forked from OSchip/llvm-project
149 lines
5.4 KiB
C++
149 lines
5.4 KiB
C++
//===- InstSimplifyPass.cpp -----------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Transforms/Scalar/InstSimplifyPass.h"
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#include "llvm/ADT/DepthFirstIterator.h"
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#include "llvm/ADT/SmallPtrSet.h"
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#include "llvm/ADT/Statistic.h"
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#include "llvm/Analysis/AssumptionCache.h"
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#include "llvm/Analysis/InstructionSimplify.h"
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#include "llvm/Analysis/OptimizationRemarkEmitter.h"
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#include "llvm/Analysis/TargetLibraryInfo.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/Function.h"
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#include "llvm/IR/Type.h"
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#include "llvm/InitializePasses.h"
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#include "llvm/Pass.h"
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#include "llvm/Transforms/Scalar.h"
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#include "llvm/Transforms/Utils.h"
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#include "llvm/Transforms/Utils/Local.h"
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using namespace llvm;
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#define DEBUG_TYPE "instsimplify"
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STATISTIC(NumSimplified, "Number of redundant instructions removed");
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static bool runImpl(Function &F, const SimplifyQuery &SQ,
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OptimizationRemarkEmitter *ORE) {
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SmallPtrSet<const Instruction *, 8> S1, S2, *ToSimplify = &S1, *Next = &S2;
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bool Changed = false;
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do {
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for (BasicBlock &BB : F) {
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// Unreachable code can take on strange forms that we are not prepared to
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// handle. For example, an instruction may have itself as an operand.
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if (!SQ.DT->isReachableFromEntry(&BB))
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continue;
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SmallVector<WeakTrackingVH, 8> DeadInstsInBB;
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for (Instruction &I : BB) {
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// The first time through the loop, ToSimplify is empty and we try to
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// simplify all instructions. On later iterations, ToSimplify is not
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// empty and we only bother simplifying instructions that are in it.
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if (!ToSimplify->empty() && !ToSimplify->count(&I))
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continue;
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// Don't waste time simplifying dead/unused instructions.
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if (isInstructionTriviallyDead(&I)) {
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DeadInstsInBB.push_back(&I);
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Changed = true;
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} else if (!I.use_empty()) {
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if (Value *V = SimplifyInstruction(&I, SQ, ORE)) {
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// Mark all uses for resimplification next time round the loop.
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for (User *U : I.users())
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Next->insert(cast<Instruction>(U));
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I.replaceAllUsesWith(V);
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++NumSimplified;
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Changed = true;
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// A call can get simplified, but it may not be trivially dead.
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if (isInstructionTriviallyDead(&I))
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DeadInstsInBB.push_back(&I);
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}
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}
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}
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RecursivelyDeleteTriviallyDeadInstructions(DeadInstsInBB, SQ.TLI);
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}
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// Place the list of instructions to simplify on the next loop iteration
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// into ToSimplify.
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std::swap(ToSimplify, Next);
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Next->clear();
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} while (!ToSimplify->empty());
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return Changed;
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}
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namespace {
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struct InstSimplifyLegacyPass : public FunctionPass {
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static char ID; // Pass identification, replacement for typeid
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InstSimplifyLegacyPass() : FunctionPass(ID) {
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initializeInstSimplifyLegacyPassPass(*PassRegistry::getPassRegistry());
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}
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void getAnalysisUsage(AnalysisUsage &AU) const override {
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AU.setPreservesCFG();
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AU.addRequired<DominatorTreeWrapperPass>();
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AU.addRequired<AssumptionCacheTracker>();
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AU.addRequired<TargetLibraryInfoWrapperPass>();
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AU.addRequired<OptimizationRemarkEmitterWrapperPass>();
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}
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/// Remove instructions that simplify.
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bool runOnFunction(Function &F) override {
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if (skipFunction(F))
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return false;
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const DominatorTree *DT =
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&getAnalysis<DominatorTreeWrapperPass>().getDomTree();
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const TargetLibraryInfo *TLI =
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&getAnalysis<TargetLibraryInfoWrapperPass>().getTLI(F);
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AssumptionCache *AC =
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&getAnalysis<AssumptionCacheTracker>().getAssumptionCache(F);
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OptimizationRemarkEmitter *ORE =
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&getAnalysis<OptimizationRemarkEmitterWrapperPass>().getORE();
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const DataLayout &DL = F.getParent()->getDataLayout();
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const SimplifyQuery SQ(DL, TLI, DT, AC);
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return runImpl(F, SQ, ORE);
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}
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};
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} // namespace
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char InstSimplifyLegacyPass::ID = 0;
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INITIALIZE_PASS_BEGIN(InstSimplifyLegacyPass, "instsimplify",
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"Remove redundant instructions", false, false)
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INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)
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INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
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INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
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INITIALIZE_PASS_DEPENDENCY(OptimizationRemarkEmitterWrapperPass)
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INITIALIZE_PASS_END(InstSimplifyLegacyPass, "instsimplify",
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"Remove redundant instructions", false, false)
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// Public interface to the simplify instructions pass.
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FunctionPass *llvm::createInstSimplifyLegacyPass() {
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return new InstSimplifyLegacyPass();
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}
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PreservedAnalyses InstSimplifyPass::run(Function &F,
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FunctionAnalysisManager &AM) {
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auto &DT = AM.getResult<DominatorTreeAnalysis>(F);
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auto &TLI = AM.getResult<TargetLibraryAnalysis>(F);
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auto &AC = AM.getResult<AssumptionAnalysis>(F);
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auto &ORE = AM.getResult<OptimizationRemarkEmitterAnalysis>(F);
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const DataLayout &DL = F.getParent()->getDataLayout();
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const SimplifyQuery SQ(DL, &TLI, &DT, &AC);
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bool Changed = runImpl(F, SQ, &ORE);
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if (!Changed)
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return PreservedAnalyses::all();
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PreservedAnalyses PA;
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PA.preserveSet<CFGAnalyses>();
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return PA;
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}
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