| //===-- 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 "VPlanDominatorTree.h" |
| #include "VPRecipeBuilder.h" |
| #include "VPlanCFG.h" |
| #include "llvm/ADT/PostOrderIterator.h" |
| #include "llvm/ADT/SetVector.h" |
| #include "llvm/Analysis/IVDescriptors.h" |
| #include "llvm/Analysis/VectorUtils.h" |
| #include "llvm/IR/Intrinsics.h" |
| |
| using namespace llvm; |
| |
| void VPlanTransforms::VPInstructionsToVPRecipes( |
| VPlanPtr &Plan, |
| function_ref<const InductionDescriptor *(PHINode *)> |
| GetIntOrFpInductionDescriptor, |
| ScalarEvolution &SE, const TargetLibraryInfo &TLI) { |
| |
| ReversePostOrderTraversal<VPBlockDeepTraversalWrapper<VPBlockBase *>> RPOT( |
| Plan->getEntry()); |
| for (VPBasicBlock *VPBB : VPBlockUtils::blocksOnly<VPBasicBlock>(RPOT)) { |
| 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(); |
| Instruction *Inst = cast<Instruction>(VPV->getUnderlyingValue()); |
| |
| VPRecipeBase *NewRecipe = nullptr; |
| if (auto *VPPhi = dyn_cast<VPWidenPHIRecipe>(&Ingredient)) { |
| auto *Phi = cast<PHINode>(VPPhi->getUnderlyingValue()); |
| if (const auto *II = GetIntOrFpInductionDescriptor(Phi)) { |
| VPValue *Start = Plan->getVPValueOrAddLiveIn(II->getStartValue()); |
| VPValue *Step = |
| vputils::getOrCreateVPValueForSCEVExpr(*Plan, II->getStep(), SE); |
| NewRecipe = new VPWidenIntOrFpInductionRecipe(Phi, Start, Step, *II); |
| } else { |
| Plan->addVPValue(Phi, VPPhi); |
| continue; |
| } |
| } else { |
| assert(isa<VPInstruction>(&Ingredient) && |
| "only VPInstructions expected here"); |
| assert(!isa<PHINode>(Inst) && "phis should be handled above"); |
| // Create VPWidenMemoryInstructionRecipe for loads and stores. |
| if (LoadInst *Load = dyn_cast<LoadInst>(Inst)) { |
| NewRecipe = new VPWidenMemoryInstructionRecipe( |
| *Load, Ingredient.getOperand(0), nullptr /*Mask*/, |
| false /*Consecutive*/, false /*Reverse*/); |
| } else if (StoreInst *Store = dyn_cast<StoreInst>(Inst)) { |
| NewRecipe = new VPWidenMemoryInstructionRecipe( |
| *Store, Ingredient.getOperand(1), Ingredient.getOperand(0), |
| nullptr /*Mask*/, false /*Consecutive*/, false /*Reverse*/); |
| } else if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Inst)) { |
| NewRecipe = new VPWidenGEPRecipe(GEP, Ingredient.operands()); |
| } else if (CallInst *CI = dyn_cast<CallInst>(Inst)) { |
| NewRecipe = |
| new VPWidenCallRecipe(*CI, drop_end(Ingredient.operands()), |
| getVectorIntrinsicIDForCall(CI, &TLI)); |
| } 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(); |
| } |
| } |
| } |
| |
| 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 *, VPRecipeBase *>> 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 = 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; |
| VPRecipeBase *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->isUniform()) |
| 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 = dyn_cast<VPRecipeBase>(U); |
| if (!UI) |
| return false; |
| if (UI->getParent() == SinkTo) |
| return true; |
| NeedsDuplicating = |
| UI->onlyFirstLaneUsed(SinkCandidate->getVPSingleValue()); |
| // We only know how to duplicate VPRecipeRecipes for now. |
| return NeedsDuplicating && isa<VPReplicateRecipe>(SinkCandidate); |
| }; |
| if (!all_of(SinkCandidate->getVPSingleValue()->users(), CanSinkWithUser)) |
| continue; |
| |
| if (NeedsDuplicating) { |
| if (ScalarVFOnly) |
| continue; |
| Instruction *I = cast<Instruction>( |
| cast<VPReplicateRecipe>(SinkCandidate)->getUnderlyingValue()); |
| auto *Clone = new VPReplicateRecipe(I, SinkCandidate->operands(), true); |
| // TODO: add ".cloned" suffix to name of Clone's VPValue. |
| |
| Clone->insertBefore(SinkCandidate); |
| for (auto *U : to_vector(SinkCandidate->getVPSingleValue()->users())) { |
| auto *UI = cast<VPRecipeBase>(U); |
| if (UI->getParent() == SinkTo) |
| continue; |
| |
| for (unsigned Idx = 0; Idx != UI->getNumOperands(); Idx++) { |
| if (UI->getOperand(Idx) != SinkCandidate->getVPSingleValue()) |
| continue; |
| UI->setOperand(Idx, Clone); |
| } |
| } |
| } |
| SinkCandidate->moveBefore(*SinkTo, SinkTo->getFirstNonPhi()); |
| for (VPValue *Op : SinkCandidate->operands()) |
| if (auto *Def = 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) { |
| SetVector<VPRegionBlock *> DeletedRegions; |
| |
| // 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 (DeletedRegions.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(); |
| for (VPUser *U : to_vector(Phi1ToMoveV->users())) { |
| auto *UI = dyn_cast<VPRecipeBase>(U); |
| if (!UI || UI->getParent() != Then2) |
| continue; |
| for (unsigned I = 0, E = U->getNumOperands(); I != E; ++I) { |
| if (Phi1ToMoveV != U->getOperand(I)) |
| continue; |
| U->setOperand(I, PredInst1); |
| } |
| } |
| |
| Phi1ToMove.moveBefore(*Merge2, Merge2->begin()); |
| } |
| |
| // 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); |
| DeletedRegions.insert(Region1); |
| } |
| |
| for (VPRegionBlock *ToDelete : DeletedRegions) |
| delete ToDelete; |
| return !DeletedRegions.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 *BOMRecipe = new VPBranchOnMaskRecipe(BlockInMask); |
| auto *Entry = new VPBasicBlock(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->isUniform()); |
| auto *Pred = new VPBasicBlock(Twine(RegionName) + ".if", RecipeWithoutMask); |
| |
| VPPredInstPHIRecipe *PHIRecipe = nullptr; |
| if (PredRecipe->getNumUsers() != 0) { |
| PHIRecipe = new VPPredInstPHIRecipe(RecipeWithoutMask); |
| PredRecipe->replaceAllUsesWith(PHIRecipe); |
| PHIRecipe->setOperand(0, RecipeWithoutMask); |
| } |
| PredRecipe->eraseFromParent(); |
| auto *Exiting = new VPBasicBlock(Twine(RegionName) + ".continue", PHIRecipe); |
| VPRegionBlock *Region = new VPRegionBlock(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. |
| VPBlockBase *Region = createReplicateRegion(RepR, Plan); |
| Region->setParent(CurrentBlock->getParent()); |
| VPBlockUtils::disconnectBlocks(CurrentBlock, SplitBlock); |
| VPBlockUtils::connectBlocks(CurrentBlock, Region); |
| VPBlockUtils::connectBlocks(Region, SplitBlock); |
| } |
| } |
| |
| 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 |= VPlanTransforms::mergeBlocksIntoPredecessors(Plan); |
| } |
| } |
| bool VPlanTransforms::mergeBlocksIntoPredecessors(VPlan &Plan) { |
| SmallVector<VPBasicBlock *> WorkList; |
| for (VPBasicBlock *VPBB : VPBlockUtils::blocksOnly<VPBasicBlock>( |
| vp_depth_first_deep(Plan.getEntry()))) { |
| auto *PredVPBB = |
| dyn_cast_or_null<VPBasicBlock>(VPBB->getSinglePredecessor()); |
| if (PredVPBB && PredVPBB->getNumSuccessors() == 1) |
| 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 = cast_or_null<VPRegionBlock>(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); |
| } |
| delete VPBB; |
| } |
| return !WorkList.empty(); |
| } |
| |
| void VPlanTransforms::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)) { |
| VPRecipeBase *FoundUserCast = nullptr; |
| for (auto *U : FindMyCast->users()) { |
| auto *UserCast = cast<VPRecipeBase>(U); |
| if (UserCast->getNumDefinedValues() == 1 && |
| UserCast->getVPSingleValue()->getUnderlyingValue() == IRCast) { |
| FoundUserCast = UserCast; |
| break; |
| } |
| } |
| FindMyCast = FoundUserCast->getVPSingleValue(); |
| } |
| FindMyCast->replaceAllUsesWith(IV); |
| } |
| } |
| |
| void VPlanTransforms::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() || |
| WidenOriginalIV->getScalarType() != WidenNewIV->getScalarType()) |
| 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 (any_of(WidenOriginalIV->users(), |
| [WidenOriginalIV](VPUser *U) { |
| return !U->usesScalars(WidenOriginalIV); |
| }) || |
| vputils::onlyFirstLaneUsed(WidenNewIV)) { |
| WidenNewIV->replaceAllUsesWith(WidenOriginalIV); |
| WidenNewIV->eraseFromParent(); |
| return; |
| } |
| } |
| } |
| |
| void VPlanTransforms::removeDeadRecipes(VPlan &Plan) { |
| ReversePostOrderTraversal<VPBlockDeepTraversalWrapper<VPBlockBase *>> RPOT( |
| Plan.getEntry()); |
| |
| for (VPBasicBlock *VPBB : reverse(VPBlockUtils::blocksOnly<VPBasicBlock>(RPOT))) { |
| // 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 (R.mayHaveSideEffects() || any_of(R.definedValues(), [](VPValue *V) { |
| return V->getNumUsers() > 0; |
| })) |
| continue; |
| R.eraseFromParent(); |
| } |
| } |
| } |
| |
| void VPlanTransforms::optimizeInductions(VPlan &Plan, ScalarEvolution &SE) { |
| SmallVector<VPRecipeBase *> ToRemove; |
| VPBasicBlock *HeaderVPBB = Plan.getVectorLoopRegion()->getEntryBasicBlock(); |
| bool HasOnlyVectorVFs = !Plan.hasVF(ElementCount::getFixed(1)); |
| for (VPRecipeBase &Phi : HeaderVPBB->phis()) { |
| auto *WideIV = dyn_cast<VPWidenIntOrFpInductionRecipe>(&Phi); |
| if (!WideIV) |
| continue; |
| if (HasOnlyVectorVFs && none_of(WideIV->users(), [WideIV](VPUser *U) { |
| return U->usesScalars(WideIV); |
| })) |
| continue; |
| |
| auto IP = HeaderVPBB->getFirstNonPhi(); |
| VPCanonicalIVPHIRecipe *CanonicalIV = Plan.getCanonicalIV(); |
| Type *ResultTy = WideIV->getPHINode()->getType(); |
| if (Instruction *TruncI = WideIV->getTruncInst()) |
| ResultTy = TruncI->getType(); |
| const InductionDescriptor &ID = WideIV->getInductionDescriptor(); |
| VPValue *Step = WideIV->getStepValue(); |
| VPValue *BaseIV = CanonicalIV; |
| if (!CanonicalIV->isCanonical(ID.getKind(), WideIV->getStartValue(), Step, |
| ResultTy)) { |
| BaseIV = new VPDerivedIVRecipe(ID, WideIV->getStartValue(), CanonicalIV, |
| Step, ResultTy); |
| HeaderVPBB->insert(BaseIV->getDefiningRecipe(), IP); |
| } |
| |
| VPScalarIVStepsRecipe *Steps = new VPScalarIVStepsRecipe(ID, BaseIV, Step); |
| HeaderVPBB->insert(Steps, IP); |
| |
| // Update scalar users of IV to use Step instead. Use SetVector to ensure |
| // the list of users doesn't contain duplicates. |
| SetVector<VPUser *> Users(WideIV->user_begin(), WideIV->user_end()); |
| for (VPUser *U : Users) { |
| if (HasOnlyVectorVFs && !U->usesScalars(WideIV)) |
| continue; |
| for (unsigned I = 0, E = U->getNumOperands(); I != E; I++) { |
| if (U->getOperand(I) != WideIV) |
| continue; |
| U->setOperand(I, Steps); |
| } |
| } |
| } |
| } |
| |
| void VPlanTransforms::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 bool canSimplifyBranchOnCond(VPInstruction *Term) { |
| VPInstruction *Not = dyn_cast<VPInstruction>(Term->getOperand(0)); |
| if (!Not || Not->getOpcode() != VPInstruction::Not) |
| return false; |
| |
| VPInstruction *ALM = dyn_cast<VPInstruction>(Not->getOperand(0)); |
| return ALM && ALM->getOpcode() == VPInstruction::ActiveLaneMask; |
| } |
| |
| 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"); |
| VPBasicBlock *ExitingVPBB = |
| Plan.getVectorLoopRegion()->getExitingBasicBlock(); |
| auto *Term = dyn_cast<VPInstruction>(&ExitingVPBB->back()); |
| // Try to simplify the branch condition if TC <= VF * UF when preparing to |
| // execute the plan for the main vector loop. We only do this if the |
| // terminator is: |
| // 1. BranchOnCount, or |
| // 2. BranchOnCond where the input is Not(ActiveLaneMask). |
| if (!Term || (Term->getOpcode() != VPInstruction::BranchOnCount && |
| (Term->getOpcode() != VPInstruction::BranchOnCond || |
| !canSimplifyBranchOnCond(Term)))) |
| return; |
| |
| Type *IdxTy = |
| Plan.getCanonicalIV()->getStartValue()->getLiveInIRValue()->getType(); |
| const SCEV *TripCount = createTripCountSCEV(IdxTy, PSE); |
| ScalarEvolution &SE = *PSE.getSE(); |
| const SCEV *C = |
| SE.getConstant(TripCount->getType(), BestVF.getKnownMinValue() * BestUF); |
| if (TripCount->isZero() || |
| !SE.isKnownPredicate(CmpInst::ICMP_ULE, TripCount, C)) |
| return; |
| |
| LLVMContext &Ctx = SE.getContext(); |
| auto *BOC = new VPInstruction( |
| VPInstruction::BranchOnCond, |
| {Plan.getVPValueOrAddLiveIn(ConstantInt::getTrue(Ctx))}); |
| Term->eraseFromParent(); |
| ExitingVPBB->appendRecipe(BOC); |
| Plan.setVF(BestVF); |
| Plan.setUF(BestUF); |
| // TODO: Further simplifications are possible |
| // 1. Replace inductions with constants. |
| // 2. Replace vector loop region with VPBasicBlock. |
| } |
| |
| #ifndef NDEBUG |
| static VPRegionBlock *GetReplicateRegion(VPRecipeBase *R) { |
| auto *Region = dyn_cast_or_null<VPRegionBlock>(R->getParent()->getParent()); |
| if (Region && Region->isReplicator()) { |
| assert(Region->getNumSuccessors() == 1 && |
| Region->getNumPredecessors() == 1 && "Expected SESE region!"); |
| assert(R->getParent()->size() == 1 && |
| "A recipe in an original replicator region must be the only " |
| "recipe in its block"); |
| return Region; |
| } |
| return nullptr; |
| } |
| #endif |
| |
| static bool properlyDominates(const VPRecipeBase *A, const VPRecipeBase *B, |
| VPDominatorTree &VPDT) { |
| if (A == B) |
| return false; |
| |
| auto LocalComesBefore = [](const VPRecipeBase *A, const VPRecipeBase *B) { |
| for (auto &R : *A->getParent()) { |
| if (&R == A) |
| return true; |
| if (&R == B) |
| return false; |
| } |
| llvm_unreachable("recipe not found"); |
| }; |
| const VPBlockBase *ParentA = A->getParent(); |
| const VPBlockBase *ParentB = B->getParent(); |
| if (ParentA == ParentB) |
| return LocalComesBefore(A, B); |
| |
| assert(!GetReplicateRegion(const_cast<VPRecipeBase *>(A)) && |
| "No replicate regions expected at this point"); |
| assert(!GetReplicateRegion(const_cast<VPRecipeBase *>(B)) && |
| "No replicate regions expected at this point"); |
| return VPDT.properlyDominates(ParentA, ParentB); |
| } |
| |
| /// 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 || |
| properlyDominates(Previous, SinkCandidate, VPDT)) |
| 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 (auto *R = dyn_cast<VPRecipeBase>(User)) |
| if (!TryToPushSinkCandidate(R)) |
| 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 properlyDominates(A, B, VPDT); |
| }); |
| |
| for (VPRecipeBase *SinkCandidate : WorkList) { |
| if (SinkCandidate == FOR) |
| continue; |
| |
| SinkCandidate->moveAfter(Previous); |
| Previous = SinkCandidate; |
| } |
| return true; |
| } |
| |
| bool VPlanTransforms::adjustFixedOrderRecurrences(VPlan &Plan, |
| VPBuilder &Builder) { |
| 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)) |
| 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)) |
| Builder.setInsertPoint(InsertBlock, InsertBlock->getFirstNonPhi()); |
| else |
| Builder.setInsertPoint(InsertBlock, std::next(Previous->getIterator())); |
| |
| auto *RecurSplice = cast<VPInstruction>( |
| Builder.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; |
| const RecurrenceDescriptor &RdxDesc = PhiR->getRecurrenceDescriptor(); |
| RecurKind RK = RdxDesc.getRecurrenceKind(); |
| if (RK != RecurKind::Add && RK != RecurKind::Mul) |
| continue; |
| |
| SmallSetVector<VPValue *, 8> Worklist; |
| Worklist.insert(PhiR); |
| |
| for (unsigned I = 0; I != Worklist.size(); ++I) { |
| VPValue *Cur = Worklist[I]; |
| if (auto *RecWithFlags = |
| dyn_cast<VPRecipeWithIRFlags>(Cur->getDefiningRecipe())) { |
| RecWithFlags->dropPoisonGeneratingFlags(); |
| } |
| |
| for (VPUser *U : Cur->users()) { |
| auto *UserRecipe = dyn_cast<VPRecipeBase>(U); |
| if (!UserRecipe) |
| continue; |
| for (VPValue *V : UserRecipe->definedValues()) |
| Worklist.insert(V); |
| } |
| } |
| } |
| } |
