mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2024-11-12 15:05:06 +00:00
dc615e41b5
InstructionSimplify on instructions that didn't change since the last time round the loop. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122745 91177308-0d34-0410-b5e6-96231b3b80d8
95 lines
3.6 KiB
C++
95 lines
3.6 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/DepthFirstIterator.h"
|
|
#include "llvm/ADT/SmallPtrSet.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 DominatorTree *DT = getAnalysisIfAvailable<DominatorTree>();
|
|
const TargetData *TD = getAnalysisIfAvailable<TargetData>();
|
|
SmallPtrSet<const Instruction*, 8> S1, S2, *ToSimplify = &S1, *Next = &S2;
|
|
bool Changed = false;
|
|
|
|
do {
|
|
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;) {
|
|
Instruction *I = BI++;
|
|
// The first time through the loop ToSimplify is empty and we try to
|
|
// simplify all instructions. On later iterations ToSimplify is not
|
|
// empty and we only bother simplifying instructions that are in it.
|
|
if (!ToSimplify->empty() && !ToSimplify->count(I))
|
|
continue;
|
|
// Don't waste time simplifying unused instructions.
|
|
if (!I->use_empty())
|
|
if (Value *V = SimplifyInstruction(I, TD, DT)) {
|
|
// Mark all uses for resimplification next time round the loop.
|
|
for (Value::use_iterator UI = I->use_begin(), UE = I->use_end();
|
|
UI != UE; ++UI)
|
|
Next->insert(cast<Instruction>(*UI));
|
|
I->replaceAllUsesWith(V);
|
|
++NumSimplified;
|
|
Changed = true;
|
|
}
|
|
Changed |= RecursivelyDeleteTriviallyDeadInstructions(I);
|
|
}
|
|
|
|
// Place the list of instructions to simplify on the next loop iteration
|
|
// into ToSimplify.
|
|
std::swap(ToSimplify, Next);
|
|
Next->clear();
|
|
} while (!ToSimplify->empty());
|
|
|
|
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();
|
|
}
|