forked from OSchip/llvm-project
1038 lines
35 KiB
C++
1038 lines
35 KiB
C++
//===----- LoadStoreVectorizer.cpp - GPU Load & Store Vectorizer ----------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/ADT/MapVector.h"
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#include "llvm/ADT/PostOrderIterator.h"
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#include "llvm/ADT/SetVector.h"
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#include "llvm/ADT/Statistic.h"
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#include "llvm/ADT/Triple.h"
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#include "llvm/Analysis/AliasAnalysis.h"
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#include "llvm/Analysis/OrderedBasicBlock.h"
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#include "llvm/Analysis/ScalarEvolution.h"
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#include "llvm/Analysis/ScalarEvolutionExpressions.h"
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#include "llvm/Analysis/TargetTransformInfo.h"
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#include "llvm/Analysis/ValueTracking.h"
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#include "llvm/Analysis/VectorUtils.h"
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#include "llvm/IR/DataLayout.h"
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#include "llvm/IR/Dominators.h"
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#include "llvm/IR/IRBuilder.h"
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#include "llvm/IR/Instructions.h"
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#include "llvm/IR/Module.h"
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#include "llvm/IR/Type.h"
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#include "llvm/IR/Value.h"
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#include "llvm/Support/CommandLine.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/Support/raw_ostream.h"
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#include "llvm/Transforms/Utils/Local.h"
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#include "llvm/Transforms/Vectorize.h"
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using namespace llvm;
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#define DEBUG_TYPE "load-store-vectorizer"
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STATISTIC(NumVectorInstructions, "Number of vector accesses generated");
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STATISTIC(NumScalarsVectorized, "Number of scalar accesses vectorized");
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namespace {
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// FIXME: Assuming stack alignment of 4 is always good enough
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static const unsigned StackAdjustedAlignment = 4;
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typedef SmallVector<Instruction *, 8> InstrList;
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typedef MapVector<Value *, InstrList> InstrListMap;
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class Vectorizer {
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Function &F;
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AliasAnalysis &AA;
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DominatorTree &DT;
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ScalarEvolution &SE;
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TargetTransformInfo &TTI;
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const DataLayout &DL;
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IRBuilder<> Builder;
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public:
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Vectorizer(Function &F, AliasAnalysis &AA, DominatorTree &DT,
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ScalarEvolution &SE, TargetTransformInfo &TTI)
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: F(F), AA(AA), DT(DT), SE(SE), TTI(TTI),
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DL(F.getParent()->getDataLayout()), Builder(SE.getContext()) {}
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bool run();
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private:
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Value *getPointerOperand(Value *I);
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unsigned getPointerAddressSpace(Value *I);
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unsigned getAlignment(LoadInst *LI) const {
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unsigned Align = LI->getAlignment();
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if (Align != 0)
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return Align;
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return DL.getABITypeAlignment(LI->getType());
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}
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unsigned getAlignment(StoreInst *SI) const {
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unsigned Align = SI->getAlignment();
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if (Align != 0)
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return Align;
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return DL.getABITypeAlignment(SI->getValueOperand()->getType());
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}
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bool isConsecutiveAccess(Value *A, Value *B);
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/// After vectorization, reorder the instructions that I depends on
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/// (the instructions defining its operands), to ensure they dominate I.
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void reorder(Instruction *I);
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/// Returns the first and the last instructions in Chain.
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std::pair<BasicBlock::iterator, BasicBlock::iterator>
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getBoundaryInstrs(ArrayRef<Instruction *> Chain);
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/// Erases the original instructions after vectorizing.
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void eraseInstructions(ArrayRef<Instruction *> Chain);
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/// "Legalize" the vector type that would be produced by combining \p
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/// ElementSizeBits elements in \p Chain. Break into two pieces such that the
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/// total size of each piece is 1, 2 or a multiple of 4 bytes. \p Chain is
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/// expected to have more than 4 elements.
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std::pair<ArrayRef<Instruction *>, ArrayRef<Instruction *>>
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splitOddVectorElts(ArrayRef<Instruction *> Chain, unsigned ElementSizeBits);
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/// Finds the largest prefix of Chain that's vectorizable, checking for
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/// intervening instructions which may affect the memory accessed by the
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/// instructions within Chain.
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///
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/// The elements of \p Chain must be all loads or all stores and must be in
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/// address order.
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ArrayRef<Instruction *> getVectorizablePrefix(ArrayRef<Instruction *> Chain);
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/// Collects load and store instructions to vectorize.
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std::pair<InstrListMap, InstrListMap> collectInstructions(BasicBlock *BB);
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/// Processes the collected instructions, the \p Map. The values of \p Map
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/// should be all loads or all stores.
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bool vectorizeChains(InstrListMap &Map);
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/// Finds the load/stores to consecutive memory addresses and vectorizes them.
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bool vectorizeInstructions(ArrayRef<Instruction *> Instrs);
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/// Vectorizes the load instructions in Chain.
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bool
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vectorizeLoadChain(ArrayRef<Instruction *> Chain,
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SmallPtrSet<Instruction *, 16> *InstructionsProcessed);
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/// Vectorizes the store instructions in Chain.
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bool
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vectorizeStoreChain(ArrayRef<Instruction *> Chain,
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SmallPtrSet<Instruction *, 16> *InstructionsProcessed);
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/// Check if this load/store access is misaligned accesses
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bool accessIsMisaligned(unsigned SzInBytes, unsigned AddressSpace,
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unsigned Alignment);
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};
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class LoadStoreVectorizer : public FunctionPass {
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public:
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static char ID;
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LoadStoreVectorizer() : FunctionPass(ID) {
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initializeLoadStoreVectorizerPass(*PassRegistry::getPassRegistry());
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}
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bool runOnFunction(Function &F) override;
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const char *getPassName() const override {
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return "GPU Load and Store Vectorizer";
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}
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void getAnalysisUsage(AnalysisUsage &AU) const override {
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AU.addRequired<AAResultsWrapperPass>();
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AU.addRequired<ScalarEvolutionWrapperPass>();
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AU.addRequired<DominatorTreeWrapperPass>();
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AU.addRequired<TargetTransformInfoWrapperPass>();
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AU.setPreservesCFG();
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}
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};
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}
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INITIALIZE_PASS_BEGIN(LoadStoreVectorizer, DEBUG_TYPE,
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"Vectorize load and Store instructions", false, false)
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INITIALIZE_PASS_DEPENDENCY(SCEVAAWrapperPass)
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INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
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INITIALIZE_PASS_DEPENDENCY(AAResultsWrapperPass)
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INITIALIZE_PASS_DEPENDENCY(GlobalsAAWrapperPass)
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INITIALIZE_PASS_DEPENDENCY(TargetTransformInfoWrapperPass)
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INITIALIZE_PASS_END(LoadStoreVectorizer, DEBUG_TYPE,
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"Vectorize load and store instructions", false, false)
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char LoadStoreVectorizer::ID = 0;
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Pass *llvm::createLoadStoreVectorizerPass() {
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return new LoadStoreVectorizer();
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}
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// The real propagateMetadata expects a SmallVector<Value*>, but we deal in
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// vectors of Instructions.
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static void propagateMetadata(Instruction *I, ArrayRef<Instruction *> IL) {
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SmallVector<Value *, 8> VL(IL.begin(), IL.end());
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propagateMetadata(I, VL);
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}
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bool LoadStoreVectorizer::runOnFunction(Function &F) {
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// Don't vectorize when the attribute NoImplicitFloat is used.
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if (skipFunction(F) || F.hasFnAttribute(Attribute::NoImplicitFloat))
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return false;
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AliasAnalysis &AA = getAnalysis<AAResultsWrapperPass>().getAAResults();
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DominatorTree &DT = getAnalysis<DominatorTreeWrapperPass>().getDomTree();
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ScalarEvolution &SE = getAnalysis<ScalarEvolutionWrapperPass>().getSE();
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TargetTransformInfo &TTI =
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getAnalysis<TargetTransformInfoWrapperPass>().getTTI(F);
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Vectorizer V(F, AA, DT, SE, TTI);
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return V.run();
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}
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// Vectorizer Implementation
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bool Vectorizer::run() {
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bool Changed = false;
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// Scan the blocks in the function in post order.
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for (BasicBlock *BB : post_order(&F)) {
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InstrListMap LoadRefs, StoreRefs;
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std::tie(LoadRefs, StoreRefs) = collectInstructions(BB);
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Changed |= vectorizeChains(LoadRefs);
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Changed |= vectorizeChains(StoreRefs);
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}
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return Changed;
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}
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Value *Vectorizer::getPointerOperand(Value *I) {
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if (LoadInst *LI = dyn_cast<LoadInst>(I))
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return LI->getPointerOperand();
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if (StoreInst *SI = dyn_cast<StoreInst>(I))
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return SI->getPointerOperand();
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return nullptr;
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}
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unsigned Vectorizer::getPointerAddressSpace(Value *I) {
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if (LoadInst *L = dyn_cast<LoadInst>(I))
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return L->getPointerAddressSpace();
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if (StoreInst *S = dyn_cast<StoreInst>(I))
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return S->getPointerAddressSpace();
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return -1;
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}
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// FIXME: Merge with llvm::isConsecutiveAccess
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bool Vectorizer::isConsecutiveAccess(Value *A, Value *B) {
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Value *PtrA = getPointerOperand(A);
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Value *PtrB = getPointerOperand(B);
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unsigned ASA = getPointerAddressSpace(A);
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unsigned ASB = getPointerAddressSpace(B);
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// Check that the address spaces match and that the pointers are valid.
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if (!PtrA || !PtrB || (ASA != ASB))
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return false;
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// Make sure that A and B are different pointers of the same size type.
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unsigned PtrBitWidth = DL.getPointerSizeInBits(ASA);
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Type *PtrATy = PtrA->getType()->getPointerElementType();
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Type *PtrBTy = PtrB->getType()->getPointerElementType();
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if (PtrA == PtrB ||
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DL.getTypeStoreSize(PtrATy) != DL.getTypeStoreSize(PtrBTy) ||
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DL.getTypeStoreSize(PtrATy->getScalarType()) !=
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DL.getTypeStoreSize(PtrBTy->getScalarType()))
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return false;
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APInt Size(PtrBitWidth, DL.getTypeStoreSize(PtrATy));
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APInt OffsetA(PtrBitWidth, 0), OffsetB(PtrBitWidth, 0);
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PtrA = PtrA->stripAndAccumulateInBoundsConstantOffsets(DL, OffsetA);
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PtrB = PtrB->stripAndAccumulateInBoundsConstantOffsets(DL, OffsetB);
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APInt OffsetDelta = OffsetB - OffsetA;
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// Check if they are based on the same pointer. That makes the offsets
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// sufficient.
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if (PtrA == PtrB)
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return OffsetDelta == Size;
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// Compute the necessary base pointer delta to have the necessary final delta
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// equal to the size.
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APInt BaseDelta = Size - OffsetDelta;
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// Compute the distance with SCEV between the base pointers.
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const SCEV *PtrSCEVA = SE.getSCEV(PtrA);
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const SCEV *PtrSCEVB = SE.getSCEV(PtrB);
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const SCEV *C = SE.getConstant(BaseDelta);
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const SCEV *X = SE.getAddExpr(PtrSCEVA, C);
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if (X == PtrSCEVB)
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return true;
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// Sometimes even this doesn't work, because SCEV can't always see through
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// patterns that look like (gep (ext (add (shl X, C1), C2))). Try checking
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// things the hard way.
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// Look through GEPs after checking they're the same except for the last
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// index.
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GetElementPtrInst *GEPA = dyn_cast<GetElementPtrInst>(getPointerOperand(A));
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GetElementPtrInst *GEPB = dyn_cast<GetElementPtrInst>(getPointerOperand(B));
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if (!GEPA || !GEPB || GEPA->getNumOperands() != GEPB->getNumOperands())
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return false;
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unsigned FinalIndex = GEPA->getNumOperands() - 1;
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for (unsigned i = 0; i < FinalIndex; i++)
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if (GEPA->getOperand(i) != GEPB->getOperand(i))
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return false;
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Instruction *OpA = dyn_cast<Instruction>(GEPA->getOperand(FinalIndex));
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Instruction *OpB = dyn_cast<Instruction>(GEPB->getOperand(FinalIndex));
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if (!OpA || !OpB || OpA->getOpcode() != OpB->getOpcode() ||
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OpA->getType() != OpB->getType())
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return false;
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// Only look through a ZExt/SExt.
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if (!isa<SExtInst>(OpA) && !isa<ZExtInst>(OpA))
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return false;
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bool Signed = isa<SExtInst>(OpA);
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OpA = dyn_cast<Instruction>(OpA->getOperand(0));
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OpB = dyn_cast<Instruction>(OpB->getOperand(0));
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if (!OpA || !OpB || OpA->getType() != OpB->getType())
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return false;
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// Now we need to prove that adding 1 to OpA won't overflow.
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bool Safe = false;
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// First attempt: if OpB is an add with NSW/NUW, and OpB is 1 added to OpA,
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// we're okay.
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if (OpB->getOpcode() == Instruction::Add &&
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isa<ConstantInt>(OpB->getOperand(1)) &&
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cast<ConstantInt>(OpB->getOperand(1))->getSExtValue() > 0) {
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if (Signed)
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Safe = cast<BinaryOperator>(OpB)->hasNoSignedWrap();
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else
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Safe = cast<BinaryOperator>(OpB)->hasNoUnsignedWrap();
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}
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unsigned BitWidth = OpA->getType()->getScalarSizeInBits();
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// Second attempt:
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// If any bits are known to be zero other than the sign bit in OpA, we can
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// add 1 to it while guaranteeing no overflow of any sort.
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if (!Safe) {
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APInt KnownZero(BitWidth, 0);
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APInt KnownOne(BitWidth, 0);
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computeKnownBits(OpA, KnownZero, KnownOne, DL, 0, nullptr, OpA, &DT);
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KnownZero &= ~APInt::getHighBitsSet(BitWidth, 1);
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if (KnownZero != 0)
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Safe = true;
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}
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if (!Safe)
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return false;
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const SCEV *OffsetSCEVA = SE.getSCEV(OpA);
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const SCEV *OffsetSCEVB = SE.getSCEV(OpB);
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const SCEV *One = SE.getConstant(APInt(BitWidth, 1));
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const SCEV *X2 = SE.getAddExpr(OffsetSCEVA, One);
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return X2 == OffsetSCEVB;
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}
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void Vectorizer::reorder(Instruction *I) {
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OrderedBasicBlock OBB(I->getParent());
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SmallPtrSet<Instruction *, 16> InstructionsToMove;
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SmallVector<Instruction *, 16> Worklist;
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Worklist.push_back(I);
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while (!Worklist.empty()) {
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Instruction *IW = Worklist.pop_back_val();
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int NumOperands = IW->getNumOperands();
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for (int i = 0; i < NumOperands; i++) {
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Instruction *IM = dyn_cast<Instruction>(IW->getOperand(i));
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if (!IM || IM->getOpcode() == Instruction::PHI)
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continue;
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// If IM is in another BB, no need to move it, because this pass only
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// vectorizes instructions within one BB.
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if (IM->getParent() != I->getParent())
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continue;
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if (!OBB.dominates(IM, I)) {
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InstructionsToMove.insert(IM);
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Worklist.push_back(IM);
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}
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}
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}
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// All instructions to move should follow I. Start from I, not from begin().
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for (auto BBI = I->getIterator(), E = I->getParent()->end(); BBI != E;
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++BBI) {
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if (!InstructionsToMove.count(&*BBI))
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continue;
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Instruction *IM = &*BBI;
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--BBI;
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IM->removeFromParent();
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IM->insertBefore(I);
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}
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}
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std::pair<BasicBlock::iterator, BasicBlock::iterator>
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Vectorizer::getBoundaryInstrs(ArrayRef<Instruction *> Chain) {
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Instruction *C0 = Chain[0];
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BasicBlock::iterator FirstInstr = C0->getIterator();
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BasicBlock::iterator LastInstr = C0->getIterator();
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BasicBlock *BB = C0->getParent();
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unsigned NumFound = 0;
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for (Instruction &I : *BB) {
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if (!is_contained(Chain, &I))
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continue;
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++NumFound;
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if (NumFound == 1) {
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FirstInstr = I.getIterator();
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}
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if (NumFound == Chain.size()) {
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LastInstr = I.getIterator();
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break;
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}
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}
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// Range is [first, last).
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return std::make_pair(FirstInstr, ++LastInstr);
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}
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void Vectorizer::eraseInstructions(ArrayRef<Instruction *> Chain) {
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SmallVector<Instruction *, 16> Instrs;
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for (Instruction *I : Chain) {
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Value *PtrOperand = getPointerOperand(I);
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assert(PtrOperand && "Instruction must have a pointer operand.");
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Instrs.push_back(I);
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if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(PtrOperand))
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Instrs.push_back(GEP);
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}
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// Erase instructions.
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for (Instruction *I : Instrs)
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if (I->use_empty())
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I->eraseFromParent();
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}
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std::pair<ArrayRef<Instruction *>, ArrayRef<Instruction *>>
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Vectorizer::splitOddVectorElts(ArrayRef<Instruction *> Chain,
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unsigned ElementSizeBits) {
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unsigned ElemSizeInBytes = ElementSizeBits / 8;
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unsigned SizeInBytes = ElemSizeInBytes * Chain.size();
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unsigned NumRight = (SizeInBytes % 4) / ElemSizeInBytes;
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unsigned NumLeft = Chain.size() - NumRight;
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return std::make_pair(Chain.slice(0, NumLeft), Chain.slice(NumLeft));
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}
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ArrayRef<Instruction *>
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Vectorizer::getVectorizablePrefix(ArrayRef<Instruction *> Chain) {
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// These are in BB order, unlike Chain, which is in address order.
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SmallVector<Instruction *, 16> MemoryInstrs;
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SmallVector<Instruction *, 16> ChainInstrs;
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bool IsLoadChain = isa<LoadInst>(Chain[0]);
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DEBUG({
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for (Instruction *I : Chain) {
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if (IsLoadChain)
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assert(isa<LoadInst>(I) &&
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"All elements of Chain must be loads, or all must be stores.");
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else
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assert(isa<StoreInst>(I) &&
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"All elements of Chain must be loads, or all must be stores.");
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}
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});
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for (Instruction &I : make_range(getBoundaryInstrs(Chain))) {
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if (isa<LoadInst>(I) || isa<StoreInst>(I)) {
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if (!is_contained(Chain, &I))
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MemoryInstrs.push_back(&I);
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else
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ChainInstrs.push_back(&I);
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} else if (IsLoadChain && (I.mayWriteToMemory() || I.mayThrow())) {
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DEBUG(dbgs() << "LSV: Found may-write/throw operation: " << I << '\n');
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break;
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} else if (!IsLoadChain && (I.mayReadOrWriteMemory() || I.mayThrow())) {
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DEBUG(dbgs() << "LSV: Found may-read/write/throw operation: " << I
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<< '\n');
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break;
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}
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}
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OrderedBasicBlock OBB(Chain[0]->getParent());
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// Loop until we find an instruction in ChainInstrs that we can't vectorize.
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unsigned ChainInstrIdx = 0;
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for (unsigned E = ChainInstrs.size(); ChainInstrIdx < E; ++ChainInstrIdx) {
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Instruction *ChainInstr = ChainInstrs[ChainInstrIdx];
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bool AliasFound = false;
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for (Instruction *MemInstr : MemoryInstrs) {
|
|
if (isa<LoadInst>(MemInstr) && isa<LoadInst>(ChainInstr))
|
|
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>(MemInstr) && isa<LoadInst>(ChainInstr) &&
|
|
OBB.dominates(ChainInstr, MemInstr))
|
|
continue;
|
|
|
|
// Same case, but in reverse.
|
|
if (isa<LoadInst>(MemInstr) && isa<StoreInst>(ChainInstr) &&
|
|
OBB.dominates(MemInstr, ChainInstr))
|
|
continue;
|
|
|
|
if (!AA.isNoAlias(MemoryLocation::get(MemInstr),
|
|
MemoryLocation::get(ChainInstr))) {
|
|
DEBUG({
|
|
dbgs() << "LSV: Found alias:\n"
|
|
" Aliasing instruction and pointer:\n"
|
|
<< " " << *MemInstr << '\n'
|
|
<< " " << *getPointerOperand(MemInstr) << '\n'
|
|
<< " Aliased instruction and pointer:\n"
|
|
<< " " << *ChainInstr << '\n'
|
|
<< " " << *getPointerOperand(ChainInstr) << '\n';
|
|
});
|
|
AliasFound = true;
|
|
break;
|
|
}
|
|
}
|
|
if (AliasFound)
|
|
break;
|
|
}
|
|
|
|
// Find the largest prefix of Chain whose elements are all in
|
|
// ChainInstrs[0, ChainInstrIdx). This is the largest vectorizable prefix of
|
|
// Chain. (Recall that Chain is in address order, but ChainInstrs is in BB
|
|
// order.)
|
|
SmallPtrSet<Instruction *, 8> VectorizableChainInstrs(
|
|
ChainInstrs.begin(), ChainInstrs.begin() + ChainInstrIdx);
|
|
unsigned ChainIdx = 0;
|
|
for (unsigned ChainLen = Chain.size(); ChainIdx < ChainLen; ++ChainIdx) {
|
|
if (!VectorizableChainInstrs.count(Chain[ChainIdx]))
|
|
break;
|
|
}
|
|
return Chain.slice(0, ChainIdx);
|
|
}
|
|
|
|
std::pair<InstrListMap, InstrListMap>
|
|
Vectorizer::collectInstructions(BasicBlock *BB) {
|
|
InstrListMap LoadRefs;
|
|
InstrListMap StoreRefs;
|
|
|
|
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 ExtractElementInst *EEI = dyn_cast<ExtractElementInst>(U);
|
|
return EEI && isa<ConstantInt>(EEI->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 ExtractElementInst *EEI = dyn_cast<ExtractElementInst>(U);
|
|
return EEI && isa<ConstantInt>(EEI->getOperand(1));
|
|
}))
|
|
continue;
|
|
|
|
// Save store location.
|
|
Value *ObjPtr = GetUnderlyingObject(Ptr, DL);
|
|
StoreRefs[ObjPtr].push_back(SI);
|
|
}
|
|
}
|
|
|
|
return {LoadRefs, StoreRefs};
|
|
}
|
|
|
|
bool Vectorizer::vectorizeChains(InstrListMap &Map) {
|
|
bool Changed = false;
|
|
|
|
for (const std::pair<Value *, InstrList> &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<Instruction *> Chunk(&Chain.second[CI], Len);
|
|
Changed |= vectorizeInstructions(Chunk);
|
|
}
|
|
}
|
|
|
|
return Changed;
|
|
}
|
|
|
|
bool Vectorizer::vectorizeInstructions(ArrayRef<Instruction *> Instrs) {
|
|
DEBUG(dbgs() << "LSV: Vectorizing " << Instrs.size() << " instructions.\n");
|
|
SmallVector<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.push_back(j);
|
|
Heads.push_back(i);
|
|
ConsecutiveChain[i] = j;
|
|
}
|
|
}
|
|
}
|
|
|
|
bool Changed = false;
|
|
SmallPtrSet<Instruction *, 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<Instruction *, 16> Operands;
|
|
int I = Head;
|
|
while (I != -1 && (is_contained(Tails, I) || is_contained(Heads, 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<Instruction *> Chain,
|
|
SmallPtrSet<Instruction *, 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 (Instruction *I : Chain) {
|
|
StoreTy = cast<StoreInst>(I)->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;
|
|
}
|
|
|
|
ArrayRef<Instruction *> NewChain = getVectorizablePrefix(Chain);
|
|
if (NewChain.empty()) {
|
|
// No vectorization possible.
|
|
InstructionsProcessed->insert(Chain.begin(), Chain.end());
|
|
return false;
|
|
}
|
|
if (NewChain.size() == 1) {
|
|
// Failed after the first instruction. Discard it and try the smaller chain.
|
|
InstructionsProcessed->insert(NewChain.front());
|
|
return false;
|
|
}
|
|
|
|
// Update Chain to the valid vectorizable subchain.
|
|
Chain = NewChain;
|
|
ChainSize = Chain.size();
|
|
|
|
// Store size should be 1B, 2B or multiple of 4B.
|
|
// TODO: Target hook for size constraint?
|
|
unsigned EltSzInBytes = Sz / 8;
|
|
unsigned SzInBytes = EltSzInBytes * 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 (Instruction *I : Chain)
|
|
dbgs() << " " << *I << "\n";
|
|
});
|
|
|
|
// 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;
|
|
|
|
unsigned NewAlign = getOrEnforceKnownAlignment(S0->getPointerOperand(),
|
|
StackAdjustedAlignment,
|
|
DL, S0, nullptr, &DT);
|
|
if (NewAlign < StackAdjustedAlignment)
|
|
return false;
|
|
}
|
|
|
|
BasicBlock::iterator First, Last;
|
|
std::tie(First, Last) = getBoundaryInstrs(Chain);
|
|
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;
|
|
}
|
|
}
|
|
|
|
// This cast is safe because Builder.CreateStore() always creates a bona fide
|
|
// StoreInst.
|
|
StoreInst *SI = cast<StoreInst>(
|
|
Builder.CreateStore(Vec, Builder.CreateBitCast(S0->getPointerOperand(),
|
|
VecTy->getPointerTo(AS))));
|
|
propagateMetadata(SI, Chain);
|
|
SI->setAlignment(Alignment);
|
|
|
|
eraseInstructions(Chain);
|
|
++NumVectorInstructions;
|
|
NumScalarsVectorized += Chain.size();
|
|
return true;
|
|
}
|
|
|
|
bool Vectorizer::vectorizeLoadChain(
|
|
ArrayRef<Instruction *> Chain,
|
|
SmallPtrSet<Instruction *, 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;
|
|
}
|
|
|
|
ArrayRef<Instruction *> NewChain = getVectorizablePrefix(Chain);
|
|
if (NewChain.empty()) {
|
|
// No vectorization possible.
|
|
InstructionsProcessed->insert(Chain.begin(), Chain.end());
|
|
return false;
|
|
}
|
|
if (NewChain.size() == 1) {
|
|
// Failed after the first instruction. Discard it and try the smaller chain.
|
|
InstructionsProcessed->insert(NewChain.front());
|
|
return false;
|
|
}
|
|
|
|
// Update Chain to the valid vectorizable subchain.
|
|
Chain = NewChain;
|
|
ChainSize = Chain.size();
|
|
|
|
// Load size should be 1B, 2B or multiple of 4B.
|
|
// TODO: Should size constraint be a target hook?
|
|
unsigned EltSzInBytes = Sz / 8;
|
|
unsigned SzInBytes = EltSzInBytes * 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;
|
|
|
|
unsigned NewAlign = getOrEnforceKnownAlignment(L0->getPointerOperand(),
|
|
StackAdjustedAlignment,
|
|
DL, L0, nullptr, &DT);
|
|
if (NewAlign < StackAdjustedAlignment)
|
|
return false;
|
|
|
|
Alignment = NewAlign;
|
|
}
|
|
|
|
DEBUG({
|
|
dbgs() << "LSV: Loads to vectorize:\n";
|
|
for (Instruction *I : Chain)
|
|
I->dump();
|
|
});
|
|
|
|
// getVectorizablePrefix already computed getBoundaryInstrs. The value of
|
|
// Last may have changed since then, but the value of First won't have. If it
|
|
// matters, we could compute getBoundaryInstrs only once and reuse it here.
|
|
BasicBlock::iterator First, Last;
|
|
std::tie(First, Last) = getBoundaryInstrs(Chain);
|
|
Builder.SetInsertPoint(&*First);
|
|
|
|
Value *Bitcast =
|
|
Builder.CreateBitCast(L0->getPointerOperand(), VecTy->getPointerTo(AS));
|
|
// This cast is safe because Builder.CreateLoad always creates a bona fide
|
|
// LoadInst.
|
|
LoadInst *LI = cast<LoadInst>(Builder.CreateLoad(Bitcast));
|
|
propagateMetadata(LI, Chain);
|
|
LI->setAlignment(Alignment);
|
|
|
|
if (VecLoadTy) {
|
|
SmallVector<Instruction *, 16> InstrsToErase;
|
|
|
|
unsigned VecWidth = VecLoadTy->getNumElements();
|
|
for (unsigned I = 0, E = Chain.size(); I != E; ++I) {
|
|
for (auto Use : Chain[I]->users()) {
|
|
// All users of vector loads are ExtractElement instructions with
|
|
// constant indices, otherwise we would have bailed before now.
|
|
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),
|
|
UI->getName());
|
|
if (V->getType() != UI->getType())
|
|
V = Builder.CreateBitCast(V, UI->getType());
|
|
|
|
// Replace the old instruction.
|
|
UI->replaceAllUsesWith(V);
|
|
InstrsToErase.push_back(UI);
|
|
}
|
|
}
|
|
|
|
// Bitcast might not be an Instruction, if the value being loaded is a
|
|
// constant. In that case, no need to reorder anything.
|
|
if (Instruction *BitcastInst = dyn_cast<Instruction>(Bitcast))
|
|
reorder(BitcastInst);
|
|
|
|
for (auto I : InstrsToErase)
|
|
I->eraseFromParent();
|
|
} else {
|
|
for (unsigned I = 0, E = Chain.size(); I != E; ++I) {
|
|
Value *CV = Chain[I];
|
|
Value *V =
|
|
Builder.CreateExtractElement(LI, Builder.getInt32(I), CV->getName());
|
|
if (V->getType() != CV->getType()) {
|
|
V = Builder.CreateBitOrPointerCast(V, CV->getType());
|
|
}
|
|
|
|
// Replace the old instruction.
|
|
CV->replaceAllUsesWith(V);
|
|
}
|
|
|
|
if (Instruction *BitcastInst = dyn_cast<Instruction>(Bitcast))
|
|
reorder(BitcastInst);
|
|
}
|
|
|
|
eraseInstructions(Chain);
|
|
|
|
++NumVectorInstructions;
|
|
NumScalarsVectorized += Chain.size();
|
|
return true;
|
|
}
|
|
|
|
bool Vectorizer::accessIsMisaligned(unsigned SzInBytes, unsigned AddressSpace,
|
|
unsigned Alignment) {
|
|
if (Alignment % SzInBytes == 0)
|
|
return false;
|
|
|
|
bool Fast = false;
|
|
bool Allows = TTI.allowsMisalignedMemoryAccesses(F.getParent()->getContext(),
|
|
SzInBytes * 8, AddressSpace,
|
|
Alignment, &Fast);
|
|
DEBUG(dbgs() << "LSV: Target said misaligned is allowed? " << Allows
|
|
<< " and fast? " << Fast << "\n";);
|
|
return !Allows || !Fast;
|
|
}
|