SimplifyCFG.cpp revision f0426601977c3e386d2d26c72a2cca691dc42072
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" 36d3a1788da15311781f661c1cbfe48cd5f98ae778Devang Patel#include "llvm/Support/NoFolder.h" 37302ba6fc1cb26248b0d6524fc42c740370926d6dChris Lattner#include "llvm/Support/raw_ostream.h" 3801d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner#include <algorithm> 39d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner#include <set> 40698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner#include <map> 41f7703df4968084c18c248c1feea9961c19a32e6aChris Lattnerusing namespace llvm; 42d0fde30ce850b78371fd1386338350591f9ff494Brian Gaeke 4357808b3da00d7abd01382d3ed5e70bfb0b2beb4bPeter Collingbournestatic cl::opt<unsigned> 4457808b3da00d7abd01382d3ed5e70bfb0b2beb4bPeter CollingbournePHINodeFoldingThreshold("phi-node-folding-threshold", cl::Hidden, cl::init(1), 4557808b3da00d7abd01382d3ed5e70bfb0b2beb4bPeter Collingbourne cl::desc("Control the amount of phi node folding to perform (default = 1)")); 4657808b3da00d7abd01382d3ed5e70bfb0b2beb4bPeter Collingbourne 47c3f507f98a0747bd256e1c13536060b6fc5c4b62Evan Chengstatic cl::opt<bool> 48c3f507f98a0747bd256e1c13536060b6fc5c4b62Evan ChengDupRet("simplifycfg-dup-ret", cl::Hidden, cl::init(false), 49c3f507f98a0747bd256e1c13536060b6fc5c4b62Evan Cheng cl::desc("Duplicate return instructions into unconditional branches")); 50c3f507f98a0747bd256e1c13536060b6fc5c4b62Evan Cheng 51502a4f5162498ec420e3cb22f667808d726dd7daEvan ChengSTATISTIC(NumSpeculations, "Number of speculative executed instructions"); 52502a4f5162498ec420e3cb22f667808d726dd7daEvan Cheng 5358e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesennamespace { 5458e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesenclass SimplifyCFGOpt { 5558e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen const TargetData *const TD; 5658e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen 5758e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen Value *isValueEqualityComparison(TerminatorInst *TI); 5858e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen BasicBlock *GetValueEqualityComparisonCases(TerminatorInst *TI, 5958e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen std::vector<std::pair<ConstantInt*, BasicBlock*> > &Cases); 6058e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen bool SimplifyEqualityComparisonWithOnlyPredecessor(TerminatorInst *TI, 61007349dafda47296177fd7481aff9764d4179f42Devang Patel BasicBlock *Pred, 62007349dafda47296177fd7481aff9764d4179f42Devang Patel IRBuilder<> &Builder); 63b55d924b1e33341d08b1bead78e86fce56617784Devang Patel bool FoldValueComparisonIntoPredecessors(TerminatorInst *TI, 64b55d924b1e33341d08b1bead78e86fce56617784Devang Patel IRBuilder<> &Builder); 6558e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen 66ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands bool SimplifyResume(ResumeInst *RI, IRBuilder<> &Builder); 67176ec40cb18c51c14fccbb38ee0db5deafb6baa9Devang Patel bool SimplifyReturn(ReturnInst *RI, IRBuilder<> &Builder); 68d46ba26a6b513086ad575e5db0069b03d41fca13Devang Patel bool SimplifyUnwind(UnwindInst *UI, IRBuilder<> &Builder); 693d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner bool SimplifyUnreachable(UnreachableInst *UI); 70007349dafda47296177fd7481aff9764d4179f42Devang Patel bool SimplifySwitch(SwitchInst *SI, IRBuilder<> &Builder); 713d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner bool SimplifyIndirectBr(IndirectBrInst *IBI); 72a23812cfbd23604d2fc103cf232cde8fa270a491Devang Patel bool SimplifyUncondBranch(BranchInst *BI, IRBuilder <> &Builder); 73007349dafda47296177fd7481aff9764d4179f42Devang Patel bool SimplifyCondBranch(BranchInst *BI, IRBuilder <>&Builder); 743d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 7558e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesenpublic: 7658e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen explicit SimplifyCFGOpt(const TargetData *td) : TD(td) {} 7758e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen bool run(BasicBlock *BB); 7858e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen}; 7958e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen} 8058e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen 812bdcb56146279009f233933a101cb3dd54a951cdChris Lattner/// SafeToMergeTerminators - Return true if it is safe to merge these two 822bdcb56146279009f233933a101cb3dd54a951cdChris Lattner/// terminator instructions together. 832bdcb56146279009f233933a101cb3dd54a951cdChris Lattner/// 842bdcb56146279009f233933a101cb3dd54a951cdChris Lattnerstatic bool SafeToMergeTerminators(TerminatorInst *SI1, TerminatorInst *SI2) { 852bdcb56146279009f233933a101cb3dd54a951cdChris Lattner if (SI1 == SI2) return false; // Can't merge with self! 862bdcb56146279009f233933a101cb3dd54a951cdChris Lattner 872bdcb56146279009f233933a101cb3dd54a951cdChris Lattner // It is not safe to merge these two switch instructions if they have a common 882bdcb56146279009f233933a101cb3dd54a951cdChris Lattner // successor, and if that successor has a PHI node, and if *that* PHI node has 892bdcb56146279009f233933a101cb3dd54a951cdChris Lattner // conflicting incoming values from the two switch blocks. 902bdcb56146279009f233933a101cb3dd54a951cdChris Lattner BasicBlock *SI1BB = SI1->getParent(); 912bdcb56146279009f233933a101cb3dd54a951cdChris Lattner BasicBlock *SI2BB = SI2->getParent(); 92c9951231822215d6aea7a9b50947c18d8d745609Chris Lattner SmallPtrSet<BasicBlock*, 16> SI1Succs(succ_begin(SI1BB), succ_end(SI1BB)); 932bdcb56146279009f233933a101cb3dd54a951cdChris Lattner 942bdcb56146279009f233933a101cb3dd54a951cdChris Lattner for (succ_iterator I = succ_begin(SI2BB), E = succ_end(SI2BB); I != E; ++I) 952bdcb56146279009f233933a101cb3dd54a951cdChris Lattner if (SI1Succs.count(*I)) 962bdcb56146279009f233933a101cb3dd54a951cdChris Lattner for (BasicBlock::iterator BBI = (*I)->begin(); 972bdcb56146279009f233933a101cb3dd54a951cdChris Lattner isa<PHINode>(BBI); ++BBI) { 982bdcb56146279009f233933a101cb3dd54a951cdChris Lattner PHINode *PN = cast<PHINode>(BBI); 992bdcb56146279009f233933a101cb3dd54a951cdChris Lattner if (PN->getIncomingValueForBlock(SI1BB) != 1002bdcb56146279009f233933a101cb3dd54a951cdChris Lattner PN->getIncomingValueForBlock(SI2BB)) 1012bdcb56146279009f233933a101cb3dd54a951cdChris Lattner return false; 1022bdcb56146279009f233933a101cb3dd54a951cdChris Lattner } 1032bdcb56146279009f233933a101cb3dd54a951cdChris Lattner 1042bdcb56146279009f233933a101cb3dd54a951cdChris Lattner return true; 1052bdcb56146279009f233933a101cb3dd54a951cdChris Lattner} 1062bdcb56146279009f233933a101cb3dd54a951cdChris Lattner 1072bdcb56146279009f233933a101cb3dd54a951cdChris Lattner/// AddPredecessorToBlock - Update PHI nodes in Succ to indicate that there will 1082bdcb56146279009f233933a101cb3dd54a951cdChris Lattner/// now be entries in it from the 'NewPred' block. The values that will be 1092bdcb56146279009f233933a101cb3dd54a951cdChris Lattner/// flowing into the PHI nodes will be the same as those coming in from 1102bdcb56146279009f233933a101cb3dd54a951cdChris Lattner/// ExistPred, an existing predecessor of Succ. 1112bdcb56146279009f233933a101cb3dd54a951cdChris Lattnerstatic void AddPredecessorToBlock(BasicBlock *Succ, BasicBlock *NewPred, 1122bdcb56146279009f233933a101cb3dd54a951cdChris Lattner BasicBlock *ExistPred) { 1132bdcb56146279009f233933a101cb3dd54a951cdChris Lattner if (!isa<PHINode>(Succ->begin())) return; // Quick exit if nothing to do 1142bdcb56146279009f233933a101cb3dd54a951cdChris Lattner 115093a4385027235459ab6972b2e2fdc79061773cfChris Lattner PHINode *PN; 116093a4385027235459ab6972b2e2fdc79061773cfChris Lattner for (BasicBlock::iterator I = Succ->begin(); 117093a4385027235459ab6972b2e2fdc79061773cfChris Lattner (PN = dyn_cast<PHINode>(I)); ++I) 118093a4385027235459ab6972b2e2fdc79061773cfChris Lattner PN->addIncoming(PN->getIncomingValueForBlock(ExistPred), NewPred); 1192bdcb56146279009f233933a101cb3dd54a951cdChris Lattner} 1202bdcb56146279009f233933a101cb3dd54a951cdChris Lattner 1217e66348cba4384d07b37ad1c186e67ba6d26babdChris Lattner 12273c50a68a7e26b59db54df86e9cc87eed5034bf4Chris Lattner/// GetIfCondition - Given a basic block (BB) with two predecessors (and at 12373c50a68a7e26b59db54df86e9cc87eed5034bf4Chris Lattner/// least one PHI node in it), check to see if the merge at this block is due 124723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner/// to an "if condition". If so, return the boolean condition that determines 125723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner/// which entry into BB will be taken. Also, return by references the block 126723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner/// that will be entered from if the condition is true, and the block that will 127723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner/// be entered if the condition is false. 128fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukman/// 129995ba1bd49e57dee8e301d5f33a7c01d73b7385dChris Lattner/// This does no checking to see if the true/false blocks have large or unsavory 130995ba1bd49e57dee8e301d5f33a7c01d73b7385dChris Lattner/// instructions in them. 13173c50a68a7e26b59db54df86e9cc87eed5034bf4Chris Lattnerstatic Value *GetIfCondition(BasicBlock *BB, BasicBlock *&IfTrue, 13273c50a68a7e26b59db54df86e9cc87eed5034bf4Chris Lattner BasicBlock *&IfFalse) { 13373c50a68a7e26b59db54df86e9cc87eed5034bf4Chris Lattner PHINode *SomePHI = cast<PHINode>(BB->begin()); 13473c50a68a7e26b59db54df86e9cc87eed5034bf4Chris Lattner assert(SomePHI->getNumIncomingValues() == 2 && 135723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner "Function can only handle blocks with 2 predecessors!"); 13673c50a68a7e26b59db54df86e9cc87eed5034bf4Chris Lattner BasicBlock *Pred1 = SomePHI->getIncomingBlock(0); 13773c50a68a7e26b59db54df86e9cc87eed5034bf4Chris Lattner BasicBlock *Pred2 = SomePHI->getIncomingBlock(1); 138723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner 139723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // We can only handle branches. Other control flow will be lowered to 140723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // branches if possible anyway. 141995ba1bd49e57dee8e301d5f33a7c01d73b7385dChris Lattner BranchInst *Pred1Br = dyn_cast<BranchInst>(Pred1->getTerminator()); 142995ba1bd49e57dee8e301d5f33a7c01d73b7385dChris Lattner BranchInst *Pred2Br = dyn_cast<BranchInst>(Pred2->getTerminator()); 143995ba1bd49e57dee8e301d5f33a7c01d73b7385dChris Lattner if (Pred1Br == 0 || Pred2Br == 0) 144723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner return 0; 145723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner 146723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // Eliminate code duplication by ensuring that Pred1Br is conditional if 147723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // either are. 148723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner if (Pred2Br->isConditional()) { 149723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // If both branches are conditional, we don't have an "if statement". In 150723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // reality, we could transform this case, but since the condition will be 151723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // required anyway, we stand no chance of eliminating it, so the xform is 152723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // probably not profitable. 153723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner if (Pred1Br->isConditional()) 154723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner return 0; 155723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner 156723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner std::swap(Pred1, Pred2); 157723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner std::swap(Pred1Br, Pred2Br); 158723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner } 159723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner 160723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner if (Pred1Br->isConditional()) { 161995ba1bd49e57dee8e301d5f33a7c01d73b7385dChris Lattner // The only thing we have to watch out for here is to make sure that Pred2 162995ba1bd49e57dee8e301d5f33a7c01d73b7385dChris Lattner // doesn't have incoming edges from other blocks. If it does, the condition 163995ba1bd49e57dee8e301d5f33a7c01d73b7385dChris Lattner // doesn't dominate BB. 164995ba1bd49e57dee8e301d5f33a7c01d73b7385dChris Lattner if (Pred2->getSinglePredecessor() == 0) 165995ba1bd49e57dee8e301d5f33a7c01d73b7385dChris Lattner return 0; 166995ba1bd49e57dee8e301d5f33a7c01d73b7385dChris Lattner 167723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // If we found a conditional branch predecessor, make sure that it branches 168723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // to BB and Pred2Br. If it doesn't, this isn't an "if statement". 169723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner if (Pred1Br->getSuccessor(0) == BB && 170723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner Pred1Br->getSuccessor(1) == Pred2) { 171723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner IfTrue = Pred1; 172723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner IfFalse = Pred2; 173723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner } else if (Pred1Br->getSuccessor(0) == Pred2 && 174723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner Pred1Br->getSuccessor(1) == BB) { 175723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner IfTrue = Pred2; 176723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner IfFalse = Pred1; 177723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner } else { 178723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // We know that one arm of the conditional goes to BB, so the other must 179723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // go somewhere unrelated, and this must not be an "if statement". 180723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner return 0; 181723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner } 182723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner 183723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner return Pred1Br->getCondition(); 184723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner } 185723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner 186723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // Ok, if we got here, both predecessors end with an unconditional branch to 187723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // BB. Don't panic! If both blocks only have a single (identical) 188723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // predecessor, and THAT is a conditional branch, then we're all ok! 189995ba1bd49e57dee8e301d5f33a7c01d73b7385dChris Lattner BasicBlock *CommonPred = Pred1->getSinglePredecessor(); 190995ba1bd49e57dee8e301d5f33a7c01d73b7385dChris Lattner if (CommonPred == 0 || CommonPred != Pred2->getSinglePredecessor()) 191723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner return 0; 192723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner 193723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // Otherwise, if this is a conditional branch, then we can use it! 194995ba1bd49e57dee8e301d5f33a7c01d73b7385dChris Lattner BranchInst *BI = dyn_cast<BranchInst>(CommonPred->getTerminator()); 195995ba1bd49e57dee8e301d5f33a7c01d73b7385dChris Lattner if (BI == 0) return 0; 196995ba1bd49e57dee8e301d5f33a7c01d73b7385dChris Lattner 197995ba1bd49e57dee8e301d5f33a7c01d73b7385dChris Lattner assert(BI->isConditional() && "Two successors but not conditional?"); 198995ba1bd49e57dee8e301d5f33a7c01d73b7385dChris Lattner if (BI->getSuccessor(0) == Pred1) { 199995ba1bd49e57dee8e301d5f33a7c01d73b7385dChris Lattner IfTrue = Pred1; 200995ba1bd49e57dee8e301d5f33a7c01d73b7385dChris Lattner IfFalse = Pred2; 201995ba1bd49e57dee8e301d5f33a7c01d73b7385dChris Lattner } else { 202995ba1bd49e57dee8e301d5f33a7c01d73b7385dChris Lattner IfTrue = Pred2; 203995ba1bd49e57dee8e301d5f33a7c01d73b7385dChris Lattner IfFalse = Pred1; 204723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner } 205995ba1bd49e57dee8e301d5f33a7c01d73b7385dChris Lattner return BI->getCondition(); 206723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner} 207723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner 2085049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// DominatesMergePoint - If we have a merge point of an "if condition" as 2095049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// accepted above, return true if the specified value dominates the block. We 2105049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// don't handle the true generality of domination here, just a special case 2115049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// which works well enough for us. 2125049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// 2135049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// If AggressiveInsts is non-null, and if V does not dominate BB, we check to 214f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne/// see if V (which must be an instruction) and its recursive operands 215f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne/// that do not dominate BB have a combined cost lower than CostRemaining and 216f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne/// are non-trapping. If both are true, the instruction is inserted into the 217f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne/// set and true is returned. 218f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne/// 219f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne/// The cost for most non-trapping instructions is defined as 1 except for 220f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne/// Select whose cost is 2. 221f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne/// 222f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne/// After this function returns, CostRemaining is decreased by the cost of 223f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne/// V plus its non-dominating operands. If that cost is greater than 224f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne/// CostRemaining, false is returned and CostRemaining is undefined. 2259c07866ef861e072395306e9811c329c7fe5bbe8Chris Lattnerstatic bool DominatesMergePoint(Value *V, BasicBlock *BB, 226f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne SmallPtrSet<Instruction*, 4> *AggressiveInsts, 227f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne unsigned &CostRemaining) { 228570751c2a7d8851bc61e408746a903b0253d2d21Chris Lattner Instruction *I = dyn_cast<Instruction>(V); 229b74b1816305affe25da32c2f29532df41a23cd55Chris Lattner if (!I) { 230b74b1816305affe25da32c2f29532df41a23cd55Chris Lattner // Non-instructions all dominate instructions, but not all constantexprs 231b74b1816305affe25da32c2f29532df41a23cd55Chris Lattner // can be executed unconditionally. 232b74b1816305affe25da32c2f29532df41a23cd55Chris Lattner if (ConstantExpr *C = dyn_cast<ConstantExpr>(V)) 233b74b1816305affe25da32c2f29532df41a23cd55Chris Lattner if (C->canTrap()) 234b74b1816305affe25da32c2f29532df41a23cd55Chris Lattner return false; 235b74b1816305affe25da32c2f29532df41a23cd55Chris Lattner return true; 236b74b1816305affe25da32c2f29532df41a23cd55Chris Lattner } 237570751c2a7d8851bc61e408746a903b0253d2d21Chris Lattner BasicBlock *PBB = I->getParent(); 238570751c2a7d8851bc61e408746a903b0253d2d21Chris Lattner 239da895d63377b421dc50117befb2bec80d2973526Chris Lattner // We don't want to allow weird loops that might have the "if condition" in 240570751c2a7d8851bc61e408746a903b0253d2d21Chris Lattner // the bottom of this block. 241570751c2a7d8851bc61e408746a903b0253d2d21Chris Lattner if (PBB == BB) return false; 242570751c2a7d8851bc61e408746a903b0253d2d21Chris Lattner 243570751c2a7d8851bc61e408746a903b0253d2d21Chris Lattner // If this instruction is defined in a block that contains an unconditional 244570751c2a7d8851bc61e408746a903b0253d2d21Chris Lattner // branch to BB, then it must be in the 'conditional' part of the "if 24544da7ca4213333bcade57a407a890970351db494Chris Lattner // statement". If not, it definitely dominates the region. 24644da7ca4213333bcade57a407a890970351db494Chris Lattner BranchInst *BI = dyn_cast<BranchInst>(PBB->getTerminator()); 24744da7ca4213333bcade57a407a890970351db494Chris Lattner if (BI == 0 || BI->isConditional() || BI->getSuccessor(0) != BB) 24844da7ca4213333bcade57a407a890970351db494Chris Lattner return true; 2490b79a7727d68a507837e827803859424cf3d997bEli Friedman 25044da7ca4213333bcade57a407a890970351db494Chris Lattner // If we aren't allowing aggressive promotion anymore, then don't consider 25144da7ca4213333bcade57a407a890970351db494Chris Lattner // instructions in the 'if region'. 25244da7ca4213333bcade57a407a890970351db494Chris Lattner if (AggressiveInsts == 0) return false; 25344da7ca4213333bcade57a407a890970351db494Chris Lattner 254f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne // If we have seen this instruction before, don't count it again. 255f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne if (AggressiveInsts->count(I)) return true; 256f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne 25744da7ca4213333bcade57a407a890970351db494Chris Lattner // Okay, it looks like the instruction IS in the "condition". Check to 25844da7ca4213333bcade57a407a890970351db494Chris Lattner // see if it's a cheap instruction to unconditionally compute, and if it 25944da7ca4213333bcade57a407a890970351db494Chris Lattner // only uses stuff defined outside of the condition. If so, hoist it out. 260f0426601977c3e386d2d26c72a2cca691dc42072Dan Gohman if (!isSafeToSpeculativelyExecute(I)) 26144da7ca4213333bcade57a407a890970351db494Chris Lattner return false; 262fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukman 263f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne unsigned Cost = 0; 264f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne 26544da7ca4213333bcade57a407a890970351db494Chris Lattner switch (I->getOpcode()) { 26644da7ca4213333bcade57a407a890970351db494Chris Lattner default: return false; // Cannot hoist this out safely. 26744da7ca4213333bcade57a407a890970351db494Chris Lattner case Instruction::Load: 26844da7ca4213333bcade57a407a890970351db494Chris Lattner // We have to check to make sure there are no instructions before the 26944da7ca4213333bcade57a407a890970351db494Chris Lattner // load in its basic block, as we are going to hoist the load out to its 27044da7ca4213333bcade57a407a890970351db494Chris Lattner // predecessor. 27144da7ca4213333bcade57a407a890970351db494Chris Lattner if (PBB->getFirstNonPHIOrDbg() != I) 27244da7ca4213333bcade57a407a890970351db494Chris Lattner return false; 273f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne Cost = 1; 27444da7ca4213333bcade57a407a890970351db494Chris Lattner break; 275278be783b5068e6f87f16bc9b69a77e0bc958f9fBenjamin Kramer case Instruction::GetElementPtr: 276278be783b5068e6f87f16bc9b69a77e0bc958f9fBenjamin Kramer // GEPs are cheap if all indices are constant. 277278be783b5068e6f87f16bc9b69a77e0bc958f9fBenjamin Kramer if (!cast<GetElementPtrInst>(I)->hasAllConstantIndices()) 2789b61c550c2f1fa889163a338f5d6c02b50fe961cBenjamin Kramer return false; 279f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne Cost = 1; 2809b61c550c2f1fa889163a338f5d6c02b50fe961cBenjamin Kramer break; 28144da7ca4213333bcade57a407a890970351db494Chris Lattner case Instruction::Add: 28244da7ca4213333bcade57a407a890970351db494Chris Lattner case Instruction::Sub: 28344da7ca4213333bcade57a407a890970351db494Chris Lattner case Instruction::And: 28444da7ca4213333bcade57a407a890970351db494Chris Lattner case Instruction::Or: 28544da7ca4213333bcade57a407a890970351db494Chris Lattner case Instruction::Xor: 28644da7ca4213333bcade57a407a890970351db494Chris Lattner case Instruction::Shl: 28744da7ca4213333bcade57a407a890970351db494Chris Lattner case Instruction::LShr: 28844da7ca4213333bcade57a407a890970351db494Chris Lattner case Instruction::AShr: 28944da7ca4213333bcade57a407a890970351db494Chris Lattner case Instruction::ICmp: 2908a70192b510e2a0f05493b9212e998017f3d178dPeter Collingbourne case Instruction::Trunc: 2918a70192b510e2a0f05493b9212e998017f3d178dPeter Collingbourne case Instruction::ZExt: 2928a70192b510e2a0f05493b9212e998017f3d178dPeter Collingbourne case Instruction::SExt: 293f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne Cost = 1; 29444da7ca4213333bcade57a407a890970351db494Chris Lattner break; // These are all cheap and non-trapping instructions. 295f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne 296f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne case Instruction::Select: 297f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne Cost = 2; 298f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne break; 29944da7ca4213333bcade57a407a890970351db494Chris Lattner } 300723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner 301f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne if (Cost > CostRemaining) 302f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne return false; 303f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne 304f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne CostRemaining -= Cost; 305f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne 306f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne // Okay, we can only really hoist these out if their operands do 307f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne // not take us over the cost threshold. 30844da7ca4213333bcade57a407a890970351db494Chris Lattner for (User::op_iterator i = I->op_begin(), e = I->op_end(); i != e; ++i) 309f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne if (!DominatesMergePoint(*i, BB, AggressiveInsts, CostRemaining)) 31044da7ca4213333bcade57a407a890970351db494Chris Lattner return false; 31144da7ca4213333bcade57a407a890970351db494Chris Lattner // Okay, it's safe to do this! Remember this instruction. 31244da7ca4213333bcade57a407a890970351db494Chris Lattner AggressiveInsts->insert(I); 313723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner return true; 314723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner} 31501d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner 31658e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen/// GetConstantInt - Extract ConstantInt from value, looking through IntToPtr 31758e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen/// and PointerNullValue. Return NULL if value is not a constant int. 31828acc135481691771205dea7cb4edbd3927aa764Chris Lattnerstatic ConstantInt *GetConstantInt(Value *V, const TargetData *TD) { 31958e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen // Normal constant int. 32058e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen ConstantInt *CI = dyn_cast<ConstantInt>(V); 3211df9859c40492511b8aa4321eb76496005d3b75bDuncan Sands if (CI || !TD || !isa<Constant>(V) || !V->getType()->isPointerTy()) 32258e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen return CI; 32358e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen 32458e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen // This is some kind of pointer constant. Turn it into a pointer-sized 32558e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen // ConstantInt if possible. 326db125cfaf57cc83e7dd7453de2d509bc8efd0e5eChris Lattner IntegerType *PtrTy = TD->getIntPtrType(V->getContext()); 32758e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen 32858e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen // Null pointer means 0, see SelectionDAGBuilder::getValue(const Value*). 32958e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen if (isa<ConstantPointerNull>(V)) 33058e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen return ConstantInt::get(PtrTy, 0); 33158e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen 33258e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen // IntToPtr const int. 33358e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) 33458e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen if (CE->getOpcode() == Instruction::IntToPtr) 33558e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen if (ConstantInt *CI = dyn_cast<ConstantInt>(CE->getOperand(0))) { 33658e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen // The constant is very likely to have the right type already. 33758e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen if (CI->getType() == PtrTy) 33858e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen return CI; 33958e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen else 34058e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen return cast<ConstantInt> 34158e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen (ConstantExpr::getIntegerCast(CI, PtrTy, /*isSigned=*/false)); 34258e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen } 34358e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen return 0; 34458e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen} 34558e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen 3460aa749bde7c696e0522df5581ea9cc70f25e62cbChris Lattner/// GatherConstantCompares - Given a potentially 'or'd or 'and'd together 3470aa749bde7c696e0522df5581ea9cc70f25e62cbChris Lattner/// collection of icmp eq/ne instructions that compare a value against a 3480aa749bde7c696e0522df5581ea9cc70f25e62cbChris Lattner/// constant, return the value being compared, and stick the constant into the 3490aa749bde7c696e0522df5581ea9cc70f25e62cbChris Lattner/// Values vector. 35028acc135481691771205dea7cb4edbd3927aa764Chris Lattnerstatic Value * 3510aa749bde7c696e0522df5581ea9cc70f25e62cbChris LattnerGatherConstantCompares(Value *V, std::vector<ConstantInt*> &Vals, Value *&Extra, 35233828bcb24176aae72afac0e4953e4b7f9560ef1Benjamin Kramer const TargetData *TD, bool isEQ, unsigned &UsedICmps) { 3530aa749bde7c696e0522df5581ea9cc70f25e62cbChris Lattner Instruction *I = dyn_cast<Instruction>(V); 3540aa749bde7c696e0522df5581ea9cc70f25e62cbChris Lattner if (I == 0) return 0; 3559a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner 3567312a22ed63607e4ae7b0d9326e42358fd41e245Chris Lattner // If this is an icmp against a constant, handle this as one of the cases. 3570aa749bde7c696e0522df5581ea9cc70f25e62cbChris Lattner if (ICmpInst *ICI = dyn_cast<ICmpInst>(I)) { 358e27db74a60c44d2b5d2700ecde11b1adce0d0d59Chris Lattner if (ConstantInt *C = GetConstantInt(I->getOperand(1), TD)) { 359e27db74a60c44d2b5d2700ecde11b1adce0d0d59Chris Lattner if (ICI->getPredicate() == (isEQ ? ICmpInst::ICMP_EQ:ICmpInst::ICMP_NE)) { 36033828bcb24176aae72afac0e4953e4b7f9560ef1Benjamin Kramer UsedICmps++; 3610aa749bde7c696e0522df5581ea9cc70f25e62cbChris Lattner Vals.push_back(C); 3620aa749bde7c696e0522df5581ea9cc70f25e62cbChris Lattner return I->getOperand(0); 3630aa749bde7c696e0522df5581ea9cc70f25e62cbChris Lattner } 364e27db74a60c44d2b5d2700ecde11b1adce0d0d59Chris Lattner 365e27db74a60c44d2b5d2700ecde11b1adce0d0d59Chris Lattner // If we have "x ult 3" comparison, for example, then we can add 0,1,2 to 366e27db74a60c44d2b5d2700ecde11b1adce0d0d59Chris Lattner // the set. 367e27db74a60c44d2b5d2700ecde11b1adce0d0d59Chris Lattner ConstantRange Span = 368a37029cd24105f645a694abbafbc9bf1212708b0Chris Lattner ConstantRange::makeICmpRegion(ICI->getPredicate(), C->getValue()); 369e27db74a60c44d2b5d2700ecde11b1adce0d0d59Chris Lattner 370e27db74a60c44d2b5d2700ecde11b1adce0d0d59Chris Lattner // If this is an and/!= check then we want to optimize "x ugt 2" into 371e27db74a60c44d2b5d2700ecde11b1adce0d0d59Chris Lattner // x != 0 && x != 1. 372e27db74a60c44d2b5d2700ecde11b1adce0d0d59Chris Lattner if (!isEQ) 373e27db74a60c44d2b5d2700ecde11b1adce0d0d59Chris Lattner Span = Span.inverse(); 374e27db74a60c44d2b5d2700ecde11b1adce0d0d59Chris Lattner 375e27db74a60c44d2b5d2700ecde11b1adce0d0d59Chris Lattner // If there are a ton of values, we don't want to make a ginormous switch. 37614c0987bd9ab50ebb8728e62a0b29d8f7f951984Benjamin Kramer if (Span.getSetSize().ugt(8) || Span.isEmptySet() || 377e27db74a60c44d2b5d2700ecde11b1adce0d0d59Chris Lattner // We don't handle wrapped sets yet. 378e27db74a60c44d2b5d2700ecde11b1adce0d0d59Chris Lattner Span.isWrappedSet()) 379e27db74a60c44d2b5d2700ecde11b1adce0d0d59Chris Lattner return 0; 380e27db74a60c44d2b5d2700ecde11b1adce0d0d59Chris Lattner 381e27db74a60c44d2b5d2700ecde11b1adce0d0d59Chris Lattner for (APInt Tmp = Span.getLower(); Tmp != Span.getUpper(); ++Tmp) 382e27db74a60c44d2b5d2700ecde11b1adce0d0d59Chris Lattner Vals.push_back(ConstantInt::get(V->getContext(), Tmp)); 38333828bcb24176aae72afac0e4953e4b7f9560ef1Benjamin Kramer UsedICmps++; 384e27db74a60c44d2b5d2700ecde11b1adce0d0d59Chris Lattner return I->getOperand(0); 385e27db74a60c44d2b5d2700ecde11b1adce0d0d59Chris Lattner } 386662269d2abb2f220c3a9b727c2a948246128cd05Chris Lattner return 0; 387662269d2abb2f220c3a9b727c2a948246128cd05Chris Lattner } 388662269d2abb2f220c3a9b727c2a948246128cd05Chris Lattner 3897312a22ed63607e4ae7b0d9326e42358fd41e245Chris Lattner // Otherwise, we can only handle an | or &, depending on isEQ. 3900aa749bde7c696e0522df5581ea9cc70f25e62cbChris Lattner if (I->getOpcode() != (isEQ ? Instruction::Or : Instruction::And)) 391662269d2abb2f220c3a9b727c2a948246128cd05Chris Lattner return 0; 392662269d2abb2f220c3a9b727c2a948246128cd05Chris Lattner 3937312a22ed63607e4ae7b0d9326e42358fd41e245Chris Lattner unsigned NumValsBeforeLHS = Vals.size(); 39433828bcb24176aae72afac0e4953e4b7f9560ef1Benjamin Kramer unsigned UsedICmpsBeforeLHS = UsedICmps; 3950aa749bde7c696e0522df5581ea9cc70f25e62cbChris Lattner if (Value *LHS = GatherConstantCompares(I->getOperand(0), Vals, Extra, TD, 39633828bcb24176aae72afac0e4953e4b7f9560ef1Benjamin Kramer isEQ, UsedICmps)) { 3977312a22ed63607e4ae7b0d9326e42358fd41e245Chris Lattner unsigned NumVals = Vals.size(); 39833828bcb24176aae72afac0e4953e4b7f9560ef1Benjamin Kramer unsigned UsedICmpsBeforeRHS = UsedICmps; 3990aa749bde7c696e0522df5581ea9cc70f25e62cbChris Lattner if (Value *RHS = GatherConstantCompares(I->getOperand(1), Vals, Extra, TD, 40033828bcb24176aae72afac0e4953e4b7f9560ef1Benjamin Kramer isEQ, UsedICmps)) { 4010aa749bde7c696e0522df5581ea9cc70f25e62cbChris Lattner if (LHS == RHS) 4020aa749bde7c696e0522df5581ea9cc70f25e62cbChris Lattner return LHS; 40392407e589524d98080f4db943a0e2a3bf18ec8a2Chris Lattner Vals.resize(NumVals); 40433828bcb24176aae72afac0e4953e4b7f9560ef1Benjamin Kramer UsedICmps = UsedICmpsBeforeRHS; 4050aa749bde7c696e0522df5581ea9cc70f25e62cbChris Lattner } 4067312a22ed63607e4ae7b0d9326e42358fd41e245Chris Lattner 4077312a22ed63607e4ae7b0d9326e42358fd41e245Chris Lattner // The RHS of the or/and can't be folded in and we haven't used "Extra" yet, 4087312a22ed63607e4ae7b0d9326e42358fd41e245Chris Lattner // set it and return success. 4097312a22ed63607e4ae7b0d9326e42358fd41e245Chris Lattner if (Extra == 0 || Extra == I->getOperand(1)) { 4107312a22ed63607e4ae7b0d9326e42358fd41e245Chris Lattner Extra = I->getOperand(1); 4117312a22ed63607e4ae7b0d9326e42358fd41e245Chris Lattner return LHS; 4127312a22ed63607e4ae7b0d9326e42358fd41e245Chris Lattner } 4137312a22ed63607e4ae7b0d9326e42358fd41e245Chris Lattner 4147312a22ed63607e4ae7b0d9326e42358fd41e245Chris Lattner Vals.resize(NumValsBeforeLHS); 41533828bcb24176aae72afac0e4953e4b7f9560ef1Benjamin Kramer UsedICmps = UsedICmpsBeforeLHS; 4167312a22ed63607e4ae7b0d9326e42358fd41e245Chris Lattner return 0; 4177312a22ed63607e4ae7b0d9326e42358fd41e245Chris Lattner } 4187312a22ed63607e4ae7b0d9326e42358fd41e245Chris Lattner 4197312a22ed63607e4ae7b0d9326e42358fd41e245Chris Lattner // If the LHS can't be folded in, but Extra is available and RHS can, try to 4207312a22ed63607e4ae7b0d9326e42358fd41e245Chris Lattner // use LHS as Extra. 4217312a22ed63607e4ae7b0d9326e42358fd41e245Chris Lattner if (Extra == 0 || Extra == I->getOperand(0)) { 42292407e589524d98080f4db943a0e2a3bf18ec8a2Chris Lattner Value *OldExtra = Extra; 4237312a22ed63607e4ae7b0d9326e42358fd41e245Chris Lattner Extra = I->getOperand(0); 4247312a22ed63607e4ae7b0d9326e42358fd41e245Chris Lattner if (Value *RHS = GatherConstantCompares(I->getOperand(1), Vals, Extra, TD, 42533828bcb24176aae72afac0e4953e4b7f9560ef1Benjamin Kramer isEQ, UsedICmps)) 4267312a22ed63607e4ae7b0d9326e42358fd41e245Chris Lattner return RHS; 42792407e589524d98080f4db943a0e2a3bf18ec8a2Chris Lattner assert(Vals.size() == NumValsBeforeLHS); 42892407e589524d98080f4db943a0e2a3bf18ec8a2Chris Lattner Extra = OldExtra; 42907e6e56f57e8781a8d7bc601cc9034a3741d84c2Anton Korobeynikov } 4307312a22ed63607e4ae7b0d9326e42358fd41e245Chris Lattner 4310d56008f53587531718ec36af82cc24576580b36Chris Lattner return 0; 4320d56008f53587531718ec36af82cc24576580b36Chris Lattner} 4330aa749bde7c696e0522df5581ea9cc70f25e62cbChris Lattner 434080efb8cea6255b4f1f373d9cb583d6a6302106bEli Friedmanstatic void EraseTerminatorInstAndDCECond(TerminatorInst *TI) { 435080efb8cea6255b4f1f373d9cb583d6a6302106bEli Friedman Instruction* Cond = 0; 436080efb8cea6255b4f1f373d9cb583d6a6302106bEli Friedman if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) { 437080efb8cea6255b4f1f373d9cb583d6a6302106bEli Friedman Cond = dyn_cast<Instruction>(SI->getCondition()); 438080efb8cea6255b4f1f373d9cb583d6a6302106bEli Friedman } else if (BranchInst *BI = dyn_cast<BranchInst>(TI)) { 439080efb8cea6255b4f1f373d9cb583d6a6302106bEli Friedman if (BI->isConditional()) 440080efb8cea6255b4f1f373d9cb583d6a6302106bEli Friedman Cond = dyn_cast<Instruction>(BI->getCondition()); 4417ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel } else if (IndirectBrInst *IBI = dyn_cast<IndirectBrInst>(TI)) { 4427ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel Cond = dyn_cast<Instruction>(IBI->getAddress()); 443080efb8cea6255b4f1f373d9cb583d6a6302106bEli Friedman } 444080efb8cea6255b4f1f373d9cb583d6a6302106bEli Friedman 445080efb8cea6255b4f1f373d9cb583d6a6302106bEli Friedman TI->eraseFromParent(); 446080efb8cea6255b4f1f373d9cb583d6a6302106bEli Friedman if (Cond) RecursivelyDeleteTriviallyDeadInstructions(Cond); 447080efb8cea6255b4f1f373d9cb583d6a6302106bEli Friedman} 448080efb8cea6255b4f1f373d9cb583d6a6302106bEli Friedman 4499fd4955c6ab9a191dec2d5afd4b2027d4b906f2eChris Lattner/// isValueEqualityComparison - Return true if the specified terminator checks 4509fd4955c6ab9a191dec2d5afd4b2027d4b906f2eChris Lattner/// to see if a value is equal to constant integer value. 45158e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund OlesenValue *SimplifyCFGOpt::isValueEqualityComparison(TerminatorInst *TI) { 45258e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen Value *CV = 0; 4534bebf08d152d84970d250feec72fb734cb8a5316Chris Lattner if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) { 4544bebf08d152d84970d250feec72fb734cb8a5316Chris Lattner // Do not permit merging of large switch instructions into their 4554bebf08d152d84970d250feec72fb734cb8a5316Chris Lattner // predecessors unless there is only one predecessor. 45658e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen if (SI->getNumSuccessors()*std::distance(pred_begin(SI->getParent()), 45758e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen pred_end(SI->getParent())) <= 128) 45858e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen CV = SI->getCondition(); 45958e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen } else if (BranchInst *BI = dyn_cast<BranchInst>(TI)) 460542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner if (BI->isConditional() && BI->getCondition()->hasOneUse()) 461e4d87aa2de6e52952dca73716386db09aad5a8fdReid Spencer if (ICmpInst *ICI = dyn_cast<ICmpInst>(BI->getCondition())) 462e4d87aa2de6e52952dca73716386db09aad5a8fdReid Spencer if ((ICI->getPredicate() == ICmpInst::ICMP_EQ || 463e4d87aa2de6e52952dca73716386db09aad5a8fdReid Spencer ICI->getPredicate() == ICmpInst::ICMP_NE) && 46428acc135481691771205dea7cb4edbd3927aa764Chris Lattner GetConstantInt(ICI->getOperand(1), TD)) 46558e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen CV = ICI->getOperand(0); 46658e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen 46758e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen // Unwrap any lossless ptrtoint cast. 46858e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen if (TD && CV && CV->getType() == TD->getIntPtrType(CV->getContext())) 46958e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen if (PtrToIntInst *PTII = dyn_cast<PtrToIntInst>(CV)) 47058e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen CV = PTII->getOperand(0); 47158e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen return CV; 472542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner} 473542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner 4745049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// GetValueEqualityComparisonCases - Given a value comparison instruction, 4755049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// decode all of the 'cases' that it represents and return the 'default' block. 47658e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund OlesenBasicBlock *SimplifyCFGOpt:: 477fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha BrukmanGetValueEqualityComparisonCases(TerminatorInst *TI, 478542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner std::vector<std::pair<ConstantInt*, 479542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner BasicBlock*> > &Cases) { 480542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) { 481542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner Cases.reserve(SI->getNumCases()); 482542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner for (unsigned i = 1, e = SI->getNumCases(); i != e; ++i) 483be54dcc8a9d14592e324d6e6ae1322782e17f09fChris Lattner Cases.push_back(std::make_pair(SI->getCaseValue(i), SI->getSuccessor(i))); 484542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner return SI->getDefaultDest(); 485542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner } 486542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner 487542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner BranchInst *BI = cast<BranchInst>(TI); 488e4d87aa2de6e52952dca73716386db09aad5a8fdReid Spencer ICmpInst *ICI = cast<ICmpInst>(BI->getCondition()); 48928acc135481691771205dea7cb4edbd3927aa764Chris Lattner Cases.push_back(std::make_pair(GetConstantInt(ICI->getOperand(1), TD), 490e4d87aa2de6e52952dca73716386db09aad5a8fdReid Spencer BI->getSuccessor(ICI->getPredicate() == 491e4d87aa2de6e52952dca73716386db09aad5a8fdReid Spencer ICmpInst::ICMP_NE))); 492e4d87aa2de6e52952dca73716386db09aad5a8fdReid Spencer return BI->getSuccessor(ICI->getPredicate() == ICmpInst::ICMP_EQ); 493542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner} 494542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner 495542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner 4965049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// EliminateBlockCases - Given a vector of bb/value pairs, remove any entries 4975049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// in the list that match the specified block. 498fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukmanstatic void EliminateBlockCases(BasicBlock *BB, 499623369ac5669a3667a94a3cbba342dea78845615Chris Lattner std::vector<std::pair<ConstantInt*, BasicBlock*> > &Cases) { 500623369ac5669a3667a94a3cbba342dea78845615Chris Lattner for (unsigned i = 0, e = Cases.size(); i != e; ++i) 501623369ac5669a3667a94a3cbba342dea78845615Chris Lattner if (Cases[i].second == BB) { 502623369ac5669a3667a94a3cbba342dea78845615Chris Lattner Cases.erase(Cases.begin()+i); 503623369ac5669a3667a94a3cbba342dea78845615Chris Lattner --i; --e; 504623369ac5669a3667a94a3cbba342dea78845615Chris Lattner } 505623369ac5669a3667a94a3cbba342dea78845615Chris Lattner} 506623369ac5669a3667a94a3cbba342dea78845615Chris Lattner 5075049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// ValuesOverlap - Return true if there are any keys in C1 that exist in C2 as 5085049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// well. 509623369ac5669a3667a94a3cbba342dea78845615Chris Lattnerstatic bool 510623369ac5669a3667a94a3cbba342dea78845615Chris LattnerValuesOverlap(std::vector<std::pair<ConstantInt*, BasicBlock*> > &C1, 511623369ac5669a3667a94a3cbba342dea78845615Chris Lattner std::vector<std::pair<ConstantInt*, BasicBlock*> > &C2) { 512623369ac5669a3667a94a3cbba342dea78845615Chris Lattner std::vector<std::pair<ConstantInt*, BasicBlock*> > *V1 = &C1, *V2 = &C2; 513623369ac5669a3667a94a3cbba342dea78845615Chris Lattner 514623369ac5669a3667a94a3cbba342dea78845615Chris Lattner // Make V1 be smaller than V2. 515623369ac5669a3667a94a3cbba342dea78845615Chris Lattner if (V1->size() > V2->size()) 516623369ac5669a3667a94a3cbba342dea78845615Chris Lattner std::swap(V1, V2); 517623369ac5669a3667a94a3cbba342dea78845615Chris Lattner 518623369ac5669a3667a94a3cbba342dea78845615Chris Lattner if (V1->size() == 0) return false; 519623369ac5669a3667a94a3cbba342dea78845615Chris Lattner if (V1->size() == 1) { 520623369ac5669a3667a94a3cbba342dea78845615Chris Lattner // Just scan V2. 521623369ac5669a3667a94a3cbba342dea78845615Chris Lattner ConstantInt *TheVal = (*V1)[0].first; 522623369ac5669a3667a94a3cbba342dea78845615Chris Lattner for (unsigned i = 0, e = V2->size(); i != e; ++i) 523623369ac5669a3667a94a3cbba342dea78845615Chris Lattner if (TheVal == (*V2)[i].first) 524623369ac5669a3667a94a3cbba342dea78845615Chris Lattner return true; 525623369ac5669a3667a94a3cbba342dea78845615Chris Lattner } 526623369ac5669a3667a94a3cbba342dea78845615Chris Lattner 527623369ac5669a3667a94a3cbba342dea78845615Chris Lattner // Otherwise, just sort both lists and compare element by element. 528fca20f507ccfd3407511cd1ccb94ab4421388107Chris Lattner array_pod_sort(V1->begin(), V1->end()); 529fca20f507ccfd3407511cd1ccb94ab4421388107Chris Lattner array_pod_sort(V2->begin(), V2->end()); 530623369ac5669a3667a94a3cbba342dea78845615Chris Lattner unsigned i1 = 0, i2 = 0, e1 = V1->size(), e2 = V2->size(); 531623369ac5669a3667a94a3cbba342dea78845615Chris Lattner while (i1 != e1 && i2 != e2) { 532623369ac5669a3667a94a3cbba342dea78845615Chris Lattner if ((*V1)[i1].first == (*V2)[i2].first) 533623369ac5669a3667a94a3cbba342dea78845615Chris Lattner return true; 534623369ac5669a3667a94a3cbba342dea78845615Chris Lattner if ((*V1)[i1].first < (*V2)[i2].first) 535623369ac5669a3667a94a3cbba342dea78845615Chris Lattner ++i1; 536623369ac5669a3667a94a3cbba342dea78845615Chris Lattner else 537623369ac5669a3667a94a3cbba342dea78845615Chris Lattner ++i2; 538623369ac5669a3667a94a3cbba342dea78845615Chris Lattner } 539623369ac5669a3667a94a3cbba342dea78845615Chris Lattner return false; 540623369ac5669a3667a94a3cbba342dea78845615Chris Lattner} 541623369ac5669a3667a94a3cbba342dea78845615Chris Lattner 5425049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// SimplifyEqualityComparisonWithOnlyPredecessor - If TI is known to be a 5435049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// terminator instruction and its block is known to only have a single 5445049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// predecessor block, check to see if that predecessor is also a value 5455049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// comparison with the same value, and if that comparison determines the 5465049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// outcome of this comparison. If so, simplify TI. This does a very limited 5475049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// form of jump threading. 54858e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesenbool SimplifyCFGOpt:: 54958e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund OlesenSimplifyEqualityComparisonWithOnlyPredecessor(TerminatorInst *TI, 550007349dafda47296177fd7481aff9764d4179f42Devang Patel BasicBlock *Pred, 551007349dafda47296177fd7481aff9764d4179f42Devang Patel IRBuilder<> &Builder) { 552623369ac5669a3667a94a3cbba342dea78845615Chris Lattner Value *PredVal = isValueEqualityComparison(Pred->getTerminator()); 553623369ac5669a3667a94a3cbba342dea78845615Chris Lattner if (!PredVal) return false; // Not a value comparison in predecessor. 554623369ac5669a3667a94a3cbba342dea78845615Chris Lattner 555623369ac5669a3667a94a3cbba342dea78845615Chris Lattner Value *ThisVal = isValueEqualityComparison(TI); 556623369ac5669a3667a94a3cbba342dea78845615Chris Lattner assert(ThisVal && "This isn't a value comparison!!"); 557623369ac5669a3667a94a3cbba342dea78845615Chris Lattner if (ThisVal != PredVal) return false; // Different predicates. 558623369ac5669a3667a94a3cbba342dea78845615Chris Lattner 559623369ac5669a3667a94a3cbba342dea78845615Chris Lattner // Find out information about when control will move from Pred to TI's block. 560623369ac5669a3667a94a3cbba342dea78845615Chris Lattner std::vector<std::pair<ConstantInt*, BasicBlock*> > PredCases; 561623369ac5669a3667a94a3cbba342dea78845615Chris Lattner BasicBlock *PredDef = GetValueEqualityComparisonCases(Pred->getTerminator(), 562623369ac5669a3667a94a3cbba342dea78845615Chris Lattner PredCases); 563623369ac5669a3667a94a3cbba342dea78845615Chris Lattner EliminateBlockCases(PredDef, PredCases); // Remove default from cases. 564fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukman 565623369ac5669a3667a94a3cbba342dea78845615Chris Lattner // Find information about how control leaves this block. 566623369ac5669a3667a94a3cbba342dea78845615Chris Lattner std::vector<std::pair<ConstantInt*, BasicBlock*> > ThisCases; 567623369ac5669a3667a94a3cbba342dea78845615Chris Lattner BasicBlock *ThisDef = GetValueEqualityComparisonCases(TI, ThisCases); 568623369ac5669a3667a94a3cbba342dea78845615Chris Lattner EliminateBlockCases(ThisDef, ThisCases); // Remove default from cases. 569623369ac5669a3667a94a3cbba342dea78845615Chris Lattner 570623369ac5669a3667a94a3cbba342dea78845615Chris Lattner // If TI's block is the default block from Pred's comparison, potentially 571623369ac5669a3667a94a3cbba342dea78845615Chris Lattner // simplify TI based on this knowledge. 572623369ac5669a3667a94a3cbba342dea78845615Chris Lattner if (PredDef == TI->getParent()) { 573623369ac5669a3667a94a3cbba342dea78845615Chris Lattner // If we are here, we know that the value is none of those cases listed in 574623369ac5669a3667a94a3cbba342dea78845615Chris Lattner // PredCases. If there are any cases in ThisCases that are in PredCases, we 575623369ac5669a3667a94a3cbba342dea78845615Chris Lattner // can simplify TI. 5769a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (!ValuesOverlap(PredCases, ThisCases)) 5779a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner return false; 5789a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner 5799a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (isa<BranchInst>(TI)) { 5809a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // Okay, one of the successors of this condbr is dead. Convert it to a 5819a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // uncond br. 5829a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner assert(ThisCases.size() == 1 && "Branch can only have one case!"); 5839a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // Insert the new branch. 584007349dafda47296177fd7481aff9764d4179f42Devang Patel Instruction *NI = Builder.CreateBr(ThisDef); 5859a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner (void) NI; 586623369ac5669a3667a94a3cbba342dea78845615Chris Lattner 5879a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // Remove PHI node entries for the dead edge. 5889a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner ThisCases[0].second->removePredecessor(TI->getParent()); 589623369ac5669a3667a94a3cbba342dea78845615Chris Lattner 5909a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner DEBUG(dbgs() << "Threading pred instr: " << *Pred->getTerminator() 5919a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner << "Through successor TI: " << *TI << "Leaving: " << *NI << "\n"); 592623369ac5669a3667a94a3cbba342dea78845615Chris Lattner 5939a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner EraseTerminatorInstAndDCECond(TI); 5949a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner return true; 595623369ac5669a3667a94a3cbba342dea78845615Chris Lattner } 5969a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner 5979a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner SwitchInst *SI = cast<SwitchInst>(TI); 5989a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // Okay, TI has cases that are statically dead, prune them away. 5999a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner SmallPtrSet<Constant*, 16> DeadCases; 600623369ac5669a3667a94a3cbba342dea78845615Chris Lattner for (unsigned i = 0, e = PredCases.size(); i != e; ++i) 6019a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner DeadCases.insert(PredCases[i].first); 6029a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner 6039a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner DEBUG(dbgs() << "Threading pred instr: " << *Pred->getTerminator() 6049a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner << "Through successor TI: " << *TI); 6059a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner 6069a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner for (unsigned i = SI->getNumCases()-1; i != 0; --i) 6079a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (DeadCases.count(SI->getCaseValue(i))) { 6089a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner SI->getSuccessor(i)->removePredecessor(TI->getParent()); 6099a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner SI->removeCase(i); 610623369ac5669a3667a94a3cbba342dea78845615Chris Lattner } 611623369ac5669a3667a94a3cbba342dea78845615Chris Lattner 6129a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner DEBUG(dbgs() << "Leaving: " << *TI << "\n"); 6139a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner return true; 6149a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner } 6159a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner 6169a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // Otherwise, TI's block must correspond to some matched value. Find out 6179a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // which value (or set of values) this is. 6189a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner ConstantInt *TIV = 0; 6199a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner BasicBlock *TIBB = TI->getParent(); 6209a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner for (unsigned i = 0, e = PredCases.size(); i != e; ++i) 6219a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (PredCases[i].second == TIBB) { 6229a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (TIV != 0) 6239a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner return false; // Cannot handle multiple values coming to this block. 6249a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner TIV = PredCases[i].first; 6259a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner } 6269a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner assert(TIV && "No edge from pred to succ?"); 6279a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner 6289a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // Okay, we found the one constant that our value can be if we get into TI's 6299a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // BB. Find out which successor will unconditionally be branched to. 6309a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner BasicBlock *TheRealDest = 0; 6319a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner for (unsigned i = 0, e = ThisCases.size(); i != e; ++i) 6329a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (ThisCases[i].first == TIV) { 6339a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner TheRealDest = ThisCases[i].second; 6349a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner break; 6359a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner } 6369a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner 6379a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // If not handled by any explicit cases, it is handled by the default case. 6389a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (TheRealDest == 0) TheRealDest = ThisDef; 639623369ac5669a3667a94a3cbba342dea78845615Chris Lattner 6409a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // Remove PHI node entries for dead edges. 6419a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner BasicBlock *CheckEdge = TheRealDest; 6429a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner for (succ_iterator SI = succ_begin(TIBB), e = succ_end(TIBB); SI != e; ++SI) 6439a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (*SI != CheckEdge) 6449a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner (*SI)->removePredecessor(TIBB); 6459a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner else 6469a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner CheckEdge = 0; 647623369ac5669a3667a94a3cbba342dea78845615Chris Lattner 6489a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // Insert the new branch. 649007349dafda47296177fd7481aff9764d4179f42Devang Patel Instruction *NI = Builder.CreateBr(TheRealDest); 6509a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner (void) NI; 651623369ac5669a3667a94a3cbba342dea78845615Chris Lattner 6529a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner DEBUG(dbgs() << "Threading pred instr: " << *Pred->getTerminator() 6539a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner << "Through successor TI: " << *TI << "Leaving: " << *NI << "\n"); 654623369ac5669a3667a94a3cbba342dea78845615Chris Lattner 6559a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner EraseTerminatorInstAndDCECond(TI); 6569a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner return true; 657623369ac5669a3667a94a3cbba342dea78845615Chris Lattner} 658623369ac5669a3667a94a3cbba342dea78845615Chris Lattner 659c81f5445a7cbe3ba0252aec030082a40e5019eceDale Johannesennamespace { 660c81f5445a7cbe3ba0252aec030082a40e5019eceDale Johannesen /// ConstantIntOrdering - This class implements a stable ordering of constant 661c81f5445a7cbe3ba0252aec030082a40e5019eceDale Johannesen /// integers that does not depend on their address. This is important for 662c81f5445a7cbe3ba0252aec030082a40e5019eceDale Johannesen /// applications that sort ConstantInt's to ensure uniqueness. 663c81f5445a7cbe3ba0252aec030082a40e5019eceDale Johannesen struct ConstantIntOrdering { 664c81f5445a7cbe3ba0252aec030082a40e5019eceDale Johannesen bool operator()(const ConstantInt *LHS, const ConstantInt *RHS) const { 665c81f5445a7cbe3ba0252aec030082a40e5019eceDale Johannesen return LHS->getValue().ult(RHS->getValue()); 666c81f5445a7cbe3ba0252aec030082a40e5019eceDale Johannesen } 667c81f5445a7cbe3ba0252aec030082a40e5019eceDale Johannesen }; 668c81f5445a7cbe3ba0252aec030082a40e5019eceDale Johannesen} 669a9537cf3fcf9fdaac94749db9fbd34912b1f0f08Dale Johannesen 6706d4d21e29d4840236ab6f15c5247379820021d0cChris Lattnerstatic int ConstantIntSortPredicate(const void *P1, const void *P2) { 6716d4d21e29d4840236ab6f15c5247379820021d0cChris Lattner const ConstantInt *LHS = *(const ConstantInt**)P1; 6726d4d21e29d4840236ab6f15c5247379820021d0cChris Lattner const ConstantInt *RHS = *(const ConstantInt**)P2; 673ba3c8155704e5e2ac24b5069c32bca359b0738edChris Lattner if (LHS->getValue().ult(RHS->getValue())) 674ba3c8155704e5e2ac24b5069c32bca359b0738edChris Lattner return 1; 675ba3c8155704e5e2ac24b5069c32bca359b0738edChris Lattner if (LHS->getValue() == RHS->getValue()) 676ba3c8155704e5e2ac24b5069c32bca359b0738edChris Lattner return 0; 677ba3c8155704e5e2ac24b5069c32bca359b0738edChris Lattner return -1; 6786d4d21e29d4840236ab6f15c5247379820021d0cChris Lattner} 6796d4d21e29d4840236ab6f15c5247379820021d0cChris Lattner 6805049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// FoldValueComparisonIntoPredecessors - The specified terminator is a value 6815049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// equality comparison instruction (either a switch or a branch on "X == c"). 6825049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// See if any of the predecessors of the terminator block are value comparisons 6835049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// on the same value. If so, and if safe to do so, fold them together. 684b55d924b1e33341d08b1bead78e86fce56617784Devang Patelbool SimplifyCFGOpt::FoldValueComparisonIntoPredecessors(TerminatorInst *TI, 685b55d924b1e33341d08b1bead78e86fce56617784Devang Patel IRBuilder<> &Builder) { 686542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner BasicBlock *BB = TI->getParent(); 687542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner Value *CV = isValueEqualityComparison(TI); // CondVal 688542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner assert(CV && "Not a comparison?"); 689542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner bool Changed = false; 690542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner 6918244243a31d636ce8838a81d4c402274fd391d2bChris Lattner SmallVector<BasicBlock*, 16> Preds(pred_begin(BB), pred_end(BB)); 692542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner while (!Preds.empty()) { 693e9d87f49063cb1bd213d8e9c339b9b63393cc2d9Dan Gohman BasicBlock *Pred = Preds.pop_back_val(); 694fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukman 695542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // See if the predecessor is a comparison with the same value. 696542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner TerminatorInst *PTI = Pred->getTerminator(); 697542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner Value *PCV = isValueEqualityComparison(PTI); // PredCondVal 698542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner 699542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner if (PCV == CV && SafeToMergeTerminators(TI, PTI)) { 700542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // Figure out which 'cases' to copy from SI to PSI. 701542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner std::vector<std::pair<ConstantInt*, BasicBlock*> > BBCases; 702542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner BasicBlock *BBDefault = GetValueEqualityComparisonCases(TI, BBCases); 703542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner 704542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner std::vector<std::pair<ConstantInt*, BasicBlock*> > PredCases; 705542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner BasicBlock *PredDefault = GetValueEqualityComparisonCases(PTI, PredCases); 706542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner 707542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // Based on whether the default edge from PTI goes to BB or not, fill in 708542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // PredCases and PredDefault with the new switch cases we would like to 709542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // build. 7108244243a31d636ce8838a81d4c402274fd391d2bChris Lattner SmallVector<BasicBlock*, 8> NewSuccessors; 711542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner 712542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner if (PredDefault == BB) { 713542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // If this is the default destination from PTI, only the edges in TI 714542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // that don't occur in PTI, or that branch to BB will be activated. 715c81f5445a7cbe3ba0252aec030082a40e5019eceDale Johannesen std::set<ConstantInt*, ConstantIntOrdering> PTIHandled; 716542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner for (unsigned i = 0, e = PredCases.size(); i != e; ++i) 717542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner if (PredCases[i].second != BB) 718542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner PTIHandled.insert(PredCases[i].first); 719542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner else { 720542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // The default destination is BB, we don't need explicit targets. 721542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner std::swap(PredCases[i], PredCases.back()); 722542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner PredCases.pop_back(); 723542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner --i; --e; 724542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner } 725542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner 726542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // Reconstruct the new switch statement we will be building. 727542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner if (PredDefault != BBDefault) { 728542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner PredDefault->removePredecessor(Pred); 729542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner PredDefault = BBDefault; 730542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner NewSuccessors.push_back(BBDefault); 731542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner } 732542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner for (unsigned i = 0, e = BBCases.size(); i != e; ++i) 733542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner if (!PTIHandled.count(BBCases[i].first) && 734542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner BBCases[i].second != BBDefault) { 735542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner PredCases.push_back(BBCases[i]); 736542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner NewSuccessors.push_back(BBCases[i].second); 737542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner } 738542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner 739542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner } else { 740542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // If this is not the default destination from PSI, only the edges 741542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // in SI that occur in PSI with a destination of BB will be 742542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // activated. 743c81f5445a7cbe3ba0252aec030082a40e5019eceDale Johannesen std::set<ConstantInt*, ConstantIntOrdering> PTIHandled; 744542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner for (unsigned i = 0, e = PredCases.size(); i != e; ++i) 745542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner if (PredCases[i].second == BB) { 746542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner PTIHandled.insert(PredCases[i].first); 747542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner std::swap(PredCases[i], PredCases.back()); 748542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner PredCases.pop_back(); 749542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner --i; --e; 750542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner } 751542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner 752542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // Okay, now we know which constants were sent to BB from the 753542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // predecessor. Figure out where they will all go now. 754542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner for (unsigned i = 0, e = BBCases.size(); i != e; ++i) 755542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner if (PTIHandled.count(BBCases[i].first)) { 756542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // If this is one we are capable of getting... 757542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner PredCases.push_back(BBCases[i]); 758542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner NewSuccessors.push_back(BBCases[i].second); 759542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner PTIHandled.erase(BBCases[i].first);// This constant is taken care of 760542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner } 761542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner 762542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // If there are any constants vectored to BB that TI doesn't handle, 763542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // they must go to the default destination of TI. 764c81f5445a7cbe3ba0252aec030082a40e5019eceDale Johannesen for (std::set<ConstantInt*, ConstantIntOrdering>::iterator I = 765c81f5445a7cbe3ba0252aec030082a40e5019eceDale Johannesen PTIHandled.begin(), 766542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner E = PTIHandled.end(); I != E; ++I) { 767542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner PredCases.push_back(std::make_pair(*I, BBDefault)); 768542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner NewSuccessors.push_back(BBDefault); 769542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner } 770542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner } 771542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner 772542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // Okay, at this point, we know which new successor Pred will get. Make 773542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // sure we update the number of entries in the PHI nodes for these 774542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // successors. 775542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner for (unsigned i = 0, e = NewSuccessors.size(); i != e; ++i) 776542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner AddPredecessorToBlock(NewSuccessors[i], Pred, BB); 777542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner 778b55d924b1e33341d08b1bead78e86fce56617784Devang Patel Builder.SetInsertPoint(PTI); 77958e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen // Convert pointer to int before we switch. 7801df9859c40492511b8aa4321eb76496005d3b75bDuncan Sands if (CV->getType()->isPointerTy()) { 78158e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen assert(TD && "Cannot switch on pointer without TargetData"); 782b55d924b1e33341d08b1bead78e86fce56617784Devang Patel CV = Builder.CreatePtrToInt(CV, TD->getIntPtrType(CV->getContext()), 783b55d924b1e33341d08b1bead78e86fce56617784Devang Patel "magicptr"); 78458e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen } 78558e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen 786542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // Now that the successors are updated, create the new Switch instruction. 787b55d924b1e33341d08b1bead78e86fce56617784Devang Patel SwitchInst *NewSI = Builder.CreateSwitch(CV, PredDefault, 788b55d924b1e33341d08b1bead78e86fce56617784Devang Patel PredCases.size()); 789d80e8ed2fa20c7ad51af49c3b2650525edbdcd08Devang Patel NewSI->setDebugLoc(PTI->getDebugLoc()); 790542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner for (unsigned i = 0, e = PredCases.size(); i != e; ++i) 791542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner NewSI->addCase(PredCases[i].first, PredCases[i].second); 79213b2f764c041e15af3d6033826deb9c7e669ca97Chris Lattner 793080efb8cea6255b4f1f373d9cb583d6a6302106bEli Friedman EraseTerminatorInstAndDCECond(PTI); 79413b2f764c041e15af3d6033826deb9c7e669ca97Chris Lattner 795542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // Okay, last check. If BB is still a successor of PSI, then we must 796542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // have an infinite loop case. If so, add an infinitely looping block 797542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // to handle the case to preserve the behavior of the code. 798542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner BasicBlock *InfLoopBlock = 0; 799542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner for (unsigned i = 0, e = NewSI->getNumSuccessors(); i != e; ++i) 800542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner if (NewSI->getSuccessor(i) == BB) { 801542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner if (InfLoopBlock == 0) { 802093a4385027235459ab6972b2e2fdc79061773cfChris Lattner // Insert it at the end of the function, because it's either code, 803542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // or it won't matter if it's hot. :) 8041d0be15f89cb5056e20e2d24faa8d6afb1573bcaOwen Anderson InfLoopBlock = BasicBlock::Create(BB->getContext(), 8051d0be15f89cb5056e20e2d24faa8d6afb1573bcaOwen Anderson "infloop", BB->getParent()); 806051a950000e21935165db56695e35bade668193bGabor Greif BranchInst::Create(InfLoopBlock, InfLoopBlock); 807542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner } 808542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner NewSI->setSuccessor(i, InfLoopBlock); 809542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner } 810fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukman 811542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner Changed = true; 812542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner } 813542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner } 814542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner return Changed; 815542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner} 816542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner 817c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen// isSafeToHoistInvoke - If we would need to insert a select that uses the 818c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen// value of this invoke (comments in HoistThenElseCodeToIf explain why we 819c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen// would need to do this), we can't hoist the invoke, as there is nowhere 820c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen// to put the select in this case. 821c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesenstatic bool isSafeToHoistInvoke(BasicBlock *BB1, BasicBlock *BB2, 822c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen Instruction *I1, Instruction *I2) { 823c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen for (succ_iterator SI = succ_begin(BB1), E = succ_end(BB1); SI != E; ++SI) { 824c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen PHINode *PN; 825c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen for (BasicBlock::iterator BBI = SI->begin(); 826c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen (PN = dyn_cast<PHINode>(BBI)); ++BBI) { 827c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen Value *BB1V = PN->getIncomingValueForBlock(BB1); 828c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen Value *BB2V = PN->getIncomingValueForBlock(BB2); 829c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen if (BB1V != BB2V && (BB1V==I1 || BB2V==I2)) { 830c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen return false; 831c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen } 832c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen } 833c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen } 834c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen return true; 835c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen} 836c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen 8376306d07aa8cf71e3c7fed7f295665f53595473ebChris Lattner/// HoistThenElseCodeToIf - Given a conditional branch that goes to BB1 and 83837dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner/// BB2, hoist any common code in the two blocks up into the branch block. The 83937dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner/// caller of this function guarantees that BI's block dominates BB1 and BB2. 840216dde91d1def3e08002d6251e11f3dfa5cb3656Rafael Espindolastatic bool HoistThenElseCodeToIf(BranchInst *BI) { 84137dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner // This does very trivial matching, with limited scanning, to find identical 84237dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner // instructions in the two blocks. In particular, we don't want to get into 84337dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner // O(M*N) situations here where M and N are the sizes of BB1 and BB2. As 84437dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner // such, we currently just scan for obviously identical instructions in an 84537dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner // identical order. 84637dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner BasicBlock *BB1 = BI->getSuccessor(0); // The true destination. 84737dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner BasicBlock *BB2 = BI->getSuccessor(1); // The false destination 84837dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner 84965085cf7b3470b7b087f5fd7b0497879b90b32baDevang Patel BasicBlock::iterator BB1_Itr = BB1->begin(); 85065085cf7b3470b7b087f5fd7b0497879b90b32baDevang Patel BasicBlock::iterator BB2_Itr = BB2->begin(); 85165085cf7b3470b7b087f5fd7b0497879b90b32baDevang Patel 85265085cf7b3470b7b087f5fd7b0497879b90b32baDevang Patel Instruction *I1 = BB1_Itr++, *I2 = BB2_Itr++; 853949666ea16214e1b7e79fc8e653b06ad8b93dd5aDevang Patel // Skip debug info if it is not identical. 854949666ea16214e1b7e79fc8e653b06ad8b93dd5aDevang Patel DbgInfoIntrinsic *DBI1 = dyn_cast<DbgInfoIntrinsic>(I1); 855949666ea16214e1b7e79fc8e653b06ad8b93dd5aDevang Patel DbgInfoIntrinsic *DBI2 = dyn_cast<DbgInfoIntrinsic>(I2); 856949666ea16214e1b7e79fc8e653b06ad8b93dd5aDevang Patel if (!DBI1 || !DBI2 || !DBI1->isIdenticalToWhenDefined(DBI2)) { 857949666ea16214e1b7e79fc8e653b06ad8b93dd5aDevang Patel while (isa<DbgInfoIntrinsic>(I1)) 858949666ea16214e1b7e79fc8e653b06ad8b93dd5aDevang Patel I1 = BB1_Itr++; 859949666ea16214e1b7e79fc8e653b06ad8b93dd5aDevang Patel while (isa<DbgInfoIntrinsic>(I2)) 860949666ea16214e1b7e79fc8e653b06ad8b93dd5aDevang Patel I2 = BB2_Itr++; 861949666ea16214e1b7e79fc8e653b06ad8b93dd5aDevang Patel } 862ae6c95b58e78403707fb75e78f0959a86d57b0c5Devang Patel if (isa<PHINode>(I1) || !I1->isIdenticalToWhenDefined(I2) || 863c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen (isa<InvokeInst>(I1) && !isSafeToHoistInvoke(BB1, BB2, I1, I2))) 86437dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner return false; 86537dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner 86637dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner // If we get here, we can hoist at least one instruction. 86737dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner BasicBlock *BIParent = BI->getParent(); 86837dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner 86937dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner do { 87037dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner // If we are hoisting the terminator instruction, don't move one (making a 87137dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner // broken BB), instead clone it, and remove BI. 87237dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner if (isa<TerminatorInst>(I1)) 87337dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner goto HoistTerminator; 874fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukman 87537dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner // For a normal instruction, we just move one to right before the branch, 87637dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner // then replace all uses of the other with the first. Finally, we remove 87737dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner // the now redundant second instruction. 87837dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner BIParent->getInstList().splice(BI, BB1->getInstList(), I1); 87937dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner if (!I2->use_empty()) 88037dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner I2->replaceAllUsesWith(I1); 88158cfa3b13752579c86cf85270d49f9ced0942f2fDan Gohman I1->intersectOptionalDataWith(I2); 882302ba6fc1cb26248b0d6524fc42c740370926d6dChris Lattner I2->eraseFromParent(); 883fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukman 88465085cf7b3470b7b087f5fd7b0497879b90b32baDevang Patel I1 = BB1_Itr++; 88565085cf7b3470b7b087f5fd7b0497879b90b32baDevang Patel I2 = BB2_Itr++; 886949666ea16214e1b7e79fc8e653b06ad8b93dd5aDevang Patel // Skip debug info if it is not identical. 887949666ea16214e1b7e79fc8e653b06ad8b93dd5aDevang Patel DbgInfoIntrinsic *DBI1 = dyn_cast<DbgInfoIntrinsic>(I1); 888949666ea16214e1b7e79fc8e653b06ad8b93dd5aDevang Patel DbgInfoIntrinsic *DBI2 = dyn_cast<DbgInfoIntrinsic>(I2); 889949666ea16214e1b7e79fc8e653b06ad8b93dd5aDevang Patel if (!DBI1 || !DBI2 || !DBI1->isIdenticalToWhenDefined(DBI2)) { 890949666ea16214e1b7e79fc8e653b06ad8b93dd5aDevang Patel while (isa<DbgInfoIntrinsic>(I1)) 891949666ea16214e1b7e79fc8e653b06ad8b93dd5aDevang Patel I1 = BB1_Itr++; 892949666ea16214e1b7e79fc8e653b06ad8b93dd5aDevang Patel while (isa<DbgInfoIntrinsic>(I2)) 893949666ea16214e1b7e79fc8e653b06ad8b93dd5aDevang Patel I2 = BB2_Itr++; 894949666ea16214e1b7e79fc8e653b06ad8b93dd5aDevang Patel } 895ae6c95b58e78403707fb75e78f0959a86d57b0c5Devang Patel } while (I1->isIdenticalToWhenDefined(I2)); 89637dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner 89737dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner return true; 89837dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner 89937dc938bbe556a9414d063196d367c2f75d07d95Chris LattnerHoistTerminator: 900c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen // It may not be possible to hoist an invoke. 901c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen if (isa<InvokeInst>(I1) && !isSafeToHoistInvoke(BB1, BB2, I1, I2)) 902c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen return true; 903c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen 90437dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner // Okay, it is safe to hoist the terminator. 9056776064d190701c5bae4d5403939eed2e480d1cdNick Lewycky Instruction *NT = I1->clone(); 90637dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner BIParent->getInstList().insert(BI, NT); 907f012705c7e4ca8cf90b6b734ce1d5355daca5ba5Benjamin Kramer if (!NT->getType()->isVoidTy()) { 90837dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner I1->replaceAllUsesWith(NT); 90937dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner I2->replaceAllUsesWith(NT); 91086cc42355593dd1689f7d58d56695c451215b02bChris Lattner NT->takeName(I1); 91137dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner } 91237dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner 913d3a1788da15311781f661c1cbfe48cd5f98ae778Devang Patel IRBuilder<true, NoFolder> Builder(NT); 91437dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner // Hoisting one of the terminators from our successor is a great thing. 91537dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner // Unfortunately, the successors of the if/else blocks may have PHI nodes in 91637dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner // them. If they do, all PHI entries for BB1/BB2 must agree for all PHI 91737dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner // nodes, so we insert select instruction to compute the final result. 91837dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner std::map<std::pair<Value*,Value*>, SelectInst*> InsertedSelects; 91937dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner for (succ_iterator SI = succ_begin(BB1), E = succ_end(BB1); SI != E; ++SI) { 92037dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner PHINode *PN; 92137dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner for (BasicBlock::iterator BBI = SI->begin(); 9220f535c6fa8b03491dc110feb65d78922ee29d1fcChris Lattner (PN = dyn_cast<PHINode>(BBI)); ++BBI) { 92337dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner Value *BB1V = PN->getIncomingValueForBlock(BB1); 92437dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner Value *BB2V = PN->getIncomingValueForBlock(BB2); 9259a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (BB1V == BB2V) continue; 9269a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner 9279a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // These values do not agree. Insert a select instruction before NT 9289a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // that determines the right value. 9299a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner SelectInst *&SI = InsertedSelects[std::make_pair(BB1V, BB2V)]; 930d3a1788da15311781f661c1cbfe48cd5f98ae778Devang Patel if (SI == 0) 931d3a1788da15311781f661c1cbfe48cd5f98ae778Devang Patel SI = cast<SelectInst> 932d3a1788da15311781f661c1cbfe48cd5f98ae778Devang Patel (Builder.CreateSelect(BI->getCondition(), BB1V, BB2V, 933d3a1788da15311781f661c1cbfe48cd5f98ae778Devang Patel BB1V->getName()+"."+BB2V->getName())); 934d3a1788da15311781f661c1cbfe48cd5f98ae778Devang Patel 9359a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // Make the PHI node use the select for all incoming values for BB1/BB2 9369a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) 9379a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (PN->getIncomingBlock(i) == BB1 || PN->getIncomingBlock(i) == BB2) 9389a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner PN->setIncomingValue(i, SI); 93937dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner } 94037dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner } 94137dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner 94237dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner // Update any PHI nodes in our new successors. 94337dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner for (succ_iterator SI = succ_begin(BB1), E = succ_end(BB1); SI != E; ++SI) 94437dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner AddPredecessorToBlock(*SI, BIParent, BB1); 945fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukman 946080efb8cea6255b4f1f373d9cb583d6a6302106bEli Friedman EraseTerminatorInstAndDCECond(BI); 94737dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner return true; 94837dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner} 94937dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner 9504d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng/// SpeculativelyExecuteBB - Given a conditional branch that goes to BB1 9514d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng/// and an BB2 and the only successor of BB1 is BB2, hoist simple code 9524d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng/// (for now, restricted to a single instruction that's side effect free) from 9534d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng/// the BB1 into the branch block to speculatively execute it. 954216dde91d1def3e08002d6251e11f3dfa5cb3656Rafael Espindolastatic bool SpeculativelyExecuteBB(BranchInst *BI, BasicBlock *BB1) { 9554d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // Only speculatively execution a single instruction (not counting the 9564d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // terminator) for now. 95706b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel Instruction *HInst = NULL; 95806b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel Instruction *Term = BB1->getTerminator(); 95906b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel for (BasicBlock::iterator BBI = BB1->begin(), BBE = BB1->end(); 96006b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel BBI != BBE; ++BBI) { 96106b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel Instruction *I = BBI; 96206b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel // Skip debug info. 9639a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (isa<DbgInfoIntrinsic>(I)) continue; 9649a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (I == Term) break; 96506b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel 9669a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (HInst) 96706b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel return false; 9689a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner HInst = I; 96906b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel } 97006b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel if (!HInst) 97106b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel return false; 9724d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng 973797d95188d00963a835db9ad66dd3c4a54aa2fafEvan Cheng // Be conservative for now. FP select instruction can often be expensive. 974797d95188d00963a835db9ad66dd3c4a54aa2fafEvan Cheng Value *BrCond = BI->getCondition(); 9759a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (isa<FCmpInst>(BrCond)) 976797d95188d00963a835db9ad66dd3c4a54aa2fafEvan Cheng return false; 977797d95188d00963a835db9ad66dd3c4a54aa2fafEvan Cheng 9784d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // If BB1 is actually on the false edge of the conditional branch, remember 9794d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // to swap the select operands later. 9804d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng bool Invert = false; 9814d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng if (BB1 != BI->getSuccessor(0)) { 9824d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng assert(BB1 == BI->getSuccessor(1) && "No edge from 'if' block?"); 9834d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng Invert = true; 9844d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng } 9854d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng 9864d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // Turn 9874d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // BB: 9884d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // %t1 = icmp 9894d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // br i1 %t1, label %BB1, label %BB2 9904d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // BB1: 9914d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // %t3 = add %t2, c 9924d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // br label BB2 9934d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // BB2: 9944d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // => 9954d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // BB: 9964d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // %t1 = icmp 9974d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // %t4 = add %t2, c 9984d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // %t3 = select i1 %t1, %t2, %t3 99906b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel switch (HInst->getOpcode()) { 10004d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng default: return false; // Not safe / profitable to hoist. 10014d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng case Instruction::Add: 10024d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng case Instruction::Sub: 1003ae3a0be92e33bc716722aa600983fc1535acb122Dan Gohman // Not worth doing for vector ops. 10041df9859c40492511b8aa4321eb76496005d3b75bDuncan Sands if (HInst->getType()->isVectorTy()) 10059dd3b610dcb17f88ed52ae03022179bf21e0e132Chris Lattner return false; 10069dd3b610dcb17f88ed52ae03022179bf21e0e132Chris Lattner break; 10074d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng case Instruction::And: 10084d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng case Instruction::Or: 10094d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng case Instruction::Xor: 10104d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng case Instruction::Shl: 10114d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng case Instruction::LShr: 10124d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng case Instruction::AShr: 10139dd3b610dcb17f88ed52ae03022179bf21e0e132Chris Lattner // Don't mess with vector operations. 10141df9859c40492511b8aa4321eb76496005d3b75bDuncan Sands if (HInst->getType()->isVectorTy()) 1015e5334ea518e3dffec4037ede97433eb700fa1d26Evan Cheng return false; 10164d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng break; // These are all cheap and non-trapping instructions. 10174d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng } 10186fe73bbcf3b6c1ddfd5e70e8b5188f8df439ace6Chris Lattner 10196fe73bbcf3b6c1ddfd5e70e8b5188f8df439ace6Chris Lattner // If the instruction is obviously dead, don't try to predicate it. 102006b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel if (HInst->use_empty()) { 102106b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel HInst->eraseFromParent(); 10226fe73bbcf3b6c1ddfd5e70e8b5188f8df439ace6Chris Lattner return true; 10236fe73bbcf3b6c1ddfd5e70e8b5188f8df439ace6Chris Lattner } 10244d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng 10254d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // Can we speculatively execute the instruction? And what is the value 10264d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // if the condition is false? Consider the phi uses, if the incoming value 10274d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // from the "if" block are all the same V, then V is the value of the 10284d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // select if the condition is false. 10294d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng BasicBlock *BIParent = BI->getParent(); 10304d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng SmallVector<PHINode*, 4> PHIUses; 10314d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng Value *FalseV = NULL; 10326fe73bbcf3b6c1ddfd5e70e8b5188f8df439ace6Chris Lattner 10336fe73bbcf3b6c1ddfd5e70e8b5188f8df439ace6Chris Lattner BasicBlock *BB2 = BB1->getTerminator()->getSuccessor(0); 103406b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel for (Value::use_iterator UI = HInst->use_begin(), E = HInst->use_end(); 10354d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng UI != E; ++UI) { 10366fe73bbcf3b6c1ddfd5e70e8b5188f8df439ace6Chris Lattner // Ignore any user that is not a PHI node in BB2. These can only occur in 10376fe73bbcf3b6c1ddfd5e70e8b5188f8df439ace6Chris Lattner // unreachable blocks, because they would not be dominated by the instr. 103820361b9d4d9988d7bfa2112650971642cf81d13eGabor Greif PHINode *PN = dyn_cast<PHINode>(*UI); 10396fe73bbcf3b6c1ddfd5e70e8b5188f8df439ace6Chris Lattner if (!PN || PN->getParent() != BB2) 10406fe73bbcf3b6c1ddfd5e70e8b5188f8df439ace6Chris Lattner return false; 10414d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng PHIUses.push_back(PN); 10426fe73bbcf3b6c1ddfd5e70e8b5188f8df439ace6Chris Lattner 10434d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng Value *PHIV = PN->getIncomingValueForBlock(BIParent); 10444d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng if (!FalseV) 10454d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng FalseV = PHIV; 10464d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng else if (FalseV != PHIV) 10476fe73bbcf3b6c1ddfd5e70e8b5188f8df439ace6Chris Lattner return false; // Inconsistent value when condition is false. 10484d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng } 10496fe73bbcf3b6c1ddfd5e70e8b5188f8df439ace6Chris Lattner 10506fe73bbcf3b6c1ddfd5e70e8b5188f8df439ace6Chris Lattner assert(FalseV && "Must have at least one user, and it must be a PHI"); 10514d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng 1052502a4f5162498ec420e3cb22f667808d726dd7daEvan Cheng // Do not hoist the instruction if any of its operands are defined but not 1053502a4f5162498ec420e3cb22f667808d726dd7daEvan Cheng // used in this BB. The transformation will prevent the operand from 1054502a4f5162498ec420e3cb22f667808d726dd7daEvan Cheng // being sunk into the use block. 105506b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel for (User::op_iterator i = HInst->op_begin(), e = HInst->op_end(); 105606b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel i != e; ++i) { 1057502a4f5162498ec420e3cb22f667808d726dd7daEvan Cheng Instruction *OpI = dyn_cast<Instruction>(*i); 1058502a4f5162498ec420e3cb22f667808d726dd7daEvan Cheng if (OpI && OpI->getParent() == BIParent && 1059502a4f5162498ec420e3cb22f667808d726dd7daEvan Cheng !OpI->isUsedInBasicBlock(BIParent)) 1060502a4f5162498ec420e3cb22f667808d726dd7daEvan Cheng return false; 1061502a4f5162498ec420e3cb22f667808d726dd7daEvan Cheng } 1062502a4f5162498ec420e3cb22f667808d726dd7daEvan Cheng 10633d0a9a371c0ce3a46e845a7bf1f1acb7a1cf523eDevang Patel // If we get here, we can hoist the instruction. Try to place it 1064990afedb3a4b7d32832d74ad5b5863c19f909e1fDale Johannesen // before the icmp instruction preceding the conditional branch. 10653d0a9a371c0ce3a46e845a7bf1f1acb7a1cf523eDevang Patel BasicBlock::iterator InsertPos = BI; 1066990afedb3a4b7d32832d74ad5b5863c19f909e1fDale Johannesen if (InsertPos != BIParent->begin()) 1067990afedb3a4b7d32832d74ad5b5863c19f909e1fDale Johannesen --InsertPos; 1068990afedb3a4b7d32832d74ad5b5863c19f909e1fDale Johannesen // Skip debug info between condition and branch. 1069990afedb3a4b7d32832d74ad5b5863c19f909e1fDale Johannesen while (InsertPos != BIParent->begin() && isa<DbgInfoIntrinsic>(InsertPos)) 10703d0a9a371c0ce3a46e845a7bf1f1acb7a1cf523eDevang Patel --InsertPos; 107120da1f07dac4d771e55ee5c7f105ccedfa4caaaaDevang Patel if (InsertPos == BrCond && !isa<PHINode>(BrCond)) { 10723d0a9a371c0ce3a46e845a7bf1f1acb7a1cf523eDevang Patel SmallPtrSet<Instruction *, 4> BB1Insns; 10733d0a9a371c0ce3a46e845a7bf1f1acb7a1cf523eDevang Patel for(BasicBlock::iterator BB1I = BB1->begin(), BB1E = BB1->end(); 10743d0a9a371c0ce3a46e845a7bf1f1acb7a1cf523eDevang Patel BB1I != BB1E; ++BB1I) 10753d0a9a371c0ce3a46e845a7bf1f1acb7a1cf523eDevang Patel BB1Insns.insert(BB1I); 10763d0a9a371c0ce3a46e845a7bf1f1acb7a1cf523eDevang Patel for(Value::use_iterator UI = BrCond->use_begin(), UE = BrCond->use_end(); 10773d0a9a371c0ce3a46e845a7bf1f1acb7a1cf523eDevang Patel UI != UE; ++UI) { 10783d0a9a371c0ce3a46e845a7bf1f1acb7a1cf523eDevang Patel Instruction *Use = cast<Instruction>(*UI); 10799a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (!BB1Insns.count(Use)) continue; 10809a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner 10819a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // If BrCond uses the instruction that place it just before 10829a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // branch instruction. 10839a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner InsertPos = BI; 10849a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner break; 10853d0a9a371c0ce3a46e845a7bf1f1acb7a1cf523eDevang Patel } 10863d0a9a371c0ce3a46e845a7bf1f1acb7a1cf523eDevang Patel } else 10873d0a9a371c0ce3a46e845a7bf1f1acb7a1cf523eDevang Patel InsertPos = BI; 108806b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel BIParent->getInstList().splice(InsertPos, BB1->getInstList(), HInst); 10894d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng 10904d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // Create a select whose true value is the speculatively executed value and 10914d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // false value is the previously determined FalseV. 1092d3a1788da15311781f661c1cbfe48cd5f98ae778Devang Patel IRBuilder<true, NoFolder> Builder(BI); 10934d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng SelectInst *SI; 10944d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng if (Invert) 1095d3a1788da15311781f661c1cbfe48cd5f98ae778Devang Patel SI = cast<SelectInst> 1096d3a1788da15311781f661c1cbfe48cd5f98ae778Devang Patel (Builder.CreateSelect(BrCond, FalseV, HInst, 1097d3a1788da15311781f661c1cbfe48cd5f98ae778Devang Patel FalseV->getName() + "." + HInst->getName())); 10984d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng else 1099d3a1788da15311781f661c1cbfe48cd5f98ae778Devang Patel SI = cast<SelectInst> 1100d3a1788da15311781f661c1cbfe48cd5f98ae778Devang Patel (Builder.CreateSelect(BrCond, HInst, FalseV, 1101d3a1788da15311781f661c1cbfe48cd5f98ae778Devang Patel HInst->getName() + "." + FalseV->getName())); 11024d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng 11034d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // Make the PHI node use the select for all incoming values for "then" and 11044d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // "if" blocks. 11054d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng for (unsigned i = 0, e = PHIUses.size(); i != e; ++i) { 11064d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng PHINode *PN = PHIUses[i]; 11074d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng for (unsigned j = 0, ee = PN->getNumIncomingValues(); j != ee; ++j) 11089a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (PN->getIncomingBlock(j) == BB1 || PN->getIncomingBlock(j) == BIParent) 11094d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng PN->setIncomingValue(j, SI); 11104d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng } 11114d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng 1112502a4f5162498ec420e3cb22f667808d726dd7daEvan Cheng ++NumSpeculations; 11134d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng return true; 11144d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng} 11154d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng 11162e42e36698d5a34f1952ca3389f1973a6a1166f2Chris Lattner/// BlockIsSimpleEnoughToThreadThrough - Return true if we can thread a branch 11172e42e36698d5a34f1952ca3389f1973a6a1166f2Chris Lattner/// across this block. 11182e42e36698d5a34f1952ca3389f1973a6a1166f2Chris Lattnerstatic bool BlockIsSimpleEnoughToThreadThrough(BasicBlock *BB) { 11192e42e36698d5a34f1952ca3389f1973a6a1166f2Chris Lattner BranchInst *BI = cast<BranchInst>(BB->getTerminator()); 1120e9487f0dc8c6d15cb257d5b49fa96ed436d32f5fChris Lattner unsigned Size = 0; 1121e9487f0dc8c6d15cb257d5b49fa96ed436d32f5fChris Lattner 11229200c89968e52a590ee0b96092a0a589aa138a6fDevang Patel for (BasicBlock::iterator BBI = BB->begin(); &*BBI != BI; ++BBI) { 11238483e54837ede5dd40c5561f15c6a663e2bee87cDale Johannesen if (isa<DbgInfoIntrinsic>(BBI)) 11248483e54837ede5dd40c5561f15c6a663e2bee87cDale Johannesen continue; 1125e9487f0dc8c6d15cb257d5b49fa96ed436d32f5fChris Lattner if (Size > 10) return false; // Don't clone large BB's. 11268483e54837ede5dd40c5561f15c6a663e2bee87cDale Johannesen ++Size; 11272e42e36698d5a34f1952ca3389f1973a6a1166f2Chris Lattner 11288483e54837ede5dd40c5561f15c6a663e2bee87cDale Johannesen // We can only support instructions that do not define values that are 1129e9487f0dc8c6d15cb257d5b49fa96ed436d32f5fChris Lattner // live outside of the current basic block. 1130e9487f0dc8c6d15cb257d5b49fa96ed436d32f5fChris Lattner for (Value::use_iterator UI = BBI->use_begin(), E = BBI->use_end(); 1131e9487f0dc8c6d15cb257d5b49fa96ed436d32f5fChris Lattner UI != E; ++UI) { 1132e9487f0dc8c6d15cb257d5b49fa96ed436d32f5fChris Lattner Instruction *U = cast<Instruction>(*UI); 1133e9487f0dc8c6d15cb257d5b49fa96ed436d32f5fChris Lattner if (U->getParent() != BB || isa<PHINode>(U)) return false; 1134e9487f0dc8c6d15cb257d5b49fa96ed436d32f5fChris Lattner } 11352e42e36698d5a34f1952ca3389f1973a6a1166f2Chris Lattner 11362e42e36698d5a34f1952ca3389f1973a6a1166f2Chris Lattner // Looks ok, continue checking. 11372e42e36698d5a34f1952ca3389f1973a6a1166f2Chris Lattner } 1138e9487f0dc8c6d15cb257d5b49fa96ed436d32f5fChris Lattner 11392e42e36698d5a34f1952ca3389f1973a6a1166f2Chris Lattner return true; 11402e42e36698d5a34f1952ca3389f1973a6a1166f2Chris Lattner} 11412e42e36698d5a34f1952ca3389f1973a6a1166f2Chris Lattner 1142eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner/// FoldCondBranchOnPHI - If we have a conditional branch on a PHI node value 1143eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner/// that is defined in the same block as the branch and if any PHI entries are 1144eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner/// constants, thread edges corresponding to that entry to be branches to their 1145eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner/// ultimate destination. 1146302ba6fc1cb26248b0d6524fc42c740370926d6dChris Lattnerstatic bool FoldCondBranchOnPHI(BranchInst *BI, const TargetData *TD) { 1147eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner BasicBlock *BB = BI->getParent(); 1148eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner PHINode *PN = dyn_cast<PHINode>(BI->getCondition()); 11499c88d9816246d260b37cdc689f313c56aec6941eChris Lattner // NOTE: we currently cannot transform this case if the PHI node is used 11509c88d9816246d260b37cdc689f313c56aec6941eChris Lattner // outside of the block. 11512e42e36698d5a34f1952ca3389f1973a6a1166f2Chris Lattner if (!PN || PN->getParent() != BB || !PN->hasOneUse()) 11522e42e36698d5a34f1952ca3389f1973a6a1166f2Chris Lattner return false; 1153eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner 1154eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner // Degenerate case of a single entry PHI. 1155eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner if (PN->getNumIncomingValues() == 1) { 115629874e0dc6c4e55bc384611273343bb358982cc3Chris Lattner FoldSingleEntryPHINodes(PN->getParent()); 1157eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner return true; 1158eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner } 1159eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner 1160eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner // Now we know that this block has multiple preds and two succs. 11612e42e36698d5a34f1952ca3389f1973a6a1166f2Chris Lattner if (!BlockIsSimpleEnoughToThreadThrough(BB)) return false; 1162eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner 1163eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner // Okay, this is a simple enough basic block. See if any phi values are 1164eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner // constants. 11656b6b6ef1677fa71b1072c2911b4c1f9524a558c9Zhou Sheng for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) { 11669a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner ConstantInt *CB = dyn_cast<ConstantInt>(PN->getIncomingValue(i)); 11679a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (CB == 0 || !CB->getType()->isIntegerTy(1)) continue; 11689a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner 11699a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // Okay, we now know that all edges from PredBB should be revectored to 11709a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // branch to RealDest. 11719a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner BasicBlock *PredBB = PN->getIncomingBlock(i); 11729a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner BasicBlock *RealDest = BI->getSuccessor(!CB->getZExtValue()); 11739a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner 11749a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (RealDest == BB) continue; // Skip self loops. 11756a648b8538bb4d4b3e96669ef8cd3a4ce3aedeb8Bill Wendling // Skip if the predecessor's terminator is an indirect branch. 11766a648b8538bb4d4b3e96669ef8cd3a4ce3aedeb8Bill Wendling if (isa<IndirectBrInst>(PredBB->getTerminator())) continue; 11779a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner 11789a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // The dest block might have PHI nodes, other predecessors and other 11799a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // difficult cases. Instead of being smart about this, just insert a new 11809a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // block that jumps to the destination block, effectively splitting 11819a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // the edge we are about to create. 11829a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner BasicBlock *EdgeBB = BasicBlock::Create(BB->getContext(), 11839a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner RealDest->getName()+".critedge", 11849a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner RealDest->getParent(), RealDest); 11859a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner BranchInst::Create(RealDest, EdgeBB); 11866de0a28dfb84095ebd7775f371dd4085cf955076Chris Lattner 11876de0a28dfb84095ebd7775f371dd4085cf955076Chris Lattner // Update PHI nodes. 11886de0a28dfb84095ebd7775f371dd4085cf955076Chris Lattner AddPredecessorToBlock(RealDest, EdgeBB, BB); 11899a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner 11909a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // BB may have instructions that are being threaded over. Clone these 11919a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // instructions into EdgeBB. We know that there will be no uses of the 11929a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // cloned instructions outside of EdgeBB. 11939a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner BasicBlock::iterator InsertPt = EdgeBB->begin(); 11949a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner DenseMap<Value*, Value*> TranslateMap; // Track translated values. 11959a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner for (BasicBlock::iterator BBI = BB->begin(); &*BBI != BI; ++BBI) { 11969a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (PHINode *PN = dyn_cast<PHINode>(BBI)) { 11979a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner TranslateMap[PN] = PN->getIncomingValueForBlock(PredBB); 11989a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner continue; 11999a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner } 12009a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // Clone the instruction. 12019a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner Instruction *N = BBI->clone(); 12029a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (BBI->hasName()) N->setName(BBI->getName()+".c"); 1203eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner 12049a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // Update operands due to translation. 12059a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner for (User::op_iterator i = N->op_begin(), e = N->op_end(); 12069a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner i != e; ++i) { 12079a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner DenseMap<Value*, Value*>::iterator PI = TranslateMap.find(*i); 12089a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (PI != TranslateMap.end()) 12099a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner *i = PI->second; 12109a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner } 1211eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner 12129a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // Check for trivial simplification. 1213302ba6fc1cb26248b0d6524fc42c740370926d6dChris Lattner if (Value *V = SimplifyInstruction(N, TD)) { 1214302ba6fc1cb26248b0d6524fc42c740370926d6dChris Lattner TranslateMap[BBI] = V; 1215302ba6fc1cb26248b0d6524fc42c740370926d6dChris Lattner delete N; // Instruction folded away, don't need actual inst 12169a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner } else { 12179a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // Insert the new instruction into its new home. 12189a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner EdgeBB->getInstList().insert(InsertPt, N); 12199a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (!BBI->use_empty()) 12209a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner TranslateMap[BBI] = N; 1221e9487f0dc8c6d15cb257d5b49fa96ed436d32f5fChris Lattner } 12229a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner } 1223e9487f0dc8c6d15cb257d5b49fa96ed436d32f5fChris Lattner 12249a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // Loop over all of the edges from PredBB to BB, changing them to branch 12259a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // to EdgeBB instead. 12269a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner TerminatorInst *PredBBTI = PredBB->getTerminator(); 12279a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner for (unsigned i = 0, e = PredBBTI->getNumSuccessors(); i != e; ++i) 12289a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (PredBBTI->getSuccessor(i) == BB) { 12299a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner BB->removePredecessor(PredBB); 12309a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner PredBBTI->setSuccessor(i, EdgeBB); 1231e9487f0dc8c6d15cb257d5b49fa96ed436d32f5fChris Lattner } 12326a648b8538bb4d4b3e96669ef8cd3a4ce3aedeb8Bill Wendling 12339a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // Recurse, simplifying any other constants. 1234302ba6fc1cb26248b0d6524fc42c740370926d6dChris Lattner return FoldCondBranchOnPHI(BI, TD) | true; 12356b6b6ef1677fa71b1072c2911b4c1f9524a558c9Zhou Sheng } 1236eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner 1237eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner return false; 1238eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner} 1239eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner 1240f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner/// FoldTwoEntryPHINode - Given a BB that starts with the specified two-entry 1241f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner/// PHI node, see if we can eliminate it. 1242d3a1788da15311781f661c1cbfe48cd5f98ae778Devang Patelstatic bool FoldTwoEntryPHINode(PHINode *PN, const TargetData *TD) { 1243f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // Ok, this is a two entry PHI node. Check to see if this is a simple "if 1244f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // statement", which has a very simple dominance structure. Basically, we 1245f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // are trying to find the condition that is being branched on, which 1246f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // subsequently causes this merge to happen. We really want control 1247f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // dependence information for this check, but simplifycfg can't keep it up 1248f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // to date, and this catches most of the cases we care about anyway. 1249f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner BasicBlock *BB = PN->getParent(); 1250f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner BasicBlock *IfTrue, *IfFalse; 1251f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner Value *IfCond = GetIfCondition(BB, IfTrue, IfFalse); 125260d410d7bb2eb11f36a004237e5948ffc5aff5a6Chris Lattner if (!IfCond || 125360d410d7bb2eb11f36a004237e5948ffc5aff5a6Chris Lattner // Don't bother if the branch will be constant folded trivially. 125460d410d7bb2eb11f36a004237e5948ffc5aff5a6Chris Lattner isa<ConstantInt>(IfCond)) 125560d410d7bb2eb11f36a004237e5948ffc5aff5a6Chris Lattner return false; 1256f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner 1257822a87998387a4c52be5162523f09cc8e5e5afb7Chris Lattner // Okay, we found that we can merge this two-entry phi node into a select. 1258822a87998387a4c52be5162523f09cc8e5e5afb7Chris Lattner // Doing so would require us to fold *all* two entry phi nodes in this block. 1259822a87998387a4c52be5162523f09cc8e5e5afb7Chris Lattner // At some point this becomes non-profitable (particularly if the target 1260822a87998387a4c52be5162523f09cc8e5e5afb7Chris Lattner // doesn't support cmov's). Only do this transformation if there are two or 1261822a87998387a4c52be5162523f09cc8e5e5afb7Chris Lattner // fewer PHI nodes in this block. 1262822a87998387a4c52be5162523f09cc8e5e5afb7Chris Lattner unsigned NumPhis = 0; 1263822a87998387a4c52be5162523f09cc8e5e5afb7Chris Lattner for (BasicBlock::iterator I = BB->begin(); isa<PHINode>(I); ++NumPhis, ++I) 1264822a87998387a4c52be5162523f09cc8e5e5afb7Chris Lattner if (NumPhis > 2) 1265822a87998387a4c52be5162523f09cc8e5e5afb7Chris Lattner return false; 1266822a87998387a4c52be5162523f09cc8e5e5afb7Chris Lattner 1267f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // Loop over the PHI's seeing if we can promote them all to select 1268f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // instructions. While we are at it, keep track of the instructions 1269f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // that need to be moved to the dominating block. 127044da7ca4213333bcade57a407a890970351db494Chris Lattner SmallPtrSet<Instruction*, 4> AggressiveInsts; 127157808b3da00d7abd01382d3ed5e70bfb0b2beb4bPeter Collingbourne unsigned MaxCostVal0 = PHINodeFoldingThreshold, 127257808b3da00d7abd01382d3ed5e70bfb0b2beb4bPeter Collingbourne MaxCostVal1 = PHINodeFoldingThreshold; 1273f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner 12743aff13b82a579e910420b6c040f3e85c99110e15Chris Lattner for (BasicBlock::iterator II = BB->begin(); isa<PHINode>(II);) { 12753aff13b82a579e910420b6c040f3e85c99110e15Chris Lattner PHINode *PN = cast<PHINode>(II++); 127607ff3539f5342bdac019c68bb362cb222b3f71d9Chris Lattner if (Value *V = SimplifyInstruction(PN, TD)) { 127707ff3539f5342bdac019c68bb362cb222b3f71d9Chris Lattner PN->replaceAllUsesWith(V); 12783aff13b82a579e910420b6c040f3e85c99110e15Chris Lattner PN->eraseFromParent(); 127907ff3539f5342bdac019c68bb362cb222b3f71d9Chris Lattner continue; 1280f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner } 128107ff3539f5342bdac019c68bb362cb222b3f71d9Chris Lattner 1282f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne if (!DominatesMergePoint(PN->getIncomingValue(0), BB, &AggressiveInsts, 1283f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne MaxCostVal0) || 1284f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne !DominatesMergePoint(PN->getIncomingValue(1), BB, &AggressiveInsts, 1285f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne MaxCostVal1)) 128607ff3539f5342bdac019c68bb362cb222b3f71d9Chris Lattner return false; 1287f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner } 1288f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner 128944da7ca4213333bcade57a407a890970351db494Chris Lattner // If we folded the the first phi, PN dangles at this point. Refresh it. If 129044da7ca4213333bcade57a407a890970351db494Chris Lattner // we ran out of PHIs then we simplified them all. 129144da7ca4213333bcade57a407a890970351db494Chris Lattner PN = dyn_cast<PHINode>(BB->begin()); 129244da7ca4213333bcade57a407a890970351db494Chris Lattner if (PN == 0) return true; 129344da7ca4213333bcade57a407a890970351db494Chris Lattner 12943aff13b82a579e910420b6c040f3e85c99110e15Chris Lattner // Don't fold i1 branches on PHIs which contain binary operators. These can 12953aff13b82a579e910420b6c040f3e85c99110e15Chris Lattner // often be turned into switches and other things. 12963aff13b82a579e910420b6c040f3e85c99110e15Chris Lattner if (PN->getType()->isIntegerTy(1) && 12973aff13b82a579e910420b6c040f3e85c99110e15Chris Lattner (isa<BinaryOperator>(PN->getIncomingValue(0)) || 12983aff13b82a579e910420b6c040f3e85c99110e15Chris Lattner isa<BinaryOperator>(PN->getIncomingValue(1)) || 12993aff13b82a579e910420b6c040f3e85c99110e15Chris Lattner isa<BinaryOperator>(IfCond))) 13003aff13b82a579e910420b6c040f3e85c99110e15Chris Lattner return false; 13013aff13b82a579e910420b6c040f3e85c99110e15Chris Lattner 1302f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // If we all PHI nodes are promotable, check to make sure that all 1303f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // instructions in the predecessor blocks can be promoted as well. If 1304f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // not, we won't be able to get rid of the control flow, so it's not 1305f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // worth promoting to select instructions. 130644da7ca4213333bcade57a407a890970351db494Chris Lattner BasicBlock *DomBlock = 0; 130744da7ca4213333bcade57a407a890970351db494Chris Lattner BasicBlock *IfBlock1 = PN->getIncomingBlock(0); 130844da7ca4213333bcade57a407a890970351db494Chris Lattner BasicBlock *IfBlock2 = PN->getIncomingBlock(1); 130944da7ca4213333bcade57a407a890970351db494Chris Lattner if (cast<BranchInst>(IfBlock1->getTerminator())->isConditional()) { 131044da7ca4213333bcade57a407a890970351db494Chris Lattner IfBlock1 = 0; 131144da7ca4213333bcade57a407a890970351db494Chris Lattner } else { 131244da7ca4213333bcade57a407a890970351db494Chris Lattner DomBlock = *pred_begin(IfBlock1); 131344da7ca4213333bcade57a407a890970351db494Chris Lattner for (BasicBlock::iterator I = IfBlock1->begin();!isa<TerminatorInst>(I);++I) 1314383d7ed9158576aef5cde872548225a17e3c0155Devang Patel if (!AggressiveInsts.count(I) && !isa<DbgInfoIntrinsic>(I)) { 1315f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // This is not an aggressive instruction that we can promote. 1316f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // Because of this, we won't be able to get rid of the control 1317f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // flow, so the xform is not worth it. 1318f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner return false; 1319f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner } 1320f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner } 1321f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner 132244da7ca4213333bcade57a407a890970351db494Chris Lattner if (cast<BranchInst>(IfBlock2->getTerminator())->isConditional()) { 132344da7ca4213333bcade57a407a890970351db494Chris Lattner IfBlock2 = 0; 132444da7ca4213333bcade57a407a890970351db494Chris Lattner } else { 132544da7ca4213333bcade57a407a890970351db494Chris Lattner DomBlock = *pred_begin(IfBlock2); 132644da7ca4213333bcade57a407a890970351db494Chris Lattner for (BasicBlock::iterator I = IfBlock2->begin();!isa<TerminatorInst>(I);++I) 1327383d7ed9158576aef5cde872548225a17e3c0155Devang Patel if (!AggressiveInsts.count(I) && !isa<DbgInfoIntrinsic>(I)) { 1328f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // This is not an aggressive instruction that we can promote. 1329f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // Because of this, we won't be able to get rid of the control 1330f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // flow, so the xform is not worth it. 1331f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner return false; 1332f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner } 1333f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner } 1334e0b18e59120abc29bd25d69d20c4b0f310ec3382Chris Lattner 1335e0b18e59120abc29bd25d69d20c4b0f310ec3382Chris Lattner DEBUG(dbgs() << "FOUND IF CONDITION! " << *IfCond << " T: " 133644da7ca4213333bcade57a407a890970351db494Chris Lattner << IfTrue->getName() << " F: " << IfFalse->getName() << "\n"); 1337f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner 1338f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // If we can still promote the PHI nodes after this gauntlet of tests, 1339f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // do all of the PHI's now. 13403aff13b82a579e910420b6c040f3e85c99110e15Chris Lattner Instruction *InsertPt = DomBlock->getTerminator(); 1341d3a1788da15311781f661c1cbfe48cd5f98ae778Devang Patel IRBuilder<true, NoFolder> Builder(InsertPt); 13423aff13b82a579e910420b6c040f3e85c99110e15Chris Lattner 1343f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // Move all 'aggressive' instructions, which are defined in the 1344f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // conditional parts of the if's up to the dominating block. 13459a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (IfBlock1) 13463aff13b82a579e910420b6c040f3e85c99110e15Chris Lattner DomBlock->getInstList().splice(InsertPt, 13479a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner IfBlock1->getInstList(), IfBlock1->begin(), 1348f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner IfBlock1->getTerminator()); 13499a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (IfBlock2) 13503aff13b82a579e910420b6c040f3e85c99110e15Chris Lattner DomBlock->getInstList().splice(InsertPt, 13519a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner IfBlock2->getInstList(), IfBlock2->begin(), 1352f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner IfBlock2->getTerminator()); 1353f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner 1354f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner while (PHINode *PN = dyn_cast<PHINode>(BB->begin())) { 1355f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // Change the PHI node into a select instruction. 13569a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner Value *TrueVal = PN->getIncomingValue(PN->getIncomingBlock(0) == IfFalse); 13579a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner Value *FalseVal = PN->getIncomingValue(PN->getIncomingBlock(0) == IfTrue); 1358f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner 1359f60364de44add5c92841425851cda1a6943bfcd7Devang Patel SelectInst *NV = 1360f60364de44add5c92841425851cda1a6943bfcd7Devang Patel cast<SelectInst>(Builder.CreateSelect(IfCond, TrueVal, FalseVal, "")); 136186cc42355593dd1689f7d58d56695c451215b02bChris Lattner PN->replaceAllUsesWith(NV); 136286cc42355593dd1689f7d58d56695c451215b02bChris Lattner NV->takeName(PN); 1363302ba6fc1cb26248b0d6524fc42c740370926d6dChris Lattner PN->eraseFromParent(); 1364f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner } 136560d410d7bb2eb11f36a004237e5948ffc5aff5a6Chris Lattner 136660d410d7bb2eb11f36a004237e5948ffc5aff5a6Chris Lattner // At this point, IfBlock1 and IfBlock2 are both empty, so our if statement 136760d410d7bb2eb11f36a004237e5948ffc5aff5a6Chris Lattner // has been flattened. Change DomBlock to jump directly to our new block to 136860d410d7bb2eb11f36a004237e5948ffc5aff5a6Chris Lattner // avoid other simplifycfg's kicking in on the diamond. 136960d410d7bb2eb11f36a004237e5948ffc5aff5a6Chris Lattner TerminatorInst *OldTI = DomBlock->getTerminator(); 1370f60364de44add5c92841425851cda1a6943bfcd7Devang Patel Builder.SetInsertPoint(OldTI); 1371f60364de44add5c92841425851cda1a6943bfcd7Devang Patel Builder.CreateBr(BB); 137260d410d7bb2eb11f36a004237e5948ffc5aff5a6Chris Lattner OldTI->eraseFromParent(); 1373f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner return true; 1374f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner} 1375eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner 1376c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner/// SimplifyCondBranchToTwoReturns - If we found a conditional branch that goes 1377c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner/// to two returning blocks, try to merge them together into one return, 1378c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner/// introducing a select if the return values disagree. 1379176ec40cb18c51c14fccbb38ee0db5deafb6baa9Devang Patelstatic bool SimplifyCondBranchToTwoReturns(BranchInst *BI, 1380176ec40cb18c51c14fccbb38ee0db5deafb6baa9Devang Patel IRBuilder<> &Builder) { 1381c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner assert(BI->isConditional() && "Must be a conditional branch"); 1382c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner BasicBlock *TrueSucc = BI->getSuccessor(0); 1383c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner BasicBlock *FalseSucc = BI->getSuccessor(1); 1384c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner ReturnInst *TrueRet = cast<ReturnInst>(TrueSucc->getTerminator()); 1385c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner ReturnInst *FalseRet = cast<ReturnInst>(FalseSucc->getTerminator()); 1386c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner 1387c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner // Check to ensure both blocks are empty (just a return) or optionally empty 1388c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner // with PHI nodes. If there are other instructions, merging would cause extra 1389c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner // computation on one path or the other. 13909a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (!TrueSucc->getFirstNonPHIOrDbg()->isTerminator()) 13912cc86a1de1cf598be384836f19d1ef1892fb50fcDevang Patel return false; 13929a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (!FalseSucc->getFirstNonPHIOrDbg()->isTerminator()) 13932cc86a1de1cf598be384836f19d1ef1892fb50fcDevang Patel return false; 1394c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner 1395176ec40cb18c51c14fccbb38ee0db5deafb6baa9Devang Patel Builder.SetInsertPoint(BI); 1396c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner // Okay, we found a branch that is going to two return nodes. If 1397c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner // there is no return value for this function, just change the 1398c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner // branch into a return. 1399c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner if (FalseRet->getNumOperands() == 0) { 1400c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner TrueSucc->removePredecessor(BI->getParent()); 1401c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner FalseSucc->removePredecessor(BI->getParent()); 1402176ec40cb18c51c14fccbb38ee0db5deafb6baa9Devang Patel Builder.CreateRetVoid(); 1403080efb8cea6255b4f1f373d9cb583d6a6302106bEli Friedman EraseTerminatorInstAndDCECond(BI); 1404c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner return true; 1405c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner } 1406c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner 1407fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman // Otherwise, figure out what the true and false return values are 1408fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman // so we can insert a new select instruction. 1409fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman Value *TrueValue = TrueRet->getReturnValue(); 1410fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman Value *FalseValue = FalseRet->getReturnValue(); 1411fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman 1412fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman // Unwrap any PHI nodes in the return blocks. 1413fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman if (PHINode *TVPN = dyn_cast_or_null<PHINode>(TrueValue)) 1414fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman if (TVPN->getParent() == TrueSucc) 1415fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman TrueValue = TVPN->getIncomingValueForBlock(BI->getParent()); 1416fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman if (PHINode *FVPN = dyn_cast_or_null<PHINode>(FalseValue)) 1417fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman if (FVPN->getParent() == FalseSucc) 1418fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman FalseValue = FVPN->getIncomingValueForBlock(BI->getParent()); 1419fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman 1420fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman // In order for this transformation to be safe, we must be able to 1421fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman // unconditionally execute both operands to the return. This is 1422fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman // normally the case, but we could have a potentially-trapping 1423fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman // constant expression that prevents this transformation from being 1424fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman // safe. 1425fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman if (ConstantExpr *TCV = dyn_cast_or_null<ConstantExpr>(TrueValue)) 1426fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman if (TCV->canTrap()) 1427fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman return false; 1428fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman if (ConstantExpr *FCV = dyn_cast_or_null<ConstantExpr>(FalseValue)) 1429fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman if (FCV->canTrap()) 1430fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman return false; 1431c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner 1432c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner // Okay, we collected all the mapped values and checked them for sanity, and 1433c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner // defined to really do this transformation. First, update the CFG. 1434c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner TrueSucc->removePredecessor(BI->getParent()); 1435c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner FalseSucc->removePredecessor(BI->getParent()); 1436c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner 1437c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner // Insert select instructions where needed. 1438c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner Value *BrCond = BI->getCondition(); 1439fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman if (TrueValue) { 1440c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner // Insert a select if the results differ. 1441fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman if (TrueValue == FalseValue || isa<UndefValue>(FalseValue)) { 1442fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman } else if (isa<UndefValue>(TrueValue)) { 1443fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman TrueValue = FalseValue; 1444fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman } else { 1445176ec40cb18c51c14fccbb38ee0db5deafb6baa9Devang Patel TrueValue = Builder.CreateSelect(BrCond, TrueValue, 1446176ec40cb18c51c14fccbb38ee0db5deafb6baa9Devang Patel FalseValue, "retval"); 1447c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner } 1448c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner } 1449c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner 1450176ec40cb18c51c14fccbb38ee0db5deafb6baa9Devang Patel Value *RI = !TrueValue ? 1451176ec40cb18c51c14fccbb38ee0db5deafb6baa9Devang Patel Builder.CreateRetVoid() : Builder.CreateRet(TrueValue); 1452176ec40cb18c51c14fccbb38ee0db5deafb6baa9Devang Patel 1453e317bcc74c1f317f913e9b05db385901cfc54d0bDaniel Dunbar (void) RI; 1454c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner 145589d6fd36a26fdf068ceea90422dc2897e89700b5David Greene DEBUG(dbgs() << "\nCHANGING BRANCH TO TWO RETURNS INTO SELECT:" 1456bdff548e4dd577a72094d57b282de4e765643b96Chris Lattner << "\n " << *BI << "NewRet = " << *RI 1457bdff548e4dd577a72094d57b282de4e765643b96Chris Lattner << "TRUEBLOCK: " << *TrueSucc << "FALSEBLOCK: "<< *FalseSucc); 1458c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner 1459080efb8cea6255b4f1f373d9cb583d6a6302106bEli Friedman EraseTerminatorInstAndDCECond(BI); 1460080efb8cea6255b4f1f373d9cb583d6a6302106bEli Friedman 1461c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner return true; 1462c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner} 1463c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner 1464c8fbc34869fc1737adea00f775de5b8dd829f7a1Chris Lattner/// FoldBranchToCommonDest - If this basic block is simple enough, and if a 1465c8fbc34869fc1737adea00f775de5b8dd829f7a1Chris Lattner/// predecessor branches to us and one of our successors, fold the block into 1466c8fbc34869fc1737adea00f775de5b8dd829f7a1Chris Lattner/// the predecessor and use logical operations to pick the right destination. 14674b35f83b91a1a313f0730c600e5178aaf7df98d6Dan Gohmanbool llvm::FoldBranchToCommonDest(BranchInst *BI) { 1468093a4385027235459ab6972b2e2fdc79061773cfChris Lattner BasicBlock *BB = BI->getParent(); 1469d3a1788da15311781f661c1cbfe48cd5f98ae778Devang Patel 14701347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner Instruction *Cond = dyn_cast<Instruction>(BI->getCondition()); 1471e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson if (Cond == 0 || (!isa<CmpInst>(Cond) && !isa<BinaryOperator>(Cond)) || 1472e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson Cond->getParent() != BB || !Cond->hasOneUse()) 1473e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson return false; 1474d418194036e9e05f47154535ddb9f1f1c8bc592bDevang Patel 14751347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner // Only allow this if the condition is a simple instruction that can be 14761347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner // executed unconditionally. It must be in the same block as the branch, and 14771347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner // must be at the front of the block. 1478d0a203d76f4ef77ae1c392e8e73e2f05b676a5f2Devang Patel BasicBlock::iterator FrontIt = BB->front(); 14793c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner 1480d0a203d76f4ef77ae1c392e8e73e2f05b676a5f2Devang Patel // Ignore dbg intrinsics. 14813c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner while (isa<DbgInfoIntrinsic>(FrontIt)) ++FrontIt; 1482e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson 1483e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson // Allow a single instruction to be hoisted in addition to the compare 1484e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson // that feeds the branch. We later ensure that any values that _it_ uses 1485e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson // were also live in the predecessor, so that we don't unnecessarily create 1486e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson // register pressure or inhibit out-of-order execution. 1487e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson Instruction *BonusInst = 0; 1488e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson if (&*FrontIt != Cond && 14892722dfa75dbf4436197f6fcf9d8cb2391975f1a1Owen Anderson FrontIt->hasOneUse() && *FrontIt->use_begin() == Cond && 1490f0426601977c3e386d2d26c72a2cca691dc42072Dan Gohman isSafeToSpeculativelyExecute(FrontIt)) { 1491e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson BonusInst = &*FrontIt; 1492e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson ++FrontIt; 14933c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner 14943c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner // Ignore dbg intrinsics. 14953c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner while (isa<DbgInfoIntrinsic>(FrontIt)) ++FrontIt; 149660d490cdc7b11e678f35f5b7eb2c9ef354462211Devang Patel } 149760d490cdc7b11e678f35f5b7eb2c9ef354462211Devang Patel 1498e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson // Only a single bonus inst is allowed. 1499e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson if (&*FrontIt != Cond) 1500e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson return false; 1501e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson 15021347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner // Make sure the instruction after the condition is the cond branch. 15031347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner BasicBlock::iterator CondIt = Cond; ++CondIt; 15043c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner 1505d0a203d76f4ef77ae1c392e8e73e2f05b676a5f2Devang Patel // Ingore dbg intrinsics. 15063c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner while (isa<DbgInfoIntrinsic>(CondIt)) ++CondIt; 15073c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner 15083c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner if (&*CondIt != BI) 15091347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner return false; 15106ff645bf0fcfc0c62e9d9126e1243ec8bf10abbcChris Lattner 15116ff645bf0fcfc0c62e9d9126e1243ec8bf10abbcChris Lattner // Cond is known to be a compare or binary operator. Check to make sure that 15126ff645bf0fcfc0c62e9d9126e1243ec8bf10abbcChris Lattner // neither operand is a potentially-trapping constant expression. 15136ff645bf0fcfc0c62e9d9126e1243ec8bf10abbcChris Lattner if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Cond->getOperand(0))) 15146ff645bf0fcfc0c62e9d9126e1243ec8bf10abbcChris Lattner if (CE->canTrap()) 15156ff645bf0fcfc0c62e9d9126e1243ec8bf10abbcChris Lattner return false; 15166ff645bf0fcfc0c62e9d9126e1243ec8bf10abbcChris Lattner if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Cond->getOperand(1))) 15176ff645bf0fcfc0c62e9d9126e1243ec8bf10abbcChris Lattner if (CE->canTrap()) 15186ff645bf0fcfc0c62e9d9126e1243ec8bf10abbcChris Lattner return false; 15196ff645bf0fcfc0c62e9d9126e1243ec8bf10abbcChris Lattner 15201347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner // Finally, don't infinitely unroll conditional loops. 15211347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner BasicBlock *TrueDest = BI->getSuccessor(0); 15221347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner BasicBlock *FalseDest = BI->getSuccessor(1); 15231347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner if (TrueDest == BB || FalseDest == BB) 15241347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner return false; 1525d418194036e9e05f47154535ddb9f1f1c8bc592bDevang Patel 15261347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI) { 15271347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner BasicBlock *PredBlock = *PI; 15281347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner BranchInst *PBI = dyn_cast<BranchInst>(PredBlock->getTerminator()); 15296ff645bf0fcfc0c62e9d9126e1243ec8bf10abbcChris Lattner 1530093a4385027235459ab6972b2e2fdc79061773cfChris Lattner // Check that we have two conditional branches. If there is a PHI node in 1531093a4385027235459ab6972b2e2fdc79061773cfChris Lattner // the common successor, verify that the same value flows in from both 1532093a4385027235459ab6972b2e2fdc79061773cfChris Lattner // blocks. 15333c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner if (PBI == 0 || PBI->isUnconditional() || !SafeToMergeTerminators(BI, PBI)) 15341347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner continue; 15351347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner 15363c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner // Determine if the two branches share a common destination. 15373c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner Instruction::BinaryOps Opc; 15383c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner bool InvertPredCond = false; 15393c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner 15403c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner if (PBI->getSuccessor(0) == TrueDest) 15413c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner Opc = Instruction::Or; 15423c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner else if (PBI->getSuccessor(1) == FalseDest) 15433c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner Opc = Instruction::And; 15443c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner else if (PBI->getSuccessor(0) == FalseDest) 15453c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner Opc = Instruction::And, InvertPredCond = true; 15463c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner else if (PBI->getSuccessor(1) == TrueDest) 15473c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner Opc = Instruction::Or, InvertPredCond = true; 15483c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner else 15493c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner continue; 15503c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner 1551e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson // Ensure that any values used in the bonus instruction are also used 1552e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson // by the terminator of the predecessor. This means that those values 1553e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson // must already have been resolved, so we won't be inhibiting the 1554e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson // out-of-order core by speculating them earlier. 1555e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson if (BonusInst) { 1556e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson // Collect the values used by the bonus inst 1557e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson SmallPtrSet<Value*, 4> UsedValues; 1558e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson for (Instruction::op_iterator OI = BonusInst->op_begin(), 1559e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson OE = BonusInst->op_end(); OI != OE; ++OI) { 1560e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson Value* V = *OI; 1561e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson if (!isa<Constant>(V)) 1562e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson UsedValues.insert(V); 1563e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson } 1564e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson 1565e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson SmallVector<std::pair<Value*, unsigned>, 4> Worklist; 1566e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson Worklist.push_back(std::make_pair(PBI->getOperand(0), 0)); 1567e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson 1568e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson // Walk up to four levels back up the use-def chain of the predecessor's 1569e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson // terminator to see if all those values were used. The choice of four 1570e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson // levels is arbitrary, to provide a compile-time-cost bound. 1571e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson while (!Worklist.empty()) { 1572e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson std::pair<Value*, unsigned> Pair = Worklist.back(); 1573e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson Worklist.pop_back(); 1574e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson 1575e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson if (Pair.second >= 4) continue; 1576e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson UsedValues.erase(Pair.first); 1577e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson if (UsedValues.empty()) break; 1578e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson 1579daa02ab70c7619cc22131c75c62390cf3f5f8891Chris Lattner if (Instruction *I = dyn_cast<Instruction>(Pair.first)) { 1580e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson for (Instruction::op_iterator OI = I->op_begin(), OE = I->op_end(); 1581e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson OI != OE; ++OI) 1582e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson Worklist.push_back(std::make_pair(OI->get(), Pair.second+1)); 1583e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson } 1584e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson } 1585e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson 1586e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson if (!UsedValues.empty()) return false; 1587e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson } 15883698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner 158989d6fd36a26fdf068ceea90422dc2897e89700b5David Greene DEBUG(dbgs() << "FOLDING BRANCH TO COMMON DEST:\n" << *PBI << *BB); 1590d3a1788da15311781f661c1cbfe48cd5f98ae778Devang Patel IRBuilder<> Builder(PBI); 1591d3a1788da15311781f661c1cbfe48cd5f98ae778Devang Patel 15923698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner // If we need to invert the condition in the pred block to match, do so now. 15933698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner if (InvertPredCond) { 1594daa02ab70c7619cc22131c75c62390cf3f5f8891Chris Lattner Value *NewCond = PBI->getCondition(); 1595daa02ab70c7619cc22131c75c62390cf3f5f8891Chris Lattner 1596daa02ab70c7619cc22131c75c62390cf3f5f8891Chris Lattner if (NewCond->hasOneUse() && isa<CmpInst>(NewCond)) { 1597daa02ab70c7619cc22131c75c62390cf3f5f8891Chris Lattner CmpInst *CI = cast<CmpInst>(NewCond); 1598daa02ab70c7619cc22131c75c62390cf3f5f8891Chris Lattner CI->setPredicate(CI->getInversePredicate()); 1599daa02ab70c7619cc22131c75c62390cf3f5f8891Chris Lattner } else { 1600d3a1788da15311781f661c1cbfe48cd5f98ae778Devang Patel NewCond = Builder.CreateNot(NewCond, 1601d3a1788da15311781f661c1cbfe48cd5f98ae778Devang Patel PBI->getCondition()->getName()+".not"); 1602daa02ab70c7619cc22131c75c62390cf3f5f8891Chris Lattner } 1603daa02ab70c7619cc22131c75c62390cf3f5f8891Chris Lattner 16041347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner PBI->setCondition(NewCond); 16051347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner BasicBlock *OldTrue = PBI->getSuccessor(0); 16061347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner BasicBlock *OldFalse = PBI->getSuccessor(1); 16071347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner PBI->setSuccessor(0, OldFalse); 16081347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner PBI->setSuccessor(1, OldTrue); 16091347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner } 161070087f31f154156bcb494dd0cf3b7d74c0c8b528Chris Lattner 1611e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson // If we have a bonus inst, clone it into the predecessor block. 1612e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson Instruction *NewBonus = 0; 1613e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson if (BonusInst) { 1614e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson NewBonus = BonusInst->clone(); 1615e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson PredBlock->getInstList().insert(PBI, NewBonus); 1616e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson NewBonus->takeName(BonusInst); 1617e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson BonusInst->setName(BonusInst->getName()+".old"); 1618e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson } 1619e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson 16203698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner // Clone Cond into the predecessor basic block, and or/and the 16213698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner // two conditions together. 16226776064d190701c5bae4d5403939eed2e480d1cdNick Lewycky Instruction *New = Cond->clone(); 1623e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson if (BonusInst) New->replaceUsesOfWith(BonusInst, NewBonus); 16243698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner PredBlock->getInstList().insert(PBI, New); 16253698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner New->takeName(Cond); 16263698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner Cond->setName(New->getName()+".old"); 162770087f31f154156bcb494dd0cf3b7d74c0c8b528Chris Lattner 1628d3a1788da15311781f661c1cbfe48cd5f98ae778Devang Patel Instruction *NewCond = 1629d3a1788da15311781f661c1cbfe48cd5f98ae778Devang Patel cast<Instruction>(Builder.CreateBinOp(Opc, PBI->getCondition(), 1630d3a1788da15311781f661c1cbfe48cd5f98ae778Devang Patel New, "or.cond")); 16313698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner PBI->setCondition(NewCond); 16323698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner if (PBI->getSuccessor(0) == BB) { 16333698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner AddPredecessorToBlock(TrueDest, PredBlock, BB); 16343698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner PBI->setSuccessor(0, TrueDest); 16353698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner } 16363698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner if (PBI->getSuccessor(1) == BB) { 16373698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner AddPredecessorToBlock(FalseDest, PredBlock, BB); 16383698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner PBI->setSuccessor(1, FalseDest); 16391347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner } 1640d418194036e9e05f47154535ddb9f1f1c8bc592bDevang Patel 16413c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner // Copy any debug value intrinsics into the end of PredBlock. 16423c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) 16433c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner if (isa<DbgInfoIntrinsic>(*I)) 16443c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner I->clone()->insertBefore(PBI); 16453c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner 1646117f8cffc5499217ff8824eb0d6a0f6b1b78d96eChris Lattner return true; 16471347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner } 16481347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner return false; 16491347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner} 16501347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner 1651867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner/// SimplifyCondBranchToCondBranch - If we have a conditional branch as a 1652867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner/// predecessor of another block, this function tries to simplify it. We know 1653867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner/// that PBI and BI are both conditional branches, and BI is in one of the 1654867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner/// successor blocks of PBI - PBI branches to BI. 1655867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattnerstatic bool SimplifyCondBranchToCondBranch(BranchInst *PBI, BranchInst *BI) { 1656867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner assert(PBI->isConditional() && BI->isConditional()); 1657867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner BasicBlock *BB = BI->getParent(); 16584ae5126d041768ab9665cf2f11c024becd76c41fDan Gohman 1659867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner // If this block ends with a branch instruction, and if there is a 1660867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner // predecessor that ends on a branch of the same condition, make 1661867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner // this conditional branch redundant. 1662867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner if (PBI->getCondition() == BI->getCondition() && 1663867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner PBI->getSuccessor(0) != PBI->getSuccessor(1)) { 1664867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner // Okay, the outcome of this conditional branch is statically 1665867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner // knowable. If this block had a single pred, handle specially. 1666867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner if (BB->getSinglePredecessor()) { 1667867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner // Turn this into a branch on constant. 1668867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner bool CondIsTrue = PBI->getSuccessor(0) == BB; 16691d0be15f89cb5056e20e2d24faa8d6afb1573bcaOwen Anderson BI->setCondition(ConstantInt::get(Type::getInt1Ty(BB->getContext()), 16701d0be15f89cb5056e20e2d24faa8d6afb1573bcaOwen Anderson CondIsTrue)); 1671867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner return true; // Nuke the branch on constant. 1672867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner } 1673867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner 1674867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner // Otherwise, if there are multiple predecessors, insert a PHI that merges 1675867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner // in the constant and simplify the block result. Subsequent passes of 1676867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner // simplifycfg will thread the block. 1677867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner if (BlockIsSimpleEnoughToThreadThrough(BB)) { 1678d8b4fb4aab4d6fedb2b14bed1b846451b17bde7cJay Foad pred_iterator PB = pred_begin(BB), PE = pred_end(BB); 16791d0be15f89cb5056e20e2d24faa8d6afb1573bcaOwen Anderson PHINode *NewPN = PHINode::Create(Type::getInt1Ty(BB->getContext()), 16803ecfc861b4365f341c5c969b40e1afccde676e6fJay Foad std::distance(PB, PE), 1681867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner BI->getCondition()->getName() + ".pr", 1682867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner BB->begin()); 1683eb388af89f15ee3de6f53359473e1a54418a667fChris Lattner // Okay, we're going to insert the PHI node. Since PBI is not the only 1684eb388af89f15ee3de6f53359473e1a54418a667fChris Lattner // predecessor, compute the PHI'd conditional value for all of the preds. 1685eb388af89f15ee3de6f53359473e1a54418a667fChris Lattner // Any predecessor where the condition is not computable we keep symbolic. 1686d8b4fb4aab4d6fedb2b14bed1b846451b17bde7cJay Foad for (pred_iterator PI = PB; PI != PE; ++PI) { 1687625398343e2673a0c4bb5228fc88f71fe4e1c629Gabor Greif BasicBlock *P = *PI; 1688625398343e2673a0c4bb5228fc88f71fe4e1c629Gabor Greif if ((PBI = dyn_cast<BranchInst>(P->getTerminator())) && 1689867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner PBI != BI && PBI->isConditional() && 1690867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner PBI->getCondition() == BI->getCondition() && 1691867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner PBI->getSuccessor(0) != PBI->getSuccessor(1)) { 1692867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner bool CondIsTrue = PBI->getSuccessor(0) == BB; 16931d0be15f89cb5056e20e2d24faa8d6afb1573bcaOwen Anderson NewPN->addIncoming(ConstantInt::get(Type::getInt1Ty(BB->getContext()), 1694625398343e2673a0c4bb5228fc88f71fe4e1c629Gabor Greif CondIsTrue), P); 1695867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner } else { 1696625398343e2673a0c4bb5228fc88f71fe4e1c629Gabor Greif NewPN->addIncoming(BI->getCondition(), P); 1697867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner } 1698625398343e2673a0c4bb5228fc88f71fe4e1c629Gabor Greif } 1699867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner 1700867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner BI->setCondition(NewPN); 1701867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner return true; 1702867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner } 1703867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner } 1704867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner 1705867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner // If this is a conditional branch in an empty block, and if any 1706867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner // predecessors is a conditional branch to one of our destinations, 1707867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner // fold the conditions into logical ops and one cond br. 1708a8d57fe96bb870e4f69c6b522a78936d1495d0d2Zhou Sheng BasicBlock::iterator BBI = BB->begin(); 1709a8d57fe96bb870e4f69c6b522a78936d1495d0d2Zhou Sheng // Ignore dbg intrinsics. 1710a8d57fe96bb870e4f69c6b522a78936d1495d0d2Zhou Sheng while (isa<DbgInfoIntrinsic>(BBI)) 1711a8d57fe96bb870e4f69c6b522a78936d1495d0d2Zhou Sheng ++BBI; 1712a8d57fe96bb870e4f69c6b522a78936d1495d0d2Zhou Sheng if (&*BBI != BI) 1713b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner return false; 171463bf29b5b1c741038d6d502d62721cac0d2760b4Chris Lattner 171563bf29b5b1c741038d6d502d62721cac0d2760b4Chris Lattner 171663bf29b5b1c741038d6d502d62721cac0d2760b4Chris Lattner if (ConstantExpr *CE = dyn_cast<ConstantExpr>(BI->getCondition())) 171763bf29b5b1c741038d6d502d62721cac0d2760b4Chris Lattner if (CE->canTrap()) 171863bf29b5b1c741038d6d502d62721cac0d2760b4Chris Lattner return false; 1719b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner 1720b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner int PBIOp, BIOp; 1721b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner if (PBI->getSuccessor(0) == BI->getSuccessor(0)) 1722b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner PBIOp = BIOp = 0; 1723b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner else if (PBI->getSuccessor(0) == BI->getSuccessor(1)) 1724b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner PBIOp = 0, BIOp = 1; 1725b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner else if (PBI->getSuccessor(1) == BI->getSuccessor(0)) 1726b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner PBIOp = 1, BIOp = 0; 1727b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner else if (PBI->getSuccessor(1) == BI->getSuccessor(1)) 1728b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner PBIOp = BIOp = 1; 1729b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner else 1730b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner return false; 1731867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner 1732b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // Check to make sure that the other destination of this branch 1733b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // isn't BB itself. If so, this is an infinite loop that will 1734b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // keep getting unwound. 1735b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner if (PBI->getSuccessor(PBIOp) == BB) 1736b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner return false; 1737867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner 1738b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // Do not perform this transformation if it would require 1739b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // insertion of a large number of select instructions. For targets 1740b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // without predication/cmovs, this is a big pessimization. 1741b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner BasicBlock *CommonDest = PBI->getSuccessor(PBIOp); 1742867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner 1743b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner unsigned NumPhis = 0; 1744b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner for (BasicBlock::iterator II = CommonDest->begin(); 1745b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner isa<PHINode>(II); ++II, ++NumPhis) 1746b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner if (NumPhis > 2) // Disable this xform. 1747b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner return false; 1748867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner 1749b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // Finally, if everything is ok, fold the branches to logical ops. 1750b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner BasicBlock *OtherDest = BI->getSuccessor(BIOp ^ 1); 1751b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner 175289d6fd36a26fdf068ceea90422dc2897e89700b5David Greene DEBUG(dbgs() << "FOLDING BRs:" << *PBI->getParent() 1753bdff548e4dd577a72094d57b282de4e765643b96Chris Lattner << "AND: " << *BI->getParent()); 1754b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner 1755093a4385027235459ab6972b2e2fdc79061773cfChris Lattner 1756093a4385027235459ab6972b2e2fdc79061773cfChris Lattner // If OtherDest *is* BB, then BB is a basic block with a single conditional 1757093a4385027235459ab6972b2e2fdc79061773cfChris Lattner // branch in it, where one edge (OtherDest) goes back to itself but the other 1758093a4385027235459ab6972b2e2fdc79061773cfChris Lattner // exits. We don't *know* that the program avoids the infinite loop 1759093a4385027235459ab6972b2e2fdc79061773cfChris Lattner // (even though that seems likely). If we do this xform naively, we'll end up 1760093a4385027235459ab6972b2e2fdc79061773cfChris Lattner // recursively unpeeling the loop. Since we know that (after the xform is 1761093a4385027235459ab6972b2e2fdc79061773cfChris Lattner // done) that the block *is* infinite if reached, we just make it an obviously 1762093a4385027235459ab6972b2e2fdc79061773cfChris Lattner // infinite loop with no cond branch. 1763093a4385027235459ab6972b2e2fdc79061773cfChris Lattner if (OtherDest == BB) { 1764093a4385027235459ab6972b2e2fdc79061773cfChris Lattner // Insert it at the end of the function, because it's either code, 1765093a4385027235459ab6972b2e2fdc79061773cfChris Lattner // or it won't matter if it's hot. :) 17661d0be15f89cb5056e20e2d24faa8d6afb1573bcaOwen Anderson BasicBlock *InfLoopBlock = BasicBlock::Create(BB->getContext(), 17671d0be15f89cb5056e20e2d24faa8d6afb1573bcaOwen Anderson "infloop", BB->getParent()); 1768093a4385027235459ab6972b2e2fdc79061773cfChris Lattner BranchInst::Create(InfLoopBlock, InfLoopBlock); 1769093a4385027235459ab6972b2e2fdc79061773cfChris Lattner OtherDest = InfLoopBlock; 1770093a4385027235459ab6972b2e2fdc79061773cfChris Lattner } 1771093a4385027235459ab6972b2e2fdc79061773cfChris Lattner 177289d6fd36a26fdf068ceea90422dc2897e89700b5David Greene DEBUG(dbgs() << *PBI->getParent()->getParent()); 1773d3a1788da15311781f661c1cbfe48cd5f98ae778Devang Patel 1774b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // BI may have other predecessors. Because of this, we leave 1775b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // it alone, but modify PBI. 1776b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner 1777b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // Make sure we get to CommonDest on True&True directions. 1778b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner Value *PBICond = PBI->getCondition(); 1779d3a1788da15311781f661c1cbfe48cd5f98ae778Devang Patel IRBuilder<true, NoFolder> Builder(PBI); 1780b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner if (PBIOp) 1781d3a1788da15311781f661c1cbfe48cd5f98ae778Devang Patel PBICond = Builder.CreateNot(PBICond, PBICond->getName()+".not"); 1782d3a1788da15311781f661c1cbfe48cd5f98ae778Devang Patel 1783b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner Value *BICond = BI->getCondition(); 1784b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner if (BIOp) 1785d3a1788da15311781f661c1cbfe48cd5f98ae778Devang Patel BICond = Builder.CreateNot(BICond, BICond->getName()+".not"); 1786d3a1788da15311781f661c1cbfe48cd5f98ae778Devang Patel 1787b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // Merge the conditions. 1788d3a1788da15311781f661c1cbfe48cd5f98ae778Devang Patel Value *Cond = Builder.CreateOr(PBICond, BICond, "brmerge"); 1789b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner 1790b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // Modify PBI to branch on the new condition to the new dests. 1791b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner PBI->setCondition(Cond); 1792b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner PBI->setSuccessor(0, CommonDest); 1793b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner PBI->setSuccessor(1, OtherDest); 1794b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner 1795b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // OtherDest may have phi nodes. If so, add an entry from PBI's 1796b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // block that are identical to the entries for BI's block. 17976de0a28dfb84095ebd7775f371dd4085cf955076Chris Lattner AddPredecessorToBlock(OtherDest, PBI->getParent(), BB); 1798b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner 1799b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // We know that the CommonDest already had an edge from PBI to 1800b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // it. If it has PHIs though, the PHIs may have different 1801b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // entries for BB and PBI's BB. If so, insert a select to make 1802b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // them agree. 18036de0a28dfb84095ebd7775f371dd4085cf955076Chris Lattner PHINode *PN; 1804b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner for (BasicBlock::iterator II = CommonDest->begin(); 1805b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner (PN = dyn_cast<PHINode>(II)); ++II) { 1806b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner Value *BIV = PN->getIncomingValueForBlock(BB); 1807b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner unsigned PBBIdx = PN->getBasicBlockIndex(PBI->getParent()); 1808b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner Value *PBIV = PN->getIncomingValue(PBBIdx); 1809b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner if (BIV != PBIV) { 1810b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // Insert a select in PBI to pick the right value. 1811d3a1788da15311781f661c1cbfe48cd5f98ae778Devang Patel Value *NV = cast<SelectInst> 1812d3a1788da15311781f661c1cbfe48cd5f98ae778Devang Patel (Builder.CreateSelect(PBICond, PBIV, BIV, PBIV->getName()+".mux")); 1813b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner PN->setIncomingValue(PBBIdx, NV); 1814867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner } 1815867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner } 1816b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner 181789d6fd36a26fdf068ceea90422dc2897e89700b5David Greene DEBUG(dbgs() << "INTO: " << *PBI->getParent()); 181889d6fd36a26fdf068ceea90422dc2897e89700b5David Greene DEBUG(dbgs() << *PBI->getParent()->getParent()); 1819b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner 1820b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // This basic block is probably dead. We know it has at least 1821b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // one fewer predecessor. 1822b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner return true; 1823867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner} 1824867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner 182565fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel// SimplifyTerminatorOnSelect - Simplifies a terminator by replacing it with a 182665fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel// branch to TrueBB if Cond is true or to FalseBB if Cond is false. 182765fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel// Takes care of updating the successors and removing the old terminator. 182865fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel// Also makes sure not to introduce new successors by assuming that edges to 182965fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel// non-successor TrueBBs and FalseBBs aren't reachable. 183065fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommelstatic bool SimplifyTerminatorOnSelect(TerminatorInst *OldTerm, Value *Cond, 183165fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel BasicBlock *TrueBB, BasicBlock *FalseBB){ 18327ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel // Remove any superfluous successor edges from the CFG. 18337ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel // First, figure out which successors to preserve. 18347ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel // If TrueBB and FalseBB are equal, only try to preserve one copy of that 18357ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel // successor. 18367ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel BasicBlock *KeepEdge1 = TrueBB; 18377ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel BasicBlock *KeepEdge2 = TrueBB != FalseBB ? FalseBB : 0; 18387ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel 18397ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel // Then remove the rest. 184065fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel for (unsigned I = 0, E = OldTerm->getNumSuccessors(); I != E; ++I) { 184165fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel BasicBlock *Succ = OldTerm->getSuccessor(I); 18427ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel // Make sure only to keep exactly one copy of each edge. 18437ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel if (Succ == KeepEdge1) 18447ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel KeepEdge1 = 0; 18457ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel else if (Succ == KeepEdge2) 18467ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel KeepEdge2 = 0; 18477ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel else 184865fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel Succ->removePredecessor(OldTerm->getParent()); 18497ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel } 18507ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel 1851d3372b85e6008d85e30d13172ef0b1646b482b7eDevang Patel IRBuilder<> Builder(OldTerm); 1852d3372b85e6008d85e30d13172ef0b1646b482b7eDevang Patel Builder.SetCurrentDebugLocation(OldTerm->getDebugLoc()); 1853d3372b85e6008d85e30d13172ef0b1646b482b7eDevang Patel 18547ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel // Insert an appropriate new terminator. 18557ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel if ((KeepEdge1 == 0) && (KeepEdge2 == 0)) { 18567ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel if (TrueBB == FalseBB) 18577ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel // We were only looking for one successor, and it was present. 18587ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel // Create an unconditional branch to it. 1859d3372b85e6008d85e30d13172ef0b1646b482b7eDevang Patel Builder.CreateBr(TrueBB); 18607ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel else 18617ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel // We found both of the successors we were looking for. 18627ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel // Create a conditional branch sharing the condition of the select. 1863d3372b85e6008d85e30d13172ef0b1646b482b7eDevang Patel Builder.CreateCondBr(Cond, TrueBB, FalseBB); 18647ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel } else if (KeepEdge1 && (KeepEdge2 || TrueBB == FalseBB)) { 18657ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel // Neither of the selected blocks were successors, so this 186665fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel // terminator must be unreachable. 186765fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel new UnreachableInst(OldTerm->getContext(), OldTerm); 18687ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel } else { 18697ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel // One of the selected values was a successor, but the other wasn't. 18707ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel // Insert an unconditional branch to the one that was found; 18717ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel // the edge to the one that wasn't must be unreachable. 18727ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel if (KeepEdge1 == 0) 18737ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel // Only TrueBB was found. 1874d3372b85e6008d85e30d13172ef0b1646b482b7eDevang Patel Builder.CreateBr(TrueBB); 18757ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel else 18767ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel // Only FalseBB was found. 1877d3372b85e6008d85e30d13172ef0b1646b482b7eDevang Patel Builder.CreateBr(FalseBB); 18787ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel } 18797ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel 188065fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel EraseTerminatorInstAndDCECond(OldTerm); 18817ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel return true; 18827ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel} 18837ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel 1884f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel// SimplifySwitchOnSelect - Replaces 1885f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel// (switch (select cond, X, Y)) on constant X, Y 1886f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel// with a branch - conditional if X and Y lead to distinct BBs, 1887f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel// unconditional otherwise. 1888f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommelstatic bool SimplifySwitchOnSelect(SwitchInst *SI, SelectInst *Select) { 1889f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel // Check for constant integer values in the select. 1890f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel ConstantInt *TrueVal = dyn_cast<ConstantInt>(Select->getTrueValue()); 1891f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel ConstantInt *FalseVal = dyn_cast<ConstantInt>(Select->getFalseValue()); 1892f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel if (!TrueVal || !FalseVal) 1893f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel return false; 1894f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel 1895f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel // Find the relevant condition and destinations. 1896f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel Value *Condition = Select->getCondition(); 1897f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel BasicBlock *TrueBB = SI->getSuccessor(SI->findCaseValue(TrueVal)); 1898f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel BasicBlock *FalseBB = SI->getSuccessor(SI->findCaseValue(FalseVal)); 1899f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel 1900f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel // Perform the actual simplification. 1901f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel return SimplifyTerminatorOnSelect(SI, Condition, TrueBB, FalseBB); 1902f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel} 1903f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel 190465fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel// SimplifyIndirectBrOnSelect - Replaces 190565fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel// (indirectbr (select cond, blockaddress(@fn, BlockA), 190665fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel// blockaddress(@fn, BlockB))) 190765fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel// with 190865fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel// (br cond, BlockA, BlockB). 190965fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommelstatic bool SimplifyIndirectBrOnSelect(IndirectBrInst *IBI, SelectInst *SI) { 191065fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel // Check that both operands of the select are block addresses. 191165fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel BlockAddress *TBA = dyn_cast<BlockAddress>(SI->getTrueValue()); 191265fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel BlockAddress *FBA = dyn_cast<BlockAddress>(SI->getFalseValue()); 191365fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel if (!TBA || !FBA) 191465fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel return false; 191565fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel 191665fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel // Extract the actual blocks. 191765fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel BasicBlock *TrueBB = TBA->getBasicBlock(); 191865fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel BasicBlock *FalseBB = FBA->getBasicBlock(); 191965fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel 192065fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel // Perform the actual simplification. 192165fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel return SimplifyTerminatorOnSelect(IBI, SI->getCondition(), TrueBB, FalseBB); 192265fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel} 192365fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel 192461c77449c772427a0d2559fca500debd93c7f97cChris Lattner/// TryToSimplifyUncondBranchWithICmpInIt - This is called when we find an icmp 192561c77449c772427a0d2559fca500debd93c7f97cChris Lattner/// instruction (a seteq/setne with a constant) as the only instruction in a 192661c77449c772427a0d2559fca500debd93c7f97cChris Lattner/// block that ends with an uncond branch. We are looking for a very specific 192761c77449c772427a0d2559fca500debd93c7f97cChris Lattner/// pattern that occurs when "A == 1 || A == 2 || A == 3" gets simplified. In 192861c77449c772427a0d2559fca500debd93c7f97cChris Lattner/// this case, we merge the first two "or's of icmp" into a switch, but then the 192961c77449c772427a0d2559fca500debd93c7f97cChris Lattner/// default value goes to an uncond block with a seteq in it, we get something 193061c77449c772427a0d2559fca500debd93c7f97cChris Lattner/// like: 193161c77449c772427a0d2559fca500debd93c7f97cChris Lattner/// 193261c77449c772427a0d2559fca500debd93c7f97cChris Lattner/// switch i8 %A, label %DEFAULT [ i8 1, label %end i8 2, label %end ] 193361c77449c772427a0d2559fca500debd93c7f97cChris Lattner/// DEFAULT: 193461c77449c772427a0d2559fca500debd93c7f97cChris Lattner/// %tmp = icmp eq i8 %A, 92 193561c77449c772427a0d2559fca500debd93c7f97cChris Lattner/// br label %end 193661c77449c772427a0d2559fca500debd93c7f97cChris Lattner/// end: 193761c77449c772427a0d2559fca500debd93c7f97cChris Lattner/// ... = phi i1 [ true, %entry ], [ %tmp, %DEFAULT ], [ true, %entry ] 193861c77449c772427a0d2559fca500debd93c7f97cChris Lattner/// 193961c77449c772427a0d2559fca500debd93c7f97cChris Lattner/// We prefer to split the edge to 'end' so that there is a true/false entry to 194061c77449c772427a0d2559fca500debd93c7f97cChris Lattner/// the PHI, merging the third icmp into the switch. 1941302ba6fc1cb26248b0d6524fc42c740370926d6dChris Lattnerstatic bool TryToSimplifyUncondBranchWithICmpInIt(ICmpInst *ICI, 1942a23812cfbd23604d2fc103cf232cde8fa270a491Devang Patel const TargetData *TD, 1943a23812cfbd23604d2fc103cf232cde8fa270a491Devang Patel IRBuilder<> &Builder) { 194461c77449c772427a0d2559fca500debd93c7f97cChris Lattner BasicBlock *BB = ICI->getParent(); 1945a23812cfbd23604d2fc103cf232cde8fa270a491Devang Patel 194661c77449c772427a0d2559fca500debd93c7f97cChris Lattner // If the block has any PHIs in it or the icmp has multiple uses, it is too 194761c77449c772427a0d2559fca500debd93c7f97cChris Lattner // complex. 194861c77449c772427a0d2559fca500debd93c7f97cChris Lattner if (isa<PHINode>(BB->begin()) || !ICI->hasOneUse()) return false; 194961c77449c772427a0d2559fca500debd93c7f97cChris Lattner 195061c77449c772427a0d2559fca500debd93c7f97cChris Lattner Value *V = ICI->getOperand(0); 195161c77449c772427a0d2559fca500debd93c7f97cChris Lattner ConstantInt *Cst = cast<ConstantInt>(ICI->getOperand(1)); 195261c77449c772427a0d2559fca500debd93c7f97cChris Lattner 195361c77449c772427a0d2559fca500debd93c7f97cChris Lattner // The pattern we're looking for is where our only predecessor is a switch on 195461c77449c772427a0d2559fca500debd93c7f97cChris Lattner // 'V' and this block is the default case for the switch. In this case we can 195561c77449c772427a0d2559fca500debd93c7f97cChris Lattner // fold the compared value into the switch to simplify things. 195661c77449c772427a0d2559fca500debd93c7f97cChris Lattner BasicBlock *Pred = BB->getSinglePredecessor(); 195761c77449c772427a0d2559fca500debd93c7f97cChris Lattner if (Pred == 0 || !isa<SwitchInst>(Pred->getTerminator())) return false; 195861c77449c772427a0d2559fca500debd93c7f97cChris Lattner 195961c77449c772427a0d2559fca500debd93c7f97cChris Lattner SwitchInst *SI = cast<SwitchInst>(Pred->getTerminator()); 196061c77449c772427a0d2559fca500debd93c7f97cChris Lattner if (SI->getCondition() != V) 196161c77449c772427a0d2559fca500debd93c7f97cChris Lattner return false; 196261c77449c772427a0d2559fca500debd93c7f97cChris Lattner 196361c77449c772427a0d2559fca500debd93c7f97cChris Lattner // If BB is reachable on a non-default case, then we simply know the value of 196461c77449c772427a0d2559fca500debd93c7f97cChris Lattner // V in this block. Substitute it and constant fold the icmp instruction 196561c77449c772427a0d2559fca500debd93c7f97cChris Lattner // away. 196661c77449c772427a0d2559fca500debd93c7f97cChris Lattner if (SI->getDefaultDest() != BB) { 196761c77449c772427a0d2559fca500debd93c7f97cChris Lattner ConstantInt *VVal = SI->findCaseDest(BB); 196861c77449c772427a0d2559fca500debd93c7f97cChris Lattner assert(VVal && "Should have a unique destination value"); 196961c77449c772427a0d2559fca500debd93c7f97cChris Lattner ICI->setOperand(0, VVal); 197061c77449c772427a0d2559fca500debd93c7f97cChris Lattner 1971302ba6fc1cb26248b0d6524fc42c740370926d6dChris Lattner if (Value *V = SimplifyInstruction(ICI, TD)) { 1972302ba6fc1cb26248b0d6524fc42c740370926d6dChris Lattner ICI->replaceAllUsesWith(V); 197361c77449c772427a0d2559fca500debd93c7f97cChris Lattner ICI->eraseFromParent(); 197461c77449c772427a0d2559fca500debd93c7f97cChris Lattner } 197561c77449c772427a0d2559fca500debd93c7f97cChris Lattner // BB is now empty, so it is likely to simplify away. 197661c77449c772427a0d2559fca500debd93c7f97cChris Lattner return SimplifyCFG(BB) | true; 197761c77449c772427a0d2559fca500debd93c7f97cChris Lattner } 197861c77449c772427a0d2559fca500debd93c7f97cChris Lattner 1979abf706703fcbcde8fdc69b1bbdfb34e874813107Chris Lattner // Ok, the block is reachable from the default dest. If the constant we're 1980abf706703fcbcde8fdc69b1bbdfb34e874813107Chris Lattner // comparing exists in one of the other edges, then we can constant fold ICI 1981abf706703fcbcde8fdc69b1bbdfb34e874813107Chris Lattner // and zap it. 1982abf706703fcbcde8fdc69b1bbdfb34e874813107Chris Lattner if (SI->findCaseValue(Cst) != 0) { 1983abf706703fcbcde8fdc69b1bbdfb34e874813107Chris Lattner Value *V; 1984abf706703fcbcde8fdc69b1bbdfb34e874813107Chris Lattner if (ICI->getPredicate() == ICmpInst::ICMP_EQ) 1985abf706703fcbcde8fdc69b1bbdfb34e874813107Chris Lattner V = ConstantInt::getFalse(BB->getContext()); 1986abf706703fcbcde8fdc69b1bbdfb34e874813107Chris Lattner else 1987abf706703fcbcde8fdc69b1bbdfb34e874813107Chris Lattner V = ConstantInt::getTrue(BB->getContext()); 1988abf706703fcbcde8fdc69b1bbdfb34e874813107Chris Lattner 1989abf706703fcbcde8fdc69b1bbdfb34e874813107Chris Lattner ICI->replaceAllUsesWith(V); 1990abf706703fcbcde8fdc69b1bbdfb34e874813107Chris Lattner ICI->eraseFromParent(); 1991abf706703fcbcde8fdc69b1bbdfb34e874813107Chris Lattner // BB is now empty, so it is likely to simplify away. 1992abf706703fcbcde8fdc69b1bbdfb34e874813107Chris Lattner return SimplifyCFG(BB) | true; 1993abf706703fcbcde8fdc69b1bbdfb34e874813107Chris Lattner } 1994abf706703fcbcde8fdc69b1bbdfb34e874813107Chris Lattner 199561c77449c772427a0d2559fca500debd93c7f97cChris Lattner // The use of the icmp has to be in the 'end' block, by the only PHI node in 199661c77449c772427a0d2559fca500debd93c7f97cChris Lattner // the block. 199761c77449c772427a0d2559fca500debd93c7f97cChris Lattner BasicBlock *SuccBlock = BB->getTerminator()->getSuccessor(0); 199861c77449c772427a0d2559fca500debd93c7f97cChris Lattner PHINode *PHIUse = dyn_cast<PHINode>(ICI->use_back()); 199961c77449c772427a0d2559fca500debd93c7f97cChris Lattner if (PHIUse == 0 || PHIUse != &SuccBlock->front() || 200061c77449c772427a0d2559fca500debd93c7f97cChris Lattner isa<PHINode>(++BasicBlock::iterator(PHIUse))) 200161c77449c772427a0d2559fca500debd93c7f97cChris Lattner return false; 200261c77449c772427a0d2559fca500debd93c7f97cChris Lattner 200361c77449c772427a0d2559fca500debd93c7f97cChris Lattner // If the icmp is a SETEQ, then the default dest gets false, the new edge gets 200461c77449c772427a0d2559fca500debd93c7f97cChris Lattner // true in the PHI. 200561c77449c772427a0d2559fca500debd93c7f97cChris Lattner Constant *DefaultCst = ConstantInt::getTrue(BB->getContext()); 200661c77449c772427a0d2559fca500debd93c7f97cChris Lattner Constant *NewCst = ConstantInt::getFalse(BB->getContext()); 200761c77449c772427a0d2559fca500debd93c7f97cChris Lattner 200861c77449c772427a0d2559fca500debd93c7f97cChris Lattner if (ICI->getPredicate() == ICmpInst::ICMP_EQ) 200961c77449c772427a0d2559fca500debd93c7f97cChris Lattner std::swap(DefaultCst, NewCst); 201061c77449c772427a0d2559fca500debd93c7f97cChris Lattner 201161c77449c772427a0d2559fca500debd93c7f97cChris Lattner // Replace ICI (which is used by the PHI for the default value) with true or 201261c77449c772427a0d2559fca500debd93c7f97cChris Lattner // false depending on if it is EQ or NE. 201361c77449c772427a0d2559fca500debd93c7f97cChris Lattner ICI->replaceAllUsesWith(DefaultCst); 201461c77449c772427a0d2559fca500debd93c7f97cChris Lattner ICI->eraseFromParent(); 201561c77449c772427a0d2559fca500debd93c7f97cChris Lattner 201661c77449c772427a0d2559fca500debd93c7f97cChris Lattner // Okay, the switch goes to this block on a default value. Add an edge from 201761c77449c772427a0d2559fca500debd93c7f97cChris Lattner // the switch to the merge point on the compared value. 201861c77449c772427a0d2559fca500debd93c7f97cChris Lattner BasicBlock *NewBB = BasicBlock::Create(BB->getContext(), "switch.edge", 201961c77449c772427a0d2559fca500debd93c7f97cChris Lattner BB->getParent(), BB); 202061c77449c772427a0d2559fca500debd93c7f97cChris Lattner SI->addCase(Cst, NewBB); 202161c77449c772427a0d2559fca500debd93c7f97cChris Lattner 202261c77449c772427a0d2559fca500debd93c7f97cChris Lattner // NewBB branches to the phi block, add the uncond branch and the phi entry. 2023a23812cfbd23604d2fc103cf232cde8fa270a491Devang Patel Builder.SetInsertPoint(NewBB); 2024a23812cfbd23604d2fc103cf232cde8fa270a491Devang Patel Builder.SetCurrentDebugLocation(SI->getDebugLoc()); 2025a23812cfbd23604d2fc103cf232cde8fa270a491Devang Patel Builder.CreateBr(SuccBlock); 202661c77449c772427a0d2559fca500debd93c7f97cChris Lattner PHIUse->addIncoming(NewCst, NewBB); 202761c77449c772427a0d2559fca500debd93c7f97cChris Lattner return true; 202861c77449c772427a0d2559fca500debd93c7f97cChris Lattner} 202961c77449c772427a0d2559fca500debd93c7f97cChris Lattner 203097fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner/// SimplifyBranchOnICmpChain - The specified branch is a conditional branch. 203197fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner/// Check to see if it is branching on an or/and chain of icmp instructions, and 203297fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner/// fold it into a switch instruction if so. 203302dd5418d29c2a43f225df887923e144e12e7ec6Devang Patelstatic bool SimplifyBranchOnICmpChain(BranchInst *BI, const TargetData *TD, 203402dd5418d29c2a43f225df887923e144e12e7ec6Devang Patel IRBuilder<> &Builder) { 203597fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner Instruction *Cond = dyn_cast<Instruction>(BI->getCondition()); 203697fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner if (Cond == 0) return false; 203797fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner 203897fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner 203997fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner // Change br (X == 0 | X == 1), T, F into a switch instruction. 204097fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner // If this is a bunch of seteq's or'd together, or if it's a bunch of 204197fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner // 'setne's and'ed together, collect them. 204297fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner Value *CompVal = 0; 204397fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner std::vector<ConstantInt*> Values; 204497fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner bool TrueWhenEqual = true; 204597fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner Value *ExtraCase = 0; 204633828bcb24176aae72afac0e4953e4b7f9560ef1Benjamin Kramer unsigned UsedICmps = 0; 204797fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner 204897fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner if (Cond->getOpcode() == Instruction::Or) { 204933828bcb24176aae72afac0e4953e4b7f9560ef1Benjamin Kramer CompVal = GatherConstantCompares(Cond, Values, ExtraCase, TD, true, 205033828bcb24176aae72afac0e4953e4b7f9560ef1Benjamin Kramer UsedICmps); 205197fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner } else if (Cond->getOpcode() == Instruction::And) { 205233828bcb24176aae72afac0e4953e4b7f9560ef1Benjamin Kramer CompVal = GatherConstantCompares(Cond, Values, ExtraCase, TD, false, 205333828bcb24176aae72afac0e4953e4b7f9560ef1Benjamin Kramer UsedICmps); 205497fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner TrueWhenEqual = false; 205597fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner } 205697fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner 205797fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner // If we didn't have a multiply compared value, fail. 205897fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner if (CompVal == 0) return false; 205997fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner 206033828bcb24176aae72afac0e4953e4b7f9560ef1Benjamin Kramer // Avoid turning single icmps into a switch. 206133828bcb24176aae72afac0e4953e4b7f9560ef1Benjamin Kramer if (UsedICmps <= 1) 206233828bcb24176aae72afac0e4953e4b7f9560ef1Benjamin Kramer return false; 206333828bcb24176aae72afac0e4953e4b7f9560ef1Benjamin Kramer 206497fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner // There might be duplicate constants in the list, which the switch 206597fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner // instruction can't handle, remove them now. 206697fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner array_pod_sort(Values.begin(), Values.end(), ConstantIntSortPredicate); 206797fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner Values.erase(std::unique(Values.begin(), Values.end()), Values.end()); 206897fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner 206997fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner // If Extra was used, we require at least two switch values to do the 207097fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner // transformation. A switch with one value is just an cond branch. 207197fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner if (ExtraCase && Values.size() < 2) return false; 207297fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner 207397fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner // Figure out which block is which destination. 207497fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner BasicBlock *DefaultBB = BI->getSuccessor(1); 207597fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner BasicBlock *EdgeBB = BI->getSuccessor(0); 207697fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner if (!TrueWhenEqual) std::swap(DefaultBB, EdgeBB); 207797fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner 207897fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner BasicBlock *BB = BI->getParent(); 207997fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner 2080302ba6fc1cb26248b0d6524fc42c740370926d6dChris Lattner DEBUG(dbgs() << "Converting 'icmp' chain with " << Values.size() 2081117f8cffc5499217ff8824eb0d6a0f6b1b78d96eChris Lattner << " cases into SWITCH. BB is:\n" << *BB); 2082117f8cffc5499217ff8824eb0d6a0f6b1b78d96eChris Lattner 208397fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner // If there are any extra values that couldn't be folded into the switch 208497fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner // then we evaluate them with an explicit branch first. Split the block 208597fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner // right before the condbr to handle it. 208697fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner if (ExtraCase) { 208797fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner BasicBlock *NewBB = BB->splitBasicBlock(BI, "switch.early.test"); 208897fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner // Remove the uncond branch added to the old block. 208997fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner TerminatorInst *OldTI = BB->getTerminator(); 209002dd5418d29c2a43f225df887923e144e12e7ec6Devang Patel Builder.SetInsertPoint(OldTI); 209102dd5418d29c2a43f225df887923e144e12e7ec6Devang Patel 2092117f8cffc5499217ff8824eb0d6a0f6b1b78d96eChris Lattner if (TrueWhenEqual) 209302dd5418d29c2a43f225df887923e144e12e7ec6Devang Patel Builder.CreateCondBr(ExtraCase, EdgeBB, NewBB); 2094117f8cffc5499217ff8824eb0d6a0f6b1b78d96eChris Lattner else 209502dd5418d29c2a43f225df887923e144e12e7ec6Devang Patel Builder.CreateCondBr(ExtraCase, NewBB, EdgeBB); 2096117f8cffc5499217ff8824eb0d6a0f6b1b78d96eChris Lattner 209797fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner OldTI->eraseFromParent(); 209897bd89ece3fff29ab7e0eaa38f85183abd962f42Chris Lattner 209997bd89ece3fff29ab7e0eaa38f85183abd962f42Chris Lattner // If there are PHI nodes in EdgeBB, then we need to add a new entry to them 210097bd89ece3fff29ab7e0eaa38f85183abd962f42Chris Lattner // for the edge we just added. 21016de0a28dfb84095ebd7775f371dd4085cf955076Chris Lattner AddPredecessorToBlock(EdgeBB, BB, NewBB); 2102302ba6fc1cb26248b0d6524fc42c740370926d6dChris Lattner 2103302ba6fc1cb26248b0d6524fc42c740370926d6dChris Lattner DEBUG(dbgs() << " ** 'icmp' chain unhandled condition: " << *ExtraCase 2104302ba6fc1cb26248b0d6524fc42c740370926d6dChris Lattner << "\nEXTRABB = " << *BB); 210597fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner BB = NewBB; 210697fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner } 210702dd5418d29c2a43f225df887923e144e12e7ec6Devang Patel 210802dd5418d29c2a43f225df887923e144e12e7ec6Devang Patel Builder.SetInsertPoint(BI); 210997fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner // Convert pointer to int before we switch. 211097fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner if (CompVal->getType()->isPointerTy()) { 211197fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner assert(TD && "Cannot switch on pointer without TargetData"); 211202dd5418d29c2a43f225df887923e144e12e7ec6Devang Patel CompVal = Builder.CreatePtrToInt(CompVal, 211302dd5418d29c2a43f225df887923e144e12e7ec6Devang Patel TD->getIntPtrType(CompVal->getContext()), 211402dd5418d29c2a43f225df887923e144e12e7ec6Devang Patel "magicptr"); 211597fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner } 211697fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner 211797fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner // Create the new switch instruction now. 211802dd5418d29c2a43f225df887923e144e12e7ec6Devang Patel SwitchInst *New = Builder.CreateSwitch(CompVal, DefaultBB, Values.size()); 2119d80e8ed2fa20c7ad51af49c3b2650525edbdcd08Devang Patel 212097fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner // Add all of the 'cases' to the switch instruction. 212197fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner for (unsigned i = 0, e = Values.size(); i != e; ++i) 212297fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner New->addCase(Values[i], EdgeBB); 212397fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner 212497fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner // We added edges from PI to the EdgeBB. As such, if there were any 212597fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner // PHI nodes in EdgeBB, they need entries to be added corresponding to 212697fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner // the number of edges added. 212797fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner for (BasicBlock::iterator BBI = EdgeBB->begin(); 212897fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner isa<PHINode>(BBI); ++BBI) { 212997fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner PHINode *PN = cast<PHINode>(BBI); 213097fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner Value *InVal = PN->getIncomingValueForBlock(BB); 213197fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner for (unsigned i = 0, e = Values.size()-1; i != e; ++i) 213297fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner PN->addIncoming(InVal, BB); 213397fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner } 213497fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner 213597fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner // Erase the old branch instruction. 213697fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner EraseTerminatorInstAndDCECond(BI); 2137117f8cffc5499217ff8824eb0d6a0f6b1b78d96eChris Lattner 2138302ba6fc1cb26248b0d6524fc42c740370926d6dChris Lattner DEBUG(dbgs() << " ** 'icmp' chain result is:\n" << *BB << '\n'); 213997fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner return true; 214097fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner} 214197fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner 2142ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sandsbool SimplifyCFGOpt::SimplifyResume(ResumeInst *RI, IRBuilder<> &Builder) { 2143ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands // If this is a trivial landing pad that just continues unwinding the caught 2144ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands // exception then zap the landing pad, turning its invokes into calls. 2145ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands BasicBlock *BB = RI->getParent(); 2146ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands LandingPadInst *LPInst = dyn_cast<LandingPadInst>(BB->getFirstNonPHI()); 2147ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands if (RI->getValue() != LPInst) 2148ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands // Not a landing pad, or the resume is not unwinding the exception that 2149ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands // caused control to branch here. 2150ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands return false; 2151ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands 2152ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands // Check that there are no other instructions except for debug intrinsics. 2153ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands BasicBlock::iterator I = LPInst, E = RI; 2154ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands while (++I != E) 2155ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands if (!isa<DbgInfoIntrinsic>(I)) 2156ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands return false; 2157ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands 2158ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands // Turn all invokes that unwind here into calls and delete the basic block. 2159ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands for (pred_iterator PI = pred_begin(BB), PE = pred_end(BB); PI != PE;) { 2160ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands InvokeInst *II = cast<InvokeInst>((*PI++)->getTerminator()); 2161ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands SmallVector<Value*, 8> Args(II->op_begin(), II->op_end() - 3); 2162ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands // Insert a call instruction before the invoke. 2163ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands CallInst *Call = CallInst::Create(II->getCalledValue(), Args, "", II); 2164ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands Call->takeName(II); 2165ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands Call->setCallingConv(II->getCallingConv()); 2166ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands Call->setAttributes(II->getAttributes()); 2167ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands Call->setDebugLoc(II->getDebugLoc()); 2168ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands 2169ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands // Anything that used the value produced by the invoke instruction now uses 2170ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands // the value produced by the call instruction. Note that we do this even 2171ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands // for void functions and calls with no uses so that the callgraph edge is 2172ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands // updated. 2173ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands II->replaceAllUsesWith(Call); 2174ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands BB->removePredecessor(II->getParent()); 2175ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands 2176ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands // Insert a branch to the normal destination right before the invoke. 2177ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands BranchInst::Create(II->getNormalDest(), II); 2178ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands 2179ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands // Finally, delete the invoke instruction! 2180ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands II->eraseFromParent(); 2181ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands } 2182ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands 2183ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands // The landingpad is now unreachable. Zap it. 2184ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands BB->eraseFromParent(); 2185ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands return true; 2186ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands} 2187ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands 2188176ec40cb18c51c14fccbb38ee0db5deafb6baa9Devang Patelbool SimplifyCFGOpt::SimplifyReturn(ReturnInst *RI, IRBuilder<> &Builder) { 21893d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BasicBlock *BB = RI->getParent(); 21903d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (!BB->getFirstNonPHIOrDbg()->isTerminator()) return false; 21913d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 21923d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // Find predecessors that end with branches. 21933d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner SmallVector<BasicBlock*, 8> UncondBranchPreds; 21943d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner SmallVector<BranchInst*, 8> CondBranchPreds; 21953d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI) { 21963d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BasicBlock *P = *PI; 21973d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner TerminatorInst *PTI = P->getTerminator(); 21983d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (BranchInst *BI = dyn_cast<BranchInst>(PTI)) { 21993d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (BI->isUnconditional()) 22003d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner UncondBranchPreds.push_back(P); 22013d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner else 22023d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner CondBranchPreds.push_back(BI); 22033d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } 22043d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } 22053d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 22063d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // If we found some, do the transformation! 2207c3f507f98a0747bd256e1c13536060b6fc5c4b62Evan Cheng if (!UncondBranchPreds.empty() && DupRet) { 22083d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner while (!UncondBranchPreds.empty()) { 22093d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BasicBlock *Pred = UncondBranchPreds.pop_back_val(); 22103d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner DEBUG(dbgs() << "FOLDING: " << *BB 22113d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner << "INTO UNCOND BRANCH PRED: " << *Pred); 2212c3f507f98a0747bd256e1c13536060b6fc5c4b62Evan Cheng (void)FoldReturnIntoUncondBranch(RI, BB, Pred); 22133d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } 22143d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 22153d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // If we eliminated all predecessors of the block, delete the block now. 22163d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (pred_begin(BB) == pred_end(BB)) 22173d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // We know there are no successors, so just nuke the block. 22183d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BB->eraseFromParent(); 22193d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 222001d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner return true; 222101d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner } 22223d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 22233d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // Check out all of the conditional branches going to this return 22243d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // instruction. If any of them just select between returns, change the 22253d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // branch itself into a select/return pair. 22263d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner while (!CondBranchPreds.empty()) { 22273d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BranchInst *BI = CondBranchPreds.pop_back_val(); 22283d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 22293d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // Check to see if the non-BB successor is also a return block. 22303d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (isa<ReturnInst>(BI->getSuccessor(0)->getTerminator()) && 22313d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner isa<ReturnInst>(BI->getSuccessor(1)->getTerminator()) && 2232176ec40cb18c51c14fccbb38ee0db5deafb6baa9Devang Patel SimplifyCondBranchToTwoReturns(BI, Builder)) 22333d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner return true; 22343d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } 22353d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner return false; 22363d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner} 223701d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner 2238d46ba26a6b513086ad575e5db0069b03d41fca13Devang Patelbool SimplifyCFGOpt::SimplifyUnwind(UnwindInst *UI, IRBuilder<> &Builder) { 22393d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // Check to see if the first instruction in this block is just an unwind. 22403d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // If so, replace any invoke instructions which use this as an exception 22413d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // destination with call instructions. 22423d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BasicBlock *BB = UI->getParent(); 22433d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (!BB->getFirstNonPHIOrDbg()->isTerminator()) return false; 22442c63566e406974caa70ee27f35af28112e80f951Dan Gohman 22453d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner bool Changed = false; 22463d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner SmallVector<BasicBlock*, 8> Preds(pred_begin(BB), pred_end(BB)); 22473d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner while (!Preds.empty()) { 22483d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BasicBlock *Pred = Preds.back(); 22493d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner InvokeInst *II = dyn_cast<InvokeInst>(Pred->getTerminator()); 22503d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (II && II->getUnwindDest() == BB) { 22513d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // Insert a new branch instruction before the invoke, because this 22523d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // is now a fall through. 2253d46ba26a6b513086ad575e5db0069b03d41fca13Devang Patel Builder.SetInsertPoint(II); 2254d46ba26a6b513086ad575e5db0069b03d41fca13Devang Patel BranchInst *BI = Builder.CreateBr(II->getNormalDest()); 22553d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner Pred->getInstList().remove(II); // Take out of symbol table 22563d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 22573d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // Insert the call now. 22583d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner SmallVector<Value*,8> Args(II->op_begin(), II->op_end()-3); 2259d46ba26a6b513086ad575e5db0069b03d41fca13Devang Patel Builder.SetInsertPoint(BI); 2260d46ba26a6b513086ad575e5db0069b03d41fca13Devang Patel CallInst *CI = Builder.CreateCall(II->getCalledValue(), 2261a3efbb15ddd5aa9006564cd79086723640084878Jay Foad Args, II->getName()); 22623d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner CI->setCallingConv(II->getCallingConv()); 22633d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner CI->setAttributes(II->getAttributes()); 22643d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // If the invoke produced a value, the Call now does instead. 22653d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner II->replaceAllUsesWith(CI); 22663d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner delete II; 22673d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner Changed = true; 22683d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } 22693d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 22703d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner Preds.pop_back(); 22713d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } 22723d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 22733d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // If this block is now dead (and isn't the entry block), remove it. 22743d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (pred_begin(BB) == pred_end(BB) && 22753d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BB != &BB->getParent()->getEntryBlock()) { 22763d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // We know there are no successors, so just nuke the block. 22773d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BB->eraseFromParent(); 2278ddb97a2bf1f06d7d1b0a1af8e74c67917b43b606Chris Lattner return true; 22793d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } 2280ddb97a2bf1f06d7d1b0a1af8e74c67917b43b606Chris Lattner 22813d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner return Changed; 22823d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner} 2283882d87d168374ce790621e9ad4d7304b9dff0d78Dan Gohman 22843d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattnerbool SimplifyCFGOpt::SimplifyUnreachable(UnreachableInst *UI) { 22853d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BasicBlock *BB = UI->getParent(); 22863d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 22873d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner bool Changed = false; 22883d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 22893d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // If there are any instructions immediately before the unreachable that can 22903d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // be removed, do so. 22913d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner while (UI != BB->begin()) { 22923d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BasicBlock::iterator BBI = UI; 22933d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner --BBI; 22948176388d65083339efdfa5bee63e620c6bd05aa1Eli Friedman // Do not delete instructions that can have side effects which might cause 22958176388d65083339efdfa5bee63e620c6bd05aa1Eli Friedman // the unreachable to not be reachable; specifically, calls and volatile 22968176388d65083339efdfa5bee63e620c6bd05aa1Eli Friedman // operations may have this effect. 22973d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (isa<CallInst>(BBI) && !isa<DbgInfoIntrinsic>(BBI)) break; 22988176388d65083339efdfa5bee63e620c6bd05aa1Eli Friedman 22998176388d65083339efdfa5bee63e620c6bd05aa1Eli Friedman if (BBI->mayHaveSideEffects()) { 23008176388d65083339efdfa5bee63e620c6bd05aa1Eli Friedman if (StoreInst *SI = dyn_cast<StoreInst>(BBI)) { 23018176388d65083339efdfa5bee63e620c6bd05aa1Eli Friedman if (SI->isVolatile()) 23028176388d65083339efdfa5bee63e620c6bd05aa1Eli Friedman break; 23038176388d65083339efdfa5bee63e620c6bd05aa1Eli Friedman } else if (LoadInst *LI = dyn_cast<LoadInst>(BBI)) { 23048176388d65083339efdfa5bee63e620c6bd05aa1Eli Friedman if (LI->isVolatile()) 23058176388d65083339efdfa5bee63e620c6bd05aa1Eli Friedman break; 23068176388d65083339efdfa5bee63e620c6bd05aa1Eli Friedman } else if (AtomicRMWInst *RMWI = dyn_cast<AtomicRMWInst>(BBI)) { 23078176388d65083339efdfa5bee63e620c6bd05aa1Eli Friedman if (RMWI->isVolatile()) 23088176388d65083339efdfa5bee63e620c6bd05aa1Eli Friedman break; 23098176388d65083339efdfa5bee63e620c6bd05aa1Eli Friedman } else if (AtomicCmpXchgInst *CXI = dyn_cast<AtomicCmpXchgInst>(BBI)) { 23108176388d65083339efdfa5bee63e620c6bd05aa1Eli Friedman if (CXI->isVolatile()) 23118176388d65083339efdfa5bee63e620c6bd05aa1Eli Friedman break; 23128176388d65083339efdfa5bee63e620c6bd05aa1Eli Friedman } else if (!isa<FenceInst>(BBI) && !isa<VAArgInst>(BBI) && 23138176388d65083339efdfa5bee63e620c6bd05aa1Eli Friedman !isa<LandingPadInst>(BBI)) { 23143d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner break; 23158176388d65083339efdfa5bee63e620c6bd05aa1Eli Friedman } 231623b49ba6d55972fdffdfd4ed37edcf067bb60f3cBill Wendling // Note that deleting LandingPad's here is in fact okay, although it 231723b49ba6d55972fdffdfd4ed37edcf067bb60f3cBill Wendling // involves a bit of subtle reasoning. If this inst is a LandingPad, 231823b49ba6d55972fdffdfd4ed37edcf067bb60f3cBill Wendling // all the predecessors of this block will be the unwind edges of Invokes, 231923b49ba6d55972fdffdfd4ed37edcf067bb60f3cBill Wendling // and we can therefore guarantee this block will be erased. 23208176388d65083339efdfa5bee63e620c6bd05aa1Eli Friedman } 23218176388d65083339efdfa5bee63e620c6bd05aa1Eli Friedman 23222adc5b6a17268834b08fda444b1a84550e8c5ae8Eli Friedman // Delete this instruction (any uses are guaranteed to be dead) 23232adc5b6a17268834b08fda444b1a84550e8c5ae8Eli Friedman if (!BBI->use_empty()) 23242adc5b6a17268834b08fda444b1a84550e8c5ae8Eli Friedman BBI->replaceAllUsesWith(UndefValue::get(BBI->getType())); 2325302ba6fc1cb26248b0d6524fc42c740370926d6dChris Lattner BBI->eraseFromParent(); 23263d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner Changed = true; 23273d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } 23283d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 23293d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // If the unreachable instruction is the first in the block, take a gander 23303d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // at all of the predecessors of this instruction, and simplify them. 23313d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (&BB->front() != UI) return Changed; 23323d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 23333d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner SmallVector<BasicBlock*, 8> Preds(pred_begin(BB), pred_end(BB)); 23343d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner for (unsigned i = 0, e = Preds.size(); i != e; ++i) { 23353d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner TerminatorInst *TI = Preds[i]->getTerminator(); 23361aa89a2f91948993a5d535e3d59513af7f3e7dc9Devang Patel IRBuilder<> Builder(TI); 23373d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (BranchInst *BI = dyn_cast<BranchInst>(TI)) { 23383d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (BI->isUnconditional()) { 23393d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (BI->getSuccessor(0) == BB) { 23403d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner new UnreachableInst(TI->getContext(), TI); 23413d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner TI->eraseFromParent(); 23423d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner Changed = true; 23433d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } 23443d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } else { 23453d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (BI->getSuccessor(0) == BB) { 23461aa89a2f91948993a5d535e3d59513af7f3e7dc9Devang Patel Builder.CreateBr(BI->getSuccessor(1)); 23473d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner EraseTerminatorInstAndDCECond(BI); 23483d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } else if (BI->getSuccessor(1) == BB) { 23491aa89a2f91948993a5d535e3d59513af7f3e7dc9Devang Patel Builder.CreateBr(BI->getSuccessor(0)); 23503d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner EraseTerminatorInstAndDCECond(BI); 23513d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner Changed = true; 235207e6e56f57e8781a8d7bc601cc9034a3741d84c2Anton Korobeynikov } 235319831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner } 23543d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } else if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) { 23553d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner for (unsigned i = 1, e = SI->getNumCases(); i != e; ++i) 23563d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (SI->getSuccessor(i) == BB) { 23573d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BB->removePredecessor(SI->getParent()); 23583d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner SI->removeCase(i); 23593d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner --i; --e; 23603d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner Changed = true; 23613d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } 23623d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // If the default value is unreachable, figure out the most popular 23633d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // destination and make it the default. 23643d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (SI->getSuccessor(0) == BB) { 2365b1a6eab655adce4f84a15afa9092e814b9aaabdaEli Friedman std::map<BasicBlock*, std::pair<unsigned, unsigned> > Popularity; 2366b1a6eab655adce4f84a15afa9092e814b9aaabdaEli Friedman for (unsigned i = 1, e = SI->getNumCases(); i != e; ++i) { 2367b1a6eab655adce4f84a15afa9092e814b9aaabdaEli Friedman std::pair<unsigned, unsigned>& entry = 2368b1a6eab655adce4f84a15afa9092e814b9aaabdaEli Friedman Popularity[SI->getSuccessor(i)]; 2369b1a6eab655adce4f84a15afa9092e814b9aaabdaEli Friedman if (entry.first == 0) { 2370b1a6eab655adce4f84a15afa9092e814b9aaabdaEli Friedman entry.first = 1; 2371b1a6eab655adce4f84a15afa9092e814b9aaabdaEli Friedman entry.second = i; 2372b1a6eab655adce4f84a15afa9092e814b9aaabdaEli Friedman } else { 2373b1a6eab655adce4f84a15afa9092e814b9aaabdaEli Friedman entry.first++; 2374b1a6eab655adce4f84a15afa9092e814b9aaabdaEli Friedman } 2375b1a6eab655adce4f84a15afa9092e814b9aaabdaEli Friedman } 2376b1a6eab655adce4f84a15afa9092e814b9aaabdaEli Friedman 23773d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // Find the most popular block. 23783d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner unsigned MaxPop = 0; 2379b1a6eab655adce4f84a15afa9092e814b9aaabdaEli Friedman unsigned MaxIndex = 0; 23803d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BasicBlock *MaxBlock = 0; 2381b1a6eab655adce4f84a15afa9092e814b9aaabdaEli Friedman for (std::map<BasicBlock*, std::pair<unsigned, unsigned> >::iterator 23823d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner I = Popularity.begin(), E = Popularity.end(); I != E; ++I) { 2383b1a6eab655adce4f84a15afa9092e814b9aaabdaEli Friedman if (I->second.first > MaxPop || 2384b1a6eab655adce4f84a15afa9092e814b9aaabdaEli Friedman (I->second.first == MaxPop && MaxIndex > I->second.second)) { 2385b1a6eab655adce4f84a15afa9092e814b9aaabdaEli Friedman MaxPop = I->second.first; 2386b1a6eab655adce4f84a15afa9092e814b9aaabdaEli Friedman MaxIndex = I->second.second; 23873d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner MaxBlock = I->first; 23883d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } 23893d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } 23903d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (MaxBlock) { 23913d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // Make this the new default, allowing us to delete any explicit 23923d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // edges to it. 23933d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner SI->setSuccessor(0, MaxBlock); 23943d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner Changed = true; 2395ffba5821eee7b7a6139f9dfb06b8d306bf344a9dChris Lattner 23963d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // If MaxBlock has phinodes in it, remove MaxPop-1 entries from 23973d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // it. 23983d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (isa<PHINode>(MaxBlock->begin())) 23993d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner for (unsigned i = 0; i != MaxPop-1; ++i) 24003d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner MaxBlock->removePredecessor(SI->getParent()); 24013d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 24023d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner for (unsigned i = 1, e = SI->getNumCases(); i != e; ++i) 24033d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (SI->getSuccessor(i) == MaxBlock) { 24043d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner SI->removeCase(i); 24053d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner --i; --e; 24063d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } 240719831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner } 240819831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner } 24093d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } else if (InvokeInst *II = dyn_cast<InvokeInst>(TI)) { 24103d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (II->getUnwindDest() == BB) { 24113d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // Convert the invoke to a call instruction. This would be a good 24123d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // place to note that the call does not throw though. 24131aa89a2f91948993a5d535e3d59513af7f3e7dc9Devang Patel BranchInst *BI = Builder.CreateBr(II->getNormalDest()); 24143d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner II->removeFromParent(); // Take out of symbol table 24153d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 24163d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // Insert the call now... 24173d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner SmallVector<Value*, 8> Args(II->op_begin(), II->op_end()-3); 24181aa89a2f91948993a5d535e3d59513af7f3e7dc9Devang Patel Builder.SetInsertPoint(BI); 24191aa89a2f91948993a5d535e3d59513af7f3e7dc9Devang Patel CallInst *CI = Builder.CreateCall(II->getCalledValue(), 2420a3efbb15ddd5aa9006564cd79086723640084878Jay Foad Args, II->getName()); 24219a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner CI->setCallingConv(II->getCallingConv()); 24229a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner CI->setAttributes(II->getAttributes()); 24233d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // If the invoke produced a value, the call does now instead. 24249a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner II->replaceAllUsesWith(CI); 24259a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner delete II; 24269a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner Changed = true; 24279a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner } 2428e14ea0804afba2ac5824507571a220d05b0aa21dChris Lattner } 24293d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } 24303d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 24313d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // If this block is now dead, remove it. 24323d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (pred_begin(BB) == pred_end(BB) && 24333d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BB != &BB->getParent()->getEntryBlock()) { 24343d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // We know there are no successors, so just nuke the block. 24353d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BB->eraseFromParent(); 24363d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner return true; 24373d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } 24388e509dd5e81e92a466580ab4022994079952cca9Chris Lattner 24393d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner return Changed; 24403d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner} 24418e509dd5e81e92a466580ab4022994079952cca9Chris Lattner 244256442dfdcf7b07c04b585de5205b9427b1739895Benjamin Kramer/// TurnSwitchRangeIntoICmp - Turns a switch with that contains only a 244356442dfdcf7b07c04b585de5205b9427b1739895Benjamin Kramer/// integer range comparison into a sub, an icmp and a branch. 2444007349dafda47296177fd7481aff9764d4179f42Devang Patelstatic bool TurnSwitchRangeIntoICmp(SwitchInst *SI, IRBuilder<> &Builder) { 244556442dfdcf7b07c04b585de5205b9427b1739895Benjamin Kramer assert(SI->getNumCases() > 2 && "Degenerate switch?"); 2446042b27f40e4b1dcae70c0e98c3b4f5760dd8fa9bBenjamin Kramer 2447042b27f40e4b1dcae70c0e98c3b4f5760dd8fa9bBenjamin Kramer // Make sure all cases point to the same destination and gather the values. 2448042b27f40e4b1dcae70c0e98c3b4f5760dd8fa9bBenjamin Kramer SmallVector<ConstantInt *, 16> Cases; 2449042b27f40e4b1dcae70c0e98c3b4f5760dd8fa9bBenjamin Kramer Cases.push_back(SI->getCaseValue(1)); 2450042b27f40e4b1dcae70c0e98c3b4f5760dd8fa9bBenjamin Kramer for (unsigned I = 2, E = SI->getNumCases(); I != E; ++I) { 2451042b27f40e4b1dcae70c0e98c3b4f5760dd8fa9bBenjamin Kramer if (SI->getSuccessor(I-1) != SI->getSuccessor(I)) 245256442dfdcf7b07c04b585de5205b9427b1739895Benjamin Kramer return false; 2453042b27f40e4b1dcae70c0e98c3b4f5760dd8fa9bBenjamin Kramer Cases.push_back(SI->getCaseValue(I)); 2454042b27f40e4b1dcae70c0e98c3b4f5760dd8fa9bBenjamin Kramer } 2455042b27f40e4b1dcae70c0e98c3b4f5760dd8fa9bBenjamin Kramer assert(Cases.size() == SI->getNumCases()-1 && "Not all cases gathered"); 2456042b27f40e4b1dcae70c0e98c3b4f5760dd8fa9bBenjamin Kramer 2457042b27f40e4b1dcae70c0e98c3b4f5760dd8fa9bBenjamin Kramer // Sort the case values, then check if they form a range we can transform. 2458042b27f40e4b1dcae70c0e98c3b4f5760dd8fa9bBenjamin Kramer array_pod_sort(Cases.begin(), Cases.end(), ConstantIntSortPredicate); 2459042b27f40e4b1dcae70c0e98c3b4f5760dd8fa9bBenjamin Kramer for (unsigned I = 1, E = Cases.size(); I != E; ++I) { 2460042b27f40e4b1dcae70c0e98c3b4f5760dd8fa9bBenjamin Kramer if (Cases[I-1]->getValue() != Cases[I]->getValue()+1) 2461042b27f40e4b1dcae70c0e98c3b4f5760dd8fa9bBenjamin Kramer return false; 2462042b27f40e4b1dcae70c0e98c3b4f5760dd8fa9bBenjamin Kramer } 246356442dfdcf7b07c04b585de5205b9427b1739895Benjamin Kramer 2464042b27f40e4b1dcae70c0e98c3b4f5760dd8fa9bBenjamin Kramer Constant *Offset = ConstantExpr::getNeg(Cases.back()); 246556442dfdcf7b07c04b585de5205b9427b1739895Benjamin Kramer Constant *NumCases = ConstantInt::get(Offset->getType(), SI->getNumCases()-1); 246656442dfdcf7b07c04b585de5205b9427b1739895Benjamin Kramer 246733828bcb24176aae72afac0e4953e4b7f9560ef1Benjamin Kramer Value *Sub = SI->getCondition(); 246833828bcb24176aae72afac0e4953e4b7f9560ef1Benjamin Kramer if (!Offset->isNullValue()) 24691f5812bd995afc97d32061c532aaa0aedbead9ffDevang Patel Sub = Builder.CreateAdd(Sub, Offset, Sub->getName()+".off"); 24701f5812bd995afc97d32061c532aaa0aedbead9ffDevang Patel Value *Cmp = Builder.CreateICmpULT(Sub, NumCases, "switch"); 2471007349dafda47296177fd7481aff9764d4179f42Devang Patel Builder.CreateCondBr(Cmp, SI->getSuccessor(1), SI->getDefaultDest()); 247256442dfdcf7b07c04b585de5205b9427b1739895Benjamin Kramer 247356442dfdcf7b07c04b585de5205b9427b1739895Benjamin Kramer // Prune obsolete incoming values off the successor's PHI nodes. 247456442dfdcf7b07c04b585de5205b9427b1739895Benjamin Kramer for (BasicBlock::iterator BBI = SI->getSuccessor(1)->begin(); 247556442dfdcf7b07c04b585de5205b9427b1739895Benjamin Kramer isa<PHINode>(BBI); ++BBI) { 247656442dfdcf7b07c04b585de5205b9427b1739895Benjamin Kramer for (unsigned I = 0, E = SI->getNumCases()-2; I != E; ++I) 247756442dfdcf7b07c04b585de5205b9427b1739895Benjamin Kramer cast<PHINode>(BBI)->removeIncomingValue(SI->getParent()); 247856442dfdcf7b07c04b585de5205b9427b1739895Benjamin Kramer } 247956442dfdcf7b07c04b585de5205b9427b1739895Benjamin Kramer SI->eraseFromParent(); 248056442dfdcf7b07c04b585de5205b9427b1739895Benjamin Kramer 248156442dfdcf7b07c04b585de5205b9427b1739895Benjamin Kramer return true; 248256442dfdcf7b07c04b585de5205b9427b1739895Benjamin Kramer} 2483d0a203d76f4ef77ae1c392e8e73e2f05b676a5f2Devang Patel 248410fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer/// EliminateDeadSwitchCases - Compute masked bits for the condition of a switch 248510fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer/// and use it to remove dead cases. 248610fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramerstatic bool EliminateDeadSwitchCases(SwitchInst *SI) { 248710fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer Value *Cond = SI->getCondition(); 248810fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer unsigned Bits = cast<IntegerType>(Cond->getType())->getBitWidth(); 248910fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer APInt KnownZero(Bits, 0), KnownOne(Bits, 0); 249010fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer ComputeMaskedBits(Cond, APInt::getAllOnesValue(Bits), KnownZero, KnownOne); 249110fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer 249210fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer // Gather dead cases. 249310fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer SmallVector<ConstantInt*, 8> DeadCases; 249410fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer for (unsigned I = 1, E = SI->getNumCases(); I != E; ++I) { 249510fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer if ((SI->getCaseValue(I)->getValue() & KnownZero) != 0 || 249610fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer (SI->getCaseValue(I)->getValue() & KnownOne) != KnownOne) { 249710fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer DeadCases.push_back(SI->getCaseValue(I)); 249810fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer DEBUG(dbgs() << "SimplifyCFG: switch case '" 249910fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer << SI->getCaseValue(I)->getValue() << "' is dead.\n"); 250010fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer } 250110fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer } 250210fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer 250310fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer // Remove dead cases from the switch. 250410fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer for (unsigned I = 0, E = DeadCases.size(); I != E; ++I) { 250510fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer unsigned Case = SI->findCaseValue(DeadCases[I]); 250610fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer // Prune unused values from PHI nodes. 250710fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer SI->getSuccessor(Case)->removePredecessor(SI->getParent()); 250810fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer SI->removeCase(Case); 250910fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer } 251010fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer 251110fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer return !DeadCases.empty(); 251210fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer} 251310fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer 2514448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg/// FindPHIForConditionForwarding - If BB would be eligible for simplification 2515448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg/// by TryToSimplifyUncondBranchFromEmptyBlock (i.e. it is empty and terminated 2516448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg/// by an unconditional branch), look at the phi node for BB in the successor 2517448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg/// block and see if the incoming value is equal to CaseValue. If so, return 2518448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg/// the phi node, and set PhiIndex to BB's index in the phi node. 2519448da519cca87cbcba620188e1e595dc1f120512Hans Wennborgstatic PHINode *FindPHIForConditionForwarding(ConstantInt *CaseValue, 2520448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg BasicBlock *BB, 2521448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg int *PhiIndex) { 2522448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg if (BB->getFirstNonPHIOrDbg() != BB->getTerminator()) 2523448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg return NULL; // BB must be empty to be a candidate for simplification. 2524448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg if (!BB->getSinglePredecessor()) 2525448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg return NULL; // BB must be dominated by the switch. 2526448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg 2527448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg BranchInst *Branch = dyn_cast<BranchInst>(BB->getTerminator()); 2528448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg if (!Branch || !Branch->isUnconditional()) 2529448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg return NULL; // Terminator must be unconditional branch. 2530448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg 2531448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg BasicBlock *Succ = Branch->getSuccessor(0); 2532448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg 2533448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg BasicBlock::iterator I = Succ->begin(); 2534448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg while (PHINode *PHI = dyn_cast<PHINode>(I++)) { 2535448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg int Idx = PHI->getBasicBlockIndex(BB); 2536448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg assert(Idx >= 0 && "PHI has no entry for predecessor?"); 2537448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg 2538448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg Value *InValue = PHI->getIncomingValue(Idx); 2539448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg if (InValue != CaseValue) continue; 2540448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg 2541448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg *PhiIndex = Idx; 2542448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg return PHI; 2543448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg } 2544448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg 2545448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg return NULL; 2546448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg} 2547448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg 2548448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg/// ForwardSwitchConditionToPHI - Try to forward the condition of a switch 2549448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg/// instruction to a phi node dominated by the switch, if that would mean that 2550448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg/// some of the destination blocks of the switch can be folded away. 2551448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg/// Returns true if a change is made. 2552448da519cca87cbcba620188e1e595dc1f120512Hans Wennborgstatic bool ForwardSwitchConditionToPHI(SwitchInst *SI) { 2553448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg typedef DenseMap<PHINode*, SmallVector<int,4> > ForwardingNodesMap; 2554448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg ForwardingNodesMap ForwardingNodes; 2555448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg 2556448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg for (unsigned I = 1; I < SI->getNumCases(); ++I) { // 0 is the default case. 2557448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg ConstantInt *CaseValue = SI->getCaseValue(I); 2558448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg BasicBlock *CaseDest = SI->getSuccessor(I); 2559448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg 2560448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg int PhiIndex; 2561448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg PHINode *PHI = FindPHIForConditionForwarding(CaseValue, CaseDest, 2562448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg &PhiIndex); 2563448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg if (!PHI) continue; 2564448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg 2565448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg ForwardingNodes[PHI].push_back(PhiIndex); 2566448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg } 2567448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg 2568448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg bool Changed = false; 2569448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg 2570448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg for (ForwardingNodesMap::iterator I = ForwardingNodes.begin(), 2571448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg E = ForwardingNodes.end(); I != E; ++I) { 2572448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg PHINode *Phi = I->first; 2573448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg SmallVector<int,4> &Indexes = I->second; 2574448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg 2575448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg if (Indexes.size() < 2) continue; 2576448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg 2577448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg for (size_t I = 0, E = Indexes.size(); I != E; ++I) 2578448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg Phi->setIncomingValue(Indexes[I], SI->getCondition()); 2579448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg Changed = true; 2580448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg } 2581448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg 2582448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg return Changed; 2583448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg} 2584448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg 2585007349dafda47296177fd7481aff9764d4179f42Devang Patelbool SimplifyCFGOpt::SimplifySwitch(SwitchInst *SI, IRBuilder<> &Builder) { 25863d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // If this switch is too complex to want to look at, ignore it. 25873d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (!isValueEqualityComparison(SI)) 25883d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner return false; 2589e67fa05036f634a4ec1e0893033c89250eb58954Chris Lattner 25903d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BasicBlock *BB = SI->getParent(); 25913d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 25923d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // If we only have one predecessor, and if it is a branch on this value, 25933d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // see if that predecessor totally determines the outcome of this switch. 25943d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (BasicBlock *OnlyPred = BB->getSinglePredecessor()) 2595007349dafda47296177fd7481aff9764d4179f42Devang Patel if (SimplifyEqualityComparisonWithOnlyPredecessor(SI, OnlyPred, Builder)) 2596021c9d3bd41bc446ef0860c05a073e32afa5e20fChris Lattner return SimplifyCFG(BB) | true; 2597f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel 2598f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel Value *Cond = SI->getCondition(); 2599f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel if (SelectInst *Select = dyn_cast<SelectInst>(Cond)) 2600f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel if (SimplifySwitchOnSelect(SI, Select)) 2601f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel return SimplifyCFG(BB) | true; 2602f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel 26033d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // If the block only contains the switch, see if we can fold the block 26043d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // away into any preds. 26053d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BasicBlock::iterator BBI = BB->begin(); 26063d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // Ignore dbg intrinsics. 26073d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner while (isa<DbgInfoIntrinsic>(BBI)) 26083d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner ++BBI; 26093d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (SI == &*BBI) 2610b55d924b1e33341d08b1bead78e86fce56617784Devang Patel if (FoldValueComparisonIntoPredecessors(SI, Builder)) 2611021c9d3bd41bc446ef0860c05a073e32afa5e20fChris Lattner return SimplifyCFG(BB) | true; 261256442dfdcf7b07c04b585de5205b9427b1739895Benjamin Kramer 261356442dfdcf7b07c04b585de5205b9427b1739895Benjamin Kramer // Try to transform the switch into an icmp and a branch. 2614007349dafda47296177fd7481aff9764d4179f42Devang Patel if (TurnSwitchRangeIntoICmp(SI, Builder)) 261556442dfdcf7b07c04b585de5205b9427b1739895Benjamin Kramer return SimplifyCFG(BB) | true; 261610fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer 261710fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer // Remove unreachable cases. 261810fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer if (EliminateDeadSwitchCases(SI)) 261910fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer return SimplifyCFG(BB) | true; 262010fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer 2621448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg if (ForwardSwitchConditionToPHI(SI)) 2622448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg return SimplifyCFG(BB) | true; 2623448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg 26243d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner return false; 26253d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner} 26263d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 26273d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattnerbool SimplifyCFGOpt::SimplifyIndirectBr(IndirectBrInst *IBI) { 26283d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BasicBlock *BB = IBI->getParent(); 26293d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner bool Changed = false; 26303d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 26313d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // Eliminate redundant destinations. 26323d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner SmallPtrSet<Value *, 8> Succs; 26333d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner for (unsigned i = 0, e = IBI->getNumDestinations(); i != e; ++i) { 26343d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BasicBlock *Dest = IBI->getDestination(i); 26353d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (!Dest->hasAddressTaken() || !Succs.insert(Dest)) { 26363d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner Dest->removePredecessor(BB); 26373d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner IBI->removeDestination(i); 26383d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner --i; --e; 2639698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner Changed = true; 2640698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner } 26413d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } 2642698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner 26433d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (IBI->getNumDestinations() == 0) { 26443d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // If the indirectbr has no successors, change it to unreachable. 26453d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner new UnreachableInst(IBI->getContext(), IBI); 26463d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner EraseTerminatorInstAndDCECond(IBI); 26473d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner return true; 26483d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } 26493d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 26503d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (IBI->getNumDestinations() == 1) { 26513d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // If the indirectbr has one successor, change it to a direct branch. 26523d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BranchInst::Create(IBI->getDestination(0), IBI); 26533d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner EraseTerminatorInstAndDCECond(IBI); 26543d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner return true; 26553d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } 26563d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 26573d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (SelectInst *SI = dyn_cast<SelectInst>(IBI->getAddress())) { 26583d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (SimplifyIndirectBrOnSelect(IBI, SI)) 26593d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner return SimplifyCFG(BB) | true; 26603d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } 26613d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner return Changed; 26623d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner} 2663698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner 2664a23812cfbd23604d2fc103cf232cde8fa270a491Devang Patelbool SimplifyCFGOpt::SimplifyUncondBranch(BranchInst *BI, IRBuilder<> &Builder){ 26653d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BasicBlock *BB = BI->getParent(); 26663d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 26673d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // If the Terminator is the only non-phi instruction, simplify the block. 266877a2c372face15a302f4c9e5cb9acc035b8b3bd3Rafael Espindola BasicBlock::iterator I = BB->getFirstNonPHIOrDbgOrLifetime(); 26693d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (I->isTerminator() && BB != &BB->getParent()->getEntryBlock() && 26703d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner TryToSimplifyUncondBranchFromEmptyBlock(BB)) 26713d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner return true; 26723d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 26733d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // If the only instruction in the block is a seteq/setne comparison 26743d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // against a constant, try to simplify the block. 26753d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (ICmpInst *ICI = dyn_cast<ICmpInst>(I)) 26763d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (ICI->isEquality() && isa<ConstantInt>(ICI->getOperand(1))) { 26773d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner for (++I; isa<DbgInfoIntrinsic>(I); ++I) 26783d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner ; 2679a23812cfbd23604d2fc103cf232cde8fa270a491Devang Patel if (I->isTerminator() 2680a23812cfbd23604d2fc103cf232cde8fa270a491Devang Patel && TryToSimplifyUncondBranchWithICmpInIt(ICI, TD, Builder)) 2681698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner return true; 2682698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner } 26833d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 26843d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner return false; 26853d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner} 2686e2c6d131d12c779a410740e0a90545def75e0f48Dan Gohman 26873d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 2688007349dafda47296177fd7481aff9764d4179f42Devang Patelbool SimplifyCFGOpt::SimplifyCondBranch(BranchInst *BI, IRBuilder<> &Builder) { 26893d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BasicBlock *BB = BI->getParent(); 26903d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 26913d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // Conditional branch 26923d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (isValueEqualityComparison(BI)) { 26933d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // If we only have one predecessor, and if it is a branch on this value, 26943d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // see if that predecessor totally determines the outcome of this 26953d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // switch. 26963d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (BasicBlock *OnlyPred = BB->getSinglePredecessor()) 2697007349dafda47296177fd7481aff9764d4179f42Devang Patel if (SimplifyEqualityComparisonWithOnlyPredecessor(BI, OnlyPred, Builder)) 26983d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner return SimplifyCFG(BB) | true; 26993d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 27003d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // This block must be empty, except for the setcond inst, if it exists. 27013d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // Ignore dbg intrinsics. 27023d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BasicBlock::iterator I = BB->begin(); 27033d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // Ignore dbg intrinsics. 27043d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner while (isa<DbgInfoIntrinsic>(I)) 27053d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner ++I; 27063d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (&*I == BI) { 2707b55d924b1e33341d08b1bead78e86fce56617784Devang Patel if (FoldValueComparisonIntoPredecessors(BI, Builder)) 27083d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner return SimplifyCFG(BB) | true; 27093d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } else if (&*I == cast<Instruction>(BI->getCondition())){ 27103d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner ++I; 27113d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // Ignore dbg intrinsics. 27123d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner while (isa<DbgInfoIntrinsic>(I)) 27133d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner ++I; 2714b55d924b1e33341d08b1bead78e86fce56617784Devang Patel if (&*I == BI && FoldValueComparisonIntoPredecessors(BI, Builder)) 27153d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner return SimplifyCFG(BB) | true; 27163d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } 27173d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } 27183d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 27193d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // Try to turn "br (X == 0 | X == 1), T, F" into a switch instruction. 272002dd5418d29c2a43f225df887923e144e12e7ec6Devang Patel if (SimplifyBranchOnICmpChain(BI, TD, Builder)) 27213d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner return true; 27223d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 27233d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // We have a conditional branch to two blocks that are only reachable 27243d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // from BI. We know that the condbr dominates the two blocks, so see if 27253d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // there is any identical code in the "then" and "else" blocks. If so, we 27263d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // can hoist it up to the branching block. 27273d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (BI->getSuccessor(0)->getSinglePredecessor() != 0) { 27283d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (BI->getSuccessor(1)->getSinglePredecessor() != 0) { 2729216dde91d1def3e08002d6251e11f3dfa5cb3656Rafael Espindola if (HoistThenElseCodeToIf(BI)) 27307ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel return SimplifyCFG(BB) | true; 27313d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } else { 27323d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // If Successor #1 has multiple preds, we may be able to conditionally 27333d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // execute Successor #0 if it branches to successor #1. 27343d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner TerminatorInst *Succ0TI = BI->getSuccessor(0)->getTerminator(); 27353d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (Succ0TI->getNumSuccessors() == 1 && 27363d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner Succ0TI->getSuccessor(0) == BI->getSuccessor(1)) 2737216dde91d1def3e08002d6251e11f3dfa5cb3656Rafael Espindola if (SpeculativelyExecuteBB(BI, BI->getSuccessor(0))) 27383d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner return SimplifyCFG(BB) | true; 2739e2c6d131d12c779a410740e0a90545def75e0f48Dan Gohman } 27403d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } else if (BI->getSuccessor(1)->getSinglePredecessor() != 0) { 27413d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // If Successor #0 has multiple preds, we may be able to conditionally 27423d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // execute Successor #1 if it branches to successor #0. 27433d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner TerminatorInst *Succ1TI = BI->getSuccessor(1)->getTerminator(); 27443d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (Succ1TI->getNumSuccessors() == 1 && 27453d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner Succ1TI->getSuccessor(0) == BI->getSuccessor(0)) 2746216dde91d1def3e08002d6251e11f3dfa5cb3656Rafael Espindola if (SpeculativelyExecuteBB(BI, BI->getSuccessor(1))) 27473d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner return SimplifyCFG(BB) | true; 274819831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner } 27493d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 27503d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // If this is a branch on a phi node in the current block, thread control 27513d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // through this block if any PHI node entries are constants. 27523d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (PHINode *PN = dyn_cast<PHINode>(BI->getCondition())) 27533d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (PN->getParent() == BI->getParent()) 2754302ba6fc1cb26248b0d6524fc42c740370926d6dChris Lattner if (FoldCondBranchOnPHI(BI, TD)) 27553d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner return SimplifyCFG(BB) | true; 27563d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 27573d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // If this basic block is ONLY a setcc and a branch, and if a predecessor 27583d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // branches to us and one of our successors, fold the setcc into the 27593d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // predecessor and use logical operations to pick the right destination. 27603d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (FoldBranchToCommonDest(BI)) 27612d9220e8f5b45390d64e943fa4eef1562b87f04bOwen Anderson return SimplifyCFG(BB) | true; 27623d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 27633d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // Scan predecessor blocks for conditional branches. 27643d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI) 27653d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (BranchInst *PBI = dyn_cast<BranchInst>((*PI)->getTerminator())) 27663d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (PBI != BI && PBI->isConditional()) 27673d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (SimplifyCondBranchToCondBranch(PBI, BI)) 27683d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner return SimplifyCFG(BB) | true; 27693d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 27703d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner return false; 27713d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner} 27723d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 277398d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer/// Check if passing a value to an instruction will cause undefined behavior. 277498d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramerstatic bool passingValueIsAlwaysUndefined(Value *V, Instruction *I) { 277598d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer Constant *C = dyn_cast<Constant>(V); 277698d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer if (!C) 277798d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer return false; 277898d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer 27799bb5488dbd152de41ffcaedccf94bfc43b069becBenjamin Kramer if (!I->hasOneUse()) // Only look at single-use instructions, for compile time 278098d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer return false; 278198d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer 278298d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer if (C->isNullValue()) { 278398d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer Instruction *Use = I->use_back(); 278498d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer 278598d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer // Now make sure that there are no instructions in between that can alter 278698d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer // control flow (eg. calls) 278798d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer for (BasicBlock::iterator i = ++BasicBlock::iterator(I); &*i != Use; ++i) 27889bb5488dbd152de41ffcaedccf94bfc43b069becBenjamin Kramer if (i == I->getParent()->end() || i->mayHaveSideEffects()) 278998d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer return false; 279098d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer 279198d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer // Look through GEPs. A load from a GEP derived from NULL is still undefined 279298d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Use)) 279398d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer if (GEP->getPointerOperand() == I) 279498d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer return passingValueIsAlwaysUndefined(V, GEP); 279598d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer 279698d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer // Look through bitcasts. 279798d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer if (BitCastInst *BC = dyn_cast<BitCastInst>(Use)) 279898d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer return passingValueIsAlwaysUndefined(V, BC); 279998d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer 28009bb5488dbd152de41ffcaedccf94bfc43b069becBenjamin Kramer // Load from null is undefined. 28019bb5488dbd152de41ffcaedccf94bfc43b069becBenjamin Kramer if (LoadInst *LI = dyn_cast<LoadInst>(Use)) 28029bb5488dbd152de41ffcaedccf94bfc43b069becBenjamin Kramer return LI->getPointerAddressSpace() == 0; 280398d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer 28049bb5488dbd152de41ffcaedccf94bfc43b069becBenjamin Kramer // Store to null is undefined. 28059bb5488dbd152de41ffcaedccf94bfc43b069becBenjamin Kramer if (StoreInst *SI = dyn_cast<StoreInst>(Use)) 28069bb5488dbd152de41ffcaedccf94bfc43b069becBenjamin Kramer return SI->getPointerAddressSpace() == 0 && SI->getPointerOperand() == I; 280798d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer } 280898d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer return false; 280998d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer} 281098d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer 281198d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer/// If BB has an incoming value that will always trigger undefined behavior 281298d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer/// (eg. null pointer derefence), remove the branch leading here. 281398d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramerstatic bool removeUndefIntroducingPredecessor(BasicBlock *BB) { 281498d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer for (BasicBlock::iterator i = BB->begin(); 281598d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer PHINode *PHI = dyn_cast<PHINode>(i); ++i) 281698d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer for (unsigned i = 0, e = PHI->getNumIncomingValues(); i != e; ++i) 281798d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer if (passingValueIsAlwaysUndefined(PHI->getIncomingValue(i), PHI)) { 281898d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer TerminatorInst *T = PHI->getIncomingBlock(i)->getTerminator(); 281998d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer IRBuilder<> Builder(T); 282098d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer if (BranchInst *BI = dyn_cast<BranchInst>(T)) { 282198d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer BB->removePredecessor(PHI->getIncomingBlock(i)); 282298d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer // Turn uncoditional branches into unreachables and remove the dead 282398d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer // destination from conditional branches. 282498d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer if (BI->isUnconditional()) 282598d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer Builder.CreateUnreachable(); 282698d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer else 282798d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer Builder.CreateBr(BI->getSuccessor(0) == BB ? BI->getSuccessor(1) : 282898d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer BI->getSuccessor(0)); 282998d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer BI->eraseFromParent(); 283098d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer return true; 283198d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer } 283298d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer // TODO: SwitchInst. 283398d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer } 283498d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer 283598d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer return false; 283698d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer} 283798d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer 28383d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattnerbool SimplifyCFGOpt::run(BasicBlock *BB) { 28393d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner bool Changed = false; 28403d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 2841302ba6fc1cb26248b0d6524fc42c740370926d6dChris Lattner assert(BB && BB->getParent() && "Block not embedded in function!"); 28423d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner assert(BB->getTerminator() && "Degenerate basic block encountered!"); 28433d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 28443d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // Remove basic blocks that have no predecessors (except the entry block)... 28453d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // or that just have themself as a predecessor. These are unreachable. 2846302ba6fc1cb26248b0d6524fc42c740370926d6dChris Lattner if ((pred_begin(BB) == pred_end(BB) && 2847302ba6fc1cb26248b0d6524fc42c740370926d6dChris Lattner BB != &BB->getParent()->getEntryBlock()) || 28483d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BB->getSinglePredecessor() == BB) { 28493d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner DEBUG(dbgs() << "Removing BB: \n" << *BB); 28503d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner DeleteDeadBlock(BB); 28513d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner return true; 28523d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } 28533d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 28543d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // Check to see if we can constant propagate this terminator instruction 28553d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // away... 28565649ba70fb39f2fda4791d255ae8bb373071874fFrits van Bommel Changed |= ConstantFoldTerminator(BB, true); 28573d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 28583d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // Check for and eliminate duplicate PHI nodes in this block. 28593d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner Changed |= EliminateDuplicatePHINodes(BB); 28603d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 286198d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer // Check for and remove branches that will always cause undefined behavior. 286298d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer Changed |= removeUndefIntroducingPredecessor(BB); 286398d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer 28643d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // Merge basic blocks into their predecessor if there is only one distinct 28653d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // pred, and if there is only one distinct successor of the predecessor, and 28663d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // if there are no PHI nodes. 28673d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // 28683d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (MergeBlockIntoPredecessor(BB)) 28693d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner return true; 28703d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 28713e410c6607192bbf28ba3708245cb70a0f983556Devang Patel IRBuilder<> Builder(BB); 28723e410c6607192bbf28ba3708245cb70a0f983556Devang Patel 28733d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // If there is a trivial two-entry PHI node in this basic block, and we can 28743d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // eliminate it, do so now. 28753d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (PHINode *PN = dyn_cast<PHINode>(BB->begin())) 28763d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (PN->getNumIncomingValues() == 2) 2877d3a1788da15311781f661c1cbfe48cd5f98ae778Devang Patel Changed |= FoldTwoEntryPHINode(PN, TD); 28783d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 2879007349dafda47296177fd7481aff9764d4179f42Devang Patel Builder.SetInsertPoint(BB->getTerminator()); 28803d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (BranchInst *BI = dyn_cast<BranchInst>(BB->getTerminator())) { 2881021c9d3bd41bc446ef0860c05a073e32afa5e20fChris Lattner if (BI->isUnconditional()) { 2882a23812cfbd23604d2fc103cf232cde8fa270a491Devang Patel if (SimplifyUncondBranch(BI, Builder)) return true; 2883021c9d3bd41bc446ef0860c05a073e32afa5e20fChris Lattner } else { 2884007349dafda47296177fd7481aff9764d4179f42Devang Patel if (SimplifyCondBranch(BI, Builder)) return true; 2885021c9d3bd41bc446ef0860c05a073e32afa5e20fChris Lattner } 2886ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands } else if (ResumeInst *RI = dyn_cast<ResumeInst>(BB->getTerminator())) { 2887ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands if (SimplifyResume(RI, Builder)) return true; 2888021c9d3bd41bc446ef0860c05a073e32afa5e20fChris Lattner } else if (ReturnInst *RI = dyn_cast<ReturnInst>(BB->getTerminator())) { 2889176ec40cb18c51c14fccbb38ee0db5deafb6baa9Devang Patel if (SimplifyReturn(RI, Builder)) return true; 2890021c9d3bd41bc446ef0860c05a073e32afa5e20fChris Lattner } else if (SwitchInst *SI = dyn_cast<SwitchInst>(BB->getTerminator())) { 2891007349dafda47296177fd7481aff9764d4179f42Devang Patel if (SimplifySwitch(SI, Builder)) return true; 2892021c9d3bd41bc446ef0860c05a073e32afa5e20fChris Lattner } else if (UnreachableInst *UI = 2893021c9d3bd41bc446ef0860c05a073e32afa5e20fChris Lattner dyn_cast<UnreachableInst>(BB->getTerminator())) { 2894021c9d3bd41bc446ef0860c05a073e32afa5e20fChris Lattner if (SimplifyUnreachable(UI)) return true; 2895021c9d3bd41bc446ef0860c05a073e32afa5e20fChris Lattner } else if (UnwindInst *UI = dyn_cast<UnwindInst>(BB->getTerminator())) { 2896d46ba26a6b513086ad575e5db0069b03d41fca13Devang Patel if (SimplifyUnwind(UI, Builder)) return true; 2897021c9d3bd41bc446ef0860c05a073e32afa5e20fChris Lattner } else if (IndirectBrInst *IBI = 2898021c9d3bd41bc446ef0860c05a073e32afa5e20fChris Lattner dyn_cast<IndirectBrInst>(BB->getTerminator())) { 2899021c9d3bd41bc446ef0860c05a073e32afa5e20fChris Lattner if (SimplifyIndirectBr(IBI)) return true; 29003d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } 29013d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 2902694e37f08a7c09ccc24642532106295cf7b3a1e3Chris Lattner return Changed; 290301d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner} 290458e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen 290558e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen/// SimplifyCFG - This function is used to do simplification of a CFG. For 290658e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen/// example, it adjusts branches to branches to eliminate the extra hop, it 290758e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen/// eliminates unreachable basic blocks, and does other "peephole" optimization 290858e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen/// of the CFG. It returns true if a modification was made. 290958e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen/// 291058e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesenbool llvm::SimplifyCFG(BasicBlock *BB, const TargetData *TD) { 291158e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen return SimplifyCFGOpt(TD).run(BB); 291258e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen} 2913