mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2024-09-07 01:54:50 +00:00
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
117 lines
3.7 KiB
C++
117 lines
3.7 KiB
C++
//===- LoopInstSimplify.cpp - Loop Instruction Simplification Pass --------===//
|
|
//
|
|
// The LLVM Compiler Infrastructure
|
|
//
|
|
// This file is distributed under the University of Illinois Open Source
|
|
// License. See LICENSE.TXT for details.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
//
|
|
// This pass performs lightweight instruction simplification on loop bodies.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#define DEBUG_TYPE "loop-instsimplify"
|
|
#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"
|
|
#include "llvm/ADT/Statistic.h"
|
|
using namespace llvm;
|
|
|
|
STATISTIC(NumSimplified, "Number of redundant instructions simplified");
|
|
|
|
namespace {
|
|
class LoopInstSimplify : public LoopPass {
|
|
public:
|
|
static char ID; // Pass ID, replacement for typeid
|
|
LoopInstSimplify() : LoopPass(ID) {
|
|
initializeLoopInstSimplifyPass(*PassRegistry::getPassRegistry());
|
|
}
|
|
|
|
bool runOnLoop(Loop*, LPPassManager&);
|
|
|
|
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
|
|
AU.setPreservesCFG();
|
|
AU.addRequired<LoopInfo>();
|
|
AU.addRequiredID(LoopSimplifyID);
|
|
AU.addPreservedID(LCSSAID);
|
|
}
|
|
};
|
|
}
|
|
|
|
char LoopInstSimplify::ID = 0;
|
|
INITIALIZE_PASS_BEGIN(LoopInstSimplify, "loop-instsimplify",
|
|
"Simplify instructions in loops", false, false)
|
|
INITIALIZE_PASS_DEPENDENCY(DominatorTree)
|
|
INITIALIZE_PASS_DEPENDENCY(LoopInfo)
|
|
INITIALIZE_PASS_DEPENDENCY(LCSSA)
|
|
INITIALIZE_PASS_END(LoopInstSimplify, "loop-instsimplify",
|
|
"Simplify instructions in loops", false, false)
|
|
|
|
Pass* llvm::createLoopInstSimplifyPass() {
|
|
return new LoopInstSimplify();
|
|
}
|
|
|
|
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;
|
|
|
|
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()) {
|
|
Value *V = SimplifyInstruction(I, TD, DT);
|
|
if (V && LI->replacementPreservesLCSSAForm(I, V)) {
|
|
I->replaceAllUsesWith(V);
|
|
LocalChanged = true;
|
|
++NumSimplified;
|
|
}
|
|
}
|
|
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);
|
|
|
|
return Changed;
|
|
}
|