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Diffstat (limited to 'lib/Transforms/Vectorize/LoadStoreVectorizer.cpp')
| -rw-r--r-- | lib/Transforms/Vectorize/LoadStoreVectorizer.cpp | 999 |
1 files changed, 999 insertions, 0 deletions
diff --git a/lib/Transforms/Vectorize/LoadStoreVectorizer.cpp b/lib/Transforms/Vectorize/LoadStoreVectorizer.cpp new file mode 100644 index 000000000000..c8906bde15e0 --- /dev/null +++ b/lib/Transforms/Vectorize/LoadStoreVectorizer.cpp @@ -0,0 +1,999 @@ +//===----- LoadStoreVectorizer.cpp - GPU Load & Store Vectorizer ----------===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +// +//===----------------------------------------------------------------------===// + +#include "llvm/ADT/MapVector.h" +#include "llvm/ADT/PostOrderIterator.h" +#include "llvm/ADT/SetVector.h" +#include "llvm/ADT/Statistic.h" +#include "llvm/ADT/Triple.h" +#include "llvm/Analysis/AliasAnalysis.h" +#include "llvm/Analysis/ScalarEvolution.h" +#include "llvm/Analysis/ScalarEvolutionExpressions.h" +#include "llvm/Analysis/TargetTransformInfo.h" +#include "llvm/Analysis/ValueTracking.h" +#include "llvm/Analysis/VectorUtils.h" +#include "llvm/IR/DataLayout.h" +#include "llvm/IR/Dominators.h" +#include "llvm/IR/IRBuilder.h" +#include "llvm/IR/Instructions.h" +#include "llvm/IR/Module.h" +#include "llvm/IR/Type.h" +#include "llvm/IR/Value.h" +#include "llvm/Support/CommandLine.h" +#include "llvm/Support/Debug.h" +#include "llvm/Support/raw_ostream.h" +#include "llvm/Transforms/Vectorize.h" + +using namespace llvm; + +#define DEBUG_TYPE "load-store-vectorizer" +STATISTIC(NumVectorInstructions, "Number of vector accesses generated"); +STATISTIC(NumScalarsVectorized, "Number of scalar accesses vectorized"); + +namespace { + +// TODO: Remove this +static const unsigned TargetBaseAlign = 4; + +class Vectorizer { + typedef SmallVector<Value *, 8> ValueList; + typedef MapVector<Value *, ValueList> ValueListMap; + + Function &F; + AliasAnalysis &AA; + DominatorTree &DT; + ScalarEvolution &SE; + TargetTransformInfo &TTI; + const DataLayout &DL; + IRBuilder<> Builder; + ValueListMap StoreRefs; + ValueListMap LoadRefs; + +public: + Vectorizer(Function &F, AliasAnalysis &AA, DominatorTree &DT, + ScalarEvolution &SE, TargetTransformInfo &TTI) + : F(F), AA(AA), DT(DT), SE(SE), TTI(TTI), + DL(F.getParent()->getDataLayout()), Builder(SE.getContext()) {} + + bool run(); + +private: + Value *getPointerOperand(Value *I); + + unsigned getPointerAddressSpace(Value *I); + + unsigned getAlignment(LoadInst *LI) const { + unsigned Align = LI->getAlignment(); + if (Align != 0) + return Align; + + return DL.getABITypeAlignment(LI->getType()); + } + + unsigned getAlignment(StoreInst *SI) const { + unsigned Align = SI->getAlignment(); + if (Align != 0) + return Align; + + return DL.getABITypeAlignment(SI->getValueOperand()->getType()); + } + + bool isConsecutiveAccess(Value *A, Value *B); + + /// After vectorization, reorder the instructions that I depends on + /// (the instructions defining its operands), to ensure they dominate I. + void reorder(Instruction *I); + + /// Returns the first and the last instructions in Chain. + std::pair<BasicBlock::iterator, BasicBlock::iterator> + getBoundaryInstrs(ArrayRef<Value *> Chain); + + /// Erases the original instructions after vectorizing. + void eraseInstructions(ArrayRef<Value *> Chain); + + /// "Legalize" the vector type that would be produced by combining \p + /// ElementSizeBits elements in \p Chain. Break into two pieces such that the + /// total size of each piece is 1, 2 or a multiple of 4 bytes. \p Chain is + /// expected to have more than 4 elements. + std::pair<ArrayRef<Value *>, ArrayRef<Value *>> + splitOddVectorElts(ArrayRef<Value *> Chain, unsigned ElementSizeBits); + + /// Checks for instructions which may affect the memory accessed + /// in the chain between \p From and \p To. Returns Index, where + /// \p Chain[0, Index) is the largest vectorizable chain prefix. + /// The elements of \p Chain should be all loads or all stores. + unsigned getVectorizablePrefixEndIdx(ArrayRef<Value *> Chain, + BasicBlock::iterator From, + BasicBlock::iterator To); + + /// Collects load and store instructions to vectorize. + void collectInstructions(BasicBlock *BB); + + /// Processes the collected instructions, the \p Map. The elements of \p Map + /// should be all loads or all stores. + bool vectorizeChains(ValueListMap &Map); + + /// Finds the load/stores to consecutive memory addresses and vectorizes them. + bool vectorizeInstructions(ArrayRef<Value *> Instrs); + + /// Vectorizes the load instructions in Chain. + bool vectorizeLoadChain(ArrayRef<Value *> Chain, + SmallPtrSet<Value *, 16> *InstructionsProcessed); + + /// Vectorizes the store instructions in Chain. + bool vectorizeStoreChain(ArrayRef<Value *> Chain, + SmallPtrSet<Value *, 16> *InstructionsProcessed); + + /// Check if this load/store access is misaligned accesses + bool accessIsMisaligned(unsigned SzInBytes, unsigned AddressSpace, + unsigned Alignment); +}; + +class LoadStoreVectorizer : public FunctionPass { +public: + static char ID; + + LoadStoreVectorizer() : FunctionPass(ID) { + initializeLoadStoreVectorizerPass(*PassRegistry::getPassRegistry()); + } + + bool runOnFunction(Function &F) override; + + const char *getPassName() const override { + return "GPU Load and Store Vectorizer"; + } + + void getAnalysisUsage(AnalysisUsage &AU) const override { + AU.addRequired<AAResultsWrapperPass>(); + AU.addRequired<ScalarEvolutionWrapperPass>(); + AU.addRequired<DominatorTreeWrapperPass>(); + AU.addRequired<TargetTransformInfoWrapperPass>(); + AU.setPreservesCFG(); + } +}; +} + +INITIALIZE_PASS_BEGIN(LoadStoreVectorizer, DEBUG_TYPE, + "Vectorize load and Store instructions", false, false) +INITIALIZE_PASS_DEPENDENCY(SCEVAAWrapperPass) +INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass) +INITIALIZE_PASS_DEPENDENCY(AAResultsWrapperPass) +INITIALIZE_PASS_DEPENDENCY(GlobalsAAWrapperPass) +INITIALIZE_PASS_DEPENDENCY(TargetTransformInfoWrapperPass) +INITIALIZE_PASS_END(LoadStoreVectorizer, DEBUG_TYPE, + "Vectorize load and store instructions", false, false) + +char LoadStoreVectorizer::ID = 0; + +Pass *llvm::createLoadStoreVectorizerPass() { + return new LoadStoreVectorizer(); +} + +bool LoadStoreVectorizer::runOnFunction(Function &F) { + // Don't vectorize when the attribute NoImplicitFloat is used. + if (skipFunction(F) || F.hasFnAttribute(Attribute::NoImplicitFloat)) + return false; + + AliasAnalysis &AA = getAnalysis<AAResultsWrapperPass>().getAAResults(); + DominatorTree &DT = getAnalysis<DominatorTreeWrapperPass>().getDomTree(); + ScalarEvolution &SE = getAnalysis<ScalarEvolutionWrapperPass>().getSE(); + TargetTransformInfo &TTI = + getAnalysis<TargetTransformInfoWrapperPass>().getTTI(F); + + Vectorizer V(F, AA, DT, SE, TTI); + return V.run(); +} + +// Vectorizer Implementation +bool Vectorizer::run() { + bool Changed = false; + + // Scan the blocks in the function in post order. + for (BasicBlock *BB : post_order(&F)) { + collectInstructions(BB); + Changed |= vectorizeChains(LoadRefs); + Changed |= vectorizeChains(StoreRefs); + } + + return Changed; +} + +Value *Vectorizer::getPointerOperand(Value *I) { + if (LoadInst *LI = dyn_cast<LoadInst>(I)) + return LI->getPointerOperand(); + if (StoreInst *SI = dyn_cast<StoreInst>(I)) + return SI->getPointerOperand(); + return nullptr; +} + +unsigned Vectorizer::getPointerAddressSpace(Value *I) { + if (LoadInst *L = dyn_cast<LoadInst>(I)) + return L->getPointerAddressSpace(); + if (StoreInst *S = dyn_cast<StoreInst>(I)) + return S->getPointerAddressSpace(); + return -1; +} + +// FIXME: Merge with llvm::isConsecutiveAccess +bool Vectorizer::isConsecutiveAccess(Value *A, Value *B) { + Value *PtrA = getPointerOperand(A); + Value *PtrB = getPointerOperand(B); + unsigned ASA = getPointerAddressSpace(A); + unsigned ASB = getPointerAddressSpace(B); + + // Check that the address spaces match and that the pointers are valid. + if (!PtrA || !PtrB || (ASA != ASB)) + return false; + + // Make sure that A and B are different pointers of the same size type. + unsigned PtrBitWidth = DL.getPointerSizeInBits(ASA); + Type *PtrATy = PtrA->getType()->getPointerElementType(); + Type *PtrBTy = PtrB->getType()->getPointerElementType(); + if (PtrA == PtrB || + DL.getTypeStoreSize(PtrATy) != DL.getTypeStoreSize(PtrBTy) || + DL.getTypeStoreSize(PtrATy->getScalarType()) != + DL.getTypeStoreSize(PtrBTy->getScalarType())) + return false; + + APInt Size(PtrBitWidth, DL.getTypeStoreSize(PtrATy)); + + APInt OffsetA(PtrBitWidth, 0), OffsetB(PtrBitWidth, 0); + PtrA = PtrA->stripAndAccumulateInBoundsConstantOffsets(DL, OffsetA); + PtrB = PtrB->stripAndAccumulateInBoundsConstantOffsets(DL, OffsetB); + + APInt OffsetDelta = OffsetB - OffsetA; + + // Check if they are based on the same pointer. That makes the offsets + // sufficient. + if (PtrA == PtrB) + return OffsetDelta == Size; + + // Compute the necessary base pointer delta to have the necessary final delta + // equal to the size. + APInt BaseDelta = Size - OffsetDelta; + + // Compute the distance with SCEV between the base pointers. + const SCEV *PtrSCEVA = SE.getSCEV(PtrA); + const SCEV *PtrSCEVB = SE.getSCEV(PtrB); + const SCEV *C = SE.getConstant(BaseDelta); + const SCEV *X = SE.getAddExpr(PtrSCEVA, C); + if (X == PtrSCEVB) + return true; + + // Sometimes even this doesn't work, because SCEV can't always see through + // patterns that look like (gep (ext (add (shl X, C1), C2))). Try checking + // things the hard way. + + // Look through GEPs after checking they're the same except for the last + // index. + GetElementPtrInst *GEPA = dyn_cast<GetElementPtrInst>(getPointerOperand(A)); + GetElementPtrInst *GEPB = dyn_cast<GetElementPtrInst>(getPointerOperand(B)); + if (!GEPA || !GEPB || GEPA->getNumOperands() != GEPB->getNumOperands()) + return false; + unsigned FinalIndex = GEPA->getNumOperands() - 1; + for (unsigned i = 0; i < FinalIndex; i++) + if (GEPA->getOperand(i) != GEPB->getOperand(i)) + return false; + + Instruction *OpA = dyn_cast<Instruction>(GEPA->getOperand(FinalIndex)); + Instruction *OpB = dyn_cast<Instruction>(GEPB->getOperand(FinalIndex)); + if (!OpA || !OpB || OpA->getOpcode() != OpB->getOpcode() || + OpA->getType() != OpB->getType()) + return false; + + // Only look through a ZExt/SExt. + if (!isa<SExtInst>(OpA) && !isa<ZExtInst>(OpA)) + return false; + + bool Signed = isa<SExtInst>(OpA); + + OpA = dyn_cast<Instruction>(OpA->getOperand(0)); + OpB = dyn_cast<Instruction>(OpB->getOperand(0)); + if (!OpA || !OpB || OpA->getType() != OpB->getType()) + return false; + + // Now we need to prove that adding 1 to OpA won't overflow. + bool Safe = false; + // First attempt: if OpB is an add with NSW/NUW, and OpB is 1 added to OpA, + // we're okay. + if (OpB->getOpcode() == Instruction::Add && + isa<ConstantInt>(OpB->getOperand(1)) && + cast<ConstantInt>(OpB->getOperand(1))->getSExtValue() > 0) { + if (Signed) + Safe = cast<BinaryOperator>(OpB)->hasNoSignedWrap(); + else + Safe = cast<BinaryOperator>(OpB)->hasNoUnsignedWrap(); + } + + unsigned BitWidth = OpA->getType()->getScalarSizeInBits(); + + // Second attempt: + // If any bits are known to be zero other than the sign bit in OpA, we can + // add 1 to it while guaranteeing no overflow of any sort. + if (!Safe) { + APInt KnownZero(BitWidth, 0); + APInt KnownOne(BitWidth, 0); + computeKnownBits(OpA, KnownZero, KnownOne, DL, 0, nullptr, OpA, &DT); + KnownZero &= ~APInt::getHighBitsSet(BitWidth, 1); + if (KnownZero != 0) + Safe = true; + } + + if (!Safe) + return false; + + const SCEV *OffsetSCEVA = SE.getSCEV(OpA); + const SCEV *OffsetSCEVB = SE.getSCEV(OpB); + const SCEV *One = SE.getConstant(APInt(BitWidth, 1)); + const SCEV *X2 = SE.getAddExpr(OffsetSCEVA, One); + return X2 == OffsetSCEVB; +} + +void Vectorizer::reorder(Instruction *I) { + SmallPtrSet<Instruction *, 16> InstructionsToMove; + SmallVector<Instruction *, 16> Worklist; + + Worklist.push_back(I); + while (!Worklist.empty()) { + Instruction *IW = Worklist.pop_back_val(); + int NumOperands = IW->getNumOperands(); + for (int i = 0; i < NumOperands; i++) { + Instruction *IM = dyn_cast<Instruction>(IW->getOperand(i)); + if (!IM || IM->getOpcode() == Instruction::PHI) + continue; + + if (!DT.dominates(IM, I)) { + InstructionsToMove.insert(IM); + Worklist.push_back(IM); + assert(IM->getParent() == IW->getParent() && + "Instructions to move should be in the same basic block"); + } + } + } + + // All instructions to move should follow I. Start from I, not from begin(). + for (auto BBI = I->getIterator(), E = I->getParent()->end(); BBI != E; + ++BBI) { + if (!is_contained(InstructionsToMove, &*BBI)) + continue; + Instruction *IM = &*BBI; + --BBI; + IM->removeFromParent(); + IM->insertBefore(I); + } +} + +std::pair<BasicBlock::iterator, BasicBlock::iterator> +Vectorizer::getBoundaryInstrs(ArrayRef<Value *> Chain) { + Instruction *C0 = cast<Instruction>(Chain[0]); + BasicBlock::iterator FirstInstr = C0->getIterator(); + BasicBlock::iterator LastInstr = C0->getIterator(); + + BasicBlock *BB = C0->getParent(); + unsigned NumFound = 0; + for (Instruction &I : *BB) { + if (!is_contained(Chain, &I)) + continue; + + ++NumFound; + if (NumFound == 1) { + FirstInstr = I.getIterator(); + } + if (NumFound == Chain.size()) { + LastInstr = I.getIterator(); + break; + } + } + + // Range is [first, last). + return std::make_pair(FirstInstr, ++LastInstr); +} + +void Vectorizer::eraseInstructions(ArrayRef<Value *> Chain) { + SmallVector<Instruction *, 16> Instrs; + for (Value *V : Chain) { + Value *PtrOperand = getPointerOperand(V); + assert(PtrOperand && "Instruction must have a pointer operand."); + Instrs.push_back(cast<Instruction>(V)); + if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(PtrOperand)) + Instrs.push_back(GEP); + } + + // Erase instructions. + for (Value *V : Instrs) { + Instruction *Instr = cast<Instruction>(V); + if (Instr->use_empty()) + Instr->eraseFromParent(); + } +} + +std::pair<ArrayRef<Value *>, ArrayRef<Value *>> +Vectorizer::splitOddVectorElts(ArrayRef<Value *> Chain, + unsigned ElementSizeBits) { + unsigned ElemSizeInBytes = ElementSizeBits / 8; + unsigned SizeInBytes = ElemSizeInBytes * Chain.size(); + unsigned NumRight = (SizeInBytes % 4) / ElemSizeInBytes; + unsigned NumLeft = Chain.size() - NumRight; + return std::make_pair(Chain.slice(0, NumLeft), Chain.slice(NumLeft)); +} + +unsigned Vectorizer::getVectorizablePrefixEndIdx(ArrayRef<Value *> Chain, + BasicBlock::iterator From, + BasicBlock::iterator To) { + SmallVector<std::pair<Value *, unsigned>, 16> MemoryInstrs; + SmallVector<std::pair<Value *, unsigned>, 16> ChainInstrs; + + unsigned InstrIdx = 0; + for (auto I = From; I != To; ++I, ++InstrIdx) { + if (isa<LoadInst>(I) || isa<StoreInst>(I)) { + if (!is_contained(Chain, &*I)) + MemoryInstrs.push_back({&*I, InstrIdx}); + else + ChainInstrs.push_back({&*I, InstrIdx}); + } else if (I->mayHaveSideEffects()) { + DEBUG(dbgs() << "LSV: Found side-effecting operation: " << *I << '\n'); + return 0; + } + } + + assert(Chain.size() == ChainInstrs.size() && + "All instructions in the Chain must exist in [From, To)."); + + unsigned ChainIdx = 0; + for (auto EntryChain : ChainInstrs) { + Value *ChainInstrValue = EntryChain.first; + unsigned ChainInstrIdx = EntryChain.second; + for (auto EntryMem : MemoryInstrs) { + Value *MemInstrValue = EntryMem.first; + unsigned MemInstrIdx = EntryMem.second; + if (isa<LoadInst>(MemInstrValue) && isa<LoadInst>(ChainInstrValue)) + continue; + + // We can ignore the alias as long as the load comes before the store, + // because that means we won't be moving the load past the store to + // vectorize it (the vectorized load is inserted at the location of the + // first load in the chain). + if (isa<StoreInst>(MemInstrValue) && isa<LoadInst>(ChainInstrValue) && + ChainInstrIdx < MemInstrIdx) + continue; + + // Same case, but in reverse. + if (isa<LoadInst>(MemInstrValue) && isa<StoreInst>(ChainInstrValue) && + ChainInstrIdx > MemInstrIdx) + continue; + + Instruction *M0 = cast<Instruction>(MemInstrValue); + Instruction *M1 = cast<Instruction>(ChainInstrValue); + + if (!AA.isNoAlias(MemoryLocation::get(M0), MemoryLocation::get(M1))) { + DEBUG({ + Value *Ptr0 = getPointerOperand(M0); + Value *Ptr1 = getPointerOperand(M1); + + dbgs() << "LSV: Found alias.\n" + " Aliasing instruction and pointer:\n" + << *MemInstrValue << " aliases " << *Ptr0 << '\n' + << " Aliased instruction and pointer:\n" + << *ChainInstrValue << " aliases " << *Ptr1 << '\n'; + }); + + return ChainIdx; + } + } + ChainIdx++; + } + return Chain.size(); +} + +void Vectorizer::collectInstructions(BasicBlock *BB) { + LoadRefs.clear(); + StoreRefs.clear(); + + for (Instruction &I : *BB) { + if (!I.mayReadOrWriteMemory()) + continue; + + if (LoadInst *LI = dyn_cast<LoadInst>(&I)) { + if (!LI->isSimple()) + continue; + + Type *Ty = LI->getType(); + if (!VectorType::isValidElementType(Ty->getScalarType())) + continue; + + // Skip weird non-byte sizes. They probably aren't worth the effort of + // handling correctly. + unsigned TySize = DL.getTypeSizeInBits(Ty); + if (TySize < 8) + continue; + + Value *Ptr = LI->getPointerOperand(); + unsigned AS = Ptr->getType()->getPointerAddressSpace(); + unsigned VecRegSize = TTI.getLoadStoreVecRegBitWidth(AS); + + // No point in looking at these if they're too big to vectorize. + if (TySize > VecRegSize / 2) + continue; + + // Make sure all the users of a vector are constant-index extracts. + if (isa<VectorType>(Ty) && !all_of(LI->users(), [LI](const User *U) { + const Instruction *UI = cast<Instruction>(U); + return isa<ExtractElementInst>(UI) && + isa<ConstantInt>(UI->getOperand(1)); + })) + continue; + + // TODO: Target hook to filter types. + + // Save the load locations. + Value *ObjPtr = GetUnderlyingObject(Ptr, DL); + LoadRefs[ObjPtr].push_back(LI); + + } else if (StoreInst *SI = dyn_cast<StoreInst>(&I)) { + if (!SI->isSimple()) + continue; + + Type *Ty = SI->getValueOperand()->getType(); + if (!VectorType::isValidElementType(Ty->getScalarType())) + continue; + + // Skip weird non-byte sizes. They probably aren't worth the effort of + // handling correctly. + unsigned TySize = DL.getTypeSizeInBits(Ty); + if (TySize < 8) + continue; + + Value *Ptr = SI->getPointerOperand(); + unsigned AS = Ptr->getType()->getPointerAddressSpace(); + unsigned VecRegSize = TTI.getLoadStoreVecRegBitWidth(AS); + if (TySize > VecRegSize / 2) + continue; + + if (isa<VectorType>(Ty) && !all_of(SI->users(), [SI](const User *U) { + const Instruction *UI = cast<Instruction>(U); + return isa<ExtractElementInst>(UI) && + isa<ConstantInt>(UI->getOperand(1)); + })) + continue; + + // Save store location. + Value *ObjPtr = GetUnderlyingObject(Ptr, DL); + StoreRefs[ObjPtr].push_back(SI); + } + } +} + +bool Vectorizer::vectorizeChains(ValueListMap &Map) { + bool Changed = false; + + for (const std::pair<Value *, ValueList> &Chain : Map) { + unsigned Size = Chain.second.size(); + if (Size < 2) + continue; + + DEBUG(dbgs() << "LSV: Analyzing a chain of length " << Size << ".\n"); + + // Process the stores in chunks of 64. + for (unsigned CI = 0, CE = Size; CI < CE; CI += 64) { + unsigned Len = std::min<unsigned>(CE - CI, 64); + ArrayRef<Value *> Chunk(&Chain.second[CI], Len); + Changed |= vectorizeInstructions(Chunk); + } + } + + return Changed; +} + +bool Vectorizer::vectorizeInstructions(ArrayRef<Value *> Instrs) { + DEBUG(dbgs() << "LSV: Vectorizing " << Instrs.size() << " instructions.\n"); + SmallSetVector<int, 16> Heads, Tails; + int ConsecutiveChain[64]; + + // Do a quadratic search on all of the given stores and find all of the pairs + // of stores that follow each other. + for (int i = 0, e = Instrs.size(); i < e; ++i) { + ConsecutiveChain[i] = -1; + for (int j = e - 1; j >= 0; --j) { + if (i == j) + continue; + + if (isConsecutiveAccess(Instrs[i], Instrs[j])) { + if (ConsecutiveChain[i] != -1) { + int CurDistance = std::abs(ConsecutiveChain[i] - i); + int NewDistance = std::abs(ConsecutiveChain[i] - j); + if (j < i || NewDistance > CurDistance) + continue; // Should not insert. + } + + Tails.insert(j); + Heads.insert(i); + ConsecutiveChain[i] = j; + } + } + } + + bool Changed = false; + SmallPtrSet<Value *, 16> InstructionsProcessed; + + for (int Head : Heads) { + if (InstructionsProcessed.count(Instrs[Head])) + continue; + bool longerChainExists = false; + for (unsigned TIt = 0; TIt < Tails.size(); TIt++) + if (Head == Tails[TIt] && + !InstructionsProcessed.count(Instrs[Heads[TIt]])) { + longerChainExists = true; + break; + } + if (longerChainExists) + continue; + + // We found an instr that starts a chain. Now follow the chain and try to + // vectorize it. + SmallVector<Value *, 16> Operands; + int I = Head; + while (I != -1 && (Tails.count(I) || Heads.count(I))) { + if (InstructionsProcessed.count(Instrs[I])) + break; + + Operands.push_back(Instrs[I]); + I = ConsecutiveChain[I]; + } + + bool Vectorized = false; + if (isa<LoadInst>(*Operands.begin())) + Vectorized = vectorizeLoadChain(Operands, &InstructionsProcessed); + else + Vectorized = vectorizeStoreChain(Operands, &InstructionsProcessed); + + Changed |= Vectorized; + } + + return Changed; +} + +bool Vectorizer::vectorizeStoreChain( + ArrayRef<Value *> Chain, SmallPtrSet<Value *, 16> *InstructionsProcessed) { + StoreInst *S0 = cast<StoreInst>(Chain[0]); + + // If the vector has an int element, default to int for the whole load. + Type *StoreTy; + for (const auto &V : Chain) { + StoreTy = cast<StoreInst>(V)->getValueOperand()->getType(); + if (StoreTy->isIntOrIntVectorTy()) + break; + + if (StoreTy->isPtrOrPtrVectorTy()) { + StoreTy = Type::getIntNTy(F.getParent()->getContext(), + DL.getTypeSizeInBits(StoreTy)); + break; + } + } + + unsigned Sz = DL.getTypeSizeInBits(StoreTy); + unsigned AS = S0->getPointerAddressSpace(); + unsigned VecRegSize = TTI.getLoadStoreVecRegBitWidth(AS); + unsigned VF = VecRegSize / Sz; + unsigned ChainSize = Chain.size(); + + if (!isPowerOf2_32(Sz) || VF < 2 || ChainSize < 2) { + InstructionsProcessed->insert(Chain.begin(), Chain.end()); + return false; + } + + BasicBlock::iterator First, Last; + std::tie(First, Last) = getBoundaryInstrs(Chain); + unsigned StopChain = getVectorizablePrefixEndIdx(Chain, First, Last); + if (StopChain == 0) { + // There exists a side effect instruction, no vectorization possible. + InstructionsProcessed->insert(Chain.begin(), Chain.end()); + return false; + } + if (StopChain == 1) { + // Failed after the first instruction. Discard it and try the smaller chain. + InstructionsProcessed->insert(Chain.front()); + return false; + } + + // Update Chain to the valid vectorizable subchain. + Chain = Chain.slice(0, StopChain); + ChainSize = Chain.size(); + + // Store size should be 1B, 2B or multiple of 4B. + // TODO: Target hook for size constraint? + unsigned SzInBytes = (Sz / 8) * ChainSize; + if (SzInBytes > 2 && SzInBytes % 4 != 0) { + DEBUG(dbgs() << "LSV: Size should be 1B, 2B " + "or multiple of 4B. Splitting.\n"); + if (SzInBytes == 3) + return vectorizeStoreChain(Chain.slice(0, ChainSize - 1), + InstructionsProcessed); + + auto Chains = splitOddVectorElts(Chain, Sz); + return vectorizeStoreChain(Chains.first, InstructionsProcessed) | + vectorizeStoreChain(Chains.second, InstructionsProcessed); + } + + VectorType *VecTy; + VectorType *VecStoreTy = dyn_cast<VectorType>(StoreTy); + if (VecStoreTy) + VecTy = VectorType::get(StoreTy->getScalarType(), + Chain.size() * VecStoreTy->getNumElements()); + else + VecTy = VectorType::get(StoreTy, Chain.size()); + + // If it's more than the max vector size, break it into two pieces. + // TODO: Target hook to control types to split to. + if (ChainSize > VF) { + DEBUG(dbgs() << "LSV: Vector factor is too big." + " Creating two separate arrays.\n"); + return vectorizeStoreChain(Chain.slice(0, VF), InstructionsProcessed) | + vectorizeStoreChain(Chain.slice(VF), InstructionsProcessed); + } + + DEBUG({ + dbgs() << "LSV: Stores to vectorize:\n"; + for (Value *V : Chain) + V->dump(); + }); + + // We won't try again to vectorize the elements of the chain, regardless of + // whether we succeed below. + InstructionsProcessed->insert(Chain.begin(), Chain.end()); + + // Check alignment restrictions. + unsigned Alignment = getAlignment(S0); + + // If the store is going to be misaligned, don't vectorize it. + if (accessIsMisaligned(SzInBytes, AS, Alignment)) { + if (S0->getPointerAddressSpace() != 0) + return false; + + // If we're storing to an object on the stack, we control its alignment, + // so we can cheat and change it! + Value *V = GetUnderlyingObject(S0->getPointerOperand(), DL); + if (AllocaInst *AI = dyn_cast_or_null<AllocaInst>(V)) { + AI->setAlignment(TargetBaseAlign); + Alignment = TargetBaseAlign; + } else { + return false; + } + } + + // Set insert point. + Builder.SetInsertPoint(&*Last); + + Value *Vec = UndefValue::get(VecTy); + + if (VecStoreTy) { + unsigned VecWidth = VecStoreTy->getNumElements(); + for (unsigned I = 0, E = Chain.size(); I != E; ++I) { + StoreInst *Store = cast<StoreInst>(Chain[I]); + for (unsigned J = 0, NE = VecStoreTy->getNumElements(); J != NE; ++J) { + unsigned NewIdx = J + I * VecWidth; + Value *Extract = Builder.CreateExtractElement(Store->getValueOperand(), + Builder.getInt32(J)); + if (Extract->getType() != StoreTy->getScalarType()) + Extract = Builder.CreateBitCast(Extract, StoreTy->getScalarType()); + + Value *Insert = + Builder.CreateInsertElement(Vec, Extract, Builder.getInt32(NewIdx)); + Vec = Insert; + } + } + } else { + for (unsigned I = 0, E = Chain.size(); I != E; ++I) { + StoreInst *Store = cast<StoreInst>(Chain[I]); + Value *Extract = Store->getValueOperand(); + if (Extract->getType() != StoreTy->getScalarType()) + Extract = + Builder.CreateBitOrPointerCast(Extract, StoreTy->getScalarType()); + + Value *Insert = + Builder.CreateInsertElement(Vec, Extract, Builder.getInt32(I)); + Vec = Insert; + } + } + + Value *Bitcast = + Builder.CreateBitCast(S0->getPointerOperand(), VecTy->getPointerTo(AS)); + StoreInst *SI = cast<StoreInst>(Builder.CreateStore(Vec, Bitcast)); + propagateMetadata(SI, Chain); + SI->setAlignment(Alignment); + + eraseInstructions(Chain); + ++NumVectorInstructions; + NumScalarsVectorized += Chain.size(); + return true; +} + +bool Vectorizer::vectorizeLoadChain( + ArrayRef<Value *> Chain, SmallPtrSet<Value *, 16> *InstructionsProcessed) { + LoadInst *L0 = cast<LoadInst>(Chain[0]); + + // If the vector has an int element, default to int for the whole load. + Type *LoadTy; + for (const auto &V : Chain) { + LoadTy = cast<LoadInst>(V)->getType(); + if (LoadTy->isIntOrIntVectorTy()) + break; + + if (LoadTy->isPtrOrPtrVectorTy()) { + LoadTy = Type::getIntNTy(F.getParent()->getContext(), + DL.getTypeSizeInBits(LoadTy)); + break; + } + } + + unsigned Sz = DL.getTypeSizeInBits(LoadTy); + unsigned AS = L0->getPointerAddressSpace(); + unsigned VecRegSize = TTI.getLoadStoreVecRegBitWidth(AS); + unsigned VF = VecRegSize / Sz; + unsigned ChainSize = Chain.size(); + + if (!isPowerOf2_32(Sz) || VF < 2 || ChainSize < 2) { + InstructionsProcessed->insert(Chain.begin(), Chain.end()); + return false; + } + + BasicBlock::iterator First, Last; + std::tie(First, Last) = getBoundaryInstrs(Chain); + unsigned StopChain = getVectorizablePrefixEndIdx(Chain, First, Last); + if (StopChain == 0) { + // There exists a side effect instruction, no vectorization possible. + InstructionsProcessed->insert(Chain.begin(), Chain.end()); + return false; + } + if (StopChain == 1) { + // Failed after the first instruction. Discard it and try the smaller chain. + InstructionsProcessed->insert(Chain.front()); + return false; + } + + // Update Chain to the valid vectorizable subchain. + Chain = Chain.slice(0, StopChain); + ChainSize = Chain.size(); + + // Load size should be 1B, 2B or multiple of 4B. + // TODO: Should size constraint be a target hook? + unsigned SzInBytes = (Sz / 8) * ChainSize; + if (SzInBytes > 2 && SzInBytes % 4 != 0) { + DEBUG(dbgs() << "LSV: Size should be 1B, 2B " + "or multiple of 4B. Splitting.\n"); + if (SzInBytes == 3) + return vectorizeLoadChain(Chain.slice(0, ChainSize - 1), + InstructionsProcessed); + auto Chains = splitOddVectorElts(Chain, Sz); + return vectorizeLoadChain(Chains.first, InstructionsProcessed) | + vectorizeLoadChain(Chains.second, InstructionsProcessed); + } + + VectorType *VecTy; + VectorType *VecLoadTy = dyn_cast<VectorType>(LoadTy); + if (VecLoadTy) + VecTy = VectorType::get(LoadTy->getScalarType(), + Chain.size() * VecLoadTy->getNumElements()); + else + VecTy = VectorType::get(LoadTy, Chain.size()); + + // If it's more than the max vector size, break it into two pieces. + // TODO: Target hook to control types to split to. + if (ChainSize > VF) { + DEBUG(dbgs() << "LSV: Vector factor is too big. " + "Creating two separate arrays.\n"); + return vectorizeLoadChain(Chain.slice(0, VF), InstructionsProcessed) | + vectorizeLoadChain(Chain.slice(VF), InstructionsProcessed); + } + + // We won't try again to vectorize the elements of the chain, regardless of + // whether we succeed below. + InstructionsProcessed->insert(Chain.begin(), Chain.end()); + + // Check alignment restrictions. + unsigned Alignment = getAlignment(L0); + + // If the load is going to be misaligned, don't vectorize it. + if (accessIsMisaligned(SzInBytes, AS, Alignment)) { + if (L0->getPointerAddressSpace() != 0) + return false; + + // If we're loading from an object on the stack, we control its alignment, + // so we can cheat and change it! + Value *V = GetUnderlyingObject(L0->getPointerOperand(), DL); + if (AllocaInst *AI = dyn_cast_or_null<AllocaInst>(V)) { + AI->setAlignment(TargetBaseAlign); + Alignment = TargetBaseAlign; + } else { + return false; + } + } + + DEBUG({ + dbgs() << "LSV: Loads to vectorize:\n"; + for (Value *V : Chain) + V->dump(); + }); + + // Set insert point. + Builder.SetInsertPoint(&*First); + + Value *Bitcast = + Builder.CreateBitCast(L0->getPointerOperand(), VecTy->getPointerTo(AS)); + + LoadInst *LI = cast<LoadInst>(Builder.CreateLoad(Bitcast)); + propagateMetadata(LI, Chain); + LI->setAlignment(Alignment); + + if (VecLoadTy) { + SmallVector<Instruction *, 16> InstrsToErase; + SmallVector<Instruction *, 16> InstrsToReorder; + InstrsToReorder.push_back(cast<Instruction>(Bitcast)); + + unsigned VecWidth = VecLoadTy->getNumElements(); + for (unsigned I = 0, E = Chain.size(); I != E; ++I) { + for (auto Use : Chain[I]->users()) { + Instruction *UI = cast<Instruction>(Use); + unsigned Idx = cast<ConstantInt>(UI->getOperand(1))->getZExtValue(); + unsigned NewIdx = Idx + I * VecWidth; + Value *V = Builder.CreateExtractElement(LI, Builder.getInt32(NewIdx)); + Instruction *Extracted = cast<Instruction>(V); + if (Extracted->getType() != UI->getType()) + Extracted = cast<Instruction>( + Builder.CreateBitCast(Extracted, UI->getType())); + + // Replace the old instruction. + UI->replaceAllUsesWith(Extracted); + InstrsToErase.push_back(UI); + } + } + + for (Instruction *ModUser : InstrsToReorder) + reorder(ModUser); + + for (auto I : InstrsToErase) + I->eraseFromParent(); + } else { + SmallVector<Instruction *, 16> InstrsToReorder; + InstrsToReorder.push_back(cast<Instruction>(Bitcast)); + + for (unsigned I = 0, E = Chain.size(); I != E; ++I) { + Value *V = Builder.CreateExtractElement(LI, Builder.getInt32(I)); + Instruction *Extracted = cast<Instruction>(V); + Instruction *UI = cast<Instruction>(Chain[I]); + if (Extracted->getType() != UI->getType()) { + Extracted = cast<Instruction>( + Builder.CreateBitOrPointerCast(Extracted, UI->getType())); + } + + // Replace the old instruction. + UI->replaceAllUsesWith(Extracted); + } + + for (Instruction *ModUser : InstrsToReorder) + reorder(ModUser); + } + + eraseInstructions(Chain); + + ++NumVectorInstructions; + NumScalarsVectorized += Chain.size(); + return true; +} + +bool Vectorizer::accessIsMisaligned(unsigned SzInBytes, unsigned AddressSpace, + unsigned Alignment) { + bool Fast = false; + bool Allows = TTI.allowsMisalignedMemoryAccesses(SzInBytes * 8, AddressSpace, + Alignment, &Fast); + // TODO: Remove TargetBaseAlign + return !(Allows && Fast) && (Alignment % SzInBytes) != 0 && + (Alignment % TargetBaseAlign) != 0; +} |