mirror of
https://github.com/RPCSX/llvm.git
synced 2025-04-07 02:31:55 +00:00
e95cc25a22
not very important since the pass is only used for testing, but it does make it more realistic. Suggested by Frits van Bommel. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122336 91177308-0d34-0410-b5e6-96231b3b80d8
98 lines
3.5 KiB
C++
98 lines
3.5 KiB
C++
//===------ SimplifyInstructions.cpp - Remove redundant instructions ------===//
|
|
//
|
|
// The LLVM Compiler Infrastructure
|
|
//
|
|
// This file is distributed under the University of Illinois Open Source
|
|
// License. See LICENSE.TXT for details.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
//
|
|
// This is a utility pass used for testing the InstructionSimplify analysis.
|
|
// The analysis is applied to every instruction, and if it simplifies then the
|
|
// instruction is replaced by the simplification. If you are looking for a pass
|
|
// that performs serious instruction folding, use the instcombine pass instead.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#define DEBUG_TYPE "instsimplify"
|
|
#include "llvm/Function.h"
|
|
#include "llvm/Pass.h"
|
|
#include "llvm/Type.h"
|
|
#include "llvm/ADT/Statistic.h"
|
|
#include "llvm/Analysis/Dominators.h"
|
|
#include "llvm/Analysis/InstructionSimplify.h"
|
|
#include "llvm/Target/TargetData.h"
|
|
#include "llvm/Transforms/Scalar.h"
|
|
#include "llvm/Transforms/Utils/Local.h"
|
|
using namespace llvm;
|
|
|
|
STATISTIC(NumSimplified, "Number of redundant instructions removed");
|
|
|
|
namespace {
|
|
struct InstSimplifier : public FunctionPass {
|
|
static char ID; // Pass identification, replacement for typeid
|
|
InstSimplifier() : FunctionPass(ID) {
|
|
initializeInstSimplifierPass(*PassRegistry::getPassRegistry());
|
|
}
|
|
|
|
void getAnalysisUsage(AnalysisUsage &AU) const {
|
|
AU.setPreservesCFG();
|
|
}
|
|
|
|
/// runOnFunction - Remove instructions that simplify.
|
|
bool runOnFunction(Function &F) {
|
|
const TargetData *TD = getAnalysisIfAvailable<TargetData>();
|
|
const DominatorTree *DT = getAnalysisIfAvailable<DominatorTree>();
|
|
bool Changed = false;
|
|
|
|
// Add all interesting instructions to the worklist.
|
|
std::set<Instruction*> Worklist;
|
|
for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
|
|
for (BasicBlock::iterator BI = BB->begin(), BE = BB->end(); BI != BE;) {
|
|
Instruction *I = BI++;
|
|
// Zap any dead instructions.
|
|
if (isInstructionTriviallyDead(I)) {
|
|
I->eraseFromParent();
|
|
Changed = true;
|
|
continue;
|
|
}
|
|
// Add all others to the worklist.
|
|
Worklist.insert(I);
|
|
}
|
|
|
|
// Simplify everything in the worklist until the cows come home.
|
|
while (!Worklist.empty()) {
|
|
Instruction *I = *Worklist.begin();
|
|
Worklist.erase(Worklist.begin());
|
|
Value *V = SimplifyInstruction(I, TD, DT);
|
|
if (!V) continue;
|
|
|
|
// This instruction simplifies! Replace it with its simplification and
|
|
// add all uses to the worklist, since they may now simplify.
|
|
I->replaceAllUsesWith(V);
|
|
for (Value::use_iterator UI = I->use_begin(), UE = I->use_end();
|
|
UI != UE; ++UI)
|
|
// In unreachable code an instruction can use itself, in which case
|
|
// don't add it to the worklist since we are about to erase it.
|
|
if (*UI != I) Worklist.insert(cast<Instruction>(*UI));
|
|
if (isInstructionTriviallyDead(I))
|
|
I->eraseFromParent();
|
|
++NumSimplified;
|
|
Changed = true;
|
|
}
|
|
|
|
return Changed;
|
|
}
|
|
};
|
|
}
|
|
|
|
char InstSimplifier::ID = 0;
|
|
INITIALIZE_PASS(InstSimplifier, "instsimplify", "Remove redundant instructions",
|
|
false, false)
|
|
char &llvm::InstructionSimplifierID = InstSimplifier::ID;
|
|
|
|
// Public interface to the simplify instructions pass.
|
|
FunctionPass *llvm::createInstructionSimplifierPass() {
|
|
return new InstSimplifier();
|
|
}
|