forked from OSchip/llvm-project
111 lines
3.8 KiB
C++
111 lines
3.8 KiB
C++
//===--------- LoopSimplifyCFG.cpp - Loop CFG Simplification Pass ---------===//
|
|
//
|
|
// The LLVM Compiler Infrastructure
|
|
//
|
|
// This file is distributed under the University of Illinois Open Source
|
|
// License. See LICENSE.TXT for details.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
//
|
|
// This file implements the Loop SimplifyCFG Pass. This pass is responsible for
|
|
// basic loop CFG cleanup, primarily to assist other loop passes. If you
|
|
// encounter a noncanonical CFG construct that causes another loop pass to
|
|
// perform suboptimally, this is the place to fix it up.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#include "llvm/Transforms/Scalar/LoopSimplifyCFG.h"
|
|
#include "llvm/ADT/SmallVector.h"
|
|
#include "llvm/ADT/Statistic.h"
|
|
#include "llvm/Analysis/AliasAnalysis.h"
|
|
#include "llvm/Analysis/AssumptionCache.h"
|
|
#include "llvm/Analysis/BasicAliasAnalysis.h"
|
|
#include "llvm/Analysis/DependenceAnalysis.h"
|
|
#include "llvm/Analysis/GlobalsModRef.h"
|
|
#include "llvm/Analysis/LoopInfo.h"
|
|
#include "llvm/Analysis/LoopPass.h"
|
|
#include "llvm/Analysis/ScalarEvolution.h"
|
|
#include "llvm/Analysis/ScalarEvolutionAliasAnalysis.h"
|
|
#include "llvm/Analysis/TargetTransformInfo.h"
|
|
#include "llvm/Analysis/Utils/Local.h"
|
|
#include "llvm/IR/Dominators.h"
|
|
#include "llvm/Transforms/Scalar.h"
|
|
#include "llvm/Transforms/Scalar/LoopPassManager.h"
|
|
#include "llvm/Transforms/Utils.h"
|
|
#include "llvm/Transforms/Utils/LoopUtils.h"
|
|
using namespace llvm;
|
|
|
|
#define DEBUG_TYPE "loop-simplifycfg"
|
|
|
|
static bool simplifyLoopCFG(Loop &L, DominatorTree &DT, LoopInfo &LI) {
|
|
bool Changed = false;
|
|
// Copy blocks into a temporary array to avoid iterator invalidation issues
|
|
// as we remove them.
|
|
SmallVector<WeakTrackingVH, 16> Blocks(L.blocks());
|
|
|
|
for (auto &Block : Blocks) {
|
|
// Attempt to merge blocks in the trivial case. Don't modify blocks which
|
|
// belong to other loops.
|
|
BasicBlock *Succ = cast_or_null<BasicBlock>(Block);
|
|
if (!Succ)
|
|
continue;
|
|
|
|
BasicBlock *Pred = Succ->getSinglePredecessor();
|
|
if (!Pred || !Pred->getSingleSuccessor() || LI.getLoopFor(Pred) != &L)
|
|
continue;
|
|
|
|
// Pred is going to disappear, so we need to update the loop info.
|
|
if (L.getHeader() == Pred)
|
|
L.moveToHeader(Succ);
|
|
LI.removeBlock(Pred);
|
|
MergeBasicBlockIntoOnlyPred(Succ, &DT);
|
|
Changed = true;
|
|
}
|
|
|
|
return Changed;
|
|
}
|
|
|
|
PreservedAnalyses LoopSimplifyCFGPass::run(Loop &L, LoopAnalysisManager &AM,
|
|
LoopStandardAnalysisResults &AR,
|
|
LPMUpdater &) {
|
|
if (!simplifyLoopCFG(L, AR.DT, AR.LI))
|
|
return PreservedAnalyses::all();
|
|
|
|
return getLoopPassPreservedAnalyses();
|
|
}
|
|
|
|
namespace {
|
|
class LoopSimplifyCFGLegacyPass : public LoopPass {
|
|
public:
|
|
static char ID; // Pass ID, replacement for typeid
|
|
LoopSimplifyCFGLegacyPass() : LoopPass(ID) {
|
|
initializeLoopSimplifyCFGLegacyPassPass(*PassRegistry::getPassRegistry());
|
|
}
|
|
|
|
bool runOnLoop(Loop *L, LPPassManager &) override {
|
|
if (skipLoop(L))
|
|
return false;
|
|
|
|
DominatorTree &DT = getAnalysis<DominatorTreeWrapperPass>().getDomTree();
|
|
LoopInfo &LI = getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
|
|
return simplifyLoopCFG(*L, DT, LI);
|
|
}
|
|
|
|
void getAnalysisUsage(AnalysisUsage &AU) const override {
|
|
AU.addPreserved<DependenceAnalysisWrapperPass>();
|
|
getLoopAnalysisUsage(AU);
|
|
}
|
|
};
|
|
}
|
|
|
|
char LoopSimplifyCFGLegacyPass::ID = 0;
|
|
INITIALIZE_PASS_BEGIN(LoopSimplifyCFGLegacyPass, "loop-simplifycfg",
|
|
"Simplify loop CFG", false, false)
|
|
INITIALIZE_PASS_DEPENDENCY(LoopPass)
|
|
INITIALIZE_PASS_END(LoopSimplifyCFGLegacyPass, "loop-simplifycfg",
|
|
"Simplify loop CFG", false, false)
|
|
|
|
Pass *llvm::createLoopSimplifyCFGPass() {
|
|
return new LoopSimplifyCFGLegacyPass();
|
|
}
|