1 //===------ SimplifyInstructions.cpp - Remove redundant instructions ------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This is a utility pass used for testing the InstructionSimplify analysis.
11 // The analysis is applied to every instruction, and if it simplifies then the
12 // instruction is replaced by the simplification. If you are looking for a pass
13 // that performs serious instruction folding, use the instcombine pass instead.
15 //===----------------------------------------------------------------------===//
17 #define DEBUG_TYPE "instsimplify"
18 #include "llvm/Function.h"
19 #include "llvm/Pass.h"
20 #include "llvm/Type.h"
21 #include "llvm/ADT/Statistic.h"
22 #include "llvm/Analysis/Dominators.h"
23 #include "llvm/Analysis/InstructionSimplify.h"
24 #include "llvm/Target/TargetData.h"
25 #include "llvm/Transforms/Scalar.h"
28 STATISTIC(NumSimplified, "Number of redundant instructions removed");
31 struct InstSimplifier : public FunctionPass {
32 static char ID; // Pass identification, replacement for typeid
33 InstSimplifier() : FunctionPass(ID) {
34 initializeInstSimplifierPass(*PassRegistry::getPassRegistry());
37 void getAnalysisUsage(AnalysisUsage &AU) const {
41 /// runOnFunction - Remove instructions that simplify.
42 bool runOnFunction(Function &F) {
44 const TargetData *TD = getAnalysisIfAvailable<TargetData>();
45 const DominatorTree *DT = getAnalysisIfAvailable<DominatorTree>();
46 for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
47 for (BasicBlock::iterator BI = BB->begin(), BE = BB->end(); BI != BE;) {
48 Instruction *I = BI++;
49 if (Value *V = SimplifyInstruction(I, TD, DT)) {
50 I->replaceAllUsesWith(V);
61 char InstSimplifier::ID = 0;
62 INITIALIZE_PASS(InstSimplifier, "instsimplify", "Remove redundant instructions",
64 char &llvm::InstructionSimplifierID = InstSimplifier::ID;
66 // Public interface to the simplify instructions pass.
67 FunctionPass *llvm::createInstructionSimplifierPass() {
68 return new InstSimplifier();