IndVarSimplify.cpp revision 20151da8c38287b9fa181e9fef93f70bc2cd9fd2
16148c02591bd83da7b957589c4bbf6f9720d503fChris Lattner//===- IndVarSimplify.cpp - Induction Variable Elimination ----------------===// 2fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukman// 3b576c94c15af9a440f69d9d03c2afead7971118cJohn Criswell// The LLVM Compiler Infrastructure 4b576c94c15af9a440f69d9d03c2afead7971118cJohn Criswell// 54ee451de366474b9c228b4e5fa573795a715216dChris Lattner// This file is distributed under the University of Illinois Open Source 64ee451de366474b9c228b4e5fa573795a715216dChris Lattner// License. See LICENSE.TXT for details. 7fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukman// 8b576c94c15af9a440f69d9d03c2afead7971118cJohn Criswell//===----------------------------------------------------------------------===// 96148c02591bd83da7b957589c4bbf6f9720d503fChris Lattner// 1040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// This transformation analyzes and transforms the induction variables (and 1140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// computations derived from them) into simpler forms suitable for subsequent 1240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// analysis and transformation. 1340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// 144b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick// Additionally, unless -disable-iv-rewrite is on, this transformation makes the 154b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick// following changes to each loop with an identifiable induction variable: 1640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// 1. All loops are transformed to have a SINGLE canonical induction variable 1740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// which starts at zero and steps by one. 1840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// 2. The canonical induction variable is guaranteed to be the first PHI node 1940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// in the loop header block. 20ea73f3c2e14d84bb4cb07bd6a1a3d7915f3aff83Dan Gohman// 3. The canonical induction variable is guaranteed to be in a wide enough 21ea73f3c2e14d84bb4cb07bd6a1a3d7915f3aff83Dan Gohman// type so that IV expressions need not be (directly) zero-extended or 22ea73f3c2e14d84bb4cb07bd6a1a3d7915f3aff83Dan Gohman// sign-extended. 23ea73f3c2e14d84bb4cb07bd6a1a3d7915f3aff83Dan Gohman// 4. Any pointer arithmetic recurrences are raised to use array subscripts. 2440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// 2540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// If the trip count of a loop is computable, this pass also makes the following 2640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// changes: 2740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// 1. The exit condition for the loop is canonicalized to compare the 2840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// induction value against the exit value. This turns loops like: 2940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// 'for (i = 7; i*i < 1000; ++i)' into 'for (i = 0; i != 25; ++i)' 3040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// 2. Any use outside of the loop of an expression derived from the indvar 3140bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// is changed to compute the derived value outside of the loop, eliminating 3240bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// the dependence on the exit value of the induction variable. If the only 3340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// purpose of the loop is to compute the exit value of some derived 3440bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// expression, this transformation will make the loop dead. 3540bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// 3640bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner// This transformation should be followed by strength reduction after all of the 37c2c4cbf7b3a0229cf1804ca9d7c18113f75bab46Dan Gohman// desired loop transformations have been performed. 386148c02591bd83da7b957589c4bbf6f9720d503fChris Lattner// 396148c02591bd83da7b957589c4bbf6f9720d503fChris Lattner//===----------------------------------------------------------------------===// 406148c02591bd83da7b957589c4bbf6f9720d503fChris Lattner 410e5f499638c8d277b9dc4a4385712177c53b5681Chris Lattner#define DEBUG_TYPE "indvars" 42022103b3f33febb7e54b8fdf2c9bc461eea78cbaChris Lattner#include "llvm/Transforms/Scalar.h" 4340bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner#include "llvm/BasicBlock.h" 4459fdaeeae8f183e18bb6ad5c382ca23e28e6aaf6Chris Lattner#include "llvm/Constants.h" 4518b3c97bc773b24a66eb779e85da1820b0f16b31Chris Lattner#include "llvm/Instructions.h" 467b9f6b1b21bc0b06f3c72beae51e9db631319503Devang Patel#include "llvm/IntrinsicInst.h" 47d672ecb0178c6247a5eaa5b0fb0c3b23cd25bd7cOwen Anderson#include "llvm/LLVMContext.h" 4840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner#include "llvm/Type.h" 4981db61a2e6d3c95a2738c3559a108e05e9d7a05aDan Gohman#include "llvm/Analysis/Dominators.h" 5081db61a2e6d3c95a2738c3559a108e05e9d7a05aDan Gohman#include "llvm/Analysis/IVUsers.h" 5136f891bdf6cf38fcc655a0930ca18664e18518d4Nate Begeman#include "llvm/Analysis/ScalarEvolutionExpander.h" 5247df12d80db90e125e9f2ff764286ee11665476dJohn Criswell#include "llvm/Analysis/LoopInfo.h" 535ee99979065d75605d150d7e567e4351024aae8fDevang Patel#include "llvm/Analysis/LoopPass.h" 54455889aa79e3463a4b0f2161e3d9d72a683268b6Chris Lattner#include "llvm/Support/CFG.h" 5556caa098085977c14cfab39d92c7dfa15dde0d90Andrew Trick#include "llvm/Support/CommandLine.h" 56ee4f13a9046c380725cdeab62d57722db375c473Chris Lattner#include "llvm/Support/Debug.h" 57bdff548e4dd577a72094d57b282de4e765643b96Chris Lattner#include "llvm/Support/raw_ostream.h" 5847df12d80db90e125e9f2ff764286ee11665476dJohn Criswell#include "llvm/Transforms/Utils/Local.h" 5981db61a2e6d3c95a2738c3559a108e05e9d7a05aDan Gohman#include "llvm/Transforms/Utils/BasicBlockUtils.h" 604b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick#include "llvm/Transforms/Utils/SimplifyIndVar.h" 6137da40875873d70b83dc08b2803052bec9b68886Andrew Trick#include "llvm/Target/TargetData.h" 62037d1c0c7e01cefeff7e538682c9a1e536e14030Andrew Trick#include "llvm/ADT/DenseMap.h" 63a54b7cbd452b3adb2f51346140d996b29c2cdb30Reid Spencer#include "llvm/ADT/SmallVector.h" 64551ccae044b0ff658fe629dd67edd5ffe75d10e8Reid Spencer#include "llvm/ADT/Statistic.h" 6547df12d80db90e125e9f2ff764286ee11665476dJohn Criswellusing namespace llvm; 66d0fde30ce850b78371fd1386338350591f9ff494Brian Gaeke 672fabd464ae9fd33f068066e3fc3d0caa7ea2279dAndrew TrickSTATISTIC(NumRemoved , "Number of aux indvars removed"); 682fabd464ae9fd33f068066e3fc3d0caa7ea2279dAndrew TrickSTATISTIC(NumWidened , "Number of indvars widened"); 692fabd464ae9fd33f068066e3fc3d0caa7ea2279dAndrew TrickSTATISTIC(NumInserted , "Number of canonical indvars added"); 702fabd464ae9fd33f068066e3fc3d0caa7ea2279dAndrew TrickSTATISTIC(NumReplaced , "Number of exit values replaced"); 712fabd464ae9fd33f068066e3fc3d0caa7ea2279dAndrew TrickSTATISTIC(NumLFTR , "Number of loop exit tests replaced"); 722fabd464ae9fd33f068066e3fc3d0caa7ea2279dAndrew TrickSTATISTIC(NumElimExt , "Number of IV sign/zero extends eliminated"); 73037d1c0c7e01cefeff7e538682c9a1e536e14030Andrew TrickSTATISTIC(NumElimIV , "Number of congruent IVs eliminated"); 743324e718bc9ac2ede08a14c325848b576849542bChris Lattner 754b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Tricknamespace llvm { 764b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick cl::opt<bool> DisableIVRewrite( 774b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick "disable-iv-rewrite", cl::Hidden, 784b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick cl::desc("Disable canonical induction variable rewriting")); 7975ebc0ec2019f391648d3bc3bac6f6da11cfbabdAndrew Trick 8075ebc0ec2019f391648d3bc3bac6f6da11cfbabdAndrew Trick // Trip count verification can be enabled by default under NDEBUG if we 8175ebc0ec2019f391648d3bc3bac6f6da11cfbabdAndrew Trick // implement a strong expression equivalence checker in SCEV. Until then, we 8275ebc0ec2019f391648d3bc3bac6f6da11cfbabdAndrew Trick // use the verify-indvars flag, which may assert in some cases. 8375ebc0ec2019f391648d3bc3bac6f6da11cfbabdAndrew Trick cl::opt<bool> VerifyIndvars( 8475ebc0ec2019f391648d3bc3bac6f6da11cfbabdAndrew Trick "verify-indvars", cl::Hidden, 8575ebc0ec2019f391648d3bc3bac6f6da11cfbabdAndrew Trick cl::desc("Verify the ScalarEvolution result after running indvars")); 864b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick} 8737da40875873d70b83dc08b2803052bec9b68886Andrew Trick 88fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick// Temporary flag for use with -disable-iv-rewrite to force a canonical IV for 89fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick// LFTR purposes. 90fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trickstatic cl::opt<bool> ForceLFTR( 91fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick "force-lftr", cl::Hidden, 92fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick cl::desc("Enable forced linear function test replacement")); 93fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick 940e5f499638c8d277b9dc4a4385712177c53b5681Chris Lattnernamespace { 953e8b6631e67e01e4960a7ba4668a50c596607473Chris Lattner class IndVarSimplify : public LoopPass { 9681db61a2e6d3c95a2738c3559a108e05e9d7a05aDan Gohman IVUsers *IU; 9740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner LoopInfo *LI; 9840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner ScalarEvolution *SE; 99de53dc03f5c1549f3176e979bbeeac965dfa5cbcDan Gohman DominatorTree *DT; 10037da40875873d70b83dc08b2803052bec9b68886Andrew Trick TargetData *TD; 1012fabd464ae9fd33f068066e3fc3d0caa7ea2279dAndrew Trick 102b12a754cce0c1d5542af605203a47820edba454dAndrew Trick SmallVector<WeakVH, 16> DeadInsts; 10315cad759fe2048ac5eb137c6bb0ab7287538677eChris Lattner bool Changed; 1043324e718bc9ac2ede08a14c325848b576849542bChris Lattner public: 105794fd75c67a2cdc128d67342c6d88a504d186896Devang Patel 1065668cf77a77493ec9f2a9b33f08125e885c8e4cfDan Gohman static char ID; // Pass identification, replacement for typeid 1072fabd464ae9fd33f068066e3fc3d0caa7ea2279dAndrew Trick IndVarSimplify() : LoopPass(ID), IU(0), LI(0), SE(0), DT(0), TD(0), 10815832f61775040995bb8aa6056176425bc2c9088Andrew Trick Changed(false) { 109081c34b725980f995be9080eaec24cd3dfaaf065Owen Anderson initializeIndVarSimplifyPass(*PassRegistry::getPassRegistry()); 110081c34b725980f995be9080eaec24cd3dfaaf065Owen Anderson } 111794fd75c67a2cdc128d67342c6d88a504d186896Devang Patel 1125668cf77a77493ec9f2a9b33f08125e885c8e4cfDan Gohman virtual bool runOnLoop(Loop *L, LPPassManager &LPM); 11360f8a63e2502d57e879bf52a4a48505b74fa9716Dan Gohman 1145668cf77a77493ec9f2a9b33f08125e885c8e4cfDan Gohman virtual void getAnalysisUsage(AnalysisUsage &AU) const { 1155668cf77a77493ec9f2a9b33f08125e885c8e4cfDan Gohman AU.addRequired<DominatorTree>(); 1165668cf77a77493ec9f2a9b33f08125e885c8e4cfDan Gohman AU.addRequired<LoopInfo>(); 1175668cf77a77493ec9f2a9b33f08125e885c8e4cfDan Gohman AU.addRequired<ScalarEvolution>(); 1185668cf77a77493ec9f2a9b33f08125e885c8e4cfDan Gohman AU.addRequiredID(LoopSimplifyID); 1195668cf77a77493ec9f2a9b33f08125e885c8e4cfDan Gohman AU.addRequiredID(LCSSAID); 12056caa098085977c14cfab39d92c7dfa15dde0d90Andrew Trick if (!DisableIVRewrite) 12156caa098085977c14cfab39d92c7dfa15dde0d90Andrew Trick AU.addRequired<IVUsers>(); 1225668cf77a77493ec9f2a9b33f08125e885c8e4cfDan Gohman AU.addPreserved<ScalarEvolution>(); 1235668cf77a77493ec9f2a9b33f08125e885c8e4cfDan Gohman AU.addPreservedID(LoopSimplifyID); 1245668cf77a77493ec9f2a9b33f08125e885c8e4cfDan Gohman AU.addPreservedID(LCSSAID); 1252fabd464ae9fd33f068066e3fc3d0caa7ea2279dAndrew Trick if (!DisableIVRewrite) 1262fabd464ae9fd33f068066e3fc3d0caa7ea2279dAndrew Trick AU.addPreserved<IVUsers>(); 1275668cf77a77493ec9f2a9b33f08125e885c8e4cfDan Gohman AU.setPreservesCFG(); 1285668cf77a77493ec9f2a9b33f08125e885c8e4cfDan Gohman } 1293324e718bc9ac2ede08a14c325848b576849542bChris Lattner 13040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner private: 131037d1c0c7e01cefeff7e538682c9a1e536e14030Andrew Trick virtual void releaseMemory() { 132037d1c0c7e01cefeff7e538682c9a1e536e14030Andrew Trick DeadInsts.clear(); 133037d1c0c7e01cefeff7e538682c9a1e536e14030Andrew Trick } 134037d1c0c7e01cefeff7e538682c9a1e536e14030Andrew Trick 135b12a754cce0c1d5542af605203a47820edba454dAndrew Trick bool isValidRewrite(Value *FromVal, Value *ToVal); 1365ee99979065d75605d150d7e567e4351024aae8fDevang Patel 1371a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick void HandleFloatingPointIV(Loop *L, PHINode *PH); 1381a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick void RewriteNonIntegerIVs(Loop *L); 1391a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 1404b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick void SimplifyAndExtend(Loop *L, SCEVExpander &Rewriter, LPPassManager &LPM); 14106988bcf6a5c74e81cf7e76f06a686aa822ec00aAndrew Trick 142037d1c0c7e01cefeff7e538682c9a1e536e14030Andrew Trick void SimplifyCongruentIVs(Loop *L); 143037d1c0c7e01cefeff7e538682c9a1e536e14030Andrew Trick 1444b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick void RewriteLoopExitValues(Loop *L, SCEVExpander &Rewriter); 1454b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick 146454d26dc43207ec537d843229db6f5e6a302e23dDan Gohman void RewriteIVExpressions(Loop *L, SCEVExpander &Rewriter); 147d22a849282c45bbf7eb1734c274294d81e49e3a8Devang Patel 148fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick Value *LinearFunctionTestReplace(Loop *L, const SCEV *BackedgeTakenCount, 149fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick PHINode *IndVar, SCEVExpander &Rewriter); 15081db61a2e6d3c95a2738c3559a108e05e9d7a05aDan Gohman 1511a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick void SinkUnusedInvariants(Loop *L); 1523324e718bc9ac2ede08a14c325848b576849542bChris Lattner }; 1535e76140536ba66fadeced1cd892f79616f407e3cChris Lattner} 154394437ff7eaccfe1de92fe14d0022ca0addf3e41Chris Lattner 155844731a7f1909f55935e3514c9e713a62d67662eDan Gohmanchar IndVarSimplify::ID = 0; 1562ab36d350293c77fc8941ce1023e4899df7e3a82Owen AndersonINITIALIZE_PASS_BEGIN(IndVarSimplify, "indvars", 15737da40875873d70b83dc08b2803052bec9b68886Andrew Trick "Induction Variable Simplification", false, false) 1582ab36d350293c77fc8941ce1023e4899df7e3a82Owen AndersonINITIALIZE_PASS_DEPENDENCY(DominatorTree) 1592ab36d350293c77fc8941ce1023e4899df7e3a82Owen AndersonINITIALIZE_PASS_DEPENDENCY(LoopInfo) 1602ab36d350293c77fc8941ce1023e4899df7e3a82Owen AndersonINITIALIZE_PASS_DEPENDENCY(ScalarEvolution) 1612ab36d350293c77fc8941ce1023e4899df7e3a82Owen AndersonINITIALIZE_PASS_DEPENDENCY(LoopSimplify) 1622ab36d350293c77fc8941ce1023e4899df7e3a82Owen AndersonINITIALIZE_PASS_DEPENDENCY(LCSSA) 1632ab36d350293c77fc8941ce1023e4899df7e3a82Owen AndersonINITIALIZE_PASS_DEPENDENCY(IVUsers) 1642ab36d350293c77fc8941ce1023e4899df7e3a82Owen AndersonINITIALIZE_PASS_END(IndVarSimplify, "indvars", 16537da40875873d70b83dc08b2803052bec9b68886Andrew Trick "Induction Variable Simplification", false, false) 166844731a7f1909f55935e3514c9e713a62d67662eDan Gohman 167394f0441e06dafca29f0752cf400990a5b8fe4b1Daniel DunbarPass *llvm::createIndVarSimplifyPass() { 1683324e718bc9ac2ede08a14c325848b576849542bChris Lattner return new IndVarSimplify(); 169394437ff7eaccfe1de92fe14d0022ca0addf3e41Chris Lattner} 170394437ff7eaccfe1de92fe14d0022ca0addf3e41Chris Lattner 171b12a754cce0c1d5542af605203a47820edba454dAndrew Trick/// isValidRewrite - Return true if the SCEV expansion generated by the 172b12a754cce0c1d5542af605203a47820edba454dAndrew Trick/// rewriter can replace the original value. SCEV guarantees that it 173b12a754cce0c1d5542af605203a47820edba454dAndrew Trick/// produces the same value, but the way it is produced may be illegal IR. 174b12a754cce0c1d5542af605203a47820edba454dAndrew Trick/// Ideally, this function will only be called for verification. 175b12a754cce0c1d5542af605203a47820edba454dAndrew Trickbool IndVarSimplify::isValidRewrite(Value *FromVal, Value *ToVal) { 176b12a754cce0c1d5542af605203a47820edba454dAndrew Trick // If an SCEV expression subsumed multiple pointers, its expansion could 177b12a754cce0c1d5542af605203a47820edba454dAndrew Trick // reassociate the GEP changing the base pointer. This is illegal because the 178b12a754cce0c1d5542af605203a47820edba454dAndrew Trick // final address produced by a GEP chain must be inbounds relative to its 179b12a754cce0c1d5542af605203a47820edba454dAndrew Trick // underlying object. Otherwise basic alias analysis, among other things, 180b12a754cce0c1d5542af605203a47820edba454dAndrew Trick // could fail in a dangerous way. Ultimately, SCEV will be improved to avoid 181b12a754cce0c1d5542af605203a47820edba454dAndrew Trick // producing an expression involving multiple pointers. Until then, we must 182b12a754cce0c1d5542af605203a47820edba454dAndrew Trick // bail out here. 183b12a754cce0c1d5542af605203a47820edba454dAndrew Trick // 184b12a754cce0c1d5542af605203a47820edba454dAndrew Trick // Retrieve the pointer operand of the GEP. Don't use GetUnderlyingObject 185b12a754cce0c1d5542af605203a47820edba454dAndrew Trick // because it understands lcssa phis while SCEV does not. 186b12a754cce0c1d5542af605203a47820edba454dAndrew Trick Value *FromPtr = FromVal; 187b12a754cce0c1d5542af605203a47820edba454dAndrew Trick Value *ToPtr = ToVal; 188b12a754cce0c1d5542af605203a47820edba454dAndrew Trick if (GEPOperator *GEP = dyn_cast<GEPOperator>(FromVal)) { 189b12a754cce0c1d5542af605203a47820edba454dAndrew Trick FromPtr = GEP->getPointerOperand(); 190b12a754cce0c1d5542af605203a47820edba454dAndrew Trick } 191b12a754cce0c1d5542af605203a47820edba454dAndrew Trick if (GEPOperator *GEP = dyn_cast<GEPOperator>(ToVal)) { 192b12a754cce0c1d5542af605203a47820edba454dAndrew Trick ToPtr = GEP->getPointerOperand(); 193b12a754cce0c1d5542af605203a47820edba454dAndrew Trick } 194b12a754cce0c1d5542af605203a47820edba454dAndrew Trick if (FromPtr != FromVal || ToPtr != ToVal) { 195b12a754cce0c1d5542af605203a47820edba454dAndrew Trick // Quickly check the common case 196b12a754cce0c1d5542af605203a47820edba454dAndrew Trick if (FromPtr == ToPtr) 197b12a754cce0c1d5542af605203a47820edba454dAndrew Trick return true; 198b12a754cce0c1d5542af605203a47820edba454dAndrew Trick 199b12a754cce0c1d5542af605203a47820edba454dAndrew Trick // SCEV may have rewritten an expression that produces the GEP's pointer 200b12a754cce0c1d5542af605203a47820edba454dAndrew Trick // operand. That's ok as long as the pointer operand has the same base 201b12a754cce0c1d5542af605203a47820edba454dAndrew Trick // pointer. Unlike GetUnderlyingObject(), getPointerBase() will find the 202b12a754cce0c1d5542af605203a47820edba454dAndrew Trick // base of a recurrence. This handles the case in which SCEV expansion 203b12a754cce0c1d5542af605203a47820edba454dAndrew Trick // converts a pointer type recurrence into a nonrecurrent pointer base 204b12a754cce0c1d5542af605203a47820edba454dAndrew Trick // indexed by an integer recurrence. 205b12a754cce0c1d5542af605203a47820edba454dAndrew Trick const SCEV *FromBase = SE->getPointerBase(SE->getSCEV(FromPtr)); 206b12a754cce0c1d5542af605203a47820edba454dAndrew Trick const SCEV *ToBase = SE->getPointerBase(SE->getSCEV(ToPtr)); 207b12a754cce0c1d5542af605203a47820edba454dAndrew Trick if (FromBase == ToBase) 208b12a754cce0c1d5542af605203a47820edba454dAndrew Trick return true; 209b12a754cce0c1d5542af605203a47820edba454dAndrew Trick 210b12a754cce0c1d5542af605203a47820edba454dAndrew Trick DEBUG(dbgs() << "INDVARS: GEP rewrite bail out " 211b12a754cce0c1d5542af605203a47820edba454dAndrew Trick << *FromBase << " != " << *ToBase << "\n"); 212b12a754cce0c1d5542af605203a47820edba454dAndrew Trick 213b12a754cce0c1d5542af605203a47820edba454dAndrew Trick return false; 214b12a754cce0c1d5542af605203a47820edba454dAndrew Trick } 215b12a754cce0c1d5542af605203a47820edba454dAndrew Trick return true; 216b12a754cce0c1d5542af605203a47820edba454dAndrew Trick} 217b12a754cce0c1d5542af605203a47820edba454dAndrew Trick 21886c98145b268a0d10e062792f98bc8eea6b639b4Andrew Trick/// Determine the insertion point for this user. By default, insert immediately 21986c98145b268a0d10e062792f98bc8eea6b639b4Andrew Trick/// before the user. SCEVExpander or LICM will hoist loop invariants out of the 22086c98145b268a0d10e062792f98bc8eea6b639b4Andrew Trick/// loop. For PHI nodes, there may be multiple uses, so compute the nearest 22186c98145b268a0d10e062792f98bc8eea6b639b4Andrew Trick/// common dominator for the incoming blocks. 22286c98145b268a0d10e062792f98bc8eea6b639b4Andrew Trickstatic Instruction *getInsertPointForUses(Instruction *User, Value *Def, 22386c98145b268a0d10e062792f98bc8eea6b639b4Andrew Trick DominatorTree *DT) { 22486c98145b268a0d10e062792f98bc8eea6b639b4Andrew Trick PHINode *PHI = dyn_cast<PHINode>(User); 22586c98145b268a0d10e062792f98bc8eea6b639b4Andrew Trick if (!PHI) 22686c98145b268a0d10e062792f98bc8eea6b639b4Andrew Trick return User; 22786c98145b268a0d10e062792f98bc8eea6b639b4Andrew Trick 22886c98145b268a0d10e062792f98bc8eea6b639b4Andrew Trick Instruction *InsertPt = 0; 22986c98145b268a0d10e062792f98bc8eea6b639b4Andrew Trick for (unsigned i = 0, e = PHI->getNumIncomingValues(); i != e; ++i) { 23086c98145b268a0d10e062792f98bc8eea6b639b4Andrew Trick if (PHI->getIncomingValue(i) != Def) 23186c98145b268a0d10e062792f98bc8eea6b639b4Andrew Trick continue; 23286c98145b268a0d10e062792f98bc8eea6b639b4Andrew Trick 23386c98145b268a0d10e062792f98bc8eea6b639b4Andrew Trick BasicBlock *InsertBB = PHI->getIncomingBlock(i); 23486c98145b268a0d10e062792f98bc8eea6b639b4Andrew Trick if (!InsertPt) { 23586c98145b268a0d10e062792f98bc8eea6b639b4Andrew Trick InsertPt = InsertBB->getTerminator(); 23686c98145b268a0d10e062792f98bc8eea6b639b4Andrew Trick continue; 23786c98145b268a0d10e062792f98bc8eea6b639b4Andrew Trick } 23886c98145b268a0d10e062792f98bc8eea6b639b4Andrew Trick InsertBB = DT->findNearestCommonDominator(InsertPt->getParent(), InsertBB); 23986c98145b268a0d10e062792f98bc8eea6b639b4Andrew Trick InsertPt = InsertBB->getTerminator(); 24086c98145b268a0d10e062792f98bc8eea6b639b4Andrew Trick } 24186c98145b268a0d10e062792f98bc8eea6b639b4Andrew Trick assert(InsertPt && "Missing phi operand"); 242626f52d43df67c29b156f524551327d741ef80bfJay Foad assert((!isa<Instruction>(Def) || 243626f52d43df67c29b156f524551327d741ef80bfJay Foad DT->dominates(cast<Instruction>(Def), InsertPt)) && 24486c98145b268a0d10e062792f98bc8eea6b639b4Andrew Trick "def does not dominate all uses"); 24586c98145b268a0d10e062792f98bc8eea6b639b4Andrew Trick return InsertPt; 24686c98145b268a0d10e062792f98bc8eea6b639b4Andrew Trick} 24786c98145b268a0d10e062792f98bc8eea6b639b4Andrew Trick 2481a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick//===----------------------------------------------------------------------===// 2491a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick// RewriteNonIntegerIVs and helpers. Prefer integer IVs. 2501a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick//===----------------------------------------------------------------------===// 2514dfdf242c1917e98f407818eb5b68ae0b4678f26Andrew Trick 2521a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick/// ConvertToSInt - Convert APF to an integer, if possible. 2531a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trickstatic bool ConvertToSInt(const APFloat &APF, int64_t &IntVal) { 2541a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick bool isExact = false; 2551a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick if (&APF.getSemantics() == &APFloat::PPCDoubleDouble) 2564dfdf242c1917e98f407818eb5b68ae0b4678f26Andrew Trick return false; 2571a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // See if we can convert this to an int64_t 2581a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick uint64_t UIntVal; 2591a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick if (APF.convertToInteger(&UIntVal, 64, true, APFloat::rmTowardZero, 2601a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick &isExact) != APFloat::opOK || !isExact) 2614dfdf242c1917e98f407818eb5b68ae0b4678f26Andrew Trick return false; 2621a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick IntVal = UIntVal; 2634dfdf242c1917e98f407818eb5b68ae0b4678f26Andrew Trick return true; 2644dfdf242c1917e98f407818eb5b68ae0b4678f26Andrew Trick} 2654dfdf242c1917e98f407818eb5b68ae0b4678f26Andrew Trick 2661a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick/// HandleFloatingPointIV - If the loop has floating induction variable 2671a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick/// then insert corresponding integer induction variable if possible. 2681a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick/// For example, 2691a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick/// for(double i = 0; i < 10000; ++i) 2701a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick/// bar(i) 2711a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick/// is converted into 2721a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick/// for(int i = 0; i < 10000; ++i) 2731a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick/// bar((double)i); 27403d3d3b361800f28c75d3386978d22e6d57744b7Andrew Trick/// 2751a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trickvoid IndVarSimplify::HandleFloatingPointIV(Loop *L, PHINode *PN) { 2761a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick unsigned IncomingEdge = L->contains(PN->getIncomingBlock(0)); 2771a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick unsigned BackEdge = IncomingEdge^1; 27803d3d3b361800f28c75d3386978d22e6d57744b7Andrew Trick 2791a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // Check incoming value. 2801a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick ConstantFP *InitValueVal = 2811a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick dyn_cast<ConstantFP>(PN->getIncomingValue(IncomingEdge)); 28203d3d3b361800f28c75d3386978d22e6d57744b7Andrew Trick 2831a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick int64_t InitValue; 2841a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick if (!InitValueVal || !ConvertToSInt(InitValueVal->getValueAPF(), InitValue)) 2851a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick return; 28603d3d3b361800f28c75d3386978d22e6d57744b7Andrew Trick 2871a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // Check IV increment. Reject this PN if increment operation is not 2881a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // an add or increment value can not be represented by an integer. 2891a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick BinaryOperator *Incr = 2901a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick dyn_cast<BinaryOperator>(PN->getIncomingValue(BackEdge)); 2911a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick if (Incr == 0 || Incr->getOpcode() != Instruction::FAdd) return; 29203d3d3b361800f28c75d3386978d22e6d57744b7Andrew Trick 2931a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // If this is not an add of the PHI with a constantfp, or if the constant fp 2941a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // is not an integer, bail out. 2951a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick ConstantFP *IncValueVal = dyn_cast<ConstantFP>(Incr->getOperand(1)); 2961a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick int64_t IncValue; 2971a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick if (IncValueVal == 0 || Incr->getOperand(0) != PN || 2981a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick !ConvertToSInt(IncValueVal->getValueAPF(), IncValue)) 2991a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick return; 30003d3d3b361800f28c75d3386978d22e6d57744b7Andrew Trick 3011a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // Check Incr uses. One user is PN and the other user is an exit condition 3021a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // used by the conditional terminator. 3031a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick Value::use_iterator IncrUse = Incr->use_begin(); 3041a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick Instruction *U1 = cast<Instruction>(*IncrUse++); 3051a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick if (IncrUse == Incr->use_end()) return; 3061a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick Instruction *U2 = cast<Instruction>(*IncrUse++); 3071a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick if (IncrUse != Incr->use_end()) return; 308ca9b7037e28759c200fe5ca98190cabd121a1bbaDan Gohman 3091a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // Find exit condition, which is an fcmp. If it doesn't exist, or if it isn't 3101a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // only used by a branch, we can't transform it. 3111a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick FCmpInst *Compare = dyn_cast<FCmpInst>(U1); 3121a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick if (!Compare) 3131a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick Compare = dyn_cast<FCmpInst>(U2); 3141a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick if (Compare == 0 || !Compare->hasOneUse() || 3151a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick !isa<BranchInst>(Compare->use_back())) 3161a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick return; 317c2390b14c91764cba6e4394d05e58e387a7dfb19Dan Gohman 3181a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick BranchInst *TheBr = cast<BranchInst>(Compare->use_back()); 31959fdaeeae8f183e18bb6ad5c382ca23e28e6aaf6Chris Lattner 3201a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // We need to verify that the branch actually controls the iteration count 3211a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // of the loop. If not, the new IV can overflow and no one will notice. 3221a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // The branch block must be in the loop and one of the successors must be out 3231a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // of the loop. 3241a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick assert(TheBr->isConditional() && "Can't use fcmp if not conditional"); 3251a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick if (!L->contains(TheBr->getParent()) || 3261a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick (L->contains(TheBr->getSuccessor(0)) && 3271a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick L->contains(TheBr->getSuccessor(1)))) 3281a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick return; 32940bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner 33040bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner 3311a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // If it isn't a comparison with an integer-as-fp (the exit value), we can't 3321a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // transform it. 3331a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick ConstantFP *ExitValueVal = dyn_cast<ConstantFP>(Compare->getOperand(1)); 3341a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick int64_t ExitValue; 3351a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick if (ExitValueVal == 0 || 3361a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick !ConvertToSInt(ExitValueVal->getValueAPF(), ExitValue)) 3371a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick return; 338c2390b14c91764cba6e4394d05e58e387a7dfb19Dan Gohman 3391a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // Find new predicate for integer comparison. 3401a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick CmpInst::Predicate NewPred = CmpInst::BAD_ICMP_PREDICATE; 3411a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick switch (Compare->getPredicate()) { 3421a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick default: return; // Unknown comparison. 3431a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick case CmpInst::FCMP_OEQ: 3441a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick case CmpInst::FCMP_UEQ: NewPred = CmpInst::ICMP_EQ; break; 3451a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick case CmpInst::FCMP_ONE: 3461a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick case CmpInst::FCMP_UNE: NewPred = CmpInst::ICMP_NE; break; 3471a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick case CmpInst::FCMP_OGT: 3481a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick case CmpInst::FCMP_UGT: NewPred = CmpInst::ICMP_SGT; break; 3491a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick case CmpInst::FCMP_OGE: 3501a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick case CmpInst::FCMP_UGE: NewPred = CmpInst::ICMP_SGE; break; 3511a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick case CmpInst::FCMP_OLT: 3521a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick case CmpInst::FCMP_ULT: NewPred = CmpInst::ICMP_SLT; break; 3531a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick case CmpInst::FCMP_OLE: 3541a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick case CmpInst::FCMP_ULE: NewPred = CmpInst::ICMP_SLE; break; 3551a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick } 35681db61a2e6d3c95a2738c3559a108e05e9d7a05aDan Gohman 3571a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // We convert the floating point induction variable to a signed i32 value if 3581a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // we can. This is only safe if the comparison will not overflow in a way 3591a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // that won't be trapped by the integer equivalent operations. Check for this 3601a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // now. 3611a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // TODO: We could use i64 if it is native and the range requires it. 3623324e718bc9ac2ede08a14c325848b576849542bChris Lattner 3631a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // The start/stride/exit values must all fit in signed i32. 3641a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick if (!isInt<32>(InitValue) || !isInt<32>(IncValue) || !isInt<32>(ExitValue)) 3651a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick return; 36681db61a2e6d3c95a2738c3559a108e05e9d7a05aDan Gohman 3671a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // If not actually striding (add x, 0.0), avoid touching the code. 3681a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick if (IncValue == 0) 3691a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick return; 3701a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 3711a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // Positive and negative strides have different safety conditions. 3721a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick if (IncValue > 0) { 3731a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // If we have a positive stride, we require the init to be less than the 3741a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // exit value and an equality or less than comparison. 3751a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick if (InitValue >= ExitValue || 3761a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick NewPred == CmpInst::ICMP_SGT || NewPred == CmpInst::ICMP_SGE) 3771a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick return; 3781a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 3791a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick uint32_t Range = uint32_t(ExitValue-InitValue); 3801a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick if (NewPred == CmpInst::ICMP_SLE) { 3811a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // Normalize SLE -> SLT, check for infinite loop. 3821a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick if (++Range == 0) return; // Range overflows. 3831a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick } 3841a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 3851a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick unsigned Leftover = Range % uint32_t(IncValue); 3861a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 3871a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // If this is an equality comparison, we require that the strided value 3881a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // exactly land on the exit value, otherwise the IV condition will wrap 3891a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // around and do things the fp IV wouldn't. 3901a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick if ((NewPred == CmpInst::ICMP_EQ || NewPred == CmpInst::ICMP_NE) && 3911a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick Leftover != 0) 3921a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick return; 3931a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 3941a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // If the stride would wrap around the i32 before exiting, we can't 3951a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // transform the IV. 3961a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick if (Leftover != 0 && int32_t(ExitValue+IncValue) < ExitValue) 3971a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick return; 3981a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 3991a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick } else { 4001a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // If we have a negative stride, we require the init to be greater than the 4011a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // exit value and an equality or greater than comparison. 4021a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick if (InitValue >= ExitValue || 4031a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick NewPred == CmpInst::ICMP_SLT || NewPred == CmpInst::ICMP_SLE) 4041a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick return; 4051a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 4061a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick uint32_t Range = uint32_t(InitValue-ExitValue); 4071a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick if (NewPred == CmpInst::ICMP_SGE) { 4081a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // Normalize SGE -> SGT, check for infinite loop. 4091a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick if (++Range == 0) return; // Range overflows. 4101a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick } 4111a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 4121a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick unsigned Leftover = Range % uint32_t(-IncValue); 4131a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 4141a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // If this is an equality comparison, we require that the strided value 4151a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // exactly land on the exit value, otherwise the IV condition will wrap 4161a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // around and do things the fp IV wouldn't. 4171a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick if ((NewPred == CmpInst::ICMP_EQ || NewPred == CmpInst::ICMP_NE) && 4181a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick Leftover != 0) 4191a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick return; 4201a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 4211a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // If the stride would wrap around the i32 before exiting, we can't 4221a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // transform the IV. 4231a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick if (Leftover != 0 && int32_t(ExitValue+IncValue) > ExitValue) 4241a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick return; 4251a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick } 4261a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 427db125cfaf57cc83e7dd7453de2d509bc8efd0e5eChris Lattner IntegerType *Int32Ty = Type::getInt32Ty(PN->getContext()); 4281a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 4291a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // Insert new integer induction variable. 4301a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick PHINode *NewPHI = PHINode::Create(Int32Ty, 2, PN->getName()+".int", PN); 4311a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick NewPHI->addIncoming(ConstantInt::get(Int32Ty, InitValue), 4321a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick PN->getIncomingBlock(IncomingEdge)); 4331a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 4341a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick Value *NewAdd = 4351a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick BinaryOperator::CreateAdd(NewPHI, ConstantInt::get(Int32Ty, IncValue), 4361a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick Incr->getName()+".int", Incr); 4371a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick NewPHI->addIncoming(NewAdd, PN->getIncomingBlock(BackEdge)); 4381a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 4391a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick ICmpInst *NewCompare = new ICmpInst(TheBr, NewPred, NewAdd, 4401a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick ConstantInt::get(Int32Ty, ExitValue), 4411a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick Compare->getName()); 4421a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 4431a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // In the following deletions, PN may become dead and may be deleted. 4441a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // Use a WeakVH to observe whether this happens. 4451a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick WeakVH WeakPH = PN; 4461a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 4471a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // Delete the old floating point exit comparison. The branch starts using the 4481a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // new comparison. 4491a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick NewCompare->takeName(Compare); 4501a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick Compare->replaceAllUsesWith(NewCompare); 4511a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick RecursivelyDeleteTriviallyDeadInstructions(Compare); 4521a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 4531a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // Delete the old floating point increment. 4541a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick Incr->replaceAllUsesWith(UndefValue::get(Incr->getType())); 4551a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick RecursivelyDeleteTriviallyDeadInstructions(Incr); 4561a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 4571a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // If the FP induction variable still has uses, this is because something else 4581a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // in the loop uses its value. In order to canonicalize the induction 4591a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // variable, we chose to eliminate the IV and rewrite it in terms of an 4601a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // int->fp cast. 4611a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // 4621a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // We give preference to sitofp over uitofp because it is faster on most 4631a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // platforms. 4641a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick if (WeakPH) { 4651a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick Value *Conv = new SIToFPInst(NewPHI, PN->getType(), "indvar.conv", 466b05fdd6babada25da2ec3ba54bb462c2ecfc42a8Bill Wendling PN->getParent()->getFirstInsertionPt()); 4671a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick PN->replaceAllUsesWith(Conv); 4681a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick RecursivelyDeleteTriviallyDeadInstructions(PN); 4691a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick } 4701a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 4711a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // Add a new IVUsers entry for the newly-created integer PHI. 4721a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick if (IU) 4731a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick IU->AddUsersIfInteresting(NewPHI); 4744b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick 4754b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick Changed = true; 4761a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick} 4771a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 4781a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trickvoid IndVarSimplify::RewriteNonIntegerIVs(Loop *L) { 4791a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // First step. Check to see if there are any floating-point recurrences. 4801a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // If there are, change them into integer recurrences, permitting analysis by 4811a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // the SCEV routines. 4821a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // 4831a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick BasicBlock *Header = L->getHeader(); 4841a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 4851a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick SmallVector<WeakVH, 8> PHIs; 4861a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick for (BasicBlock::iterator I = Header->begin(); 4871a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick PHINode *PN = dyn_cast<PHINode>(I); ++I) 4881a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick PHIs.push_back(PN); 4891a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 4901a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick for (unsigned i = 0, e = PHIs.size(); i != e; ++i) 4911a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick if (PHINode *PN = dyn_cast_or_null<PHINode>(&*PHIs[i])) 4921a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick HandleFloatingPointIV(L, PN); 4931a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 4941a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // If the loop previously had floating-point IV, ScalarEvolution 4951a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // may not have been able to compute a trip count. Now that we've done some 4961a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // re-writing, the trip count may be computable. 4971a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick if (Changed) 4981a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick SE->forgetLoop(L); 4991a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick} 5001a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 5011a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick//===----------------------------------------------------------------------===// 5021a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick// RewriteLoopExitValues - Optimize IV users outside the loop. 5031a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick// As a side effect, reduces the amount of IV processing within the loop. 5041a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick//===----------------------------------------------------------------------===// 5051a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 5061a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick/// RewriteLoopExitValues - Check to see if this loop has a computable 5071a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick/// loop-invariant execution count. If so, this means that we can compute the 5081a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick/// final value of any expressions that are recurrent in the loop, and 5091a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick/// substitute the exit values from the loop into any instructions outside of 5101a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick/// the loop that use the final values of the current expressions. 5111a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick/// 5121a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick/// This is mostly redundant with the regular IndVarSimplify activities that 5131a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick/// happen later, except that it's more powerful in some cases, because it's 5141a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick/// able to brute-force evaluate arbitrary instructions as long as they have 5151a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick/// constant operands at the beginning of the loop. 5161a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trickvoid IndVarSimplify::RewriteLoopExitValues(Loop *L, SCEVExpander &Rewriter) { 5171a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // Verify the input to the pass in already in LCSSA form. 5181a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick assert(L->isLCSSAForm(*DT)); 5191a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 5201a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick SmallVector<BasicBlock*, 8> ExitBlocks; 5219f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner L->getUniqueExitBlocks(ExitBlocks); 5229f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner 5239f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner // Find all values that are computed inside the loop, but used outside of it. 5249f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner // Because of LCSSA, these values will only occur in LCSSA PHI Nodes. Scan 5259f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner // the exit blocks of the loop to find them. 5269f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner for (unsigned i = 0, e = ExitBlocks.size(); i != e; ++i) { 5279f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner BasicBlock *ExitBB = ExitBlocks[i]; 528cafb81337bdf2574049533f5b8a6bc1ed92f1f3eDan Gohman 5299f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner // If there are no PHI nodes in this exit block, then no values defined 5309f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner // inside the loop are used on this path, skip it. 5319f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner PHINode *PN = dyn_cast<PHINode>(ExitBB->begin()); 5329f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner if (!PN) continue; 533cafb81337bdf2574049533f5b8a6bc1ed92f1f3eDan Gohman 5349f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner unsigned NumPreds = PN->getNumIncomingValues(); 535cafb81337bdf2574049533f5b8a6bc1ed92f1f3eDan Gohman 5369f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner // Iterate over all of the PHI nodes. 5379f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner BasicBlock::iterator BBI = ExitBB->begin(); 5389f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner while ((PN = dyn_cast<PHINode>(BBI++))) { 5393790fb0c036acaa4db50aff83dd8b3bf51f8af6aTorok Edwin if (PN->use_empty()) 5403790fb0c036acaa4db50aff83dd8b3bf51f8af6aTorok Edwin continue; // dead use, don't replace it 541814f2b2d1927a5397c0e923588527277b9f67d6bDan Gohman 542814f2b2d1927a5397c0e923588527277b9f67d6bDan Gohman // SCEV only supports integer expressions for now. 543814f2b2d1927a5397c0e923588527277b9f67d6bDan Gohman if (!PN->getType()->isIntegerTy() && !PN->getType()->isPointerTy()) 544814f2b2d1927a5397c0e923588527277b9f67d6bDan Gohman continue; 545814f2b2d1927a5397c0e923588527277b9f67d6bDan Gohman 54645a2d7d44ae697e28df383d31455145fb754ac58Dale Johannesen // It's necessary to tell ScalarEvolution about this explicitly so that 54745a2d7d44ae697e28df383d31455145fb754ac58Dale Johannesen // it can walk the def-use list and forget all SCEVs, as it may not be 54845a2d7d44ae697e28df383d31455145fb754ac58Dale Johannesen // watching the PHI itself. Once the new exit value is in place, there 54945a2d7d44ae697e28df383d31455145fb754ac58Dale Johannesen // may not be a def-use connection between the loop and every instruction 55045a2d7d44ae697e28df383d31455145fb754ac58Dale Johannesen // which got a SCEVAddRecExpr for that loop. 55145a2d7d44ae697e28df383d31455145fb754ac58Dale Johannesen SE->forgetValue(PN); 55245a2d7d44ae697e28df383d31455145fb754ac58Dale Johannesen 5539f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner // Iterate over all of the values in all the PHI nodes. 5549f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner for (unsigned i = 0; i != NumPreds; ++i) { 5559f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner // If the value being merged in is not integer or is not defined 5569f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner // in the loop, skip it. 5579f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner Value *InVal = PN->getIncomingValue(i); 558814f2b2d1927a5397c0e923588527277b9f67d6bDan Gohman if (!isa<Instruction>(InVal)) 5599f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner continue; 5609f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner 5619f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner // If this pred is for a subloop, not L itself, skip it. 562cafb81337bdf2574049533f5b8a6bc1ed92f1f3eDan Gohman if (LI->getLoopFor(PN->getIncomingBlock(i)) != L) 5639f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner continue; // The Block is in a subloop, skip it. 5649f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner 5659f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner // Check that InVal is defined in the loop. 5669f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner Instruction *Inst = cast<Instruction>(InVal); 56792329c7fbe572892c17aa2d2542a10e3ea16132fDan Gohman if (!L->contains(Inst)) 5689f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner continue; 569cafb81337bdf2574049533f5b8a6bc1ed92f1f3eDan Gohman 5709f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner // Okay, this instruction has a user outside of the current loop 5719f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner // and varies predictably *inside* the loop. Evaluate the value it 5729f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner // contains when the loop exits, if possible. 5730bba49cebc50c7bd4662a4807bcb3ee7f42cb470Dan Gohman const SCEV *ExitValue = SE->getSCEVAtScope(Inst, L->getParentLoop()); 57417ead4ff4baceb2c5503f233d0288d363ae44165Dan Gohman if (!SE->isLoopInvariant(ExitValue, L)) 5759f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner continue; 5769f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner 577667d787c0a21cf3f5dfcde03ca471162ba35b614Dan Gohman Value *ExitVal = Rewriter.expandCodeFor(ExitValue, PN->getType(), Inst); 578cafb81337bdf2574049533f5b8a6bc1ed92f1f3eDan Gohman 579f67ef318aa29e7cc0c7de76349881959936d9eeeDavid Greene DEBUG(dbgs() << "INDVARS: RLEV: AfterLoopVal = " << *ExitVal << '\n' 580bdff548e4dd577a72094d57b282de4e765643b96Chris Lattner << " LoopVal = " << *Inst << "\n"); 5819caed5440d59dac4b388152fe8b993dc0491e5e9Chris Lattner 582b12a754cce0c1d5542af605203a47820edba454dAndrew Trick if (!isValidRewrite(Inst, ExitVal)) { 583b12a754cce0c1d5542af605203a47820edba454dAndrew Trick DeadInsts.push_back(ExitVal); 584b12a754cce0c1d5542af605203a47820edba454dAndrew Trick continue; 585b12a754cce0c1d5542af605203a47820edba454dAndrew Trick } 586b12a754cce0c1d5542af605203a47820edba454dAndrew Trick Changed = true; 587b12a754cce0c1d5542af605203a47820edba454dAndrew Trick ++NumReplaced; 588b12a754cce0c1d5542af605203a47820edba454dAndrew Trick 5899f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner PN->setIncomingValue(i, ExitVal); 590cafb81337bdf2574049533f5b8a6bc1ed92f1f3eDan Gohman 59181db61a2e6d3c95a2738c3559a108e05e9d7a05aDan Gohman // If this instruction is dead now, delete it. 59281db61a2e6d3c95a2738c3559a108e05e9d7a05aDan Gohman RecursivelyDeleteTriviallyDeadInstructions(Inst); 593cafb81337bdf2574049533f5b8a6bc1ed92f1f3eDan Gohman 59465d1e2b6e74fcd370093cbe518ebc15cbc445ad4Dan Gohman if (NumPreds == 1) { 59565d1e2b6e74fcd370093cbe518ebc15cbc445ad4Dan Gohman // Completely replace a single-pred PHI. This is safe, because the 59665d1e2b6e74fcd370093cbe518ebc15cbc445ad4Dan Gohman // NewVal won't be variant in the loop, so we don't need an LCSSA phi 59765d1e2b6e74fcd370093cbe518ebc15cbc445ad4Dan Gohman // node anymore. 5989f3d73886612fd06812fb63cf8e6fa10db9b17e7Chris Lattner PN->replaceAllUsesWith(ExitVal); 59981db61a2e6d3c95a2738c3559a108e05e9d7a05aDan Gohman RecursivelyDeleteTriviallyDeadInstructions(PN); 600c9838f25d53d3dd7d38949ef6c28f2505a110f45Chris Lattner } 6014bd09d70cceb3851f7eb1c2f98338b3071d405f3Chris Lattner } 60265d1e2b6e74fcd370093cbe518ebc15cbc445ad4Dan Gohman if (NumPreds != 1) { 603667d787c0a21cf3f5dfcde03ca471162ba35b614Dan Gohman // Clone the PHI and delete the original one. This lets IVUsers and 604667d787c0a21cf3f5dfcde03ca471162ba35b614Dan Gohman // any other maps purge the original user from their records. 60550b6e33584f4e4cf75c7795b1f1a90731861c825Devang Patel PHINode *NewPN = cast<PHINode>(PN->clone()); 606667d787c0a21cf3f5dfcde03ca471162ba35b614Dan Gohman NewPN->takeName(PN); 607667d787c0a21cf3f5dfcde03ca471162ba35b614Dan Gohman NewPN->insertBefore(PN); 608667d787c0a21cf3f5dfcde03ca471162ba35b614Dan Gohman PN->replaceAllUsesWith(NewPN); 609667d787c0a21cf3f5dfcde03ca471162ba35b614Dan Gohman PN->eraseFromParent(); 610667d787c0a21cf3f5dfcde03ca471162ba35b614Dan Gohman } 611c9838f25d53d3dd7d38949ef6c28f2505a110f45Chris Lattner } 612c9838f25d53d3dd7d38949ef6c28f2505a110f45Chris Lattner } 613472fdf7090bb00af3a3f9dcbe22263120a527533Dan Gohman 614472fdf7090bb00af3a3f9dcbe22263120a527533Dan Gohman // The insertion point instruction may have been deleted; clear it out 615472fdf7090bb00af3a3f9dcbe22263120a527533Dan Gohman // so that the rewriter doesn't trip over it later. 616472fdf7090bb00af3a3f9dcbe22263120a527533Dan Gohman Rewriter.clearInsertPoint(); 61740bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner} 61815cad759fe2048ac5eb137c6bb0ab7287538677eChris Lattner 6191a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick//===----------------------------------------------------------------------===// 6201a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick// Rewrite IV users based on a canonical IV. 6211a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick// To be replaced by -disable-iv-rewrite. 6221a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick//===----------------------------------------------------------------------===// 623c671d892ab1d3d8fed18a61f66f3f3a86e73ebd9Dale Johannesen 62439d7802224532c075f4c781c3e51ffed83d17420Andrew Trick/// FIXME: It is an extremely bad idea to indvar substitute anything more 62539d7802224532c075f4c781c3e51ffed83d17420Andrew Trick/// complex than affine induction variables. Doing so will put expensive 62639d7802224532c075f4c781c3e51ffed83d17420Andrew Trick/// polynomial evaluations inside of the loop, and the str reduction pass 62739d7802224532c075f4c781c3e51ffed83d17420Andrew Trick/// currently can only reduce affine polynomials. For now just disable 62839d7802224532c075f4c781c3e51ffed83d17420Andrew Trick/// indvar subst on anything more complex than an affine addrec, unless 62939d7802224532c075f4c781c3e51ffed83d17420Andrew Trick/// it can be expanded to a trivial value. 6301a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trickstatic bool isSafe(const SCEV *S, const Loop *L, ScalarEvolution *SE) { 6311a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // Loop-invariant values are safe. 6321a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick if (SE->isLoopInvariant(S, L)) return true; 633f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick 6341a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // Affine addrecs are safe. Non-affine are not, because LSR doesn't know how 6351a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // to transform them into efficient code. 6361a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S)) 6371a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick return AR->isAffine(); 638f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick 6391a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // An add is safe it all its operands are safe. 64039d7802224532c075f4c781c3e51ffed83d17420Andrew Trick if (const SCEVCommutativeExpr *Commutative 64139d7802224532c075f4c781c3e51ffed83d17420Andrew Trick = dyn_cast<SCEVCommutativeExpr>(S)) { 6421a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick for (SCEVCommutativeExpr::op_iterator I = Commutative->op_begin(), 6431a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick E = Commutative->op_end(); I != E; ++I) 6441a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick if (!isSafe(*I, L, SE)) return false; 6451a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick return true; 646f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick } 647f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick 6481a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // A cast is safe if its operand is. 6491a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick if (const SCEVCastExpr *C = dyn_cast<SCEVCastExpr>(S)) 6501a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick return isSafe(C->getOperand(), L, SE); 651f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick 6521a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // A udiv is safe if its operands are. 6531a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick if (const SCEVUDivExpr *UD = dyn_cast<SCEVUDivExpr>(S)) 6541a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick return isSafe(UD->getLHS(), L, SE) && 6551a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick isSafe(UD->getRHS(), L, SE); 656f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick 6571a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // SCEVUnknown is always safe. 6581a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick if (isa<SCEVUnknown>(S)) 6591a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick return true; 660f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick 6611a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // Nothing else is safe. 6621a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick return false; 6631a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick} 664f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick 6651a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trickvoid IndVarSimplify::RewriteIVExpressions(Loop *L, SCEVExpander &Rewriter) { 6661a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // Rewrite all induction variable expressions in terms of the canonical 6671a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // induction variable. 6681a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // 6691a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // If there were induction variables of other sizes or offsets, manually 6701a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // add the offsets to the primary induction variable and cast, avoiding 6711a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // the need for the code evaluation methods to insert induction variables 6721a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // of different sizes. 6731a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick for (IVUsers::iterator UI = IU->begin(), E = IU->end(); UI != E; ++UI) { 6741a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick Value *Op = UI->getOperandValToReplace(); 675db125cfaf57cc83e7dd7453de2d509bc8efd0e5eChris Lattner Type *UseTy = Op->getType(); 6761a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick Instruction *User = UI->getUser(); 6771a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 6781a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // Compute the final addrec to expand into code. 6791a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick const SCEV *AR = IU->getReplacementExpr(*UI); 6801a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 6811a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // Evaluate the expression out of the loop, if possible. 6821a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick if (!L->contains(UI->getUser())) { 6831a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick const SCEV *ExitVal = SE->getSCEVAtScope(AR, L->getParentLoop()); 6841a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick if (SE->isLoopInvariant(ExitVal, L)) 6851a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick AR = ExitVal; 6861a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick } 6871a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 6881a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // FIXME: It is an extremely bad idea to indvar substitute anything more 6891a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // complex than affine induction variables. Doing so will put expensive 6901a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // polynomial evaluations inside of the loop, and the str reduction pass 6911a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // currently can only reduce affine polynomials. For now just disable 6921a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // indvar subst on anything more complex than an affine addrec, unless 6931a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // it can be expanded to a trivial value. 6941a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick if (!isSafe(AR, L, SE)) 6951a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick continue; 6961a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 6971a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // Determine the insertion point for this user. By default, insert 6981a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // immediately before the user. The SCEVExpander class will automatically 6991a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // hoist loop invariants out of the loop. For PHI nodes, there may be 7001a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // multiple uses, so compute the nearest common dominator for the 7011a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // incoming blocks. 70286c98145b268a0d10e062792f98bc8eea6b639b4Andrew Trick Instruction *InsertPt = getInsertPointForUses(User, Op, DT); 7031a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 7041a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // Now expand it into actual Instructions and patch it into place. 7051a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick Value *NewVal = Rewriter.expandCodeFor(AR, UseTy, InsertPt); 7061a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 7071a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick DEBUG(dbgs() << "INDVARS: Rewrote IV '" << *AR << "' " << *Op << '\n' 7081a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick << " into = " << *NewVal << "\n"); 7091a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 7101a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick if (!isValidRewrite(Op, NewVal)) { 7111a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick DeadInsts.push_back(NewVal); 7121a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick continue; 7131a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick } 7141a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // Inform ScalarEvolution that this value is changing. The change doesn't 7151a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // affect its value, but it does potentially affect which use lists the 7161a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // value will be on after the replacement, which affects ScalarEvolution's 7171a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // ability to walk use lists and drop dangling pointers when a value is 7181a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // deleted. 7191a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick SE->forgetValue(User); 7201a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 7211a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // Patch the new value into place. 7221a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick if (Op->hasName()) 7231a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick NewVal->takeName(Op); 7241a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick if (Instruction *NewValI = dyn_cast<Instruction>(NewVal)) 7251a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick NewValI->setDebugLoc(User->getDebugLoc()); 7261a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick User->replaceUsesOfWith(Op, NewVal); 7271a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick UI->setOperandValToReplace(NewVal); 7281a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 7291a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick ++NumRemoved; 7301a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick Changed = true; 7311a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 7321a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // The old value may be dead now. 7331a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick DeadInsts.push_back(Op); 7341a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick } 7351a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick} 7361a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 7371a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick//===----------------------------------------------------------------------===// 7381a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick// IV Widening - Extend the width of an IV to cover its widest uses. 7391a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick//===----------------------------------------------------------------------===// 7401a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 7411a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Tricknamespace { 7421a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // Collect information about induction variables that are used by sign/zero 7431a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // extend operations. This information is recorded by CollectExtend and 7441a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // provides the input to WidenIV. 7451a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick struct WideIVInfo { 746db125cfaf57cc83e7dd7453de2d509bc8efd0e5eChris Lattner Type *WidestNativeType; // Widest integer type created [sz]ext 7474b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick bool IsSigned; // Was an sext user seen before a zext? 7481a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 7491a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick WideIVInfo() : WidestNativeType(0), IsSigned(false) {} 7501a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick }; 7514b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick 7524b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick class WideIVVisitor : public IVVisitor { 7534b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick ScalarEvolution *SE; 7544b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick const TargetData *TD; 7554b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick 7564b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick public: 7574b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick WideIVInfo WI; 7584b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick 7594b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick WideIVVisitor(ScalarEvolution *SCEV, const TargetData *TData) : 7604b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick SE(SCEV), TD(TData) {} 7614b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick 7624b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick // Implement the interface used by simplifyUsersOfIV. 7634b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick virtual void visitCast(CastInst *Cast); 7644b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick }; 7651a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick} 7661a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 7674b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick/// visitCast - Update information about the induction variable that is 7681a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick/// extended by this sign or zero extend operation. This is used to determine 7691a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick/// the final width of the IV before actually widening it. 7704b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trickvoid WideIVVisitor::visitCast(CastInst *Cast) { 7714b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick bool IsSigned = Cast->getOpcode() == Instruction::SExt; 7724b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick if (!IsSigned && Cast->getOpcode() != Instruction::ZExt) 7734b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick return; 7744b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick 775db125cfaf57cc83e7dd7453de2d509bc8efd0e5eChris Lattner Type *Ty = Cast->getType(); 7761a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick uint64_t Width = SE->getTypeSizeInBits(Ty); 7771a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick if (TD && !TD->isLegalInteger(Width)) 7781a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick return; 7791a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 7801a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick if (!WI.WidestNativeType) { 7811a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick WI.WidestNativeType = SE->getEffectiveSCEVType(Ty); 7821a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick WI.IsSigned = IsSigned; 7831a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick return; 7841a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick } 7851a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 7861a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // We extend the IV to satisfy the sign of its first user, arbitrarily. 7871a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick if (WI.IsSigned != IsSigned) 7881a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick return; 7891a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 7901a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick if (Width > SE->getTypeSizeInBits(WI.WidestNativeType)) 7911a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick WI.WidestNativeType = SE->getEffectiveSCEVType(Ty); 7921a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick} 7931a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 7941a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Tricknamespace { 79513bcf2e68a88cb87378c9773effa5b79b3091d75Andrew Trick 79613bcf2e68a88cb87378c9773effa5b79b3091d75Andrew Trick/// NarrowIVDefUse - Record a link in the Narrow IV def-use chain along with the 79713bcf2e68a88cb87378c9773effa5b79b3091d75Andrew Trick/// WideIV that computes the same value as the Narrow IV def. This avoids 79813bcf2e68a88cb87378c9773effa5b79b3091d75Andrew Trick/// caching Use* pointers. 79913bcf2e68a88cb87378c9773effa5b79b3091d75Andrew Trickstruct NarrowIVDefUse { 80013bcf2e68a88cb87378c9773effa5b79b3091d75Andrew Trick Instruction *NarrowDef; 80113bcf2e68a88cb87378c9773effa5b79b3091d75Andrew Trick Instruction *NarrowUse; 80213bcf2e68a88cb87378c9773effa5b79b3091d75Andrew Trick Instruction *WideDef; 80313bcf2e68a88cb87378c9773effa5b79b3091d75Andrew Trick 80413bcf2e68a88cb87378c9773effa5b79b3091d75Andrew Trick NarrowIVDefUse(): NarrowDef(0), NarrowUse(0), WideDef(0) {} 80513bcf2e68a88cb87378c9773effa5b79b3091d75Andrew Trick 80613bcf2e68a88cb87378c9773effa5b79b3091d75Andrew Trick NarrowIVDefUse(Instruction *ND, Instruction *NU, Instruction *WD): 80713bcf2e68a88cb87378c9773effa5b79b3091d75Andrew Trick NarrowDef(ND), NarrowUse(NU), WideDef(WD) {} 80813bcf2e68a88cb87378c9773effa5b79b3091d75Andrew Trick}; 80913bcf2e68a88cb87378c9773effa5b79b3091d75Andrew Trick 8101a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick/// WidenIV - The goal of this transform is to remove sign and zero extends 8111a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick/// without creating any new induction variables. To do this, it creates a new 8121a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick/// phi of the wider type and redirects all users, either removing extends or 8131a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick/// inserting truncs whenever we stop propagating the type. 8141a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick/// 8151a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trickclass WidenIV { 8161a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // Parameters 8171a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick PHINode *OrigPhi; 818db125cfaf57cc83e7dd7453de2d509bc8efd0e5eChris Lattner Type *WideType; 8191a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick bool IsSigned; 8201a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 8211a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // Context 8221a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick LoopInfo *LI; 8231a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick Loop *L; 8241a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick ScalarEvolution *SE; 8251a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick DominatorTree *DT; 8261a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 8271a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // Result 8281a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick PHINode *WidePhi; 8291a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick Instruction *WideInc; 8301a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick const SCEV *WideIncExpr; 8312fabd464ae9fd33f068066e3fc3d0caa7ea2279dAndrew Trick SmallVectorImpl<WeakVH> &DeadInsts; 832f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick 8332fabd464ae9fd33f068066e3fc3d0caa7ea2279dAndrew Trick SmallPtrSet<Instruction*,16> Widened; 83413bcf2e68a88cb87378c9773effa5b79b3091d75Andrew Trick SmallVector<NarrowIVDefUse, 8> NarrowIVUsers; 835f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick 836f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trickpublic: 8372fabd464ae9fd33f068066e3fc3d0caa7ea2279dAndrew Trick WidenIV(PHINode *PN, const WideIVInfo &WI, LoopInfo *LInfo, 8382fabd464ae9fd33f068066e3fc3d0caa7ea2279dAndrew Trick ScalarEvolution *SEv, DominatorTree *DTree, 839fcdc9a44e59ff2846c6f929e91c90ee34e6ba5d5Andrew Trick SmallVectorImpl<WeakVH> &DI) : 840f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick OrigPhi(PN), 8412fabd464ae9fd33f068066e3fc3d0caa7ea2279dAndrew Trick WideType(WI.WidestNativeType), 8422fabd464ae9fd33f068066e3fc3d0caa7ea2279dAndrew Trick IsSigned(WI.IsSigned), 843f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick LI(LInfo), 844f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick L(LI->getLoopFor(OrigPhi->getParent())), 845f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick SE(SEv), 846fcdc9a44e59ff2846c6f929e91c90ee34e6ba5d5Andrew Trick DT(DTree), 847f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick WidePhi(0), 848f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick WideInc(0), 8492fabd464ae9fd33f068066e3fc3d0caa7ea2279dAndrew Trick WideIncExpr(0), 8502fabd464ae9fd33f068066e3fc3d0caa7ea2279dAndrew Trick DeadInsts(DI) { 851f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick assert(L->getHeader() == OrigPhi->getParent() && "Phi must be an IV"); 852f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick } 853f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick 8542fabd464ae9fd33f068066e3fc3d0caa7ea2279dAndrew Trick PHINode *CreateWideIV(SCEVExpander &Rewriter); 855f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick 856f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trickprotected: 85713bcf2e68a88cb87378c9773effa5b79b3091d75Andrew Trick Instruction *CloneIVUser(NarrowIVDefUse DU); 858f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick 859e0dc2faaa0105c9d1cc56f0b70e93d532a6f8c4cAndrew Trick const SCEVAddRecExpr *GetWideRecurrence(Instruction *NarrowUse); 860e0dc2faaa0105c9d1cc56f0b70e93d532a6f8c4cAndrew Trick 86120151da8c38287b9fa181e9fef93f70bc2cd9fd2Andrew Trick const SCEVAddRecExpr* GetExtendedOperandRecurrence(NarrowIVDefUse DU); 86220151da8c38287b9fa181e9fef93f70bc2cd9fd2Andrew Trick 86313bcf2e68a88cb87378c9773effa5b79b3091d75Andrew Trick Instruction *WidenIVUse(NarrowIVDefUse DU); 8644b02915386046fa882a95553a7457ae7d05e9f27Andrew Trick 8654b02915386046fa882a95553a7457ae7d05e9f27Andrew Trick void pushNarrowIVUsers(Instruction *NarrowDef, Instruction *WideDef); 866f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick}; 867f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick} // anonymous namespace 868f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick 869db125cfaf57cc83e7dd7453de2d509bc8efd0e5eChris Lattnerstatic Value *getExtend( Value *NarrowOper, Type *WideType, 87003d3d3b361800f28c75d3386978d22e6d57744b7Andrew Trick bool IsSigned, IRBuilder<> &Builder) { 87103d3d3b361800f28c75d3386978d22e6d57744b7Andrew Trick return IsSigned ? Builder.CreateSExt(NarrowOper, WideType) : 87203d3d3b361800f28c75d3386978d22e6d57744b7Andrew Trick Builder.CreateZExt(NarrowOper, WideType); 873f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick} 874931e345e76e75391d2a7c96530e305f802b5429dDan Gohman 875f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick/// CloneIVUser - Instantiate a wide operation to replace a narrow 876f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick/// operation. This only needs to handle operations that can evaluation to 877f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick/// SCEVAddRec. It can safely return 0 for any operation we decide not to clone. 87813bcf2e68a88cb87378c9773effa5b79b3091d75Andrew TrickInstruction *WidenIV::CloneIVUser(NarrowIVDefUse DU) { 87913bcf2e68a88cb87378c9773effa5b79b3091d75Andrew Trick unsigned Opcode = DU.NarrowUse->getOpcode(); 880f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick switch (Opcode) { 881f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick default: 882f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick return 0; 883f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick case Instruction::Add: 884f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick case Instruction::Mul: 885f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick case Instruction::UDiv: 886f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick case Instruction::Sub: 887f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick case Instruction::And: 888f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick case Instruction::Or: 889f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick case Instruction::Xor: 890f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick case Instruction::Shl: 891f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick case Instruction::LShr: 892f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick case Instruction::AShr: 89313bcf2e68a88cb87378c9773effa5b79b3091d75Andrew Trick DEBUG(dbgs() << "Cloning IVUser: " << *DU.NarrowUse << "\n"); 894f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick 89513bcf2e68a88cb87378c9773effa5b79b3091d75Andrew Trick IRBuilder<> Builder(DU.NarrowUse); 89603d3d3b361800f28c75d3386978d22e6d57744b7Andrew Trick 89703d3d3b361800f28c75d3386978d22e6d57744b7Andrew Trick // Replace NarrowDef operands with WideDef. Otherwise, we don't know 89803d3d3b361800f28c75d3386978d22e6d57744b7Andrew Trick // anything about the narrow operand yet so must insert a [sz]ext. It is 89903d3d3b361800f28c75d3386978d22e6d57744b7Andrew Trick // probably loop invariant and will be folded or hoisted. If it actually 90003d3d3b361800f28c75d3386978d22e6d57744b7Andrew Trick // comes from a widened IV, it should be removed during a future call to 90103d3d3b361800f28c75d3386978d22e6d57744b7Andrew Trick // WidenIVUse. 90213bcf2e68a88cb87378c9773effa5b79b3091d75Andrew Trick Value *LHS = (DU.NarrowUse->getOperand(0) == DU.NarrowDef) ? DU.WideDef : 90313bcf2e68a88cb87378c9773effa5b79b3091d75Andrew Trick getExtend(DU.NarrowUse->getOperand(0), WideType, IsSigned, Builder); 90413bcf2e68a88cb87378c9773effa5b79b3091d75Andrew Trick Value *RHS = (DU.NarrowUse->getOperand(1) == DU.NarrowDef) ? DU.WideDef : 90513bcf2e68a88cb87378c9773effa5b79b3091d75Andrew Trick getExtend(DU.NarrowUse->getOperand(1), WideType, IsSigned, Builder); 90603d3d3b361800f28c75d3386978d22e6d57744b7Andrew Trick 90713bcf2e68a88cb87378c9773effa5b79b3091d75Andrew Trick BinaryOperator *NarrowBO = cast<BinaryOperator>(DU.NarrowUse); 908f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick BinaryOperator *WideBO = BinaryOperator::Create(NarrowBO->getOpcode(), 90903d3d3b361800f28c75d3386978d22e6d57744b7Andrew Trick LHS, RHS, 910f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick NarrowBO->getName()); 911f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick Builder.Insert(WideBO); 9126e0ce24e0ca8b0dc05872b9b4cec3a18972bee40Andrew Trick if (const OverflowingBinaryOperator *OBO = 9136e0ce24e0ca8b0dc05872b9b4cec3a18972bee40Andrew Trick dyn_cast<OverflowingBinaryOperator>(NarrowBO)) { 9146e0ce24e0ca8b0dc05872b9b4cec3a18972bee40Andrew Trick if (OBO->hasNoUnsignedWrap()) WideBO->setHasNoUnsignedWrap(); 9156e0ce24e0ca8b0dc05872b9b4cec3a18972bee40Andrew Trick if (OBO->hasNoSignedWrap()) WideBO->setHasNoSignedWrap(); 9166e0ce24e0ca8b0dc05872b9b4cec3a18972bee40Andrew Trick } 91703d3d3b361800f28c75d3386978d22e6d57744b7Andrew Trick return WideBO; 918f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick } 919f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick llvm_unreachable(0); 920f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick} 921f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick 922fcdc9a44e59ff2846c6f929e91c90ee34e6ba5d5Andrew Trick/// HoistStep - Attempt to hoist an IV increment above a potential use. 923fcdc9a44e59ff2846c6f929e91c90ee34e6ba5d5Andrew Trick/// 924fcdc9a44e59ff2846c6f929e91c90ee34e6ba5d5Andrew Trick/// To successfully hoist, two criteria must be met: 925fcdc9a44e59ff2846c6f929e91c90ee34e6ba5d5Andrew Trick/// - IncV operands dominate InsertPos and 926fcdc9a44e59ff2846c6f929e91c90ee34e6ba5d5Andrew Trick/// - InsertPos dominates IncV 927fcdc9a44e59ff2846c6f929e91c90ee34e6ba5d5Andrew Trick/// 928fcdc9a44e59ff2846c6f929e91c90ee34e6ba5d5Andrew Trick/// Meeting the second condition means that we don't need to check all of IncV's 929fcdc9a44e59ff2846c6f929e91c90ee34e6ba5d5Andrew Trick/// existing uses (it's moving up in the domtree). 930fcdc9a44e59ff2846c6f929e91c90ee34e6ba5d5Andrew Trick/// 931fcdc9a44e59ff2846c6f929e91c90ee34e6ba5d5Andrew Trick/// This does not yet recursively hoist the operands, although that would 932fcdc9a44e59ff2846c6f929e91c90ee34e6ba5d5Andrew Trick/// not be difficult. 933fcdc9a44e59ff2846c6f929e91c90ee34e6ba5d5Andrew Trickstatic bool HoistStep(Instruction *IncV, Instruction *InsertPos, 934fcdc9a44e59ff2846c6f929e91c90ee34e6ba5d5Andrew Trick const DominatorTree *DT) 935fcdc9a44e59ff2846c6f929e91c90ee34e6ba5d5Andrew Trick{ 936fcdc9a44e59ff2846c6f929e91c90ee34e6ba5d5Andrew Trick if (DT->dominates(IncV, InsertPos)) 937fcdc9a44e59ff2846c6f929e91c90ee34e6ba5d5Andrew Trick return true; 938fcdc9a44e59ff2846c6f929e91c90ee34e6ba5d5Andrew Trick 939fcdc9a44e59ff2846c6f929e91c90ee34e6ba5d5Andrew Trick if (!DT->dominates(InsertPos->getParent(), IncV->getParent())) 940fcdc9a44e59ff2846c6f929e91c90ee34e6ba5d5Andrew Trick return false; 941fcdc9a44e59ff2846c6f929e91c90ee34e6ba5d5Andrew Trick 942fcdc9a44e59ff2846c6f929e91c90ee34e6ba5d5Andrew Trick if (IncV->mayHaveSideEffects()) 943fcdc9a44e59ff2846c6f929e91c90ee34e6ba5d5Andrew Trick return false; 944fcdc9a44e59ff2846c6f929e91c90ee34e6ba5d5Andrew Trick 945fcdc9a44e59ff2846c6f929e91c90ee34e6ba5d5Andrew Trick // Attempt to hoist IncV 946fcdc9a44e59ff2846c6f929e91c90ee34e6ba5d5Andrew Trick for (User::op_iterator OI = IncV->op_begin(), OE = IncV->op_end(); 947fcdc9a44e59ff2846c6f929e91c90ee34e6ba5d5Andrew Trick OI != OE; ++OI) { 948fcdc9a44e59ff2846c6f929e91c90ee34e6ba5d5Andrew Trick Instruction *OInst = dyn_cast<Instruction>(OI); 949fcdc9a44e59ff2846c6f929e91c90ee34e6ba5d5Andrew Trick if (OInst && !DT->dominates(OInst, InsertPos)) 950fcdc9a44e59ff2846c6f929e91c90ee34e6ba5d5Andrew Trick return false; 951fcdc9a44e59ff2846c6f929e91c90ee34e6ba5d5Andrew Trick } 952fcdc9a44e59ff2846c6f929e91c90ee34e6ba5d5Andrew Trick IncV->moveBefore(InsertPos); 953fcdc9a44e59ff2846c6f929e91c90ee34e6ba5d5Andrew Trick return true; 954fcdc9a44e59ff2846c6f929e91c90ee34e6ba5d5Andrew Trick} 955fcdc9a44e59ff2846c6f929e91c90ee34e6ba5d5Andrew Trick 95620151da8c38287b9fa181e9fef93f70bc2cd9fd2Andrew Trick/// No-wrap operations can transfer sign extension of their result to their 95720151da8c38287b9fa181e9fef93f70bc2cd9fd2Andrew Trick/// operands. Generate the SCEV value for the widened operation without 95820151da8c38287b9fa181e9fef93f70bc2cd9fd2Andrew Trick/// actually modifying the IR yet. If the expression after extending the 95920151da8c38287b9fa181e9fef93f70bc2cd9fd2Andrew Trick/// operands is an AddRec for this loop, return it. 96020151da8c38287b9fa181e9fef93f70bc2cd9fd2Andrew Trickconst SCEVAddRecExpr* WidenIV::GetExtendedOperandRecurrence(NarrowIVDefUse DU) { 96120151da8c38287b9fa181e9fef93f70bc2cd9fd2Andrew Trick // Handle the common case of add<nsw/nuw> 96220151da8c38287b9fa181e9fef93f70bc2cd9fd2Andrew Trick if (DU.NarrowUse->getOpcode() != Instruction::Add) 96320151da8c38287b9fa181e9fef93f70bc2cd9fd2Andrew Trick return 0; 96420151da8c38287b9fa181e9fef93f70bc2cd9fd2Andrew Trick 96520151da8c38287b9fa181e9fef93f70bc2cd9fd2Andrew Trick // One operand (NarrowDef) has already been extended to WideDef. Now determine 96620151da8c38287b9fa181e9fef93f70bc2cd9fd2Andrew Trick // if extending the other will lead to a recurrence. 96720151da8c38287b9fa181e9fef93f70bc2cd9fd2Andrew Trick unsigned ExtendOperIdx = DU.NarrowUse->getOperand(0) == DU.NarrowDef ? 1 : 0; 96820151da8c38287b9fa181e9fef93f70bc2cd9fd2Andrew Trick assert(DU.NarrowUse->getOperand(1-ExtendOperIdx) == DU.NarrowDef && "bad DU"); 96920151da8c38287b9fa181e9fef93f70bc2cd9fd2Andrew Trick 97020151da8c38287b9fa181e9fef93f70bc2cd9fd2Andrew Trick const SCEV *ExtendOperExpr = 0; 97120151da8c38287b9fa181e9fef93f70bc2cd9fd2Andrew Trick const OverflowingBinaryOperator *OBO = 97220151da8c38287b9fa181e9fef93f70bc2cd9fd2Andrew Trick cast<OverflowingBinaryOperator>(DU.NarrowUse); 97320151da8c38287b9fa181e9fef93f70bc2cd9fd2Andrew Trick if (IsSigned && OBO->hasNoSignedWrap()) 97420151da8c38287b9fa181e9fef93f70bc2cd9fd2Andrew Trick ExtendOperExpr = SE->getSignExtendExpr( 97520151da8c38287b9fa181e9fef93f70bc2cd9fd2Andrew Trick SE->getSCEV(DU.NarrowUse->getOperand(ExtendOperIdx)), WideType); 97620151da8c38287b9fa181e9fef93f70bc2cd9fd2Andrew Trick else if(!IsSigned && OBO->hasNoUnsignedWrap()) 97720151da8c38287b9fa181e9fef93f70bc2cd9fd2Andrew Trick ExtendOperExpr = SE->getZeroExtendExpr( 97820151da8c38287b9fa181e9fef93f70bc2cd9fd2Andrew Trick SE->getSCEV(DU.NarrowUse->getOperand(ExtendOperIdx)), WideType); 97920151da8c38287b9fa181e9fef93f70bc2cd9fd2Andrew Trick else 98020151da8c38287b9fa181e9fef93f70bc2cd9fd2Andrew Trick return 0; 98120151da8c38287b9fa181e9fef93f70bc2cd9fd2Andrew Trick 98220151da8c38287b9fa181e9fef93f70bc2cd9fd2Andrew Trick const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>( 98320151da8c38287b9fa181e9fef93f70bc2cd9fd2Andrew Trick SE->getAddExpr(SE->getSCEV(DU.WideDef), ExtendOperExpr, 98420151da8c38287b9fa181e9fef93f70bc2cd9fd2Andrew Trick IsSigned ? SCEV::FlagNSW : SCEV::FlagNUW)); 98520151da8c38287b9fa181e9fef93f70bc2cd9fd2Andrew Trick 98620151da8c38287b9fa181e9fef93f70bc2cd9fd2Andrew Trick if (!AddRec || AddRec->getLoop() != L) 98720151da8c38287b9fa181e9fef93f70bc2cd9fd2Andrew Trick return 0; 98820151da8c38287b9fa181e9fef93f70bc2cd9fd2Andrew Trick return AddRec; 98920151da8c38287b9fa181e9fef93f70bc2cd9fd2Andrew Trick} 99020151da8c38287b9fa181e9fef93f70bc2cd9fd2Andrew Trick 99139d7802224532c075f4c781c3e51ffed83d17420Andrew Trick/// GetWideRecurrence - Is this instruction potentially interesting from 99239d7802224532c075f4c781c3e51ffed83d17420Andrew Trick/// IVUsers' perspective after widening it's type? In other words, can the 99339d7802224532c075f4c781c3e51ffed83d17420Andrew Trick/// extend be safely hoisted out of the loop with SCEV reducing the value to a 99439d7802224532c075f4c781c3e51ffed83d17420Andrew Trick/// recurrence on the same loop. If so, return the sign or zero extended 99539d7802224532c075f4c781c3e51ffed83d17420Andrew Trick/// recurrence. Otherwise return NULL. 996e0dc2faaa0105c9d1cc56f0b70e93d532a6f8c4cAndrew Trickconst SCEVAddRecExpr *WidenIV::GetWideRecurrence(Instruction *NarrowUse) { 997e0dc2faaa0105c9d1cc56f0b70e93d532a6f8c4cAndrew Trick if (!SE->isSCEVable(NarrowUse->getType())) 998e0dc2faaa0105c9d1cc56f0b70e93d532a6f8c4cAndrew Trick return 0; 999e0dc2faaa0105c9d1cc56f0b70e93d532a6f8c4cAndrew Trick 1000e0dc2faaa0105c9d1cc56f0b70e93d532a6f8c4cAndrew Trick const SCEV *NarrowExpr = SE->getSCEV(NarrowUse); 1001e0dc2faaa0105c9d1cc56f0b70e93d532a6f8c4cAndrew Trick if (SE->getTypeSizeInBits(NarrowExpr->getType()) 1002e0dc2faaa0105c9d1cc56f0b70e93d532a6f8c4cAndrew Trick >= SE->getTypeSizeInBits(WideType)) { 1003e0dc2faaa0105c9d1cc56f0b70e93d532a6f8c4cAndrew Trick // NarrowUse implicitly widens its operand. e.g. a gep with a narrow 1004e0dc2faaa0105c9d1cc56f0b70e93d532a6f8c4cAndrew Trick // index. So don't follow this use. 1005e0dc2faaa0105c9d1cc56f0b70e93d532a6f8c4cAndrew Trick return 0; 1006e0dc2faaa0105c9d1cc56f0b70e93d532a6f8c4cAndrew Trick } 1007e0dc2faaa0105c9d1cc56f0b70e93d532a6f8c4cAndrew Trick 1008e0dc2faaa0105c9d1cc56f0b70e93d532a6f8c4cAndrew Trick const SCEV *WideExpr = IsSigned ? 1009e0dc2faaa0105c9d1cc56f0b70e93d532a6f8c4cAndrew Trick SE->getSignExtendExpr(NarrowExpr, WideType) : 1010e0dc2faaa0105c9d1cc56f0b70e93d532a6f8c4cAndrew Trick SE->getZeroExtendExpr(NarrowExpr, WideType); 1011e0dc2faaa0105c9d1cc56f0b70e93d532a6f8c4cAndrew Trick const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(WideExpr); 1012e0dc2faaa0105c9d1cc56f0b70e93d532a6f8c4cAndrew Trick if (!AddRec || AddRec->getLoop() != L) 1013e0dc2faaa0105c9d1cc56f0b70e93d532a6f8c4cAndrew Trick return 0; 1014e0dc2faaa0105c9d1cc56f0b70e93d532a6f8c4cAndrew Trick return AddRec; 1015e0dc2faaa0105c9d1cc56f0b70e93d532a6f8c4cAndrew Trick} 1016e0dc2faaa0105c9d1cc56f0b70e93d532a6f8c4cAndrew Trick 1017f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick/// WidenIVUse - Determine whether an individual user of the narrow IV can be 1018f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick/// widened. If so, return the wide clone of the user. 101913bcf2e68a88cb87378c9773effa5b79b3091d75Andrew TrickInstruction *WidenIV::WidenIVUse(NarrowIVDefUse DU) { 1020cc359d9fa28a871b18d93da76fd9cf516499e39fAndrew Trick 10214b02915386046fa882a95553a7457ae7d05e9f27Andrew Trick // Stop traversing the def-use chain at inner-loop phis or post-loop phis. 102213bcf2e68a88cb87378c9773effa5b79b3091d75Andrew Trick if (isa<PHINode>(DU.NarrowUse) && 102313bcf2e68a88cb87378c9773effa5b79b3091d75Andrew Trick LI->getLoopFor(DU.NarrowUse->getParent()) != L) 1024f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick return 0; 1025f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick 1026f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick // Our raison d'etre! Eliminate sign and zero extension. 102713bcf2e68a88cb87378c9773effa5b79b3091d75Andrew Trick if (IsSigned ? isa<SExtInst>(DU.NarrowUse) : isa<ZExtInst>(DU.NarrowUse)) { 102813bcf2e68a88cb87378c9773effa5b79b3091d75Andrew Trick Value *NewDef = DU.WideDef; 102913bcf2e68a88cb87378c9773effa5b79b3091d75Andrew Trick if (DU.NarrowUse->getType() != WideType) { 103013bcf2e68a88cb87378c9773effa5b79b3091d75Andrew Trick unsigned CastWidth = SE->getTypeSizeInBits(DU.NarrowUse->getType()); 103103d3d3b361800f28c75d3386978d22e6d57744b7Andrew Trick unsigned IVWidth = SE->getTypeSizeInBits(WideType); 103203d3d3b361800f28c75d3386978d22e6d57744b7Andrew Trick if (CastWidth < IVWidth) { 103303d3d3b361800f28c75d3386978d22e6d57744b7Andrew Trick // The cast isn't as wide as the IV, so insert a Trunc. 103413bcf2e68a88cb87378c9773effa5b79b3091d75Andrew Trick IRBuilder<> Builder(DU.NarrowUse); 103513bcf2e68a88cb87378c9773effa5b79b3091d75Andrew Trick NewDef = Builder.CreateTrunc(DU.WideDef, DU.NarrowUse->getType()); 103603d3d3b361800f28c75d3386978d22e6d57744b7Andrew Trick } 103703d3d3b361800f28c75d3386978d22e6d57744b7Andrew Trick else { 103803d3d3b361800f28c75d3386978d22e6d57744b7Andrew Trick // A wider extend was hidden behind a narrower one. This may induce 103903d3d3b361800f28c75d3386978d22e6d57744b7Andrew Trick // another round of IV widening in which the intermediate IV becomes 104003d3d3b361800f28c75d3386978d22e6d57744b7Andrew Trick // dead. It should be very rare. 104103d3d3b361800f28c75d3386978d22e6d57744b7Andrew Trick DEBUG(dbgs() << "INDVARS: New IV " << *WidePhi 104213bcf2e68a88cb87378c9773effa5b79b3091d75Andrew Trick << " not wide enough to subsume " << *DU.NarrowUse << "\n"); 104313bcf2e68a88cb87378c9773effa5b79b3091d75Andrew Trick DU.NarrowUse->replaceUsesOfWith(DU.NarrowDef, DU.WideDef); 104413bcf2e68a88cb87378c9773effa5b79b3091d75Andrew Trick NewDef = DU.NarrowUse; 104503d3d3b361800f28c75d3386978d22e6d57744b7Andrew Trick } 104603d3d3b361800f28c75d3386978d22e6d57744b7Andrew Trick } 104713bcf2e68a88cb87378c9773effa5b79b3091d75Andrew Trick if (NewDef != DU.NarrowUse) { 104813bcf2e68a88cb87378c9773effa5b79b3091d75Andrew Trick DEBUG(dbgs() << "INDVARS: eliminating " << *DU.NarrowUse 104913bcf2e68a88cb87378c9773effa5b79b3091d75Andrew Trick << " replaced by " << *DU.WideDef << "\n"); 105003d3d3b361800f28c75d3386978d22e6d57744b7Andrew Trick ++NumElimExt; 105113bcf2e68a88cb87378c9773effa5b79b3091d75Andrew Trick DU.NarrowUse->replaceAllUsesWith(NewDef); 105213bcf2e68a88cb87378c9773effa5b79b3091d75Andrew Trick DeadInsts.push_back(DU.NarrowUse); 105303d3d3b361800f28c75d3386978d22e6d57744b7Andrew Trick } 10542fabd464ae9fd33f068066e3fc3d0caa7ea2279dAndrew Trick // Now that the extend is gone, we want to expose it's uses for potential 10552fabd464ae9fd33f068066e3fc3d0caa7ea2279dAndrew Trick // further simplification. We don't need to directly inform SimplifyIVUsers 10562fabd464ae9fd33f068066e3fc3d0caa7ea2279dAndrew Trick // of the new users, because their parent IV will be processed later as a 10572fabd464ae9fd33f068066e3fc3d0caa7ea2279dAndrew Trick // new loop phi. If we preserved IVUsers analysis, we would also want to 10582fabd464ae9fd33f068066e3fc3d0caa7ea2279dAndrew Trick // push the uses of WideDef here. 1059f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick 1060f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick // No further widening is needed. The deceased [sz]ext had done it for us. 1061f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick return 0; 1062f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick } 10634b02915386046fa882a95553a7457ae7d05e9f27Andrew Trick 10644b02915386046fa882a95553a7457ae7d05e9f27Andrew Trick // Does this user itself evaluate to a recurrence after widening? 106513bcf2e68a88cb87378c9773effa5b79b3091d75Andrew Trick const SCEVAddRecExpr *WideAddRec = GetWideRecurrence(DU.NarrowUse); 1066f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick if (!WideAddRec) { 106720151da8c38287b9fa181e9fef93f70bc2cd9fd2Andrew Trick WideAddRec = GetExtendedOperandRecurrence(DU); 106820151da8c38287b9fa181e9fef93f70bc2cd9fd2Andrew Trick } 106920151da8c38287b9fa181e9fef93f70bc2cd9fd2Andrew Trick if (!WideAddRec) { 1070f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick // This user does not evaluate to a recurence after widening, so don't 1071f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick // follow it. Instead insert a Trunc to kill off the original use, 1072f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick // eventually isolating the original narrow IV so it can be removed. 107386c98145b268a0d10e062792f98bc8eea6b639b4Andrew Trick IRBuilder<> Builder(getInsertPointForUses(DU.NarrowUse, DU.NarrowDef, DT)); 107413bcf2e68a88cb87378c9773effa5b79b3091d75Andrew Trick Value *Trunc = Builder.CreateTrunc(DU.WideDef, DU.NarrowDef->getType()); 107513bcf2e68a88cb87378c9773effa5b79b3091d75Andrew Trick DU.NarrowUse->replaceUsesOfWith(DU.NarrowDef, Trunc); 1076f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick return 0; 1077f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick } 1078fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick // Assume block terminators cannot evaluate to a recurrence. We can't to 10794b02915386046fa882a95553a7457ae7d05e9f27Andrew Trick // insert a Trunc after a terminator if there happens to be a critical edge. 108013bcf2e68a88cb87378c9773effa5b79b3091d75Andrew Trick assert(DU.NarrowUse != DU.NarrowUse->getParent()->getTerminator() && 10814b02915386046fa882a95553a7457ae7d05e9f27Andrew Trick "SCEV is not expected to evaluate a block terminator"); 1082cc359d9fa28a871b18d93da76fd9cf516499e39fAndrew Trick 1083fcdc9a44e59ff2846c6f929e91c90ee34e6ba5d5Andrew Trick // Reuse the IV increment that SCEVExpander created as long as it dominates 1084fcdc9a44e59ff2846c6f929e91c90ee34e6ba5d5Andrew Trick // NarrowUse. 1085f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick Instruction *WideUse = 0; 108613bcf2e68a88cb87378c9773effa5b79b3091d75Andrew Trick if (WideAddRec == WideIncExpr && HoistStep(WideInc, DU.NarrowUse, DT)) { 1087f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick WideUse = WideInc; 1088f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick } 1089f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick else { 109013bcf2e68a88cb87378c9773effa5b79b3091d75Andrew Trick WideUse = CloneIVUser(DU); 1091f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick if (!WideUse) 1092f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick return 0; 1093f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick } 10944b02915386046fa882a95553a7457ae7d05e9f27Andrew Trick // Evaluation of WideAddRec ensured that the narrow expression could be 10954b02915386046fa882a95553a7457ae7d05e9f27Andrew Trick // extended outside the loop without overflow. This suggests that the wide use 1096f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick // evaluates to the same expression as the extended narrow use, but doesn't 1097f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick // absolutely guarantee it. Hence the following failsafe check. In rare cases 10982fabd464ae9fd33f068066e3fc3d0caa7ea2279dAndrew Trick // where it fails, we simply throw away the newly created wide use. 1099f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick if (WideAddRec != SE->getSCEV(WideUse)) { 1100f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick DEBUG(dbgs() << "Wide use expression mismatch: " << *WideUse 1101f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick << ": " << *SE->getSCEV(WideUse) << " != " << *WideAddRec << "\n"); 1102f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick DeadInsts.push_back(WideUse); 1103f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick return 0; 1104f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick } 1105f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick 1106f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick // Returning WideUse pushes it on the worklist. 1107f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick return WideUse; 1108f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick} 1109f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick 11104b02915386046fa882a95553a7457ae7d05e9f27Andrew Trick/// pushNarrowIVUsers - Add eligible users of NarrowDef to NarrowIVUsers. 11114b02915386046fa882a95553a7457ae7d05e9f27Andrew Trick/// 11124b02915386046fa882a95553a7457ae7d05e9f27Andrew Trickvoid WidenIV::pushNarrowIVUsers(Instruction *NarrowDef, Instruction *WideDef) { 11134b02915386046fa882a95553a7457ae7d05e9f27Andrew Trick for (Value::use_iterator UI = NarrowDef->use_begin(), 11144b02915386046fa882a95553a7457ae7d05e9f27Andrew Trick UE = NarrowDef->use_end(); UI != UE; ++UI) { 111513bcf2e68a88cb87378c9773effa5b79b3091d75Andrew Trick Instruction *NarrowUse = cast<Instruction>(*UI); 11164b02915386046fa882a95553a7457ae7d05e9f27Andrew Trick 11174b02915386046fa882a95553a7457ae7d05e9f27Andrew Trick // Handle data flow merges and bizarre phi cycles. 111813bcf2e68a88cb87378c9773effa5b79b3091d75Andrew Trick if (!Widened.insert(NarrowUse)) 11194b02915386046fa882a95553a7457ae7d05e9f27Andrew Trick continue; 11204b02915386046fa882a95553a7457ae7d05e9f27Andrew Trick 112113bcf2e68a88cb87378c9773effa5b79b3091d75Andrew Trick NarrowIVUsers.push_back(NarrowIVDefUse(NarrowDef, NarrowUse, WideDef)); 11224b02915386046fa882a95553a7457ae7d05e9f27Andrew Trick } 11234b02915386046fa882a95553a7457ae7d05e9f27Andrew Trick} 11244b02915386046fa882a95553a7457ae7d05e9f27Andrew Trick 1125f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick/// CreateWideIV - Process a single induction variable. First use the 1126f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick/// SCEVExpander to create a wide induction variable that evaluates to the same 1127f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick/// recurrence as the original narrow IV. Then use a worklist to forward 11282fabd464ae9fd33f068066e3fc3d0caa7ea2279dAndrew Trick/// traverse the narrow IV's def-use chain. After WidenIVUse has processed all 1129f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick/// interesting IV users, the narrow IV will be isolated for removal by 1130f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick/// DeleteDeadPHIs. 1131f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick/// 1132f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick/// It would be simpler to delete uses as they are processed, but we must avoid 1133f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick/// invalidating SCEV expressions. 1134f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick/// 11352fabd464ae9fd33f068066e3fc3d0caa7ea2279dAndrew TrickPHINode *WidenIV::CreateWideIV(SCEVExpander &Rewriter) { 1136f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick // Is this phi an induction variable? 1137f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(SE->getSCEV(OrigPhi)); 1138f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick if (!AddRec) 11392fabd464ae9fd33f068066e3fc3d0caa7ea2279dAndrew Trick return NULL; 1140f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick 1141f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick // Widen the induction variable expression. 1142f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick const SCEV *WideIVExpr = IsSigned ? 1143f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick SE->getSignExtendExpr(AddRec, WideType) : 1144f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick SE->getZeroExtendExpr(AddRec, WideType); 1145f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick 1146f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick assert(SE->getEffectiveSCEVType(WideIVExpr->getType()) == WideType && 1147f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick "Expect the new IV expression to preserve its type"); 1148f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick 1149f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick // Can the IV be extended outside the loop without overflow? 1150f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick AddRec = dyn_cast<SCEVAddRecExpr>(WideIVExpr); 1151f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick if (!AddRec || AddRec->getLoop() != L) 11522fabd464ae9fd33f068066e3fc3d0caa7ea2279dAndrew Trick return NULL; 1153f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick 11542fabd464ae9fd33f068066e3fc3d0caa7ea2279dAndrew Trick // An AddRec must have loop-invariant operands. Since this AddRec is 1155f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick // materialized by a loop header phi, the expression cannot have any post-loop 1156f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick // operands, so they must dominate the loop header. 1157f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick assert(SE->properlyDominates(AddRec->getStart(), L->getHeader()) && 1158f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick SE->properlyDominates(AddRec->getStepRecurrence(*SE), L->getHeader()) 1159f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick && "Loop header phi recurrence inputs do not dominate the loop"); 1160f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick 1161f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick // The rewriter provides a value for the desired IV expression. This may 1162f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick // either find an existing phi or materialize a new one. Either way, we 1163f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick // expect a well-formed cyclic phi-with-increments. i.e. any operand not part 1164f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick // of the phi-SCC dominates the loop entry. 1165f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick Instruction *InsertPt = L->getHeader()->begin(); 1166f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick WidePhi = cast<PHINode>(Rewriter.expandCodeFor(AddRec, WideType, InsertPt)); 1167f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick 1168f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick // Remembering the WideIV increment generated by SCEVExpander allows 1169f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick // WidenIVUse to reuse it when widening the narrow IV's increment. We don't 1170f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick // employ a general reuse mechanism because the call above is the only call to 1171f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick // SCEVExpander. Henceforth, we produce 1-to-1 narrow to wide uses. 1172fcdc9a44e59ff2846c6f929e91c90ee34e6ba5d5Andrew Trick if (BasicBlock *LatchBlock = L->getLoopLatch()) { 1173fcdc9a44e59ff2846c6f929e91c90ee34e6ba5d5Andrew Trick WideInc = 1174fcdc9a44e59ff2846c6f929e91c90ee34e6ba5d5Andrew Trick cast<Instruction>(WidePhi->getIncomingValueForBlock(LatchBlock)); 1175fcdc9a44e59ff2846c6f929e91c90ee34e6ba5d5Andrew Trick WideIncExpr = SE->getSCEV(WideInc); 1176fcdc9a44e59ff2846c6f929e91c90ee34e6ba5d5Andrew Trick } 1177f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick 1178f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick DEBUG(dbgs() << "Wide IV: " << *WidePhi << "\n"); 1179f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick ++NumWidened; 1180f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick 1181f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick // Traverse the def-use chain using a worklist starting at the original IV. 11824b02915386046fa882a95553a7457ae7d05e9f27Andrew Trick assert(Widened.empty() && NarrowIVUsers.empty() && "expect initial state" ); 11834b02915386046fa882a95553a7457ae7d05e9f27Andrew Trick 11844b02915386046fa882a95553a7457ae7d05e9f27Andrew Trick Widened.insert(OrigPhi); 11854b02915386046fa882a95553a7457ae7d05e9f27Andrew Trick pushNarrowIVUsers(OrigPhi, WidePhi); 1186f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick 1187f85092c25525f75eef6982ffa40c9b48b87da987Andrew Trick while (!NarrowIVUsers.empty()) { 118813bcf2e68a88cb87378c9773effa5b79b3091d75Andrew Trick NarrowIVDefUse DU = NarrowIVUsers.pop_back_val(); 1189fcdc9a44e59ff2846c6f929e91c90ee34e6ba5d5Andrew Trick 1190fcdc9a44e59ff2846c6f929e91c90ee34e6ba5d5Andrew Trick // Process a def-use edge. This may replace the use, so don't hold a 1191fcdc9a44e59ff2846c6f929e91c90ee34e6ba5d5Andrew Trick // use_iterator across it. 119213bcf2e68a88cb87378c9773effa5b79b3091d75Andrew Trick Instruction *WideUse = WidenIVUse(DU); 1193fcdc9a44e59ff2846c6f929e91c90ee34e6ba5d5Andrew Trick 1194fcdc9a44e59ff2846c6f929e91c90ee34e6ba5d5Andrew Trick // Follow all def-use edges from the previous narrow use. 11954b02915386046fa882a95553a7457ae7d05e9f27Andrew Trick if (WideUse) 119613bcf2e68a88cb87378c9773effa5b79b3091d75Andrew Trick pushNarrowIVUsers(DU.NarrowUse, WideUse); 11974b02915386046fa882a95553a7457ae7d05e9f27Andrew Trick 1198fcdc9a44e59ff2846c6f929e91c90ee34e6ba5d5Andrew Trick // WidenIVUse may have removed the def-use edge. 119913bcf2e68a88cb87378c9773effa5b79b3091d75Andrew Trick if (DU.NarrowDef->use_empty()) 120013bcf2e68a88cb87378c9773effa5b79b3091d75Andrew Trick DeadInsts.push_back(DU.NarrowDef); 1201931e345e76e75391d2a7c96530e305f802b5429dDan Gohman } 12022fabd464ae9fd33f068066e3fc3d0caa7ea2279dAndrew Trick return WidePhi; 1203931e345e76e75391d2a7c96530e305f802b5429dDan Gohman} 1204931e345e76e75391d2a7c96530e305f802b5429dDan Gohman 12051a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick//===----------------------------------------------------------------------===// 12061a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick// Simplification of IV users based on SCEV evaluation. 12071a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick//===----------------------------------------------------------------------===// 12081a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 120906988bcf6a5c74e81cf7e76f06a686aa822ec00aAndrew Trick 12104b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick/// SimplifyAndExtend - Iteratively perform simplification on a worklist of IV 12114b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick/// users. Each successive simplification may push more users which may 12122fabd464ae9fd33f068066e3fc3d0caa7ea2279dAndrew Trick/// themselves be candidates for simplification. 12132fabd464ae9fd33f068066e3fc3d0caa7ea2279dAndrew Trick/// 12144b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick/// Sign/Zero extend elimination is interleaved with IV simplification. 12152fabd464ae9fd33f068066e3fc3d0caa7ea2279dAndrew Trick/// 12164b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trickvoid IndVarSimplify::SimplifyAndExtend(Loop *L, 12174b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick SCEVExpander &Rewriter, 12184b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick LPPassManager &LPM) { 121915832f61775040995bb8aa6056176425bc2c9088Andrew Trick std::map<PHINode *, WideIVInfo> WideIVMap; 122015832f61775040995bb8aa6056176425bc2c9088Andrew Trick 12212fabd464ae9fd33f068066e3fc3d0caa7ea2279dAndrew Trick SmallVector<PHINode*, 8> LoopPhis; 12222fabd464ae9fd33f068066e3fc3d0caa7ea2279dAndrew Trick for (BasicBlock::iterator I = L->getHeader()->begin(); isa<PHINode>(I); ++I) { 12232fabd464ae9fd33f068066e3fc3d0caa7ea2279dAndrew Trick LoopPhis.push_back(cast<PHINode>(I)); 12242fabd464ae9fd33f068066e3fc3d0caa7ea2279dAndrew Trick } 122515832f61775040995bb8aa6056176425bc2c9088Andrew Trick // Each round of simplification iterates through the SimplifyIVUsers worklist 122615832f61775040995bb8aa6056176425bc2c9088Andrew Trick // for all current phis, then determines whether any IVs can be 122715832f61775040995bb8aa6056176425bc2c9088Andrew Trick // widened. Widening adds new phis to LoopPhis, inducing another round of 122815832f61775040995bb8aa6056176425bc2c9088Andrew Trick // simplification on the wide IVs. 12292fabd464ae9fd33f068066e3fc3d0caa7ea2279dAndrew Trick while (!LoopPhis.empty()) { 123015832f61775040995bb8aa6056176425bc2c9088Andrew Trick // Evaluate as many IV expressions as possible before widening any IVs. This 123199a92f67c7ee0d428e18f35c91311a2baba6c03eAndrew Trick // forces SCEV to set no-wrap flags before evaluating sign/zero 123215832f61775040995bb8aa6056176425bc2c9088Andrew Trick // extension. The first time SCEV attempts to normalize sign/zero extension, 123315832f61775040995bb8aa6056176425bc2c9088Andrew Trick // the result becomes final. So for the most predictable results, we delay 123415832f61775040995bb8aa6056176425bc2c9088Andrew Trick // evaluation of sign/zero extend evaluation until needed, and avoid running 12354b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick // other SCEV based analysis prior to SimplifyAndExtend. 123615832f61775040995bb8aa6056176425bc2c9088Andrew Trick do { 123715832f61775040995bb8aa6056176425bc2c9088Andrew Trick PHINode *CurrIV = LoopPhis.pop_back_val(); 12382fabd464ae9fd33f068066e3fc3d0caa7ea2279dAndrew Trick 123915832f61775040995bb8aa6056176425bc2c9088Andrew Trick // Information about sign/zero extensions of CurrIV. 12404b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick WideIVVisitor WIV(SE, TD); 124115832f61775040995bb8aa6056176425bc2c9088Andrew Trick 1242bddb7f82103deb226baa6793f41c5961661167e7Andrew Trick Changed |= simplifyUsersOfIV(CurrIV, SE, &LPM, DeadInsts, &WIV); 124306988bcf6a5c74e81cf7e76f06a686aa822ec00aAndrew Trick 12444b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick if (WIV.WI.WidestNativeType) { 12454b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick WideIVMap[CurrIV] = WIV.WI; 12462fabd464ae9fd33f068066e3fc3d0caa7ea2279dAndrew Trick } 124715832f61775040995bb8aa6056176425bc2c9088Andrew Trick } while(!LoopPhis.empty()); 124815832f61775040995bb8aa6056176425bc2c9088Andrew Trick 124915832f61775040995bb8aa6056176425bc2c9088Andrew Trick for (std::map<PHINode *, WideIVInfo>::const_iterator I = WideIVMap.begin(), 125015832f61775040995bb8aa6056176425bc2c9088Andrew Trick E = WideIVMap.end(); I != E; ++I) { 125115832f61775040995bb8aa6056176425bc2c9088Andrew Trick WidenIV Widener(I->first, I->second, LI, SE, DT, DeadInsts); 12522fabd464ae9fd33f068066e3fc3d0caa7ea2279dAndrew Trick if (PHINode *WidePhi = Widener.CreateWideIV(Rewriter)) { 12532fabd464ae9fd33f068066e3fc3d0caa7ea2279dAndrew Trick Changed = true; 12542fabd464ae9fd33f068066e3fc3d0caa7ea2279dAndrew Trick LoopPhis.push_back(WidePhi); 12552fabd464ae9fd33f068066e3fc3d0caa7ea2279dAndrew Trick } 12562fabd464ae9fd33f068066e3fc3d0caa7ea2279dAndrew Trick } 125715832f61775040995bb8aa6056176425bc2c9088Andrew Trick WideIVMap.clear(); 12582fabd464ae9fd33f068066e3fc3d0caa7ea2279dAndrew Trick } 12592fabd464ae9fd33f068066e3fc3d0caa7ea2279dAndrew Trick} 12602fabd464ae9fd33f068066e3fc3d0caa7ea2279dAndrew Trick 1261037d1c0c7e01cefeff7e538682c9a1e536e14030Andrew Trick/// SimplifyCongruentIVs - Check for congruent phis in this loop header and 12624b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick/// replace them with their chosen representative. 1263037d1c0c7e01cefeff7e538682c9a1e536e14030Andrew Trick/// 1264037d1c0c7e01cefeff7e538682c9a1e536e14030Andrew Trickvoid IndVarSimplify::SimplifyCongruentIVs(Loop *L) { 12656f684b0becc4c1b2ece3ec6dcecf30b19343128dAndrew Trick DenseMap<const SCEV *, PHINode *> ExprToIVMap; 1266037d1c0c7e01cefeff7e538682c9a1e536e14030Andrew Trick for (BasicBlock::iterator I = L->getHeader()->begin(); isa<PHINode>(I); ++I) { 1267037d1c0c7e01cefeff7e538682c9a1e536e14030Andrew Trick PHINode *Phi = cast<PHINode>(I); 12681a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick if (!SE->isSCEVable(Phi->getType())) 12691a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick continue; 12701a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 1271037d1c0c7e01cefeff7e538682c9a1e536e14030Andrew Trick const SCEV *S = SE->getSCEV(Phi); 1272c30a38f34bdfecb99ce49e3ffa479039c9bf0209Chris Lattner std::pair<DenseMap<const SCEV *, PHINode *>::const_iterator, bool> Tmp = 1273c30a38f34bdfecb99ce49e3ffa479039c9bf0209Chris Lattner ExprToIVMap.insert(std::make_pair(S, Phi)); 1274c30a38f34bdfecb99ce49e3ffa479039c9bf0209Chris Lattner if (Tmp.second) 1275037d1c0c7e01cefeff7e538682c9a1e536e14030Andrew Trick continue; 1276c30a38f34bdfecb99ce49e3ffa479039c9bf0209Chris Lattner PHINode *OrigPhi = Tmp.first->second; 1277f22d95749a876975329f6de3a233031171af26a6Andrew Trick 1278f22d95749a876975329f6de3a233031171af26a6Andrew Trick // If one phi derives from the other via GEPs, types may differ. 1279f22d95749a876975329f6de3a233031171af26a6Andrew Trick if (OrigPhi->getType() != Phi->getType()) 1280f22d95749a876975329f6de3a233031171af26a6Andrew Trick continue; 1281f22d95749a876975329f6de3a233031171af26a6Andrew Trick 1282037d1c0c7e01cefeff7e538682c9a1e536e14030Andrew Trick // Replacing the congruent phi is sufficient because acyclic redundancy 1283037d1c0c7e01cefeff7e538682c9a1e536e14030Andrew Trick // elimination, CSE/GVN, should handle the rest. However, once SCEV proves 1284037d1c0c7e01cefeff7e538682c9a1e536e14030Andrew Trick // that a phi is congruent, it's almost certain to be the head of an IV 1285037d1c0c7e01cefeff7e538682c9a1e536e14030Andrew Trick // user cycle that is isomorphic with the original phi. So it's worth 1286037d1c0c7e01cefeff7e538682c9a1e536e14030Andrew Trick // eagerly cleaning up the common case of a single IV increment. 1287037d1c0c7e01cefeff7e538682c9a1e536e14030Andrew Trick if (BasicBlock *LatchBlock = L->getLoopLatch()) { 1288037d1c0c7e01cefeff7e538682c9a1e536e14030Andrew Trick Instruction *OrigInc = 1289037d1c0c7e01cefeff7e538682c9a1e536e14030Andrew Trick cast<Instruction>(OrigPhi->getIncomingValueForBlock(LatchBlock)); 1290037d1c0c7e01cefeff7e538682c9a1e536e14030Andrew Trick Instruction *IsomorphicInc = 1291037d1c0c7e01cefeff7e538682c9a1e536e14030Andrew Trick cast<Instruction>(Phi->getIncomingValueForBlock(LatchBlock)); 1292037d1c0c7e01cefeff7e538682c9a1e536e14030Andrew Trick if (OrigInc != IsomorphicInc && 1293f22d95749a876975329f6de3a233031171af26a6Andrew Trick OrigInc->getType() == IsomorphicInc->getType() && 1294037d1c0c7e01cefeff7e538682c9a1e536e14030Andrew Trick SE->getSCEV(OrigInc) == SE->getSCEV(IsomorphicInc) && 1295037d1c0c7e01cefeff7e538682c9a1e536e14030Andrew Trick HoistStep(OrigInc, IsomorphicInc, DT)) { 1296037d1c0c7e01cefeff7e538682c9a1e536e14030Andrew Trick DEBUG(dbgs() << "INDVARS: Eliminated congruent iv.inc: " 1297037d1c0c7e01cefeff7e538682c9a1e536e14030Andrew Trick << *IsomorphicInc << '\n'); 1298037d1c0c7e01cefeff7e538682c9a1e536e14030Andrew Trick IsomorphicInc->replaceAllUsesWith(OrigInc); 1299037d1c0c7e01cefeff7e538682c9a1e536e14030Andrew Trick DeadInsts.push_back(IsomorphicInc); 1300037d1c0c7e01cefeff7e538682c9a1e536e14030Andrew Trick } 1301037d1c0c7e01cefeff7e538682c9a1e536e14030Andrew Trick } 1302037d1c0c7e01cefeff7e538682c9a1e536e14030Andrew Trick DEBUG(dbgs() << "INDVARS: Eliminated congruent iv: " << *Phi << '\n'); 1303037d1c0c7e01cefeff7e538682c9a1e536e14030Andrew Trick ++NumElimIV; 1304037d1c0c7e01cefeff7e538682c9a1e536e14030Andrew Trick Phi->replaceAllUsesWith(OrigPhi); 1305037d1c0c7e01cefeff7e538682c9a1e536e14030Andrew Trick DeadInsts.push_back(Phi); 1306037d1c0c7e01cefeff7e538682c9a1e536e14030Andrew Trick } 1307037d1c0c7e01cefeff7e538682c9a1e536e14030Andrew Trick} 1308037d1c0c7e01cefeff7e538682c9a1e536e14030Andrew Trick 13091a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick//===----------------------------------------------------------------------===// 13101a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick// LinearFunctionTestReplace and its kin. Rewrite the loop exit condition. 13111a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick//===----------------------------------------------------------------------===// 13121a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 131339d7802224532c075f4c781c3e51ffed83d17420Andrew Trick/// Check for expressions that ScalarEvolution generates to compute 131439d7802224532c075f4c781c3e51ffed83d17420Andrew Trick/// BackedgeTakenInfo. If these expressions have not been reduced, then 131539d7802224532c075f4c781c3e51ffed83d17420Andrew Trick/// expanding them may incur additional cost (albeit in the loop preheader). 13165241b79ebc3ec10469dab49a24e4ed3a8b4c3fa5Andrew Trickstatic bool isHighCostExpansion(const SCEV *S, BranchInst *BI, 13175241b79ebc3ec10469dab49a24e4ed3a8b4c3fa5Andrew Trick ScalarEvolution *SE) { 13185241b79ebc3ec10469dab49a24e4ed3a8b4c3fa5Andrew Trick // If the backedge-taken count is a UDiv, it's very likely a UDiv that 13195241b79ebc3ec10469dab49a24e4ed3a8b4c3fa5Andrew Trick // ScalarEvolution's HowFarToZero or HowManyLessThans produced to compute a 13205241b79ebc3ec10469dab49a24e4ed3a8b4c3fa5Andrew Trick // precise expression, rather than a UDiv from the user's code. If we can't 13215241b79ebc3ec10469dab49a24e4ed3a8b4c3fa5Andrew Trick // find a UDiv in the code with some simple searching, assume the former and 13225241b79ebc3ec10469dab49a24e4ed3a8b4c3fa5Andrew Trick // forego rewriting the loop. 13235241b79ebc3ec10469dab49a24e4ed3a8b4c3fa5Andrew Trick if (isa<SCEVUDivExpr>(S)) { 13245241b79ebc3ec10469dab49a24e4ed3a8b4c3fa5Andrew Trick ICmpInst *OrigCond = dyn_cast<ICmpInst>(BI->getCondition()); 13255241b79ebc3ec10469dab49a24e4ed3a8b4c3fa5Andrew Trick if (!OrigCond) return true; 13265241b79ebc3ec10469dab49a24e4ed3a8b4c3fa5Andrew Trick const SCEV *R = SE->getSCEV(OrigCond->getOperand(1)); 13275241b79ebc3ec10469dab49a24e4ed3a8b4c3fa5Andrew Trick R = SE->getMinusSCEV(R, SE->getConstant(R->getType(), 1)); 13285241b79ebc3ec10469dab49a24e4ed3a8b4c3fa5Andrew Trick if (R != S) { 13295241b79ebc3ec10469dab49a24e4ed3a8b4c3fa5Andrew Trick const SCEV *L = SE->getSCEV(OrigCond->getOperand(0)); 13305241b79ebc3ec10469dab49a24e4ed3a8b4c3fa5Andrew Trick L = SE->getMinusSCEV(L, SE->getConstant(L->getType(), 1)); 13315241b79ebc3ec10469dab49a24e4ed3a8b4c3fa5Andrew Trick if (L != S) 13325241b79ebc3ec10469dab49a24e4ed3a8b4c3fa5Andrew Trick return true; 13335241b79ebc3ec10469dab49a24e4ed3a8b4c3fa5Andrew Trick } 13345241b79ebc3ec10469dab49a24e4ed3a8b4c3fa5Andrew Trick } 13355241b79ebc3ec10469dab49a24e4ed3a8b4c3fa5Andrew Trick 1336fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick if (!DisableIVRewrite || ForceLFTR) 13375241b79ebc3ec10469dab49a24e4ed3a8b4c3fa5Andrew Trick return false; 13385241b79ebc3ec10469dab49a24e4ed3a8b4c3fa5Andrew Trick 13395241b79ebc3ec10469dab49a24e4ed3a8b4c3fa5Andrew Trick // Recurse past add expressions, which commonly occur in the 13405241b79ebc3ec10469dab49a24e4ed3a8b4c3fa5Andrew Trick // BackedgeTakenCount. They may already exist in program code, and if not, 13415241b79ebc3ec10469dab49a24e4ed3a8b4c3fa5Andrew Trick // they are not too expensive rematerialize. 13425241b79ebc3ec10469dab49a24e4ed3a8b4c3fa5Andrew Trick if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(S)) { 13435241b79ebc3ec10469dab49a24e4ed3a8b4c3fa5Andrew Trick for (SCEVAddExpr::op_iterator I = Add->op_begin(), E = Add->op_end(); 13445241b79ebc3ec10469dab49a24e4ed3a8b4c3fa5Andrew Trick I != E; ++I) { 13455241b79ebc3ec10469dab49a24e4ed3a8b4c3fa5Andrew Trick if (isHighCostExpansion(*I, BI, SE)) 13465241b79ebc3ec10469dab49a24e4ed3a8b4c3fa5Andrew Trick return true; 13475241b79ebc3ec10469dab49a24e4ed3a8b4c3fa5Andrew Trick } 13485241b79ebc3ec10469dab49a24e4ed3a8b4c3fa5Andrew Trick return false; 13495241b79ebc3ec10469dab49a24e4ed3a8b4c3fa5Andrew Trick } 13505241b79ebc3ec10469dab49a24e4ed3a8b4c3fa5Andrew Trick 13515241b79ebc3ec10469dab49a24e4ed3a8b4c3fa5Andrew Trick // HowManyLessThans uses a Max expression whenever the loop is not guarded by 13525241b79ebc3ec10469dab49a24e4ed3a8b4c3fa5Andrew Trick // the exit condition. 13535241b79ebc3ec10469dab49a24e4ed3a8b4c3fa5Andrew Trick if (isa<SCEVSMaxExpr>(S) || isa<SCEVUMaxExpr>(S)) 13545241b79ebc3ec10469dab49a24e4ed3a8b4c3fa5Andrew Trick return true; 13555241b79ebc3ec10469dab49a24e4ed3a8b4c3fa5Andrew Trick 13565241b79ebc3ec10469dab49a24e4ed3a8b4c3fa5Andrew Trick // If we haven't recognized an expensive SCEV patter, assume its an expression 13575241b79ebc3ec10469dab49a24e4ed3a8b4c3fa5Andrew Trick // produced by program code. 13585241b79ebc3ec10469dab49a24e4ed3a8b4c3fa5Andrew Trick return false; 13595241b79ebc3ec10469dab49a24e4ed3a8b4c3fa5Andrew Trick} 13605241b79ebc3ec10469dab49a24e4ed3a8b4c3fa5Andrew Trick 13611a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick/// canExpandBackedgeTakenCount - Return true if this loop's backedge taken 13621a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick/// count expression can be safely and cheaply expanded into an instruction 13631a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick/// sequence that can be used by LinearFunctionTestReplace. 13641a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trickstatic bool canExpandBackedgeTakenCount(Loop *L, ScalarEvolution *SE) { 13651a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick const SCEV *BackedgeTakenCount = SE->getBackedgeTakenCount(L); 13661a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick if (isa<SCEVCouldNotCompute>(BackedgeTakenCount) || 13671a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick BackedgeTakenCount->isZero()) 1368a52838285b6dce66821f0b272cb3479af8c3edb2Dan Gohman return false; 1369a52838285b6dce66821f0b272cb3479af8c3edb2Dan Gohman 13701a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick if (!L->getExitingBlock()) 13711a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick return false; 137237da40875873d70b83dc08b2803052bec9b68886Andrew Trick 13731a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // Can't rewrite non-branch yet. 13741a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick BranchInst *BI = dyn_cast<BranchInst>(L->getExitingBlock()->getTerminator()); 13751a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick if (!BI) 13761a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick return false; 137760f8a63e2502d57e879bf52a4a48505b74fa9716Dan Gohman 13785241b79ebc3ec10469dab49a24e4ed3a8b4c3fa5Andrew Trick if (isHighCostExpansion(BackedgeTakenCount, BI, SE)) 13795241b79ebc3ec10469dab49a24e4ed3a8b4c3fa5Andrew Trick return false; 13805241b79ebc3ec10469dab49a24e4ed3a8b4c3fa5Andrew Trick 13811a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick return true; 13821a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick} 138360f8a63e2502d57e879bf52a4a48505b74fa9716Dan Gohman 13841a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick/// getBackedgeIVType - Get the widest type used by the loop test after peeking 13851a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick/// through Truncs. 13861a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick/// 1387fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick/// TODO: Unnecessary when ForceLFTR is removed. 1388db125cfaf57cc83e7dd7453de2d509bc8efd0e5eChris Lattnerstatic Type *getBackedgeIVType(Loop *L) { 13891a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick if (!L->getExitingBlock()) 13901a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick return 0; 13919caed5440d59dac4b388152fe8b993dc0491e5e9Chris Lattner 13921a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // Can't rewrite non-branch yet. 13931a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick BranchInst *BI = dyn_cast<BranchInst>(L->getExitingBlock()->getTerminator()); 13941a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick if (!BI) 13951a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick return 0; 1396156d460c758463eb407590cba2371857daf27d8aAndrew Trick 13971a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick ICmpInst *Cond = dyn_cast<ICmpInst>(BI->getCondition()); 13981a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick if (!Cond) 13991a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick return 0; 140037da40875873d70b83dc08b2803052bec9b68886Andrew Trick 1401db125cfaf57cc83e7dd7453de2d509bc8efd0e5eChris Lattner Type *Ty = 0; 14021a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick for(User::op_iterator OI = Cond->op_begin(), OE = Cond->op_end(); 14031a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick OI != OE; ++OI) { 14041a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick assert((!Ty || Ty == (*OI)->getType()) && "bad icmp operand types"); 14051a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick TruncInst *Trunc = dyn_cast<TruncInst>(*OI); 14061a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick if (!Trunc) 14071a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick continue; 140840bf8b48cdb9961898dba1bc67320be1e49e3da1Chris Lattner 14091a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick return Trunc->getSrcTy(); 14101a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick } 14111a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick return Ty; 14121a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick} 1413a590b79ee227b93c59f60ce1f54cae7a9ebec7c1Dan Gohman 1414fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick/// isLoopInvariant - Perform a quick domtree based check for loop invariance 1415fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick/// assuming that V is used within the loop. LoopInfo::isLoopInvariant() seems 1416fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick/// gratuitous for this purpose. 1417fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trickstatic bool isLoopInvariant(Value *V, Loop *L, DominatorTree *DT) { 1418fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick Instruction *Inst = dyn_cast<Instruction>(V); 1419fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick if (!Inst) 1420fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick return true; 1421fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick 1422fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick return DT->properlyDominates(Inst->getParent(), L->getHeader()); 1423fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick} 1424fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick 1425fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick/// getLoopPhiForCounter - Return the loop header phi IFF IncV adds a loop 1426fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick/// invariant value to the phi. 1427fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trickstatic PHINode *getLoopPhiForCounter(Value *IncV, Loop *L, DominatorTree *DT) { 1428fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick Instruction *IncI = dyn_cast<Instruction>(IncV); 1429fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick if (!IncI) 1430fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick return 0; 1431fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick 1432fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick switch (IncI->getOpcode()) { 1433fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick case Instruction::Add: 1434fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick case Instruction::Sub: 1435fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick break; 1436fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick case Instruction::GetElementPtr: 1437fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick // An IV counter must preserve its type. 1438fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick if (IncI->getNumOperands() == 2) 1439fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick break; 1440fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick default: 1441fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick return 0; 1442fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick } 1443fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick 1444fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick PHINode *Phi = dyn_cast<PHINode>(IncI->getOperand(0)); 1445fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick if (Phi && Phi->getParent() == L->getHeader()) { 1446fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick if (isLoopInvariant(IncI->getOperand(1), L, DT)) 1447fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick return Phi; 1448fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick return 0; 1449fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick } 1450fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick if (IncI->getOpcode() == Instruction::GetElementPtr) 1451fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick return 0; 1452fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick 1453fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick // Allow add/sub to be commuted. 1454fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick Phi = dyn_cast<PHINode>(IncI->getOperand(1)); 1455fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick if (Phi && Phi->getParent() == L->getHeader()) { 1456fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick if (isLoopInvariant(IncI->getOperand(0), L, DT)) 1457fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick return Phi; 1458fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick } 1459fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick return 0; 1460fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick} 1461fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick 1462fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick/// needsLFTR - LinearFunctionTestReplace policy. Return true unless we can show 1463fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick/// that the current exit test is already sufficiently canonical. 1464fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trickstatic bool needsLFTR(Loop *L, DominatorTree *DT) { 1465fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick assert(L->getExitingBlock() && "expected loop exit"); 1466fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick 1467fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick BasicBlock *LatchBlock = L->getLoopLatch(); 1468fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick // Don't bother with LFTR if the loop is not properly simplified. 1469fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick if (!LatchBlock) 1470fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick return false; 1471fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick 1472fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick BranchInst *BI = dyn_cast<BranchInst>(L->getExitingBlock()->getTerminator()); 1473fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick assert(BI && "expected exit branch"); 1474fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick 1475fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick // Do LFTR to simplify the exit condition to an ICMP. 1476fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick ICmpInst *Cond = dyn_cast<ICmpInst>(BI->getCondition()); 1477fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick if (!Cond) 1478fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick return true; 1479fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick 1480fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick // Do LFTR to simplify the exit ICMP to EQ/NE 1481fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick ICmpInst::Predicate Pred = Cond->getPredicate(); 1482fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick if (Pred != ICmpInst::ICMP_NE && Pred != ICmpInst::ICMP_EQ) 1483fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick return true; 1484fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick 1485fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick // Look for a loop invariant RHS 1486fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick Value *LHS = Cond->getOperand(0); 1487fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick Value *RHS = Cond->getOperand(1); 1488fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick if (!isLoopInvariant(RHS, L, DT)) { 1489fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick if (!isLoopInvariant(LHS, L, DT)) 1490fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick return true; 1491fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick std::swap(LHS, RHS); 1492fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick } 1493fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick // Look for a simple IV counter LHS 1494fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick PHINode *Phi = dyn_cast<PHINode>(LHS); 1495fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick if (!Phi) 1496fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick Phi = getLoopPhiForCounter(LHS, L, DT); 1497fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick 1498fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick if (!Phi) 1499fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick return true; 1500fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick 1501fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick // Do LFTR if the exit condition's IV is *not* a simple counter. 1502fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick Value *IncV = Phi->getIncomingValueForBlock(L->getLoopLatch()); 1503fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick return Phi != getLoopPhiForCounter(IncV, L, DT); 1504fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick} 1505fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick 1506fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick/// AlmostDeadIV - Return true if this IV has any uses other than the (soon to 1507fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick/// be rewritten) loop exit test. 1508fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trickstatic bool AlmostDeadIV(PHINode *Phi, BasicBlock *LatchBlock, Value *Cond) { 1509fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick int LatchIdx = Phi->getBasicBlockIndex(LatchBlock); 1510fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick Value *IncV = Phi->getIncomingValue(LatchIdx); 1511fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick 1512fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick for (Value::use_iterator UI = Phi->use_begin(), UE = Phi->use_end(); 1513fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick UI != UE; ++UI) { 1514fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick if (*UI != Cond && *UI != IncV) return false; 1515fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick } 1516fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick 1517fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick for (Value::use_iterator UI = IncV->use_begin(), UE = IncV->use_end(); 1518fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick UI != UE; ++UI) { 1519fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick if (*UI != Cond && *UI != Phi) return false; 1520fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick } 1521fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick return true; 1522fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick} 1523fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick 1524fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick/// FindLoopCounter - Find an affine IV in canonical form. 1525fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick/// 1526fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick/// FIXME: Accept -1 stride and set IVLimit = IVInit - BECount 1527fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick/// 1528fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick/// FIXME: Accept non-unit stride as long as SCEV can reduce BECount * Stride. 1529fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick/// This is difficult in general for SCEV because of potential overflow. But we 1530fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick/// could at least handle constant BECounts. 1531fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trickstatic PHINode * 1532fc933c073e9357a791c0f6b307355ed735e3557fAndrew TrickFindLoopCounter(Loop *L, const SCEV *BECount, 1533fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick ScalarEvolution *SE, DominatorTree *DT, const TargetData *TD) { 1534fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick // I'm not sure how BECount could be a pointer type, but we definitely don't 1535fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick // want to LFTR that. 1536fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick if (BECount->getType()->isPointerTy()) 1537fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick return 0; 1538fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick 1539fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick uint64_t BCWidth = SE->getTypeSizeInBits(BECount->getType()); 1540fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick 1541fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick Value *Cond = 1542fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick cast<BranchInst>(L->getExitingBlock()->getTerminator())->getCondition(); 1543fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick 1544fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick // Loop over all of the PHI nodes, looking for a simple counter. 1545fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick PHINode *BestPhi = 0; 1546fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick const SCEV *BestInit = 0; 1547fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick BasicBlock *LatchBlock = L->getLoopLatch(); 1548fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick assert(LatchBlock && "needsLFTR should guarantee a loop latch"); 1549fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick 1550fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick for (BasicBlock::iterator I = L->getHeader()->begin(); isa<PHINode>(I); ++I) { 1551fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick PHINode *Phi = cast<PHINode>(I); 1552fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick if (!SE->isSCEVable(Phi->getType())) 1553fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick continue; 1554fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick 1555fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(SE->getSCEV(Phi)); 1556fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick if (!AR || AR->getLoop() != L || !AR->isAffine()) 1557fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick continue; 1558fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick 1559fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick // AR may be a pointer type, while BECount is an integer type. 1560fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick // AR may be wider than BECount. With eq/ne tests overflow is immaterial. 1561fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick // AR may not be a narrower type, or we may never exit. 1562fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick uint64_t PhiWidth = SE->getTypeSizeInBits(AR->getType()); 1563fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick if (PhiWidth < BCWidth || (TD && !TD->isLegalInteger(PhiWidth))) 1564fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick continue; 1565fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick 1566fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick const SCEV *Step = dyn_cast<SCEVConstant>(AR->getStepRecurrence(*SE)); 1567fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick if (!Step || !Step->isOne()) 1568fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick continue; 1569fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick 1570fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick int LatchIdx = Phi->getBasicBlockIndex(LatchBlock); 1571fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick Value *IncV = Phi->getIncomingValue(LatchIdx); 1572fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick if (getLoopPhiForCounter(IncV, L, DT) != Phi) 1573fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick continue; 1574fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick 1575fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick const SCEV *Init = AR->getStart(); 1576fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick 1577fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick if (BestPhi && !AlmostDeadIV(BestPhi, LatchBlock, Cond)) { 1578fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick // Don't force a live loop counter if another IV can be used. 1579fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick if (AlmostDeadIV(Phi, LatchBlock, Cond)) 1580fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick continue; 1581fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick 1582fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick // Prefer to count-from-zero. This is a more "canonical" counter form. It 1583fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick // also prefers integer to pointer IVs. 1584fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick if (BestInit->isZero() != Init->isZero()) { 1585fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick if (BestInit->isZero()) 1586fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick continue; 1587fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick } 1588fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick // If two IVs both count from zero or both count from nonzero then the 1589fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick // narrower is likely a dead phi that has been widened. Use the wider phi 1590fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick // to allow the other to be eliminated. 1591fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick if (PhiWidth <= SE->getTypeSizeInBits(BestPhi->getType())) 1592fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick continue; 1593fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick } 1594fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick BestPhi = Phi; 1595fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick BestInit = Init; 1596fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick } 1597fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick return BestPhi; 1598fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick} 1599fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick 16001a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick/// LinearFunctionTestReplace - This method rewrites the exit condition of the 16011a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick/// loop to be a canonical != comparison against the incremented loop induction 16021a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick/// variable. This pass is able to rewrite the exit tests of any loop where the 16031a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick/// SCEV analysis can determine a loop-invariant trip count of the loop, which 16041a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick/// is actually a much broader range than just linear tests. 1605fc933c073e9357a791c0f6b307355ed735e3557fAndrew TrickValue *IndVarSimplify:: 16061a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew TrickLinearFunctionTestReplace(Loop *L, 16071a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick const SCEV *BackedgeTakenCount, 16081a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick PHINode *IndVar, 16091a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick SCEVExpander &Rewriter) { 16101a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick assert(canExpandBackedgeTakenCount(L, SE) && "precondition"); 16111a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick BranchInst *BI = cast<BranchInst>(L->getExitingBlock()->getTerminator()); 16121a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 1613fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick // In DisableIVRewrite mode, IndVar is not necessarily a canonical IV. In this 1614fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick // mode, LFTR can ignore IV overflow and truncate to the width of 1615fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick // BECount. This avoids materializing the add(zext(add)) expression. 1616fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick Type *CntTy = DisableIVRewrite ? 1617fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick BackedgeTakenCount->getType() : IndVar->getType(); 1618fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick 1619fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick const SCEV *IVLimit = BackedgeTakenCount; 1620fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick 16211a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // If the exiting block is not the same as the backedge block, we must compare 16221a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // against the preincremented value, otherwise we prefer to compare against 16231a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // the post-incremented value. 16241a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick Value *CmpIndVar; 16251a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick if (L->getExitingBlock() == L->getLoopLatch()) { 16261a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // Add one to the "backedge-taken" count to get the trip count. 16271a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // If this addition may overflow, we have to be more pessimistic and 16281a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // cast the induction variable before doing the add. 16291a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick const SCEV *N = 1630fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick SE->getAddExpr(IVLimit, SE->getConstant(IVLimit->getType(), 1)); 1631fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick if (CntTy == IVLimit->getType()) 1632fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick IVLimit = N; 1633fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick else { 1634fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick const SCEV *Zero = SE->getConstant(IVLimit->getType(), 0); 1635fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick if ((isa<SCEVConstant>(N) && !N->isZero()) || 1636fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick SE->isLoopEntryGuardedByCond(L, ICmpInst::ICMP_NE, N, Zero)) { 1637fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick // No overflow. Cast the sum. 1638fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick IVLimit = SE->getTruncateOrZeroExtend(N, CntTy); 1639fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick } else { 1640fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick // Potential overflow. Cast before doing the add. 1641fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick IVLimit = SE->getTruncateOrZeroExtend(IVLimit, CntTy); 1642fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick IVLimit = SE->getAddExpr(IVLimit, SE->getConstant(CntTy, 1)); 1643fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick } 16441a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick } 16451a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // The BackedgeTaken expression contains the number of times that the 16461a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // backedge branches to the loop header. This is one less than the 16471a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // number of times the loop executes, so use the incremented indvar. 16481a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick CmpIndVar = IndVar->getIncomingValueForBlock(L->getExitingBlock()); 16491a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick } else { 16501a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // We have to use the preincremented value... 1651fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick IVLimit = SE->getTruncateOrZeroExtend(IVLimit, CntTy); 16521a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick CmpIndVar = IndVar; 16531a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick } 16541a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 1655fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick // For unit stride, IVLimit = Start + BECount with 2's complement overflow. 1656fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick // So for, non-zero start compute the IVLimit here. 1657fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick bool isPtrIV = false; 1658fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick Type *CmpTy = CntTy; 1659fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(SE->getSCEV(IndVar)); 1660fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick assert(AR && AR->getLoop() == L && AR->isAffine() && "bad loop counter"); 1661fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick if (!AR->getStart()->isZero()) { 1662fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick assert(AR->getStepRecurrence(*SE)->isOne() && "only handles unit stride"); 1663fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick const SCEV *IVInit = AR->getStart(); 1664fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick 1665fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick // For pointer types, sign extend BECount in order to materialize a GEP. 1666fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick // Note that for DisableIVRewrite, we never run SCEVExpander on a 1667fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick // pointer type, because we must preserve the existing GEPs. Instead we 1668fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick // directly generate a GEP later. 1669fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick if (IVInit->getType()->isPointerTy()) { 1670fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick isPtrIV = true; 1671fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick CmpTy = SE->getEffectiveSCEVType(IVInit->getType()); 1672fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick IVLimit = SE->getTruncateOrSignExtend(IVLimit, CmpTy); 1673fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick } 1674fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick // For integer types, truncate the IV before computing IVInit + BECount. 1675fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick else { 1676fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick if (SE->getTypeSizeInBits(IVInit->getType()) 1677fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick > SE->getTypeSizeInBits(CmpTy)) 1678fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick IVInit = SE->getTruncateExpr(IVInit, CmpTy); 1679fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick 1680fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick IVLimit = SE->getAddExpr(IVInit, IVLimit); 1681fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick } 1682fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick } 16831a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // Expand the code for the iteration count. 1684fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick IRBuilder<> Builder(BI); 1685fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick 1686fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick assert(SE->isLoopInvariant(IVLimit, L) && 16871a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick "Computed iteration count is not loop invariant!"); 1688fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick Value *ExitCnt = Rewriter.expandCodeFor(IVLimit, CmpTy, BI); 1689fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick 1690fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick // Create a gep for IVInit + IVLimit from on an existing pointer base. 1691fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick assert(isPtrIV == IndVar->getType()->isPointerTy() && 1692fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick "IndVar type must match IVInit type"); 1693fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick if (isPtrIV) { 1694fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick Value *IVStart = IndVar->getIncomingValueForBlock(L->getLoopPreheader()); 1695fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick assert(AR->getStart() == SE->getSCEV(IVStart) && "bad loop counter"); 169641e0d4e788eb473ea2ac9f086f51fd7e11882430Andrew Trick assert(SE->getSizeOfExpr( 169741e0d4e788eb473ea2ac9f086f51fd7e11882430Andrew Trick cast<PointerType>(IVStart->getType())->getElementType())->isOne() 169841e0d4e788eb473ea2ac9f086f51fd7e11882430Andrew Trick && "unit stride pointer IV must be i8*"); 1699fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick 1700fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick Builder.SetInsertPoint(L->getLoopPreheader()->getTerminator()); 1701fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick ExitCnt = Builder.CreateGEP(IVStart, ExitCnt, "lftr.limit"); 1702fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick Builder.SetInsertPoint(BI); 1703fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick } 17041a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 17051a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // Insert a new icmp_ne or icmp_eq instruction before the branch. 1706fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick ICmpInst::Predicate P; 17071a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick if (L->contains(BI->getSuccessor(0))) 1708fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick P = ICmpInst::ICMP_NE; 17091a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick else 1710fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick P = ICmpInst::ICMP_EQ; 17111a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 17121a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick DEBUG(dbgs() << "INDVARS: Rewriting loop exit condition to:\n" 17131a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick << " LHS:" << *CmpIndVar << '\n' 17141a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick << " op:\t" 1715fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick << (P == ICmpInst::ICMP_NE ? "!=" : "==") << "\n" 1716fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick << " RHS:\t" << *ExitCnt << "\n" 1717fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick << " Expr:\t" << *IVLimit << "\n"); 17181a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 1719fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick if (SE->getTypeSizeInBits(CmpIndVar->getType()) 1720fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick > SE->getTypeSizeInBits(CmpTy)) { 1721fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick CmpIndVar = Builder.CreateTrunc(CmpIndVar, CmpTy, "lftr.wideiv"); 1722fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick } 1723fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick 1724fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick Value *Cond = Builder.CreateICmp(P, CmpIndVar, ExitCnt, "exitcond"); 17251a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick Value *OrigCond = BI->getCondition(); 17261a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // It's tempting to use replaceAllUsesWith here to fully replace the old 17271a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // comparison, but that's not immediately safe, since users of the old 17281a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // comparison may not be dominated by the new comparison. Instead, just 17291a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // update the branch to use the new comparison; in the common case this 17301a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // will make old comparison dead. 17311a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick BI->setCondition(Cond); 17321a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick DeadInsts.push_back(OrigCond); 17331a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 17341a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick ++NumLFTR; 17351a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick Changed = true; 17361a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick return Cond; 17371a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick} 17381a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 17391a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick//===----------------------------------------------------------------------===// 17401a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick// SinkUnusedInvariants. A late subpass to cleanup loop preheaders. 17411a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick//===----------------------------------------------------------------------===// 17421a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 17431a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick/// If there's a single exit block, sink any loop-invariant values that 17441a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick/// were defined in the preheader but not used inside the loop into the 17451a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick/// exit block to reduce register pressure in the loop. 17461a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trickvoid IndVarSimplify::SinkUnusedInvariants(Loop *L) { 17471a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick BasicBlock *ExitBlock = L->getExitBlock(); 17481a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick if (!ExitBlock) return; 17491a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 17501a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick BasicBlock *Preheader = L->getLoopPreheader(); 17511a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick if (!Preheader) return; 17521a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 1753b05fdd6babada25da2ec3ba54bb462c2ecfc42a8Bill Wendling Instruction *InsertPt = ExitBlock->getFirstInsertionPt(); 17541a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick BasicBlock::iterator I = Preheader->getTerminator(); 17551a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick while (I != Preheader->begin()) { 17561a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick --I; 17571a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // New instructions were inserted at the end of the preheader. 17581a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick if (isa<PHINode>(I)) 17591a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick break; 17601a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 17611a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // Don't move instructions which might have side effects, since the side 17621a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // effects need to complete before instructions inside the loop. Also don't 17631a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // move instructions which might read memory, since the loop may modify 17641a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // memory. Note that it's okay if the instruction might have undefined 17651a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // behavior: LoopSimplify guarantees that the preheader dominates the exit 17661a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // block. 17671a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick if (I->mayHaveSideEffects() || I->mayReadFromMemory()) 17681a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick continue; 17691a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 17701a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // Skip debug info intrinsics. 17711a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick if (isa<DbgInfoIntrinsic>(I)) 17721a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick continue; 17731a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 17742b18881185b123e5f163eb7b32b3452fc3f339d8Bill Wendling // Skip landingpad instructions. 17752b18881185b123e5f163eb7b32b3452fc3f339d8Bill Wendling if (isa<LandingPadInst>(I)) 17762b18881185b123e5f163eb7b32b3452fc3f339d8Bill Wendling continue; 17772b18881185b123e5f163eb7b32b3452fc3f339d8Bill Wendling 17781a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // Don't sink static AllocaInsts out of the entry block, which would 17791a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // turn them into dynamic allocas! 17801a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick if (AllocaInst *AI = dyn_cast<AllocaInst>(I)) 17811a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick if (AI->isStaticAlloca()) 17821a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick continue; 17831a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 17841a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // Determine if there is a use in or before the loop (direct or 17851a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // otherwise). 17861a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick bool UsedInLoop = false; 17871a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick for (Value::use_iterator UI = I->use_begin(), UE = I->use_end(); 17881a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick UI != UE; ++UI) { 17891a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick User *U = *UI; 17901a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick BasicBlock *UseBB = cast<Instruction>(U)->getParent(); 17911a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick if (PHINode *P = dyn_cast<PHINode>(U)) { 17921a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick unsigned i = 17931a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick PHINode::getIncomingValueNumForOperand(UI.getOperandNo()); 17941a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick UseBB = P->getIncomingBlock(i); 17951a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick } 17961a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick if (UseBB == Preheader || L->contains(UseBB)) { 17971a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick UsedInLoop = true; 17981a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick break; 17991a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick } 18001a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick } 18011a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 18021a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // If there is, the def must remain in the preheader. 18031a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick if (UsedInLoop) 18041a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick continue; 18051a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 18061a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // Otherwise, sink it to the exit block. 18071a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick Instruction *ToMove = I; 18081a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick bool Done = false; 18091a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 18101a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick if (I != Preheader->begin()) { 18111a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // Skip debug info intrinsics. 18121a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick do { 18131a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick --I; 18141a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick } while (isa<DbgInfoIntrinsic>(I) && I != Preheader->begin()); 18151a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 18161a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick if (isa<DbgInfoIntrinsic>(I) && I == Preheader->begin()) 18171a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick Done = true; 18181a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick } else { 18191a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick Done = true; 18201a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick } 18211a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 18221a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick ToMove->moveBefore(InsertPt); 18231a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick if (Done) break; 18241a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick InsertPt = ToMove; 18251a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick } 18261a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick} 18271a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 18281a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick//===----------------------------------------------------------------------===// 18291a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick// IndVarSimplify driver. Manage several subpasses of IV simplification. 18301a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick//===----------------------------------------------------------------------===// 18311a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 18321a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trickbool IndVarSimplify::runOnLoop(Loop *L, LPPassManager &LPM) { 18331a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // If LoopSimplify form is not available, stay out of trouble. Some notes: 18341a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // - LSR currently only supports LoopSimplify-form loops. Indvars' 18351a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // canonicalization can be a pessimization without LSR to "clean up" 18361a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // afterwards. 18371a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // - We depend on having a preheader; in particular, 18381a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // Loop::getCanonicalInductionVariable only supports loops with preheaders, 18391a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // and we're in trouble if we can't find the induction variable even when 18401a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // we've manually inserted one. 18411a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick if (!L->isLoopSimplifyForm()) 18421a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick return false; 18431a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 18441a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick if (!DisableIVRewrite) 18451a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick IU = &getAnalysis<IVUsers>(); 18461a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick LI = &getAnalysis<LoopInfo>(); 18471a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick SE = &getAnalysis<ScalarEvolution>(); 18481a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick DT = &getAnalysis<DominatorTree>(); 18491a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick TD = getAnalysisIfAvailable<TargetData>(); 18501a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 18511a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick DeadInsts.clear(); 18521a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick Changed = false; 18531a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 18541a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // If there are any floating-point recurrences, attempt to 18551a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // transform them to use integer recurrences. 18561a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick RewriteNonIntegerIVs(L); 18571a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 18581a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick const SCEV *BackedgeTakenCount = SE->getBackedgeTakenCount(L); 18591a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 18601a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // Create a rewriter object which we'll use to transform the code with. 18611a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick SCEVExpander Rewriter(*SE, "indvars"); 18621a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 18631a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // Eliminate redundant IV users. 18641a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // 18651a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // Simplification works best when run before other consumers of SCEV. We 18661a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // attempt to avoid evaluating SCEVs for sign/zero extend operations until 18671a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // other expressions involving loop IVs have been evaluated. This helps SCEV 18681a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // set no-wrap flags before normalizing sign/zero extension. 18691a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick if (DisableIVRewrite) { 18701a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick Rewriter.disableCanonicalMode(); 18714b4bb71bcdfd8c17cd4acb6116fc9a56c5fecd47Andrew Trick SimplifyAndExtend(L, Rewriter, LPM); 18721a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick } 18731a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 18741a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // Check to see if this loop has a computable loop-invariant execution count. 18751a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // If so, this means that we can compute the final value of any expressions 18761a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // that are recurrent in the loop, and substitute the exit values from the 18771a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // loop into any instructions outside of the loop that use the final values of 18781a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // the current expressions. 18791a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // 18801a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick if (!isa<SCEVCouldNotCompute>(BackedgeTakenCount)) 18811a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick RewriteLoopExitValues(L, Rewriter); 18821a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 18831a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick // Eliminate redundant IV users. 18841a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick if (!DisableIVRewrite) 1885bddb7f82103deb226baa6793f41c5961661167e7Andrew Trick Changed |= simplifyIVUsers(IU, SE, &LPM, DeadInsts); 18861a54bb28c79d5fc5b1c4e7fb0273ccb6a92c74e0Andrew Trick 18876f684b0becc4c1b2ece3ec6dcecf30b19343128dAndrew Trick // Eliminate redundant IV cycles. 1888037d1c0c7e01cefeff7e538682c9a1e536e14030Andrew Trick if (DisableIVRewrite) 1889037d1c0c7e01cefeff7e538682c9a1e536e14030Andrew Trick SimplifyCongruentIVs(L); 1890037d1c0c7e01cefeff7e538682c9a1e536e14030Andrew Trick 189181db61a2e6d3c95a2738c3559a108e05e9d7a05aDan Gohman // Compute the type of the largest recurrence expression, and decide whether 189281db61a2e6d3c95a2738c3559a108e05e9d7a05aDan Gohman // a canonical induction variable should be inserted. 1893db125cfaf57cc83e7dd7453de2d509bc8efd0e5eChris Lattner Type *LargestType = 0; 189481db61a2e6d3c95a2738c3559a108e05e9d7a05aDan Gohman bool NeedCannIV = false; 1895fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick bool ReuseIVForExit = DisableIVRewrite && !ForceLFTR; 189603d3d3b361800f28c75d3386978d22e6d57744b7Andrew Trick bool ExpandBECount = canExpandBackedgeTakenCount(L, SE); 1897fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick if (ExpandBECount && !ReuseIVForExit) { 189881db61a2e6d3c95a2738c3559a108e05e9d7a05aDan Gohman // If we have a known trip count and a single exit block, we'll be 189981db61a2e6d3c95a2738c3559a108e05e9d7a05aDan Gohman // rewriting the loop exit test condition below, which requires a 190081db61a2e6d3c95a2738c3559a108e05e9d7a05aDan Gohman // canonical induction variable. 19014dfdf242c1917e98f407818eb5b68ae0b4678f26Andrew Trick NeedCannIV = true; 1902db125cfaf57cc83e7dd7453de2d509bc8efd0e5eChris Lattner Type *Ty = BackedgeTakenCount->getType(); 190303d3d3b361800f28c75d3386978d22e6d57744b7Andrew Trick if (DisableIVRewrite) { 190403d3d3b361800f28c75d3386978d22e6d57744b7Andrew Trick // In this mode, SimplifyIVUsers may have already widened the IV used by 190503d3d3b361800f28c75d3386978d22e6d57744b7Andrew Trick // the backedge test and inserted a Trunc on the compare's operand. Get 190603d3d3b361800f28c75d3386978d22e6d57744b7Andrew Trick // the wider type to avoid creating a redundant narrow IV only used by the 190703d3d3b361800f28c75d3386978d22e6d57744b7Andrew Trick // loop test. 190803d3d3b361800f28c75d3386978d22e6d57744b7Andrew Trick LargestType = getBackedgeIVType(L); 190903d3d3b361800f28c75d3386978d22e6d57744b7Andrew Trick } 19104dfdf242c1917e98f407818eb5b68ae0b4678f26Andrew Trick if (!LargestType || 19114dfdf242c1917e98f407818eb5b68ae0b4678f26Andrew Trick SE->getTypeSizeInBits(Ty) > 19124dfdf242c1917e98f407818eb5b68ae0b4678f26Andrew Trick SE->getTypeSizeInBits(LargestType)) 19134dfdf242c1917e98f407818eb5b68ae0b4678f26Andrew Trick LargestType = SE->getEffectiveSCEVType(Ty); 1914f50af088f19f525f3d1026eb61db77e0037a9f43Chris Lattner } 191537da40875873d70b83dc08b2803052bec9b68886Andrew Trick if (!DisableIVRewrite) { 191637da40875873d70b83dc08b2803052bec9b68886Andrew Trick for (IVUsers::const_iterator I = IU->begin(), E = IU->end(); I != E; ++I) { 191737da40875873d70b83dc08b2803052bec9b68886Andrew Trick NeedCannIV = true; 1918db125cfaf57cc83e7dd7453de2d509bc8efd0e5eChris Lattner Type *Ty = 191937da40875873d70b83dc08b2803052bec9b68886Andrew Trick SE->getEffectiveSCEVType(I->getOperandValToReplace()->getType()); 192037da40875873d70b83dc08b2803052bec9b68886Andrew Trick if (!LargestType || 192137da40875873d70b83dc08b2803052bec9b68886Andrew Trick SE->getTypeSizeInBits(Ty) > 1922af79fb5f47b0088c6a8973a7fdbaea96973a429dDan Gohman SE->getTypeSizeInBits(LargestType)) 192337da40875873d70b83dc08b2803052bec9b68886Andrew Trick LargestType = Ty; 192437da40875873d70b83dc08b2803052bec9b68886Andrew Trick } 1925500597a1c39e91a3020587318ed61e737b6c613aChris Lattner } 1926394437ff7eaccfe1de92fe14d0022ca0addf3e41Chris Lattner 1927f451cb870efcf9e0302d25ed05f4cac6bb494e42Dan Gohman // Now that we know the largest of the induction variable expressions 192881db61a2e6d3c95a2738c3559a108e05e9d7a05aDan Gohman // in this loop, insert a canonical induction variable of the largest size. 192943ef3fbae12c7924a25df4563d86084973db9c67Dan Gohman PHINode *IndVar = 0; 193081db61a2e6d3c95a2738c3559a108e05e9d7a05aDan Gohman if (NeedCannIV) { 193185669637139089eaed8def1583ac04266c9654e2Dan Gohman // Check to see if the loop already has any canonical-looking induction 193285669637139089eaed8def1583ac04266c9654e2Dan Gohman // variables. If any are present and wider than the planned canonical 193385669637139089eaed8def1583ac04266c9654e2Dan Gohman // induction variable, temporarily remove them, so that the Rewriter 193485669637139089eaed8def1583ac04266c9654e2Dan Gohman // doesn't attempt to reuse them. 193585669637139089eaed8def1583ac04266c9654e2Dan Gohman SmallVector<PHINode *, 2> OldCannIVs; 193685669637139089eaed8def1583ac04266c9654e2Dan Gohman while (PHINode *OldCannIV = L->getCanonicalInductionVariable()) { 19374d8414f42033a5e744e8e60d2ca188b424c76168Dan Gohman if (SE->getTypeSizeInBits(OldCannIV->getType()) > 19384d8414f42033a5e744e8e60d2ca188b424c76168Dan Gohman SE->getTypeSizeInBits(LargestType)) 19394d8414f42033a5e744e8e60d2ca188b424c76168Dan Gohman OldCannIV->removeFromParent(); 19404d8414f42033a5e744e8e60d2ca188b424c76168Dan Gohman else 194185669637139089eaed8def1583ac04266c9654e2Dan Gohman break; 194285669637139089eaed8def1583ac04266c9654e2Dan Gohman OldCannIVs.push_back(OldCannIV); 19434d8414f42033a5e744e8e60d2ca188b424c76168Dan Gohman } 19444d8414f42033a5e744e8e60d2ca188b424c76168Dan Gohman 1945667d787c0a21cf3f5dfcde03ca471162ba35b614Dan Gohman IndVar = Rewriter.getOrInsertCanonicalInductionVariable(L, LargestType); 19464d8414f42033a5e744e8e60d2ca188b424c76168Dan Gohman 1947c2390b14c91764cba6e4394d05e58e387a7dfb19Dan Gohman ++NumInserted; 1948c2390b14c91764cba6e4394d05e58e387a7dfb19Dan Gohman Changed = true; 1949f67ef318aa29e7cc0c7de76349881959936d9eeeDavid Greene DEBUG(dbgs() << "INDVARS: New CanIV: " << *IndVar << '\n'); 19504d8414f42033a5e744e8e60d2ca188b424c76168Dan Gohman 19514d8414f42033a5e744e8e60d2ca188b424c76168Dan Gohman // Now that the official induction variable is established, reinsert 195285669637139089eaed8def1583ac04266c9654e2Dan Gohman // any old canonical-looking variables after it so that the IR remains 195385669637139089eaed8def1583ac04266c9654e2Dan Gohman // consistent. They will be deleted as part of the dead-PHI deletion at 19544d8414f42033a5e744e8e60d2ca188b424c76168Dan Gohman // the end of the pass. 195585669637139089eaed8def1583ac04266c9654e2Dan Gohman while (!OldCannIVs.empty()) { 195685669637139089eaed8def1583ac04266c9654e2Dan Gohman PHINode *OldCannIV = OldCannIVs.pop_back_val(); 1957b05fdd6babada25da2ec3ba54bb462c2ecfc42a8Bill Wendling OldCannIV->insertBefore(L->getHeader()->getFirstInsertionPt()); 195885669637139089eaed8def1583ac04266c9654e2Dan Gohman } 1959d19534add90a2a894af61523b830887097bb780bDan Gohman } 1960fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick else if (ExpandBECount && ReuseIVForExit && needsLFTR(L, DT)) { 1961fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick IndVar = FindLoopCounter(L, BackedgeTakenCount, SE, DT, TD); 1962fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick } 1963c2390b14c91764cba6e4394d05e58e387a7dfb19Dan Gohman // If we have a trip count expression, rewrite the loop's exit condition 1964c2390b14c91764cba6e4394d05e58e387a7dfb19Dan Gohman // using it. We can currently only handle loops with a single exit. 1965fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick Value *NewICmp = 0; 1966fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick if (ExpandBECount && IndVar) { 19675614769d557600fda3cf73b481581fe32fbff258Andrew Trick // Check preconditions for proper SCEVExpander operation. SCEV does not 19685614769d557600fda3cf73b481581fe32fbff258Andrew Trick // express SCEVExpander's dependencies, such as LoopSimplify. Instead any 19695614769d557600fda3cf73b481581fe32fbff258Andrew Trick // pass that uses the SCEVExpander must do it. This does not work well for 19705614769d557600fda3cf73b481581fe32fbff258Andrew Trick // loop passes because SCEVExpander makes assumptions about all loops, while 19715614769d557600fda3cf73b481581fe32fbff258Andrew Trick // LoopPassManager only forces the current loop to be simplified. 19725614769d557600fda3cf73b481581fe32fbff258Andrew Trick // 19735614769d557600fda3cf73b481581fe32fbff258Andrew Trick // FIXME: SCEV expansion has no way to bail out, so the caller must 19745614769d557600fda3cf73b481581fe32fbff258Andrew Trick // explicitly check any assumptions made by SCEV. Brittle. 19755614769d557600fda3cf73b481581fe32fbff258Andrew Trick const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(BackedgeTakenCount); 19765614769d557600fda3cf73b481581fe32fbff258Andrew Trick if (!AR || AR->getLoop()->getLoopPreheader()) 19775614769d557600fda3cf73b481581fe32fbff258Andrew Trick NewICmp = 19785614769d557600fda3cf73b481581fe32fbff258Andrew Trick LinearFunctionTestReplace(L, BackedgeTakenCount, IndVar, Rewriter); 197981db61a2e6d3c95a2738c3559a108e05e9d7a05aDan Gohman } 1980b12a754cce0c1d5542af605203a47820edba454dAndrew Trick // Rewrite IV-derived expressions. 198137da40875873d70b83dc08b2803052bec9b68886Andrew Trick if (!DisableIVRewrite) 198237da40875873d70b83dc08b2803052bec9b68886Andrew Trick RewriteIVExpressions(L, Rewriter); 1983fcb81f5f4cbac61851b7dec403961cf88e614aa1Chris Lattner 1984b12a754cce0c1d5542af605203a47820edba454dAndrew Trick // Clear the rewriter cache, because values that are in the rewriter's cache 1985b12a754cce0c1d5542af605203a47820edba454dAndrew Trick // can be deleted in the loop below, causing the AssertingVH in the cache to 1986b12a754cce0c1d5542af605203a47820edba454dAndrew Trick // trigger. 1987b12a754cce0c1d5542af605203a47820edba454dAndrew Trick Rewriter.clear(); 1988b12a754cce0c1d5542af605203a47820edba454dAndrew Trick 1989b12a754cce0c1d5542af605203a47820edba454dAndrew Trick // Now that we're done iterating through lists, clean up any instructions 1990b12a754cce0c1d5542af605203a47820edba454dAndrew Trick // which are now dead. 1991b12a754cce0c1d5542af605203a47820edba454dAndrew Trick while (!DeadInsts.empty()) 1992b12a754cce0c1d5542af605203a47820edba454dAndrew Trick if (Instruction *Inst = 1993b12a754cce0c1d5542af605203a47820edba454dAndrew Trick dyn_cast_or_null<Instruction>(&*DeadInsts.pop_back_val())) 1994b12a754cce0c1d5542af605203a47820edba454dAndrew Trick RecursivelyDeleteTriviallyDeadInstructions(Inst); 1995b12a754cce0c1d5542af605203a47820edba454dAndrew Trick 1996667d787c0a21cf3f5dfcde03ca471162ba35b614Dan Gohman // The Rewriter may not be used from this point on. 19973d431384f05c9defc84f36eafe220415cc12ee93Torok Edwin 199881db61a2e6d3c95a2738c3559a108e05e9d7a05aDan Gohman // Loop-invariant instructions in the preheader that aren't used in the 199981db61a2e6d3c95a2738c3559a108e05e9d7a05aDan Gohman // loop may be sunk below the loop to reduce register pressure. 2000667d787c0a21cf3f5dfcde03ca471162ba35b614Dan Gohman SinkUnusedInvariants(L); 200181db61a2e6d3c95a2738c3559a108e05e9d7a05aDan Gohman 200281db61a2e6d3c95a2738c3559a108e05e9d7a05aDan Gohman // For completeness, inform IVUsers of the IV use in the newly-created 200381db61a2e6d3c95a2738c3559a108e05e9d7a05aDan Gohman // loop exit test instruction. 2004fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick if (IU && NewICmp) { 2005fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick ICmpInst *NewICmpInst = dyn_cast<ICmpInst>(NewICmp); 2006fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick if (NewICmpInst) 2007fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick IU->AddUsersIfInteresting(cast<Instruction>(NewICmpInst->getOperand(0))); 2008fc933c073e9357a791c0f6b307355ed735e3557fAndrew Trick } 200981db61a2e6d3c95a2738c3559a108e05e9d7a05aDan Gohman // Clean up dead instructions. 20109fff2187a21f765ed87a25c48552a6942450f3e2Dan Gohman Changed |= DeleteDeadPHIs(L->getHeader()); 201181db61a2e6d3c95a2738c3559a108e05e9d7a05aDan Gohman // Check a post-condition. 2012f6a0dbaaf4f68f8e948a818135b9272776b8a52fAndrew Trick assert(L->isLCSSAForm(*DT) && 2013f6a0dbaaf4f68f8e948a818135b9272776b8a52fAndrew Trick "Indvars did not leave the loop in lcssa form!"); 2014f6a0dbaaf4f68f8e948a818135b9272776b8a52fAndrew Trick 2015f6a0dbaaf4f68f8e948a818135b9272776b8a52fAndrew Trick // Verify that LFTR, and any other change have not interfered with SCEV's 2016f6a0dbaaf4f68f8e948a818135b9272776b8a52fAndrew Trick // ability to compute trip count. 2017f6a0dbaaf4f68f8e948a818135b9272776b8a52fAndrew Trick#ifndef NDEBUG 201875ebc0ec2019f391648d3bc3bac6f6da11cfbabdAndrew Trick if (DisableIVRewrite && VerifyIndvars && 201975ebc0ec2019f391648d3bc3bac6f6da11cfbabdAndrew Trick !isa<SCEVCouldNotCompute>(BackedgeTakenCount)) { 2020f6a0dbaaf4f68f8e948a818135b9272776b8a52fAndrew Trick SE->forgetLoop(L); 2021f6a0dbaaf4f68f8e948a818135b9272776b8a52fAndrew Trick const SCEV *NewBECount = SE->getBackedgeTakenCount(L); 2022f6a0dbaaf4f68f8e948a818135b9272776b8a52fAndrew Trick if (SE->getTypeSizeInBits(BackedgeTakenCount->getType()) < 2023f6a0dbaaf4f68f8e948a818135b9272776b8a52fAndrew Trick SE->getTypeSizeInBits(NewBECount->getType())) 2024f6a0dbaaf4f68f8e948a818135b9272776b8a52fAndrew Trick NewBECount = SE->getTruncateOrNoop(NewBECount, 2025f6a0dbaaf4f68f8e948a818135b9272776b8a52fAndrew Trick BackedgeTakenCount->getType()); 2026f6a0dbaaf4f68f8e948a818135b9272776b8a52fAndrew Trick else 2027f6a0dbaaf4f68f8e948a818135b9272776b8a52fAndrew Trick BackedgeTakenCount = SE->getTruncateOrNoop(BackedgeTakenCount, 2028f6a0dbaaf4f68f8e948a818135b9272776b8a52fAndrew Trick NewBECount->getType()); 2029f6a0dbaaf4f68f8e948a818135b9272776b8a52fAndrew Trick assert(BackedgeTakenCount == NewBECount && "indvars must preserve SCEV"); 2030f6a0dbaaf4f68f8e948a818135b9272776b8a52fAndrew Trick } 2031f6a0dbaaf4f68f8e948a818135b9272776b8a52fAndrew Trick#endif 2032f6a0dbaaf4f68f8e948a818135b9272776b8a52fAndrew Trick 203381db61a2e6d3c95a2738c3559a108e05e9d7a05aDan Gohman return Changed; 203481db61a2e6d3c95a2738c3559a108e05e9d7a05aDan Gohman} 2035