LoopIdiomRecognize.cpp revision e41d3c015ce5cafde305d9a6d9baaae1c41bf46a
1e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner//===-- LoopIdiomRecognize.cpp - Loop idiom recognition -------------------===// 2e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner// 3e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner// The LLVM Compiler Infrastructure 4e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner// 5e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner// This file is distributed under the University of Illinois Open Source 6e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner// License. See LICENSE.TXT for details. 7e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner// 8e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner//===----------------------------------------------------------------------===// 9e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner// 10e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner// This pass implements an idiom recognizer that transforms simple loops into a 11e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner// non-loop form. In cases that this kicks in, it can be a significant 12e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner// performance win. 13e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner// 14e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner//===----------------------------------------------------------------------===// 15bdce5720ad878259544e6a4e3621dac32cf2d134Chris Lattner// 16bdce5720ad878259544e6a4e3621dac32cf2d134Chris Lattner// TODO List: 17bdce5720ad878259544e6a4e3621dac32cf2d134Chris Lattner// 18bdce5720ad878259544e6a4e3621dac32cf2d134Chris Lattner// Future loop memory idioms to recognize: 19bdce5720ad878259544e6a4e3621dac32cf2d134Chris Lattner// memcmp, memmove, strlen, etc. 20bdce5720ad878259544e6a4e3621dac32cf2d134Chris Lattner// Future floating point idioms to recognize in -ffast-math mode: 21bdce5720ad878259544e6a4e3621dac32cf2d134Chris Lattner// fpowi 22bdce5720ad878259544e6a4e3621dac32cf2d134Chris Lattner// Future integer operation idioms to recognize: 23bdce5720ad878259544e6a4e3621dac32cf2d134Chris Lattner// ctpop, ctlz, cttz 24bdce5720ad878259544e6a4e3621dac32cf2d134Chris Lattner// 25bdce5720ad878259544e6a4e3621dac32cf2d134Chris Lattner// Beware that isel's default lowering for ctpop is highly inefficient for 26bdce5720ad878259544e6a4e3621dac32cf2d134Chris Lattner// i64 and larger types when i64 is legal and the value has few bits set. It 27bdce5720ad878259544e6a4e3621dac32cf2d134Chris Lattner// would be good to enhance isel to emit a loop for ctpop in this case. 28bdce5720ad878259544e6a4e3621dac32cf2d134Chris Lattner// 29bdce5720ad878259544e6a4e3621dac32cf2d134Chris Lattner// We should enhance the memset/memcpy recognition to handle multiple stores in 30bdce5720ad878259544e6a4e3621dac32cf2d134Chris Lattner// the loop. This would handle things like: 31bdce5720ad878259544e6a4e3621dac32cf2d134Chris Lattner// void foo(_Complex float *P) 32bdce5720ad878259544e6a4e3621dac32cf2d134Chris Lattner// for (i) { __real__(*P) = 0; __imag__(*P) = 0; } 33bdce5720ad878259544e6a4e3621dac32cf2d134Chris Lattner// this is also "Example 2" from http://blog.regehr.org/archives/320 3491139ccd995149dd0d5e4ab3604d9239e1f90a54Chris Lattner// 35d957c717918c412402157b85fc51b4c6d2631381Chris Lattner// This could recognize common matrix multiplies and dot product idioms and 3691139ccd995149dd0d5e4ab3604d9239e1f90a54Chris Lattner// replace them with calls to BLAS (if linked in??). 3791139ccd995149dd0d5e4ab3604d9239e1f90a54Chris Lattner// 38bdce5720ad878259544e6a4e3621dac32cf2d134Chris Lattner//===----------------------------------------------------------------------===// 39e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner 40e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner#define DEBUG_TYPE "loop-idiom" 41e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner#include "llvm/Transforms/Scalar.h" 42e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner#include "llvm/IntrinsicInst.h" 432e12f1ac6ebd49e5c41b7e9dcd802f3df40a1bc7Chris Lattner#include "llvm/Analysis/AliasAnalysis.h" 44e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner#include "llvm/Analysis/LoopPass.h" 45e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner#include "llvm/Analysis/ScalarEvolutionExpressions.h" 46a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner#include "llvm/Analysis/ScalarEvolutionExpander.h" 4722920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner#include "llvm/Analysis/ValueTracking.h" 4822920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner#include "llvm/Target/TargetData.h" 499f39188def2b4102817945522fac1209083efa06Chris Lattner#include "llvm/Transforms/Utils/Local.h" 50e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner#include "llvm/Support/Debug.h" 51a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner#include "llvm/Support/IRBuilder.h" 52e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner#include "llvm/Support/raw_ostream.h" 534ce31fb57412b16cd61337ba41c60112dfbecfb6Chris Lattner#include "llvm/ADT/Statistic.h" 54e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattnerusing namespace llvm; 55e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner 564ce31fb57412b16cd61337ba41c60112dfbecfb6Chris LattnerSTATISTIC(NumMemSet, "Number of memset's formed from loop stores"); 574ce31fb57412b16cd61337ba41c60112dfbecfb6Chris LattnerSTATISTIC(NumMemCpy, "Number of memcpy's formed from loop load+stores"); 58e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner 59e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattnernamespace { 60e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner class LoopIdiomRecognize : public LoopPass { 6122920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner Loop *CurLoop; 6222920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner const TargetData *TD; 6362c50fdf69064c0d086aedfadb6ceb7c303bbcb9Chris Lattner DominatorTree *DT; 6422920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner ScalarEvolution *SE; 65e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner public: 66e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner static char ID; 67e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner explicit LoopIdiomRecognize() : LoopPass(ID) { 68e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner initializeLoopIdiomRecognizePass(*PassRegistry::getPassRegistry()); 69e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner } 70e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner 71e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner bool runOnLoop(Loop *L, LPPassManager &LPM); 7262c50fdf69064c0d086aedfadb6ceb7c303bbcb9Chris Lattner bool runOnLoopBlock(BasicBlock *BB, const SCEV *BECount, 7362c50fdf69064c0d086aedfadb6ceb7c303bbcb9Chris Lattner SmallVectorImpl<BasicBlock*> &ExitBlocks); 74e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner 7522920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner bool processLoopStore(StoreInst *SI, const SCEV *BECount); 76e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner bool processLoopMemSet(MemSetInst *MSI, const SCEV *BECount); 77e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner 78e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner bool processLoopStoreOfSplatValue(Value *DestPtr, unsigned StoreSize, 79e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner unsigned StoreAlignment, 80e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner Value *SplatValue, Instruction *TheStore, 81a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner const SCEVAddRecExpr *Ev, 82a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner const SCEV *BECount); 83e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner bool processLoopStoreOfLoopLoad(StoreInst *SI, unsigned StoreSize, 84e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner const SCEVAddRecExpr *StoreEv, 85e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner const SCEVAddRecExpr *LoadEv, 86e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner const SCEV *BECount); 87e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner 88e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner /// This transformation requires natural loop information & requires that 89e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner /// loop preheaders be inserted into the CFG. 90e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner /// 91e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner virtual void getAnalysisUsage(AnalysisUsage &AU) const { 92e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner AU.addRequired<LoopInfo>(); 93e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner AU.addPreserved<LoopInfo>(); 94e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner AU.addRequiredID(LoopSimplifyID); 95e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner AU.addPreservedID(LoopSimplifyID); 96e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner AU.addRequiredID(LCSSAID); 97e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner AU.addPreservedID(LCSSAID); 982e12f1ac6ebd49e5c41b7e9dcd802f3df40a1bc7Chris Lattner AU.addRequired<AliasAnalysis>(); 992e12f1ac6ebd49e5c41b7e9dcd802f3df40a1bc7Chris Lattner AU.addPreserved<AliasAnalysis>(); 100e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner AU.addRequired<ScalarEvolution>(); 101e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner AU.addPreserved<ScalarEvolution>(); 102e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner AU.addPreserved<DominatorTree>(); 10362c50fdf69064c0d086aedfadb6ceb7c303bbcb9Chris Lattner AU.addRequired<DominatorTree>(); 104e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner } 105e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner }; 106e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner} 107e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner 108e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattnerchar LoopIdiomRecognize::ID = 0; 109e6bb649ec63059d795a31198c3c569c137e7ad59Chris LattnerINITIALIZE_PASS_BEGIN(LoopIdiomRecognize, "loop-idiom", "Recognize loop idioms", 110e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner false, false) 111e6bb649ec63059d795a31198c3c569c137e7ad59Chris LattnerINITIALIZE_PASS_DEPENDENCY(LoopInfo) 11262c50fdf69064c0d086aedfadb6ceb7c303bbcb9Chris LattnerINITIALIZE_PASS_DEPENDENCY(DominatorTree) 113e6bb649ec63059d795a31198c3c569c137e7ad59Chris LattnerINITIALIZE_PASS_DEPENDENCY(LoopSimplify) 114e6bb649ec63059d795a31198c3c569c137e7ad59Chris LattnerINITIALIZE_PASS_DEPENDENCY(LCSSA) 115e6bb649ec63059d795a31198c3c569c137e7ad59Chris LattnerINITIALIZE_PASS_DEPENDENCY(ScalarEvolution) 1162e12f1ac6ebd49e5c41b7e9dcd802f3df40a1bc7Chris LattnerINITIALIZE_AG_DEPENDENCY(AliasAnalysis) 117e6bb649ec63059d795a31198c3c569c137e7ad59Chris LattnerINITIALIZE_PASS_END(LoopIdiomRecognize, "loop-idiom", "Recognize loop idioms", 118e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner false, false) 119e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner 120e6bb649ec63059d795a31198c3c569c137e7ad59Chris LattnerPass *llvm::createLoopIdiomPass() { return new LoopIdiomRecognize(); } 121e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner 1229f39188def2b4102817945522fac1209083efa06Chris Lattner/// DeleteDeadInstruction - Delete this instruction. Before we do, go through 1239f39188def2b4102817945522fac1209083efa06Chris Lattner/// and zero out all the operands of this instruction. If any of them become 1249f39188def2b4102817945522fac1209083efa06Chris Lattner/// dead, delete them and the computation tree that feeds them. 1259f39188def2b4102817945522fac1209083efa06Chris Lattner/// 1269f39188def2b4102817945522fac1209083efa06Chris Lattnerstatic void DeleteDeadInstruction(Instruction *I, ScalarEvolution &SE) { 1279f39188def2b4102817945522fac1209083efa06Chris Lattner SmallVector<Instruction*, 32> NowDeadInsts; 1289f39188def2b4102817945522fac1209083efa06Chris Lattner 1299f39188def2b4102817945522fac1209083efa06Chris Lattner NowDeadInsts.push_back(I); 1309f39188def2b4102817945522fac1209083efa06Chris Lattner 1319f39188def2b4102817945522fac1209083efa06Chris Lattner // Before we touch this instruction, remove it from SE! 1329f39188def2b4102817945522fac1209083efa06Chris Lattner do { 1339f39188def2b4102817945522fac1209083efa06Chris Lattner Instruction *DeadInst = NowDeadInsts.pop_back_val(); 1349f39188def2b4102817945522fac1209083efa06Chris Lattner 1359f39188def2b4102817945522fac1209083efa06Chris Lattner // This instruction is dead, zap it, in stages. Start by removing it from 1369f39188def2b4102817945522fac1209083efa06Chris Lattner // SCEV. 1379f39188def2b4102817945522fac1209083efa06Chris Lattner SE.forgetValue(DeadInst); 1389f39188def2b4102817945522fac1209083efa06Chris Lattner 1399f39188def2b4102817945522fac1209083efa06Chris Lattner for (unsigned op = 0, e = DeadInst->getNumOperands(); op != e; ++op) { 1409f39188def2b4102817945522fac1209083efa06Chris Lattner Value *Op = DeadInst->getOperand(op); 1419f39188def2b4102817945522fac1209083efa06Chris Lattner DeadInst->setOperand(op, 0); 1429f39188def2b4102817945522fac1209083efa06Chris Lattner 1439f39188def2b4102817945522fac1209083efa06Chris Lattner // If this operand just became dead, add it to the NowDeadInsts list. 1449f39188def2b4102817945522fac1209083efa06Chris Lattner if (!Op->use_empty()) continue; 1459f39188def2b4102817945522fac1209083efa06Chris Lattner 1469f39188def2b4102817945522fac1209083efa06Chris Lattner if (Instruction *OpI = dyn_cast<Instruction>(Op)) 1479f39188def2b4102817945522fac1209083efa06Chris Lattner if (isInstructionTriviallyDead(OpI)) 1489f39188def2b4102817945522fac1209083efa06Chris Lattner NowDeadInsts.push_back(OpI); 1499f39188def2b4102817945522fac1209083efa06Chris Lattner } 1509f39188def2b4102817945522fac1209083efa06Chris Lattner 1519f39188def2b4102817945522fac1209083efa06Chris Lattner DeadInst->eraseFromParent(); 1529f39188def2b4102817945522fac1209083efa06Chris Lattner 1539f39188def2b4102817945522fac1209083efa06Chris Lattner } while (!NowDeadInsts.empty()); 1549f39188def2b4102817945522fac1209083efa06Chris Lattner} 1559f39188def2b4102817945522fac1209083efa06Chris Lattner 156e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattnerbool LoopIdiomRecognize::runOnLoop(Loop *L, LPPassManager &LPM) { 15722920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner CurLoop = L; 15822920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner 15922920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner // The trip count of the loop must be analyzable. 16022920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner SE = &getAnalysis<ScalarEvolution>(); 16122920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner if (!SE->hasLoopInvariantBackedgeTakenCount(L)) 16222920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner return false; 16322920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner const SCEV *BECount = SE->getBackedgeTakenCount(L); 16422920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner if (isa<SCEVCouldNotCompute>(BECount)) return false; 16522920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner 1668e08e73f0e12c9e669f2d7d0a5c9213df3046c01Chris Lattner // If this loop executes exactly one time, then it should be peeled, not 1678e08e73f0e12c9e669f2d7d0a5c9213df3046c01Chris Lattner // optimized by this pass. 1688e08e73f0e12c9e669f2d7d0a5c9213df3046c01Chris Lattner if (const SCEVConstant *BECst = dyn_cast<SCEVConstant>(BECount)) 1698e08e73f0e12c9e669f2d7d0a5c9213df3046c01Chris Lattner if (BECst->getValue()->getValue() == 0) 1708e08e73f0e12c9e669f2d7d0a5c9213df3046c01Chris Lattner return false; 1718e08e73f0e12c9e669f2d7d0a5c9213df3046c01Chris Lattner 17222920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner // We require target data for now. 17322920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner TD = getAnalysisIfAvailable<TargetData>(); 17422920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner if (TD == 0) return false; 17562c50fdf69064c0d086aedfadb6ceb7c303bbcb9Chris Lattner 17662c50fdf69064c0d086aedfadb6ceb7c303bbcb9Chris Lattner DT = &getAnalysis<DominatorTree>(); 17762c50fdf69064c0d086aedfadb6ceb7c303bbcb9Chris Lattner LoopInfo &LI = getAnalysis<LoopInfo>(); 17822920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner 17962c50fdf69064c0d086aedfadb6ceb7c303bbcb9Chris Lattner SmallVector<BasicBlock*, 8> ExitBlocks; 18062c50fdf69064c0d086aedfadb6ceb7c303bbcb9Chris Lattner CurLoop->getUniqueExitBlocks(ExitBlocks); 18162c50fdf69064c0d086aedfadb6ceb7c303bbcb9Chris Lattner 18263f9c3c49ac7011e6366fbec42716f3f70f1beeeChris Lattner DEBUG(dbgs() << "loop-idiom Scanning: F[" 18363f9c3c49ac7011e6366fbec42716f3f70f1beeeChris Lattner << L->getHeader()->getParent()->getName() 18463f9c3c49ac7011e6366fbec42716f3f70f1beeeChris Lattner << "] Loop %" << L->getHeader()->getName() << "\n"); 18563f9c3c49ac7011e6366fbec42716f3f70f1beeeChris Lattner 18662c50fdf69064c0d086aedfadb6ceb7c303bbcb9Chris Lattner bool MadeChange = false; 18762c50fdf69064c0d086aedfadb6ceb7c303bbcb9Chris Lattner // Scan all the blocks in the loop that are not in subloops. 18862c50fdf69064c0d086aedfadb6ceb7c303bbcb9Chris Lattner for (Loop::block_iterator BI = L->block_begin(), E = L->block_end(); BI != E; 18962c50fdf69064c0d086aedfadb6ceb7c303bbcb9Chris Lattner ++BI) { 19062c50fdf69064c0d086aedfadb6ceb7c303bbcb9Chris Lattner // Ignore blocks in subloops. 19162c50fdf69064c0d086aedfadb6ceb7c303bbcb9Chris Lattner if (LI.getLoopFor(*BI) != CurLoop) 19262c50fdf69064c0d086aedfadb6ceb7c303bbcb9Chris Lattner continue; 19362c50fdf69064c0d086aedfadb6ceb7c303bbcb9Chris Lattner 19462c50fdf69064c0d086aedfadb6ceb7c303bbcb9Chris Lattner MadeChange |= runOnLoopBlock(*BI, BECount, ExitBlocks); 19562c50fdf69064c0d086aedfadb6ceb7c303bbcb9Chris Lattner } 19662c50fdf69064c0d086aedfadb6ceb7c303bbcb9Chris Lattner return MadeChange; 19762c50fdf69064c0d086aedfadb6ceb7c303bbcb9Chris Lattner} 198e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner 19962c50fdf69064c0d086aedfadb6ceb7c303bbcb9Chris Lattner/// runOnLoopBlock - Process the specified block, which lives in a counted loop 20062c50fdf69064c0d086aedfadb6ceb7c303bbcb9Chris Lattner/// with the specified backedge count. This block is known to be in the current 20162c50fdf69064c0d086aedfadb6ceb7c303bbcb9Chris Lattner/// loop and not in any subloops. 20262c50fdf69064c0d086aedfadb6ceb7c303bbcb9Chris Lattnerbool LoopIdiomRecognize::runOnLoopBlock(BasicBlock *BB, const SCEV *BECount, 20362c50fdf69064c0d086aedfadb6ceb7c303bbcb9Chris Lattner SmallVectorImpl<BasicBlock*> &ExitBlocks) { 20462c50fdf69064c0d086aedfadb6ceb7c303bbcb9Chris Lattner // We can only promote stores in this block if they are unconditionally 20562c50fdf69064c0d086aedfadb6ceb7c303bbcb9Chris Lattner // executed in the loop. For a block to be unconditionally executed, it has 20662c50fdf69064c0d086aedfadb6ceb7c303bbcb9Chris Lattner // to dominate all the exit blocks of the loop. Verify this now. 20762c50fdf69064c0d086aedfadb6ceb7c303bbcb9Chris Lattner for (unsigned i = 0, e = ExitBlocks.size(); i != e; ++i) 20862c50fdf69064c0d086aedfadb6ceb7c303bbcb9Chris Lattner if (!DT->dominates(BB, ExitBlocks[i])) 20962c50fdf69064c0d086aedfadb6ceb7c303bbcb9Chris Lattner return false; 21062c50fdf69064c0d086aedfadb6ceb7c303bbcb9Chris Lattner 21122920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner bool MadeChange = false; 21222920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ) { 213b7e9ef0ed1e246bd64d97a768555c8334c0d86e9Chris Lattner Instruction *Inst = I++; 214b7e9ef0ed1e246bd64d97a768555c8334c0d86e9Chris Lattner // Look for store instructions, which may be optimized to memset/memcpy. 215b7e9ef0ed1e246bd64d97a768555c8334c0d86e9Chris Lattner if (StoreInst *SI = dyn_cast<StoreInst>(Inst)) { 216b7e9ef0ed1e246bd64d97a768555c8334c0d86e9Chris Lattner WeakVH InstPtr(I); 217b7e9ef0ed1e246bd64d97a768555c8334c0d86e9Chris Lattner if (!processLoopStore(SI, BECount)) continue; 218b7e9ef0ed1e246bd64d97a768555c8334c0d86e9Chris Lattner MadeChange = true; 219b7e9ef0ed1e246bd64d97a768555c8334c0d86e9Chris Lattner 220b7e9ef0ed1e246bd64d97a768555c8334c0d86e9Chris Lattner // If processing the store invalidated our iterator, start over from the 221e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner // top of the block. 222b7e9ef0ed1e246bd64d97a768555c8334c0d86e9Chris Lattner if (InstPtr == 0) 223b7e9ef0ed1e246bd64d97a768555c8334c0d86e9Chris Lattner I = BB->begin(); 224b7e9ef0ed1e246bd64d97a768555c8334c0d86e9Chris Lattner continue; 225b7e9ef0ed1e246bd64d97a768555c8334c0d86e9Chris Lattner } 2262e12f1ac6ebd49e5c41b7e9dcd802f3df40a1bc7Chris Lattner 227e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner // Look for memset instructions, which may be optimized to a larger memset. 228e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner if (MemSetInst *MSI = dyn_cast<MemSetInst>(Inst)) { 229e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner WeakVH InstPtr(I); 230e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner if (!processLoopMemSet(MSI, BECount)) continue; 231e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner MadeChange = true; 232e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner 233e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner // If processing the memset invalidated our iterator, start over from the 234e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner // top of the block. 235e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner if (InstPtr == 0) 236e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner I = BB->begin(); 237e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner continue; 238e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner } 23922920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner } 24022920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner 24122920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner return MadeChange; 242e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner} 243e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner 24462c50fdf69064c0d086aedfadb6ceb7c303bbcb9Chris Lattner 245e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner/// processLoopStore - See if this store can be promoted to a memset or memcpy. 24622920b59864cac3b62d158fd4111cfda3c09c67aChris Lattnerbool LoopIdiomRecognize::processLoopStore(StoreInst *SI, const SCEV *BECount) { 247e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner if (SI->isVolatile()) return false; 248e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner 24922920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner Value *StoredVal = SI->getValueOperand(); 250a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner Value *StorePtr = SI->getPointerOperand(); 251e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner 25295ae676bc89b4cb9166576b74f1220ab5b0ff0adChris Lattner // Reject stores that are so large that they overflow an unsigned. 25322920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner uint64_t SizeInBits = TD->getTypeSizeInBits(StoredVal->getType()); 25495ae676bc89b4cb9166576b74f1220ab5b0ff0adChris Lattner if ((SizeInBits & 7) || (SizeInBits >> 32) != 0) 25522920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner return false; 25622920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner 25722920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner // See if the pointer expression is an AddRec like {base,+,1} on the current 25822920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner // loop, which indicates a strided store. If we have something else, it's a 25922920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner // random store we can't handle. 260e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner const SCEVAddRecExpr *StoreEv = 261e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner dyn_cast<SCEVAddRecExpr>(SE->getSCEV(StorePtr)); 262e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner if (StoreEv == 0 || StoreEv->getLoop() != CurLoop || !StoreEv->isAffine()) 26322920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner return false; 26422920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner 26522920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner // Check to see if the stride matches the size of the store. If so, then we 26622920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner // know that every byte is touched in the loop. 26722920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner unsigned StoreSize = (unsigned)SizeInBits >> 3; 268e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner const SCEVConstant *Stride = dyn_cast<SCEVConstant>(StoreEv->getOperand(1)); 26930980b68151a1c1527306aa0f39e3b297af05583Chris Lattner 27030980b68151a1c1527306aa0f39e3b297af05583Chris Lattner // TODO: Could also handle negative stride here someday, that will require the 2716f96b275b62529c341168d516c290189bf408a7cOwen Anderson // validity check in mayLoopAccessLocation to be updated though. 27222920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner if (Stride == 0 || StoreSize != Stride->getValue()->getValue()) 27322920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner return false; 274e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner 27522920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner // If the stored value is a byte-wise value (like i32 -1), then it may be 27622920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner // turned into a memset of i8 -1, assuming that all the consequtive bytes 27722920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner // are stored. A store of i32 0x01020304 can never be turned into a memset. 278a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner if (Value *SplatValue = isBytewiseValue(StoredVal)) 279e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner if (processLoopStoreOfSplatValue(StorePtr, StoreSize, SI->getAlignment(), 280e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner SplatValue, SI, StoreEv, BECount)) 281e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner return true; 282a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner 283e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner // If the stored value is a strided load in the same loop with the same stride 284e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner // this this may be transformable into a memcpy. This kicks in for stuff like 285e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner // for (i) A[i] = B[i]; 286e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner if (LoadInst *LI = dyn_cast<LoadInst>(StoredVal)) { 287e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner const SCEVAddRecExpr *LoadEv = 288e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner dyn_cast<SCEVAddRecExpr>(SE->getSCEV(LI->getOperand(0))); 289e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner if (LoadEv && LoadEv->getLoop() == CurLoop && LoadEv->isAffine() && 290e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner StoreEv->getOperand(1) == LoadEv->getOperand(1) && !LI->isVolatile()) 291e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner if (processLoopStoreOfLoopLoad(SI, StoreSize, StoreEv, LoadEv, BECount)) 292e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner return true; 293e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner } 2944ce31fb57412b16cd61337ba41c60112dfbecfb6Chris Lattner //errs() << "UNHANDLED strided store: " << *StoreEv << " - " << *SI << "\n"; 29522920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner 296e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner return false; 297e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner} 298e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner 299e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner/// processLoopMemSet - See if this memset can be promoted to a large memset. 300e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattnerbool LoopIdiomRecognize:: 301e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris LattnerprocessLoopMemSet(MemSetInst *MSI, const SCEV *BECount) { 302e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner // We can only handle non-volatile memsets with a constant size. 303e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner if (MSI->isVolatile() || !isa<ConstantInt>(MSI->getLength())) return false; 304e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner 305e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner Value *Pointer = MSI->getDest(); 306e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner 307e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner // See if the pointer expression is an AddRec like {base,+,1} on the current 308e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner // loop, which indicates a strided store. If we have something else, it's a 309e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner // random store we can't handle. 310e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner const SCEVAddRecExpr *Ev = dyn_cast<SCEVAddRecExpr>(SE->getSCEV(Pointer)); 311e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner if (Ev == 0 || Ev->getLoop() != CurLoop || !Ev->isAffine()) 312e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner return false; 313e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner 314e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner // Reject memsets that are so large that they overflow an unsigned. 315e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner uint64_t SizeInBytes = cast<ConstantInt>(MSI->getLength())->getZExtValue(); 316e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner if ((SizeInBytes >> 32) != 0) 317e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner return false; 318e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner 319e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner // Check to see if the stride matches the size of the memset. If so, then we 320e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner // know that every byte is touched in the loop. 321e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner const SCEVConstant *Stride = dyn_cast<SCEVConstant>(Ev->getOperand(1)); 322e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner 323e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner // TODO: Could also handle negative stride here someday, that will require the 324e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner // validity check in mayLoopAccessLocation to be updated though. 325e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner if (Stride == 0 || MSI->getLength() != Stride->getValue()) 326e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner return false; 327e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner 328e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner return processLoopStoreOfSplatValue(Pointer, (unsigned)SizeInBytes, 329e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner MSI->getAlignment(), MSI->getValue(), 330e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner MSI, Ev, BECount); 331e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner} 332e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner 333e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner 33463f9c3c49ac7011e6366fbec42716f3f70f1beeeChris Lattner/// mayLoopAccessLocation - Return true if the specified loop might access the 33563f9c3c49ac7011e6366fbec42716f3f70f1beeeChris Lattner/// specified pointer location, which is a loop-strided access. The 'Access' 33663f9c3c49ac7011e6366fbec42716f3f70f1beeeChris Lattner/// argument specifies what the verboten forms of access are (read or write). 33763f9c3c49ac7011e6366fbec42716f3f70f1beeeChris Lattnerstatic bool mayLoopAccessLocation(Value *Ptr,AliasAnalysis::ModRefResult Access, 33863f9c3c49ac7011e6366fbec42716f3f70f1beeeChris Lattner Loop *L, const SCEV *BECount, 339e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner unsigned StoreSize, AliasAnalysis &AA, 340e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner Instruction *IgnoredStore) { 34130980b68151a1c1527306aa0f39e3b297af05583Chris Lattner // Get the location that may be stored across the loop. Since the access is 34230980b68151a1c1527306aa0f39e3b297af05583Chris Lattner // strided positively through memory, we say that the modified location starts 34330980b68151a1c1527306aa0f39e3b297af05583Chris Lattner // at the pointer and has infinite size. 344a64cbf067d6315522d13b606774bbadb4e328d1bChris Lattner uint64_t AccessSize = AliasAnalysis::UnknownSize; 345a64cbf067d6315522d13b606774bbadb4e328d1bChris Lattner 346a64cbf067d6315522d13b606774bbadb4e328d1bChris Lattner // If the loop iterates a fixed number of times, we can refine the access size 347a64cbf067d6315522d13b606774bbadb4e328d1bChris Lattner // to be exactly the size of the memset, which is (BECount+1)*StoreSize 348a64cbf067d6315522d13b606774bbadb4e328d1bChris Lattner if (const SCEVConstant *BECst = dyn_cast<SCEVConstant>(BECount)) 349a64cbf067d6315522d13b606774bbadb4e328d1bChris Lattner AccessSize = (BECst->getValue()->getZExtValue()+1)*StoreSize; 350a64cbf067d6315522d13b606774bbadb4e328d1bChris Lattner 351a64cbf067d6315522d13b606774bbadb4e328d1bChris Lattner // TODO: For this to be really effective, we have to dive into the pointer 352a64cbf067d6315522d13b606774bbadb4e328d1bChris Lattner // operand in the store. Store to &A[i] of 100 will always return may alias 353a64cbf067d6315522d13b606774bbadb4e328d1bChris Lattner // with store of &A[100], we need to StoreLoc to be "A" with size of 100, 354a64cbf067d6315522d13b606774bbadb4e328d1bChris Lattner // which will then no-alias a store to &A[100]. 355e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner AliasAnalysis::Location StoreLoc(Ptr, AccessSize); 35630980b68151a1c1527306aa0f39e3b297af05583Chris Lattner 35730980b68151a1c1527306aa0f39e3b297af05583Chris Lattner for (Loop::block_iterator BI = L->block_begin(), E = L->block_end(); BI != E; 35830980b68151a1c1527306aa0f39e3b297af05583Chris Lattner ++BI) 35930980b68151a1c1527306aa0f39e3b297af05583Chris Lattner for (BasicBlock::iterator I = (*BI)->begin(), E = (*BI)->end(); I != E; ++I) 360e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner if (&*I != IgnoredStore && 36163f9c3c49ac7011e6366fbec42716f3f70f1beeeChris Lattner (AA.getModRefInfo(I, StoreLoc) & Access)) 36230980b68151a1c1527306aa0f39e3b297af05583Chris Lattner return true; 36330980b68151a1c1527306aa0f39e3b297af05583Chris Lattner 36430980b68151a1c1527306aa0f39e3b297af05583Chris Lattner return false; 36530980b68151a1c1527306aa0f39e3b297af05583Chris Lattner} 36630980b68151a1c1527306aa0f39e3b297af05583Chris Lattner 367a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner/// processLoopStoreOfSplatValue - We see a strided store of a memsetable value. 368a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner/// If we can transform this into a memset in the loop preheader, do so. 369a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattnerbool LoopIdiomRecognize:: 370e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris LattnerprocessLoopStoreOfSplatValue(Value *DestPtr, unsigned StoreSize, 371e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner unsigned StoreAlignment, Value *SplatValue, 372e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner Instruction *TheStore, 373a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner const SCEVAddRecExpr *Ev, const SCEV *BECount) { 374bafa117e8f2e3532f391227ebc9d4513b17edbadChris Lattner // Verify that the stored value is loop invariant. If not, we can't promote 375bafa117e8f2e3532f391227ebc9d4513b17edbadChris Lattner // the memset. 376bafa117e8f2e3532f391227ebc9d4513b17edbadChris Lattner if (!CurLoop->isLoopInvariant(SplatValue)) 377bafa117e8f2e3532f391227ebc9d4513b17edbadChris Lattner return false; 378bafa117e8f2e3532f391227ebc9d4513b17edbadChris Lattner 379a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner // Okay, we have a strided store "p[i]" of a splattable value. We can turn 380a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner // this into a memset in the loop preheader now if we want. However, this 381a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner // would be unsafe to do if there is anything else in the loop that may read 382a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner // or write to the aliased location. Check for an alias. 383e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner if (mayLoopAccessLocation(DestPtr, AliasAnalysis::ModRef, 38463f9c3c49ac7011e6366fbec42716f3f70f1beeeChris Lattner CurLoop, BECount, 385e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner StoreSize, getAnalysis<AliasAnalysis>(), TheStore)) 386e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner return false; 387a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner 388a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner // Okay, everything looks good, insert the memset. 389a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner BasicBlock *Preheader = CurLoop->getLoopPreheader(); 390a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner 391a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner IRBuilder<> Builder(Preheader->getTerminator()); 392a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner 393a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner // The trip count of the loop and the base pointer of the addrec SCEV is 394a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner // guaranteed to be loop invariant, which means that it should dominate the 395a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner // header. Just insert code for it in the preheader. 396a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner SCEVExpander Expander(*SE); 397a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner 398e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner unsigned AddrSpace = cast<PointerType>(DestPtr->getType())->getAddressSpace(); 399a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner Value *BasePtr = 400a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner Expander.expandCodeFor(Ev->getStart(), Builder.getInt8PtrTy(AddrSpace), 401a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner Preheader->getTerminator()); 402a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner 403a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner // The # stored bytes is (BECount+1)*Size. Expand the trip count out to 404a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner // pointer size if it isn't already. 405e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner const Type *IntPtr = TD->getIntPtrType(SplatValue->getContext()); 4067c90b90f4e9b0c421f0e45d7de03f6edce113a90Chris Lattner BECount = SE->getTruncateOrZeroExtend(BECount, IntPtr); 407a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner 408a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner const SCEV *NumBytesS = SE->getAddExpr(BECount, SE->getConstant(IntPtr, 1), 4097c90b90f4e9b0c421f0e45d7de03f6edce113a90Chris Lattner true /*no unsigned overflow*/); 410a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner if (StoreSize != 1) 411a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner NumBytesS = SE->getMulExpr(NumBytesS, SE->getConstant(IntPtr, StoreSize), 4127c90b90f4e9b0c421f0e45d7de03f6edce113a90Chris Lattner true /*no unsigned overflow*/); 413a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner 414a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner Value *NumBytes = 415a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner Expander.expandCodeFor(NumBytesS, IntPtr, Preheader->getTerminator()); 416a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner 417a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner Value *NewCall = 418e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner Builder.CreateMemSet(BasePtr, SplatValue, NumBytes, StoreAlignment); 419a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner 420a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner DEBUG(dbgs() << " Formed memset: " << *NewCall << "\n" 421e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner << " from store to: " << *Ev << " at: " << *TheStore << "\n"); 4227922d34b6073712cb62f7d4d74810509c19a84dfDuncan Sands (void)NewCall; 423a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner 4249f39188def2b4102817945522fac1209083efa06Chris Lattner // Okay, the memset has been formed. Zap the original store and anything that 4259f39188def2b4102817945522fac1209083efa06Chris Lattner // feeds into it. 426e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner DeleteDeadInstruction(TheStore, *SE); 4274ce31fb57412b16cd61337ba41c60112dfbecfb6Chris Lattner ++NumMemSet; 428a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner return true; 429a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner} 430a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner 431e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner/// processLoopStoreOfLoopLoad - We see a strided store whose value is a 432e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner/// same-strided load. 433e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattnerbool LoopIdiomRecognize:: 434e2c43920919c6fe376613d1d8331897dc1ba3d57Chris LattnerprocessLoopStoreOfLoopLoad(StoreInst *SI, unsigned StoreSize, 435e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner const SCEVAddRecExpr *StoreEv, 436e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner const SCEVAddRecExpr *LoadEv, 437e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner const SCEV *BECount) { 438e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner LoadInst *LI = cast<LoadInst>(SI->getValueOperand()); 439e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner 440e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner // Okay, we have a strided store "p[i]" of a loaded value. We can turn 441bdce5720ad878259544e6a4e3621dac32cf2d134Chris Lattner // this into a memcpy in the loop preheader now if we want. However, this 442e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner // would be unsafe to do if there is anything else in the loop that may read 44363f9c3c49ac7011e6366fbec42716f3f70f1beeeChris Lattner // or write to the stored location (including the load feeding the stores). 444e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner // Check for an alias. 44563f9c3c49ac7011e6366fbec42716f3f70f1beeeChris Lattner if (mayLoopAccessLocation(SI->getPointerOperand(), AliasAnalysis::ModRef, 44663f9c3c49ac7011e6366fbec42716f3f70f1beeeChris Lattner CurLoop, BECount, StoreSize, 44763f9c3c49ac7011e6366fbec42716f3f70f1beeeChris Lattner getAnalysis<AliasAnalysis>(), SI)) 44863f9c3c49ac7011e6366fbec42716f3f70f1beeeChris Lattner return false; 44963f9c3c49ac7011e6366fbec42716f3f70f1beeeChris Lattner 45063f9c3c49ac7011e6366fbec42716f3f70f1beeeChris Lattner // For a memcpy, we have to make sure that the input array is not being 45163f9c3c49ac7011e6366fbec42716f3f70f1beeeChris Lattner // mutated by the loop. 45263f9c3c49ac7011e6366fbec42716f3f70f1beeeChris Lattner if (mayLoopAccessLocation(LI->getPointerOperand(), AliasAnalysis::Mod, 45363f9c3c49ac7011e6366fbec42716f3f70f1beeeChris Lattner CurLoop, BECount, StoreSize, 45463f9c3c49ac7011e6366fbec42716f3f70f1beeeChris Lattner getAnalysis<AliasAnalysis>(), SI)) 455e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner return false; 456e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner 457e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner // Okay, everything looks good, insert the memcpy. 458e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner BasicBlock *Preheader = CurLoop->getLoopPreheader(); 459e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner 460e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner IRBuilder<> Builder(Preheader->getTerminator()); 461e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner 462e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner // The trip count of the loop and the base pointer of the addrec SCEV is 463e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner // guaranteed to be loop invariant, which means that it should dominate the 464e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner // header. Just insert code for it in the preheader. 465e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner SCEVExpander Expander(*SE); 466e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner 467e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner Value *LoadBasePtr = 468e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner Expander.expandCodeFor(LoadEv->getStart(), 469e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner Builder.getInt8PtrTy(LI->getPointerAddressSpace()), 470e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner Preheader->getTerminator()); 471e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner Value *StoreBasePtr = 472e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner Expander.expandCodeFor(StoreEv->getStart(), 473e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner Builder.getInt8PtrTy(SI->getPointerAddressSpace()), 474e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner Preheader->getTerminator()); 475e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner 476e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner // The # stored bytes is (BECount+1)*Size. Expand the trip count out to 477e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner // pointer size if it isn't already. 478e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner const Type *IntPtr = TD->getIntPtrType(SI->getContext()); 4797c90b90f4e9b0c421f0e45d7de03f6edce113a90Chris Lattner BECount = SE->getTruncateOrZeroExtend(BECount, IntPtr); 480e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner 481e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner const SCEV *NumBytesS = SE->getAddExpr(BECount, SE->getConstant(IntPtr, 1), 4827c90b90f4e9b0c421f0e45d7de03f6edce113a90Chris Lattner true /*no unsigned overflow*/); 483e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner if (StoreSize != 1) 484e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner NumBytesS = SE->getMulExpr(NumBytesS, SE->getConstant(IntPtr, StoreSize), 4857c90b90f4e9b0c421f0e45d7de03f6edce113a90Chris Lattner true /*no unsigned overflow*/); 486e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner 487e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner Value *NumBytes = 488e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner Expander.expandCodeFor(NumBytesS, IntPtr, Preheader->getTerminator()); 489e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner 490e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner Value *NewCall = 491e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner Builder.CreateMemCpy(StoreBasePtr, LoadBasePtr, NumBytes, 492e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner std::min(SI->getAlignment(), LI->getAlignment())); 493e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner 494e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner DEBUG(dbgs() << " Formed memcpy: " << *NewCall << "\n" 495e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner << " from load ptr=" << *LoadEv << " at: " << *LI << "\n" 496e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner << " from store ptr=" << *StoreEv << " at: " << *SI << "\n"); 497e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner (void)NewCall; 498e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner 499e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner // Okay, the memset has been formed. Zap the original store and anything that 500e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner // feeds into it. 501e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner DeleteDeadInstruction(SI, *SE); 5024ce31fb57412b16cd61337ba41c60112dfbecfb6Chris Lattner ++NumMemCpy; 503e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner return true; 504e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner} 505