Google Git
Sign in
llvm/llvm-project/llvm/e792d67e0739c3ffa8108174e5767aa83d275025/./lib/Transforms/Vectorize/VPlanTransforms.cpp
blob: 0fa411450ea9245ab09b149bc67bffb6ba3da507 [file]
//===-- VPlanTransforms.cpp - Utility VPlan to VPlan transforms -----------===//
//
// 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
//
//===----------------------------------------------------------------------===//
///
/// \file
/// This file implements a set of utility VPlan to VPlan transformations.
///
//===----------------------------------------------------------------------===//
#include "VPlanTransforms.h"
#include "VPRecipeBuilder.h"
#include "VPlan.h"
#include "VPlanAnalysis.h"
#include "VPlanCFG.h"
#include "VPlanDominatorTree.h"
#include "VPlanHelpers.h"
#include "VPlanPatternMatch.h"
#include "VPlanUtils.h"
#include "VPlanVerifier.h"
#include "llvm/ADT/APInt.h"
#include "llvm/ADT/PostOrderIterator.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SetOperations.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/TypeSwitch.h"
#include "llvm/Analysis/IVDescriptors.h"
#include "llvm/Analysis/InstSimplifyFolder.h"
#include "llvm/Analysis/Loads.h"
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/Analysis/MemoryLocation.h"
#include "llvm/Analysis/ScalarEvolutionPatternMatch.h"
#include "llvm/Analysis/ScopedNoAliasAA.h"
#include "llvm/Analysis/VectorUtils.h"
#include "llvm/IR/Intrinsics.h"
#include "llvm/IR/MDBuilder.h"
#include "llvm/IR/Metadata.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/TypeSize.h"
#include "llvm/Transforms/Utils/LoopUtils.h"
#include "llvm/Transforms/Utils/ScalarEvolutionExpander.h"
using namespace llvm;
using namespace VPlanPatternMatch;
using namespace SCEVPatternMatch;
bool VPlanTransforms::tryToConvertVPInstructionsToVPRecipes(
VPlan &Plan, const TargetLibraryInfo &TLI) {
ReversePostOrderTraversal<VPBlockDeepTraversalWrapper<VPBlockBase *>> RPOT(
Plan.getVectorLoopRegion());
for (VPBasicBlock *VPBB : VPBlockUtils::blocksOnly<VPBasicBlock>(RPOT)) {
// Skip blocks outside region
if (!VPBB->getParent())
break;
VPRecipeBase *Term = VPBB->getTerminator();
auto EndIter = Term ? Term->getIterator() : VPBB->end();
// Introduce each ingredient into VPlan.
for (VPRecipeBase &Ingredient :
make_early_inc_range(make_range(VPBB->begin(), EndIter))) {
VPValue *VPV = Ingredient.getVPSingleValue();
if (!VPV->getUnderlyingValue())
continue;
Instruction *Inst = cast<Instruction>(VPV->getUnderlyingValue());
VPRecipeBase *NewRecipe = nullptr;
if (auto *PhiR = dyn_cast<VPPhi>(&Ingredient)) {
auto *Phi = cast<PHINode>(PhiR->getUnderlyingValue());
NewRecipe = new VPWidenPHIRecipe(PhiR->operands(), PhiR->getDebugLoc(),
Phi->getName());
} else if (auto *VPI = dyn_cast<VPInstruction>(&Ingredient)) {
assert(!isa<PHINode>(Inst) && "phis should be handled above");
// Create VPWidenMemoryRecipe for loads and stores.
if (LoadInst *Load = dyn_cast<LoadInst>(Inst)) {
NewRecipe = new VPWidenLoadRecipe(
*Load, Ingredient.getOperand(0), nullptr /*Mask*/,
false /*Consecutive*/, *VPI, Ingredient.getDebugLoc());
} else if (StoreInst *Store = dyn_cast<StoreInst>(Inst)) {
NewRecipe = new VPWidenStoreRecipe(
*Store, Ingredient.getOperand(1), Ingredient.getOperand(0),
nullptr /*Mask*/, false /*Consecutive*/, *VPI,
Ingredient.getDebugLoc());
} else if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Inst)) {
NewRecipe = new VPWidenGEPRecipe(GEP->getSourceElementType(),
Ingredient.operands(), *VPI,
Ingredient.getDebugLoc(), GEP);
} else if (CallInst *CI = dyn_cast<CallInst>(Inst)) {
Intrinsic::ID VectorID = getVectorIntrinsicIDForCall(CI, &TLI);
if (VectorID == Intrinsic::not_intrinsic)
return false;
// The noalias.scope.decl intrinsic declares a noalias scope that
// is valid for a single iteration. Emitting it as a single-scalar
// replicate would incorrectly extend the scope across multiple
// original iterations packed into one vector iteration.
// FIXME: If we want to vectorize this loop, then we have to drop
// all the associated !alias.scope and !noalias.
if (VectorID == Intrinsic::experimental_noalias_scope_decl)
return false;
// These intrinsics are recognized by getVectorIntrinsicIDForCall
// but are not widenable. Emit them as replicate instead of widening.
if (VectorID == Intrinsic::assume ||
VectorID == Intrinsic::lifetime_end ||
VectorID == Intrinsic::lifetime_start ||
VectorID == Intrinsic::sideeffect ||
VectorID == Intrinsic::pseudoprobe) {
// If the operand of llvm.assume holds before vectorization, it will
// also hold per lane.
// llvm.pseudoprobe requires to be duplicated per lane for accurate
// sample count.
const bool IsSingleScalar = VectorID != Intrinsic::assume &&
VectorID != Intrinsic::pseudoprobe;
NewRecipe = new VPReplicateRecipe(CI, Ingredient.operands(),
/*IsSingleScalar=*/IsSingleScalar,
/*Mask=*/nullptr, *VPI, *VPI,
Ingredient.getDebugLoc());
} else {
NewRecipe = new VPWidenIntrinsicRecipe(
*CI, VectorID, drop_end(Ingredient.operands()), CI->getType(),
VPIRFlags(*CI), *VPI, CI->getDebugLoc());
}
} else if (auto *CI = dyn_cast<CastInst>(Inst)) {
NewRecipe = new VPWidenCastRecipe(
CI->getOpcode(), Ingredient.getOperand(0), CI->getType(), CI,
VPIRFlags(*CI), VPIRMetadata(*CI));
} else {
NewRecipe = new VPWidenRecipe(*Inst, Ingredient.operands(), *VPI,
*VPI, Ingredient.getDebugLoc());
}
} else {
assert(isa<VPWidenIntOrFpInductionRecipe>(&Ingredient) &&
"inductions must be created earlier");
continue;
}
NewRecipe->insertBefore(&Ingredient);
if (NewRecipe->getNumDefinedValues() == 1)
VPV->replaceAllUsesWith(NewRecipe->getVPSingleValue());
else
assert(NewRecipe->getNumDefinedValues() == 0 &&
"Only recpies with zero or one defined values expected");
Ingredient.eraseFromParent();
}
}
return true;
}
/// Helper for extra no-alias checks via known-safe recipe and SCEV.
class SinkStoreInfo {
const SmallPtrSetImpl<VPRecipeBase *> &ExcludeRecipes;
VPReplicateRecipe &GroupLeader;
PredicatedScalarEvolution &PSE;
const Loop &L;
// Return true if \p A and \p B are known to not alias for all VFs in the
// plan, checked via the distance between the accesses
bool isNoAliasViaDistance(VPReplicateRecipe *A, VPReplicateRecipe *B) const {
if (A->getOpcode() != Instruction::Store ||
B->getOpcode() != Instruction::Store)
return false;
VPValue *AddrA = A->getOperand(1);
const SCEV *SCEVA = vputils::getSCEVExprForVPValue(AddrA, PSE, &L);
VPValue *AddrB = B->getOperand(1);
const SCEV *SCEVB = vputils::getSCEVExprForVPValue(AddrB, PSE, &L);
if (isa<SCEVCouldNotCompute>(SCEVA) || isa<SCEVCouldNotCompute>(SCEVB))
return false;
const APInt *Distance;
ScalarEvolution &SE = *PSE.getSE();
if (!match(SE.getMinusSCEV(SCEVA, SCEVB), m_scev_APInt(Distance)))
return false;
const DataLayout &DL = SE.getDataLayout();
Type *TyA = A->getOperand(0)->getScalarType();
uint64_t SizeA = DL.getTypeStoreSize(TyA);
Type *TyB = B->getOperand(0)->getScalarType();
uint64_t SizeB = DL.getTypeStoreSize(TyB);
// Use the maximum store size to ensure no overlap from either direction.
// Currently only handles fixed sizes, as it is only used for
// replicating VPReplicateRecipes.
uint64_t MaxStoreSize = std::max(SizeA, SizeB);
auto VFs = B->getParent()->getPlan()->vectorFactors();
ElementCount MaxVF = *max_element(VFs, ElementCount::isKnownLT);
if (MaxVF.isScalable())
return false;
return Distance->abs().uge(
MaxVF.multiplyCoefficientBy(MaxStoreSize).getFixedValue());
}
public:
SinkStoreInfo(const SmallPtrSetImpl<VPRecipeBase *> &ExcludeRecipes,
VPReplicateRecipe &GroupLeader, PredicatedScalarEvolution &PSE,
const Loop &L)
: ExcludeRecipes(ExcludeRecipes), GroupLeader(GroupLeader), PSE(PSE),
L(L) {}
/// Return true if \p R should be skipped during alias checking, either
/// because it's in the exclude set or because no-alias can be proven via
/// SCEV.
bool shouldSkip(VPRecipeBase &R) const {
auto *Store = dyn_cast<VPReplicateRecipe>(&R);
return ExcludeRecipes.contains(&R) ||
(Store && isNoAliasViaDistance(Store, &GroupLeader));
}
};
/// Check if a memory operation doesn't alias with memory operations using
/// scoped noalias metadata, in blocks in the single-successor chain between \p
/// FirstBB and \p LastBB. If \p SinkInfo is std::nullopt, only recipes that may
/// write to memory are checked (for load hoisting). Otherwise recipes that both
/// read and write memory are checked, and SCEV is used to prove no-alias
/// between the group leader and other replicate recipes (for store sinking).
static bool
canHoistOrSinkWithNoAliasCheck(const MemoryLocation &MemLoc,
VPBasicBlock *FirstBB, VPBasicBlock *LastBB,
std::optional<SinkStoreInfo> SinkInfo = {}) {
bool CheckReads = SinkInfo.has_value();
if (!MemLoc.AATags.Scope)
return false;
for (VPBasicBlock *VPBB :
VPBlockUtils::blocksInSingleSuccessorChainBetween(FirstBB, LastBB)) {
for (VPRecipeBase &R : *VPBB) {
if (SinkInfo && SinkInfo->shouldSkip(R))
continue;
// Skip recipes that don't need checking.
if (!R.mayWriteToMemory() && !(CheckReads && R.mayReadFromMemory()))
continue;
auto Loc = vputils::getMemoryLocation(R);
if (!Loc)
// Conservatively assume aliasing for memory operations without
// location.
return false;
if (ScopedNoAliasAAResult::alias(*Loc, MemLoc) != AliasResult::NoAlias)
return false;
}
}
return true;
}
/// Get the value type of the replicate load or store. \p IsLoad indicates
/// whether it is a load.
static Type *getLoadStoreValueType(VPReplicateRecipe *R, bool IsLoad) {
return (IsLoad ? R : R->getOperand(0))->getScalarType();
}
/// Collect either replicated Loads or Stores grouped by their address SCEV and
/// their load-store type, in a deep-traversal of the vector loop region in \p
/// Plan.
template <unsigned Opcode>
static SmallVector<SmallVector<VPReplicateRecipe *, 4>>
collectGroupedReplicateMemOps(
VPlan &Plan, PredicatedScalarEvolution &PSE, const Loop *L,
function_ref<bool(VPReplicateRecipe *)> FilterFn) {
static_assert(Opcode == Instruction::Load || Opcode == Instruction::Store,
"Only Load and Store opcodes supported");
constexpr bool IsLoad = (Opcode == Instruction::Load);
SmallDenseMap<std::pair<const SCEV *, const Type *>,
SmallVector<VPReplicateRecipe *, 4>>
RecipesByAddressAndType;
for (VPBasicBlock *VPBB : VPBlockUtils::blocksOnly<VPBasicBlock>(
vp_depth_first_deep(Plan.getVectorLoopRegion()->getEntry()))) {
for (VPRecipeBase &R : *VPBB) {
auto *RepR = dyn_cast<VPReplicateRecipe>(&R);
if (!RepR || RepR->getOpcode() != Opcode || !FilterFn(RepR))
continue;
// For loads, operand 0 is address; for stores, operand 1 is address.
VPValue *Addr = RepR->getOperand(IsLoad ? 0 : 1);
const Type *LoadStoreTy = getLoadStoreValueType(RepR, IsLoad);
const SCEV *AddrSCEV = vputils::getSCEVExprForVPValue(Addr, PSE, L);
if (!isa<SCEVCouldNotCompute>(AddrSCEV))
RecipesByAddressAndType[{AddrSCEV, LoadStoreTy}].push_back(RepR);
}
}
auto Groups = to_vector(RecipesByAddressAndType.values());
VPDominatorTree VPDT(Plan);
for (auto &Group : Groups) {
// Sort mem ops by dominance order, with earliest (most dominating) first.
stable_sort(Group, [&VPDT](VPReplicateRecipe *A, VPReplicateRecipe *B) {
return VPDT.properlyDominates(A, B);
});
}
return Groups;
}
static bool sinkScalarOperands(VPlan &Plan) {
auto Iter = vp_depth_first_deep(Plan.getEntry());
bool ScalarVFOnly = Plan.hasScalarVFOnly();
bool Changed = false;
SetVector<std::pair<VPBasicBlock *, VPSingleDefRecipe *>> WorkList;
auto InsertIfValidSinkCandidate = [ScalarVFOnly, &WorkList](
VPBasicBlock *SinkTo, VPValue *Op) {
auto *Candidate =
dyn_cast_or_null<VPSingleDefRecipe>(Op->getDefiningRecipe());
if (!Candidate)
return;
// We only know how to sink VPReplicateRecipes and VPScalarIVStepsRecipes
// for now.
if (!isa<VPReplicateRecipe, VPScalarIVStepsRecipe>(Candidate))
return;
if (Candidate->getParent() == SinkTo ||
vputils::cannotHoistOrSinkRecipe(*Candidate, /*Sinking=*/true))
return;
if (auto *RepR = dyn_cast<VPReplicateRecipe>(Candidate))
if (!ScalarVFOnly && RepR->isSingleScalar())
return;
WorkList.insert({SinkTo, Candidate});
};
// First, collect the operands of all recipes in replicate blocks as seeds for
// sinking.
for (VPRegionBlock *VPR : VPBlockUtils::blocksOnly<VPRegionBlock>(Iter)) {
VPBasicBlock *EntryVPBB = VPR->getEntryBasicBlock();
if (!VPR->isReplicator() || EntryVPBB->getSuccessors().size() != 2)
continue;
VPBasicBlock *VPBB = cast<VPBasicBlock>(EntryVPBB->getSuccessors().front());
if (VPBB->getSingleSuccessor() != VPR->getExitingBasicBlock())
continue;
for (auto &Recipe : *VPBB)
for (VPValue *Op : Recipe.operands())
InsertIfValidSinkCandidate(VPBB, Op);
}
// Try to sink each replicate or scalar IV steps recipe in the worklist.
for (unsigned I = 0; I != WorkList.size(); ++I) {
VPBasicBlock *SinkTo;
VPSingleDefRecipe *SinkCandidate;
std::tie(SinkTo, SinkCandidate) = WorkList[I];
// All recipe users of SinkCandidate must be in the same block SinkTo or all
// users outside of SinkTo must only use the first lane of SinkCandidate. In
// the latter case, we need to duplicate SinkCandidate.
auto UsersOutsideSinkTo =
make_filter_range(SinkCandidate->users(), [SinkTo](VPUser *U) {
return cast<VPRecipeBase>(U)->getParent() != SinkTo;
});
if (any_of(UsersOutsideSinkTo, [SinkCandidate](VPUser *U) {
return !U->usesFirstLaneOnly(SinkCandidate);
}))
continue;
bool NeedsDuplicating = !UsersOutsideSinkTo.empty();
if (NeedsDuplicating) {
if (ScalarVFOnly)
continue;
VPSingleDefRecipe *Clone;
if (auto *SinkCandidateRepR =
dyn_cast<VPReplicateRecipe>(SinkCandidate)) {
// TODO: Handle converting to uniform recipes as separate transform,
// then cloning should be sufficient here.
Instruction *I = SinkCandidate->getUnderlyingInstr();
Clone = new VPReplicateRecipe(I, SinkCandidate->operands(), true,
nullptr /*Mask*/, *SinkCandidateRepR,
*SinkCandidateRepR);
// TODO: add ".cloned" suffix to name of Clone's VPValue.
} else {
Clone = SinkCandidate->clone();
}
Clone->insertBefore(SinkCandidate);
SinkCandidate->replaceUsesWithIf(Clone, [SinkTo](VPUser &U, unsigned) {
return cast<VPRecipeBase>(&U)->getParent() != SinkTo;
});
}
SinkCandidate->moveBefore(*SinkTo, SinkTo->getFirstNonPhi());
for (VPValue *Op : SinkCandidate->operands())
InsertIfValidSinkCandidate(SinkTo, Op);
Changed = true;
}
return Changed;
}
/// If \p R is a region with a VPBranchOnMaskRecipe in the entry block, return
/// the mask.
static VPValue *getPredicatedMask(VPRegionBlock *R) {
auto *EntryBB = dyn_cast<VPBasicBlock>(R->getEntry());
if (!EntryBB || EntryBB->size() != 1 ||
!isa<VPBranchOnMaskRecipe>(EntryBB->begin()))
return nullptr;
return cast<VPBranchOnMaskRecipe>(&*EntryBB->begin())->getOperand(0);
}
/// If \p R is a triangle region, return the 'then' block of the triangle.
static VPBasicBlock *getPredicatedThenBlock(VPRegionBlock *R) {
auto *EntryBB = cast<VPBasicBlock>(R->getEntry());
if (EntryBB->getNumSuccessors() != 2)
return nullptr;
auto *Succ0 = dyn_cast<VPBasicBlock>(EntryBB->getSuccessors()[0]);
auto *Succ1 = dyn_cast<VPBasicBlock>(EntryBB->getSuccessors()[1]);
if (!Succ0 || !Succ1)
return nullptr;
if (Succ0->getNumSuccessors() + Succ1->getNumSuccessors() != 1)
return nullptr;
if (Succ0->getSingleSuccessor() == Succ1)
return Succ0;
if (Succ1->getSingleSuccessor() == Succ0)
return Succ1;
return nullptr;
}
// Merge replicate regions in their successor region, if a replicate region
// is connected to a successor replicate region with the same predicate by a
// single, empty VPBasicBlock.
static bool mergeReplicateRegionsIntoSuccessors(VPlan &Plan) {
SmallPtrSet<VPRegionBlock *, 4> TransformedRegions;
// Collect replicate regions followed by an empty block, followed by another
// replicate region with matching masks to process front. This is to avoid
// iterator invalidation issues while merging regions.
SmallVector<VPRegionBlock *, 8> WorkList;
for (VPRegionBlock *Region1 : VPBlockUtils::blocksOnly<VPRegionBlock>(
vp_depth_first_deep(Plan.getEntry()))) {
if (!Region1->isReplicator())
continue;
auto *MiddleBasicBlock =
dyn_cast_or_null<VPBasicBlock>(Region1->getSingleSuccessor());
if (!MiddleBasicBlock || !MiddleBasicBlock->empty())
continue;
auto *Region2 =
dyn_cast_or_null<VPRegionBlock>(MiddleBasicBlock->getSingleSuccessor());
if (!Region2 || !Region2->isReplicator())
continue;
VPValue *Mask1 = getPredicatedMask(Region1);
VPValue *Mask2 = getPredicatedMask(Region2);
if (!Mask1 || Mask1 != Mask2)
continue;
assert(Mask1 && Mask2 && "both region must have conditions");
WorkList.push_back(Region1);
}
// Move recipes from Region1 to its successor region, if both are triangles.
for (VPRegionBlock *Region1 : WorkList) {
if (TransformedRegions.contains(Region1))
continue;
auto *MiddleBasicBlock = cast<VPBasicBlock>(Region1->getSingleSuccessor());
auto *Region2 = cast<VPRegionBlock>(MiddleBasicBlock->getSingleSuccessor());
VPBasicBlock *Then1 = getPredicatedThenBlock(Region1);
VPBasicBlock *Then2 = getPredicatedThenBlock(Region2);
if (!Then1 || !Then2)
continue;
// Note: No fusion-preventing memory dependencies are expected in either
// region. Such dependencies should be rejected during earlier dependence
// checks, which guarantee accesses can be re-ordered for vectorization.
//
// Move recipes to the successor region.
for (VPRecipeBase &ToMove : make_early_inc_range(reverse(*Then1)))
ToMove.moveBefore(*Then2, Then2->getFirstNonPhi());
auto *Merge1 = cast<VPBasicBlock>(Then1->getSingleSuccessor());
auto *Merge2 = cast<VPBasicBlock>(Then2->getSingleSuccessor());
// Move VPPredInstPHIRecipes from the merge block to the successor region's
// merge block. Update all users inside the successor region to use the
// original values.
for (VPRecipeBase &Phi1ToMove : make_early_inc_range(reverse(*Merge1))) {
VPValue *PredInst1 =
cast<VPPredInstPHIRecipe>(&Phi1ToMove)->getOperand(0);
VPValue *Phi1ToMoveV = Phi1ToMove.getVPSingleValue();
Phi1ToMoveV->replaceUsesWithIf(PredInst1, [Then2](VPUser &U, unsigned) {
return cast<VPRecipeBase>(&U)->getParent() == Then2;
});
// Remove phi recipes that are unused after merging the regions.
if (Phi1ToMove.getVPSingleValue()->getNumUsers() == 0) {
Phi1ToMove.eraseFromParent();
continue;
}
Phi1ToMove.moveBefore(*Merge2, Merge2->begin());
}
// Remove the dead recipes in Region1's entry block.
for (VPRecipeBase &R :
make_early_inc_range(reverse(*Region1->getEntryBasicBlock())))
R.eraseFromParent();
// Finally, remove the first region.
for (VPBlockBase *Pred : make_early_inc_range(Region1->getPredecessors())) {
VPBlockUtils::disconnectBlocks(Pred, Region1);
VPBlockUtils::connectBlocks(Pred, MiddleBasicBlock);
}
VPBlockUtils::disconnectBlocks(Region1, MiddleBasicBlock);
TransformedRegions.insert(Region1);
}
return !TransformedRegions.empty();
}
static VPRegionBlock *createReplicateRegion(VPReplicateRecipe *PredRecipe,
VPRegionBlock *ParentRegion,
VPlan &Plan) {
Instruction *Instr = PredRecipe->getUnderlyingInstr();
// Build the triangular if-then region.
std::string RegionName = (Twine("pred.") + Instr->getOpcodeName()).str();
assert(Instr->getParent() && "Predicated instruction not in any basic block");
auto *BlockInMask = PredRecipe->getMask();
auto *MaskDef = BlockInMask->getDefiningRecipe();
auto *BOMRecipe = new VPBranchOnMaskRecipe(
BlockInMask, MaskDef ? MaskDef->getDebugLoc() : DebugLoc::getUnknown());
auto *Entry =
Plan.createVPBasicBlock(Twine(RegionName) + ".entry", BOMRecipe);
// Replace predicated replicate recipe with a replicate recipe without a
// mask but in the replicate region.
auto *RecipeWithoutMask = new VPReplicateRecipe(
PredRecipe->getUnderlyingInstr(), PredRecipe->operandsWithoutMask(),
PredRecipe->isSingleScalar(), nullptr /*Mask*/, *PredRecipe, *PredRecipe,
PredRecipe->getDebugLoc());
auto *Pred =
Plan.createVPBasicBlock(Twine(RegionName) + ".if", RecipeWithoutMask);
auto *Exiting = Plan.createVPBasicBlock(Twine(RegionName) + ".continue");
VPRegionBlock *Region =
Plan.createReplicateRegion(Entry, Exiting, RegionName);
// Note: first set Entry as region entry and then connect successors starting
// from it in order, to propagate the "parent" of each VPBasicBlock.
Region->setParent(ParentRegion);
VPBlockUtils::insertTwoBlocksAfter(Pred, Exiting, Entry);
VPBlockUtils::connectBlocks(Pred, Exiting);
if (PredRecipe->getNumUsers() != 0) {
auto *PHIRecipe = new VPPredInstPHIRecipe(RecipeWithoutMask,
RecipeWithoutMask->getDebugLoc());
Exiting->appendRecipe(PHIRecipe);
PredRecipe->replaceAllUsesWith(PHIRecipe);
}
PredRecipe->eraseFromParent();
return Region;
}
static void addReplicateRegions(VPlan &Plan) {
SmallVector<VPReplicateRecipe *> WorkList;
for (VPBasicBlock *VPBB : VPBlockUtils::blocksOnly<VPBasicBlock>(
vp_depth_first_deep(Plan.getEntry()))) {
for (VPRecipeBase &R : *VPBB)
if (auto *RepR = dyn_cast<VPReplicateRecipe>(&R)) {
if (RepR->isPredicated())
WorkList.push_back(RepR);
}
}
unsigned BBNum = 0;
for (VPReplicateRecipe *RepR : WorkList) {
VPBasicBlock *CurrentBlock = RepR->getParent();
VPBasicBlock *SplitBlock = CurrentBlock->splitAt(RepR->getIterator());
BasicBlock *OrigBB = RepR->getUnderlyingInstr()->getParent();
SplitBlock->setName(
OrigBB->hasName() ? OrigBB->getName() + "." + Twine(BBNum++) : "");
// Record predicated instructions for above packing optimizations.
VPRegionBlock *Region =
createReplicateRegion(RepR, CurrentBlock->getParent(), Plan);
VPBlockUtils::insertOnEdge(CurrentBlock, SplitBlock, Region);
VPRegionBlock *ParentRegion = Region->getParent();
if (ParentRegion && ParentRegion->getExiting() == CurrentBlock)
ParentRegion->setExiting(SplitBlock);
}
}
bool VPlanTransforms::mergeBlocksIntoPredecessors(VPlan &Plan) {
SmallVector<VPBasicBlock *> WorkList;
for (VPBasicBlock *VPBB : VPBlockUtils::blocksOnly<VPBasicBlock>(
vp_depth_first_deep(Plan.getEntry()))) {
// Don't fold the blocks in the skeleton of the Plan into their single
// predecessors for now.
// TODO: Remove restriction once more of the skeleton is modeled in VPlan.
if (!VPBB->getParent())
continue;
auto *PredVPBB =
dyn_cast_or_null<VPBasicBlock>(VPBB->getSinglePredecessor());
if (!PredVPBB || PredVPBB->getNumSuccessors() != 1 ||
isa<VPIRBasicBlock>(PredVPBB))
continue;
WorkList.push_back(VPBB);
}
for (VPBasicBlock *VPBB : WorkList) {
VPBasicBlock *PredVPBB = cast<VPBasicBlock>(VPBB->getSinglePredecessor());
for (VPRecipeBase &R : make_early_inc_range(*VPBB))
R.moveBefore(*PredVPBB, PredVPBB->end());
VPBlockUtils::disconnectBlocks(PredVPBB, VPBB);
auto *ParentRegion = VPBB->getParent();
if (ParentRegion && ParentRegion->getExiting() == VPBB)
ParentRegion->setExiting(PredVPBB);
VPBlockUtils::transferSuccessors(VPBB, PredVPBB);
// VPBB is now dead and will be cleaned up when the plan gets destroyed.
}
return !WorkList.empty();
}
void VPlanTransforms::createAndOptimizeReplicateRegions(VPlan &Plan) {
// Convert masked VPReplicateRecipes to if-then region blocks.
addReplicateRegions(Plan);
bool ShouldSimplify = true;
while (ShouldSimplify) {
ShouldSimplify = sinkScalarOperands(Plan);
ShouldSimplify |= mergeReplicateRegionsIntoSuccessors(Plan);
ShouldSimplify |= mergeBlocksIntoPredecessors(Plan);
}
}
/// Remove redundant casts of inductions.
///
/// Such redundant casts are casts of induction variables that can be ignored,
/// because we already proved that the casted phi is equal to the uncasted phi
/// in the vectorized loop. There is no need to vectorize the cast - the same
/// value can be used for both the phi and casts in the vector loop.
static void removeRedundantInductionCasts(VPlan &Plan) {
for (auto &Phi : Plan.getVectorLoopRegion()->getEntryBasicBlock()->phis()) {
auto *IV = dyn_cast<VPWidenIntOrFpInductionRecipe>(&Phi);
if (!IV || IV->getTruncInst())
continue;
// A sequence of IR Casts has potentially been recorded for IV, which
// *must be bypassed* when the IV is vectorized, because the vectorized IV
// will produce the desired casted value. This sequence forms a def-use
// chain and is provided in reverse order, ending with the cast that uses
// the IV phi. Search for the recipe of the last cast in the chain and
// replace it with the original IV. Note that only the final cast is
// expected to have users outside the cast-chain and the dead casts left
// over will be cleaned up later.
ArrayRef<Instruction *> Casts = IV->getInductionDescriptor().getCastInsts();
VPValue *FindMyCast = IV;
for (Instruction *IRCast : reverse(Casts)) {
VPSingleDefRecipe *FoundUserCast = nullptr;
for (auto *U : FindMyCast->users()) {
auto *UserCast = dyn_cast<VPSingleDefRecipe>(U);
if (UserCast && UserCast->getUnderlyingValue() == IRCast) {
FoundUserCast = UserCast;
break;
}
}
// A cast recipe in the chain may have been removed by earlier DCE.
if (!FoundUserCast)
break;
FindMyCast = FoundUserCast;
}
if (FindMyCast != IV)
FindMyCast->replaceAllUsesWith(IV);
}
}
static VPScalarIVStepsRecipe *
createScalarIVSteps(VPlan &Plan, InductionDescriptor::InductionKind Kind,
Instruction::BinaryOps InductionOpcode,
FPMathOperator *FPBinOp, Instruction *TruncI,
VPIRValue *StartV, VPValue *Step, DebugLoc DL,
VPBuilder &Builder) {
VPRegionBlock *LoopRegion = Plan.getVectorLoopRegion();
VPBasicBlock *HeaderVPBB = LoopRegion->getEntryBasicBlock();
VPValue *CanonicalIV = LoopRegion->getCanonicalIV();
VPSingleDefRecipe *BaseIV =
Builder.createDerivedIV(Kind, FPBinOp, StartV, CanonicalIV, Step);
// Truncate base induction if needed.
Type *ResultTy = BaseIV->getScalarType();
if (TruncI) {
Type *TruncTy = TruncI->getType();
assert(ResultTy->getScalarSizeInBits() > TruncTy->getScalarSizeInBits() &&
"Not truncating.");
assert(ResultTy->isIntegerTy() && "Truncation requires an integer type");
BaseIV = Builder.createScalarCast(Instruction::Trunc, BaseIV, TruncTy, DL);
ResultTy = TruncTy;
}
// Truncate step if needed.
Type *StepTy = Step->getScalarType();
if (ResultTy != StepTy) {
assert(StepTy->getScalarSizeInBits() > ResultTy->getScalarSizeInBits() &&
"Not truncating.");
assert(StepTy->isIntegerTy() && "Truncation requires an integer type");
auto *VecPreheader =
cast<VPBasicBlock>(HeaderVPBB->getSingleHierarchicalPredecessor());
VPBuilder::InsertPointGuard Guard(Builder);
Builder.setInsertPoint(VecPreheader);
Step = Builder.createScalarCast(Instruction::Trunc, Step, ResultTy, DL);
}
return Builder.createScalarIVSteps(InductionOpcode, FPBinOp, BaseIV, Step,
&Plan.getVF(), DL);
}
void VPlanTransforms::replaceWideCanonicalIVWithWideIV(
VPlan &Plan, ScalarEvolution &SE, const TargetTransformInfo &TTI,
TargetTransformInfo::TargetCostKind CostKind, ElementCount VF, unsigned UF,
const SmallPtrSetImpl<const Value *> &ValuesToIgnore) {
VPRegionBlock *LoopRegion = Plan.getVectorLoopRegion();
if (!LoopRegion)
return;
auto *WideCanIV =
findUserOf<VPWidenCanonicalIVRecipe>(LoopRegion->getCanonicalIV());
if (!WideCanIV)
return;
Type *CanIVTy = LoopRegion->getCanonicalIVType();
// Replace the wide canonical IV with a scalar-iv-steps over the canonical
// IV.
if (Plan.hasScalarVFOnly() || vputils::onlyFirstLaneUsed(WideCanIV)) {
VPBuilder Builder(WideCanIV);
WideCanIV->replaceAllUsesWith(createScalarIVSteps(
Plan, InductionDescriptor::IK_IntInduction, Instruction::Add, nullptr,
nullptr, Plan.getZero(CanIVTy), Plan.getConstantInt(CanIVTy, 1),
WideCanIV->getDebugLoc(), Builder));
WideCanIV->eraseFromParent();
return;
}
if (vputils::onlyScalarValuesUsed(WideCanIV))
return;
// If a canonical VPWidenIntOrFpInductionRecipe already produces vector lanes
// in the header, reuse it instead of introducing another wide induction phi.
VPBasicBlock *Header = LoopRegion->getEntryBasicBlock();
for (VPRecipeBase &Phi : Header->phis()) {
VPWidenIntOrFpInductionRecipe *WidenIV;
if (!match(&Phi, m_CanonicalWidenIV(WidenIV)))
continue;
// The reused wide IV feeds the header mask, whose lanes may extend past
// the trip count; drop flags that only hold inside the scalar loop.
WidenIV->dropPoisonGeneratingFlags();
WideCanIV->replaceAllUsesWith(WidenIV);
WideCanIV->eraseFromParent();
return;
}
// Introduce a new VPWidenIntOrFpInductionRecipe if profitable.
auto *VecTy = VectorType::get(CanIVTy, VF);
InstructionCost BroadcastCost = TTI.getShuffleCost(
TargetTransformInfo::SK_Broadcast, VecTy, VecTy, {}, CostKind);
InstructionCost PHICost = TTI.getCFInstrCost(Instruction::PHI, CostKind);
if (PHICost > BroadcastCost)
return;
// Bail out if the additional wide induction phi increase the expected spill
// cost.
VPRegisterUsage UnrolledBase =
calculateRegisterUsageForPlan(Plan, VF, TTI, ValuesToIgnore)[0];
for (unsigned &NumUsers : make_second_range(UnrolledBase.MaxLocalUsers))
NumUsers *= UF;
unsigned RegClass = TTI.getRegisterClassForType(/*Vector=*/true, VecTy);
VPRegisterUsage Projected = UnrolledBase;
Projected.MaxLocalUsers[RegClass] += TTI.getRegUsageForType(VecTy);
if (Projected.spillCost(TTI, CostKind) >
UnrolledBase.spillCost(TTI, CostKind))
return;
InductionDescriptor ID =
InductionDescriptor::getCanonicalIntInduction(CanIVTy, SE);
VPValue *StepV = Plan.getConstantInt(CanIVTy, 1);
auto *NewWideIV = new VPWidenIntOrFpInductionRecipe(
/*IV=*/nullptr, Plan.getZero(CanIVTy), StepV, &Plan.getVF(), ID,
WideCanIV->getNoWrapFlags(), WideCanIV->getDebugLoc());
NewWideIV->insertBefore(&*Header->getFirstNonPhi());
WideCanIV->replaceAllUsesWith(NewWideIV);
WideCanIV->eraseFromParent();
}
/// Returns true if \p R is dead and can be removed.
static bool isDeadRecipe(VPRecipeBase &R) {
// Do remove conditional assume instructions as their conditions may be
// flattened.
auto *RepR = dyn_cast<VPReplicateRecipe>(&R);
bool IsConditionalAssume = RepR && RepR->isPredicated() &&
match(RepR, m_Intrinsic<Intrinsic::assume>());
if (IsConditionalAssume)
return true;
if (R.mayHaveSideEffects())
return false;
// Recipe is dead if no user keeps the recipe alive.
return all_of(R.definedValues(),
[](VPValue *V) { return V->getNumUsers() == 0; });
}
void VPlanTransforms::removeDeadRecipes(VPlan &Plan) {
PostOrderTraversal<VPBlockDeepTraversalWrapper<VPBlockBase *>> POT(
Plan.getEntry());
for (VPBasicBlock *VPBB : VPBlockUtils::blocksOnly<VPBasicBlock>(POT)) {
// The recipes in the block are processed in reverse order, to catch chains
// of dead recipes.
for (VPRecipeBase &R : make_early_inc_range(reverse(*VPBB))) {
if (isDeadRecipe(R)) {
R.eraseFromParent();
continue;
}
// Check if R is a dead VPPhi <-> update cycle and remove it.
VPValue *Start, *Incoming;
if (!match(&R, m_VPPhi(m_VPValue(Start), m_VPValue(Incoming))))
continue;
auto *PhiR = cast<VPPhi>(&R);
VPUser *PhiUser = PhiR->getSingleUser();
if (!PhiUser)
continue;
if (PhiUser != Incoming->getDefiningRecipe() ||
Incoming->getNumUsers() != 1)
continue;
PhiR->replaceAllUsesWith(Start);
PhiR->eraseFromParent();
Incoming->getDefiningRecipe()->eraseFromParent();
}
}
}
static SmallVector<VPUser *> collectUsersRecursively(VPValue *V) {
SetVector<VPUser *> Users(llvm::from_range, V->users());
for (unsigned I = 0; I != Users.size(); ++I) {
VPRecipeBase *Cur = cast<VPRecipeBase>(Users[I]);
for (VPValue *V : Cur->definedValues())
Users.insert_range(V->users());
}
return Users.takeVector();
}
/// Scalarize a VPWidenPointerInductionRecipe by replacing it with a PtrAdd
/// (IndStart, ScalarIVSteps (0, Step)). This is used when the recipe only
/// generates scalar values.
static VPValue *
scalarizeVPWidenPointerInduction(VPWidenPointerInductionRecipe *PtrIV,
VPlan &Plan, VPBuilder &Builder) {
const InductionDescriptor &ID = PtrIV->getInductionDescriptor();
VPIRValue *StartV = Plan.getZero(ID.getStep()->getType());
VPValue *StepV = PtrIV->getOperand(1);
VPScalarIVStepsRecipe *Steps = createScalarIVSteps(
Plan, InductionDescriptor::IK_IntInduction, Instruction::Add, nullptr,
nullptr, StartV, StepV, PtrIV->getDebugLoc(), Builder);
return Builder.createPtrAdd(PtrIV->getStartValue(), Steps,
PtrIV->getDebugLoc(), "next.gep");
}
/// Legalize VPWidenPointerInductionRecipe, by replacing it with a PtrAdd
/// (IndStart, ScalarIVSteps (0, Step)) if only its scalar values are used, as
/// VPWidenPointerInductionRecipe will generate vectors only. If some users
/// require vectors while other require scalars, the scalar uses need to extract
/// the scalars from the generated vectors (Note that this is different to how
/// int/fp inductions are handled). Legalize extract-from-ends using uniform
/// VPReplicateRecipe of wide inductions to use regular VPReplicateRecipe, so
/// the correct end value is available. Also optimize
/// VPWidenIntOrFpInductionRecipe, if any of its users needs scalar values, by
/// providing them scalar steps built on the canonical scalar IV and update the
/// original IV's users. This is an optional optimization to reduce the needs of
/// vector extracts.
static void legalizeAndOptimizeInductions(VPlan &Plan) {
VPBasicBlock *HeaderVPBB = Plan.getVectorLoopRegion()->getEntryBasicBlock();
bool HasOnlyVectorVFs = !Plan.hasScalarVFOnly();
VPBuilder Builder(HeaderVPBB, HeaderVPBB->getFirstNonPhi());
for (VPRecipeBase &Phi : HeaderVPBB->phis()) {
auto *PhiR = dyn_cast<VPWidenInductionRecipe>(&Phi);
if (!PhiR)
continue;
// Try to narrow wide and replicating recipes to uniform recipes, based on
// VPlan analysis.
// TODO: Apply to all recipes in the future, to replace legacy uniformity
// analysis.
auto Users = collectUsersRecursively(PhiR);
for (VPUser *U : reverse(Users)) {
auto *Def = dyn_cast<VPRecipeWithIRFlags>(U);
auto *RepR = dyn_cast<VPReplicateRecipe>(U);
// Skip recipes that shouldn't be narrowed.
if (!Def || !isa<VPReplicateRecipe, VPWidenRecipe>(Def) ||
Def->getNumUsers() == 0 || !Def->getUnderlyingValue() ||
(RepR && (RepR->isSingleScalar() || RepR->isPredicated())))
continue;
// Skip recipes that may have other lanes than their first used.
if (!vputils::isSingleScalar(Def) && !vputils::onlyFirstLaneUsed(Def))
continue;
// TODO: Support scalarizing ExtractValue.
if (match(Def,
m_Binary<Instruction::ExtractValue>(m_VPValue(), m_VPValue())))
continue;
auto *Clone = new VPReplicateRecipe(Def->getUnderlyingInstr(),
Def->operands(), /*IsUniform*/ true,
/*Mask*/ nullptr, /*Flags*/ *Def);
Clone->insertAfter(Def);
Def->replaceAllUsesWith(Clone);
}
// Replace wide pointer inductions which have only their scalars used by
// PtrAdd(IndStart, ScalarIVSteps (0, Step)).
if (auto *PtrIV = dyn_cast<VPWidenPointerInductionRecipe>(&Phi)) {
if (!Plan.hasScalarVFOnly() &&
!PtrIV->onlyScalarsGenerated(Plan.hasScalableVF()))
continue;
VPValue *PtrAdd = scalarizeVPWidenPointerInduction(PtrIV, Plan, Builder);
PtrIV->replaceAllUsesWith(PtrAdd);
continue;
}
// Replace widened induction with scalar steps for users that only use
// scalars.
auto *WideIV = cast<VPWidenIntOrFpInductionRecipe>(&Phi);
if (HasOnlyVectorVFs && none_of(WideIV->users(), [WideIV](VPUser *U) {
return U->usesScalars(WideIV);
}))
continue;
const InductionDescriptor &ID = WideIV->getInductionDescriptor();
VPScalarIVStepsRecipe *Steps = createScalarIVSteps(
Plan, ID.getKind(), ID.getInductionOpcode(),
dyn_cast_or_null<FPMathOperator>(ID.getInductionBinOp()),
WideIV->getTruncInst(), WideIV->getStartValue(), WideIV->getStepValue(),
WideIV->getDebugLoc(), Builder);
// Update scalar users of IV to use Step instead.
if (!HasOnlyVectorVFs) {
assert(!Plan.hasScalableVF() &&
"plans containing a scalar VF cannot also include scalable VFs");
WideIV->replaceAllUsesWith(Steps);
} else {
bool HasScalableVF = Plan.hasScalableVF();
WideIV->replaceUsesWithIf(Steps,
[WideIV, HasScalableVF](VPUser &U, unsigned) {
if (HasScalableVF)
return U.usesFirstLaneOnly(WideIV);
return U.usesScalars(WideIV);
});
}
}
}
/// Check if \p VPV is an untruncated wide induction, either before or after the
/// increment. If so return the header IV (before the increment), otherwise
/// return null.
static VPWidenInductionRecipe *
getOptimizableIVOf(VPValue *VPV, PredicatedScalarEvolution &PSE) {
auto *WideIV = dyn_cast<VPWidenInductionRecipe>(VPV);
if (WideIV) {
// VPV itself is a wide induction, separately compute the end value for exit
// users if it is not a truncated IV.
auto *IntOrFpIV = dyn_cast<VPWidenIntOrFpInductionRecipe>(WideIV);
return (IntOrFpIV && IntOrFpIV->getTruncInst()) ? nullptr : WideIV;
}
// Check if VPV is an optimizable induction increment.
VPRecipeBase *Def = VPV->getDefiningRecipe();
if (!Def || Def->getNumOperands() != 2)
return nullptr;
WideIV = dyn_cast<VPWidenInductionRecipe>(Def->getOperand(0));
if (!WideIV)
WideIV = dyn_cast<VPWidenInductionRecipe>(Def->getOperand(1));
if (!WideIV)
return nullptr;
auto IsWideIVInc = [&]() {
auto &ID = WideIV->getInductionDescriptor();
// Check if VPV increments the induction by the induction step.
VPValue *IVStep = WideIV->getStepValue();
switch (ID.getInductionOpcode()) {
case Instruction::Add:
return match(VPV, m_c_Add(m_Specific(WideIV), m_Specific(IVStep)));
case Instruction::FAdd:
return match(VPV, m_c_FAdd(m_Specific(WideIV), m_Specific(IVStep)));
case Instruction::FSub:
return match(VPV, m_Binary<Instruction::FSub>(m_Specific(WideIV),
m_Specific(IVStep)));
case Instruction::Sub: {
// IVStep will be the negated step of the subtraction. Check if Step == -1
// * IVStep.
VPValue *Step;
if (!match(VPV, m_Sub(m_VPValue(), m_VPValue(Step))))
return false;
const SCEV *IVStepSCEV = vputils::getSCEVExprForVPValue(IVStep, PSE);
const SCEV *StepSCEV = vputils::getSCEVExprForVPValue(Step, PSE);
ScalarEvolution &SE = *PSE.getSE();
return !isa<SCEVCouldNotCompute>(IVStepSCEV) &&
!isa<SCEVCouldNotCompute>(StepSCEV) &&
IVStepSCEV == SE.getNegativeSCEV(StepSCEV);
}
default:
return ID.getKind() == InductionDescriptor::IK_PtrInduction &&
match(VPV, m_GetElementPtr(m_Specific(WideIV),
m_Specific(WideIV->getStepValue())));
}
llvm_unreachable("should have been covered by switch above");
};
return IsWideIVInc() ? WideIV : nullptr;
}
/// Attempts to optimize the induction variable exit values for users in the
/// early exit block.
static VPValue *optimizeEarlyExitInductionUser(VPlan &Plan, VPValue *Op,
PredicatedScalarEvolution &PSE) {
VPValue *Incoming, *Mask;
if (!match(Op, m_ExtractLane(m_FirstActiveLane(m_VPValue(Mask)),
m_VPValue(Incoming))))
return nullptr;
auto *WideIV = getOptimizableIVOf(Incoming, PSE);
if (!WideIV)
return nullptr;
auto *WideIntOrFp = dyn_cast<VPWidenIntOrFpInductionRecipe>(WideIV);
if (WideIntOrFp && WideIntOrFp->getTruncInst())
return nullptr;
// Calculate the final index.
VPRegionBlock *LoopRegion = Plan.getVectorLoopRegion();
auto *CanonicalIV = LoopRegion->getCanonicalIV();
Type *CanonicalIVType = LoopRegion->getCanonicalIVType();
auto *ExtractR = cast<VPInstruction>(Op);
VPBuilder B(ExtractR);
DebugLoc DL = ExtractR->getDebugLoc();
VPValue *FirstActiveLane = B.createFirstActiveLane(Mask, DL);
FirstActiveLane = B.createScalarZExtOrTrunc(
FirstActiveLane, CanonicalIVType, FirstActiveLane->getScalarType(), DL);
VPValue *EndValue = B.createAdd(CanonicalIV, FirstActiveLane, DL);
// `getOptimizableIVOf()` always returns the pre-incremented IV, so if it
// changed it means the exit is using the incremented value, so we need to
// add the step.
if (Incoming != WideIV) {
VPValue *One = Plan.getConstantInt(CanonicalIVType, 1);
EndValue = B.createAdd(EndValue, One, DL);
}
if (!match(WideIV, m_CanonicalWidenIV())) {
const InductionDescriptor &ID = WideIV->getInductionDescriptor();
VPIRValue *Start = WideIV->getStartValue();
VPValue *Step = WideIV->getStepValue();
EndValue = B.createDerivedIV(
ID.getKind(), dyn_cast_or_null<FPMathOperator>(ID.getInductionBinOp()),
Start, EndValue, Step);
}
return EndValue;
}
/// Compute the end value for \p WideIV, unless it is truncated. Creates a
/// VPDerivedIVRecipe for non-canonical inductions.
static VPValue *tryToComputeEndValueForInduction(VPWidenInductionRecipe *WideIV,
VPBuilder &VectorPHBuilder,
VPValue *VectorTC) {
auto *WideIntOrFp = dyn_cast<VPWidenIntOrFpInductionRecipe>(WideIV);
// Truncated wide inductions resume from the last lane of their vector value
// in the last vector iteration which is handled elsewhere.
if (WideIntOrFp && WideIntOrFp->getTruncInst())
return nullptr;
VPIRValue *Start = WideIV->getStartValue();
VPValue *Step = WideIV->getStepValue();
const InductionDescriptor &ID = WideIV->getInductionDescriptor();
VPValue *EndValue = VectorTC;
if (!match(WideIV, m_CanonicalWidenIV())) {
EndValue = VectorPHBuilder.createDerivedIV(
ID.getKind(), dyn_cast_or_null<FPMathOperator>(ID.getInductionBinOp()),
Start, VectorTC, Step);
}
// EndValue is derived from the vector trip count (which has the same type as
// the widest induction) and thus may be wider than the induction here.
Type *ScalarTypeOfWideIV = WideIV->getScalarType();
if (ScalarTypeOfWideIV != EndValue->getScalarType()) {
EndValue = VectorPHBuilder.createScalarCast(Instruction::Trunc, EndValue,
ScalarTypeOfWideIV,
WideIV->getDebugLoc());
}
return EndValue;
}
/// Attempts to optimize the induction variable exit values for users in the
/// exit block coming from the latch in the original scalar loop.
static VPValue *
optimizeLatchExitInductionUser(VPlan &Plan, VPValue *Op,
DenseMap<VPValue *, VPValue *> &EndValues,
PredicatedScalarEvolution &PSE) {
VPValue *Incoming;
if (!match(Op, m_ExtractLastLaneOfLastPart(m_VPValue(Incoming))))
return nullptr;
VPWidenInductionRecipe *WideIV = getOptimizableIVOf(Incoming, PSE);
if (!WideIV)
return nullptr;
VPValue *EndValue = EndValues.lookup(WideIV);
assert(EndValue && "Must have computed the end value up front");
// `getOptimizableIVOf()` always returns the pre-incremented IV, so if it
// changed it means the exit is using the incremented value, so we don't
// need to subtract the step.
if (Incoming != WideIV)
return EndValue;
// Otherwise, subtract the step from the EndValue.
auto *ExtractR = cast<VPInstruction>(Op);
VPBuilder B(ExtractR);
VPValue *Step = WideIV->getStepValue();
Type *ScalarTy = WideIV->getScalarType();
if (ScalarTy->isIntegerTy())
return B.createSub(EndValue, Step, DebugLoc::getUnknown(), "ind.escape");
if (ScalarTy->isPointerTy()) {
Type *StepTy = Step->getScalarType();
auto *Zero = Plan.getZero(StepTy);
return B.createPtrAdd(EndValue, B.createSub(Zero, Step),
DebugLoc::getUnknown(), "ind.escape");
}
if (ScalarTy->isFloatingPointTy()) {
const auto &ID = WideIV->getInductionDescriptor();
return B.createNaryOp(
ID.getInductionBinOp()->getOpcode() == Instruction::FAdd
? Instruction::FSub
: Instruction::FAdd,
{EndValue, Step}, {ID.getInductionBinOp()->getFastMathFlags()});
}
llvm_unreachable("all possible induction types must be handled");
return nullptr;
}
void VPlanTransforms::optimizeInductionLiveOutUsers(
VPlan &Plan, PredicatedScalarEvolution &PSE, bool FoldTail) {
// Compute end values for all inductions.
VPRegionBlock *VectorRegion = Plan.getVectorLoopRegion();
auto *VectorPH = cast<VPBasicBlock>(VectorRegion->getSinglePredecessor());
VPBuilder VectorPHBuilder(VectorPH, VectorPH->begin());
DenseMap<VPValue *, VPValue *> EndValues;
VPValue *ResumeTC =
FoldTail ? Plan.getTripCount() : &Plan.getVectorTripCount();
for (auto &Phi : VectorRegion->getEntryBasicBlock()->phis()) {
auto *WideIV = dyn_cast<VPWidenInductionRecipe>(&Phi);
if (!WideIV)
continue;
if (VPValue *EndValue =
tryToComputeEndValueForInduction(WideIV, VectorPHBuilder, ResumeTC))
EndValues[WideIV] = EndValue;
}
VPBasicBlock *MiddleVPBB = Plan.getMiddleBlock();
for (VPRecipeBase &R : make_early_inc_range(*MiddleVPBB)) {
VPValue *Op;
if (!match(&R, m_ExitingIVValue(m_VPValue(Op))))
continue;
auto *WideIV = cast<VPWidenInductionRecipe>(Op);
if (VPValue *EndValue = EndValues.lookup(WideIV)) {
R.getVPSingleValue()->replaceAllUsesWith(EndValue);
R.eraseFromParent();
}
}
// Then, optimize exit block users.
for (VPIRBasicBlock *ExitVPBB : Plan.getExitBlocks()) {
for (VPRecipeBase &R : ExitVPBB->phis()) {
auto *ExitIRI = cast<VPIRPhi>(&R);
for (auto [Idx, PredVPBB] : enumerate(ExitVPBB->getPredecessors())) {
VPValue *Escape = nullptr;
if (PredVPBB == MiddleVPBB)
Escape = optimizeLatchExitInductionUser(
Plan, ExitIRI->getOperand(Idx), EndValues, PSE);
else
Escape = optimizeEarlyExitInductionUser(
Plan, ExitIRI->getOperand(Idx), PSE);
if (Escape)
ExitIRI->setOperand(Idx, Escape);
}
}
}
}
/// Remove redundant ExpandSCEVRecipes in \p Plan's entry block by replacing
/// them with already existing recipes expanding the same SCEV expression.
static void removeRedundantExpandSCEVRecipes(VPlan &Plan) {
DenseMap<const SCEV *, VPValue *> SCEV2VPV;
for (VPRecipeBase &R :
make_early_inc_range(*Plan.getEntry()->getEntryBasicBlock())) {
auto *ExpR = dyn_cast<VPExpandSCEVRecipe>(&R);
if (!ExpR)
continue;
const auto &[V, Inserted] = SCEV2VPV.try_emplace(ExpR->getSCEV(), ExpR);
if (Inserted)
continue;
ExpR->replaceAllUsesWith(V->second);
if (ExpR == Plan.getTripCount())
Plan.resetTripCount(V->second);
ExpR->eraseFromParent();
}
}
static void recursivelyDeleteDeadRecipes(VPValue *V) {
SmallVector<VPValue *> WorkList;
SmallPtrSet<VPValue *, 8> Seen;
WorkList.push_back(V);
while (!WorkList.empty()) {
VPValue *Cur = WorkList.pop_back_val();
if (!Seen.insert(Cur).second)
continue;
VPRecipeBase *R = Cur->getDefiningRecipe();
if (!R)
continue;
if (!isDeadRecipe(*R))
continue;
append_range(WorkList, R->operands());
R->eraseFromParent();
}
}
/// Get any instruction opcode or intrinsic ID data embedded in recipe \p R.
/// Returns an optional pair, where the first element indicates whether it is
/// an intrinsic ID.
static std::optional<std::pair<bool, unsigned>>
getOpcodeOrIntrinsicID(const VPSingleDefRecipe *R) {
return TypeSwitch<const VPSingleDefRecipe *,
std::optional<std::pair<bool, unsigned>>>(R)
.Case<VPInstruction, VPWidenRecipe, VPWidenCastRecipe, VPWidenGEPRecipe,
VPReplicateRecipe>(
[](auto *I) { return std::make_pair(false, I->getOpcode()); })
.Case([](const VPWidenIntrinsicRecipe *I) {
return std::make_pair(true, I->getVectorIntrinsicID());
})
.Case<VPVectorPointerRecipe, VPPredInstPHIRecipe, VPScalarIVStepsRecipe>(
[](auto *I) {
// For recipes that do not directly map to LLVM IR instructions,
// assign opcodes after the last VPInstruction opcode (which is also
// after the last IR Instruction opcode), based on the VPRecipeID.
return std::make_pair(false, VPInstruction::OpsEnd + 1 +
I->getVPRecipeID());
})
.Default([](auto *) { return std::nullopt; });
}
/// Try to fold \p R using InstSimplifyFolder. Will succeed and return a
/// non-nullptr VPValue for a handled opcode or intrinsic ID if corresponding \p
/// Operands are foldable live-ins.
static VPIRValue *tryToFoldLiveIns(VPSingleDefRecipe &R,
ArrayRef<VPValue *> Operands,
const DataLayout &DL, LLVMContext &Ctx) {
auto OpcodeOrIID = getOpcodeOrIntrinsicID(&R);
if (!OpcodeOrIID)
return nullptr;
SmallVector<Value *, 4> Ops;
for (VPValue *Op : Operands) {
if (!match(Op, m_LiveIn()))
return nullptr;
Value *V = Op->getUnderlyingValue();
if (!V)
return nullptr;
Ops.push_back(V);
}
auto FoldToIRValue = [&]() -> Value * {
InstSimplifyFolder Folder(DL);
if (OpcodeOrIID->first) {
if (R.getNumOperands() != 2)
return nullptr;
unsigned ID = OpcodeOrIID->second;
return Folder.FoldBinaryIntrinsic(ID, Ops[0], Ops[1], R.getScalarType());
}
unsigned Opcode = OpcodeOrIID->second;
if (Instruction::isBinaryOp(Opcode))
return Folder.FoldBinOp(static_cast<Instruction::BinaryOps>(Opcode),
Ops[0], Ops[1]);
if (Instruction::isCast(Opcode))
return Folder.FoldCast(static_cast<Instruction::CastOps>(Opcode), Ops[0],
R.getVPSingleValue()->getScalarType());
switch (Opcode) {
case VPInstruction::LogicalAnd:
return Folder.FoldSelect(Ops[0], Ops[1],
ConstantInt::getNullValue(Ops[1]->getType()));
case VPInstruction::Not:
return Folder.FoldBinOp(Instruction::BinaryOps::Xor, Ops[0],
Constant::getAllOnesValue(Ops[0]->getType()));
case Instruction::Select:
return Folder.FoldSelect(Ops[0], Ops[1], Ops[2]);
case Instruction::ICmp:
case Instruction::FCmp:
return Folder.FoldCmp(cast<VPRecipeWithIRFlags>(R).getPredicate(), Ops[0],
Ops[1]);
case Instruction::GetElementPtr: {
auto &RFlags = cast<VPRecipeWithIRFlags>(R);
auto *GEP = cast<GetElementPtrInst>(RFlags.getUnderlyingInstr());
return Folder.FoldGEP(GEP->getSourceElementType(), Ops[0],
drop_begin(Ops), RFlags.getGEPNoWrapFlags());
}
case VPInstruction::PtrAdd:
case VPInstruction::WidePtrAdd:
return Folder.FoldGEP(IntegerType::getInt8Ty(Ctx), Ops[0], Ops[1],
cast<VPRecipeWithIRFlags>(R).getGEPNoWrapFlags());
// An extract of a live-in is an extract of a broadcast, so return the
// broadcasted element.
case Instruction::ExtractElement:
assert(!Ops[0]->getType()->isVectorTy() && "Live-ins should be scalar");
return Ops[0];
}
return nullptr;
};
if (Value *V = FoldToIRValue())
return R.getParent()->getPlan()->getOrAddLiveIn(V);
return nullptr;
}
/// Try to simplify logical and bitwise recipes in \p Def.
static bool simplifyLogicalRecipe(VPSingleDefRecipe *Def, VPBuilder &Builder,
bool CanCreateNewRecipe) {
VPlan *Plan = Def->getParent()->getPlan();
// Simplify (X && Y) | (X && !Y) -> X.
// TODO: Split up into simpler, modular combines: (X && Y) | (X && Z) into X
// && (Y | Z) and (X | !X) into true. This requires queuing newly created
// recipes to be visited during simplification.
VPValue *X, *Y, *Z;
if (match(Def,
m_c_BinaryOr(m_LogicalAnd(m_VPValue(X), m_VPValue(Y)),
m_LogicalAnd(m_Deferred(X), m_Not(m_Deferred(Y)))))) {
Def->replaceAllUsesWith(X);
Def->eraseFromParent();
return true;
}
// x | AllOnes -> AllOnes
if (match(Def, m_c_BinaryOr(m_VPValue(X), m_AllOnes()))) {
Def->replaceAllUsesWith(Plan->getAllOnesValue(Def->getScalarType()));
return true;
}
// x | 0 -> x
if (match(Def, m_c_BinaryOr(m_VPValue(X), m_ZeroInt()))) {
Def->replaceAllUsesWith(X);
return true;
}
// x | !x -> AllOnes
if (match(Def, m_c_BinaryOr(m_VPValue(X), m_Not(m_Deferred(X))))) {
Def->replaceAllUsesWith(Plan->getAllOnesValue(Def->getScalarType()));
return true;
}
// x & 0 -> 0
if (match(Def, m_c_BinaryAnd(m_VPValue(X), m_ZeroInt()))) {
Def->replaceAllUsesWith(Plan->getZero(Def->getScalarType()));
return true;
}
// x & AllOnes -> x
if (match(Def, m_c_BinaryAnd(m_VPValue(X), m_AllOnes()))) {
Def->replaceAllUsesWith(X);
return true;
}
// x && false -> false
if (match(Def, m_c_LogicalAnd(m_VPValue(X), m_False()))) {
Def->replaceAllUsesWith(Plan->getFalse());
return true;
}
// x && true -> x
if (match(Def, m_c_LogicalAnd(m_VPValue(X), m_True()))) {
Def->replaceAllUsesWith(X);
return true;
}
// (x && y) | (x && z) -> x && (y | z)
if (CanCreateNewRecipe &&
match(Def, m_c_BinaryOr(m_LogicalAnd(m_VPValue(X), m_VPValue(Y)),
m_LogicalAnd(m_Deferred(X), m_VPValue(Z)))) &&
// Simplify only if one of the operands has one use to avoid creating an
// extra recipe.
(!Def->getOperand(0)->hasMoreThanOneUniqueUser() ||
!Def->getOperand(1)->hasMoreThanOneUniqueUser())) {
Def->replaceAllUsesWith(
Builder.createLogicalAnd(X, Builder.createOr(Y, Z)));
return true;
}
// x && (x && y) -> x && y
if (match(Def, m_LogicalAnd(m_VPValue(X),
m_LogicalAnd(m_Deferred(X), m_VPValue())))) {
Def->replaceAllUsesWith(Def->getOperand(1));
return true;
}
// x && (y && x) -> x && y
if (match(Def, m_LogicalAnd(m_VPValue(X),
m_LogicalAnd(m_VPValue(Y), m_Deferred(X))))) {
Def->replaceAllUsesWith(Builder.createLogicalAnd(X, Y));
return true;
}
// x && !x -> 0
if (match(Def, m_LogicalAnd(m_VPValue(X), m_Not(m_Deferred(X))))) {
Def->replaceAllUsesWith(Plan->getFalse());
return true;
}
if (match(Def, m_Select(m_VPValue(), m_VPValue(X), m_Deferred(X)))) {
Def->replaceAllUsesWith(X);
return true;
}
// select c, false, true -> not c
VPValue *C;
if (CanCreateNewRecipe &&
match(Def, m_Select(m_VPValue(C), m_False(), m_True()))) {
Def->replaceAllUsesWith(Builder.createNot(C));
return true;
}
// select !c, x, y -> select c, y, x
if (match(Def, m_Select(m_Not(m_VPValue(C)), m_VPValue(X), m_VPValue(Y)))) {
Def->setOperand(0, C);
Def->setOperand(1, Y);
Def->setOperand(2, X);
return true;
}
// select x, (i1 y | z), y -> y | (x && z)
if (CanCreateNewRecipe &&
match(Def, m_Select(m_VPValue(X),
m_OneUse(m_c_BinaryOr(m_VPValue(Y), m_VPValue(Z))),
m_Deferred(Y))) &&
Y->getScalarType()->isIntegerTy(1)) {
Def->replaceAllUsesWith(
Builder.createOr(Y, Builder.createLogicalAnd(X, Z)));
return true;
}
return false;
}
/// Try to simplify VPSingleDefRecipe \p Def.
static void simplifyRecipe(VPSingleDefRecipe *Def) {
VPlan *Plan = Def->getParent()->getPlan();
// Simplification of live-in IR values for SingleDef recipes using
// InstSimplifyFolder.
const DataLayout &DL = Plan->getDataLayout();
if (VPValue *V =
tryToFoldLiveIns(*Def, Def->operands(), DL, Plan->getContext()))
return Def->replaceAllUsesWith(V);
// Fold PredPHI LiveIn -> LiveIn.
if (auto *PredPHI = dyn_cast<VPPredInstPHIRecipe>(Def)) {
VPValue *Op = PredPHI->getOperand(0);
if (isa<VPIRValue>(Op))
PredPHI->replaceAllUsesWith(Op);
}
VPBuilder Builder(Def);
// Avoid replacing VPInstructions with underlying values with new
// VPInstructions, as we would fail to create widen/replicate recpes from the
// new VPInstructions without an underlying value, and miss out on some
// transformations that only apply to widened/replicated recipes later, by
// doing so.
// TODO: We should also not replace non-VPInstructions like VPWidenRecipe with
// VPInstructions without underlying values, as those will get skipped during
// cost computation.
bool CanCreateNewRecipe =
!isa<VPInstruction>(Def) || !Def->getUnderlyingValue();
VPValue *A;
if (match(Def, m_Trunc(m_ZExtOrSExt(m_VPValue(A))))) {
Type *TruncTy = Def->getScalarType();
Type *ATy = A->getScalarType();
if (TruncTy == ATy) {
Def->replaceAllUsesWith(A);
} else {
// Don't replace a non-widened cast recipe with a widened cast.
if (!isa<VPWidenCastRecipe>(Def))
return;
if (ATy->getScalarSizeInBits() < TruncTy->getScalarSizeInBits()) {
unsigned ExtOpcode = match(Def->getOperand(0), m_SExt(m_VPValue()))
? Instruction::SExt
: Instruction::ZExt;
auto *Ext = Builder.createWidenCast(Instruction::CastOps(ExtOpcode), A,
TruncTy);
if (auto *UnderlyingExt = Def->getOperand(0)->getUnderlyingValue()) {
// UnderlyingExt has distinct return type, used to retain legacy cost.
Ext->setUnderlyingValue(UnderlyingExt);
}
Def->replaceAllUsesWith(Ext);
} else if (ATy->getScalarSizeInBits() > TruncTy->getScalarSizeInBits()) {
auto *Trunc = Builder.createWidenCast(Instruction::Trunc, A, TruncTy);
Def->replaceAllUsesWith(Trunc);
}
}
}
if (simplifyLogicalRecipe(Def, Builder, CanCreateNewRecipe))
return;
VPValue *X, *Y, *C;
if (match(Def, m_c_Add(m_VPValue(A), m_ZeroInt())))
return Def->replaceAllUsesWith(A);
if (match(Def, m_c_Mul(m_VPValue(A), m_One())))
return Def->replaceAllUsesWith(A);
if (match(Def, m_c_Mul(m_VPValue(A), m_ZeroInt())))
return Def->replaceAllUsesWith(Plan->getZero(Def->getScalarType()));
if (CanCreateNewRecipe && match(Def, m_c_Mul(m_VPValue(A), m_AllOnes()))) {
// Preserve nsw from the Mul on the new Sub.
VPIRFlags::WrapFlagsTy NW = {
false, cast<VPRecipeWithIRFlags>(Def)->hasNoSignedWrap()};
return Def->replaceAllUsesWith(Builder.createSub(
Plan->getZero(A->getScalarType()), A, Def->getDebugLoc(), "", NW));
}
if (CanCreateNewRecipe &&
match(Def, m_c_Add(m_VPValue(X), m_Sub(m_ZeroInt(), m_VPValue(Y))))) {
// Preserve nsw from the Add and the Sub, if it's present on both, on the
// new Sub.
VPIRFlags::WrapFlagsTy NW = {
false,
cast<VPRecipeWithIRFlags>(Def)->hasNoSignedWrap() &&
cast<VPRecipeWithIRFlags>(Def->getOperand(Def->getOperand(0) == X))
->hasNoSignedWrap()};
return Def->replaceAllUsesWith(
Builder.createSub(X, Y, Def->getDebugLoc(), "", NW));
}
const APInt *APC;
if (CanCreateNewRecipe && match(Def, m_c_Mul(m_VPValue(A), m_APInt(APC))) &&
APC->isPowerOf2())
return Def->replaceAllUsesWith(Builder.createNaryOp(
Instruction::Shl,
{A, Plan->getConstantInt(APC->getBitWidth(), APC->exactLogBase2())},
*cast<VPRecipeWithIRFlags>(Def), Def->getDebugLoc()));
if (CanCreateNewRecipe && match(Def, m_UDiv(m_VPValue(A), m_APInt(APC))) &&
APC->isPowerOf2())
return Def->replaceAllUsesWith(Builder.createNaryOp(
Instruction::LShr,
{A, Plan->getConstantInt(APC->getBitWidth(), APC->exactLogBase2())},
*cast<VPRecipeWithIRFlags>(Def), Def->getDebugLoc()));
if (match(Def, m_Not(m_VPValue(A)))) {
if (match(A, m_Not(m_VPValue(A))))
return Def->replaceAllUsesWith(A);
// Try to fold Not into compares by adjusting the predicate in-place.
CmpPredicate Pred;
if (match(A, m_Cmp(Pred, m_VPValue(), m_VPValue()))) {
auto *Cmp = cast<VPRecipeWithIRFlags>(A);
if (all_of(Cmp->users(),
match_fn(m_CombineOr(
m_Not(m_Specific(Cmp)),
m_Select(m_Specific(Cmp), m_VPValue(), m_VPValue()))))) {
Cmp->setPredicate(CmpInst::getInversePredicate(Pred));
for (VPUser *U : to_vector(Cmp->users())) {
auto *R = cast<VPSingleDefRecipe>(U);
if (match(R, m_Select(m_Specific(Cmp), m_VPValue(X), m_VPValue(Y)))) {
// select (cmp pred), x, y -> select (cmp inv_pred), y, x
R->setOperand(1, Y);
R->setOperand(2, X);
} else {
// not (cmp pred) -> cmp inv_pred
assert(match(R, m_Not(m_Specific(Cmp))) && "Unexpected user");
R->replaceAllUsesWith(Cmp);
}
}
// If Cmp doesn't have a debug location, use the one from the negation,
// to preserve the location.
if (!Cmp->getDebugLoc() && Def->getDebugLoc())
Cmp->setDebugLoc(Def->getDebugLoc());
}
}
}
// Fold any-of (fcmp uno %A, %A), (fcmp uno %B, %B), ... ->
// any-of (fcmp uno %A, %B), ...
if (match(Def, m_AnyOf())) {
SmallVector<VPValue *, 4> NewOps;
VPRecipeBase *UnpairedCmp = nullptr;
for (VPValue *Op : Def->operands()) {
VPValue *X;
if (Op->getNumUsers() > 1 ||
!match(Op, m_SpecificCmp(CmpInst::FCMP_UNO, m_VPValue(X),
m_Deferred(X)))) {
NewOps.push_back(Op);
} else if (!UnpairedCmp) {
UnpairedCmp = Op->getDefiningRecipe();
} else {
NewOps.push_back(Builder.createFCmp(CmpInst::FCMP_UNO,
UnpairedCmp->getOperand(0), X));
UnpairedCmp = nullptr;
}
}
if (UnpairedCmp)
NewOps.push_back(UnpairedCmp->getVPSingleValue());
if (NewOps.size() < Def->getNumOperands()) {
VPValue *NewAnyOf = Builder.createNaryOp(VPInstruction::AnyOf, NewOps);
return Def->replaceAllUsesWith(NewAnyOf);
}
}
// Fold (fcmp uno %X, %X) or (fcmp uno %Y, %Y) -> fcmp uno %X, %Y
// This is useful for fmax/fmin without fast-math flags, where we need to
// check if any operand is NaN.
if (CanCreateNewRecipe &&
match(Def, m_BinaryOr(m_SpecificCmp(CmpInst::FCMP_UNO, m_VPValue(X),
m_Deferred(X)),
m_SpecificCmp(CmpInst::FCMP_UNO, m_VPValue(Y),
m_Deferred(Y))))) {
VPValue *NewCmp = Builder.createFCmp(CmpInst::FCMP_UNO, X, Y);
return Def->replaceAllUsesWith(NewCmp);
}
// Remove redundant DerviedIVs, that is 0 + A * 1 -> A and 0 + 0 * x -> 0.
if ((match(Def, m_DerivedIV(m_ZeroInt(), m_VPValue(A), m_One())) ||
match(Def, m_DerivedIV(m_ZeroInt(), m_ZeroInt(), m_VPValue()))) &&
Def->getOperand(1)->getScalarType() == Def->getScalarType())
return Def->replaceAllUsesWith(Def->getOperand(1));
if (match(Def, m_VPInstruction<VPInstruction::WideIVStep>(m_VPValue(X),
m_One()))) {
Type *WideStepTy = Def->getScalarType();
if (X->getScalarType() != WideStepTy)
X = Builder.createWidenCast(Instruction::Trunc, X, WideStepTy);
Def->replaceAllUsesWith(X);
return;
}
// For i1 vp.merges produced by AnyOf reductions:
// vp.merge true, (or x, y), x, evl -> vp.merge y, true, x, evl
if (match(Def, m_Intrinsic<Intrinsic::vp_merge>(m_True(), m_VPValue(A),
m_VPValue(X), m_VPValue())) &&
match(A, m_c_BinaryOr(m_Specific(X), m_VPValue(Y))) &&
Def->getScalarType()->isIntegerTy(1)) {
Def->setOperand(1, Def->getOperand(0));
Def->setOperand(0, Y);
return;
}
// Simplify MaskedCond with no block mask to its single operand.
if (match(Def, m_VPInstruction<VPInstruction::MaskedCond>()) &&
!cast<VPInstruction>(Def)->isMasked())
return Def->replaceAllUsesWith(Def->getOperand(0));
// Look through ExtractLastLane.
if (match(Def, m_ExtractLastLane(m_VPValue(A)))) {
if (match(A, m_BuildVector())) {
auto *BuildVector = cast<VPInstruction>(A);
Def->replaceAllUsesWith(
BuildVector->getOperand(BuildVector->getNumOperands() - 1));
return;
}
if (match(A, m_Broadcast(m_VPValue(X))))
return Def->replaceAllUsesWith(X);
if (isa<VPInstruction, VPReplicateRecipe>(A) && vputils::isSingleScalar(A))
return Def->replaceAllUsesWith(A);
if (Plan->hasScalarVFOnly())
return Def->replaceAllUsesWith(A);
}
// Look through ExtractPenultimateElement (BuildVector ....).
if (match(Def, m_ExtractPenultimateElement(m_BuildVector()))) {
auto *BuildVector = cast<VPInstruction>(Def->getOperand(0));
Def->replaceAllUsesWith(
BuildVector->getOperand(BuildVector->getNumOperands() - 2));
return;
}
uint64_t Idx;
if (match(Def, m_ExtractElement(m_BuildVector(), m_ConstantInt(Idx)))) {
auto *BuildVector = cast<VPInstruction>(Def->getOperand(0));
Def->replaceAllUsesWith(BuildVector->getOperand(Idx));
return;
}
if (match(Def, m_BuildVector()) && all_equal(Def->operands())) {
Def->replaceAllUsesWith(
Builder.createNaryOp(VPInstruction::Broadcast, Def->getOperand(0)));
return;
}
// Look through broadcast of single-scalar when used as select conditions; in
// that case the scalar condition can be used directly.
if (match(Def,
m_Select(m_Broadcast(m_VPValue(C)), m_VPValue(), m_VPValue()))) {
assert(vputils::isSingleScalar(C) &&
"broadcast operand must be single-scalar");
Def->setOperand(0, C);
return;
}
if (match(Def, m_Broadcast(m_VPValue(X))))
return Def->replaceUsesWithIf(
X, [Def](const VPUser &U, unsigned) { return U.usesScalars(Def); });
if (isa<VPPhi, VPWidenPHIRecipe, VPHeaderPHIRecipe>(Def)) {
if (Def->getNumOperands() == 1) {
Def->replaceAllUsesWith(Def->getOperand(0));
return;
}
if (auto *Phi = dyn_cast<VPFirstOrderRecurrencePHIRecipe>(Def)) {
if (all_equal(Phi->incoming_values()))
Phi->replaceAllUsesWith(Phi->getOperand(0));
}
return;
}
VPIRValue *IRV;
if (Def->getNumOperands() == 1 &&
match(Def, m_ComputeReductionResult(m_VPIRValue(IRV))))
return Def->replaceAllUsesWith(IRV);
// Some simplifications can only be applied after unrolling. Perform them
// below.
if (!Plan->isUnrolled())
return;
// After unrolling, extract-lane may be used to extract values from multiple
// scalar sources. Only simplify when extracting from a single scalar source.
VPValue *LaneToExtract;
if (match(Def, m_ExtractLane(m_VPValue(LaneToExtract), m_VPValue(A)))) {
// Simplify extract-lane(%lane_num, %scalar_val) -> %scalar_val.
if (vputils::isSingleScalar(A))
return Def->replaceAllUsesWith(A);
// Replace extract-lane(0, canonical-WIDEN-INDUCTION) with the region's
// scalar canonical IV.
VPWidenIntOrFpInductionRecipe *WidenIV;
if (match(LaneToExtract, m_ZeroInt()) &&
match(A, m_CanonicalWidenIV(WidenIV)))
return Def->replaceAllUsesWith(WidenIV->getRegion()->getCanonicalIV());
// Simplify extract-lane with single source to extract-element.
Def->replaceAllUsesWith(Builder.createNaryOp(
Instruction::ExtractElement, {A, LaneToExtract}, Def->getDebugLoc()));
return;
}
// Look for cycles where Def is of the form:
// X = phi(0, IVInc) ; used only by IVInc, or by IVInc and Inc = X + Y
// IVInc = X + Step ; used by X and Def
// Def = IVInc + Y
// Fold the increment Y into the phi's start value, replace Def with IVInc,
// and if Inc exists, replace it with X.
if (match(Def, m_Add(m_Add(m_VPValue(X), m_VPValue()), m_VPValue(Y))) &&
isa<VPIRValue>(Y) &&
match(X, m_VPPhi(m_ZeroInt(), m_Specific(Def->getOperand(0))))) {
auto *Phi = cast<VPPhi>(X);
auto *IVInc = Def->getOperand(0);
if (IVInc->getNumUsers() == 2) {
// If Phi has a second user (besides IVInc's defining recipe), it must
// be Inc = Phi + Y for the fold to apply.
auto *Inc = dyn_cast_or_null<VPSingleDefRecipe>(
findUserOf(Phi, m_Add(m_Specific(Phi), m_Specific(Y))));
if (Phi->getNumUsers() == 1 || (Phi->getNumUsers() == 2 && Inc)) {
Def->replaceAllUsesWith(IVInc);
if (Inc)
Inc->replaceAllUsesWith(Phi);
Phi->setOperand(0, Y);
return;
}
}
}
// Simplify unrolled VectorPointer without offset, or with zero offset, to
// just the pointer operand.
if (auto *VPR = dyn_cast<VPVectorPointerRecipe>(Def))
if (!VPR->getVFxPart() || match(VPR->getVFxPart(), m_ZeroInt()))
return VPR->replaceAllUsesWith(VPR->getOperand(0));
// VPScalarIVSteps after unrolling can be replaced by their start value, if
// the start index is zero and only the first lane 0 is demanded.
if (auto *Steps = dyn_cast<VPScalarIVStepsRecipe>(Def)) {
if (!Steps->getStartIndex() && vputils::onlyFirstLaneUsed(Steps)) {
Steps->replaceAllUsesWith(Steps->getOperand(0));
return;
}
}
// Simplify redundant ReductionStartVector recipes after unrolling.
VPValue *StartV;
if (match(Def, m_VPInstruction<VPInstruction::ReductionStartVector>(
m_VPValue(StartV), m_VPValue(), m_VPValue()))) {
Def->replaceUsesWithIf(StartV, [](const VPUser &U, unsigned Idx) {
auto *PhiR = dyn_cast<VPReductionPHIRecipe>(&U);
return PhiR && PhiR->isInLoop();
});
return;
}
if (Plan->getConcreteUF() == 1 && match(Def, m_ExtractLastPart(m_VPValue(A))))
return Def->replaceAllUsesWith(A);
}
void VPlanTransforms::simplifyRecipes(VPlan &Plan) {
ReversePostOrderTraversal<VPBlockDeepTraversalWrapper<VPBlockBase *>> RPOT(
Plan.getEntry());
for (VPBasicBlock *VPBB : VPBlockUtils::blocksOnly<VPBasicBlock>(RPOT)) {
for (VPRecipeBase &R : make_early_inc_range(*VPBB))
if (auto *Def = dyn_cast<VPSingleDefRecipe>(&R))
simplifyRecipe(Def);
}
}
/// Reassociate (headermask && x) && y -> headermask && (x && y) to allow the
/// header mask to be simplified further when tail folding, e.g. in
/// optimizeEVLMasks.
static void reassociateHeaderMask(VPlan &Plan) {
VPValue *HeaderMask = vputils::findHeaderMask(Plan);
if (!HeaderMask)
return;
SmallVector<VPUser *> Worklist;
for (VPUser *U : HeaderMask->users())
if (match(U, m_LogicalAnd(m_Specific(HeaderMask), m_VPValue())))
append_range(Worklist, cast<VPSingleDefRecipe>(U)->users());
while (!Worklist.empty()) {
auto *R = dyn_cast<VPSingleDefRecipe>(Worklist.pop_back_val());
VPValue *X, *Y;
if (!R || !match(R, m_LogicalAnd(
m_LogicalAnd(m_Specific(HeaderMask), m_VPValue(X)),
m_VPValue(Y))))
continue;
append_range(Worklist, R->users());
VPBuilder Builder(R);
R->replaceAllUsesWith(
Builder.createLogicalAnd(HeaderMask, Builder.createLogicalAnd(X, Y)));
}
}
static std::optional<Instruction::BinaryOps>
getUnmaskedDivRemOpcode(Intrinsic::ID ID) {
switch (ID) {
case Intrinsic::masked_udiv:
return Instruction::UDiv;
case Intrinsic::masked_sdiv:
return Instruction::SDiv;
case Intrinsic::masked_urem:
return Instruction::URem;
case Intrinsic::masked_srem:
return Instruction::SRem;
default:
return {};
}
}
static void narrowToSingleScalarRecipes(VPlan &Plan) {
if (Plan.hasScalarVFOnly())
return;
for (VPBasicBlock *VPBB : VPBlockUtils::blocksOnly<VPBasicBlock>(
vp_depth_first_deep(Plan.getEntry()))) {
for (VPRecipeBase &R : make_early_inc_range(reverse(*VPBB))) {
if (!isa<VPWidenRecipe, VPWidenGEPRecipe, VPReplicateRecipe,
VPWidenIntrinsicRecipe>(&R))
continue;
auto *RepR = dyn_cast<VPReplicateRecipe>(&R);
if (RepR && (RepR->isSingleScalar() || RepR->isPredicated()))
continue;
auto *RepOrWidenR = cast<VPRecipeWithIRFlags>(&R);
if (RepR && RepR->getOpcode() == Instruction::Store &&
vputils::isSingleScalar(RepR->getOperand(1))) {
auto *Clone = new VPReplicateRecipe(
RepOrWidenR->getUnderlyingInstr(), RepOrWidenR->operands(),
true /*IsSingleScalar*/, nullptr /*Mask*/, *RepR /*Flags*/,
*RepR /*Metadata*/, RepR->getDebugLoc());
Clone->insertBefore(RepOrWidenR);
VPBuilder Builder(Clone);
VPValue *ExtractOp = Clone->getOperand(0);
if (vputils::isUniformAcrossVFsAndUFs(RepR->getOperand(1)))
ExtractOp =
Builder.createNaryOp(VPInstruction::ExtractLastPart, ExtractOp);
ExtractOp =
Builder.createNaryOp(VPInstruction::ExtractLastLane, ExtractOp);
Clone->setOperand(0, ExtractOp);
RepR->eraseFromParent();
continue;
}
// Narrow llvm.masked.{u,s}{div,rem} intrinsics with a safe divisor.
if (auto *IntrR = dyn_cast<VPWidenIntrinsicRecipe>(RepOrWidenR)) {
if (!vputils::onlyFirstLaneUsed(IntrR))
continue;
auto Opc = getUnmaskedDivRemOpcode(IntrR->getVectorIntrinsicID());
if (!Opc)
continue;
VPBuilder Builder(IntrR);
VPValue *SafeDivisor = Builder.createSelect(
IntrR->getOperand(2), IntrR->getOperand(1),
Plan.getConstantInt(IntrR->getScalarType(), 1));
VPValue *Clone = Builder.createNaryOp(
*Opc, {IntrR->getOperand(0), SafeDivisor},
VPIRFlags::getDefaultFlags(*Opc), IntrR->getDebugLoc());
IntrR->replaceAllUsesWith(Clone);
IntrR->eraseFromParent();
continue;
}
// Skip recipes that aren't single scalars.
if (!vputils::isSingleScalar(RepOrWidenR))
continue;
// Predicate to check if a user of Op introduces extra broadcasts.
auto IntroducesBCastOf = [](const VPValue *Op) {
return [Op](const VPUser *U) {
if (auto *VPI = dyn_cast<VPInstruction>(U)) {
if (is_contained({VPInstruction::ExtractLastLane,
VPInstruction::ExtractLastPart,
VPInstruction::ExtractPenultimateElement},
VPI->getOpcode()))
return false;
}
return !U->usesScalars(Op);
};
};
if (any_of(RepOrWidenR->users(), IntroducesBCastOf(RepOrWidenR)) &&
none_of(RepOrWidenR->operands(), [&](VPValue *Op) {
if (any_of(
make_filter_range(Op->users(), not_equal_to(RepOrWidenR)),
IntroducesBCastOf(Op)))
return false;
// Non-constant live-ins require broadcasts, while constants do not
// need explicit broadcasts.
auto *IRV = dyn_cast<VPIRValue>(Op);
bool LiveInNeedsBroadcast = IRV && !isa<Constant>(IRV->getValue());
auto *OpR = dyn_cast<VPReplicateRecipe>(Op);
return LiveInNeedsBroadcast || (OpR && OpR->isSingleScalar());
}))
continue;
auto *Clone = new VPReplicateRecipe(
RepOrWidenR->getUnderlyingInstr(), RepOrWidenR->operands(),
true /*IsSingleScalar*/, nullptr, *RepOrWidenR);
Clone->insertBefore(RepOrWidenR);
RepOrWidenR->replaceAllUsesWith(Clone);
if (isDeadRecipe(*RepOrWidenR))
RepOrWidenR->eraseFromParent();
}
}
}
/// Try to see if all of \p Blend's masks share a common value logically and'ed
/// and remove it from the masks.
static void removeCommonBlendMask(VPBlendRecipe *Blend) {
if (Blend->isNormalized())
return;
VPValue *CommonEdgeMask;
if (!match(Blend->getMask(0),
m_LogicalAnd(m_VPValue(CommonEdgeMask), m_VPValue())))
return;
for (unsigned I = 0; I < Blend->getNumIncomingValues(); I++)
if (!match(Blend->getMask(I),
m_LogicalAnd(m_Specific(CommonEdgeMask), m_VPValue())))
return;
for (unsigned I = 0; I < Blend->getNumIncomingValues(); I++)
Blend->setMask(I, Blend->getMask(I)->getDefiningRecipe()->getOperand(1));
}
/// Normalize and simplify VPBlendRecipes. Should be run after simplifyRecipes
/// to make sure the masks are simplified.
static void simplifyBlends(VPlan &Plan) {
for (VPBasicBlock *VPBB : VPBlockUtils::blocksOnly<VPBasicBlock>(
vp_depth_first_shallow(Plan.getVectorLoopRegion()->getEntry()))) {
for (VPRecipeBase &R : make_early_inc_range(*VPBB)) {
auto *Blend = dyn_cast<VPBlendRecipe>(&R);
if (!Blend)
continue;
removeCommonBlendMask(Blend);
// Try to remove redundant blend recipes.
SmallPtrSet<VPValue *, 4> UniqueValues;
if (Blend->isNormalized() || !match(Blend->getMask(0), m_False()))
UniqueValues.insert(Blend->getIncomingValue(0));
for (unsigned I = 1; I != Blend->getNumIncomingValues(); ++I)
if (!match(Blend->getMask(I), m_False()))
UniqueValues.insert(Blend->getIncomingValue(I));
if (UniqueValues.size() == 1) {
Blend->replaceAllUsesWith(*UniqueValues.begin());
Blend->eraseFromParent();
continue;
}
if (Blend->isNormalized())
continue;
// Normalize the blend so its first incoming value is used as the initial
// value with the others blended into it.
unsigned StartIndex = 0;
for (unsigned I = 0; I != Blend->getNumIncomingValues(); ++I) {
// If a value's mask is used only by the blend then is can be deadcoded.
// TODO: Find the most expensive mask that can be deadcoded, or a mask
// that's used by multiple blends where it can be removed from them all.
VPValue *Mask = Blend->getMask(I);
if (Mask->getNumUsers() == 1 && !match(Mask, m_False())) {
StartIndex = I;
break;
}
}
SmallVector<VPValue *, 4> OperandsWithMask;
OperandsWithMask.push_back(Blend->getIncomingValue(StartIndex));
for (unsigned I = 0; I != Blend->getNumIncomingValues(); ++I) {
if (I == StartIndex)
continue;
OperandsWithMask.push_back(Blend->getIncomingValue(I));
OperandsWithMask.push_back(Blend->getMask(I));
}
auto *NewBlend =
new VPBlendRecipe(cast_or_null<PHINode>(Blend->getUnderlyingValue()),
OperandsWithMask, *Blend, Blend->getDebugLoc());
NewBlend->insertBefore(&R);
VPValue *DeadMask = Blend->getMask(StartIndex);
Blend->replaceAllUsesWith(NewBlend);
Blend->eraseFromParent();
recursivelyDeleteDeadRecipes(DeadMask);
/// Simplify BLEND %a, %b, Not(%mask) -> BLEND %b, %a, %mask.
VPValue *NewMask;
if (NewBlend->getNumOperands() == 3 &&
match(NewBlend->getMask(1), m_Not(m_VPValue(NewMask)))) {
VPValue *Inc0 = NewBlend->getOperand(0);
VPValue *Inc1 = NewBlend->getOperand(1);
VPValue *OldMask = NewBlend->getOperand(2);
NewBlend->setOperand(0, Inc1);
NewBlend->setOperand(1, Inc0);
NewBlend->setOperand(2, NewMask);
if (OldMask->getNumUsers() == 0)
cast<VPInstruction>(OldMask)->eraseFromParent();
}
}
}
}
/// Optimize the width of vector induction variables in \p Plan based on a known
/// constant Trip Count, \p BestVF and \p BestUF.
static bool optimizeVectorInductionWidthForTCAndVFUF(VPlan &Plan,
ElementCount BestVF,
unsigned BestUF) {
// Only proceed if we have not completely removed the vector region.
if (!Plan.getVectorLoopRegion())
return false;
const APInt *TC;
if (!BestVF.isFixed() || !match(Plan.getTripCount(), m_APInt(TC)))
return false;
// Calculate the minimum power-of-2 bit width that can fit the known TC, VF
// and UF. Returns at least 8.
auto ComputeBitWidth = [](APInt TC, uint64_t Align) {
APInt AlignedTC =
Align * APIntOps::RoundingUDiv(TC, APInt(TC.getBitWidth(), Align),
APInt::Rounding::UP);
APInt MaxVal = AlignedTC - 1;
return std::max<unsigned>(PowerOf2Ceil(MaxVal.getActiveBits()), 8);
};
unsigned NewBitWidth =
ComputeBitWidth(*TC, BestVF.getKnownMinValue() * BestUF);
LLVMContext &Ctx = Plan.getContext();
auto *NewIVTy = IntegerType::get(Ctx, NewBitWidth);
bool MadeChange = false;
VPBasicBlock *HeaderVPBB = Plan.getVectorLoopRegion()->getEntryBasicBlock();
for (VPRecipeBase &Phi : HeaderVPBB->phis()) {
// Currently only handle canonical IVs as it is trivial to replace the start
// and stop values, and we currently only perform the optimization when the
// IV has a single use.
VPWidenIntOrFpInductionRecipe *WideIV;
if (!match(&Phi, m_CanonicalWidenIV(WideIV)))
continue;
if (WideIV->hasMoreThanOneUniqueUser() ||
NewIVTy == WideIV->getScalarType())
continue;
// Currently only handle cases where the single user is a header-mask
// comparison with the backedge-taken-count.
VPUser *SingleUser = WideIV->getSingleUser();
if (!SingleUser ||
!match(SingleUser,
m_ICmp(m_Specific(WideIV),
m_Broadcast(m_Specific(Plan.getBackedgeTakenCount())))))
continue;
// Update IV operands and comparison bound to use new narrower type.
assert(!WideIV->getTruncInst() &&
"canonical IV is not expected to have a truncation");
auto *NewWideIV = new VPWidenIntOrFpInductionRecipe(
WideIV->getPHINode(), Plan.getZero(NewIVTy),
Plan.getConstantInt(NewIVTy, 1), WideIV->getVFValue(),
WideIV->getInductionDescriptor(), *WideIV, WideIV->getDebugLoc());
NewWideIV->insertBefore(WideIV);
auto *NewBTC = new VPWidenCastRecipe(
Instruction::Trunc, Plan.getOrCreateBackedgeTakenCount(), NewIVTy,
nullptr, VPIRFlags::getDefaultFlags(Instruction::Trunc));
Plan.getVectorPreheader()->appendRecipe(NewBTC);
auto *Cmp = cast<VPInstruction>(WideIV->getSingleUser());
Cmp->replaceAllUsesWith(
VPBuilder(Cmp).createICmp(Cmp->getPredicate(), NewWideIV, NewBTC));
MadeChange = true;
}
return MadeChange;
}
/// Return true if \p Cond is known to be true for given \p BestVF and \p
/// BestUF.
static bool isConditionTrueViaVFAndUF(VPValue *Cond, VPlan &Plan,
ElementCount BestVF, unsigned BestUF,
PredicatedScalarEvolution &PSE) {
if (match(Cond, m_BinaryOr(m_VPValue(), m_VPValue())))
return any_of(Cond->getDefiningRecipe()->operands(), [&Plan, BestVF, BestUF,
&PSE](VPValue *C) {
return isConditionTrueViaVFAndUF(C, Plan, BestVF, BestUF, PSE);
});
auto *CanIV = Plan.getVectorLoopRegion()->getCanonicalIV();
if (!match(Cond, m_SpecificICmp(
CmpInst::ICMP_EQ,
m_c_Add(m_Specific(CanIV), m_Specific(&Plan.getVFxUF())),
m_Specific(&Plan.getVectorTripCount()))))
return false;
// The compare checks CanIV + VFxUF == vector trip count. The vector trip
// count is not conveniently available as SCEV so far, so we compare directly
// against the original trip count. This is stricter than necessary, as we
// will only return true if the trip count == vector trip count.
const SCEV *VectorTripCount =
vputils::getSCEVExprForVPValue(&Plan.getVectorTripCount(), PSE);
if (isa<SCEVCouldNotCompute>(VectorTripCount))
VectorTripCount = vputils::getSCEVExprForVPValue(Plan.getTripCount(), PSE);
assert(!isa<SCEVCouldNotCompute>(VectorTripCount) &&
"Trip count SCEV must be computable");
ScalarEvolution &SE = *PSE.getSE();
ElementCount NumElements = BestVF.multiplyCoefficientBy(BestUF);
const SCEV *C = SE.getElementCount(VectorTripCount->getType(), NumElements);
return SE.isKnownPredicate(CmpInst::ICMP_EQ, VectorTripCount, C);
}
/// Try to replace multiple active lane masks used for control flow with
/// a single, wide active lane mask instruction followed by multiple
/// extract subvector intrinsics. This applies to the active lane mask
/// instructions both in the loop and in the preheader.
/// Incoming values of all ActiveLaneMaskPHIs are updated to use the
/// new extracts from the first active lane mask, which has it's last
/// operand (multiplier) set to UF.
static bool tryToReplaceALMWithWideALM(VPlan &Plan, ElementCount VF,
unsigned UF) {
if (!EnableWideActiveLaneMask || !VF.isVector() || UF == 1)
return false;
VPRegionBlock *VectorRegion = Plan.getVectorLoopRegion();
VPBasicBlock *ExitingVPBB = VectorRegion->getExitingBasicBlock();
auto *Term = &ExitingVPBB->back();
using namespace llvm::VPlanPatternMatch;
if (!match(Term, m_BranchOnCond(m_Not(m_ActiveLaneMask(
m_VPValue(), m_VPValue(), m_VPValue())))))
return false;
auto *Header = cast<VPBasicBlock>(VectorRegion->getEntry());
LLVMContext &Ctx = Plan.getContext();
auto ExtractFromALM = [&](VPInstruction *ALM,
SmallVectorImpl<VPValue *> &Extracts) {
DebugLoc DL = ALM->getDebugLoc();
for (unsigned Part = 0; Part < UF; ++Part) {
SmallVector<VPValue *> Ops;
Ops.append({ALM, Plan.getConstantInt(64, VF.getKnownMinValue() * Part)});
auto *Ext =
new VPWidenIntrinsicRecipe(Intrinsic::vector_extract, Ops,
IntegerType::getInt1Ty(Ctx), {}, {}, DL);
Extracts[Part] = Ext;
Ext->insertAfter(ALM);
}
};
// Create a list of each active lane mask phi, ordered by unroll part.
SmallVector<VPActiveLaneMaskPHIRecipe *> Phis(UF, nullptr);
for (VPRecipeBase &R : Header->phis()) {
auto *Phi = dyn_cast<VPActiveLaneMaskPHIRecipe>(&R);
if (!Phi)
continue;
VPValue *Index = nullptr;
match(Phi->getBackedgeValue(),
m_ActiveLaneMask(m_VPValue(Index), m_VPValue(), m_VPValue()));
assert(Index && "Expected index from ActiveLaneMask instruction");
uint64_t Part;
if (match(Index,
m_VPInstruction<VPInstruction::CanonicalIVIncrementForPart>(
m_VPValue(), m_Mul(m_VPValue(), m_ConstantInt(Part)))))
Phis[Part] = Phi;
else {
// Anything other than a CanonicalIVIncrementForPart is part 0
assert(!match(
Index,
m_VPInstruction<VPInstruction::CanonicalIVIncrementForPart>()));
Phis[0] = Phi;
}
}
assert(all_of(Phis, not_equal_to(nullptr)) &&
"Expected one VPActiveLaneMaskPHIRecipe for each unroll part");
auto *EntryALM = cast<VPInstruction>(Phis[0]->getStartValue());
auto *LoopALM = cast<VPInstruction>(Phis[0]->getBackedgeValue());
assert((EntryALM->getOpcode() == VPInstruction::ActiveLaneMask &&
LoopALM->getOpcode() == VPInstruction::ActiveLaneMask) &&
"Expected incoming values of Phi to be ActiveLaneMasks");
// When using wide lane masks, the return type of the get.active.lane.mask
// intrinsic is VF x UF (last operand).
VPValue *ALMMultiplier = Plan.getConstantInt(64, UF);
EntryALM->setOperand(2, ALMMultiplier);
LoopALM->setOperand(2, ALMMultiplier);
// Create UF x extract vectors and insert into preheader.
SmallVector<VPValue *> EntryExtracts(UF);
ExtractFromALM(EntryALM, EntryExtracts);
// Create UF x extract vectors and insert before the loop compare & branch,
// updating the compare to use the first extract.
SmallVector<VPValue *> LoopExtracts(UF);
ExtractFromALM(LoopALM, LoopExtracts);
VPInstruction *Not = cast<VPInstruction>(Term->getOperand(0));
Not->setOperand(0, LoopExtracts[0]);
// Update the incoming values of active lane mask phis.
for (unsigned Part = 0; Part < UF; ++Part) {
Phis[Part]->setStartValue(EntryExtracts[Part]);
Phis[Part]->setBackedgeValue(LoopExtracts[Part]);
}
return true;
}
/// Try to simplify the branch condition of \p Plan. This may restrict the
/// resulting plan to \p BestVF and \p BestUF.
static bool simplifyBranchConditionForVFAndUF(VPlan &Plan, ElementCount BestVF,
unsigned BestUF,
PredicatedScalarEvolution &PSE) {
VPRegionBlock *VectorRegion = Plan.getVectorLoopRegion();
VPBasicBlock *ExitingVPBB = VectorRegion->getExitingBasicBlock();
auto *Term = &ExitingVPBB->back();
VPValue *Cond;
auto m_CanIVInc = m_Add(m_VPValue(), m_Specific(&Plan.getVFxUF()));
// Check if the branch condition compares the canonical IV increment (for main
// loop), or the canonical IV increment plus an offset (for epilog loop).
if (match(Term, m_BranchOnCount(
m_CombineOr(m_CanIVInc, m_c_Add(m_CanIVInc, m_LiveIn())),
m_VPValue())) ||
match(Term, m_BranchOnCond(m_Not(m_ActiveLaneMask(
m_VPValue(), m_VPValue(), m_VPValue()))))) {
// Try to simplify the branch condition if VectorTC <= VF * UF when the
// latch terminator is BranchOnCount or BranchOnCond(Not(ActiveLaneMask)).
const SCEV *VectorTripCount =
vputils::getSCEVExprForVPValue(&Plan.getVectorTripCount(), PSE);
if (isa<SCEVCouldNotCompute>(VectorTripCount))
VectorTripCount =
vputils::getSCEVExprForVPValue(Plan.getTripCount(), PSE);
assert(!isa<SCEVCouldNotCompute>(VectorTripCount) &&
"Trip count SCEV must be computable");
ScalarEvolution &SE = *PSE.getSE();
ElementCount NumElements = BestVF.multiplyCoefficientBy(BestUF);
const SCEV *C = SE.getElementCount(VectorTripCount->getType(), NumElements);
if (!SE.isKnownPredicate(CmpInst::ICMP_ULE, VectorTripCount, C))
return false;
} else if (match(Term, m_BranchOnCond(m_VPValue(Cond))) ||
match(Term, m_BranchOnTwoConds(m_VPValue(), m_VPValue(Cond)))) {
// For BranchOnCond, check if we can prove the condition to be true using VF
// and UF.
if (!isConditionTrueViaVFAndUF(Cond, Plan, BestVF, BestUF, PSE))
return false;
} else {
return false;
}
// The vector loop region only executes once. Convert terminator of the
// exiting block to exit in the first iteration.
if (match(Term, m_BranchOnTwoConds())) {
Term->setOperand(1, Plan.getTrue());
return true;
}
auto *BOC = new VPInstruction(VPInstruction::BranchOnCond, Plan.getTrue(), {},
{}, Term->getDebugLoc());
ExitingVPBB->appendRecipe(BOC);
Term->eraseFromParent();
return true;
}
/// From the definition of llvm.experimental.get.vector.length,
/// VPInstruction::ExplicitVectorLength(%AVL) = %AVL when %AVL <= VF.
bool VPlanTransforms::simplifyKnownEVL(VPlan &Plan, ElementCount VF,
PredicatedScalarEvolution &PSE) {
for (VPBasicBlock *VPBB : VPBlockUtils::blocksOnly<VPBasicBlock>(
vp_depth_first_deep(Plan.getEntry()))) {
for (VPRecipeBase &R : *VPBB) {
VPValue *AVL;
if (!match(&R, m_EVL(m_VPValue(AVL))))
continue;
const SCEV *AVLSCEV = vputils::getSCEVExprForVPValue(AVL, PSE);
if (isa<SCEVCouldNotCompute>(AVLSCEV))
continue;
ScalarEvolution &SE = *PSE.getSE();
const SCEV *VFSCEV = SE.getElementCount(AVLSCEV->getType(), VF);
if (!SE.isKnownPredicate(CmpInst::ICMP_ULE, AVLSCEV, VFSCEV))
continue;
VPValue *Trunc = VPBuilder(&R).createScalarZExtOrTrunc(
AVL, Type::getInt32Ty(Plan.getContext()), AVLSCEV->getType(),
R.getDebugLoc());
if (Trunc != AVL) {
auto *TruncR = cast<VPSingleDefRecipe>(Trunc);
const DataLayout &DL = Plan.getDataLayout();
if (VPValue *Folded = tryToFoldLiveIns(*TruncR, TruncR->operands(), DL,
Plan.getContext()))
Trunc = Folded;
}
R.getVPSingleValue()->replaceAllUsesWith(Trunc);
return true;
}
}
return false;
}
void VPlanTransforms::optimizeForVFAndUF(VPlan &Plan, ElementCount BestVF,
unsigned BestUF,
PredicatedScalarEvolution &PSE) {
assert(Plan.hasVF(BestVF) && "BestVF is not available in Plan");
assert(Plan.hasUF(BestUF) && "BestUF is not available in Plan");
bool MadeChange = tryToReplaceALMWithWideALM(Plan, BestVF, BestUF);
MadeChange |= simplifyBranchConditionForVFAndUF(Plan, BestVF, BestUF, PSE);
MadeChange |= optimizeVectorInductionWidthForTCAndVFUF(Plan, BestVF, BestUF);
if (MadeChange) {
Plan.setVF(BestVF);
assert(Plan.getConcreteUF() == BestUF && "BestUF must match the Plan's UF");
}
}
void VPlanTransforms::clearReductionWrapFlags(VPlan &Plan) {
for (VPRecipeBase &R :
Plan.getVectorLoopRegion()->getEntryBasicBlock()->phis()) {
auto *PhiR = dyn_cast<VPReductionPHIRecipe>(&R);
if (!PhiR)
continue;
RecurKind RK = PhiR->getRecurrenceKind();
if (RK != RecurKind::Add && RK != RecurKind::Mul && RK != RecurKind::Sub &&
RK != RecurKind::AddChainWithSubs)
continue;
for (VPUser *U : collectUsersRecursively(PhiR))
if (auto *RecWithFlags = dyn_cast<VPRecipeWithIRFlags>(U)) {
RecWithFlags->dropPoisonGeneratingFlags();
}
}
}
namespace {
struct VPCSEDenseMapInfo : public DenseMapInfo<VPSingleDefRecipe *> {
/// If recipe \p R will lower to a GEP with a non-i8 source element type,
/// return that source element type.
static Type *getGEPSourceElementType(const VPSingleDefRecipe *R) {
// All VPInstructions that lower to GEPs must have the i8 source element
// type (as they are PtrAdds), so we omit it.
return TypeSwitch<const VPSingleDefRecipe *, Type *>(R)
.Case([](const VPReplicateRecipe *I) -> Type * {
if (auto *GEP = dyn_cast<GetElementPtrInst>(I->getUnderlyingValue()))
return GEP->getSourceElementType();
return nullptr;
})
.Case<VPVectorPointerRecipe, VPWidenGEPRecipe>(
[](auto *I) { return I->getSourceElementType(); })
.Default([](auto *) { return nullptr; });
}
/// Returns true if recipe \p Def can be safely handed for CSE.
static bool canHandle(const VPSingleDefRecipe *Def) {
// We can extend the list of handled recipes in the future,
// provided we account for the data embedded in them while checking for
// equality or hashing.
auto C = getOpcodeOrIntrinsicID(Def);
// The issue with (Insert|Extract)Value is that the index of the
// insert/extract is not a proper operand in LLVM IR, and hence also not in
// VPlan.
if (!C || (!C->first && (C->second == Instruction::InsertValue ||
C->second == Instruction::ExtractValue)))
return false;
// During CSE, we can only handle recipes that don't read from memory: if
// they read from memory, there could be an intervening write to memory
// before the next instance is CSE'd, leading to an incorrect result.
return !Def->mayReadFromMemory();
}
/// Hash the underlying data of \p Def.
static unsigned getHashValue(const VPSingleDefRecipe *Def) {
hash_code Result = hash_combine(
Def->getVPRecipeID(), getOpcodeOrIntrinsicID(Def),
getGEPSourceElementType(Def), Def->getScalarType(),
vputils::isSingleScalar(Def), hash_combine_range(Def->operands()));
if (auto *RFlags = dyn_cast<VPRecipeWithIRFlags>(Def))
if (RFlags->hasPredicate())
return hash_combine(Result, RFlags->getPredicate());
if (auto *SIVSteps = dyn_cast<VPScalarIVStepsRecipe>(Def))
return hash_combine(Result, SIVSteps->getInductionOpcode());
return Result;
}
/// Check equality of underlying data of \p L and \p R.
static bool isEqual(const VPSingleDefRecipe *L, const VPSingleDefRecipe *R) {
if (L->getVPRecipeID() != R->getVPRecipeID() ||
getOpcodeOrIntrinsicID(L) != getOpcodeOrIntrinsicID(R) ||
getGEPSourceElementType(L) != getGEPSourceElementType(R) ||
vputils::isSingleScalar(L) != vputils::isSingleScalar(R) ||
!equal(L->operands(), R->operands()))
return false;
assert(getOpcodeOrIntrinsicID(L) && getOpcodeOrIntrinsicID(R) &&
"must have valid opcode info for both recipes");
if (auto *LFlags = dyn_cast<VPRecipeWithIRFlags>(L))
if (LFlags->hasPredicate() &&
LFlags->getPredicate() !=
cast<VPRecipeWithIRFlags>(R)->getPredicate())
return false;
if (auto *LSIV = dyn_cast<VPScalarIVStepsRecipe>(L))
if (LSIV->getInductionOpcode() !=
cast<VPScalarIVStepsRecipe>(R)->getInductionOpcode())
return false;
// Recipes in replicate regions implicitly depend on predicate. If either
// recipe is in a replicate region, only consider them equal if both have
// the same parent.
const VPRegionBlock *RegionL = L->getRegion();
const VPRegionBlock *RegionR = R->getRegion();
if (((RegionL && RegionL->isReplicator()) ||
(RegionR && RegionR->isReplicator())) &&
L->getParent() != R->getParent())
return false;
return L->getScalarType() == R->getScalarType();
}
};
} // end anonymous namespace
/// Perform a common-subexpression-elimination of VPSingleDefRecipes on the \p
/// Plan.
void VPlanTransforms::cse(VPlan &Plan) {
VPDominatorTree VPDT(Plan);
DenseMap<VPSingleDefRecipe *, VPSingleDefRecipe *, VPCSEDenseMapInfo> CSEMap;
ReversePostOrderTraversal<VPBlockDeepTraversalWrapper<VPBlockBase *>> RPOT(
Plan.getEntry());
for (VPBasicBlock *VPBB : VPBlockUtils::blocksOnly<VPBasicBlock>(RPOT)) {
for (VPRecipeBase &R : *VPBB) {
auto *Def = dyn_cast<VPSingleDefRecipe>(&R);
if (!Def || !VPCSEDenseMapInfo::canHandle(Def))
continue;
if (VPSingleDefRecipe *V = CSEMap.lookup(Def)) {
// V must dominate Def for a valid replacement.
if (!VPDT.dominates(V->getParent(), VPBB))
continue;
// Only keep flags present on both V and Def.
if (auto *RFlags = dyn_cast<VPRecipeWithIRFlags>(V))
RFlags->intersectFlags(*cast<VPRecipeWithIRFlags>(Def));
Def->replaceAllUsesWith(V);
continue;
}
CSEMap[Def] = Def;
}
}
}
/// Return true if we do not know how to (mechanically) hoist or sink a
/// non-memory or memory recipe \p R out of a loop region.
static bool cannotHoistOrSinkRecipe(VPRecipeBase &R, VPBasicBlock *FirstBB,
VPBasicBlock *LastBB) {
if (!isa<VPReplicateRecipe>(R) || !R.mayReadFromMemory())
return vputils::cannotHoistOrSinkRecipe(R);
// Check that the load doesn't alias with stores between FirstBB and LastBB.
auto MemLoc = vputils::getMemoryLocation(R);
return !MemLoc || !canHoistOrSinkWithNoAliasCheck(*MemLoc, FirstBB, LastBB);
}
/// Move loop-invariant recipes out of the vector loop region in \p Plan.
static void licm(VPlan &Plan) {
VPBasicBlock *Preheader = Plan.getVectorPreheader();
// Hoist any loop invariant recipes from the vector loop region to the
// preheader. Preform a shallow traversal of the vector loop region, to
// exclude recipes in replicate regions. Since the top-level blocks in the
// vector loop region are guaranteed to execute if the vector pre-header is,
// we don't need to check speculation safety.
VPRegionBlock *LoopRegion = Plan.getVectorLoopRegion();
assert(Preheader->getSingleSuccessor() == LoopRegion &&
"Expected vector prehader's successor to be the vector loop region");
for (VPBasicBlock *VPBB : VPBlockUtils::blocksOnly<VPBasicBlock>(
vp_depth_first_shallow(LoopRegion->getEntry()))) {
for (VPRecipeBase &R : make_early_inc_range(*VPBB)) {
if (cannotHoistOrSinkRecipe(R, LoopRegion->getEntryBasicBlock(),
LoopRegion->getExitingBasicBlock()))
continue;
if (any_of(R.operands(), [](VPValue *Op) {
return !Op->isDefinedOutsideLoopRegions();
}))
continue;
R.moveBefore(*Preheader, Preheader->end());
}
}
#ifndef NDEBUG
VPDominatorTree VPDT(Plan);
#endif
// Sink recipes with no users inside the vector loop region if all users are
// in the same exit block of the region.
// TODO: Extend to sink recipes from inner loops.
PostOrderTraversal<VPBlockShallowTraversalWrapper<VPBlockBase *>> POT(
LoopRegion->getEntry());
for (VPBasicBlock *VPBB : VPBlockUtils::blocksOnly<VPBasicBlock>(POT)) {
for (VPRecipeBase &R : make_early_inc_range(reverse(*VPBB))) {
if (vputils::cannotHoistOrSinkRecipe(R, /*Sinking=*/true))
continue;
if (auto *RepR = dyn_cast<VPReplicateRecipe>(&R)) {
assert(!RepR->isPredicated() &&
"Expected prior transformation of predicated replicates to "
"replicate regions");
// narrowToSingleScalarRecipes should have already maximally narrowed
// replicates to single-scalar replicates.
// TODO: When unrolling, replicateByVF doesn't handle sunk
// non-single-scalar replicates correctly.
if (!RepR->isSingleScalar())
continue;
}
// TODO: Use R.definedValues() instead of casting to VPSingleDefRecipe to
// support recipes with multiple defined values (e.g., interleaved loads).
auto *Def = cast<VPSingleDefRecipe>(&R);
// Cannot sink the recipe if the user is defined in a loop region or a
// non-successor of the vector loop region. Cannot sink if user is a phi
// either.
VPBasicBlock *SinkBB = nullptr;
if (any_of(Def->users(), [&SinkBB, &LoopRegion](VPUser *U) {
auto *UserR = cast<VPRecipeBase>(U);
VPBasicBlock *Parent = UserR->getParent();
// TODO: Support sinking when users are in multiple blocks.
if (SinkBB && SinkBB != Parent)
return true;
SinkBB = Parent;
// TODO: If the user is a PHI node, we should check the block of
// incoming value. Support PHI node users if needed.
return UserR->isPhi() || Parent->getEnclosingLoopRegion() ||
Parent->getSinglePredecessor() != LoopRegion;
}))
continue;
if (!SinkBB)
SinkBB = cast<VPBasicBlock>(LoopRegion->getSingleSuccessor());
// TODO: This will need to be a check instead of a assert after
// conditional branches in vectorized loops are supported.
assert(VPDT.properlyDominates(VPBB, SinkBB) &&
"Defining block must dominate sink block");
// TODO: Clone the recipe if users are on multiple exit paths, instead of
// just moving.
Def->moveBefore(*SinkBB, SinkBB->getFirstNonPhi());
}
}
}
void VPlanTransforms::truncateToMinimalBitwidths(
VPlan &Plan, const MapVector<Instruction *, uint64_t> &MinBWs) {
if (Plan.hasScalarVFOnly())
return;
// Keep track of created truncates, so they can be re-used. Note that we
// cannot use RAUW after creating a new truncate, as this would could make
// other uses have different types for their operands, making them invalidly
// typed.
DenseMap<VPValue *, VPWidenCastRecipe *> ProcessedTruncs;
VPBasicBlock *PH = Plan.getVectorPreheader();
for (VPBasicBlock *VPBB : VPBlockUtils::blocksOnly<VPBasicBlock>(
vp_depth_first_deep(Plan.getVectorLoopRegion()))) {
for (VPRecipeBase &R : make_early_inc_range(*VPBB)) {
if (!isa<VPWidenRecipe, VPWidenCastRecipe, VPReplicateRecipe,
VPWidenLoadRecipe, VPWidenIntrinsicRecipe>(&R))
continue;
VPValue *ResultVPV = R.getVPSingleValue();
auto *UI = cast_or_null<Instruction>(ResultVPV->getUnderlyingValue());
unsigned NewResSizeInBits = MinBWs.lookup(UI);
if (!NewResSizeInBits)
continue;
// If the value wasn't vectorized, we must maintain the original scalar
// type. Skip those here, after incrementing NumProcessedRecipes. Also
// skip casts which do not need to be handled explicitly here, as
// redundant casts will be removed during recipe simplification.
if (isa<VPReplicateRecipe, VPWidenCastRecipe>(&R))
continue;
Type *OldResTy = ResultVPV->getScalarType();
unsigned OldResSizeInBits = OldResTy->getScalarSizeInBits();
assert(OldResTy->isIntegerTy() && "only integer types supported");
(void)OldResSizeInBits;
auto *NewResTy = IntegerType::get(Plan.getContext(), NewResSizeInBits);
// Any wrapping introduced by shrinking this operation shouldn't be
// considered undefined behavior. So, we can't unconditionally copy
// arithmetic wrapping flags to VPW.
if (auto *VPW = dyn_cast<VPRecipeWithIRFlags>(&R))
VPW->dropPoisonGeneratingFlags();
assert((OldResSizeInBits != NewResSizeInBits ||
match(&R, m_ICmp(m_VPValue(), m_VPValue()))) &&
"Only ICmps should not need extending the result.");
assert(!isa<VPWidenStoreRecipe>(&R) && "stores cannot be narrowed");
// For loads/intrinsics we don't recreate the recipe; just wrap the
// original wide result in a ZExt to OldResTy.
if (isa<VPWidenLoadRecipe, VPWidenIntrinsicRecipe>(&R)) {
if (OldResSizeInBits != NewResSizeInBits) {
auto *Ext = VPBuilder::getToInsertAfter(&R).createWidenCast(
Instruction::ZExt, ResultVPV, OldResTy);
ResultVPV->replaceAllUsesWith(Ext);
Ext->setOperand(0, ResultVPV);
}
continue;
}
// Shrink operands by introducing truncates as needed.
unsigned StartIdx =
match(&R, m_Select(m_VPValue(), m_VPValue(), m_VPValue())) ? 1 : 0;
SmallVector<VPValue *> NewOperands(R.operands());
for (VPValue *&Op : drop_begin(NewOperands, StartIdx)) {
unsigned OpSizeInBits = Op->getScalarType()->getScalarSizeInBits();
if (OpSizeInBits == NewResSizeInBits)
continue;
assert(OpSizeInBits > NewResSizeInBits && "nothing to truncate");
auto [ProcessedIter, Inserted] = ProcessedTruncs.try_emplace(Op);
if (Inserted) {
VPBuilder Builder;
if (isa<VPIRValue>(Op))
Builder.setInsertPoint(PH);
else
Builder.setInsertPoint(&R);
ProcessedIter->second =
Builder.createWidenCast(Instruction::Trunc, Op, NewResTy);
}
Op = ProcessedIter->second;
}
auto *NWR = cast<VPWidenRecipe>(&R)->cloneWithOperands(NewOperands);
NWR->insertBefore(&R);
// Wrap NWR in a ZExt to preserve the original wide type for downstream
// users (unless this is an ICmp, which produces i1 regardless).
VPValue *Replacement = NWR->getVPSingleValue();
if (OldResSizeInBits != NewResSizeInBits)
Replacement =
VPBuilder::getToInsertAfter(NWR)
.createWidenCast(Instruction::ZExt, Replacement, OldResTy)
->getVPSingleValue();
ResultVPV->replaceAllUsesWith(Replacement);
R.eraseFromParent();
}
}
}
void VPlanTransforms::removeBranchOnConst(VPlan &Plan, bool OnlyLatches) {
std::optional<VPDominatorTree> VPDT;
if (OnlyLatches)
VPDT.emplace(Plan);
// Collect all blocks before modifying the CFG so we can identify unreachable
// ones after constant branch removal.
SmallVector<VPBlockBase *> AllBlocks(vp_depth_first_shallow(Plan.getEntry()));
for (VPBasicBlock *VPBB : VPBlockUtils::blocksOnly<VPBasicBlock>(AllBlocks)) {
VPValue *Cond;
// Skip blocks that are not terminated by BranchOnCond.
if (VPBB->empty() || !match(&VPBB->back(), m_BranchOnCond(m_VPValue(Cond))))
continue;
if (OnlyLatches && !VPBlockUtils::isLatch(VPBB, *VPDT))
continue;
assert(VPBB->getNumSuccessors() == 2 &&
"Two successors expected for BranchOnCond");
unsigned RemovedIdx;
if (match(Cond, m_True()))
RemovedIdx = 1;
else if (match(Cond, m_False()))
RemovedIdx = 0;
else
continue;
VPBasicBlock *RemovedSucc =
cast<VPBasicBlock>(VPBB->getSuccessors()[RemovedIdx]);
assert(count(RemovedSucc->getPredecessors(), VPBB) == 1 &&
"There must be a single edge between VPBB and its successor");
// Values coming from VPBB into phi recipes of RemovedSucc are removed from
// these recipes.
for (VPRecipeBase &R : RemovedSucc->phis())
cast<VPPhiAccessors>(&R)->removeIncomingValueFor(VPBB);
// Disconnect blocks and remove the terminator.
VPBlockUtils::disconnectBlocks(VPBB, RemovedSucc);
VPBB->back().eraseFromParent();
}
// Compute which blocks are still reachable from the entry after constant
// branch removal.
SmallPtrSet<VPBlockBase *, 16> Reachable(
llvm::from_range, vp_depth_first_shallow(Plan.getEntry()));
// Detach all unreachable blocks from their successors, removing their recipes
// and incoming values from phi recipes.
VPSymbolicValue Tmp(nullptr);
for (VPBlockBase *B : AllBlocks) {
if (Reachable.contains(B))
continue;
for (VPBlockBase *Succ : to_vector(B->successors())) {
if (auto *SuccBB = dyn_cast<VPBasicBlock>(Succ))
for (VPRecipeBase &R : SuccBB->phis())
cast<VPPhiAccessors>(&R)->removeIncomingValueFor(B);
VPBlockUtils::disconnectBlocks(B, Succ);
}
for (VPBasicBlock *DeadBB :
VPBlockUtils::blocksOnly<VPBasicBlock>(vp_depth_first_deep(B))) {
for (VPRecipeBase &R : make_early_inc_range(*DeadBB)) {
for (VPValue *Def : R.definedValues())
Def->replaceAllUsesWith(&Tmp);
R.eraseFromParent();
}
}
}
}
void VPlanTransforms::optimize(VPlan &Plan) {
RUN_VPLAN_PASS(removeRedundantInductionCasts, Plan);
RUN_VPLAN_PASS(reassociateHeaderMask, Plan);
RUN_VPLAN_PASS(simplifyRecipes, Plan);
RUN_VPLAN_PASS(removeDeadRecipes, Plan);
RUN_VPLAN_PASS(simplifyBlends, Plan);
RUN_VPLAN_PASS(legalizeAndOptimizeInductions, Plan);
RUN_VPLAN_PASS(narrowToSingleScalarRecipes, Plan);
RUN_VPLAN_PASS(removeRedundantExpandSCEVRecipes, Plan);
RUN_VPLAN_PASS(reassociateHeaderMask, Plan);
RUN_VPLAN_PASS(simplifyRecipes, Plan);
RUN_VPLAN_PASS(removeBranchOnConst, Plan, /*OnlyLatches=*/false);
RUN_VPLAN_PASS(removeDeadRecipes, Plan);
RUN_VPLAN_PASS(createAndOptimizeReplicateRegions, Plan);
RUN_VPLAN_PASS(mergeBlocksIntoPredecessors, Plan);
RUN_VPLAN_PASS(licm, Plan);
}
// Add a VPActiveLaneMaskPHIRecipe and related recipes to \p Plan and replace
// the loop terminator with a branch-on-cond recipe with the negated
// active-lane-mask as operand. Note that this turns the loop into an
// uncountable one. Only the existing terminator is replaced, all other existing
// recipes/users remain unchanged, except for poison-generating flags being
// dropped from the canonical IV increment. Return the created
// VPActiveLaneMaskPHIRecipe.
//
// The function adds the following recipes:
//
// vector.ph:
// %EntryInc = canonical-iv-increment-for-part CanonicalIVStart
// %EntryALM = active-lane-mask %EntryInc, TC
//
// vector.body:
// ...
// %P = active-lane-mask-phi [ %EntryALM, %vector.ph ], [ %ALM, %vector.body ]
// ...
// %InLoopInc = canonical-iv-increment-for-part CanonicalIVIncrement
// %ALM = active-lane-mask %InLoopInc, TC
// %Negated = Not %ALM
// branch-on-cond %Negated
//
static VPActiveLaneMaskPHIRecipe *
addVPLaneMaskPhiAndUpdateExitBranch(VPlan &Plan) {
VPRegionBlock *TopRegion = Plan.getVectorLoopRegion();
VPBasicBlock *EB = TopRegion->getExitingBasicBlock();
VPValue *StartV = Plan.getZero(TopRegion->getCanonicalIVType());
auto *CanonicalIVIncrement = TopRegion->getOrCreateCanonicalIVIncrement();
// TODO: Check if dropping the flags is needed.
TopRegion->clearCanonicalIVNUW(CanonicalIVIncrement);
DebugLoc DL = CanonicalIVIncrement->getDebugLoc();
// We can't use StartV directly in the ActiveLaneMask VPInstruction, since
// we have to take unrolling into account. Each part needs to start at
// Part * VF
auto *VecPreheader = Plan.getVectorPreheader();
VPBuilder Builder(VecPreheader);
// Create the ActiveLaneMask instruction using the correct start values.
VPValue *TC = Plan.getTripCount();
VPValue *VF = &Plan.getVF();
auto *EntryIncrement = Builder.createOverflowingOp(
VPInstruction::CanonicalIVIncrementForPart, {StartV, VF}, {false, false},
DL, "index.part.next");
// Create the active lane mask instruction in the VPlan preheader.
VPValue *ALMMultiplier =
Plan.getConstantInt(TopRegion->getCanonicalIVType(), 1);
auto *EntryALM = Builder.createNaryOp(VPInstruction::ActiveLaneMask,
{EntryIncrement, TC, ALMMultiplier}, DL,
"active.lane.mask.entry");
// Now create the ActiveLaneMaskPhi recipe in the main loop using the
// preheader ActiveLaneMask instruction.
auto *LaneMaskPhi =
new VPActiveLaneMaskPHIRecipe(EntryALM, DebugLoc::getUnknown());
auto *HeaderVPBB = TopRegion->getEntryBasicBlock();
LaneMaskPhi->insertBefore(*HeaderVPBB, HeaderVPBB->begin());
// Create the active lane mask for the next iteration of the loop before the
// original terminator.
VPRecipeBase *OriginalTerminator = EB->getTerminator();
Builder.setInsertPoint(OriginalTerminator);
auto *InLoopIncrement = Builder.createOverflowingOp(
VPInstruction::CanonicalIVIncrementForPart,
{CanonicalIVIncrement, &Plan.getVF()}, {false, false}, DL);
auto *ALM = Builder.createNaryOp(VPInstruction::ActiveLaneMask,
{InLoopIncrement, TC, ALMMultiplier}, DL,
"active.lane.mask.next");
LaneMaskPhi->addBackedgeValue(ALM);
// Replace the original terminator with BranchOnCond. We have to invert the
// mask here because a true condition means jumping to the exit block.
auto *NotMask = Builder.createNot(ALM, DL);
Builder.createNaryOp(VPInstruction::BranchOnCond, {NotMask}, DL);
OriginalTerminator->eraseFromParent();
return LaneMaskPhi;
}
void VPlanTransforms::addActiveLaneMask(VPlan &Plan,
bool UseActiveLaneMaskForControlFlow) {
VPRegionBlock *LoopRegion = Plan.getVectorLoopRegion();
auto *WideCanonicalIV =
findUserOf<VPWidenCanonicalIVRecipe>(LoopRegion->getCanonicalIV());
assert(WideCanonicalIV &&
"Must have widened canonical IV when tail folding!");
VPSingleDefRecipe *HeaderMask = vputils::findHeaderMask(Plan);
VPSingleDefRecipe *LaneMask;
if (UseActiveLaneMaskForControlFlow) {
LaneMask = addVPLaneMaskPhiAndUpdateExitBranch(Plan);
} else {
VPBuilder B = VPBuilder::getToInsertAfter(WideCanonicalIV);
VPValue *ALMMultiplier =
Plan.getConstantInt(LoopRegion->getCanonicalIVType(), 1);
LaneMask =
B.createNaryOp(VPInstruction::ActiveLaneMask,
{WideCanonicalIV, Plan.getTripCount(), ALMMultiplier},
nullptr, "active.lane.mask");
}
// Walk users of WideCanonicalIV and replace the header mask of the form
// (ICMP_ULE, WideCanonicalIV, backedge-taken-count) with an active-lane-mask,
// removing the old one to ensure there is always only a single header mask.
HeaderMask->replaceAllUsesWith(LaneMask);
HeaderMask->eraseFromParent();
}
template <typename Op0_t, typename Op1_t> struct RemoveMask_match {
Op0_t In;
Op1_t &Out;
RemoveMask_match(const Op0_t &In, Op1_t &Out) : In(In), Out(Out) {}
template <typename OpTy> bool match(OpTy *V) const {
if (m_Specific(In).match(V)) {
Out = nullptr;
return true;
}
return m_LogicalAnd(m_Specific(In), m_VPValue(Out)).match(V);
}
};
/// Match a specific mask \p In, or a combination of it (logical-and In, Out).
/// Returns the remaining part \p Out if so, or nullptr otherwise.
template <typename Op0_t, typename Op1_t>
static inline RemoveMask_match<Op0_t, Op1_t> m_RemoveMask(const Op0_t &In,
Op1_t &Out) {
return RemoveMask_match<Op0_t, Op1_t>(In, Out);
}
static std::optional<Intrinsic::ID> getVPDivRemIntrinsic(Intrinsic::ID IntrID) {
switch (IntrID) {
case Intrinsic::masked_udiv:
return Intrinsic::vp_udiv;
case Intrinsic::masked_sdiv:
return Intrinsic::vp_sdiv;
case Intrinsic::masked_urem:
return Intrinsic::vp_urem;
case Intrinsic::masked_srem:
return Intrinsic::vp_srem;
default:
return std::nullopt;
}
}
/// Try to optimize a \p CurRecipe masked by \p HeaderMask to a corresponding
/// EVL-based recipe without the header mask. Returns nullptr if no EVL-based
/// recipe could be created.
/// \p HeaderMask Header Mask.
/// \p CurRecipe Recipe to be transform.
/// \p EVL The explicit vector length parameter of vector-predication
/// intrinsics.
static VPRecipeBase *optimizeMaskToEVL(VPValue *HeaderMask,
VPRecipeBase &CurRecipe, VPValue &EVL) {
VPlan *Plan = CurRecipe.getParent()->getPlan();
DebugLoc DL = CurRecipe.getDebugLoc();
VPValue *Addr, *Mask, *EndPtr;
/// Adjust any end pointers so that they point to the end of EVL lanes not VF.
auto AdjustEndPtr = [&CurRecipe, &EVL](VPValue *EndPtr) {
auto *EVLEndPtr = cast<VPVectorEndPointerRecipe>(EndPtr)->clone();
EVLEndPtr->insertBefore(&CurRecipe);
// Cast EVL (i32) to match the VF operand's type.
VPValue *EVLAsVF = VPBuilder(EVLEndPtr).createScalarZExtOrTrunc(
&EVL, EVLEndPtr->getOperand(1)->getScalarType(), EVL.getScalarType(),
DebugLoc::getUnknown());
EVLEndPtr->setOperand(1, EVLAsVF);
return EVLEndPtr;
};
auto GetVPReverse = [&CurRecipe, &EVL, Plan,
DL](VPValue *V) -> VPWidenIntrinsicRecipe * {
if (!V)
return nullptr;
auto *Reverse = new VPWidenIntrinsicRecipe(
Intrinsic::experimental_vp_reverse, {V, Plan->getTrue(), &EVL},
V->getScalarType(), {}, {}, DL);
Reverse->insertBefore(&CurRecipe);
return Reverse;
};
if (match(&CurRecipe,
m_MaskedLoad(m_VPValue(Addr), m_RemoveMask(HeaderMask, Mask))))
return new VPWidenLoadEVLRecipe(cast<VPWidenLoadRecipe>(CurRecipe), Addr,
EVL, Mask);
VPValue *ReversedVal;
if (match(&CurRecipe, m_Reverse(m_VPValue(ReversedVal))) &&
match(ReversedVal,
m_MaskedLoad(m_VPValue(EndPtr),
m_Reverse(m_RemoveMask(HeaderMask, Mask)))) &&
match(EndPtr, m_VecEndPtr(m_VPValue(), m_Specific(&Plan->getVF())))) {
Mask = GetVPReverse(Mask);
Addr = AdjustEndPtr(EndPtr);
auto *LoadR = new VPWidenLoadEVLRecipe(
*cast<VPWidenLoadRecipe>(ReversedVal), Addr, EVL, Mask);
LoadR->insertBefore(&CurRecipe);
return new VPWidenIntrinsicRecipe(Intrinsic::experimental_vp_reverse,
{LoadR, Plan->getTrue(), &EVL},
LoadR->getScalarType(), {}, {}, DL);
}
VPValue *Stride;
if (match(&CurRecipe, m_Intrinsic<Intrinsic::experimental_vp_strided_load>(
m_VPValue(Addr), m_VPValue(Stride),
m_RemoveMask(HeaderMask, Mask),
m_TruncOrSelf(m_Specific(&Plan->getVF()))))) {
if (!Mask)
Mask = Plan->getTrue();
auto *NewLoad = cast<VPWidenMemIntrinsicRecipe>(&CurRecipe)->clone();
NewLoad->setOperand(2, Mask);
NewLoad->setOperand(3, &EVL);
return NewLoad;
}
VPValue *StoredVal;
if (match(&CurRecipe, m_MaskedStore(m_VPValue(Addr), m_VPValue(StoredVal),
m_RemoveMask(HeaderMask, Mask))))
return new VPWidenStoreEVLRecipe(cast<VPWidenStoreRecipe>(CurRecipe), Addr,
StoredVal, EVL, Mask);
if (match(&CurRecipe,
m_MaskedStore(m_VPValue(EndPtr), m_Reverse(m_VPValue(ReversedVal)),
m_Reverse(m_RemoveMask(HeaderMask, Mask)))) &&
match(EndPtr, m_VecEndPtr(m_VPValue(), m_Specific(&Plan->getVF())))) {
Mask = GetVPReverse(Mask);
Addr = AdjustEndPtr(EndPtr);
StoredVal = GetVPReverse(ReversedVal);
return new VPWidenStoreEVLRecipe(cast<VPWidenStoreRecipe>(CurRecipe), Addr,
StoredVal, EVL, Mask);
}
if (auto *Rdx = dyn_cast<VPReductionRecipe>(&CurRecipe))
if (Rdx->isConditional() &&
match(Rdx->getCondOp(), m_RemoveMask(HeaderMask, Mask)))
return new VPReductionEVLRecipe(*Rdx, EVL, Mask);
if (auto *Interleave = dyn_cast<VPInterleaveRecipe>(&CurRecipe))
if (Interleave->getMask() &&
match(Interleave->getMask(), m_RemoveMask(HeaderMask, Mask)))
return new VPInterleaveEVLRecipe(*Interleave, EVL, Mask);
VPValue *LHS, *RHS;
if (match(&CurRecipe, m_Select(m_RemoveMask(HeaderMask, Mask), m_VPValue(LHS),
m_VPValue(RHS))))
return new VPWidenIntrinsicRecipe(
Intrinsic::vp_merge, {Mask ? Mask : Plan->getTrue(), LHS, RHS, &EVL},
LHS->getScalarType(), {}, {}, DL);
if (match(&CurRecipe, m_LastActiveLane(m_Specific(HeaderMask)))) {
Type *Ty = CurRecipe.getVPSingleValue()->getScalarType();
VPValue *ZExt =
VPBuilder(&CurRecipe)
.createScalarZExtOrTrunc(&EVL, Ty, EVL.getScalarType(), DL);
return new VPInstruction(
Instruction::Sub, {ZExt, Plan->getConstantInt(Ty, 1)},
VPIRFlags::getDefaultFlags(Instruction::Sub), {}, DL);
}
// lhs | (headermask && rhs) -> vp.merge rhs, true, lhs, evl
if (match(&CurRecipe,
m_c_BinaryOr(m_VPValue(LHS),
m_LogicalAnd(m_Specific(HeaderMask), m_VPValue(RHS)))))
return new VPWidenIntrinsicRecipe(Intrinsic::vp_merge,
{RHS, Plan->getTrue(), LHS, &EVL},
LHS->getScalarType(), {}, {}, DL);
if (auto *IntrR = dyn_cast<VPWidenIntrinsicRecipe>(&CurRecipe))
if (auto VPID = getVPDivRemIntrinsic(IntrR->getVectorIntrinsicID()))
if (match(IntrR->getOperand(2), m_RemoveMask(HeaderMask, Mask)))
return new VPWidenIntrinsicRecipe(*VPID,
{IntrR->getOperand(0),
IntrR->getOperand(1),
Mask ? Mask : Plan->getTrue(), &EVL},
IntrR->getScalarType(), {}, {}, DL);
return nullptr;
}
/// Optimize away any EVL-based header masks to VP intrinsic based recipes.
/// The transforms here need to preserve the original semantics.
void VPlanTransforms::optimizeEVLMasks(VPlan &Plan) {
// Find the EVL-based header mask if it exists: icmp ult step-vector, EVL
VPValue *HeaderMask = nullptr, *EVL = nullptr;
for (VPRecipeBase &R : *Plan.getVectorLoopRegion()->getEntryBasicBlock()) {
if (match(&R, m_SpecificICmp(CmpInst::ICMP_ULT, m_StepVector(),
m_VPValue(EVL))) &&
match(EVL, m_EVL(m_VPValue()))) {
HeaderMask = R.getVPSingleValue();
break;
}
}
if (!HeaderMask)
return;
SmallVector<VPRecipeBase *> OldRecipes;
for (VPUser *U : collectUsersRecursively(HeaderMask)) {
VPRecipeBase *R = cast<VPRecipeBase>(U);
if (auto *NewR = optimizeMaskToEVL(HeaderMask, *R, *EVL)) {
NewR->insertBefore(R);
for (auto [Old, New] :
zip_equal(R->definedValues(), NewR->definedValues()))
Old->replaceAllUsesWith(New);
OldRecipes.push_back(R);
}
}
// Replace remaining (HeaderMask && Mask) with vp.merge (True, Mask,
// False, EVL)
for (VPUser *U : collectUsersRecursively(HeaderMask)) {
VPValue *Mask;
if (match(U, m_LogicalAnd(m_Specific(HeaderMask), m_VPValue(Mask)))) {
auto *LogicalAnd = cast<VPInstruction>(U);
auto *Merge = new VPWidenIntrinsicRecipe(
Intrinsic::vp_merge, {Plan.getTrue(), Mask, Plan.getFalse(), EVL},
Mask->getScalarType(), {}, {}, LogicalAnd->getDebugLoc());
Merge->insertBefore(LogicalAnd);
LogicalAnd->replaceAllUsesWith(Merge);
OldRecipes.push_back(LogicalAnd);
}
}
for (VPRecipeBase *R : reverse(OldRecipes)) {
SmallVector<VPValue *> PossiblyDead(R->operands());
R->eraseFromParent();
for (VPValue *Op : PossiblyDead)
recursivelyDeleteDeadRecipes(Op);
}
}
/// After replacing the canonical IV with a EVL-based IV, fixup recipes that use
/// VF to use the EVL instead to avoid incorrect updates on the penultimate
/// iteration.
static void fixupVFUsersForEVL(VPlan &Plan, VPValue &EVL) {
VPRegionBlock *LoopRegion = Plan.getVectorLoopRegion();
VPBasicBlock *Header = LoopRegion->getEntryBasicBlock();
// EVL is i32 but VF/VFxUF are IdxTy. Convert as needed.
VPValue *EVLAsIdx =
VPBuilder::getToInsertAfter(EVL.getDefiningRecipe())
.createScalarZExtOrTrunc(&EVL, Plan.getVF().getScalarType(),
EVL.getScalarType(), DebugLoc::getUnknown());
assert(all_of(Plan.getVF().users(),
[&Plan](VPUser *U) {
auto IsAllowedUser =
IsaPred<VPVectorEndPointerRecipe, VPScalarIVStepsRecipe,
VPWidenIntOrFpInductionRecipe,
VPWidenMemIntrinsicRecipe>;
if (match(U, m_Trunc(m_Specific(&Plan.getVF()))))
return all_of(cast<VPSingleDefRecipe>(U)->users(),
IsAllowedUser);
return IsAllowedUser(U);
}) &&
"User of VF that we can't transform to EVL.");
Plan.getVF().replaceUsesWithIf(EVLAsIdx, [](VPUser &U, unsigned Idx) {
return isa<VPWidenIntOrFpInductionRecipe, VPScalarIVStepsRecipe>(U);
});
assert(all_of(Plan.getVFxUF().users(),
match_fn(m_CombineOr(
m_c_Add(m_Specific(LoopRegion->getCanonicalIV()),
m_Specific(&Plan.getVFxUF())),
m_Isa<VPWidenPointerInductionRecipe>()))) &&
"Only users of VFxUF should be VPWidenPointerInductionRecipe and the "
"increment of the canonical induction.");
Plan.getVFxUF().replaceUsesWithIf(EVLAsIdx, [](VPUser &U, unsigned Idx) {
// Only replace uses in VPWidenPointerInductionRecipe; The increment of the
// canonical induction must not be updated.
return isa<VPWidenPointerInductionRecipe>(U);
});
// Create a scalar phi to track the previous EVL if fixed-order recurrence is
// contained.
bool ContainsFORs =
any_of(Header->phis(), IsaPred<VPFirstOrderRecurrencePHIRecipe>);
if (ContainsFORs) {
// TODO: Use VPInstruction::ExplicitVectorLength to get maximum EVL.
VPValue *MaxEVL = &Plan.getVF();
// Emit VPScalarCastRecipe in preheader if VF is not a 32 bits integer.
VPBuilder Builder(LoopRegion->getPreheaderVPBB());
MaxEVL = Builder.createScalarZExtOrTrunc(
MaxEVL, Type::getInt32Ty(Plan.getContext()), MaxEVL->getScalarType(),
DebugLoc::getUnknown());
Builder.setInsertPoint(Header, Header->getFirstNonPhi());
VPValue *PrevEVL = Builder.createScalarPhi(
{MaxEVL, &EVL}, DebugLoc::getUnknown(), "prev.evl");
for (VPBasicBlock *VPBB : VPBlockUtils::blocksOnly<VPBasicBlock>(
vp_depth_first_deep(Plan.getVectorLoopRegion()->getEntry()))) {
for (VPRecipeBase &R : *VPBB) {
VPValue *V1, *V2;
if (!match(&R,
m_VPInstruction<VPInstruction::FirstOrderRecurrenceSplice>(
m_VPValue(V1), m_VPValue(V2))))
continue;
VPValue *Imm = Plan.getOrAddLiveIn(
ConstantInt::getSigned(Type::getInt32Ty(Plan.getContext()), -1));
VPWidenIntrinsicRecipe *VPSplice = new VPWidenIntrinsicRecipe(
Intrinsic::experimental_vp_splice,
{V1, V2, Imm, Plan.getTrue(), PrevEVL, &EVL},
R.getVPSingleValue()->getScalarType(), {}, {}, R.getDebugLoc());
VPSplice->insertBefore(&R);
R.getVPSingleValue()->replaceAllUsesWith(VPSplice);
}
}
}
VPValue *HeaderMask = vputils::findHeaderMask(Plan);
if (!HeaderMask)
return;
// Ensure that any reduction that uses a select to mask off tail lanes does so
// in the vector loop, not the middle block, since EVL tail folding can have
// tail elements in the penultimate iteration.
assert(all_of(*Plan.getMiddleBlock(), [&Plan, HeaderMask](VPRecipeBase &R) {
if (match(&R, m_ComputeReductionResult(m_Select(m_Specific(HeaderMask),
m_VPValue(), m_VPValue()))))
return R.getOperand(0)->getDefiningRecipe()->getRegion() ==
Plan.getVectorLoopRegion();
return true;
}));
// Replace header masks with a mask equivalent to predicating by EVL:
//
// icmp ule widen-canonical-iv backedge-taken-count
// ->
// icmp ult step-vector, EVL
VPRecipeBase *EVLR = EVL.getDefiningRecipe();
VPBuilder Builder(EVLR->getParent(), std::next(EVLR->getIterator()));
Type *EVLType = EVL.getScalarType();
VPValue *EVLMask = Builder.createICmp(
CmpInst::ICMP_ULT,
Builder.createNaryOp(VPInstruction::StepVector, {}, EVLType), &EVL);
HeaderMask->replaceAllUsesWith(EVLMask);
}
/// Converts a tail folded vector loop region to step by
/// VPInstruction::ExplicitVectorLength elements instead of VF elements each
/// iteration.
///
/// - Add a VPCurrentIterationPHIRecipe and related recipes to \p Plan and
/// replaces all uses of the canonical IV except for the canonical IV
/// increment with a VPCurrentIterationPHIRecipe. The canonical IV is used
/// only for loop iterations counting after this transformation.
///
/// - The header mask is replaced with a header mask based on the EVL.
///
/// - Plans with FORs have a new phi added to keep track of the EVL of the
/// previous iteration, and VPFirstOrderRecurrencePHIRecipes are replaced with
/// @llvm.vp.splice.
///
/// The function uses the following definitions:
/// %StartV is the canonical induction start value.
///
/// The function adds the following recipes:
///
/// vector.ph:
/// ...
///
/// vector.body:
/// ...
/// %CurrentIter = CURRENT-ITERATION-PHI [ %StartV, %vector.ph ],
/// [ %NextIter, %vector.body ]
/// %AVL = phi [ trip-count, %vector.ph ], [ %NextAVL, %vector.body ]
/// %VPEVL = EXPLICIT-VECTOR-LENGTH %AVL
/// ...
/// %OpEVL = cast i32 %VPEVL to IVSize
/// %NextIter = add IVSize %OpEVL, %CurrentIter
/// %NextAVL = sub IVSize nuw %AVL, %OpEVL
/// ...
///
/// If MaxSafeElements is provided, the function adds the following recipes:
/// vector.ph:
/// ...
///
/// vector.body:
/// ...
/// %CurrentIter = CURRENT-ITERATION-PHI [ %StartV, %vector.ph ],
/// [ %NextIter, %vector.body ]
/// %AVL = phi [ trip-count, %vector.ph ], [ %NextAVL, %vector.body ]
/// %cmp = cmp ult %AVL, MaxSafeElements
/// %SAFE_AVL = select %cmp, %AVL, MaxSafeElements
/// %VPEVL = EXPLICIT-VECTOR-LENGTH %SAFE_AVL
/// ...
/// %OpEVL = cast i32 %VPEVL to IVSize
/// %NextIter = add IVSize %OpEVL, %CurrentIter
/// %NextAVL = sub IVSize nuw %AVL, %OpEVL
/// ...
///
void VPlanTransforms::addExplicitVectorLength(
VPlan &Plan, const std::optional<unsigned> &MaxSafeElements) {
if (Plan.hasScalarVFOnly())
return;
VPRegionBlock *LoopRegion = Plan.getVectorLoopRegion();
VPBasicBlock *Header = LoopRegion->getEntryBasicBlock();
auto *CanonicalIV = LoopRegion->getCanonicalIV();
auto *CanIVTy = LoopRegion->getCanonicalIVType();
VPValue *StartV = Plan.getZero(CanIVTy);
auto *CanonicalIVIncrement = LoopRegion->getOrCreateCanonicalIVIncrement();
// Create the CurrentIteration recipe in the vector loop.
auto *CurrentIteration =
new VPCurrentIterationPHIRecipe(StartV, DebugLoc::getUnknown());
CurrentIteration->insertBefore(*Header, Header->begin());
VPBuilder Builder(Header, Header->getFirstNonPhi());
// Create the AVL (application vector length), starting from TC -> 0 in steps
// of EVL.
VPPhi *AVLPhi = Builder.createScalarPhi(
{Plan.getTripCount()}, DebugLoc::getCompilerGenerated(), "avl");
VPValue *AVL = AVLPhi;
if (MaxSafeElements) {
// Support for MaxSafeDist for correct loop emission.
VPValue *AVLSafe = Plan.getConstantInt(CanIVTy, *MaxSafeElements);
VPValue *Cmp = Builder.createICmp(ICmpInst::ICMP_ULT, AVL, AVLSafe);
AVL = Builder.createSelect(Cmp, AVL, AVLSafe, DebugLoc::getUnknown(),
"safe_avl");
}
auto *VPEVL = Builder.createNaryOp(VPInstruction::ExplicitVectorLength, AVL,
DebugLoc::getUnknown(), "evl");
Builder.setInsertPoint(CanonicalIVIncrement);
VPValue *OpVPEVL = VPEVL;
auto *I32Ty = Type::getInt32Ty(Plan.getContext());
OpVPEVL = Builder.createScalarZExtOrTrunc(
OpVPEVL, CanIVTy, I32Ty, CanonicalIVIncrement->getDebugLoc());
auto *NextIter = Builder.createAdd(
OpVPEVL, CurrentIteration, CanonicalIVIncrement->getDebugLoc(),
"current.iteration.next", CanonicalIVIncrement->getNoWrapFlags());
CurrentIteration->addBackedgeValue(NextIter);
VPValue *NextAVL =
Builder.createSub(AVLPhi, OpVPEVL, DebugLoc::getCompilerGenerated(),
"avl.next", {/*NUW=*/true, /*NSW=*/false});
AVLPhi->addIncoming(NextAVL);
fixupVFUsersForEVL(Plan, *VPEVL);
removeDeadRecipes(Plan);
// Replace all uses of the canonical IV with VPCurrentIterationPHIRecipe
// except for the canonical IV increment.
CanonicalIV->replaceAllUsesWith(CurrentIteration);
CanonicalIVIncrement->setOperand(0, CanonicalIV);
// TODO: support unroll factor > 1.
Plan.setUF(1);
}
void VPlanTransforms::convertToVariableLengthStep(VPlan &Plan) {
// Find the vector loop entry by locating VPCurrentIterationPHIRecipe.
// There should be only one VPCurrentIteration in the entire plan.
VPCurrentIterationPHIRecipe *CurrentIteration = nullptr;
for (VPBasicBlock *VPBB : VPBlockUtils::blocksAs<VPBasicBlock>(
vp_depth_first_shallow(Plan.getEntry())))
for (VPRecipeBase &R : VPBB->phis())
if (auto *PhiR = dyn_cast<VPCurrentIterationPHIRecipe>(&R)) {
assert(!CurrentIteration &&
"Found multiple CurrentIteration. Only one expected");
CurrentIteration = PhiR;
}
// Early return if it is not variable-length stepping.
if (!CurrentIteration)
return;
VPBasicBlock *HeaderVPBB = CurrentIteration->getParent();
VPValue *CurrentIterationIncr = CurrentIteration->getBackedgeValue();
// Convert CurrentIteration to concrete recipe.
auto *ScalarR =
VPBuilder(CurrentIteration)
.createScalarPhi(
{CurrentIteration->getStartValue(), CurrentIterationIncr},
CurrentIteration->getDebugLoc(), "current.iteration.iv");
CurrentIteration->replaceAllUsesWith(ScalarR);
CurrentIteration->eraseFromParent();
// Replace CanonicalIVInc with CurrentIteration increment if it exists.
auto *CanonicalIV = cast<VPPhi>(&*HeaderVPBB->begin());
if (auto *CanIVInc = findUserOf(
CanonicalIV, m_c_Add(m_VPValue(), m_Specific(&Plan.getVFxUF())))) {
cast<VPInstruction>(CanIVInc)->replaceAllUsesWith(CurrentIterationIncr);
CanIVInc->eraseFromParent();
}
}
void VPlanTransforms::convertEVLExitCond(VPlan &Plan) {
VPRegionBlock *LoopRegion = Plan.getVectorLoopRegion();
if (!LoopRegion)
return;
VPBasicBlock *Header = LoopRegion->getEntryBasicBlock();
if (Header->empty())
return;
// The EVL IV is always at the beginning.
auto *EVLPhi = dyn_cast<VPCurrentIterationPHIRecipe>(&Header->front());
if (!EVLPhi)
return;
// Bail if not an EVL tail folded loop.
VPValue *AVL;
if (!match(EVLPhi->getBackedgeValue(),
m_c_Add(m_ZExtOrSelf(m_EVL(m_VPValue(AVL))), m_Specific(EVLPhi))))
return;
// The AVL may be capped to a safe distance.
VPValue *SafeAVL, *UnsafeAVL;
if (match(AVL,
m_Select(m_SpecificICmp(CmpInst::ICMP_ULT, m_VPValue(UnsafeAVL),
m_VPValue(SafeAVL)),
m_Deferred(UnsafeAVL), m_Deferred(SafeAVL))))
AVL = UnsafeAVL;
VPValue *AVLNext;
[[maybe_unused]] bool FoundAVLNext =
match(AVL, m_VPInstruction<Instruction::PHI>(
m_Specific(Plan.getTripCount()), m_VPValue(AVLNext)));
assert(FoundAVLNext && "Didn't find AVL backedge?");
VPBasicBlock *Latch = LoopRegion->getExitingBasicBlock();
auto *LatchBr = cast<VPInstruction>(Latch->getTerminator());
if (match(LatchBr, m_BranchOnCond(m_True())))
return;
VPValue *CanIVInc;
[[maybe_unused]] bool FoundIncrement = match(
LatchBr,
m_BranchOnCond(m_SpecificCmp(CmpInst::ICMP_EQ, m_VPValue(CanIVInc),
m_Specific(&Plan.getVectorTripCount()))));
assert(FoundIncrement &&
match(CanIVInc, m_Add(m_Specific(LoopRegion->getCanonicalIV()),
m_Specific(&Plan.getVFxUF()))) &&
"Expected BranchOnCond with ICmp comparing CanIV + VFxUF with vector "
"trip count");
Type *AVLTy = AVLNext->getScalarType();
VPBuilder Builder(LatchBr);
LatchBr->setOperand(
0, Builder.createICmp(CmpInst::ICMP_EQ, AVLNext, Plan.getZero(AVLTy)));
}
void VPlanTransforms::replaceSymbolicStrides(
VPlan &Plan, PredicatedScalarEvolution &PSE,
const DenseMap<Value *, const SCEV *> &StridesMap) {
// Replace VPValues for known constant strides guaranteed by predicated scalar
// evolution that are guaranteed to be guarded by the runtime checks; that is,
// blocks dominated by the vector preheader.
assert(!Plan.getVectorLoopRegion() &&
"expected to run before loop regions are created");
VPDominatorTree VPDT(Plan);
VPBlockBase *Preheader = Plan.getEntry()->getSuccessors()[1];
auto CanUseVersionedStride = [&VPDT, Preheader](VPUser &U, unsigned) {
auto *R = cast<VPRecipeBase>(&U);
VPBlockBase *Parent = R->getParent();
return VPDT.dominates(Preheader, Parent);
};
ValueToSCEVMapTy RewriteMap;
for (const SCEV *Stride : StridesMap.values()) {
using namespace SCEVPatternMatch;
auto *StrideV = cast<SCEVUnknown>(Stride)->getValue();
const APInt *StrideConst;
if (!match(PSE.getSCEV(StrideV), m_scev_APInt(StrideConst)))
// Only handle constant strides for now.
continue;
auto *CI = Plan.getConstantInt(*StrideConst);
if (VPValue *StrideVPV = Plan.getLiveIn(StrideV))
StrideVPV->replaceUsesWithIf(CI, CanUseVersionedStride);
// The versioned value may not be used in the loop directly but through a
// sext/zext. Add new live-ins in those cases.
for (Value *U : StrideV->users()) {
if (!isa<SExtInst, ZExtInst>(U))
continue;
VPValue *StrideVPV = Plan.getLiveIn(U);
if (!StrideVPV)
continue;
unsigned BW = U->getType()->getScalarSizeInBits();
APInt C =
isa<SExtInst>(U) ? StrideConst->sext(BW) : StrideConst->zext(BW);
VPValue *CI = Plan.getConstantInt(C);
StrideVPV->replaceUsesWithIf(CI, CanUseVersionedStride);
}
RewriteMap[StrideV] = PSE.getSCEV(StrideV);
}
for (VPRecipeBase &R : *Plan.getEntry()) {
auto *ExpSCEV = dyn_cast<VPExpandSCEVRecipe>(&R);
if (!ExpSCEV)
continue;
const SCEV *ScevExpr = ExpSCEV->getSCEV();
auto *NewSCEV =
SCEVParameterRewriter::rewrite(ScevExpr, *PSE.getSE(), RewriteMap);
if (NewSCEV != ScevExpr) {
VPValue *NewExp = vputils::getOrCreateVPValueForSCEVExpr(Plan, NewSCEV);
ExpSCEV->replaceAllUsesWith(NewExp);
if (Plan.getTripCount() == ExpSCEV)
Plan.resetTripCount(NewExp);
}
}
}
void VPlanTransforms::dropPoisonGeneratingRecipes(VPlan &Plan) {
// Collect recipes in the backward slice of `Root` that may generate a poison
// value that is used after vectorization.
SmallPtrSet<VPRecipeBase *, 16> Visited;
auto CollectPoisonGeneratingInstrsInBackwardSlice([&](VPRecipeBase *Root) {
SmallVector<VPRecipeBase *, 16> Worklist;
Worklist.push_back(Root);
// Traverse the backward slice of Root through its use-def chain.
while (!Worklist.empty()) {
VPRecipeBase *CurRec = Worklist.pop_back_val();
if (!Visited.insert(CurRec).second)
continue;
// Prune search if we find another recipe generating a widen memory
// instruction. Widen memory instructions involved in address computation
// will lead to gather/scatter instructions, which don't need to be
// handled.
if (isa<VPWidenMemoryRecipe, VPInterleaveRecipe, VPScalarIVStepsRecipe,
VPHeaderPHIRecipe>(CurRec))
continue;
// This recipe contributes to the address computation of a widen
// load/store. If the underlying instruction has poison-generating flags,
// drop them directly.
if (auto *RecWithFlags = dyn_cast<VPRecipeWithIRFlags>(CurRec)) {
VPValue *A, *B;
// Dropping disjoint from an OR may yield incorrect results, as some
// analysis may have converted it to an Add implicitly (e.g. SCEV used
// for dependence analysis). Instead, replace it with an equivalent Add.
// This is possible as all users of the disjoint OR only access lanes
// where the operands are disjoint or poison otherwise.
if (match(RecWithFlags, m_BinaryOr(m_VPValue(A), m_VPValue(B))) &&
RecWithFlags->isDisjoint()) {
VPBuilder Builder(RecWithFlags);
VPInstruction *New =
Builder.createAdd(A, B, RecWithFlags->getDebugLoc());
New->setUnderlyingValue(RecWithFlags->getUnderlyingValue());
RecWithFlags->replaceAllUsesWith(New);
RecWithFlags->eraseFromParent();
CurRec = New;
} else
RecWithFlags->dropPoisonGeneratingFlags();
} else {
Instruction *Instr = dyn_cast_or_null<Instruction>(
CurRec->getVPSingleValue()->getUnderlyingValue());
(void)Instr;
assert((!Instr || !Instr->hasPoisonGeneratingFlags()) &&
"found instruction with poison generating flags not covered by "
"VPRecipeWithIRFlags");
}
// Add new definitions to the worklist.
for (VPValue *Operand : CurRec->operands())
if (VPRecipeBase *OpDef = Operand->getDefiningRecipe())
Worklist.push_back(OpDef);
}
});
// We want to exclude the tail folding case, as we don't need to drop flags
// for operations computing the first lane in this case: the first lane of the
// header mask must always be true.
auto IsNotHeaderMask = [&Plan](VPValue *Mask) {
return Mask && !vputils::isHeaderMask(Mask, Plan);
};
// Traverse all the recipes in the VPlan and collect the poison-generating
// recipes in the backward slice starting at the address of a VPWidenRecipe or
// VPInterleaveRecipe.
auto Iter =
vp_depth_first_shallow(Plan.getVectorLoopRegion()->getEntryBasicBlock());
for (VPBasicBlock *VPBB : VPBlockUtils::blocksOnly<VPBasicBlock>(Iter)) {
for (VPRecipeBase &Recipe : *VPBB) {
if (auto *WidenRec = dyn_cast<VPWidenMemoryRecipe>(&Recipe)) {
VPRecipeBase *AddrDef = WidenRec->getAddr()->getDefiningRecipe();
if (AddrDef && WidenRec->isConsecutive() &&
IsNotHeaderMask(WidenRec->getMask()))
CollectPoisonGeneratingInstrsInBackwardSlice(AddrDef);
} else if (auto *InterleaveRec = dyn_cast<VPInterleaveRecipe>(&Recipe)) {
VPRecipeBase *AddrDef = InterleaveRec->getAddr()->getDefiningRecipe();
if (AddrDef && IsNotHeaderMask(InterleaveRec->getMask()))
CollectPoisonGeneratingInstrsInBackwardSlice(AddrDef);
}
}
}
}
void VPlanTransforms::createInterleaveGroups(
VPlan &Plan,
const SmallPtrSetImpl<const InterleaveGroup<Instruction> *>
&InterleaveGroups,
const bool &EpilogueAllowed) {
if (InterleaveGroups.empty())
return;
DenseMap<Instruction *, VPWidenMemoryRecipe *> IRMemberToRecipe;
for (VPBasicBlock *VPBB :
VPBlockUtils::blocksOnly<VPBasicBlock>(vp_depth_first_shallow(
Plan.getVectorLoopRegion()->getEntryBasicBlock())))
for (VPRecipeBase &R : make_filter_range(*VPBB, [](VPRecipeBase &R) {
return isa<VPWidenMemoryRecipe>(&R);
})) {
auto *MemR = cast<VPWidenMemoryRecipe>(&R);
IRMemberToRecipe[&MemR->getIngredient()] = MemR;
}
// Interleave memory: for each Interleave Group we marked earlier as relevant
// for this VPlan, replace the Recipes widening its memory instructions with a
// single VPInterleaveRecipe at its insertion point.
VPDominatorTree VPDT(Plan);
for (const auto *IG : InterleaveGroups) {
// Skip interleave groups where members don't have recipes. This can happen
// when removeDeadRecipes removes recipes that are part of interleave groups
// but have no users.
if (llvm::any_of(IG->members(), [&IRMemberToRecipe](Instruction *Member) {
return !IRMemberToRecipe.contains(Member);
}))
continue;
auto *Start = IRMemberToRecipe.lookup(IG->getMember(0));
VPIRMetadata InterleaveMD(*Start);
SmallVector<VPValue *, 4> StoredValues;
if (auto *StoreR = dyn_cast<VPWidenStoreRecipe>(Start->getAsRecipe()))
StoredValues.push_back(StoreR->getStoredValue());
for (unsigned I = 1; I < IG->getFactor(); ++I) {
Instruction *MemberI = IG->getMember(I);
if (!MemberI)
continue;
VPWidenMemoryRecipe *MemoryR = IRMemberToRecipe.lookup(MemberI);
if (auto *StoreR = dyn_cast<VPWidenStoreRecipe>(MemoryR->getAsRecipe()))
StoredValues.push_back(StoreR->getStoredValue());
InterleaveMD.intersect(*MemoryR);
}
bool NeedsMaskForGaps =
(IG->requiresScalarEpilogue() && !EpilogueAllowed) ||
(!StoredValues.empty() && !IG->isFull());
Instruction *IRInsertPos = IG->getInsertPos();
auto *InsertPos = IRMemberToRecipe.lookup(IRInsertPos);
VPRecipeBase *InsertPosR = InsertPos->getAsRecipe();
GEPNoWrapFlags NW = GEPNoWrapFlags::none();
if (auto *Gep = dyn_cast<GetElementPtrInst>(
getLoadStorePointerOperand(IRInsertPos)->stripPointerCasts()))
NW = Gep->getNoWrapFlags().withoutNoUnsignedWrap();
// Get or create the start address for the interleave group.
VPValue *Addr = Start->getAddr();
VPRecipeBase *AddrDef = Addr->getDefiningRecipe();
if (AddrDef && !VPDT.properlyDominates(AddrDef, InsertPosR)) {
// We cannot re-use the address of member zero because it does not
// dominate the insert position. Instead, use the address of the insert
// position and create a PtrAdd adjusting it to the address of member
// zero.
// TODO: Hoist Addr's defining recipe (and any operands as needed) to
// InsertPos or sink loads above zero members to join it.
assert(IG->getIndex(IRInsertPos) != 0 &&
"index of insert position shouldn't be zero");
auto &DL = IRInsertPos->getDataLayout();
APInt Offset(32,
DL.getTypeAllocSize(getLoadStoreType(IRInsertPos)) *
IG->getIndex(IRInsertPos),
/*IsSigned=*/true);
VPValue *OffsetVPV = Plan.getConstantInt(-Offset);
VPBuilder B(InsertPosR);
Addr = B.createNoWrapPtrAdd(InsertPos->getAddr(), OffsetVPV, NW);
}
// If the group is reverse, adjust the index to refer to the last vector
// lane instead of the first. We adjust the index from the first vector
// lane, rather than directly getting the pointer for lane VF - 1, because
// the pointer operand of the interleaved access is supposed to be uniform.
if (IG->isReverse()) {
auto *ReversePtr = new VPVectorEndPointerRecipe(
Addr, &Plan.getVF(), getLoadStoreType(IRInsertPos),
-(int64_t)IG->getFactor(), NW, InsertPosR->getDebugLoc());
ReversePtr->insertBefore(InsertPosR);
Addr = ReversePtr;
}
auto *VPIG = new VPInterleaveRecipe(
IG, Addr, StoredValues, InsertPos->getMask(), NeedsMaskForGaps,
InterleaveMD, InsertPosR->getDebugLoc());
VPIG->insertBefore(InsertPosR);
unsigned J = 0;
for (unsigned i = 0; i < IG->getFactor(); ++i)
if (Instruction *Member = IG->getMember(i)) {
VPRecipeBase *MemberR = IRMemberToRecipe.lookup(Member)->getAsRecipe();
if (!Member->getType()->isVoidTy()) {
VPValue *OriginalV = MemberR->getVPSingleValue();
OriginalV->replaceAllUsesWith(VPIG->getVPValue(J));
J++;
}
MemberR->eraseFromParent();
}
}
}
/// Expand a VPWidenIntOrFpInduction into executable recipes, for the initial
/// value, phi and backedge value. In the following example:
///
/// vector.ph:
/// Successor(s): vector loop
///
/// <x1> vector loop: {
/// vector.body:
/// WIDEN-INDUCTION %i = phi %start, %step, %vf
/// ...
/// EMIT branch-on-count ...
/// No successors
/// }
///
/// WIDEN-INDUCTION will get expanded to:
///
/// vector.ph:
/// ...
/// vp<%induction.start> = ...
/// vp<%induction.increment> = ...
///
/// Successor(s): vector loop
///
/// <x1> vector loop: {
/// vector.body:
/// ir<%i> = WIDEN-PHI vp<%induction.start>, vp<%vec.ind.next>
/// ...
/// vp<%vec.ind.next> = add ir<%i>, vp<%induction.increment>
/// EMIT branch-on-count ...
/// No successors
/// }
static void
expandVPWidenIntOrFpInduction(VPWidenIntOrFpInductionRecipe *WidenIVR) {
VPlan *Plan = WidenIVR->getParent()->getPlan();
VPValue *Start = WidenIVR->getStartValue();
VPValue *Step = WidenIVR->getStepValue();
VPValue *VF = WidenIVR->getVFValue();
DebugLoc DL = WidenIVR->getDebugLoc();
// The value from the original loop to which we are mapping the new induction
// variable.
Type *Ty = WidenIVR->getScalarType();
const InductionDescriptor &ID = WidenIVR->getInductionDescriptor();
Instruction::BinaryOps AddOp;
Instruction::BinaryOps MulOp;
VPIRFlags Flags = *WidenIVR;
if (ID.getKind() == InductionDescriptor::IK_IntInduction) {
AddOp = Instruction::Add;
MulOp = Instruction::Mul;
} else {
AddOp = ID.getInductionOpcode();
MulOp = Instruction::FMul;
}
// If the phi is truncated, truncate the start and step values.
VPBuilder Builder(Plan->getVectorPreheader());
Type *StepTy = Step->getScalarType();
if (Ty->getScalarSizeInBits() < StepTy->getScalarSizeInBits()) {
assert(StepTy->isIntegerTy() && "Truncation requires an integer type");
Step = Builder.createScalarCast(Instruction::Trunc, Step, Ty, DL);
Start = Builder.createScalarCast(Instruction::Trunc, Start, Ty, DL);
StepTy = Ty;
}
// Construct the initial value of the vector IV in the vector loop preheader.
Type *IVIntTy =
IntegerType::get(Plan->getContext(), StepTy->getScalarSizeInBits());
VPValue *Init = Builder.createNaryOp(VPInstruction::StepVector, {}, IVIntTy);
if (StepTy->isFloatingPointTy())
Init = Builder.createWidenCast(Instruction::UIToFP, Init, StepTy);
VPValue *SplatStart = Builder.createNaryOp(VPInstruction::Broadcast, Start);
VPValue *SplatStep = Builder.createNaryOp(VPInstruction::Broadcast, Step);
Init = Builder.createNaryOp(MulOp, {Init, SplatStep}, Flags);
Init = Builder.createNaryOp(AddOp, {SplatStart, Init}, Flags,
DebugLoc::getUnknown(), "induction");
// Create the widened phi of the vector IV.
auto *WidePHI = VPBuilder(WidenIVR).createWidenPhi(
Init, WidenIVR->getDebugLoc(), "vec.ind");
// Create the backedge value for the vector IV.
VPValue *Inc;
VPValue *Prev;
// If unrolled, use the increment and prev value from the operands.
if (auto *SplatVF = WidenIVR->getSplatVFValue()) {
Inc = SplatVF;
Prev = WidenIVR->getLastUnrolledPartOperand();
} else {
// Move the insertion point after the VF definition when the VF is defined
// inside a loop, such as for EVL tail-folding.
if (VPRecipeBase *R = VF->getDefiningRecipe())
if (R->getParent()->getEnclosingLoopRegion())
Builder.setInsertPoint(R->getParent(), std::next(R->getIterator()));
// Multiply the vectorization factor by the step using integer or
// floating-point arithmetic as appropriate.
if (StepTy->isFloatingPointTy())
VF = Builder.createScalarCast(Instruction::CastOps::UIToFP, VF, StepTy,
DL);
else
VF = Builder.createScalarZExtOrTrunc(VF, StepTy, VF->getScalarType(), DL);
Inc = Builder.createNaryOp(MulOp, {Step, VF}, Flags);
Inc = Builder.createNaryOp(VPInstruction::Broadcast, Inc);
Prev = WidePHI;
}
VPBasicBlock *ExitingBB = Plan->getVectorLoopRegion()->getExitingBasicBlock();
Builder.setInsertPoint(ExitingBB, ExitingBB->getTerminator()->getIterator());
auto *Next = Builder.createNaryOp(AddOp, {Prev, Inc}, Flags,
WidenIVR->getDebugLoc(), "vec.ind.next");
WidePHI->addIncoming(Next);
WidenIVR->replaceAllUsesWith(WidePHI);
}
/// Expand a VPWidenPointerInductionRecipe into executable recipes, for the
/// initial value, phi and backedge value. In the following example:
///
/// <x1> vector loop: {
/// vector.body:
/// EMIT ir<%ptr.iv> = WIDEN-POINTER-INDUCTION %start, %step, %vf
/// ...
/// EMIT branch-on-count ...
/// }
///
/// WIDEN-POINTER-INDUCTION will get expanded to:
///
/// <x1> vector loop: {
/// vector.body:
/// EMIT-SCALAR %pointer.phi = phi %start, %ptr.ind
/// EMIT %mul = mul %stepvector, %step
/// EMIT %vector.gep = wide-ptradd %pointer.phi, %mul
/// ...
/// EMIT %ptr.ind = ptradd %pointer.phi, %vf
/// EMIT branch-on-count ...
/// }
static void expandVPWidenPointerInduction(VPWidenPointerInductionRecipe *R) {
VPlan *Plan = R->getParent()->getPlan();
VPValue *Start = R->getStartValue();
VPValue *Step = R->getStepValue();
VPValue *VF = R->getVFValue();
assert(R->getInductionDescriptor().getKind() ==
InductionDescriptor::IK_PtrInduction &&
"Not a pointer induction according to InductionDescriptor!");
assert(R->getScalarType()->isPointerTy() && "Unexpected type.");
assert(!R->onlyScalarsGenerated(Plan->hasScalableVF()) &&
"Recipe should have been replaced");
VPBuilder Builder(R);
DebugLoc DL = R->getDebugLoc();
// Build a scalar pointer phi.
VPPhi *ScalarPtrPhi = Builder.createScalarPhi(Start, DL, "pointer.phi");
// Create actual address geps that use the pointer phi as base and a
// vectorized version of the step value (<step*0, ..., step*N>) as offset.
Builder.setInsertPoint(R->getParent(), R->getParent()->getFirstNonPhi());
Type *StepTy = Step->getScalarType();
VPValue *Offset = Builder.createNaryOp(VPInstruction::StepVector, {}, StepTy);
Offset = Builder.createOverflowingOp(Instruction::Mul, {Offset, Step});
VPValue *PtrAdd =
Builder.createWidePtrAdd(ScalarPtrPhi, Offset, DL, "vector.gep");
R->replaceAllUsesWith(PtrAdd);
// Create the backedge value for the scalar pointer phi.
VPBasicBlock *ExitingBB = Plan->getVectorLoopRegion()->getExitingBasicBlock();
Builder.setInsertPoint(ExitingBB, ExitingBB->getTerminator()->getIterator());
VF = Builder.createScalarZExtOrTrunc(VF, StepTy, VF->getScalarType(), DL);
VPValue *Inc = Builder.createOverflowingOp(Instruction::Mul, {Step, VF});
VPValue *InductionGEP =
Builder.createPtrAdd(ScalarPtrPhi, Inc, DL, "ptr.ind");
ScalarPtrPhi->addIncoming(InductionGEP);
}
/// Expand a VPDerivedIVRecipe into executable recipes.
static void expandVPDerivedIV(VPDerivedIVRecipe *R) {
VPBuilder Builder(R);
VPIRValue *Start = R->getStartValue();
VPValue *Step = R->getStepValue();
VPValue *Index = R->getIndex();
Type *StepTy = Step->getScalarType();
Type *IndexTy = Index->getScalarType();
Index = StepTy->isIntegerTy()
? Builder.createScalarSExtOrTrunc(
Index, StepTy, IndexTy, DebugLoc::getCompilerGenerated())
: Builder.createScalarCast(Instruction::SIToFP, Index, StepTy,
DebugLoc::getCompilerGenerated());
switch (R->getInductionKind()) {
case InductionDescriptor::IK_IntInduction: {
assert(Index->getScalarType() == Start->getScalarType() &&
"Index type does not match StartValue type");
return R->replaceAllUsesWith(Builder.createAdd(
Start, Builder.createOverflowingOp(Instruction::Mul, {Index, Step})));
}
case InductionDescriptor::IK_PtrInduction:
return R->replaceAllUsesWith(Builder.createPtrAdd(
Start, Builder.createOverflowingOp(Instruction::Mul, {Index, Step})));
case InductionDescriptor::IK_FpInduction: {
assert(StepTy->isFloatingPointTy() && "Expected FP Step value");
const FPMathOperator *FPBinOp = R->getFPBinOp();
assert(FPBinOp &&
(FPBinOp->getOpcode() == Instruction::FAdd ||
FPBinOp->getOpcode() == Instruction::FSub) &&
"Original BinOp should be defined for FP induction");
FastMathFlags FMF = FPBinOp->getFastMathFlags();
VPValue *FMul = Builder.createNaryOp(Instruction::FMul, {Step, Index}, FMF);
return R->replaceAllUsesWith(
Builder.createNaryOp(FPBinOp->getOpcode(), {Start, FMul}, FMF));
}
case InductionDescriptor::IK_NoInduction:
return;
}
llvm_unreachable("Unhandled induction kind");
}
void VPlanTransforms::dissolveLoopRegions(VPlan &Plan) {
// Replace loop regions with explicity CFG.
SmallVector<VPRegionBlock *> LoopRegions;
for (VPRegionBlock *R : VPBlockUtils::blocksOnly<VPRegionBlock>(
vp_depth_first_deep(Plan.getEntry()))) {
if (!R->isReplicator())
LoopRegions.push_back(R);
}
for (VPRegionBlock *R : LoopRegions)
R->dissolveToCFGLoop();
}
void VPlanTransforms::expandBranchOnTwoConds(VPlan &Plan) {
SmallVector<VPInstruction *> WorkList;
// The transform runs after dissolving loop regions, so all VPBasicBlocks
// terminated with BranchOnTwoConds are reached via a shallow traversal.
for (VPBasicBlock *VPBB : VPBlockUtils::blocksAs<VPBasicBlock>(
vp_depth_first_shallow(Plan.getEntry()))) {
if (!VPBB->empty() && match(&VPBB->back(), m_BranchOnTwoConds()))
WorkList.push_back(cast<VPInstruction>(&VPBB->back()));
}
// Expand BranchOnTwoConds instructions into explicit CFG with two new
// single-condition branches:
// 1. A branch that replaces BranchOnTwoConds, jumps to the first successor if
// the first condition is true, and otherwise jumps to a new interim block.
// 2. A branch that ends the interim block, jumps to the second successor if
// the second condition is true, and otherwise jumps to the third
// successor.
for (VPInstruction *Br : WorkList) {
assert(Br->getNumOperands() == 2 &&
"BranchOnTwoConds must have exactly 2 conditions");
DebugLoc DL = Br->getDebugLoc();
VPBasicBlock *BrOnTwoCondsBB = Br->getParent();
const auto Successors = to_vector(BrOnTwoCondsBB->getSuccessors());
assert(Successors.size() == 3 &&
"BranchOnTwoConds must have exactly 3 successors");
for (VPBlockBase *Succ : Successors)
VPBlockUtils::disconnectBlocks(BrOnTwoCondsBB, Succ);
VPValue *Cond0 = Br->getOperand(0);
VPValue *Cond1 = Br->getOperand(1);
VPBlockBase *Succ0 = Successors[0];
VPBlockBase *Succ1 = Successors[1];
VPBlockBase *Succ2 = Successors[2];
// If the successor block for both conditions is the same, then combine the
// two conditions and plant a single conditional branch.
if (Succ0 == Succ1) {
VPBuilder Builder(Br);
VPValue *Combined = Builder.createOr(Cond0, Cond1, DL);
Builder.createNaryOp(VPInstruction::BranchOnCond, {Combined}, DL);
VPBlockUtils::connectBlocks(BrOnTwoCondsBB, Succ0);
VPBlockUtils::connectBlocks(BrOnTwoCondsBB, Succ2);
Br->eraseFromParent();
continue;
}
assert(!Succ0->getParent() && !Succ1->getParent() && !Succ2->getParent() &&
!BrOnTwoCondsBB->getParent() && "regions must already be dissolved");
VPBasicBlock *InterimBB =
Plan.createVPBasicBlock(BrOnTwoCondsBB->getName() + ".interim");
VPBuilder(BrOnTwoCondsBB)
.createNaryOp(VPInstruction::BranchOnCond, {Cond0}, DL);
VPBlockUtils::connectBlocks(BrOnTwoCondsBB, Succ0);
VPBlockUtils::connectBlocks(BrOnTwoCondsBB, InterimBB);
VPBuilder(InterimBB).createNaryOp(VPInstruction::BranchOnCond, {Cond1}, DL);
VPBlockUtils::connectBlocks(InterimBB, Succ1);
VPBlockUtils::connectBlocks(InterimBB, Succ2);
Br->eraseFromParent();
}
}
void VPlanTransforms::convertToConcreteRecipes(VPlan &Plan) {
for (VPBasicBlock *VPBB : VPBlockUtils::blocksOnly<VPBasicBlock>(
vp_depth_first_deep(Plan.getEntry()))) {
for (VPRecipeBase &R : make_early_inc_range(*VPBB)) {
VPBuilder Builder(&R);
if (auto *WidenIVR = dyn_cast<VPWidenIntOrFpInductionRecipe>(&R)) {
expandVPWidenIntOrFpInduction(WidenIVR);
WidenIVR->eraseFromParent();
continue;
}
if (auto *WidenIVR = dyn_cast<VPWidenPointerInductionRecipe>(&R)) {
// If the recipe only generates scalars, scalarize it instead of
// expanding it.
if (WidenIVR->onlyScalarsGenerated(Plan.hasScalableVF())) {
VPValue *PtrAdd =
scalarizeVPWidenPointerInduction(WidenIVR, Plan, Builder);
WidenIVR->replaceAllUsesWith(PtrAdd);
WidenIVR->eraseFromParent();
continue;
}
expandVPWidenPointerInduction(WidenIVR);
WidenIVR->eraseFromParent();
continue;
}
if (auto *DerivedIVR = dyn_cast<VPDerivedIVRecipe>(&R)) {
expandVPDerivedIV(DerivedIVR);
DerivedIVR->eraseFromParent();
continue;
}
if (auto *WideCanIV = dyn_cast<VPWidenCanonicalIVRecipe>(&R)) {
VPValue *CanIV = WideCanIV->getCanonicalIV();
Type *CanIVTy = CanIV->getScalarType();
VPValue *Step = WideCanIV->getStepValue();
if (!Step) {
assert(Plan.getConcreteUF() == 1 &&
"Expected unroller to have materialized step for UF != 1");
Step = Plan.getZero(CanIVTy);
}
CanIV = Builder.createNaryOp(VPInstruction::Broadcast, CanIV);
Step = Builder.createNaryOp(VPInstruction::Broadcast, Step);
Step = Builder.createAdd(
Step, Builder.createNaryOp(VPInstruction::StepVector, {}, CanIVTy));
VPValue *CanVecIV =
Builder.createAdd(CanIV, Step, WideCanIV->getDebugLoc(), "vec.iv",
WideCanIV->getNoWrapFlags());
WideCanIV->replaceAllUsesWith(CanVecIV);
WideCanIV->eraseFromParent();
continue;
}
// Expand VPBlendRecipe into VPInstruction::Select.
if (auto *Blend = dyn_cast<VPBlendRecipe>(&R)) {
VPValue *Select = Blend->getIncomingValue(0);
for (unsigned I = 1; I != Blend->getNumIncomingValues(); ++I)
Select = Builder.createSelect(Blend->getMask(I),
Blend->getIncomingValue(I), Select,
R.getDebugLoc(), "predphi", *Blend);
Blend->replaceAllUsesWith(Select);
Blend->eraseFromParent();
continue;
}
if (auto *VEPR = dyn_cast<VPVectorEndPointerRecipe>(&R)) {
if (!VEPR->getOffset()) {
assert(Plan.getConcreteUF() == 1 &&
"Expected unroller to have materialized offset for UF != 1");
VEPR->materializeOffset();
}
continue;
}
if (auto *Expr = dyn_cast<VPExpressionRecipe>(&R)) {
Expr->decompose();
Expr->eraseFromParent();
continue;
}
// Expand LastActiveLane into Not + FirstActiveLane + Sub.
auto *LastActiveL = dyn_cast<VPInstruction>(&R);
if (LastActiveL &&
LastActiveL->getOpcode() == VPInstruction::LastActiveLane) {
// Create Not(Mask) for all operands.
SmallVector<VPValue *, 2> NotMasks;
for (VPValue *Op : LastActiveL->operands()) {
VPValue *NotMask = Builder.createNot(Op, LastActiveL->getDebugLoc());
NotMasks.push_back(NotMask);
}
// Create FirstActiveLane on the inverted masks.
VPValue *FirstInactiveLane = Builder.createFirstActiveLane(
NotMasks, LastActiveL->getDebugLoc(), "first.inactive.lane");
// Subtract 1 to get the last active lane.
VPValue *One =
Plan.getConstantInt(FirstInactiveLane->getScalarType(), 1);
VPValue *LastLane =
Builder.createSub(FirstInactiveLane, One,
LastActiveL->getDebugLoc(), "last.active.lane");
LastActiveL->replaceAllUsesWith(LastLane);
LastActiveL->eraseFromParent();
continue;
}
// Lower MaskedCond with block mask to LogicalAnd.
if (match(&R, m_VPInstruction<VPInstruction::MaskedCond>())) {
auto *VPI = cast<VPInstruction>(&R);
assert(VPI->isMasked() &&
"Unmasked MaskedCond should be simplified earlier");
VPI->replaceAllUsesWith(Builder.createNaryOp(
VPInstruction::LogicalAnd, {VPI->getMask(), VPI->getOperand(0)}));
VPI->eraseFromParent();
continue;
}
// Lower CanonicalIVIncrementForPart to plain Add.
if (match(
&R,
m_VPInstruction<VPInstruction::CanonicalIVIncrementForPart>())) {
auto *VPI = cast<VPInstruction>(&R);
VPValue *Add = Builder.createOverflowingOp(
Instruction::Add, VPI->operands(), VPI->getNoWrapFlags(),
VPI->getDebugLoc());
VPI->replaceAllUsesWith(Add);
VPI->eraseFromParent();
continue;
}
// Lower BranchOnCount to ICmp + BranchOnCond.
VPValue *IV, *TC;
if (match(&R, m_BranchOnCount(m_VPValue(IV), m_VPValue(TC)))) {
auto *BranchOnCountInst = cast<VPInstruction>(&R);
DebugLoc DL = BranchOnCountInst->getDebugLoc();
VPValue *Cond = Builder.createICmp(CmpInst::ICMP_EQ, IV, TC, DL);
Builder.createNaryOp(VPInstruction::BranchOnCond, Cond, DL);
BranchOnCountInst->eraseFromParent();
continue;
}
VPValue *VectorStep;
VPValue *ScalarStep;
if (!match(&R, m_VPInstruction<VPInstruction::WideIVStep>(
m_VPValue(VectorStep), m_VPValue(ScalarStep))))
continue;
// Expand WideIVStep.
auto *VPI = cast<VPInstruction>(&R);
Type *IVTy = VPI->getScalarType();
if (VectorStep->getScalarType() != IVTy) {
Instruction::CastOps CastOp = IVTy->isFloatingPointTy()
? Instruction::UIToFP
: Instruction::Trunc;
VectorStep = Builder.createWidenCast(CastOp, VectorStep, IVTy);
}
assert(!match(ScalarStep, m_One()) && "Expected non-unit scalar-step");
if (ScalarStep->getScalarType() != IVTy) {
ScalarStep =
Builder.createWidenCast(Instruction::Trunc, ScalarStep, IVTy);
}
VPIRFlags Flags;
unsigned MulOpc;
if (IVTy->isFloatingPointTy()) {
MulOpc = Instruction::FMul;
Flags = VPI->getFastMathFlagsOrNone();
} else {
MulOpc = Instruction::Mul;
Flags = VPIRFlags::getDefaultFlags(MulOpc);
}
VPInstruction *Mul = Builder.createNaryOp(
MulOpc, {VectorStep, ScalarStep}, Flags, R.getDebugLoc());
VectorStep = Mul;
VPI->replaceAllUsesWith(VectorStep);
VPI->eraseFromParent();
}
}
}
struct EarlyExitInfo {
VPBasicBlock *EarlyExitingVPBB;
VPIRBasicBlock *EarlyExitVPBB;
VPValue *CondToExit;
};
/// Update \p Plan to mask memory operations in the loop based on whether the
/// early exit is taken or not.
static bool handleUncountableExitsWithSideEffects(
VPlan &Plan, SmallVectorImpl<EarlyExitInfo> &Exits,
VPBasicBlock *HeaderVPBB, VPBasicBlock *LatchVPBB, VPBasicBlock *MiddleVPBB,
Loop *TheLoop, PredicatedScalarEvolution &PSE, DominatorTree &DT,
AssumptionCache *AC, VPDominatorTree &VPDT) {
// Disconnect early exiting blocks from successors, remove branches. We
// currently don't support multiple uses for recipes involved in creating
// the uncountable exit condition.
for (auto &Exit : Exits) {
if (Exit.EarlyExitingVPBB == LatchVPBB)
continue;
for (VPRecipeBase &R : Exit.EarlyExitVPBB->phis())
cast<VPIRPhi>(&R)->removeIncomingValueFor(Exit.EarlyExitingVPBB);
Exit.EarlyExitingVPBB->getTerminator()->eraseFromParent();
VPBlockUtils::disconnectBlocks(Exit.EarlyExitingVPBB, Exit.EarlyExitVPBB);
}
// We can abandon a VPlan entirely if we return false here, so we shouldn't
// crash if some earlier assumptions on scalar IR don't hold for the vplan
// version of the loop.
SmallVector<VPInstruction *, 2> GEPs;
SmallVector<VPInstruction *, 8> ConditionRecipes;
std::optional<VPValue *> Cond =
vputils::getRecipesForUncountableExit(ConditionRecipes, GEPs, LatchVPBB);
if (!Cond)
return false;
// Find load contributing to condition.
VPRecipeBase *CondLoad = nullptr;
for (auto *Recipe : ConditionRecipes) {
if (match(Recipe, m_VPInstruction<Instruction::Load>(m_VPValue()))) {
// TODO: Support more than one load. Needs legality updates too.
assert(CondLoad == nullptr && "Too many condition loads");
CondLoad = Recipe;
}
}
assert(CondLoad && "Couldn't find load");
// Ensure that we are guaranteed to be able to dereference the memory used
// for determining the uncountable exit for the maximum possible number of
// scalar iterations of the loop.
//
// TODO: Support first-faulting loads in cases where we don't know whether
// all possible addresses are dereferenceable.
{
SmallVector<const SCEVPredicate *, 4> Predicates;
VPSingleDefRecipe *Load = cast<VPSingleDefRecipe>(CondLoad);
VPValue *Ptr = Load->getOperand(0);
const SCEV *PtrSCEV = vputils::getSCEVExprForVPValue(Ptr, PSE, TheLoop);
const DataLayout &DL = Plan.getDataLayout();
APInt EltSize(DL.getIndexTypeSizeInBits(Ptr->getScalarType()),
DL.getTypeStoreSize(Load->getScalarType()).getFixedValue());
if (!isDereferenceableAndAlignedInLoop(
PtrSCEV, cast<LoadInst>(Load->getUnderlyingInstr())->getAlign(),
PSE.getSE()->getConstant(EltSize), TheLoop, *PSE.getSE(), DT, AC,
&Predicates))
return false;
}
// Check GEPs to see if we can link them to a widen IV recipe with a step of
// 1; we're only interested in contiguous accesses for the condition load
// right now.
for (auto *GEP : GEPs) {
VPValue *MaybeIV = nullptr;
if (!match(GEP, m_VPInstruction<Instruction::GetElementPtr>(
m_LiveIn(), m_VPValue(MaybeIV))))
return false;
auto *WIV = dyn_cast<VPWidenInductionRecipe>(MaybeIV);
if (!WIV)
return false;
if (!match(WIV->getStartValue(), m_SpecificInt(0)) ||
!match(WIV->getStepValue(), m_SpecificInt(1)))
return false;
}
// Find an insertion point. Default to the end of the header but override
// if we find a memory op that needs masking before the condition load.
auto InsertIt = HeaderVPBB->end();
VPRecipeBase *CondR = (*Cond)->getDefiningRecipe();
bool CondMoveNeeded = CondR->getParent() != HeaderVPBB;
for (VPRecipeBase &R : *HeaderVPBB) {
if (&R == CondLoad)
continue;
if (R.mayReadOrWriteMemory()) {
if (!VPDT.properlyDominates(CondR, &R)) {
CondMoveNeeded = true;
InsertIt = R.getIterator();
}
break;
}
}
// If another memory operation would take place before the comparison to
// determine whether to exit early or the comparison doesn't take place in
// the header, move the comparison (and supporting recipes).
if (CondMoveNeeded)
for (auto *Recipe : reverse(ConditionRecipes))
Recipe->moveBefore(*HeaderVPBB, InsertIt);
// Create a mask to represent all lanes that fully execute in the vector loop,
// stopping short of any early exit.
VPBuilder MaskBuilder(HeaderVPBB, InsertIt);
VPValue *FirstActive = MaskBuilder.createFirstActiveLane(*Cond);
VPValue *IV = cast<VPSingleDefRecipe>(&HeaderVPBB->front());
Type *IVScalarTy = IV->getScalarType();
Type *FirstActiveTy = FirstActive->getScalarType();
VPValue *ALMMultiplier = Plan.getConstantInt(IVScalarTy, 1);
VPValue *Zero = Plan.getZero(IVScalarTy);
FirstActive = MaskBuilder.createScalarZExtOrTrunc(FirstActive, IVScalarTy,
FirstActiveTy, DebugLoc());
VPValue *Mask = MaskBuilder.createNaryOp(VPInstruction::ActiveLaneMask,
{Zero, FirstActive, ALMMultiplier},
DebugLoc(), "uncountable.exit.mask");
// Convert all other memory operations to use the mask.
for (VPBasicBlock *VPBB : vp_rpo_plain_cfg_loop_body(HeaderVPBB))
for (VPRecipeBase &R : *VPBB)
if (R.mayReadOrWriteMemory() && &R != CondLoad) {
// TODO: Handle conditional memory operations in the loop.
if (!VPDT.dominates(R.getParent(), LatchVPBB))
return false;
cast<VPInstruction>(&R)->addMask(Mask);
}
// Update middle block branch to compare (IV + however many lanes were active)
// against the full trip count, since we may be exiting the vector loop early.
// If we didn't take an early exit, we should get the equivalent of VF from
// the FirstActiveLane.
VPBuilder MiddleBuilder(MiddleVPBB, MiddleVPBB->end());
VPValue *ScalarIV = MiddleBuilder.createNaryOp(VPInstruction::ExtractLane,
{Zero, IV}, DebugLoc());
VPValue *ExitIV = MiddleBuilder.createAdd(ScalarIV, FirstActive);
VPValue *FullTC =
MiddleBuilder.createICmp(CmpInst::ICMP_EQ, ExitIV, Plan.getTripCount());
MiddleBuilder.createNaryOp(VPInstruction::BranchOnCond, {FullTC});
// Update resume phi in scalar.ph.
VPBasicBlock *ScalarPH = Plan.getScalarPreheader();
auto Phis = ScalarPH->phis();
// TODO: Handle more than one Phi; re-derive from IV.
// TODO: Handle reductions.
if (range_size(Phis) != 1)
return false;
VPPhi *ContinueIV = cast<VPPhi>(Phis.begin());
ContinueIV->setOperand(0, ExitIV);
return true;
}
bool VPlanTransforms::handleUncountableEarlyExits(
VPlan &Plan, VPBasicBlock *HeaderVPBB, VPBasicBlock *LatchVPBB,
VPBasicBlock *MiddleVPBB, Loop *TheLoop, PredicatedScalarEvolution &PSE,
DominatorTree &DT, AssumptionCache *AC, UncountableExitStyle Style) {
VPDominatorTree VPDT(Plan);
VPBuilder LatchBuilder(LatchVPBB->getTerminator());
SmallVector<EarlyExitInfo> Exits;
for (VPIRBasicBlock *ExitBlock : Plan.getExitBlocks()) {
for (VPBlockBase *Pred : to_vector(ExitBlock->getPredecessors())) {
if (Pred == MiddleVPBB)
continue;
// Collect condition for this early exit.
auto *EarlyExitingVPBB = cast<VPBasicBlock>(Pred);
VPBlockBase *TrueSucc = EarlyExitingVPBB->getSuccessors()[0];
VPValue *CondOfEarlyExitingVPBB;
[[maybe_unused]] bool Matched =
match(EarlyExitingVPBB->getTerminator(),
m_BranchOnCond(m_VPValue(CondOfEarlyExitingVPBB)));
assert(Matched && "Terminator must be BranchOnCond");
// Insert the MaskedCond in the EarlyExitingVPBB so the predicator adds
// the correct block mask.
VPBuilder EarlyExitingBuilder(EarlyExitingVPBB->getTerminator());
auto *CondToEarlyExit = EarlyExitingBuilder.createNaryOp(
VPInstruction::MaskedCond,
TrueSucc == ExitBlock
? CondOfEarlyExitingVPBB
: EarlyExitingBuilder.createNot(CondOfEarlyExitingVPBB));
assert((isa<VPIRValue>(CondOfEarlyExitingVPBB) ||
!VPDT.properlyDominates(EarlyExitingVPBB, LatchVPBB) ||
VPDT.properlyDominates(
CondOfEarlyExitingVPBB->getDefiningRecipe()->getParent(),
LatchVPBB)) &&
"exit condition must dominate the latch");
Exits.push_back({
EarlyExitingVPBB,
ExitBlock,
CondToEarlyExit,
});
}
}
assert(!Exits.empty() && "must have at least one early exit");
// Sort exits by RPO order to get correct program order. RPO gives a
// topological ordering of the CFG, ensuring upstream exits are checked
// before downstream exits in the dispatch chain.
ReversePostOrderTraversal<VPBlockShallowTraversalWrapper<VPBlockBase *>> RPOT(
HeaderVPBB);
DenseMap<VPBlockBase *, unsigned> RPOIdx;
for (const auto &[Num, VPB] : enumerate(RPOT))
RPOIdx[VPB] = Num;
llvm::sort(Exits, [&RPOIdx](const EarlyExitInfo &A, const EarlyExitInfo &B) {
return RPOIdx[A.EarlyExitingVPBB] < RPOIdx[B.EarlyExitingVPBB];
});
#ifndef NDEBUG
// After RPO sorting, verify that for any pair where one exit dominates
// another, the dominating exit comes first. This is guaranteed by RPO
// (topological order) and is required for the dispatch chain correctness.
for (unsigned I = 0; I + 1 < Exits.size(); ++I)
for (unsigned J = I + 1; J < Exits.size(); ++J)
assert(!VPDT.properlyDominates(Exits[J].EarlyExitingVPBB,
Exits[I].EarlyExitingVPBB) &&
"RPO sort must place dominating exits before dominated ones");
#endif
// Build the AnyOf condition for the latch terminator using logical OR
// to avoid poison propagation from later exit conditions when an earlier
// exit is taken.
VPValue *Combined = Exits[0].CondToExit;
for (const EarlyExitInfo &Info : drop_begin(Exits))
Combined = LatchBuilder.createLogicalOr(Combined, Info.CondToExit);
VPValue *IsAnyExitTaken =
LatchBuilder.createNaryOp(VPInstruction::AnyOf, {Combined});
// Create a comparison for the latch exit condition and replace the
// BranchOnCond with a BranchOnTwoConds. The original BranchOnCond's condition
// is used as the latch-exit condition; canonical IV recipes have not been
// introduced yet, so there is no BranchOnCount to derive the condition from.
auto *LatchExitingBranch = cast<VPInstruction>(LatchVPBB->getTerminator());
assert(LatchExitingBranch->getOpcode() == VPInstruction::BranchOnCond &&
"Unexpected terminator");
VPValue *IsLatchExitTaken = LatchExitingBranch->getOperand(0);
DebugLoc LatchDL = LatchExitingBranch->getDebugLoc();
LatchExitingBranch->eraseFromParent();
LatchBuilder.setInsertPoint(LatchVPBB);
LatchBuilder.createNaryOp(VPInstruction::BranchOnTwoConds,
{IsAnyExitTaken, IsLatchExitTaken}, LatchDL);
LatchVPBB->clearSuccessors();
if (Style == UncountableExitStyle::MaskedHandleExitInScalarLoop) {
// If handling the exiting lane in the scalar loop, combine the exit
// conditions into a single BranchOnCond.
LatchVPBB->setSuccessors({MiddleVPBB, MiddleVPBB, HeaderVPBB});
MiddleVPBB->clearPredecessors();
MiddleVPBB->setPredecessors({LatchVPBB, LatchVPBB});
return handleUncountableExitsWithSideEffects(Plan, Exits, HeaderVPBB,
LatchVPBB, MiddleVPBB, TheLoop,
PSE, DT, AC, VPDT);
}
// Create the vector.early.exit blocks.
SmallVector<VPBasicBlock *> VectorEarlyExitVPBBs(Exits.size());
for (unsigned Idx = 0; Idx != Exits.size(); ++Idx) {
Twine BlockSuffix = Exits.size() == 1 ? "" : Twine(".") + Twine(Idx);
VPBasicBlock *VectorEarlyExitVPBB =
Plan.createVPBasicBlock("vector.early.exit" + BlockSuffix);
VectorEarlyExitVPBBs[Idx] = VectorEarlyExitVPBB;
}
// Create the dispatch block (or reuse the single exit block if only one
// exit). The dispatch block computes the first active lane of the combined
// condition and, for multiple exits, chains through conditions to determine
// which exit to take.
VPBasicBlock *DispatchVPBB =
Exits.size() == 1 ? VectorEarlyExitVPBBs[0]
: Plan.createVPBasicBlock("vector.early.exit.check");
DispatchVPBB->setPredecessors({LatchVPBB});
LatchVPBB->setSuccessors({DispatchVPBB, MiddleVPBB, HeaderVPBB});
VPBuilder DispatchBuilder(DispatchVPBB, DispatchVPBB->begin());
VPValue *FirstActiveLane = DispatchBuilder.createFirstActiveLane(
{Combined}, DebugLoc::getUnknown(), "first.active.lane");
// For each early exit, disconnect the original exiting block
// (early.exiting.I) from the exit block (ir-bb<exit.I>) and route through a
// new vector.early.exit block. Update ir-bb<exit.I>'s phis to extract their
// values at the first active lane:
//
// Input:
// early.exiting.I:
// ...
// EMIT branch-on-cond vp<%cond.I>
// Successor(s): in.loop.succ, ir-bb<exit.I>
//
// ir-bb<exit.I>:
// IR %phi = phi [ vp<%incoming.I>, early.exiting.I ], ...
//
// Output:
// early.exiting.I:
// ...
// Successor(s): in.loop.succ
//
// vector.early.exit.I:
// EMIT vp<%exit.val> = extract-lane vp<%first.lane>, vp<%incoming.I>
// Successor(s): ir-bb<exit.I>
//
// ir-bb<exit.I>:
// IR %phi = phi ... (extra operand: vp<%exit.val> from
// vector.early.exit.I)
//
for (auto [Exit, VectorEarlyExitVPBB] :
zip_equal(Exits, VectorEarlyExitVPBBs)) {
auto &[EarlyExitingVPBB, EarlyExitVPBB, _] = Exit;
// Adjust the phi nodes in EarlyExitVPBB.
// 1. remove incoming values from EarlyExitingVPBB,
// 2. extract the incoming value at FirstActiveLane
// 3. add back the extracts as last operands for the phis
// Then adjust the CFG, removing the edge between EarlyExitingVPBB and
// EarlyExitVPBB and adding a new edge between VectorEarlyExitVPBB and
// EarlyExitVPBB. The extracts at FirstActiveLane are now the incoming
// values from VectorEarlyExitVPBB.
for (VPRecipeBase &R : EarlyExitVPBB->phis()) {
auto *ExitIRI = cast<VPIRPhi>(&R);
VPValue *IncomingVal =
ExitIRI->getIncomingValueForBlock(EarlyExitingVPBB);
VPValue *NewIncoming = IncomingVal;
if (!isa<VPIRValue>(IncomingVal)) {
VPBuilder EarlyExitBuilder(VectorEarlyExitVPBB);
NewIncoming = EarlyExitBuilder.createNaryOp(
VPInstruction::ExtractLane, {FirstActiveLane, IncomingVal},
DebugLoc::getUnknown(), "early.exit.value");
}
ExitIRI->removeIncomingValueFor(EarlyExitingVPBB);
ExitIRI->addIncoming(NewIncoming);
}
EarlyExitingVPBB->getTerminator()->eraseFromParent();
VPBlockUtils::disconnectBlocks(EarlyExitingVPBB, EarlyExitVPBB);
VPBlockUtils::connectBlocks(VectorEarlyExitVPBB, EarlyExitVPBB);
}
// Chain through exits: for each exit, check if its condition is true at
// the first active lane. If so, take that exit; otherwise, try the next.
// The last exit needs no check since it must be taken if all others fail.
//
// For 3 exits (cond.0, cond.1, cond.2), this creates:
//
// latch:
// ...
// EMIT vp<%combined> = logical-or vp<%cond.0>, vp<%cond.1>, vp<%cond.2>
// ...
//
// vector.early.exit.check:
// EMIT vp<%first.lane> = first-active-lane vp<%combined>
// EMIT vp<%at.cond.0> = extract-lane vp<%first.lane>, vp<%cond.0>
// EMIT branch-on-cond vp<%at.cond.0>
// Successor(s): vector.early.exit.0, vector.early.exit.check.0
//
// vector.early.exit.check.0:
// EMIT vp<%at.cond.1> = extract-lane vp<%first.lane>, vp<%cond.1>
// EMIT branch-on-cond vp<%at.cond.1>
// Successor(s): vector.early.exit.1, vector.early.exit.2
VPBasicBlock *CurrentBB = DispatchVPBB;
for (auto [I, Exit] : enumerate(ArrayRef(Exits).drop_back())) {
VPValue *LaneVal = DispatchBuilder.createNaryOp(
VPInstruction::ExtractLane, {FirstActiveLane, Exit.CondToExit},
DebugLoc::getUnknown(), "exit.cond.at.lane");
// For the last dispatch, branch directly to the last exit on false;
// otherwise, create a new check block.
bool IsLastDispatch = (I + 2 == Exits.size());
VPBasicBlock *FalseBB =
IsLastDispatch ? VectorEarlyExitVPBBs.back()
: Plan.createVPBasicBlock(
Twine("vector.early.exit.check.") + Twine(I));
DispatchBuilder.createNaryOp(VPInstruction::BranchOnCond, {LaneVal});
CurrentBB->setSuccessors({VectorEarlyExitVPBBs[I], FalseBB});
VectorEarlyExitVPBBs[I]->setPredecessors({CurrentBB});
FalseBB->setPredecessors({CurrentBB});
CurrentBB = FalseBB;
DispatchBuilder.setInsertPoint(CurrentBB);
}
return true;
}
/// This function tries convert extended in-loop reductions to
/// VPExpressionRecipe and clamp the \p Range if it is beneficial and
/// valid. The created recipe must be decomposed to its constituent
/// recipes before execution.
static VPExpressionRecipe *
tryToMatchAndCreateExtendedReduction(VPReductionRecipe *Red, VPCostContext &Ctx,
VFRange &Range) {
Type *RedTy = Red->getScalarType();
VPValue *VecOp = Red->getVecOp();
assert(!Red->isPartialReduction() &&
"This path does not support partial reductions");
// Clamp the range if using extended-reduction is profitable.
auto IsExtendedRedValidAndClampRange =
[&](unsigned Opcode, Instruction::CastOps ExtOpc, Type *SrcTy) -> bool {
return LoopVectorizationPlanner::getDecisionAndClampRange(
[&](ElementCount VF) {
auto *SrcVecTy = cast<VectorType>(toVectorTy(SrcTy, VF));
TTI::TargetCostKind CostKind = TTI::TCK_RecipThroughput;
InstructionCost ExtRedCost = InstructionCost::getInvalid();
InstructionCost ExtCost =
cast<VPWidenCastRecipe>(VecOp)->computeCost(VF, Ctx);
InstructionCost RedCost = Red->computeCost(VF, Ctx);
assert(!RedTy->isFloatingPointTy() &&
"getExtendedReductionCost only supports integer types");
ExtRedCost = Ctx.TTI.getExtendedReductionCost(
Opcode, ExtOpc == Instruction::CastOps::ZExt, RedTy, SrcVecTy,
Red->getFastMathFlagsOrNone(), CostKind);
return ExtRedCost.isValid() && ExtRedCost < ExtCost + RedCost;
},
Range);
};
VPValue *A;
// Match reduce(ext)).
if (match(VecOp, m_Isa<VPWidenCastRecipe>(m_ZExtOrSExt(m_VPValue(A)))) &&
IsExtendedRedValidAndClampRange(
RecurrenceDescriptor::getOpcode(Red->getRecurrenceKind()),
cast<VPWidenCastRecipe>(VecOp)->getOpcode(), A->getScalarType()))
return new VPExpressionRecipe(cast<VPWidenCastRecipe>(VecOp), Red);
return nullptr;
}
/// This function tries convert extended in-loop reductions to
/// VPExpressionRecipe and clamp the \p Range if it is beneficial
/// and valid. The created VPExpressionRecipe must be decomposed to its
/// constituent recipes before execution. Patterns of the
/// VPExpressionRecipe:
/// reduce.add(mul(...)),
/// reduce.add(mul(ext(A), ext(B))),
/// reduce.add(ext(mul(ext(A), ext(B)))).
/// reduce.fadd(fmul(ext(A), ext(B)))
static VPExpressionRecipe *
tryToMatchAndCreateMulAccumulateReduction(VPReductionRecipe *Red,
VPCostContext &Ctx, VFRange &Range) {
unsigned Opcode = RecurrenceDescriptor::getOpcode(Red->getRecurrenceKind());
if (Opcode != Instruction::Add && Opcode != Instruction::Sub &&
Opcode != Instruction::FAdd)
return nullptr;
assert(!Red->isPartialReduction() &&
"This path does not support partial reductions");
Type *RedTy = Red->getScalarType();
// Clamp the range if using multiply-accumulate-reduction is profitable.
auto IsMulAccValidAndClampRange =
[&](VPWidenRecipe *Mul, VPWidenCastRecipe *Ext0, VPWidenCastRecipe *Ext1,
VPWidenCastRecipe *OuterExt) -> bool {
return LoopVectorizationPlanner::getDecisionAndClampRange(
[&](ElementCount VF) {
TTI::TargetCostKind CostKind = TTI::TCK_RecipThroughput;
Type *SrcTy = Ext0 ? Ext0->getOperand(0)->getScalarType() : RedTy;
InstructionCost MulAccCost;
// getMulAccReductionCost for in-loop reductions does not support
// mixed or floating-point extends.
if (Ext0 && Ext1 &&
(Ext0->getOpcode() != Ext1->getOpcode() ||
Ext0->getOpcode() == Instruction::CastOps::FPExt))
return false;
bool IsZExt =
!Ext0 || Ext0->getOpcode() == Instruction::CastOps::ZExt;
auto *SrcVecTy = cast<VectorType>(toVectorTy(SrcTy, VF));
MulAccCost = Ctx.TTI.getMulAccReductionCost(IsZExt, Opcode, RedTy,
SrcVecTy, CostKind);
InstructionCost MulCost = Mul->computeCost(VF, Ctx);
InstructionCost RedCost = Red->computeCost(VF, Ctx);
InstructionCost ExtCost = 0;
if (Ext0)
ExtCost += Ext0->computeCost(VF, Ctx);
if (Ext1)
ExtCost += Ext1->computeCost(VF, Ctx);
if (OuterExt)
ExtCost += OuterExt->computeCost(VF, Ctx);
return MulAccCost.isValid() &&
MulAccCost < ExtCost + MulCost + RedCost;
},
Range);
};
VPValue *VecOp = Red->getVecOp();
VPRecipeBase *Sub = nullptr;
VPValue *A, *B;
VPValue *Tmp = nullptr;
if (RedTy->isFloatingPointTy())
return nullptr;
// Sub reductions could have a sub between the add reduction and vec op.
if (match(VecOp, m_Sub(m_ZeroInt(), m_VPValue(Tmp)))) {
Sub = VecOp->getDefiningRecipe();
VecOp = Tmp;
}
// If ValB is a constant and can be safely extended, truncate it to the same
// type as ExtA's operand, then extend it to the same type as ExtA. This
// creates two uniform extends that can more easily be matched by the rest of
// the bundling code. The ExtB reference, ValB and operand 1 of Mul are all
// replaced with the new extend of the constant.
auto ExtendAndReplaceConstantOp = [](VPWidenCastRecipe *ExtA,
VPWidenCastRecipe *&ExtB, VPValue *&ValB,
VPWidenRecipe *Mul) {
if (!ExtA || ExtB || !isa<VPIRValue>(ValB))
return;
Type *NarrowTy = ExtA->getOperand(0)->getScalarType();
Instruction::CastOps ExtOpc = ExtA->getOpcode();
const APInt *Const;
if (!match(ValB, m_APInt(Const)) ||
!llvm::canConstantBeExtended(
Const, NarrowTy, TTI::getPartialReductionExtendKind(ExtOpc)))
return;
// The truncate ensures that the type of each extended operand is the
// same, and it's been proven that the constant can be extended from
// NarrowTy safely. Necessary since ExtA's extended operand would be
// e.g. an i8, while the const will likely be an i32. This will be
// elided by later optimisations.
VPBuilder Builder(Mul);
auto *Trunc =
Builder.createWidenCast(Instruction::CastOps::Trunc, ValB, NarrowTy);
Type *WideTy = ExtA->getScalarType();
ValB = ExtB = Builder.createWidenCast(ExtOpc, Trunc, WideTy);
Mul->setOperand(1, ExtB);
};
// Try to match reduce.add(mul(...)).
if (match(VecOp, m_Mul(m_VPValue(A), m_VPValue(B)))) {
auto *RecipeA = dyn_cast<VPWidenCastRecipe>(A);
auto *RecipeB = dyn_cast<VPWidenCastRecipe>(B);
auto *Mul = cast<VPWidenRecipe>(VecOp);
// Convert reduce.add(mul(ext, const)) to reduce.add(mul(ext, ext(const)))
ExtendAndReplaceConstantOp(RecipeA, RecipeB, B, Mul);
// Match reduce.add/sub(mul(ext, ext)).
if (RecipeA && RecipeB && match(RecipeA, m_ZExtOrSExt(m_VPValue())) &&
match(RecipeB, m_ZExtOrSExt(m_VPValue())) &&
IsMulAccValidAndClampRange(Mul, RecipeA, RecipeB, nullptr)) {
if (Sub)
return new VPExpressionRecipe(RecipeA, RecipeB, Mul,
cast<VPWidenRecipe>(Sub), Red);
return new VPExpressionRecipe(RecipeA, RecipeB, Mul, Red);
}
// TODO: Add an expression type for this variant with a negated mul
if (!Sub && IsMulAccValidAndClampRange(Mul, nullptr, nullptr, nullptr))
return new VPExpressionRecipe(Mul, Red);
}
// TODO: Add an expression type for negated versions of other expression
// variants.
if (Sub)
return nullptr;
// Match reduce.add(ext(mul(A, B))).
if (match(VecOp, m_ZExtOrSExt(m_Mul(m_VPValue(A), m_VPValue(B))))) {
auto *Ext = cast<VPWidenCastRecipe>(VecOp);
auto *Mul = cast<VPWidenRecipe>(Ext->getOperand(0));
auto *Ext0 = dyn_cast<VPWidenCastRecipe>(A);
auto *Ext1 = dyn_cast<VPWidenCastRecipe>(B);
// reduce.add(ext(mul(ext, const)))
// -> reduce.add(ext(mul(ext, ext(const))))
ExtendAndReplaceConstantOp(Ext0, Ext1, B, Mul);
// reduce.add(ext(mul(ext(A), ext(B))))
// -> reduce.add(mul(wider_ext(A), wider_ext(B)))
// The inner extends must either have the same opcode as the outer extend or
// be the same, in which case the multiply can never result in a negative
// value and the outer extend can be folded away by doing wider
// extends for the operands of the mul.
if (Ext0 && Ext1 &&
(Ext->getOpcode() == Ext0->getOpcode() || Ext0 == Ext1) &&
Ext0->getOpcode() == Ext1->getOpcode() &&
IsMulAccValidAndClampRange(Mul, Ext0, Ext1, Ext) && Mul->hasOneUse()) {
auto *NewExt0 = new VPWidenCastRecipe(
Ext0->getOpcode(), Ext0->getOperand(0), Ext->getScalarType(), nullptr,
*Ext0, *Ext0, Ext0->getDebugLoc());
NewExt0->insertBefore(Ext0);
VPWidenCastRecipe *NewExt1 = NewExt0;
if (Ext0 != Ext1) {
NewExt1 = new VPWidenCastRecipe(Ext1->getOpcode(), Ext1->getOperand(0),
Ext->getScalarType(), nullptr, *Ext1,
*Ext1, Ext1->getDebugLoc());
NewExt1->insertBefore(Ext1);
}
auto *NewMul = Mul->cloneWithOperands({NewExt0, NewExt1});
NewMul->insertBefore(Mul);
Ext->replaceAllUsesWith(NewMul);
Ext->eraseFromParent();
Mul->eraseFromParent();
return new VPExpressionRecipe(NewExt0, NewExt1, NewMul, Red);
}
}
return nullptr;
}
/// This function tries to create abstract recipes from the reduction recipe for
/// following optimizations and cost estimation.
static void tryToCreateAbstractReductionRecipe(VPReductionRecipe *Red,
VPCostContext &Ctx,
VFRange &Range) {
// Creation of VPExpressions for partial reductions is entirely handled in
// transformToPartialReduction.
assert(!Red->isPartialReduction() &&
"This path does not support partial reductions");
VPExpressionRecipe *AbstractR = nullptr;
auto IP = std::next(Red->getIterator());
auto *VPBB = Red->getParent();
if (auto *MulAcc = tryToMatchAndCreateMulAccumulateReduction(Red, Ctx, Range))
AbstractR = MulAcc;
else if (auto *ExtRed = tryToMatchAndCreateExtendedReduction(Red, Ctx, Range))
AbstractR = ExtRed;
// Cannot create abstract inloop reduction recipes.
if (!AbstractR)
return;
AbstractR->insertBefore(*VPBB, IP);
Red->replaceAllUsesWith(AbstractR);
}
void VPlanTransforms::convertToAbstractRecipes(VPlan &Plan, VPCostContext &Ctx,
VFRange &Range) {
for (VPBasicBlock *VPBB : VPBlockUtils::blocksOnly<VPBasicBlock>(
vp_depth_first_deep(Plan.getVectorLoopRegion()))) {
for (VPRecipeBase &R : make_early_inc_range(*VPBB)) {
if (auto *Red = dyn_cast<VPReductionRecipe>(&R))
tryToCreateAbstractReductionRecipe(Red, Ctx, Range);
}
}
}
void VPlanTransforms::materializeBroadcasts(VPlan &Plan) {
if (Plan.hasScalarVFOnly())
return;
#ifndef NDEBUG
VPDominatorTree VPDT(Plan);
#endif
SmallVector<VPValue *> VPValues;
if (VPValue *BTC = Plan.getBackedgeTakenCount())
VPValues.push_back(BTC);
append_range(VPValues, Plan.getLiveIns());
for (VPRecipeBase &R : *Plan.getEntry())
append_range(VPValues, R.definedValues());
auto *VectorPreheader = Plan.getVectorPreheader();
for (VPValue *VPV : VPValues) {
if (vputils::onlyScalarValuesUsed(VPV) ||
(isa<VPIRValue>(VPV) && isa<Constant>(VPV->getLiveInIRValue())))
continue;
// Add explicit broadcast at the insert point that dominates all users.
VPBasicBlock *HoistBlock = VectorPreheader;
VPBasicBlock::iterator HoistPoint = VectorPreheader->end();
for (VPUser *User : VPV->users()) {
if (User->usesScalars(VPV))
continue;
if (cast<VPRecipeBase>(User)->getParent() == VectorPreheader)
HoistPoint = HoistBlock->begin();
else
assert(VPDT.dominates(VectorPreheader,
cast<VPRecipeBase>(User)->getParent()) &&
"All users must be in the vector preheader or dominated by it");
}
VPBuilder Builder(cast<VPBasicBlock>(HoistBlock), HoistPoint);
auto *Broadcast = Builder.createNaryOp(VPInstruction::Broadcast, {VPV});
VPV->replaceUsesWithIf(Broadcast,
[VPV, Broadcast](VPUser &U, unsigned Idx) {
return Broadcast != &U && !U.usesScalars(VPV);
});
}
}
// Collect common metadata from a group of replicate recipes by intersecting
// metadata from all recipes in the group.
static VPIRMetadata getCommonMetadata(ArrayRef<VPReplicateRecipe *> Recipes) {
VPIRMetadata CommonMetadata = *Recipes.front();
for (VPReplicateRecipe *Recipe : drop_begin(Recipes))
CommonMetadata.intersect(*Recipe);
return CommonMetadata;
}
template <unsigned Opcode>
static SmallVector<SmallVector<VPReplicateRecipe *, 4>>
collectComplementaryPredicatedMemOps(VPlan &Plan,
PredicatedScalarEvolution &PSE,
const Loop *L) {
static_assert(Opcode == Instruction::Load || Opcode == Instruction::Store,
"Only Load and Store opcodes supported");
[[maybe_unused]] constexpr bool IsLoad = (Opcode == Instruction::Load);
// For each address, collect operations with the same or complementary masks.
SmallVector<SmallVector<VPReplicateRecipe *, 4>> AllGroups;
auto Groups = collectGroupedReplicateMemOps<Opcode>(
Plan, PSE, L,
[](VPReplicateRecipe *RepR) { return RepR->isPredicated(); });
for (auto Recipes : Groups) {
if (Recipes.size() < 2)
continue;
assert(all_equal(
map_range(Recipes, bind_back<getLoadStoreValueType>(IsLoad))) &&
"Expected all recipes in group to have the same load-store type");
// Collect groups with the same or complementary masks.
for (VPReplicateRecipe *&RecipeI : Recipes) {
if (!RecipeI)
continue;
VPValue *MaskI = RecipeI->getMask();
SmallVector<VPReplicateRecipe *, 4> Group;
Group.push_back(RecipeI);
RecipeI = nullptr;
// Find all operations with the same or complementary masks.
bool HasComplementaryMask = false;
for (VPReplicateRecipe *&RecipeJ : Recipes) {
if (!RecipeJ)
continue;
VPValue *MaskJ = RecipeJ->getMask();
// Check if any operation in the group has a complementary mask with
// another, that is M1 == NOT(M2) or M2 == NOT(M1).
HasComplementaryMask |= match(MaskI, m_Not(m_Specific(MaskJ))) ||
match(MaskJ, m_Not(m_Specific(MaskI)));
Group.push_back(RecipeJ);
RecipeJ = nullptr;
}
if (HasComplementaryMask) {
assert(Group.size() >= 2 && "must have at least 2 entries");
AllGroups.push_back(std::move(Group));
}
}
}
return AllGroups;
}
// Find the recipe with minimum alignment in the group.
template <typename InstType>
static VPReplicateRecipe *
findRecipeWithMinAlign(ArrayRef<VPReplicateRecipe *> Group) {
return *min_element(Group, [](VPReplicateRecipe *A, VPReplicateRecipe *B) {
return cast<InstType>(A->getUnderlyingInstr())->getAlign() <
cast<InstType>(B->getUnderlyingInstr())->getAlign();
});
}
void VPlanTransforms::hoistPredicatedLoads(VPlan &Plan,
PredicatedScalarEvolution &PSE,
const Loop *L) {
auto Groups =
collectComplementaryPredicatedMemOps<Instruction::Load>(Plan, PSE, L);
if (Groups.empty())
return;
// Process each group of loads.
for (auto &Group : Groups) {
// Try to use the earliest (most dominating) load to replace all others.
VPReplicateRecipe *EarliestLoad = Group[0];
VPBasicBlock *FirstBB = EarliestLoad->getParent();
VPBasicBlock *LastBB = Group.back()->getParent();
// Check that the load doesn't alias with stores between first and last.
auto LoadLoc = vputils::getMemoryLocation(*EarliestLoad);
if (!LoadLoc || !canHoistOrSinkWithNoAliasCheck(*LoadLoc, FirstBB, LastBB))
continue;
// Collect common metadata from all loads in the group.
VPIRMetadata CommonMetadata = getCommonMetadata(Group);
// Find the load with minimum alignment to use.
auto *LoadWithMinAlign = findRecipeWithMinAlign<LoadInst>(Group);
bool IsSingleScalar = EarliestLoad->isSingleScalar();
assert(all_of(Group,
[IsSingleScalar](VPReplicateRecipe *R) {
return R->isSingleScalar() == IsSingleScalar;
}) &&
"all members in group must agree on IsSingleScalar");
// Create an unpredicated version of the earliest load with common
// metadata.
auto *UnpredicatedLoad = new VPReplicateRecipe(
LoadWithMinAlign->getUnderlyingInstr(), {EarliestLoad->getOperand(0)},
IsSingleScalar, /*Mask=*/nullptr, *EarliestLoad, CommonMetadata);
UnpredicatedLoad->insertBefore(EarliestLoad);
// Replace all loads in the group with the unpredicated load.
for (VPReplicateRecipe *Load : Group) {
Load->replaceAllUsesWith(UnpredicatedLoad);
Load->eraseFromParent();
}
}
}
static bool
canSinkStoreWithNoAliasCheck(ArrayRef<VPReplicateRecipe *> StoresToSink,
PredicatedScalarEvolution &PSE, const Loop &L) {
auto StoreLoc = vputils::getMemoryLocation(*StoresToSink.front());
if (!StoreLoc || !StoreLoc->AATags.Scope)
return false;
// When sinking a group of stores, all members of the group alias each other.
// Skip them during the alias checks.
SmallPtrSet<VPRecipeBase *, 4> StoresToSinkSet(StoresToSink.begin(),
StoresToSink.end());
VPBasicBlock *FirstBB = StoresToSink.front()->getParent();
VPBasicBlock *LastBB = StoresToSink.back()->getParent();
SinkStoreInfo SinkInfo(StoresToSinkSet, *StoresToSink[0], PSE, L);
return canHoistOrSinkWithNoAliasCheck(*StoreLoc, FirstBB, LastBB, SinkInfo);
}
void VPlanTransforms::sinkPredicatedStores(VPlan &Plan,
PredicatedScalarEvolution &PSE,
const Loop *L) {
auto Groups =
collectComplementaryPredicatedMemOps<Instruction::Store>(Plan, PSE, L);
if (Groups.empty())
return;
for (auto &Group : Groups) {
if (!canSinkStoreWithNoAliasCheck(Group, PSE, *L))
continue;
// Use the last (most dominated) store's location for the unconditional
// store.
VPReplicateRecipe *LastStore = Group.back();
VPBasicBlock *InsertBB = LastStore->getParent();
// Collect common alias metadata from all stores in the group.
VPIRMetadata CommonMetadata = getCommonMetadata(Group);
// Build select chain for stored values.
VPValue *SelectedValue = Group[0]->getOperand(0);
VPBuilder Builder(InsertBB, LastStore->getIterator());
bool IsSingleScalar = Group[0]->isSingleScalar();
for (unsigned I = 1; I < Group.size(); ++I) {
assert(IsSingleScalar == Group[I]->isSingleScalar() &&
"all members in group must agree on IsSingleScalar");
VPValue *Mask = Group[I]->getMask();
VPValue *Value = Group[I]->getOperand(0);
SelectedValue = Builder.createSelect(Mask, Value, SelectedValue,
Group[I]->getDebugLoc());
}
// Find the store with minimum alignment to use.
auto *StoreWithMinAlign = findRecipeWithMinAlign<StoreInst>(Group);
// Create unconditional store with selected value and common metadata.
auto *UnpredicatedStore = new VPReplicateRecipe(
StoreWithMinAlign->getUnderlyingInstr(),
{SelectedValue, LastStore->getOperand(1)}, IsSingleScalar,
/*Mask=*/nullptr, *LastStore, CommonMetadata);
UnpredicatedStore->insertBefore(*InsertBB, LastStore->getIterator());
// Remove all predicated stores from the group.
for (VPReplicateRecipe *Store : Group)
Store->eraseFromParent();
}
}
void VPlanTransforms::materializeConstantVectorTripCount(
VPlan &Plan, ElementCount BestVF, unsigned BestUF,
PredicatedScalarEvolution &PSE) {
assert(Plan.hasVF(BestVF) && "BestVF is not available in Plan");
assert(Plan.hasUF(BestUF) && "BestUF is not available in Plan");
VPValue *TC = Plan.getTripCount();
if (TC->getNumUsers() == 0)
return;
// Skip cases for which the trip count may be non-trivial to materialize.
// I.e., when a scalar tail is absent - due to tail folding, or when a scalar
// tail is required.
if (!Plan.hasScalarTail() ||
Plan.getMiddleBlock()->getSingleSuccessor() ==
Plan.getScalarPreheader() ||
!isa<VPIRValue>(TC))
return;
// Materialize vector trip counts for constants early if it can simply
// be computed as (Original TC / VF * UF) * VF * UF.
// TODO: Compute vector trip counts for loops requiring a scalar epilogue and
// tail-folded loops.
ScalarEvolution &SE = *PSE.getSE();
auto *TCScev = SE.getSCEV(TC->getLiveInIRValue());
if (!isa<SCEVConstant>(TCScev))
return;
const SCEV *VFxUF = SE.getElementCount(TCScev->getType(), BestVF * BestUF);
auto VecTCScev = SE.getMulExpr(SE.getUDivExpr(TCScev, VFxUF), VFxUF);
if (auto *ConstVecTC = dyn_cast<SCEVConstant>(VecTCScev))
Plan.getVectorTripCount().setUnderlyingValue(ConstVecTC->getValue());
}
void VPlanTransforms::materializeBackedgeTakenCount(VPlan &Plan,
VPBasicBlock *VectorPH) {
VPValue *BTC = Plan.getOrCreateBackedgeTakenCount();
if (BTC->getNumUsers() == 0)
return;
VPBuilder Builder(VectorPH, VectorPH->begin());
auto *TCTy = Plan.getTripCount()->getScalarType();
auto *TCMO =
Builder.createSub(Plan.getTripCount(), Plan.getConstantInt(TCTy, 1),
DebugLoc::getCompilerGenerated(), "trip.count.minus.1");
BTC->replaceAllUsesWith(TCMO);
}
void VPlanTransforms::materializePacksAndUnpacks(VPlan &Plan) {
if (Plan.hasScalarVFOnly())
return;
VPRegionBlock *LoopRegion = Plan.getVectorLoopRegion();
auto VPBBsOutsideLoopRegion = VPBlockUtils::blocksOnly<VPBasicBlock>(
vp_depth_first_shallow(Plan.getEntry()));
auto VPBBsInsideLoopRegion = VPBlockUtils::blocksOnly<VPBasicBlock>(
vp_depth_first_shallow(LoopRegion->getEntry()));
// Materialize Build(Struct)Vector for all replicating VPReplicateRecipes,
// VPScalarIVStepsRecipe and VPInstructions, excluding ones in replicate
// regions. Those are not materialized explicitly yet.
// TODO: materialize build vectors for replicating recipes in replicating
// regions.
for (VPBasicBlock *VPBB :
concat<VPBasicBlock *>(VPBBsOutsideLoopRegion, VPBBsInsideLoopRegion)) {
for (VPRecipeBase &R : make_early_inc_range(*VPBB)) {
if (!isa<VPScalarIVStepsRecipe, VPReplicateRecipe, VPInstruction>(&R))
continue;
auto *DefR = cast<VPSingleDefRecipe>(&R);
auto UsesVectorOrInsideReplicateRegion = [DefR, LoopRegion](VPUser *U) {
VPRegionBlock *ParentRegion = cast<VPRecipeBase>(U)->getRegion();
return !U->usesScalars(DefR) || ParentRegion != LoopRegion;
};
if ((isa<VPReplicateRecipe>(DefR) &&
cast<VPReplicateRecipe>(DefR)->isSingleScalar()) ||
(isa<VPInstruction>(DefR) &&
(vputils::onlyFirstLaneUsed(DefR) ||
!cast<VPInstruction>(DefR)->doesGeneratePerAllLanes())) ||
none_of(DefR->users(), UsesVectorOrInsideReplicateRegion))
continue;
Type *ScalarTy = DefR->getScalarType();
unsigned Opcode = ScalarTy->isStructTy()
? VPInstruction::BuildStructVector
: VPInstruction::BuildVector;
auto *BuildVector = new VPInstruction(Opcode, {DefR});
BuildVector->insertAfter(DefR);
DefR->replaceUsesWithIf(
BuildVector, [BuildVector, &UsesVectorOrInsideReplicateRegion](
VPUser &U, unsigned) {
return &U != BuildVector && UsesVectorOrInsideReplicateRegion(&U);
});
}
}
// Create explicit VPInstructions to convert vectors to scalars. The current
// implementation is conservative - it may miss some cases that may or may not
// be vector values. TODO: introduce Unpacks speculatively - remove them later
// if they are known to operate on scalar values.
for (VPBasicBlock *VPBB : VPBBsInsideLoopRegion) {
for (VPRecipeBase &R : make_early_inc_range(*VPBB)) {
if (isa<VPReplicateRecipe, VPInstruction, VPScalarIVStepsRecipe,
VPDerivedIVRecipe>(&R))
continue;
for (VPValue *Def : R.definedValues()) {
// Skip recipes that are single-scalar or only have their first lane
// used.
// TODO: The Defs skipped here may or may not be vector values.
// Introduce Unpacks, and remove them later, if they are guaranteed to
// produce scalar values.
if (vputils::isSingleScalar(Def) || vputils::onlyFirstLaneUsed(Def))
continue;
// At the moment, we create unpacks only for scalar users outside
// replicate regions. Recipes inside replicate regions still extract the
// required lanes implicitly.
// TODO: Remove once replicate regions are unrolled completely.
auto IsCandidateUnpackUser = [Def](VPUser *U) {
VPRegionBlock *ParentRegion = cast<VPRecipeBase>(U)->getRegion();
return U->usesScalars(Def) &&
(!ParentRegion || !ParentRegion->isReplicator());
};
if (none_of(Def->users(), IsCandidateUnpackUser))
continue;
auto *Unpack = new VPInstruction(VPInstruction::Unpack, {Def});
if (R.isPhi())
Unpack->insertBefore(*VPBB, VPBB->getFirstNonPhi());
else
Unpack->insertAfter(&R);
Def->replaceUsesWithIf(Unpack,
[&IsCandidateUnpackUser](VPUser &U, unsigned) {
return IsCandidateUnpackUser(&U);
});
}
}
}
}
void VPlanTransforms::materializeVectorTripCount(
VPlan &Plan, VPBasicBlock *VectorPHVPBB, bool TailByMasking,
bool RequiresScalarEpilogue, VPValue *Step,
std::optional<uint64_t> MaxRuntimeStep) {
VPSymbolicValue &VectorTC = Plan.getVectorTripCount();
// There's nothing to do if there are no users of the vector trip count or its
// IR value has already been set.
if (VectorTC.getNumUsers() == 0 || VectorTC.getUnderlyingValue())
return;
VPValue *TC = Plan.getTripCount();
Type *TCTy = TC->getScalarType();
VPBasicBlock::iterator InsertPt = VectorPHVPBB->begin();
if (auto *StepR = Step->getDefiningRecipe()) {
assert(VPDominatorTree(Plan).dominates(StepR->getParent(), VectorPHVPBB) &&
"Step VPBB must dominate VectorPHVPBB");
// Insert after Step's definition to maintain valid def-use ordering.
InsertPt = std::next(StepR->getIterator());
}
VPBuilder Builder(VectorPHVPBB, InsertPt);
// For scalable steps, if TC is a constant and is divisible by the maximum
// possible runtime step, then TC % Step == 0 for all valid vscale values
// and the vector trip count equals TC directly.
const APInt *TCVal;
if (!RequiresScalarEpilogue && match(TC, m_APInt(TCVal)) && MaxRuntimeStep &&
TCVal->getZExtValue() % *MaxRuntimeStep == 0) {
VectorTC.replaceAllUsesWith(TC);
return;
}
// If the tail is to be folded by masking, round the number of iterations N
// up to a multiple of Step instead of rounding down. This is done by first
// adding Step-1 and then rounding down. Note that it's ok if this addition
// overflows: the vector induction variable will eventually wrap to zero given
// that it starts at zero and its Step is a power of two; the loop will then
// exit, with the last early-exit vector comparison also producing all-true.
if (TailByMasking) {
TC = Builder.createAdd(
TC, Builder.createSub(Step, Plan.getConstantInt(TCTy, 1)),
DebugLoc::getCompilerGenerated(), "n.rnd.up");
}
// Now we need to generate the expression for the part of the loop that the
// vectorized body will execute. This is equal to N - (N % Step) if scalar
// iterations are not required for correctness, or N - Step, otherwise. Step
// is equal to the vectorization factor (number of SIMD elements) times the
// unroll factor (number of SIMD instructions).
VPValue *R =
Builder.createNaryOp(Instruction::URem, {TC, Step},
DebugLoc::getCompilerGenerated(), "n.mod.vf");
// There are cases where we *must* run at least one iteration in the remainder
// loop. See the cost model for when this can happen. If the step evenly
// divides the trip count, we set the remainder to be equal to the step. If
// the step does not evenly divide the trip count, no adjustment is necessary
// since there will already be scalar iterations. Note that the minimum
// iterations check ensures that N >= Step.
if (RequiresScalarEpilogue) {
assert(!TailByMasking &&
"requiring scalar epilogue is not supported with fail folding");
VPValue *IsZero =
Builder.createICmp(CmpInst::ICMP_EQ, R, Plan.getZero(TCTy));
R = Builder.createSelect(IsZero, Step, R);
}
VPValue *Res =
Builder.createSub(TC, R, DebugLoc::getCompilerGenerated(), "n.vec");
VectorTC.replaceAllUsesWith(Res);
}
void VPlanTransforms::materializeFactors(VPlan &Plan, VPBasicBlock *VectorPH,
ElementCount VFEC) {
// If VF and VFxUF have already been materialized (no remaining users),
// there's nothing more to do.
if (Plan.getVF().isMaterialized()) {
assert(Plan.getVFxUF().isMaterialized() &&
"VF and VFxUF must be materialized together");
return;
}
VPBuilder Builder(VectorPH, VectorPH->begin());
Type *TCTy = Plan.getTripCount()->getScalarType();
VPValue &VF = Plan.getVF();
VPValue &VFxUF = Plan.getVFxUF();
// If there are no users of the runtime VF, compute VFxUF by constant folding
// the multiplication of VF and UF.
if (VF.getNumUsers() == 0) {
VPValue *RuntimeVFxUF =
Builder.createElementCount(TCTy, VFEC * Plan.getConcreteUF());
VFxUF.replaceAllUsesWith(RuntimeVFxUF);
return;
}
// For users of the runtime VF, compute it as VF * vscale, and VFxUF as (VF *
// vscale) * UF.
VPValue *RuntimeVF = Builder.createElementCount(TCTy, VFEC);
if (!vputils::onlyScalarValuesUsed(&VF)) {
VPValue *BC = Builder.createNaryOp(VPInstruction::Broadcast, RuntimeVF);
VF.replaceUsesWithIf(
BC, [&VF](VPUser &U, unsigned) { return !U.usesScalars(&VF); });
}
VF.replaceAllUsesWith(RuntimeVF);
VPValue *MulByUF = Builder.createOverflowingOp(
Instruction::Mul,
{RuntimeVF, Plan.getConstantInt(TCTy, Plan.getConcreteUF())},
{true, false});
VFxUF.replaceAllUsesWith(MulByUF);
}
void VPlanTransforms::attachAliasMaskToHeaderMask(VPlan &Plan) {
VPSingleDefRecipe *HeaderMask = vputils::findHeaderMask(Plan);
auto *HeaderMaskDef = HeaderMask->getDefiningRecipe();
Type *I1Ty = IntegerType::getInt1Ty(Plan.getContext());
VPBuilder Builder(Plan.getVectorPreheader());
auto *AliasMask = Builder.createNaryOp(
VPInstruction::IncomingAliasMask, {}, nullptr, {}, {},
DebugLoc::getUnknown(), "incoming.alias.mask", I1Ty);
if (HeaderMaskDef->isPhi())
Builder = VPBuilder(&*HeaderMaskDef->getParent()->getFirstNonPhi());
else
Builder = VPBuilder::getToInsertAfter(HeaderMaskDef);
// Update all existing users of the header mask to "HeaderMask & AliasMask".
auto *ClampedHeaderMask = Builder.createAnd(HeaderMask, AliasMask);
HeaderMask->replaceUsesWithIf(ClampedHeaderMask, [&](VPUser &U, unsigned) {
return &U != ClampedHeaderMask;
});
}
VPValue *
VPlanTransforms::materializeAliasMask(VPlan &Plan, VPBasicBlock *AliasCheckVPBB,
ArrayRef<PointerDiffInfo> DiffChecks) {
VPBuilder Builder(AliasCheckVPBB);
Type *I1Ty = IntegerType::getInt1Ty(Plan.getContext());
VPValue *IncomingAliasMask = vputils::findIncomingAliasMask(Plan);
assert(IncomingAliasMask && "Expected an alias mask!");
VPValue *AliasMask = nullptr;
for (const PointerDiffInfo &Check : DiffChecks) {
VPValue *Src = vputils::getOrCreateVPValueForSCEVExpr(Plan, Check.SrcStart);
VPValue *Sink =
vputils::getOrCreateVPValueForSCEVExpr(Plan, Check.SinkStart);
Type *AddrType = Src->getScalarType();
// TODO: Only freeze the required pointer (not both src and sink).
if (Check.NeedsFreeze) {
Src = Builder.createScalarFreeze(Src, AddrType, DebugLoc::getUnknown());
Sink = Builder.createScalarFreeze(Sink, AddrType, DebugLoc::getUnknown());
}
// TODO: Generate loop_dependence_raw_mask when there's a read-after-write
// dependency between the source and the sink. This is not necessary for
// correctness of the mask, but using the "raw" variant prevents loads
// depending on the completion of stores.
VPWidenIntrinsicRecipe *WARMask = Builder.insert(new VPWidenIntrinsicRecipe(
Intrinsic::loop_dependence_war_mask,
{Src, Sink, Plan.getConstantInt(AddrType, Check.AccessSize)}, I1Ty));
if (AliasMask)
AliasMask = Builder.createAnd(AliasMask, WARMask);
else
AliasMask = WARMask;
}
Type *IVTy = Plan.getVectorLoopRegion()->getCanonicalIVType();
Type *IndexTy = Plan.getDataLayout().getIndexType(Plan.getContext(), 0);
VPValue *NumActive = Builder.createNaryOp(
VPInstruction::NumActiveLanes, {AliasMask}, nullptr, {}, {},
DebugLoc::getUnknown(), "num.active.lanes", IndexTy);
VPValue *ClampedVF = Builder.createScalarZExtOrTrunc(
NumActive, IVTy, IndexTy, DebugLoc::getCompilerGenerated());
IncomingAliasMask->replaceAllUsesWith(AliasMask);
return ClampedVF;
}
void VPlanTransforms::materializeAliasMaskCheckBlock(
VPlan &Plan, ArrayRef<PointerDiffInfo> DiffChecks, bool HasBranchWeights) {
VPBasicBlock *ClampedVFCheck =
Plan.createVPBasicBlock("vector.clamped.vf.check");
VPValue *ClampedVF = materializeAliasMask(Plan, ClampedVFCheck, DiffChecks);
VPBuilder Builder(ClampedVFCheck);
DebugLoc DL = DebugLoc::getCompilerGenerated();
Type *TCTy = Plan.getTripCount()->getScalarType();
// Check the "ClampedVF" from the alias mask is larger than one.
VPValue *IsScalar =
Builder.createICmp(CmpInst::ICMP_ULE, ClampedVF,
Plan.getConstantInt(TCTy, 1), DL, "vf.is.scalar");
VPValue *TripCount = Plan.getTripCount();
VPValue *MaxUIntTripCount =
Plan.getConstantInt(cast<IntegerType>(TCTy)->getMask());
VPValue *DistanceToMax = Builder.createSub(MaxUIntTripCount, TripCount);
// For tail-folding: Don't execute the vector loop if (UMax - n) < ClampedVF.
// Note: The ClampedVF may not be a power-of-two. This means the loop exit
// condition (index.next == n.vec) may not be correct in the case of an
// overflow. The issue is `n.vec` could be zero due to an overflow, but
// index.next is not guaranteed to overflow to zero as the ClampedVF is not a
// power-of-two).
VPValue *TripCountCheck = Builder.createICmp(
ICmpInst::ICMP_ULT, DistanceToMax, ClampedVF, DL, "vf.step.overflow");
VPValue *Cond = Builder.createOr(IsScalar, TripCountCheck, DL);
attachVPCheckBlock(Plan, Cond, ClampedVFCheck, HasBranchWeights);
// Materialize the trip count early as this will add a use of (VFxUF) that
// needs to be replaced with the ClampedVF.
materializeVectorTripCount(Plan, Plan.getVectorPreheader(),
/*TailByMasking=*/true,
/*RequiresScalarEpilogue=*/false,
&Plan.getVFxUF());
assert(Plan.getConcreteUF() == 1 &&
"Clamped VF not supported with interleaving");
Plan.getVF().replaceAllUsesWith(ClampedVF);
Plan.getVFxUF().replaceAllUsesWith(ClampedVF);
}
void VPlanTransforms::expandSCEVsToVPInstructions(VPlan &Plan,
ScalarEvolution &SE) {
auto *Entry = Plan.getEntry();
VPBuilder Builder(Entry, Entry->begin());
VPSCEVExpander Expander(Builder, SE);
// Expand VPExpandSCEVRecipes to VPInstructions using VPSCEVExpander. During
// the transition, unsupported VPExpandSCEVRecipes are skipped and left for
// late expansion.
for (VPRecipeBase &R : make_early_inc_range(*Entry)) {
auto *ExpSCEV = dyn_cast<VPExpandSCEVRecipe>(&R);
if (!ExpSCEV || ExpSCEV->getNumUsers() == 0)
continue;
Builder.setInsertPoint(ExpSCEV);
VPValue *Expanded = Expander.tryToExpand(ExpSCEV->getSCEV());
if (!Expanded)
continue;
ExpSCEV->replaceAllUsesWith(Expanded);
// TripCount should not be used after expansion to VPInstructions. Reset to
// poison to avoid dangling references.
if (Plan.getTripCount() == ExpSCEV)
Plan.resetTripCount(
Plan.getOrAddLiveIn(PoisonValue::get(ExpSCEV->getScalarType())));
ExpSCEV->eraseFromParent();
}
}
DenseMap<const SCEV *, Value *>
VPlanTransforms::expandSCEVs(VPlan &Plan, ScalarEvolution &SE) {
SCEVExpander Expander(SE, "induction", /*PreserveLCSSA=*/false);
auto *Entry = cast<VPIRBasicBlock>(Plan.getEntry());
BasicBlock *EntryBB = Entry->getIRBasicBlock();
DenseMap<const SCEV *, Value *> ExpandedSCEVs;
// Expand remaining VPExpandSCEVRecipes to IR instructions using SCEVExpander.
for (VPRecipeBase &R : make_early_inc_range(*Entry)) {
auto *ExpSCEV = dyn_cast<VPExpandSCEVRecipe>(&R);
if (!ExpSCEV)
continue;
const SCEV *Expr = ExpSCEV->getSCEV();
Value *Res =
Expander.expandCodeFor(Expr, Expr->getType(), EntryBB->getTerminator());
ExpandedSCEVs[Expr] = Res;
VPValue *Exp = Plan.getOrAddLiveIn(Res);
ExpSCEV->replaceAllUsesWith(Exp);
if (Plan.getTripCount() == ExpSCEV)
Plan.resetTripCount(Exp);
ExpSCEV->eraseFromParent();
}
assert(none_of(*Entry, IsaPred<VPExpandSCEVRecipe>) &&
"all VPExpandSCEVRecipes must have been expanded");
// Add IR instructions in the entry basic block but not in the VPIRBasicBlock
// to the VPIRBasicBlock.
auto EI = Entry->begin();
for (Instruction &I : drop_end(*EntryBB)) {
if (EI != Entry->end() && isa<VPIRInstruction>(*EI) &&
&cast<VPIRInstruction>(&*EI)->getInstruction() == &I) {
EI++;
continue;
}
VPIRInstruction::create(I)->insertBefore(*Entry, EI);
}
return ExpandedSCEVs;
}
/// Returns true if \p V is VPWidenLoadRecipe or VPInterleaveRecipe that can be
/// converted to a narrower recipe. \p V is used by a wide recipe that feeds a
/// store interleave group at index \p Idx, \p WideMember0 is the recipe feeding
/// the same interleave group at index 0. A VPWidenLoadRecipe can be narrowed to
/// an index-independent load if it feeds all wide ops at all indices (\p OpV
/// must be the operand at index \p OpIdx for both the recipe at lane 0, \p
/// WideMember0). A VPInterleaveRecipe can be narrowed to a wide load, if \p V
/// is defined at \p Idx of a load interleave group.
static bool canNarrowLoad(VPSingleDefRecipe *WideMember0, unsigned OpIdx,
VPValue *OpV, unsigned Idx, bool IsScalable) {
VPValue *Member0Op = WideMember0->getOperand(OpIdx);
VPRecipeBase *Member0OpR = Member0Op->getDefiningRecipe();
if (!Member0OpR)
return Member0Op == OpV;
if (auto *W = dyn_cast<VPWidenLoadRecipe>(Member0OpR))
// For scalable VFs, the narrowed plan processes vscale iterations at once,
// so a shared wide load cannot be narrowed to a uniform scalar; bail out.
return !IsScalable && !W->getMask() && W->isConsecutive() &&
Member0Op == OpV;
if (auto *IR = dyn_cast<VPInterleaveRecipe>(Member0OpR))
return IR->getInterleaveGroup()->isFull() && IR->getVPValue(Idx) == OpV;
return false;
}
static bool canNarrowOps(ArrayRef<VPValue *> Ops, bool IsScalable) {
SmallVector<VPValue *> Ops0;
auto *WideMember0 = dyn_cast<VPSingleDefRecipe>(Ops[0]);
if (!WideMember0)
return false;
for (VPValue *V : Ops) {
if (!isa<VPWidenRecipe, VPWidenCastRecipe>(V))
return false;
auto *R = cast<VPSingleDefRecipe>(V);
if (getOpcodeOrIntrinsicID(R) != getOpcodeOrIntrinsicID(WideMember0))
return false;
}
for (unsigned Idx = 0; Idx != WideMember0->getNumOperands(); ++Idx) {
SmallVector<VPValue *> OpsI;
for (VPValue *Op : Ops)
OpsI.push_back(Op->getDefiningRecipe()->getOperand(Idx));
if (canNarrowOps(OpsI, IsScalable))
continue;
if (any_of(enumerate(OpsI), [WideMember0, Idx, IsScalable](const auto &P) {
const auto &[OpIdx, OpV] = P;
return !canNarrowLoad(WideMember0, Idx, OpV, OpIdx, IsScalable);
}))
return false;
}
return true;
}
/// Returns VF from \p VFs if \p IR is a full interleave group with factor and
/// number of members both equal to VF. The interleave group must also access
/// the full vector width.
static std::optional<ElementCount>
isConsecutiveInterleaveGroup(VPInterleaveRecipe *InterleaveR,
ArrayRef<ElementCount> VFs,
const TargetTransformInfo &TTI) {
if (!InterleaveR || InterleaveR->getMask())
return std::nullopt;
Type *GroupElementTy = nullptr;
if (InterleaveR->getStoredValues().empty()) {
GroupElementTy = InterleaveR->getVPValue(0)->getScalarType();
if (!all_of(InterleaveR->definedValues(), [GroupElementTy](VPValue *Op) {
return Op->getScalarType() == GroupElementTy;
}))
return std::nullopt;
} else {
GroupElementTy = InterleaveR->getStoredValues()[0]->getScalarType();
if (!all_of(InterleaveR->getStoredValues(), [GroupElementTy](VPValue *Op) {
return Op->getScalarType() == GroupElementTy;
}))
return std::nullopt;
}
auto IG = InterleaveR->getInterleaveGroup();
if (IG->getFactor() != IG->getNumMembers())
return std::nullopt;
auto GetVectorBitWidthForVF = [&TTI](ElementCount VF) {
TypeSize Size = TTI.getRegisterBitWidth(
VF.isFixed() ? TargetTransformInfo::RGK_FixedWidthVector
: TargetTransformInfo::RGK_ScalableVector);
assert(Size.isScalable() == VF.isScalable() &&
"if Size is scalable, VF must be scalable and vice versa");
return Size.getKnownMinValue();
};
for (ElementCount VF : VFs) {
unsigned MinVal = VF.getKnownMinValue();
unsigned GroupSize = GroupElementTy->getScalarSizeInBits() * MinVal;
if (IG->getFactor() == MinVal && GroupSize == GetVectorBitWidthForVF(VF))
return {VF};
}
return std::nullopt;
}
/// Returns true if \p VPValue is a narrow VPValue.
static bool isAlreadyNarrow(VPValue *VPV) {
if (isa<VPIRValue>(VPV))
return true;
auto *RepR = dyn_cast<VPReplicateRecipe>(VPV);
return RepR && RepR->isSingleScalar();
}
// Convert the wide recipes defining the VPValues in \p Members feeding an
// interleave group to a single narrow variant. The first member is reused as
// the narrowed recipe.
static VPValue *
narrowInterleaveGroupOp(ArrayRef<VPValue *> Members,
SmallPtrSetImpl<VPValue *> &NarrowedOps) {
VPValue *V = Members.front();
auto *R = V->getDefiningRecipe();
if (!R || NarrowedOps.contains(V))
return V;
if (isAlreadyNarrow(V))
return V;
if (isa<VPWidenRecipe, VPWidenCastRecipe>(R)) {
auto *WideMember0 = cast<VPRecipeWithIRFlags>(R);
for (VPValue *Member : Members.drop_front())
WideMember0->intersectFlags(*cast<VPRecipeWithIRFlags>(Member));
for (unsigned Idx = 0, E = WideMember0->getNumOperands(); Idx != E; ++Idx) {
SmallVector<VPValue *> OpsI;
for (VPValue *Member : Members)
OpsI.push_back(Member->getDefiningRecipe()->getOperand(Idx));
WideMember0->setOperand(Idx, narrowInterleaveGroupOp(OpsI, NarrowedOps));
}
return V;
}
if (auto *LoadGroup = dyn_cast<VPInterleaveRecipe>(R)) {
// Narrow interleave group to wide load, as transformed VPlan will only
// process one original iteration.
auto *LI = cast<LoadInst>(LoadGroup->getInterleaveGroup()->getInsertPos());
auto *L = new VPWidenLoadRecipe(*LI, LoadGroup->getAddr(),
LoadGroup->getMask(), /*Consecutive=*/true,
*LoadGroup, LoadGroup->getDebugLoc());
L->insertBefore(LoadGroup);
NarrowedOps.insert(L);
return L;
}
if (auto *RepR = dyn_cast<VPReplicateRecipe>(R)) {
assert(RepR->isSingleScalar() && RepR->getOpcode() == Instruction::Load &&
"must be a single scalar load");
NarrowedOps.insert(RepR);
return RepR;
}
auto *WideLoad = cast<VPWidenLoadRecipe>(R);
VPValue *PtrOp = WideLoad->getAddr();
if (auto *VecPtr = dyn_cast<VPVectorPointerRecipe>(PtrOp))
PtrOp = VecPtr->getOperand(0);
// Narrow wide load to uniform scalar load, as transformed VPlan will only
// process one original iteration.
auto *N = new VPReplicateRecipe(&WideLoad->getIngredient(), {PtrOp},
/*IsUniform*/ true,
/*Mask*/ nullptr, {}, *WideLoad);
N->insertBefore(WideLoad);
NarrowedOps.insert(N);
return N;
}
std::unique_ptr<VPlan>
VPlanTransforms::narrowInterleaveGroups(VPlan &Plan,
const TargetTransformInfo &TTI) {
VPRegionBlock *VectorLoop = Plan.getVectorLoopRegion();
if (!VectorLoop)
return nullptr;
// Only handle single-block loops for now.
if (VectorLoop->getEntryBasicBlock() != VectorLoop->getExitingBasicBlock())
return nullptr;
// Skip plans when we may not be able to properly narrow.
VPBasicBlock *Exiting = VectorLoop->getExitingBasicBlock();
if (!match(&Exiting->back(), m_BranchOnCount()))
return nullptr;
assert(match(&Exiting->back(),
m_BranchOnCount(m_Add(m_VPValue(), m_Specific(&Plan.getVFxUF())),
m_Specific(&Plan.getVectorTripCount()))) &&
"unexpected branch-on-count");
SmallVector<VPInterleaveRecipe *> StoreGroups;
std::optional<ElementCount> VFToOptimize;
for (auto &R : *VectorLoop->getEntryBasicBlock()) {
if (isa<VPDerivedIVRecipe, VPScalarIVStepsRecipe>(&R) &&
vputils::onlyFirstLaneUsed(cast<VPSingleDefRecipe>(&R)))
continue;
// Bail out on recipes not supported at the moment:
// * phi recipes other than the canonical induction
// * recipes writing to memory except interleave groups
// Only support plans with a canonical induction phi.
if (R.isPhi())
return nullptr;
auto *InterleaveR = dyn_cast<VPInterleaveRecipe>(&R);
if (R.mayWriteToMemory() && !InterleaveR)
return nullptr;
// Bail out if any recipe defines a vector value used outside the
// vector loop region.
if (any_of(R.definedValues(), [&](VPValue *V) {
return any_of(V->users(), [&](VPUser *U) {
auto *UR = cast<VPRecipeBase>(U);
return UR->getParent()->getParent() != VectorLoop;
});
}))
return nullptr;
// All other ops are allowed, but we reject uses that cannot be converted
// when checking all allowed consumers (store interleave groups) below.
if (!InterleaveR)
continue;
// Try to find a single VF, where all interleave groups are consecutive and
// saturate the full vector width. If we already have a candidate VF, check
// if it is applicable for the current InterleaveR, otherwise look for a
// suitable VF across the Plan's VFs.
SmallVector<ElementCount> VFs =
VFToOptimize ? SmallVector<ElementCount>({*VFToOptimize})
: to_vector(Plan.vectorFactors());
std::optional<ElementCount> NarrowedVF =
isConsecutiveInterleaveGroup(InterleaveR, VFs, TTI);
if (!NarrowedVF || (VFToOptimize && NarrowedVF != VFToOptimize))
return nullptr;
VFToOptimize = NarrowedVF;
// Skip read interleave groups.
if (InterleaveR->getStoredValues().empty())
continue;
// Narrow interleave groups, if all operands are already matching narrow
// ops.
auto *Member0 = InterleaveR->getStoredValues()[0];
if (isAlreadyNarrow(Member0) &&
all_of(InterleaveR->getStoredValues(), equal_to(Member0))) {
StoreGroups.push_back(InterleaveR);
continue;
}
// For now, we only support full interleave groups storing load interleave
// groups.
if (all_of(enumerate(InterleaveR->getStoredValues()), [](auto Op) {
VPRecipeBase *DefR = Op.value()->getDefiningRecipe();
if (!DefR)
return false;
auto *IR = dyn_cast<VPInterleaveRecipe>(DefR);
return IR && IR->getInterleaveGroup()->isFull() &&
IR->getVPValue(Op.index()) == Op.value();
})) {
StoreGroups.push_back(InterleaveR);
continue;
}
// Check if all values feeding InterleaveR are matching wide recipes, which
// operands that can be narrowed.
if (!canNarrowOps(InterleaveR->getStoredValues(),
VFToOptimize->isScalable()))
return nullptr;
StoreGroups.push_back(InterleaveR);
}
if (StoreGroups.empty())
return nullptr;
VPBasicBlock *MiddleVPBB = Plan.getMiddleBlock();
bool RequiresScalarEpilogue =
MiddleVPBB->getNumSuccessors() == 1 &&
MiddleVPBB->getSingleSuccessor() == Plan.getScalarPreheader();
// Bail out for tail-folding (middle block with a single successor to exit).
if (MiddleVPBB->getNumSuccessors() != 2 && !RequiresScalarEpilogue)
return nullptr;
// All interleave groups in Plan can be narrowed for VFToOptimize. Split the
// original Plan into 2: a) a new clone which contains all VFs of Plan, except
// VFToOptimize, and b) the original Plan with VFToOptimize as single VF.
// TODO: Handle cases where only some interleave groups can be narrowed.
std::unique_ptr<VPlan> NewPlan;
if (size(Plan.vectorFactors()) != 1) {
NewPlan = std::unique_ptr<VPlan>(Plan.duplicate());
Plan.setVF(*VFToOptimize);
NewPlan->removeVF(*VFToOptimize);
}
// Convert InterleaveGroup \p R to a single VPWidenLoadRecipe.
SmallPtrSet<VPValue *, 4> NarrowedOps;
// Narrow operation tree rooted at store groups.
for (auto *StoreGroup : StoreGroups) {
VPValue *Res =
narrowInterleaveGroupOp(StoreGroup->getStoredValues(), NarrowedOps);
auto *SI =
cast<StoreInst>(StoreGroup->getInterleaveGroup()->getInsertPos());
auto *S = new VPWidenStoreRecipe(*SI, StoreGroup->getAddr(), Res, nullptr,
/*Consecutive=*/true, *StoreGroup,
StoreGroup->getDebugLoc());
S->insertBefore(StoreGroup);
StoreGroup->eraseFromParent();
}
// Adjust induction to reflect that the transformed plan only processes one
// original iteration.
VPInstruction *CanIVInc = vputils::findCanonicalIVIncrement(Plan);
Type *CanIVTy = VectorLoop->getCanonicalIVType();
VPBasicBlock *VectorPH = Plan.getVectorPreheader();
VPBuilder PHBuilder(VectorPH, VectorPH->begin());
VPValue *UF = &Plan.getUF();
VPValue *Step;
if (VFToOptimize->isScalable()) {
VPValue *VScale =
PHBuilder.createElementCount(CanIVTy, ElementCount::getScalable(1));
Step = PHBuilder.createOverflowingOp(Instruction::Mul, {VScale, UF},
{true, false});
Plan.getVF().replaceAllUsesWith(VScale);
} else {
Step = UF;
Plan.getVF().replaceAllUsesWith(Plan.getConstantInt(CanIVTy, 1));
}
// Materialize vector trip count with the narrowed step.
materializeVectorTripCount(Plan, VectorPH, /*TailByMasking=*/false,
RequiresScalarEpilogue, Step);
CanIVInc->setOperand(1, Step);
Plan.getVFxUF().replaceAllUsesWith(Step);
removeDeadRecipes(Plan);
assert(none_of(*VectorLoop->getEntryBasicBlock(),
IsaPred<VPVectorPointerRecipe>) &&
"All VPVectorPointerRecipes should have been removed");
return NewPlan;
}
/// Add branch weight metadata, if the \p Plan's middle block is terminated by a
/// BranchOnCond recipe.
void VPlanTransforms::addBranchWeightToMiddleTerminator(
VPlan &Plan, ElementCount VF, std::optional<unsigned> VScaleForTuning) {
VPBasicBlock *MiddleVPBB = Plan.getMiddleBlock();
auto *MiddleTerm =
dyn_cast_or_null<VPInstruction>(MiddleVPBB->getTerminator());
// Only add branch metadata if there is a (conditional) terminator.
if (!MiddleTerm)
return;
assert(MiddleTerm->getOpcode() == VPInstruction::BranchOnCond &&
"must have a BranchOnCond");
// Assume that `TripCount % VectorStep ` is equally distributed.
unsigned VectorStep = Plan.getConcreteUF() * VF.getKnownMinValue();
if (VF.isScalable() && VScaleForTuning.has_value())
VectorStep *= *VScaleForTuning;
assert(VectorStep > 0 && "trip count should not be zero");
MDBuilder MDB(Plan.getContext());
MDNode *BranchWeights =
MDB.createBranchWeights({1, VectorStep - 1}, /*IsExpected=*/false);
MiddleTerm->setMetadata(LLVMContext::MD_prof, BranchWeights);
}
void VPlanTransforms::adjustFirstOrderRecurrenceMiddleUsers(VPlan &Plan,
VFRange &Range) {
VPRegionBlock *VectorRegion = Plan.getVectorLoopRegion();
auto *MiddleVPBB = Plan.getMiddleBlock();
VPBuilder MiddleBuilder(MiddleVPBB, MiddleVPBB->getFirstNonPhi());
auto IsScalableOne = [](ElementCount VF) -> bool {
return VF == ElementCount::getScalable(1);
};
for (auto &HeaderPhi : VectorRegion->getEntryBasicBlock()->phis()) {
auto *FOR = dyn_cast<VPFirstOrderRecurrencePHIRecipe>(&HeaderPhi);
if (!FOR)
continue;
assert(VectorRegion->getSingleSuccessor() == Plan.getMiddleBlock() &&
"Cannot handle loops with uncountable early exits");
// Find the existing splice for this FOR, created in
// createHeaderPhiRecipes. All uses of FOR have already been replaced with
// RecurSplice there; only RecurSplice itself still references FOR.
auto *RecurSplice =
findUserOf<VPInstruction::FirstOrderRecurrenceSplice>(FOR);
assert(RecurSplice && "expected FirstOrderRecurrenceSplice");
// For VF vscale x 1, if vscale = 1, we are unable to extract the
// penultimate value of the recurrence. Instead we rely on the existing
// extract of the last element from the result of
// VPInstruction::FirstOrderRecurrenceSplice.
// TODO: Consider vscale_range info and UF.
if (any_of(RecurSplice->users(),
[](VPUser *U) { return !cast<VPRecipeBase>(U)->getRegion(); }) &&
LoopVectorizationPlanner::getDecisionAndClampRange(IsScalableOne,
Range))
return;
// This is the second phase of vectorizing first-order recurrences, creating
// extracts for users outside the loop. An overview of the transformation is
// described below. Suppose we have the following loop with some use after
// the loop of the last a[i-1],
//
// for (int i = 0; i < n; ++i) {
// t = a[i - 1];
// b[i] = a[i] - t;
// }
// use t;
//
// There is a first-order recurrence on "a". For this loop, the shorthand
// scalar IR looks like:
//
// scalar.ph:
// s.init = a[-1]
// br scalar.body
//
// scalar.body:
// i = phi [0, scalar.ph], [i+1, scalar.body]
// s1 = phi [s.init, scalar.ph], [s2, scalar.body]
// s2 = a[i]
// b[i] = s2 - s1
// br cond, scalar.body, exit.block
//
// exit.block:
// use = lcssa.phi [s1, scalar.body]
//
// In this example, s1 is a recurrence because it's value depends on the
// previous iteration. In the first phase of vectorization, we created a
// VPFirstOrderRecurrencePHIRecipe v1 for s1. Now we create the extracts
// for users in the scalar preheader and exit block.
//
// vector.ph:
// v_init = vector(..., ..., ..., a[-1])
// br vector.body
//
// vector.body
// i = phi [0, vector.ph], [i+4, vector.body]
// v1 = phi [v_init, vector.ph], [v2, vector.body]
// v2 = a[i, i+1, i+2, i+3]
// v1' = splice(v1(3), v2(0, 1, 2))
// b[i, i+1, i+2, i+3] = v2 - v1'
// br cond, vector.body, middle.block
//
// middle.block:
// vector.recur.extract.for.phi = v2(2)
// vector.recur.extract = v2(3)
// br cond, scalar.ph, exit.block
//
// scalar.ph:
// scalar.recur.init = phi [vector.recur.extract, middle.block],
// [s.init, otherwise]
// br scalar.body
//
// scalar.body:
// i = phi [0, scalar.ph], [i+1, scalar.body]
// s1 = phi [scalar.recur.init, scalar.ph], [s2, scalar.body]
// s2 = a[i]
// b[i] = s2 - s1
// br cond, scalar.body, exit.block
//
// exit.block:
// lo = lcssa.phi [s1, scalar.body],
// [vector.recur.extract.for.phi, middle.block]
//
// Update extracts of the splice in the middle block: they extract the
// penultimate element of the recurrence.
for (VPRecipeBase &R : make_early_inc_range(
make_range(MiddleVPBB->getFirstNonPhi(), MiddleVPBB->end()))) {
if (!match(&R, m_ExtractLastLaneOfLastPart(m_Specific(RecurSplice))))
continue;
auto *ExtractR = cast<VPInstruction>(&R);
VPValue *PenultimateElement = MiddleBuilder.createNaryOp(
VPInstruction::ExtractPenultimateElement, RecurSplice->getOperand(1),
{}, "vector.recur.extract.for.phi");
for (VPUser *ExitU : to_vector(ExtractR->users())) {
if (auto *ExitPhi = dyn_cast<VPIRPhi>(ExitU))
ExitPhi->replaceUsesOfWith(ExtractR, PenultimateElement);
}
}
}
}
/// Check if \p V is a binary expression of a widened IV and a loop-invariant
/// value. Returns the widened IV if found, nullptr otherwise.
static VPWidenIntOrFpInductionRecipe *getExpressionIV(VPValue *V) {
auto *BinOp = dyn_cast<VPWidenRecipe>(V);
if (!BinOp || !Instruction::isBinaryOp(BinOp->getOpcode()) ||
Instruction::isIntDivRem(BinOp->getOpcode()))
return nullptr;
VPValue *WidenIVCandidate = BinOp->getOperand(0);
VPValue *InvariantCandidate = BinOp->getOperand(1);
if (!isa<VPWidenIntOrFpInductionRecipe>(WidenIVCandidate))
std::swap(WidenIVCandidate, InvariantCandidate);
if (!InvariantCandidate->isDefinedOutsideLoopRegions())
return nullptr;
return dyn_cast<VPWidenIntOrFpInductionRecipe>(WidenIVCandidate);
}
/// Create a scalar version of \p BinOp, with its \p WidenIV operand replaced
/// by \p ScalarIV, and place it after \p ScalarIV's defining recipe.
static VPValue *cloneBinOpForScalarIV(VPWidenRecipe *BinOp, VPValue *ScalarIV,
VPWidenIntOrFpInductionRecipe *WidenIV) {
assert(Instruction::isBinaryOp(BinOp->getOpcode()) &&
BinOp->getNumOperands() == 2 && "BinOp must have 2 operands");
auto *ClonedOp = BinOp->clone();
if (ClonedOp->getOperand(0) == WidenIV) {
ClonedOp->setOperand(0, ScalarIV);
} else {
assert(ClonedOp->getOperand(1) == WidenIV && "one operand must be WideIV");
ClonedOp->setOperand(1, ScalarIV);
}
ClonedOp->insertAfter(ScalarIV->getDefiningRecipe());
return ClonedOp;
}
void VPlanTransforms::optimizeFindIVReductions(VPlan &Plan,
PredicatedScalarEvolution &PSE,
Loop &L) {
ScalarEvolution &SE = *PSE.getSE();
VPRegionBlock *VectorLoopRegion = Plan.getVectorLoopRegion();
// Helper lambda to check if the IV range excludes the sentinel value. Try
// signed first, then unsigned. Return an excluded sentinel if found,
// otherwise return std::nullopt.
auto CheckSentinel = [&SE](const SCEV *IVSCEV,
bool UseMax) -> std::optional<APSInt> {
unsigned BW = IVSCEV->getType()->getScalarSizeInBits();
for (bool Signed : {true, false}) {
APSInt Sentinel = UseMax ? APSInt::getMinValue(BW, /*Unsigned=*/!Signed)
: APSInt::getMaxValue(BW, /*Unsigned=*/!Signed);
ConstantRange IVRange =
Signed ? SE.getSignedRange(IVSCEV) : SE.getUnsignedRange(IVSCEV);
if (!IVRange.contains(Sentinel))
return Sentinel;
}
return std::nullopt;
};
VPValue *HeaderMask = vputils::findHeaderMask(Plan);
for (VPRecipeBase &Phi :
make_early_inc_range(VectorLoopRegion->getEntryBasicBlock()->phis())) {
auto *PhiR = dyn_cast<VPReductionPHIRecipe>(&Phi);
if (!PhiR || !RecurrenceDescriptor::isFindLastRecurrenceKind(
PhiR->getRecurrenceKind()))
continue;
Type *PhiTy = PhiR->getScalarType();
if (PhiTy->isPointerTy() || PhiTy->isFloatingPointTy())
continue;
// If there's a header mask, the backedge select will not be the find-last
// select.
VPValue *BackedgeVal = PhiR->getBackedgeValue();
auto *FindLastSelect = cast<VPSingleDefRecipe>(BackedgeVal);
if (HeaderMask &&
!match(BackedgeVal,
m_Select(m_Specific(HeaderMask),
m_VPSingleDefRecipe(FindLastSelect), m_Specific(PhiR))))
continue;
// Get the find-last expression from the find-last select of the reduction
// phi. The find-last select should be a select between the phi and the
// find-last expression.
VPValue *Cond, *FindLastExpression;
if (!match(FindLastSelect, m_Select(m_VPValue(Cond), m_Specific(PhiR),
m_VPValue(FindLastExpression))) &&
!match(FindLastSelect,
m_Select(m_VPValue(Cond), m_VPValue(FindLastExpression),
m_Specific(PhiR))))
continue;
// Check if FindLastExpression is a simple expression of a widened IV. If
// so, we can track the underlying IV instead and sink the expression.
auto *IVOfExpressionToSink = getExpressionIV(FindLastExpression);
const SCEV *IVSCEV = vputils::getSCEVExprForVPValue(
IVOfExpressionToSink ? IVOfExpressionToSink : FindLastExpression, PSE,
&L);
const SCEV *Step;
if (!match(IVSCEV, m_scev_AffineAddRec(m_SCEV(), m_SCEV(Step)))) {
assert(!match(vputils::getSCEVExprForVPValue(FindLastExpression, PSE, &L),
m_scev_AffineAddRec(m_SCEV(), m_SCEV())) &&
"IVOfExpressionToSink not being an AddRec must imply "
"FindLastExpression not being an AddRec.");
continue;
}
// Determine direction from SCEV step.
if (!SE.isKnownNonZero(Step))
continue;
// Positive step means we need UMax/SMax to find the last IV value, and
// UMin/SMin otherwise.
bool UseMax = SE.isKnownPositive(Step);
std::optional<APSInt> SentinelVal = CheckSentinel(IVSCEV, UseMax);
bool UseSigned = SentinelVal && SentinelVal->isSigned();
// Sinking an expression will disable epilogue vectorization. Only use it,
// if FindLastExpression cannot be vectorized via a sentinel. Sinking may
// also prevent vectorizing using a sentinel (e.g., if the expression is a
// multiply or divide by large constant, respectively), which also makes
// sinking undesirable.
if (IVOfExpressionToSink) {
const SCEV *FindLastExpressionSCEV =
vputils::getSCEVExprForVPValue(FindLastExpression, PSE, &L);
if (match(FindLastExpressionSCEV,
m_scev_AffineAddRec(m_SCEV(), m_SCEV(Step)))) {
bool NewUseMax = SE.isKnownPositive(Step);
if (auto NewSentinel =
CheckSentinel(FindLastExpressionSCEV, NewUseMax)) {
// The original expression already has a sentinel, so prefer not
// sinking to keep epilogue vectorization possible.
SentinelVal = *NewSentinel;
UseSigned = NewSentinel->isSigned();
UseMax = NewUseMax;
IVSCEV = FindLastExpressionSCEV;
IVOfExpressionToSink = nullptr;
}
}
}
// If no sentinel was found, fall back to a boolean AnyOf reduction to track
// if the condition was ever true. Requires the IV to not wrap, otherwise we
// cannot use min/max.
if (!SentinelVal) {
auto *AR = cast<SCEVAddRecExpr>(IVSCEV);
if (AR->hasNoSignedWrap())
UseSigned = true;
else if (AR->hasNoUnsignedWrap())
UseSigned = false;
else
continue;
}
VPInstruction *RdxResult = cast<VPInstruction>(vputils::findRecipe(
BackedgeVal,
match_fn(m_VPInstruction<VPInstruction::ComputeReductionResult>())));
VPValue *NewFindLastSelect = BackedgeVal;
VPValue *SelectCond = Cond;
if (!SentinelVal || IVOfExpressionToSink) {
// When we need to create a new select, normalize the condition so that
// PhiR is the last operand and include the header mask if needed.
DebugLoc DL = FindLastSelect->getDefiningRecipe()->getDebugLoc();
VPBuilder LoopBuilder(FindLastSelect->getDefiningRecipe());
if (FindLastSelect->getDefiningRecipe()->getOperand(1) == PhiR)
SelectCond = LoopBuilder.createNot(SelectCond);
// When tail folding, mask the condition with the header mask to prevent
// propagating poison from inactive lanes in the last vector iteration.
if (HeaderMask)
SelectCond = LoopBuilder.createLogicalAnd(HeaderMask, SelectCond);
if (SelectCond != Cond || IVOfExpressionToSink) {
NewFindLastSelect = LoopBuilder.createSelect(
SelectCond,
IVOfExpressionToSink ? IVOfExpressionToSink : FindLastExpression,
PhiR, DL);
}
}
// Create the reduction result in the middle block using sentinel directly.
RecurKind MinMaxKind =
UseMax ? (UseSigned ? RecurKind::SMax : RecurKind::UMax)
: (UseSigned ? RecurKind::SMin : RecurKind::UMin);
VPIRFlags Flags(MinMaxKind, /*IsOrdered=*/false, /*IsInLoop=*/false,
FastMathFlags());
DebugLoc ExitDL = RdxResult->getDebugLoc();
VPBuilder MiddleBuilder(RdxResult);
VPValue *ReducedIV =
MiddleBuilder.createNaryOp(VPInstruction::ComputeReductionResult,
NewFindLastSelect, Flags, ExitDL);
// If IVOfExpressionToSink is an expression to sink, sink it now.
VPValue *VectorRegionExitingVal = ReducedIV;
if (IVOfExpressionToSink)
VectorRegionExitingVal =
cloneBinOpForScalarIV(cast<VPWidenRecipe>(FindLastExpression),
ReducedIV, IVOfExpressionToSink);
VPValue *NewRdxResult;
VPValue *StartVPV = PhiR->getStartValue();
if (SentinelVal) {
// Sentinel-based approach: reduce IVs with min/max, compare against
// sentinel to detect if condition was ever true, select accordingly.
VPValue *Sentinel = Plan.getConstantInt(*SentinelVal);
auto *Cmp = MiddleBuilder.createICmp(CmpInst::ICMP_NE, ReducedIV,
Sentinel, ExitDL);
NewRdxResult = MiddleBuilder.createSelect(Cmp, VectorRegionExitingVal,
StartVPV, ExitDL);
StartVPV = Sentinel;
} else {
// Introduce a boolean AnyOf reduction to track if the condition was ever
// true in the loop. Use it to select the initial start value, if it was
// never true.
auto *AnyOfPhi = new VPReductionPHIRecipe(
/*Phi=*/nullptr, RecurKind::Or, *Plan.getFalse(), *Plan.getFalse(),
RdxUnordered{1}, {}, /*HasUsesOutsideReductionChain=*/false);
AnyOfPhi->insertAfter(PhiR);
VPBuilder LoopBuilder(BackedgeVal->getDefiningRecipe());
VPValue *OrVal = LoopBuilder.createOr(AnyOfPhi, SelectCond);
AnyOfPhi->setOperand(1, OrVal);
NewRdxResult = MiddleBuilder.createAnyOfReduction(
OrVal, VectorRegionExitingVal, StartVPV, ExitDL);
// Initialize the IV reduction phi with the neutral element, not the
// original start value, to ensure correct min/max reduction results.
StartVPV = Plan.getOrAddLiveIn(
getRecurrenceIdentity(MinMaxKind, IVSCEV->getType(), {}));
}
RdxResult->replaceAllUsesWith(NewRdxResult);
RdxResult->eraseFromParent();
auto *NewPhiR = new VPReductionPHIRecipe(
cast<PHINode>(PhiR->getUnderlyingInstr()), RecurKind::FindIV, *StartVPV,
*NewFindLastSelect, RdxUnordered{1}, {},
PhiR->hasUsesOutsideReductionChain());
NewPhiR->insertBefore(PhiR);
PhiR->replaceAllUsesWith(NewPhiR);
PhiR->eraseFromParent();
}
}
namespace {
using ExtendKind = TTI::PartialReductionExtendKind;
struct ReductionExtend {
Type *SrcType = nullptr;
ExtendKind Kind = ExtendKind::PR_None;
};
/// Describes the extends used to compute the extended reduction operand.
/// ExtendB is optional. If ExtendB is present, ExtendsUser is a binary
/// operation.
struct ExtendedReductionOperand {
/// The recipe that consumes the extends.
VPWidenRecipe *ExtendsUser = nullptr;
/// Extend descriptions (inputs to getPartialReductionCost).
ReductionExtend ExtendA, ExtendB;
};
/// A chain of recipes that form a partial reduction. Matches either
/// reduction_bin_op (extended op, accumulator), or
/// reduction_bin_op (accumulator, extended op).
/// The possible forms of the "extended op" are listed in
/// matchExtendedReductionOperand.
struct VPPartialReductionChain {
/// The top-level binary operation that forms the reduction to a scalar
/// after the loop body.
VPWidenRecipe *ReductionBinOp = nullptr;
/// The user of the extends that is then reduced.
ExtendedReductionOperand ExtendedOp;
/// The recurrence kind for the entire partial reduction chain.
/// This allows distinguishing between Sub and AddWithSub recurrences,
/// when the ReductionBinOp is a Instruction::Sub.
RecurKind RK;
/// The index of the accumulator operand of ReductionBinOp. The extended op
/// is `1 - AccumulatorOpIdx`.
unsigned AccumulatorOpIdx;
unsigned ScaleFactor;
};
static VPSingleDefRecipe *
optimizeExtendsForPartialReduction(VPSingleDefRecipe *Op) {
// reduce.add(mul(ext(A), C))
// -> reduce.add(mul(ext(A), ext(trunc(C))))
const APInt *Const;
if (match(Op, m_Mul(m_ZExtOrSExt(m_VPValue()), m_APInt(Const)))) {
auto *ExtA = cast<VPWidenCastRecipe>(Op->getOperand(0));
Instruction::CastOps ExtOpc = ExtA->getOpcode();
Type *NarrowTy = ExtA->getOperand(0)->getScalarType();
if (!Op->hasOneUse() ||
!llvm::canConstantBeExtended(
Const, NarrowTy, TTI::getPartialReductionExtendKind(ExtOpc)))
return Op;
VPBuilder Builder(Op);
auto *Trunc = Builder.createWidenCast(Instruction::CastOps::Trunc,
Op->getOperand(1), NarrowTy);
Type *WideTy = ExtA->getScalarType();
Op->setOperand(1, Builder.createWidenCast(ExtOpc, Trunc, WideTy));
return Op;
}
// reduce.add(abs(sub(ext(A), ext(B))))
// -> reduce.add(ext(absolute-difference(A, B)))
VPValue *X, *Y;
if (match(Op, m_WidenIntrinsic<Intrinsic::abs>(m_Sub(
m_ZExtOrSExt(m_VPValue(X)), m_ZExtOrSExt(m_VPValue(Y)))))) {
auto *Sub = Op->getOperand(0)->getDefiningRecipe();
auto *Ext = cast<VPWidenCastRecipe>(Sub->getOperand(0));
assert(Ext->getOpcode() ==
cast<VPWidenCastRecipe>(Sub->getOperand(1))->getOpcode() &&
"Expected both the LHS and RHS extends to be the same");
bool IsSigned = Ext->getOpcode() == Instruction::SExt;
VPBuilder Builder(Op);
Type *SrcTy = X->getScalarType();
auto *FreezeX = Builder.insert(new VPWidenRecipe(Instruction::Freeze, {X}));
auto *FreezeY = Builder.insert(new VPWidenRecipe(Instruction::Freeze, {Y}));
auto *Max = Builder.insert(
new VPWidenIntrinsicRecipe(IsSigned ? Intrinsic::smax : Intrinsic::umax,
{FreezeX, FreezeY}, SrcTy));
auto *Min = Builder.insert(
new VPWidenIntrinsicRecipe(IsSigned ? Intrinsic::smin : Intrinsic::umin,
{FreezeX, FreezeY}, SrcTy));
auto *AbsDiff =
Builder.insert(new VPWidenRecipe(Instruction::Sub, {Max, Min}));
return Builder.createWidenCast(Instruction::CastOps::ZExt, AbsDiff,
Op->getScalarType());
}
// reduce.add(ext(mul(ext(A), ext(B))))
// -> reduce.add(mul(wider_ext(A), wider_ext(B)))
// TODO: Support this optimization for float types.
if (match(Op, m_ZExtOrSExt(m_Mul(m_ZExtOrSExt(m_VPValue()),
m_ZExtOrSExt(m_VPValue()))))) {
auto *Ext = cast<VPWidenCastRecipe>(Op);
auto *Mul = cast<VPWidenRecipe>(Ext->getOperand(0));
auto *MulLHS = cast<VPWidenCastRecipe>(Mul->getOperand(0));
auto *MulRHS = cast<VPWidenCastRecipe>(Mul->getOperand(1));
if (!Mul->hasOneUse() ||
(Ext->getOpcode() != MulLHS->getOpcode() && MulLHS != MulRHS) ||
MulLHS->getOpcode() != MulRHS->getOpcode())
return Op;
VPBuilder Builder(Mul);
auto *NewLHS = Builder.createWidenCast(
MulLHS->getOpcode(), MulLHS->getOperand(0), Ext->getScalarType());
auto *NewRHS = MulLHS == MulRHS
? NewLHS
: Builder.createWidenCast(MulRHS->getOpcode(),
MulRHS->getOperand(0),
Ext->getScalarType());
auto *NewMul = Mul->cloneWithOperands({NewLHS, NewRHS});
Builder.insert(NewMul);
Op->replaceAllUsesWith(NewMul);
Op->eraseFromParent();
Mul->eraseFromParent();
return NewMul;
}
return Op;
}
static VPExpressionRecipe *
createPartialReductionExpression(VPReductionRecipe *Red) {
VPValue *VecOp = Red->getVecOp();
// reduce.[f]add(ext(op))
// -> VPExpressionRecipe(op, red)
if (match(VecOp, m_WidenAnyExtend(m_VPValue())))
return new VPExpressionRecipe(cast<VPWidenCastRecipe>(VecOp), Red);
// reduce.[f]add(neg(ext(op)))
// -> VPExpressionRecipe(op, sub/neg, red)
if (match(VecOp, m_AnyNeg(m_WidenAnyExtend(m_VPValue())))) {
auto *Neg = cast<VPWidenRecipe>(VecOp);
auto *Ext =
cast<VPWidenCastRecipe>(Neg->getOperand(Neg->getNumOperands() - 1));
return new VPExpressionRecipe(Ext, Neg, Red);
}
// reduce.[f]add([f]mul(ext(a), ext(b)))
// -> VPExpressionRecipe(a, b, mul, red)
if (match(VecOp, m_FMul(m_FPExt(m_VPValue()), m_FPExt(m_VPValue()))) ||
match(VecOp,
m_Mul(m_ZExtOrSExt(m_VPValue()), m_ZExtOrSExt(m_VPValue())))) {
auto *Mul = cast<VPWidenRecipe>(VecOp);
auto *ExtA = cast<VPWidenCastRecipe>(Mul->getOperand(0));
auto *ExtB = cast<VPWidenCastRecipe>(Mul->getOperand(1));
return new VPExpressionRecipe(ExtA, ExtB, Mul, Red);
}
// reduce.fadd(fneg(fmul(fpext(a), fpext(b))))
// -> VPExpressionRecipe(a, b, fmul, fsub, red)
if (match(VecOp,
m_FNeg(m_FMul(m_FPExt(m_VPValue()), m_FPExt(m_VPValue()))))) {
auto *FNeg = cast<VPWidenRecipe>(VecOp);
auto *FMul = cast<VPWidenRecipe>(FNeg->getOperand(0));
auto *ExtA = cast<VPWidenCastRecipe>(FMul->getOperand(0));
auto *ExtB = cast<VPWidenCastRecipe>(FMul->getOperand(1));
return new VPExpressionRecipe(ExtA, ExtB, FMul, FNeg, Red);
}
// reduce.add(neg(mul(ext(a), ext(b))))
// -> VPExpressionRecipe(a, b, mul, sub, red)
if (match(VecOp, m_Sub(m_ZeroInt(), m_Mul(m_ZExtOrSExt(m_VPValue()),
m_ZExtOrSExt(m_VPValue()))))) {
auto *Sub = cast<VPWidenRecipe>(VecOp);
auto *Mul = cast<VPWidenRecipe>(Sub->getOperand(1));
auto *ExtA = cast<VPWidenCastRecipe>(Mul->getOperand(0));
auto *ExtB = cast<VPWidenCastRecipe>(Mul->getOperand(1));
return new VPExpressionRecipe(ExtA, ExtB, Mul, Sub, Red);
}
llvm_unreachable("Unsupported expression");
}
// Helper to transform a partial reduction chain into a partial reduction
// recipe. Assumes profitability has been checked.
static void transformToPartialReduction(const VPPartialReductionChain &Chain,
VPlan &Plan,
VPReductionPHIRecipe *RdxPhi) {
VPWidenRecipe *WidenRecipe = Chain.ReductionBinOp;
assert(WidenRecipe->getNumOperands() == 2 && "Expected binary operation");
VPValue *Accumulator = WidenRecipe->getOperand(Chain.AccumulatorOpIdx);
auto *ExtendedOp = cast<VPSingleDefRecipe>(
WidenRecipe->getOperand(1 - Chain.AccumulatorOpIdx));
// FIXME: Do these transforms before invoking the cost-model.
ExtendedOp = optimizeExtendsForPartialReduction(ExtendedOp);
// Sub-reductions can be implemented in two ways:
// (1) negate the operand in the vector loop (the default way).
// (2) subtract the reduced value from the init value in the middle block.
// Both ways keep the reduction itself as an 'add' reduction.
//
// The ISD nodes for partial reductions don't support folding the
// sub/negation into its operands because the following is not a valid
// transformation:
// sub(0, mul(ext(a), ext(b)))
// -> mul(ext(a), ext(sub(0, b)))
//
// It's therefore better to choose option (2) such that the partial
// reduction is always positive (starting at '0') and to do a final
// subtract in the middle block.
if ((WidenRecipe->getOpcode() == Instruction::Sub &&
Chain.RK != RecurKind::Sub) ||
(WidenRecipe->getOpcode() == Instruction::FSub &&
Chain.RK != RecurKind::FSub)) {
VPBuilder Builder(WidenRecipe);
Type *ElemTy = ExtendedOp->getScalarType();
VPWidenRecipe *NegRecipe;
if (WidenRecipe->getOpcode() == Instruction::FSub) {
NegRecipe =
new VPWidenRecipe(Instruction::FNeg, {ExtendedOp}, VPIRFlags(),
VPIRMetadata(), DebugLoc::getUnknown());
} else {
auto *Zero = Plan.getZero(ElemTy);
NegRecipe =
new VPWidenRecipe(Instruction::Sub, {Zero, ExtendedOp}, VPIRFlags(),
VPIRMetadata(), DebugLoc::getUnknown());
}
Builder.insert(NegRecipe);
ExtendedOp = NegRecipe;
}
// Check if WidenRecipe is the final result of the reduction. If so look
// through selects for predicated reductions.
VPValue *Cond = nullptr;
VPValue *ExitValue = cast_or_null<VPInstruction>(
findUserOf(WidenRecipe, m_Select(m_VPValue(Cond), m_Specific(WidenRecipe),
m_Specific(RdxPhi))));
bool IsLastInChain = RdxPhi->getBackedgeValue() == WidenRecipe ||
RdxPhi->getBackedgeValue() == ExitValue;
assert((!ExitValue || IsLastInChain) &&
"if we found ExitValue, it must match RdxPhi's backedge value");
Type *PhiType = RdxPhi->getScalarType();
RecurKind RdxKind =
PhiType->isFloatingPointTy() ? RecurKind::FAdd : RecurKind::Add;
auto *PartialRed = new VPReductionRecipe(
RdxKind,
RdxKind == RecurKind::FAdd ? WidenRecipe->getFastMathFlagsOrNone()
: FastMathFlags(),
WidenRecipe->getUnderlyingInstr(), Accumulator, ExtendedOp, Cond,
RdxUnordered{/*VFScaleFactor=*/Chain.ScaleFactor});
PartialRed->insertBefore(WidenRecipe);
if (Cond)
ExitValue->replaceAllUsesWith(PartialRed);
WidenRecipe->replaceAllUsesWith(PartialRed);
// For cost-model purposes, fold this into a VPExpression.
VPExpressionRecipe *E = createPartialReductionExpression(PartialRed);
E->insertBefore(WidenRecipe);
PartialRed->replaceAllUsesWith(E);
// We only need to update the PHI node once, which is when we find the
// last reduction in the chain.
if (!IsLastInChain)
return;
// Scale the PHI and ReductionStartVector by the VFScaleFactor
assert(RdxPhi->getVFScaleFactor() == 1 && "scale factor must not be set");
RdxPhi->setVFScaleFactor(Chain.ScaleFactor);
auto *StartInst = cast<VPInstruction>(RdxPhi->getStartValue());
assert(StartInst->getOpcode() == VPInstruction::ReductionStartVector);
auto *NewScaleFactor = Plan.getConstantInt(32, Chain.ScaleFactor);
StartInst->setOperand(2, NewScaleFactor);
// If this is the last value in a sub-reduction chain, then update the PHI
// node to start at `0` and update the reduction-result to subtract from
// the PHI's start value.
if (Chain.RK != RecurKind::Sub && Chain.RK != RecurKind::FSub)
return;
VPValue *OldStartValue = StartInst->getOperand(0);
StartInst->setOperand(0, StartInst->getOperand(1));
// Replace reduction_result by 'sub (startval, reductionresult)'.
VPInstruction *RdxResult = vputils::findComputeReductionResult(RdxPhi);
assert(RdxResult && "Could not find reduction result");
VPBuilder Builder = VPBuilder::getToInsertAfter(RdxResult);
unsigned SubOpc = Chain.RK == RecurKind::FSub ? Instruction::BinaryOps::FSub
: Instruction::BinaryOps::Sub;
VPInstruction *NewResult = Builder.createNaryOp(
SubOpc, {OldStartValue, RdxResult}, VPIRFlags::getDefaultFlags(SubOpc),
RdxPhi->getDebugLoc());
RdxResult->replaceUsesWithIf(
NewResult,
[&NewResult](VPUser &U, unsigned Idx) { return &U != NewResult; });
}
/// Returns the cost of a link in a partial-reduction chain for a given VF.
static InstructionCost
getPartialReductionLinkCost(VPCostContext &CostCtx,
const VPPartialReductionChain &Link,
ElementCount VF) {
Type *RdxType = Link.ReductionBinOp->getScalarType();
const ExtendedReductionOperand &ExtendedOp = Link.ExtendedOp;
std::optional<unsigned> BinOpc = std::nullopt;
// If ExtendB is not none, then the "ExtendsUser" is the binary operation.
if (ExtendedOp.ExtendB.Kind != ExtendKind::PR_None)
BinOpc = ExtendedOp.ExtendsUser->getOpcode();
std::optional<llvm::FastMathFlags> Flags;
if (RdxType->isFloatingPointTy())
Flags = Link.ReductionBinOp->getFastMathFlagsOrNone();
auto GetLinkOpcode = [&Link]() -> unsigned {
switch (Link.RK) {
case RecurKind::Sub:
return Instruction::Add;
case RecurKind::FSub:
return Instruction::FAdd;
default:
return Link.ReductionBinOp->getOpcode();
}
};
return CostCtx.TTI.getPartialReductionCost(
GetLinkOpcode(), ExtendedOp.ExtendA.SrcType, ExtendedOp.ExtendB.SrcType,
RdxType, VF, ExtendedOp.ExtendA.Kind, ExtendedOp.ExtendB.Kind, BinOpc,
CostCtx.CostKind, Flags);
}
static ExtendKind getPartialReductionExtendKind(VPWidenCastRecipe *Cast) {
return TTI::getPartialReductionExtendKind(Cast->getOpcode());
}
/// Checks if \p Op (which is an operand of \p UpdateR) is an extended reduction
/// operand. This is an operand where the source of the value (e.g. a load) has
/// been extended (sext, zext, or fpext) before it is used in the reduction.
///
/// Possible forms matched by this function:
/// - UpdateR(PrevValue, ext(...))
/// - UpdateR(PrevValue, mul(ext(...), ext(...)))
/// - UpdateR(PrevValue, mul(ext(...), Constant))
/// - UpdateR(PrevValue, ext(mul(ext(...), ext(...))))
/// - UpdateR(PrevValue, ext(mul(ext(...), Constant)))
/// - UpdateR(PrevValue, abs(sub(ext(...), ext(...)))
///
/// Note: The second operand of UpdateR corresponds to \p Op in the examples.
static std::optional<ExtendedReductionOperand>
matchExtendedReductionOperand(VPWidenRecipe *UpdateR, VPValue *Op) {
assert(is_contained(UpdateR->operands(), Op) &&
"Op should be operand of UpdateR");
// Try matching an absolute difference operand of the form
// `abs(sub(ext(A), ext(B)))`. This will be later transformed into
// `ext(absolute-difference(A, B))`. This allows us to perform the absolute
// difference on a wider type and get the extend for "free" from the partial
// reduction.
VPValue *X, *Y;
if (Op->hasOneUse() &&
match(Op, m_WidenIntrinsic<Intrinsic::abs>(
m_OneUse(m_Sub(m_WidenAnyExtend(m_VPValue(X)),
m_WidenAnyExtend(m_VPValue(Y))))))) {
auto *Abs = cast<VPWidenIntrinsicRecipe>(Op);
auto *Sub = cast<VPWidenRecipe>(Abs->getOperand(0));
auto *LHSExt = cast<VPWidenCastRecipe>(Sub->getOperand(0));
auto *RHSExt = cast<VPWidenCastRecipe>(Sub->getOperand(1));
Type *LHSInputType = X->getScalarType();
Type *RHSInputType = Y->getScalarType();
if (LHSInputType != RHSInputType ||
LHSExt->getOpcode() != RHSExt->getOpcode())
return std::nullopt;
// Note: This is essentially the same as matching ext(...) as we will
// rewrite this operand to ext(absolute-difference(A, B)).
return ExtendedReductionOperand{
Sub,
/*ExtendA=*/{LHSInputType, getPartialReductionExtendKind(LHSExt)},
/*ExtendB=*/{}};
}
std::optional<TTI::PartialReductionExtendKind> OuterExtKind;
if (match(Op, m_WidenAnyExtend(m_VPValue()))) {
auto *CastRecipe = cast<VPWidenCastRecipe>(Op);
VPValue *CastSource = CastRecipe->getOperand(0);
OuterExtKind = getPartialReductionExtendKind(CastRecipe);
if (match(CastSource, m_Mul(m_VPValue(), m_VPValue())) ||
match(CastSource, m_FMul(m_VPValue(), m_VPValue()))) {
// Match: ext(mul(...))
// Record the outer extend kind and set `Op` to the mul. We can then match
// this as a binary operation. Note: We can optimize out the outer extend
// by widening the inner extends to match it. See
// optimizeExtendsForPartialReduction.
Op = CastSource;
} else {
return ExtendedReductionOperand{
UpdateR,
/*ExtendA=*/{CastSource->getScalarType(), *OuterExtKind},
/*ExtendB=*/{}};
}
}
if (!Op->hasOneUse())
return std::nullopt;
VPWidenRecipe *MulOp = dyn_cast<VPWidenRecipe>(Op);
if (!MulOp ||
!is_contained({Instruction::Mul, Instruction::FMul}, MulOp->getOpcode()))
return std::nullopt;
// The rest of the matching assumes `Op` is a (possibly extended) mul
// operation.
VPValue *LHS = MulOp->getOperand(0);
VPValue *RHS = MulOp->getOperand(1);
// The LHS of the operation must always be an extend.
if (!match(LHS, m_WidenAnyExtend(m_VPValue())))
return std::nullopt;
auto *LHSCast = cast<VPWidenCastRecipe>(LHS);
Type *LHSInputType = LHSCast->getOperand(0)->getScalarType();
ExtendKind LHSExtendKind = getPartialReductionExtendKind(LHSCast);
// The RHS of the operation can be an extend or a constant integer.
const APInt *RHSConst = nullptr;
VPWidenCastRecipe *RHSCast = nullptr;
if (match(RHS, m_WidenAnyExtend(m_VPValue())))
RHSCast = cast<VPWidenCastRecipe>(RHS);
else if (!match(RHS, m_APInt(RHSConst)) ||
!canConstantBeExtended(RHSConst, LHSInputType, LHSExtendKind))
return std::nullopt;
// The outer extend kind must match the inner extends for folding.
for (VPWidenCastRecipe *Cast : {LHSCast, RHSCast})
if (Cast && OuterExtKind &&
getPartialReductionExtendKind(Cast) != OuterExtKind)
return std::nullopt;
Type *RHSInputType = LHSInputType;
ExtendKind RHSExtendKind = LHSExtendKind;
if (RHSCast) {
RHSInputType = RHSCast->getOperand(0)->getScalarType();
RHSExtendKind = getPartialReductionExtendKind(RHSCast);
}
return ExtendedReductionOperand{
MulOp, {LHSInputType, LHSExtendKind}, {RHSInputType, RHSExtendKind}};
}
/// Examines each operation in the reduction chain corresponding to \p RedPhiR,
/// and determines if the target can use a cheaper operation with a wider
/// per-iteration input VF and narrower PHI VF. If successful, returns the chain
/// of operations in the reduction.
static std::optional<SmallVector<VPPartialReductionChain>>
getScaledReductions(VPReductionPHIRecipe *RedPhiR, VPCostContext &CostCtx,
VFRange &Range) {
// Get the backedge value from the reduction PHI and find the
// ComputeReductionResult that uses it (directly or through a select for
// predicated reductions).
auto *RdxResult = vputils::findComputeReductionResult(RedPhiR);
if (!RdxResult)
return std::nullopt;
VPValue *ExitValue = RdxResult->getOperand(0);
match(ExitValue, m_Select(m_VPValue(), m_VPValue(ExitValue), m_VPValue()));
SmallVector<VPPartialReductionChain> Chain;
RecurKind RK = RedPhiR->getRecurrenceKind();
Type *PhiType = RedPhiR->getScalarType();
TypeSize PHISize = PhiType->getPrimitiveSizeInBits();
// Work backwards from the ExitValue examining each reduction operation.
VPValue *CurrentValue = ExitValue;
while (CurrentValue != RedPhiR) {
auto *UpdateR = dyn_cast<VPWidenRecipe>(CurrentValue);
if (!UpdateR || !Instruction::isBinaryOp(UpdateR->getOpcode()))
return std::nullopt;
VPValue *Op = UpdateR->getOperand(1);
VPValue *PrevValue = UpdateR->getOperand(0);
// Find the extended operand. The other operand (PrevValue) is the next link
// in the reduction chain.
std::optional<ExtendedReductionOperand> ExtendedOp =
matchExtendedReductionOperand(UpdateR, Op);
if (!ExtendedOp) {
ExtendedOp = matchExtendedReductionOperand(UpdateR, PrevValue);
if (!ExtendedOp)
return std::nullopt;
std::swap(Op, PrevValue);
}
Type *ExtSrcType = ExtendedOp->ExtendA.SrcType;
TypeSize ExtSrcSize = ExtSrcType->getPrimitiveSizeInBits();
if (!PHISize.hasKnownScalarFactor(ExtSrcSize))
return std::nullopt;
// Check if a partial reduction chain is supported by the target (i.e. does
// not have an invalid cost) for the given VF range. Clamps the range and
// returns true if feasible for any VF.
VPPartialReductionChain Link(
{UpdateR, *ExtendedOp, RK,
PrevValue == UpdateR->getOperand(0) ? 0U : 1U,
static_cast<unsigned>(PHISize.getKnownScalarFactor(ExtSrcSize))});
Chain.push_back(Link);
CurrentValue = PrevValue;
}
// The chain links were collected by traversing backwards from the exit value.
// Reverse the chains so they are in program order.
std::reverse(Chain.begin(), Chain.end());
return Chain;
}
} // namespace
void VPlanTransforms::createPartialReductions(VPlan &Plan,
VPCostContext &CostCtx,
VFRange &Range) {
// Find all possible valid partial reductions, grouping chains by their PHI.
// This grouping allows invalidating the whole chain, if any link is not a
// valid partial reduction.
MapVector<VPReductionPHIRecipe *, SmallVector<VPPartialReductionChain>>
ChainsByPhi;
VPBasicBlock *HeaderVPBB = Plan.getVectorLoopRegion()->getEntryBasicBlock();
for (VPRecipeBase &R : HeaderVPBB->phis()) {
auto *RedPhiR = dyn_cast<VPReductionPHIRecipe>(&R);
if (!RedPhiR)
continue;
if (auto Chains = getScaledReductions(RedPhiR, CostCtx, Range))
ChainsByPhi.try_emplace(RedPhiR, std::move(*Chains));
}
if (ChainsByPhi.empty())
return;
// Build set of partial reduction operations for extend user validation and
// a map of reduction bin ops to their scale factors for scale validation.
SmallPtrSet<VPRecipeBase *, 4> PartialReductionOps;
DenseMap<VPSingleDefRecipe *, unsigned> ScaledReductionMap;
for (const auto &[_, Chains] : ChainsByPhi)
for (const VPPartialReductionChain &Chain : Chains) {
PartialReductionOps.insert(Chain.ExtendedOp.ExtendsUser);
ScaledReductionMap[Chain.ReductionBinOp] = Chain.ScaleFactor;
}
// A partial reduction is invalid if any of its extends are used by
// something that isn't another partial reduction. This is because the
// extends are intended to be lowered along with the reduction itself.
auto ExtendUsersValid = [&](VPValue *Ext) {
return !isa<VPWidenCastRecipe>(Ext) || all_of(Ext->users(), [&](VPUser *U) {
return PartialReductionOps.contains(cast<VPRecipeBase>(U));
});
};
auto IsProfitablePartialReductionChainForVF =
[&](ArrayRef<VPPartialReductionChain> Chain, ElementCount VF) -> bool {
InstructionCost PartialCost = 0, RegularCost = 0;
// The chain is a profitable partial reduction chain if the cost of handling
// the entire chain is cheaper when using partial reductions than when
// handling the entire chain using regular reductions.
for (const VPPartialReductionChain &Link : Chain) {
const ExtendedReductionOperand &ExtendedOp = Link.ExtendedOp;
InstructionCost LinkCost = getPartialReductionLinkCost(CostCtx, Link, VF);
if (!LinkCost.isValid())
return false;
PartialCost += LinkCost;
RegularCost += Link.ReductionBinOp->computeCost(VF, CostCtx);
// If ExtendB is not none, then the "ExtendsUser" is the binary operation.
if (ExtendedOp.ExtendB.Kind != ExtendKind::PR_None)
RegularCost += ExtendedOp.ExtendsUser->computeCost(VF, CostCtx);
for (VPValue *Op : ExtendedOp.ExtendsUser->operands())
if (auto *Extend = dyn_cast<VPWidenCastRecipe>(Op))
RegularCost += Extend->computeCost(VF, CostCtx);
}
return PartialCost.isValid() && PartialCost < RegularCost;
};
// Validate chains: check that extends are only used by partial reductions,
// and that reduction bin ops are only used by other partial reductions with
// matching scale factors, are outside the loop region or the select
// introduced by tail-folding. Otherwise we would create users of scaled
// reductions where the types of the other operands don't match.
for (auto &[RedPhiR, Chains] : ChainsByPhi) {
for (const VPPartialReductionChain &Chain : Chains) {
if (!all_of(Chain.ExtendedOp.ExtendsUser->operands(), ExtendUsersValid)) {
Chains.clear();
break;
}
auto UseIsValid = [&, RedPhiR = RedPhiR](VPUser *U) {
if (auto *PhiR = dyn_cast<VPReductionPHIRecipe>(U))
return PhiR == RedPhiR;
auto *R = cast<VPSingleDefRecipe>(U);
return Chain.ScaleFactor == ScaledReductionMap.lookup_or(R, 0) ||
match(R, m_ComputeReductionResult(
m_Specific(Chain.ReductionBinOp))) ||
match(R, m_Select(m_VPValue(), m_Specific(Chain.ReductionBinOp),
m_Specific(RedPhiR)));
};
if (!all_of(Chain.ReductionBinOp->users(), UseIsValid)) {
Chains.clear();
break;
}
// Check if the compute-reduction-result is used by a sunk store.
// TODO: Also form partial reductions in those cases.
if (auto *RdxResult = vputils::findComputeReductionResult(RedPhiR)) {
if (any_of(RdxResult->users(), [](VPUser *U) {
auto *RepR = dyn_cast<VPReplicateRecipe>(U);
return RepR && RepR->getOpcode() == Instruction::Store;
})) {
Chains.clear();
break;
}
}
}
// Clear the chain if it is not profitable.
if (!LoopVectorizationPlanner::getDecisionAndClampRange(
[&, &Chains = Chains](ElementCount VF) {
return IsProfitablePartialReductionChainForVF(Chains, VF);
},
Range))
Chains.clear();
}
for (auto &[Phi, Chains] : ChainsByPhi)
for (const VPPartialReductionChain &Chain : Chains)
transformToPartialReduction(Chain, Plan, Phi);
}
void VPlanTransforms::makeMemOpWideningDecisions(
VPlan &Plan, VFRange &Range, VPRecipeBuilder &RecipeBuilder) {
// Collect all loads/stores first. We will start with ones having simpler
// decisions followed by more complex ones that are potentially
// guided/dependent on the simpler ones.
SmallVector<VPInstruction *> MemOps;
for (VPBasicBlock *VPBB :
VPBlockUtils::blocksOnly<VPBasicBlock>(vp_depth_first_shallow(
Plan.getVectorLoopRegion()->getEntryBasicBlock()))) {
for (VPRecipeBase &R : *VPBB) {
auto *VPI = dyn_cast<VPInstruction>(&R);
if (VPI && VPI->getUnderlyingValue() &&
is_contained({Instruction::Load, Instruction::Store},
VPI->getOpcode()))
MemOps.push_back(VPI);
}
}
VPBasicBlock *MiddleVPBB = Plan.getMiddleBlock();
VPBuilder FinalRedStoresBuilder(MiddleVPBB, MiddleVPBB->getFirstNonPhi());
for (VPInstruction *VPI : MemOps) {
auto ReplaceWith = [&](VPRecipeBase *New) {
New->insertBefore(VPI);
if (VPI->getOpcode() == Instruction::Load)
VPI->replaceAllUsesWith(New->getVPSingleValue());
VPI->eraseFromParent();
};
// Note: we must do that for scalar VPlan as well.
if (RecipeBuilder.replaceWithFinalIfReductionStore(VPI,
FinalRedStoresBuilder))
continue;
// Filter out scalar VPlan for the remaining memory operations.
if (LoopVectorizationPlanner::getDecisionAndClampRange(
[](ElementCount VF) { return VF.isScalar(); }, Range))
continue;
if (VPHistogramRecipe *Histogram = RecipeBuilder.widenIfHistogram(VPI)) {
ReplaceWith(Histogram);
continue;
}
VPRecipeBase *Recipe = RecipeBuilder.tryToWidenMemory(VPI, Range);
if (!Recipe)
Recipe = RecipeBuilder.handleReplication(VPI, Range);
ReplaceWith(Recipe);
}
}
void VPlanTransforms::makeScalarizationDecisions(VPlan &Plan, VFRange &Range) {
if (LoopVectorizationPlanner::getDecisionAndClampRange(
[&](ElementCount VF) { return VF.isScalar(); }, Range))
return;
PostOrderTraversal<VPBlockDeepTraversalWrapper<VPBlockBase *>> POT(
Plan.getEntry());
for (VPBasicBlock *VPBB : VPBlockUtils::blocksOnly<VPBasicBlock>(POT)) {
for (VPRecipeBase &R : make_early_inc_range(reverse(*VPBB))) {
auto *VPI = dyn_cast<VPInstruction>(&R);
if (!VPI)
continue;
auto *I = cast_or_null<Instruction>(VPI->getUnderlyingValue());
// Wouldn't be able to create a `VPReplicateRecipe` anyway.
if (!I)
continue;
// If executing other lanes produces side-effects we can't avoid them.
if (VPI->mayHaveSideEffects())
continue;
// We want to drop the mask operand, verify we can safely do that.
if (VPI->isMasked() && !VPI->isSafeToSpeculativelyExecute())
continue;
// Avoid rewriting IV increment as that interferes with
// `removeRedundantCanonicalIVs`.
if (VPI->getOpcode() == Instruction::Add &&
any_of(VPI->operands(), IsaPred<VPWidenIntOrFpInductionRecipe>))
continue;
// Other lanes are needed - can't drop them.
if (!vputils::onlyFirstLaneUsed(VPI))
continue;
auto *Recipe = new VPReplicateRecipe(
I, VPI->operandsWithoutMask(), /*IsSingleScalar=*/true,
/*Mask=*/nullptr, *VPI, *VPI, VPI->getDebugLoc());
Recipe->insertBefore(VPI);
VPI->replaceAllUsesWith(Recipe);
VPI->eraseFromParent();
}
}
}
/// Returns true if \p Info's parameter kinds are compatible with \p Args.
static bool areVFParamsOk(const VFInfo &Info, ArrayRef<VPValue *> Args,
PredicatedScalarEvolution &PSE, const Loop *L) {
ScalarEvolution *SE = PSE.getSE();
return all_of(Info.Shape.Parameters, [&](VFParameter Param) {
switch (Param.ParamKind) {
case VFParamKind::Vector:
case VFParamKind::GlobalPredicate:
return true;
case VFParamKind::OMP_Uniform:
return SE->isSCEVable(Args[Param.ParamPos]->getScalarType()) &&
SE->isLoopInvariant(
vputils::getSCEVExprForVPValue(Args[Param.ParamPos], PSE, L),
L);
case VFParamKind::OMP_Linear:
return match(vputils::getSCEVExprForVPValue(Args[Param.ParamPos], PSE, L),
m_scev_AffineAddRec(
m_SCEV(), m_scev_SpecificSInt(Param.LinearStepOrPos),
m_SpecificLoop(L)));
default:
return false;
}
});
}
/// Find a vector variant of \p CI for \p VF, respecting \p MaskRequired.
/// Returns the variant function, or nullptr. Masked variants are assumed to
/// take the mask as a trailing parameter.
static Function *findVectorVariant(CallInst *CI, ArrayRef<VPValue *> Args,
ElementCount VF, bool MaskRequired,
PredicatedScalarEvolution &PSE,
const Loop *L) {
if (CI->isNoBuiltin())
return nullptr;
auto Mappings = VFDatabase::getMappings(*CI);
const auto *It = find_if(Mappings, [&](const VFInfo &Info) {
return Info.Shape.VF == VF && (!MaskRequired || Info.isMasked()) &&
areVFParamsOk(Info, Args, PSE, L);
});
if (It == Mappings.end())
return nullptr;
return CI->getModule()->getFunction(It->VectorName);
}
namespace {
/// The outcome of choosing how to widen a call at a given VF.
struct CallWideningDecision {
enum class KindTy { Scalarize, Intrinsic, VectorVariant };
CallWideningDecision(KindTy Kind, Function *Variant = nullptr)
: Kind(Kind), Variant(Variant) {}
KindTy Kind;
/// Set when Kind == VectorVariant.
Function *Variant;
bool operator==(const CallWideningDecision &Other) const {
return Kind == Other.Kind && Variant == Other.Variant;
}
};
} // namespace
/// Pick the cheapest widening for the call \p VPI at \p VF among scalarization,
/// vector intrinsic, and vector library variant.
static CallWideningDecision decideCallWidening(VPInstruction &VPI,
ArrayRef<VPValue *> Ops,
ElementCount VF,
VPCostContext &CostCtx) {
auto *CI = cast<CallInst>(VPI.getUnderlyingInstr());
// Scalar VFs and calls forced or known to scalarize always replicate.
if (VF.isScalar() || CostCtx.willBeScalarized(CI, VF))
return CallWideningDecision::KindTy::Scalarize;
auto *CalledFn = cast<Function>(
VPI.getOperand(VPI.getNumOperandsWithoutMask() - 1)->getLiveInIRValue());
Type *ResultTy = VPI.getScalarType();
Intrinsic::ID ID = getVectorIntrinsicIDForCall(CI, &CostCtx.TLI);
bool MaskRequired = CostCtx.isMaskRequired(CI);
// Pseudo intrinsics (assume, lifetime, ...) are always scalarized.
if (ID && VPCostContext::isFreeScalarIntrinsic(ID))
return CallWideningDecision::KindTy::Scalarize;
InstructionCost ScalarCost =
VPReplicateRecipe::computeCallCost(CalledFn, ResultTy, Ops,
/*IsSingleScalar=*/false, VF, CostCtx);
Function *VecFunc =
findVectorVariant(CI, Ops, VF, MaskRequired, CostCtx.PSE, CostCtx.L);
InstructionCost VecCallCost = InstructionCost::getInvalid();
if (VecFunc)
VecCallCost = VPWidenCallRecipe::computeCallCost(VecFunc, CostCtx);
// Prefer the intrinsic if it is at least as cheap as scalarizing and any
// available vector variant.
if (ID) {
InstructionCost IntrinsicCost =
VPWidenIntrinsicRecipe::computeCallCost(ID, Ops, VPI, VF, CostCtx);
if (IntrinsicCost.isValid() && ScalarCost >= IntrinsicCost &&
(!VecFunc || VecCallCost >= IntrinsicCost))
return CallWideningDecision::KindTy::Intrinsic;
}
// Otherwise, use a vector library variant when it beats scalarizing.
if (VecFunc && ScalarCost >= VecCallCost)
return {CallWideningDecision::KindTy::VectorVariant, VecFunc};
return CallWideningDecision::KindTy::Scalarize;
}
void VPlanTransforms::makeCallWideningDecisions(VPlan &Plan, VFRange &Range,
VPRecipeBuilder &RecipeBuilder,
VPCostContext &CostCtx) {
for (VPBasicBlock *VPBB : VPBlockUtils::blocksAs<VPBasicBlock>(
vp_depth_first_shallow(Plan.getVectorLoopRegion()->getEntry()))) {
for (VPRecipeBase &R : make_early_inc_range(*VPBB)) {
auto *VPI = dyn_cast<VPInstruction>(&R);
if (!VPI || !VPI->getUnderlyingValue() ||
VPI->getOpcode() != Instruction::Call)
continue;
auto *CI = cast<CallInst>(VPI->getUnderlyingInstr());
SmallVector<VPValue *, 4> Ops(VPI->op_begin(),
VPI->op_begin() + CI->arg_size());
CallWideningDecision Decision =
decideCallWidening(*VPI, Ops, Range.Start, CostCtx);
LoopVectorizationPlanner::getDecisionAndClampRange(
[&](ElementCount VF) {
return Decision == decideCallWidening(*VPI, Ops, VF, CostCtx);
},
Range);
VPSingleDefRecipe *Replacement = nullptr;
switch (Decision.Kind) {
case CallWideningDecision::KindTy::Intrinsic: {
Intrinsic::ID ID = getVectorIntrinsicIDForCall(CI, &CostCtx.TLI);
Type *ResultTy = VPI->getScalarType();
Replacement = new VPWidenIntrinsicRecipe(*CI, ID, Ops, ResultTy, *VPI,
*VPI, VPI->getDebugLoc());
break;
}
case CallWideningDecision::KindTy::VectorVariant: {
// Masked variants take the mask as a trailing parameter, so they have
// one more parameter than the original call's arguments.
if (Decision.Variant->arg_size() > Ops.size()) {
VPValue *Mask = VPI->isMasked() ? VPI->getMask() : Plan.getTrue();
Ops.push_back(Mask);
}
Ops.push_back(VPI->getOperand(VPI->getNumOperandsWithoutMask() - 1));
Replacement = new VPWidenCallRecipe(CI, Decision.Variant, Ops, *VPI,
*VPI, VPI->getDebugLoc());
break;
}
case CallWideningDecision::KindTy::Scalarize:
Replacement = RecipeBuilder.handleReplication(VPI, Range);
break;
}
Replacement->insertBefore(VPI);
VPI->replaceAllUsesWith(Replacement);
VPI->eraseFromParent();
}
}
}
void VPlanTransforms::convertToStridedAccesses(VPlan &Plan,
PredicatedScalarEvolution &PSE,
Loop &L, VPCostContext &Ctx,
VFRange &Range) {
if (Plan.hasScalarVFOnly())
return;
VPRegionBlock *VectorLoop = Plan.getVectorLoopRegion();
VPValue *I32VF = nullptr;
for (VPBasicBlock *VPBB : VPBlockUtils::blocksOnly<VPBasicBlock>(
vp_depth_first_shallow(VectorLoop->getEntry()))) {
for (VPRecipeBase &R : make_early_inc_range(*VPBB)) {
auto *LoadR = dyn_cast<VPWidenLoadRecipe>(&R);
// TODO: Support strided store.
// TODO: Transform reverse access into strided access with -1 stride.
// TODO: Transform gather/scatter with uniform address into strided access
// with 0 stride.
// TODO: Transform interleave access into multiple strided accesses.
if (!LoadR || LoadR->isConsecutive())
continue;
auto *Ptr = dyn_cast<VPWidenGEPRecipe>(LoadR->getAddr());
if (!Ptr)
continue;
// Check if this is a strided access by analyzing the address SCEV for an
// affine addRec.
const SCEV *PtrSCEV = vputils::getSCEVExprForVPValue(Ptr, PSE, &L);
const SCEV *Start;
const SCEVConstant *Step;
// TODO: Support non-constant loop invariant stride.
if (!match(PtrSCEV,
m_scev_AffineAddRec(m_SCEV(Start), m_SCEVConstant(Step),
m_SpecificLoop(&L))))
continue;
Type *LoadTy = LoadR->getScalarType();
Align Alignment = LoadR->getAlign();
auto IsProfitable = [&](ElementCount VF) {
Type *DataTy = toVectorTy(LoadTy, VF);
if (!Ctx.TTI.isLegalStridedLoadStore(DataTy, Alignment))
return false;
const InstructionCost CurrentCost = LoadR->computeCost(VF, Ctx);
const InstructionCost StridedLoadStoreCost =
VPWidenMemIntrinsicRecipe::computeMemIntrinsicCost(
Intrinsic::experimental_vp_strided_load, DataTy,
LoadR->isMasked(), Alignment, Ctx);
return StridedLoadStoreCost < CurrentCost;
};
if (!LoopVectorizationPlanner::getDecisionAndClampRange(IsProfitable,
Range))
continue;
// Invalidate the legacy widening decision so the cost of replaced load is
// not counted during precomputeCosts.
// TODO: Remove once the legacy exit cost computation is retired.
for (ElementCount VF : Range)
Ctx.invalidateWideningDecision(&LoadR->getIngredient(), VF);
// Get VF as i32 for the vector length operand.
if (!I32VF) {
VPBuilder Builder(Plan.getVectorPreheader());
I32VF = Builder.createScalarZExtOrTrunc(
&Plan.getVF(), Type::getInt32Ty(Plan.getContext()),
Plan.getVF().getScalarType(), DebugLoc::getUnknown());
}
VPBuilder Builder(LoadR);
// Create the base pointer of strided access.
// TODO: reuse VPDerivedIVRecipe for base pointer computation when it
// supports a general VPValue as the start value.
VPValue *StartVPV = vputils::getOrCreateVPValueForSCEVExpr(Plan, Start);
VPValue *StrideInBytes = Plan.getOrAddLiveIn(Step->getValue());
Type *IndexTy = Plan.getDataLayout().getIndexType(Ptr->getScalarType());
assert(IndexTy == StrideInBytes->getScalarType() &&
"Stride type from SCEV must match the index type");
VPValue *CanIV = Builder.createScalarSExtOrTrunc(
VectorLoop->getCanonicalIV(), IndexTy,
VectorLoop->getCanonicalIVType(), DebugLoc::getUnknown());
auto *AddRecPtr = cast<SCEVAddRecExpr>(PtrSCEV);
auto *Offset = Builder.createOverflowingOp(
Instruction::Mul, {CanIV, StrideInBytes},
{AddRecPtr->hasNoUnsignedWrap(), AddRecPtr->hasNoSignedWrap()});
auto *BasePtr = Builder.createNoWrapPtrAdd(
StartVPV, Offset,
AddRecPtr->hasNoUnsignedWrap() ? GEPNoWrapFlags::noUnsignedWrap()
: GEPNoWrapFlags::none());
// Create a new vector pointer for strided access.
VPValue *NewPtr = Builder.createVectorPointer(
BasePtr, Type::getInt8Ty(Plan.getContext()), StrideInBytes,
Ptr->getGEPNoWrapFlags(), Ptr->getDebugLoc());
VPValue *Mask = LoadR->getMask();
if (!Mask)
Mask = Plan.getTrue();
auto *StridedLoad = Builder.createWidenMemIntrinsic(
Intrinsic::experimental_vp_strided_load,
{NewPtr, StrideInBytes, Mask, I32VF}, LoadTy, Alignment, *LoadR,
LoadR->getDebugLoc());
LoadR->replaceAllUsesWith(StridedLoad);
}
}
}