Mercurial > hg > Members > tobaru > cbc > CbC_llvm
view lib/Transforms/Scalar/Scalarizer.cpp @ 83:60c9769439b8
LLVM 3.7
author | Tatsuki IHA <e125716@ie.u-ryukyu.ac.jp> |
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date | Wed, 18 Feb 2015 14:55:36 +0900 |
parents | 54457678186b |
children | afa8332a0e37 |
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//===--- Scalarizer.cpp - Scalarize vector operations ---------------------===// // // The LLVM Compiler Infrastructure // // This file is distributed under the University of Illinois Open Source // License. See LICENSE.TXT for details. // //===----------------------------------------------------------------------===// // // This pass converts vector operations into scalar operations, in order // to expose optimization opportunities on the individual scalar operations. // It is mainly intended for targets that do not have vector units, but it // may also be useful for revectorizing code to different vector widths. // //===----------------------------------------------------------------------===// #include "llvm/ADT/STLExtras.h" #include "llvm/IR/IRBuilder.h" #include "llvm/IR/InstVisitor.h" #include "llvm/Pass.h" #include "llvm/Support/CommandLine.h" #include "llvm/Transforms/Scalar.h" #include "llvm/Transforms/Utils/BasicBlockUtils.h" using namespace llvm; #define DEBUG_TYPE "scalarizer" namespace { // Used to store the scattered form of a vector. typedef SmallVector<Value *, 8> ValueVector; // Used to map a vector Value to its scattered form. We use std::map // because we want iterators to persist across insertion and because the // values are relatively large. typedef std::map<Value *, ValueVector> ScatterMap; // Lists Instructions that have been replaced with scalar implementations, // along with a pointer to their scattered forms. typedef SmallVector<std::pair<Instruction *, ValueVector *>, 16> GatherList; // Provides a very limited vector-like interface for lazily accessing one // component of a scattered vector or vector pointer. class Scatterer { public: Scatterer() {} // Scatter V into Size components. If new instructions are needed, // insert them before BBI in BB. If Cache is nonnull, use it to cache // the results. Scatterer(BasicBlock *bb, BasicBlock::iterator bbi, Value *v, ValueVector *cachePtr = nullptr); // Return component I, creating a new Value for it if necessary. Value *operator[](unsigned I); // Return the number of components. unsigned size() const { return Size; } private: BasicBlock *BB; BasicBlock::iterator BBI; Value *V; ValueVector *CachePtr; PointerType *PtrTy; ValueVector Tmp; unsigned Size; }; // FCmpSpliiter(FCI)(Builder, X, Y, Name) uses Builder to create an FCmp // called Name that compares X and Y in the same way as FCI. struct FCmpSplitter { FCmpSplitter(FCmpInst &fci) : FCI(fci) {} Value *operator()(IRBuilder<> &Builder, Value *Op0, Value *Op1, const Twine &Name) const { return Builder.CreateFCmp(FCI.getPredicate(), Op0, Op1, Name); } FCmpInst &FCI; }; // ICmpSpliiter(ICI)(Builder, X, Y, Name) uses Builder to create an ICmp // called Name that compares X and Y in the same way as ICI. struct ICmpSplitter { ICmpSplitter(ICmpInst &ici) : ICI(ici) {} Value *operator()(IRBuilder<> &Builder, Value *Op0, Value *Op1, const Twine &Name) const { return Builder.CreateICmp(ICI.getPredicate(), Op0, Op1, Name); } ICmpInst &ICI; }; // BinarySpliiter(BO)(Builder, X, Y, Name) uses Builder to create // a binary operator like BO called Name with operands X and Y. struct BinarySplitter { BinarySplitter(BinaryOperator &bo) : BO(bo) {} Value *operator()(IRBuilder<> &Builder, Value *Op0, Value *Op1, const Twine &Name) const { return Builder.CreateBinOp(BO.getOpcode(), Op0, Op1, Name); } BinaryOperator &BO; }; // Information about a load or store that we're scalarizing. struct VectorLayout { VectorLayout() : VecTy(nullptr), ElemTy(nullptr), VecAlign(0), ElemSize(0) {} // Return the alignment of element I. uint64_t getElemAlign(unsigned I) { return MinAlign(VecAlign, I * ElemSize); } // The type of the vector. VectorType *VecTy; // The type of each element. Type *ElemTy; // The alignment of the vector. uint64_t VecAlign; // The size of each element. uint64_t ElemSize; }; class Scalarizer : public FunctionPass, public InstVisitor<Scalarizer, bool> { public: static char ID; Scalarizer() : FunctionPass(ID) { initializeScalarizerPass(*PassRegistry::getPassRegistry()); } bool doInitialization(Module &M) override; bool runOnFunction(Function &F) override; // InstVisitor methods. They return true if the instruction was scalarized, // false if nothing changed. bool visitInstruction(Instruction &) { return false; } bool visitSelectInst(SelectInst &SI); bool visitICmpInst(ICmpInst &); bool visitFCmpInst(FCmpInst &); bool visitBinaryOperator(BinaryOperator &); bool visitGetElementPtrInst(GetElementPtrInst &); bool visitCastInst(CastInst &); bool visitBitCastInst(BitCastInst &); bool visitShuffleVectorInst(ShuffleVectorInst &); bool visitPHINode(PHINode &); bool visitLoadInst(LoadInst &); bool visitStoreInst(StoreInst &); static void registerOptions() { // This is disabled by default because having separate loads and stores // makes it more likely that the -combiner-alias-analysis limits will be // reached. OptionRegistry::registerOption<bool, Scalarizer, &Scalarizer::ScalarizeLoadStore>( "scalarize-load-store", "Allow the scalarizer pass to scalarize loads and store", false); } private: Scatterer scatter(Instruction *, Value *); void gather(Instruction *, const ValueVector &); bool canTransferMetadata(unsigned Kind); void transferMetadata(Instruction *, const ValueVector &); bool getVectorLayout(Type *, unsigned, VectorLayout &); bool finish(); template<typename T> bool splitBinary(Instruction &, const T &); ScatterMap Scattered; GatherList Gathered; unsigned ParallelLoopAccessMDKind; const DataLayout *DL; bool ScalarizeLoadStore; }; char Scalarizer::ID = 0; } // end anonymous namespace INITIALIZE_PASS_WITH_OPTIONS(Scalarizer, "scalarizer", "Scalarize vector operations", false, false) Scatterer::Scatterer(BasicBlock *bb, BasicBlock::iterator bbi, Value *v, ValueVector *cachePtr) : BB(bb), BBI(bbi), V(v), CachePtr(cachePtr) { Type *Ty = V->getType(); PtrTy = dyn_cast<PointerType>(Ty); if (PtrTy) Ty = PtrTy->getElementType(); Size = Ty->getVectorNumElements(); if (!CachePtr) Tmp.resize(Size, nullptr); else if (CachePtr->empty()) CachePtr->resize(Size, nullptr); else assert(Size == CachePtr->size() && "Inconsistent vector sizes"); } // Return component I, creating a new Value for it if necessary. Value *Scatterer::operator[](unsigned I) { ValueVector &CV = (CachePtr ? *CachePtr : Tmp); // Try to reuse a previous value. if (CV[I]) return CV[I]; IRBuilder<> Builder(BB, BBI); if (PtrTy) { if (!CV[0]) { Type *Ty = PointerType::get(PtrTy->getElementType()->getVectorElementType(), PtrTy->getAddressSpace()); CV[0] = Builder.CreateBitCast(V, Ty, V->getName() + ".i0"); } if (I != 0) CV[I] = Builder.CreateConstGEP1_32(CV[0], I, V->getName() + ".i" + Twine(I)); } else { // Search through a chain of InsertElementInsts looking for element I. // Record other elements in the cache. The new V is still suitable // for all uncached indices. for (;;) { InsertElementInst *Insert = dyn_cast<InsertElementInst>(V); if (!Insert) break; ConstantInt *Idx = dyn_cast<ConstantInt>(Insert->getOperand(2)); if (!Idx) break; unsigned J = Idx->getZExtValue(); CV[J] = Insert->getOperand(1); V = Insert->getOperand(0); if (I == J) return CV[J]; } CV[I] = Builder.CreateExtractElement(V, Builder.getInt32(I), V->getName() + ".i" + Twine(I)); } return CV[I]; } bool Scalarizer::doInitialization(Module &M) { ParallelLoopAccessMDKind = M.getContext().getMDKindID("llvm.mem.parallel_loop_access"); ScalarizeLoadStore = M.getContext().getOption<bool, Scalarizer, &Scalarizer::ScalarizeLoadStore>(); return false; } bool Scalarizer::runOnFunction(Function &F) { DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>(); DL = DLP ? &DLP->getDataLayout() : nullptr; for (Function::iterator BBI = F.begin(), BBE = F.end(); BBI != BBE; ++BBI) { BasicBlock *BB = BBI; for (BasicBlock::iterator II = BB->begin(), IE = BB->end(); II != IE;) { Instruction *I = II; bool Done = visit(I); ++II; if (Done && I->getType()->isVoidTy()) I->eraseFromParent(); } } return finish(); } // Return a scattered form of V that can be accessed by Point. V must be a // vector or a pointer to a vector. Scatterer Scalarizer::scatter(Instruction *Point, Value *V) { if (Argument *VArg = dyn_cast<Argument>(V)) { // Put the scattered form of arguments in the entry block, // so that it can be used everywhere. Function *F = VArg->getParent(); BasicBlock *BB = &F->getEntryBlock(); return Scatterer(BB, BB->begin(), V, &Scattered[V]); } if (Instruction *VOp = dyn_cast<Instruction>(V)) { // Put the scattered form of an instruction directly after the // instruction. BasicBlock *BB = VOp->getParent(); return Scatterer(BB, std::next(BasicBlock::iterator(VOp)), V, &Scattered[V]); } // In the fallback case, just put the scattered before Point and // keep the result local to Point. return Scatterer(Point->getParent(), Point, V); } // Replace Op with the gathered form of the components in CV. Defer the // deletion of Op and creation of the gathered form to the end of the pass, // so that we can avoid creating the gathered form if all uses of Op are // replaced with uses of CV. void Scalarizer::gather(Instruction *Op, const ValueVector &CV) { // Since we're not deleting Op yet, stub out its operands, so that it // doesn't make anything live unnecessarily. for (unsigned I = 0, E = Op->getNumOperands(); I != E; ++I) Op->setOperand(I, UndefValue::get(Op->getOperand(I)->getType())); transferMetadata(Op, CV); // If we already have a scattered form of Op (created from ExtractElements // of Op itself), replace them with the new form. ValueVector &SV = Scattered[Op]; if (!SV.empty()) { for (unsigned I = 0, E = SV.size(); I != E; ++I) { Instruction *Old = cast<Instruction>(SV[I]); CV[I]->takeName(Old); Old->replaceAllUsesWith(CV[I]); Old->eraseFromParent(); } } SV = CV; Gathered.push_back(GatherList::value_type(Op, &SV)); } // Return true if it is safe to transfer the given metadata tag from // vector to scalar instructions. bool Scalarizer::canTransferMetadata(unsigned Tag) { return (Tag == LLVMContext::MD_tbaa || Tag == LLVMContext::MD_fpmath || Tag == LLVMContext::MD_tbaa_struct || Tag == LLVMContext::MD_invariant_load || Tag == LLVMContext::MD_alias_scope || Tag == LLVMContext::MD_noalias || Tag == ParallelLoopAccessMDKind); } // Transfer metadata from Op to the instructions in CV if it is known // to be safe to do so. void Scalarizer::transferMetadata(Instruction *Op, const ValueVector &CV) { SmallVector<std::pair<unsigned, MDNode *>, 4> MDs; Op->getAllMetadataOtherThanDebugLoc(MDs); for (unsigned I = 0, E = CV.size(); I != E; ++I) { if (Instruction *New = dyn_cast<Instruction>(CV[I])) { for (SmallVectorImpl<std::pair<unsigned, MDNode *>>::iterator MI = MDs.begin(), ME = MDs.end(); MI != ME; ++MI) if (canTransferMetadata(MI->first)) New->setMetadata(MI->first, MI->second); New->setDebugLoc(Op->getDebugLoc()); } } } // Try to fill in Layout from Ty, returning true on success. Alignment is // the alignment of the vector, or 0 if the ABI default should be used. bool Scalarizer::getVectorLayout(Type *Ty, unsigned Alignment, VectorLayout &Layout) { if (!DL) return false; // Make sure we're dealing with a vector. Layout.VecTy = dyn_cast<VectorType>(Ty); if (!Layout.VecTy) return false; // Check that we're dealing with full-byte elements. Layout.ElemTy = Layout.VecTy->getElementType(); if (DL->getTypeSizeInBits(Layout.ElemTy) != DL->getTypeStoreSizeInBits(Layout.ElemTy)) return false; if (Alignment) Layout.VecAlign = Alignment; else Layout.VecAlign = DL->getABITypeAlignment(Layout.VecTy); Layout.ElemSize = DL->getTypeStoreSize(Layout.ElemTy); return true; } // Scalarize two-operand instruction I, using Split(Builder, X, Y, Name) // to create an instruction like I with operands X and Y and name Name. template<typename Splitter> bool Scalarizer::splitBinary(Instruction &I, const Splitter &Split) { VectorType *VT = dyn_cast<VectorType>(I.getType()); if (!VT) return false; unsigned NumElems = VT->getNumElements(); IRBuilder<> Builder(I.getParent(), &I); Scatterer Op0 = scatter(&I, I.getOperand(0)); Scatterer Op1 = scatter(&I, I.getOperand(1)); assert(Op0.size() == NumElems && "Mismatched binary operation"); assert(Op1.size() == NumElems && "Mismatched binary operation"); ValueVector Res; Res.resize(NumElems); for (unsigned Elem = 0; Elem < NumElems; ++Elem) Res[Elem] = Split(Builder, Op0[Elem], Op1[Elem], I.getName() + ".i" + Twine(Elem)); gather(&I, Res); return true; } bool Scalarizer::visitSelectInst(SelectInst &SI) { VectorType *VT = dyn_cast<VectorType>(SI.getType()); if (!VT) return false; unsigned NumElems = VT->getNumElements(); IRBuilder<> Builder(SI.getParent(), &SI); Scatterer Op1 = scatter(&SI, SI.getOperand(1)); Scatterer Op2 = scatter(&SI, SI.getOperand(2)); assert(Op1.size() == NumElems && "Mismatched select"); assert(Op2.size() == NumElems && "Mismatched select"); ValueVector Res; Res.resize(NumElems); if (SI.getOperand(0)->getType()->isVectorTy()) { Scatterer Op0 = scatter(&SI, SI.getOperand(0)); assert(Op0.size() == NumElems && "Mismatched select"); for (unsigned I = 0; I < NumElems; ++I) Res[I] = Builder.CreateSelect(Op0[I], Op1[I], Op2[I], SI.getName() + ".i" + Twine(I)); } else { Value *Op0 = SI.getOperand(0); for (unsigned I = 0; I < NumElems; ++I) Res[I] = Builder.CreateSelect(Op0, Op1[I], Op2[I], SI.getName() + ".i" + Twine(I)); } gather(&SI, Res); return true; } bool Scalarizer::visitICmpInst(ICmpInst &ICI) { return splitBinary(ICI, ICmpSplitter(ICI)); } bool Scalarizer::visitFCmpInst(FCmpInst &FCI) { return splitBinary(FCI, FCmpSplitter(FCI)); } bool Scalarizer::visitBinaryOperator(BinaryOperator &BO) { return splitBinary(BO, BinarySplitter(BO)); } bool Scalarizer::visitGetElementPtrInst(GetElementPtrInst &GEPI) { VectorType *VT = dyn_cast<VectorType>(GEPI.getType()); if (!VT) return false; IRBuilder<> Builder(GEPI.getParent(), &GEPI); unsigned NumElems = VT->getNumElements(); unsigned NumIndices = GEPI.getNumIndices(); Scatterer Base = scatter(&GEPI, GEPI.getOperand(0)); SmallVector<Scatterer, 8> Ops; Ops.resize(NumIndices); for (unsigned I = 0; I < NumIndices; ++I) Ops[I] = scatter(&GEPI, GEPI.getOperand(I + 1)); ValueVector Res; Res.resize(NumElems); for (unsigned I = 0; I < NumElems; ++I) { SmallVector<Value *, 8> Indices; Indices.resize(NumIndices); for (unsigned J = 0; J < NumIndices; ++J) Indices[J] = Ops[J][I]; Res[I] = Builder.CreateGEP(Base[I], Indices, GEPI.getName() + ".i" + Twine(I)); if (GEPI.isInBounds()) if (GetElementPtrInst *NewGEPI = dyn_cast<GetElementPtrInst>(Res[I])) NewGEPI->setIsInBounds(); } gather(&GEPI, Res); return true; } bool Scalarizer::visitCastInst(CastInst &CI) { VectorType *VT = dyn_cast<VectorType>(CI.getDestTy()); if (!VT) return false; unsigned NumElems = VT->getNumElements(); IRBuilder<> Builder(CI.getParent(), &CI); Scatterer Op0 = scatter(&CI, CI.getOperand(0)); assert(Op0.size() == NumElems && "Mismatched cast"); ValueVector Res; Res.resize(NumElems); for (unsigned I = 0; I < NumElems; ++I) Res[I] = Builder.CreateCast(CI.getOpcode(), Op0[I], VT->getElementType(), CI.getName() + ".i" + Twine(I)); gather(&CI, Res); return true; } bool Scalarizer::visitBitCastInst(BitCastInst &BCI) { VectorType *DstVT = dyn_cast<VectorType>(BCI.getDestTy()); VectorType *SrcVT = dyn_cast<VectorType>(BCI.getSrcTy()); if (!DstVT || !SrcVT) return false; unsigned DstNumElems = DstVT->getNumElements(); unsigned SrcNumElems = SrcVT->getNumElements(); IRBuilder<> Builder(BCI.getParent(), &BCI); Scatterer Op0 = scatter(&BCI, BCI.getOperand(0)); ValueVector Res; Res.resize(DstNumElems); if (DstNumElems == SrcNumElems) { for (unsigned I = 0; I < DstNumElems; ++I) Res[I] = Builder.CreateBitCast(Op0[I], DstVT->getElementType(), BCI.getName() + ".i" + Twine(I)); } else if (DstNumElems > SrcNumElems) { // <M x t1> -> <N*M x t2>. Convert each t1 to <N x t2> and copy the // individual elements to the destination. unsigned FanOut = DstNumElems / SrcNumElems; Type *MidTy = VectorType::get(DstVT->getElementType(), FanOut); unsigned ResI = 0; for (unsigned Op0I = 0; Op0I < SrcNumElems; ++Op0I) { Value *V = Op0[Op0I]; Instruction *VI; // Look through any existing bitcasts before converting to <N x t2>. // In the best case, the resulting conversion might be a no-op. while ((VI = dyn_cast<Instruction>(V)) && VI->getOpcode() == Instruction::BitCast) V = VI->getOperand(0); V = Builder.CreateBitCast(V, MidTy, V->getName() + ".cast"); Scatterer Mid = scatter(&BCI, V); for (unsigned MidI = 0; MidI < FanOut; ++MidI) Res[ResI++] = Mid[MidI]; } } else { // <N*M x t1> -> <M x t2>. Convert each group of <N x t1> into a t2. unsigned FanIn = SrcNumElems / DstNumElems; Type *MidTy = VectorType::get(SrcVT->getElementType(), FanIn); unsigned Op0I = 0; for (unsigned ResI = 0; ResI < DstNumElems; ++ResI) { Value *V = UndefValue::get(MidTy); for (unsigned MidI = 0; MidI < FanIn; ++MidI) V = Builder.CreateInsertElement(V, Op0[Op0I++], Builder.getInt32(MidI), BCI.getName() + ".i" + Twine(ResI) + ".upto" + Twine(MidI)); Res[ResI] = Builder.CreateBitCast(V, DstVT->getElementType(), BCI.getName() + ".i" + Twine(ResI)); } } gather(&BCI, Res); return true; } bool Scalarizer::visitShuffleVectorInst(ShuffleVectorInst &SVI) { VectorType *VT = dyn_cast<VectorType>(SVI.getType()); if (!VT) return false; unsigned NumElems = VT->getNumElements(); Scatterer Op0 = scatter(&SVI, SVI.getOperand(0)); Scatterer Op1 = scatter(&SVI, SVI.getOperand(1)); ValueVector Res; Res.resize(NumElems); for (unsigned I = 0; I < NumElems; ++I) { int Selector = SVI.getMaskValue(I); if (Selector < 0) Res[I] = UndefValue::get(VT->getElementType()); else if (unsigned(Selector) < Op0.size()) Res[I] = Op0[Selector]; else Res[I] = Op1[Selector - Op0.size()]; } gather(&SVI, Res); return true; } bool Scalarizer::visitPHINode(PHINode &PHI) { VectorType *VT = dyn_cast<VectorType>(PHI.getType()); if (!VT) return false; unsigned NumElems = VT->getNumElements(); IRBuilder<> Builder(PHI.getParent(), &PHI); ValueVector Res; Res.resize(NumElems); unsigned NumOps = PHI.getNumOperands(); for (unsigned I = 0; I < NumElems; ++I) Res[I] = Builder.CreatePHI(VT->getElementType(), NumOps, PHI.getName() + ".i" + Twine(I)); for (unsigned I = 0; I < NumOps; ++I) { Scatterer Op = scatter(&PHI, PHI.getIncomingValue(I)); BasicBlock *IncomingBlock = PHI.getIncomingBlock(I); for (unsigned J = 0; J < NumElems; ++J) cast<PHINode>(Res[J])->addIncoming(Op[J], IncomingBlock); } gather(&PHI, Res); return true; } bool Scalarizer::visitLoadInst(LoadInst &LI) { if (!ScalarizeLoadStore) return false; if (!LI.isSimple()) return false; VectorLayout Layout; if (!getVectorLayout(LI.getType(), LI.getAlignment(), Layout)) return false; unsigned NumElems = Layout.VecTy->getNumElements(); IRBuilder<> Builder(LI.getParent(), &LI); Scatterer Ptr = scatter(&LI, LI.getPointerOperand()); ValueVector Res; Res.resize(NumElems); for (unsigned I = 0; I < NumElems; ++I) Res[I] = Builder.CreateAlignedLoad(Ptr[I], Layout.getElemAlign(I), LI.getName() + ".i" + Twine(I)); gather(&LI, Res); return true; } bool Scalarizer::visitStoreInst(StoreInst &SI) { if (!ScalarizeLoadStore) return false; if (!SI.isSimple()) return false; VectorLayout Layout; Value *FullValue = SI.getValueOperand(); if (!getVectorLayout(FullValue->getType(), SI.getAlignment(), Layout)) return false; unsigned NumElems = Layout.VecTy->getNumElements(); IRBuilder<> Builder(SI.getParent(), &SI); Scatterer Ptr = scatter(&SI, SI.getPointerOperand()); Scatterer Val = scatter(&SI, FullValue); ValueVector Stores; Stores.resize(NumElems); for (unsigned I = 0; I < NumElems; ++I) { unsigned Align = Layout.getElemAlign(I); Stores[I] = Builder.CreateAlignedStore(Val[I], Ptr[I], Align); } transferMetadata(&SI, Stores); return true; } // Delete the instructions that we scalarized. If a full vector result // is still needed, recreate it using InsertElements. bool Scalarizer::finish() { if (Gathered.empty()) return false; for (GatherList::iterator GMI = Gathered.begin(), GME = Gathered.end(); GMI != GME; ++GMI) { Instruction *Op = GMI->first; ValueVector &CV = *GMI->second; if (!Op->use_empty()) { // The value is still needed, so recreate it using a series of // InsertElements. Type *Ty = Op->getType(); Value *Res = UndefValue::get(Ty); BasicBlock *BB = Op->getParent(); unsigned Count = Ty->getVectorNumElements(); IRBuilder<> Builder(BB, Op); if (isa<PHINode>(Op)) Builder.SetInsertPoint(BB, BB->getFirstInsertionPt()); for (unsigned I = 0; I < Count; ++I) Res = Builder.CreateInsertElement(Res, CV[I], Builder.getInt32(I), Op->getName() + ".upto" + Twine(I)); Res->takeName(Op); Op->replaceAllUsesWith(Res); } Op->eraseFromParent(); } Gathered.clear(); Scattered.clear(); return true; } FunctionPass *llvm::createScalarizerPass() { return new Scalarizer(); }