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Change LoopInstSimplify back to a LoopPass. It revisits subloops rather than

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skipping them, but it should probably use a worklist and only revisit those
instructions in subloops that have actually changed. It should probably also
use a worklist after the first iteration like instsimplify now does. Regardless,
it's only 0.3% of opt -O2 time on 403.gcc if it replaces the instcombine placed
in the middle of the loop passes.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122868 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Cameron Zwarich 2011-01-05 05:15:53 +00:00
parent be478819cb
commit e389ab16f3
1 changed files with 36 additions and 10 deletions
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46
lib/Transforms/Scalar/LoopInstSimplify.cpp
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@ -12,11 +12,11 @@
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "loop-instsimplify"
#include "llvm/Function.h"
#include "llvm/Pass.h"
#include "llvm/Analysis/Dominators.h"
#include "llvm/Analysis/InstructionSimplify.h"
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/Analysis/LoopPass.h"
#include "llvm/Support/Debug.h"
#include "llvm/Target/TargetData.h"
#include "llvm/Transforms/Scalar.h"
#include "llvm/Transforms/Utils/Local.h"
@ -26,19 +26,19 @@ using namespace llvm;
STATISTIC(NumSimplified, "Number of redundant instructions simplified");
namespace {
class LoopInstSimplify : public FunctionPass {
class LoopInstSimplify : public LoopPass {
public:
static char ID; // Pass ID, replacement for typeid
LoopInstSimplify() : FunctionPass(ID) {
LoopInstSimplify() : LoopPass(ID) {
initializeLoopInstSimplifyPass(*PassRegistry::getPassRegistry());
}
bool runOnFunction(Function &);
bool runOnLoop(Loop*, LPPassManager&);
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesCFG();
AU.addRequired<LoopInfo>();
AU.addPreserved<LoopInfo>();
AU.addRequiredID(LoopSimplifyID);
AU.addPreservedID(LCSSAID);
}
};
@ -57,19 +57,34 @@ Pass* llvm::createLoopInstSimplifyPass() {
return new LoopInstSimplify();
}
bool LoopInstSimplify::runOnFunction(Function &F) {
bool LoopInstSimplify::runOnLoop(Loop *L, LPPassManager &LPM) {
DominatorTree *DT = getAnalysisIfAvailable<DominatorTree>();
LoopInfo *LI = &getAnalysis<LoopInfo>();
const TargetData *TD = getAnalysisIfAvailable<TargetData>();
SmallVector<BasicBlock*, 8> ExitBlocks;
L->getUniqueExitBlocks(ExitBlocks);
array_pod_sort(ExitBlocks.begin(), ExitBlocks.end());
SmallVector<BasicBlock*, 16> VisitStack;
SmallPtrSet<BasicBlock*, 32> Visited;
bool Changed = false;
bool LocalChanged;
do {
LocalChanged = false;
for (df_iterator<BasicBlock*> DI = df_begin(&F.getEntryBlock()),
DE = df_end(&F.getEntryBlock()); DI != DE; ++DI)
for (BasicBlock::iterator BI = DI->begin(), BE = DI->end(); BI != BE;) {
VisitStack.clear();
Visited.clear();
VisitStack.push_back(L->getHeader());
while (!VisitStack.empty()) {
BasicBlock *BB = VisitStack.back();
VisitStack.pop_back();
// Simplify instructions in the current basic block.
for (BasicBlock::iterator BI = BB->begin(), BE = BB->end(); BI != BE;) {
Instruction *I = BI++;
// Don't bother simplifying unused instructions.
if (!I->use_empty()) {
@ -83,6 +98,17 @@ bool LoopInstSimplify::runOnFunction(Function &F) {
LocalChanged |= RecursivelyDeleteTriviallyDeadInstructions(I);
}
// Add all successors to the worklist, except for loop exit blocks.
for (succ_iterator SI = succ_begin(BB), SE = succ_end(BB); SI != SE;
++SI) {
BasicBlock *SuccBB = *SI;
bool IsExitBlock = std::binary_search(ExitBlocks.begin(),
ExitBlocks.end(), SuccBB);
if (!IsExitBlock && Visited.insert(SuccBB))
VisitStack.push_back(SuccBB);
}
}
Changed |= LocalChanged;
} while (LocalChanged);