LoopIdiomRecognize.cpp revision 0e68cee62f251c45df92c71ca536142bc7d82631
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; } 3391139ccd995149dd0d5e4ab3604d9239e1f90a54Chris Lattner// 34408b534e431cc317f1116cd78df96da2af7cafd9Chris Lattner// We should enhance this to handle negative strides through memory. 35408b534e431cc317f1116cd78df96da2af7cafd9Chris Lattner// Alternatively (and perhaps better) we could rely on an earlier pass to force 36408b534e431cc317f1116cd78df96da2af7cafd9Chris Lattner// forward iteration through memory, which is generally better for cache 37408b534e431cc317f1116cd78df96da2af7cafd9Chris Lattner// behavior. Negative strides *do* happen for memset/memcpy loops. 38408b534e431cc317f1116cd78df96da2af7cafd9Chris Lattner// 39d957c717918c412402157b85fc51b4c6d2631381Chris Lattner// This could recognize common matrix multiplies and dot product idioms and 4091139ccd995149dd0d5e4ab3604d9239e1f90a54Chris Lattner// replace them with calls to BLAS (if linked in??). 4191139ccd995149dd0d5e4ab3604d9239e1f90a54Chris Lattner// 42bdce5720ad878259544e6a4e3621dac32cf2d134Chris Lattner//===----------------------------------------------------------------------===// 43e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner 44e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner#define DEBUG_TYPE "loop-idiom" 45e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner#include "llvm/Transforms/Scalar.h" 46e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner#include "llvm/IntrinsicInst.h" 473a393728a62122d7009d8e2cbe52a221874e576aChris Lattner#include "llvm/Module.h" 482e12f1ac6ebd49e5c41b7e9dcd802f3df40a1bc7Chris Lattner#include "llvm/Analysis/AliasAnalysis.h" 49e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner#include "llvm/Analysis/LoopPass.h" 50e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner#include "llvm/Analysis/ScalarEvolutionExpressions.h" 51a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner#include "llvm/Analysis/ScalarEvolutionExpander.h" 5222920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner#include "llvm/Analysis/ValueTracking.h" 5322920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner#include "llvm/Target/TargetData.h" 54c19175c9d8d3c2663b682a7fe34bb22da370d5c1Chris Lattner#include "llvm/Target/TargetLibraryInfo.h" 559f39188def2b4102817945522fac1209083efa06Chris Lattner#include "llvm/Transforms/Utils/Local.h" 56e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner#include "llvm/Support/Debug.h" 57a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner#include "llvm/Support/IRBuilder.h" 58e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner#include "llvm/Support/raw_ostream.h" 594ce31fb57412b16cd61337ba41c60112dfbecfb6Chris Lattner#include "llvm/ADT/Statistic.h" 60e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattnerusing namespace llvm; 61e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner 624ce31fb57412b16cd61337ba41c60112dfbecfb6Chris LattnerSTATISTIC(NumMemSet, "Number of memset's formed from loop stores"); 634ce31fb57412b16cd61337ba41c60112dfbecfb6Chris LattnerSTATISTIC(NumMemCpy, "Number of memcpy's formed from loop load+stores"); 64e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner 65e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattnernamespace { 66e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner class LoopIdiomRecognize : public LoopPass { 6722920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner Loop *CurLoop; 6822920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner const TargetData *TD; 6962c50fdf69064c0d086aedfadb6ceb7c303bbcb9Chris Lattner DominatorTree *DT; 7022920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner ScalarEvolution *SE; 71c19175c9d8d3c2663b682a7fe34bb22da370d5c1Chris Lattner TargetLibraryInfo *TLI; 72e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner public: 73e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner static char ID; 74e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner explicit LoopIdiomRecognize() : LoopPass(ID) { 75e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner initializeLoopIdiomRecognizePass(*PassRegistry::getPassRegistry()); 76e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner } 77e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner 78e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner bool runOnLoop(Loop *L, LPPassManager &LPM); 7962c50fdf69064c0d086aedfadb6ceb7c303bbcb9Chris Lattner bool runOnLoopBlock(BasicBlock *BB, const SCEV *BECount, 8062c50fdf69064c0d086aedfadb6ceb7c303bbcb9Chris Lattner SmallVectorImpl<BasicBlock*> &ExitBlocks); 81e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner 8222920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner bool processLoopStore(StoreInst *SI, const SCEV *BECount); 83e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner bool processLoopMemSet(MemSetInst *MSI, const SCEV *BECount); 84e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner 853a393728a62122d7009d8e2cbe52a221874e576aChris Lattner bool processLoopStridedStore(Value *DestPtr, unsigned StoreSize, 863a393728a62122d7009d8e2cbe52a221874e576aChris Lattner unsigned StoreAlignment, 873a393728a62122d7009d8e2cbe52a221874e576aChris Lattner Value *SplatValue, Instruction *TheStore, 883a393728a62122d7009d8e2cbe52a221874e576aChris Lattner const SCEVAddRecExpr *Ev, 893a393728a62122d7009d8e2cbe52a221874e576aChris Lattner const SCEV *BECount); 90e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner bool processLoopStoreOfLoopLoad(StoreInst *SI, unsigned StoreSize, 91e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner const SCEVAddRecExpr *StoreEv, 92e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner const SCEVAddRecExpr *LoadEv, 93e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner const SCEV *BECount); 94e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner 95e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner /// This transformation requires natural loop information & requires that 96e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner /// loop preheaders be inserted into the CFG. 97e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner /// 98e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner virtual void getAnalysisUsage(AnalysisUsage &AU) const { 99e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner AU.addRequired<LoopInfo>(); 100e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner AU.addPreserved<LoopInfo>(); 101e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner AU.addRequiredID(LoopSimplifyID); 102e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner AU.addPreservedID(LoopSimplifyID); 103e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner AU.addRequiredID(LCSSAID); 104e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner AU.addPreservedID(LCSSAID); 1052e12f1ac6ebd49e5c41b7e9dcd802f3df40a1bc7Chris Lattner AU.addRequired<AliasAnalysis>(); 1062e12f1ac6ebd49e5c41b7e9dcd802f3df40a1bc7Chris Lattner AU.addPreserved<AliasAnalysis>(); 107e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner AU.addRequired<ScalarEvolution>(); 108e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner AU.addPreserved<ScalarEvolution>(); 109e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner AU.addPreserved<DominatorTree>(); 11062c50fdf69064c0d086aedfadb6ceb7c303bbcb9Chris Lattner AU.addRequired<DominatorTree>(); 111c19175c9d8d3c2663b682a7fe34bb22da370d5c1Chris Lattner AU.addRequired<TargetLibraryInfo>(); 112e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner } 113e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner }; 114e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner} 115e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner 116e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattnerchar LoopIdiomRecognize::ID = 0; 117e6bb649ec63059d795a31198c3c569c137e7ad59Chris LattnerINITIALIZE_PASS_BEGIN(LoopIdiomRecognize, "loop-idiom", "Recognize loop idioms", 118e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner false, false) 119e6bb649ec63059d795a31198c3c569c137e7ad59Chris LattnerINITIALIZE_PASS_DEPENDENCY(LoopInfo) 12062c50fdf69064c0d086aedfadb6ceb7c303bbcb9Chris LattnerINITIALIZE_PASS_DEPENDENCY(DominatorTree) 121e6bb649ec63059d795a31198c3c569c137e7ad59Chris LattnerINITIALIZE_PASS_DEPENDENCY(LoopSimplify) 122e6bb649ec63059d795a31198c3c569c137e7ad59Chris LattnerINITIALIZE_PASS_DEPENDENCY(LCSSA) 123e6bb649ec63059d795a31198c3c569c137e7ad59Chris LattnerINITIALIZE_PASS_DEPENDENCY(ScalarEvolution) 124c19175c9d8d3c2663b682a7fe34bb22da370d5c1Chris LattnerINITIALIZE_PASS_DEPENDENCY(TargetLibraryInfo) 1252e12f1ac6ebd49e5c41b7e9dcd802f3df40a1bc7Chris LattnerINITIALIZE_AG_DEPENDENCY(AliasAnalysis) 126e6bb649ec63059d795a31198c3c569c137e7ad59Chris LattnerINITIALIZE_PASS_END(LoopIdiomRecognize, "loop-idiom", "Recognize loop idioms", 127e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner false, false) 128e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner 129e6bb649ec63059d795a31198c3c569c137e7ad59Chris LattnerPass *llvm::createLoopIdiomPass() { return new LoopIdiomRecognize(); } 130e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner 1319f39188def2b4102817945522fac1209083efa06Chris Lattner/// DeleteDeadInstruction - Delete this instruction. Before we do, go through 1329f39188def2b4102817945522fac1209083efa06Chris Lattner/// and zero out all the operands of this instruction. If any of them become 1339f39188def2b4102817945522fac1209083efa06Chris Lattner/// dead, delete them and the computation tree that feeds them. 1349f39188def2b4102817945522fac1209083efa06Chris Lattner/// 1359f39188def2b4102817945522fac1209083efa06Chris Lattnerstatic void DeleteDeadInstruction(Instruction *I, ScalarEvolution &SE) { 1369f39188def2b4102817945522fac1209083efa06Chris Lattner SmallVector<Instruction*, 32> NowDeadInsts; 1379f39188def2b4102817945522fac1209083efa06Chris Lattner 1389f39188def2b4102817945522fac1209083efa06Chris Lattner NowDeadInsts.push_back(I); 1399f39188def2b4102817945522fac1209083efa06Chris Lattner 1409f39188def2b4102817945522fac1209083efa06Chris Lattner // Before we touch this instruction, remove it from SE! 1419f39188def2b4102817945522fac1209083efa06Chris Lattner do { 1429f39188def2b4102817945522fac1209083efa06Chris Lattner Instruction *DeadInst = NowDeadInsts.pop_back_val(); 1439f39188def2b4102817945522fac1209083efa06Chris Lattner 1449f39188def2b4102817945522fac1209083efa06Chris Lattner // This instruction is dead, zap it, in stages. Start by removing it from 1459f39188def2b4102817945522fac1209083efa06Chris Lattner // SCEV. 1469f39188def2b4102817945522fac1209083efa06Chris Lattner SE.forgetValue(DeadInst); 1479f39188def2b4102817945522fac1209083efa06Chris Lattner 1489f39188def2b4102817945522fac1209083efa06Chris Lattner for (unsigned op = 0, e = DeadInst->getNumOperands(); op != e; ++op) { 1499f39188def2b4102817945522fac1209083efa06Chris Lattner Value *Op = DeadInst->getOperand(op); 1509f39188def2b4102817945522fac1209083efa06Chris Lattner DeadInst->setOperand(op, 0); 1519f39188def2b4102817945522fac1209083efa06Chris Lattner 1529f39188def2b4102817945522fac1209083efa06Chris Lattner // If this operand just became dead, add it to the NowDeadInsts list. 1539f39188def2b4102817945522fac1209083efa06Chris Lattner if (!Op->use_empty()) continue; 1549f39188def2b4102817945522fac1209083efa06Chris Lattner 1559f39188def2b4102817945522fac1209083efa06Chris Lattner if (Instruction *OpI = dyn_cast<Instruction>(Op)) 1569f39188def2b4102817945522fac1209083efa06Chris Lattner if (isInstructionTriviallyDead(OpI)) 1579f39188def2b4102817945522fac1209083efa06Chris Lattner NowDeadInsts.push_back(OpI); 1589f39188def2b4102817945522fac1209083efa06Chris Lattner } 1599f39188def2b4102817945522fac1209083efa06Chris Lattner 1609f39188def2b4102817945522fac1209083efa06Chris Lattner DeadInst->eraseFromParent(); 1619f39188def2b4102817945522fac1209083efa06Chris Lattner 1629f39188def2b4102817945522fac1209083efa06Chris Lattner } while (!NowDeadInsts.empty()); 1639f39188def2b4102817945522fac1209083efa06Chris Lattner} 1649f39188def2b4102817945522fac1209083efa06Chris Lattner 165e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattnerbool LoopIdiomRecognize::runOnLoop(Loop *L, LPPassManager &LPM) { 16622920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner CurLoop = L; 16722920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner 16822920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner // The trip count of the loop must be analyzable. 16922920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner SE = &getAnalysis<ScalarEvolution>(); 17022920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner if (!SE->hasLoopInvariantBackedgeTakenCount(L)) 17122920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner return false; 17222920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner const SCEV *BECount = SE->getBackedgeTakenCount(L); 17322920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner if (isa<SCEVCouldNotCompute>(BECount)) return false; 17422920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner 1758e08e73f0e12c9e669f2d7d0a5c9213df3046c01Chris Lattner // If this loop executes exactly one time, then it should be peeled, not 1768e08e73f0e12c9e669f2d7d0a5c9213df3046c01Chris Lattner // optimized by this pass. 1778e08e73f0e12c9e669f2d7d0a5c9213df3046c01Chris Lattner if (const SCEVConstant *BECst = dyn_cast<SCEVConstant>(BECount)) 1788e08e73f0e12c9e669f2d7d0a5c9213df3046c01Chris Lattner if (BECst->getValue()->getValue() == 0) 1798e08e73f0e12c9e669f2d7d0a5c9213df3046c01Chris Lattner return false; 1808e08e73f0e12c9e669f2d7d0a5c9213df3046c01Chris Lattner 18122920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner // We require target data for now. 18222920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner TD = getAnalysisIfAvailable<TargetData>(); 18322920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner if (TD == 0) return false; 18462c50fdf69064c0d086aedfadb6ceb7c303bbcb9Chris Lattner 18562c50fdf69064c0d086aedfadb6ceb7c303bbcb9Chris Lattner DT = &getAnalysis<DominatorTree>(); 18662c50fdf69064c0d086aedfadb6ceb7c303bbcb9Chris Lattner LoopInfo &LI = getAnalysis<LoopInfo>(); 187c19175c9d8d3c2663b682a7fe34bb22da370d5c1Chris Lattner TLI = &getAnalysis<TargetLibraryInfo>(); 18822920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner 18962c50fdf69064c0d086aedfadb6ceb7c303bbcb9Chris Lattner SmallVector<BasicBlock*, 8> ExitBlocks; 19062c50fdf69064c0d086aedfadb6ceb7c303bbcb9Chris Lattner CurLoop->getUniqueExitBlocks(ExitBlocks); 19162c50fdf69064c0d086aedfadb6ceb7c303bbcb9Chris Lattner 19263f9c3c49ac7011e6366fbec42716f3f70f1beeeChris Lattner DEBUG(dbgs() << "loop-idiom Scanning: F[" 19363f9c3c49ac7011e6366fbec42716f3f70f1beeeChris Lattner << L->getHeader()->getParent()->getName() 19463f9c3c49ac7011e6366fbec42716f3f70f1beeeChris Lattner << "] Loop %" << L->getHeader()->getName() << "\n"); 19563f9c3c49ac7011e6366fbec42716f3f70f1beeeChris Lattner 19662c50fdf69064c0d086aedfadb6ceb7c303bbcb9Chris Lattner bool MadeChange = false; 19762c50fdf69064c0d086aedfadb6ceb7c303bbcb9Chris Lattner // Scan all the blocks in the loop that are not in subloops. 19862c50fdf69064c0d086aedfadb6ceb7c303bbcb9Chris Lattner for (Loop::block_iterator BI = L->block_begin(), E = L->block_end(); BI != E; 19962c50fdf69064c0d086aedfadb6ceb7c303bbcb9Chris Lattner ++BI) { 20062c50fdf69064c0d086aedfadb6ceb7c303bbcb9Chris Lattner // Ignore blocks in subloops. 20162c50fdf69064c0d086aedfadb6ceb7c303bbcb9Chris Lattner if (LI.getLoopFor(*BI) != CurLoop) 20262c50fdf69064c0d086aedfadb6ceb7c303bbcb9Chris Lattner continue; 20362c50fdf69064c0d086aedfadb6ceb7c303bbcb9Chris Lattner 20462c50fdf69064c0d086aedfadb6ceb7c303bbcb9Chris Lattner MadeChange |= runOnLoopBlock(*BI, BECount, ExitBlocks); 20562c50fdf69064c0d086aedfadb6ceb7c303bbcb9Chris Lattner } 20662c50fdf69064c0d086aedfadb6ceb7c303bbcb9Chris Lattner return MadeChange; 20762c50fdf69064c0d086aedfadb6ceb7c303bbcb9Chris Lattner} 208e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner 20962c50fdf69064c0d086aedfadb6ceb7c303bbcb9Chris Lattner/// runOnLoopBlock - Process the specified block, which lives in a counted loop 21062c50fdf69064c0d086aedfadb6ceb7c303bbcb9Chris Lattner/// with the specified backedge count. This block is known to be in the current 21162c50fdf69064c0d086aedfadb6ceb7c303bbcb9Chris Lattner/// loop and not in any subloops. 21262c50fdf69064c0d086aedfadb6ceb7c303bbcb9Chris Lattnerbool LoopIdiomRecognize::runOnLoopBlock(BasicBlock *BB, const SCEV *BECount, 21362c50fdf69064c0d086aedfadb6ceb7c303bbcb9Chris Lattner SmallVectorImpl<BasicBlock*> &ExitBlocks) { 21462c50fdf69064c0d086aedfadb6ceb7c303bbcb9Chris Lattner // We can only promote stores in this block if they are unconditionally 21562c50fdf69064c0d086aedfadb6ceb7c303bbcb9Chris Lattner // executed in the loop. For a block to be unconditionally executed, it has 21662c50fdf69064c0d086aedfadb6ceb7c303bbcb9Chris Lattner // to dominate all the exit blocks of the loop. Verify this now. 21762c50fdf69064c0d086aedfadb6ceb7c303bbcb9Chris Lattner for (unsigned i = 0, e = ExitBlocks.size(); i != e; ++i) 21862c50fdf69064c0d086aedfadb6ceb7c303bbcb9Chris Lattner if (!DT->dominates(BB, ExitBlocks[i])) 21962c50fdf69064c0d086aedfadb6ceb7c303bbcb9Chris Lattner return false; 22062c50fdf69064c0d086aedfadb6ceb7c303bbcb9Chris Lattner 22122920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner bool MadeChange = false; 22222920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ) { 223b7e9ef0ed1e246bd64d97a768555c8334c0d86e9Chris Lattner Instruction *Inst = I++; 224b7e9ef0ed1e246bd64d97a768555c8334c0d86e9Chris Lattner // Look for store instructions, which may be optimized to memset/memcpy. 225b7e9ef0ed1e246bd64d97a768555c8334c0d86e9Chris Lattner if (StoreInst *SI = dyn_cast<StoreInst>(Inst)) { 226b7e9ef0ed1e246bd64d97a768555c8334c0d86e9Chris Lattner WeakVH InstPtr(I); 227b7e9ef0ed1e246bd64d97a768555c8334c0d86e9Chris Lattner if (!processLoopStore(SI, BECount)) continue; 228b7e9ef0ed1e246bd64d97a768555c8334c0d86e9Chris Lattner MadeChange = true; 229b7e9ef0ed1e246bd64d97a768555c8334c0d86e9Chris Lattner 230b7e9ef0ed1e246bd64d97a768555c8334c0d86e9Chris Lattner // If processing the store invalidated our iterator, start over from the 231e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner // top of the block. 232b7e9ef0ed1e246bd64d97a768555c8334c0d86e9Chris Lattner if (InstPtr == 0) 233b7e9ef0ed1e246bd64d97a768555c8334c0d86e9Chris Lattner I = BB->begin(); 234b7e9ef0ed1e246bd64d97a768555c8334c0d86e9Chris Lattner continue; 235b7e9ef0ed1e246bd64d97a768555c8334c0d86e9Chris Lattner } 2362e12f1ac6ebd49e5c41b7e9dcd802f3df40a1bc7Chris Lattner 237e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner // Look for memset instructions, which may be optimized to a larger memset. 238e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner if (MemSetInst *MSI = dyn_cast<MemSetInst>(Inst)) { 239e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner WeakVH InstPtr(I); 240e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner if (!processLoopMemSet(MSI, BECount)) continue; 241e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner MadeChange = true; 242e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner 243e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner // If processing the memset invalidated our iterator, start over from the 244e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner // top of the block. 245e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner if (InstPtr == 0) 246e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner I = BB->begin(); 247e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner continue; 248e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner } 24922920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner } 25022920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner 25122920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner return MadeChange; 252e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner} 253e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner 25462c50fdf69064c0d086aedfadb6ceb7c303bbcb9Chris Lattner 255e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner/// processLoopStore - See if this store can be promoted to a memset or memcpy. 25622920b59864cac3b62d158fd4111cfda3c09c67aChris Lattnerbool LoopIdiomRecognize::processLoopStore(StoreInst *SI, const SCEV *BECount) { 257e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner if (SI->isVolatile()) return false; 258e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner 25922920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner Value *StoredVal = SI->getValueOperand(); 260a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner Value *StorePtr = SI->getPointerOperand(); 261e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner 26295ae676bc89b4cb9166576b74f1220ab5b0ff0adChris Lattner // Reject stores that are so large that they overflow an unsigned. 26322920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner uint64_t SizeInBits = TD->getTypeSizeInBits(StoredVal->getType()); 26495ae676bc89b4cb9166576b74f1220ab5b0ff0adChris Lattner if ((SizeInBits & 7) || (SizeInBits >> 32) != 0) 26522920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner return false; 26622920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner 26722920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner // See if the pointer expression is an AddRec like {base,+,1} on the current 26822920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner // loop, which indicates a strided store. If we have something else, it's a 26922920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner // random store we can't handle. 270e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner const SCEVAddRecExpr *StoreEv = 271e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner dyn_cast<SCEVAddRecExpr>(SE->getSCEV(StorePtr)); 272e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner if (StoreEv == 0 || StoreEv->getLoop() != CurLoop || !StoreEv->isAffine()) 27322920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner return false; 27422920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner 27522920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner // Check to see if the stride matches the size of the store. If so, then we 27622920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner // know that every byte is touched in the loop. 27722920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner unsigned StoreSize = (unsigned)SizeInBits >> 3; 278e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner const SCEVConstant *Stride = dyn_cast<SCEVConstant>(StoreEv->getOperand(1)); 27930980b68151a1c1527306aa0f39e3b297af05583Chris Lattner 280408b534e431cc317f1116cd78df96da2af7cafd9Chris Lattner if (Stride == 0 || StoreSize != Stride->getValue()->getValue()) { 281408b534e431cc317f1116cd78df96da2af7cafd9Chris Lattner // TODO: Could also handle negative stride here someday, that will require 282408b534e431cc317f1116cd78df96da2af7cafd9Chris Lattner // the validity check in mayLoopAccessLocation to be updated though. 283408b534e431cc317f1116cd78df96da2af7cafd9Chris Lattner // Enable this to print exact negative strides. 2840e68cee62f251c45df92c71ca536142bc7d82631Chris Lattner if (0 && Stride && StoreSize == -Stride->getValue()->getValue()) { 285408b534e431cc317f1116cd78df96da2af7cafd9Chris Lattner dbgs() << "NEGATIVE STRIDE: " << *SI << "\n"; 286408b534e431cc317f1116cd78df96da2af7cafd9Chris Lattner dbgs() << "BB: " << *SI->getParent(); 287408b534e431cc317f1116cd78df96da2af7cafd9Chris Lattner } 288408b534e431cc317f1116cd78df96da2af7cafd9Chris Lattner 28922920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner return false; 290408b534e431cc317f1116cd78df96da2af7cafd9Chris Lattner } 2913a393728a62122d7009d8e2cbe52a221874e576aChris Lattner 2923a393728a62122d7009d8e2cbe52a221874e576aChris Lattner // See if we can optimize just this store in isolation. 2933a393728a62122d7009d8e2cbe52a221874e576aChris Lattner if (processLoopStridedStore(StorePtr, StoreSize, SI->getAlignment(), 2943a393728a62122d7009d8e2cbe52a221874e576aChris Lattner StoredVal, SI, StoreEv, BECount)) 2953a393728a62122d7009d8e2cbe52a221874e576aChris Lattner return true; 296a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner 297e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner // If the stored value is a strided load in the same loop with the same stride 298e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner // this this may be transformable into a memcpy. This kicks in for stuff like 299e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner // for (i) A[i] = B[i]; 300e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner if (LoadInst *LI = dyn_cast<LoadInst>(StoredVal)) { 301e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner const SCEVAddRecExpr *LoadEv = 302e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner dyn_cast<SCEVAddRecExpr>(SE->getSCEV(LI->getOperand(0))); 303e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner if (LoadEv && LoadEv->getLoop() == CurLoop && LoadEv->isAffine() && 304e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner StoreEv->getOperand(1) == LoadEv->getOperand(1) && !LI->isVolatile()) 305e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner if (processLoopStoreOfLoopLoad(SI, StoreSize, StoreEv, LoadEv, BECount)) 306e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner return true; 307e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner } 3084ce31fb57412b16cd61337ba41c60112dfbecfb6Chris Lattner //errs() << "UNHANDLED strided store: " << *StoreEv << " - " << *SI << "\n"; 30922920b59864cac3b62d158fd4111cfda3c09c67aChris Lattner 310e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner return false; 311e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner} 312e6bb649ec63059d795a31198c3c569c137e7ad59Chris Lattner 313e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner/// processLoopMemSet - See if this memset can be promoted to a large memset. 314e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattnerbool LoopIdiomRecognize:: 315e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris LattnerprocessLoopMemSet(MemSetInst *MSI, const SCEV *BECount) { 316e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner // We can only handle non-volatile memsets with a constant size. 317e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner if (MSI->isVolatile() || !isa<ConstantInt>(MSI->getLength())) return false; 318e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner 319c19175c9d8d3c2663b682a7fe34bb22da370d5c1Chris Lattner // If we're not allowed to hack on memset, we fail. 320c19175c9d8d3c2663b682a7fe34bb22da370d5c1Chris Lattner if (!TLI->has(LibFunc::memset)) 321c19175c9d8d3c2663b682a7fe34bb22da370d5c1Chris Lattner return false; 322c19175c9d8d3c2663b682a7fe34bb22da370d5c1Chris Lattner 323e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner Value *Pointer = MSI->getDest(); 324e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner 325e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner // See if the pointer expression is an AddRec like {base,+,1} on the current 326e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner // loop, which indicates a strided store. If we have something else, it's a 327e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner // random store we can't handle. 328e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner const SCEVAddRecExpr *Ev = dyn_cast<SCEVAddRecExpr>(SE->getSCEV(Pointer)); 329e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner if (Ev == 0 || Ev->getLoop() != CurLoop || !Ev->isAffine()) 330e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner return false; 331e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner 332e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner // Reject memsets that are so large that they overflow an unsigned. 333e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner uint64_t SizeInBytes = cast<ConstantInt>(MSI->getLength())->getZExtValue(); 334e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner if ((SizeInBytes >> 32) != 0) 335e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner return false; 336e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner 337e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner // Check to see if the stride matches the size of the memset. If so, then we 338e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner // know that every byte is touched in the loop. 339e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner const SCEVConstant *Stride = dyn_cast<SCEVConstant>(Ev->getOperand(1)); 340e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner 341e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner // TODO: Could also handle negative stride here someday, that will require the 342e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner // validity check in mayLoopAccessLocation to be updated though. 343e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner if (Stride == 0 || MSI->getLength() != Stride->getValue()) 344e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner return false; 345e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner 3463a393728a62122d7009d8e2cbe52a221874e576aChris Lattner return processLoopStridedStore(Pointer, (unsigned)SizeInBytes, 3473a393728a62122d7009d8e2cbe52a221874e576aChris Lattner MSI->getAlignment(), MSI->getValue(), 3483a393728a62122d7009d8e2cbe52a221874e576aChris Lattner MSI, Ev, BECount); 349e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner} 350e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner 351e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner 35263f9c3c49ac7011e6366fbec42716f3f70f1beeeChris Lattner/// mayLoopAccessLocation - Return true if the specified loop might access the 35363f9c3c49ac7011e6366fbec42716f3f70f1beeeChris Lattner/// specified pointer location, which is a loop-strided access. The 'Access' 35463f9c3c49ac7011e6366fbec42716f3f70f1beeeChris Lattner/// argument specifies what the verboten forms of access are (read or write). 35563f9c3c49ac7011e6366fbec42716f3f70f1beeeChris Lattnerstatic bool mayLoopAccessLocation(Value *Ptr,AliasAnalysis::ModRefResult Access, 35663f9c3c49ac7011e6366fbec42716f3f70f1beeeChris Lattner Loop *L, const SCEV *BECount, 357e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner unsigned StoreSize, AliasAnalysis &AA, 358e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner Instruction *IgnoredStore) { 35930980b68151a1c1527306aa0f39e3b297af05583Chris Lattner // Get the location that may be stored across the loop. Since the access is 36030980b68151a1c1527306aa0f39e3b297af05583Chris Lattner // strided positively through memory, we say that the modified location starts 36130980b68151a1c1527306aa0f39e3b297af05583Chris Lattner // at the pointer and has infinite size. 362a64cbf067d6315522d13b606774bbadb4e328d1bChris Lattner uint64_t AccessSize = AliasAnalysis::UnknownSize; 363a64cbf067d6315522d13b606774bbadb4e328d1bChris Lattner 364a64cbf067d6315522d13b606774bbadb4e328d1bChris Lattner // If the loop iterates a fixed number of times, we can refine the access size 365a64cbf067d6315522d13b606774bbadb4e328d1bChris Lattner // to be exactly the size of the memset, which is (BECount+1)*StoreSize 366a64cbf067d6315522d13b606774bbadb4e328d1bChris Lattner if (const SCEVConstant *BECst = dyn_cast<SCEVConstant>(BECount)) 367a64cbf067d6315522d13b606774bbadb4e328d1bChris Lattner AccessSize = (BECst->getValue()->getZExtValue()+1)*StoreSize; 368a64cbf067d6315522d13b606774bbadb4e328d1bChris Lattner 369a64cbf067d6315522d13b606774bbadb4e328d1bChris Lattner // TODO: For this to be really effective, we have to dive into the pointer 370a64cbf067d6315522d13b606774bbadb4e328d1bChris Lattner // operand in the store. Store to &A[i] of 100 will always return may alias 371a64cbf067d6315522d13b606774bbadb4e328d1bChris Lattner // with store of &A[100], we need to StoreLoc to be "A" with size of 100, 372a64cbf067d6315522d13b606774bbadb4e328d1bChris Lattner // which will then no-alias a store to &A[100]. 373e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner AliasAnalysis::Location StoreLoc(Ptr, AccessSize); 37430980b68151a1c1527306aa0f39e3b297af05583Chris Lattner 37530980b68151a1c1527306aa0f39e3b297af05583Chris Lattner for (Loop::block_iterator BI = L->block_begin(), E = L->block_end(); BI != E; 37630980b68151a1c1527306aa0f39e3b297af05583Chris Lattner ++BI) 37730980b68151a1c1527306aa0f39e3b297af05583Chris Lattner for (BasicBlock::iterator I = (*BI)->begin(), E = (*BI)->end(); I != E; ++I) 378e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner if (&*I != IgnoredStore && 37963f9c3c49ac7011e6366fbec42716f3f70f1beeeChris Lattner (AA.getModRefInfo(I, StoreLoc) & Access)) 38030980b68151a1c1527306aa0f39e3b297af05583Chris Lattner return true; 38130980b68151a1c1527306aa0f39e3b297af05583Chris Lattner 38230980b68151a1c1527306aa0f39e3b297af05583Chris Lattner return false; 38330980b68151a1c1527306aa0f39e3b297af05583Chris Lattner} 38430980b68151a1c1527306aa0f39e3b297af05583Chris Lattner 3853a393728a62122d7009d8e2cbe52a221874e576aChris Lattner/// getMemSetPatternValue - If a strided store of the specified value is safe to 3863a393728a62122d7009d8e2cbe52a221874e576aChris Lattner/// turn into a memset_pattern16, return a ConstantArray of 16 bytes that should 3873a393728a62122d7009d8e2cbe52a221874e576aChris Lattner/// be passed in. Otherwise, return null. 3883a393728a62122d7009d8e2cbe52a221874e576aChris Lattner/// 3893a393728a62122d7009d8e2cbe52a221874e576aChris Lattner/// Note that we don't ever attempt to use memset_pattern8 or 4, because these 3903a393728a62122d7009d8e2cbe52a221874e576aChris Lattner/// just replicate their input array and then pass on to memset_pattern16. 3913a393728a62122d7009d8e2cbe52a221874e576aChris Lattnerstatic Constant *getMemSetPatternValue(Value *V, const TargetData &TD) { 3923a393728a62122d7009d8e2cbe52a221874e576aChris Lattner // If the value isn't a constant, we can't promote it to being in a constant 3933a393728a62122d7009d8e2cbe52a221874e576aChris Lattner // array. We could theoretically do a store to an alloca or something, but 3943a393728a62122d7009d8e2cbe52a221874e576aChris Lattner // that doesn't seem worthwhile. 3953a393728a62122d7009d8e2cbe52a221874e576aChris Lattner Constant *C = dyn_cast<Constant>(V); 3963a393728a62122d7009d8e2cbe52a221874e576aChris Lattner if (C == 0) return 0; 3973a393728a62122d7009d8e2cbe52a221874e576aChris Lattner 3983a393728a62122d7009d8e2cbe52a221874e576aChris Lattner // Only handle simple values that are a power of two bytes in size. 3993a393728a62122d7009d8e2cbe52a221874e576aChris Lattner uint64_t Size = TD.getTypeSizeInBits(V->getType()); 4003a393728a62122d7009d8e2cbe52a221874e576aChris Lattner if (Size == 0 || (Size & 7) || (Size & (Size-1))) 4013a393728a62122d7009d8e2cbe52a221874e576aChris Lattner return 0; 4023a393728a62122d7009d8e2cbe52a221874e576aChris Lattner 40380e8b506b8134d63dc3cb6211cccc34be4b19d40Chris Lattner // Don't care enough about darwin/ppc to implement this. 40480e8b506b8134d63dc3cb6211cccc34be4b19d40Chris Lattner if (TD.isBigEndian()) 40580e8b506b8134d63dc3cb6211cccc34be4b19d40Chris Lattner return 0; 4063a393728a62122d7009d8e2cbe52a221874e576aChris Lattner 4073a393728a62122d7009d8e2cbe52a221874e576aChris Lattner // Convert to size in bytes. 4083a393728a62122d7009d8e2cbe52a221874e576aChris Lattner Size /= 8; 409c19175c9d8d3c2663b682a7fe34bb22da370d5c1Chris Lattner 4103a393728a62122d7009d8e2cbe52a221874e576aChris Lattner // TODO: If CI is larger than 16-bytes, we can try slicing it in half to see 41180e8b506b8134d63dc3cb6211cccc34be4b19d40Chris Lattner // if the top and bottom are the same (e.g. for vectors and large integers). 4123a393728a62122d7009d8e2cbe52a221874e576aChris Lattner if (Size > 16) return 0; 4133a393728a62122d7009d8e2cbe52a221874e576aChris Lattner 41480e8b506b8134d63dc3cb6211cccc34be4b19d40Chris Lattner // If the constant is exactly 16 bytes, just use it. 41580e8b506b8134d63dc3cb6211cccc34be4b19d40Chris Lattner if (Size == 16) return C; 41680e8b506b8134d63dc3cb6211cccc34be4b19d40Chris Lattner 41780e8b506b8134d63dc3cb6211cccc34be4b19d40Chris Lattner // Otherwise, we'll use an array of the constants. 41880e8b506b8134d63dc3cb6211cccc34be4b19d40Chris Lattner unsigned ArraySize = 16/Size; 41980e8b506b8134d63dc3cb6211cccc34be4b19d40Chris Lattner ArrayType *AT = ArrayType::get(V->getType(), ArraySize); 42080e8b506b8134d63dc3cb6211cccc34be4b19d40Chris Lattner return ConstantArray::get(AT, std::vector<Constant*>(ArraySize, C)); 4213a393728a62122d7009d8e2cbe52a221874e576aChris Lattner} 4223a393728a62122d7009d8e2cbe52a221874e576aChris Lattner 4233a393728a62122d7009d8e2cbe52a221874e576aChris Lattner 4243a393728a62122d7009d8e2cbe52a221874e576aChris Lattner/// processLoopStridedStore - We see a strided store of some value. If we can 4253a393728a62122d7009d8e2cbe52a221874e576aChris Lattner/// transform this into a memset or memset_pattern in the loop preheader, do so. 4263a393728a62122d7009d8e2cbe52a221874e576aChris Lattnerbool LoopIdiomRecognize:: 4273a393728a62122d7009d8e2cbe52a221874e576aChris LattnerprocessLoopStridedStore(Value *DestPtr, unsigned StoreSize, 4283a393728a62122d7009d8e2cbe52a221874e576aChris Lattner unsigned StoreAlignment, Value *StoredVal, 4293a393728a62122d7009d8e2cbe52a221874e576aChris Lattner Instruction *TheStore, const SCEVAddRecExpr *Ev, 4303a393728a62122d7009d8e2cbe52a221874e576aChris Lattner const SCEV *BECount) { 4313a393728a62122d7009d8e2cbe52a221874e576aChris Lattner 4323a393728a62122d7009d8e2cbe52a221874e576aChris Lattner // If the stored value is a byte-wise value (like i32 -1), then it may be 4333a393728a62122d7009d8e2cbe52a221874e576aChris Lattner // turned into a memset of i8 -1, assuming that all the consecutive bytes 4343a393728a62122d7009d8e2cbe52a221874e576aChris Lattner // are stored. A store of i32 0x01020304 can never be turned into a memset, 4353a393728a62122d7009d8e2cbe52a221874e576aChris Lattner // but it can be turned into memset_pattern if the target supports it. 4363a393728a62122d7009d8e2cbe52a221874e576aChris Lattner Value *SplatValue = isBytewiseValue(StoredVal); 4373a393728a62122d7009d8e2cbe52a221874e576aChris Lattner Constant *PatternValue = 0; 4383a393728a62122d7009d8e2cbe52a221874e576aChris Lattner 4393a393728a62122d7009d8e2cbe52a221874e576aChris Lattner // If we're allowed to form a memset, and the stored value would be acceptable 4403a393728a62122d7009d8e2cbe52a221874e576aChris Lattner // for memset, use it. 4413a393728a62122d7009d8e2cbe52a221874e576aChris Lattner if (SplatValue && TLI->has(LibFunc::memset) && 4423a393728a62122d7009d8e2cbe52a221874e576aChris Lattner // Verify that the stored value is loop invariant. If not, we can't 4433a393728a62122d7009d8e2cbe52a221874e576aChris Lattner // promote the memset. 4443a393728a62122d7009d8e2cbe52a221874e576aChris Lattner CurLoop->isLoopInvariant(SplatValue)) { 4453a393728a62122d7009d8e2cbe52a221874e576aChris Lattner // Keep and use SplatValue. 4463a393728a62122d7009d8e2cbe52a221874e576aChris Lattner PatternValue = 0; 4473a393728a62122d7009d8e2cbe52a221874e576aChris Lattner } else if (TLI->has(LibFunc::memset_pattern16) && 4483a393728a62122d7009d8e2cbe52a221874e576aChris Lattner (PatternValue = getMemSetPatternValue(StoredVal, *TD))) { 4493a393728a62122d7009d8e2cbe52a221874e576aChris Lattner // It looks like we can use PatternValue! 4503a393728a62122d7009d8e2cbe52a221874e576aChris Lattner SplatValue = 0; 4513a393728a62122d7009d8e2cbe52a221874e576aChris Lattner } else { 4523a393728a62122d7009d8e2cbe52a221874e576aChris Lattner // Otherwise, this isn't an idiom we can transform. For example, we can't 4533a393728a62122d7009d8e2cbe52a221874e576aChris Lattner // do anything with a 3-byte store, for example. 454bafa117e8f2e3532f391227ebc9d4513b17edbadChris Lattner return false; 4553a393728a62122d7009d8e2cbe52a221874e576aChris Lattner } 4563a393728a62122d7009d8e2cbe52a221874e576aChris Lattner 457bafa117e8f2e3532f391227ebc9d4513b17edbadChris Lattner 458a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner // Okay, we have a strided store "p[i]" of a splattable value. We can turn 459a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner // this into a memset in the loop preheader now if we want. However, this 460a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner // would be unsafe to do if there is anything else in the loop that may read 461a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner // or write to the aliased location. Check for an alias. 462e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner if (mayLoopAccessLocation(DestPtr, AliasAnalysis::ModRef, 46363f9c3c49ac7011e6366fbec42716f3f70f1beeeChris Lattner CurLoop, BECount, 464e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner StoreSize, getAnalysis<AliasAnalysis>(), TheStore)) 465e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner return false; 466a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner 467a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner // Okay, everything looks good, insert the memset. 468a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner BasicBlock *Preheader = CurLoop->getLoopPreheader(); 469a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner 470a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner IRBuilder<> Builder(Preheader->getTerminator()); 471a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner 472a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner // The trip count of the loop and the base pointer of the addrec SCEV is 473a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner // guaranteed to be loop invariant, which means that it should dominate the 474a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner // header. Just insert code for it in the preheader. 475a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner SCEVExpander Expander(*SE); 476a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner 477e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner unsigned AddrSpace = cast<PointerType>(DestPtr->getType())->getAddressSpace(); 478a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner Value *BasePtr = 479a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner Expander.expandCodeFor(Ev->getStart(), Builder.getInt8PtrTy(AddrSpace), 480a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner Preheader->getTerminator()); 481a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner 482a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner // The # stored bytes is (BECount+1)*Size. Expand the trip count out to 483a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner // pointer size if it isn't already. 4843a393728a62122d7009d8e2cbe52a221874e576aChris Lattner const Type *IntPtr = TD->getIntPtrType(DestPtr->getContext()); 4857c90b90f4e9b0c421f0e45d7de03f6edce113a90Chris Lattner BECount = SE->getTruncateOrZeroExtend(BECount, IntPtr); 486a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner 487a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner const SCEV *NumBytesS = SE->getAddExpr(BECount, SE->getConstant(IntPtr, 1), 4887c90b90f4e9b0c421f0e45d7de03f6edce113a90Chris Lattner true /*no unsigned overflow*/); 489a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner if (StoreSize != 1) 490a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner NumBytesS = SE->getMulExpr(NumBytesS, SE->getConstant(IntPtr, StoreSize), 4917c90b90f4e9b0c421f0e45d7de03f6edce113a90Chris Lattner true /*no unsigned overflow*/); 492a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner 493a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner Value *NumBytes = 494a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner Expander.expandCodeFor(NumBytesS, IntPtr, Preheader->getTerminator()); 495a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner 4963a393728a62122d7009d8e2cbe52a221874e576aChris Lattner Value *NewCall; 4973a393728a62122d7009d8e2cbe52a221874e576aChris Lattner if (SplatValue) 4983a393728a62122d7009d8e2cbe52a221874e576aChris Lattner NewCall = Builder.CreateMemSet(BasePtr, SplatValue,NumBytes,StoreAlignment); 4993a393728a62122d7009d8e2cbe52a221874e576aChris Lattner else { 5003a393728a62122d7009d8e2cbe52a221874e576aChris Lattner Module *M = TheStore->getParent()->getParent()->getParent(); 5013a393728a62122d7009d8e2cbe52a221874e576aChris Lattner Value *MSP = M->getOrInsertFunction("memset_pattern16", 5023a393728a62122d7009d8e2cbe52a221874e576aChris Lattner Builder.getVoidTy(), 5033a393728a62122d7009d8e2cbe52a221874e576aChris Lattner Builder.getInt8PtrTy(), 5043a393728a62122d7009d8e2cbe52a221874e576aChris Lattner Builder.getInt8PtrTy(), IntPtr, 5053a393728a62122d7009d8e2cbe52a221874e576aChris Lattner (void*)0); 5063a393728a62122d7009d8e2cbe52a221874e576aChris Lattner 5073a393728a62122d7009d8e2cbe52a221874e576aChris Lattner // Otherwise we should form a memset_pattern16. PatternValue is known to be 5083a393728a62122d7009d8e2cbe52a221874e576aChris Lattner // an constant array of 16-bytes. Plop the value into a mergable global. 5093a393728a62122d7009d8e2cbe52a221874e576aChris Lattner GlobalVariable *GV = new GlobalVariable(*M, PatternValue->getType(), true, 5103a393728a62122d7009d8e2cbe52a221874e576aChris Lattner GlobalValue::InternalLinkage, 5113a393728a62122d7009d8e2cbe52a221874e576aChris Lattner PatternValue, ".memset_pattern"); 5123a393728a62122d7009d8e2cbe52a221874e576aChris Lattner GV->setUnnamedAddr(true); // Ok to merge these. 5133a393728a62122d7009d8e2cbe52a221874e576aChris Lattner GV->setAlignment(16); 51480e8b506b8134d63dc3cb6211cccc34be4b19d40Chris Lattner Value *PatternPtr = ConstantExpr::getBitCast(GV, Builder.getInt8PtrTy()); 5153a393728a62122d7009d8e2cbe52a221874e576aChris Lattner NewCall = Builder.CreateCall3(MSP, BasePtr, PatternPtr, NumBytes); 5163a393728a62122d7009d8e2cbe52a221874e576aChris Lattner } 517a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner 518a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner DEBUG(dbgs() << " Formed memset: " << *NewCall << "\n" 519e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner << " from store to: " << *Ev << " at: " << *TheStore << "\n"); 5207922d34b6073712cb62f7d4d74810509c19a84dfDuncan Sands (void)NewCall; 521a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner 5229f39188def2b4102817945522fac1209083efa06Chris Lattner // Okay, the memset has been formed. Zap the original store and anything that 5239f39188def2b4102817945522fac1209083efa06Chris Lattner // feeds into it. 524e41d3c015ce5cafde305d9a6d9baaae1c41bf46aChris Lattner DeleteDeadInstruction(TheStore, *SE); 5254ce31fb57412b16cd61337ba41c60112dfbecfb6Chris Lattner ++NumMemSet; 526a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner return true; 527a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner} 528a92ff91a967c63a2395a34c9e8331a7d50d6ab10Chris Lattner 529e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner/// processLoopStoreOfLoopLoad - We see a strided store whose value is a 530e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner/// same-strided load. 531e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattnerbool LoopIdiomRecognize:: 532e2c43920919c6fe376613d1d8331897dc1ba3d57Chris LattnerprocessLoopStoreOfLoopLoad(StoreInst *SI, unsigned StoreSize, 533e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner const SCEVAddRecExpr *StoreEv, 534e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner const SCEVAddRecExpr *LoadEv, 535e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner const SCEV *BECount) { 536c19175c9d8d3c2663b682a7fe34bb22da370d5c1Chris Lattner // If we're not allowed to form memcpy, we fail. 537c19175c9d8d3c2663b682a7fe34bb22da370d5c1Chris Lattner if (!TLI->has(LibFunc::memcpy)) 538c19175c9d8d3c2663b682a7fe34bb22da370d5c1Chris Lattner return false; 539c19175c9d8d3c2663b682a7fe34bb22da370d5c1Chris Lattner 540e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner LoadInst *LI = cast<LoadInst>(SI->getValueOperand()); 541e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner 542e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner // Okay, we have a strided store "p[i]" of a loaded value. We can turn 543bdce5720ad878259544e6a4e3621dac32cf2d134Chris Lattner // this into a memcpy in the loop preheader now if we want. However, this 544e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner // would be unsafe to do if there is anything else in the loop that may read 54563f9c3c49ac7011e6366fbec42716f3f70f1beeeChris Lattner // or write to the stored location (including the load feeding the stores). 546e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner // Check for an alias. 54763f9c3c49ac7011e6366fbec42716f3f70f1beeeChris Lattner if (mayLoopAccessLocation(SI->getPointerOperand(), AliasAnalysis::ModRef, 54863f9c3c49ac7011e6366fbec42716f3f70f1beeeChris Lattner CurLoop, BECount, StoreSize, 54963f9c3c49ac7011e6366fbec42716f3f70f1beeeChris Lattner getAnalysis<AliasAnalysis>(), SI)) 55063f9c3c49ac7011e6366fbec42716f3f70f1beeeChris Lattner return false; 55163f9c3c49ac7011e6366fbec42716f3f70f1beeeChris Lattner 55263f9c3c49ac7011e6366fbec42716f3f70f1beeeChris Lattner // For a memcpy, we have to make sure that the input array is not being 55363f9c3c49ac7011e6366fbec42716f3f70f1beeeChris Lattner // mutated by the loop. 55463f9c3c49ac7011e6366fbec42716f3f70f1beeeChris Lattner if (mayLoopAccessLocation(LI->getPointerOperand(), AliasAnalysis::Mod, 55563f9c3c49ac7011e6366fbec42716f3f70f1beeeChris Lattner CurLoop, BECount, StoreSize, 55663f9c3c49ac7011e6366fbec42716f3f70f1beeeChris Lattner getAnalysis<AliasAnalysis>(), SI)) 557e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner return false; 558e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner 559e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner // Okay, everything looks good, insert the memcpy. 560e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner BasicBlock *Preheader = CurLoop->getLoopPreheader(); 561e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner 562e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner IRBuilder<> Builder(Preheader->getTerminator()); 563e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner 564e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner // The trip count of the loop and the base pointer of the addrec SCEV is 565e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner // guaranteed to be loop invariant, which means that it should dominate the 566e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner // header. Just insert code for it in the preheader. 567e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner SCEVExpander Expander(*SE); 568e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner 569e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner Value *LoadBasePtr = 570e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner Expander.expandCodeFor(LoadEv->getStart(), 571e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner Builder.getInt8PtrTy(LI->getPointerAddressSpace()), 572e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner Preheader->getTerminator()); 573e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner Value *StoreBasePtr = 574e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner Expander.expandCodeFor(StoreEv->getStart(), 575e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner Builder.getInt8PtrTy(SI->getPointerAddressSpace()), 576e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner Preheader->getTerminator()); 577e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner 578e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner // The # stored bytes is (BECount+1)*Size. Expand the trip count out to 579e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner // pointer size if it isn't already. 580e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner const Type *IntPtr = TD->getIntPtrType(SI->getContext()); 5817c90b90f4e9b0c421f0e45d7de03f6edce113a90Chris Lattner BECount = SE->getTruncateOrZeroExtend(BECount, IntPtr); 582e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner 583e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner const SCEV *NumBytesS = SE->getAddExpr(BECount, SE->getConstant(IntPtr, 1), 5847c90b90f4e9b0c421f0e45d7de03f6edce113a90Chris Lattner true /*no unsigned overflow*/); 585e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner if (StoreSize != 1) 586e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner NumBytesS = SE->getMulExpr(NumBytesS, SE->getConstant(IntPtr, StoreSize), 5877c90b90f4e9b0c421f0e45d7de03f6edce113a90Chris Lattner true /*no unsigned overflow*/); 588e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner 589e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner Value *NumBytes = 590e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner Expander.expandCodeFor(NumBytesS, IntPtr, Preheader->getTerminator()); 591e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner 592e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner Value *NewCall = 593e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner Builder.CreateMemCpy(StoreBasePtr, LoadBasePtr, NumBytes, 594e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner std::min(SI->getAlignment(), LI->getAlignment())); 595e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner 596e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner DEBUG(dbgs() << " Formed memcpy: " << *NewCall << "\n" 597e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner << " from load ptr=" << *LoadEv << " at: " << *LI << "\n" 598e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner << " from store ptr=" << *StoreEv << " at: " << *SI << "\n"); 599e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner (void)NewCall; 600e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner 601e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner // Okay, the memset has been formed. Zap the original store and anything that 602e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner // feeds into it. 603e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner DeleteDeadInstruction(SI, *SE); 6044ce31fb57412b16cd61337ba41c60112dfbecfb6Chris Lattner ++NumMemCpy; 605e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner return true; 606e2c43920919c6fe376613d1d8331897dc1ba3d57Chris Lattner} 607