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llvm-project/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp

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//===-- 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/SetVector.h"
#include "llvm/ADT/TypeSwitch.h"
#include "llvm/Analysis/IVDescriptors.h"
#include "llvm/Analysis/InstSimplifyFolder.h"
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/Analysis/VectorUtils.h"
#include "llvm/IR/Intrinsics.h"
#include "llvm/IR/MDBuilder.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/TypeSize.h"
using namespace llvm;
using namespace VPlanPatternMatch;
bool VPlanTransforms::tryToConvertVPInstructionsToVPRecipes(
VPlanPtr &Plan,
function_ref<const InductionDescriptor *(PHINode *)>
GetIntOrFpInductionDescriptor,
ScalarEvolution &SE, 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());
const auto *II = GetIntOrFpInductionDescriptor(Phi);
if (!II) {
NewRecipe = new VPWidenPHIRecipe(Phi, nullptr, PhiR->getDebugLoc());
for (VPValue *Op : PhiR->operands())
NewRecipe->addOperand(Op);
} else {
VPValue *Start = Plan->getOrAddLiveIn(II->getStartValue());
VPValue *Step =
vputils::getOrCreateVPValueForSCEVExpr(*Plan, II->getStep(), SE);
NewRecipe = new VPWidenIntOrFpInductionRecipe(
Phi, Start, Step, &Plan->getVF(), *II, Ingredient.getDebugLoc());
}
} else {
assert(isa<VPInstruction>(&Ingredient) &&
"only VPInstructions expected here");
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*/, false /*Reverse*/, VPIRMetadata(*Load),
Ingredient.getDebugLoc());
} else if (StoreInst *Store = dyn_cast<StoreInst>(Inst)) {
NewRecipe = new VPWidenStoreRecipe(
*Store, Ingredient.getOperand(1), Ingredient.getOperand(0),
nullptr /*Mask*/, false /*Consecutive*/, false /*Reverse*/,
VPIRMetadata(*Store), Ingredient.getDebugLoc());
} else if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Inst)) {
NewRecipe = new VPWidenGEPRecipe(GEP, Ingredient.operands());
} else if (CallInst *CI = dyn_cast<CallInst>(Inst)) {
Intrinsic::ID VectorID = getVectorIntrinsicIDForCall(CI, &TLI);
if (VectorID == Intrinsic::not_intrinsic)
return false;
NewRecipe = new VPWidenIntrinsicRecipe(
*CI, getVectorIntrinsicIDForCall(CI, &TLI),
{Ingredient.op_begin(), Ingredient.op_end() - 1}, CI->getType(),
CI->getDebugLoc());
} else if (SelectInst *SI = dyn_cast<SelectInst>(Inst)) {
NewRecipe = new VPWidenSelectRecipe(*SI, Ingredient.operands());
} else if (auto *CI = dyn_cast<CastInst>(Inst)) {
NewRecipe = new VPWidenCastRecipe(
CI->getOpcode(), Ingredient.getOperand(0), CI->getType(), *CI);
} else {
NewRecipe = new VPWidenRecipe(*Inst, Ingredient.operands());
}
}
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;
}
static bool sinkScalarOperands(VPlan &Plan) {
auto Iter = vp_depth_first_deep(Plan.getEntry());
bool Changed = false;
// First, collect the operands of all recipes in replicate blocks as seeds for
// sinking.
SetVector<std::pair<VPBasicBlock *, VPSingleDefRecipe *>> WorkList;
for (VPRegionBlock *VPR : VPBlockUtils::blocksOnly<VPRegionBlock>(Iter)) {
VPBasicBlock *EntryVPBB = VPR->getEntryBasicBlock();
if (!VPR->isReplicator() || EntryVPBB->getSuccessors().size() != 2)
continue;
VPBasicBlock *VPBB = dyn_cast<VPBasicBlock>(EntryVPBB->getSuccessors()[0]);
if (!VPBB || VPBB->getSingleSuccessor() != VPR->getExitingBasicBlock())
continue;
for (auto &Recipe : *VPBB) {
for (VPValue *Op : Recipe.operands())
if (auto *Def =
dyn_cast_or_null<VPSingleDefRecipe>(Op->getDefiningRecipe()))
WorkList.insert(std::make_pair(VPBB, Def));
}
}
bool ScalarVFOnly = Plan.hasScalarVFOnly();
// 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];
if (SinkCandidate->getParent() == SinkTo ||
SinkCandidate->mayHaveSideEffects() ||
SinkCandidate->mayReadOrWriteMemory())
continue;
if (auto *RepR = dyn_cast<VPReplicateRecipe>(SinkCandidate)) {
if (!ScalarVFOnly && RepR->isSingleScalar())
continue;
} else if (!isa<VPScalarIVStepsRecipe>(SinkCandidate))
continue;
bool NeedsDuplicating = false;
// All recipe users of the sink candidate must be in the same block SinkTo
// or all users outside of SinkTo must be uniform-after-vectorization (
// i.e., only first lane is used) . In the latter case, we need to duplicate
// SinkCandidate.
auto CanSinkWithUser = [SinkTo, &NeedsDuplicating,
SinkCandidate](VPUser *U) {
auto *UI = cast<VPRecipeBase>(U);
if (UI->getParent() == SinkTo)
return true;
NeedsDuplicating = UI->onlyFirstLaneUsed(SinkCandidate);
// We only know how to duplicate VPReplicateRecipes and
// VPScalarIVStepsRecipes for now.
return NeedsDuplicating &&
isa<VPReplicateRecipe, VPScalarIVStepsRecipe>(SinkCandidate);
};
if (!all_of(SinkCandidate->users(), CanSinkWithUser))
continue;
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);
// 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())
if (auto *Def =
dyn_cast_or_null<VPSingleDefRecipe>(Op->getDefiningRecipe()))
WorkList.insert(std::make_pair(SinkTo, Def));
Changed = true;
}
return Changed;
}
/// If \p R is a region with a VPBranchOnMaskRecipe in the entry block, return
/// the mask.
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,
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());
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(),
make_range(PredRecipe->op_begin(), std::prev(PredRecipe->op_end())),
PredRecipe->isSingleScalar(), nullptr /*Mask*/, *PredRecipe);
auto *Pred =
Plan.createVPBasicBlock(Twine(RegionName) + ".if", RecipeWithoutMask);
VPPredInstPHIRecipe *PHIRecipe = nullptr;
if (PredRecipe->getNumUsers() != 0) {
PHIRecipe = new VPPredInstPHIRecipe(RecipeWithoutMask,
RecipeWithoutMask->getDebugLoc());
PredRecipe->replaceAllUsesWith(PHIRecipe);
PHIRecipe->setOperand(0, RecipeWithoutMask);
}
PredRecipe->eraseFromParent();
auto *Exiting =
Plan.createVPBasicBlock(Twine(RegionName) + ".continue", PHIRecipe);
VPRegionBlock *Region =
Plan.createVPRegionBlock(Entry, Exiting, RegionName, true);
// Note: first set Entry as region entry and then connect successors starting
// from it in order, to propagate the "parent" of each VPBasicBlock.
VPBlockUtils::insertTwoBlocksAfter(Pred, Exiting, Entry);
VPBlockUtils::connectBlocks(Pred, Exiting);
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, Plan);
Region->setParent(CurrentBlock->getParent());
VPBlockUtils::insertOnEdge(CurrentBlock, SplitBlock, Region);
VPRegionBlock *ParentRegion = Region->getParent();
if (ParentRegion && ParentRegion->getExiting() == CurrentBlock)
ParentRegion->setExiting(SplitBlock);
}
}
/// Remove redundant VPBasicBlocks by merging them into their predecessor if
/// the predecessor has a single successor.
static bool 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);
for (auto *Succ : to_vector(VPBB->successors())) {
VPBlockUtils::disconnectBlocks(VPBB, Succ);
VPBlockUtils::connectBlocks(PredVPBB, Succ);
}
// 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.
auto &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;
}
}
FindMyCast = FoundUserCast;
}
FindMyCast->replaceAllUsesWith(IV);
}
}
/// Try to replace VPWidenCanonicalIVRecipes with a widened canonical IV
/// recipe, if it exists.
static void removeRedundantCanonicalIVs(VPlan &Plan) {
VPCanonicalIVPHIRecipe *CanonicalIV = Plan.getCanonicalIV();
VPWidenCanonicalIVRecipe *WidenNewIV = nullptr;
for (VPUser *U : CanonicalIV->users()) {
WidenNewIV = dyn_cast<VPWidenCanonicalIVRecipe>(U);
if (WidenNewIV)
break;
}
if (!WidenNewIV)
return;
VPBasicBlock *HeaderVPBB = Plan.getVectorLoopRegion()->getEntryBasicBlock();
for (VPRecipeBase &Phi : HeaderVPBB->phis()) {
auto *WidenOriginalIV = dyn_cast<VPWidenIntOrFpInductionRecipe>(&Phi);
if (!WidenOriginalIV || !WidenOriginalIV->isCanonical())
continue;
// Replace WidenNewIV with WidenOriginalIV if WidenOriginalIV provides
// everything WidenNewIV's users need. That is, WidenOriginalIV will
// generate a vector phi or all users of WidenNewIV demand the first lane
// only.
if (!vputils::onlyScalarValuesUsed(WidenOriginalIV) ||
vputils::onlyFirstLaneUsed(WidenNewIV)) {
WidenNewIV->replaceAllUsesWith(WidenOriginalIV);
WidenNewIV->eraseFromParent();
return;
}
}
}
/// 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) {
for (VPBasicBlock *VPBB : VPBlockUtils::blocksOnly<VPBasicBlock>(
vp_post_order_deep(Plan.getEntry()))) {
// 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.
auto *PhiR = dyn_cast<VPPhi>(&R);
if (!PhiR || PhiR->getNumOperands() != 2 || PhiR->getNumUsers() != 1)
continue;
VPValue *Incoming = PhiR->getOperand(1);
if (*PhiR->user_begin() != Incoming->getDefiningRecipe() ||
Incoming->getNumUsers() != 1)
continue;
PhiR->replaceAllUsesWith(PhiR->getOperand(0));
PhiR->eraseFromParent();
Incoming->getDefiningRecipe()->eraseFromParent();
}
}
}
static VPScalarIVStepsRecipe *
createScalarIVSteps(VPlan &Plan, InductionDescriptor::InductionKind Kind,
Instruction::BinaryOps InductionOpcode,
FPMathOperator *FPBinOp, Instruction *TruncI,
VPValue *StartV, VPValue *Step, DebugLoc DL,
VPBuilder &Builder) {
VPBasicBlock *HeaderVPBB = Plan.getVectorLoopRegion()->getEntryBasicBlock();
VPCanonicalIVPHIRecipe *CanonicalIV = Plan.getCanonicalIV();
VPSingleDefRecipe *BaseIV = Builder.createDerivedIV(
Kind, FPBinOp, StartV, CanonicalIV, Step, "offset.idx");
// Truncate base induction if needed.
VPTypeAnalysis TypeInfo(Plan);
Type *ResultTy = TypeInfo.inferScalarType(BaseIV);
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 = TypeInfo.inferScalarType(Step);
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);
}
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]);
if (isa<VPHeaderPHIRecipe>(Cur))
continue;
for (VPValue *V : Cur->definedValues())
Users.insert_range(V->users());
}
return Users.takeVector();
}
/// 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<VPSingleDefRecipe>(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;
auto *Clone = new VPReplicateRecipe(Def->getUnderlyingInstr(),
Def->operands(), /*IsUniform*/ true);
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 (!PtrIV->onlyScalarsGenerated(Plan.hasScalableVF()))
continue;
const InductionDescriptor &ID = PtrIV->getInductionDescriptor();
VPValue *StartV =
Plan.getOrAddLiveIn(ConstantInt::get(ID.getStep()->getType(), 0));
VPValue *StepV = PtrIV->getOperand(1);
VPScalarIVStepsRecipe *Steps = createScalarIVSteps(
Plan, InductionDescriptor::IK_IntInduction, Instruction::Add, nullptr,
nullptr, StartV, StepV, PtrIV->getDebugLoc(), Builder);
VPValue *PtrAdd = Builder.createPtrAdd(PtrIV->getStartValue(), Steps,
PtrIV->getDebugLoc(), "next.gep");
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)
WideIV->replaceAllUsesWith(Steps);
else
WideIV->replaceUsesWithIf(Steps, [WideIV](VPUser &U, unsigned) {
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) {
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_Binary<Instruction::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))) ||
!Step->isLiveIn() || !IVStep->isLiveIn())
return false;
auto *StepCI = dyn_cast<ConstantInt>(Step->getLiveInIRValue());
auto *IVStepCI = dyn_cast<ConstantInt>(IVStep->getLiveInIRValue());
return StepCI && IVStepCI &&
StepCI->getValue() == (-1 * IVStepCI->getValue());
}
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,
VPTypeAnalysis &TypeInfo,
VPBlockBase *PredVPBB,
VPValue *Op) {
VPValue *Incoming, *Mask;
if (!match(Op, m_VPInstruction<VPInstruction::ExtractLane>(
m_VPInstruction<VPInstruction::FirstActiveLane>(
m_VPValue(Mask)),
m_VPValue(Incoming))))
return nullptr;
auto *WideIV = getOptimizableIVOf(Incoming);
if (!WideIV)
return nullptr;
auto *WideIntOrFp = dyn_cast<VPWidenIntOrFpInductionRecipe>(WideIV);
if (WideIntOrFp && WideIntOrFp->getTruncInst())
return nullptr;
// Calculate the final index.
VPValue *EndValue = Plan.getCanonicalIV();
auto CanonicalIVType = Plan.getCanonicalIV()->getScalarType();
VPBuilder B(cast<VPBasicBlock>(PredVPBB));
DebugLoc DL = cast<VPInstruction>(Op)->getDebugLoc();
VPValue *FirstActiveLane =
B.createNaryOp(VPInstruction::FirstActiveLane, Mask, DL);
Type *FirstActiveLaneType = TypeInfo.inferScalarType(FirstActiveLane);
FirstActiveLane = B.createScalarZExtOrTrunc(FirstActiveLane, CanonicalIVType,
FirstActiveLaneType, DL);
EndValue = B.createNaryOp(Instruction::Add, {EndValue, 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.getOrAddLiveIn(ConstantInt::get(CanonicalIVType, 1));
EndValue = B.createNaryOp(Instruction::Add, {EndValue, One}, DL);
}
if (!WideIntOrFp || !WideIntOrFp->isCanonical()) {
const InductionDescriptor &ID = WideIV->getInductionDescriptor();
VPValue *Start = WideIV->getStartValue();
VPValue *Step = WideIV->getStepValue();
EndValue = B.createDerivedIV(
ID.getKind(), dyn_cast_or_null<FPMathOperator>(ID.getInductionBinOp()),
Start, EndValue, Step);
}
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, VPTypeAnalysis &TypeInfo,
VPBlockBase *PredVPBB, VPValue *Op,
DenseMap<VPValue *, VPValue *> &EndValues) {
VPValue *Incoming;
if (!match(Op, m_VPInstruction<VPInstruction::ExtractLastElement>(
m_VPValue(Incoming))))
return nullptr;
auto *WideIV = getOptimizableIVOf(Incoming);
if (!WideIV)
return nullptr;
VPValue *EndValue = EndValues.lookup(WideIV);
assert(EndValue && "end value must have been pre-computed");
// `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.
VPBuilder B(cast<VPBasicBlock>(PredVPBB)->getTerminator());
VPValue *Step = WideIV->getStepValue();
Type *ScalarTy = TypeInfo.inferScalarType(WideIV);
if (ScalarTy->isIntegerTy())
return B.createNaryOp(Instruction::Sub, {EndValue, Step}, {}, "ind.escape");
if (ScalarTy->isPointerTy()) {
Type *StepTy = TypeInfo.inferScalarType(Step);
auto *Zero = Plan.getOrAddLiveIn(ConstantInt::get(StepTy, 0));
return B.createPtrAdd(EndValue,
B.createNaryOp(Instruction::Sub, {Zero, Step}), {},
"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::optimizeInductionExitUsers(
VPlan &Plan, DenseMap<VPValue *, VPValue *> &EndValues) {
VPBlockBase *MiddleVPBB = Plan.getMiddleBlock();
VPTypeAnalysis TypeInfo(Plan);
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, TypeInfo, PredVPBB, ExitIRI->getOperand(Idx), EndValues);
else
Escape = optimizeEarlyExitInductionUser(Plan, TypeInfo, PredVPBB,
ExitIRI->getOperand(Idx));
if (Escape)
ExitIRI->setOperand(Idx, Escape);
}
}
}
}
/// Remove redundant EpxandSCEVRecipes 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;
auto I = SCEV2VPV.insert({ExpR->getSCEV(), ExpR});
if (I.second)
continue;
ExpR->replaceAllUsesWith(I.first->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;
WorkList.append(R->op_begin(), R->op_end());
R->eraseFromParent();
}
}
/// Try to fold \p R using InstSimplifyFolder. Will succeed and return a
/// non-nullptr Value for a handled \p Opcode if corresponding \p Operands are
/// foldable live-ins.
static Value *tryToFoldLiveIns(const VPRecipeBase &R, unsigned Opcode,
ArrayRef<VPValue *> Operands,
const DataLayout &DL, VPTypeAnalysis &TypeInfo) {
SmallVector<Value *, 4> Ops;
for (VPValue *Op : Operands) {
if (!Op->isLiveIn() || !Op->getLiveInIRValue())
return nullptr;
Ops.push_back(Op->getLiveInIRValue());
}
InstSimplifyFolder Folder(DL);
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],
TypeInfo.inferScalarType(R.getVPSingleValue()));
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(TypeInfo.getContext()), 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;
}
/// Try to simplify recipe \p R.
static void simplifyRecipe(VPRecipeBase &R, VPTypeAnalysis &TypeInfo) {
VPlan *Plan = R.getParent()->getPlan();
auto *Def = dyn_cast<VPSingleDefRecipe>(&R);
if (!Def)
return;
// Simplification of live-in IR values for SingleDef recipes using
// InstSimplifyFolder.
if (TypeSwitch<VPRecipeBase *, bool>(&R)
.Case<VPInstruction, VPWidenRecipe, VPWidenCastRecipe,
VPReplicateRecipe, VPWidenSelectRecipe>([&](auto *I) {
const DataLayout &DL =
Plan->getScalarHeader()->getIRBasicBlock()->getDataLayout();
Value *V = tryToFoldLiveIns(*I, I->getOpcode(), I->operands(), DL,
TypeInfo);
if (V)
I->replaceAllUsesWith(Plan->getOrAddLiveIn(V));
return V;
})
.Default([](auto *) { return false; }))
return;
// Fold PredPHI LiveIn -> LiveIn.
if (auto *PredPHI = dyn_cast<VPPredInstPHIRecipe>(&R)) {
VPValue *Op = PredPHI->getOperand(0);
if (Op->isLiveIn())
PredPHI->replaceAllUsesWith(Op);
}
VPValue *A;
if (match(Def, m_Trunc(m_ZExtOrSExt(m_VPValue(A))))) {
Type *TruncTy = TypeInfo.inferScalarType(Def);
Type *ATy = TypeInfo.inferScalarType(A);
if (TruncTy == ATy) {
Def->replaceAllUsesWith(A);
} else {
// Don't replace a scalarizing recipe with a widened cast.
if (isa<VPReplicateRecipe>(Def))
return;
if (ATy->getScalarSizeInBits() < TruncTy->getScalarSizeInBits()) {
unsigned ExtOpcode = match(R.getOperand(0), m_SExt(m_VPValue()))
? Instruction::SExt
: Instruction::ZExt;
auto *VPC =
new VPWidenCastRecipe(Instruction::CastOps(ExtOpcode), A, TruncTy);
if (auto *UnderlyingExt = R.getOperand(0)->getUnderlyingValue()) {
// UnderlyingExt has distinct return type, used to retain legacy cost.
VPC->setUnderlyingValue(UnderlyingExt);
}
VPC->insertBefore(&R);
Def->replaceAllUsesWith(VPC);
} else if (ATy->getScalarSizeInBits() > TruncTy->getScalarSizeInBits()) {
auto *VPC = new VPWidenCastRecipe(Instruction::Trunc, A, TruncTy);
VPC->insertBefore(&R);
Def->replaceAllUsesWith(VPC);
}
}
#ifndef NDEBUG
// Verify that the cached type info is for both A and its users is still
// accurate by comparing it to freshly computed types.
VPTypeAnalysis TypeInfo2(*Plan);
assert(TypeInfo.inferScalarType(A) == TypeInfo2.inferScalarType(A));
for (VPUser *U : A->users()) {
auto *R = cast<VPRecipeBase>(U);
for (VPValue *VPV : R->definedValues())
assert(TypeInfo.inferScalarType(VPV) == TypeInfo2.inferScalarType(VPV));
}
#endif
}
// 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;
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;
}
// OR x, 1 -> 1.
if (match(Def, m_c_BinaryOr(m_VPValue(X), m_AllOnes()))) {
Def->replaceAllUsesWith(Def->getOperand(0) == X ? Def->getOperand(1)
: Def->getOperand(0));
Def->eraseFromParent();
return;
}
if (match(Def, m_Select(m_VPValue(), m_VPValue(X), m_Deferred(X))))
return Def->replaceAllUsesWith(X);
// select !c, x, y -> select c, y, x
VPValue *C;
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;
}
if (match(Def, m_c_Mul(m_VPValue(A), m_SpecificInt(1))))
return Def->replaceAllUsesWith(A);
if (match(Def, m_c_Mul(m_VPValue(A), m_SpecificInt(0))))
return Def->replaceAllUsesWith(R.getOperand(0) == A ? R.getOperand(1)
: R.getOperand(0));
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.
if (isa<VPWidenRecipe>(A) && A->getNumUsers() == 1) {
auto *WideCmp = cast<VPWidenRecipe>(A);
if (WideCmp->getOpcode() == Instruction::ICmp ||
WideCmp->getOpcode() == Instruction::FCmp) {
WideCmp->setPredicate(
CmpInst::getInversePredicate(WideCmp->getPredicate()));
Def->replaceAllUsesWith(WideCmp);
// If WideCmp doesn't have a debug location, use the one from the
// negation, to preserve the location.
if (!WideCmp->getDebugLoc() && R.getDebugLoc())
WideCmp->setDebugLoc(R.getDebugLoc());
}
}
}
// Remove redundant DerviedIVs, that is 0 + A * 1 -> A and 0 + 0 * x -> 0.
if ((match(Def,
m_DerivedIV(m_SpecificInt(0), m_VPValue(A), m_SpecificInt(1))) ||
match(Def,
m_DerivedIV(m_SpecificInt(0), m_SpecificInt(0), m_VPValue()))) &&
TypeInfo.inferScalarType(Def->getOperand(1)) ==
TypeInfo.inferScalarType(Def))
return Def->replaceAllUsesWith(Def->getOperand(1));
if (match(Def, m_VPInstruction<VPInstruction::WideIVStep>(
m_VPValue(X), m_SpecificInt(1)))) {
Type *WideStepTy = TypeInfo.inferScalarType(Def);
if (TypeInfo.inferScalarType(X) != WideStepTy)
X = VPBuilder(Def).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))) &&
TypeInfo.inferScalarType(R.getVPSingleValue())->isIntegerTy(1)) {
Def->setOperand(1, Def->getOperand(0));
Def->setOperand(0, Y);
return;
}
if (auto *Phi = dyn_cast<VPFirstOrderRecurrencePHIRecipe>(Def)) {
if (Phi->getOperand(0) == Phi->getOperand(1))
Def->replaceAllUsesWith(Phi->getOperand(0));
return;
}
// Look through ExtractLastElement (BuildVector ....).
if (match(&R, m_VPInstruction<VPInstruction::ExtractLastElement>(
m_BuildVector()))) {
auto *BuildVector = cast<VPInstruction>(R.getOperand(0));
Def->replaceAllUsesWith(
BuildVector->getOperand(BuildVector->getNumOperands() - 1));
return;
}
// Look through ExtractPenultimateElement (BuildVector ....).
if (match(&R, m_VPInstruction<VPInstruction::ExtractPenultimateElement>(
m_BuildVector()))) {
auto *BuildVector = cast<VPInstruction>(R.getOperand(0));
Def->replaceAllUsesWith(
BuildVector->getOperand(BuildVector->getNumOperands() - 2));
return;
}
if (auto *Phi = dyn_cast<VPPhi>(Def)) {
if (Phi->getNumOperands() == 1)
Phi->replaceAllUsesWith(Phi->getOperand(0));
return;
}
// Some simplifications can only be applied after unrolling. Perform them
// below.
if (!Plan->isUnrolled())
return;
// VPVectorPointer for part 0 can be replaced by their start pointer.
if (auto *VecPtr = dyn_cast<VPVectorPointerRecipe>(&R)) {
if (VecPtr->isFirstPart()) {
VecPtr->replaceAllUsesWith(VecPtr->getOperand(0));
return;
}
}
// VPScalarIVSteps for part 0 can be replaced by their start value, if only
// the first lane is demanded.
if (auto *Steps = dyn_cast<VPScalarIVStepsRecipe>(Def)) {
if (Steps->isPart0() && 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 (match(Def, m_VPInstruction<VPInstruction::ExtractLastElement>(
m_Broadcast(m_VPValue(A))))) {
Def->replaceAllUsesWith(A);
return;
}
VPInstruction *OpVPI;
if (match(Def, m_VPInstruction<VPInstruction::ExtractLastElement>(
m_VPInstruction(OpVPI))) &&
OpVPI->isVectorToScalar()) {
Def->replaceAllUsesWith(OpVPI);
return;
}
}
void VPlanTransforms::simplifyRecipes(VPlan &Plan) {
ReversePostOrderTraversal<VPBlockDeepTraversalWrapper<VPBlockBase *>> RPOT(
Plan.getEntry());
VPTypeAnalysis TypeInfo(Plan);
for (VPBasicBlock *VPBB : VPBlockUtils::blocksOnly<VPBasicBlock>(RPOT)) {
for (VPRecipeBase &R : make_early_inc_range(*VPBB)) {
simplifyRecipe(R, TypeInfo);
}
}
}
static void narrowToSingleScalarRecipes(VPlan &Plan) {
if (Plan.hasScalarVFOnly())
return;
// Try to narrow wide and replicating recipes to single scalar recipes,
// based on VPlan analysis. Only process blocks in the loop region for now,
// without traversing into nested regions, as recipes in replicate regions
// cannot be converted yet.
for (VPBasicBlock *VPBB : VPBlockUtils::blocksOnly<VPBasicBlock>(
vp_depth_first_shallow(Plan.getVectorLoopRegion()->getEntry()))) {
for (VPRecipeBase &R : make_early_inc_range(reverse(*VPBB))) {
if (!isa<VPWidenRecipe, VPWidenSelectRecipe, VPReplicateRecipe>(&R))
continue;
auto *RepR = dyn_cast<VPReplicateRecipe>(&R);
if (RepR && (RepR->isSingleScalar() || RepR->isPredicated()))
continue;
auto *RepOrWidenR = cast<VPSingleDefRecipe>(&R);
// Skip recipes that aren't single scalars or don't have only their
// scalar results used. In the latter case, we would introduce extra
// broadcasts.
if (!vputils::isSingleScalar(RepOrWidenR) ||
!vputils::onlyScalarValuesUsed(RepOrWidenR))
continue;
auto *Clone = new VPReplicateRecipe(RepOrWidenR->getUnderlyingInstr(),
RepOrWidenR->operands(),
true /*IsSingleScalar*/);
Clone->insertBefore(RepOrWidenR);
RepOrWidenR->replaceAllUsesWith(Clone);
}
}
}
/// 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;
// 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->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;
if (!Plan.getTripCount()->isLiveIn())
return false;
auto *TC = dyn_cast_if_present<ConstantInt>(
Plan.getTripCount()->getUnderlyingValue());
if (!TC || !BestVF.isFixed())
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->getValue(), 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()) {
auto *WideIV = dyn_cast<VPWidenIntOrFpInductionRecipe>(&Phi);
// 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.
if (!WideIV || !WideIV->isCanonical() ||
WideIV->hasMoreThanOneUniqueUser() ||
NewIVTy == WideIV->getScalarType())
continue;
// Currently only handle cases where the single user is a header-mask
// comparison with the backedge-taken-count.
if (!match(*WideIV->user_begin(),
m_ICmp(m_Specific(WideIV),
m_Broadcast(
m_Specific(Plan.getOrCreateBackedgeTakenCount())))))
continue;
// Update IV operands and comparison bound to use new narrower type.
auto *NewStart = Plan.getOrAddLiveIn(ConstantInt::get(NewIVTy, 0));
WideIV->setStartValue(NewStart);
auto *NewStep = Plan.getOrAddLiveIn(ConstantInt::get(NewIVTy, 1));
WideIV->setStepValue(NewStep);
auto *NewBTC = new VPWidenCastRecipe(
Instruction::Trunc, Plan.getOrCreateBackedgeTakenCount(), NewIVTy);
Plan.getVectorPreheader()->appendRecipe(NewBTC);
auto *Cmp = cast<VPInstruction>(*WideIV->user_begin());
Cmp->setOperand(1, 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,
ScalarEvolution &SE) {
if (match(Cond, m_BinaryOr(m_VPValue(), m_VPValue())))
return any_of(Cond->getDefiningRecipe()->operands(), [&Plan, BestVF, BestUF,
&SE](VPValue *C) {
return isConditionTrueViaVFAndUF(C, Plan, BestVF, BestUF, SE);
});
auto *CanIV = Plan.getCanonicalIV();
if (!match(Cond, m_SpecificICmp(CmpInst::ICMP_EQ,
m_Specific(CanIV->getBackedgeValue()),
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(), SE);
if (isa<SCEVCouldNotCompute>(VectorTripCount))
VectorTripCount = vputils::getSCEVExprForVPValue(Plan.getTripCount(), SE);
assert(!isa<SCEVCouldNotCompute>(VectorTripCount) &&
"Trip count SCEV must be computable");
ElementCount NumElements = BestVF.multiplyCoefficientBy(BestUF);
const SCEV *C = SE.getElementCount(VectorTripCount->getType(), NumElements);
return SE.isKnownPredicate(CmpInst::ICMP_EQ, VectorTripCount, C);
}
/// 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;
ScalarEvolution &SE = *PSE.getSE();
if (match(Term, m_BranchOnCount(m_VPValue(), m_VPValue())) ||
match(Term, m_BranchOnCond(
m_Not(m_ActiveLaneMask(m_VPValue(), m_VPValue()))))) {
// Try to simplify the branch condition if TC <= VF * UF when the latch
// terminator is BranchOnCount or BranchOnCond where the input is
// Not(ActiveLaneMask).
const SCEV *TripCount =
vputils::getSCEVExprForVPValue(Plan.getTripCount(), SE);
assert(!isa<SCEVCouldNotCompute>(TripCount) &&
"Trip count SCEV must be computable");
ElementCount NumElements = BestVF.multiplyCoefficientBy(BestUF);
const SCEV *C = SE.getElementCount(TripCount->getType(), NumElements);
if (TripCount->isZero() ||
!SE.isKnownPredicate(CmpInst::ICMP_ULE, TripCount, C))
return false;
} else if (match(Term, m_BranchOnCond(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, SE))
return false;
} else {
return false;
}
// The vector loop region only executes once. If possible, completely remove
// the region, otherwise replace the terminator controlling the latch with
// (BranchOnCond true).
// TODO: VPWidenIntOrFpInductionRecipe is only partially supported; add
// support for other non-canonical widen induction recipes (e.g.,
// VPWidenPointerInductionRecipe).
auto *Header = cast<VPBasicBlock>(VectorRegion->getEntry());
if (all_of(Header->phis(), [](VPRecipeBase &Phi) {
if (auto *R = dyn_cast<VPWidenIntOrFpInductionRecipe>(&Phi))
return R->isCanonical();
return isa<VPCanonicalIVPHIRecipe, VPEVLBasedIVPHIRecipe,
VPFirstOrderRecurrencePHIRecipe, VPPhi>(&Phi);
})) {
for (VPRecipeBase &HeaderR : make_early_inc_range(Header->phis())) {
if (auto *R = dyn_cast<VPWidenIntOrFpInductionRecipe>(&HeaderR)) {
VPBuilder Builder(Plan.getVectorPreheader());
VPValue *StepV = Builder.createNaryOp(VPInstruction::StepVector, {},
R->getScalarType());
HeaderR.getVPSingleValue()->replaceAllUsesWith(StepV);
HeaderR.eraseFromParent();
continue;
}
auto *Phi = cast<VPPhiAccessors>(&HeaderR);
HeaderR.getVPSingleValue()->replaceAllUsesWith(Phi->getIncomingValue(0));
HeaderR.eraseFromParent();
}
VPBlockBase *Preheader = VectorRegion->getSinglePredecessor();
VPBlockBase *Exit = VectorRegion->getSingleSuccessor();
VPBlockUtils::disconnectBlocks(Preheader, VectorRegion);
VPBlockUtils::disconnectBlocks(VectorRegion, Exit);
for (VPBlockBase *B : vp_depth_first_shallow(VectorRegion->getEntry()))
B->setParent(nullptr);
VPBlockUtils::connectBlocks(Preheader, Header);
VPBlockUtils::connectBlocks(ExitingVPBB, Exit);
VPlanTransforms::simplifyRecipes(Plan);
} else {
// The vector region contains header phis for which we cannot remove the
// loop region yet.
auto *BOC = new VPInstruction(VPInstruction::BranchOnCond, {Plan.getTrue()},
Term->getDebugLoc());
ExitingVPBB->appendRecipe(BOC);
}
Term->eraseFromParent();
return true;
}
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 =
simplifyBranchConditionForVFAndUF(Plan, BestVF, BestUF, PSE);
MadeChange |= optimizeVectorInductionWidthForTCAndVFUF(Plan, BestVF, BestUF);
if (MadeChange) {
Plan.setVF(BestVF);
assert(Plan.getUF() == BestUF && "BestUF must match the Plan's UF");
}
// TODO: Further simplifications are possible
// 1. Replace inductions with constants.
// 2. Replace vector loop region with VPBasicBlock.
}
/// Sink users of \p FOR after the recipe defining the previous value \p
/// Previous of the recurrence. \returns true if all users of \p FOR could be
/// re-arranged as needed or false if it is not possible.
static bool
sinkRecurrenceUsersAfterPrevious(VPFirstOrderRecurrencePHIRecipe *FOR,
VPRecipeBase *Previous,
VPDominatorTree &VPDT) {
// Collect recipes that need sinking.
SmallVector<VPRecipeBase *> WorkList;
SmallPtrSet<VPRecipeBase *, 8> Seen;
Seen.insert(Previous);
auto TryToPushSinkCandidate = [&](VPRecipeBase *SinkCandidate) {
// The previous value must not depend on the users of the recurrence phi. In
// that case, FOR is not a fixed order recurrence.
if (SinkCandidate == Previous)
return false;
if (isa<VPHeaderPHIRecipe>(SinkCandidate) ||
!Seen.insert(SinkCandidate).second ||
VPDT.properlyDominates(Previous, SinkCandidate))
return true;
if (SinkCandidate->mayHaveSideEffects())
return false;
WorkList.push_back(SinkCandidate);
return true;
};
// Recursively sink users of FOR after Previous.
WorkList.push_back(FOR);
for (unsigned I = 0; I != WorkList.size(); ++I) {
VPRecipeBase *Current = WorkList[I];
assert(Current->getNumDefinedValues() == 1 &&
"only recipes with a single defined value expected");
for (VPUser *User : Current->getVPSingleValue()->users()) {
if (!TryToPushSinkCandidate(cast<VPRecipeBase>(User)))
return false;
}
}
// Keep recipes to sink ordered by dominance so earlier instructions are
// processed first.
sort(WorkList, [&VPDT](const VPRecipeBase *A, const VPRecipeBase *B) {
return VPDT.properlyDominates(A, B);
});
for (VPRecipeBase *SinkCandidate : WorkList) {
if (SinkCandidate == FOR)
continue;
SinkCandidate->moveAfter(Previous);
Previous = SinkCandidate;
}
return true;
}
/// Try to hoist \p Previous and its operands before all users of \p FOR.
static bool hoistPreviousBeforeFORUsers(VPFirstOrderRecurrencePHIRecipe *FOR,
VPRecipeBase *Previous,
VPDominatorTree &VPDT) {
if (Previous->mayHaveSideEffects() || Previous->mayReadFromMemory())
return false;
// Collect recipes that need hoisting.
SmallVector<VPRecipeBase *> HoistCandidates;
SmallPtrSet<VPRecipeBase *, 8> Visited;
VPRecipeBase *HoistPoint = nullptr;
// Find the closest hoist point by looking at all users of FOR and selecting
// the recipe dominating all other users.
for (VPUser *U : FOR->users()) {
auto *R = cast<VPRecipeBase>(U);
if (!HoistPoint || VPDT.properlyDominates(R, HoistPoint))
HoistPoint = R;
}
assert(all_of(FOR->users(),
[&VPDT, HoistPoint](VPUser *U) {
auto *R = cast<VPRecipeBase>(U);
return HoistPoint == R ||
VPDT.properlyDominates(HoistPoint, R);
}) &&
"HoistPoint must dominate all users of FOR");
auto NeedsHoisting = [HoistPoint, &VPDT,
&Visited](VPValue *HoistCandidateV) -> VPRecipeBase * {
VPRecipeBase *HoistCandidate = HoistCandidateV->getDefiningRecipe();
if (!HoistCandidate)
return nullptr;
VPRegionBlock *EnclosingLoopRegion =
HoistCandidate->getParent()->getEnclosingLoopRegion();
assert((!HoistCandidate->getParent()->getParent() ||
HoistCandidate->getParent()->getParent() == EnclosingLoopRegion) &&
"CFG in VPlan should still be flat, without replicate regions");
// Hoist candidate was already visited, no need to hoist.
if (!Visited.insert(HoistCandidate).second)
return nullptr;
// Candidate is outside loop region or a header phi, dominates FOR users w/o
// hoisting.
if (!EnclosingLoopRegion || isa<VPHeaderPHIRecipe>(HoistCandidate))
return nullptr;
// If we reached a recipe that dominates HoistPoint, we don't need to
// hoist the recipe.
if (VPDT.properlyDominates(HoistCandidate, HoistPoint))
return nullptr;
return HoistCandidate;
};
auto CanHoist = [&](VPRecipeBase *HoistCandidate) {
// Avoid hoisting candidates with side-effects, as we do not yet analyze
// associated dependencies.
return !HoistCandidate->mayHaveSideEffects();
};
if (!NeedsHoisting(Previous->getVPSingleValue()))
return true;
// Recursively try to hoist Previous and its operands before all users of FOR.
HoistCandidates.push_back(Previous);
for (unsigned I = 0; I != HoistCandidates.size(); ++I) {
VPRecipeBase *Current = HoistCandidates[I];
assert(Current->getNumDefinedValues() == 1 &&
"only recipes with a single defined value expected");
if (!CanHoist(Current))
return false;
for (VPValue *Op : Current->operands()) {
// If we reach FOR, it means the original Previous depends on some other
// recurrence that in turn depends on FOR. If that is the case, we would
// also need to hoist recipes involving the other FOR, which may break
// dependencies.
if (Op == FOR)
return false;
if (auto *R = NeedsHoisting(Op))
HoistCandidates.push_back(R);
}
}
// Order recipes to hoist by dominance so earlier instructions are processed
// first.
sort(HoistCandidates, [&VPDT](const VPRecipeBase *A, const VPRecipeBase *B) {
return VPDT.properlyDominates(A, B);
});
for (VPRecipeBase *HoistCandidate : HoistCandidates) {
HoistCandidate->moveBefore(*HoistPoint->getParent(),
HoistPoint->getIterator());
}
return true;
}
bool VPlanTransforms::adjustFixedOrderRecurrences(VPlan &Plan,
VPBuilder &LoopBuilder) {
VPDominatorTree VPDT;
VPDT.recalculate(Plan);
SmallVector<VPFirstOrderRecurrencePHIRecipe *> RecurrencePhis;
for (VPRecipeBase &R :
Plan.getVectorLoopRegion()->getEntry()->getEntryBasicBlock()->phis())
if (auto *FOR = dyn_cast<VPFirstOrderRecurrencePHIRecipe>(&R))
RecurrencePhis.push_back(FOR);
for (VPFirstOrderRecurrencePHIRecipe *FOR : RecurrencePhis) {
SmallPtrSet<VPFirstOrderRecurrencePHIRecipe *, 4> SeenPhis;
VPRecipeBase *Previous = FOR->getBackedgeValue()->getDefiningRecipe();
// Fixed-order recurrences do not contain cycles, so this loop is guaranteed
// to terminate.
while (auto *PrevPhi =
dyn_cast_or_null<VPFirstOrderRecurrencePHIRecipe>(Previous)) {
assert(PrevPhi->getParent() == FOR->getParent());
assert(SeenPhis.insert(PrevPhi).second);
Previous = PrevPhi->getBackedgeValue()->getDefiningRecipe();
}
if (!sinkRecurrenceUsersAfterPrevious(FOR, Previous, VPDT) &&
!hoistPreviousBeforeFORUsers(FOR, Previous, VPDT))
return false;
// Introduce a recipe to combine the incoming and previous values of a
// fixed-order recurrence.
VPBasicBlock *InsertBlock = Previous->getParent();
if (isa<VPHeaderPHIRecipe>(Previous))
LoopBuilder.setInsertPoint(InsertBlock, InsertBlock->getFirstNonPhi());
else
LoopBuilder.setInsertPoint(InsertBlock,
std::next(Previous->getIterator()));
auto *RecurSplice =
LoopBuilder.createNaryOp(VPInstruction::FirstOrderRecurrenceSplice,
{FOR, FOR->getBackedgeValue()});
FOR->replaceAllUsesWith(RecurSplice);
// Set the first operand of RecurSplice to FOR again, after replacing
// all users.
RecurSplice->setOperand(0, FOR);
}
return true;
}
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();
}
}
}
/// Move loop-invariant recipes out of the vector loop region in \p Plan.
static void licm(VPlan &Plan) {
VPBasicBlock *Preheader = Plan.getVectorPreheader();
// Return true if we do not know how to (mechanically) hoist a given recipe
// out of a loop region. Does not address legality concerns such as aliasing
// or speculation safety.
auto CannotHoistRecipe = [](VPRecipeBase &R) {
// Allocas cannot be hoisted.
auto *RepR = dyn_cast<VPReplicateRecipe>(&R);
return RepR && RepR->getOpcode() == Instruction::Alloca;
};
// 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.
VPRegionBlock *LoopRegion = Plan.getVectorLoopRegion();
for (VPBasicBlock *VPBB : VPBlockUtils::blocksOnly<VPBasicBlock>(
vp_depth_first_shallow(LoopRegion->getEntry()))) {
for (VPRecipeBase &R : make_early_inc_range(*VPBB)) {
if (CannotHoistRecipe(R))
continue;
// TODO: Relax checks in the future, e.g. we could also hoist reads, if
// their memory location is not modified in the vector loop.
if (R.mayHaveSideEffects() || R.mayReadFromMemory() || R.isPhi() ||
any_of(R.operands(), [](VPValue *Op) {
return !Op->isDefinedOutsideLoopRegions();
}))
continue;
R.moveBefore(*Preheader, Preheader->end());
}
}
}
void VPlanTransforms::truncateToMinimalBitwidths(
VPlan &Plan, const MapVector<Instruction *, uint64_t> &MinBWs) {
// 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;
VPTypeAnalysis TypeInfo(Plan);
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,
VPWidenSelectRecipe, 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 = TypeInfo.inferScalarType(ResultVPV);
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();
if (OldResSizeInBits != NewResSizeInBits &&
!match(&R, m_ICmp(m_VPValue(), m_VPValue()))) {
// Extend result to original width.
auto *Ext =
new VPWidenCastRecipe(Instruction::ZExt, ResultVPV, OldResTy);
Ext->insertAfter(&R);
ResultVPV->replaceAllUsesWith(Ext);
Ext->setOperand(0, ResultVPV);
assert(OldResSizeInBits > NewResSizeInBits && "Nothing to shrink?");
} else {
assert(match(&R, m_ICmp(m_VPValue(), m_VPValue())) &&
"Only ICmps should not need extending the result.");
}
assert(!isa<VPWidenStoreRecipe>(&R) && "stores cannot be narrowed");
if (isa<VPWidenLoadRecipe, VPWidenIntrinsicRecipe>(&R))
continue;
// Shrink operands by introducing truncates as needed.
unsigned StartIdx = isa<VPWidenSelectRecipe>(&R) ? 1 : 0;
for (unsigned Idx = StartIdx; Idx != R.getNumOperands(); ++Idx) {
auto *Op = R.getOperand(Idx);
unsigned OpSizeInBits =
TypeInfo.inferScalarType(Op)->getScalarSizeInBits();
if (OpSizeInBits == NewResSizeInBits)
continue;
assert(OpSizeInBits > NewResSizeInBits && "nothing to truncate");
auto [ProcessedIter, IterIsEmpty] = ProcessedTruncs.try_emplace(Op);
VPWidenCastRecipe *NewOp =
IterIsEmpty
? new VPWidenCastRecipe(Instruction::Trunc, Op, NewResTy)
: ProcessedIter->second;
R.setOperand(Idx, NewOp);
if (!IterIsEmpty)
continue;
ProcessedIter->second = NewOp;
if (!Op->isLiveIn()) {
NewOp->insertBefore(&R);
} else {
PH->appendRecipe(NewOp);
}
}
}
}
}
void VPlanTransforms::removeBranchOnConst(VPlan &Plan) {
for (VPBasicBlock *VPBB : VPBlockUtils::blocksOnly<VPBasicBlock>(
vp_depth_first_shallow(Plan.getEntry()))) {
VPValue *Cond;
if (VPBB->getNumSuccessors() != 2 || VPBB == Plan.getEntry() ||
!match(&VPBB->back(), m_BranchOnCond(m_VPValue(Cond))))
continue;
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 RemoveSucc are removed from
// these recipes.
for (VPRecipeBase &R : RemovedSucc->phis())
cast<VPPhiAccessors>(&R)->removeIncomingValueFor(VPBB);
// Disconnect blocks and remove the terminator. RemovedSucc will be deleted
// automatically on VPlan destruction if it becomes unreachable.
VPBlockUtils::disconnectBlocks(VPBB, RemovedSucc);
VPBB->back().eraseFromParent();
}
}
void VPlanTransforms::optimize(VPlan &Plan) {
runPass(removeRedundantCanonicalIVs, Plan);
runPass(removeRedundantInductionCasts, Plan);
runPass(simplifyRecipes, Plan);
runPass(simplifyBlends, Plan);
runPass(removeDeadRecipes, Plan);
runPass(narrowToSingleScalarRecipes, Plan);
runPass(legalizeAndOptimizeInductions, Plan);
runPass(removeRedundantExpandSCEVRecipes, Plan);
runPass(simplifyRecipes, Plan);
runPass(removeBranchOnConst, Plan);
runPass(removeDeadRecipes, Plan);
runPass(createAndOptimizeReplicateRegions, Plan);
runPass(mergeBlocksIntoPredecessors, Plan);
runPass(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 uses the following definitions:
//
// %TripCount = DataWithControlFlowWithoutRuntimeCheck ?
// calculate-trip-count-minus-VF (original TC) : original TC
// %IncrementValue = DataWithControlFlowWithoutRuntimeCheck ?
// CanonicalIVPhi : CanonicalIVIncrement
// %StartV is the canonical induction start value.
//
// The function adds the following recipes:
//
// vector.ph:
// %TripCount = calculate-trip-count-minus-VF (original TC)
// [if DataWithControlFlowWithoutRuntimeCheck]
// %EntryInc = canonical-iv-increment-for-part %StartV
// %EntryALM = active-lane-mask %EntryInc, %TripCount
//
// vector.body:
// ...
// %P = active-lane-mask-phi [ %EntryALM, %vector.ph ], [ %ALM, %vector.body ]
// ...
// %InLoopInc = canonical-iv-increment-for-part %IncrementValue
// %ALM = active-lane-mask %InLoopInc, TripCount
// %Negated = Not %ALM
// branch-on-cond %Negated
//
static VPActiveLaneMaskPHIRecipe *addVPLaneMaskPhiAndUpdateExitBranch(
VPlan &Plan, bool DataAndControlFlowWithoutRuntimeCheck) {
VPRegionBlock *TopRegion = Plan.getVectorLoopRegion();
VPBasicBlock *EB = TopRegion->getExitingBasicBlock();
auto *CanonicalIVPHI = Plan.getCanonicalIV();
VPValue *StartV = CanonicalIVPHI->getStartValue();
auto *CanonicalIVIncrement =
cast<VPInstruction>(CanonicalIVPHI->getBackedgeValue());
// TODO: Check if dropping the flags is needed if
// !DataAndControlFlowWithoutRuntimeCheck.
CanonicalIVIncrement->dropPoisonGeneratingFlags();
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 *TripCount, *IncrementValue;
if (!DataAndControlFlowWithoutRuntimeCheck) {
// When the loop is guarded by a runtime overflow check for the loop
// induction variable increment by VF, we can increment the value before
// the get.active.lane mask and use the unmodified tripcount.
IncrementValue = CanonicalIVIncrement;
TripCount = TC;
} else {
// When avoiding a runtime check, the active.lane.mask inside the loop
// uses a modified trip count and the induction variable increment is
// done after the active.lane.mask intrinsic is called.
IncrementValue = CanonicalIVPHI;
TripCount = Builder.createNaryOp(VPInstruction::CalculateTripCountMinusVF,
{TC}, DL);
}
auto *EntryIncrement = Builder.createOverflowingOp(
VPInstruction::CanonicalIVIncrementForPart, {StartV}, {false, false}, DL,
"index.part.next");
// Create the active lane mask instruction in the VPlan preheader.
auto *EntryALM =
Builder.createNaryOp(VPInstruction::ActiveLaneMask, {EntryIncrement, TC},
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());
LaneMaskPhi->insertAfter(CanonicalIVPHI);
// 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,
{IncrementValue}, {false, false}, DL);
auto *ALM = Builder.createNaryOp(VPInstruction::ActiveLaneMask,
{InLoopIncrement, TripCount}, DL,
"active.lane.mask.next");
LaneMaskPhi->addOperand(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;
}
/// Collect the header mask with the pattern:
/// (ICMP_ULE, WideCanonicalIV, backedge-taken-count)
/// TODO: Introduce explicit recipe for header-mask instead of searching
/// for the header-mask pattern manually.
static VPSingleDefRecipe *findHeaderMask(VPlan &Plan) {
SmallVector<VPValue *> WideCanonicalIVs;
auto *FoundWidenCanonicalIVUser =
find_if(Plan.getCanonicalIV()->users(),
[](VPUser *U) { return isa<VPWidenCanonicalIVRecipe>(U); });
assert(count_if(Plan.getCanonicalIV()->users(),
[](VPUser *U) { return isa<VPWidenCanonicalIVRecipe>(U); }) <=
1 &&
"Must have at most one VPWideCanonicalIVRecipe");
if (FoundWidenCanonicalIVUser != Plan.getCanonicalIV()->users().end()) {
auto *WideCanonicalIV =
cast<VPWidenCanonicalIVRecipe>(*FoundWidenCanonicalIVUser);
WideCanonicalIVs.push_back(WideCanonicalIV);
}
// Also include VPWidenIntOrFpInductionRecipes that represent a widened
// version of the canonical induction.
VPBasicBlock *HeaderVPBB = Plan.getVectorLoopRegion()->getEntryBasicBlock();
for (VPRecipeBase &Phi : HeaderVPBB->phis()) {
auto *WidenOriginalIV = dyn_cast<VPWidenIntOrFpInductionRecipe>(&Phi);
if (WidenOriginalIV && WidenOriginalIV->isCanonical())
WideCanonicalIVs.push_back(WidenOriginalIV);
}
// Walk users of wide canonical IVs and find the single compare of the form
// (ICMP_ULE, WideCanonicalIV, backedge-taken-count).
VPSingleDefRecipe *HeaderMask = nullptr;
for (auto *Wide : WideCanonicalIVs) {
for (VPUser *U : SmallVector<VPUser *>(Wide->users())) {
auto *VPI = dyn_cast<VPInstruction>(U);
if (!VPI || !vputils::isHeaderMask(VPI, Plan))
continue;
assert(VPI->getOperand(0) == Wide &&
"WidenCanonicalIV must be the first operand of the compare");
assert(!HeaderMask && "Multiple header masks found?");
HeaderMask = VPI;
}
}
return HeaderMask;
}
void VPlanTransforms::addActiveLaneMask(
VPlan &Plan, bool UseActiveLaneMaskForControlFlow,
bool DataAndControlFlowWithoutRuntimeCheck) {
assert((!DataAndControlFlowWithoutRuntimeCheck ||
UseActiveLaneMaskForControlFlow) &&
"DataAndControlFlowWithoutRuntimeCheck implies "
"UseActiveLaneMaskForControlFlow");
auto *FoundWidenCanonicalIVUser =
find_if(Plan.getCanonicalIV()->users(),
[](VPUser *U) { return isa<VPWidenCanonicalIVRecipe>(U); });
assert(FoundWidenCanonicalIVUser &&
"Must have widened canonical IV when tail folding!");
VPSingleDefRecipe *HeaderMask = findHeaderMask(Plan);
auto *WideCanonicalIV =
cast<VPWidenCanonicalIVRecipe>(*FoundWidenCanonicalIVUser);
VPSingleDefRecipe *LaneMask;
if (UseActiveLaneMaskForControlFlow) {
LaneMask = addVPLaneMaskPhiAndUpdateExitBranch(
Plan, DataAndControlFlowWithoutRuntimeCheck);
} else {
VPBuilder B = VPBuilder::getToInsertAfter(WideCanonicalIV);
LaneMask = B.createNaryOp(VPInstruction::ActiveLaneMask,
{WideCanonicalIV, Plan.getTripCount()}, 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();
}
/// 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 TypeInfo VPlan-based type analysis.
/// \p AllOneMask The vector mask parameter of vector-predication intrinsics.
/// \p EVL The explicit vector length parameter of vector-predication
/// intrinsics.
static VPRecipeBase *optimizeMaskToEVL(VPValue *HeaderMask,
VPRecipeBase &CurRecipe,
VPTypeAnalysis &TypeInfo,
VPValue &AllOneMask, VPValue &EVL) {
// FIXME: Don't transform recipes to EVL recipes if they're not masked by the
// header mask.
auto GetNewMask = [&](VPValue *OrigMask) -> VPValue * {
assert(OrigMask && "Unmasked recipe when folding tail");
// HeaderMask will be handled using EVL.
VPValue *Mask;
if (match(OrigMask, m_LogicalAnd(m_Specific(HeaderMask), m_VPValue(Mask))))
return Mask;
return HeaderMask == OrigMask ? nullptr : OrigMask;
};
/// Adjust any end pointers so that they point to the end of EVL lanes not VF.
auto GetNewAddr = [&CurRecipe, &EVL](VPValue *Addr) -> VPValue * {
auto *EndPtr = dyn_cast<VPVectorEndPointerRecipe>(Addr);
if (!EndPtr)
return Addr;
assert(EndPtr->getOperand(1) == &EndPtr->getParent()->getPlan()->getVF() &&
"VPVectorEndPointerRecipe with non-VF VF operand?");
assert(
all_of(EndPtr->users(),
[](VPUser *U) {
return cast<VPWidenMemoryRecipe>(U)->isReverse();
}) &&
"VPVectorEndPointRecipe not used by reversed widened memory recipe?");
VPVectorEndPointerRecipe *EVLAddr = EndPtr->clone();
EVLAddr->insertBefore(&CurRecipe);
EVLAddr->setOperand(1, &EVL);
return EVLAddr;
};
return TypeSwitch<VPRecipeBase *, VPRecipeBase *>(&CurRecipe)
.Case<VPWidenLoadRecipe>([&](VPWidenLoadRecipe *L) {
VPValue *NewMask = GetNewMask(L->getMask());
VPValue *NewAddr = GetNewAddr(L->getAddr());
return new VPWidenLoadEVLRecipe(*L, NewAddr, EVL, NewMask);
})
.Case<VPWidenStoreRecipe>([&](VPWidenStoreRecipe *S) {
VPValue *NewMask = GetNewMask(S->getMask());
VPValue *NewAddr = GetNewAddr(S->getAddr());
return new VPWidenStoreEVLRecipe(*S, NewAddr, EVL, NewMask);
})
.Case<VPReductionRecipe>([&](VPReductionRecipe *Red) {
VPValue *NewMask = GetNewMask(Red->getCondOp());
return new VPReductionEVLRecipe(*Red, EVL, NewMask);
})
.Case<VPInstruction>([&](VPInstruction *VPI) -> VPRecipeBase * {
VPValue *LHS, *RHS;
// Transform select with a header mask condition
// select(header_mask, LHS, RHS)
// into vector predication merge.
// vp.merge(all-true, LHS, RHS, EVL)
if (!match(VPI, m_Select(m_Specific(HeaderMask), m_VPValue(LHS),
m_VPValue(RHS))))
return nullptr;
// Use all true as the condition because this transformation is
// limited to selects whose condition is a header mask.
return new VPWidenIntrinsicRecipe(
Intrinsic::vp_merge, {&AllOneMask, LHS, RHS, &EVL},
TypeInfo.inferScalarType(LHS), VPI->getDebugLoc());
})
.Default([&](VPRecipeBase *R) { return nullptr; });
}
/// Replace recipes with their EVL variants.
static void transformRecipestoEVLRecipes(VPlan &Plan, VPValue &EVL) {
VPTypeAnalysis TypeInfo(Plan);
VPValue *AllOneMask = Plan.getTrue();
VPRegionBlock *LoopRegion = Plan.getVectorLoopRegion();
VPBasicBlock *Header = LoopRegion->getEntryBasicBlock();
assert(all_of(Plan.getVF().users(),
IsaPred<VPVectorEndPointerRecipe, VPScalarIVStepsRecipe,
VPWidenIntOrFpInductionRecipe>) &&
"User of VF that we can't transform to EVL.");
Plan.getVF().replaceUsesWithIf(&EVL, [](VPUser &U, unsigned Idx) {
return isa<VPWidenIntOrFpInductionRecipe, VPScalarIVStepsRecipe>(U);
});
assert(all_of(Plan.getVFxUF().users(),
[&Plan](VPUser *U) {
return match(U, m_c_Add(m_Specific(Plan.getCanonicalIV()),
m_Specific(&Plan.getVFxUF()))) ||
isa<VPWidenPointerInductionRecipe>(U);
}) &&
"Only users of VFxUF should be VPWidenPointerInductionRecipe and the "
"increment of the canonical induction.");
Plan.getVFxUF().replaceUsesWithIf(&EVL, [](VPUser &U, unsigned Idx) {
// Only replace uses in VPWidenPointerInductionRecipe; The increment of the
// canonical induction must not be updated.
return isa<VPWidenPointerInductionRecipe>(U);
});
// Defer erasing recipes till the end so that we don't invalidate the
// VPTypeAnalysis cache.
SmallVector<VPRecipeBase *> ToErase;
// 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()),
TypeInfo.inferScalarType(MaxEVL), DebugLoc());
Builder.setInsertPoint(Header, Header->getFirstNonPhi());
VPValue *PrevEVL =
Builder.createScalarPhi({MaxEVL, &EVL}, DebugLoc(), "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, AllOneMask, PrevEVL, &EVL},
TypeInfo.inferScalarType(R.getVPSingleValue()), R.getDebugLoc());
VPSplice->insertBefore(&R);
R.getVPSingleValue()->replaceAllUsesWith(VPSplice);
ToErase.push_back(&R);
}
}
}
VPValue *HeaderMask = findHeaderMask(Plan);
if (!HeaderMask)
return;
// 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 = TypeInfo.inferScalarType(&EVL);
VPValue *EVLMask = Builder.createICmp(
CmpInst::ICMP_ULT,
Builder.createNaryOp(VPInstruction::StepVector, {}, EVLType), &EVL);
HeaderMask->replaceAllUsesWith(EVLMask);
ToErase.push_back(HeaderMask->getDefiningRecipe());
// Try to optimize header mask recipes away to their EVL variants.
// TODO: Split optimizeMaskToEVL out and move into
// VPlanTransforms::optimize. transformRecipestoEVLRecipes should be run in
// tryToBuildVPlanWithVPRecipes beforehand.
for (VPUser *U : collectUsersRecursively(EVLMask)) {
auto *CurRecipe = cast<VPRecipeBase>(U);
VPRecipeBase *EVLRecipe =
optimizeMaskToEVL(EVLMask, *CurRecipe, TypeInfo, *AllOneMask, EVL);
if (!EVLRecipe)
continue;
[[maybe_unused]] unsigned NumDefVal = EVLRecipe->getNumDefinedValues();
assert(NumDefVal == CurRecipe->getNumDefinedValues() &&
"New recipe must define the same number of values as the "
"original.");
assert(NumDefVal <= 1 &&
"Only supports recipes with a single definition or without users.");
EVLRecipe->insertBefore(CurRecipe);
if (isa<VPSingleDefRecipe, VPWidenLoadEVLRecipe>(EVLRecipe)) {
VPValue *CurVPV = CurRecipe->getVPSingleValue();
CurVPV->replaceAllUsesWith(EVLRecipe->getVPSingleValue());
}
ToErase.push_back(CurRecipe);
}
// Remove dead EVL mask.
if (EVLMask->getNumUsers() == 0)
ToErase.push_back(EVLMask->getDefiningRecipe());
for (VPRecipeBase *R : reverse(ToErase)) {
SmallVector<VPValue *> PossiblyDead(R->operands());
R->eraseFromParent();
for (VPValue *Op : PossiblyDead)
recursivelyDeleteDeadRecipes(Op);
}
}
/// Add a VPEVLBasedIVPHIRecipe and related recipes to \p Plan and
/// replaces all uses except the canonical IV increment of
/// VPCanonicalIVPHIRecipe with a VPEVLBasedIVPHIRecipe. VPCanonicalIVPHIRecipe
/// is used only for loop iterations counting after this transformation.
///
/// The function uses the following definitions:
/// %StartV is the canonical induction start value.
///
/// The function adds the following recipes:
///
/// vector.ph:
/// ...
///
/// vector.body:
/// ...
/// %EVLPhi = EXPLICIT-VECTOR-LENGTH-BASED-IV-PHI [ %StartV, %vector.ph ],
/// [ %NextEVLIV, %vector.body ]
/// %AVL = phi [ trip-count, %vector.ph ], [ %NextAVL, %vector.body ]
/// %VPEVL = EXPLICIT-VECTOR-LENGTH %AVL
/// ...
/// %OpEVL = cast i32 %VPEVL to IVSize
/// %NextEVLIV = add IVSize %OpEVL, %EVLPhi
/// %NextAVL = sub IVSize nuw %AVL, %OpEVL
/// ...
///
/// If MaxSafeElements is provided, the function adds the following recipes:
/// vector.ph:
/// ...
///
/// vector.body:
/// ...
/// %EVLPhi = EXPLICIT-VECTOR-LENGTH-BASED-IV-PHI [ %StartV, %vector.ph ],
/// [ %NextEVLIV, %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
/// %NextEVLIV = add IVSize %OpEVL, %EVLPhi
/// %NextAVL = sub IVSize nuw %AVL, %OpEVL
/// ...
///
void VPlanTransforms::addExplicitVectorLength(
VPlan &Plan, const std::optional<unsigned> &MaxSafeElements) {
VPBasicBlock *Header = Plan.getVectorLoopRegion()->getEntryBasicBlock();
auto *CanonicalIVPHI = Plan.getCanonicalIV();
auto *CanIVTy = CanonicalIVPHI->getScalarType();
VPValue *StartV = CanonicalIVPHI->getStartValue();
// Create the ExplicitVectorLengthPhi recipe in the main loop.
auto *EVLPhi = new VPEVLBasedIVPHIRecipe(StartV, DebugLoc());
EVLPhi->insertAfter(CanonicalIVPHI);
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.getOrAddLiveIn(ConstantInt::get(CanIVTy, *MaxSafeElements));
VPValue *Cmp = Builder.createICmp(ICmpInst::ICMP_ULT, AVL, AVLSafe);
AVL = Builder.createSelect(Cmp, AVL, AVLSafe, DebugLoc(), "safe_avl");
}
auto *VPEVL = Builder.createNaryOp(VPInstruction::ExplicitVectorLength, AVL,
DebugLoc());
auto *CanonicalIVIncrement =
cast<VPInstruction>(CanonicalIVPHI->getBackedgeValue());
Builder.setInsertPoint(CanonicalIVIncrement);
VPValue *OpVPEVL = VPEVL;
auto *I32Ty = Type::getInt32Ty(Plan.getContext());
OpVPEVL = Builder.createScalarZExtOrTrunc(
OpVPEVL, CanIVTy, I32Ty, CanonicalIVIncrement->getDebugLoc());
auto *NextEVLIV = Builder.createOverflowingOp(
Instruction::Add, {OpVPEVL, EVLPhi},
{CanonicalIVIncrement->hasNoUnsignedWrap(),
CanonicalIVIncrement->hasNoSignedWrap()},
CanonicalIVIncrement->getDebugLoc(), "index.evl.next");
EVLPhi->addOperand(NextEVLIV);
VPValue *NextAVL = Builder.createOverflowingOp(
Instruction::Sub, {AVLPhi, OpVPEVL}, {/*hasNUW=*/true, /*hasNSW=*/false},
DebugLoc::getCompilerGenerated(), "avl.next");
AVLPhi->addOperand(NextAVL);
transformRecipestoEVLRecipes(Plan, *VPEVL);
// Replace all uses of VPCanonicalIVPHIRecipe by
// VPEVLBasedIVPHIRecipe except for the canonical IV increment.
CanonicalIVPHI->replaceAllUsesWith(EVLPhi);
CanonicalIVIncrement->setOperand(0, CanonicalIVPHI);
// TODO: support unroll factor > 1.
Plan.setUF(1);
}
void VPlanTransforms::canonicalizeEVLLoops(VPlan &Plan) {
// Find EVL loop entries by locating VPEVLBasedIVPHIRecipe.
// There should be only one EVL PHI in the entire plan.
VPEVLBasedIVPHIRecipe *EVLPhi = nullptr;
for (VPBasicBlock *VPBB : VPBlockUtils::blocksOnly<VPBasicBlock>(
vp_depth_first_shallow(Plan.getEntry())))
for (VPRecipeBase &R : VPBB->phis())
if (auto *PhiR = dyn_cast<VPEVLBasedIVPHIRecipe>(&R)) {
assert(!EVLPhi && "Found multiple EVL PHIs. Only one expected");
EVLPhi = PhiR;
}
// Early return if no EVL PHI is found.
if (!EVLPhi)
return;
VPBasicBlock *HeaderVPBB = EVLPhi->getParent();
VPValue *EVLIncrement = EVLPhi->getBackedgeValue();
// Convert EVLPhi to concrete recipe.
auto *ScalarR =
VPBuilder(EVLPhi).createScalarPhi({EVLPhi->getStartValue(), EVLIncrement},
EVLPhi->getDebugLoc(), "evl.based.iv");
EVLPhi->replaceAllUsesWith(ScalarR);
EVLPhi->eraseFromParent();
// Replace CanonicalIVInc with EVL-PHI increment.
auto *CanonicalIV = cast<VPPhi>(&*HeaderVPBB->begin());
VPValue *Backedge = CanonicalIV->getIncomingValue(1);
assert(match(Backedge, m_c_Add(m_Specific(CanonicalIV),
m_Specific(&Plan.getVFxUF()))) &&
"Unexpected canonical iv");
Backedge->replaceAllUsesWith(EVLIncrement);
// Remove unused phi and increment.
VPRecipeBase *CanonicalIVIncrement = Backedge->getDefiningRecipe();
CanonicalIVIncrement->eraseFromParent();
CanonicalIV->eraseFromParent();
// Replace the use of VectorTripCount in the latch-exiting block.
// Before: (branch-on-count EVLIVInc, VectorTripCount)
// After: (branch-on-count EVLIVInc, TripCount)
VPBasicBlock *LatchExiting =
HeaderVPBB->getPredecessors()[1]->getEntryBasicBlock();
auto *LatchExitingBr = cast<VPInstruction>(LatchExiting->getTerminator());
// Skip single-iteration loop region
if (match(LatchExitingBr, m_BranchOnCond(m_True())))
return;
assert(LatchExitingBr &&
match(LatchExitingBr,
m_BranchOnCount(m_VPValue(EVLIncrement),
m_Specific(&Plan.getVectorTripCount()))) &&
"Unexpected terminator in EVL loop");
LatchExitingBr->setOperand(1, Plan.getTripCount());
}
void VPlanTransforms::dropPoisonGeneratingRecipes(
VPlan &Plan,
const std::function<bool(BasicBlock *)> &BlockNeedsPredication) {
// 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.createOverflowingOp(
Instruction::Add, {A, B}, {false, false},
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);
}
});
// 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_deep(Plan.getEntry());
for (VPBasicBlock *VPBB : VPBlockUtils::blocksOnly<VPBasicBlock>(Iter)) {
for (VPRecipeBase &Recipe : *VPBB) {
if (auto *WidenRec = dyn_cast<VPWidenMemoryRecipe>(&Recipe)) {
Instruction &UnderlyingInstr = WidenRec->getIngredient();
VPRecipeBase *AddrDef = WidenRec->getAddr()->getDefiningRecipe();
if (AddrDef && WidenRec->isConsecutive() &&
BlockNeedsPredication(UnderlyingInstr.getParent()))
CollectPoisonGeneratingInstrsInBackwardSlice(AddrDef);
} else if (auto *InterleaveRec = dyn_cast<VPInterleaveRecipe>(&Recipe)) {
VPRecipeBase *AddrDef = InterleaveRec->getAddr()->getDefiningRecipe();
if (AddrDef) {
// Check if any member of the interleave group needs predication.
const InterleaveGroup<Instruction> *InterGroup =
InterleaveRec->getInterleaveGroup();
bool NeedPredication = false;
for (int I = 0, NumMembers = InterGroup->getNumMembers();
I < NumMembers; ++I) {
Instruction *Member = InterGroup->getMember(I);
if (Member)
NeedPredication |= BlockNeedsPredication(Member->getParent());
}
if (NeedPredication)
CollectPoisonGeneratingInstrsInBackwardSlice(AddrDef);
}
}
}
}
}
void VPlanTransforms::createInterleaveGroups(
VPlan &Plan,
const SmallPtrSetImpl<const InterleaveGroup<Instruction> *>
&InterleaveGroups,
VPRecipeBuilder &RecipeBuilder, const bool &ScalarEpilogueAllowed) {
if (InterleaveGroups.empty())
return;
// 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;
VPDT.recalculate(Plan);
for (const auto *IG : InterleaveGroups) {
SmallVector<VPValue *, 4> StoredValues;
for (unsigned i = 0; i < IG->getFactor(); ++i)
if (auto *SI = dyn_cast_or_null<StoreInst>(IG->getMember(i))) {
auto *StoreR = cast<VPWidenStoreRecipe>(RecipeBuilder.getRecipe(SI));
StoredValues.push_back(StoreR->getStoredValue());
}
bool NeedsMaskForGaps =
(IG->requiresScalarEpilogue() && !ScalarEpilogueAllowed) ||
(!StoredValues.empty() && !IG->isFull());
Instruction *IRInsertPos = IG->getInsertPos();
auto *InsertPos =
cast<VPWidenMemoryRecipe>(RecipeBuilder.getRecipe(IRInsertPos));
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.
auto *Start =
cast<VPWidenMemoryRecipe>(RecipeBuilder.getRecipe(IG->getMember(0)));
VPValue *Addr = Start->getAddr();
VPRecipeBase *AddrDef = Addr->getDefiningRecipe();
if (AddrDef && !VPDT.properlyDominates(AddrDef, InsertPos)) {
// 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.getOrAddLiveIn(ConstantInt::get(Plan.getContext(), -Offset));
VPBuilder B(InsertPos);
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, InsertPos->getDebugLoc());
ReversePtr->insertBefore(InsertPos);
Addr = ReversePtr;
}
auto *VPIG = new VPInterleaveRecipe(IG, Addr, StoredValues,
InsertPos->getMask(), NeedsMaskForGaps, InsertPos->getDebugLoc());
VPIG->insertBefore(InsertPos);
unsigned J = 0;
for (unsigned i = 0; i < IG->getFactor(); ++i)
if (Instruction *Member = IG->getMember(i)) {
VPRecipeBase *MemberR = RecipeBuilder.getRecipe(Member);
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,
VPTypeAnalysis &TypeInfo) {
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 = TypeInfo.inferScalarType(WidenIVR);
const InductionDescriptor &ID = WidenIVR->getInductionDescriptor();
Instruction::BinaryOps AddOp;
Instruction::BinaryOps MulOp;
// FIXME: The newly created binary instructions should contain nsw/nuw
// flags, which can be found from the original scalar operations.
VPIRFlags Flags;
if (ID.getKind() == InductionDescriptor::IK_IntInduction) {
AddOp = Instruction::Add;
MulOp = Instruction::Mul;
} else {
AddOp = ID.getInductionOpcode();
MulOp = Instruction::FMul;
Flags = ID.getInductionBinOp()->getFastMathFlags();
}
// If the phi is truncated, truncate the start and step values.
VPBuilder Builder(Plan->getVectorPreheader());
Type *StepTy = TypeInfo.inferScalarType(Step);
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, {}, "induction");
// Create the widened phi of the vector IV.
auto *WidePHI = new VPWidenPHIRecipe(WidenIVR->getPHINode(), nullptr,
WidenIVR->getDebugLoc(), "vec.ind");
WidePHI->addOperand(Init);
WidePHI->insertBefore(WidenIVR);
// 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 {
if (VPRecipeBase *R = VF->getDefiningRecipe())
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,
TypeInfo.inferScalarType(VF), 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->addOperand(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,
VPTypeAnalysis &TypeInfo) {
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(TypeInfo.inferScalarType(R)->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 = TypeInfo.inferScalarType(Step);
VPValue *Offset = Builder.createNaryOp(VPInstruction::StepVector, {}, StepTy);
Offset = Builder.createNaryOp(Instruction::Mul, {Offset, Step});
VPValue *PtrAdd = Builder.createNaryOp(
VPInstruction::WidePtrAdd, {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, TypeInfo.inferScalarType(VF),
DL);
VPValue *Inc = Builder.createNaryOp(Instruction::Mul, {Step, VF});
VPValue *InductionGEP =
Builder.createPtrAdd(ScalarPtrPhi, Inc, DL, "ptr.ind");
ScalarPtrPhi->addOperand(InductionGEP);
}
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::convertToConcreteRecipes(VPlan &Plan) {
VPTypeAnalysis TypeInfo(Plan);
SmallVector<VPRecipeBase *> ToRemove;
for (VPBasicBlock *VPBB : VPBlockUtils::blocksOnly<VPBasicBlock>(
vp_depth_first_deep(Plan.getEntry()))) {
for (VPRecipeBase &R : make_early_inc_range(*VPBB)) {
if (auto *WidenIVR = dyn_cast<VPWidenIntOrFpInductionRecipe>(&R)) {
expandVPWidenIntOrFpInduction(WidenIVR, TypeInfo);
ToRemove.push_back(WidenIVR);
continue;
}
if (auto *WidenIVR = dyn_cast<VPWidenPointerInductionRecipe>(&R)) {
expandVPWidenPointerInduction(WidenIVR, TypeInfo);
ToRemove.push_back(WidenIVR);
continue;
}
// Expand VPBlendRecipe into VPInstruction::Select.
VPBuilder Builder(&R);
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->replaceAllUsesWith(Select);
ToRemove.push_back(Blend);
}
if (auto *Expr = dyn_cast<VPExpressionRecipe>(&R)) {
Expr->decompose();
ToRemove.push_back(Expr);
}
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 = TypeInfo.inferScalarType(VPI);
if (TypeInfo.inferScalarType(VectorStep) != IVTy) {
Instruction::CastOps CastOp = IVTy->isFloatingPointTy()
? Instruction::UIToFP
: Instruction::Trunc;
VectorStep = Builder.createWidenCast(CastOp, VectorStep, IVTy);
}
[[maybe_unused]] auto *ConstStep =
ScalarStep->isLiveIn()
? dyn_cast<ConstantInt>(ScalarStep->getLiveInIRValue())
: nullptr;
assert(!ConstStep || ConstStep->getValue() != 1);
(void)ConstStep;
if (TypeInfo.inferScalarType(ScalarStep) != IVTy) {
ScalarStep =
Builder.createWidenCast(Instruction::Trunc, ScalarStep, IVTy);
}
VPIRFlags Flags;
if (IVTy->isFloatingPointTy())
Flags = {VPI->getFastMathFlags()};
unsigned MulOpc =
IVTy->isFloatingPointTy() ? Instruction::FMul : Instruction::Mul;
VPInstruction *Mul = Builder.createNaryOp(
MulOpc, {VectorStep, ScalarStep}, Flags, R.getDebugLoc());
VectorStep = Mul;
VPI->replaceAllUsesWith(VectorStep);
ToRemove.push_back(VPI);
}
}
for (VPRecipeBase *R : ToRemove)
R->eraseFromParent();
}
void VPlanTransforms::handleUncountableEarlyExit(
VPBasicBlock *EarlyExitingVPBB, VPBasicBlock *EarlyExitVPBB, VPlan &Plan,
VPBasicBlock *HeaderVPBB, VPBasicBlock *LatchVPBB, VFRange &Range) {
VPBlockBase *MiddleVPBB = LatchVPBB->getSuccessors()[0];
if (!EarlyExitVPBB->getSinglePredecessor() &&
EarlyExitVPBB->getPredecessors()[1] == MiddleVPBB) {
assert(EarlyExitVPBB->getNumPredecessors() == 2 &&
EarlyExitVPBB->getPredecessors()[0] == EarlyExitingVPBB &&
"unsupported early exit VPBB");
// Early exit operand should always be last phi operand. If EarlyExitVPBB
// has two predecessors and EarlyExitingVPBB is the first, swap the operands
// of the phis.
for (VPRecipeBase &R : EarlyExitVPBB->phis())
cast<VPIRPhi>(&R)->swapOperands();
}
VPBuilder Builder(LatchVPBB->getTerminator());
VPBlockBase *TrueSucc = EarlyExitingVPBB->getSuccessors()[0];
assert(
match(EarlyExitingVPBB->getTerminator(), m_BranchOnCond(m_VPValue())) &&
"Terminator must be be BranchOnCond");
VPValue *CondOfEarlyExitingVPBB =
EarlyExitingVPBB->getTerminator()->getOperand(0);
auto *CondToEarlyExit = TrueSucc == EarlyExitVPBB
? CondOfEarlyExitingVPBB
: Builder.createNot(CondOfEarlyExitingVPBB);
// Split the middle block and have it conditionally branch to the early exit
// block if CondToEarlyExit.
VPValue *IsEarlyExitTaken =
Builder.createNaryOp(VPInstruction::AnyOf, {CondToEarlyExit});
VPBasicBlock *NewMiddle = Plan.createVPBasicBlock("middle.split");
VPBasicBlock *VectorEarlyExitVPBB =
Plan.createVPBasicBlock("vector.early.exit");
VPBlockUtils::insertOnEdge(LatchVPBB, MiddleVPBB, NewMiddle);
VPBlockUtils::connectBlocks(NewMiddle, VectorEarlyExitVPBB);
NewMiddle->swapSuccessors();
VPBlockUtils::connectBlocks(VectorEarlyExitVPBB, EarlyExitVPBB);
// Update the exit phis in the early exit block.
VPBuilder MiddleBuilder(NewMiddle);
VPBuilder EarlyExitB(VectorEarlyExitVPBB);
for (VPRecipeBase &R : EarlyExitVPBB->phis()) {
auto *ExitIRI = cast<VPIRPhi>(&R);
// Early exit operand should always be last, i.e., 0 if EarlyExitVPBB has
// a single predecessor and 1 if it has two.
unsigned EarlyExitIdx = ExitIRI->getNumOperands() - 1;
if (ExitIRI->getNumOperands() != 1) {
// The first of two operands corresponds to the latch exit, via MiddleVPBB
// predecessor. Extract its last lane.
ExitIRI->extractLastLaneOfFirstOperand(MiddleBuilder);
}
VPValue *IncomingFromEarlyExit = ExitIRI->getOperand(EarlyExitIdx);
auto IsVector = [](ElementCount VF) { return VF.isVector(); };
// When the VFs are vectors, need to add `extract` to get the incoming value
// from early exit. When the range contains scalar VF, limit the range to
// scalar VF to prevent mis-compilation for the range containing both scalar
// and vector VFs.
if (!IncomingFromEarlyExit->isLiveIn() &&
LoopVectorizationPlanner::getDecisionAndClampRange(IsVector, Range)) {
// Update the incoming value from the early exit.
VPValue *FirstActiveLane = EarlyExitB.createNaryOp(
VPInstruction::FirstActiveLane, {CondToEarlyExit}, nullptr,
"first.active.lane");
IncomingFromEarlyExit = EarlyExitB.createNaryOp(
VPInstruction::ExtractLane, {FirstActiveLane, IncomingFromEarlyExit},
nullptr, "early.exit.value");
ExitIRI->setOperand(EarlyExitIdx, IncomingFromEarlyExit);
}
}
MiddleBuilder.createNaryOp(VPInstruction::BranchOnCond, {IsEarlyExitTaken});
// Replace the condition controlling the non-early exit from the vector loop
// with one exiting if either the original condition of the vector latch is
// true or the early exit has been taken.
auto *LatchExitingBranch = cast<VPInstruction>(LatchVPBB->getTerminator());
assert(LatchExitingBranch->getOpcode() == VPInstruction::BranchOnCount &&
"Unexpected terminator");
auto *IsLatchExitTaken =
Builder.createICmp(CmpInst::ICMP_EQ, LatchExitingBranch->getOperand(0),
LatchExitingBranch->getOperand(1));
auto *AnyExitTaken = Builder.createNaryOp(
Instruction::Or, {IsEarlyExitTaken, IsLatchExitTaken});
Builder.createNaryOp(VPInstruction::BranchOnCond, AnyExitTaken);
LatchExitingBranch->eraseFromParent();
}
/// 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 = Ctx.Types.inferScalarType(Red);
VPValue *VecOp = Red->getVecOp();
// Clamp the range if using extended-reduction is profitable.
auto IsExtendedRedValidAndClampRange = [&](unsigned Opcode, bool isZExt,
Type *SrcTy) -> bool {
return LoopVectorizationPlanner::getDecisionAndClampRange(
[&](ElementCount VF) {
auto *SrcVecTy = cast<VectorType>(toVectorTy(SrcTy, VF));
TTI::TargetCostKind CostKind = TTI::TCK_RecipThroughput;
InstructionCost ExtRedCost = Ctx.TTI.getExtendedReductionCost(
Opcode, isZExt, RedTy, SrcVecTy, Red->getFastMathFlags(),
CostKind);
InstructionCost ExtCost =
cast<VPWidenCastRecipe>(VecOp)->computeCost(VF, Ctx);
InstructionCost RedCost = Red->computeCost(VF, Ctx);
return ExtRedCost.isValid() && ExtRedCost < ExtCost + RedCost;
},
Range);
};
VPValue *A;
// Match reduce(ext)).
if (match(VecOp, m_ZExtOrSExt(m_VPValue(A))) &&
IsExtendedRedValidAndClampRange(
RecurrenceDescriptor::getOpcode(Red->getRecurrenceKind()),
cast<VPWidenCastRecipe>(VecOp)->getOpcode() ==
Instruction::CastOps::ZExt,
Ctx.Types.inferScalarType(A)))
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)))).
static VPExpressionRecipe *
tryToMatchAndCreateMulAccumulateReduction(VPReductionRecipe *Red,
VPCostContext &Ctx, VFRange &Range) {
unsigned Opcode = RecurrenceDescriptor::getOpcode(Red->getRecurrenceKind());
if (Opcode != Instruction::Add)
return nullptr;
Type *RedTy = Ctx.Types.inferScalarType(Red);
// Clamp the range if using multiply-accumulate-reduction is profitable.
auto IsMulAccValidAndClampRange =
[&](bool isZExt, VPWidenRecipe *Mul, VPWidenCastRecipe *Ext0,
VPWidenCastRecipe *Ext1, VPWidenCastRecipe *OuterExt) -> bool {
return LoopVectorizationPlanner::getDecisionAndClampRange(
[&](ElementCount VF) {
TTI::TargetCostKind CostKind = TTI::TCK_RecipThroughput;
Type *SrcTy =
Ext0 ? Ctx.Types.inferScalarType(Ext0->getOperand(0)) : RedTy;
auto *SrcVecTy = cast<VectorType>(toVectorTy(SrcTy, VF));
InstructionCost MulAccCost =
Ctx.TTI.getMulAccReductionCost(isZExt, 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();
VPValue *A, *B;
// Try to match reduce.add(mul(...)).
if (match(VecOp, m_Mul(m_VPValue(A), m_VPValue(B)))) {
auto *RecipeA =
dyn_cast_if_present<VPWidenCastRecipe>(A->getDefiningRecipe());
auto *RecipeB =
dyn_cast_if_present<VPWidenCastRecipe>(B->getDefiningRecipe());
auto *Mul = cast<VPWidenRecipe>(VecOp->getDefiningRecipe());
// Match reduce.add(mul(ext, ext)).
if (RecipeA && RecipeB &&
(RecipeA->getOpcode() == RecipeB->getOpcode() || A == B) &&
match(RecipeA, m_ZExtOrSExt(m_VPValue())) &&
match(RecipeB, m_ZExtOrSExt(m_VPValue())) &&
IsMulAccValidAndClampRange(RecipeA->getOpcode() ==
Instruction::CastOps::ZExt,
Mul, RecipeA, RecipeB, nullptr)) {
return new VPExpressionRecipe(RecipeA, RecipeB, Mul, Red);
}
// Match reduce.add(mul).
if (IsMulAccValidAndClampRange(true, Mul, nullptr, nullptr, nullptr))
return new VPExpressionRecipe(Mul, Red);
}
// Match reduce.add(ext(mul(ext(A), ext(B)))).
// All extend recipes must have same opcode or A == B
// which can be transform to reduce.add(zext(mul(sext(A), sext(B)))).
if (match(VecOp, m_ZExtOrSExt(m_Mul(m_ZExtOrSExt(m_VPValue()),
m_ZExtOrSExt(m_VPValue()))))) {
auto *Ext = cast<VPWidenCastRecipe>(VecOp->getDefiningRecipe());
auto *Mul = cast<VPWidenRecipe>(Ext->getOperand(0)->getDefiningRecipe());
auto *Ext0 =
cast<VPWidenCastRecipe>(Mul->getOperand(0)->getDefiningRecipe());
auto *Ext1 =
cast<VPWidenCastRecipe>(Mul->getOperand(1)->getDefiningRecipe());
if ((Ext->getOpcode() == Ext0->getOpcode() || Ext0 == Ext1) &&
Ext0->getOpcode() == Ext1->getOpcode() &&
IsMulAccValidAndClampRange(Ext0->getOpcode() ==
Instruction::CastOps::ZExt,
Mul, Ext0, Ext1, Ext)) {
auto *NewExt0 = new VPWidenCastRecipe(
Ext0->getOpcode(), Ext0->getOperand(0), Ext->getResultType(), *Ext0,
Ext0->getDebugLoc());
NewExt0->insertBefore(Ext0);
VPWidenCastRecipe *NewExt1 = NewExt0;
if (Ext0 != Ext1) {
NewExt1 = new VPWidenCastRecipe(Ext1->getOpcode(), Ext1->getOperand(0),
Ext->getResultType(), *Ext1,
Ext1->getDebugLoc());
NewExt1->insertBefore(Ext1);
}
Mul->setOperand(0, NewExt0);
Mul->setOperand(1, NewExt1);
Red->setOperand(1, Mul);
return new VPExpressionRecipe(NewExt0, NewExt1, Mul, 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) {
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;
VPDT.recalculate(Plan);
#endif
SmallVector<VPValue *> VPValues;
if (Plan.getOrCreateBackedgeTakenCount()->getNumUsers() > 0)
VPValues.push_back(Plan.getOrCreateBackedgeTakenCount());
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) ||
(VPV->isLiveIn() && VPV->getLiveInIRValue() &&
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);
});
}
}
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();
// 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() ||
!TC->isLiveIn())
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 = VPTypeAnalysis(Plan).inferScalarType(Plan.getTripCount());
auto *TCMO = Builder.createNaryOp(
Instruction::Sub,
{Plan.getTripCount(), Plan.getOrAddLiveIn(ConstantInt::get(TCTy, 1))},
DebugLoc::getCompilerGenerated(), "trip.count.minus.1");
BTC->replaceAllUsesWith(TCMO);
}
void VPlanTransforms::materializeBuildVectors(VPlan &Plan) {
if (Plan.hasScalarVFOnly())
return;
VPTypeAnalysis TypeInfo(Plan);
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,
// excluding ones in replicate regions. Those are not materialized explicitly
// yet. Those vector users are still handled in VPReplicateRegion::execute(),
// via shouldPack().
// TODO: materialize build vectors for replicating recipes in replicating
// regions.
// TODO: materialize build vectors for VPInstructions.
for (VPBasicBlock *VPBB :
concat<VPBasicBlock *>(VPBBsOutsideLoopRegion, VPBBsInsideLoopRegion)) {
for (VPRecipeBase &R : make_early_inc_range(*VPBB)) {
auto *RepR = dyn_cast<VPReplicateRecipe>(&R);
auto UsesVectorOrInsideReplicateRegion = [RepR, LoopRegion](VPUser *U) {
VPRegionBlock *ParentRegion =
cast<VPRecipeBase>(U)->getParent()->getParent();
return !U->usesScalars(RepR) || ParentRegion != LoopRegion;
};
if (!RepR || RepR->isSingleScalar() ||
none_of(RepR->users(), UsesVectorOrInsideReplicateRegion))
continue;
Type *ScalarTy = TypeInfo.inferScalarType(RepR);
unsigned Opcode = ScalarTy->isStructTy()
? VPInstruction::BuildStructVector
: VPInstruction::BuildVector;
auto *BuildVector = new VPInstruction(Opcode, {RepR});
BuildVector->insertAfter(RepR);
RepR->replaceUsesWithIf(
BuildVector, [BuildVector, &UsesVectorOrInsideReplicateRegion](
VPUser &U, unsigned) {
return &U != BuildVector && UsesVectorOrInsideReplicateRegion(&U);
});
}
}
}
void VPlanTransforms::materializeVectorTripCount(VPlan &Plan,
VPBasicBlock *VectorPHVPBB,
bool TailByMasking,
bool RequiresScalarEpilogue) {
VPValue &VectorTC = Plan.getVectorTripCount();
assert(VectorTC.isLiveIn() && "vector-trip-count must be a live-in");
// 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.getLiveInIRValue())
return;
VPValue *TC = Plan.getTripCount();
Type *TCTy = VPTypeAnalysis(Plan).inferScalarType(TC);
VPBuilder Builder(VectorPHVPBB, VectorPHVPBB->begin());
VPValue *Step = &Plan.getVFxUF();
// 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.
// For scalable vectors the VF is not guaranteed to be a power of 2, but this
// is accounted for in emitIterationCountCheck that adds an overflow check.
if (TailByMasking) {
TC = Builder.createNaryOp(
Instruction::Add,
{TC, Builder.createNaryOp(
Instruction::Sub,
{Step, Plan.getOrAddLiveIn(ConstantInt::get(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.getOrAddLiveIn(ConstantInt::get(TCTy, 0)));
R = Builder.createSelect(IsZero, Step, R);
}
VPValue *Res = Builder.createNaryOp(
Instruction::Sub, {TC, R}, DebugLoc::getCompilerGenerated(), "n.vec");
VectorTC.replaceAllUsesWith(Res);
}
void VPlanTransforms::materializeVFAndVFxUF(VPlan &Plan, VPBasicBlock *VectorPH,
ElementCount VFEC) {
VPBuilder Builder(VectorPH, VectorPH->begin());
Type *TCTy = VPTypeAnalysis(Plan).inferScalarType(Plan.getTripCount());
VPValue &VF = Plan.getVF();
VPValue &VFxUF = Plan.getVFxUF();
// Note that after the transform, Plan.getVF and Plan.getVFxUF should not be
// used.
// TODO: Assert that they aren't used.
// 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.getUF());
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 *UF = Plan.getOrAddLiveIn(ConstantInt::get(TCTy, Plan.getUF()));
VPValue *MulByUF = Builder.createNaryOp(Instruction::Mul, {RuntimeVF, UF});
VFxUF.replaceAllUsesWith(MulByUF);
}
/// 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(VPWidenRecipe *WideMember0, unsigned OpIdx,
VPValue *OpV, unsigned Idx) {
auto *DefR = OpV->getDefiningRecipe();
if (!DefR)
return WideMember0->getOperand(OpIdx) == OpV;
if (auto *W = dyn_cast<VPWidenLoadRecipe>(DefR))
return !W->getMask() && WideMember0->getOperand(OpIdx) == OpV;
if (auto *IR = dyn_cast<VPInterleaveRecipe>(DefR))
return IR->getInterleaveGroup()->isFull() && IR->getVPValue(Idx) == OpV;
return false;
}
/// Returns true if \p IR is a full interleave group with factor and number of
/// members both equal to \p VF. The interleave group must also access the full
/// vector width \p VectorRegWidth.
static bool isConsecutiveInterleaveGroup(VPInterleaveRecipe *InterleaveR,
unsigned VF, VPTypeAnalysis &TypeInfo,
unsigned VectorRegWidth) {
if (!InterleaveR)
return false;
Type *GroupElementTy = nullptr;
if (InterleaveR->getStoredValues().empty()) {
GroupElementTy = TypeInfo.inferScalarType(InterleaveR->getVPValue(0));
if (!all_of(InterleaveR->definedValues(),
[&TypeInfo, GroupElementTy](VPValue *Op) {
return TypeInfo.inferScalarType(Op) == GroupElementTy;
}))
return false;
} else {
GroupElementTy =
TypeInfo.inferScalarType(InterleaveR->getStoredValues()[0]);
if (!all_of(InterleaveR->getStoredValues(),
[&TypeInfo, GroupElementTy](VPValue *Op) {
return TypeInfo.inferScalarType(Op) == GroupElementTy;
}))
return false;
}
unsigned GroupSize = GroupElementTy->getScalarSizeInBits() * VF;
auto IG = InterleaveR->getInterleaveGroup();
return IG->getFactor() == VF && IG->getNumMembers() == VF &&
GroupSize == VectorRegWidth;
}
/// Returns true if \p VPValue is a narrow VPValue.
static bool isAlreadyNarrow(VPValue *VPV) {
if (VPV->isLiveIn())
return true;
auto *RepR = dyn_cast<VPReplicateRecipe>(VPV);
return RepR && RepR->isSingleScalar();
}
void VPlanTransforms::narrowInterleaveGroups(VPlan &Plan, ElementCount VF,
unsigned VectorRegWidth) {
VPRegionBlock *VectorLoop = Plan.getVectorLoopRegion();
if (VF.isScalable() || !VectorLoop)
return;
VPTypeAnalysis TypeInfo(Plan);
unsigned FixedVF = VF.getFixedValue();
SmallVector<VPInterleaveRecipe *> StoreGroups;
for (auto &R : *VectorLoop->getEntryBasicBlock()) {
if (isa<VPCanonicalIVPHIRecipe>(&R) ||
match(&R, m_BranchOnCount(m_VPValue(), m_VPValue())))
continue;
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;
auto *InterleaveR = dyn_cast<VPInterleaveRecipe>(&R);
if (R.mayWriteToMemory() && !InterleaveR)
return;
// Do not narrow interleave groups if there are VectorPointer recipes and
// the plan was unrolled. The recipe implicitly uses VF from
// VPTransformState.
// TODO: Remove restriction once the VF for the VectorPointer offset is
// modeled explicitly as operand.
if (isa<VPVectorPointerRecipe>(&R) && Plan.getUF() > 1)
return;
// 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;
// Bail out on non-consecutive interleave groups.
if (!isConsecutiveInterleaveGroup(InterleaveR, FixedVF, TypeInfo,
VectorRegWidth))
return;
// 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(),
[Member0](VPValue *VPV) { return Member0 == VPV; })) {
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.
auto *WideMember0 = dyn_cast_or_null<VPWidenRecipe>(
InterleaveR->getStoredValues()[0]->getDefiningRecipe());
if (!WideMember0)
return;
for (const auto &[I, V] : enumerate(InterleaveR->getStoredValues())) {
auto *R = dyn_cast_or_null<VPWidenRecipe>(V->getDefiningRecipe());
if (!R || R->getOpcode() != WideMember0->getOpcode() ||
R->getNumOperands() > 2)
return;
if (any_of(enumerate(R->operands()),
[WideMember0, Idx = I](const auto &P) {
const auto &[OpIdx, OpV] = P;
return !canNarrowLoad(WideMember0, OpIdx, OpV, Idx);
}))
return;
}
StoreGroups.push_back(InterleaveR);
}
if (StoreGroups.empty())
return;
// Convert InterleaveGroup \p R to a single VPWidenLoadRecipe.
auto NarrowOp = [](VPValue *V) -> VPValue * {
auto *R = V->getDefiningRecipe();
if (!R)
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 *L = new VPWidenLoadRecipe(
*cast<LoadInst>(LoadGroup->getInterleaveGroup()->getInsertPos()),
LoadGroup->getAddr(), LoadGroup->getMask(), /*Consecutive=*/true,
/*Reverse=*/false, {}, LoadGroup->getDebugLoc());
L->insertBefore(LoadGroup);
return L;
}
if (auto *RepR = dyn_cast<VPReplicateRecipe>(R)) {
assert(RepR->isSingleScalar() &&
isa<LoadInst>(RepR->getUnderlyingInstr()) &&
"must be a single scalar load");
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);
return N;
};
// Narrow operation tree rooted at store groups.
for (auto *StoreGroup : StoreGroups) {
VPValue *Res = nullptr;
VPValue *Member0 = StoreGroup->getStoredValues()[0];
if (isAlreadyNarrow(Member0)) {
Res = Member0;
} else if (auto *WideMember0 =
dyn_cast<VPWidenRecipe>(Member0->getDefiningRecipe())) {
for (unsigned Idx = 0, E = WideMember0->getNumOperands(); Idx != E; ++Idx)
WideMember0->setOperand(Idx, NarrowOp(WideMember0->getOperand(Idx)));
Res = WideMember0;
} else {
Res = NarrowOp(Member0);
}
auto *S = new VPWidenStoreRecipe(
*cast<StoreInst>(StoreGroup->getInterleaveGroup()->getInsertPos()),
StoreGroup->getAddr(), Res, nullptr, /*Consecutive=*/true,
/*Reverse=*/false, {}, StoreGroup->getDebugLoc());
S->insertBefore(StoreGroup);
StoreGroup->eraseFromParent();
}
// Adjust induction to reflect that the transformed plan only processes one
// original iteration.
auto *CanIV = Plan.getCanonicalIV();
auto *Inc = cast<VPInstruction>(CanIV->getBackedgeValue());
Inc->setOperand(1, Plan.getOrAddLiveIn(ConstantInt::get(
CanIV->getScalarType(), 1 * Plan.getUF())));
Plan.getVF().replaceAllUsesWith(
Plan.getOrAddLiveIn(ConstantInt::get(CanIV->getScalarType(), 1)));
removeDeadRecipes(Plan);
}
/// 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.getUF() * 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->addMetadata(LLVMContext::MD_prof, BranchWeights);
}
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