IndVarSimplify.cpp revision 5d461d20aea308471f2a31b718a274bfee28b60c
16148c02591bd83da7b957589c4bbf6f9720d503fChris Lattner//===- IndVarSimplify.cpp - Induction Variable Elimination ----------------===// 2b576c94c15af9a440f69d9d03c2afead7971118cJohn Criswell// 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. 7b576c94c15af9a440f69d9d03c2afead7971118cJohn Criswell// 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// 1440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// This transformation make 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 40022103b3f33febb7e54b8fdf2c9bc461eea78cbaChris Lattner#include "llvm/Transforms/Scalar.h" 4140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner#include "llvm/BasicBlock.h" 4259fdaeeae8f183e18bb6ad5c382ca23e28e6aaf6Chris Lattner#include "llvm/Constants.h" 4318b3c97bc773b24a66eb779e85da1820b0f16b31Chris Lattner#include "llvm/Instructions.h" 4440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner#include "llvm/Type.h" 4559fdaeeae8f183e18bb6ad5c382ca23e28e6aaf6Chris Lattner#include "llvm/Analysis/ScalarEvolutionExpressions.h" 4647df12d80db90e125e9f2ff764286ee11665476dJohn Criswell#include "llvm/Analysis/LoopInfo.h" 47455889aa79e3463a4b0f2161e3d9d72a683268b6Chris Lattner#include "llvm/Support/CFG.h" 4847df12d80db90e125e9f2ff764286ee11665476dJohn Criswell#include "llvm/Transforms/Utils/Local.h" 4940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner#include "Support/CommandLine.h" 50a92f696b74a99325026ebbdbffd2a44317e0c10bChris Lattner#include "Support/Statistic.h" 5147df12d80db90e125e9f2ff764286ee11665476dJohn Criswellusing namespace llvm; 52d0fde30ce850b78371fd1386338350591f9ff494Brian Gaeke 535e76140536ba66fadeced1cd892f79616f407e3cChris Lattnernamespace { 54a92f696b74a99325026ebbdbffd2a44317e0c10bChris Lattner Statistic<> NumRemoved ("indvars", "Number of aux indvars removed"); 5540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner Statistic<> NumPointer ("indvars", "Number of pointer indvars promoted"); 563adf51d022348b06a1adeef7649fa35928ad9358Chris Lattner Statistic<> NumInserted("indvars", "Number of canonical indvars added"); 5740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner Statistic<> NumReplaced("indvars", "Number of exit values replaced"); 5840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner Statistic<> NumLFTR ("indvars", "Number of loop exit tests replaced"); 593324e718bc9ac2ede08a14c325848b576849542bChris Lattner 603324e718bc9ac2ede08a14c325848b576849542bChris Lattner class IndVarSimplify : public FunctionPass { 6140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner LoopInfo *LI; 6240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner ScalarEvolution *SE; 6315cad759fe2048ac5eb137c6bb0ab7287538677eChris Lattner bool Changed; 643324e718bc9ac2ede08a14c325848b576849542bChris Lattner public: 653324e718bc9ac2ede08a14c325848b576849542bChris Lattner virtual bool runOnFunction(Function &) { 6640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner LI = &getAnalysis<LoopInfo>(); 6740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner SE = &getAnalysis<ScalarEvolution>(); 6815cad759fe2048ac5eb137c6bb0ab7287538677eChris Lattner Changed = false; 6915cad759fe2048ac5eb137c6bb0ab7287538677eChris Lattner 703324e718bc9ac2ede08a14c325848b576849542bChris Lattner // Induction Variables live in the header nodes of loops 7140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner for (LoopInfo::iterator I = LI->begin(), E = LI->end(); I != E; ++I) 72329c1c6c949d07e3fe9722ec633b4258217fd99dChris Lattner runOnLoop(*I); 733324e718bc9ac2ede08a14c325848b576849542bChris Lattner return Changed; 743324e718bc9ac2ede08a14c325848b576849542bChris Lattner } 753324e718bc9ac2ede08a14c325848b576849542bChris Lattner 763324e718bc9ac2ede08a14c325848b576849542bChris Lattner virtual void getAnalysisUsage(AnalysisUsage &AU) const { 773324e718bc9ac2ede08a14c325848b576849542bChris Lattner AU.addRequiredID(LoopSimplifyID); 7840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner AU.addRequired<ScalarEvolution>(); 7940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner AU.addRequired<LoopInfo>(); 803324e718bc9ac2ede08a14c325848b576849542bChris Lattner AU.addPreservedID(LoopSimplifyID); 813324e718bc9ac2ede08a14c325848b576849542bChris Lattner AU.setPreservesCFG(); 823324e718bc9ac2ede08a14c325848b576849542bChris Lattner } 8340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner private: 8440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner void runOnLoop(Loop *L); 8540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner void EliminatePointerRecurrence(PHINode *PN, BasicBlock *Preheader, 8640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner std::set<Instruction*> &DeadInsts); 8740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner void LinearFunctionTestReplace(Loop *L, SCEV *IterationCount, 8859fdaeeae8f183e18bb6ad5c382ca23e28e6aaf6Chris Lattner ScalarEvolutionRewriter &RW); 8940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner void RewriteLoopExitValues(Loop *L); 9040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner 9140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner void DeleteTriviallyDeadInstructions(std::set<Instruction*> &Insts); 923324e718bc9ac2ede08a14c325848b576849542bChris Lattner }; 933324e718bc9ac2ede08a14c325848b576849542bChris Lattner RegisterOpt<IndVarSimplify> X("indvars", "Canonicalize Induction Variables"); 945e76140536ba66fadeced1cd892f79616f407e3cChris Lattner} 95394437ff7eaccfe1de92fe14d0022ca0addf3e41Chris Lattner 963324e718bc9ac2ede08a14c325848b576849542bChris LattnerPass *llvm::createIndVarSimplifyPass() { 973324e718bc9ac2ede08a14c325848b576849542bChris Lattner return new IndVarSimplify(); 98394437ff7eaccfe1de92fe14d0022ca0addf3e41Chris Lattner} 99394437ff7eaccfe1de92fe14d0022ca0addf3e41Chris Lattner 1003324e718bc9ac2ede08a14c325848b576849542bChris Lattner 10140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner/// DeleteTriviallyDeadInstructions - If any of the instructions is the 10240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner/// specified set are trivially dead, delete them and see if this makes any of 10340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner/// their operands subsequently dead. 10440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattnervoid IndVarSimplify:: 10540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris LattnerDeleteTriviallyDeadInstructions(std::set<Instruction*> &Insts) { 10640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner while (!Insts.empty()) { 10740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner Instruction *I = *Insts.begin(); 10840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner Insts.erase(Insts.begin()); 10940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner if (isInstructionTriviallyDead(I)) { 11040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) 11140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner if (Instruction *U = dyn_cast<Instruction>(I->getOperand(i))) 11240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner Insts.insert(U); 11340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner SE->deleteInstructionFromRecords(I); 11440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner I->getParent()->getInstList().erase(I); 11540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner Changed = true; 11640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner } 11740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner } 11840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner} 1193324e718bc9ac2ede08a14c325848b576849542bChris Lattner 1206148c02591bd83da7b957589c4bbf6f9720d503fChris Lattner 12140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner/// EliminatePointerRecurrence - Check to see if this is a trivial GEP pointer 12240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner/// recurrence. If so, change it into an integer recurrence, permitting 12340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner/// analysis by the SCEV routines. 12440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattnervoid IndVarSimplify::EliminatePointerRecurrence(PHINode *PN, 12540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner BasicBlock *Preheader, 12640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner std::set<Instruction*> &DeadInsts) { 12740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner assert(PN->getNumIncomingValues() == 2 && "Noncanonicalized loop!"); 12840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner unsigned PreheaderIdx = PN->getBasicBlockIndex(Preheader); 12940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner unsigned BackedgeIdx = PreheaderIdx^1; 13040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner if (GetElementPtrInst *GEPI = 13140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner dyn_cast<GetElementPtrInst>(PN->getIncomingValue(BackedgeIdx))) 13240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner if (GEPI->getOperand(0) == PN) { 13340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner assert(GEPI->getNumOperands() == 2 && "GEP types must mismatch!"); 13440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner 13540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // Okay, we found a pointer recurrence. Transform this pointer 13640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // recurrence into an integer recurrence. Compute the value that gets 13740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // added to the pointer at every iteration. 13840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner Value *AddedVal = GEPI->getOperand(1); 13940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner 14040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // Insert a new integer PHI node into the top of the block. 14140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner PHINode *NewPhi = new PHINode(AddedVal->getType(), 14240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner PN->getName()+".rec", PN); 14340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner NewPhi->addIncoming(Constant::getNullValue(NewPhi->getType()), 14440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner Preheader); 14540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // Create the new add instruction. 14640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner Value *NewAdd = BinaryOperator::create(Instruction::Add, NewPhi, 14740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner AddedVal, 14840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner GEPI->getName()+".rec", GEPI); 14940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner NewPhi->addIncoming(NewAdd, PN->getIncomingBlock(BackedgeIdx)); 15040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner 15140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // Update the existing GEP to use the recurrence. 15240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner GEPI->setOperand(0, PN->getIncomingValue(PreheaderIdx)); 15340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner 15440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // Update the GEP to use the new recurrence we just inserted. 15540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner GEPI->setOperand(1, NewAdd); 15640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner 15740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // Finally, if there are any other users of the PHI node, we must 15840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // insert a new GEP instruction that uses the pre-incremented version 15940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // of the induction amount. 16040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner if (!PN->use_empty()) { 16140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner BasicBlock::iterator InsertPos = PN; ++InsertPos; 16240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner while (isa<PHINode>(InsertPos)) ++InsertPos; 16340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner std::string Name = PN->getName(); PN->setName(""); 16440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner Value *PreInc = 16540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner new GetElementPtrInst(PN->getIncomingValue(PreheaderIdx), 16640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner std::vector<Value*>(1, NewPhi), Name, 16740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner InsertPos); 16840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner PN->replaceAllUsesWith(PreInc); 16940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner } 17040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner 17140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // Delete the old PHI for sure, and the GEP if its otherwise unused. 17240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner DeadInsts.insert(PN); 1733324e718bc9ac2ede08a14c325848b576849542bChris Lattner 17440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner ++NumPointer; 17540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner Changed = true; 17640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner } 17740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner} 1783324e718bc9ac2ede08a14c325848b576849542bChris Lattner 17940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner/// LinearFunctionTestReplace - This method rewrites the exit condition of the 18059fdaeeae8f183e18bb6ad5c382ca23e28e6aaf6Chris Lattner/// loop to be a canonical != comparison against the incremented loop induction 18159fdaeeae8f183e18bb6ad5c382ca23e28e6aaf6Chris Lattner/// variable. This pass is able to rewrite the exit tests of any loop where the 18259fdaeeae8f183e18bb6ad5c382ca23e28e6aaf6Chris Lattner/// SCEV analysis can determine a loop-invariant trip count of the loop, which 18359fdaeeae8f183e18bb6ad5c382ca23e28e6aaf6Chris Lattner/// is actually a much broader range than just linear tests. 18440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattnervoid IndVarSimplify::LinearFunctionTestReplace(Loop *L, SCEV *IterationCount, 18540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner ScalarEvolutionRewriter &RW) { 18640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // Find the exit block for the loop. We can currently only handle loops with 18740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // a single exit. 188f1ab4b4eac5603d19c20f4a508f93a118a52bdd5Chris Lattner std::vector<BasicBlock*> ExitBlocks; 189f1ab4b4eac5603d19c20f4a508f93a118a52bdd5Chris Lattner L->getExitBlocks(ExitBlocks); 190f1ab4b4eac5603d19c20f4a508f93a118a52bdd5Chris Lattner if (ExitBlocks.size() != 1) return; 191f1ab4b4eac5603d19c20f4a508f93a118a52bdd5Chris Lattner BasicBlock *ExitBlock = ExitBlocks[0]; 19240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner 19340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // Make sure there is only one predecessor block in the loop. 19440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner BasicBlock *ExitingBlock = 0; 19540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner for (pred_iterator PI = pred_begin(ExitBlock), PE = pred_end(ExitBlock); 19640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner PI != PE; ++PI) 19740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner if (L->contains(*PI)) { 19840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner if (ExitingBlock == 0) 19940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner ExitingBlock = *PI; 20040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner else 20140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner return; // Multiple exits from loop to this block. 20240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner } 20340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner assert(ExitingBlock && "Loop info is broken"); 20440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner 20540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner if (!isa<BranchInst>(ExitingBlock->getTerminator())) 20640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner return; // Can't rewrite non-branch yet 20740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner BranchInst *BI = cast<BranchInst>(ExitingBlock->getTerminator()); 20840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner assert(BI->isConditional() && "Must be conditional to be part of loop!"); 20940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner 21040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner std::set<Instruction*> InstructionsToDelete; 21140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner if (Instruction *Cond = dyn_cast<Instruction>(BI->getCondition())) 21240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner InstructionsToDelete.insert(Cond); 21340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner 214d244057a48660c3cd30d219118ece3f947947790Chris Lattner // If the exiting block is not the same as the backedge block, we must compare 215d244057a48660c3cd30d219118ece3f947947790Chris Lattner // against the preincremented value, otherwise we prefer to compare against 216d244057a48660c3cd30d219118ece3f947947790Chris Lattner // the post-incremented value. 217d244057a48660c3cd30d219118ece3f947947790Chris Lattner BasicBlock *Header = L->getHeader(); 218d244057a48660c3cd30d219118ece3f947947790Chris Lattner pred_iterator HPI = pred_begin(Header); 219d244057a48660c3cd30d219118ece3f947947790Chris Lattner assert(HPI != pred_end(Header) && "Loop with zero preds???"); 220d244057a48660c3cd30d219118ece3f947947790Chris Lattner if (!L->contains(*HPI)) ++HPI; 221d244057a48660c3cd30d219118ece3f947947790Chris Lattner assert(HPI != pred_end(Header) && L->contains(*HPI) && 222d244057a48660c3cd30d219118ece3f947947790Chris Lattner "No backedge in loop?"); 223d244057a48660c3cd30d219118ece3f947947790Chris Lattner 224d244057a48660c3cd30d219118ece3f947947790Chris Lattner SCEVHandle TripCount = IterationCount; 225d244057a48660c3cd30d219118ece3f947947790Chris Lattner Value *IndVar; 226d244057a48660c3cd30d219118ece3f947947790Chris Lattner if (*HPI == ExitingBlock) { 227d244057a48660c3cd30d219118ece3f947947790Chris Lattner // The IterationCount expression contains the number of times that the 228d244057a48660c3cd30d219118ece3f947947790Chris Lattner // backedge actually branches to the loop header. This is one less than the 229d244057a48660c3cd30d219118ece3f947947790Chris Lattner // number of times the loop executes, so add one to it. 230d244057a48660c3cd30d219118ece3f947947790Chris Lattner Constant *OneC = ConstantInt::get(IterationCount->getType(), 1); 231d244057a48660c3cd30d219118ece3f947947790Chris Lattner TripCount = SCEVAddExpr::get(IterationCount, SCEVUnknown::get(OneC)); 232d244057a48660c3cd30d219118ece3f947947790Chris Lattner IndVar = L->getCanonicalInductionVariableIncrement(); 233d244057a48660c3cd30d219118ece3f947947790Chris Lattner } else { 234d244057a48660c3cd30d219118ece3f947947790Chris Lattner // We have to use the preincremented value... 235d244057a48660c3cd30d219118ece3f947947790Chris Lattner IndVar = L->getCanonicalInductionVariable(); 236d244057a48660c3cd30d219118ece3f947947790Chris Lattner } 23759fdaeeae8f183e18bb6ad5c382ca23e28e6aaf6Chris Lattner 23840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // Expand the code for the iteration count into the preheader of the loop. 23940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner BasicBlock *Preheader = L->getLoopPreheader(); 24059fdaeeae8f183e18bb6ad5c382ca23e28e6aaf6Chris Lattner Value *ExitCnt = RW.ExpandCodeFor(TripCount, Preheader->getTerminator(), 24140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner IndVar->getType()); 24240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner 24340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // Insert a new setne or seteq instruction before the branch. 24440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner Instruction::BinaryOps Opcode; 24540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner if (L->contains(BI->getSuccessor(0))) 24640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner Opcode = Instruction::SetNE; 24740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner else 24840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner Opcode = Instruction::SetEQ; 24940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner 25040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner Value *Cond = new SetCondInst(Opcode, IndVar, ExitCnt, "exitcond", BI); 25140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner BI->setCondition(Cond); 25240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner ++NumLFTR; 25340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner Changed = true; 25440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner 25540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner DeleteTriviallyDeadInstructions(InstructionsToDelete); 25640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner} 2573324e718bc9ac2ede08a14c325848b576849542bChris Lattner 2583324e718bc9ac2ede08a14c325848b576849542bChris Lattner 25940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner/// RewriteLoopExitValues - Check to see if this loop has a computable 26040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner/// loop-invariant execution count. If so, this means that we can compute the 26140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner/// final value of any expressions that are recurrent in the loop, and 26240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner/// substitute the exit values from the loop into any instructions outside of 26340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner/// the loop that use the final values of the current expressions. 26440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattnervoid IndVarSimplify::RewriteLoopExitValues(Loop *L) { 26540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner BasicBlock *Preheader = L->getLoopPreheader(); 26640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner 26740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // Scan all of the instructions in the loop, looking at those that have 26840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // extra-loop users and which are recurrences. 26940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner ScalarEvolutionRewriter Rewriter(*SE, *LI); 27040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner 27140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // We insert the code into the preheader of the loop if the loop contains 27240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // multiple exit blocks, or in the exit block if there is exactly one. 27340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner BasicBlock *BlockToInsertInto; 274f1ab4b4eac5603d19c20f4a508f93a118a52bdd5Chris Lattner std::vector<BasicBlock*> ExitBlocks; 275f1ab4b4eac5603d19c20f4a508f93a118a52bdd5Chris Lattner L->getExitBlocks(ExitBlocks); 276f1ab4b4eac5603d19c20f4a508f93a118a52bdd5Chris Lattner if (ExitBlocks.size() == 1) 277f1ab4b4eac5603d19c20f4a508f93a118a52bdd5Chris Lattner BlockToInsertInto = ExitBlocks[0]; 27840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner else 27940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner BlockToInsertInto = Preheader; 28040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner BasicBlock::iterator InsertPt = BlockToInsertInto->begin(); 28140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner while (isa<PHINode>(InsertPt)) ++InsertPt; 28240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner 28320aa098ba694aa7e3f5fb5a52d22dba7c1e857aeChris Lattner bool HasConstantItCount = isa<SCEVConstant>(SE->getIterationCount(L)); 28420aa098ba694aa7e3f5fb5a52d22dba7c1e857aeChris Lattner 28540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner std::set<Instruction*> InstructionsToDelete; 28640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner 28740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner for (unsigned i = 0, e = L->getBlocks().size(); i != e; ++i) 28840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner if (LI->getLoopFor(L->getBlocks()[i]) == L) { // Not in a subloop... 28940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner BasicBlock *BB = L->getBlocks()[i]; 29040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) 29140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner if (I->getType()->isInteger()) { // Is an integer instruction 29240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner SCEVHandle SH = SE->getSCEV(I); 29320aa098ba694aa7e3f5fb5a52d22dba7c1e857aeChris Lattner if (SH->hasComputableLoopEvolution(L) || // Varies predictably 29420aa098ba694aa7e3f5fb5a52d22dba7c1e857aeChris Lattner HasConstantItCount) { 29540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // Find out if this predictably varying value is actually used 29640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // outside of the loop. "extra" as opposed to "intra". 29740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner std::vector<User*> ExtraLoopUsers; 29840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner for (Value::use_iterator UI = I->use_begin(), E = I->use_end(); 29940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner UI != E; ++UI) 30040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner if (!L->contains(cast<Instruction>(*UI)->getParent())) 30140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner ExtraLoopUsers.push_back(*UI); 30240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner if (!ExtraLoopUsers.empty()) { 30340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // Okay, this instruction has a user outside of the current loop 30440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // and varies predictably in this loop. Evaluate the value it 30540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // contains when the loop exits, and insert code for it. 30620aa098ba694aa7e3f5fb5a52d22dba7c1e857aeChris Lattner SCEVHandle ExitValue = SE->getSCEVAtScope(I, L->getParentLoop()); 30740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner if (!isa<SCEVCouldNotCompute>(ExitValue)) { 30840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner Changed = true; 30940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner ++NumReplaced; 31040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner Value *NewVal = Rewriter.ExpandCodeFor(ExitValue, InsertPt, 31140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner I->getType()); 31240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner 31340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // Rewrite any users of the computed value outside of the loop 31440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // with the newly computed value. 31540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner for (unsigned i = 0, e = ExtraLoopUsers.size(); i != e; ++i) 31640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner ExtraLoopUsers[i]->replaceUsesOfWith(I, NewVal); 31740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner 31840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // If this instruction is dead now, schedule it to be removed. 31940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner if (I->use_empty()) 32040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner InstructionsToDelete.insert(I); 32140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner } 32240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner } 32340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner } 32440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner } 3253324e718bc9ac2ede08a14c325848b576849542bChris Lattner } 3266148c02591bd83da7b957589c4bbf6f9720d503fChris Lattner 32740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner DeleteTriviallyDeadInstructions(InstructionsToDelete); 32840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner} 32915cad759fe2048ac5eb137c6bb0ab7287538677eChris Lattner 33015cad759fe2048ac5eb137c6bb0ab7287538677eChris Lattner 33140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattnervoid IndVarSimplify::runOnLoop(Loop *L) { 33240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // First step. Check to see if there are any trivial GEP pointer recurrences. 33340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // If there are, change them into integer recurrences, permitting analysis by 33440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // the SCEV routines. 33515cad759fe2048ac5eb137c6bb0ab7287538677eChris Lattner // 33640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner BasicBlock *Header = L->getHeader(); 33740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner BasicBlock *Preheader = L->getLoopPreheader(); 33840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner 33940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner std::set<Instruction*> DeadInsts; 34040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner for (BasicBlock::iterator I = Header->begin(); 34140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner PHINode *PN = dyn_cast<PHINode>(I); ++I) 34240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner if (isa<PointerType>(PN->getType())) 34340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner EliminatePointerRecurrence(PN, Preheader, DeadInsts); 34415cad759fe2048ac5eb137c6bb0ab7287538677eChris Lattner 34540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner if (!DeadInsts.empty()) 34640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner DeleteTriviallyDeadInstructions(DeadInsts); 347394437ff7eaccfe1de92fe14d0022ca0addf3e41Chris Lattner 348394437ff7eaccfe1de92fe14d0022ca0addf3e41Chris Lattner 34940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // Next, transform all loops nesting inside of this loop. 35040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner for (LoopInfo::iterator I = L->begin(), E = L->end(); I != E; ++I) 35140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner runOnLoop(*I); 352394437ff7eaccfe1de92fe14d0022ca0addf3e41Chris Lattner 35340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // Check to see if this loop has a computable loop-invariant execution count. 35440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // If so, this means that we can compute the final value of any expressions 35540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // that are recurrent in the loop, and substitute the exit values from the 35640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // loop into any instructions outside of the loop that use the final values of 35740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // the current expressions. 358394437ff7eaccfe1de92fe14d0022ca0addf3e41Chris Lattner // 35940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner SCEVHandle IterationCount = SE->getIterationCount(L); 36040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner if (!isa<SCEVCouldNotCompute>(IterationCount)) 36140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner RewriteLoopExitValues(L); 36240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner 36340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // Next, analyze all of the induction variables in the loop, canonicalizing 36440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // auxillary induction variables. 36540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner std::vector<std::pair<PHINode*, SCEVHandle> > IndVars; 36640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner 36740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner for (BasicBlock::iterator I = Header->begin(); 36840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner PHINode *PN = dyn_cast<PHINode>(I); ++I) 36940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner if (PN->getType()->isInteger()) { // FIXME: when we have fast-math, enable! 37040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner SCEVHandle SCEV = SE->getSCEV(PN); 37140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner if (SCEV->hasComputableLoopEvolution(L)) 37240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner if (SE->shouldSubstituteIndVar(SCEV)) // HACK! 37340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner IndVars.push_back(std::make_pair(PN, SCEV)); 37440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner } 375f016ea4ff80c56c467247a90567dd07bddb590f3Chris Lattner 37640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // If there are no induction variables in the loop, there is nothing more to 37740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // do. 378f50af088f19f525f3d1026eb61db77e0037a9f43Chris Lattner if (IndVars.empty()) { 379f50af088f19f525f3d1026eb61db77e0037a9f43Chris Lattner // Actually, if we know how many times the loop iterates, lets insert a 380f50af088f19f525f3d1026eb61db77e0037a9f43Chris Lattner // canonical induction variable to help subsequent passes. 381f50af088f19f525f3d1026eb61db77e0037a9f43Chris Lattner if (!isa<SCEVCouldNotCompute>(IterationCount)) { 382f50af088f19f525f3d1026eb61db77e0037a9f43Chris Lattner ScalarEvolutionRewriter Rewriter(*SE, *LI); 383f50af088f19f525f3d1026eb61db77e0037a9f43Chris Lattner Rewriter.GetOrInsertCanonicalInductionVariable(L, 384f50af088f19f525f3d1026eb61db77e0037a9f43Chris Lattner IterationCount->getType()); 385f50af088f19f525f3d1026eb61db77e0037a9f43Chris Lattner LinearFunctionTestReplace(L, IterationCount, Rewriter); 386f50af088f19f525f3d1026eb61db77e0037a9f43Chris Lattner } 387f50af088f19f525f3d1026eb61db77e0037a9f43Chris Lattner return; 388f50af088f19f525f3d1026eb61db77e0037a9f43Chris Lattner } 389f016ea4ff80c56c467247a90567dd07bddb590f3Chris Lattner 39040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // Compute the type of the largest recurrence expression. 39140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // 39240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner const Type *LargestType = IndVars[0].first->getType(); 39340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner for (unsigned i = 1, e = IndVars.size(); i != e; ++i) { 39440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner const Type *Ty = IndVars[i].first->getType(); 39540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner if (Ty->getPrimitiveSize() > LargestType->getPrimitiveSize()) 39640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner LargestType = Ty; 397500597a1c39e91a3020587318ed61e737b6c613aChris Lattner } 398394437ff7eaccfe1de92fe14d0022ca0addf3e41Chris Lattner 39940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // Create a rewriter object which we'll use to transform the code with. 40040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner ScalarEvolutionRewriter Rewriter(*SE, *LI); 40140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner 40240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // Now that we know the largest of of the induction variables in this loop, 40340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // insert a canonical induction variable of the largest size. 404006118fe8c73d8009d7952b84cabd50882ed0033Chris Lattner LargestType = LargestType->getUnsignedVersion(); 40540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner Value *IndVar = Rewriter.GetOrInsertCanonicalInductionVariable(L,LargestType); 40640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner ++NumInserted; 40740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner Changed = true; 40840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner 40940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner if (!isa<SCEVCouldNotCompute>(IterationCount)) 41059fdaeeae8f183e18bb6ad5c382ca23e28e6aaf6Chris Lattner LinearFunctionTestReplace(L, IterationCount, Rewriter); 41140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner 41240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // Now that we have a canonical induction variable, we can rewrite any 41340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // recurrences in terms of the induction variable. Start with the auxillary 41440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // induction variables, and recursively rewrite any of their uses. 41540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner BasicBlock::iterator InsertPt = Header->begin(); 41640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner while (isa<PHINode>(InsertPt)) ++InsertPt; 41740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner 4185d461d20aea308471f2a31b718a274bfee28b60cChris Lattner // If there were induction variables of other sizes, cast the primary 4195d461d20aea308471f2a31b718a274bfee28b60cChris Lattner // induction variable to the right size for them, avoiding the need for the 4205d461d20aea308471f2a31b718a274bfee28b60cChris Lattner // code evaluation methods to insert induction variables of different sizes. 4215d461d20aea308471f2a31b718a274bfee28b60cChris Lattner std::map<unsigned, Value*> InsertedSizes; 4225d461d20aea308471f2a31b718a274bfee28b60cChris Lattner InsertedSizes[LargestType->getPrimitiveSize()] = IndVar; 42340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner while (!IndVars.empty()) { 42440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner PHINode *PN = IndVars.back().first; 4255d461d20aea308471f2a31b718a274bfee28b60cChris Lattner 4265d461d20aea308471f2a31b718a274bfee28b60cChris Lattner const Type *Ty = PN->getType()->getUnsignedVersion(); 4275d461d20aea308471f2a31b718a274bfee28b60cChris Lattner Value *&IV = InsertedSizes[Ty->getPrimitiveSize()]; 4285d461d20aea308471f2a31b718a274bfee28b60cChris Lattner if (IV == 0) { 4295d461d20aea308471f2a31b718a274bfee28b60cChris Lattner // Insert a new cast instruction, which will hold this recurrence. 4305d461d20aea308471f2a31b718a274bfee28b60cChris Lattner std::string Name = PN->getName(); 4315d461d20aea308471f2a31b718a274bfee28b60cChris Lattner PN->setName(""); 4325d461d20aea308471f2a31b718a274bfee28b60cChris Lattner IV = new CastInst(IndVar, Ty, Name, InsertPt); 4335d461d20aea308471f2a31b718a274bfee28b60cChris Lattner } 4345d461d20aea308471f2a31b718a274bfee28b60cChris Lattner 4355d461d20aea308471f2a31b718a274bfee28b60cChris Lattner Value *V = IV; 4365d461d20aea308471f2a31b718a274bfee28b60cChris Lattner if (PN->getType() != Ty) 4375d461d20aea308471f2a31b718a274bfee28b60cChris Lattner V = new CastInst(V, PN->getType(), V->getName(), InsertPt); 4385d461d20aea308471f2a31b718a274bfee28b60cChris Lattner 43940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // Replace the old PHI Node with the inserted computation. 4405d461d20aea308471f2a31b718a274bfee28b60cChris Lattner PN->replaceAllUsesWith(V); 44140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner DeadInsts.insert(PN); 44240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner IndVars.pop_back(); 44340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner ++NumRemoved; 44440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner Changed = true; 445500597a1c39e91a3020587318ed61e737b6c613aChris Lattner } 446ba4f3f6a419326df190599421fa149c90235cb72Chris Lattner 44740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner DeleteTriviallyDeadInstructions(DeadInsts); 44840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner 44940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // TODO: In the future we could replace all instructions in the loop body with 45040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // simpler expressions. It's not clear how useful this would be though or if 45140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // the code expansion cost would be worth it! We probably shouldn't do this 45240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner // until we have a way to reuse expressions already in the code. 45340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner#if 0 45440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner for (unsigned i = 0, e = L->getBlocks().size(); i != e; ++i) 45540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner if (LI->getLoopFor(L->getBlocks()[i]) == L) { // Not in a subloop... 45640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner BasicBlock *BB = L->getBlocks()[i]; 45740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) 45840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner if (I->getType()->isInteger() && // Is an integer instruction 45940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner !Rewriter.isInsertedInstruction(I)) { 46040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner SCEVHandle SH = SE->getSCEV(I); 46140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner } 462394437ff7eaccfe1de92fe14d0022ca0addf3e41Chris Lattner } 46340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner#endif 4646148c02591bd83da7b957589c4bbf6f9720d503fChris Lattner} 465