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93054c1e87
Review feedback from r328165. Split out just the one function from the file that's used by Analysis. (As chandlerc pointed out, the original change only moved the header and not the implementation anyway - which was fine for the one function that was used (since it's a template/inlined in the header) but not in general) llvm-svn: 333954
111 lines
3.8 KiB
C++
111 lines
3.8 KiB
C++
//===--------- LoopSimplifyCFG.cpp - Loop CFG Simplification Pass ---------===//
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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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// This file implements the Loop SimplifyCFG Pass. This pass is responsible for
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// basic loop CFG cleanup, primarily to assist other loop passes. If you
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// encounter a noncanonical CFG construct that causes another loop pass to
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// perform suboptimally, this is the place to fix it up.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Transforms/Scalar/LoopSimplifyCFG.h"
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#include "llvm/ADT/SmallVector.h"
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#include "llvm/ADT/Statistic.h"
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#include "llvm/Analysis/AliasAnalysis.h"
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#include "llvm/Analysis/AssumptionCache.h"
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#include "llvm/Analysis/BasicAliasAnalysis.h"
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#include "llvm/Analysis/DependenceAnalysis.h"
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#include "llvm/Analysis/GlobalsModRef.h"
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#include "llvm/Analysis/LoopInfo.h"
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#include "llvm/Analysis/LoopPass.h"
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#include "llvm/Analysis/ScalarEvolution.h"
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#include "llvm/Analysis/ScalarEvolutionAliasAnalysis.h"
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#include "llvm/Analysis/TargetTransformInfo.h"
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#include "llvm/Transforms/Utils/Local.h"
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#include "llvm/IR/Dominators.h"
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#include "llvm/Transforms/Scalar.h"
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#include "llvm/Transforms/Scalar/LoopPassManager.h"
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#include "llvm/Transforms/Utils.h"
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#include "llvm/Transforms/Utils/LoopUtils.h"
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using namespace llvm;
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#define DEBUG_TYPE "loop-simplifycfg"
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static bool simplifyLoopCFG(Loop &L, DominatorTree &DT, LoopInfo &LI) {
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bool Changed = false;
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// Copy blocks into a temporary array to avoid iterator invalidation issues
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// as we remove them.
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SmallVector<WeakTrackingVH, 16> Blocks(L.blocks());
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for (auto &Block : Blocks) {
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// Attempt to merge blocks in the trivial case. Don't modify blocks which
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// belong to other loops.
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BasicBlock *Succ = cast_or_null<BasicBlock>(Block);
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if (!Succ)
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continue;
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BasicBlock *Pred = Succ->getSinglePredecessor();
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if (!Pred || !Pred->getSingleSuccessor() || LI.getLoopFor(Pred) != &L)
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continue;
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// Pred is going to disappear, so we need to update the loop info.
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if (L.getHeader() == Pred)
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L.moveToHeader(Succ);
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LI.removeBlock(Pred);
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MergeBasicBlockIntoOnlyPred(Succ, &DT);
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Changed = true;
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}
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return Changed;
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}
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PreservedAnalyses LoopSimplifyCFGPass::run(Loop &L, LoopAnalysisManager &AM,
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LoopStandardAnalysisResults &AR,
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LPMUpdater &) {
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if (!simplifyLoopCFG(L, AR.DT, AR.LI))
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return PreservedAnalyses::all();
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return getLoopPassPreservedAnalyses();
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}
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namespace {
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class LoopSimplifyCFGLegacyPass : public LoopPass {
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public:
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static char ID; // Pass ID, replacement for typeid
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LoopSimplifyCFGLegacyPass() : LoopPass(ID) {
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initializeLoopSimplifyCFGLegacyPassPass(*PassRegistry::getPassRegistry());
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}
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bool runOnLoop(Loop *L, LPPassManager &) override {
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if (skipLoop(L))
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return false;
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DominatorTree &DT = getAnalysis<DominatorTreeWrapperPass>().getDomTree();
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LoopInfo &LI = getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
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return simplifyLoopCFG(*L, DT, LI);
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}
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void getAnalysisUsage(AnalysisUsage &AU) const override {
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AU.addPreserved<DependenceAnalysisWrapperPass>();
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getLoopAnalysisUsage(AU);
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}
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};
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}
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char LoopSimplifyCFGLegacyPass::ID = 0;
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INITIALIZE_PASS_BEGIN(LoopSimplifyCFGLegacyPass, "loop-simplifycfg",
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"Simplify loop CFG", false, false)
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INITIALIZE_PASS_DEPENDENCY(LoopPass)
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INITIALIZE_PASS_END(LoopSimplifyCFGLegacyPass, "loop-simplifycfg",
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"Simplify loop CFG", false, false)
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Pass *llvm::createLoopSimplifyCFGPass() {
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return new LoopSimplifyCFGLegacyPass();
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}
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