SimplifyCFG.cpp revision 007349dafda47296177fd7481aff9764d4179f42
101d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner//===- SimplifyCFG.cpp - Code to perform CFG simplification ---------------===// 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//===----------------------------------------------------------------------===// 901d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner// 10bb190ac8dafdcc5e604da3695987d69ee8632195Chris Lattner// Peephole optimize the CFG. 1101d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner// 1201d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner//===----------------------------------------------------------------------===// 1301d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner 14218a8223e62c41ae6318e28e8f4c672fcfbb5082Chris Lattner#define DEBUG_TYPE "simplifycfg" 1501d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner#include "llvm/Transforms/Utils/Local.h" 16723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner#include "llvm/Constants.h" 17723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner#include "llvm/Instructions.h" 18383d7ed9158576aef5cde872548225a17e3c0155Devang Patel#include "llvm/IntrinsicInst.h" 190d56008f53587531718ec36af82cc24576580b36Chris Lattner#include "llvm/Type.h" 20c10305743c313558405079452138f03124e87581Reid Spencer#include "llvm/DerivedTypes.h" 21f8bc3008214c8327ff987573a111fc0dcefb7d25Dale Johannesen#include "llvm/GlobalVariable.h" 22302ba6fc1cb26248b0d6524fc42c740370926d6dChris Lattner#include "llvm/Analysis/InstructionSimplify.h" 2310fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer#include "llvm/Analysis/ValueTracking.h" 2458e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen#include "llvm/Target/TargetData.h" 25eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner#include "llvm/Transforms/Utils/BasicBlockUtils.h" 262c63566e406974caa70ee27f35af28112e80f951Dan Gohman#include "llvm/ADT/DenseMap.h" 2793e985f1b17aef62d58e3198a4604f9f6cfe8d19Chris Lattner#include "llvm/ADT/SmallVector.h" 28c9951231822215d6aea7a9b50947c18d8d745609Chris Lattner#include "llvm/ADT/SmallPtrSet.h" 29502a4f5162498ec420e3cb22f667808d726dd7daEvan Cheng#include "llvm/ADT/Statistic.h" 306d4d21e29d4840236ab6f15c5247379820021d0cChris Lattner#include "llvm/ADT/STLExtras.h" 31302ba6fc1cb26248b0d6524fc42c740370926d6dChris Lattner#include "llvm/Support/CFG.h" 32c3f507f98a0747bd256e1c13536060b6fc5c4b62Evan Cheng#include "llvm/Support/CommandLine.h" 33e27db74a60c44d2b5d2700ecde11b1adce0d0d59Chris Lattner#include "llvm/Support/ConstantRange.h" 34302ba6fc1cb26248b0d6524fc42c740370926d6dChris Lattner#include "llvm/Support/Debug.h" 353e410c6607192bbf28ba3708245cb70a0f983556Devang Patel#include "llvm/Support/IRBuilder.h" 36302ba6fc1cb26248b0d6524fc42c740370926d6dChris Lattner#include "llvm/Support/raw_ostream.h" 3701d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner#include <algorithm> 38d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner#include <set> 39698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner#include <map> 40f7703df4968084c18c248c1feea9961c19a32e6aChris Lattnerusing namespace llvm; 41d0fde30ce850b78371fd1386338350591f9ff494Brian Gaeke 4257808b3da00d7abd01382d3ed5e70bfb0b2beb4bPeter Collingbournestatic cl::opt<unsigned> 4357808b3da00d7abd01382d3ed5e70bfb0b2beb4bPeter CollingbournePHINodeFoldingThreshold("phi-node-folding-threshold", cl::Hidden, cl::init(1), 4457808b3da00d7abd01382d3ed5e70bfb0b2beb4bPeter Collingbourne cl::desc("Control the amount of phi node folding to perform (default = 1)")); 4557808b3da00d7abd01382d3ed5e70bfb0b2beb4bPeter Collingbourne 46c3f507f98a0747bd256e1c13536060b6fc5c4b62Evan Chengstatic cl::opt<bool> 47c3f507f98a0747bd256e1c13536060b6fc5c4b62Evan ChengDupRet("simplifycfg-dup-ret", cl::Hidden, cl::init(false), 48c3f507f98a0747bd256e1c13536060b6fc5c4b62Evan Cheng cl::desc("Duplicate return instructions into unconditional branches")); 49c3f507f98a0747bd256e1c13536060b6fc5c4b62Evan Cheng 50502a4f5162498ec420e3cb22f667808d726dd7daEvan ChengSTATISTIC(NumSpeculations, "Number of speculative executed instructions"); 51502a4f5162498ec420e3cb22f667808d726dd7daEvan Cheng 5258e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesennamespace { 5358e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesenclass SimplifyCFGOpt { 5458e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen const TargetData *const TD; 5558e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen 5658e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen Value *isValueEqualityComparison(TerminatorInst *TI); 5758e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen BasicBlock *GetValueEqualityComparisonCases(TerminatorInst *TI, 5858e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen std::vector<std::pair<ConstantInt*, BasicBlock*> > &Cases); 5958e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen bool SimplifyEqualityComparisonWithOnlyPredecessor(TerminatorInst *TI, 60007349dafda47296177fd7481aff9764d4179f42Devang Patel BasicBlock *Pred, 61007349dafda47296177fd7481aff9764d4179f42Devang Patel IRBuilder<> &Builder); 6258e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen bool FoldValueComparisonIntoPredecessors(TerminatorInst *TI); 6358e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen 643d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner bool SimplifyReturn(ReturnInst *RI); 65d46ba26a6b513086ad575e5db0069b03d41fca13Devang Patel bool SimplifyUnwind(UnwindInst *UI, IRBuilder<> &Builder); 663d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner bool SimplifyUnreachable(UnreachableInst *UI); 67007349dafda47296177fd7481aff9764d4179f42Devang Patel bool SimplifySwitch(SwitchInst *SI, IRBuilder<> &Builder); 683d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner bool SimplifyIndirectBr(IndirectBrInst *IBI); 69a23812cfbd23604d2fc103cf232cde8fa270a491Devang Patel bool SimplifyUncondBranch(BranchInst *BI, IRBuilder <> &Builder); 70007349dafda47296177fd7481aff9764d4179f42Devang Patel bool SimplifyCondBranch(BranchInst *BI, IRBuilder <>&Builder); 713d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 7258e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesenpublic: 7358e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen explicit SimplifyCFGOpt(const TargetData *td) : TD(td) {} 7458e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen bool run(BasicBlock *BB); 7558e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen}; 7658e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen} 7758e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen 782bdcb56146279009f233933a101cb3dd54a951cdChris Lattner/// SafeToMergeTerminators - Return true if it is safe to merge these two 792bdcb56146279009f233933a101cb3dd54a951cdChris Lattner/// terminator instructions together. 802bdcb56146279009f233933a101cb3dd54a951cdChris Lattner/// 812bdcb56146279009f233933a101cb3dd54a951cdChris Lattnerstatic bool SafeToMergeTerminators(TerminatorInst *SI1, TerminatorInst *SI2) { 822bdcb56146279009f233933a101cb3dd54a951cdChris Lattner if (SI1 == SI2) return false; // Can't merge with self! 832bdcb56146279009f233933a101cb3dd54a951cdChris Lattner 842bdcb56146279009f233933a101cb3dd54a951cdChris Lattner // It is not safe to merge these two switch instructions if they have a common 852bdcb56146279009f233933a101cb3dd54a951cdChris Lattner // successor, and if that successor has a PHI node, and if *that* PHI node has 862bdcb56146279009f233933a101cb3dd54a951cdChris Lattner // conflicting incoming values from the two switch blocks. 872bdcb56146279009f233933a101cb3dd54a951cdChris Lattner BasicBlock *SI1BB = SI1->getParent(); 882bdcb56146279009f233933a101cb3dd54a951cdChris Lattner BasicBlock *SI2BB = SI2->getParent(); 89c9951231822215d6aea7a9b50947c18d8d745609Chris Lattner SmallPtrSet<BasicBlock*, 16> SI1Succs(succ_begin(SI1BB), succ_end(SI1BB)); 902bdcb56146279009f233933a101cb3dd54a951cdChris Lattner 912bdcb56146279009f233933a101cb3dd54a951cdChris Lattner for (succ_iterator I = succ_begin(SI2BB), E = succ_end(SI2BB); I != E; ++I) 922bdcb56146279009f233933a101cb3dd54a951cdChris Lattner if (SI1Succs.count(*I)) 932bdcb56146279009f233933a101cb3dd54a951cdChris Lattner for (BasicBlock::iterator BBI = (*I)->begin(); 942bdcb56146279009f233933a101cb3dd54a951cdChris Lattner isa<PHINode>(BBI); ++BBI) { 952bdcb56146279009f233933a101cb3dd54a951cdChris Lattner PHINode *PN = cast<PHINode>(BBI); 962bdcb56146279009f233933a101cb3dd54a951cdChris Lattner if (PN->getIncomingValueForBlock(SI1BB) != 972bdcb56146279009f233933a101cb3dd54a951cdChris Lattner PN->getIncomingValueForBlock(SI2BB)) 982bdcb56146279009f233933a101cb3dd54a951cdChris Lattner return false; 992bdcb56146279009f233933a101cb3dd54a951cdChris Lattner } 1002bdcb56146279009f233933a101cb3dd54a951cdChris Lattner 1012bdcb56146279009f233933a101cb3dd54a951cdChris Lattner return true; 1022bdcb56146279009f233933a101cb3dd54a951cdChris Lattner} 1032bdcb56146279009f233933a101cb3dd54a951cdChris Lattner 1042bdcb56146279009f233933a101cb3dd54a951cdChris Lattner/// AddPredecessorToBlock - Update PHI nodes in Succ to indicate that there will 1052bdcb56146279009f233933a101cb3dd54a951cdChris Lattner/// now be entries in it from the 'NewPred' block. The values that will be 1062bdcb56146279009f233933a101cb3dd54a951cdChris Lattner/// flowing into the PHI nodes will be the same as those coming in from 1072bdcb56146279009f233933a101cb3dd54a951cdChris Lattner/// ExistPred, an existing predecessor of Succ. 1082bdcb56146279009f233933a101cb3dd54a951cdChris Lattnerstatic void AddPredecessorToBlock(BasicBlock *Succ, BasicBlock *NewPred, 1092bdcb56146279009f233933a101cb3dd54a951cdChris Lattner BasicBlock *ExistPred) { 1102bdcb56146279009f233933a101cb3dd54a951cdChris Lattner if (!isa<PHINode>(Succ->begin())) return; // Quick exit if nothing to do 1112bdcb56146279009f233933a101cb3dd54a951cdChris Lattner 112093a4385027235459ab6972b2e2fdc79061773cfChris Lattner PHINode *PN; 113093a4385027235459ab6972b2e2fdc79061773cfChris Lattner for (BasicBlock::iterator I = Succ->begin(); 114093a4385027235459ab6972b2e2fdc79061773cfChris Lattner (PN = dyn_cast<PHINode>(I)); ++I) 115093a4385027235459ab6972b2e2fdc79061773cfChris Lattner PN->addIncoming(PN->getIncomingValueForBlock(ExistPred), NewPred); 1162bdcb56146279009f233933a101cb3dd54a951cdChris Lattner} 1172bdcb56146279009f233933a101cb3dd54a951cdChris Lattner 1187e66348cba4384d07b37ad1c186e67ba6d26babdChris Lattner 11973c50a68a7e26b59db54df86e9cc87eed5034bf4Chris Lattner/// GetIfCondition - Given a basic block (BB) with two predecessors (and at 12073c50a68a7e26b59db54df86e9cc87eed5034bf4Chris Lattner/// least one PHI node in it), check to see if the merge at this block is due 121723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner/// to an "if condition". If so, return the boolean condition that determines 122723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner/// which entry into BB will be taken. Also, return by references the block 123723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner/// that will be entered from if the condition is true, and the block that will 124723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner/// be entered if the condition is false. 125fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukman/// 126995ba1bd49e57dee8e301d5f33a7c01d73b7385dChris Lattner/// This does no checking to see if the true/false blocks have large or unsavory 127995ba1bd49e57dee8e301d5f33a7c01d73b7385dChris Lattner/// instructions in them. 12873c50a68a7e26b59db54df86e9cc87eed5034bf4Chris Lattnerstatic Value *GetIfCondition(BasicBlock *BB, BasicBlock *&IfTrue, 12973c50a68a7e26b59db54df86e9cc87eed5034bf4Chris Lattner BasicBlock *&IfFalse) { 13073c50a68a7e26b59db54df86e9cc87eed5034bf4Chris Lattner PHINode *SomePHI = cast<PHINode>(BB->begin()); 13173c50a68a7e26b59db54df86e9cc87eed5034bf4Chris Lattner assert(SomePHI->getNumIncomingValues() == 2 && 132723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner "Function can only handle blocks with 2 predecessors!"); 13373c50a68a7e26b59db54df86e9cc87eed5034bf4Chris Lattner BasicBlock *Pred1 = SomePHI->getIncomingBlock(0); 13473c50a68a7e26b59db54df86e9cc87eed5034bf4Chris Lattner BasicBlock *Pred2 = SomePHI->getIncomingBlock(1); 135723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner 136723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // We can only handle branches. Other control flow will be lowered to 137723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // branches if possible anyway. 138995ba1bd49e57dee8e301d5f33a7c01d73b7385dChris Lattner BranchInst *Pred1Br = dyn_cast<BranchInst>(Pred1->getTerminator()); 139995ba1bd49e57dee8e301d5f33a7c01d73b7385dChris Lattner BranchInst *Pred2Br = dyn_cast<BranchInst>(Pred2->getTerminator()); 140995ba1bd49e57dee8e301d5f33a7c01d73b7385dChris Lattner if (Pred1Br == 0 || Pred2Br == 0) 141723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner return 0; 142723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner 143723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // Eliminate code duplication by ensuring that Pred1Br is conditional if 144723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // either are. 145723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner if (Pred2Br->isConditional()) { 146723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // If both branches are conditional, we don't have an "if statement". In 147723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // reality, we could transform this case, but since the condition will be 148723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // required anyway, we stand no chance of eliminating it, so the xform is 149723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // probably not profitable. 150723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner if (Pred1Br->isConditional()) 151723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner return 0; 152723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner 153723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner std::swap(Pred1, Pred2); 154723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner std::swap(Pred1Br, Pred2Br); 155723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner } 156723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner 157723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner if (Pred1Br->isConditional()) { 158995ba1bd49e57dee8e301d5f33a7c01d73b7385dChris Lattner // The only thing we have to watch out for here is to make sure that Pred2 159995ba1bd49e57dee8e301d5f33a7c01d73b7385dChris Lattner // doesn't have incoming edges from other blocks. If it does, the condition 160995ba1bd49e57dee8e301d5f33a7c01d73b7385dChris Lattner // doesn't dominate BB. 161995ba1bd49e57dee8e301d5f33a7c01d73b7385dChris Lattner if (Pred2->getSinglePredecessor() == 0) 162995ba1bd49e57dee8e301d5f33a7c01d73b7385dChris Lattner return 0; 163995ba1bd49e57dee8e301d5f33a7c01d73b7385dChris Lattner 164723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // If we found a conditional branch predecessor, make sure that it branches 165723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // to BB and Pred2Br. If it doesn't, this isn't an "if statement". 166723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner if (Pred1Br->getSuccessor(0) == BB && 167723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner Pred1Br->getSuccessor(1) == Pred2) { 168723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner IfTrue = Pred1; 169723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner IfFalse = Pred2; 170723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner } else if (Pred1Br->getSuccessor(0) == Pred2 && 171723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner Pred1Br->getSuccessor(1) == BB) { 172723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner IfTrue = Pred2; 173723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner IfFalse = Pred1; 174723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner } else { 175723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // We know that one arm of the conditional goes to BB, so the other must 176723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // go somewhere unrelated, and this must not be an "if statement". 177723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner return 0; 178723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner } 179723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner 180723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner return Pred1Br->getCondition(); 181723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner } 182723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner 183723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // Ok, if we got here, both predecessors end with an unconditional branch to 184723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // BB. Don't panic! If both blocks only have a single (identical) 185723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // predecessor, and THAT is a conditional branch, then we're all ok! 186995ba1bd49e57dee8e301d5f33a7c01d73b7385dChris Lattner BasicBlock *CommonPred = Pred1->getSinglePredecessor(); 187995ba1bd49e57dee8e301d5f33a7c01d73b7385dChris Lattner if (CommonPred == 0 || CommonPred != Pred2->getSinglePredecessor()) 188723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner return 0; 189723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner 190723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // Otherwise, if this is a conditional branch, then we can use it! 191995ba1bd49e57dee8e301d5f33a7c01d73b7385dChris Lattner BranchInst *BI = dyn_cast<BranchInst>(CommonPred->getTerminator()); 192995ba1bd49e57dee8e301d5f33a7c01d73b7385dChris Lattner if (BI == 0) return 0; 193995ba1bd49e57dee8e301d5f33a7c01d73b7385dChris Lattner 194995ba1bd49e57dee8e301d5f33a7c01d73b7385dChris Lattner assert(BI->isConditional() && "Two successors but not conditional?"); 195995ba1bd49e57dee8e301d5f33a7c01d73b7385dChris Lattner if (BI->getSuccessor(0) == Pred1) { 196995ba1bd49e57dee8e301d5f33a7c01d73b7385dChris Lattner IfTrue = Pred1; 197995ba1bd49e57dee8e301d5f33a7c01d73b7385dChris Lattner IfFalse = Pred2; 198995ba1bd49e57dee8e301d5f33a7c01d73b7385dChris Lattner } else { 199995ba1bd49e57dee8e301d5f33a7c01d73b7385dChris Lattner IfTrue = Pred2; 200995ba1bd49e57dee8e301d5f33a7c01d73b7385dChris Lattner IfFalse = Pred1; 201723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner } 202995ba1bd49e57dee8e301d5f33a7c01d73b7385dChris Lattner return BI->getCondition(); 203723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner} 204723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner 2055049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// DominatesMergePoint - If we have a merge point of an "if condition" as 2065049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// accepted above, return true if the specified value dominates the block. We 2075049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// don't handle the true generality of domination here, just a special case 2085049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// which works well enough for us. 2095049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// 2105049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// If AggressiveInsts is non-null, and if V does not dominate BB, we check to 211f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne/// see if V (which must be an instruction) and its recursive operands 212f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne/// that do not dominate BB have a combined cost lower than CostRemaining and 213f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne/// are non-trapping. If both are true, the instruction is inserted into the 214f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne/// set and true is returned. 215f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne/// 216f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne/// The cost for most non-trapping instructions is defined as 1 except for 217f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne/// Select whose cost is 2. 218f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne/// 219f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne/// After this function returns, CostRemaining is decreased by the cost of 220f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne/// V plus its non-dominating operands. If that cost is greater than 221f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne/// CostRemaining, false is returned and CostRemaining is undefined. 2229c07866ef861e072395306e9811c329c7fe5bbe8Chris Lattnerstatic bool DominatesMergePoint(Value *V, BasicBlock *BB, 223f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne SmallPtrSet<Instruction*, 4> *AggressiveInsts, 224f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne unsigned &CostRemaining) { 225570751c2a7d8851bc61e408746a903b0253d2d21Chris Lattner Instruction *I = dyn_cast<Instruction>(V); 226b74b1816305affe25da32c2f29532df41a23cd55Chris Lattner if (!I) { 227b74b1816305affe25da32c2f29532df41a23cd55Chris Lattner // Non-instructions all dominate instructions, but not all constantexprs 228b74b1816305affe25da32c2f29532df41a23cd55Chris Lattner // can be executed unconditionally. 229b74b1816305affe25da32c2f29532df41a23cd55Chris Lattner if (ConstantExpr *C = dyn_cast<ConstantExpr>(V)) 230b74b1816305affe25da32c2f29532df41a23cd55Chris Lattner if (C->canTrap()) 231b74b1816305affe25da32c2f29532df41a23cd55Chris Lattner return false; 232b74b1816305affe25da32c2f29532df41a23cd55Chris Lattner return true; 233b74b1816305affe25da32c2f29532df41a23cd55Chris Lattner } 234570751c2a7d8851bc61e408746a903b0253d2d21Chris Lattner BasicBlock *PBB = I->getParent(); 235570751c2a7d8851bc61e408746a903b0253d2d21Chris Lattner 236da895d63377b421dc50117befb2bec80d2973526Chris Lattner // We don't want to allow weird loops that might have the "if condition" in 237570751c2a7d8851bc61e408746a903b0253d2d21Chris Lattner // the bottom of this block. 238570751c2a7d8851bc61e408746a903b0253d2d21Chris Lattner if (PBB == BB) return false; 239570751c2a7d8851bc61e408746a903b0253d2d21Chris Lattner 240570751c2a7d8851bc61e408746a903b0253d2d21Chris Lattner // If this instruction is defined in a block that contains an unconditional 241570751c2a7d8851bc61e408746a903b0253d2d21Chris Lattner // branch to BB, then it must be in the 'conditional' part of the "if 24244da7ca4213333bcade57a407a890970351db494Chris Lattner // statement". If not, it definitely dominates the region. 24344da7ca4213333bcade57a407a890970351db494Chris Lattner BranchInst *BI = dyn_cast<BranchInst>(PBB->getTerminator()); 24444da7ca4213333bcade57a407a890970351db494Chris Lattner if (BI == 0 || BI->isConditional() || BI->getSuccessor(0) != BB) 24544da7ca4213333bcade57a407a890970351db494Chris Lattner return true; 2460b79a7727d68a507837e827803859424cf3d997bEli Friedman 24744da7ca4213333bcade57a407a890970351db494Chris Lattner // If we aren't allowing aggressive promotion anymore, then don't consider 24844da7ca4213333bcade57a407a890970351db494Chris Lattner // instructions in the 'if region'. 24944da7ca4213333bcade57a407a890970351db494Chris Lattner if (AggressiveInsts == 0) return false; 25044da7ca4213333bcade57a407a890970351db494Chris Lattner 251f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne // If we have seen this instruction before, don't count it again. 252f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne if (AggressiveInsts->count(I)) return true; 253f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne 25444da7ca4213333bcade57a407a890970351db494Chris Lattner // Okay, it looks like the instruction IS in the "condition". Check to 25544da7ca4213333bcade57a407a890970351db494Chris Lattner // see if it's a cheap instruction to unconditionally compute, and if it 25644da7ca4213333bcade57a407a890970351db494Chris Lattner // only uses stuff defined outside of the condition. If so, hoist it out. 25744da7ca4213333bcade57a407a890970351db494Chris Lattner if (!I->isSafeToSpeculativelyExecute()) 25844da7ca4213333bcade57a407a890970351db494Chris Lattner return false; 259fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukman 260f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne unsigned Cost = 0; 261f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne 26244da7ca4213333bcade57a407a890970351db494Chris Lattner switch (I->getOpcode()) { 26344da7ca4213333bcade57a407a890970351db494Chris Lattner default: return false; // Cannot hoist this out safely. 26444da7ca4213333bcade57a407a890970351db494Chris Lattner case Instruction::Load: 26544da7ca4213333bcade57a407a890970351db494Chris Lattner // We have to check to make sure there are no instructions before the 26644da7ca4213333bcade57a407a890970351db494Chris Lattner // load in its basic block, as we are going to hoist the load out to its 26744da7ca4213333bcade57a407a890970351db494Chris Lattner // predecessor. 26844da7ca4213333bcade57a407a890970351db494Chris Lattner if (PBB->getFirstNonPHIOrDbg() != I) 26944da7ca4213333bcade57a407a890970351db494Chris Lattner return false; 270f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne Cost = 1; 27144da7ca4213333bcade57a407a890970351db494Chris Lattner break; 272278be783b5068e6f87f16bc9b69a77e0bc958f9fBenjamin Kramer case Instruction::GetElementPtr: 273278be783b5068e6f87f16bc9b69a77e0bc958f9fBenjamin Kramer // GEPs are cheap if all indices are constant. 274278be783b5068e6f87f16bc9b69a77e0bc958f9fBenjamin Kramer if (!cast<GetElementPtrInst>(I)->hasAllConstantIndices()) 2759b61c550c2f1fa889163a338f5d6c02b50fe961cBenjamin Kramer return false; 276f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne Cost = 1; 2779b61c550c2f1fa889163a338f5d6c02b50fe961cBenjamin Kramer break; 27844da7ca4213333bcade57a407a890970351db494Chris Lattner case Instruction::Add: 27944da7ca4213333bcade57a407a890970351db494Chris Lattner case Instruction::Sub: 28044da7ca4213333bcade57a407a890970351db494Chris Lattner case Instruction::And: 28144da7ca4213333bcade57a407a890970351db494Chris Lattner case Instruction::Or: 28244da7ca4213333bcade57a407a890970351db494Chris Lattner case Instruction::Xor: 28344da7ca4213333bcade57a407a890970351db494Chris Lattner case Instruction::Shl: 28444da7ca4213333bcade57a407a890970351db494Chris Lattner case Instruction::LShr: 28544da7ca4213333bcade57a407a890970351db494Chris Lattner case Instruction::AShr: 28644da7ca4213333bcade57a407a890970351db494Chris Lattner case Instruction::ICmp: 2878a70192b510e2a0f05493b9212e998017f3d178dPeter Collingbourne case Instruction::Trunc: 2888a70192b510e2a0f05493b9212e998017f3d178dPeter Collingbourne case Instruction::ZExt: 2898a70192b510e2a0f05493b9212e998017f3d178dPeter Collingbourne case Instruction::SExt: 290f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne Cost = 1; 29144da7ca4213333bcade57a407a890970351db494Chris Lattner break; // These are all cheap and non-trapping instructions. 292f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne 293f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne case Instruction::Select: 294f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne Cost = 2; 295f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne break; 29644da7ca4213333bcade57a407a890970351db494Chris Lattner } 297723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner 298f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne if (Cost > CostRemaining) 299f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne return false; 300f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne 301f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne CostRemaining -= Cost; 302f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne 303f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne // Okay, we can only really hoist these out if their operands do 304f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne // not take us over the cost threshold. 30544da7ca4213333bcade57a407a890970351db494Chris Lattner for (User::op_iterator i = I->op_begin(), e = I->op_end(); i != e; ++i) 306f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne if (!DominatesMergePoint(*i, BB, AggressiveInsts, CostRemaining)) 30744da7ca4213333bcade57a407a890970351db494Chris Lattner return false; 30844da7ca4213333bcade57a407a890970351db494Chris Lattner // Okay, it's safe to do this! Remember this instruction. 30944da7ca4213333bcade57a407a890970351db494Chris Lattner AggressiveInsts->insert(I); 310723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner return true; 311723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner} 31201d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner 31358e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen/// GetConstantInt - Extract ConstantInt from value, looking through IntToPtr 31458e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen/// and PointerNullValue. Return NULL if value is not a constant int. 31528acc135481691771205dea7cb4edbd3927aa764Chris Lattnerstatic ConstantInt *GetConstantInt(Value *V, const TargetData *TD) { 31658e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen // Normal constant int. 31758e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen ConstantInt *CI = dyn_cast<ConstantInt>(V); 3181df9859c40492511b8aa4321eb76496005d3b75bDuncan Sands if (CI || !TD || !isa<Constant>(V) || !V->getType()->isPointerTy()) 31958e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen return CI; 32058e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen 32158e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen // This is some kind of pointer constant. Turn it into a pointer-sized 32258e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen // ConstantInt if possible. 32358e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen const IntegerType *PtrTy = TD->getIntPtrType(V->getContext()); 32458e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen 32558e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen // Null pointer means 0, see SelectionDAGBuilder::getValue(const Value*). 32658e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen if (isa<ConstantPointerNull>(V)) 32758e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen return ConstantInt::get(PtrTy, 0); 32858e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen 32958e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen // IntToPtr const int. 33058e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) 33158e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen if (CE->getOpcode() == Instruction::IntToPtr) 33258e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen if (ConstantInt *CI = dyn_cast<ConstantInt>(CE->getOperand(0))) { 33358e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen // The constant is very likely to have the right type already. 33458e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen if (CI->getType() == PtrTy) 33558e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen return CI; 33658e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen else 33758e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen return cast<ConstantInt> 33858e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen (ConstantExpr::getIntegerCast(CI, PtrTy, /*isSigned=*/false)); 33958e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen } 34058e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen return 0; 34158e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen} 34258e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen 3430aa749bde7c696e0522df5581ea9cc70f25e62cbChris Lattner/// GatherConstantCompares - Given a potentially 'or'd or 'and'd together 3440aa749bde7c696e0522df5581ea9cc70f25e62cbChris Lattner/// collection of icmp eq/ne instructions that compare a value against a 3450aa749bde7c696e0522df5581ea9cc70f25e62cbChris Lattner/// constant, return the value being compared, and stick the constant into the 3460aa749bde7c696e0522df5581ea9cc70f25e62cbChris Lattner/// Values vector. 34728acc135481691771205dea7cb4edbd3927aa764Chris Lattnerstatic Value * 3480aa749bde7c696e0522df5581ea9cc70f25e62cbChris LattnerGatherConstantCompares(Value *V, std::vector<ConstantInt*> &Vals, Value *&Extra, 34933828bcb24176aae72afac0e4953e4b7f9560ef1Benjamin Kramer const TargetData *TD, bool isEQ, unsigned &UsedICmps) { 3500aa749bde7c696e0522df5581ea9cc70f25e62cbChris Lattner Instruction *I = dyn_cast<Instruction>(V); 3510aa749bde7c696e0522df5581ea9cc70f25e62cbChris Lattner if (I == 0) return 0; 3529a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner 3537312a22ed63607e4ae7b0d9326e42358fd41e245Chris Lattner // If this is an icmp against a constant, handle this as one of the cases. 3540aa749bde7c696e0522df5581ea9cc70f25e62cbChris Lattner if (ICmpInst *ICI = dyn_cast<ICmpInst>(I)) { 355e27db74a60c44d2b5d2700ecde11b1adce0d0d59Chris Lattner if (ConstantInt *C = GetConstantInt(I->getOperand(1), TD)) { 356e27db74a60c44d2b5d2700ecde11b1adce0d0d59Chris Lattner if (ICI->getPredicate() == (isEQ ? ICmpInst::ICMP_EQ:ICmpInst::ICMP_NE)) { 35733828bcb24176aae72afac0e4953e4b7f9560ef1Benjamin Kramer UsedICmps++; 3580aa749bde7c696e0522df5581ea9cc70f25e62cbChris Lattner Vals.push_back(C); 3590aa749bde7c696e0522df5581ea9cc70f25e62cbChris Lattner return I->getOperand(0); 3600aa749bde7c696e0522df5581ea9cc70f25e62cbChris Lattner } 361e27db74a60c44d2b5d2700ecde11b1adce0d0d59Chris Lattner 362e27db74a60c44d2b5d2700ecde11b1adce0d0d59Chris Lattner // If we have "x ult 3" comparison, for example, then we can add 0,1,2 to 363e27db74a60c44d2b5d2700ecde11b1adce0d0d59Chris Lattner // the set. 364e27db74a60c44d2b5d2700ecde11b1adce0d0d59Chris Lattner ConstantRange Span = 365a37029cd24105f645a694abbafbc9bf1212708b0Chris Lattner ConstantRange::makeICmpRegion(ICI->getPredicate(), C->getValue()); 366e27db74a60c44d2b5d2700ecde11b1adce0d0d59Chris Lattner 367e27db74a60c44d2b5d2700ecde11b1adce0d0d59Chris Lattner // If this is an and/!= check then we want to optimize "x ugt 2" into 368e27db74a60c44d2b5d2700ecde11b1adce0d0d59Chris Lattner // x != 0 && x != 1. 369e27db74a60c44d2b5d2700ecde11b1adce0d0d59Chris Lattner if (!isEQ) 370e27db74a60c44d2b5d2700ecde11b1adce0d0d59Chris Lattner Span = Span.inverse(); 371e27db74a60c44d2b5d2700ecde11b1adce0d0d59Chris Lattner 372e27db74a60c44d2b5d2700ecde11b1adce0d0d59Chris Lattner // If there are a ton of values, we don't want to make a ginormous switch. 37314c0987bd9ab50ebb8728e62a0b29d8f7f951984Benjamin Kramer if (Span.getSetSize().ugt(8) || Span.isEmptySet() || 374e27db74a60c44d2b5d2700ecde11b1adce0d0d59Chris Lattner // We don't handle wrapped sets yet. 375e27db74a60c44d2b5d2700ecde11b1adce0d0d59Chris Lattner Span.isWrappedSet()) 376e27db74a60c44d2b5d2700ecde11b1adce0d0d59Chris Lattner return 0; 377e27db74a60c44d2b5d2700ecde11b1adce0d0d59Chris Lattner 378e27db74a60c44d2b5d2700ecde11b1adce0d0d59Chris Lattner for (APInt Tmp = Span.getLower(); Tmp != Span.getUpper(); ++Tmp) 379e27db74a60c44d2b5d2700ecde11b1adce0d0d59Chris Lattner Vals.push_back(ConstantInt::get(V->getContext(), Tmp)); 38033828bcb24176aae72afac0e4953e4b7f9560ef1Benjamin Kramer UsedICmps++; 381e27db74a60c44d2b5d2700ecde11b1adce0d0d59Chris Lattner return I->getOperand(0); 382e27db74a60c44d2b5d2700ecde11b1adce0d0d59Chris Lattner } 383662269d2abb2f220c3a9b727c2a948246128cd05Chris Lattner return 0; 384662269d2abb2f220c3a9b727c2a948246128cd05Chris Lattner } 385662269d2abb2f220c3a9b727c2a948246128cd05Chris Lattner 3867312a22ed63607e4ae7b0d9326e42358fd41e245Chris Lattner // Otherwise, we can only handle an | or &, depending on isEQ. 3870aa749bde7c696e0522df5581ea9cc70f25e62cbChris Lattner if (I->getOpcode() != (isEQ ? Instruction::Or : Instruction::And)) 388662269d2abb2f220c3a9b727c2a948246128cd05Chris Lattner return 0; 389662269d2abb2f220c3a9b727c2a948246128cd05Chris Lattner 3907312a22ed63607e4ae7b0d9326e42358fd41e245Chris Lattner unsigned NumValsBeforeLHS = Vals.size(); 39133828bcb24176aae72afac0e4953e4b7f9560ef1Benjamin Kramer unsigned UsedICmpsBeforeLHS = UsedICmps; 3920aa749bde7c696e0522df5581ea9cc70f25e62cbChris Lattner if (Value *LHS = GatherConstantCompares(I->getOperand(0), Vals, Extra, TD, 39333828bcb24176aae72afac0e4953e4b7f9560ef1Benjamin Kramer isEQ, UsedICmps)) { 3947312a22ed63607e4ae7b0d9326e42358fd41e245Chris Lattner unsigned NumVals = Vals.size(); 39533828bcb24176aae72afac0e4953e4b7f9560ef1Benjamin Kramer unsigned UsedICmpsBeforeRHS = UsedICmps; 3960aa749bde7c696e0522df5581ea9cc70f25e62cbChris Lattner if (Value *RHS = GatherConstantCompares(I->getOperand(1), Vals, Extra, TD, 39733828bcb24176aae72afac0e4953e4b7f9560ef1Benjamin Kramer isEQ, UsedICmps)) { 3980aa749bde7c696e0522df5581ea9cc70f25e62cbChris Lattner if (LHS == RHS) 3990aa749bde7c696e0522df5581ea9cc70f25e62cbChris Lattner return LHS; 40092407e589524d98080f4db943a0e2a3bf18ec8a2Chris Lattner Vals.resize(NumVals); 40133828bcb24176aae72afac0e4953e4b7f9560ef1Benjamin Kramer UsedICmps = UsedICmpsBeforeRHS; 4020aa749bde7c696e0522df5581ea9cc70f25e62cbChris Lattner } 4037312a22ed63607e4ae7b0d9326e42358fd41e245Chris Lattner 4047312a22ed63607e4ae7b0d9326e42358fd41e245Chris Lattner // The RHS of the or/and can't be folded in and we haven't used "Extra" yet, 4057312a22ed63607e4ae7b0d9326e42358fd41e245Chris Lattner // set it and return success. 4067312a22ed63607e4ae7b0d9326e42358fd41e245Chris Lattner if (Extra == 0 || Extra == I->getOperand(1)) { 4077312a22ed63607e4ae7b0d9326e42358fd41e245Chris Lattner Extra = I->getOperand(1); 4087312a22ed63607e4ae7b0d9326e42358fd41e245Chris Lattner return LHS; 4097312a22ed63607e4ae7b0d9326e42358fd41e245Chris Lattner } 4107312a22ed63607e4ae7b0d9326e42358fd41e245Chris Lattner 4117312a22ed63607e4ae7b0d9326e42358fd41e245Chris Lattner Vals.resize(NumValsBeforeLHS); 41233828bcb24176aae72afac0e4953e4b7f9560ef1Benjamin Kramer UsedICmps = UsedICmpsBeforeLHS; 4137312a22ed63607e4ae7b0d9326e42358fd41e245Chris Lattner return 0; 4147312a22ed63607e4ae7b0d9326e42358fd41e245Chris Lattner } 4157312a22ed63607e4ae7b0d9326e42358fd41e245Chris Lattner 4167312a22ed63607e4ae7b0d9326e42358fd41e245Chris Lattner // If the LHS can't be folded in, but Extra is available and RHS can, try to 4177312a22ed63607e4ae7b0d9326e42358fd41e245Chris Lattner // use LHS as Extra. 4187312a22ed63607e4ae7b0d9326e42358fd41e245Chris Lattner if (Extra == 0 || Extra == I->getOperand(0)) { 41992407e589524d98080f4db943a0e2a3bf18ec8a2Chris Lattner Value *OldExtra = Extra; 4207312a22ed63607e4ae7b0d9326e42358fd41e245Chris Lattner Extra = I->getOperand(0); 4217312a22ed63607e4ae7b0d9326e42358fd41e245Chris Lattner if (Value *RHS = GatherConstantCompares(I->getOperand(1), Vals, Extra, TD, 42233828bcb24176aae72afac0e4953e4b7f9560ef1Benjamin Kramer isEQ, UsedICmps)) 4237312a22ed63607e4ae7b0d9326e42358fd41e245Chris Lattner return RHS; 42492407e589524d98080f4db943a0e2a3bf18ec8a2Chris Lattner assert(Vals.size() == NumValsBeforeLHS); 42592407e589524d98080f4db943a0e2a3bf18ec8a2Chris Lattner Extra = OldExtra; 42607e6e56f57e8781a8d7bc601cc9034a3741d84c2Anton Korobeynikov } 4277312a22ed63607e4ae7b0d9326e42358fd41e245Chris Lattner 4280d56008f53587531718ec36af82cc24576580b36Chris Lattner return 0; 4290d56008f53587531718ec36af82cc24576580b36Chris Lattner} 4300aa749bde7c696e0522df5581ea9cc70f25e62cbChris Lattner 431080efb8cea6255b4f1f373d9cb583d6a6302106bEli Friedmanstatic void EraseTerminatorInstAndDCECond(TerminatorInst *TI) { 432080efb8cea6255b4f1f373d9cb583d6a6302106bEli Friedman Instruction* Cond = 0; 433080efb8cea6255b4f1f373d9cb583d6a6302106bEli Friedman if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) { 434080efb8cea6255b4f1f373d9cb583d6a6302106bEli Friedman Cond = dyn_cast<Instruction>(SI->getCondition()); 435080efb8cea6255b4f1f373d9cb583d6a6302106bEli Friedman } else if (BranchInst *BI = dyn_cast<BranchInst>(TI)) { 436080efb8cea6255b4f1f373d9cb583d6a6302106bEli Friedman if (BI->isConditional()) 437080efb8cea6255b4f1f373d9cb583d6a6302106bEli Friedman Cond = dyn_cast<Instruction>(BI->getCondition()); 4387ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel } else if (IndirectBrInst *IBI = dyn_cast<IndirectBrInst>(TI)) { 4397ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel Cond = dyn_cast<Instruction>(IBI->getAddress()); 440080efb8cea6255b4f1f373d9cb583d6a6302106bEli Friedman } 441080efb8cea6255b4f1f373d9cb583d6a6302106bEli Friedman 442080efb8cea6255b4f1f373d9cb583d6a6302106bEli Friedman TI->eraseFromParent(); 443080efb8cea6255b4f1f373d9cb583d6a6302106bEli Friedman if (Cond) RecursivelyDeleteTriviallyDeadInstructions(Cond); 444080efb8cea6255b4f1f373d9cb583d6a6302106bEli Friedman} 445080efb8cea6255b4f1f373d9cb583d6a6302106bEli Friedman 4469fd4955c6ab9a191dec2d5afd4b2027d4b906f2eChris Lattner/// isValueEqualityComparison - Return true if the specified terminator checks 4479fd4955c6ab9a191dec2d5afd4b2027d4b906f2eChris Lattner/// to see if a value is equal to constant integer value. 44858e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund OlesenValue *SimplifyCFGOpt::isValueEqualityComparison(TerminatorInst *TI) { 44958e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen Value *CV = 0; 4504bebf08d152d84970d250feec72fb734cb8a5316Chris Lattner if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) { 4514bebf08d152d84970d250feec72fb734cb8a5316Chris Lattner // Do not permit merging of large switch instructions into their 4524bebf08d152d84970d250feec72fb734cb8a5316Chris Lattner // predecessors unless there is only one predecessor. 45358e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen if (SI->getNumSuccessors()*std::distance(pred_begin(SI->getParent()), 45458e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen pred_end(SI->getParent())) <= 128) 45558e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen CV = SI->getCondition(); 45658e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen } else if (BranchInst *BI = dyn_cast<BranchInst>(TI)) 457542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner if (BI->isConditional() && BI->getCondition()->hasOneUse()) 458e4d87aa2de6e52952dca73716386db09aad5a8fdReid Spencer if (ICmpInst *ICI = dyn_cast<ICmpInst>(BI->getCondition())) 459e4d87aa2de6e52952dca73716386db09aad5a8fdReid Spencer if ((ICI->getPredicate() == ICmpInst::ICMP_EQ || 460e4d87aa2de6e52952dca73716386db09aad5a8fdReid Spencer ICI->getPredicate() == ICmpInst::ICMP_NE) && 46128acc135481691771205dea7cb4edbd3927aa764Chris Lattner GetConstantInt(ICI->getOperand(1), TD)) 46258e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen CV = ICI->getOperand(0); 46358e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen 46458e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen // Unwrap any lossless ptrtoint cast. 46558e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen if (TD && CV && CV->getType() == TD->getIntPtrType(CV->getContext())) 46658e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen if (PtrToIntInst *PTII = dyn_cast<PtrToIntInst>(CV)) 46758e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen CV = PTII->getOperand(0); 46858e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen return CV; 469542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner} 470542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner 4715049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// GetValueEqualityComparisonCases - Given a value comparison instruction, 4725049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// decode all of the 'cases' that it represents and return the 'default' block. 47358e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund OlesenBasicBlock *SimplifyCFGOpt:: 474fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha BrukmanGetValueEqualityComparisonCases(TerminatorInst *TI, 475542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner std::vector<std::pair<ConstantInt*, 476542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner BasicBlock*> > &Cases) { 477542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) { 478542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner Cases.reserve(SI->getNumCases()); 479542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner for (unsigned i = 1, e = SI->getNumCases(); i != e; ++i) 480be54dcc8a9d14592e324d6e6ae1322782e17f09fChris Lattner Cases.push_back(std::make_pair(SI->getCaseValue(i), SI->getSuccessor(i))); 481542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner return SI->getDefaultDest(); 482542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner } 483542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner 484542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner BranchInst *BI = cast<BranchInst>(TI); 485e4d87aa2de6e52952dca73716386db09aad5a8fdReid Spencer ICmpInst *ICI = cast<ICmpInst>(BI->getCondition()); 48628acc135481691771205dea7cb4edbd3927aa764Chris Lattner Cases.push_back(std::make_pair(GetConstantInt(ICI->getOperand(1), TD), 487e4d87aa2de6e52952dca73716386db09aad5a8fdReid Spencer BI->getSuccessor(ICI->getPredicate() == 488e4d87aa2de6e52952dca73716386db09aad5a8fdReid Spencer ICmpInst::ICMP_NE))); 489e4d87aa2de6e52952dca73716386db09aad5a8fdReid Spencer return BI->getSuccessor(ICI->getPredicate() == ICmpInst::ICMP_EQ); 490542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner} 491542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner 492542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner 4935049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// EliminateBlockCases - Given a vector of bb/value pairs, remove any entries 4945049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// in the list that match the specified block. 495fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukmanstatic void EliminateBlockCases(BasicBlock *BB, 496623369ac5669a3667a94a3cbba342dea78845615Chris Lattner std::vector<std::pair<ConstantInt*, BasicBlock*> > &Cases) { 497623369ac5669a3667a94a3cbba342dea78845615Chris Lattner for (unsigned i = 0, e = Cases.size(); i != e; ++i) 498623369ac5669a3667a94a3cbba342dea78845615Chris Lattner if (Cases[i].second == BB) { 499623369ac5669a3667a94a3cbba342dea78845615Chris Lattner Cases.erase(Cases.begin()+i); 500623369ac5669a3667a94a3cbba342dea78845615Chris Lattner --i; --e; 501623369ac5669a3667a94a3cbba342dea78845615Chris Lattner } 502623369ac5669a3667a94a3cbba342dea78845615Chris Lattner} 503623369ac5669a3667a94a3cbba342dea78845615Chris Lattner 5045049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// ValuesOverlap - Return true if there are any keys in C1 that exist in C2 as 5055049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// well. 506623369ac5669a3667a94a3cbba342dea78845615Chris Lattnerstatic bool 507623369ac5669a3667a94a3cbba342dea78845615Chris LattnerValuesOverlap(std::vector<std::pair<ConstantInt*, BasicBlock*> > &C1, 508623369ac5669a3667a94a3cbba342dea78845615Chris Lattner std::vector<std::pair<ConstantInt*, BasicBlock*> > &C2) { 509623369ac5669a3667a94a3cbba342dea78845615Chris Lattner std::vector<std::pair<ConstantInt*, BasicBlock*> > *V1 = &C1, *V2 = &C2; 510623369ac5669a3667a94a3cbba342dea78845615Chris Lattner 511623369ac5669a3667a94a3cbba342dea78845615Chris Lattner // Make V1 be smaller than V2. 512623369ac5669a3667a94a3cbba342dea78845615Chris Lattner if (V1->size() > V2->size()) 513623369ac5669a3667a94a3cbba342dea78845615Chris Lattner std::swap(V1, V2); 514623369ac5669a3667a94a3cbba342dea78845615Chris Lattner 515623369ac5669a3667a94a3cbba342dea78845615Chris Lattner if (V1->size() == 0) return false; 516623369ac5669a3667a94a3cbba342dea78845615Chris Lattner if (V1->size() == 1) { 517623369ac5669a3667a94a3cbba342dea78845615Chris Lattner // Just scan V2. 518623369ac5669a3667a94a3cbba342dea78845615Chris Lattner ConstantInt *TheVal = (*V1)[0].first; 519623369ac5669a3667a94a3cbba342dea78845615Chris Lattner for (unsigned i = 0, e = V2->size(); i != e; ++i) 520623369ac5669a3667a94a3cbba342dea78845615Chris Lattner if (TheVal == (*V2)[i].first) 521623369ac5669a3667a94a3cbba342dea78845615Chris Lattner return true; 522623369ac5669a3667a94a3cbba342dea78845615Chris Lattner } 523623369ac5669a3667a94a3cbba342dea78845615Chris Lattner 524623369ac5669a3667a94a3cbba342dea78845615Chris Lattner // Otherwise, just sort both lists and compare element by element. 525fca20f507ccfd3407511cd1ccb94ab4421388107Chris Lattner array_pod_sort(V1->begin(), V1->end()); 526fca20f507ccfd3407511cd1ccb94ab4421388107Chris Lattner array_pod_sort(V2->begin(), V2->end()); 527623369ac5669a3667a94a3cbba342dea78845615Chris Lattner unsigned i1 = 0, i2 = 0, e1 = V1->size(), e2 = V2->size(); 528623369ac5669a3667a94a3cbba342dea78845615Chris Lattner while (i1 != e1 && i2 != e2) { 529623369ac5669a3667a94a3cbba342dea78845615Chris Lattner if ((*V1)[i1].first == (*V2)[i2].first) 530623369ac5669a3667a94a3cbba342dea78845615Chris Lattner return true; 531623369ac5669a3667a94a3cbba342dea78845615Chris Lattner if ((*V1)[i1].first < (*V2)[i2].first) 532623369ac5669a3667a94a3cbba342dea78845615Chris Lattner ++i1; 533623369ac5669a3667a94a3cbba342dea78845615Chris Lattner else 534623369ac5669a3667a94a3cbba342dea78845615Chris Lattner ++i2; 535623369ac5669a3667a94a3cbba342dea78845615Chris Lattner } 536623369ac5669a3667a94a3cbba342dea78845615Chris Lattner return false; 537623369ac5669a3667a94a3cbba342dea78845615Chris Lattner} 538623369ac5669a3667a94a3cbba342dea78845615Chris Lattner 5395049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// SimplifyEqualityComparisonWithOnlyPredecessor - If TI is known to be a 5405049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// terminator instruction and its block is known to only have a single 5415049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// predecessor block, check to see if that predecessor is also a value 5425049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// comparison with the same value, and if that comparison determines the 5435049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// outcome of this comparison. If so, simplify TI. This does a very limited 5445049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// form of jump threading. 54558e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesenbool SimplifyCFGOpt:: 54658e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund OlesenSimplifyEqualityComparisonWithOnlyPredecessor(TerminatorInst *TI, 547007349dafda47296177fd7481aff9764d4179f42Devang Patel BasicBlock *Pred, 548007349dafda47296177fd7481aff9764d4179f42Devang Patel IRBuilder<> &Builder) { 549623369ac5669a3667a94a3cbba342dea78845615Chris Lattner Value *PredVal = isValueEqualityComparison(Pred->getTerminator()); 550623369ac5669a3667a94a3cbba342dea78845615Chris Lattner if (!PredVal) return false; // Not a value comparison in predecessor. 551623369ac5669a3667a94a3cbba342dea78845615Chris Lattner 552623369ac5669a3667a94a3cbba342dea78845615Chris Lattner Value *ThisVal = isValueEqualityComparison(TI); 553623369ac5669a3667a94a3cbba342dea78845615Chris Lattner assert(ThisVal && "This isn't a value comparison!!"); 554623369ac5669a3667a94a3cbba342dea78845615Chris Lattner if (ThisVal != PredVal) return false; // Different predicates. 555623369ac5669a3667a94a3cbba342dea78845615Chris Lattner 556623369ac5669a3667a94a3cbba342dea78845615Chris Lattner // Find out information about when control will move from Pred to TI's block. 557623369ac5669a3667a94a3cbba342dea78845615Chris Lattner std::vector<std::pair<ConstantInt*, BasicBlock*> > PredCases; 558623369ac5669a3667a94a3cbba342dea78845615Chris Lattner BasicBlock *PredDef = GetValueEqualityComparisonCases(Pred->getTerminator(), 559623369ac5669a3667a94a3cbba342dea78845615Chris Lattner PredCases); 560623369ac5669a3667a94a3cbba342dea78845615Chris Lattner EliminateBlockCases(PredDef, PredCases); // Remove default from cases. 561fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukman 562623369ac5669a3667a94a3cbba342dea78845615Chris Lattner // Find information about how control leaves this block. 563623369ac5669a3667a94a3cbba342dea78845615Chris Lattner std::vector<std::pair<ConstantInt*, BasicBlock*> > ThisCases; 564623369ac5669a3667a94a3cbba342dea78845615Chris Lattner BasicBlock *ThisDef = GetValueEqualityComparisonCases(TI, ThisCases); 565623369ac5669a3667a94a3cbba342dea78845615Chris Lattner EliminateBlockCases(ThisDef, ThisCases); // Remove default from cases. 566623369ac5669a3667a94a3cbba342dea78845615Chris Lattner 567623369ac5669a3667a94a3cbba342dea78845615Chris Lattner // If TI's block is the default block from Pred's comparison, potentially 568623369ac5669a3667a94a3cbba342dea78845615Chris Lattner // simplify TI based on this knowledge. 569623369ac5669a3667a94a3cbba342dea78845615Chris Lattner if (PredDef == TI->getParent()) { 570623369ac5669a3667a94a3cbba342dea78845615Chris Lattner // If we are here, we know that the value is none of those cases listed in 571623369ac5669a3667a94a3cbba342dea78845615Chris Lattner // PredCases. If there are any cases in ThisCases that are in PredCases, we 572623369ac5669a3667a94a3cbba342dea78845615Chris Lattner // can simplify TI. 5739a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (!ValuesOverlap(PredCases, ThisCases)) 5749a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner return false; 5759a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner 5769a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (isa<BranchInst>(TI)) { 5779a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // Okay, one of the successors of this condbr is dead. Convert it to a 5789a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // uncond br. 5799a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner assert(ThisCases.size() == 1 && "Branch can only have one case!"); 5809a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // Insert the new branch. 581007349dafda47296177fd7481aff9764d4179f42Devang Patel Instruction *NI = Builder.CreateBr(ThisDef); 5829a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner (void) NI; 583623369ac5669a3667a94a3cbba342dea78845615Chris Lattner 5849a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // Remove PHI node entries for the dead edge. 5859a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner ThisCases[0].second->removePredecessor(TI->getParent()); 586623369ac5669a3667a94a3cbba342dea78845615Chris Lattner 5879a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner DEBUG(dbgs() << "Threading pred instr: " << *Pred->getTerminator() 5889a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner << "Through successor TI: " << *TI << "Leaving: " << *NI << "\n"); 589623369ac5669a3667a94a3cbba342dea78845615Chris Lattner 5909a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner EraseTerminatorInstAndDCECond(TI); 5919a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner return true; 592623369ac5669a3667a94a3cbba342dea78845615Chris Lattner } 5939a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner 5949a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner SwitchInst *SI = cast<SwitchInst>(TI); 5959a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // Okay, TI has cases that are statically dead, prune them away. 5969a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner SmallPtrSet<Constant*, 16> DeadCases; 597623369ac5669a3667a94a3cbba342dea78845615Chris Lattner for (unsigned i = 0, e = PredCases.size(); i != e; ++i) 5989a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner DeadCases.insert(PredCases[i].first); 5999a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner 6009a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner DEBUG(dbgs() << "Threading pred instr: " << *Pred->getTerminator() 6019a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner << "Through successor TI: " << *TI); 6029a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner 6039a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner for (unsigned i = SI->getNumCases()-1; i != 0; --i) 6049a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (DeadCases.count(SI->getCaseValue(i))) { 6059a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner SI->getSuccessor(i)->removePredecessor(TI->getParent()); 6069a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner SI->removeCase(i); 607623369ac5669a3667a94a3cbba342dea78845615Chris Lattner } 608623369ac5669a3667a94a3cbba342dea78845615Chris Lattner 6099a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner DEBUG(dbgs() << "Leaving: " << *TI << "\n"); 6109a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner return true; 6119a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner } 6129a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner 6139a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // Otherwise, TI's block must correspond to some matched value. Find out 6149a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // which value (or set of values) this is. 6159a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner ConstantInt *TIV = 0; 6169a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner BasicBlock *TIBB = TI->getParent(); 6179a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner for (unsigned i = 0, e = PredCases.size(); i != e; ++i) 6189a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (PredCases[i].second == TIBB) { 6199a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (TIV != 0) 6209a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner return false; // Cannot handle multiple values coming to this block. 6219a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner TIV = PredCases[i].first; 6229a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner } 6239a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner assert(TIV && "No edge from pred to succ?"); 6249a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner 6259a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // Okay, we found the one constant that our value can be if we get into TI's 6269a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // BB. Find out which successor will unconditionally be branched to. 6279a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner BasicBlock *TheRealDest = 0; 6289a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner for (unsigned i = 0, e = ThisCases.size(); i != e; ++i) 6299a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (ThisCases[i].first == TIV) { 6309a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner TheRealDest = ThisCases[i].second; 6319a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner break; 6329a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner } 6339a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner 6349a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // If not handled by any explicit cases, it is handled by the default case. 6359a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (TheRealDest == 0) TheRealDest = ThisDef; 636623369ac5669a3667a94a3cbba342dea78845615Chris Lattner 6379a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // Remove PHI node entries for dead edges. 6389a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner BasicBlock *CheckEdge = TheRealDest; 6399a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner for (succ_iterator SI = succ_begin(TIBB), e = succ_end(TIBB); SI != e; ++SI) 6409a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (*SI != CheckEdge) 6419a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner (*SI)->removePredecessor(TIBB); 6429a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner else 6439a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner CheckEdge = 0; 644623369ac5669a3667a94a3cbba342dea78845615Chris Lattner 6459a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // Insert the new branch. 646007349dafda47296177fd7481aff9764d4179f42Devang Patel Instruction *NI = Builder.CreateBr(TheRealDest); 6479a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner (void) NI; 648623369ac5669a3667a94a3cbba342dea78845615Chris Lattner 6499a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner DEBUG(dbgs() << "Threading pred instr: " << *Pred->getTerminator() 6509a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner << "Through successor TI: " << *TI << "Leaving: " << *NI << "\n"); 651623369ac5669a3667a94a3cbba342dea78845615Chris Lattner 6529a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner EraseTerminatorInstAndDCECond(TI); 6539a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner return true; 654623369ac5669a3667a94a3cbba342dea78845615Chris Lattner} 655623369ac5669a3667a94a3cbba342dea78845615Chris Lattner 656c81f5445a7cbe3ba0252aec030082a40e5019eceDale Johannesennamespace { 657c81f5445a7cbe3ba0252aec030082a40e5019eceDale Johannesen /// ConstantIntOrdering - This class implements a stable ordering of constant 658c81f5445a7cbe3ba0252aec030082a40e5019eceDale Johannesen /// integers that does not depend on their address. This is important for 659c81f5445a7cbe3ba0252aec030082a40e5019eceDale Johannesen /// applications that sort ConstantInt's to ensure uniqueness. 660c81f5445a7cbe3ba0252aec030082a40e5019eceDale Johannesen struct ConstantIntOrdering { 661c81f5445a7cbe3ba0252aec030082a40e5019eceDale Johannesen bool operator()(const ConstantInt *LHS, const ConstantInt *RHS) const { 662c81f5445a7cbe3ba0252aec030082a40e5019eceDale Johannesen return LHS->getValue().ult(RHS->getValue()); 663c81f5445a7cbe3ba0252aec030082a40e5019eceDale Johannesen } 664c81f5445a7cbe3ba0252aec030082a40e5019eceDale Johannesen }; 665c81f5445a7cbe3ba0252aec030082a40e5019eceDale Johannesen} 666a9537cf3fcf9fdaac94749db9fbd34912b1f0f08Dale Johannesen 6676d4d21e29d4840236ab6f15c5247379820021d0cChris Lattnerstatic int ConstantIntSortPredicate(const void *P1, const void *P2) { 6686d4d21e29d4840236ab6f15c5247379820021d0cChris Lattner const ConstantInt *LHS = *(const ConstantInt**)P1; 6696d4d21e29d4840236ab6f15c5247379820021d0cChris Lattner const ConstantInt *RHS = *(const ConstantInt**)P2; 670ba3c8155704e5e2ac24b5069c32bca359b0738edChris Lattner if (LHS->getValue().ult(RHS->getValue())) 671ba3c8155704e5e2ac24b5069c32bca359b0738edChris Lattner return 1; 672ba3c8155704e5e2ac24b5069c32bca359b0738edChris Lattner if (LHS->getValue() == RHS->getValue()) 673ba3c8155704e5e2ac24b5069c32bca359b0738edChris Lattner return 0; 674ba3c8155704e5e2ac24b5069c32bca359b0738edChris Lattner return -1; 6756d4d21e29d4840236ab6f15c5247379820021d0cChris Lattner} 6766d4d21e29d4840236ab6f15c5247379820021d0cChris Lattner 6775049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// FoldValueComparisonIntoPredecessors - The specified terminator is a value 6785049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// equality comparison instruction (either a switch or a branch on "X == c"). 6795049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// See if any of the predecessors of the terminator block are value comparisons 6805049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// on the same value. If so, and if safe to do so, fold them together. 68158e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesenbool SimplifyCFGOpt::FoldValueComparisonIntoPredecessors(TerminatorInst *TI) { 682542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner BasicBlock *BB = TI->getParent(); 683542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner Value *CV = isValueEqualityComparison(TI); // CondVal 684542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner assert(CV && "Not a comparison?"); 685542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner bool Changed = false; 686542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner 6878244243a31d636ce8838a81d4c402274fd391d2bChris Lattner SmallVector<BasicBlock*, 16> Preds(pred_begin(BB), pred_end(BB)); 688542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner while (!Preds.empty()) { 689e9d87f49063cb1bd213d8e9c339b9b63393cc2d9Dan Gohman BasicBlock *Pred = Preds.pop_back_val(); 690fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukman 691542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // See if the predecessor is a comparison with the same value. 692542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner TerminatorInst *PTI = Pred->getTerminator(); 693542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner Value *PCV = isValueEqualityComparison(PTI); // PredCondVal 694542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner 695542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner if (PCV == CV && SafeToMergeTerminators(TI, PTI)) { 696542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // Figure out which 'cases' to copy from SI to PSI. 697542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner std::vector<std::pair<ConstantInt*, BasicBlock*> > BBCases; 698542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner BasicBlock *BBDefault = GetValueEqualityComparisonCases(TI, BBCases); 699542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner 700542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner std::vector<std::pair<ConstantInt*, BasicBlock*> > PredCases; 701542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner BasicBlock *PredDefault = GetValueEqualityComparisonCases(PTI, PredCases); 702542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner 703542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // Based on whether the default edge from PTI goes to BB or not, fill in 704542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // PredCases and PredDefault with the new switch cases we would like to 705542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // build. 7068244243a31d636ce8838a81d4c402274fd391d2bChris Lattner SmallVector<BasicBlock*, 8> NewSuccessors; 707542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner 708542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner if (PredDefault == BB) { 709542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // If this is the default destination from PTI, only the edges in TI 710542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // that don't occur in PTI, or that branch to BB will be activated. 711c81f5445a7cbe3ba0252aec030082a40e5019eceDale Johannesen std::set<ConstantInt*, ConstantIntOrdering> PTIHandled; 712542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner for (unsigned i = 0, e = PredCases.size(); i != e; ++i) 713542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner if (PredCases[i].second != BB) 714542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner PTIHandled.insert(PredCases[i].first); 715542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner else { 716542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // The default destination is BB, we don't need explicit targets. 717542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner std::swap(PredCases[i], PredCases.back()); 718542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner PredCases.pop_back(); 719542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner --i; --e; 720542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner } 721542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner 722542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // Reconstruct the new switch statement we will be building. 723542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner if (PredDefault != BBDefault) { 724542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner PredDefault->removePredecessor(Pred); 725542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner PredDefault = BBDefault; 726542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner NewSuccessors.push_back(BBDefault); 727542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner } 728542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner for (unsigned i = 0, e = BBCases.size(); i != e; ++i) 729542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner if (!PTIHandled.count(BBCases[i].first) && 730542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner BBCases[i].second != BBDefault) { 731542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner PredCases.push_back(BBCases[i]); 732542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner NewSuccessors.push_back(BBCases[i].second); 733542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner } 734542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner 735542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner } else { 736542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // If this is not the default destination from PSI, only the edges 737542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // in SI that occur in PSI with a destination of BB will be 738542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // activated. 739c81f5445a7cbe3ba0252aec030082a40e5019eceDale Johannesen std::set<ConstantInt*, ConstantIntOrdering> PTIHandled; 740542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner for (unsigned i = 0, e = PredCases.size(); i != e; ++i) 741542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner if (PredCases[i].second == BB) { 742542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner PTIHandled.insert(PredCases[i].first); 743542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner std::swap(PredCases[i], PredCases.back()); 744542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner PredCases.pop_back(); 745542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner --i; --e; 746542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner } 747542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner 748542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // Okay, now we know which constants were sent to BB from the 749542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // predecessor. Figure out where they will all go now. 750542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner for (unsigned i = 0, e = BBCases.size(); i != e; ++i) 751542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner if (PTIHandled.count(BBCases[i].first)) { 752542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // If this is one we are capable of getting... 753542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner PredCases.push_back(BBCases[i]); 754542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner NewSuccessors.push_back(BBCases[i].second); 755542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner PTIHandled.erase(BBCases[i].first);// This constant is taken care of 756542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner } 757542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner 758542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // If there are any constants vectored to BB that TI doesn't handle, 759542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // they must go to the default destination of TI. 760c81f5445a7cbe3ba0252aec030082a40e5019eceDale Johannesen for (std::set<ConstantInt*, ConstantIntOrdering>::iterator I = 761c81f5445a7cbe3ba0252aec030082a40e5019eceDale Johannesen PTIHandled.begin(), 762542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner E = PTIHandled.end(); I != E; ++I) { 763542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner PredCases.push_back(std::make_pair(*I, BBDefault)); 764542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner NewSuccessors.push_back(BBDefault); 765542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner } 766542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner } 767542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner 768542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // Okay, at this point, we know which new successor Pred will get. Make 769542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // sure we update the number of entries in the PHI nodes for these 770542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // successors. 771542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner for (unsigned i = 0, e = NewSuccessors.size(); i != e; ++i) 772542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner AddPredecessorToBlock(NewSuccessors[i], Pred, BB); 773542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner 77458e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen // Convert pointer to int before we switch. 7751df9859c40492511b8aa4321eb76496005d3b75bDuncan Sands if (CV->getType()->isPointerTy()) { 77658e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen assert(TD && "Cannot switch on pointer without TargetData"); 77758e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen CV = new PtrToIntInst(CV, TD->getIntPtrType(CV->getContext()), 77858e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen "magicptr", PTI); 779d80e8ed2fa20c7ad51af49c3b2650525edbdcd08Devang Patel cast<PtrToIntInst>(CV)->setDebugLoc(PTI->getDebugLoc()); 78058e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen } 78158e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen 782542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // Now that the successors are updated, create the new Switch instruction. 783b1dbcd886a4b5597a839f299054b78b33fb2d6dfGabor Greif SwitchInst *NewSI = SwitchInst::Create(CV, PredDefault, 784b1dbcd886a4b5597a839f299054b78b33fb2d6dfGabor Greif PredCases.size(), PTI); 785d80e8ed2fa20c7ad51af49c3b2650525edbdcd08Devang Patel NewSI->setDebugLoc(PTI->getDebugLoc()); 786542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner for (unsigned i = 0, e = PredCases.size(); i != e; ++i) 787542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner NewSI->addCase(PredCases[i].first, PredCases[i].second); 78813b2f764c041e15af3d6033826deb9c7e669ca97Chris Lattner 789080efb8cea6255b4f1f373d9cb583d6a6302106bEli Friedman EraseTerminatorInstAndDCECond(PTI); 79013b2f764c041e15af3d6033826deb9c7e669ca97Chris Lattner 791542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // Okay, last check. If BB is still a successor of PSI, then we must 792542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // have an infinite loop case. If so, add an infinitely looping block 793542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // to handle the case to preserve the behavior of the code. 794542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner BasicBlock *InfLoopBlock = 0; 795542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner for (unsigned i = 0, e = NewSI->getNumSuccessors(); i != e; ++i) 796542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner if (NewSI->getSuccessor(i) == BB) { 797542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner if (InfLoopBlock == 0) { 798093a4385027235459ab6972b2e2fdc79061773cfChris Lattner // Insert it at the end of the function, because it's either code, 799542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // or it won't matter if it's hot. :) 8001d0be15f89cb5056e20e2d24faa8d6afb1573bcaOwen Anderson InfLoopBlock = BasicBlock::Create(BB->getContext(), 8011d0be15f89cb5056e20e2d24faa8d6afb1573bcaOwen Anderson "infloop", BB->getParent()); 802051a950000e21935165db56695e35bade668193bGabor Greif BranchInst::Create(InfLoopBlock, InfLoopBlock); 803542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner } 804542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner NewSI->setSuccessor(i, InfLoopBlock); 805542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner } 806fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukman 807542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner Changed = true; 808542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner } 809542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner } 810542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner return Changed; 811542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner} 812542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner 813c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen// isSafeToHoistInvoke - If we would need to insert a select that uses the 814c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen// value of this invoke (comments in HoistThenElseCodeToIf explain why we 815c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen// would need to do this), we can't hoist the invoke, as there is nowhere 816c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen// to put the select in this case. 817c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesenstatic bool isSafeToHoistInvoke(BasicBlock *BB1, BasicBlock *BB2, 818c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen Instruction *I1, Instruction *I2) { 819c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen for (succ_iterator SI = succ_begin(BB1), E = succ_end(BB1); SI != E; ++SI) { 820c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen PHINode *PN; 821c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen for (BasicBlock::iterator BBI = SI->begin(); 822c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen (PN = dyn_cast<PHINode>(BBI)); ++BBI) { 823c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen Value *BB1V = PN->getIncomingValueForBlock(BB1); 824c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen Value *BB2V = PN->getIncomingValueForBlock(BB2); 825c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen if (BB1V != BB2V && (BB1V==I1 || BB2V==I2)) { 826c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen return false; 827c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen } 828c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen } 829c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen } 830c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen return true; 831c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen} 832c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen 8336306d07aa8cf71e3c7fed7f295665f53595473ebChris Lattner/// HoistThenElseCodeToIf - Given a conditional branch that goes to BB1 and 83437dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner/// BB2, hoist any common code in the two blocks up into the branch block. The 83537dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner/// caller of this function guarantees that BI's block dominates BB1 and BB2. 83637dc938bbe556a9414d063196d367c2f75d07d95Chris Lattnerstatic bool HoistThenElseCodeToIf(BranchInst *BI) { 83737dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner // This does very trivial matching, with limited scanning, to find identical 83837dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner // instructions in the two blocks. In particular, we don't want to get into 83937dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner // O(M*N) situations here where M and N are the sizes of BB1 and BB2. As 84037dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner // such, we currently just scan for obviously identical instructions in an 84137dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner // identical order. 84237dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner BasicBlock *BB1 = BI->getSuccessor(0); // The true destination. 84337dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner BasicBlock *BB2 = BI->getSuccessor(1); // The false destination 84437dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner 84565085cf7b3470b7b087f5fd7b0497879b90b32baDevang Patel BasicBlock::iterator BB1_Itr = BB1->begin(); 84665085cf7b3470b7b087f5fd7b0497879b90b32baDevang Patel BasicBlock::iterator BB2_Itr = BB2->begin(); 84765085cf7b3470b7b087f5fd7b0497879b90b32baDevang Patel 84865085cf7b3470b7b087f5fd7b0497879b90b32baDevang Patel Instruction *I1 = BB1_Itr++, *I2 = BB2_Itr++; 849949666ea16214e1b7e79fc8e653b06ad8b93dd5aDevang Patel // Skip debug info if it is not identical. 850949666ea16214e1b7e79fc8e653b06ad8b93dd5aDevang Patel DbgInfoIntrinsic *DBI1 = dyn_cast<DbgInfoIntrinsic>(I1); 851949666ea16214e1b7e79fc8e653b06ad8b93dd5aDevang Patel DbgInfoIntrinsic *DBI2 = dyn_cast<DbgInfoIntrinsic>(I2); 852949666ea16214e1b7e79fc8e653b06ad8b93dd5aDevang Patel if (!DBI1 || !DBI2 || !DBI1->isIdenticalToWhenDefined(DBI2)) { 853949666ea16214e1b7e79fc8e653b06ad8b93dd5aDevang Patel while (isa<DbgInfoIntrinsic>(I1)) 854949666ea16214e1b7e79fc8e653b06ad8b93dd5aDevang Patel I1 = BB1_Itr++; 855949666ea16214e1b7e79fc8e653b06ad8b93dd5aDevang Patel while (isa<DbgInfoIntrinsic>(I2)) 856949666ea16214e1b7e79fc8e653b06ad8b93dd5aDevang Patel I2 = BB2_Itr++; 857949666ea16214e1b7e79fc8e653b06ad8b93dd5aDevang Patel } 858ae6c95b58e78403707fb75e78f0959a86d57b0c5Devang Patel if (isa<PHINode>(I1) || !I1->isIdenticalToWhenDefined(I2) || 859c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen (isa<InvokeInst>(I1) && !isSafeToHoistInvoke(BB1, BB2, I1, I2))) 86037dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner return false; 86137dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner 86237dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner // If we get here, we can hoist at least one instruction. 86337dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner BasicBlock *BIParent = BI->getParent(); 86437dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner 86537dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner do { 86637dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner // If we are hoisting the terminator instruction, don't move one (making a 86737dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner // broken BB), instead clone it, and remove BI. 86837dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner if (isa<TerminatorInst>(I1)) 86937dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner goto HoistTerminator; 870fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukman 87137dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner // For a normal instruction, we just move one to right before the branch, 87237dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner // then replace all uses of the other with the first. Finally, we remove 87337dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner // the now redundant second instruction. 87437dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner BIParent->getInstList().splice(BI, BB1->getInstList(), I1); 87537dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner if (!I2->use_empty()) 87637dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner I2->replaceAllUsesWith(I1); 87758cfa3b13752579c86cf85270d49f9ced0942f2fDan Gohman I1->intersectOptionalDataWith(I2); 878302ba6fc1cb26248b0d6524fc42c740370926d6dChris Lattner I2->eraseFromParent(); 879fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukman 88065085cf7b3470b7b087f5fd7b0497879b90b32baDevang Patel I1 = BB1_Itr++; 88165085cf7b3470b7b087f5fd7b0497879b90b32baDevang Patel I2 = BB2_Itr++; 882949666ea16214e1b7e79fc8e653b06ad8b93dd5aDevang Patel // Skip debug info if it is not identical. 883949666ea16214e1b7e79fc8e653b06ad8b93dd5aDevang Patel DbgInfoIntrinsic *DBI1 = dyn_cast<DbgInfoIntrinsic>(I1); 884949666ea16214e1b7e79fc8e653b06ad8b93dd5aDevang Patel DbgInfoIntrinsic *DBI2 = dyn_cast<DbgInfoIntrinsic>(I2); 885949666ea16214e1b7e79fc8e653b06ad8b93dd5aDevang Patel if (!DBI1 || !DBI2 || !DBI1->isIdenticalToWhenDefined(DBI2)) { 886949666ea16214e1b7e79fc8e653b06ad8b93dd5aDevang Patel while (isa<DbgInfoIntrinsic>(I1)) 887949666ea16214e1b7e79fc8e653b06ad8b93dd5aDevang Patel I1 = BB1_Itr++; 888949666ea16214e1b7e79fc8e653b06ad8b93dd5aDevang Patel while (isa<DbgInfoIntrinsic>(I2)) 889949666ea16214e1b7e79fc8e653b06ad8b93dd5aDevang Patel I2 = BB2_Itr++; 890949666ea16214e1b7e79fc8e653b06ad8b93dd5aDevang Patel } 891ae6c95b58e78403707fb75e78f0959a86d57b0c5Devang Patel } while (I1->isIdenticalToWhenDefined(I2)); 89237dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner 89337dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner return true; 89437dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner 89537dc938bbe556a9414d063196d367c2f75d07d95Chris LattnerHoistTerminator: 896c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen // It may not be possible to hoist an invoke. 897c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen if (isa<InvokeInst>(I1) && !isSafeToHoistInvoke(BB1, BB2, I1, I2)) 898c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen return true; 899c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen 90037dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner // Okay, it is safe to hoist the terminator. 9016776064d190701c5bae4d5403939eed2e480d1cdNick Lewycky Instruction *NT = I1->clone(); 90237dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner BIParent->getInstList().insert(BI, NT); 903f012705c7e4ca8cf90b6b734ce1d5355daca5ba5Benjamin Kramer if (!NT->getType()->isVoidTy()) { 90437dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner I1->replaceAllUsesWith(NT); 90537dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner I2->replaceAllUsesWith(NT); 90686cc42355593dd1689f7d58d56695c451215b02bChris Lattner NT->takeName(I1); 90737dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner } 90837dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner 90937dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner // Hoisting one of the terminators from our successor is a great thing. 91037dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner // Unfortunately, the successors of the if/else blocks may have PHI nodes in 91137dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner // them. If they do, all PHI entries for BB1/BB2 must agree for all PHI 91237dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner // nodes, so we insert select instruction to compute the final result. 91337dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner std::map<std::pair<Value*,Value*>, SelectInst*> InsertedSelects; 91437dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner for (succ_iterator SI = succ_begin(BB1), E = succ_end(BB1); SI != E; ++SI) { 91537dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner PHINode *PN; 91637dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner for (BasicBlock::iterator BBI = SI->begin(); 9170f535c6fa8b03491dc110feb65d78922ee29d1fcChris Lattner (PN = dyn_cast<PHINode>(BBI)); ++BBI) { 91837dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner Value *BB1V = PN->getIncomingValueForBlock(BB1); 91937dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner Value *BB2V = PN->getIncomingValueForBlock(BB2); 9209a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (BB1V == BB2V) continue; 9219a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner 9229a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // These values do not agree. Insert a select instruction before NT 9239a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // that determines the right value. 9249a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner SelectInst *&SI = InsertedSelects[std::make_pair(BB1V, BB2V)]; 925d80e8ed2fa20c7ad51af49c3b2650525edbdcd08Devang Patel if (SI == 0) { 9269a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner SI = SelectInst::Create(BI->getCondition(), BB1V, BB2V, 9279a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner BB1V->getName()+"."+BB2V->getName(), NT); 928d80e8ed2fa20c7ad51af49c3b2650525edbdcd08Devang Patel SI->setDebugLoc(BI->getDebugLoc()); 929d80e8ed2fa20c7ad51af49c3b2650525edbdcd08Devang Patel } 9309a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // Make the PHI node use the select for all incoming values for BB1/BB2 9319a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) 9329a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (PN->getIncomingBlock(i) == BB1 || PN->getIncomingBlock(i) == BB2) 9339a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner PN->setIncomingValue(i, SI); 93437dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner } 93537dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner } 93637dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner 93737dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner // Update any PHI nodes in our new successors. 93837dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner for (succ_iterator SI = succ_begin(BB1), E = succ_end(BB1); SI != E; ++SI) 93937dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner AddPredecessorToBlock(*SI, BIParent, BB1); 940fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukman 941080efb8cea6255b4f1f373d9cb583d6a6302106bEli Friedman EraseTerminatorInstAndDCECond(BI); 94237dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner return true; 94337dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner} 94437dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner 9454d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng/// SpeculativelyExecuteBB - Given a conditional branch that goes to BB1 9464d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng/// and an BB2 and the only successor of BB1 is BB2, hoist simple code 9474d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng/// (for now, restricted to a single instruction that's side effect free) from 9484d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng/// the BB1 into the branch block to speculatively execute it. 9494d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Chengstatic bool SpeculativelyExecuteBB(BranchInst *BI, BasicBlock *BB1) { 9504d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // Only speculatively execution a single instruction (not counting the 9514d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // terminator) for now. 95206b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel Instruction *HInst = NULL; 95306b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel Instruction *Term = BB1->getTerminator(); 95406b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel for (BasicBlock::iterator BBI = BB1->begin(), BBE = BB1->end(); 95506b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel BBI != BBE; ++BBI) { 95606b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel Instruction *I = BBI; 95706b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel // Skip debug info. 9589a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (isa<DbgInfoIntrinsic>(I)) continue; 9599a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (I == Term) break; 96006b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel 9619a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (HInst) 96206b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel return false; 9639a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner HInst = I; 96406b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel } 96506b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel if (!HInst) 96606b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel return false; 9674d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng 968797d95188d00963a835db9ad66dd3c4a54aa2fafEvan Cheng // Be conservative for now. FP select instruction can often be expensive. 969797d95188d00963a835db9ad66dd3c4a54aa2fafEvan Cheng Value *BrCond = BI->getCondition(); 9709a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (isa<FCmpInst>(BrCond)) 971797d95188d00963a835db9ad66dd3c4a54aa2fafEvan Cheng return false; 972797d95188d00963a835db9ad66dd3c4a54aa2fafEvan Cheng 9734d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // If BB1 is actually on the false edge of the conditional branch, remember 9744d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // to swap the select operands later. 9754d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng bool Invert = false; 9764d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng if (BB1 != BI->getSuccessor(0)) { 9774d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng assert(BB1 == BI->getSuccessor(1) && "No edge from 'if' block?"); 9784d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng Invert = true; 9794d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng } 9804d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng 9814d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // Turn 9824d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // BB: 9834d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // %t1 = icmp 9844d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // br i1 %t1, label %BB1, label %BB2 9854d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // BB1: 9864d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // %t3 = add %t2, c 9874d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // br label BB2 9884d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // BB2: 9894d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // => 9904d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // BB: 9914d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // %t1 = icmp 9924d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // %t4 = add %t2, c 9934d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // %t3 = select i1 %t1, %t2, %t3 99406b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel switch (HInst->getOpcode()) { 9954d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng default: return false; // Not safe / profitable to hoist. 9964d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng case Instruction::Add: 9974d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng case Instruction::Sub: 998ae3a0be92e33bc716722aa600983fc1535acb122Dan Gohman // Not worth doing for vector ops. 9991df9859c40492511b8aa4321eb76496005d3b75bDuncan Sands if (HInst->getType()->isVectorTy()) 10009dd3b610dcb17f88ed52ae03022179bf21e0e132Chris Lattner return false; 10019dd3b610dcb17f88ed52ae03022179bf21e0e132Chris Lattner break; 10024d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng case Instruction::And: 10034d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng case Instruction::Or: 10044d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng case Instruction::Xor: 10054d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng case Instruction::Shl: 10064d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng case Instruction::LShr: 10074d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng case Instruction::AShr: 10089dd3b610dcb17f88ed52ae03022179bf21e0e132Chris Lattner // Don't mess with vector operations. 10091df9859c40492511b8aa4321eb76496005d3b75bDuncan Sands if (HInst->getType()->isVectorTy()) 1010e5334ea518e3dffec4037ede97433eb700fa1d26Evan Cheng return false; 10114d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng break; // These are all cheap and non-trapping instructions. 10124d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng } 10136fe73bbcf3b6c1ddfd5e70e8b5188f8df439ace6Chris Lattner 10146fe73bbcf3b6c1ddfd5e70e8b5188f8df439ace6Chris Lattner // If the instruction is obviously dead, don't try to predicate it. 101506b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel if (HInst->use_empty()) { 101606b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel HInst->eraseFromParent(); 10176fe73bbcf3b6c1ddfd5e70e8b5188f8df439ace6Chris Lattner return true; 10186fe73bbcf3b6c1ddfd5e70e8b5188f8df439ace6Chris Lattner } 10194d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng 10204d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // Can we speculatively execute the instruction? And what is the value 10214d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // if the condition is false? Consider the phi uses, if the incoming value 10224d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // from the "if" block are all the same V, then V is the value of the 10234d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // select if the condition is false. 10244d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng BasicBlock *BIParent = BI->getParent(); 10254d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng SmallVector<PHINode*, 4> PHIUses; 10264d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng Value *FalseV = NULL; 10276fe73bbcf3b6c1ddfd5e70e8b5188f8df439ace6Chris Lattner 10286fe73bbcf3b6c1ddfd5e70e8b5188f8df439ace6Chris Lattner BasicBlock *BB2 = BB1->getTerminator()->getSuccessor(0); 102906b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel for (Value::use_iterator UI = HInst->use_begin(), E = HInst->use_end(); 10304d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng UI != E; ++UI) { 10316fe73bbcf3b6c1ddfd5e70e8b5188f8df439ace6Chris Lattner // Ignore any user that is not a PHI node in BB2. These can only occur in 10326fe73bbcf3b6c1ddfd5e70e8b5188f8df439ace6Chris Lattner // unreachable blocks, because they would not be dominated by the instr. 103320361b9d4d9988d7bfa2112650971642cf81d13eGabor Greif PHINode *PN = dyn_cast<PHINode>(*UI); 10346fe73bbcf3b6c1ddfd5e70e8b5188f8df439ace6Chris Lattner if (!PN || PN->getParent() != BB2) 10356fe73bbcf3b6c1ddfd5e70e8b5188f8df439ace6Chris Lattner return false; 10364d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng PHIUses.push_back(PN); 10376fe73bbcf3b6c1ddfd5e70e8b5188f8df439ace6Chris Lattner 10384d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng Value *PHIV = PN->getIncomingValueForBlock(BIParent); 10394d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng if (!FalseV) 10404d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng FalseV = PHIV; 10414d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng else if (FalseV != PHIV) 10426fe73bbcf3b6c1ddfd5e70e8b5188f8df439ace6Chris Lattner return false; // Inconsistent value when condition is false. 10434d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng } 10446fe73bbcf3b6c1ddfd5e70e8b5188f8df439ace6Chris Lattner 10456fe73bbcf3b6c1ddfd5e70e8b5188f8df439ace6Chris Lattner assert(FalseV && "Must have at least one user, and it must be a PHI"); 10464d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng 1047502a4f5162498ec420e3cb22f667808d726dd7daEvan Cheng // Do not hoist the instruction if any of its operands are defined but not 1048502a4f5162498ec420e3cb22f667808d726dd7daEvan Cheng // used in this BB. The transformation will prevent the operand from 1049502a4f5162498ec420e3cb22f667808d726dd7daEvan Cheng // being sunk into the use block. 105006b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel for (User::op_iterator i = HInst->op_begin(), e = HInst->op_end(); 105106b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel i != e; ++i) { 1052502a4f5162498ec420e3cb22f667808d726dd7daEvan Cheng Instruction *OpI = dyn_cast<Instruction>(*i); 1053502a4f5162498ec420e3cb22f667808d726dd7daEvan Cheng if (OpI && OpI->getParent() == BIParent && 1054502a4f5162498ec420e3cb22f667808d726dd7daEvan Cheng !OpI->isUsedInBasicBlock(BIParent)) 1055502a4f5162498ec420e3cb22f667808d726dd7daEvan Cheng return false; 1056502a4f5162498ec420e3cb22f667808d726dd7daEvan Cheng } 1057502a4f5162498ec420e3cb22f667808d726dd7daEvan Cheng 10583d0a9a371c0ce3a46e845a7bf1f1acb7a1cf523eDevang Patel // If we get here, we can hoist the instruction. Try to place it 1059990afedb3a4b7d32832d74ad5b5863c19f909e1fDale Johannesen // before the icmp instruction preceding the conditional branch. 10603d0a9a371c0ce3a46e845a7bf1f1acb7a1cf523eDevang Patel BasicBlock::iterator InsertPos = BI; 1061990afedb3a4b7d32832d74ad5b5863c19f909e1fDale Johannesen if (InsertPos != BIParent->begin()) 1062990afedb3a4b7d32832d74ad5b5863c19f909e1fDale Johannesen --InsertPos; 1063990afedb3a4b7d32832d74ad5b5863c19f909e1fDale Johannesen // Skip debug info between condition and branch. 1064990afedb3a4b7d32832d74ad5b5863c19f909e1fDale Johannesen while (InsertPos != BIParent->begin() && isa<DbgInfoIntrinsic>(InsertPos)) 10653d0a9a371c0ce3a46e845a7bf1f1acb7a1cf523eDevang Patel --InsertPos; 106620da1f07dac4d771e55ee5c7f105ccedfa4caaaaDevang Patel if (InsertPos == BrCond && !isa<PHINode>(BrCond)) { 10673d0a9a371c0ce3a46e845a7bf1f1acb7a1cf523eDevang Patel SmallPtrSet<Instruction *, 4> BB1Insns; 10683d0a9a371c0ce3a46e845a7bf1f1acb7a1cf523eDevang Patel for(BasicBlock::iterator BB1I = BB1->begin(), BB1E = BB1->end(); 10693d0a9a371c0ce3a46e845a7bf1f1acb7a1cf523eDevang Patel BB1I != BB1E; ++BB1I) 10703d0a9a371c0ce3a46e845a7bf1f1acb7a1cf523eDevang Patel BB1Insns.insert(BB1I); 10713d0a9a371c0ce3a46e845a7bf1f1acb7a1cf523eDevang Patel for(Value::use_iterator UI = BrCond->use_begin(), UE = BrCond->use_end(); 10723d0a9a371c0ce3a46e845a7bf1f1acb7a1cf523eDevang Patel UI != UE; ++UI) { 10733d0a9a371c0ce3a46e845a7bf1f1acb7a1cf523eDevang Patel Instruction *Use = cast<Instruction>(*UI); 10749a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (!BB1Insns.count(Use)) continue; 10759a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner 10769a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // If BrCond uses the instruction that place it just before 10779a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // branch instruction. 10789a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner InsertPos = BI; 10799a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner break; 10803d0a9a371c0ce3a46e845a7bf1f1acb7a1cf523eDevang Patel } 10813d0a9a371c0ce3a46e845a7bf1f1acb7a1cf523eDevang Patel } else 10823d0a9a371c0ce3a46e845a7bf1f1acb7a1cf523eDevang Patel InsertPos = BI; 108306b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel BIParent->getInstList().splice(InsertPos, BB1->getInstList(), HInst); 10844d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng 10854d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // Create a select whose true value is the speculatively executed value and 10864d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // false value is the previously determined FalseV. 10874d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng SelectInst *SI; 10884d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng if (Invert) 108906b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel SI = SelectInst::Create(BrCond, FalseV, HInst, 109006b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel FalseV->getName() + "." + HInst->getName(), BI); 10914d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng else 109206b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel SI = SelectInst::Create(BrCond, HInst, FalseV, 109306b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel HInst->getName() + "." + FalseV->getName(), BI); 1094d80e8ed2fa20c7ad51af49c3b2650525edbdcd08Devang Patel SI->setDebugLoc(BI->getDebugLoc()); 10954d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng 10964d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // Make the PHI node use the select for all incoming values for "then" and 10974d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // "if" blocks. 10984d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng for (unsigned i = 0, e = PHIUses.size(); i != e; ++i) { 10994d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng PHINode *PN = PHIUses[i]; 11004d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng for (unsigned j = 0, ee = PN->getNumIncomingValues(); j != ee; ++j) 11019a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (PN->getIncomingBlock(j) == BB1 || PN->getIncomingBlock(j) == BIParent) 11024d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng PN->setIncomingValue(j, SI); 11034d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng } 11044d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng 1105502a4f5162498ec420e3cb22f667808d726dd7daEvan Cheng ++NumSpeculations; 11064d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng return true; 11074d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng} 11084d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng 11092e42e36698d5a34f1952ca3389f1973a6a1166f2Chris Lattner/// BlockIsSimpleEnoughToThreadThrough - Return true if we can thread a branch 11102e42e36698d5a34f1952ca3389f1973a6a1166f2Chris Lattner/// across this block. 11112e42e36698d5a34f1952ca3389f1973a6a1166f2Chris Lattnerstatic bool BlockIsSimpleEnoughToThreadThrough(BasicBlock *BB) { 11122e42e36698d5a34f1952ca3389f1973a6a1166f2Chris Lattner BranchInst *BI = cast<BranchInst>(BB->getTerminator()); 1113e9487f0dc8c6d15cb257d5b49fa96ed436d32f5fChris Lattner unsigned Size = 0; 1114e9487f0dc8c6d15cb257d5b49fa96ed436d32f5fChris Lattner 11159200c89968e52a590ee0b96092a0a589aa138a6fDevang Patel for (BasicBlock::iterator BBI = BB->begin(); &*BBI != BI; ++BBI) { 11168483e54837ede5dd40c5561f15c6a663e2bee87cDale Johannesen if (isa<DbgInfoIntrinsic>(BBI)) 11178483e54837ede5dd40c5561f15c6a663e2bee87cDale Johannesen continue; 1118e9487f0dc8c6d15cb257d5b49fa96ed436d32f5fChris Lattner if (Size > 10) return false; // Don't clone large BB's. 11198483e54837ede5dd40c5561f15c6a663e2bee87cDale Johannesen ++Size; 11202e42e36698d5a34f1952ca3389f1973a6a1166f2Chris Lattner 11218483e54837ede5dd40c5561f15c6a663e2bee87cDale Johannesen // We can only support instructions that do not define values that are 1122e9487f0dc8c6d15cb257d5b49fa96ed436d32f5fChris Lattner // live outside of the current basic block. 1123e9487f0dc8c6d15cb257d5b49fa96ed436d32f5fChris Lattner for (Value::use_iterator UI = BBI->use_begin(), E = BBI->use_end(); 1124e9487f0dc8c6d15cb257d5b49fa96ed436d32f5fChris Lattner UI != E; ++UI) { 1125e9487f0dc8c6d15cb257d5b49fa96ed436d32f5fChris Lattner Instruction *U = cast<Instruction>(*UI); 1126e9487f0dc8c6d15cb257d5b49fa96ed436d32f5fChris Lattner if (U->getParent() != BB || isa<PHINode>(U)) return false; 1127e9487f0dc8c6d15cb257d5b49fa96ed436d32f5fChris Lattner } 11282e42e36698d5a34f1952ca3389f1973a6a1166f2Chris Lattner 11292e42e36698d5a34f1952ca3389f1973a6a1166f2Chris Lattner // Looks ok, continue checking. 11302e42e36698d5a34f1952ca3389f1973a6a1166f2Chris Lattner } 1131e9487f0dc8c6d15cb257d5b49fa96ed436d32f5fChris Lattner 11322e42e36698d5a34f1952ca3389f1973a6a1166f2Chris Lattner return true; 11332e42e36698d5a34f1952ca3389f1973a6a1166f2Chris Lattner} 11342e42e36698d5a34f1952ca3389f1973a6a1166f2Chris Lattner 1135eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner/// FoldCondBranchOnPHI - If we have a conditional branch on a PHI node value 1136eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner/// that is defined in the same block as the branch and if any PHI entries are 1137eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner/// constants, thread edges corresponding to that entry to be branches to their 1138eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner/// ultimate destination. 1139302ba6fc1cb26248b0d6524fc42c740370926d6dChris Lattnerstatic bool FoldCondBranchOnPHI(BranchInst *BI, const TargetData *TD) { 1140eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner BasicBlock *BB = BI->getParent(); 1141eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner PHINode *PN = dyn_cast<PHINode>(BI->getCondition()); 11429c88d9816246d260b37cdc689f313c56aec6941eChris Lattner // NOTE: we currently cannot transform this case if the PHI node is used 11439c88d9816246d260b37cdc689f313c56aec6941eChris Lattner // outside of the block. 11442e42e36698d5a34f1952ca3389f1973a6a1166f2Chris Lattner if (!PN || PN->getParent() != BB || !PN->hasOneUse()) 11452e42e36698d5a34f1952ca3389f1973a6a1166f2Chris Lattner return false; 1146eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner 1147eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner // Degenerate case of a single entry PHI. 1148eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner if (PN->getNumIncomingValues() == 1) { 114929874e0dc6c4e55bc384611273343bb358982cc3Chris Lattner FoldSingleEntryPHINodes(PN->getParent()); 1150eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner return true; 1151eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner } 1152eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner 1153eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner // Now we know that this block has multiple preds and two succs. 11542e42e36698d5a34f1952ca3389f1973a6a1166f2Chris Lattner if (!BlockIsSimpleEnoughToThreadThrough(BB)) return false; 1155eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner 1156eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner // Okay, this is a simple enough basic block. See if any phi values are 1157eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner // constants. 11586b6b6ef1677fa71b1072c2911b4c1f9524a558c9Zhou Sheng for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) { 11599a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner ConstantInt *CB = dyn_cast<ConstantInt>(PN->getIncomingValue(i)); 11609a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (CB == 0 || !CB->getType()->isIntegerTy(1)) continue; 11619a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner 11629a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // Okay, we now know that all edges from PredBB should be revectored to 11639a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // branch to RealDest. 11649a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner BasicBlock *PredBB = PN->getIncomingBlock(i); 11659a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner BasicBlock *RealDest = BI->getSuccessor(!CB->getZExtValue()); 11669a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner 11679a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (RealDest == BB) continue; // Skip self loops. 11689a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner 11699a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // The dest block might have PHI nodes, other predecessors and other 11709a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // difficult cases. Instead of being smart about this, just insert a new 11719a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // block that jumps to the destination block, effectively splitting 11729a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // the edge we are about to create. 11739a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner BasicBlock *EdgeBB = BasicBlock::Create(BB->getContext(), 11749a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner RealDest->getName()+".critedge", 11759a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner RealDest->getParent(), RealDest); 11769a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner BranchInst::Create(RealDest, EdgeBB); 11776de0a28dfb84095ebd7775f371dd4085cf955076Chris Lattner 11786de0a28dfb84095ebd7775f371dd4085cf955076Chris Lattner // Update PHI nodes. 11796de0a28dfb84095ebd7775f371dd4085cf955076Chris Lattner AddPredecessorToBlock(RealDest, EdgeBB, BB); 11809a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner 11819a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // BB may have instructions that are being threaded over. Clone these 11829a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // instructions into EdgeBB. We know that there will be no uses of the 11839a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // cloned instructions outside of EdgeBB. 11849a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner BasicBlock::iterator InsertPt = EdgeBB->begin(); 11859a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner DenseMap<Value*, Value*> TranslateMap; // Track translated values. 11869a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner for (BasicBlock::iterator BBI = BB->begin(); &*BBI != BI; ++BBI) { 11879a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (PHINode *PN = dyn_cast<PHINode>(BBI)) { 11889a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner TranslateMap[PN] = PN->getIncomingValueForBlock(PredBB); 11899a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner continue; 11909a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner } 11919a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // Clone the instruction. 11929a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner Instruction *N = BBI->clone(); 11939a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (BBI->hasName()) N->setName(BBI->getName()+".c"); 1194eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner 11959a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // Update operands due to translation. 11969a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner for (User::op_iterator i = N->op_begin(), e = N->op_end(); 11979a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner i != e; ++i) { 11989a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner DenseMap<Value*, Value*>::iterator PI = TranslateMap.find(*i); 11999a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (PI != TranslateMap.end()) 12009a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner *i = PI->second; 12019a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner } 1202eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner 12039a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // Check for trivial simplification. 1204302ba6fc1cb26248b0d6524fc42c740370926d6dChris Lattner if (Value *V = SimplifyInstruction(N, TD)) { 1205302ba6fc1cb26248b0d6524fc42c740370926d6dChris Lattner TranslateMap[BBI] = V; 1206302ba6fc1cb26248b0d6524fc42c740370926d6dChris Lattner delete N; // Instruction folded away, don't need actual inst 12079a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner } else { 12089a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // Insert the new instruction into its new home. 12099a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner EdgeBB->getInstList().insert(InsertPt, N); 12109a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (!BBI->use_empty()) 12119a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner TranslateMap[BBI] = N; 1212e9487f0dc8c6d15cb257d5b49fa96ed436d32f5fChris Lattner } 12139a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner } 1214e9487f0dc8c6d15cb257d5b49fa96ed436d32f5fChris Lattner 12159a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // Loop over all of the edges from PredBB to BB, changing them to branch 12169a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // to EdgeBB instead. 12179a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner TerminatorInst *PredBBTI = PredBB->getTerminator(); 12189a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner for (unsigned i = 0, e = PredBBTI->getNumSuccessors(); i != e; ++i) 12199a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (PredBBTI->getSuccessor(i) == BB) { 12209a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner BB->removePredecessor(PredBB); 12219a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner PredBBTI->setSuccessor(i, EdgeBB); 1222e9487f0dc8c6d15cb257d5b49fa96ed436d32f5fChris Lattner } 12239a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner 12249a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // Recurse, simplifying any other constants. 1225302ba6fc1cb26248b0d6524fc42c740370926d6dChris Lattner return FoldCondBranchOnPHI(BI, TD) | true; 12266b6b6ef1677fa71b1072c2911b4c1f9524a558c9Zhou Sheng } 1227eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner 1228eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner return false; 1229eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner} 1230eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner 1231f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner/// FoldTwoEntryPHINode - Given a BB that starts with the specified two-entry 1232f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner/// PHI node, see if we can eliminate it. 1233f60364de44add5c92841425851cda1a6943bfcd7Devang Patelstatic bool FoldTwoEntryPHINode(PHINode *PN, const TargetData *TD, 1234f60364de44add5c92841425851cda1a6943bfcd7Devang Patel IRBuilder<> &Builder) { 1235f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // Ok, this is a two entry PHI node. Check to see if this is a simple "if 1236f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // statement", which has a very simple dominance structure. Basically, we 1237f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // are trying to find the condition that is being branched on, which 1238f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // subsequently causes this merge to happen. We really want control 1239f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // dependence information for this check, but simplifycfg can't keep it up 1240f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // to date, and this catches most of the cases we care about anyway. 1241f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner BasicBlock *BB = PN->getParent(); 1242f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner BasicBlock *IfTrue, *IfFalse; 1243f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner Value *IfCond = GetIfCondition(BB, IfTrue, IfFalse); 124460d410d7bb2eb11f36a004237e5948ffc5aff5a6Chris Lattner if (!IfCond || 124560d410d7bb2eb11f36a004237e5948ffc5aff5a6Chris Lattner // Don't bother if the branch will be constant folded trivially. 124660d410d7bb2eb11f36a004237e5948ffc5aff5a6Chris Lattner isa<ConstantInt>(IfCond)) 124760d410d7bb2eb11f36a004237e5948ffc5aff5a6Chris Lattner return false; 1248f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner 1249822a87998387a4c52be5162523f09cc8e5e5afb7Chris Lattner // Okay, we found that we can merge this two-entry phi node into a select. 1250822a87998387a4c52be5162523f09cc8e5e5afb7Chris Lattner // Doing so would require us to fold *all* two entry phi nodes in this block. 1251822a87998387a4c52be5162523f09cc8e5e5afb7Chris Lattner // At some point this becomes non-profitable (particularly if the target 1252822a87998387a4c52be5162523f09cc8e5e5afb7Chris Lattner // doesn't support cmov's). Only do this transformation if there are two or 1253822a87998387a4c52be5162523f09cc8e5e5afb7Chris Lattner // fewer PHI nodes in this block. 1254822a87998387a4c52be5162523f09cc8e5e5afb7Chris Lattner unsigned NumPhis = 0; 1255822a87998387a4c52be5162523f09cc8e5e5afb7Chris Lattner for (BasicBlock::iterator I = BB->begin(); isa<PHINode>(I); ++NumPhis, ++I) 1256822a87998387a4c52be5162523f09cc8e5e5afb7Chris Lattner if (NumPhis > 2) 1257822a87998387a4c52be5162523f09cc8e5e5afb7Chris Lattner return false; 1258822a87998387a4c52be5162523f09cc8e5e5afb7Chris Lattner 1259f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // Loop over the PHI's seeing if we can promote them all to select 1260f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // instructions. While we are at it, keep track of the instructions 1261f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // that need to be moved to the dominating block. 126244da7ca4213333bcade57a407a890970351db494Chris Lattner SmallPtrSet<Instruction*, 4> AggressiveInsts; 126357808b3da00d7abd01382d3ed5e70bfb0b2beb4bPeter Collingbourne unsigned MaxCostVal0 = PHINodeFoldingThreshold, 126457808b3da00d7abd01382d3ed5e70bfb0b2beb4bPeter Collingbourne MaxCostVal1 = PHINodeFoldingThreshold; 1265f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner 12663aff13b82a579e910420b6c040f3e85c99110e15Chris Lattner for (BasicBlock::iterator II = BB->begin(); isa<PHINode>(II);) { 12673aff13b82a579e910420b6c040f3e85c99110e15Chris Lattner PHINode *PN = cast<PHINode>(II++); 126807ff3539f5342bdac019c68bb362cb222b3f71d9Chris Lattner if (Value *V = SimplifyInstruction(PN, TD)) { 126907ff3539f5342bdac019c68bb362cb222b3f71d9Chris Lattner PN->replaceAllUsesWith(V); 12703aff13b82a579e910420b6c040f3e85c99110e15Chris Lattner PN->eraseFromParent(); 127107ff3539f5342bdac019c68bb362cb222b3f71d9Chris Lattner continue; 1272f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner } 127307ff3539f5342bdac019c68bb362cb222b3f71d9Chris Lattner 1274f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne if (!DominatesMergePoint(PN->getIncomingValue(0), BB, &AggressiveInsts, 1275f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne MaxCostVal0) || 1276f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne !DominatesMergePoint(PN->getIncomingValue(1), BB, &AggressiveInsts, 1277f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne MaxCostVal1)) 127807ff3539f5342bdac019c68bb362cb222b3f71d9Chris Lattner return false; 1279f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner } 1280f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner 128144da7ca4213333bcade57a407a890970351db494Chris Lattner // If we folded the the first phi, PN dangles at this point. Refresh it. If 128244da7ca4213333bcade57a407a890970351db494Chris Lattner // we ran out of PHIs then we simplified them all. 128344da7ca4213333bcade57a407a890970351db494Chris Lattner PN = dyn_cast<PHINode>(BB->begin()); 128444da7ca4213333bcade57a407a890970351db494Chris Lattner if (PN == 0) return true; 128544da7ca4213333bcade57a407a890970351db494Chris Lattner 12863aff13b82a579e910420b6c040f3e85c99110e15Chris Lattner // Don't fold i1 branches on PHIs which contain binary operators. These can 12873aff13b82a579e910420b6c040f3e85c99110e15Chris Lattner // often be turned into switches and other things. 12883aff13b82a579e910420b6c040f3e85c99110e15Chris Lattner if (PN->getType()->isIntegerTy(1) && 12893aff13b82a579e910420b6c040f3e85c99110e15Chris Lattner (isa<BinaryOperator>(PN->getIncomingValue(0)) || 12903aff13b82a579e910420b6c040f3e85c99110e15Chris Lattner isa<BinaryOperator>(PN->getIncomingValue(1)) || 12913aff13b82a579e910420b6c040f3e85c99110e15Chris Lattner isa<BinaryOperator>(IfCond))) 12923aff13b82a579e910420b6c040f3e85c99110e15Chris Lattner return false; 12933aff13b82a579e910420b6c040f3e85c99110e15Chris Lattner 1294f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // If we all PHI nodes are promotable, check to make sure that all 1295f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // instructions in the predecessor blocks can be promoted as well. If 1296f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // not, we won't be able to get rid of the control flow, so it's not 1297f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // worth promoting to select instructions. 129844da7ca4213333bcade57a407a890970351db494Chris Lattner BasicBlock *DomBlock = 0; 129944da7ca4213333bcade57a407a890970351db494Chris Lattner BasicBlock *IfBlock1 = PN->getIncomingBlock(0); 130044da7ca4213333bcade57a407a890970351db494Chris Lattner BasicBlock *IfBlock2 = PN->getIncomingBlock(1); 130144da7ca4213333bcade57a407a890970351db494Chris Lattner if (cast<BranchInst>(IfBlock1->getTerminator())->isConditional()) { 130244da7ca4213333bcade57a407a890970351db494Chris Lattner IfBlock1 = 0; 130344da7ca4213333bcade57a407a890970351db494Chris Lattner } else { 130444da7ca4213333bcade57a407a890970351db494Chris Lattner DomBlock = *pred_begin(IfBlock1); 130544da7ca4213333bcade57a407a890970351db494Chris Lattner for (BasicBlock::iterator I = IfBlock1->begin();!isa<TerminatorInst>(I);++I) 1306383d7ed9158576aef5cde872548225a17e3c0155Devang Patel if (!AggressiveInsts.count(I) && !isa<DbgInfoIntrinsic>(I)) { 1307f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // This is not an aggressive instruction that we can promote. 1308f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // Because of this, we won't be able to get rid of the control 1309f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // flow, so the xform is not worth it. 1310f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner return false; 1311f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner } 1312f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner } 1313f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner 131444da7ca4213333bcade57a407a890970351db494Chris Lattner if (cast<BranchInst>(IfBlock2->getTerminator())->isConditional()) { 131544da7ca4213333bcade57a407a890970351db494Chris Lattner IfBlock2 = 0; 131644da7ca4213333bcade57a407a890970351db494Chris Lattner } else { 131744da7ca4213333bcade57a407a890970351db494Chris Lattner DomBlock = *pred_begin(IfBlock2); 131844da7ca4213333bcade57a407a890970351db494Chris Lattner for (BasicBlock::iterator I = IfBlock2->begin();!isa<TerminatorInst>(I);++I) 1319383d7ed9158576aef5cde872548225a17e3c0155Devang Patel if (!AggressiveInsts.count(I) && !isa<DbgInfoIntrinsic>(I)) { 1320f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // This is not an aggressive instruction that we can promote. 1321f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // Because of this, we won't be able to get rid of the control 1322f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // flow, so the xform is not worth it. 1323f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner return false; 1324f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner } 1325f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner } 1326e0b18e59120abc29bd25d69d20c4b0f310ec3382Chris Lattner 1327e0b18e59120abc29bd25d69d20c4b0f310ec3382Chris Lattner DEBUG(dbgs() << "FOUND IF CONDITION! " << *IfCond << " T: " 132844da7ca4213333bcade57a407a890970351db494Chris Lattner << IfTrue->getName() << " F: " << IfFalse->getName() << "\n"); 1329f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner 1330f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // If we can still promote the PHI nodes after this gauntlet of tests, 1331f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // do all of the PHI's now. 13323aff13b82a579e910420b6c040f3e85c99110e15Chris Lattner Instruction *InsertPt = DomBlock->getTerminator(); 1333f60364de44add5c92841425851cda1a6943bfcd7Devang Patel Builder.SetInsertPoint(InsertPt); 13343aff13b82a579e910420b6c040f3e85c99110e15Chris Lattner 1335f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // Move all 'aggressive' instructions, which are defined in the 1336f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // conditional parts of the if's up to the dominating block. 13379a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (IfBlock1) 13383aff13b82a579e910420b6c040f3e85c99110e15Chris Lattner DomBlock->getInstList().splice(InsertPt, 13399a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner IfBlock1->getInstList(), IfBlock1->begin(), 1340f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner IfBlock1->getTerminator()); 13419a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (IfBlock2) 13423aff13b82a579e910420b6c040f3e85c99110e15Chris Lattner DomBlock->getInstList().splice(InsertPt, 13439a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner IfBlock2->getInstList(), IfBlock2->begin(), 1344f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner IfBlock2->getTerminator()); 1345f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner 1346f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner while (PHINode *PN = dyn_cast<PHINode>(BB->begin())) { 1347f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // Change the PHI node into a select instruction. 13489a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner Value *TrueVal = PN->getIncomingValue(PN->getIncomingBlock(0) == IfFalse); 13499a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner Value *FalseVal = PN->getIncomingValue(PN->getIncomingBlock(0) == IfTrue); 1350f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner 1351f60364de44add5c92841425851cda1a6943bfcd7Devang Patel SelectInst *NV = 1352f60364de44add5c92841425851cda1a6943bfcd7Devang Patel cast<SelectInst>(Builder.CreateSelect(IfCond, TrueVal, FalseVal, "")); 135386cc42355593dd1689f7d58d56695c451215b02bChris Lattner PN->replaceAllUsesWith(NV); 135486cc42355593dd1689f7d58d56695c451215b02bChris Lattner NV->takeName(PN); 1355302ba6fc1cb26248b0d6524fc42c740370926d6dChris Lattner PN->eraseFromParent(); 1356f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner } 135760d410d7bb2eb11f36a004237e5948ffc5aff5a6Chris Lattner 135860d410d7bb2eb11f36a004237e5948ffc5aff5a6Chris Lattner // At this point, IfBlock1 and IfBlock2 are both empty, so our if statement 135960d410d7bb2eb11f36a004237e5948ffc5aff5a6Chris Lattner // has been flattened. Change DomBlock to jump directly to our new block to 136060d410d7bb2eb11f36a004237e5948ffc5aff5a6Chris Lattner // avoid other simplifycfg's kicking in on the diamond. 136160d410d7bb2eb11f36a004237e5948ffc5aff5a6Chris Lattner TerminatorInst *OldTI = DomBlock->getTerminator(); 1362f60364de44add5c92841425851cda1a6943bfcd7Devang Patel Builder.SetInsertPoint(OldTI); 1363f60364de44add5c92841425851cda1a6943bfcd7Devang Patel Builder.CreateBr(BB); 136460d410d7bb2eb11f36a004237e5948ffc5aff5a6Chris Lattner OldTI->eraseFromParent(); 1365f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner return true; 1366f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner} 1367eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner 1368c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner/// SimplifyCondBranchToTwoReturns - If we found a conditional branch that goes 1369c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner/// to two returning blocks, try to merge them together into one return, 1370c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner/// introducing a select if the return values disagree. 1371c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattnerstatic bool SimplifyCondBranchToTwoReturns(BranchInst *BI) { 1372c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner assert(BI->isConditional() && "Must be a conditional branch"); 1373c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner BasicBlock *TrueSucc = BI->getSuccessor(0); 1374c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner BasicBlock *FalseSucc = BI->getSuccessor(1); 1375c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner ReturnInst *TrueRet = cast<ReturnInst>(TrueSucc->getTerminator()); 1376c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner ReturnInst *FalseRet = cast<ReturnInst>(FalseSucc->getTerminator()); 1377c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner 1378c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner // Check to ensure both blocks are empty (just a return) or optionally empty 1379c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner // with PHI nodes. If there are other instructions, merging would cause extra 1380c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner // computation on one path or the other. 13819a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (!TrueSucc->getFirstNonPHIOrDbg()->isTerminator()) 13822cc86a1de1cf598be384836f19d1ef1892fb50fcDevang Patel return false; 13839a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (!FalseSucc->getFirstNonPHIOrDbg()->isTerminator()) 13842cc86a1de1cf598be384836f19d1ef1892fb50fcDevang Patel return false; 1385c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner 1386c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner // Okay, we found a branch that is going to two return nodes. If 1387c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner // there is no return value for this function, just change the 1388c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner // branch into a return. 1389c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner if (FalseRet->getNumOperands() == 0) { 1390c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner TrueSucc->removePredecessor(BI->getParent()); 1391c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner FalseSucc->removePredecessor(BI->getParent()); 13921d0be15f89cb5056e20e2d24faa8d6afb1573bcaOwen Anderson ReturnInst::Create(BI->getContext(), 0, BI); 1393080efb8cea6255b4f1f373d9cb583d6a6302106bEli Friedman EraseTerminatorInstAndDCECond(BI); 1394c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner return true; 1395c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner } 1396c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner 1397fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman // Otherwise, figure out what the true and false return values are 1398fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman // so we can insert a new select instruction. 1399fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman Value *TrueValue = TrueRet->getReturnValue(); 1400fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman Value *FalseValue = FalseRet->getReturnValue(); 1401fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman 1402fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman // Unwrap any PHI nodes in the return blocks. 1403fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman if (PHINode *TVPN = dyn_cast_or_null<PHINode>(TrueValue)) 1404fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman if (TVPN->getParent() == TrueSucc) 1405fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman TrueValue = TVPN->getIncomingValueForBlock(BI->getParent()); 1406fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman if (PHINode *FVPN = dyn_cast_or_null<PHINode>(FalseValue)) 1407fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman if (FVPN->getParent() == FalseSucc) 1408fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman FalseValue = FVPN->getIncomingValueForBlock(BI->getParent()); 1409fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman 1410fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman // In order for this transformation to be safe, we must be able to 1411fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman // unconditionally execute both operands to the return. This is 1412fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman // normally the case, but we could have a potentially-trapping 1413fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman // constant expression that prevents this transformation from being 1414fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman // safe. 1415fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman if (ConstantExpr *TCV = dyn_cast_or_null<ConstantExpr>(TrueValue)) 1416fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman if (TCV->canTrap()) 1417fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman return false; 1418fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman if (ConstantExpr *FCV = dyn_cast_or_null<ConstantExpr>(FalseValue)) 1419fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman if (FCV->canTrap()) 1420fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman return false; 1421c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner 1422c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner // Okay, we collected all the mapped values and checked them for sanity, and 1423c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner // defined to really do this transformation. First, update the CFG. 1424c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner TrueSucc->removePredecessor(BI->getParent()); 1425c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner FalseSucc->removePredecessor(BI->getParent()); 1426c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner 1427c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner // Insert select instructions where needed. 1428c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner Value *BrCond = BI->getCondition(); 1429fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman if (TrueValue) { 1430c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner // Insert a select if the results differ. 1431fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman if (TrueValue == FalseValue || isa<UndefValue>(FalseValue)) { 1432fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman } else if (isa<UndefValue>(TrueValue)) { 1433fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman TrueValue = FalseValue; 1434fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman } else { 1435fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman TrueValue = SelectInst::Create(BrCond, TrueValue, 1436fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman FalseValue, "retval", BI); 1437c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner } 1438c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner } 1439c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner 1440fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman Value *RI = !TrueValue ? 14411d0be15f89cb5056e20e2d24faa8d6afb1573bcaOwen Anderson ReturnInst::Create(BI->getContext(), BI) : 14421d0be15f89cb5056e20e2d24faa8d6afb1573bcaOwen Anderson ReturnInst::Create(BI->getContext(), TrueValue, BI); 1443e317bcc74c1f317f913e9b05db385901cfc54d0bDaniel Dunbar (void) RI; 1444c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner 144589d6fd36a26fdf068ceea90422dc2897e89700b5David Greene DEBUG(dbgs() << "\nCHANGING BRANCH TO TWO RETURNS INTO SELECT:" 1446bdff548e4dd577a72094d57b282de4e765643b96Chris Lattner << "\n " << *BI << "NewRet = " << *RI 1447bdff548e4dd577a72094d57b282de4e765643b96Chris Lattner << "TRUEBLOCK: " << *TrueSucc << "FALSEBLOCK: "<< *FalseSucc); 1448c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner 1449080efb8cea6255b4f1f373d9cb583d6a6302106bEli Friedman EraseTerminatorInstAndDCECond(BI); 1450080efb8cea6255b4f1f373d9cb583d6a6302106bEli Friedman 1451c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner return true; 1452c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner} 1453c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner 1454c8fbc34869fc1737adea00f775de5b8dd829f7a1Chris Lattner/// FoldBranchToCommonDest - If this basic block is simple enough, and if a 1455c8fbc34869fc1737adea00f775de5b8dd829f7a1Chris Lattner/// predecessor branches to us and one of our successors, fold the block into 1456c8fbc34869fc1737adea00f775de5b8dd829f7a1Chris Lattner/// the predecessor and use logical operations to pick the right destination. 14574b35f83b91a1a313f0730c600e5178aaf7df98d6Dan Gohmanbool llvm::FoldBranchToCommonDest(BranchInst *BI) { 1458093a4385027235459ab6972b2e2fdc79061773cfChris Lattner BasicBlock *BB = BI->getParent(); 14591347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner Instruction *Cond = dyn_cast<Instruction>(BI->getCondition()); 1460e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson if (Cond == 0 || (!isa<CmpInst>(Cond) && !isa<BinaryOperator>(Cond)) || 1461e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson Cond->getParent() != BB || !Cond->hasOneUse()) 1462e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson return false; 1463d418194036e9e05f47154535ddb9f1f1c8bc592bDevang Patel 14641347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner // Only allow this if the condition is a simple instruction that can be 14651347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner // executed unconditionally. It must be in the same block as the branch, and 14661347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner // must be at the front of the block. 1467d0a203d76f4ef77ae1c392e8e73e2f05b676a5f2Devang Patel BasicBlock::iterator FrontIt = BB->front(); 14683c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner 1469d0a203d76f4ef77ae1c392e8e73e2f05b676a5f2Devang Patel // Ignore dbg intrinsics. 14703c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner while (isa<DbgInfoIntrinsic>(FrontIt)) ++FrontIt; 1471e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson 1472e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson // Allow a single instruction to be hoisted in addition to the compare 1473e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson // that feeds the branch. We later ensure that any values that _it_ uses 1474e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson // were also live in the predecessor, so that we don't unnecessarily create 1475e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson // register pressure or inhibit out-of-order execution. 1476e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson Instruction *BonusInst = 0; 1477e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson if (&*FrontIt != Cond && 14782722dfa75dbf4436197f6fcf9d8cb2391975f1a1Owen Anderson FrontIt->hasOneUse() && *FrontIt->use_begin() == Cond && 14792722dfa75dbf4436197f6fcf9d8cb2391975f1a1Owen Anderson FrontIt->isSafeToSpeculativelyExecute()) { 1480e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson BonusInst = &*FrontIt; 1481e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson ++FrontIt; 14823c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner 14833c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner // Ignore dbg intrinsics. 14843c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner while (isa<DbgInfoIntrinsic>(FrontIt)) ++FrontIt; 148560d490cdc7b11e678f35f5b7eb2c9ef354462211Devang Patel } 148660d490cdc7b11e678f35f5b7eb2c9ef354462211Devang Patel 1487e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson // Only a single bonus inst is allowed. 1488e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson if (&*FrontIt != Cond) 1489e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson return false; 1490e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson 14911347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner // Make sure the instruction after the condition is the cond branch. 14921347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner BasicBlock::iterator CondIt = Cond; ++CondIt; 14933c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner 1494d0a203d76f4ef77ae1c392e8e73e2f05b676a5f2Devang Patel // Ingore dbg intrinsics. 14953c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner while (isa<DbgInfoIntrinsic>(CondIt)) ++CondIt; 14963c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner 14973c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner if (&*CondIt != BI) 14981347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner return false; 14996ff645bf0fcfc0c62e9d9126e1243ec8bf10abbcChris Lattner 15006ff645bf0fcfc0c62e9d9126e1243ec8bf10abbcChris Lattner // Cond is known to be a compare or binary operator. Check to make sure that 15016ff645bf0fcfc0c62e9d9126e1243ec8bf10abbcChris Lattner // neither operand is a potentially-trapping constant expression. 15026ff645bf0fcfc0c62e9d9126e1243ec8bf10abbcChris Lattner if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Cond->getOperand(0))) 15036ff645bf0fcfc0c62e9d9126e1243ec8bf10abbcChris Lattner if (CE->canTrap()) 15046ff645bf0fcfc0c62e9d9126e1243ec8bf10abbcChris Lattner return false; 15056ff645bf0fcfc0c62e9d9126e1243ec8bf10abbcChris Lattner if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Cond->getOperand(1))) 15066ff645bf0fcfc0c62e9d9126e1243ec8bf10abbcChris Lattner if (CE->canTrap()) 15076ff645bf0fcfc0c62e9d9126e1243ec8bf10abbcChris Lattner return false; 15086ff645bf0fcfc0c62e9d9126e1243ec8bf10abbcChris Lattner 15091347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner // Finally, don't infinitely unroll conditional loops. 15101347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner BasicBlock *TrueDest = BI->getSuccessor(0); 15111347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner BasicBlock *FalseDest = BI->getSuccessor(1); 15121347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner if (TrueDest == BB || FalseDest == BB) 15131347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner return false; 1514d418194036e9e05f47154535ddb9f1f1c8bc592bDevang Patel 15151347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI) { 15161347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner BasicBlock *PredBlock = *PI; 15171347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner BranchInst *PBI = dyn_cast<BranchInst>(PredBlock->getTerminator()); 15186ff645bf0fcfc0c62e9d9126e1243ec8bf10abbcChris Lattner 1519093a4385027235459ab6972b2e2fdc79061773cfChris Lattner // Check that we have two conditional branches. If there is a PHI node in 1520093a4385027235459ab6972b2e2fdc79061773cfChris Lattner // the common successor, verify that the same value flows in from both 1521093a4385027235459ab6972b2e2fdc79061773cfChris Lattner // blocks. 15223c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner if (PBI == 0 || PBI->isUnconditional() || !SafeToMergeTerminators(BI, PBI)) 15231347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner continue; 15241347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner 15253c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner // Determine if the two branches share a common destination. 15263c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner Instruction::BinaryOps Opc; 15273c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner bool InvertPredCond = false; 15283c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner 15293c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner if (PBI->getSuccessor(0) == TrueDest) 15303c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner Opc = Instruction::Or; 15313c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner else if (PBI->getSuccessor(1) == FalseDest) 15323c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner Opc = Instruction::And; 15333c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner else if (PBI->getSuccessor(0) == FalseDest) 15343c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner Opc = Instruction::And, InvertPredCond = true; 15353c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner else if (PBI->getSuccessor(1) == TrueDest) 15363c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner Opc = Instruction::Or, InvertPredCond = true; 15373c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner else 15383c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner continue; 15393c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner 1540e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson // Ensure that any values used in the bonus instruction are also used 1541e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson // by the terminator of the predecessor. This means that those values 1542e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson // must already have been resolved, so we won't be inhibiting the 1543e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson // out-of-order core by speculating them earlier. 1544e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson if (BonusInst) { 1545e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson // Collect the values used by the bonus inst 1546e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson SmallPtrSet<Value*, 4> UsedValues; 1547e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson for (Instruction::op_iterator OI = BonusInst->op_begin(), 1548e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson OE = BonusInst->op_end(); OI != OE; ++OI) { 1549e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson Value* V = *OI; 1550e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson if (!isa<Constant>(V)) 1551e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson UsedValues.insert(V); 1552e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson } 1553e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson 1554e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson SmallVector<std::pair<Value*, unsigned>, 4> Worklist; 1555e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson Worklist.push_back(std::make_pair(PBI->getOperand(0), 0)); 1556e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson 1557e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson // Walk up to four levels back up the use-def chain of the predecessor's 1558e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson // terminator to see if all those values were used. The choice of four 1559e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson // levels is arbitrary, to provide a compile-time-cost bound. 1560e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson while (!Worklist.empty()) { 1561e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson std::pair<Value*, unsigned> Pair = Worklist.back(); 1562e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson Worklist.pop_back(); 1563e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson 1564e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson if (Pair.second >= 4) continue; 1565e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson UsedValues.erase(Pair.first); 1566e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson if (UsedValues.empty()) break; 1567e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson 1568daa02ab70c7619cc22131c75c62390cf3f5f8891Chris Lattner if (Instruction *I = dyn_cast<Instruction>(Pair.first)) { 1569e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson for (Instruction::op_iterator OI = I->op_begin(), OE = I->op_end(); 1570e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson OI != OE; ++OI) 1571e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson Worklist.push_back(std::make_pair(OI->get(), Pair.second+1)); 1572e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson } 1573e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson } 1574e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson 1575e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson if (!UsedValues.empty()) return false; 1576e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson } 15773698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner 157889d6fd36a26fdf068ceea90422dc2897e89700b5David Greene DEBUG(dbgs() << "FOLDING BRANCH TO COMMON DEST:\n" << *PBI << *BB); 15796ff645bf0fcfc0c62e9d9126e1243ec8bf10abbcChris Lattner 15803698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner // If we need to invert the condition in the pred block to match, do so now. 15813698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner if (InvertPredCond) { 1582daa02ab70c7619cc22131c75c62390cf3f5f8891Chris Lattner Value *NewCond = PBI->getCondition(); 1583daa02ab70c7619cc22131c75c62390cf3f5f8891Chris Lattner 1584daa02ab70c7619cc22131c75c62390cf3f5f8891Chris Lattner if (NewCond->hasOneUse() && isa<CmpInst>(NewCond)) { 1585daa02ab70c7619cc22131c75c62390cf3f5f8891Chris Lattner CmpInst *CI = cast<CmpInst>(NewCond); 1586daa02ab70c7619cc22131c75c62390cf3f5f8891Chris Lattner CI->setPredicate(CI->getInversePredicate()); 1587daa02ab70c7619cc22131c75c62390cf3f5f8891Chris Lattner } else { 1588daa02ab70c7619cc22131c75c62390cf3f5f8891Chris Lattner NewCond = BinaryOperator::CreateNot(NewCond, 15893698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner PBI->getCondition()->getName()+".not", PBI); 1590daa02ab70c7619cc22131c75c62390cf3f5f8891Chris Lattner } 1591daa02ab70c7619cc22131c75c62390cf3f5f8891Chris Lattner 15921347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner PBI->setCondition(NewCond); 15931347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner BasicBlock *OldTrue = PBI->getSuccessor(0); 15941347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner BasicBlock *OldFalse = PBI->getSuccessor(1); 15951347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner PBI->setSuccessor(0, OldFalse); 15961347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner PBI->setSuccessor(1, OldTrue); 15971347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner } 159870087f31f154156bcb494dd0cf3b7d74c0c8b528Chris Lattner 1599e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson // If we have a bonus inst, clone it into the predecessor block. 1600e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson Instruction *NewBonus = 0; 1601e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson if (BonusInst) { 1602e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson NewBonus = BonusInst->clone(); 1603e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson PredBlock->getInstList().insert(PBI, NewBonus); 1604e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson NewBonus->takeName(BonusInst); 1605e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson BonusInst->setName(BonusInst->getName()+".old"); 1606e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson } 1607e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson 16083698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner // Clone Cond into the predecessor basic block, and or/and the 16093698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner // two conditions together. 16106776064d190701c5bae4d5403939eed2e480d1cdNick Lewycky Instruction *New = Cond->clone(); 1611e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson if (BonusInst) New->replaceUsesOfWith(BonusInst, NewBonus); 16123698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner PredBlock->getInstList().insert(PBI, New); 16133698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner New->takeName(Cond); 16143698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner Cond->setName(New->getName()+".old"); 161570087f31f154156bcb494dd0cf3b7d74c0c8b528Chris Lattner 1616d80e8ed2fa20c7ad51af49c3b2650525edbdcd08Devang Patel Instruction *NewCond = BinaryOperator::Create(Opc, PBI->getCondition(), 1617d80e8ed2fa20c7ad51af49c3b2650525edbdcd08Devang Patel New, "or.cond", PBI); 1618d80e8ed2fa20c7ad51af49c3b2650525edbdcd08Devang Patel NewCond->setDebugLoc(PBI->getDebugLoc()); 16193698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner PBI->setCondition(NewCond); 16203698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner if (PBI->getSuccessor(0) == BB) { 16213698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner AddPredecessorToBlock(TrueDest, PredBlock, BB); 16223698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner PBI->setSuccessor(0, TrueDest); 16233698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner } 16243698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner if (PBI->getSuccessor(1) == BB) { 16253698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner AddPredecessorToBlock(FalseDest, PredBlock, BB); 16263698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner PBI->setSuccessor(1, FalseDest); 16271347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner } 1628d418194036e9e05f47154535ddb9f1f1c8bc592bDevang Patel 16293c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner // Copy any debug value intrinsics into the end of PredBlock. 16303c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) 16313c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner if (isa<DbgInfoIntrinsic>(*I)) 16323c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner I->clone()->insertBefore(PBI); 16333c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner 1634117f8cffc5499217ff8824eb0d6a0f6b1b78d96eChris Lattner return true; 16351347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner } 16361347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner return false; 16371347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner} 16381347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner 1639867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner/// SimplifyCondBranchToCondBranch - If we have a conditional branch as a 1640867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner/// predecessor of another block, this function tries to simplify it. We know 1641867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner/// that PBI and BI are both conditional branches, and BI is in one of the 1642867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner/// successor blocks of PBI - PBI branches to BI. 1643867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattnerstatic bool SimplifyCondBranchToCondBranch(BranchInst *PBI, BranchInst *BI) { 1644867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner assert(PBI->isConditional() && BI->isConditional()); 1645867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner BasicBlock *BB = BI->getParent(); 16464ae5126d041768ab9665cf2f11c024becd76c41fDan Gohman 1647867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner // If this block ends with a branch instruction, and if there is a 1648867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner // predecessor that ends on a branch of the same condition, make 1649867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner // this conditional branch redundant. 1650867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner if (PBI->getCondition() == BI->getCondition() && 1651867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner PBI->getSuccessor(0) != PBI->getSuccessor(1)) { 1652867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner // Okay, the outcome of this conditional branch is statically 1653867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner // knowable. If this block had a single pred, handle specially. 1654867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner if (BB->getSinglePredecessor()) { 1655867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner // Turn this into a branch on constant. 1656867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner bool CondIsTrue = PBI->getSuccessor(0) == BB; 16571d0be15f89cb5056e20e2d24faa8d6afb1573bcaOwen Anderson BI->setCondition(ConstantInt::get(Type::getInt1Ty(BB->getContext()), 16581d0be15f89cb5056e20e2d24faa8d6afb1573bcaOwen Anderson CondIsTrue)); 1659867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner return true; // Nuke the branch on constant. 1660867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner } 1661867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner 1662867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner // Otherwise, if there are multiple predecessors, insert a PHI that merges 1663867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner // in the constant and simplify the block result. Subsequent passes of 1664867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner // simplifycfg will thread the block. 1665867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner if (BlockIsSimpleEnoughToThreadThrough(BB)) { 1666d8b4fb4aab4d6fedb2b14bed1b846451b17bde7cJay Foad pred_iterator PB = pred_begin(BB), PE = pred_end(BB); 16671d0be15f89cb5056e20e2d24faa8d6afb1573bcaOwen Anderson PHINode *NewPN = PHINode::Create(Type::getInt1Ty(BB->getContext()), 16683ecfc861b4365f341c5c969b40e1afccde676e6fJay Foad std::distance(PB, PE), 1669867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner BI->getCondition()->getName() + ".pr", 1670867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner BB->begin()); 1671eb388af89f15ee3de6f53359473e1a54418a667fChris Lattner // Okay, we're going to insert the PHI node. Since PBI is not the only 1672eb388af89f15ee3de6f53359473e1a54418a667fChris Lattner // predecessor, compute the PHI'd conditional value for all of the preds. 1673eb388af89f15ee3de6f53359473e1a54418a667fChris Lattner // Any predecessor where the condition is not computable we keep symbolic. 1674d8b4fb4aab4d6fedb2b14bed1b846451b17bde7cJay Foad for (pred_iterator PI = PB; PI != PE; ++PI) { 1675625398343e2673a0c4bb5228fc88f71fe4e1c629Gabor Greif BasicBlock *P = *PI; 1676625398343e2673a0c4bb5228fc88f71fe4e1c629Gabor Greif if ((PBI = dyn_cast<BranchInst>(P->getTerminator())) && 1677867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner PBI != BI && PBI->isConditional() && 1678867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner PBI->getCondition() == BI->getCondition() && 1679867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner PBI->getSuccessor(0) != PBI->getSuccessor(1)) { 1680867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner bool CondIsTrue = PBI->getSuccessor(0) == BB; 16811d0be15f89cb5056e20e2d24faa8d6afb1573bcaOwen Anderson NewPN->addIncoming(ConstantInt::get(Type::getInt1Ty(BB->getContext()), 1682625398343e2673a0c4bb5228fc88f71fe4e1c629Gabor Greif CondIsTrue), P); 1683867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner } else { 1684625398343e2673a0c4bb5228fc88f71fe4e1c629Gabor Greif NewPN->addIncoming(BI->getCondition(), P); 1685867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner } 1686625398343e2673a0c4bb5228fc88f71fe4e1c629Gabor Greif } 1687867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner 1688867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner BI->setCondition(NewPN); 1689867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner return true; 1690867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner } 1691867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner } 1692867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner 1693867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner // If this is a conditional branch in an empty block, and if any 1694867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner // predecessors is a conditional branch to one of our destinations, 1695867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner // fold the conditions into logical ops and one cond br. 1696a8d57fe96bb870e4f69c6b522a78936d1495d0d2Zhou Sheng BasicBlock::iterator BBI = BB->begin(); 1697a8d57fe96bb870e4f69c6b522a78936d1495d0d2Zhou Sheng // Ignore dbg intrinsics. 1698a8d57fe96bb870e4f69c6b522a78936d1495d0d2Zhou Sheng while (isa<DbgInfoIntrinsic>(BBI)) 1699a8d57fe96bb870e4f69c6b522a78936d1495d0d2Zhou Sheng ++BBI; 1700a8d57fe96bb870e4f69c6b522a78936d1495d0d2Zhou Sheng if (&*BBI != BI) 1701b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner return false; 170263bf29b5b1c741038d6d502d62721cac0d2760b4Chris Lattner 170363bf29b5b1c741038d6d502d62721cac0d2760b4Chris Lattner 170463bf29b5b1c741038d6d502d62721cac0d2760b4Chris Lattner if (ConstantExpr *CE = dyn_cast<ConstantExpr>(BI->getCondition())) 170563bf29b5b1c741038d6d502d62721cac0d2760b4Chris Lattner if (CE->canTrap()) 170663bf29b5b1c741038d6d502d62721cac0d2760b4Chris Lattner return false; 1707b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner 1708b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner int PBIOp, BIOp; 1709b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner if (PBI->getSuccessor(0) == BI->getSuccessor(0)) 1710b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner PBIOp = BIOp = 0; 1711b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner else if (PBI->getSuccessor(0) == BI->getSuccessor(1)) 1712b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner PBIOp = 0, BIOp = 1; 1713b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner else if (PBI->getSuccessor(1) == BI->getSuccessor(0)) 1714b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner PBIOp = 1, BIOp = 0; 1715b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner else if (PBI->getSuccessor(1) == BI->getSuccessor(1)) 1716b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner PBIOp = BIOp = 1; 1717b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner else 1718b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner return false; 1719867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner 1720b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // Check to make sure that the other destination of this branch 1721b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // isn't BB itself. If so, this is an infinite loop that will 1722b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // keep getting unwound. 1723b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner if (PBI->getSuccessor(PBIOp) == BB) 1724b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner return false; 1725867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner 1726b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // Do not perform this transformation if it would require 1727b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // insertion of a large number of select instructions. For targets 1728b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // without predication/cmovs, this is a big pessimization. 1729b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner BasicBlock *CommonDest = PBI->getSuccessor(PBIOp); 1730867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner 1731b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner unsigned NumPhis = 0; 1732b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner for (BasicBlock::iterator II = CommonDest->begin(); 1733b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner isa<PHINode>(II); ++II, ++NumPhis) 1734b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner if (NumPhis > 2) // Disable this xform. 1735b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner return false; 1736867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner 1737b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // Finally, if everything is ok, fold the branches to logical ops. 1738b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner BasicBlock *OtherDest = BI->getSuccessor(BIOp ^ 1); 1739b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner 174089d6fd36a26fdf068ceea90422dc2897e89700b5David Greene DEBUG(dbgs() << "FOLDING BRs:" << *PBI->getParent() 1741bdff548e4dd577a72094d57b282de4e765643b96Chris Lattner << "AND: " << *BI->getParent()); 1742b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner 1743093a4385027235459ab6972b2e2fdc79061773cfChris Lattner 1744093a4385027235459ab6972b2e2fdc79061773cfChris Lattner // If OtherDest *is* BB, then BB is a basic block with a single conditional 1745093a4385027235459ab6972b2e2fdc79061773cfChris Lattner // branch in it, where one edge (OtherDest) goes back to itself but the other 1746093a4385027235459ab6972b2e2fdc79061773cfChris Lattner // exits. We don't *know* that the program avoids the infinite loop 1747093a4385027235459ab6972b2e2fdc79061773cfChris Lattner // (even though that seems likely). If we do this xform naively, we'll end up 1748093a4385027235459ab6972b2e2fdc79061773cfChris Lattner // recursively unpeeling the loop. Since we know that (after the xform is 1749093a4385027235459ab6972b2e2fdc79061773cfChris Lattner // done) that the block *is* infinite if reached, we just make it an obviously 1750093a4385027235459ab6972b2e2fdc79061773cfChris Lattner // infinite loop with no cond branch. 1751093a4385027235459ab6972b2e2fdc79061773cfChris Lattner if (OtherDest == BB) { 1752093a4385027235459ab6972b2e2fdc79061773cfChris Lattner // Insert it at the end of the function, because it's either code, 1753093a4385027235459ab6972b2e2fdc79061773cfChris Lattner // or it won't matter if it's hot. :) 17541d0be15f89cb5056e20e2d24faa8d6afb1573bcaOwen Anderson BasicBlock *InfLoopBlock = BasicBlock::Create(BB->getContext(), 17551d0be15f89cb5056e20e2d24faa8d6afb1573bcaOwen Anderson "infloop", BB->getParent()); 1756093a4385027235459ab6972b2e2fdc79061773cfChris Lattner BranchInst::Create(InfLoopBlock, InfLoopBlock); 1757093a4385027235459ab6972b2e2fdc79061773cfChris Lattner OtherDest = InfLoopBlock; 1758093a4385027235459ab6972b2e2fdc79061773cfChris Lattner } 1759093a4385027235459ab6972b2e2fdc79061773cfChris Lattner 176089d6fd36a26fdf068ceea90422dc2897e89700b5David Greene DEBUG(dbgs() << *PBI->getParent()->getParent()); 1761b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner 1762b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // BI may have other predecessors. Because of this, we leave 1763b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // it alone, but modify PBI. 1764b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner 1765b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // Make sure we get to CommonDest on True&True directions. 1766b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner Value *PBICond = PBI->getCondition(); 1767b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner if (PBIOp) 17684ae5126d041768ab9665cf2f11c024becd76c41fDan Gohman PBICond = BinaryOperator::CreateNot(PBICond, 1769b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner PBICond->getName()+".not", 1770b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner PBI); 1771b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner Value *BICond = BI->getCondition(); 1772b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner if (BIOp) 17734ae5126d041768ab9665cf2f11c024becd76c41fDan Gohman BICond = BinaryOperator::CreateNot(BICond, 1774b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner BICond->getName()+".not", 1775b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner PBI); 1776b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // Merge the conditions. 1777b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner Value *Cond = BinaryOperator::CreateOr(PBICond, BICond, "brmerge", PBI); 1778b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner 1779b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // Modify PBI to branch on the new condition to the new dests. 1780b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner PBI->setCondition(Cond); 1781b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner PBI->setSuccessor(0, CommonDest); 1782b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner PBI->setSuccessor(1, OtherDest); 1783b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner 1784b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // OtherDest may have phi nodes. If so, add an entry from PBI's 1785b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // block that are identical to the entries for BI's block. 17866de0a28dfb84095ebd7775f371dd4085cf955076Chris Lattner AddPredecessorToBlock(OtherDest, PBI->getParent(), BB); 1787b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner 1788b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // We know that the CommonDest already had an edge from PBI to 1789b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // it. If it has PHIs though, the PHIs may have different 1790b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // entries for BB and PBI's BB. If so, insert a select to make 1791b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // them agree. 17926de0a28dfb84095ebd7775f371dd4085cf955076Chris Lattner PHINode *PN; 1793b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner for (BasicBlock::iterator II = CommonDest->begin(); 1794b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner (PN = dyn_cast<PHINode>(II)); ++II) { 1795b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner Value *BIV = PN->getIncomingValueForBlock(BB); 1796b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner unsigned PBBIdx = PN->getBasicBlockIndex(PBI->getParent()); 1797b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner Value *PBIV = PN->getIncomingValue(PBBIdx); 1798b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner if (BIV != PBIV) { 1799b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // Insert a select in PBI to pick the right value. 1800b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner Value *NV = SelectInst::Create(PBICond, PBIV, BIV, 1801b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner PBIV->getName()+".mux", PBI); 1802b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner PN->setIncomingValue(PBBIdx, NV); 1803867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner } 1804867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner } 1805b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner 180689d6fd36a26fdf068ceea90422dc2897e89700b5David Greene DEBUG(dbgs() << "INTO: " << *PBI->getParent()); 180789d6fd36a26fdf068ceea90422dc2897e89700b5David Greene DEBUG(dbgs() << *PBI->getParent()->getParent()); 1808b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner 1809b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // This basic block is probably dead. We know it has at least 1810b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // one fewer predecessor. 1811b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner return true; 1812867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner} 1813867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner 181465fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel// SimplifyTerminatorOnSelect - Simplifies a terminator by replacing it with a 181565fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel// branch to TrueBB if Cond is true or to FalseBB if Cond is false. 181665fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel// Takes care of updating the successors and removing the old terminator. 181765fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel// Also makes sure not to introduce new successors by assuming that edges to 181865fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel// non-successor TrueBBs and FalseBBs aren't reachable. 181965fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommelstatic bool SimplifyTerminatorOnSelect(TerminatorInst *OldTerm, Value *Cond, 182065fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel BasicBlock *TrueBB, BasicBlock *FalseBB){ 18217ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel // Remove any superfluous successor edges from the CFG. 18227ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel // First, figure out which successors to preserve. 18237ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel // If TrueBB and FalseBB are equal, only try to preserve one copy of that 18247ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel // successor. 18257ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel BasicBlock *KeepEdge1 = TrueBB; 18267ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel BasicBlock *KeepEdge2 = TrueBB != FalseBB ? FalseBB : 0; 18277ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel 18287ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel // Then remove the rest. 182965fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel for (unsigned I = 0, E = OldTerm->getNumSuccessors(); I != E; ++I) { 183065fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel BasicBlock *Succ = OldTerm->getSuccessor(I); 18317ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel // Make sure only to keep exactly one copy of each edge. 18327ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel if (Succ == KeepEdge1) 18337ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel KeepEdge1 = 0; 18347ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel else if (Succ == KeepEdge2) 18357ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel KeepEdge2 = 0; 18367ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel else 183765fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel Succ->removePredecessor(OldTerm->getParent()); 18387ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel } 18397ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel 1840d3372b85e6008d85e30d13172ef0b1646b482b7eDevang Patel IRBuilder<> Builder(OldTerm); 1841d3372b85e6008d85e30d13172ef0b1646b482b7eDevang Patel Builder.SetCurrentDebugLocation(OldTerm->getDebugLoc()); 1842d3372b85e6008d85e30d13172ef0b1646b482b7eDevang Patel 18437ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel // Insert an appropriate new terminator. 18447ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel if ((KeepEdge1 == 0) && (KeepEdge2 == 0)) { 18457ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel if (TrueBB == FalseBB) 18467ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel // We were only looking for one successor, and it was present. 18477ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel // Create an unconditional branch to it. 1848d3372b85e6008d85e30d13172ef0b1646b482b7eDevang Patel Builder.CreateBr(TrueBB); 18497ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel else 18507ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel // We found both of the successors we were looking for. 18517ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel // Create a conditional branch sharing the condition of the select. 1852d3372b85e6008d85e30d13172ef0b1646b482b7eDevang Patel Builder.CreateCondBr(Cond, TrueBB, FalseBB); 18537ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel } else if (KeepEdge1 && (KeepEdge2 || TrueBB == FalseBB)) { 18547ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel // Neither of the selected blocks were successors, so this 185565fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel // terminator must be unreachable. 185665fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel new UnreachableInst(OldTerm->getContext(), OldTerm); 18577ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel } else { 18587ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel // One of the selected values was a successor, but the other wasn't. 18597ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel // Insert an unconditional branch to the one that was found; 18607ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel // the edge to the one that wasn't must be unreachable. 18617ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel if (KeepEdge1 == 0) 18627ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel // Only TrueBB was found. 1863d3372b85e6008d85e30d13172ef0b1646b482b7eDevang Patel Builder.CreateBr(TrueBB); 18647ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel else 18657ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel // Only FalseBB was found. 1866d3372b85e6008d85e30d13172ef0b1646b482b7eDevang Patel Builder.CreateBr(FalseBB); 18677ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel } 18687ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel 186965fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel EraseTerminatorInstAndDCECond(OldTerm); 18707ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel return true; 18717ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel} 18727ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel 1873f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel// SimplifySwitchOnSelect - Replaces 1874f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel// (switch (select cond, X, Y)) on constant X, Y 1875f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel// with a branch - conditional if X and Y lead to distinct BBs, 1876f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel// unconditional otherwise. 1877f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommelstatic bool SimplifySwitchOnSelect(SwitchInst *SI, SelectInst *Select) { 1878f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel // Check for constant integer values in the select. 1879f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel ConstantInt *TrueVal = dyn_cast<ConstantInt>(Select->getTrueValue()); 1880f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel ConstantInt *FalseVal = dyn_cast<ConstantInt>(Select->getFalseValue()); 1881f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel if (!TrueVal || !FalseVal) 1882f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel return false; 1883f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel 1884f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel // Find the relevant condition and destinations. 1885f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel Value *Condition = Select->getCondition(); 1886f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel BasicBlock *TrueBB = SI->getSuccessor(SI->findCaseValue(TrueVal)); 1887f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel BasicBlock *FalseBB = SI->getSuccessor(SI->findCaseValue(FalseVal)); 1888f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel 1889f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel // Perform the actual simplification. 1890f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel return SimplifyTerminatorOnSelect(SI, Condition, TrueBB, FalseBB); 1891f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel} 1892f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel 189365fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel// SimplifyIndirectBrOnSelect - Replaces 189465fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel// (indirectbr (select cond, blockaddress(@fn, BlockA), 189565fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel// blockaddress(@fn, BlockB))) 189665fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel// with 189765fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel// (br cond, BlockA, BlockB). 189865fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommelstatic bool SimplifyIndirectBrOnSelect(IndirectBrInst *IBI, SelectInst *SI) { 189965fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel // Check that both operands of the select are block addresses. 190065fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel BlockAddress *TBA = dyn_cast<BlockAddress>(SI->getTrueValue()); 190165fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel BlockAddress *FBA = dyn_cast<BlockAddress>(SI->getFalseValue()); 190265fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel if (!TBA || !FBA) 190365fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel return false; 190465fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel 190565fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel // Extract the actual blocks. 190665fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel BasicBlock *TrueBB = TBA->getBasicBlock(); 190765fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel BasicBlock *FalseBB = FBA->getBasicBlock(); 190865fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel 190965fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel // Perform the actual simplification. 191065fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel return SimplifyTerminatorOnSelect(IBI, SI->getCondition(), TrueBB, FalseBB); 191165fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel} 191265fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel 191361c77449c772427a0d2559fca500debd93c7f97cChris Lattner/// TryToSimplifyUncondBranchWithICmpInIt - This is called when we find an icmp 191461c77449c772427a0d2559fca500debd93c7f97cChris Lattner/// instruction (a seteq/setne with a constant) as the only instruction in a 191561c77449c772427a0d2559fca500debd93c7f97cChris Lattner/// block that ends with an uncond branch. We are looking for a very specific 191661c77449c772427a0d2559fca500debd93c7f97cChris Lattner/// pattern that occurs when "A == 1 || A == 2 || A == 3" gets simplified. In 191761c77449c772427a0d2559fca500debd93c7f97cChris Lattner/// this case, we merge the first two "or's of icmp" into a switch, but then the 191861c77449c772427a0d2559fca500debd93c7f97cChris Lattner/// default value goes to an uncond block with a seteq in it, we get something 191961c77449c772427a0d2559fca500debd93c7f97cChris Lattner/// like: 192061c77449c772427a0d2559fca500debd93c7f97cChris Lattner/// 192161c77449c772427a0d2559fca500debd93c7f97cChris Lattner/// switch i8 %A, label %DEFAULT [ i8 1, label %end i8 2, label %end ] 192261c77449c772427a0d2559fca500debd93c7f97cChris Lattner/// DEFAULT: 192361c77449c772427a0d2559fca500debd93c7f97cChris Lattner/// %tmp = icmp eq i8 %A, 92 192461c77449c772427a0d2559fca500debd93c7f97cChris Lattner/// br label %end 192561c77449c772427a0d2559fca500debd93c7f97cChris Lattner/// end: 192661c77449c772427a0d2559fca500debd93c7f97cChris Lattner/// ... = phi i1 [ true, %entry ], [ %tmp, %DEFAULT ], [ true, %entry ] 192761c77449c772427a0d2559fca500debd93c7f97cChris Lattner/// 192861c77449c772427a0d2559fca500debd93c7f97cChris Lattner/// We prefer to split the edge to 'end' so that there is a true/false entry to 192961c77449c772427a0d2559fca500debd93c7f97cChris Lattner/// the PHI, merging the third icmp into the switch. 1930302ba6fc1cb26248b0d6524fc42c740370926d6dChris Lattnerstatic bool TryToSimplifyUncondBranchWithICmpInIt(ICmpInst *ICI, 1931a23812cfbd23604d2fc103cf232cde8fa270a491Devang Patel const TargetData *TD, 1932a23812cfbd23604d2fc103cf232cde8fa270a491Devang Patel IRBuilder<> &Builder) { 193361c77449c772427a0d2559fca500debd93c7f97cChris Lattner BasicBlock *BB = ICI->getParent(); 1934a23812cfbd23604d2fc103cf232cde8fa270a491Devang Patel 193561c77449c772427a0d2559fca500debd93c7f97cChris Lattner // If the block has any PHIs in it or the icmp has multiple uses, it is too 193661c77449c772427a0d2559fca500debd93c7f97cChris Lattner // complex. 193761c77449c772427a0d2559fca500debd93c7f97cChris Lattner if (isa<PHINode>(BB->begin()) || !ICI->hasOneUse()) return false; 193861c77449c772427a0d2559fca500debd93c7f97cChris Lattner 193961c77449c772427a0d2559fca500debd93c7f97cChris Lattner Value *V = ICI->getOperand(0); 194061c77449c772427a0d2559fca500debd93c7f97cChris Lattner ConstantInt *Cst = cast<ConstantInt>(ICI->getOperand(1)); 194161c77449c772427a0d2559fca500debd93c7f97cChris Lattner 194261c77449c772427a0d2559fca500debd93c7f97cChris Lattner // The pattern we're looking for is where our only predecessor is a switch on 194361c77449c772427a0d2559fca500debd93c7f97cChris Lattner // 'V' and this block is the default case for the switch. In this case we can 194461c77449c772427a0d2559fca500debd93c7f97cChris Lattner // fold the compared value into the switch to simplify things. 194561c77449c772427a0d2559fca500debd93c7f97cChris Lattner BasicBlock *Pred = BB->getSinglePredecessor(); 194661c77449c772427a0d2559fca500debd93c7f97cChris Lattner if (Pred == 0 || !isa<SwitchInst>(Pred->getTerminator())) return false; 194761c77449c772427a0d2559fca500debd93c7f97cChris Lattner 194861c77449c772427a0d2559fca500debd93c7f97cChris Lattner SwitchInst *SI = cast<SwitchInst>(Pred->getTerminator()); 194961c77449c772427a0d2559fca500debd93c7f97cChris Lattner if (SI->getCondition() != V) 195061c77449c772427a0d2559fca500debd93c7f97cChris Lattner return false; 195161c77449c772427a0d2559fca500debd93c7f97cChris Lattner 195261c77449c772427a0d2559fca500debd93c7f97cChris Lattner // If BB is reachable on a non-default case, then we simply know the value of 195361c77449c772427a0d2559fca500debd93c7f97cChris Lattner // V in this block. Substitute it and constant fold the icmp instruction 195461c77449c772427a0d2559fca500debd93c7f97cChris Lattner // away. 195561c77449c772427a0d2559fca500debd93c7f97cChris Lattner if (SI->getDefaultDest() != BB) { 195661c77449c772427a0d2559fca500debd93c7f97cChris Lattner ConstantInt *VVal = SI->findCaseDest(BB); 195761c77449c772427a0d2559fca500debd93c7f97cChris Lattner assert(VVal && "Should have a unique destination value"); 195861c77449c772427a0d2559fca500debd93c7f97cChris Lattner ICI->setOperand(0, VVal); 195961c77449c772427a0d2559fca500debd93c7f97cChris Lattner 1960302ba6fc1cb26248b0d6524fc42c740370926d6dChris Lattner if (Value *V = SimplifyInstruction(ICI, TD)) { 1961302ba6fc1cb26248b0d6524fc42c740370926d6dChris Lattner ICI->replaceAllUsesWith(V); 196261c77449c772427a0d2559fca500debd93c7f97cChris Lattner ICI->eraseFromParent(); 196361c77449c772427a0d2559fca500debd93c7f97cChris Lattner } 196461c77449c772427a0d2559fca500debd93c7f97cChris Lattner // BB is now empty, so it is likely to simplify away. 196561c77449c772427a0d2559fca500debd93c7f97cChris Lattner return SimplifyCFG(BB) | true; 196661c77449c772427a0d2559fca500debd93c7f97cChris Lattner } 196761c77449c772427a0d2559fca500debd93c7f97cChris Lattner 1968abf706703fcbcde8fdc69b1bbdfb34e874813107Chris Lattner // Ok, the block is reachable from the default dest. If the constant we're 1969abf706703fcbcde8fdc69b1bbdfb34e874813107Chris Lattner // comparing exists in one of the other edges, then we can constant fold ICI 1970abf706703fcbcde8fdc69b1bbdfb34e874813107Chris Lattner // and zap it. 1971abf706703fcbcde8fdc69b1bbdfb34e874813107Chris Lattner if (SI->findCaseValue(Cst) != 0) { 1972abf706703fcbcde8fdc69b1bbdfb34e874813107Chris Lattner Value *V; 1973abf706703fcbcde8fdc69b1bbdfb34e874813107Chris Lattner if (ICI->getPredicate() == ICmpInst::ICMP_EQ) 1974abf706703fcbcde8fdc69b1bbdfb34e874813107Chris Lattner V = ConstantInt::getFalse(BB->getContext()); 1975abf706703fcbcde8fdc69b1bbdfb34e874813107Chris Lattner else 1976abf706703fcbcde8fdc69b1bbdfb34e874813107Chris Lattner V = ConstantInt::getTrue(BB->getContext()); 1977abf706703fcbcde8fdc69b1bbdfb34e874813107Chris Lattner 1978abf706703fcbcde8fdc69b1bbdfb34e874813107Chris Lattner ICI->replaceAllUsesWith(V); 1979abf706703fcbcde8fdc69b1bbdfb34e874813107Chris Lattner ICI->eraseFromParent(); 1980abf706703fcbcde8fdc69b1bbdfb34e874813107Chris Lattner // BB is now empty, so it is likely to simplify away. 1981abf706703fcbcde8fdc69b1bbdfb34e874813107Chris Lattner return SimplifyCFG(BB) | true; 1982abf706703fcbcde8fdc69b1bbdfb34e874813107Chris Lattner } 1983abf706703fcbcde8fdc69b1bbdfb34e874813107Chris Lattner 198461c77449c772427a0d2559fca500debd93c7f97cChris Lattner // The use of the icmp has to be in the 'end' block, by the only PHI node in 198561c77449c772427a0d2559fca500debd93c7f97cChris Lattner // the block. 198661c77449c772427a0d2559fca500debd93c7f97cChris Lattner BasicBlock *SuccBlock = BB->getTerminator()->getSuccessor(0); 198761c77449c772427a0d2559fca500debd93c7f97cChris Lattner PHINode *PHIUse = dyn_cast<PHINode>(ICI->use_back()); 198861c77449c772427a0d2559fca500debd93c7f97cChris Lattner if (PHIUse == 0 || PHIUse != &SuccBlock->front() || 198961c77449c772427a0d2559fca500debd93c7f97cChris Lattner isa<PHINode>(++BasicBlock::iterator(PHIUse))) 199061c77449c772427a0d2559fca500debd93c7f97cChris Lattner return false; 199161c77449c772427a0d2559fca500debd93c7f97cChris Lattner 199261c77449c772427a0d2559fca500debd93c7f97cChris Lattner // If the icmp is a SETEQ, then the default dest gets false, the new edge gets 199361c77449c772427a0d2559fca500debd93c7f97cChris Lattner // true in the PHI. 199461c77449c772427a0d2559fca500debd93c7f97cChris Lattner Constant *DefaultCst = ConstantInt::getTrue(BB->getContext()); 199561c77449c772427a0d2559fca500debd93c7f97cChris Lattner Constant *NewCst = ConstantInt::getFalse(BB->getContext()); 199661c77449c772427a0d2559fca500debd93c7f97cChris Lattner 199761c77449c772427a0d2559fca500debd93c7f97cChris Lattner if (ICI->getPredicate() == ICmpInst::ICMP_EQ) 199861c77449c772427a0d2559fca500debd93c7f97cChris Lattner std::swap(DefaultCst, NewCst); 199961c77449c772427a0d2559fca500debd93c7f97cChris Lattner 200061c77449c772427a0d2559fca500debd93c7f97cChris Lattner // Replace ICI (which is used by the PHI for the default value) with true or 200161c77449c772427a0d2559fca500debd93c7f97cChris Lattner // false depending on if it is EQ or NE. 200261c77449c772427a0d2559fca500debd93c7f97cChris Lattner ICI->replaceAllUsesWith(DefaultCst); 200361c77449c772427a0d2559fca500debd93c7f97cChris Lattner ICI->eraseFromParent(); 200461c77449c772427a0d2559fca500debd93c7f97cChris Lattner 200561c77449c772427a0d2559fca500debd93c7f97cChris Lattner // Okay, the switch goes to this block on a default value. Add an edge from 200661c77449c772427a0d2559fca500debd93c7f97cChris Lattner // the switch to the merge point on the compared value. 200761c77449c772427a0d2559fca500debd93c7f97cChris Lattner BasicBlock *NewBB = BasicBlock::Create(BB->getContext(), "switch.edge", 200861c77449c772427a0d2559fca500debd93c7f97cChris Lattner BB->getParent(), BB); 200961c77449c772427a0d2559fca500debd93c7f97cChris Lattner SI->addCase(Cst, NewBB); 201061c77449c772427a0d2559fca500debd93c7f97cChris Lattner 201161c77449c772427a0d2559fca500debd93c7f97cChris Lattner // NewBB branches to the phi block, add the uncond branch and the phi entry. 2012a23812cfbd23604d2fc103cf232cde8fa270a491Devang Patel Builder.SetInsertPoint(NewBB); 2013a23812cfbd23604d2fc103cf232cde8fa270a491Devang Patel Builder.SetCurrentDebugLocation(SI->getDebugLoc()); 2014a23812cfbd23604d2fc103cf232cde8fa270a491Devang Patel Builder.CreateBr(SuccBlock); 201561c77449c772427a0d2559fca500debd93c7f97cChris Lattner PHIUse->addIncoming(NewCst, NewBB); 201661c77449c772427a0d2559fca500debd93c7f97cChris Lattner return true; 201761c77449c772427a0d2559fca500debd93c7f97cChris Lattner} 201861c77449c772427a0d2559fca500debd93c7f97cChris Lattner 201997fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner/// SimplifyBranchOnICmpChain - The specified branch is a conditional branch. 202097fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner/// Check to see if it is branching on an or/and chain of icmp instructions, and 202197fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner/// fold it into a switch instruction if so. 202297fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattnerstatic bool SimplifyBranchOnICmpChain(BranchInst *BI, const TargetData *TD) { 202397fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner Instruction *Cond = dyn_cast<Instruction>(BI->getCondition()); 202497fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner if (Cond == 0) return false; 202597fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner 202697fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner 202797fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner // Change br (X == 0 | X == 1), T, F into a switch instruction. 202897fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner // If this is a bunch of seteq's or'd together, or if it's a bunch of 202997fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner // 'setne's and'ed together, collect them. 203097fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner Value *CompVal = 0; 203197fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner std::vector<ConstantInt*> Values; 203297fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner bool TrueWhenEqual = true; 203397fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner Value *ExtraCase = 0; 203433828bcb24176aae72afac0e4953e4b7f9560ef1Benjamin Kramer unsigned UsedICmps = 0; 203597fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner 203697fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner if (Cond->getOpcode() == Instruction::Or) { 203733828bcb24176aae72afac0e4953e4b7f9560ef1Benjamin Kramer CompVal = GatherConstantCompares(Cond, Values, ExtraCase, TD, true, 203833828bcb24176aae72afac0e4953e4b7f9560ef1Benjamin Kramer UsedICmps); 203997fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner } else if (Cond->getOpcode() == Instruction::And) { 204033828bcb24176aae72afac0e4953e4b7f9560ef1Benjamin Kramer CompVal = GatherConstantCompares(Cond, Values, ExtraCase, TD, false, 204133828bcb24176aae72afac0e4953e4b7f9560ef1Benjamin Kramer UsedICmps); 204297fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner TrueWhenEqual = false; 204397fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner } 204497fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner 204597fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner // If we didn't have a multiply compared value, fail. 204697fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner if (CompVal == 0) return false; 204797fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner 204833828bcb24176aae72afac0e4953e4b7f9560ef1Benjamin Kramer // Avoid turning single icmps into a switch. 204933828bcb24176aae72afac0e4953e4b7f9560ef1Benjamin Kramer if (UsedICmps <= 1) 205033828bcb24176aae72afac0e4953e4b7f9560ef1Benjamin Kramer return false; 205133828bcb24176aae72afac0e4953e4b7f9560ef1Benjamin Kramer 205297fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner // There might be duplicate constants in the list, which the switch 205397fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner // instruction can't handle, remove them now. 205497fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner array_pod_sort(Values.begin(), Values.end(), ConstantIntSortPredicate); 205597fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner Values.erase(std::unique(Values.begin(), Values.end()), Values.end()); 205697fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner 205797fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner // If Extra was used, we require at least two switch values to do the 205897fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner // transformation. A switch with one value is just an cond branch. 205997fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner if (ExtraCase && Values.size() < 2) return false; 206097fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner 206197fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner // Figure out which block is which destination. 206297fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner BasicBlock *DefaultBB = BI->getSuccessor(1); 206397fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner BasicBlock *EdgeBB = BI->getSuccessor(0); 206497fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner if (!TrueWhenEqual) std::swap(DefaultBB, EdgeBB); 206597fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner 206697fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner BasicBlock *BB = BI->getParent(); 206797fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner 2068302ba6fc1cb26248b0d6524fc42c740370926d6dChris Lattner DEBUG(dbgs() << "Converting 'icmp' chain with " << Values.size() 2069117f8cffc5499217ff8824eb0d6a0f6b1b78d96eChris Lattner << " cases into SWITCH. BB is:\n" << *BB); 2070117f8cffc5499217ff8824eb0d6a0f6b1b78d96eChris Lattner 207197fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner // If there are any extra values that couldn't be folded into the switch 207297fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner // then we evaluate them with an explicit branch first. Split the block 207397fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner // right before the condbr to handle it. 207497fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner if (ExtraCase) { 207597fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner BasicBlock *NewBB = BB->splitBasicBlock(BI, "switch.early.test"); 207697fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner // Remove the uncond branch added to the old block. 207797fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner TerminatorInst *OldTI = BB->getTerminator(); 207897fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner 2079117f8cffc5499217ff8824eb0d6a0f6b1b78d96eChris Lattner if (TrueWhenEqual) 2080117f8cffc5499217ff8824eb0d6a0f6b1b78d96eChris Lattner BranchInst::Create(EdgeBB, NewBB, ExtraCase, OldTI); 2081117f8cffc5499217ff8824eb0d6a0f6b1b78d96eChris Lattner else 2082117f8cffc5499217ff8824eb0d6a0f6b1b78d96eChris Lattner BranchInst::Create(NewBB, EdgeBB, ExtraCase, OldTI); 2083117f8cffc5499217ff8824eb0d6a0f6b1b78d96eChris Lattner 208497fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner OldTI->eraseFromParent(); 208597bd89ece3fff29ab7e0eaa38f85183abd962f42Chris Lattner 208697bd89ece3fff29ab7e0eaa38f85183abd962f42Chris Lattner // If there are PHI nodes in EdgeBB, then we need to add a new entry to them 208797bd89ece3fff29ab7e0eaa38f85183abd962f42Chris Lattner // for the edge we just added. 20886de0a28dfb84095ebd7775f371dd4085cf955076Chris Lattner AddPredecessorToBlock(EdgeBB, BB, NewBB); 2089302ba6fc1cb26248b0d6524fc42c740370926d6dChris Lattner 2090302ba6fc1cb26248b0d6524fc42c740370926d6dChris Lattner DEBUG(dbgs() << " ** 'icmp' chain unhandled condition: " << *ExtraCase 2091302ba6fc1cb26248b0d6524fc42c740370926d6dChris Lattner << "\nEXTRABB = " << *BB); 209297fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner BB = NewBB; 209397fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner } 209497fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner 209597fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner // Convert pointer to int before we switch. 209697fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner if (CompVal->getType()->isPointerTy()) { 209797fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner assert(TD && "Cannot switch on pointer without TargetData"); 209897fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner CompVal = new PtrToIntInst(CompVal, 209997fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner TD->getIntPtrType(CompVal->getContext()), 210097fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner "magicptr", BI); 2101d80e8ed2fa20c7ad51af49c3b2650525edbdcd08Devang Patel cast<PtrToIntInst>(CompVal)->setDebugLoc(BI->getDebugLoc()); 210297fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner } 210397fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner 210497fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner // Create the new switch instruction now. 21053d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner SwitchInst *New = SwitchInst::Create(CompVal, DefaultBB, Values.size(), BI); 2106d80e8ed2fa20c7ad51af49c3b2650525edbdcd08Devang Patel New->setDebugLoc(BI->getDebugLoc()); 2107d80e8ed2fa20c7ad51af49c3b2650525edbdcd08Devang Patel 210897fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner // Add all of the 'cases' to the switch instruction. 210997fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner for (unsigned i = 0, e = Values.size(); i != e; ++i) 211097fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner New->addCase(Values[i], EdgeBB); 211197fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner 211297fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner // We added edges from PI to the EdgeBB. As such, if there were any 211397fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner // PHI nodes in EdgeBB, they need entries to be added corresponding to 211497fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner // the number of edges added. 211597fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner for (BasicBlock::iterator BBI = EdgeBB->begin(); 211697fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner isa<PHINode>(BBI); ++BBI) { 211797fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner PHINode *PN = cast<PHINode>(BBI); 211897fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner Value *InVal = PN->getIncomingValueForBlock(BB); 211997fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner for (unsigned i = 0, e = Values.size()-1; i != e; ++i) 212097fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner PN->addIncoming(InVal, BB); 212197fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner } 212297fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner 212397fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner // Erase the old branch instruction. 212497fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner EraseTerminatorInstAndDCECond(BI); 2125117f8cffc5499217ff8824eb0d6a0f6b1b78d96eChris Lattner 2126302ba6fc1cb26248b0d6524fc42c740370926d6dChris Lattner DEBUG(dbgs() << " ** 'icmp' chain result is:\n" << *BB << '\n'); 212797fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner return true; 212897fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner} 212997fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner 21303d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattnerbool SimplifyCFGOpt::SimplifyReturn(ReturnInst *RI) { 21313d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BasicBlock *BB = RI->getParent(); 21323d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (!BB->getFirstNonPHIOrDbg()->isTerminator()) return false; 21333d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 21343d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // Find predecessors that end with branches. 21353d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner SmallVector<BasicBlock*, 8> UncondBranchPreds; 21363d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner SmallVector<BranchInst*, 8> CondBranchPreds; 21373d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI) { 21383d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BasicBlock *P = *PI; 21393d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner TerminatorInst *PTI = P->getTerminator(); 21403d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (BranchInst *BI = dyn_cast<BranchInst>(PTI)) { 21413d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (BI->isUnconditional()) 21423d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner UncondBranchPreds.push_back(P); 21433d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner else 21443d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner CondBranchPreds.push_back(BI); 21453d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } 21463d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } 21473d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 21483d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // If we found some, do the transformation! 2149c3f507f98a0747bd256e1c13536060b6fc5c4b62Evan Cheng if (!UncondBranchPreds.empty() && DupRet) { 21503d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner while (!UncondBranchPreds.empty()) { 21513d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BasicBlock *Pred = UncondBranchPreds.pop_back_val(); 21523d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner DEBUG(dbgs() << "FOLDING: " << *BB 21533d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner << "INTO UNCOND BRANCH PRED: " << *Pred); 2154c3f507f98a0747bd256e1c13536060b6fc5c4b62Evan Cheng (void)FoldReturnIntoUncondBranch(RI, BB, Pred); 21553d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } 21563d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 21573d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // If we eliminated all predecessors of the block, delete the block now. 21583d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (pred_begin(BB) == pred_end(BB)) 21593d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // We know there are no successors, so just nuke the block. 21603d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BB->eraseFromParent(); 21613d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 216201d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner return true; 216301d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner } 21643d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 21653d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // Check out all of the conditional branches going to this return 21663d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // instruction. If any of them just select between returns, change the 21673d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // branch itself into a select/return pair. 21683d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner while (!CondBranchPreds.empty()) { 21693d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BranchInst *BI = CondBranchPreds.pop_back_val(); 21703d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 21713d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // Check to see if the non-BB successor is also a return block. 21723d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (isa<ReturnInst>(BI->getSuccessor(0)->getTerminator()) && 21733d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner isa<ReturnInst>(BI->getSuccessor(1)->getTerminator()) && 21743d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner SimplifyCondBranchToTwoReturns(BI)) 21753d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner return true; 21763d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } 21773d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner return false; 21783d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner} 217901d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner 2180d46ba26a6b513086ad575e5db0069b03d41fca13Devang Patelbool SimplifyCFGOpt::SimplifyUnwind(UnwindInst *UI, IRBuilder<> &Builder) { 21813d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // Check to see if the first instruction in this block is just an unwind. 21823d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // If so, replace any invoke instructions which use this as an exception 21833d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // destination with call instructions. 21843d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BasicBlock *BB = UI->getParent(); 21853d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (!BB->getFirstNonPHIOrDbg()->isTerminator()) return false; 21862c63566e406974caa70ee27f35af28112e80f951Dan Gohman 21873d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner bool Changed = false; 21883d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner SmallVector<BasicBlock*, 8> Preds(pred_begin(BB), pred_end(BB)); 21893d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner while (!Preds.empty()) { 21903d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BasicBlock *Pred = Preds.back(); 21913d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner InvokeInst *II = dyn_cast<InvokeInst>(Pred->getTerminator()); 21923d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (II && II->getUnwindDest() == BB) { 21933d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // Insert a new branch instruction before the invoke, because this 21943d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // is now a fall through. 2195d46ba26a6b513086ad575e5db0069b03d41fca13Devang Patel Builder.SetInsertPoint(II); 2196d46ba26a6b513086ad575e5db0069b03d41fca13Devang Patel BranchInst *BI = Builder.CreateBr(II->getNormalDest()); 21973d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner Pred->getInstList().remove(II); // Take out of symbol table 21983d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 21993d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // Insert the call now. 22003d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner SmallVector<Value*,8> Args(II->op_begin(), II->op_end()-3); 2201d46ba26a6b513086ad575e5db0069b03d41fca13Devang Patel Builder.SetInsertPoint(BI); 2202d46ba26a6b513086ad575e5db0069b03d41fca13Devang Patel CallInst *CI = Builder.CreateCall(II->getCalledValue(), 2203d46ba26a6b513086ad575e5db0069b03d41fca13Devang Patel Args.begin(), Args.end(), 2204d46ba26a6b513086ad575e5db0069b03d41fca13Devang Patel II->getName()); 22053d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner CI->setCallingConv(II->getCallingConv()); 22063d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner CI->setAttributes(II->getAttributes()); 22073d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // If the invoke produced a value, the Call now does instead. 22083d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner II->replaceAllUsesWith(CI); 22093d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner delete II; 22103d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner Changed = true; 22113d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } 22123d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 22133d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner Preds.pop_back(); 22143d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } 22153d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 22163d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // If this block is now dead (and isn't the entry block), remove it. 22173d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (pred_begin(BB) == pred_end(BB) && 22183d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BB != &BB->getParent()->getEntryBlock()) { 22193d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // We know there are no successors, so just nuke the block. 22203d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BB->eraseFromParent(); 2221ddb97a2bf1f06d7d1b0a1af8e74c67917b43b606Chris Lattner return true; 22223d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } 2223ddb97a2bf1f06d7d1b0a1af8e74c67917b43b606Chris Lattner 22243d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner return Changed; 22253d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner} 2226882d87d168374ce790621e9ad4d7304b9dff0d78Dan Gohman 22273d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattnerbool SimplifyCFGOpt::SimplifyUnreachable(UnreachableInst *UI) { 22283d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BasicBlock *BB = UI->getParent(); 22293d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 22303d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner bool Changed = false; 22313d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 22323d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // If there are any instructions immediately before the unreachable that can 22333d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // be removed, do so. 22343d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner while (UI != BB->begin()) { 22353d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BasicBlock::iterator BBI = UI; 22363d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner --BBI; 22373d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // Do not delete instructions that can have side effects, like calls 22383d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // (which may never return) and volatile loads and stores. 22393d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (isa<CallInst>(BBI) && !isa<DbgInfoIntrinsic>(BBI)) break; 22403d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 22413d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (StoreInst *SI = dyn_cast<StoreInst>(BBI)) 22423d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (SI->isVolatile()) 22433d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner break; 22443d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 22453d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (LoadInst *LI = dyn_cast<LoadInst>(BBI)) 22463d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (LI->isVolatile()) 22473d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner break; 22483d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 22492adc5b6a17268834b08fda444b1a84550e8c5ae8Eli Friedman // Delete this instruction (any uses are guaranteed to be dead) 22502adc5b6a17268834b08fda444b1a84550e8c5ae8Eli Friedman if (!BBI->use_empty()) 22512adc5b6a17268834b08fda444b1a84550e8c5ae8Eli Friedman BBI->replaceAllUsesWith(UndefValue::get(BBI->getType())); 2252302ba6fc1cb26248b0d6524fc42c740370926d6dChris Lattner BBI->eraseFromParent(); 22533d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner Changed = true; 22543d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } 22553d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 22563d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // If the unreachable instruction is the first in the block, take a gander 22573d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // at all of the predecessors of this instruction, and simplify them. 22583d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (&BB->front() != UI) return Changed; 22593d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 22603d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner SmallVector<BasicBlock*, 8> Preds(pred_begin(BB), pred_end(BB)); 22613d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner for (unsigned i = 0, e = Preds.size(); i != e; ++i) { 22623d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner TerminatorInst *TI = Preds[i]->getTerminator(); 22633d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 22643d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (BranchInst *BI = dyn_cast<BranchInst>(TI)) { 22653d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (BI->isUnconditional()) { 22663d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (BI->getSuccessor(0) == BB) { 22673d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner new UnreachableInst(TI->getContext(), TI); 22683d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner TI->eraseFromParent(); 22693d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner Changed = true; 22703d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } 22713d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } else { 22723d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (BI->getSuccessor(0) == BB) { 22733d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BranchInst::Create(BI->getSuccessor(1), BI); 22743d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner EraseTerminatorInstAndDCECond(BI); 22753d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } else if (BI->getSuccessor(1) == BB) { 22763d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BranchInst::Create(BI->getSuccessor(0), BI); 22773d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner EraseTerminatorInstAndDCECond(BI); 22783d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner Changed = true; 227907e6e56f57e8781a8d7bc601cc9034a3741d84c2Anton Korobeynikov } 228019831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner } 22813d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } else if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) { 22823d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner for (unsigned i = 1, e = SI->getNumCases(); i != e; ++i) 22833d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (SI->getSuccessor(i) == BB) { 22843d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BB->removePredecessor(SI->getParent()); 22853d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner SI->removeCase(i); 22863d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner --i; --e; 22873d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner Changed = true; 22883d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } 22893d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // If the default value is unreachable, figure out the most popular 22903d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // destination and make it the default. 22913d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (SI->getSuccessor(0) == BB) { 2292b1a6eab655adce4f84a15afa9092e814b9aaabdaEli Friedman std::map<BasicBlock*, std::pair<unsigned, unsigned> > Popularity; 2293b1a6eab655adce4f84a15afa9092e814b9aaabdaEli Friedman for (unsigned i = 1, e = SI->getNumCases(); i != e; ++i) { 2294b1a6eab655adce4f84a15afa9092e814b9aaabdaEli Friedman std::pair<unsigned, unsigned>& entry = 2295b1a6eab655adce4f84a15afa9092e814b9aaabdaEli Friedman Popularity[SI->getSuccessor(i)]; 2296b1a6eab655adce4f84a15afa9092e814b9aaabdaEli Friedman if (entry.first == 0) { 2297b1a6eab655adce4f84a15afa9092e814b9aaabdaEli Friedman entry.first = 1; 2298b1a6eab655adce4f84a15afa9092e814b9aaabdaEli Friedman entry.second = i; 2299b1a6eab655adce4f84a15afa9092e814b9aaabdaEli Friedman } else { 2300b1a6eab655adce4f84a15afa9092e814b9aaabdaEli Friedman entry.first++; 2301b1a6eab655adce4f84a15afa9092e814b9aaabdaEli Friedman } 2302b1a6eab655adce4f84a15afa9092e814b9aaabdaEli Friedman } 2303b1a6eab655adce4f84a15afa9092e814b9aaabdaEli Friedman 23043d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // Find the most popular block. 23053d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner unsigned MaxPop = 0; 2306b1a6eab655adce4f84a15afa9092e814b9aaabdaEli Friedman unsigned MaxIndex = 0; 23073d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BasicBlock *MaxBlock = 0; 2308b1a6eab655adce4f84a15afa9092e814b9aaabdaEli Friedman for (std::map<BasicBlock*, std::pair<unsigned, unsigned> >::iterator 23093d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner I = Popularity.begin(), E = Popularity.end(); I != E; ++I) { 2310b1a6eab655adce4f84a15afa9092e814b9aaabdaEli Friedman if (I->second.first > MaxPop || 2311b1a6eab655adce4f84a15afa9092e814b9aaabdaEli Friedman (I->second.first == MaxPop && MaxIndex > I->second.second)) { 2312b1a6eab655adce4f84a15afa9092e814b9aaabdaEli Friedman MaxPop = I->second.first; 2313b1a6eab655adce4f84a15afa9092e814b9aaabdaEli Friedman MaxIndex = I->second.second; 23143d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner MaxBlock = I->first; 23153d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } 23163d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } 23173d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (MaxBlock) { 23183d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // Make this the new default, allowing us to delete any explicit 23193d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // edges to it. 23203d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner SI->setSuccessor(0, MaxBlock); 23213d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner Changed = true; 2322ffba5821eee7b7a6139f9dfb06b8d306bf344a9dChris Lattner 23233d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // If MaxBlock has phinodes in it, remove MaxPop-1 entries from 23243d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // it. 23253d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (isa<PHINode>(MaxBlock->begin())) 23263d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner for (unsigned i = 0; i != MaxPop-1; ++i) 23273d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner MaxBlock->removePredecessor(SI->getParent()); 23283d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 23293d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner for (unsigned i = 1, e = SI->getNumCases(); i != e; ++i) 23303d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (SI->getSuccessor(i) == MaxBlock) { 23313d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner SI->removeCase(i); 23323d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner --i; --e; 23333d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } 233419831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner } 233519831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner } 23363d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } else if (InvokeInst *II = dyn_cast<InvokeInst>(TI)) { 23373d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (II->getUnwindDest() == BB) { 23383d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // Convert the invoke to a call instruction. This would be a good 23393d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // place to note that the call does not throw though. 23409a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner BranchInst *BI = BranchInst::Create(II->getNormalDest(), II); 23413d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner II->removeFromParent(); // Take out of symbol table 23423d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 23433d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // Insert the call now... 23443d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner SmallVector<Value*, 8> Args(II->op_begin(), II->op_end()-3); 23459a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner CallInst *CI = CallInst::Create(II->getCalledValue(), 23469a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner Args.begin(), Args.end(), 23479a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner II->getName(), BI); 23489a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner CI->setCallingConv(II->getCallingConv()); 23499a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner CI->setAttributes(II->getAttributes()); 23503d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // If the invoke produced a value, the call does now instead. 23519a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner II->replaceAllUsesWith(CI); 23529a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner delete II; 23539a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner Changed = true; 23549a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner } 2355e14ea0804afba2ac5824507571a220d05b0aa21dChris Lattner } 23563d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } 23573d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 23583d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // If this block is now dead, remove it. 23593d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (pred_begin(BB) == pred_end(BB) && 23603d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BB != &BB->getParent()->getEntryBlock()) { 23613d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // We know there are no successors, so just nuke the block. 23623d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BB->eraseFromParent(); 23633d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner return true; 23643d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } 23658e509dd5e81e92a466580ab4022994079952cca9Chris Lattner 23663d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner return Changed; 23673d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner} 23688e509dd5e81e92a466580ab4022994079952cca9Chris Lattner 236956442dfdcf7b07c04b585de5205b9427b1739895Benjamin Kramer/// TurnSwitchRangeIntoICmp - Turns a switch with that contains only a 237056442dfdcf7b07c04b585de5205b9427b1739895Benjamin Kramer/// integer range comparison into a sub, an icmp and a branch. 2371007349dafda47296177fd7481aff9764d4179f42Devang Patelstatic bool TurnSwitchRangeIntoICmp(SwitchInst *SI, IRBuilder<> &Builder) { 237256442dfdcf7b07c04b585de5205b9427b1739895Benjamin Kramer assert(SI->getNumCases() > 2 && "Degenerate switch?"); 2373042b27f40e4b1dcae70c0e98c3b4f5760dd8fa9bBenjamin Kramer 2374042b27f40e4b1dcae70c0e98c3b4f5760dd8fa9bBenjamin Kramer // Make sure all cases point to the same destination and gather the values. 2375042b27f40e4b1dcae70c0e98c3b4f5760dd8fa9bBenjamin Kramer SmallVector<ConstantInt *, 16> Cases; 2376042b27f40e4b1dcae70c0e98c3b4f5760dd8fa9bBenjamin Kramer Cases.push_back(SI->getCaseValue(1)); 2377042b27f40e4b1dcae70c0e98c3b4f5760dd8fa9bBenjamin Kramer for (unsigned I = 2, E = SI->getNumCases(); I != E; ++I) { 2378042b27f40e4b1dcae70c0e98c3b4f5760dd8fa9bBenjamin Kramer if (SI->getSuccessor(I-1) != SI->getSuccessor(I)) 237956442dfdcf7b07c04b585de5205b9427b1739895Benjamin Kramer return false; 2380042b27f40e4b1dcae70c0e98c3b4f5760dd8fa9bBenjamin Kramer Cases.push_back(SI->getCaseValue(I)); 2381042b27f40e4b1dcae70c0e98c3b4f5760dd8fa9bBenjamin Kramer } 2382042b27f40e4b1dcae70c0e98c3b4f5760dd8fa9bBenjamin Kramer assert(Cases.size() == SI->getNumCases()-1 && "Not all cases gathered"); 2383042b27f40e4b1dcae70c0e98c3b4f5760dd8fa9bBenjamin Kramer 2384042b27f40e4b1dcae70c0e98c3b4f5760dd8fa9bBenjamin Kramer // Sort the case values, then check if they form a range we can transform. 2385042b27f40e4b1dcae70c0e98c3b4f5760dd8fa9bBenjamin Kramer array_pod_sort(Cases.begin(), Cases.end(), ConstantIntSortPredicate); 2386042b27f40e4b1dcae70c0e98c3b4f5760dd8fa9bBenjamin Kramer for (unsigned I = 1, E = Cases.size(); I != E; ++I) { 2387042b27f40e4b1dcae70c0e98c3b4f5760dd8fa9bBenjamin Kramer if (Cases[I-1]->getValue() != Cases[I]->getValue()+1) 2388042b27f40e4b1dcae70c0e98c3b4f5760dd8fa9bBenjamin Kramer return false; 2389042b27f40e4b1dcae70c0e98c3b4f5760dd8fa9bBenjamin Kramer } 239056442dfdcf7b07c04b585de5205b9427b1739895Benjamin Kramer 2391042b27f40e4b1dcae70c0e98c3b4f5760dd8fa9bBenjamin Kramer Constant *Offset = ConstantExpr::getNeg(Cases.back()); 239256442dfdcf7b07c04b585de5205b9427b1739895Benjamin Kramer Constant *NumCases = ConstantInt::get(Offset->getType(), SI->getNumCases()-1); 239356442dfdcf7b07c04b585de5205b9427b1739895Benjamin Kramer 239433828bcb24176aae72afac0e4953e4b7f9560ef1Benjamin Kramer Value *Sub = SI->getCondition(); 239533828bcb24176aae72afac0e4953e4b7f9560ef1Benjamin Kramer if (!Offset->isNullValue()) 239633828bcb24176aae72afac0e4953e4b7f9560ef1Benjamin Kramer Sub = BinaryOperator::CreateAdd(Sub, Offset, Sub->getName()+".off", SI); 239756442dfdcf7b07c04b585de5205b9427b1739895Benjamin Kramer Value *Cmp = new ICmpInst(SI, ICmpInst::ICMP_ULT, Sub, NumCases, "switch"); 2398007349dafda47296177fd7481aff9764d4179f42Devang Patel Builder.CreateCondBr(Cmp, SI->getSuccessor(1), SI->getDefaultDest()); 239956442dfdcf7b07c04b585de5205b9427b1739895Benjamin Kramer 240056442dfdcf7b07c04b585de5205b9427b1739895Benjamin Kramer // Prune obsolete incoming values off the successor's PHI nodes. 240156442dfdcf7b07c04b585de5205b9427b1739895Benjamin Kramer for (BasicBlock::iterator BBI = SI->getSuccessor(1)->begin(); 240256442dfdcf7b07c04b585de5205b9427b1739895Benjamin Kramer isa<PHINode>(BBI); ++BBI) { 240356442dfdcf7b07c04b585de5205b9427b1739895Benjamin Kramer for (unsigned I = 0, E = SI->getNumCases()-2; I != E; ++I) 240456442dfdcf7b07c04b585de5205b9427b1739895Benjamin Kramer cast<PHINode>(BBI)->removeIncomingValue(SI->getParent()); 240556442dfdcf7b07c04b585de5205b9427b1739895Benjamin Kramer } 240656442dfdcf7b07c04b585de5205b9427b1739895Benjamin Kramer SI->eraseFromParent(); 240756442dfdcf7b07c04b585de5205b9427b1739895Benjamin Kramer 240856442dfdcf7b07c04b585de5205b9427b1739895Benjamin Kramer return true; 240956442dfdcf7b07c04b585de5205b9427b1739895Benjamin Kramer} 2410d0a203d76f4ef77ae1c392e8e73e2f05b676a5f2Devang Patel 241110fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer/// EliminateDeadSwitchCases - Compute masked bits for the condition of a switch 241210fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer/// and use it to remove dead cases. 241310fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramerstatic bool EliminateDeadSwitchCases(SwitchInst *SI) { 241410fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer Value *Cond = SI->getCondition(); 241510fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer unsigned Bits = cast<IntegerType>(Cond->getType())->getBitWidth(); 241610fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer APInt KnownZero(Bits, 0), KnownOne(Bits, 0); 241710fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer ComputeMaskedBits(Cond, APInt::getAllOnesValue(Bits), KnownZero, KnownOne); 241810fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer 241910fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer // Gather dead cases. 242010fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer SmallVector<ConstantInt*, 8> DeadCases; 242110fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer for (unsigned I = 1, E = SI->getNumCases(); I != E; ++I) { 242210fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer if ((SI->getCaseValue(I)->getValue() & KnownZero) != 0 || 242310fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer (SI->getCaseValue(I)->getValue() & KnownOne) != KnownOne) { 242410fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer DeadCases.push_back(SI->getCaseValue(I)); 242510fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer DEBUG(dbgs() << "SimplifyCFG: switch case '" 242610fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer << SI->getCaseValue(I)->getValue() << "' is dead.\n"); 242710fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer } 242810fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer } 242910fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer 243010fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer // Remove dead cases from the switch. 243110fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer for (unsigned I = 0, E = DeadCases.size(); I != E; ++I) { 243210fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer unsigned Case = SI->findCaseValue(DeadCases[I]); 243310fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer // Prune unused values from PHI nodes. 243410fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer SI->getSuccessor(Case)->removePredecessor(SI->getParent()); 243510fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer SI->removeCase(Case); 243610fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer } 243710fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer 243810fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer return !DeadCases.empty(); 243910fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer} 244010fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer 2441007349dafda47296177fd7481aff9764d4179f42Devang Patelbool SimplifyCFGOpt::SimplifySwitch(SwitchInst *SI, IRBuilder<> &Builder) { 24423d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // If this switch is too complex to want to look at, ignore it. 24433d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (!isValueEqualityComparison(SI)) 24443d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner return false; 2445e67fa05036f634a4ec1e0893033c89250eb58954Chris Lattner 24463d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BasicBlock *BB = SI->getParent(); 24473d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 24483d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // If we only have one predecessor, and if it is a branch on this value, 24493d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // see if that predecessor totally determines the outcome of this switch. 24503d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (BasicBlock *OnlyPred = BB->getSinglePredecessor()) 2451007349dafda47296177fd7481aff9764d4179f42Devang Patel if (SimplifyEqualityComparisonWithOnlyPredecessor(SI, OnlyPred, Builder)) 2452021c9d3bd41bc446ef0860c05a073e32afa5e20fChris Lattner return SimplifyCFG(BB) | true; 2453f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel 2454f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel Value *Cond = SI->getCondition(); 2455f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel if (SelectInst *Select = dyn_cast<SelectInst>(Cond)) 2456f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel if (SimplifySwitchOnSelect(SI, Select)) 2457f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel return SimplifyCFG(BB) | true; 2458f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel 24593d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // If the block only contains the switch, see if we can fold the block 24603d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // away into any preds. 24613d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BasicBlock::iterator BBI = BB->begin(); 24623d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // Ignore dbg intrinsics. 24633d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner while (isa<DbgInfoIntrinsic>(BBI)) 24643d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner ++BBI; 24653d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (SI == &*BBI) 24663d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (FoldValueComparisonIntoPredecessors(SI)) 2467021c9d3bd41bc446ef0860c05a073e32afa5e20fChris Lattner return SimplifyCFG(BB) | true; 246856442dfdcf7b07c04b585de5205b9427b1739895Benjamin Kramer 246956442dfdcf7b07c04b585de5205b9427b1739895Benjamin Kramer // Try to transform the switch into an icmp and a branch. 2470007349dafda47296177fd7481aff9764d4179f42Devang Patel if (TurnSwitchRangeIntoICmp(SI, Builder)) 247156442dfdcf7b07c04b585de5205b9427b1739895Benjamin Kramer return SimplifyCFG(BB) | true; 247210fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer 247310fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer // Remove unreachable cases. 247410fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer if (EliminateDeadSwitchCases(SI)) 247510fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer return SimplifyCFG(BB) | true; 247610fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer 24773d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner return false; 24783d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner} 24793d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 24803d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattnerbool SimplifyCFGOpt::SimplifyIndirectBr(IndirectBrInst *IBI) { 24813d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BasicBlock *BB = IBI->getParent(); 24823d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner bool Changed = false; 24833d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 24843d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // Eliminate redundant destinations. 24853d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner SmallPtrSet<Value *, 8> Succs; 24863d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner for (unsigned i = 0, e = IBI->getNumDestinations(); i != e; ++i) { 24873d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BasicBlock *Dest = IBI->getDestination(i); 24883d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (!Dest->hasAddressTaken() || !Succs.insert(Dest)) { 24893d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner Dest->removePredecessor(BB); 24903d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner IBI->removeDestination(i); 24913d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner --i; --e; 2492698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner Changed = true; 2493698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner } 24943d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } 2495698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner 24963d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (IBI->getNumDestinations() == 0) { 24973d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // If the indirectbr has no successors, change it to unreachable. 24983d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner new UnreachableInst(IBI->getContext(), IBI); 24993d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner EraseTerminatorInstAndDCECond(IBI); 25003d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner return true; 25013d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } 25023d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 25033d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (IBI->getNumDestinations() == 1) { 25043d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // If the indirectbr has one successor, change it to a direct branch. 25053d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BranchInst::Create(IBI->getDestination(0), IBI); 25063d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner EraseTerminatorInstAndDCECond(IBI); 25073d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner return true; 25083d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } 25093d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 25103d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (SelectInst *SI = dyn_cast<SelectInst>(IBI->getAddress())) { 25113d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (SimplifyIndirectBrOnSelect(IBI, SI)) 25123d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner return SimplifyCFG(BB) | true; 25133d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } 25143d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner return Changed; 25153d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner} 2516698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner 2517a23812cfbd23604d2fc103cf232cde8fa270a491Devang Patelbool SimplifyCFGOpt::SimplifyUncondBranch(BranchInst *BI, IRBuilder<> &Builder){ 25183d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BasicBlock *BB = BI->getParent(); 25193d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 25203d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // If the Terminator is the only non-phi instruction, simplify the block. 25213d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BasicBlock::iterator I = BB->getFirstNonPHIOrDbg(); 25223d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (I->isTerminator() && BB != &BB->getParent()->getEntryBlock() && 25233d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner TryToSimplifyUncondBranchFromEmptyBlock(BB)) 25243d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner return true; 25253d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 25263d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // If the only instruction in the block is a seteq/setne comparison 25273d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // against a constant, try to simplify the block. 25283d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (ICmpInst *ICI = dyn_cast<ICmpInst>(I)) 25293d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (ICI->isEquality() && isa<ConstantInt>(ICI->getOperand(1))) { 25303d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner for (++I; isa<DbgInfoIntrinsic>(I); ++I) 25313d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner ; 2532a23812cfbd23604d2fc103cf232cde8fa270a491Devang Patel if (I->isTerminator() 2533a23812cfbd23604d2fc103cf232cde8fa270a491Devang Patel && TryToSimplifyUncondBranchWithICmpInIt(ICI, TD, Builder)) 2534698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner return true; 2535698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner } 25363d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 25373d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner return false; 25383d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner} 2539e2c6d131d12c779a410740e0a90545def75e0f48Dan Gohman 25403d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 2541007349dafda47296177fd7481aff9764d4179f42Devang Patelbool SimplifyCFGOpt::SimplifyCondBranch(BranchInst *BI, IRBuilder<> &Builder) { 25423d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BasicBlock *BB = BI->getParent(); 25433d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 25443d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // Conditional branch 25453d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (isValueEqualityComparison(BI)) { 25463d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // If we only have one predecessor, and if it is a branch on this value, 25473d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // see if that predecessor totally determines the outcome of this 25483d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // switch. 25493d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (BasicBlock *OnlyPred = BB->getSinglePredecessor()) 2550007349dafda47296177fd7481aff9764d4179f42Devang Patel if (SimplifyEqualityComparisonWithOnlyPredecessor(BI, OnlyPred, Builder)) 25513d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner return SimplifyCFG(BB) | true; 25523d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 25533d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // This block must be empty, except for the setcond inst, if it exists. 25543d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // Ignore dbg intrinsics. 25553d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BasicBlock::iterator I = BB->begin(); 25563d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // Ignore dbg intrinsics. 25573d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner while (isa<DbgInfoIntrinsic>(I)) 25583d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner ++I; 25593d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (&*I == BI) { 25603d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (FoldValueComparisonIntoPredecessors(BI)) 25613d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner return SimplifyCFG(BB) | true; 25623d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } else if (&*I == cast<Instruction>(BI->getCondition())){ 25633d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner ++I; 25643d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // Ignore dbg intrinsics. 25653d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner while (isa<DbgInfoIntrinsic>(I)) 25663d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner ++I; 25673d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (&*I == BI && FoldValueComparisonIntoPredecessors(BI)) 25683d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner return SimplifyCFG(BB) | true; 25693d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } 25703d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } 25713d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 25723d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // Try to turn "br (X == 0 | X == 1), T, F" into a switch instruction. 25733d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (SimplifyBranchOnICmpChain(BI, TD)) 25743d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner return true; 25753d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 25763d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // We have a conditional branch to two blocks that are only reachable 25773d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // from BI. We know that the condbr dominates the two blocks, so see if 25783d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // there is any identical code in the "then" and "else" blocks. If so, we 25793d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // can hoist it up to the branching block. 25803d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (BI->getSuccessor(0)->getSinglePredecessor() != 0) { 25813d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (BI->getSuccessor(1)->getSinglePredecessor() != 0) { 25823d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (HoistThenElseCodeToIf(BI)) 25837ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel return SimplifyCFG(BB) | true; 25843d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } else { 25853d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // If Successor #1 has multiple preds, we may be able to conditionally 25863d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // execute Successor #0 if it branches to successor #1. 25873d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner TerminatorInst *Succ0TI = BI->getSuccessor(0)->getTerminator(); 25883d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (Succ0TI->getNumSuccessors() == 1 && 25893d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner Succ0TI->getSuccessor(0) == BI->getSuccessor(1)) 25903d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (SpeculativelyExecuteBB(BI, BI->getSuccessor(0))) 25913d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner return SimplifyCFG(BB) | true; 2592e2c6d131d12c779a410740e0a90545def75e0f48Dan Gohman } 25933d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } else if (BI->getSuccessor(1)->getSinglePredecessor() != 0) { 25943d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // If Successor #0 has multiple preds, we may be able to conditionally 25953d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // execute Successor #1 if it branches to successor #0. 25963d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner TerminatorInst *Succ1TI = BI->getSuccessor(1)->getTerminator(); 25973d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (Succ1TI->getNumSuccessors() == 1 && 25983d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner Succ1TI->getSuccessor(0) == BI->getSuccessor(0)) 25993d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (SpeculativelyExecuteBB(BI, BI->getSuccessor(1))) 26003d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner return SimplifyCFG(BB) | true; 260119831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner } 26023d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 26033d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // If this is a branch on a phi node in the current block, thread control 26043d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // through this block if any PHI node entries are constants. 26053d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (PHINode *PN = dyn_cast<PHINode>(BI->getCondition())) 26063d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (PN->getParent() == BI->getParent()) 2607302ba6fc1cb26248b0d6524fc42c740370926d6dChris Lattner if (FoldCondBranchOnPHI(BI, TD)) 26083d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner return SimplifyCFG(BB) | true; 26093d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 26103d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // If this basic block is ONLY a setcc and a branch, and if a predecessor 26113d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // branches to us and one of our successors, fold the setcc into the 26123d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // predecessor and use logical operations to pick the right destination. 26133d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (FoldBranchToCommonDest(BI)) 26142d9220e8f5b45390d64e943fa4eef1562b87f04bOwen Anderson return SimplifyCFG(BB) | true; 26153d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 26163d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // Scan predecessor blocks for conditional branches. 26173d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI) 26183d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (BranchInst *PBI = dyn_cast<BranchInst>((*PI)->getTerminator())) 26193d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (PBI != BI && PBI->isConditional()) 26203d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (SimplifyCondBranchToCondBranch(PBI, BI)) 26213d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner return SimplifyCFG(BB) | true; 26223d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 26233d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner return false; 26243d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner} 26253d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 26263d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattnerbool SimplifyCFGOpt::run(BasicBlock *BB) { 26273d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner bool Changed = false; 26283d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 2629302ba6fc1cb26248b0d6524fc42c740370926d6dChris Lattner assert(BB && BB->getParent() && "Block not embedded in function!"); 26303d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner assert(BB->getTerminator() && "Degenerate basic block encountered!"); 26313d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 26323d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // Remove basic blocks that have no predecessors (except the entry block)... 26333d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // or that just have themself as a predecessor. These are unreachable. 2634302ba6fc1cb26248b0d6524fc42c740370926d6dChris Lattner if ((pred_begin(BB) == pred_end(BB) && 2635302ba6fc1cb26248b0d6524fc42c740370926d6dChris Lattner BB != &BB->getParent()->getEntryBlock()) || 26363d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BB->getSinglePredecessor() == BB) { 26373d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner DEBUG(dbgs() << "Removing BB: \n" << *BB); 26383d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner DeleteDeadBlock(BB); 26393d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner return true; 26403d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } 26413d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 26423d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // Check to see if we can constant propagate this terminator instruction 26433d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // away... 26443d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner Changed |= ConstantFoldTerminator(BB); 26453d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 26463d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // Check for and eliminate duplicate PHI nodes in this block. 26473d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner Changed |= EliminateDuplicatePHINodes(BB); 26483d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 26493d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // Merge basic blocks into their predecessor if there is only one distinct 26503d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // pred, and if there is only one distinct successor of the predecessor, and 26513d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // if there are no PHI nodes. 26523d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // 26533d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (MergeBlockIntoPredecessor(BB)) 26543d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner return true; 26553d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 26563e410c6607192bbf28ba3708245cb70a0f983556Devang Patel IRBuilder<> Builder(BB); 26573e410c6607192bbf28ba3708245cb70a0f983556Devang Patel 26583d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // If there is a trivial two-entry PHI node in this basic block, and we can 26593d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // eliminate it, do so now. 26603d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (PHINode *PN = dyn_cast<PHINode>(BB->begin())) 26613d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (PN->getNumIncomingValues() == 2) 2662f60364de44add5c92841425851cda1a6943bfcd7Devang Patel Changed |= FoldTwoEntryPHINode(PN, TD, Builder); 26633d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 2664007349dafda47296177fd7481aff9764d4179f42Devang Patel Builder.SetInsertPoint(BB->getTerminator()); 26653d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (BranchInst *BI = dyn_cast<BranchInst>(BB->getTerminator())) { 2666021c9d3bd41bc446ef0860c05a073e32afa5e20fChris Lattner if (BI->isUnconditional()) { 2667a23812cfbd23604d2fc103cf232cde8fa270a491Devang Patel if (SimplifyUncondBranch(BI, Builder)) return true; 2668021c9d3bd41bc446ef0860c05a073e32afa5e20fChris Lattner } else { 2669007349dafda47296177fd7481aff9764d4179f42Devang Patel if (SimplifyCondBranch(BI, Builder)) return true; 2670021c9d3bd41bc446ef0860c05a073e32afa5e20fChris Lattner } 2671021c9d3bd41bc446ef0860c05a073e32afa5e20fChris Lattner } else if (ReturnInst *RI = dyn_cast<ReturnInst>(BB->getTerminator())) { 2672021c9d3bd41bc446ef0860c05a073e32afa5e20fChris Lattner if (SimplifyReturn(RI)) return true; 2673021c9d3bd41bc446ef0860c05a073e32afa5e20fChris Lattner } else if (SwitchInst *SI = dyn_cast<SwitchInst>(BB->getTerminator())) { 2674007349dafda47296177fd7481aff9764d4179f42Devang Patel if (SimplifySwitch(SI, Builder)) return true; 2675021c9d3bd41bc446ef0860c05a073e32afa5e20fChris Lattner } else if (UnreachableInst *UI = 2676021c9d3bd41bc446ef0860c05a073e32afa5e20fChris Lattner dyn_cast<UnreachableInst>(BB->getTerminator())) { 2677021c9d3bd41bc446ef0860c05a073e32afa5e20fChris Lattner if (SimplifyUnreachable(UI)) return true; 2678021c9d3bd41bc446ef0860c05a073e32afa5e20fChris Lattner } else if (UnwindInst *UI = dyn_cast<UnwindInst>(BB->getTerminator())) { 2679d46ba26a6b513086ad575e5db0069b03d41fca13Devang Patel if (SimplifyUnwind(UI, Builder)) return true; 2680021c9d3bd41bc446ef0860c05a073e32afa5e20fChris Lattner } else if (IndirectBrInst *IBI = 2681021c9d3bd41bc446ef0860c05a073e32afa5e20fChris Lattner dyn_cast<IndirectBrInst>(BB->getTerminator())) { 2682021c9d3bd41bc446ef0860c05a073e32afa5e20fChris Lattner if (SimplifyIndirectBr(IBI)) return true; 26833d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } 26843d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 2685694e37f08a7c09ccc24642532106295cf7b3a1e3Chris Lattner return Changed; 268601d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner} 268758e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen 268858e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen/// SimplifyCFG - This function is used to do simplification of a CFG. For 268958e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen/// example, it adjusts branches to branches to eliminate the extra hop, it 269058e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen/// eliminates unreachable basic blocks, and does other "peephole" optimization 269158e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen/// of the CFG. It returns true if a modification was made. 269258e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen/// 269358e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesenbool llvm::SimplifyCFG(BasicBlock *BB, const TargetData *TD) { 269458e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen return SimplifyCFGOpt(TD).run(BB); 269558e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen} 2696