IndVarSimplify.cpp revision 0d7d3656f3d10c510353d69472de4c0c0691b2e6
16148c02591bd83da7b957589c4bbf6f9720d503fChris Lattner//===- IndVarSimplify.cpp - Induction Variable Elimination ----------------===// 2fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukman// 3b576c94c15af9a440f69d9d03c2afead7971118cJohn Criswell// The LLVM Compiler Infrastructure 4b576c94c15af9a440f69d9d03c2afead7971118cJohn Criswell// 5b576c94c15af9a440f69d9d03c2afead7971118cJohn Criswell// This file was developed by the LLVM research group and is distributed under 6b576c94c15af9a440f69d9d03c2afead7971118cJohn Criswell// the University of Illinois Open Source License. See LICENSE.TXT for details. 7fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukman// 8b576c94c15af9a440f69d9d03c2afead7971118cJohn Criswell//===----------------------------------------------------------------------===// 96148c02591bd83da7b957589c4bbf6f9720d503fChris Lattner// 1040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// This transformation analyzes and transforms the induction variables (and 1140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// computations derived from them) into simpler forms suitable for subsequent 1240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// analysis and transformation. 1340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// 1447a53ac726ceb1ac11bc1326be3fbe095f726b0dReid Spencer// This transformation makes the following changes to each loop with an 1540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// identifiable induction variable: 1640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// 1. All loops are transformed to have a SINGLE canonical induction variable 1740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// which starts at zero and steps by one. 1840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// 2. The canonical induction variable is guaranteed to be the first PHI node 1940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// in the loop header block. 2040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// 3. Any pointer arithmetic recurrences are raised to use array subscripts. 2140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// 2240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// If the trip count of a loop is computable, this pass also makes the following 2340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// changes: 2440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// 1. The exit condition for the loop is canonicalized to compare the 2540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// induction value against the exit value. This turns loops like: 2640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// 'for (i = 7; i*i < 1000; ++i)' into 'for (i = 0; i != 25; ++i)' 2740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// 2. Any use outside of the loop of an expression derived from the indvar 2840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// is changed to compute the derived value outside of the loop, eliminating 2940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// the dependence on the exit value of the induction variable. If the only 3040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// purpose of the loop is to compute the exit value of some derived 3140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// expression, this transformation will make the loop dead. 3240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// 3340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// This transformation should be followed by strength reduction after all of the 3440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// desired loop transformations have been performed. Additionally, on targets 3540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// where it is profitable, the loop could be transformed to count down to zero 3640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// (the "do loop" optimization). 376148c02591bd83da7b957589c4bbf6f9720d503fChris Lattner// 386148c02591bd83da7b957589c4bbf6f9720d503fChris Lattner//===----------------------------------------------------------------------===// 396148c02591bd83da7b957589c4bbf6f9720d503fChris Lattner 400e5f499638c8d277b9dc4a4385712177c53b5681Chris Lattner#define DEBUG_TYPE "indvars" 41022103b3f33febb7e54b8fdf2c9bc461eea78cbaChris Lattner#include "llvm/Transforms/Scalar.h" 4240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner#include "llvm/BasicBlock.h" 4359fdaeeae8f183e18bb6ad5c382ca23e28e6aaf6Chris Lattner#include "llvm/Constants.h" 4418b3c97bc773b24a66eb779e85da1820b0f16b31Chris Lattner#include "llvm/Instructions.h" 4540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner#include "llvm/Type.h" 4636f891bdf6cf38fcc655a0930ca18664e18518d4Nate Begeman#include "llvm/Analysis/ScalarEvolutionExpander.h" 4747df12d80db90e125e9f2ff764286ee11665476dJohn Criswell#include "llvm/Analysis/LoopInfo.h" 485ee99979065d75605d150d7e567e4351024aae8fDevang Patel#include "llvm/Analysis/LoopPass.h" 49455889aa79e3463a4b0f2161e3d9d72a683268b6Chris Lattner#include "llvm/Support/CFG.h" 509133fe28954d498fc4de13064c7d65bd811de02cReid Spencer#include "llvm/Support/Compiler.h" 51ee4f13a9046c380725cdeab62d57722db375c473Chris Lattner#include "llvm/Support/Debug.h" 52a4b9c7841f94b6a3a2ba6c562b5dc4f4de02c637Chris Lattner#include "llvm/Support/GetElementPtrTypeIterator.h" 5347df12d80db90e125e9f2ff764286ee11665476dJohn Criswell#include "llvm/Transforms/Utils/Local.h" 54551ccae044b0ff658fe629dd67edd5ffe75d10e8Reid Spencer#include "llvm/Support/CommandLine.h" 55a54b7cbd452b3adb2f51346140d996b29c2cdb30Reid Spencer#include "llvm/ADT/SmallVector.h" 56551ccae044b0ff658fe629dd67edd5ffe75d10e8Reid Spencer#include "llvm/ADT/Statistic.h" 5747df12d80db90e125e9f2ff764286ee11665476dJohn Criswellusing namespace llvm; 58d0fde30ce850b78371fd1386338350591f9ff494Brian Gaeke 590e5f499638c8d277b9dc4a4385712177c53b5681Chris LattnerSTATISTIC(NumRemoved , "Number of aux indvars removed"); 600e5f499638c8d277b9dc4a4385712177c53b5681Chris LattnerSTATISTIC(NumPointer , "Number of pointer indvars promoted"); 610e5f499638c8d277b9dc4a4385712177c53b5681Chris LattnerSTATISTIC(NumInserted, "Number of canonical indvars added"); 620e5f499638c8d277b9dc4a4385712177c53b5681Chris LattnerSTATISTIC(NumReplaced, "Number of exit values replaced"); 630e5f499638c8d277b9dc4a4385712177c53b5681Chris LattnerSTATISTIC(NumLFTR , "Number of loop exit tests replaced"); 643324e718bc9ac2ede08a14c325848b576849542bChris Lattner 650e5f499638c8d277b9dc4a4385712177c53b5681Chris Lattnernamespace { 665ee99979065d75605d150d7e567e4351024aae8fDevang Patel class VISIBILITY_HIDDEN IndVarSimplify : public LoopPass { 6740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner LoopInfo *LI; 6840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner ScalarEvolution *SE; 6915cad759fe2048ac5eb137c6bb0ab7287538677eChris Lattner bool Changed; 703324e718bc9ac2ede08a14c325848b576849542bChris Lattner public: 71794fd75c67a2cdc128d67342c6d88a504d186896Devang Patel 72ecd94c804a563f2a86572dcf1d2e81f397e19daaNick Lewycky static char ID; // Pass identification, replacement for typeid 73794fd75c67a2cdc128d67342c6d88a504d186896Devang Patel IndVarSimplify() : LoopPass((intptr_t)&ID) {} 74794fd75c67a2cdc128d67342c6d88a504d186896Devang Patel 755ee99979065d75605d150d7e567e4351024aae8fDevang Patel bool runOnLoop(Loop *L, LPPassManager &LPM); 765ee99979065d75605d150d7e567e4351024aae8fDevang Patel bool doInitialization(Loop *L, LPPassManager &LPM); 775ee99979065d75605d150d7e567e4351024aae8fDevang Patel virtual void getAnalysisUsage(AnalysisUsage &AU) const { 785ee99979065d75605d150d7e567e4351024aae8fDevang Patel AU.addRequiredID(LCSSAID); 795ee99979065d75605d150d7e567e4351024aae8fDevang Patel AU.addRequiredID(LoopSimplifyID); 805ee99979065d75605d150d7e567e4351024aae8fDevang Patel AU.addRequired<ScalarEvolution>(); 815ee99979065d75605d150d7e567e4351024aae8fDevang Patel AU.addRequired<LoopInfo>(); 825ee99979065d75605d150d7e567e4351024aae8fDevang Patel AU.addPreservedID(LoopSimplifyID); 835ee99979065d75605d150d7e567e4351024aae8fDevang Patel AU.addPreservedID(LCSSAID); 845ee99979065d75605d150d7e567e4351024aae8fDevang Patel AU.setPreservesCFG(); 855ee99979065d75605d150d7e567e4351024aae8fDevang Patel } 863324e718bc9ac2ede08a14c325848b576849542bChris Lattner 8740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner private: 885ee99979065d75605d150d7e567e4351024aae8fDevang Patel 8940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner void EliminatePointerRecurrence(PHINode *PN, BasicBlock *Preheader, 9040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner std::set<Instruction*> &DeadInsts); 919ba46c13bf3d49a5b697227c88ef987951e6b50dChris Lattner Instruction *LinearFunctionTestReplace(Loop *L, SCEV *IterationCount, 929ba46c13bf3d49a5b697227c88ef987951e6b50dChris Lattner SCEVExpander &RW); 9340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner void RewriteLoopExitValues(Loop *L); 9440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner 9540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner void DeleteTriviallyDeadInstructions(std::set<Instruction*> &Insts); 963324e718bc9ac2ede08a14c325848b576849542bChris Lattner }; 97794fd75c67a2cdc128d67342c6d88a504d186896Devang Patel 981997473cf72957d0e70322e2fe6fe2ab141c58a6Devang Patel char IndVarSimplify::ID = 0; 997f8897f22e88271cfa114998a4d6088e7c8e8e11Chris Lattner RegisterPass<IndVarSimplify> X("indvars", "Canonicalize Induction Variables"); 1005e76140536ba66fadeced1cd892f79616f407e3cChris Lattner} 101394437ff7eaccfe1de92fe14d0022ca0addf3e41Chris Lattner 1025ee99979065d75605d150d7e567e4351024aae8fDevang PatelLoopPass *llvm::createIndVarSimplifyPass() { 1033324e718bc9ac2ede08a14c325848b576849542bChris Lattner return new IndVarSimplify(); 104394437ff7eaccfe1de92fe14d0022ca0addf3e41Chris Lattner} 105394437ff7eaccfe1de92fe14d0022ca0addf3e41Chris Lattner 10640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner/// DeleteTriviallyDeadInstructions - If any of the instructions is the 10740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner/// specified set are trivially dead, delete them and see if this makes any of 10840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner/// their operands subsequently dead. 10940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattnervoid IndVarSimplify:: 11040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris LattnerDeleteTriviallyDeadInstructions(std::set<Instruction*> &Insts) { 11140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner while (!Insts.empty()) { 11240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner Instruction *I = *Insts.begin(); 11340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner Insts.erase(Insts.begin()); 11440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner if (isInstructionTriviallyDead(I)) { 11540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) 11640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner if (Instruction *U = dyn_cast<Instruction>(I->getOperand(i))) 11740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner Insts.insert(U); 1185cec4db6ae13a41d04d86f37e347fc5b5997c948Dan Gohman SE->deleteValueFromRecords(I); 119ee4f13a9046c380725cdeab62d57722db375c473Chris Lattner DOUT << "INDVARS: Deleting: " << *I; 120a4b9c7841f94b6a3a2ba6c562b5dc4f4de02c637Chris Lattner I->eraseFromParent(); 12140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner Changed = true; 12240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner } 12340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner } 12440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner} 1253324e718bc9ac2ede08a14c325848b576849542bChris Lattner 1266148c02591bd83da7b957589c4bbf6f9720d503fChris Lattner 12740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner/// EliminatePointerRecurrence - Check to see if this is a trivial GEP pointer 12840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner/// recurrence. If so, change it into an integer recurrence, permitting 12940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner/// analysis by the SCEV routines. 130fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukmanvoid IndVarSimplify::EliminatePointerRecurrence(PHINode *PN, 13140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner BasicBlock *Preheader, 13240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner std::set<Instruction*> &DeadInsts) { 13340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner assert(PN->getNumIncomingValues() == 2 && "Noncanonicalized loop!"); 13440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner unsigned PreheaderIdx = PN->getBasicBlockIndex(Preheader); 13540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner unsigned BackedgeIdx = PreheaderIdx^1; 13640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner if (GetElementPtrInst *GEPI = 137cda9ca5a4fed09ea3788b572dbddabf2a5a7a5d9Chris Lattner dyn_cast<GetElementPtrInst>(PN->getIncomingValue(BackedgeIdx))) 13840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner if (GEPI->getOperand(0) == PN) { 139cda9ca5a4fed09ea3788b572dbddabf2a5a7a5d9Chris Lattner assert(GEPI->getNumOperands() == 2 && "GEP types must match!"); 140ee4f13a9046c380725cdeab62d57722db375c473Chris Lattner DOUT << "INDVARS: Eliminating pointer recurrence: " << *GEPI; 141ee4f13a9046c380725cdeab62d57722db375c473Chris Lattner 14240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // Okay, we found a pointer recurrence. Transform this pointer 14340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // recurrence into an integer recurrence. Compute the value that gets 14440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // added to the pointer at every iteration. 14540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner Value *AddedVal = GEPI->getOperand(1); 14640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner 14740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // Insert a new integer PHI node into the top of the block. 14840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner PHINode *NewPhi = new PHINode(AddedVal->getType(), 14940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner PN->getName()+".rec", PN); 150c5c5e6afe584ffbd2bf2ce755e65bc89f170053aChris Lattner NewPhi->addIncoming(Constant::getNullValue(NewPhi->getType()), Preheader); 151c5c5e6afe584ffbd2bf2ce755e65bc89f170053aChris Lattner 15240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // Create the new add instruction. 153c5c5e6afe584ffbd2bf2ce755e65bc89f170053aChris Lattner Value *NewAdd = BinaryOperator::createAdd(NewPhi, AddedVal, 154c5c5e6afe584ffbd2bf2ce755e65bc89f170053aChris Lattner GEPI->getName()+".rec", GEPI); 15540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner NewPhi->addIncoming(NewAdd, PN->getIncomingBlock(BackedgeIdx)); 156fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukman 15740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // Update the existing GEP to use the recurrence. 15840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner GEPI->setOperand(0, PN->getIncomingValue(PreheaderIdx)); 159fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukman 16040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // Update the GEP to use the new recurrence we just inserted. 16140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner GEPI->setOperand(1, NewAdd); 16240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner 163a4b9c7841f94b6a3a2ba6c562b5dc4f4de02c637Chris Lattner // If the incoming value is a constant expr GEP, try peeling out the array 164a4b9c7841f94b6a3a2ba6c562b5dc4f4de02c637Chris Lattner // 0 index if possible to make things simpler. 165a4b9c7841f94b6a3a2ba6c562b5dc4f4de02c637Chris Lattner if (ConstantExpr *CE = dyn_cast<ConstantExpr>(GEPI->getOperand(0))) 166a4b9c7841f94b6a3a2ba6c562b5dc4f4de02c637Chris Lattner if (CE->getOpcode() == Instruction::GetElementPtr) { 167a4b9c7841f94b6a3a2ba6c562b5dc4f4de02c637Chris Lattner unsigned NumOps = CE->getNumOperands(); 168a4b9c7841f94b6a3a2ba6c562b5dc4f4de02c637Chris Lattner assert(NumOps > 1 && "CE folding didn't work!"); 169a4b9c7841f94b6a3a2ba6c562b5dc4f4de02c637Chris Lattner if (CE->getOperand(NumOps-1)->isNullValue()) { 170a4b9c7841f94b6a3a2ba6c562b5dc4f4de02c637Chris Lattner // Check to make sure the last index really is an array index. 1711730078d5f553d7516a06e098e6c2089dc8bef9cChris Lattner gep_type_iterator GTI = gep_type_begin(CE); 172ceda605fd7d0e3532a22743538c6d118fe5e40c1Chris Lattner for (unsigned i = 1, e = CE->getNumOperands()-1; 173a4b9c7841f94b6a3a2ba6c562b5dc4f4de02c637Chris Lattner i != e; ++i, ++GTI) 174a4b9c7841f94b6a3a2ba6c562b5dc4f4de02c637Chris Lattner /*empty*/; 175a4b9c7841f94b6a3a2ba6c562b5dc4f4de02c637Chris Lattner if (isa<SequentialType>(*GTI)) { 176a4b9c7841f94b6a3a2ba6c562b5dc4f4de02c637Chris Lattner // Pull the last index out of the constant expr GEP. 17755eb1c47de30a6b4e8707b6392e878e32a6583e9Chris Lattner SmallVector<Value*, 8> CEIdxs(CE->op_begin()+1, CE->op_end()-1); 178a4b9c7841f94b6a3a2ba6c562b5dc4f4de02c637Chris Lattner Constant *NCE = ConstantExpr::getGetElementPtr(CE->getOperand(0), 17955eb1c47de30a6b4e8707b6392e878e32a6583e9Chris Lattner &CEIdxs[0], 18055eb1c47de30a6b4e8707b6392e878e32a6583e9Chris Lattner CEIdxs.size()); 181cae5754619433aed7be74abbf1c0551a82d369cbReid Spencer GetElementPtrInst *NGEPI = new GetElementPtrInst( 182cae5754619433aed7be74abbf1c0551a82d369cbReid Spencer NCE, Constant::getNullValue(Type::Int32Ty), NewAdd, 183cae5754619433aed7be74abbf1c0551a82d369cbReid Spencer GEPI->getName(), GEPI); 1845cec4db6ae13a41d04d86f37e347fc5b5997c948Dan Gohman SE->deleteValueFromRecords(GEPI); 185a4b9c7841f94b6a3a2ba6c562b5dc4f4de02c637Chris Lattner GEPI->replaceAllUsesWith(NGEPI); 186a4b9c7841f94b6a3a2ba6c562b5dc4f4de02c637Chris Lattner GEPI->eraseFromParent(); 187a4b9c7841f94b6a3a2ba6c562b5dc4f4de02c637Chris Lattner GEPI = NGEPI; 188a4b9c7841f94b6a3a2ba6c562b5dc4f4de02c637Chris Lattner } 189a4b9c7841f94b6a3a2ba6c562b5dc4f4de02c637Chris Lattner } 190a4b9c7841f94b6a3a2ba6c562b5dc4f4de02c637Chris Lattner } 191a4b9c7841f94b6a3a2ba6c562b5dc4f4de02c637Chris Lattner 192a4b9c7841f94b6a3a2ba6c562b5dc4f4de02c637Chris Lattner 19340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // Finally, if there are any other users of the PHI node, we must 19440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // insert a new GEP instruction that uses the pre-incremented version 19540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // of the induction amount. 19640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner if (!PN->use_empty()) { 19740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner BasicBlock::iterator InsertPos = PN; ++InsertPos; 19840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner while (isa<PHINode>(InsertPos)) ++InsertPos; 19940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner Value *PreInc = 20040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner new GetElementPtrInst(PN->getIncomingValue(PreheaderIdx), 2016934a04a8c15e9971cd1ea4d5c8df2d7afdd5be5Chris Lattner NewPhi, "", InsertPos); 2026934a04a8c15e9971cd1ea4d5c8df2d7afdd5be5Chris Lattner PreInc->takeName(PN); 20340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner PN->replaceAllUsesWith(PreInc); 20440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner } 20540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner 20640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // Delete the old PHI for sure, and the GEP if its otherwise unused. 20740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner DeadInsts.insert(PN); 2083324e718bc9ac2ede08a14c325848b576849542bChris Lattner 20940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner ++NumPointer; 21040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner Changed = true; 21140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner } 21240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner} 2133324e718bc9ac2ede08a14c325848b576849542bChris Lattner 21440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner/// LinearFunctionTestReplace - This method rewrites the exit condition of the 21559fdaeeae8f183e18bb6ad5c382ca23e28e6aaf6Chris Lattner/// loop to be a canonical != comparison against the incremented loop induction 21659fdaeeae8f183e18bb6ad5c382ca23e28e6aaf6Chris Lattner/// variable. This pass is able to rewrite the exit tests of any loop where the 21759fdaeeae8f183e18bb6ad5c382ca23e28e6aaf6Chris Lattner/// SCEV analysis can determine a loop-invariant trip count of the loop, which 21859fdaeeae8f183e18bb6ad5c382ca23e28e6aaf6Chris Lattner/// is actually a much broader range than just linear tests. 2199ba46c13bf3d49a5b697227c88ef987951e6b50dChris Lattner/// 2209ba46c13bf3d49a5b697227c88ef987951e6b50dChris Lattner/// This method returns a "potentially dead" instruction whose computation chain 2219ba46c13bf3d49a5b697227c88ef987951e6b50dChris Lattner/// should be deleted when convenient. 2229ba46c13bf3d49a5b697227c88ef987951e6b50dChris LattnerInstruction *IndVarSimplify::LinearFunctionTestReplace(Loop *L, 2239ba46c13bf3d49a5b697227c88ef987951e6b50dChris Lattner SCEV *IterationCount, 2249ba46c13bf3d49a5b697227c88ef987951e6b50dChris Lattner SCEVExpander &RW) { 22540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // Find the exit block for the loop. We can currently only handle loops with 22640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // a single exit. 227f1ab4b4eac5603d19c20f4a508f93a118a52bdd5Chris Lattner std::vector<BasicBlock*> ExitBlocks; 228f1ab4b4eac5603d19c20f4a508f93a118a52bdd5Chris Lattner L->getExitBlocks(ExitBlocks); 2299ba46c13bf3d49a5b697227c88ef987951e6b50dChris Lattner if (ExitBlocks.size() != 1) return 0; 230f1ab4b4eac5603d19c20f4a508f93a118a52bdd5Chris Lattner BasicBlock *ExitBlock = ExitBlocks[0]; 23140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner 23240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // Make sure there is only one predecessor block in the loop. 23340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner BasicBlock *ExitingBlock = 0; 23440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner for (pred_iterator PI = pred_begin(ExitBlock), PE = pred_end(ExitBlock); 23540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner PI != PE; ++PI) 23640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner if (L->contains(*PI)) { 23740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner if (ExitingBlock == 0) 23840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner ExitingBlock = *PI; 23940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner else 2409ba46c13bf3d49a5b697227c88ef987951e6b50dChris Lattner return 0; // Multiple exits from loop to this block. 24140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner } 24240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner assert(ExitingBlock && "Loop info is broken"); 24340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner 24440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner if (!isa<BranchInst>(ExitingBlock->getTerminator())) 2459ba46c13bf3d49a5b697227c88ef987951e6b50dChris Lattner return 0; // Can't rewrite non-branch yet 24640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner BranchInst *BI = cast<BranchInst>(ExitingBlock->getTerminator()); 24740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner assert(BI->isConditional() && "Must be conditional to be part of loop!"); 24840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner 2499ba46c13bf3d49a5b697227c88ef987951e6b50dChris Lattner Instruction *PotentiallyDeadInst = dyn_cast<Instruction>(BI->getCondition()); 2509ba46c13bf3d49a5b697227c88ef987951e6b50dChris Lattner 251d244057a48660c3cd30d219118ece3f947947790Chris Lattner // If the exiting block is not the same as the backedge block, we must compare 252d244057a48660c3cd30d219118ece3f947947790Chris Lattner // against the preincremented value, otherwise we prefer to compare against 253d244057a48660c3cd30d219118ece3f947947790Chris Lattner // the post-incremented value. 254d244057a48660c3cd30d219118ece3f947947790Chris Lattner BasicBlock *Header = L->getHeader(); 255d244057a48660c3cd30d219118ece3f947947790Chris Lattner pred_iterator HPI = pred_begin(Header); 256d244057a48660c3cd30d219118ece3f947947790Chris Lattner assert(HPI != pred_end(Header) && "Loop with zero preds???"); 257d244057a48660c3cd30d219118ece3f947947790Chris Lattner if (!L->contains(*HPI)) ++HPI; 258d244057a48660c3cd30d219118ece3f947947790Chris Lattner assert(HPI != pred_end(Header) && L->contains(*HPI) && 259d244057a48660c3cd30d219118ece3f947947790Chris Lattner "No backedge in loop?"); 260d244057a48660c3cd30d219118ece3f947947790Chris Lattner 261d244057a48660c3cd30d219118ece3f947947790Chris Lattner SCEVHandle TripCount = IterationCount; 262d244057a48660c3cd30d219118ece3f947947790Chris Lattner Value *IndVar; 263d244057a48660c3cd30d219118ece3f947947790Chris Lattner if (*HPI == ExitingBlock) { 264d244057a48660c3cd30d219118ece3f947947790Chris Lattner // The IterationCount expression contains the number of times that the 265d244057a48660c3cd30d219118ece3f947947790Chris Lattner // backedge actually branches to the loop header. This is one less than the 266d244057a48660c3cd30d219118ece3f947947790Chris Lattner // number of times the loop executes, so add one to it. 267e19dd875987f8327cd93a502d4a05fc1f37064eeDan Gohman ConstantInt *OneC = ConstantInt::get(IterationCount->getType(), 1); 268e19dd875987f8327cd93a502d4a05fc1f37064eeDan Gohman TripCount = SCEVAddExpr::get(IterationCount, SCEVConstant::get(OneC)); 269d244057a48660c3cd30d219118ece3f947947790Chris Lattner IndVar = L->getCanonicalInductionVariableIncrement(); 270d244057a48660c3cd30d219118ece3f947947790Chris Lattner } else { 271d244057a48660c3cd30d219118ece3f947947790Chris Lattner // We have to use the preincremented value... 272d244057a48660c3cd30d219118ece3f947947790Chris Lattner IndVar = L->getCanonicalInductionVariable(); 273d244057a48660c3cd30d219118ece3f947947790Chris Lattner } 274ee4f13a9046c380725cdeab62d57722db375c473Chris Lattner 275ee4f13a9046c380725cdeab62d57722db375c473Chris Lattner DOUT << "INDVARS: LFTR: TripCount = " << *TripCount 276ee4f13a9046c380725cdeab62d57722db375c473Chris Lattner << " IndVar = " << *IndVar << "\n"; 27759fdaeeae8f183e18bb6ad5c382ca23e28e6aaf6Chris Lattner 27840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // Expand the code for the iteration count into the preheader of the loop. 27940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner BasicBlock *Preheader = L->getLoopPreheader(); 280d19534add90a2a894af61523b830887097bb780bDan Gohman Value *ExitCnt = RW.expandCodeFor(TripCount, Preheader->getTerminator()); 28140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner 282e4d87aa2de6e52952dca73716386db09aad5a8fdReid Spencer // Insert a new icmp_ne or icmp_eq instruction before the branch. 283e4d87aa2de6e52952dca73716386db09aad5a8fdReid Spencer ICmpInst::Predicate Opcode; 28440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner if (L->contains(BI->getSuccessor(0))) 285e4d87aa2de6e52952dca73716386db09aad5a8fdReid Spencer Opcode = ICmpInst::ICMP_NE; 28640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner else 287e4d87aa2de6e52952dca73716386db09aad5a8fdReid Spencer Opcode = ICmpInst::ICMP_EQ; 28840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner 289e4d87aa2de6e52952dca73716386db09aad5a8fdReid Spencer Value *Cond = new ICmpInst(Opcode, IndVar, ExitCnt, "exitcond", BI); 29040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner BI->setCondition(Cond); 29140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner ++NumLFTR; 29240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner Changed = true; 2939ba46c13bf3d49a5b697227c88ef987951e6b50dChris Lattner return PotentiallyDeadInst; 29440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner} 2953324e718bc9ac2ede08a14c325848b576849542bChris Lattner 2963324e718bc9ac2ede08a14c325848b576849542bChris Lattner 29740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner/// RewriteLoopExitValues - Check to see if this loop has a computable 29840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner/// loop-invariant execution count. If so, this means that we can compute the 29940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner/// final value of any expressions that are recurrent in the loop, and 30040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner/// substitute the exit values from the loop into any instructions outside of 30140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner/// the loop that use the final values of the current expressions. 30240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattnervoid IndVarSimplify::RewriteLoopExitValues(Loop *L) { 30340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner BasicBlock *Preheader = L->getLoopPreheader(); 30440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner 30540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // Scan all of the instructions in the loop, looking at those that have 30640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // extra-loop users and which are recurrences. 3074a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner SCEVExpander Rewriter(*SE, *LI); 30840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner 30940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // We insert the code into the preheader of the loop if the loop contains 31040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // multiple exit blocks, or in the exit block if there is exactly one. 31140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner BasicBlock *BlockToInsertInto; 312f1ab4b4eac5603d19c20f4a508f93a118a52bdd5Chris Lattner std::vector<BasicBlock*> ExitBlocks; 3139f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner L->getUniqueExitBlocks(ExitBlocks); 314f1ab4b4eac5603d19c20f4a508f93a118a52bdd5Chris Lattner if (ExitBlocks.size() == 1) 315f1ab4b4eac5603d19c20f4a508f93a118a52bdd5Chris Lattner BlockToInsertInto = ExitBlocks[0]; 31640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner else 31740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner BlockToInsertInto = Preheader; 31840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner BasicBlock::iterator InsertPt = BlockToInsertInto->begin(); 31940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner while (isa<PHINode>(InsertPt)) ++InsertPt; 32040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner 32120aa098ba694aa7e3f5fb5a52d22dba7c1e857aeChris Lattner bool HasConstantItCount = isa<SCEVConstant>(SE->getIterationCount(L)); 32220aa098ba694aa7e3f5fb5a52d22dba7c1e857aeChris Lattner 32340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner std::set<Instruction*> InstructionsToDelete; 3249f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner std::map<Instruction*, Value*> ExitValues; 3259f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner 3269f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner // Find all values that are computed inside the loop, but used outside of it. 3279f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner // Because of LCSSA, these values will only occur in LCSSA PHI Nodes. Scan 3289f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner // the exit blocks of the loop to find them. 3299f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner for (unsigned i = 0, e = ExitBlocks.size(); i != e; ++i) { 3309f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner BasicBlock *ExitBB = ExitBlocks[i]; 3319f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner 3329f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner // If there are no PHI nodes in this exit block, then no values defined 3339f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner // inside the loop are used on this path, skip it. 3349f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner PHINode *PN = dyn_cast<PHINode>(ExitBB->begin()); 3359f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner if (!PN) continue; 3369f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner 3379f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner unsigned NumPreds = PN->getNumIncomingValues(); 3389f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner 3399f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner // Iterate over all of the PHI nodes. 3409f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner BasicBlock::iterator BBI = ExitBB->begin(); 3419f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner while ((PN = dyn_cast<PHINode>(BBI++))) { 342c9838f25d53d3dd7d38949ef6c28f2505a110f45Chris Lattner 3439f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner // Iterate over all of the values in all the PHI nodes. 3449f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner for (unsigned i = 0; i != NumPreds; ++i) { 3459f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner // If the value being merged in is not integer or is not defined 3469f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner // in the loop, skip it. 3479f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner Value *InVal = PN->getIncomingValue(i); 3489f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner if (!isa<Instruction>(InVal) || 3499f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner // SCEV only supports integer expressions for now. 3509f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner !isa<IntegerType>(InVal->getType())) 3519f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner continue; 3529f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner 3539f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner // If this pred is for a subloop, not L itself, skip it. 3549f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner if (LI->getLoopFor(PN->getIncomingBlock(i)) != L) 3559f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner continue; // The Block is in a subloop, skip it. 3569f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner 3579f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner // Check that InVal is defined in the loop. 3589f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner Instruction *Inst = cast<Instruction>(InVal); 3599f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner if (!L->contains(Inst->getParent())) 3609f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner continue; 3619f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner 3629f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner // We require that this value either have a computable evolution or that 3639f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner // the loop have a constant iteration count. In the case where the loop 3649f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner // has a constant iteration count, we can sometimes force evaluation of 3659f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner // the exit value through brute force. 3669f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner SCEVHandle SH = SE->getSCEV(Inst); 3679f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner if (!SH->hasComputableLoopEvolution(L) && !HasConstantItCount) 3689f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner continue; // Cannot get exit evolution for the loop value. 3699f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner 3709f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner // Okay, this instruction has a user outside of the current loop 3719f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner // and varies predictably *inside* the loop. Evaluate the value it 3729f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner // contains when the loop exits, if possible. 3739f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner SCEVHandle ExitValue = SE->getSCEVAtScope(Inst, L->getParentLoop()); 3749f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner if (isa<SCEVCouldNotCompute>(ExitValue) || 3759f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner !ExitValue->isLoopInvariant(L)) 3769f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner continue; 3779f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner 3789f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner Changed = true; 3799f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner ++NumReplaced; 3809caed5440d59dac4b388152fe8b993dc0491e5e9Chris Lattner 3819f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner // See if we already computed the exit value for the instruction, if so, 3829f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner // just reuse it. 3839f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner Value *&ExitVal = ExitValues[Inst]; 3849f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner if (!ExitVal) 385d19534add90a2a894af61523b830887097bb780bDan Gohman ExitVal = Rewriter.expandCodeFor(ExitValue, InsertPt); 3869f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner 3879f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner DOUT << "INDVARS: RLEV: AfterLoopVal = " << *ExitVal 3889f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner << " LoopVal = " << *Inst << "\n"; 3899caed5440d59dac4b388152fe8b993dc0491e5e9Chris Lattner 3909f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner PN->setIncomingValue(i, ExitVal); 3919f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner 3929f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner // If this instruction is dead now, schedule it to be removed. 3939f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner if (Inst->use_empty()) 3949f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner InstructionsToDelete.insert(Inst); 3959f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner 3969f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner // See if this is a single-entry LCSSA PHI node. If so, we can (and 3979f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner // have to) remove 3989caed5440d59dac4b388152fe8b993dc0491e5e9Chris Lattner // the PHI entirely. This is safe, because the NewVal won't be variant 3999caed5440d59dac4b388152fe8b993dc0491e5e9Chris Lattner // in the loop, so we don't need an LCSSA phi node anymore. 4009f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner if (NumPreds == 1) { 4015cec4db6ae13a41d04d86f37e347fc5b5997c948Dan Gohman SE->deleteValueFromRecords(PN); 4029f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner PN->replaceAllUsesWith(ExitVal); 4039f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner PN->eraseFromParent(); 4049f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner break; 405c9838f25d53d3dd7d38949ef6c28f2505a110f45Chris Lattner } 4064bd09d70cceb3851f7eb1c2f98338b3071d405f3Chris Lattner } 407c9838f25d53d3dd7d38949ef6c28f2505a110f45Chris Lattner } 408c9838f25d53d3dd7d38949ef6c28f2505a110f45Chris Lattner } 409c9838f25d53d3dd7d38949ef6c28f2505a110f45Chris Lattner 41040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner DeleteTriviallyDeadInstructions(InstructionsToDelete); 41140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner} 41215cad759fe2048ac5eb137c6bb0ab7287538677eChris Lattner 4135ee99979065d75605d150d7e567e4351024aae8fDevang Patelbool IndVarSimplify::doInitialization(Loop *L, LPPassManager &LPM) { 41415cad759fe2048ac5eb137c6bb0ab7287538677eChris Lattner 4155ee99979065d75605d150d7e567e4351024aae8fDevang Patel Changed = false; 41640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // First step. Check to see if there are any trivial GEP pointer recurrences. 41740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // If there are, change them into integer recurrences, permitting analysis by 41840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // the SCEV routines. 41915cad759fe2048ac5eb137c6bb0ab7287538677eChris Lattner // 42040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner BasicBlock *Header = L->getHeader(); 42140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner BasicBlock *Preheader = L->getLoopPreheader(); 4225ee99979065d75605d150d7e567e4351024aae8fDevang Patel SE = &LPM.getAnalysis<ScalarEvolution>(); 423fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukman 42440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner std::set<Instruction*> DeadInsts; 4252da5c3dda6f5b9c4ec6d55008d33327764364bd4Reid Spencer for (BasicBlock::iterator I = Header->begin(); isa<PHINode>(I); ++I) { 4262da5c3dda6f5b9c4ec6d55008d33327764364bd4Reid Spencer PHINode *PN = cast<PHINode>(I); 42740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner if (isa<PointerType>(PN->getType())) 42840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner EliminatePointerRecurrence(PN, Preheader, DeadInsts); 4292da5c3dda6f5b9c4ec6d55008d33327764364bd4Reid Spencer } 43015cad759fe2048ac5eb137c6bb0ab7287538677eChris Lattner 43140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner if (!DeadInsts.empty()) 43240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner DeleteTriviallyDeadInstructions(DeadInsts); 433394437ff7eaccfe1de92fe14d0022ca0addf3e41Chris Lattner 4345ee99979065d75605d150d7e567e4351024aae8fDevang Patel return Changed; 4355ee99979065d75605d150d7e567e4351024aae8fDevang Patel} 4365ee99979065d75605d150d7e567e4351024aae8fDevang Patel 4375ee99979065d75605d150d7e567e4351024aae8fDevang Patelbool IndVarSimplify::runOnLoop(Loop *L, LPPassManager &LPM) { 4385ee99979065d75605d150d7e567e4351024aae8fDevang Patel 439394437ff7eaccfe1de92fe14d0022ca0addf3e41Chris Lattner 4405ee99979065d75605d150d7e567e4351024aae8fDevang Patel LI = &getAnalysis<LoopInfo>(); 4415ee99979065d75605d150d7e567e4351024aae8fDevang Patel SE = &getAnalysis<ScalarEvolution>(); 442394437ff7eaccfe1de92fe14d0022ca0addf3e41Chris Lattner 4435ee99979065d75605d150d7e567e4351024aae8fDevang Patel Changed = false; 4445ee99979065d75605d150d7e567e4351024aae8fDevang Patel BasicBlock *Header = L->getHeader(); 4455ee99979065d75605d150d7e567e4351024aae8fDevang Patel std::set<Instruction*> DeadInsts; 4465ee99979065d75605d150d7e567e4351024aae8fDevang Patel 4479caed5440d59dac4b388152fe8b993dc0491e5e9Chris Lattner // Verify the input to the pass in already in LCSSA form. 4489caed5440d59dac4b388152fe8b993dc0491e5e9Chris Lattner assert(L->isLCSSAForm()); 4499caed5440d59dac4b388152fe8b993dc0491e5e9Chris Lattner 45040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // Check to see if this loop has a computable loop-invariant execution count. 45140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // If so, this means that we can compute the final value of any expressions 45240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // that are recurrent in the loop, and substitute the exit values from the 45340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // loop into any instructions outside of the loop that use the final values of 45440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // the current expressions. 455394437ff7eaccfe1de92fe14d0022ca0addf3e41Chris Lattner // 45640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner SCEVHandle IterationCount = SE->getIterationCount(L); 45740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner if (!isa<SCEVCouldNotCompute>(IterationCount)) 45840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner RewriteLoopExitValues(L); 45940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner 46040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // Next, analyze all of the induction variables in the loop, canonicalizing 46140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // auxillary induction variables. 46240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner std::vector<std::pair<PHINode*, SCEVHandle> > IndVars; 46340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner 4642da5c3dda6f5b9c4ec6d55008d33327764364bd4Reid Spencer for (BasicBlock::iterator I = Header->begin(); isa<PHINode>(I); ++I) { 4652da5c3dda6f5b9c4ec6d55008d33327764364bd4Reid Spencer PHINode *PN = cast<PHINode>(I); 46642a75517250017a52afb03a0ade03cbd49559fe5Chris Lattner if (PN->getType()->isInteger()) { // FIXME: when we have fast-math, enable! 46740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner SCEVHandle SCEV = SE->getSCEV(PN); 46840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner if (SCEV->hasComputableLoopEvolution(L)) 469cda9ca5a4fed09ea3788b572dbddabf2a5a7a5d9Chris Lattner // FIXME: It is an extremely bad idea to indvar substitute anything more 470cda9ca5a4fed09ea3788b572dbddabf2a5a7a5d9Chris Lattner // complex than affine induction variables. Doing so will put expensive 471cda9ca5a4fed09ea3788b572dbddabf2a5a7a5d9Chris Lattner // polynomial evaluations inside of the loop, and the str reduction pass 472cda9ca5a4fed09ea3788b572dbddabf2a5a7a5d9Chris Lattner // currently can only reduce affine polynomials. For now just disable 473cda9ca5a4fed09ea3788b572dbddabf2a5a7a5d9Chris Lattner // indvar subst on anything more complex than an affine addrec. 474595ee7ec26432e4804f1e71817d9cf9b1f86318dChris Lattner if (SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(SCEV)) 475cda9ca5a4fed09ea3788b572dbddabf2a5a7a5d9Chris Lattner if (AR->isAffine()) 476595ee7ec26432e4804f1e71817d9cf9b1f86318dChris Lattner IndVars.push_back(std::make_pair(PN, SCEV)); 47740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner } 4782da5c3dda6f5b9c4ec6d55008d33327764364bd4Reid Spencer } 479f016ea4ff80c56c467247a90567dd07bddb590f3Chris Lattner 48040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // If there are no induction variables in the loop, there is nothing more to 48140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // do. 482f50af088f19f525f3d1026eb61db77e0037a9f43Chris Lattner if (IndVars.empty()) { 483f50af088f19f525f3d1026eb61db77e0037a9f43Chris Lattner // Actually, if we know how many times the loop iterates, lets insert a 484f50af088f19f525f3d1026eb61db77e0037a9f43Chris Lattner // canonical induction variable to help subsequent passes. 485f50af088f19f525f3d1026eb61db77e0037a9f43Chris Lattner if (!isa<SCEVCouldNotCompute>(IterationCount)) { 4864a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner SCEVExpander Rewriter(*SE, *LI); 4874a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner Rewriter.getOrInsertCanonicalInductionVariable(L, 488f50af088f19f525f3d1026eb61db77e0037a9f43Chris Lattner IterationCount->getType()); 4899ba46c13bf3d49a5b697227c88ef987951e6b50dChris Lattner if (Instruction *I = LinearFunctionTestReplace(L, IterationCount, 4909ba46c13bf3d49a5b697227c88ef987951e6b50dChris Lattner Rewriter)) { 4919ba46c13bf3d49a5b697227c88ef987951e6b50dChris Lattner std::set<Instruction*> InstructionsToDelete; 4929ba46c13bf3d49a5b697227c88ef987951e6b50dChris Lattner InstructionsToDelete.insert(I); 4939ba46c13bf3d49a5b697227c88ef987951e6b50dChris Lattner DeleteTriviallyDeadInstructions(InstructionsToDelete); 4949ba46c13bf3d49a5b697227c88ef987951e6b50dChris Lattner } 495f50af088f19f525f3d1026eb61db77e0037a9f43Chris Lattner } 4965ee99979065d75605d150d7e567e4351024aae8fDevang Patel return Changed; 497f50af088f19f525f3d1026eb61db77e0037a9f43Chris Lattner } 498f016ea4ff80c56c467247a90567dd07bddb590f3Chris Lattner 49940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // Compute the type of the largest recurrence expression. 50040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // 50140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner const Type *LargestType = IndVars[0].first->getType(); 502fcb81f5f4cbac61851b7dec403961cf88e614aa1Chris Lattner bool DifferingSizes = false; 50340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner for (unsigned i = 1, e = IndVars.size(); i != e; ++i) { 50440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner const Type *Ty = IndVars[i].first->getType(); 505abaa8ca433a52dc522f6137c01a9552ebec44bb5Reid Spencer DifferingSizes |= 506abaa8ca433a52dc522f6137c01a9552ebec44bb5Reid Spencer Ty->getPrimitiveSizeInBits() != LargestType->getPrimitiveSizeInBits(); 507abaa8ca433a52dc522f6137c01a9552ebec44bb5Reid Spencer if (Ty->getPrimitiveSizeInBits() > LargestType->getPrimitiveSizeInBits()) 50840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner LargestType = Ty; 509500597a1c39e91a3020587318ed61e737b6c613aChris Lattner } 510394437ff7eaccfe1de92fe14d0022ca0addf3e41Chris Lattner 51140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // Create a rewriter object which we'll use to transform the code with. 5124a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner SCEVExpander Rewriter(*SE, *LI); 51340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner 51440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // Now that we know the largest of of the induction variables in this loop, 51540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // insert a canonical induction variable of the largest size. 5164a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner Value *IndVar = Rewriter.getOrInsertCanonicalInductionVariable(L,LargestType); 51740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner ++NumInserted; 51840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner Changed = true; 519ee4f13a9046c380725cdeab62d57722db375c473Chris Lattner DOUT << "INDVARS: New CanIV: " << *IndVar; 52040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner 521d19534add90a2a894af61523b830887097bb780bDan Gohman if (!isa<SCEVCouldNotCompute>(IterationCount)) { 5220d7d3656f3d10c510353d69472de4c0c0691b2e6Zhou Sheng if (IterationCount->getType()->getPrimitiveSizeInBits() < 5230d7d3656f3d10c510353d69472de4c0c0691b2e6Zhou Sheng LargestType->getPrimitiveSizeInBits()) 524d19534add90a2a894af61523b830887097bb780bDan Gohman IterationCount = SCEVZeroExtendExpr::get(IterationCount, LargestType); 5250d7d3656f3d10c510353d69472de4c0c0691b2e6Zhou Sheng else if (IterationCount->getType() != LargestType) 5260d7d3656f3d10c510353d69472de4c0c0691b2e6Zhou Sheng IterationCount = SCEVTruncateExpr::get(IterationCount, LargestType); 5279ba46c13bf3d49a5b697227c88ef987951e6b50dChris Lattner if (Instruction *DI = LinearFunctionTestReplace(L, IterationCount,Rewriter)) 5289ba46c13bf3d49a5b697227c88ef987951e6b50dChris Lattner DeadInsts.insert(DI); 529d19534add90a2a894af61523b830887097bb780bDan Gohman } 53040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner 53140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // Now that we have a canonical induction variable, we can rewrite any 53240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // recurrences in terms of the induction variable. Start with the auxillary 53340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // induction variables, and recursively rewrite any of their uses. 53440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner BasicBlock::iterator InsertPt = Header->begin(); 53540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner while (isa<PHINode>(InsertPt)) ++InsertPt; 53640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner 5375d461d20aea308471f2a31b718a274bfee28b60cChris Lattner // If there were induction variables of other sizes, cast the primary 5385d461d20aea308471f2a31b718a274bfee28b60cChris Lattner // induction variable to the right size for them, avoiding the need for the 5395d461d20aea308471f2a31b718a274bfee28b60cChris Lattner // code evaluation methods to insert induction variables of different sizes. 540fcb81f5f4cbac61851b7dec403961cf88e614aa1Chris Lattner if (DifferingSizes) { 541a54b7cbd452b3adb2f51346140d996b29c2cdb30Reid Spencer SmallVector<unsigned,4> InsertedSizes; 542a54b7cbd452b3adb2f51346140d996b29c2cdb30Reid Spencer InsertedSizes.push_back(LargestType->getPrimitiveSizeInBits()); 543a54b7cbd452b3adb2f51346140d996b29c2cdb30Reid Spencer for (unsigned i = 0, e = IndVars.size(); i != e; ++i) { 544a54b7cbd452b3adb2f51346140d996b29c2cdb30Reid Spencer unsigned ithSize = IndVars[i].first->getType()->getPrimitiveSizeInBits(); 545ef60b2c4ed67017a46442903c898bc24ed9a6c91Chris Lattner if (std::find(InsertedSizes.begin(), InsertedSizes.end(), ithSize) 546ef60b2c4ed67017a46442903c898bc24ed9a6c91Chris Lattner == InsertedSizes.end()) { 547fcb81f5f4cbac61851b7dec403961cf88e614aa1Chris Lattner PHINode *PN = IndVars[i].first; 548a54b7cbd452b3adb2f51346140d996b29c2cdb30Reid Spencer InsertedSizes.push_back(ithSize); 549ee4f13a9046c380725cdeab62d57722db375c473Chris Lattner Instruction *New = new TruncInst(IndVar, PN->getType(), "indvar", 550ee4f13a9046c380725cdeab62d57722db375c473Chris Lattner InsertPt); 551fcb81f5f4cbac61851b7dec403961cf88e614aa1Chris Lattner Rewriter.addInsertedValue(New, SE->getSCEV(New)); 552ee4f13a9046c380725cdeab62d57722db375c473Chris Lattner DOUT << "INDVARS: Made trunc IV for " << *PN 553ee4f13a9046c380725cdeab62d57722db375c473Chris Lattner << " NewVal = " << *New << "\n"; 554fcb81f5f4cbac61851b7dec403961cf88e614aa1Chris Lattner } 555a54b7cbd452b3adb2f51346140d996b29c2cdb30Reid Spencer } 556fcb81f5f4cbac61851b7dec403961cf88e614aa1Chris Lattner } 557fcb81f5f4cbac61851b7dec403961cf88e614aa1Chris Lattner 558ee4f13a9046c380725cdeab62d57722db375c473Chris Lattner // Rewrite all induction variables in terms of the canonical induction 559ee4f13a9046c380725cdeab62d57722db375c473Chris Lattner // variable. 5605d461d20aea308471f2a31b718a274bfee28b60cChris Lattner std::map<unsigned, Value*> InsertedSizes; 56140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner while (!IndVars.empty()) { 56240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner PHINode *PN = IndVars.back().first; 563d19534add90a2a894af61523b830887097bb780bDan Gohman Value *NewVal = Rewriter.expandCodeFor(IndVars.back().second, InsertPt); 564ee4f13a9046c380725cdeab62d57722db375c473Chris Lattner DOUT << "INDVARS: Rewrote IV '" << *IndVars.back().second << "' " << *PN 565ee4f13a9046c380725cdeab62d57722db375c473Chris Lattner << " into = " << *NewVal << "\n"; 5666934a04a8c15e9971cd1ea4d5c8df2d7afdd5be5Chris Lattner NewVal->takeName(PN); 5675d461d20aea308471f2a31b718a274bfee28b60cChris Lattner 56840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // Replace the old PHI Node with the inserted computation. 569fcb81f5f4cbac61851b7dec403961cf88e614aa1Chris Lattner PN->replaceAllUsesWith(NewVal); 57040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner DeadInsts.insert(PN); 57140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner IndVars.pop_back(); 57240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner ++NumRemoved; 57340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner Changed = true; 574500597a1c39e91a3020587318ed61e737b6c613aChris Lattner } 575ba4f3f6a419326df190599421fa149c90235cb72Chris Lattner 576b4782d13d1444d9d18c0a681292cf0d0a32cf3efChris Lattner#if 0 5771363e85df74627530ceede53280613c62a4cdbe3Chris Lattner // Now replace all derived expressions in the loop body with simpler 5781363e85df74627530ceede53280613c62a4cdbe3Chris Lattner // expressions. 57940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner for (unsigned i = 0, e = L->getBlocks().size(); i != e; ++i) 58040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner if (LI->getLoopFor(L->getBlocks()[i]) == L) { // Not in a subloop... 58140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner BasicBlock *BB = L->getBlocks()[i]; 58240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) 58342a75517250017a52afb03a0ade03cbd49559fe5Chris Lattner if (I->getType()->isInteger() && // Is an integer instruction 5841363e85df74627530ceede53280613c62a4cdbe3Chris Lattner !I->use_empty() && 58540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner !Rewriter.isInsertedInstruction(I)) { 58640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner SCEVHandle SH = SE->getSCEV(I); 5874a7553e2da506a718f59869c03c5ce113eb40f7aChris Lattner Value *V = Rewriter.expandCodeFor(SH, I, I->getType()); 5881363e85df74627530ceede53280613c62a4cdbe3Chris Lattner if (V != I) { 5896934a04a8c15e9971cd1ea4d5c8df2d7afdd5be5Chris Lattner if (isa<Instruction>(V)) 5906934a04a8c15e9971cd1ea4d5c8df2d7afdd5be5Chris Lattner V->takeName(I); 5911363e85df74627530ceede53280613c62a4cdbe3Chris Lattner I->replaceAllUsesWith(V); 5921363e85df74627530ceede53280613c62a4cdbe3Chris Lattner DeadInsts.insert(I); 5931363e85df74627530ceede53280613c62a4cdbe3Chris Lattner ++NumRemoved; 5941363e85df74627530ceede53280613c62a4cdbe3Chris Lattner Changed = true; 595fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukman } 59640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner } 597394437ff7eaccfe1de92fe14d0022ca0addf3e41Chris Lattner } 598b4782d13d1444d9d18c0a681292cf0d0a32cf3efChris Lattner#endif 5991363e85df74627530ceede53280613c62a4cdbe3Chris Lattner 6001363e85df74627530ceede53280613c62a4cdbe3Chris Lattner DeleteTriviallyDeadInstructions(DeadInsts); 601eb705914924865201f8b8018977d94594b258142Owen Anderson 6029caed5440d59dac4b388152fe8b993dc0491e5e9Chris Lattner assert(L->isLCSSAForm()); 6035ee99979065d75605d150d7e567e4351024aae8fDevang Patel return Changed; 6046148c02591bd83da7b957589c4bbf6f9720d503fChris Lattner} 605