntry *PNode = Nodes.pop_back_val();
if (!Visited.insert(PNode).second)
continue;
const TreeEntry &Node = *PNode;
for (const EdgeInfo &EI : Node.UserTreeIndices)
if (EI.UserTE)
Nodes.push_back(EI.UserTE);
if (Node.ReuseShuffleIndices.empty())
continue;
// Build the order for the parent node.
OrdersType NewOrder(Node.ReuseShuffleIndices.size(), RootSize);
SmallVector<unsigned, 4> OrderCounter(Order.size(), 0);
// The algorithm of the order extension is:
// 1. Calculate the number of the same instructions for the order.
// 2. Calculate the index of the new order: total number of instructions
// with order less than the order of the current instruction + reuse
// number of the current instruction.
// 3. The new order is just the index of the instruction in the original
// vector of the instructions.
for (unsigned I : Node.ReuseShuffleIndices)
++OrderCounter[Order[I]];
SmallVector<unsigned, 4> CurrentCounter(Order.size(), 0);
for (unsigned I = 0, E = Node.ReuseShuffleIndices.size(); I < E; ++I) {
unsigned ReusedIdx = Node.ReuseShuffleIndices[I];
unsigned OrderIdx = Order[ReusedIdx];
unsigned NewIdx = 0;
for (unsigned J = 0; J < OrderIdx; ++J)
NewIdx += OrderCounter[J];
NewIdx += CurrentCounter[OrderIdx];
++CurrentCounter[OrderIdx];
assert(NewOrder[NewIdx] == RootSize &&
"The order index should not be written already.");
NewOrder[NewIdx] = I;
}
std::swap(Order, NewOrder);
}
assert(Order.size() == RootSize &&
"Root node is expected or the size of the order must be the same as "
"the number of elements in the root node.");
assert(llvm::all_of(Order,
[RootSize](unsigned Val) { return Val != RootSize; }) &&
"All indices must be initialized");
}
/// \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 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 DataLayout &DL) const;
/// \returns True if the VectorizableTree is both tiny and not fully
/// vectorizable. We do not vectorize such trees.
bool isTreeTinyAndNotFullyVectorizable() 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() const;
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
};
/// 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 DataLayout &DL;
ScalarEvolution &SE;
const BoUpSLP &R;
/// \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]);
}
// The hard-coded scores listed here are not very important. 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.
/// Loads from consecutive memory addresses, e.g. load(A[i]), load(A[i+1]).
static const int ScoreConsecutiveLoads = 3;
/// ExtractElementInst from same vector and consecutive indexes.
static const int ScoreConsecutiveExtracts = 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;
/// User exteranl to the vectorized code.
static const int ExternalUseCost = 1;
/// The user is internal but in a different lane.
static const int UserInDiffLaneCost = ExternalUseCost;
/// \returns the score of placing \p V1 and \p V2 in consecutive lanes.
static int getShallowScore(Value *V1, Value *V2, const DataLayout &DL,
ScalarEvolution &SE) {
auto *LI1 = dyn_cast<LoadInst>(V1);
auto *LI2 = dyn_cast<LoadInst>(V2);
if (LI1 && LI2) {
if (LI1->getParent() != LI2->getParent())
return VLOperands::ScoreFail;
Optional<int> Dist =
getPointersDiff(LI1->getPointerOperand(), LI2->getPointerOperand(),
DL, SE, /*StrictCheck=*/true);
return (Dist && *Dist == 1) ? VLOperands::ScoreConsecutiveLoads
: VLOperands::ScoreFail;
}
auto *C1 = dyn_cast<Constant>(V1);
auto *C2 = dyn_cast<Constant>(V2);
if (C1 && C2)
return VLOperands::ScoreConstants;
// Extracts from consecutive indexes of the same vector better score as
// the extracts could be optimized away.
Value *EV;
ConstantInt *Ex1Idx, *Ex2Idx;
if (match(V1, m_ExtractElt(m_Value(EV), m_ConstantInt(Ex1Idx))) &&
match(V2, m_ExtractElt(m_Deferred(EV), m_ConstantInt(Ex2Idx))) &&
Ex1Idx->getZExtValue() + 1 == Ex2Idx->getZExtValue())
return VLOperands::ScoreConsecutiveExtracts;
auto *I1 = dyn_cast<Instruction>(V1);
auto *I2 = dyn_cast<Instruction>(V2);
if (I1 && I2) {
if (I1 == I2)
return VLOperands::ScoreSplat;
InstructionsState S = getSameOpcode({I1, I2});
// Note: Only consider instructions with <= 2 operands to avoid
// complexity explosion.
if (S.getOpcode() && S.MainOp->getNumOperands() <= 2)
return S.isAltShuffle() ? VLOperands::ScoreAltOpcodes
: VLOperands::ScoreSameOpcode;
}
if (isa<UndefValue>(V2))
return VLOperands::ScoreUndef;
return VLOperands::ScoreFail;
}
/// Holds the values and their lane that are taking part in the look-ahead
/// score calculation. This is used in the external uses cost calculation.
SmallDenseMap<Value *, int> InLookAheadValues;
/// \Returns the additinal cost due to uses of \p LHS and \p RHS that are
/// either external to the vectorized code, or require shuffling.
int getExternalUsesCost(const std::pair<Value *, int> &LHS,
const std::pair<Value *, int> &RHS) {
int Cost = 0;
std::array<std::pair<Value *, int>, 2> Values = {{LHS, RHS}};
for (int Idx = 0, IdxE = Values.size(); Idx != IdxE; ++Idx) {
Value *V = Values[Idx].first;
if (isa<Constant>(V)) {
// Since this is a function pass, it doesn't make semantic sense to
// walk the users of a subclass of Constant. The users could be in
// another function, or even another module that happens to be in
// the same LLVMContext.
continue;
}
// Calculate the absolute lane, using the minimum relative lane of LHS
// and RHS as base and Idx as the offset.
int Ln = std::min(LHS.second, RHS.second) + Idx;
assert(Ln >= 0 && "Bad lane calculation");
unsigned UsersBudget = LookAheadUsersBudget;
for (User *U : V->users()) {
if (const TreeEntry *UserTE = R.getTreeEntry(U)) {
// The user is in the VectorizableTree. Check if we need to insert.
auto It = llvm::find(UserTE->Scalars, U);
assert(It != UserTE->Scalars.end() && "U is in UserTE");
int UserLn = std::distance(UserTE->Scalars.begin(), It);
assert(UserLn >= 0 && "Bad lane");
if (UserLn != Ln)
Cost += UserInDiffLaneCost;
} else {
// Check if the user is in the look-ahead code.
auto It2 = InLookAheadValues.find(U);
if (It2 != InLookAheadValues.end()) {
// The user is in the look-ahead code. Check the lane.
if (It2->second != Ln)
Cost += UserInDiffLaneCost;
} else {
// The user is neither in SLP tree nor in the look-ahead code.
Cost += ExternalUseCost;
}
}
// Limit the number of visited uses to cap compilation time.
if (--UsersBudget == 0)
break;
}
}
return Cost;
}
/// Go through the operands of \p LHS and \p RHS recursively until \p
/// MaxLevel, and return the cummulative score. 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 VLOperands::ScoreConsecutiveLoads, while
/// {A[0],C[0]} has a score of VLOperands::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(const std::pair<Value *, int> &LHS,
const std::pair<Value *, int> &RHS, int CurrLevel,
int MaxLevel) {
Value *V1 = LHS.first;
Value *V2 = RHS.first;
// Get the shallow score of V1 and V2.
int ShallowScoreAtThisLevel =
std::max((int)ScoreFail, getShallowScore(V1, V2, DL, SE) -
getExternalUsesCost(LHS, RHS));
int Lane1 = LHS.second;
int Lane2 = RHS.second;
// If reached MaxLevel,
// or if V1 and V2 are not instructions,
// or if they are SPLAT,
// or if they are not consecutive, early return the current cost.
auto *I1 = dyn_cast<Instruction>(V1);
auto *I2 = dyn_cast<Instruction>(V2);
if (CurrLevel == MaxLevel || !(I1 && I2) || I1 == I2 ||
ShallowScoreAtThisLevel == VLOperands::ScoreFail ||
(isa<LoadInst>(I1) && isa<LoadInst>(I2) && ShallowScoreAtThisLevel))
return ShallowScoreAtThisLevel;
assert(I1 && I2 && "Should have early exited.");
// Keep track of in-tree values for determining the external-use cost.
InLookAheadValues[V1] = Lane1;
InLookAheadValues[V2] = Lane2;
// 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 possbile
// 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), Lane1},
{I2->getOperand(OpIdx2), Lane2},
CurrLevel + 1, MaxLevel);
// Look for the best score.
if (TmpScore > VLOperands::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;
}
/// \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(const std::pair<Value *, int> &LHS,
const std::pair<Value *, int> &RHS) {
InLookAheadValues.clear();
return getScoreAtLevelRec(LHS, RHS, 1, LookAheadMaxDepth);
}
// 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 None.
Optional<unsigned>
getBestOperand(unsigned OpIdx, int Lane, int LastLane,
ArrayRef<ReorderingMode> ReorderingModes) {
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];
// 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 {
Optional<unsigned> Idx = None;
unsigned Score = 0;
} BestOp;
// 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::Constant:
case ReorderingMode::Opcode: {
bool LeftToRight = Lane > LastLane;
Value *OpLeft = (LeftToRight) ? OpLastLane : Op;
Value *OpRight = (LeftToRight) ? Op : OpLastLane;
unsigned Score =
getLookAheadScore({OpLeft, LastLane}, {OpRight, Lane});
if (Score > BestOp.Score) {
BestOp.Idx = Idx;
BestOp.Score = Score;
}
break;
}
case ReorderingMode::Splat:
if (Op == OpLastLane)
BestOp.Idx = Idx;
break;
case ReorderingMode::Failed:
return None;
}
}
if (BestOp.Idx) {
getData(BestOp.Idx.getValue(), Lane).IsUsed = true;
return BestOp.Idx;
}
// If we could not find a good match return None.
return None;
}
/// 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.
unsigned getBestLaneToStartReordering() const {
unsigned BestLane = 0;
unsigned Min = UINT_MAX;
for (unsigned Lane = 0, NumLanes = getNumLanes(); Lane != NumLanes;
++Lane) {
unsigned NumFreeOps = getMaxNumOperandsThatCanBeReordered(Lane);
if (NumFreeOps < Min) {
Min = NumFreeOps;
BestLane = Lane;
}
}
return BestLane;
}
/// \Returns the maximum number of operands that are allowed to be reordered
/// for \p Lane. This is used as a heuristic for selecting the first lane to
/// start operand reordering.
unsigned 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.
for (unsigned OpIdx = 0; OpIdx != NumOperands; ++OpIdx)
if (getData(OpIdx, Lane).APO)
++CntTrue;
unsigned CntFalse = NumOperands - CntTrue;
return std::max(CntTrue, CntFalse);
}
/// 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();
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.
/// 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;
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;
if (Data.V == Op) {
FoundCandidate = true;
Data.IsUsed = true;
break;
}
}
if (!FoundCandidate)
return false;
}
return true;
}
public:
/// Initialize with all the operands of the instruction vector \p RootVL.
VLOperands(ArrayRef<Value *> RootVL, const DataLayout &DL,
ScalarEvolution &SE, const BoUpSLP &R)
: DL(DL), SE(SE), R(R) {
// 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 (isa<Instruction>(OpLane0)) {
// Check if OpLane0 should be broadcast.
if (shouldBroadcast(OpLane0, 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;
}
// 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) {
// 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.
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;
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].
Optional<unsigned> BestIdx =
getBestOperand(OpIdx, Lane, LastLane, ReorderingModes);
// 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.getValue(), Lane);
} else {
// We failed to find a best operand, set mode to 'Failed'.
ReorderingModes[OpIdx] = ReorderingMode::Failed;
// Enable the second pass.
StrategyFailed = true;
}
}
}
}
// 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
};
/// Checks if the instruction is marked for deletion.
bool isDeleted(Instruction *I) const { return DeletedInstructions.count(I); }
/// Marks values operands for later deletion by replacing them with Undefs.
void eraseInstructions(ArrayRef<Value *> AV);
~BoUpSLP();
private:
/// Checks if all users of \p I are the part of the vectorization tree.
bool areAllUsersVectorized(Instruction *I) const;
/// \returns the cost of the vectorizable entry.
InstructionCost getEntryCost(TreeEntry *E);
/// 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.
bool canReuseExtract(ArrayRef<Value *> VL, Value *OpValue,
SmallVectorImpl<unsigned> &CurrentOrder) const;
/// Vectorize a single entry in the tree.
Value *vectorizeTree(TreeEntry *E);
/// Vectorize a single entry in the tree, starting in \p VL.
Value *vectorizeTree(ArrayRef<Value *> VL);
/// \returns the scalarization cost for this type. Scalarization in this
/// context means the creation of vectors from a group of scalars.
InstructionCost
getGatherCost(FixedVectorType *Ty,
const DenseSet<unsigned> &ShuffledIndices) const;
/// \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.
InstructionCost getGatherCost(ArrayRef<Value *> VL) const;
/// Set the Builder insert point to one after the last instruction in
/// the bundle
void setInsertPointAfterBundle(TreeEntry *E);
/// \returns a vector from a collection of scalars in \p VL.
Value *gather(ArrayRef<Value *> VL);
/// \returns whether the VectorizableTree is fully vectorizable and will
/// be beneficial even the tree height is tiny.
bool isFullyVectorizableTinyTree() const;
/// 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 DataLayout &DL,
ScalarEvolution &SE,
const BoUpSLP &R);
struct TreeEntry {
using VecTreeTy = SmallVector<std::unique_ptr<TreeEntry>, 8>;
TreeEntry(VecTreeTy &Container) : Container(Container) {}
/// \returns true if the scalars in VL are equal to this entry.
bool isSame(ArrayRef<Value *> VL) const {
if (VL.size() == Scalars.size())
return std::equal(VL.begin(), VL.end(), Scalars.begin());
return VL.size() == ReuseShuffleIndices.size() &&
std::equal(
VL.begin(), VL.end(), ReuseShuffleIndices.begin(),
[this](Value *V, int Idx) { return V == Scalars[Idx]; });
}
/// A vector of scalars.
ValueList Scalars;
/// The Scalars are vectorized into this value. It is initialized to Null.
Value *VectorizedValue = 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, ScatterVectorize, NeedToGather };
EntryState State;
/// 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;
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].size() == 0 && "Already resized?");
Operands[OpIdx].resize(Scalars.size());
for (unsigned Lane = 0, E = Scalars.size(); Lane != E; ++Lane)
Operands[OpIdx][Lane] = OpVL[Lane];
}
/// 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);
}
}
}
/// \returns the \p OpIdx operand of this TreeEntry.
ValueList &getOperand(unsigned OpIdx) {
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 getOpcode() != getAltOpcode();
}
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;
}
/// Update operations state of this entry if reorder occurred.
bool updateStateIfReorder() {
if (ReorderIndices.empty())
return false;
InstructionsState S = getSameOpcode(Scalars, ReorderIndices.front());
setOperations(S);
return true;
}
#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 NeedToGather:
dbgs() << "NeedToGather\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 (unsigned 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(TreeEntry *E, InstructionCost ReuseShuffleCost,
InstructionCost VecCost,
InstructionCost ScalarCost) const {
dbgs() << "SLP: Calculated costs for Tree:\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, Optional<ScheduleData *> Bundle,
const InstructionsState &S,
const EdgeInfo &UserTreeIdx,
ArrayRef<unsigned> ReuseShuffleIndices = None,
ArrayRef<unsigned> ReorderIndices = None) {
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,
Optional<ScheduleData *> Bundle,
const InstructionsState &S,
const EdgeInfo &UserTreeIdx,
ArrayRef<unsigned> ReuseShuffleIndices = None,
ArrayRef<unsigned> ReorderIndices = None) {
assert(((!Bundle && EntryState == TreeEntry::NeedToGather) ||
(Bundle && EntryState != TreeEntry::NeedToGather)) &&
"Need to vectorize gather entry?");
VectorizableTree.push_back(std::make_unique<TreeEntry>(VectorizableTree));
TreeEntry *Last = VectorizableTree.back().get();
Last->Idx = VectorizableTree.size() - 1;
Last->Scalars.insert(Last->Scalars.begin(), VL.begin(), VL.end());
Last->State = EntryState;
Last->ReuseShuffleIndices.append(ReuseShuffleIndices.begin(),
ReuseShuffleIndices.end());
Last->ReorderIndices.append(ReorderIndices.begin(), ReorderIndices.end());
Last->setOperations(S);
if (Last->State != TreeEntry::NeedToGather) {
for (Value *V : VL) {
assert(!getTreeEntry(V) && "Scalar already in tree!");
ScalarToTreeEntry[V] = Last;
}
// Update the scheduler bundle to point to this TreeEntry.
unsigned Lane = 0;
for (ScheduleData *BundleMember = Bundle.getValue(); BundleMember;
BundleMember = BundleMember->NextInBundle) {
BundleMember->TE = Last;
BundleMember->Lane = Lane;
++Lane;
}
assert((!Bundle.getValue() || Lane == VL.size()) &&
"Bundle and VL out of sync");
} else {
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);
}
/// Maps a specific scalar to its tree entry.
SmallDenseMap<Value*, TreeEntry *> ScalarToTreeEntry;
/// 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;
/// 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) {
// First check if the result is already in the cache.
AliasCacheKey key = std::make_pair(Inst1, Inst2);
Optional<bool> &result = AliasCache[key];
if (result.hasValue()) {
return result.getValue();
}
MemoryLocation Loc2 = getLocation(Inst2, AA);
bool aliased = true;
if (Loc1.Ptr && Loc2.Ptr && isSimple(Inst1) && isSimple(Inst2)) {
// Do the alias check.
aliased = AA->alias(Loc1, Loc2);
}
// Store the result in the cache.
result = aliased;
return aliased;
}
using AliasCacheKey = std::pair<Instruction *, Instruction *>;
/// Cache for alias results.
/// TODO: consider moving this to the AliasAnalysis itself.
DenseMap<AliasCacheKey, Optional<bool>> AliasCache;
/// 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.
/// This 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.
void eraseInstruction(Instruction *I, bool ReplaceOpsWithUndef = false) {
auto It = DeletedInstructions.try_emplace(I, ReplaceOpsWithUndef).first;
It->getSecond() = It->getSecond() && ReplaceOpsWithUndef;
}
/// Temporary store for deleted instructions. Instructions will be deleted
/// eventually when the BoUpSLP is destructed.
DenseMap<Instruction *, bool> DeletedInstructions;
/// 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;
/// Values used only by @llvm.assume calls.
SmallPtrSet<const Value *, 32> EphValues;
/// Holds all of the instructions that we gathered.
SetVector<Instruction *> GatherSeq;
/// A list of blocks that we are going to CSE.
SetVector<BasicBlock *> CSEBlocks;
/// 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, Value *OpVal) {
FirstInBundle = this;
NextInBundle = nullptr;
NextLoadStore = nullptr;
IsScheduled = false;
SchedulingRegionID = BlockSchedulingRegionID;
UnscheduledDepsInBundle = UnscheduledDeps;
clearDependencies();
OpValue = OpVal;
TE = nullptr;
Lane = -1;
}
/// Returns true if the dependency information has been calculated.
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;
}
/// 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, also updating it for
/// the whole bundle.
int incrementUnscheduledDeps(int Incr) {
UnscheduledDeps += Incr;
return FirstInBundle->UnscheduledDepsInBundle += Incr;
}
/// Sets the number of unscheduled dependencies to the number of
/// dependencies.
void resetUnscheduledDeps() {
incrementUnscheduledDeps(Dependencies - UnscheduledDeps);
}
/// Clears all dependency information.
void clearDependencies() {
Dependencies = InvalidDeps;
resetUnscheduledDeps();
MemoryDependencies.clear();
}
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;
/// 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;
/// 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;
/// The sum of UnscheduledDeps in a bundle. Equals to UnscheduledDeps for
/// single instructions.
int UnscheduledDepsInBundle = InvalidDeps;
/// True if this instruction is scheduled (or considered as scheduled in the
/// dry-run).
bool IsScheduled = false;
/// Opcode of the current instruction in the schedule data.
Value *OpValue = nullptr;
/// The TreeEntry that this instruction corresponds to.
TreeEntry *TE = nullptr;
/// The lane of this node in the TreeEntry.
int Lane = -1;
};
#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.
struct BlockScheduling {
BlockScheduling(BasicBlock *BB)
: BB(BB), ChunkSize(BB->size()), ChunkPos(ChunkSize) {}
void clear() {
ReadyInsts.clear();
ScheduleStart = nullptr;
ScheduleEnd = nullptr;
FirstLoadStoreInRegion = nullptr;
LastLoadStoreInRegion = nullptr;
// 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(Value *V) {
ScheduleData *SD = ScheduleDataMap[V];
if (SD && SD->SchedulingRegionID == SchedulingRegionID)
return SD;
return nullptr;
}
ScheduleData *getScheduleData(Value *V, Value *Key) {
if (V == Key)
return getScheduleData(V);
auto I = ExtraScheduleDataMap.find(V);
if (I != ExtraScheduleDataMap.end()) {
ScheduleData *SD = I->second[Key];
if (SD && SD->SchedulingRegionID == SchedulingRegionID)
return SD;
}
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");
ScheduleData *BundleMember = SD;
while (BundleMember) {
if (BundleMember->Inst != BundleMember->OpValue) {
BundleMember = BundleMember->NextInBundle;
continue;
}
// Handle the def-use chain dependencies.
// Decrement the unscheduled counter and insert to ready list if ready.
auto &&DecrUnsched = [this, &ReadyList](Instruction *I) {
doForAllOpcodes(I, [&ReadyList](ScheduleData *OpDef) {
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 duiring buildTree(). We therefore need to get its operands
// through the TreeEntry.
if (TreeEntry *TE = BundleMember->TE) {
int Lane = BundleMember->Lane;
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 = TE->getMainOp();
assert(In &&
(isa<ExtractValueInst>(In) || isa<ExtractElementInst>(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->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");
}
}
BundleMember = BundleMember->NextInBundle;
}
}
void doForAllOpcodes(Value *V,
function_ref<void(ScheduleData *SD)> Action) {
if (ScheduleData *SD = getScheduleData(V))
Action(SD);
auto I = ExtraScheduleDataMap.find(V);
if (I != ExtraScheduleDataMap.end())
for (auto &P : I->second)
if (P.second->SchedulingRegionID == SchedulingRegionID)
Action(P.second);
}
/// 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()) {
doForAllOpcodes(I, [&](ScheduleData *SD) {
if (SD->isSchedulingEntity() && SD->isReady()) {
ReadyList.insert(SD);
LLVM_DEBUG(dbgs()
<< "SLP: initially in ready list: " << *I << "\n");
}
});
}
}
/// 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 non-None
/// if \p VL is allowed to be scheduled.
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.
std::vector<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<Value *, ScheduleData *> ScheduleDataMap;
/// Attaches ScheduleData to Instruction with the leading key.
DenseMap<Value *, SmallDenseMap<Value *, ScheduleData *>>
ExtraScheduleDataMap;
struct ReadyList : SmallVector<ScheduleData *, 8> {
void insert(ScheduleData *SD) { push_back(SD); }
};
/// The ready-list for scheduling (only used for the dry-run).
ReadyList 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;
/// 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.
ArrayRef<Value *> UserIgnoreList;
/// 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;
}
};
/// Contains orders of operations along with the number of bundles that have
/// operations in this order. It stores only those orders that require
/// reordering, if reordering is not required it is counted using \a
/// NumOpsWantToKeepOriginalOrder.
DenseMap<OrdersType, unsigned, OrdersTypeDenseMapInfo> NumOpsWantToKeepOrder;
/// Number of bundles that do not require reordering.
unsigned NumOpsWantToKeepOriginalOrder = 0;
// Analysis and block reference.
Function *F;
ScalarEvolution *SE;
TargetTransformInfo *TTI;
TargetLibraryInfo *TLI;
AAResults *AA;
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<> 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.
MapVector<Value *, std::pair<uint64_t, bool>> MinBWs;
};
} // 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);
if (isSplat(Entry->Scalars)) {
OS << "<splat> " << *Entry->Scalars[0];
return Str;
}
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->State == TreeEntry::NeedToGather)
return "color=red";
return "";
}
};
} // end namespace llvm