169fdf876e1cceca935561272fd5c238a59c6e9d8Duncan Sands//===------ SimplifyInstructions.cpp - Remove redundant instructions ------===// 269fdf876e1cceca935561272fd5c238a59c6e9d8Duncan Sands// 369fdf876e1cceca935561272fd5c238a59c6e9d8Duncan Sands// The LLVM Compiler Infrastructure 469fdf876e1cceca935561272fd5c238a59c6e9d8Duncan Sands// 569fdf876e1cceca935561272fd5c238a59c6e9d8Duncan Sands// This file is distributed under the University of Illinois Open Source 669fdf876e1cceca935561272fd5c238a59c6e9d8Duncan Sands// License. See LICENSE.TXT for details. 769fdf876e1cceca935561272fd5c238a59c6e9d8Duncan Sands// 869fdf876e1cceca935561272fd5c238a59c6e9d8Duncan Sands//===----------------------------------------------------------------------===// 969fdf876e1cceca935561272fd5c238a59c6e9d8Duncan Sands// 1069fdf876e1cceca935561272fd5c238a59c6e9d8Duncan Sands// This is a utility pass used for testing the InstructionSimplify analysis. 1169fdf876e1cceca935561272fd5c238a59c6e9d8Duncan Sands// The analysis is applied to every instruction, and if it simplifies then the 1269fdf876e1cceca935561272fd5c238a59c6e9d8Duncan Sands// instruction is replaced by the simplification. If you are looking for a pass 1369fdf876e1cceca935561272fd5c238a59c6e9d8Duncan Sands// that performs serious instruction folding, use the instcombine pass instead. 1469fdf876e1cceca935561272fd5c238a59c6e9d8Duncan Sands// 1569fdf876e1cceca935561272fd5c238a59c6e9d8Duncan Sands//===----------------------------------------------------------------------===// 1669fdf876e1cceca935561272fd5c238a59c6e9d8Duncan Sands 1769fdf876e1cceca935561272fd5c238a59c6e9d8Duncan Sands#define DEBUG_TYPE "instsimplify" 18d04a8d4b33ff316ca4cf961e06c9e312eff8e64fChandler Carruth#include "llvm/Transforms/Scalar.h" 198a3d29cf1064e8efbb8c8d5d4653ad147c7b037eDuncan Sands#include "llvm/ADT/DepthFirstIterator.h" 20dc615e41b56daa380e80982097a609bb25afaa82Duncan Sands#include "llvm/ADT/SmallPtrSet.h" 2169fdf876e1cceca935561272fd5c238a59c6e9d8Duncan Sands#include "llvm/ADT/Statistic.h" 2269fdf876e1cceca935561272fd5c238a59c6e9d8Duncan Sands#include "llvm/Analysis/Dominators.h" 2369fdf876e1cceca935561272fd5c238a59c6e9d8Duncan Sands#include "llvm/Analysis/InstructionSimplify.h" 240b8c9a80f20772c3793201ab5b251d3520b9cea3Chandler Carruth#include "llvm/IR/DataLayout.h" 250b8c9a80f20772c3793201ab5b251d3520b9cea3Chandler Carruth#include "llvm/IR/Function.h" 260b8c9a80f20772c3793201ab5b251d3520b9cea3Chandler Carruth#include "llvm/IR/Type.h" 27d04a8d4b33ff316ca4cf961e06c9e312eff8e64fChandler Carruth#include "llvm/Pass.h" 28618c1dbd293d15ee19f61b1156ab8086ad28311aChad Rosier#include "llvm/Target/TargetLibraryInfo.h" 29e95cc25a2267128436bb83af6cb57c07323c8693Duncan Sands#include "llvm/Transforms/Utils/Local.h" 3069fdf876e1cceca935561272fd5c238a59c6e9d8Duncan Sandsusing namespace llvm; 3169fdf876e1cceca935561272fd5c238a59c6e9d8Duncan Sands 3269fdf876e1cceca935561272fd5c238a59c6e9d8Duncan SandsSTATISTIC(NumSimplified, "Number of redundant instructions removed"); 3369fdf876e1cceca935561272fd5c238a59c6e9d8Duncan Sands 3469fdf876e1cceca935561272fd5c238a59c6e9d8Duncan Sandsnamespace { 3569fdf876e1cceca935561272fd5c238a59c6e9d8Duncan Sands struct InstSimplifier : public FunctionPass { 3669fdf876e1cceca935561272fd5c238a59c6e9d8Duncan Sands static char ID; // Pass identification, replacement for typeid 3769fdf876e1cceca935561272fd5c238a59c6e9d8Duncan Sands InstSimplifier() : FunctionPass(ID) { 3869fdf876e1cceca935561272fd5c238a59c6e9d8Duncan Sands initializeInstSimplifierPass(*PassRegistry::getPassRegistry()); 3969fdf876e1cceca935561272fd5c238a59c6e9d8Duncan Sands } 4069fdf876e1cceca935561272fd5c238a59c6e9d8Duncan Sands 4169fdf876e1cceca935561272fd5c238a59c6e9d8Duncan Sands void getAnalysisUsage(AnalysisUsage &AU) const { 4269fdf876e1cceca935561272fd5c238a59c6e9d8Duncan Sands AU.setPreservesCFG(); 43618c1dbd293d15ee19f61b1156ab8086ad28311aChad Rosier AU.addRequired<TargetLibraryInfo>(); 4469fdf876e1cceca935561272fd5c238a59c6e9d8Duncan Sands } 4569fdf876e1cceca935561272fd5c238a59c6e9d8Duncan Sands 4669fdf876e1cceca935561272fd5c238a59c6e9d8Duncan Sands /// runOnFunction - Remove instructions that simplify. 4769fdf876e1cceca935561272fd5c238a59c6e9d8Duncan Sands bool runOnFunction(Function &F) { 4869fdf876e1cceca935561272fd5c238a59c6e9d8Duncan Sands const DominatorTree *DT = getAnalysisIfAvailable<DominatorTree>(); 493574eca1b02600bac4e625297f4ecf745f4c4f32Micah Villmow const DataLayout *TD = getAnalysisIfAvailable<DataLayout>(); 50618c1dbd293d15ee19f61b1156ab8086ad28311aChad Rosier const TargetLibraryInfo *TLI = &getAnalysis<TargetLibraryInfo>(); 51dc615e41b56daa380e80982097a609bb25afaa82Duncan Sands SmallPtrSet<const Instruction*, 8> S1, S2, *ToSimplify = &S1, *Next = &S2; 52e95cc25a2267128436bb83af6cb57c07323c8693Duncan Sands bool Changed = false; 53e95cc25a2267128436bb83af6cb57c07323c8693Duncan Sands 548a3d29cf1064e8efbb8c8d5d4653ad147c7b037eDuncan Sands do { 558a3d29cf1064e8efbb8c8d5d4653ad147c7b037eDuncan Sands for (df_iterator<BasicBlock*> DI = df_begin(&F.getEntryBlock()), 568a3d29cf1064e8efbb8c8d5d4653ad147c7b037eDuncan Sands DE = df_end(&F.getEntryBlock()); DI != DE; ++DI) 578a3d29cf1064e8efbb8c8d5d4653ad147c7b037eDuncan Sands for (BasicBlock::iterator BI = DI->begin(), BE = DI->end(); BI != BE;) { 588a3d29cf1064e8efbb8c8d5d4653ad147c7b037eDuncan Sands Instruction *I = BI++; 59dc615e41b56daa380e80982097a609bb25afaa82Duncan Sands // The first time through the loop ToSimplify is empty and we try to 60dc615e41b56daa380e80982097a609bb25afaa82Duncan Sands // simplify all instructions. On later iterations ToSimplify is not 61dc615e41b56daa380e80982097a609bb25afaa82Duncan Sands // empty and we only bother simplifying instructions that are in it. 62dc615e41b56daa380e80982097a609bb25afaa82Duncan Sands if (!ToSimplify->empty() && !ToSimplify->count(I)) 63dc615e41b56daa380e80982097a609bb25afaa82Duncan Sands continue; 64dc615e41b56daa380e80982097a609bb25afaa82Duncan Sands // Don't waste time simplifying unused instructions. 658a3d29cf1064e8efbb8c8d5d4653ad147c7b037eDuncan Sands if (!I->use_empty()) 66618c1dbd293d15ee19f61b1156ab8086ad28311aChad Rosier if (Value *V = SimplifyInstruction(I, TD, TLI, DT)) { 67dc615e41b56daa380e80982097a609bb25afaa82Duncan Sands // Mark all uses for resimplification next time round the loop. 68dc615e41b56daa380e80982097a609bb25afaa82Duncan Sands for (Value::use_iterator UI = I->use_begin(), UE = I->use_end(); 69dc615e41b56daa380e80982097a609bb25afaa82Duncan Sands UI != UE; ++UI) 70dc615e41b56daa380e80982097a609bb25afaa82Duncan Sands Next->insert(cast<Instruction>(*UI)); 718a3d29cf1064e8efbb8c8d5d4653ad147c7b037eDuncan Sands I->replaceAllUsesWith(V); 728a3d29cf1064e8efbb8c8d5d4653ad147c7b037eDuncan Sands ++NumSimplified; 73dc615e41b56daa380e80982097a609bb25afaa82Duncan Sands Changed = true; 748a3d29cf1064e8efbb8c8d5d4653ad147c7b037eDuncan Sands } 758e0d1c03ca7fd86e6879b4e37d0d7f0e982feef6Benjamin Kramer Changed |= RecursivelyDeleteTriviallyDeadInstructions(I, TLI); 768a3d29cf1064e8efbb8c8d5d4653ad147c7b037eDuncan Sands } 77e95cc25a2267128436bb83af6cb57c07323c8693Duncan Sands 78dc615e41b56daa380e80982097a609bb25afaa82Duncan Sands // Place the list of instructions to simplify on the next loop iteration 79dc615e41b56daa380e80982097a609bb25afaa82Duncan Sands // into ToSimplify. 80dc615e41b56daa380e80982097a609bb25afaa82Duncan Sands std::swap(ToSimplify, Next); 81dc615e41b56daa380e80982097a609bb25afaa82Duncan Sands Next->clear(); 82dc615e41b56daa380e80982097a609bb25afaa82Duncan Sands } while (!ToSimplify->empty()); 831cd0f4637bfb8c93996b09baec8bf2bb220b74caDuncan Sands 8469fdf876e1cceca935561272fd5c238a59c6e9d8Duncan Sands return Changed; 8569fdf876e1cceca935561272fd5c238a59c6e9d8Duncan Sands } 8669fdf876e1cceca935561272fd5c238a59c6e9d8Duncan Sands }; 8769fdf876e1cceca935561272fd5c238a59c6e9d8Duncan Sands} 8869fdf876e1cceca935561272fd5c238a59c6e9d8Duncan Sands 8969fdf876e1cceca935561272fd5c238a59c6e9d8Duncan Sandschar InstSimplifier::ID = 0; 90618c1dbd293d15ee19f61b1156ab8086ad28311aChad RosierINITIALIZE_PASS_BEGIN(InstSimplifier, "instsimplify", 91618c1dbd293d15ee19f61b1156ab8086ad28311aChad Rosier "Remove redundant instructions", false, false) 92618c1dbd293d15ee19f61b1156ab8086ad28311aChad RosierINITIALIZE_PASS_DEPENDENCY(TargetLibraryInfo) 93618c1dbd293d15ee19f61b1156ab8086ad28311aChad RosierINITIALIZE_PASS_END(InstSimplifier, "instsimplify", 94618c1dbd293d15ee19f61b1156ab8086ad28311aChad Rosier "Remove redundant instructions", false, false) 9569fdf876e1cceca935561272fd5c238a59c6e9d8Duncan Sandschar &llvm::InstructionSimplifierID = InstSimplifier::ID; 9669fdf876e1cceca935561272fd5c238a59c6e9d8Duncan Sands 9769fdf876e1cceca935561272fd5c238a59c6e9d8Duncan Sands// Public interface to the simplify instructions pass. 9869fdf876e1cceca935561272fd5c238a59c6e9d8Duncan SandsFunctionPass *llvm::createInstructionSimplifierPass() { 9969fdf876e1cceca935561272fd5c238a59c6e9d8Duncan Sands return new InstSimplifier(); 10069fdf876e1cceca935561272fd5c238a59c6e9d8Duncan Sands} 101