SimplifyCFG.cpp revision 91968489d718b313d4c0b912062e75a82db650e7
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" 179d5231022283ff20b0291eb5711a449de262d3feNick Lewycky#include "llvm/DerivedTypes.h" 189d5231022283ff20b0291eb5711a449de262d3feNick Lewycky#include "llvm/GlobalVariable.h" 19723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner#include "llvm/Instructions.h" 20383d7ed9158576aef5cde872548225a17e3c0155Devang Patel#include "llvm/IntrinsicInst.h" 2106cc66f65a5012471835068029f3f4943790f584Nick Lewycky#include "llvm/LLVMContext.h" 2206cc66f65a5012471835068029f3f4943790f584Nick Lewycky#include "llvm/Metadata.h" 230d56008f53587531718ec36af82cc24576580b36Chris Lattner#include "llvm/Type.h" 24302ba6fc1cb26248b0d6524fc42c740370926d6dChris Lattner#include "llvm/Analysis/InstructionSimplify.h" 2510fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer#include "llvm/Analysis/ValueTracking.h" 2658e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen#include "llvm/Target/TargetData.h" 27eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner#include "llvm/Transforms/Utils/BasicBlockUtils.h" 282c63566e406974caa70ee27f35af28112e80f951Dan Gohman#include "llvm/ADT/DenseMap.h" 2993e985f1b17aef62d58e3198a4604f9f6cfe8d19Chris Lattner#include "llvm/ADT/SmallVector.h" 30c9951231822215d6aea7a9b50947c18d8d745609Chris Lattner#include "llvm/ADT/SmallPtrSet.h" 31502a4f5162498ec420e3cb22f667808d726dd7daEvan Cheng#include "llvm/ADT/Statistic.h" 326d4d21e29d4840236ab6f15c5247379820021d0cChris Lattner#include "llvm/ADT/STLExtras.h" 33302ba6fc1cb26248b0d6524fc42c740370926d6dChris Lattner#include "llvm/Support/CFG.h" 34c3f507f98a0747bd256e1c13536060b6fc5c4b62Evan Cheng#include "llvm/Support/CommandLine.h" 35e27db74a60c44d2b5d2700ecde11b1adce0d0d59Chris Lattner#include "llvm/Support/ConstantRange.h" 36302ba6fc1cb26248b0d6524fc42c740370926d6dChris Lattner#include "llvm/Support/Debug.h" 373e410c6607192bbf28ba3708245cb70a0f983556Devang Patel#include "llvm/Support/IRBuilder.h" 38d3a1788da15311781f661c1cbfe48cd5f98ae778Devang Patel#include "llvm/Support/NoFolder.h" 39302ba6fc1cb26248b0d6524fc42c740370926d6dChris Lattner#include "llvm/Support/raw_ostream.h" 4001d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner#include <algorithm> 41d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner#include <set> 42698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner#include <map> 43f7703df4968084c18c248c1feea9961c19a32e6aChris Lattnerusing namespace llvm; 44d0fde30ce850b78371fd1386338350591f9ff494Brian Gaeke 4557808b3da00d7abd01382d3ed5e70bfb0b2beb4bPeter Collingbournestatic cl::opt<unsigned> 4657808b3da00d7abd01382d3ed5e70bfb0b2beb4bPeter CollingbournePHINodeFoldingThreshold("phi-node-folding-threshold", cl::Hidden, cl::init(1), 4757808b3da00d7abd01382d3ed5e70bfb0b2beb4bPeter Collingbourne cl::desc("Control the amount of phi node folding to perform (default = 1)")); 4857808b3da00d7abd01382d3ed5e70bfb0b2beb4bPeter Collingbourne 49c3f507f98a0747bd256e1c13536060b6fc5c4b62Evan Chengstatic cl::opt<bool> 50c3f507f98a0747bd256e1c13536060b6fc5c4b62Evan ChengDupRet("simplifycfg-dup-ret", cl::Hidden, cl::init(false), 51c3f507f98a0747bd256e1c13536060b6fc5c4b62Evan Cheng cl::desc("Duplicate return instructions into unconditional branches")); 52c3f507f98a0747bd256e1c13536060b6fc5c4b62Evan Cheng 53502a4f5162498ec420e3cb22f667808d726dd7daEvan ChengSTATISTIC(NumSpeculations, "Number of speculative executed instructions"); 54502a4f5162498ec420e3cb22f667808d726dd7daEvan Cheng 5558e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesennamespace { 5658e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesenclass SimplifyCFGOpt { 5758e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen const TargetData *const TD; 5858e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen 5958e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen Value *isValueEqualityComparison(TerminatorInst *TI); 6058e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen BasicBlock *GetValueEqualityComparisonCases(TerminatorInst *TI, 6158e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen std::vector<std::pair<ConstantInt*, BasicBlock*> > &Cases); 6258e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen bool SimplifyEqualityComparisonWithOnlyPredecessor(TerminatorInst *TI, 63007349dafda47296177fd7481aff9764d4179f42Devang Patel BasicBlock *Pred, 64007349dafda47296177fd7481aff9764d4179f42Devang Patel IRBuilder<> &Builder); 65b55d924b1e33341d08b1bead78e86fce56617784Devang Patel bool FoldValueComparisonIntoPredecessors(TerminatorInst *TI, 66b55d924b1e33341d08b1bead78e86fce56617784Devang Patel IRBuilder<> &Builder); 6758e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen 68ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands bool SimplifyResume(ResumeInst *RI, IRBuilder<> &Builder); 69176ec40cb18c51c14fccbb38ee0db5deafb6baa9Devang Patel bool SimplifyReturn(ReturnInst *RI, IRBuilder<> &Builder); 70d46ba26a6b513086ad575e5db0069b03d41fca13Devang Patel bool SimplifyUnwind(UnwindInst *UI, IRBuilder<> &Builder); 713d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner bool SimplifyUnreachable(UnreachableInst *UI); 72007349dafda47296177fd7481aff9764d4179f42Devang Patel bool SimplifySwitch(SwitchInst *SI, IRBuilder<> &Builder); 733d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner bool SimplifyIndirectBr(IndirectBrInst *IBI); 74a23812cfbd23604d2fc103cf232cde8fa270a491Devang Patel bool SimplifyUncondBranch(BranchInst *BI, IRBuilder <> &Builder); 75007349dafda47296177fd7481aff9764d4179f42Devang Patel bool SimplifyCondBranch(BranchInst *BI, IRBuilder <>&Builder); 763d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 7758e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesenpublic: 7858e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen explicit SimplifyCFGOpt(const TargetData *td) : TD(td) {} 7958e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen bool run(BasicBlock *BB); 8058e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen}; 8158e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen} 8258e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen 832bdcb56146279009f233933a101cb3dd54a951cdChris Lattner/// SafeToMergeTerminators - Return true if it is safe to merge these two 842bdcb56146279009f233933a101cb3dd54a951cdChris Lattner/// terminator instructions together. 852bdcb56146279009f233933a101cb3dd54a951cdChris Lattner/// 862bdcb56146279009f233933a101cb3dd54a951cdChris Lattnerstatic bool SafeToMergeTerminators(TerminatorInst *SI1, TerminatorInst *SI2) { 872bdcb56146279009f233933a101cb3dd54a951cdChris Lattner if (SI1 == SI2) return false; // Can't merge with self! 882bdcb56146279009f233933a101cb3dd54a951cdChris Lattner 892bdcb56146279009f233933a101cb3dd54a951cdChris Lattner // It is not safe to merge these two switch instructions if they have a common 902bdcb56146279009f233933a101cb3dd54a951cdChris Lattner // successor, and if that successor has a PHI node, and if *that* PHI node has 912bdcb56146279009f233933a101cb3dd54a951cdChris Lattner // conflicting incoming values from the two switch blocks. 922bdcb56146279009f233933a101cb3dd54a951cdChris Lattner BasicBlock *SI1BB = SI1->getParent(); 932bdcb56146279009f233933a101cb3dd54a951cdChris Lattner BasicBlock *SI2BB = SI2->getParent(); 94c9951231822215d6aea7a9b50947c18d8d745609Chris Lattner SmallPtrSet<BasicBlock*, 16> SI1Succs(succ_begin(SI1BB), succ_end(SI1BB)); 952bdcb56146279009f233933a101cb3dd54a951cdChris Lattner 962bdcb56146279009f233933a101cb3dd54a951cdChris Lattner for (succ_iterator I = succ_begin(SI2BB), E = succ_end(SI2BB); I != E; ++I) 972bdcb56146279009f233933a101cb3dd54a951cdChris Lattner if (SI1Succs.count(*I)) 982bdcb56146279009f233933a101cb3dd54a951cdChris Lattner for (BasicBlock::iterator BBI = (*I)->begin(); 992bdcb56146279009f233933a101cb3dd54a951cdChris Lattner isa<PHINode>(BBI); ++BBI) { 1002bdcb56146279009f233933a101cb3dd54a951cdChris Lattner PHINode *PN = cast<PHINode>(BBI); 1012bdcb56146279009f233933a101cb3dd54a951cdChris Lattner if (PN->getIncomingValueForBlock(SI1BB) != 1022bdcb56146279009f233933a101cb3dd54a951cdChris Lattner PN->getIncomingValueForBlock(SI2BB)) 1032bdcb56146279009f233933a101cb3dd54a951cdChris Lattner return false; 1042bdcb56146279009f233933a101cb3dd54a951cdChris Lattner } 1052bdcb56146279009f233933a101cb3dd54a951cdChris Lattner 1062bdcb56146279009f233933a101cb3dd54a951cdChris Lattner return true; 1072bdcb56146279009f233933a101cb3dd54a951cdChris Lattner} 1082bdcb56146279009f233933a101cb3dd54a951cdChris Lattner 1092bdcb56146279009f233933a101cb3dd54a951cdChris Lattner/// AddPredecessorToBlock - Update PHI nodes in Succ to indicate that there will 1102bdcb56146279009f233933a101cb3dd54a951cdChris Lattner/// now be entries in it from the 'NewPred' block. The values that will be 1112bdcb56146279009f233933a101cb3dd54a951cdChris Lattner/// flowing into the PHI nodes will be the same as those coming in from 1122bdcb56146279009f233933a101cb3dd54a951cdChris Lattner/// ExistPred, an existing predecessor of Succ. 1132bdcb56146279009f233933a101cb3dd54a951cdChris Lattnerstatic void AddPredecessorToBlock(BasicBlock *Succ, BasicBlock *NewPred, 1142bdcb56146279009f233933a101cb3dd54a951cdChris Lattner BasicBlock *ExistPred) { 1152bdcb56146279009f233933a101cb3dd54a951cdChris Lattner if (!isa<PHINode>(Succ->begin())) return; // Quick exit if nothing to do 1162bdcb56146279009f233933a101cb3dd54a951cdChris Lattner 117093a4385027235459ab6972b2e2fdc79061773cfChris Lattner PHINode *PN; 118093a4385027235459ab6972b2e2fdc79061773cfChris Lattner for (BasicBlock::iterator I = Succ->begin(); 119093a4385027235459ab6972b2e2fdc79061773cfChris Lattner (PN = dyn_cast<PHINode>(I)); ++I) 120093a4385027235459ab6972b2e2fdc79061773cfChris Lattner PN->addIncoming(PN->getIncomingValueForBlock(ExistPred), NewPred); 1212bdcb56146279009f233933a101cb3dd54a951cdChris Lattner} 1222bdcb56146279009f233933a101cb3dd54a951cdChris Lattner 1237e66348cba4384d07b37ad1c186e67ba6d26babdChris Lattner 12473c50a68a7e26b59db54df86e9cc87eed5034bf4Chris Lattner/// GetIfCondition - Given a basic block (BB) with two predecessors (and at 12573c50a68a7e26b59db54df86e9cc87eed5034bf4Chris Lattner/// least one PHI node in it), check to see if the merge at this block is due 126723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner/// to an "if condition". If so, return the boolean condition that determines 127723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner/// which entry into BB will be taken. Also, return by references the block 128723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner/// that will be entered from if the condition is true, and the block that will 129723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner/// be entered if the condition is false. 130fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukman/// 131995ba1bd49e57dee8e301d5f33a7c01d73b7385dChris Lattner/// This does no checking to see if the true/false blocks have large or unsavory 132995ba1bd49e57dee8e301d5f33a7c01d73b7385dChris Lattner/// instructions in them. 13373c50a68a7e26b59db54df86e9cc87eed5034bf4Chris Lattnerstatic Value *GetIfCondition(BasicBlock *BB, BasicBlock *&IfTrue, 13473c50a68a7e26b59db54df86e9cc87eed5034bf4Chris Lattner BasicBlock *&IfFalse) { 13573c50a68a7e26b59db54df86e9cc87eed5034bf4Chris Lattner PHINode *SomePHI = cast<PHINode>(BB->begin()); 13673c50a68a7e26b59db54df86e9cc87eed5034bf4Chris Lattner assert(SomePHI->getNumIncomingValues() == 2 && 137723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner "Function can only handle blocks with 2 predecessors!"); 13873c50a68a7e26b59db54df86e9cc87eed5034bf4Chris Lattner BasicBlock *Pred1 = SomePHI->getIncomingBlock(0); 13973c50a68a7e26b59db54df86e9cc87eed5034bf4Chris Lattner BasicBlock *Pred2 = SomePHI->getIncomingBlock(1); 140723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner 141723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // We can only handle branches. Other control flow will be lowered to 142723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // branches if possible anyway. 143995ba1bd49e57dee8e301d5f33a7c01d73b7385dChris Lattner BranchInst *Pred1Br = dyn_cast<BranchInst>(Pred1->getTerminator()); 144995ba1bd49e57dee8e301d5f33a7c01d73b7385dChris Lattner BranchInst *Pred2Br = dyn_cast<BranchInst>(Pred2->getTerminator()); 145995ba1bd49e57dee8e301d5f33a7c01d73b7385dChris Lattner if (Pred1Br == 0 || Pred2Br == 0) 146723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner return 0; 147723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner 148723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // Eliminate code duplication by ensuring that Pred1Br is conditional if 149723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // either are. 150723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner if (Pred2Br->isConditional()) { 151723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // If both branches are conditional, we don't have an "if statement". In 152723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // reality, we could transform this case, but since the condition will be 153723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // required anyway, we stand no chance of eliminating it, so the xform is 154723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // probably not profitable. 155723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner if (Pred1Br->isConditional()) 156723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner return 0; 157723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner 158723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner std::swap(Pred1, Pred2); 159723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner std::swap(Pred1Br, Pred2Br); 160723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner } 161723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner 162723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner if (Pred1Br->isConditional()) { 163995ba1bd49e57dee8e301d5f33a7c01d73b7385dChris Lattner // The only thing we have to watch out for here is to make sure that Pred2 164995ba1bd49e57dee8e301d5f33a7c01d73b7385dChris Lattner // doesn't have incoming edges from other blocks. If it does, the condition 165995ba1bd49e57dee8e301d5f33a7c01d73b7385dChris Lattner // doesn't dominate BB. 166995ba1bd49e57dee8e301d5f33a7c01d73b7385dChris Lattner if (Pred2->getSinglePredecessor() == 0) 167995ba1bd49e57dee8e301d5f33a7c01d73b7385dChris Lattner return 0; 168995ba1bd49e57dee8e301d5f33a7c01d73b7385dChris Lattner 169723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // If we found a conditional branch predecessor, make sure that it branches 170723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // to BB and Pred2Br. If it doesn't, this isn't an "if statement". 171723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner if (Pred1Br->getSuccessor(0) == BB && 172723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner Pred1Br->getSuccessor(1) == Pred2) { 173723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner IfTrue = Pred1; 174723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner IfFalse = Pred2; 175723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner } else if (Pred1Br->getSuccessor(0) == Pred2 && 176723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner Pred1Br->getSuccessor(1) == BB) { 177723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner IfTrue = Pred2; 178723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner IfFalse = Pred1; 179723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner } else { 180723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // We know that one arm of the conditional goes to BB, so the other must 181723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // go somewhere unrelated, and this must not be an "if statement". 182723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner return 0; 183723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner } 184723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner 185723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner return Pred1Br->getCondition(); 186723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner } 187723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner 188723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // Ok, if we got here, both predecessors end with an unconditional branch to 189723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // BB. Don't panic! If both blocks only have a single (identical) 190723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // predecessor, and THAT is a conditional branch, then we're all ok! 191995ba1bd49e57dee8e301d5f33a7c01d73b7385dChris Lattner BasicBlock *CommonPred = Pred1->getSinglePredecessor(); 192995ba1bd49e57dee8e301d5f33a7c01d73b7385dChris Lattner if (CommonPred == 0 || CommonPred != Pred2->getSinglePredecessor()) 193723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner return 0; 194723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner 195723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // Otherwise, if this is a conditional branch, then we can use it! 196995ba1bd49e57dee8e301d5f33a7c01d73b7385dChris Lattner BranchInst *BI = dyn_cast<BranchInst>(CommonPred->getTerminator()); 197995ba1bd49e57dee8e301d5f33a7c01d73b7385dChris Lattner if (BI == 0) return 0; 198995ba1bd49e57dee8e301d5f33a7c01d73b7385dChris Lattner 199995ba1bd49e57dee8e301d5f33a7c01d73b7385dChris Lattner assert(BI->isConditional() && "Two successors but not conditional?"); 200995ba1bd49e57dee8e301d5f33a7c01d73b7385dChris Lattner if (BI->getSuccessor(0) == Pred1) { 201995ba1bd49e57dee8e301d5f33a7c01d73b7385dChris Lattner IfTrue = Pred1; 202995ba1bd49e57dee8e301d5f33a7c01d73b7385dChris Lattner IfFalse = Pred2; 203995ba1bd49e57dee8e301d5f33a7c01d73b7385dChris Lattner } else { 204995ba1bd49e57dee8e301d5f33a7c01d73b7385dChris Lattner IfTrue = Pred2; 205995ba1bd49e57dee8e301d5f33a7c01d73b7385dChris Lattner IfFalse = Pred1; 206723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner } 207995ba1bd49e57dee8e301d5f33a7c01d73b7385dChris Lattner return BI->getCondition(); 208723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner} 209723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner 2105049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// DominatesMergePoint - If we have a merge point of an "if condition" as 2115049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// accepted above, return true if the specified value dominates the block. We 2125049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// don't handle the true generality of domination here, just a special case 2135049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// which works well enough for us. 2145049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// 2155049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// If AggressiveInsts is non-null, and if V does not dominate BB, we check to 216f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne/// see if V (which must be an instruction) and its recursive operands 217f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne/// that do not dominate BB have a combined cost lower than CostRemaining and 218f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne/// are non-trapping. If both are true, the instruction is inserted into the 219f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne/// set and true is returned. 220f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne/// 221f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne/// The cost for most non-trapping instructions is defined as 1 except for 222f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne/// Select whose cost is 2. 223f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne/// 224f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne/// After this function returns, CostRemaining is decreased by the cost of 225f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne/// V plus its non-dominating operands. If that cost is greater than 226f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne/// CostRemaining, false is returned and CostRemaining is undefined. 2279c07866ef861e072395306e9811c329c7fe5bbe8Chris Lattnerstatic bool DominatesMergePoint(Value *V, BasicBlock *BB, 228f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne SmallPtrSet<Instruction*, 4> *AggressiveInsts, 229f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne unsigned &CostRemaining) { 230570751c2a7d8851bc61e408746a903b0253d2d21Chris Lattner Instruction *I = dyn_cast<Instruction>(V); 231b74b1816305affe25da32c2f29532df41a23cd55Chris Lattner if (!I) { 232b74b1816305affe25da32c2f29532df41a23cd55Chris Lattner // Non-instructions all dominate instructions, but not all constantexprs 233b74b1816305affe25da32c2f29532df41a23cd55Chris Lattner // can be executed unconditionally. 234b74b1816305affe25da32c2f29532df41a23cd55Chris Lattner if (ConstantExpr *C = dyn_cast<ConstantExpr>(V)) 235b74b1816305affe25da32c2f29532df41a23cd55Chris Lattner if (C->canTrap()) 236b74b1816305affe25da32c2f29532df41a23cd55Chris Lattner return false; 237b74b1816305affe25da32c2f29532df41a23cd55Chris Lattner return true; 238b74b1816305affe25da32c2f29532df41a23cd55Chris Lattner } 239570751c2a7d8851bc61e408746a903b0253d2d21Chris Lattner BasicBlock *PBB = I->getParent(); 240570751c2a7d8851bc61e408746a903b0253d2d21Chris Lattner 241da895d63377b421dc50117befb2bec80d2973526Chris Lattner // We don't want to allow weird loops that might have the "if condition" in 242570751c2a7d8851bc61e408746a903b0253d2d21Chris Lattner // the bottom of this block. 243570751c2a7d8851bc61e408746a903b0253d2d21Chris Lattner if (PBB == BB) return false; 244570751c2a7d8851bc61e408746a903b0253d2d21Chris Lattner 245570751c2a7d8851bc61e408746a903b0253d2d21Chris Lattner // If this instruction is defined in a block that contains an unconditional 246570751c2a7d8851bc61e408746a903b0253d2d21Chris Lattner // branch to BB, then it must be in the 'conditional' part of the "if 24744da7ca4213333bcade57a407a890970351db494Chris Lattner // statement". If not, it definitely dominates the region. 24844da7ca4213333bcade57a407a890970351db494Chris Lattner BranchInst *BI = dyn_cast<BranchInst>(PBB->getTerminator()); 24944da7ca4213333bcade57a407a890970351db494Chris Lattner if (BI == 0 || BI->isConditional() || BI->getSuccessor(0) != BB) 25044da7ca4213333bcade57a407a890970351db494Chris Lattner return true; 2510b79a7727d68a507837e827803859424cf3d997bEli Friedman 25244da7ca4213333bcade57a407a890970351db494Chris Lattner // If we aren't allowing aggressive promotion anymore, then don't consider 25344da7ca4213333bcade57a407a890970351db494Chris Lattner // instructions in the 'if region'. 25444da7ca4213333bcade57a407a890970351db494Chris Lattner if (AggressiveInsts == 0) return false; 25544da7ca4213333bcade57a407a890970351db494Chris Lattner 256f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne // If we have seen this instruction before, don't count it again. 257f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne if (AggressiveInsts->count(I)) return true; 258f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne 25944da7ca4213333bcade57a407a890970351db494Chris Lattner // Okay, it looks like the instruction IS in the "condition". Check to 26044da7ca4213333bcade57a407a890970351db494Chris Lattner // see if it's a cheap instruction to unconditionally compute, and if it 26144da7ca4213333bcade57a407a890970351db494Chris Lattner // only uses stuff defined outside of the condition. If so, hoist it out. 262f0426601977c3e386d2d26c72a2cca691dc42072Dan Gohman if (!isSafeToSpeculativelyExecute(I)) 26344da7ca4213333bcade57a407a890970351db494Chris Lattner return false; 264fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukman 265f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne unsigned Cost = 0; 266f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne 26744da7ca4213333bcade57a407a890970351db494Chris Lattner switch (I->getOpcode()) { 26844da7ca4213333bcade57a407a890970351db494Chris Lattner default: return false; // Cannot hoist this out safely. 26944da7ca4213333bcade57a407a890970351db494Chris Lattner case Instruction::Load: 27044da7ca4213333bcade57a407a890970351db494Chris Lattner // We have to check to make sure there are no instructions before the 27144da7ca4213333bcade57a407a890970351db494Chris Lattner // load in its basic block, as we are going to hoist the load out to its 27244da7ca4213333bcade57a407a890970351db494Chris Lattner // predecessor. 27344da7ca4213333bcade57a407a890970351db494Chris Lattner if (PBB->getFirstNonPHIOrDbg() != I) 27444da7ca4213333bcade57a407a890970351db494Chris Lattner return false; 275f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne Cost = 1; 27644da7ca4213333bcade57a407a890970351db494Chris Lattner break; 277278be783b5068e6f87f16bc9b69a77e0bc958f9fBenjamin Kramer case Instruction::GetElementPtr: 278278be783b5068e6f87f16bc9b69a77e0bc958f9fBenjamin Kramer // GEPs are cheap if all indices are constant. 279278be783b5068e6f87f16bc9b69a77e0bc958f9fBenjamin Kramer if (!cast<GetElementPtrInst>(I)->hasAllConstantIndices()) 2809b61c550c2f1fa889163a338f5d6c02b50fe961cBenjamin Kramer return false; 281f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne Cost = 1; 2829b61c550c2f1fa889163a338f5d6c02b50fe961cBenjamin Kramer break; 28344da7ca4213333bcade57a407a890970351db494Chris Lattner case Instruction::Add: 28444da7ca4213333bcade57a407a890970351db494Chris Lattner case Instruction::Sub: 28544da7ca4213333bcade57a407a890970351db494Chris Lattner case Instruction::And: 28644da7ca4213333bcade57a407a890970351db494Chris Lattner case Instruction::Or: 28744da7ca4213333bcade57a407a890970351db494Chris Lattner case Instruction::Xor: 28844da7ca4213333bcade57a407a890970351db494Chris Lattner case Instruction::Shl: 28944da7ca4213333bcade57a407a890970351db494Chris Lattner case Instruction::LShr: 29044da7ca4213333bcade57a407a890970351db494Chris Lattner case Instruction::AShr: 29144da7ca4213333bcade57a407a890970351db494Chris Lattner case Instruction::ICmp: 2928a70192b510e2a0f05493b9212e998017f3d178dPeter Collingbourne case Instruction::Trunc: 2938a70192b510e2a0f05493b9212e998017f3d178dPeter Collingbourne case Instruction::ZExt: 2948a70192b510e2a0f05493b9212e998017f3d178dPeter Collingbourne case Instruction::SExt: 295f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne Cost = 1; 29644da7ca4213333bcade57a407a890970351db494Chris Lattner break; // These are all cheap and non-trapping instructions. 297f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne 2988369687576b062be74c941a4a90dbabb0828e028Nick Lewycky case Instruction::Call: 299f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne case Instruction::Select: 300f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne Cost = 2; 301f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne break; 30244da7ca4213333bcade57a407a890970351db494Chris Lattner } 303723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner 304f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne if (Cost > CostRemaining) 305f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne return false; 306f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne 307f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne CostRemaining -= Cost; 308f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne 309f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne // Okay, we can only really hoist these out if their operands do 310f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne // not take us over the cost threshold. 31144da7ca4213333bcade57a407a890970351db494Chris Lattner for (User::op_iterator i = I->op_begin(), e = I->op_end(); i != e; ++i) 312f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne if (!DominatesMergePoint(*i, BB, AggressiveInsts, CostRemaining)) 31344da7ca4213333bcade57a407a890970351db494Chris Lattner return false; 31444da7ca4213333bcade57a407a890970351db494Chris Lattner // Okay, it's safe to do this! Remember this instruction. 31544da7ca4213333bcade57a407a890970351db494Chris Lattner AggressiveInsts->insert(I); 316723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner return true; 317723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner} 31801d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner 31958e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen/// GetConstantInt - Extract ConstantInt from value, looking through IntToPtr 32058e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen/// and PointerNullValue. Return NULL if value is not a constant int. 32128acc135481691771205dea7cb4edbd3927aa764Chris Lattnerstatic ConstantInt *GetConstantInt(Value *V, const TargetData *TD) { 32258e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen // Normal constant int. 32358e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen ConstantInt *CI = dyn_cast<ConstantInt>(V); 3241df9859c40492511b8aa4321eb76496005d3b75bDuncan Sands if (CI || !TD || !isa<Constant>(V) || !V->getType()->isPointerTy()) 32558e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen return CI; 32658e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen 32758e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen // This is some kind of pointer constant. Turn it into a pointer-sized 32858e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen // ConstantInt if possible. 329db125cfaf57cc83e7dd7453de2d509bc8efd0e5eChris Lattner IntegerType *PtrTy = TD->getIntPtrType(V->getContext()); 33058e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen 33158e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen // Null pointer means 0, see SelectionDAGBuilder::getValue(const Value*). 33258e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen if (isa<ConstantPointerNull>(V)) 33358e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen return ConstantInt::get(PtrTy, 0); 33458e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen 33558e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen // IntToPtr const int. 33658e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) 33758e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen if (CE->getOpcode() == Instruction::IntToPtr) 33858e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen if (ConstantInt *CI = dyn_cast<ConstantInt>(CE->getOperand(0))) { 33958e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen // The constant is very likely to have the right type already. 34058e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen if (CI->getType() == PtrTy) 34158e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen return CI; 34258e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen else 34358e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen return cast<ConstantInt> 34458e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen (ConstantExpr::getIntegerCast(CI, PtrTy, /*isSigned=*/false)); 34558e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen } 34658e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen return 0; 34758e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen} 34858e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen 3490aa749bde7c696e0522df5581ea9cc70f25e62cbChris Lattner/// GatherConstantCompares - Given a potentially 'or'd or 'and'd together 3500aa749bde7c696e0522df5581ea9cc70f25e62cbChris Lattner/// collection of icmp eq/ne instructions that compare a value against a 3510aa749bde7c696e0522df5581ea9cc70f25e62cbChris Lattner/// constant, return the value being compared, and stick the constant into the 3520aa749bde7c696e0522df5581ea9cc70f25e62cbChris Lattner/// Values vector. 35328acc135481691771205dea7cb4edbd3927aa764Chris Lattnerstatic Value * 3540aa749bde7c696e0522df5581ea9cc70f25e62cbChris LattnerGatherConstantCompares(Value *V, std::vector<ConstantInt*> &Vals, Value *&Extra, 35533828bcb24176aae72afac0e4953e4b7f9560ef1Benjamin Kramer const TargetData *TD, bool isEQ, unsigned &UsedICmps) { 3560aa749bde7c696e0522df5581ea9cc70f25e62cbChris Lattner Instruction *I = dyn_cast<Instruction>(V); 3570aa749bde7c696e0522df5581ea9cc70f25e62cbChris Lattner if (I == 0) return 0; 3589a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner 3597312a22ed63607e4ae7b0d9326e42358fd41e245Chris Lattner // If this is an icmp against a constant, handle this as one of the cases. 3600aa749bde7c696e0522df5581ea9cc70f25e62cbChris Lattner if (ICmpInst *ICI = dyn_cast<ICmpInst>(I)) { 361e27db74a60c44d2b5d2700ecde11b1adce0d0d59Chris Lattner if (ConstantInt *C = GetConstantInt(I->getOperand(1), TD)) { 362e27db74a60c44d2b5d2700ecde11b1adce0d0d59Chris Lattner if (ICI->getPredicate() == (isEQ ? ICmpInst::ICMP_EQ:ICmpInst::ICMP_NE)) { 36333828bcb24176aae72afac0e4953e4b7f9560ef1Benjamin Kramer UsedICmps++; 3640aa749bde7c696e0522df5581ea9cc70f25e62cbChris Lattner Vals.push_back(C); 3650aa749bde7c696e0522df5581ea9cc70f25e62cbChris Lattner return I->getOperand(0); 3660aa749bde7c696e0522df5581ea9cc70f25e62cbChris Lattner } 367e27db74a60c44d2b5d2700ecde11b1adce0d0d59Chris Lattner 368e27db74a60c44d2b5d2700ecde11b1adce0d0d59Chris Lattner // If we have "x ult 3" comparison, for example, then we can add 0,1,2 to 369e27db74a60c44d2b5d2700ecde11b1adce0d0d59Chris Lattner // the set. 370e27db74a60c44d2b5d2700ecde11b1adce0d0d59Chris Lattner ConstantRange Span = 371a37029cd24105f645a694abbafbc9bf1212708b0Chris Lattner ConstantRange::makeICmpRegion(ICI->getPredicate(), C->getValue()); 372e27db74a60c44d2b5d2700ecde11b1adce0d0d59Chris Lattner 373e27db74a60c44d2b5d2700ecde11b1adce0d0d59Chris Lattner // If this is an and/!= check then we want to optimize "x ugt 2" into 374e27db74a60c44d2b5d2700ecde11b1adce0d0d59Chris Lattner // x != 0 && x != 1. 375e27db74a60c44d2b5d2700ecde11b1adce0d0d59Chris Lattner if (!isEQ) 376e27db74a60c44d2b5d2700ecde11b1adce0d0d59Chris Lattner Span = Span.inverse(); 377e27db74a60c44d2b5d2700ecde11b1adce0d0d59Chris Lattner 378e27db74a60c44d2b5d2700ecde11b1adce0d0d59Chris Lattner // If there are a ton of values, we don't want to make a ginormous switch. 37914c0987bd9ab50ebb8728e62a0b29d8f7f951984Benjamin Kramer if (Span.getSetSize().ugt(8) || Span.isEmptySet() || 380e27db74a60c44d2b5d2700ecde11b1adce0d0d59Chris Lattner // We don't handle wrapped sets yet. 381e27db74a60c44d2b5d2700ecde11b1adce0d0d59Chris Lattner Span.isWrappedSet()) 382e27db74a60c44d2b5d2700ecde11b1adce0d0d59Chris Lattner return 0; 383e27db74a60c44d2b5d2700ecde11b1adce0d0d59Chris Lattner 384e27db74a60c44d2b5d2700ecde11b1adce0d0d59Chris Lattner for (APInt Tmp = Span.getLower(); Tmp != Span.getUpper(); ++Tmp) 385e27db74a60c44d2b5d2700ecde11b1adce0d0d59Chris Lattner Vals.push_back(ConstantInt::get(V->getContext(), Tmp)); 38633828bcb24176aae72afac0e4953e4b7f9560ef1Benjamin Kramer UsedICmps++; 387e27db74a60c44d2b5d2700ecde11b1adce0d0d59Chris Lattner return I->getOperand(0); 388e27db74a60c44d2b5d2700ecde11b1adce0d0d59Chris Lattner } 389662269d2abb2f220c3a9b727c2a948246128cd05Chris Lattner return 0; 390662269d2abb2f220c3a9b727c2a948246128cd05Chris Lattner } 391662269d2abb2f220c3a9b727c2a948246128cd05Chris Lattner 3927312a22ed63607e4ae7b0d9326e42358fd41e245Chris Lattner // Otherwise, we can only handle an | or &, depending on isEQ. 3930aa749bde7c696e0522df5581ea9cc70f25e62cbChris Lattner if (I->getOpcode() != (isEQ ? Instruction::Or : Instruction::And)) 394662269d2abb2f220c3a9b727c2a948246128cd05Chris Lattner return 0; 395662269d2abb2f220c3a9b727c2a948246128cd05Chris Lattner 3967312a22ed63607e4ae7b0d9326e42358fd41e245Chris Lattner unsigned NumValsBeforeLHS = Vals.size(); 39733828bcb24176aae72afac0e4953e4b7f9560ef1Benjamin Kramer unsigned UsedICmpsBeforeLHS = UsedICmps; 3980aa749bde7c696e0522df5581ea9cc70f25e62cbChris Lattner if (Value *LHS = GatherConstantCompares(I->getOperand(0), Vals, Extra, TD, 39933828bcb24176aae72afac0e4953e4b7f9560ef1Benjamin Kramer isEQ, UsedICmps)) { 4007312a22ed63607e4ae7b0d9326e42358fd41e245Chris Lattner unsigned NumVals = Vals.size(); 40133828bcb24176aae72afac0e4953e4b7f9560ef1Benjamin Kramer unsigned UsedICmpsBeforeRHS = UsedICmps; 4020aa749bde7c696e0522df5581ea9cc70f25e62cbChris Lattner if (Value *RHS = GatherConstantCompares(I->getOperand(1), Vals, Extra, TD, 40333828bcb24176aae72afac0e4953e4b7f9560ef1Benjamin Kramer isEQ, UsedICmps)) { 4040aa749bde7c696e0522df5581ea9cc70f25e62cbChris Lattner if (LHS == RHS) 4050aa749bde7c696e0522df5581ea9cc70f25e62cbChris Lattner return LHS; 40692407e589524d98080f4db943a0e2a3bf18ec8a2Chris Lattner Vals.resize(NumVals); 40733828bcb24176aae72afac0e4953e4b7f9560ef1Benjamin Kramer UsedICmps = UsedICmpsBeforeRHS; 4080aa749bde7c696e0522df5581ea9cc70f25e62cbChris Lattner } 4097312a22ed63607e4ae7b0d9326e42358fd41e245Chris Lattner 4107312a22ed63607e4ae7b0d9326e42358fd41e245Chris Lattner // The RHS of the or/and can't be folded in and we haven't used "Extra" yet, 4117312a22ed63607e4ae7b0d9326e42358fd41e245Chris Lattner // set it and return success. 4127312a22ed63607e4ae7b0d9326e42358fd41e245Chris Lattner if (Extra == 0 || Extra == I->getOperand(1)) { 4137312a22ed63607e4ae7b0d9326e42358fd41e245Chris Lattner Extra = I->getOperand(1); 4147312a22ed63607e4ae7b0d9326e42358fd41e245Chris Lattner return LHS; 4157312a22ed63607e4ae7b0d9326e42358fd41e245Chris Lattner } 4167312a22ed63607e4ae7b0d9326e42358fd41e245Chris Lattner 4177312a22ed63607e4ae7b0d9326e42358fd41e245Chris Lattner Vals.resize(NumValsBeforeLHS); 41833828bcb24176aae72afac0e4953e4b7f9560ef1Benjamin Kramer UsedICmps = UsedICmpsBeforeLHS; 4197312a22ed63607e4ae7b0d9326e42358fd41e245Chris Lattner return 0; 4207312a22ed63607e4ae7b0d9326e42358fd41e245Chris Lattner } 4217312a22ed63607e4ae7b0d9326e42358fd41e245Chris Lattner 4227312a22ed63607e4ae7b0d9326e42358fd41e245Chris Lattner // If the LHS can't be folded in, but Extra is available and RHS can, try to 4237312a22ed63607e4ae7b0d9326e42358fd41e245Chris Lattner // use LHS as Extra. 4247312a22ed63607e4ae7b0d9326e42358fd41e245Chris Lattner if (Extra == 0 || Extra == I->getOperand(0)) { 42592407e589524d98080f4db943a0e2a3bf18ec8a2Chris Lattner Value *OldExtra = Extra; 4267312a22ed63607e4ae7b0d9326e42358fd41e245Chris Lattner Extra = I->getOperand(0); 4277312a22ed63607e4ae7b0d9326e42358fd41e245Chris Lattner if (Value *RHS = GatherConstantCompares(I->getOperand(1), Vals, Extra, TD, 42833828bcb24176aae72afac0e4953e4b7f9560ef1Benjamin Kramer isEQ, UsedICmps)) 4297312a22ed63607e4ae7b0d9326e42358fd41e245Chris Lattner return RHS; 43092407e589524d98080f4db943a0e2a3bf18ec8a2Chris Lattner assert(Vals.size() == NumValsBeforeLHS); 43192407e589524d98080f4db943a0e2a3bf18ec8a2Chris Lattner Extra = OldExtra; 43207e6e56f57e8781a8d7bc601cc9034a3741d84c2Anton Korobeynikov } 4337312a22ed63607e4ae7b0d9326e42358fd41e245Chris Lattner 4340d56008f53587531718ec36af82cc24576580b36Chris Lattner return 0; 4350d56008f53587531718ec36af82cc24576580b36Chris Lattner} 4369d5231022283ff20b0291eb5711a449de262d3feNick Lewycky 437080efb8cea6255b4f1f373d9cb583d6a6302106bEli Friedmanstatic void EraseTerminatorInstAndDCECond(TerminatorInst *TI) { 4389d5231022283ff20b0291eb5711a449de262d3feNick Lewycky Instruction *Cond = 0; 439080efb8cea6255b4f1f373d9cb583d6a6302106bEli Friedman if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) { 440080efb8cea6255b4f1f373d9cb583d6a6302106bEli Friedman Cond = dyn_cast<Instruction>(SI->getCondition()); 441080efb8cea6255b4f1f373d9cb583d6a6302106bEli Friedman } else if (BranchInst *BI = dyn_cast<BranchInst>(TI)) { 442080efb8cea6255b4f1f373d9cb583d6a6302106bEli Friedman if (BI->isConditional()) 443080efb8cea6255b4f1f373d9cb583d6a6302106bEli Friedman Cond = dyn_cast<Instruction>(BI->getCondition()); 4447ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel } else if (IndirectBrInst *IBI = dyn_cast<IndirectBrInst>(TI)) { 4457ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel Cond = dyn_cast<Instruction>(IBI->getAddress()); 446080efb8cea6255b4f1f373d9cb583d6a6302106bEli Friedman } 447080efb8cea6255b4f1f373d9cb583d6a6302106bEli Friedman 448080efb8cea6255b4f1f373d9cb583d6a6302106bEli Friedman TI->eraseFromParent(); 449080efb8cea6255b4f1f373d9cb583d6a6302106bEli Friedman if (Cond) RecursivelyDeleteTriviallyDeadInstructions(Cond); 450080efb8cea6255b4f1f373d9cb583d6a6302106bEli Friedman} 451080efb8cea6255b4f1f373d9cb583d6a6302106bEli Friedman 4529fd4955c6ab9a191dec2d5afd4b2027d4b906f2eChris Lattner/// isValueEqualityComparison - Return true if the specified terminator checks 4539fd4955c6ab9a191dec2d5afd4b2027d4b906f2eChris Lattner/// to see if a value is equal to constant integer value. 45458e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund OlesenValue *SimplifyCFGOpt::isValueEqualityComparison(TerminatorInst *TI) { 45558e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen Value *CV = 0; 4564bebf08d152d84970d250feec72fb734cb8a5316Chris Lattner if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) { 4574bebf08d152d84970d250feec72fb734cb8a5316Chris Lattner // Do not permit merging of large switch instructions into their 4584bebf08d152d84970d250feec72fb734cb8a5316Chris Lattner // predecessors unless there is only one predecessor. 45958e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen if (SI->getNumSuccessors()*std::distance(pred_begin(SI->getParent()), 46058e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen pred_end(SI->getParent())) <= 128) 46158e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen CV = SI->getCondition(); 46258e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen } else if (BranchInst *BI = dyn_cast<BranchInst>(TI)) 463542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner if (BI->isConditional() && BI->getCondition()->hasOneUse()) 464e4d87aa2de6e52952dca73716386db09aad5a8fdReid Spencer if (ICmpInst *ICI = dyn_cast<ICmpInst>(BI->getCondition())) 465e4d87aa2de6e52952dca73716386db09aad5a8fdReid Spencer if ((ICI->getPredicate() == ICmpInst::ICMP_EQ || 466e4d87aa2de6e52952dca73716386db09aad5a8fdReid Spencer ICI->getPredicate() == ICmpInst::ICMP_NE) && 46728acc135481691771205dea7cb4edbd3927aa764Chris Lattner GetConstantInt(ICI->getOperand(1), TD)) 46858e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen CV = ICI->getOperand(0); 46958e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen 47058e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen // Unwrap any lossless ptrtoint cast. 47158e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen if (TD && CV && CV->getType() == TD->getIntPtrType(CV->getContext())) 47258e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen if (PtrToIntInst *PTII = dyn_cast<PtrToIntInst>(CV)) 47358e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen CV = PTII->getOperand(0); 47458e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen return CV; 475542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner} 476542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner 4775049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// GetValueEqualityComparisonCases - Given a value comparison instruction, 4785049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// decode all of the 'cases' that it represents and return the 'default' block. 47958e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund OlesenBasicBlock *SimplifyCFGOpt:: 480fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha BrukmanGetValueEqualityComparisonCases(TerminatorInst *TI, 481542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner std::vector<std::pair<ConstantInt*, 482542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner BasicBlock*> > &Cases) { 483542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) { 484542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner Cases.reserve(SI->getNumCases()); 485542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner for (unsigned i = 1, e = SI->getNumCases(); i != e; ++i) 486be54dcc8a9d14592e324d6e6ae1322782e17f09fChris Lattner Cases.push_back(std::make_pair(SI->getCaseValue(i), SI->getSuccessor(i))); 487542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner return SI->getDefaultDest(); 488542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner } 489542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner 490542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner BranchInst *BI = cast<BranchInst>(TI); 491e4d87aa2de6e52952dca73716386db09aad5a8fdReid Spencer ICmpInst *ICI = cast<ICmpInst>(BI->getCondition()); 49228acc135481691771205dea7cb4edbd3927aa764Chris Lattner Cases.push_back(std::make_pair(GetConstantInt(ICI->getOperand(1), TD), 493e4d87aa2de6e52952dca73716386db09aad5a8fdReid Spencer BI->getSuccessor(ICI->getPredicate() == 494e4d87aa2de6e52952dca73716386db09aad5a8fdReid Spencer ICmpInst::ICMP_NE))); 495e4d87aa2de6e52952dca73716386db09aad5a8fdReid Spencer return BI->getSuccessor(ICI->getPredicate() == ICmpInst::ICMP_EQ); 496542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner} 497542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner 498542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner 4995049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// EliminateBlockCases - Given a vector of bb/value pairs, remove any entries 5005049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// in the list that match the specified block. 501fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukmanstatic void EliminateBlockCases(BasicBlock *BB, 502623369ac5669a3667a94a3cbba342dea78845615Chris Lattner std::vector<std::pair<ConstantInt*, BasicBlock*> > &Cases) { 503623369ac5669a3667a94a3cbba342dea78845615Chris Lattner for (unsigned i = 0, e = Cases.size(); i != e; ++i) 504623369ac5669a3667a94a3cbba342dea78845615Chris Lattner if (Cases[i].second == BB) { 505623369ac5669a3667a94a3cbba342dea78845615Chris Lattner Cases.erase(Cases.begin()+i); 506623369ac5669a3667a94a3cbba342dea78845615Chris Lattner --i; --e; 507623369ac5669a3667a94a3cbba342dea78845615Chris Lattner } 508623369ac5669a3667a94a3cbba342dea78845615Chris Lattner} 509623369ac5669a3667a94a3cbba342dea78845615Chris Lattner 5105049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// ValuesOverlap - Return true if there are any keys in C1 that exist in C2 as 5115049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// well. 512623369ac5669a3667a94a3cbba342dea78845615Chris Lattnerstatic bool 513623369ac5669a3667a94a3cbba342dea78845615Chris LattnerValuesOverlap(std::vector<std::pair<ConstantInt*, BasicBlock*> > &C1, 514623369ac5669a3667a94a3cbba342dea78845615Chris Lattner std::vector<std::pair<ConstantInt*, BasicBlock*> > &C2) { 515623369ac5669a3667a94a3cbba342dea78845615Chris Lattner std::vector<std::pair<ConstantInt*, BasicBlock*> > *V1 = &C1, *V2 = &C2; 516623369ac5669a3667a94a3cbba342dea78845615Chris Lattner 517623369ac5669a3667a94a3cbba342dea78845615Chris Lattner // Make V1 be smaller than V2. 518623369ac5669a3667a94a3cbba342dea78845615Chris Lattner if (V1->size() > V2->size()) 519623369ac5669a3667a94a3cbba342dea78845615Chris Lattner std::swap(V1, V2); 520623369ac5669a3667a94a3cbba342dea78845615Chris Lattner 521623369ac5669a3667a94a3cbba342dea78845615Chris Lattner if (V1->size() == 0) return false; 522623369ac5669a3667a94a3cbba342dea78845615Chris Lattner if (V1->size() == 1) { 523623369ac5669a3667a94a3cbba342dea78845615Chris Lattner // Just scan V2. 524623369ac5669a3667a94a3cbba342dea78845615Chris Lattner ConstantInt *TheVal = (*V1)[0].first; 525623369ac5669a3667a94a3cbba342dea78845615Chris Lattner for (unsigned i = 0, e = V2->size(); i != e; ++i) 526623369ac5669a3667a94a3cbba342dea78845615Chris Lattner if (TheVal == (*V2)[i].first) 527623369ac5669a3667a94a3cbba342dea78845615Chris Lattner return true; 528623369ac5669a3667a94a3cbba342dea78845615Chris Lattner } 529623369ac5669a3667a94a3cbba342dea78845615Chris Lattner 530623369ac5669a3667a94a3cbba342dea78845615Chris Lattner // Otherwise, just sort both lists and compare element by element. 531fca20f507ccfd3407511cd1ccb94ab4421388107Chris Lattner array_pod_sort(V1->begin(), V1->end()); 532fca20f507ccfd3407511cd1ccb94ab4421388107Chris Lattner array_pod_sort(V2->begin(), V2->end()); 533623369ac5669a3667a94a3cbba342dea78845615Chris Lattner unsigned i1 = 0, i2 = 0, e1 = V1->size(), e2 = V2->size(); 534623369ac5669a3667a94a3cbba342dea78845615Chris Lattner while (i1 != e1 && i2 != e2) { 535623369ac5669a3667a94a3cbba342dea78845615Chris Lattner if ((*V1)[i1].first == (*V2)[i2].first) 536623369ac5669a3667a94a3cbba342dea78845615Chris Lattner return true; 537623369ac5669a3667a94a3cbba342dea78845615Chris Lattner if ((*V1)[i1].first < (*V2)[i2].first) 538623369ac5669a3667a94a3cbba342dea78845615Chris Lattner ++i1; 539623369ac5669a3667a94a3cbba342dea78845615Chris Lattner else 540623369ac5669a3667a94a3cbba342dea78845615Chris Lattner ++i2; 541623369ac5669a3667a94a3cbba342dea78845615Chris Lattner } 542623369ac5669a3667a94a3cbba342dea78845615Chris Lattner return false; 543623369ac5669a3667a94a3cbba342dea78845615Chris Lattner} 544623369ac5669a3667a94a3cbba342dea78845615Chris Lattner 5455049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// SimplifyEqualityComparisonWithOnlyPredecessor - If TI is known to be a 5465049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// terminator instruction and its block is known to only have a single 5475049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// predecessor block, check to see if that predecessor is also a value 5485049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// comparison with the same value, and if that comparison determines the 5495049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// outcome of this comparison. If so, simplify TI. This does a very limited 5505049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// form of jump threading. 55158e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesenbool SimplifyCFGOpt:: 55258e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund OlesenSimplifyEqualityComparisonWithOnlyPredecessor(TerminatorInst *TI, 553007349dafda47296177fd7481aff9764d4179f42Devang Patel BasicBlock *Pred, 554007349dafda47296177fd7481aff9764d4179f42Devang Patel IRBuilder<> &Builder) { 555623369ac5669a3667a94a3cbba342dea78845615Chris Lattner Value *PredVal = isValueEqualityComparison(Pred->getTerminator()); 556623369ac5669a3667a94a3cbba342dea78845615Chris Lattner if (!PredVal) return false; // Not a value comparison in predecessor. 557623369ac5669a3667a94a3cbba342dea78845615Chris Lattner 558623369ac5669a3667a94a3cbba342dea78845615Chris Lattner Value *ThisVal = isValueEqualityComparison(TI); 559623369ac5669a3667a94a3cbba342dea78845615Chris Lattner assert(ThisVal && "This isn't a value comparison!!"); 560623369ac5669a3667a94a3cbba342dea78845615Chris Lattner if (ThisVal != PredVal) return false; // Different predicates. 561623369ac5669a3667a94a3cbba342dea78845615Chris Lattner 562623369ac5669a3667a94a3cbba342dea78845615Chris Lattner // Find out information about when control will move from Pred to TI's block. 563623369ac5669a3667a94a3cbba342dea78845615Chris Lattner std::vector<std::pair<ConstantInt*, BasicBlock*> > PredCases; 564623369ac5669a3667a94a3cbba342dea78845615Chris Lattner BasicBlock *PredDef = GetValueEqualityComparisonCases(Pred->getTerminator(), 565623369ac5669a3667a94a3cbba342dea78845615Chris Lattner PredCases); 566623369ac5669a3667a94a3cbba342dea78845615Chris Lattner EliminateBlockCases(PredDef, PredCases); // Remove default from cases. 567fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukman 568623369ac5669a3667a94a3cbba342dea78845615Chris Lattner // Find information about how control leaves this block. 569623369ac5669a3667a94a3cbba342dea78845615Chris Lattner std::vector<std::pair<ConstantInt*, BasicBlock*> > ThisCases; 570623369ac5669a3667a94a3cbba342dea78845615Chris Lattner BasicBlock *ThisDef = GetValueEqualityComparisonCases(TI, ThisCases); 571623369ac5669a3667a94a3cbba342dea78845615Chris Lattner EliminateBlockCases(ThisDef, ThisCases); // Remove default from cases. 572623369ac5669a3667a94a3cbba342dea78845615Chris Lattner 573623369ac5669a3667a94a3cbba342dea78845615Chris Lattner // If TI's block is the default block from Pred's comparison, potentially 574623369ac5669a3667a94a3cbba342dea78845615Chris Lattner // simplify TI based on this knowledge. 575623369ac5669a3667a94a3cbba342dea78845615Chris Lattner if (PredDef == TI->getParent()) { 576623369ac5669a3667a94a3cbba342dea78845615Chris Lattner // If we are here, we know that the value is none of those cases listed in 577623369ac5669a3667a94a3cbba342dea78845615Chris Lattner // PredCases. If there are any cases in ThisCases that are in PredCases, we 578623369ac5669a3667a94a3cbba342dea78845615Chris Lattner // can simplify TI. 5799a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (!ValuesOverlap(PredCases, ThisCases)) 5809a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner return false; 5819a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner 5829a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (isa<BranchInst>(TI)) { 5839a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // Okay, one of the successors of this condbr is dead. Convert it to a 5849a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // uncond br. 5859a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner assert(ThisCases.size() == 1 && "Branch can only have one case!"); 5869a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // Insert the new branch. 587007349dafda47296177fd7481aff9764d4179f42Devang Patel Instruction *NI = Builder.CreateBr(ThisDef); 5889a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner (void) NI; 589623369ac5669a3667a94a3cbba342dea78845615Chris Lattner 5909a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // Remove PHI node entries for the dead edge. 5919a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner ThisCases[0].second->removePredecessor(TI->getParent()); 592623369ac5669a3667a94a3cbba342dea78845615Chris Lattner 5939a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner DEBUG(dbgs() << "Threading pred instr: " << *Pred->getTerminator() 5949a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner << "Through successor TI: " << *TI << "Leaving: " << *NI << "\n"); 595623369ac5669a3667a94a3cbba342dea78845615Chris Lattner 5969a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner EraseTerminatorInstAndDCECond(TI); 5979a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner return true; 598623369ac5669a3667a94a3cbba342dea78845615Chris Lattner } 5999a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner 6009a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner SwitchInst *SI = cast<SwitchInst>(TI); 6019a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // Okay, TI has cases that are statically dead, prune them away. 6029a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner SmallPtrSet<Constant*, 16> DeadCases; 603623369ac5669a3667a94a3cbba342dea78845615Chris Lattner for (unsigned i = 0, e = PredCases.size(); i != e; ++i) 6049a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner DeadCases.insert(PredCases[i].first); 6059a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner 6069a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner DEBUG(dbgs() << "Threading pred instr: " << *Pred->getTerminator() 6079a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner << "Through successor TI: " << *TI); 6089a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner 6099a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner for (unsigned i = SI->getNumCases()-1; i != 0; --i) 6109a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (DeadCases.count(SI->getCaseValue(i))) { 6119a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner SI->getSuccessor(i)->removePredecessor(TI->getParent()); 6129a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner SI->removeCase(i); 613623369ac5669a3667a94a3cbba342dea78845615Chris Lattner } 614623369ac5669a3667a94a3cbba342dea78845615Chris Lattner 6159a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner DEBUG(dbgs() << "Leaving: " << *TI << "\n"); 6169a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner return true; 6179a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner } 6189a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner 6199a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // Otherwise, TI's block must correspond to some matched value. Find out 6209a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // which value (or set of values) this is. 6219a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner ConstantInt *TIV = 0; 6229a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner BasicBlock *TIBB = TI->getParent(); 6239a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner for (unsigned i = 0, e = PredCases.size(); i != e; ++i) 6249a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (PredCases[i].second == TIBB) { 6259a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (TIV != 0) 6269a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner return false; // Cannot handle multiple values coming to this block. 6279a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner TIV = PredCases[i].first; 6289a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner } 6299a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner assert(TIV && "No edge from pred to succ?"); 6309a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner 6319a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // Okay, we found the one constant that our value can be if we get into TI's 6329a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // BB. Find out which successor will unconditionally be branched to. 6339a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner BasicBlock *TheRealDest = 0; 6349a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner for (unsigned i = 0, e = ThisCases.size(); i != e; ++i) 6359a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (ThisCases[i].first == TIV) { 6369a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner TheRealDest = ThisCases[i].second; 6379a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner break; 6389a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner } 6399a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner 6409a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // If not handled by any explicit cases, it is handled by the default case. 6419a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (TheRealDest == 0) TheRealDest = ThisDef; 642623369ac5669a3667a94a3cbba342dea78845615Chris Lattner 6439a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // Remove PHI node entries for dead edges. 6449a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner BasicBlock *CheckEdge = TheRealDest; 6459a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner for (succ_iterator SI = succ_begin(TIBB), e = succ_end(TIBB); SI != e; ++SI) 6469a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (*SI != CheckEdge) 6479a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner (*SI)->removePredecessor(TIBB); 6489a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner else 6499a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner CheckEdge = 0; 650623369ac5669a3667a94a3cbba342dea78845615Chris Lattner 6519a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // Insert the new branch. 652007349dafda47296177fd7481aff9764d4179f42Devang Patel Instruction *NI = Builder.CreateBr(TheRealDest); 6539a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner (void) NI; 654623369ac5669a3667a94a3cbba342dea78845615Chris Lattner 6559a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner DEBUG(dbgs() << "Threading pred instr: " << *Pred->getTerminator() 6569a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner << "Through successor TI: " << *TI << "Leaving: " << *NI << "\n"); 657623369ac5669a3667a94a3cbba342dea78845615Chris Lattner 6589a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner EraseTerminatorInstAndDCECond(TI); 6599a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner return true; 660623369ac5669a3667a94a3cbba342dea78845615Chris Lattner} 661623369ac5669a3667a94a3cbba342dea78845615Chris Lattner 662c81f5445a7cbe3ba0252aec030082a40e5019eceDale Johannesennamespace { 663c81f5445a7cbe3ba0252aec030082a40e5019eceDale Johannesen /// ConstantIntOrdering - This class implements a stable ordering of constant 664c81f5445a7cbe3ba0252aec030082a40e5019eceDale Johannesen /// integers that does not depend on their address. This is important for 665c81f5445a7cbe3ba0252aec030082a40e5019eceDale Johannesen /// applications that sort ConstantInt's to ensure uniqueness. 666c81f5445a7cbe3ba0252aec030082a40e5019eceDale Johannesen struct ConstantIntOrdering { 667c81f5445a7cbe3ba0252aec030082a40e5019eceDale Johannesen bool operator()(const ConstantInt *LHS, const ConstantInt *RHS) const { 668c81f5445a7cbe3ba0252aec030082a40e5019eceDale Johannesen return LHS->getValue().ult(RHS->getValue()); 669c81f5445a7cbe3ba0252aec030082a40e5019eceDale Johannesen } 670c81f5445a7cbe3ba0252aec030082a40e5019eceDale Johannesen }; 671c81f5445a7cbe3ba0252aec030082a40e5019eceDale Johannesen} 672a9537cf3fcf9fdaac94749db9fbd34912b1f0f08Dale Johannesen 6736d4d21e29d4840236ab6f15c5247379820021d0cChris Lattnerstatic int ConstantIntSortPredicate(const void *P1, const void *P2) { 6746d4d21e29d4840236ab6f15c5247379820021d0cChris Lattner const ConstantInt *LHS = *(const ConstantInt**)P1; 6756d4d21e29d4840236ab6f15c5247379820021d0cChris Lattner const ConstantInt *RHS = *(const ConstantInt**)P2; 676ba3c8155704e5e2ac24b5069c32bca359b0738edChris Lattner if (LHS->getValue().ult(RHS->getValue())) 677ba3c8155704e5e2ac24b5069c32bca359b0738edChris Lattner return 1; 678ba3c8155704e5e2ac24b5069c32bca359b0738edChris Lattner if (LHS->getValue() == RHS->getValue()) 679ba3c8155704e5e2ac24b5069c32bca359b0738edChris Lattner return 0; 680ba3c8155704e5e2ac24b5069c32bca359b0738edChris Lattner return -1; 6816d4d21e29d4840236ab6f15c5247379820021d0cChris Lattner} 6826d4d21e29d4840236ab6f15c5247379820021d0cChris Lattner 6835049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// FoldValueComparisonIntoPredecessors - The specified terminator is a value 6845049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// equality comparison instruction (either a switch or a branch on "X == c"). 6855049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// See if any of the predecessors of the terminator block are value comparisons 6865049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// on the same value. If so, and if safe to do so, fold them together. 687b55d924b1e33341d08b1bead78e86fce56617784Devang Patelbool SimplifyCFGOpt::FoldValueComparisonIntoPredecessors(TerminatorInst *TI, 688b55d924b1e33341d08b1bead78e86fce56617784Devang Patel IRBuilder<> &Builder) { 689542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner BasicBlock *BB = TI->getParent(); 690542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner Value *CV = isValueEqualityComparison(TI); // CondVal 691542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner assert(CV && "Not a comparison?"); 692542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner bool Changed = false; 693542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner 6948244243a31d636ce8838a81d4c402274fd391d2bChris Lattner SmallVector<BasicBlock*, 16> Preds(pred_begin(BB), pred_end(BB)); 695542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner while (!Preds.empty()) { 696e9d87f49063cb1bd213d8e9c339b9b63393cc2d9Dan Gohman BasicBlock *Pred = Preds.pop_back_val(); 697fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukman 698542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // See if the predecessor is a comparison with the same value. 699542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner TerminatorInst *PTI = Pred->getTerminator(); 700542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner Value *PCV = isValueEqualityComparison(PTI); // PredCondVal 701542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner 702542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner if (PCV == CV && SafeToMergeTerminators(TI, PTI)) { 703542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // Figure out which 'cases' to copy from SI to PSI. 704542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner std::vector<std::pair<ConstantInt*, BasicBlock*> > BBCases; 705542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner BasicBlock *BBDefault = GetValueEqualityComparisonCases(TI, BBCases); 706542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner 707542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner std::vector<std::pair<ConstantInt*, BasicBlock*> > PredCases; 708542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner BasicBlock *PredDefault = GetValueEqualityComparisonCases(PTI, PredCases); 709542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner 710542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // Based on whether the default edge from PTI goes to BB or not, fill in 711542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // PredCases and PredDefault with the new switch cases we would like to 712542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // build. 7138244243a31d636ce8838a81d4c402274fd391d2bChris Lattner SmallVector<BasicBlock*, 8> NewSuccessors; 714542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner 715542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner if (PredDefault == BB) { 716542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // If this is the default destination from PTI, only the edges in TI 717542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // that don't occur in PTI, or that branch to BB will be activated. 718c81f5445a7cbe3ba0252aec030082a40e5019eceDale Johannesen std::set<ConstantInt*, ConstantIntOrdering> PTIHandled; 719542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner for (unsigned i = 0, e = PredCases.size(); i != e; ++i) 720542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner if (PredCases[i].second != BB) 721542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner PTIHandled.insert(PredCases[i].first); 722542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner else { 723542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // The default destination is BB, we don't need explicit targets. 724542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner std::swap(PredCases[i], PredCases.back()); 725542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner PredCases.pop_back(); 726542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner --i; --e; 727542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner } 728542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner 729542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // Reconstruct the new switch statement we will be building. 730542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner if (PredDefault != BBDefault) { 731542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner PredDefault->removePredecessor(Pred); 732542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner PredDefault = BBDefault; 733542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner NewSuccessors.push_back(BBDefault); 734542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner } 735542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner for (unsigned i = 0, e = BBCases.size(); i != e; ++i) 736542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner if (!PTIHandled.count(BBCases[i].first) && 737542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner BBCases[i].second != BBDefault) { 738542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner PredCases.push_back(BBCases[i]); 739542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner NewSuccessors.push_back(BBCases[i].second); 740542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner } 741542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner 742542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner } else { 743542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // If this is not the default destination from PSI, only the edges 744542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // in SI that occur in PSI with a destination of BB will be 745542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // activated. 746c81f5445a7cbe3ba0252aec030082a40e5019eceDale Johannesen std::set<ConstantInt*, ConstantIntOrdering> PTIHandled; 747542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner for (unsigned i = 0, e = PredCases.size(); i != e; ++i) 748542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner if (PredCases[i].second == BB) { 749542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner PTIHandled.insert(PredCases[i].first); 750542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner std::swap(PredCases[i], PredCases.back()); 751542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner PredCases.pop_back(); 752542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner --i; --e; 753542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner } 754542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner 755542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // Okay, now we know which constants were sent to BB from the 756542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // predecessor. Figure out where they will all go now. 757542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner for (unsigned i = 0, e = BBCases.size(); i != e; ++i) 758542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner if (PTIHandled.count(BBCases[i].first)) { 759542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // If this is one we are capable of getting... 760542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner PredCases.push_back(BBCases[i]); 761542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner NewSuccessors.push_back(BBCases[i].second); 762542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner PTIHandled.erase(BBCases[i].first);// This constant is taken care of 763542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner } 764542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner 765542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // If there are any constants vectored to BB that TI doesn't handle, 766542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // they must go to the default destination of TI. 767c81f5445a7cbe3ba0252aec030082a40e5019eceDale Johannesen for (std::set<ConstantInt*, ConstantIntOrdering>::iterator I = 768c81f5445a7cbe3ba0252aec030082a40e5019eceDale Johannesen PTIHandled.begin(), 769542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner E = PTIHandled.end(); I != E; ++I) { 770542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner PredCases.push_back(std::make_pair(*I, BBDefault)); 771542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner NewSuccessors.push_back(BBDefault); 772542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner } 773542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner } 774542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner 775542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // Okay, at this point, we know which new successor Pred will get. Make 776542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // sure we update the number of entries in the PHI nodes for these 777542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // successors. 778542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner for (unsigned i = 0, e = NewSuccessors.size(); i != e; ++i) 779542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner AddPredecessorToBlock(NewSuccessors[i], Pred, BB); 780542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner 781b55d924b1e33341d08b1bead78e86fce56617784Devang Patel Builder.SetInsertPoint(PTI); 78258e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen // Convert pointer to int before we switch. 7831df9859c40492511b8aa4321eb76496005d3b75bDuncan Sands if (CV->getType()->isPointerTy()) { 78458e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen assert(TD && "Cannot switch on pointer without TargetData"); 785b55d924b1e33341d08b1bead78e86fce56617784Devang Patel CV = Builder.CreatePtrToInt(CV, TD->getIntPtrType(CV->getContext()), 786b55d924b1e33341d08b1bead78e86fce56617784Devang Patel "magicptr"); 78758e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen } 78858e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen 789542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // Now that the successors are updated, create the new Switch instruction. 790b55d924b1e33341d08b1bead78e86fce56617784Devang Patel SwitchInst *NewSI = Builder.CreateSwitch(CV, PredDefault, 791b55d924b1e33341d08b1bead78e86fce56617784Devang Patel PredCases.size()); 792d80e8ed2fa20c7ad51af49c3b2650525edbdcd08Devang Patel NewSI->setDebugLoc(PTI->getDebugLoc()); 793542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner for (unsigned i = 0, e = PredCases.size(); i != e; ++i) 794542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner NewSI->addCase(PredCases[i].first, PredCases[i].second); 79513b2f764c041e15af3d6033826deb9c7e669ca97Chris Lattner 796080efb8cea6255b4f1f373d9cb583d6a6302106bEli Friedman EraseTerminatorInstAndDCECond(PTI); 79713b2f764c041e15af3d6033826deb9c7e669ca97Chris Lattner 798542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // Okay, last check. If BB is still a successor of PSI, then we must 799542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // have an infinite loop case. If so, add an infinitely looping block 800542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // to handle the case to preserve the behavior of the code. 801542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner BasicBlock *InfLoopBlock = 0; 802542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner for (unsigned i = 0, e = NewSI->getNumSuccessors(); i != e; ++i) 803542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner if (NewSI->getSuccessor(i) == BB) { 804542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner if (InfLoopBlock == 0) { 805093a4385027235459ab6972b2e2fdc79061773cfChris Lattner // Insert it at the end of the function, because it's either code, 806542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // or it won't matter if it's hot. :) 8071d0be15f89cb5056e20e2d24faa8d6afb1573bcaOwen Anderson InfLoopBlock = BasicBlock::Create(BB->getContext(), 8081d0be15f89cb5056e20e2d24faa8d6afb1573bcaOwen Anderson "infloop", BB->getParent()); 809051a950000e21935165db56695e35bade668193bGabor Greif BranchInst::Create(InfLoopBlock, InfLoopBlock); 810542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner } 811542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner NewSI->setSuccessor(i, InfLoopBlock); 812542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner } 813fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukman 814542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner Changed = true; 815542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner } 816542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner } 817542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner return Changed; 818542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner} 819542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner 820c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen// isSafeToHoistInvoke - If we would need to insert a select that uses the 821c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen// value of this invoke (comments in HoistThenElseCodeToIf explain why we 822c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen// would need to do this), we can't hoist the invoke, as there is nowhere 823c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen// to put the select in this case. 824c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesenstatic bool isSafeToHoistInvoke(BasicBlock *BB1, BasicBlock *BB2, 825c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen Instruction *I1, Instruction *I2) { 826c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen for (succ_iterator SI = succ_begin(BB1), E = succ_end(BB1); SI != E; ++SI) { 827c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen PHINode *PN; 828c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen for (BasicBlock::iterator BBI = SI->begin(); 829c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen (PN = dyn_cast<PHINode>(BBI)); ++BBI) { 830c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen Value *BB1V = PN->getIncomingValueForBlock(BB1); 831c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen Value *BB2V = PN->getIncomingValueForBlock(BB2); 832c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen if (BB1V != BB2V && (BB1V==I1 || BB2V==I2)) { 833c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen return false; 834c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen } 835c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen } 836c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen } 837c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen return true; 838c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen} 839c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen 8406306d07aa8cf71e3c7fed7f295665f53595473ebChris Lattner/// HoistThenElseCodeToIf - Given a conditional branch that goes to BB1 and 84137dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner/// BB2, hoist any common code in the two blocks up into the branch block. The 84237dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner/// caller of this function guarantees that BI's block dominates BB1 and BB2. 843216dde91d1def3e08002d6251e11f3dfa5cb3656Rafael Espindolastatic bool HoistThenElseCodeToIf(BranchInst *BI) { 84437dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner // This does very trivial matching, with limited scanning, to find identical 84537dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner // instructions in the two blocks. In particular, we don't want to get into 84637dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner // O(M*N) situations here where M and N are the sizes of BB1 and BB2. As 84737dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner // such, we currently just scan for obviously identical instructions in an 84837dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner // identical order. 84937dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner BasicBlock *BB1 = BI->getSuccessor(0); // The true destination. 85037dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner BasicBlock *BB2 = BI->getSuccessor(1); // The false destination 85137dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner 85265085cf7b3470b7b087f5fd7b0497879b90b32baDevang Patel BasicBlock::iterator BB1_Itr = BB1->begin(); 85365085cf7b3470b7b087f5fd7b0497879b90b32baDevang Patel BasicBlock::iterator BB2_Itr = BB2->begin(); 85465085cf7b3470b7b087f5fd7b0497879b90b32baDevang Patel 85565085cf7b3470b7b087f5fd7b0497879b90b32baDevang Patel Instruction *I1 = BB1_Itr++, *I2 = BB2_Itr++; 856949666ea16214e1b7e79fc8e653b06ad8b93dd5aDevang Patel // Skip debug info if it is not identical. 857949666ea16214e1b7e79fc8e653b06ad8b93dd5aDevang Patel DbgInfoIntrinsic *DBI1 = dyn_cast<DbgInfoIntrinsic>(I1); 858949666ea16214e1b7e79fc8e653b06ad8b93dd5aDevang Patel DbgInfoIntrinsic *DBI2 = dyn_cast<DbgInfoIntrinsic>(I2); 859949666ea16214e1b7e79fc8e653b06ad8b93dd5aDevang Patel if (!DBI1 || !DBI2 || !DBI1->isIdenticalToWhenDefined(DBI2)) { 860949666ea16214e1b7e79fc8e653b06ad8b93dd5aDevang Patel while (isa<DbgInfoIntrinsic>(I1)) 861949666ea16214e1b7e79fc8e653b06ad8b93dd5aDevang Patel I1 = BB1_Itr++; 862949666ea16214e1b7e79fc8e653b06ad8b93dd5aDevang Patel while (isa<DbgInfoIntrinsic>(I2)) 863949666ea16214e1b7e79fc8e653b06ad8b93dd5aDevang Patel I2 = BB2_Itr++; 864949666ea16214e1b7e79fc8e653b06ad8b93dd5aDevang Patel } 865ae6c95b58e78403707fb75e78f0959a86d57b0c5Devang Patel if (isa<PHINode>(I1) || !I1->isIdenticalToWhenDefined(I2) || 866c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen (isa<InvokeInst>(I1) && !isSafeToHoistInvoke(BB1, BB2, I1, I2))) 86737dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner return false; 86837dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner 86937dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner // If we get here, we can hoist at least one instruction. 87037dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner BasicBlock *BIParent = BI->getParent(); 87137dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner 87237dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner do { 87337dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner // If we are hoisting the terminator instruction, don't move one (making a 87437dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner // broken BB), instead clone it, and remove BI. 87537dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner if (isa<TerminatorInst>(I1)) 87637dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner goto HoistTerminator; 877fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukman 87837dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner // For a normal instruction, we just move one to right before the branch, 87937dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner // then replace all uses of the other with the first. Finally, we remove 88037dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner // the now redundant second instruction. 88137dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner BIParent->getInstList().splice(BI, BB1->getInstList(), I1); 88237dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner if (!I2->use_empty()) 88337dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner I2->replaceAllUsesWith(I1); 88458cfa3b13752579c86cf85270d49f9ced0942f2fDan Gohman I1->intersectOptionalDataWith(I2); 885302ba6fc1cb26248b0d6524fc42c740370926d6dChris Lattner I2->eraseFromParent(); 886fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukman 88765085cf7b3470b7b087f5fd7b0497879b90b32baDevang Patel I1 = BB1_Itr++; 88865085cf7b3470b7b087f5fd7b0497879b90b32baDevang Patel I2 = BB2_Itr++; 889949666ea16214e1b7e79fc8e653b06ad8b93dd5aDevang Patel // Skip debug info if it is not identical. 890949666ea16214e1b7e79fc8e653b06ad8b93dd5aDevang Patel DbgInfoIntrinsic *DBI1 = dyn_cast<DbgInfoIntrinsic>(I1); 891949666ea16214e1b7e79fc8e653b06ad8b93dd5aDevang Patel DbgInfoIntrinsic *DBI2 = dyn_cast<DbgInfoIntrinsic>(I2); 892949666ea16214e1b7e79fc8e653b06ad8b93dd5aDevang Patel if (!DBI1 || !DBI2 || !DBI1->isIdenticalToWhenDefined(DBI2)) { 893949666ea16214e1b7e79fc8e653b06ad8b93dd5aDevang Patel while (isa<DbgInfoIntrinsic>(I1)) 894949666ea16214e1b7e79fc8e653b06ad8b93dd5aDevang Patel I1 = BB1_Itr++; 895949666ea16214e1b7e79fc8e653b06ad8b93dd5aDevang Patel while (isa<DbgInfoIntrinsic>(I2)) 896949666ea16214e1b7e79fc8e653b06ad8b93dd5aDevang Patel I2 = BB2_Itr++; 897949666ea16214e1b7e79fc8e653b06ad8b93dd5aDevang Patel } 898ae6c95b58e78403707fb75e78f0959a86d57b0c5Devang Patel } while (I1->isIdenticalToWhenDefined(I2)); 89937dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner 90037dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner return true; 90137dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner 90237dc938bbe556a9414d063196d367c2f75d07d95Chris LattnerHoistTerminator: 903c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen // It may not be possible to hoist an invoke. 904c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen if (isa<InvokeInst>(I1) && !isSafeToHoistInvoke(BB1, BB2, I1, I2)) 905c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen return true; 906c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen 90737dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner // Okay, it is safe to hoist the terminator. 9086776064d190701c5bae4d5403939eed2e480d1cdNick Lewycky Instruction *NT = I1->clone(); 90937dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner BIParent->getInstList().insert(BI, NT); 910f012705c7e4ca8cf90b6b734ce1d5355daca5ba5Benjamin Kramer if (!NT->getType()->isVoidTy()) { 91137dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner I1->replaceAllUsesWith(NT); 91237dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner I2->replaceAllUsesWith(NT); 91386cc42355593dd1689f7d58d56695c451215b02bChris Lattner NT->takeName(I1); 91437dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner } 91537dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner 916d3a1788da15311781f661c1cbfe48cd5f98ae778Devang Patel IRBuilder<true, NoFolder> Builder(NT); 91737dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner // Hoisting one of the terminators from our successor is a great thing. 91837dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner // Unfortunately, the successors of the if/else blocks may have PHI nodes in 91937dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner // them. If they do, all PHI entries for BB1/BB2 must agree for all PHI 92037dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner // nodes, so we insert select instruction to compute the final result. 92137dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner std::map<std::pair<Value*,Value*>, SelectInst*> InsertedSelects; 92237dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner for (succ_iterator SI = succ_begin(BB1), E = succ_end(BB1); SI != E; ++SI) { 92337dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner PHINode *PN; 92437dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner for (BasicBlock::iterator BBI = SI->begin(); 9250f535c6fa8b03491dc110feb65d78922ee29d1fcChris Lattner (PN = dyn_cast<PHINode>(BBI)); ++BBI) { 92637dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner Value *BB1V = PN->getIncomingValueForBlock(BB1); 92737dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner Value *BB2V = PN->getIncomingValueForBlock(BB2); 9289a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (BB1V == BB2V) continue; 9299a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner 9309a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // These values do not agree. Insert a select instruction before NT 9319a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // that determines the right value. 9329a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner SelectInst *&SI = InsertedSelects[std::make_pair(BB1V, BB2V)]; 933d3a1788da15311781f661c1cbfe48cd5f98ae778Devang Patel if (SI == 0) 934d3a1788da15311781f661c1cbfe48cd5f98ae778Devang Patel SI = cast<SelectInst> 935d3a1788da15311781f661c1cbfe48cd5f98ae778Devang Patel (Builder.CreateSelect(BI->getCondition(), BB1V, BB2V, 936d3a1788da15311781f661c1cbfe48cd5f98ae778Devang Patel BB1V->getName()+"."+BB2V->getName())); 937d3a1788da15311781f661c1cbfe48cd5f98ae778Devang Patel 9389a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // Make the PHI node use the select for all incoming values for BB1/BB2 9399a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) 9409a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (PN->getIncomingBlock(i) == BB1 || PN->getIncomingBlock(i) == BB2) 9419a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner PN->setIncomingValue(i, SI); 94237dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner } 94337dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner } 94437dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner 94537dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner // Update any PHI nodes in our new successors. 94637dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner for (succ_iterator SI = succ_begin(BB1), E = succ_end(BB1); SI != E; ++SI) 94737dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner AddPredecessorToBlock(*SI, BIParent, BB1); 948fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukman 949080efb8cea6255b4f1f373d9cb583d6a6302106bEli Friedman EraseTerminatorInstAndDCECond(BI); 95037dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner return true; 95137dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner} 95237dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner 9534d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng/// SpeculativelyExecuteBB - Given a conditional branch that goes to BB1 9544d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng/// and an BB2 and the only successor of BB1 is BB2, hoist simple code 9554d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng/// (for now, restricted to a single instruction that's side effect free) from 9564d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng/// the BB1 into the branch block to speculatively execute it. 957216dde91d1def3e08002d6251e11f3dfa5cb3656Rafael Espindolastatic bool SpeculativelyExecuteBB(BranchInst *BI, BasicBlock *BB1) { 9584d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // Only speculatively execution a single instruction (not counting the 9594d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // terminator) for now. 96006b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel Instruction *HInst = NULL; 96106b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel Instruction *Term = BB1->getTerminator(); 96206b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel for (BasicBlock::iterator BBI = BB1->begin(), BBE = BB1->end(); 96306b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel BBI != BBE; ++BBI) { 96406b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel Instruction *I = BBI; 96506b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel // Skip debug info. 9669a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (isa<DbgInfoIntrinsic>(I)) continue; 9679a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (I == Term) break; 96806b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel 9699a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (HInst) 97006b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel return false; 9719a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner HInst = I; 97206b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel } 97306b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel if (!HInst) 97406b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel return false; 9754d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng 976797d95188d00963a835db9ad66dd3c4a54aa2fafEvan Cheng // Be conservative for now. FP select instruction can often be expensive. 977797d95188d00963a835db9ad66dd3c4a54aa2fafEvan Cheng Value *BrCond = BI->getCondition(); 9789a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (isa<FCmpInst>(BrCond)) 979797d95188d00963a835db9ad66dd3c4a54aa2fafEvan Cheng return false; 980797d95188d00963a835db9ad66dd3c4a54aa2fafEvan Cheng 9814d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // If BB1 is actually on the false edge of the conditional branch, remember 9824d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // to swap the select operands later. 9834d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng bool Invert = false; 9844d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng if (BB1 != BI->getSuccessor(0)) { 9854d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng assert(BB1 == BI->getSuccessor(1) && "No edge from 'if' block?"); 9864d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng Invert = true; 9874d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng } 9884d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng 9894d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // Turn 9904d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // BB: 9914d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // %t1 = icmp 9924d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // br i1 %t1, label %BB1, label %BB2 9934d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // BB1: 9944d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // %t3 = add %t2, c 9954d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // br label BB2 9964d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // BB2: 9974d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // => 9984d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // BB: 9994d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // %t1 = icmp 10004d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // %t4 = add %t2, c 10014d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // %t3 = select i1 %t1, %t2, %t3 100206b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel switch (HInst->getOpcode()) { 10034d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng default: return false; // Not safe / profitable to hoist. 10044d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng case Instruction::Add: 10054d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng case Instruction::Sub: 1006ae3a0be92e33bc716722aa600983fc1535acb122Dan Gohman // Not worth doing for vector ops. 10071df9859c40492511b8aa4321eb76496005d3b75bDuncan Sands if (HInst->getType()->isVectorTy()) 10089dd3b610dcb17f88ed52ae03022179bf21e0e132Chris Lattner return false; 10099dd3b610dcb17f88ed52ae03022179bf21e0e132Chris Lattner break; 10104d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng case Instruction::And: 10114d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng case Instruction::Or: 10124d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng case Instruction::Xor: 10134d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng case Instruction::Shl: 10144d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng case Instruction::LShr: 10154d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng case Instruction::AShr: 10169dd3b610dcb17f88ed52ae03022179bf21e0e132Chris Lattner // Don't mess with vector operations. 10171df9859c40492511b8aa4321eb76496005d3b75bDuncan Sands if (HInst->getType()->isVectorTy()) 1018e5334ea518e3dffec4037ede97433eb700fa1d26Evan Cheng return false; 10194d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng break; // These are all cheap and non-trapping instructions. 10204d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng } 10216fe73bbcf3b6c1ddfd5e70e8b5188f8df439ace6Chris Lattner 10226fe73bbcf3b6c1ddfd5e70e8b5188f8df439ace6Chris Lattner // If the instruction is obviously dead, don't try to predicate it. 102306b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel if (HInst->use_empty()) { 102406b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel HInst->eraseFromParent(); 10256fe73bbcf3b6c1ddfd5e70e8b5188f8df439ace6Chris Lattner return true; 10266fe73bbcf3b6c1ddfd5e70e8b5188f8df439ace6Chris Lattner } 10274d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng 10284d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // Can we speculatively execute the instruction? And what is the value 10294d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // if the condition is false? Consider the phi uses, if the incoming value 10304d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // from the "if" block are all the same V, then V is the value of the 10314d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // select if the condition is false. 10324d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng BasicBlock *BIParent = BI->getParent(); 10334d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng SmallVector<PHINode*, 4> PHIUses; 10344d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng Value *FalseV = NULL; 10356fe73bbcf3b6c1ddfd5e70e8b5188f8df439ace6Chris Lattner 10366fe73bbcf3b6c1ddfd5e70e8b5188f8df439ace6Chris Lattner BasicBlock *BB2 = BB1->getTerminator()->getSuccessor(0); 103706b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel for (Value::use_iterator UI = HInst->use_begin(), E = HInst->use_end(); 10384d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng UI != E; ++UI) { 10396fe73bbcf3b6c1ddfd5e70e8b5188f8df439ace6Chris Lattner // Ignore any user that is not a PHI node in BB2. These can only occur in 10406fe73bbcf3b6c1ddfd5e70e8b5188f8df439ace6Chris Lattner // unreachable blocks, because they would not be dominated by the instr. 104120361b9d4d9988d7bfa2112650971642cf81d13eGabor Greif PHINode *PN = dyn_cast<PHINode>(*UI); 10426fe73bbcf3b6c1ddfd5e70e8b5188f8df439ace6Chris Lattner if (!PN || PN->getParent() != BB2) 10436fe73bbcf3b6c1ddfd5e70e8b5188f8df439ace6Chris Lattner return false; 10444d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng PHIUses.push_back(PN); 10456fe73bbcf3b6c1ddfd5e70e8b5188f8df439ace6Chris Lattner 10464d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng Value *PHIV = PN->getIncomingValueForBlock(BIParent); 10474d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng if (!FalseV) 10484d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng FalseV = PHIV; 10494d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng else if (FalseV != PHIV) 10506fe73bbcf3b6c1ddfd5e70e8b5188f8df439ace6Chris Lattner return false; // Inconsistent value when condition is false. 10514d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng } 10526fe73bbcf3b6c1ddfd5e70e8b5188f8df439ace6Chris Lattner 10536fe73bbcf3b6c1ddfd5e70e8b5188f8df439ace6Chris Lattner assert(FalseV && "Must have at least one user, and it must be a PHI"); 10544d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng 1055502a4f5162498ec420e3cb22f667808d726dd7daEvan Cheng // Do not hoist the instruction if any of its operands are defined but not 1056502a4f5162498ec420e3cb22f667808d726dd7daEvan Cheng // used in this BB. The transformation will prevent the operand from 1057502a4f5162498ec420e3cb22f667808d726dd7daEvan Cheng // being sunk into the use block. 105806b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel for (User::op_iterator i = HInst->op_begin(), e = HInst->op_end(); 105906b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel i != e; ++i) { 1060502a4f5162498ec420e3cb22f667808d726dd7daEvan Cheng Instruction *OpI = dyn_cast<Instruction>(*i); 1061502a4f5162498ec420e3cb22f667808d726dd7daEvan Cheng if (OpI && OpI->getParent() == BIParent && 1062502a4f5162498ec420e3cb22f667808d726dd7daEvan Cheng !OpI->isUsedInBasicBlock(BIParent)) 1063502a4f5162498ec420e3cb22f667808d726dd7daEvan Cheng return false; 1064502a4f5162498ec420e3cb22f667808d726dd7daEvan Cheng } 1065502a4f5162498ec420e3cb22f667808d726dd7daEvan Cheng 10663d0a9a371c0ce3a46e845a7bf1f1acb7a1cf523eDevang Patel // If we get here, we can hoist the instruction. Try to place it 1067990afedb3a4b7d32832d74ad5b5863c19f909e1fDale Johannesen // before the icmp instruction preceding the conditional branch. 10683d0a9a371c0ce3a46e845a7bf1f1acb7a1cf523eDevang Patel BasicBlock::iterator InsertPos = BI; 1069990afedb3a4b7d32832d74ad5b5863c19f909e1fDale Johannesen if (InsertPos != BIParent->begin()) 1070990afedb3a4b7d32832d74ad5b5863c19f909e1fDale Johannesen --InsertPos; 1071990afedb3a4b7d32832d74ad5b5863c19f909e1fDale Johannesen // Skip debug info between condition and branch. 1072990afedb3a4b7d32832d74ad5b5863c19f909e1fDale Johannesen while (InsertPos != BIParent->begin() && isa<DbgInfoIntrinsic>(InsertPos)) 10733d0a9a371c0ce3a46e845a7bf1f1acb7a1cf523eDevang Patel --InsertPos; 107420da1f07dac4d771e55ee5c7f105ccedfa4caaaaDevang Patel if (InsertPos == BrCond && !isa<PHINode>(BrCond)) { 10753d0a9a371c0ce3a46e845a7bf1f1acb7a1cf523eDevang Patel SmallPtrSet<Instruction *, 4> BB1Insns; 10763d0a9a371c0ce3a46e845a7bf1f1acb7a1cf523eDevang Patel for(BasicBlock::iterator BB1I = BB1->begin(), BB1E = BB1->end(); 10773d0a9a371c0ce3a46e845a7bf1f1acb7a1cf523eDevang Patel BB1I != BB1E; ++BB1I) 10783d0a9a371c0ce3a46e845a7bf1f1acb7a1cf523eDevang Patel BB1Insns.insert(BB1I); 10793d0a9a371c0ce3a46e845a7bf1f1acb7a1cf523eDevang Patel for(Value::use_iterator UI = BrCond->use_begin(), UE = BrCond->use_end(); 10803d0a9a371c0ce3a46e845a7bf1f1acb7a1cf523eDevang Patel UI != UE; ++UI) { 10813d0a9a371c0ce3a46e845a7bf1f1acb7a1cf523eDevang Patel Instruction *Use = cast<Instruction>(*UI); 10829a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (!BB1Insns.count(Use)) continue; 10839a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner 10849a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // If BrCond uses the instruction that place it just before 10859a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // branch instruction. 10869a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner InsertPos = BI; 10879a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner break; 10883d0a9a371c0ce3a46e845a7bf1f1acb7a1cf523eDevang Patel } 10893d0a9a371c0ce3a46e845a7bf1f1acb7a1cf523eDevang Patel } else 10903d0a9a371c0ce3a46e845a7bf1f1acb7a1cf523eDevang Patel InsertPos = BI; 109106b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel BIParent->getInstList().splice(InsertPos, BB1->getInstList(), HInst); 10924d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng 10934d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // Create a select whose true value is the speculatively executed value and 10944d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // false value is the previously determined FalseV. 1095d3a1788da15311781f661c1cbfe48cd5f98ae778Devang Patel IRBuilder<true, NoFolder> Builder(BI); 10964d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng SelectInst *SI; 10974d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng if (Invert) 1098d3a1788da15311781f661c1cbfe48cd5f98ae778Devang Patel SI = cast<SelectInst> 1099d3a1788da15311781f661c1cbfe48cd5f98ae778Devang Patel (Builder.CreateSelect(BrCond, FalseV, HInst, 1100d3a1788da15311781f661c1cbfe48cd5f98ae778Devang Patel FalseV->getName() + "." + HInst->getName())); 11014d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng else 1102d3a1788da15311781f661c1cbfe48cd5f98ae778Devang Patel SI = cast<SelectInst> 1103d3a1788da15311781f661c1cbfe48cd5f98ae778Devang Patel (Builder.CreateSelect(BrCond, HInst, FalseV, 1104d3a1788da15311781f661c1cbfe48cd5f98ae778Devang Patel HInst->getName() + "." + FalseV->getName())); 11054d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng 11064d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // Make the PHI node use the select for all incoming values for "then" and 11074d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // "if" blocks. 11084d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng for (unsigned i = 0, e = PHIUses.size(); i != e; ++i) { 11094d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng PHINode *PN = PHIUses[i]; 11104d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng for (unsigned j = 0, ee = PN->getNumIncomingValues(); j != ee; ++j) 11119a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (PN->getIncomingBlock(j) == BB1 || PN->getIncomingBlock(j) == BIParent) 11124d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng PN->setIncomingValue(j, SI); 11134d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng } 11144d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng 1115502a4f5162498ec420e3cb22f667808d726dd7daEvan Cheng ++NumSpeculations; 11164d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng return true; 11174d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng} 11184d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng 11192e42e36698d5a34f1952ca3389f1973a6a1166f2Chris Lattner/// BlockIsSimpleEnoughToThreadThrough - Return true if we can thread a branch 11202e42e36698d5a34f1952ca3389f1973a6a1166f2Chris Lattner/// across this block. 11212e42e36698d5a34f1952ca3389f1973a6a1166f2Chris Lattnerstatic bool BlockIsSimpleEnoughToThreadThrough(BasicBlock *BB) { 11222e42e36698d5a34f1952ca3389f1973a6a1166f2Chris Lattner BranchInst *BI = cast<BranchInst>(BB->getTerminator()); 1123e9487f0dc8c6d15cb257d5b49fa96ed436d32f5fChris Lattner unsigned Size = 0; 1124e9487f0dc8c6d15cb257d5b49fa96ed436d32f5fChris Lattner 11259200c89968e52a590ee0b96092a0a589aa138a6fDevang Patel for (BasicBlock::iterator BBI = BB->begin(); &*BBI != BI; ++BBI) { 11268483e54837ede5dd40c5561f15c6a663e2bee87cDale Johannesen if (isa<DbgInfoIntrinsic>(BBI)) 11278483e54837ede5dd40c5561f15c6a663e2bee87cDale Johannesen continue; 1128e9487f0dc8c6d15cb257d5b49fa96ed436d32f5fChris Lattner if (Size > 10) return false; // Don't clone large BB's. 11298483e54837ede5dd40c5561f15c6a663e2bee87cDale Johannesen ++Size; 11302e42e36698d5a34f1952ca3389f1973a6a1166f2Chris Lattner 11318483e54837ede5dd40c5561f15c6a663e2bee87cDale Johannesen // We can only support instructions that do not define values that are 1132e9487f0dc8c6d15cb257d5b49fa96ed436d32f5fChris Lattner // live outside of the current basic block. 1133e9487f0dc8c6d15cb257d5b49fa96ed436d32f5fChris Lattner for (Value::use_iterator UI = BBI->use_begin(), E = BBI->use_end(); 1134e9487f0dc8c6d15cb257d5b49fa96ed436d32f5fChris Lattner UI != E; ++UI) { 1135e9487f0dc8c6d15cb257d5b49fa96ed436d32f5fChris Lattner Instruction *U = cast<Instruction>(*UI); 1136e9487f0dc8c6d15cb257d5b49fa96ed436d32f5fChris Lattner if (U->getParent() != BB || isa<PHINode>(U)) return false; 1137e9487f0dc8c6d15cb257d5b49fa96ed436d32f5fChris Lattner } 11382e42e36698d5a34f1952ca3389f1973a6a1166f2Chris Lattner 11392e42e36698d5a34f1952ca3389f1973a6a1166f2Chris Lattner // Looks ok, continue checking. 11402e42e36698d5a34f1952ca3389f1973a6a1166f2Chris Lattner } 1141e9487f0dc8c6d15cb257d5b49fa96ed436d32f5fChris Lattner 11422e42e36698d5a34f1952ca3389f1973a6a1166f2Chris Lattner return true; 11432e42e36698d5a34f1952ca3389f1973a6a1166f2Chris Lattner} 11442e42e36698d5a34f1952ca3389f1973a6a1166f2Chris Lattner 1145eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner/// FoldCondBranchOnPHI - If we have a conditional branch on a PHI node value 1146eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner/// that is defined in the same block as the branch and if any PHI entries are 1147eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner/// constants, thread edges corresponding to that entry to be branches to their 1148eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner/// ultimate destination. 1149302ba6fc1cb26248b0d6524fc42c740370926d6dChris Lattnerstatic bool FoldCondBranchOnPHI(BranchInst *BI, const TargetData *TD) { 1150eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner BasicBlock *BB = BI->getParent(); 1151eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner PHINode *PN = dyn_cast<PHINode>(BI->getCondition()); 11529c88d9816246d260b37cdc689f313c56aec6941eChris Lattner // NOTE: we currently cannot transform this case if the PHI node is used 11539c88d9816246d260b37cdc689f313c56aec6941eChris Lattner // outside of the block. 11542e42e36698d5a34f1952ca3389f1973a6a1166f2Chris Lattner if (!PN || PN->getParent() != BB || !PN->hasOneUse()) 11552e42e36698d5a34f1952ca3389f1973a6a1166f2Chris Lattner return false; 1156eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner 1157eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner // Degenerate case of a single entry PHI. 1158eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner if (PN->getNumIncomingValues() == 1) { 115929874e0dc6c4e55bc384611273343bb358982cc3Chris Lattner FoldSingleEntryPHINodes(PN->getParent()); 1160eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner return true; 1161eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner } 1162eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner 1163eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner // Now we know that this block has multiple preds and two succs. 11642e42e36698d5a34f1952ca3389f1973a6a1166f2Chris Lattner if (!BlockIsSimpleEnoughToThreadThrough(BB)) return false; 1165eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner 1166eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner // Okay, this is a simple enough basic block. See if any phi values are 1167eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner // constants. 11686b6b6ef1677fa71b1072c2911b4c1f9524a558c9Zhou Sheng for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) { 11699a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner ConstantInt *CB = dyn_cast<ConstantInt>(PN->getIncomingValue(i)); 11709a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (CB == 0 || !CB->getType()->isIntegerTy(1)) continue; 11719a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner 11729a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // Okay, we now know that all edges from PredBB should be revectored to 11739a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // branch to RealDest. 11749a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner BasicBlock *PredBB = PN->getIncomingBlock(i); 11759a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner BasicBlock *RealDest = BI->getSuccessor(!CB->getZExtValue()); 11769a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner 11779a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (RealDest == BB) continue; // Skip self loops. 11786a648b8538bb4d4b3e96669ef8cd3a4ce3aedeb8Bill Wendling // Skip if the predecessor's terminator is an indirect branch. 11796a648b8538bb4d4b3e96669ef8cd3a4ce3aedeb8Bill Wendling if (isa<IndirectBrInst>(PredBB->getTerminator())) continue; 11809a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner 11819a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // The dest block might have PHI nodes, other predecessors and other 11829a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // difficult cases. Instead of being smart about this, just insert a new 11839a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // block that jumps to the destination block, effectively splitting 11849a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // the edge we are about to create. 11859a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner BasicBlock *EdgeBB = BasicBlock::Create(BB->getContext(), 11869a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner RealDest->getName()+".critedge", 11879a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner RealDest->getParent(), RealDest); 11889a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner BranchInst::Create(RealDest, EdgeBB); 11896de0a28dfb84095ebd7775f371dd4085cf955076Chris Lattner 11906de0a28dfb84095ebd7775f371dd4085cf955076Chris Lattner // Update PHI nodes. 11916de0a28dfb84095ebd7775f371dd4085cf955076Chris Lattner AddPredecessorToBlock(RealDest, EdgeBB, BB); 11929a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner 11939a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // BB may have instructions that are being threaded over. Clone these 11949a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // instructions into EdgeBB. We know that there will be no uses of the 11959a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // cloned instructions outside of EdgeBB. 11969a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner BasicBlock::iterator InsertPt = EdgeBB->begin(); 11979a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner DenseMap<Value*, Value*> TranslateMap; // Track translated values. 11989a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner for (BasicBlock::iterator BBI = BB->begin(); &*BBI != BI; ++BBI) { 11999a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (PHINode *PN = dyn_cast<PHINode>(BBI)) { 12009a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner TranslateMap[PN] = PN->getIncomingValueForBlock(PredBB); 12019a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner continue; 12029a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner } 12039a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // Clone the instruction. 12049a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner Instruction *N = BBI->clone(); 12059a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (BBI->hasName()) N->setName(BBI->getName()+".c"); 1206eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner 12079a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // Update operands due to translation. 12089a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner for (User::op_iterator i = N->op_begin(), e = N->op_end(); 12099a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner i != e; ++i) { 12109a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner DenseMap<Value*, Value*>::iterator PI = TranslateMap.find(*i); 12119a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (PI != TranslateMap.end()) 12129a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner *i = PI->second; 12139a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner } 1214eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner 12159a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // Check for trivial simplification. 1216302ba6fc1cb26248b0d6524fc42c740370926d6dChris Lattner if (Value *V = SimplifyInstruction(N, TD)) { 1217302ba6fc1cb26248b0d6524fc42c740370926d6dChris Lattner TranslateMap[BBI] = V; 1218302ba6fc1cb26248b0d6524fc42c740370926d6dChris Lattner delete N; // Instruction folded away, don't need actual inst 12199a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner } else { 12209a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // Insert the new instruction into its new home. 12219a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner EdgeBB->getInstList().insert(InsertPt, N); 12229a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (!BBI->use_empty()) 12239a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner TranslateMap[BBI] = N; 1224e9487f0dc8c6d15cb257d5b49fa96ed436d32f5fChris Lattner } 12259a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner } 1226e9487f0dc8c6d15cb257d5b49fa96ed436d32f5fChris Lattner 12279a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // Loop over all of the edges from PredBB to BB, changing them to branch 12289a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // to EdgeBB instead. 12299a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner TerminatorInst *PredBBTI = PredBB->getTerminator(); 12309a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner for (unsigned i = 0, e = PredBBTI->getNumSuccessors(); i != e; ++i) 12319a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (PredBBTI->getSuccessor(i) == BB) { 12329a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner BB->removePredecessor(PredBB); 12339a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner PredBBTI->setSuccessor(i, EdgeBB); 1234e9487f0dc8c6d15cb257d5b49fa96ed436d32f5fChris Lattner } 12356a648b8538bb4d4b3e96669ef8cd3a4ce3aedeb8Bill Wendling 12369a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // Recurse, simplifying any other constants. 1237302ba6fc1cb26248b0d6524fc42c740370926d6dChris Lattner return FoldCondBranchOnPHI(BI, TD) | true; 12386b6b6ef1677fa71b1072c2911b4c1f9524a558c9Zhou Sheng } 1239eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner 1240eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner return false; 1241eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner} 1242eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner 1243f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner/// FoldTwoEntryPHINode - Given a BB that starts with the specified two-entry 1244f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner/// PHI node, see if we can eliminate it. 1245d3a1788da15311781f661c1cbfe48cd5f98ae778Devang Patelstatic bool FoldTwoEntryPHINode(PHINode *PN, const TargetData *TD) { 1246f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // Ok, this is a two entry PHI node. Check to see if this is a simple "if 1247f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // statement", which has a very simple dominance structure. Basically, we 1248f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // are trying to find the condition that is being branched on, which 1249f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // subsequently causes this merge to happen. We really want control 1250f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // dependence information for this check, but simplifycfg can't keep it up 1251f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // to date, and this catches most of the cases we care about anyway. 1252f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner BasicBlock *BB = PN->getParent(); 1253f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner BasicBlock *IfTrue, *IfFalse; 1254f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner Value *IfCond = GetIfCondition(BB, IfTrue, IfFalse); 125560d410d7bb2eb11f36a004237e5948ffc5aff5a6Chris Lattner if (!IfCond || 125660d410d7bb2eb11f36a004237e5948ffc5aff5a6Chris Lattner // Don't bother if the branch will be constant folded trivially. 125760d410d7bb2eb11f36a004237e5948ffc5aff5a6Chris Lattner isa<ConstantInt>(IfCond)) 125860d410d7bb2eb11f36a004237e5948ffc5aff5a6Chris Lattner return false; 1259f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner 1260822a87998387a4c52be5162523f09cc8e5e5afb7Chris Lattner // Okay, we found that we can merge this two-entry phi node into a select. 1261822a87998387a4c52be5162523f09cc8e5e5afb7Chris Lattner // Doing so would require us to fold *all* two entry phi nodes in this block. 1262822a87998387a4c52be5162523f09cc8e5e5afb7Chris Lattner // At some point this becomes non-profitable (particularly if the target 1263822a87998387a4c52be5162523f09cc8e5e5afb7Chris Lattner // doesn't support cmov's). Only do this transformation if there are two or 1264822a87998387a4c52be5162523f09cc8e5e5afb7Chris Lattner // fewer PHI nodes in this block. 1265822a87998387a4c52be5162523f09cc8e5e5afb7Chris Lattner unsigned NumPhis = 0; 1266822a87998387a4c52be5162523f09cc8e5e5afb7Chris Lattner for (BasicBlock::iterator I = BB->begin(); isa<PHINode>(I); ++NumPhis, ++I) 1267822a87998387a4c52be5162523f09cc8e5e5afb7Chris Lattner if (NumPhis > 2) 1268822a87998387a4c52be5162523f09cc8e5e5afb7Chris Lattner return false; 1269822a87998387a4c52be5162523f09cc8e5e5afb7Chris Lattner 1270f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // Loop over the PHI's seeing if we can promote them all to select 1271f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // instructions. While we are at it, keep track of the instructions 1272f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // that need to be moved to the dominating block. 127344da7ca4213333bcade57a407a890970351db494Chris Lattner SmallPtrSet<Instruction*, 4> AggressiveInsts; 127457808b3da00d7abd01382d3ed5e70bfb0b2beb4bPeter Collingbourne unsigned MaxCostVal0 = PHINodeFoldingThreshold, 127557808b3da00d7abd01382d3ed5e70bfb0b2beb4bPeter Collingbourne MaxCostVal1 = PHINodeFoldingThreshold; 1276f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner 12773aff13b82a579e910420b6c040f3e85c99110e15Chris Lattner for (BasicBlock::iterator II = BB->begin(); isa<PHINode>(II);) { 12783aff13b82a579e910420b6c040f3e85c99110e15Chris Lattner PHINode *PN = cast<PHINode>(II++); 127907ff3539f5342bdac019c68bb362cb222b3f71d9Chris Lattner if (Value *V = SimplifyInstruction(PN, TD)) { 128007ff3539f5342bdac019c68bb362cb222b3f71d9Chris Lattner PN->replaceAllUsesWith(V); 12813aff13b82a579e910420b6c040f3e85c99110e15Chris Lattner PN->eraseFromParent(); 128207ff3539f5342bdac019c68bb362cb222b3f71d9Chris Lattner continue; 1283f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner } 128407ff3539f5342bdac019c68bb362cb222b3f71d9Chris Lattner 1285f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne if (!DominatesMergePoint(PN->getIncomingValue(0), BB, &AggressiveInsts, 1286f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne MaxCostVal0) || 1287f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne !DominatesMergePoint(PN->getIncomingValue(1), BB, &AggressiveInsts, 1288f15907feadb979daf30b2569954852778e501b2ePeter Collingbourne MaxCostVal1)) 128907ff3539f5342bdac019c68bb362cb222b3f71d9Chris Lattner return false; 1290f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner } 1291f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner 129244da7ca4213333bcade57a407a890970351db494Chris Lattner // If we folded the the first phi, PN dangles at this point. Refresh it. If 129344da7ca4213333bcade57a407a890970351db494Chris Lattner // we ran out of PHIs then we simplified them all. 129444da7ca4213333bcade57a407a890970351db494Chris Lattner PN = dyn_cast<PHINode>(BB->begin()); 129544da7ca4213333bcade57a407a890970351db494Chris Lattner if (PN == 0) return true; 129644da7ca4213333bcade57a407a890970351db494Chris Lattner 12973aff13b82a579e910420b6c040f3e85c99110e15Chris Lattner // Don't fold i1 branches on PHIs which contain binary operators. These can 12983aff13b82a579e910420b6c040f3e85c99110e15Chris Lattner // often be turned into switches and other things. 12993aff13b82a579e910420b6c040f3e85c99110e15Chris Lattner if (PN->getType()->isIntegerTy(1) && 13003aff13b82a579e910420b6c040f3e85c99110e15Chris Lattner (isa<BinaryOperator>(PN->getIncomingValue(0)) || 13013aff13b82a579e910420b6c040f3e85c99110e15Chris Lattner isa<BinaryOperator>(PN->getIncomingValue(1)) || 13023aff13b82a579e910420b6c040f3e85c99110e15Chris Lattner isa<BinaryOperator>(IfCond))) 13033aff13b82a579e910420b6c040f3e85c99110e15Chris Lattner return false; 13043aff13b82a579e910420b6c040f3e85c99110e15Chris Lattner 1305f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // If we all PHI nodes are promotable, check to make sure that all 1306f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // instructions in the predecessor blocks can be promoted as well. If 1307f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // not, we won't be able to get rid of the control flow, so it's not 1308f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // worth promoting to select instructions. 130944da7ca4213333bcade57a407a890970351db494Chris Lattner BasicBlock *DomBlock = 0; 131044da7ca4213333bcade57a407a890970351db494Chris Lattner BasicBlock *IfBlock1 = PN->getIncomingBlock(0); 131144da7ca4213333bcade57a407a890970351db494Chris Lattner BasicBlock *IfBlock2 = PN->getIncomingBlock(1); 131244da7ca4213333bcade57a407a890970351db494Chris Lattner if (cast<BranchInst>(IfBlock1->getTerminator())->isConditional()) { 131344da7ca4213333bcade57a407a890970351db494Chris Lattner IfBlock1 = 0; 131444da7ca4213333bcade57a407a890970351db494Chris Lattner } else { 131544da7ca4213333bcade57a407a890970351db494Chris Lattner DomBlock = *pred_begin(IfBlock1); 131644da7ca4213333bcade57a407a890970351db494Chris Lattner for (BasicBlock::iterator I = IfBlock1->begin();!isa<TerminatorInst>(I);++I) 1317383d7ed9158576aef5cde872548225a17e3c0155Devang Patel if (!AggressiveInsts.count(I) && !isa<DbgInfoIntrinsic>(I)) { 1318f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // This is not an aggressive instruction that we can promote. 1319f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // Because of this, we won't be able to get rid of the control 1320f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // flow, so the xform is not worth it. 1321f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner return false; 1322f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner } 1323f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner } 1324f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner 132544da7ca4213333bcade57a407a890970351db494Chris Lattner if (cast<BranchInst>(IfBlock2->getTerminator())->isConditional()) { 132644da7ca4213333bcade57a407a890970351db494Chris Lattner IfBlock2 = 0; 132744da7ca4213333bcade57a407a890970351db494Chris Lattner } else { 132844da7ca4213333bcade57a407a890970351db494Chris Lattner DomBlock = *pred_begin(IfBlock2); 132944da7ca4213333bcade57a407a890970351db494Chris Lattner for (BasicBlock::iterator I = IfBlock2->begin();!isa<TerminatorInst>(I);++I) 1330383d7ed9158576aef5cde872548225a17e3c0155Devang Patel if (!AggressiveInsts.count(I) && !isa<DbgInfoIntrinsic>(I)) { 1331f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // This is not an aggressive instruction that we can promote. 1332f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // Because of this, we won't be able to get rid of the control 1333f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // flow, so the xform is not worth it. 1334f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner return false; 1335f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner } 1336f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner } 1337e0b18e59120abc29bd25d69d20c4b0f310ec3382Chris Lattner 1338e0b18e59120abc29bd25d69d20c4b0f310ec3382Chris Lattner DEBUG(dbgs() << "FOUND IF CONDITION! " << *IfCond << " T: " 133944da7ca4213333bcade57a407a890970351db494Chris Lattner << IfTrue->getName() << " F: " << IfFalse->getName() << "\n"); 1340f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner 1341f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // If we can still promote the PHI nodes after this gauntlet of tests, 1342f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // do all of the PHI's now. 13433aff13b82a579e910420b6c040f3e85c99110e15Chris Lattner Instruction *InsertPt = DomBlock->getTerminator(); 1344d3a1788da15311781f661c1cbfe48cd5f98ae778Devang Patel IRBuilder<true, NoFolder> Builder(InsertPt); 13453aff13b82a579e910420b6c040f3e85c99110e15Chris Lattner 1346f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // Move all 'aggressive' instructions, which are defined in the 1347f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // conditional parts of the if's up to the dominating block. 13489a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (IfBlock1) 13493aff13b82a579e910420b6c040f3e85c99110e15Chris Lattner DomBlock->getInstList().splice(InsertPt, 13509a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner IfBlock1->getInstList(), IfBlock1->begin(), 1351f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner IfBlock1->getTerminator()); 13529a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (IfBlock2) 13533aff13b82a579e910420b6c040f3e85c99110e15Chris Lattner DomBlock->getInstList().splice(InsertPt, 13549a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner IfBlock2->getInstList(), IfBlock2->begin(), 1355f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner IfBlock2->getTerminator()); 1356f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner 1357f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner while (PHINode *PN = dyn_cast<PHINode>(BB->begin())) { 1358f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // Change the PHI node into a select instruction. 13599a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner Value *TrueVal = PN->getIncomingValue(PN->getIncomingBlock(0) == IfFalse); 13609a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner Value *FalseVal = PN->getIncomingValue(PN->getIncomingBlock(0) == IfTrue); 1361f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner 1362f60364de44add5c92841425851cda1a6943bfcd7Devang Patel SelectInst *NV = 1363f60364de44add5c92841425851cda1a6943bfcd7Devang Patel cast<SelectInst>(Builder.CreateSelect(IfCond, TrueVal, FalseVal, "")); 136486cc42355593dd1689f7d58d56695c451215b02bChris Lattner PN->replaceAllUsesWith(NV); 136586cc42355593dd1689f7d58d56695c451215b02bChris Lattner NV->takeName(PN); 1366302ba6fc1cb26248b0d6524fc42c740370926d6dChris Lattner PN->eraseFromParent(); 1367f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner } 136860d410d7bb2eb11f36a004237e5948ffc5aff5a6Chris Lattner 136960d410d7bb2eb11f36a004237e5948ffc5aff5a6Chris Lattner // At this point, IfBlock1 and IfBlock2 are both empty, so our if statement 137060d410d7bb2eb11f36a004237e5948ffc5aff5a6Chris Lattner // has been flattened. Change DomBlock to jump directly to our new block to 137160d410d7bb2eb11f36a004237e5948ffc5aff5a6Chris Lattner // avoid other simplifycfg's kicking in on the diamond. 137260d410d7bb2eb11f36a004237e5948ffc5aff5a6Chris Lattner TerminatorInst *OldTI = DomBlock->getTerminator(); 1373f60364de44add5c92841425851cda1a6943bfcd7Devang Patel Builder.SetInsertPoint(OldTI); 1374f60364de44add5c92841425851cda1a6943bfcd7Devang Patel Builder.CreateBr(BB); 137560d410d7bb2eb11f36a004237e5948ffc5aff5a6Chris Lattner OldTI->eraseFromParent(); 1376f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner return true; 1377f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner} 1378eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner 1379c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner/// SimplifyCondBranchToTwoReturns - If we found a conditional branch that goes 1380c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner/// to two returning blocks, try to merge them together into one return, 1381c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner/// introducing a select if the return values disagree. 1382176ec40cb18c51c14fccbb38ee0db5deafb6baa9Devang Patelstatic bool SimplifyCondBranchToTwoReturns(BranchInst *BI, 1383176ec40cb18c51c14fccbb38ee0db5deafb6baa9Devang Patel IRBuilder<> &Builder) { 1384c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner assert(BI->isConditional() && "Must be a conditional branch"); 1385c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner BasicBlock *TrueSucc = BI->getSuccessor(0); 1386c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner BasicBlock *FalseSucc = BI->getSuccessor(1); 1387c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner ReturnInst *TrueRet = cast<ReturnInst>(TrueSucc->getTerminator()); 1388c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner ReturnInst *FalseRet = cast<ReturnInst>(FalseSucc->getTerminator()); 1389c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner 1390c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner // Check to ensure both blocks are empty (just a return) or optionally empty 1391c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner // with PHI nodes. If there are other instructions, merging would cause extra 1392c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner // computation on one path or the other. 13939a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (!TrueSucc->getFirstNonPHIOrDbg()->isTerminator()) 13942cc86a1de1cf598be384836f19d1ef1892fb50fcDevang Patel return false; 13959a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (!FalseSucc->getFirstNonPHIOrDbg()->isTerminator()) 13962cc86a1de1cf598be384836f19d1ef1892fb50fcDevang Patel return false; 1397c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner 1398176ec40cb18c51c14fccbb38ee0db5deafb6baa9Devang Patel Builder.SetInsertPoint(BI); 1399c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner // Okay, we found a branch that is going to two return nodes. If 1400c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner // there is no return value for this function, just change the 1401c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner // branch into a return. 1402c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner if (FalseRet->getNumOperands() == 0) { 1403c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner TrueSucc->removePredecessor(BI->getParent()); 1404c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner FalseSucc->removePredecessor(BI->getParent()); 1405176ec40cb18c51c14fccbb38ee0db5deafb6baa9Devang Patel Builder.CreateRetVoid(); 1406080efb8cea6255b4f1f373d9cb583d6a6302106bEli Friedman EraseTerminatorInstAndDCECond(BI); 1407c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner return true; 1408c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner } 1409c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner 1410fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman // Otherwise, figure out what the true and false return values are 1411fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman // so we can insert a new select instruction. 1412fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman Value *TrueValue = TrueRet->getReturnValue(); 1413fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman Value *FalseValue = FalseRet->getReturnValue(); 1414fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman 1415fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman // Unwrap any PHI nodes in the return blocks. 1416fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman if (PHINode *TVPN = dyn_cast_or_null<PHINode>(TrueValue)) 1417fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman if (TVPN->getParent() == TrueSucc) 1418fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman TrueValue = TVPN->getIncomingValueForBlock(BI->getParent()); 1419fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman if (PHINode *FVPN = dyn_cast_or_null<PHINode>(FalseValue)) 1420fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman if (FVPN->getParent() == FalseSucc) 1421fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman FalseValue = FVPN->getIncomingValueForBlock(BI->getParent()); 1422fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman 1423fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman // In order for this transformation to be safe, we must be able to 1424fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman // unconditionally execute both operands to the return. This is 1425fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman // normally the case, but we could have a potentially-trapping 1426fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman // constant expression that prevents this transformation from being 1427fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman // safe. 1428fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman if (ConstantExpr *TCV = dyn_cast_or_null<ConstantExpr>(TrueValue)) 1429fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman if (TCV->canTrap()) 1430fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman return false; 1431fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman if (ConstantExpr *FCV = dyn_cast_or_null<ConstantExpr>(FalseValue)) 1432fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman if (FCV->canTrap()) 1433fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman return false; 1434c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner 1435c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner // Okay, we collected all the mapped values and checked them for sanity, and 1436c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner // defined to really do this transformation. First, update the CFG. 1437c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner TrueSucc->removePredecessor(BI->getParent()); 1438c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner FalseSucc->removePredecessor(BI->getParent()); 1439c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner 1440c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner // Insert select instructions where needed. 1441c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner Value *BrCond = BI->getCondition(); 1442fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman if (TrueValue) { 1443c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner // Insert a select if the results differ. 1444fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman if (TrueValue == FalseValue || isa<UndefValue>(FalseValue)) { 1445fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman } else if (isa<UndefValue>(TrueValue)) { 1446fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman TrueValue = FalseValue; 1447fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman } else { 1448176ec40cb18c51c14fccbb38ee0db5deafb6baa9Devang Patel TrueValue = Builder.CreateSelect(BrCond, TrueValue, 1449176ec40cb18c51c14fccbb38ee0db5deafb6baa9Devang Patel FalseValue, "retval"); 1450c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner } 1451c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner } 1452c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner 1453176ec40cb18c51c14fccbb38ee0db5deafb6baa9Devang Patel Value *RI = !TrueValue ? 1454176ec40cb18c51c14fccbb38ee0db5deafb6baa9Devang Patel Builder.CreateRetVoid() : Builder.CreateRet(TrueValue); 1455176ec40cb18c51c14fccbb38ee0db5deafb6baa9Devang Patel 1456e317bcc74c1f317f913e9b05db385901cfc54d0bDaniel Dunbar (void) RI; 1457c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner 145889d6fd36a26fdf068ceea90422dc2897e89700b5David Greene DEBUG(dbgs() << "\nCHANGING BRANCH TO TWO RETURNS INTO SELECT:" 1459bdff548e4dd577a72094d57b282de4e765643b96Chris Lattner << "\n " << *BI << "NewRet = " << *RI 1460bdff548e4dd577a72094d57b282de4e765643b96Chris Lattner << "TRUEBLOCK: " << *TrueSucc << "FALSEBLOCK: "<< *FalseSucc); 1461c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner 1462080efb8cea6255b4f1f373d9cb583d6a6302106bEli Friedman EraseTerminatorInstAndDCECond(BI); 1463080efb8cea6255b4f1f373d9cb583d6a6302106bEli Friedman 1464c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner return true; 1465c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner} 1466c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner 146706cc66f65a5012471835068029f3f4943790f584Nick Lewycky/// ExtractBranchMetadata - Given a conditional BranchInstruction, retrieve the 146806cc66f65a5012471835068029f3f4943790f584Nick Lewycky/// probabilities of the branch taking each edge. Fills in the two APInt 146906cc66f65a5012471835068029f3f4943790f584Nick Lewycky/// parameters and return true, or returns false if no or invalid metadata was 147006cc66f65a5012471835068029f3f4943790f584Nick Lewycky/// found. 147106cc66f65a5012471835068029f3f4943790f584Nick Lewyckystatic bool ExtractBranchMetadata(BranchInst *BI, 147206cc66f65a5012471835068029f3f4943790f584Nick Lewycky APInt &ProbTrue, APInt &ProbFalse) { 147306cc66f65a5012471835068029f3f4943790f584Nick Lewycky assert(BI->isConditional() && 147406cc66f65a5012471835068029f3f4943790f584Nick Lewycky "Looking for probabilities on unconditional branch?"); 147506cc66f65a5012471835068029f3f4943790f584Nick Lewycky MDNode *ProfileData = BI->getMetadata(LLVMContext::MD_prof); 147691968489d718b313d4c0b912062e75a82db650e7Nick Lewycky if (!ProfileData || ProfileData->getNumOperands() != 3) return false; 147706cc66f65a5012471835068029f3f4943790f584Nick Lewycky ConstantInt *CITrue = dyn_cast<ConstantInt>(ProfileData->getOperand(1)); 147806cc66f65a5012471835068029f3f4943790f584Nick Lewycky ConstantInt *CIFalse = dyn_cast<ConstantInt>(ProfileData->getOperand(2)); 147991968489d718b313d4c0b912062e75a82db650e7Nick Lewycky if (!CITrue || !CIFalse) return false; 148006cc66f65a5012471835068029f3f4943790f584Nick Lewycky ProbTrue = CITrue->getValue(); 148106cc66f65a5012471835068029f3f4943790f584Nick Lewycky ProbFalse = CIFalse->getValue(); 148206cc66f65a5012471835068029f3f4943790f584Nick Lewycky assert(ProbTrue.getBitWidth() == 32 && ProbFalse.getBitWidth() == 32 && 148306cc66f65a5012471835068029f3f4943790f584Nick Lewycky "Branch probability metadata must be 32-bit integers"); 148406cc66f65a5012471835068029f3f4943790f584Nick Lewycky return true; 148506cc66f65a5012471835068029f3f4943790f584Nick Lewycky} 148606cc66f65a5012471835068029f3f4943790f584Nick Lewycky 1487c8fbc34869fc1737adea00f775de5b8dd829f7a1Chris Lattner/// FoldBranchToCommonDest - If this basic block is simple enough, and if a 1488c8fbc34869fc1737adea00f775de5b8dd829f7a1Chris Lattner/// predecessor branches to us and one of our successors, fold the block into 1489c8fbc34869fc1737adea00f775de5b8dd829f7a1Chris Lattner/// the predecessor and use logical operations to pick the right destination. 14904b35f83b91a1a313f0730c600e5178aaf7df98d6Dan Gohmanbool llvm::FoldBranchToCommonDest(BranchInst *BI) { 1491093a4385027235459ab6972b2e2fdc79061773cfChris Lattner BasicBlock *BB = BI->getParent(); 1492d3a1788da15311781f661c1cbfe48cd5f98ae778Devang Patel 14931347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner Instruction *Cond = dyn_cast<Instruction>(BI->getCondition()); 1494e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson if (Cond == 0 || (!isa<CmpInst>(Cond) && !isa<BinaryOperator>(Cond)) || 1495e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson Cond->getParent() != BB || !Cond->hasOneUse()) 1496e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson return false; 1497d418194036e9e05f47154535ddb9f1f1c8bc592bDevang Patel 14981347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner // Only allow this if the condition is a simple instruction that can be 14991347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner // executed unconditionally. It must be in the same block as the branch, and 15001347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner // must be at the front of the block. 1501d0a203d76f4ef77ae1c392e8e73e2f05b676a5f2Devang Patel BasicBlock::iterator FrontIt = BB->front(); 15023c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner 1503d0a203d76f4ef77ae1c392e8e73e2f05b676a5f2Devang Patel // Ignore dbg intrinsics. 15043c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner while (isa<DbgInfoIntrinsic>(FrontIt)) ++FrontIt; 15059d5231022283ff20b0291eb5711a449de262d3feNick Lewycky 1506e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson // Allow a single instruction to be hoisted in addition to the compare 1507e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson // that feeds the branch. We later ensure that any values that _it_ uses 1508e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson // were also live in the predecessor, so that we don't unnecessarily create 1509e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson // register pressure or inhibit out-of-order execution. 1510e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson Instruction *BonusInst = 0; 1511e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson if (&*FrontIt != Cond && 15122722dfa75dbf4436197f6fcf9d8cb2391975f1a1Owen Anderson FrontIt->hasOneUse() && *FrontIt->use_begin() == Cond && 1513f0426601977c3e386d2d26c72a2cca691dc42072Dan Gohman isSafeToSpeculativelyExecute(FrontIt)) { 1514e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson BonusInst = &*FrontIt; 1515e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson ++FrontIt; 15163c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner 15173c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner // Ignore dbg intrinsics. 15183c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner while (isa<DbgInfoIntrinsic>(FrontIt)) ++FrontIt; 151960d490cdc7b11e678f35f5b7eb2c9ef354462211Devang Patel } 152060d490cdc7b11e678f35f5b7eb2c9ef354462211Devang Patel 1521e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson // Only a single bonus inst is allowed. 1522e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson if (&*FrontIt != Cond) 1523e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson return false; 1524e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson 15251347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner // Make sure the instruction after the condition is the cond branch. 15261347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner BasicBlock::iterator CondIt = Cond; ++CondIt; 15273c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner 1528d0a203d76f4ef77ae1c392e8e73e2f05b676a5f2Devang Patel // Ingore dbg intrinsics. 15293c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner while (isa<DbgInfoIntrinsic>(CondIt)) ++CondIt; 15303c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner 15313c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner if (&*CondIt != BI) 15321347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner return false; 15336ff645bf0fcfc0c62e9d9126e1243ec8bf10abbcChris Lattner 15346ff645bf0fcfc0c62e9d9126e1243ec8bf10abbcChris Lattner // Cond is known to be a compare or binary operator. Check to make sure that 15356ff645bf0fcfc0c62e9d9126e1243ec8bf10abbcChris Lattner // neither operand is a potentially-trapping constant expression. 15366ff645bf0fcfc0c62e9d9126e1243ec8bf10abbcChris Lattner if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Cond->getOperand(0))) 15376ff645bf0fcfc0c62e9d9126e1243ec8bf10abbcChris Lattner if (CE->canTrap()) 15386ff645bf0fcfc0c62e9d9126e1243ec8bf10abbcChris Lattner return false; 15396ff645bf0fcfc0c62e9d9126e1243ec8bf10abbcChris Lattner if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Cond->getOperand(1))) 15406ff645bf0fcfc0c62e9d9126e1243ec8bf10abbcChris Lattner if (CE->canTrap()) 15416ff645bf0fcfc0c62e9d9126e1243ec8bf10abbcChris Lattner return false; 15426ff645bf0fcfc0c62e9d9126e1243ec8bf10abbcChris Lattner 15431347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner // Finally, don't infinitely unroll conditional loops. 15441347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner BasicBlock *TrueDest = BI->getSuccessor(0); 15451347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner BasicBlock *FalseDest = BI->getSuccessor(1); 15461347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner if (TrueDest == BB || FalseDest == BB) 15471347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner return false; 1548d418194036e9e05f47154535ddb9f1f1c8bc592bDevang Patel 15491347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI) { 15501347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner BasicBlock *PredBlock = *PI; 15511347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner BranchInst *PBI = dyn_cast<BranchInst>(PredBlock->getTerminator()); 15526ff645bf0fcfc0c62e9d9126e1243ec8bf10abbcChris Lattner 1553093a4385027235459ab6972b2e2fdc79061773cfChris Lattner // Check that we have two conditional branches. If there is a PHI node in 1554093a4385027235459ab6972b2e2fdc79061773cfChris Lattner // the common successor, verify that the same value flows in from both 1555093a4385027235459ab6972b2e2fdc79061773cfChris Lattner // blocks. 15563c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner if (PBI == 0 || PBI->isUnconditional() || !SafeToMergeTerminators(BI, PBI)) 15571347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner continue; 15581347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner 15593c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner // Determine if the two branches share a common destination. 15603c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner Instruction::BinaryOps Opc; 15613c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner bool InvertPredCond = false; 15623c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner 15633c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner if (PBI->getSuccessor(0) == TrueDest) 15643c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner Opc = Instruction::Or; 15653c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner else if (PBI->getSuccessor(1) == FalseDest) 15663c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner Opc = Instruction::And; 15673c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner else if (PBI->getSuccessor(0) == FalseDest) 15683c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner Opc = Instruction::And, InvertPredCond = true; 15693c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner else if (PBI->getSuccessor(1) == TrueDest) 15703c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner Opc = Instruction::Or, InvertPredCond = true; 15713c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner else 15723c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner continue; 15733c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner 1574e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson // Ensure that any values used in the bonus instruction are also used 1575e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson // by the terminator of the predecessor. This means that those values 1576e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson // must already have been resolved, so we won't be inhibiting the 1577e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson // out-of-order core by speculating them earlier. 1578e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson if (BonusInst) { 1579e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson // Collect the values used by the bonus inst 1580e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson SmallPtrSet<Value*, 4> UsedValues; 1581e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson for (Instruction::op_iterator OI = BonusInst->op_begin(), 1582e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson OE = BonusInst->op_end(); OI != OE; ++OI) { 15839d5231022283ff20b0291eb5711a449de262d3feNick Lewycky Value *V = *OI; 1584e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson if (!isa<Constant>(V)) 1585e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson UsedValues.insert(V); 1586e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson } 1587e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson 1588e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson SmallVector<std::pair<Value*, unsigned>, 4> Worklist; 1589e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson Worklist.push_back(std::make_pair(PBI->getOperand(0), 0)); 1590e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson 1591e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson // Walk up to four levels back up the use-def chain of the predecessor's 1592e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson // terminator to see if all those values were used. The choice of four 1593e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson // levels is arbitrary, to provide a compile-time-cost bound. 1594e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson while (!Worklist.empty()) { 1595e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson std::pair<Value*, unsigned> Pair = Worklist.back(); 1596e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson Worklist.pop_back(); 1597e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson 1598e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson if (Pair.second >= 4) continue; 1599e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson UsedValues.erase(Pair.first); 1600e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson if (UsedValues.empty()) break; 1601e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson 1602daa02ab70c7619cc22131c75c62390cf3f5f8891Chris Lattner if (Instruction *I = dyn_cast<Instruction>(Pair.first)) { 1603e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson for (Instruction::op_iterator OI = I->op_begin(), OE = I->op_end(); 1604e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson OI != OE; ++OI) 1605e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson Worklist.push_back(std::make_pair(OI->get(), Pair.second+1)); 1606e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson } 1607e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson } 1608e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson 1609e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson if (!UsedValues.empty()) return false; 1610e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson } 16113698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner 161289d6fd36a26fdf068ceea90422dc2897e89700b5David Greene DEBUG(dbgs() << "FOLDING BRANCH TO COMMON DEST:\n" << *PBI << *BB); 1613d3a1788da15311781f661c1cbfe48cd5f98ae778Devang Patel IRBuilder<> Builder(PBI); 1614d3a1788da15311781f661c1cbfe48cd5f98ae778Devang Patel 16153698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner // If we need to invert the condition in the pred block to match, do so now. 16163698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner if (InvertPredCond) { 1617daa02ab70c7619cc22131c75c62390cf3f5f8891Chris Lattner Value *NewCond = PBI->getCondition(); 1618daa02ab70c7619cc22131c75c62390cf3f5f8891Chris Lattner 1619daa02ab70c7619cc22131c75c62390cf3f5f8891Chris Lattner if (NewCond->hasOneUse() && isa<CmpInst>(NewCond)) { 1620daa02ab70c7619cc22131c75c62390cf3f5f8891Chris Lattner CmpInst *CI = cast<CmpInst>(NewCond); 1621daa02ab70c7619cc22131c75c62390cf3f5f8891Chris Lattner CI->setPredicate(CI->getInversePredicate()); 1622daa02ab70c7619cc22131c75c62390cf3f5f8891Chris Lattner } else { 1623d3a1788da15311781f661c1cbfe48cd5f98ae778Devang Patel NewCond = Builder.CreateNot(NewCond, 1624d3a1788da15311781f661c1cbfe48cd5f98ae778Devang Patel PBI->getCondition()->getName()+".not"); 1625daa02ab70c7619cc22131c75c62390cf3f5f8891Chris Lattner } 1626daa02ab70c7619cc22131c75c62390cf3f5f8891Chris Lattner 16271347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner PBI->setCondition(NewCond); 1628c9a1aed7fefe627820bb92154361ede0568229fcNick Lewycky PBI->swapSuccessors(); 16291347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner } 163070087f31f154156bcb494dd0cf3b7d74c0c8b528Chris Lattner 1631e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson // If we have a bonus inst, clone it into the predecessor block. 1632e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson Instruction *NewBonus = 0; 1633e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson if (BonusInst) { 1634e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson NewBonus = BonusInst->clone(); 1635e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson PredBlock->getInstList().insert(PBI, NewBonus); 1636e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson NewBonus->takeName(BonusInst); 1637e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson BonusInst->setName(BonusInst->getName()+".old"); 1638e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson } 1639e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson 16403698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner // Clone Cond into the predecessor basic block, and or/and the 16413698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner // two conditions together. 16426776064d190701c5bae4d5403939eed2e480d1cdNick Lewycky Instruction *New = Cond->clone(); 1643e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson if (BonusInst) New->replaceUsesOfWith(BonusInst, NewBonus); 16443698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner PredBlock->getInstList().insert(PBI, New); 16453698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner New->takeName(Cond); 16463698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner Cond->setName(New->getName()+".old"); 164770087f31f154156bcb494dd0cf3b7d74c0c8b528Chris Lattner 1648d3a1788da15311781f661c1cbfe48cd5f98ae778Devang Patel Instruction *NewCond = 1649d3a1788da15311781f661c1cbfe48cd5f98ae778Devang Patel cast<Instruction>(Builder.CreateBinOp(Opc, PBI->getCondition(), 1650d3a1788da15311781f661c1cbfe48cd5f98ae778Devang Patel New, "or.cond")); 16513698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner PBI->setCondition(NewCond); 16523698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner if (PBI->getSuccessor(0) == BB) { 16533698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner AddPredecessorToBlock(TrueDest, PredBlock, BB); 16543698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner PBI->setSuccessor(0, TrueDest); 16553698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner } 16563698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner if (PBI->getSuccessor(1) == BB) { 16573698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner AddPredecessorToBlock(FalseDest, PredBlock, BB); 16583698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner PBI->setSuccessor(1, FalseDest); 16591347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner } 1660d418194036e9e05f47154535ddb9f1f1c8bc592bDevang Patel 166106cc66f65a5012471835068029f3f4943790f584Nick Lewycky // TODO: If BB is reachable from all paths through PredBlock, then we 166206cc66f65a5012471835068029f3f4943790f584Nick Lewycky // could replace PBI's branch probabilities with BI's. 166306cc66f65a5012471835068029f3f4943790f584Nick Lewycky 166406cc66f65a5012471835068029f3f4943790f584Nick Lewycky // Merge probability data into PredBlock's branch. 166506cc66f65a5012471835068029f3f4943790f584Nick Lewycky APInt A, B, C, D; 166606cc66f65a5012471835068029f3f4943790f584Nick Lewycky if (ExtractBranchMetadata(PBI, C, D) && ExtractBranchMetadata(BI, A, B)) { 166706cc66f65a5012471835068029f3f4943790f584Nick Lewycky // bbA: br bbB (a% probability), bbC (b% prob.) 166806cc66f65a5012471835068029f3f4943790f584Nick Lewycky // bbB: br bbD (c% probability), bbC (d% prob.) 166906cc66f65a5012471835068029f3f4943790f584Nick Lewycky // --> bbA: br bbD ((a*c)% prob.), bbC ((b+a*d)% prob.) 167006cc66f65a5012471835068029f3f4943790f584Nick Lewycky // 167106cc66f65a5012471835068029f3f4943790f584Nick Lewycky // Probabilities aren't stored as ratios directly. Converting to 167206cc66f65a5012471835068029f3f4943790f584Nick Lewycky // probability-numerator form, we get: 167306cc66f65a5012471835068029f3f4943790f584Nick Lewycky // (a*c)% = A*C, (b+(a*d))% = A*D+B*C+B*D. 167406cc66f65a5012471835068029f3f4943790f584Nick Lewycky 167506cc66f65a5012471835068029f3f4943790f584Nick Lewycky bool Overflow1 = false, Overflow2 = false, Overflow3 = false; 167606cc66f65a5012471835068029f3f4943790f584Nick Lewycky bool Overflow4 = false, Overflow5 = false, Overflow6 = false; 167706cc66f65a5012471835068029f3f4943790f584Nick Lewycky APInt ProbTrue = A.umul_ov(C, Overflow1); 167806cc66f65a5012471835068029f3f4943790f584Nick Lewycky 167906cc66f65a5012471835068029f3f4943790f584Nick Lewycky APInt Tmp1 = A.umul_ov(D, Overflow2); 168006cc66f65a5012471835068029f3f4943790f584Nick Lewycky APInt Tmp2 = B.umul_ov(C, Overflow3); 168106cc66f65a5012471835068029f3f4943790f584Nick Lewycky APInt Tmp3 = B.umul_ov(D, Overflow4); 168206cc66f65a5012471835068029f3f4943790f584Nick Lewycky APInt Tmp4 = Tmp1.uadd_ov(Tmp2, Overflow5); 168306cc66f65a5012471835068029f3f4943790f584Nick Lewycky APInt ProbFalse = Tmp4.uadd_ov(Tmp3, Overflow6); 168406cc66f65a5012471835068029f3f4943790f584Nick Lewycky 168506cc66f65a5012471835068029f3f4943790f584Nick Lewycky APInt GCD = APIntOps::GreatestCommonDivisor(ProbTrue, ProbFalse); 168606cc66f65a5012471835068029f3f4943790f584Nick Lewycky ProbTrue = ProbTrue.udiv(GCD); 168706cc66f65a5012471835068029f3f4943790f584Nick Lewycky ProbFalse = ProbFalse.udiv(GCD); 168806cc66f65a5012471835068029f3f4943790f584Nick Lewycky 168906cc66f65a5012471835068029f3f4943790f584Nick Lewycky if (Overflow1 || Overflow2 || Overflow3 || Overflow4 || Overflow5 || 169006cc66f65a5012471835068029f3f4943790f584Nick Lewycky Overflow6) { 169106cc66f65a5012471835068029f3f4943790f584Nick Lewycky DEBUG(dbgs() << "Overflow recomputing branch weight on: " << *PBI 169206cc66f65a5012471835068029f3f4943790f584Nick Lewycky << "when merging with: " << *BI); 169306cc66f65a5012471835068029f3f4943790f584Nick Lewycky PBI->setMetadata(LLVMContext::MD_prof, NULL); 169406cc66f65a5012471835068029f3f4943790f584Nick Lewycky } else { 169506cc66f65a5012471835068029f3f4943790f584Nick Lewycky LLVMContext &Context = BI->getContext(); 169606cc66f65a5012471835068029f3f4943790f584Nick Lewycky Value *Ops[3]; 169706cc66f65a5012471835068029f3f4943790f584Nick Lewycky Ops[0] = BI->getMetadata(LLVMContext::MD_prof)->getOperand(0); 169806cc66f65a5012471835068029f3f4943790f584Nick Lewycky Ops[1] = ConstantInt::get(Context, ProbTrue); 169906cc66f65a5012471835068029f3f4943790f584Nick Lewycky Ops[2] = ConstantInt::get(Context, ProbFalse); 170006cc66f65a5012471835068029f3f4943790f584Nick Lewycky PBI->setMetadata(LLVMContext::MD_prof, MDNode::get(Context, Ops)); 170106cc66f65a5012471835068029f3f4943790f584Nick Lewycky } 170206cc66f65a5012471835068029f3f4943790f584Nick Lewycky } else { 170306cc66f65a5012471835068029f3f4943790f584Nick Lewycky PBI->setMetadata(LLVMContext::MD_prof, NULL); 170406cc66f65a5012471835068029f3f4943790f584Nick Lewycky } 170506cc66f65a5012471835068029f3f4943790f584Nick Lewycky 17063c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner // Copy any debug value intrinsics into the end of PredBlock. 17073c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) 17083c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner if (isa<DbgInfoIntrinsic>(*I)) 17093c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner I->clone()->insertBefore(PBI); 17103c6e746b5f05ffe3870e2aeadd2f9a3c0a96187bChris Lattner 1711117f8cffc5499217ff8824eb0d6a0f6b1b78d96eChris Lattner return true; 17121347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner } 17131347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner return false; 17141347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner} 17151347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner 1716867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner/// SimplifyCondBranchToCondBranch - If we have a conditional branch as a 1717867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner/// predecessor of another block, this function tries to simplify it. We know 1718867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner/// that PBI and BI are both conditional branches, and BI is in one of the 1719867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner/// successor blocks of PBI - PBI branches to BI. 1720867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattnerstatic bool SimplifyCondBranchToCondBranch(BranchInst *PBI, BranchInst *BI) { 1721867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner assert(PBI->isConditional() && BI->isConditional()); 1722867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner BasicBlock *BB = BI->getParent(); 17234ae5126d041768ab9665cf2f11c024becd76c41fDan Gohman 1724867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner // If this block ends with a branch instruction, and if there is a 1725867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner // predecessor that ends on a branch of the same condition, make 1726867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner // this conditional branch redundant. 1727867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner if (PBI->getCondition() == BI->getCondition() && 1728867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner PBI->getSuccessor(0) != PBI->getSuccessor(1)) { 1729867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner // Okay, the outcome of this conditional branch is statically 1730867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner // knowable. If this block had a single pred, handle specially. 1731867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner if (BB->getSinglePredecessor()) { 1732867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner // Turn this into a branch on constant. 1733867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner bool CondIsTrue = PBI->getSuccessor(0) == BB; 17341d0be15f89cb5056e20e2d24faa8d6afb1573bcaOwen Anderson BI->setCondition(ConstantInt::get(Type::getInt1Ty(BB->getContext()), 17351d0be15f89cb5056e20e2d24faa8d6afb1573bcaOwen Anderson CondIsTrue)); 1736867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner return true; // Nuke the branch on constant. 1737867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner } 1738867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner 1739867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner // Otherwise, if there are multiple predecessors, insert a PHI that merges 1740867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner // in the constant and simplify the block result. Subsequent passes of 1741867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner // simplifycfg will thread the block. 1742867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner if (BlockIsSimpleEnoughToThreadThrough(BB)) { 1743d8b4fb4aab4d6fedb2b14bed1b846451b17bde7cJay Foad pred_iterator PB = pred_begin(BB), PE = pred_end(BB); 17441d0be15f89cb5056e20e2d24faa8d6afb1573bcaOwen Anderson PHINode *NewPN = PHINode::Create(Type::getInt1Ty(BB->getContext()), 17453ecfc861b4365f341c5c969b40e1afccde676e6fJay Foad std::distance(PB, PE), 1746867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner BI->getCondition()->getName() + ".pr", 1747867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner BB->begin()); 1748eb388af89f15ee3de6f53359473e1a54418a667fChris Lattner // Okay, we're going to insert the PHI node. Since PBI is not the only 1749eb388af89f15ee3de6f53359473e1a54418a667fChris Lattner // predecessor, compute the PHI'd conditional value for all of the preds. 1750eb388af89f15ee3de6f53359473e1a54418a667fChris Lattner // Any predecessor where the condition is not computable we keep symbolic. 1751d8b4fb4aab4d6fedb2b14bed1b846451b17bde7cJay Foad for (pred_iterator PI = PB; PI != PE; ++PI) { 1752625398343e2673a0c4bb5228fc88f71fe4e1c629Gabor Greif BasicBlock *P = *PI; 1753625398343e2673a0c4bb5228fc88f71fe4e1c629Gabor Greif if ((PBI = dyn_cast<BranchInst>(P->getTerminator())) && 1754867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner PBI != BI && PBI->isConditional() && 1755867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner PBI->getCondition() == BI->getCondition() && 1756867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner PBI->getSuccessor(0) != PBI->getSuccessor(1)) { 1757867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner bool CondIsTrue = PBI->getSuccessor(0) == BB; 17581d0be15f89cb5056e20e2d24faa8d6afb1573bcaOwen Anderson NewPN->addIncoming(ConstantInt::get(Type::getInt1Ty(BB->getContext()), 1759625398343e2673a0c4bb5228fc88f71fe4e1c629Gabor Greif CondIsTrue), P); 1760867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner } else { 1761625398343e2673a0c4bb5228fc88f71fe4e1c629Gabor Greif NewPN->addIncoming(BI->getCondition(), P); 1762867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner } 1763625398343e2673a0c4bb5228fc88f71fe4e1c629Gabor Greif } 1764867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner 1765867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner BI->setCondition(NewPN); 1766867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner return true; 1767867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner } 1768867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner } 1769867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner 1770867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner // If this is a conditional branch in an empty block, and if any 1771867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner // predecessors is a conditional branch to one of our destinations, 1772867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner // fold the conditions into logical ops and one cond br. 1773a8d57fe96bb870e4f69c6b522a78936d1495d0d2Zhou Sheng BasicBlock::iterator BBI = BB->begin(); 1774a8d57fe96bb870e4f69c6b522a78936d1495d0d2Zhou Sheng // Ignore dbg intrinsics. 1775a8d57fe96bb870e4f69c6b522a78936d1495d0d2Zhou Sheng while (isa<DbgInfoIntrinsic>(BBI)) 1776a8d57fe96bb870e4f69c6b522a78936d1495d0d2Zhou Sheng ++BBI; 1777a8d57fe96bb870e4f69c6b522a78936d1495d0d2Zhou Sheng if (&*BBI != BI) 1778b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner return false; 177963bf29b5b1c741038d6d502d62721cac0d2760b4Chris Lattner 178063bf29b5b1c741038d6d502d62721cac0d2760b4Chris Lattner 178163bf29b5b1c741038d6d502d62721cac0d2760b4Chris Lattner if (ConstantExpr *CE = dyn_cast<ConstantExpr>(BI->getCondition())) 178263bf29b5b1c741038d6d502d62721cac0d2760b4Chris Lattner if (CE->canTrap()) 178363bf29b5b1c741038d6d502d62721cac0d2760b4Chris Lattner return false; 1784b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner 1785b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner int PBIOp, BIOp; 1786b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner if (PBI->getSuccessor(0) == BI->getSuccessor(0)) 1787b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner PBIOp = BIOp = 0; 1788b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner else if (PBI->getSuccessor(0) == BI->getSuccessor(1)) 1789b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner PBIOp = 0, BIOp = 1; 1790b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner else if (PBI->getSuccessor(1) == BI->getSuccessor(0)) 1791b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner PBIOp = 1, BIOp = 0; 1792b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner else if (PBI->getSuccessor(1) == BI->getSuccessor(1)) 1793b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner PBIOp = BIOp = 1; 1794b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner else 1795b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner return false; 1796867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner 1797b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // Check to make sure that the other destination of this branch 1798b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // isn't BB itself. If so, this is an infinite loop that will 1799b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // keep getting unwound. 1800b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner if (PBI->getSuccessor(PBIOp) == BB) 1801b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner return false; 1802867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner 1803b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // Do not perform this transformation if it would require 1804b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // insertion of a large number of select instructions. For targets 1805b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // without predication/cmovs, this is a big pessimization. 1806b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner BasicBlock *CommonDest = PBI->getSuccessor(PBIOp); 1807867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner 1808b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner unsigned NumPhis = 0; 1809b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner for (BasicBlock::iterator II = CommonDest->begin(); 1810b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner isa<PHINode>(II); ++II, ++NumPhis) 1811b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner if (NumPhis > 2) // Disable this xform. 1812b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner return false; 1813867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner 1814b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // Finally, if everything is ok, fold the branches to logical ops. 1815b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner BasicBlock *OtherDest = BI->getSuccessor(BIOp ^ 1); 1816b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner 181789d6fd36a26fdf068ceea90422dc2897e89700b5David Greene DEBUG(dbgs() << "FOLDING BRs:" << *PBI->getParent() 1818bdff548e4dd577a72094d57b282de4e765643b96Chris Lattner << "AND: " << *BI->getParent()); 1819b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner 1820093a4385027235459ab6972b2e2fdc79061773cfChris Lattner 1821093a4385027235459ab6972b2e2fdc79061773cfChris Lattner // If OtherDest *is* BB, then BB is a basic block with a single conditional 1822093a4385027235459ab6972b2e2fdc79061773cfChris Lattner // branch in it, where one edge (OtherDest) goes back to itself but the other 1823093a4385027235459ab6972b2e2fdc79061773cfChris Lattner // exits. We don't *know* that the program avoids the infinite loop 1824093a4385027235459ab6972b2e2fdc79061773cfChris Lattner // (even though that seems likely). If we do this xform naively, we'll end up 1825093a4385027235459ab6972b2e2fdc79061773cfChris Lattner // recursively unpeeling the loop. Since we know that (after the xform is 1826093a4385027235459ab6972b2e2fdc79061773cfChris Lattner // done) that the block *is* infinite if reached, we just make it an obviously 1827093a4385027235459ab6972b2e2fdc79061773cfChris Lattner // infinite loop with no cond branch. 1828093a4385027235459ab6972b2e2fdc79061773cfChris Lattner if (OtherDest == BB) { 1829093a4385027235459ab6972b2e2fdc79061773cfChris Lattner // Insert it at the end of the function, because it's either code, 1830093a4385027235459ab6972b2e2fdc79061773cfChris Lattner // or it won't matter if it's hot. :) 18311d0be15f89cb5056e20e2d24faa8d6afb1573bcaOwen Anderson BasicBlock *InfLoopBlock = BasicBlock::Create(BB->getContext(), 18321d0be15f89cb5056e20e2d24faa8d6afb1573bcaOwen Anderson "infloop", BB->getParent()); 1833093a4385027235459ab6972b2e2fdc79061773cfChris Lattner BranchInst::Create(InfLoopBlock, InfLoopBlock); 1834093a4385027235459ab6972b2e2fdc79061773cfChris Lattner OtherDest = InfLoopBlock; 1835093a4385027235459ab6972b2e2fdc79061773cfChris Lattner } 1836093a4385027235459ab6972b2e2fdc79061773cfChris Lattner 183789d6fd36a26fdf068ceea90422dc2897e89700b5David Greene DEBUG(dbgs() << *PBI->getParent()->getParent()); 1838d3a1788da15311781f661c1cbfe48cd5f98ae778Devang Patel 1839b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // BI may have other predecessors. Because of this, we leave 1840b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // it alone, but modify PBI. 1841b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner 1842b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // Make sure we get to CommonDest on True&True directions. 1843b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner Value *PBICond = PBI->getCondition(); 1844d3a1788da15311781f661c1cbfe48cd5f98ae778Devang Patel IRBuilder<true, NoFolder> Builder(PBI); 1845b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner if (PBIOp) 1846d3a1788da15311781f661c1cbfe48cd5f98ae778Devang Patel PBICond = Builder.CreateNot(PBICond, PBICond->getName()+".not"); 1847d3a1788da15311781f661c1cbfe48cd5f98ae778Devang Patel 1848b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner Value *BICond = BI->getCondition(); 1849b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner if (BIOp) 1850d3a1788da15311781f661c1cbfe48cd5f98ae778Devang Patel BICond = Builder.CreateNot(BICond, BICond->getName()+".not"); 1851d3a1788da15311781f661c1cbfe48cd5f98ae778Devang Patel 1852b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // Merge the conditions. 1853d3a1788da15311781f661c1cbfe48cd5f98ae778Devang Patel Value *Cond = Builder.CreateOr(PBICond, BICond, "brmerge"); 1854b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner 1855b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // Modify PBI to branch on the new condition to the new dests. 1856b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner PBI->setCondition(Cond); 1857b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner PBI->setSuccessor(0, CommonDest); 1858b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner PBI->setSuccessor(1, OtherDest); 1859b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner 1860b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // OtherDest may have phi nodes. If so, add an entry from PBI's 1861b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // block that are identical to the entries for BI's block. 18626de0a28dfb84095ebd7775f371dd4085cf955076Chris Lattner AddPredecessorToBlock(OtherDest, PBI->getParent(), BB); 1863b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner 1864b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // We know that the CommonDest already had an edge from PBI to 1865b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // it. If it has PHIs though, the PHIs may have different 1866b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // entries for BB and PBI's BB. If so, insert a select to make 1867b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // them agree. 18686de0a28dfb84095ebd7775f371dd4085cf955076Chris Lattner PHINode *PN; 1869b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner for (BasicBlock::iterator II = CommonDest->begin(); 1870b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner (PN = dyn_cast<PHINode>(II)); ++II) { 1871b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner Value *BIV = PN->getIncomingValueForBlock(BB); 1872b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner unsigned PBBIdx = PN->getBasicBlockIndex(PBI->getParent()); 1873b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner Value *PBIV = PN->getIncomingValue(PBBIdx); 1874b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner if (BIV != PBIV) { 1875b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // Insert a select in PBI to pick the right value. 1876d3a1788da15311781f661c1cbfe48cd5f98ae778Devang Patel Value *NV = cast<SelectInst> 1877d3a1788da15311781f661c1cbfe48cd5f98ae778Devang Patel (Builder.CreateSelect(PBICond, PBIV, BIV, PBIV->getName()+".mux")); 1878b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner PN->setIncomingValue(PBBIdx, NV); 1879867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner } 1880867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner } 1881b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner 188289d6fd36a26fdf068ceea90422dc2897e89700b5David Greene DEBUG(dbgs() << "INTO: " << *PBI->getParent()); 188389d6fd36a26fdf068ceea90422dc2897e89700b5David Greene DEBUG(dbgs() << *PBI->getParent()->getParent()); 1884b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner 1885b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // This basic block is probably dead. We know it has at least 1886b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // one fewer predecessor. 1887b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner return true; 1888867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner} 1889867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner 189065fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel// SimplifyTerminatorOnSelect - Simplifies a terminator by replacing it with a 189165fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel// branch to TrueBB if Cond is true or to FalseBB if Cond is false. 189265fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel// Takes care of updating the successors and removing the old terminator. 189365fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel// Also makes sure not to introduce new successors by assuming that edges to 189465fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel// non-successor TrueBBs and FalseBBs aren't reachable. 189565fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommelstatic bool SimplifyTerminatorOnSelect(TerminatorInst *OldTerm, Value *Cond, 189665fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel BasicBlock *TrueBB, BasicBlock *FalseBB){ 18977ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel // Remove any superfluous successor edges from the CFG. 18987ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel // First, figure out which successors to preserve. 18997ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel // If TrueBB and FalseBB are equal, only try to preserve one copy of that 19007ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel // successor. 19017ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel BasicBlock *KeepEdge1 = TrueBB; 19027ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel BasicBlock *KeepEdge2 = TrueBB != FalseBB ? FalseBB : 0; 19037ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel 19047ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel // Then remove the rest. 190565fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel for (unsigned I = 0, E = OldTerm->getNumSuccessors(); I != E; ++I) { 190665fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel BasicBlock *Succ = OldTerm->getSuccessor(I); 19077ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel // Make sure only to keep exactly one copy of each edge. 19087ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel if (Succ == KeepEdge1) 19097ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel KeepEdge1 = 0; 19107ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel else if (Succ == KeepEdge2) 19117ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel KeepEdge2 = 0; 19127ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel else 191365fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel Succ->removePredecessor(OldTerm->getParent()); 19147ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel } 19157ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel 1916d3372b85e6008d85e30d13172ef0b1646b482b7eDevang Patel IRBuilder<> Builder(OldTerm); 1917d3372b85e6008d85e30d13172ef0b1646b482b7eDevang Patel Builder.SetCurrentDebugLocation(OldTerm->getDebugLoc()); 1918d3372b85e6008d85e30d13172ef0b1646b482b7eDevang Patel 19197ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel // Insert an appropriate new terminator. 19207ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel if ((KeepEdge1 == 0) && (KeepEdge2 == 0)) { 19217ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel if (TrueBB == FalseBB) 19227ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel // We were only looking for one successor, and it was present. 19237ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel // Create an unconditional branch to it. 1924d3372b85e6008d85e30d13172ef0b1646b482b7eDevang Patel Builder.CreateBr(TrueBB); 19257ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel else 19267ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel // We found both of the successors we were looking for. 19277ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel // Create a conditional branch sharing the condition of the select. 1928d3372b85e6008d85e30d13172ef0b1646b482b7eDevang Patel Builder.CreateCondBr(Cond, TrueBB, FalseBB); 19297ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel } else if (KeepEdge1 && (KeepEdge2 || TrueBB == FalseBB)) { 19307ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel // Neither of the selected blocks were successors, so this 193165fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel // terminator must be unreachable. 193265fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel new UnreachableInst(OldTerm->getContext(), OldTerm); 19337ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel } else { 19347ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel // One of the selected values was a successor, but the other wasn't. 19357ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel // Insert an unconditional branch to the one that was found; 19367ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel // the edge to the one that wasn't must be unreachable. 19377ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel if (KeepEdge1 == 0) 19387ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel // Only TrueBB was found. 1939d3372b85e6008d85e30d13172ef0b1646b482b7eDevang Patel Builder.CreateBr(TrueBB); 19407ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel else 19417ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel // Only FalseBB was found. 1942d3372b85e6008d85e30d13172ef0b1646b482b7eDevang Patel Builder.CreateBr(FalseBB); 19437ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel } 19447ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel 194565fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel EraseTerminatorInstAndDCECond(OldTerm); 19467ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel return true; 19477ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel} 19487ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel 1949f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel// SimplifySwitchOnSelect - Replaces 1950f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel// (switch (select cond, X, Y)) on constant X, Y 1951f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel// with a branch - conditional if X and Y lead to distinct BBs, 1952f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel// unconditional otherwise. 1953f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommelstatic bool SimplifySwitchOnSelect(SwitchInst *SI, SelectInst *Select) { 1954f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel // Check for constant integer values in the select. 1955f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel ConstantInt *TrueVal = dyn_cast<ConstantInt>(Select->getTrueValue()); 1956f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel ConstantInt *FalseVal = dyn_cast<ConstantInt>(Select->getFalseValue()); 1957f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel if (!TrueVal || !FalseVal) 1958f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel return false; 1959f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel 1960f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel // Find the relevant condition and destinations. 1961f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel Value *Condition = Select->getCondition(); 1962f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel BasicBlock *TrueBB = SI->getSuccessor(SI->findCaseValue(TrueVal)); 1963f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel BasicBlock *FalseBB = SI->getSuccessor(SI->findCaseValue(FalseVal)); 1964f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel 1965f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel // Perform the actual simplification. 1966f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel return SimplifyTerminatorOnSelect(SI, Condition, TrueBB, FalseBB); 1967f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel} 1968f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel 196965fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel// SimplifyIndirectBrOnSelect - Replaces 197065fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel// (indirectbr (select cond, blockaddress(@fn, BlockA), 197165fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel// blockaddress(@fn, BlockB))) 197265fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel// with 197365fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel// (br cond, BlockA, BlockB). 197465fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommelstatic bool SimplifyIndirectBrOnSelect(IndirectBrInst *IBI, SelectInst *SI) { 197565fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel // Check that both operands of the select are block addresses. 197665fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel BlockAddress *TBA = dyn_cast<BlockAddress>(SI->getTrueValue()); 197765fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel BlockAddress *FBA = dyn_cast<BlockAddress>(SI->getFalseValue()); 197865fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel if (!TBA || !FBA) 197965fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel return false; 198065fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel 198165fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel // Extract the actual blocks. 198265fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel BasicBlock *TrueBB = TBA->getBasicBlock(); 198365fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel BasicBlock *FalseBB = FBA->getBasicBlock(); 198465fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel 198565fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel // Perform the actual simplification. 198665fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel return SimplifyTerminatorOnSelect(IBI, SI->getCondition(), TrueBB, FalseBB); 198765fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel} 198865fdded3197461232d8428af7ddd0107e4a9f946Frits van Bommel 198961c77449c772427a0d2559fca500debd93c7f97cChris Lattner/// TryToSimplifyUncondBranchWithICmpInIt - This is called when we find an icmp 199061c77449c772427a0d2559fca500debd93c7f97cChris Lattner/// instruction (a seteq/setne with a constant) as the only instruction in a 199161c77449c772427a0d2559fca500debd93c7f97cChris Lattner/// block that ends with an uncond branch. We are looking for a very specific 199261c77449c772427a0d2559fca500debd93c7f97cChris Lattner/// pattern that occurs when "A == 1 || A == 2 || A == 3" gets simplified. In 199361c77449c772427a0d2559fca500debd93c7f97cChris Lattner/// this case, we merge the first two "or's of icmp" into a switch, but then the 199461c77449c772427a0d2559fca500debd93c7f97cChris Lattner/// default value goes to an uncond block with a seteq in it, we get something 199561c77449c772427a0d2559fca500debd93c7f97cChris Lattner/// like: 199661c77449c772427a0d2559fca500debd93c7f97cChris Lattner/// 199761c77449c772427a0d2559fca500debd93c7f97cChris Lattner/// switch i8 %A, label %DEFAULT [ i8 1, label %end i8 2, label %end ] 199861c77449c772427a0d2559fca500debd93c7f97cChris Lattner/// DEFAULT: 199961c77449c772427a0d2559fca500debd93c7f97cChris Lattner/// %tmp = icmp eq i8 %A, 92 200061c77449c772427a0d2559fca500debd93c7f97cChris Lattner/// br label %end 200161c77449c772427a0d2559fca500debd93c7f97cChris Lattner/// end: 200261c77449c772427a0d2559fca500debd93c7f97cChris Lattner/// ... = phi i1 [ true, %entry ], [ %tmp, %DEFAULT ], [ true, %entry ] 200361c77449c772427a0d2559fca500debd93c7f97cChris Lattner/// 200461c77449c772427a0d2559fca500debd93c7f97cChris Lattner/// We prefer to split the edge to 'end' so that there is a true/false entry to 200561c77449c772427a0d2559fca500debd93c7f97cChris Lattner/// the PHI, merging the third icmp into the switch. 2006302ba6fc1cb26248b0d6524fc42c740370926d6dChris Lattnerstatic bool TryToSimplifyUncondBranchWithICmpInIt(ICmpInst *ICI, 2007a23812cfbd23604d2fc103cf232cde8fa270a491Devang Patel const TargetData *TD, 2008a23812cfbd23604d2fc103cf232cde8fa270a491Devang Patel IRBuilder<> &Builder) { 200961c77449c772427a0d2559fca500debd93c7f97cChris Lattner BasicBlock *BB = ICI->getParent(); 2010a23812cfbd23604d2fc103cf232cde8fa270a491Devang Patel 201161c77449c772427a0d2559fca500debd93c7f97cChris Lattner // If the block has any PHIs in it or the icmp has multiple uses, it is too 201261c77449c772427a0d2559fca500debd93c7f97cChris Lattner // complex. 201361c77449c772427a0d2559fca500debd93c7f97cChris Lattner if (isa<PHINode>(BB->begin()) || !ICI->hasOneUse()) return false; 201461c77449c772427a0d2559fca500debd93c7f97cChris Lattner 201561c77449c772427a0d2559fca500debd93c7f97cChris Lattner Value *V = ICI->getOperand(0); 201661c77449c772427a0d2559fca500debd93c7f97cChris Lattner ConstantInt *Cst = cast<ConstantInt>(ICI->getOperand(1)); 201761c77449c772427a0d2559fca500debd93c7f97cChris Lattner 201861c77449c772427a0d2559fca500debd93c7f97cChris Lattner // The pattern we're looking for is where our only predecessor is a switch on 201961c77449c772427a0d2559fca500debd93c7f97cChris Lattner // 'V' and this block is the default case for the switch. In this case we can 202061c77449c772427a0d2559fca500debd93c7f97cChris Lattner // fold the compared value into the switch to simplify things. 202161c77449c772427a0d2559fca500debd93c7f97cChris Lattner BasicBlock *Pred = BB->getSinglePredecessor(); 202261c77449c772427a0d2559fca500debd93c7f97cChris Lattner if (Pred == 0 || !isa<SwitchInst>(Pred->getTerminator())) return false; 202361c77449c772427a0d2559fca500debd93c7f97cChris Lattner 202461c77449c772427a0d2559fca500debd93c7f97cChris Lattner SwitchInst *SI = cast<SwitchInst>(Pred->getTerminator()); 202561c77449c772427a0d2559fca500debd93c7f97cChris Lattner if (SI->getCondition() != V) 202661c77449c772427a0d2559fca500debd93c7f97cChris Lattner return false; 202761c77449c772427a0d2559fca500debd93c7f97cChris Lattner 202861c77449c772427a0d2559fca500debd93c7f97cChris Lattner // If BB is reachable on a non-default case, then we simply know the value of 202961c77449c772427a0d2559fca500debd93c7f97cChris Lattner // V in this block. Substitute it and constant fold the icmp instruction 203061c77449c772427a0d2559fca500debd93c7f97cChris Lattner // away. 203161c77449c772427a0d2559fca500debd93c7f97cChris Lattner if (SI->getDefaultDest() != BB) { 203261c77449c772427a0d2559fca500debd93c7f97cChris Lattner ConstantInt *VVal = SI->findCaseDest(BB); 203361c77449c772427a0d2559fca500debd93c7f97cChris Lattner assert(VVal && "Should have a unique destination value"); 203461c77449c772427a0d2559fca500debd93c7f97cChris Lattner ICI->setOperand(0, VVal); 203561c77449c772427a0d2559fca500debd93c7f97cChris Lattner 2036302ba6fc1cb26248b0d6524fc42c740370926d6dChris Lattner if (Value *V = SimplifyInstruction(ICI, TD)) { 2037302ba6fc1cb26248b0d6524fc42c740370926d6dChris Lattner ICI->replaceAllUsesWith(V); 203861c77449c772427a0d2559fca500debd93c7f97cChris Lattner ICI->eraseFromParent(); 203961c77449c772427a0d2559fca500debd93c7f97cChris Lattner } 204061c77449c772427a0d2559fca500debd93c7f97cChris Lattner // BB is now empty, so it is likely to simplify away. 204161c77449c772427a0d2559fca500debd93c7f97cChris Lattner return SimplifyCFG(BB) | true; 204261c77449c772427a0d2559fca500debd93c7f97cChris Lattner } 204361c77449c772427a0d2559fca500debd93c7f97cChris Lattner 2044abf706703fcbcde8fdc69b1bbdfb34e874813107Chris Lattner // Ok, the block is reachable from the default dest. If the constant we're 2045abf706703fcbcde8fdc69b1bbdfb34e874813107Chris Lattner // comparing exists in one of the other edges, then we can constant fold ICI 2046abf706703fcbcde8fdc69b1bbdfb34e874813107Chris Lattner // and zap it. 2047abf706703fcbcde8fdc69b1bbdfb34e874813107Chris Lattner if (SI->findCaseValue(Cst) != 0) { 2048abf706703fcbcde8fdc69b1bbdfb34e874813107Chris Lattner Value *V; 2049abf706703fcbcde8fdc69b1bbdfb34e874813107Chris Lattner if (ICI->getPredicate() == ICmpInst::ICMP_EQ) 2050abf706703fcbcde8fdc69b1bbdfb34e874813107Chris Lattner V = ConstantInt::getFalse(BB->getContext()); 2051abf706703fcbcde8fdc69b1bbdfb34e874813107Chris Lattner else 2052abf706703fcbcde8fdc69b1bbdfb34e874813107Chris Lattner V = ConstantInt::getTrue(BB->getContext()); 2053abf706703fcbcde8fdc69b1bbdfb34e874813107Chris Lattner 2054abf706703fcbcde8fdc69b1bbdfb34e874813107Chris Lattner ICI->replaceAllUsesWith(V); 2055abf706703fcbcde8fdc69b1bbdfb34e874813107Chris Lattner ICI->eraseFromParent(); 2056abf706703fcbcde8fdc69b1bbdfb34e874813107Chris Lattner // BB is now empty, so it is likely to simplify away. 2057abf706703fcbcde8fdc69b1bbdfb34e874813107Chris Lattner return SimplifyCFG(BB) | true; 2058abf706703fcbcde8fdc69b1bbdfb34e874813107Chris Lattner } 2059abf706703fcbcde8fdc69b1bbdfb34e874813107Chris Lattner 206061c77449c772427a0d2559fca500debd93c7f97cChris Lattner // The use of the icmp has to be in the 'end' block, by the only PHI node in 206161c77449c772427a0d2559fca500debd93c7f97cChris Lattner // the block. 206261c77449c772427a0d2559fca500debd93c7f97cChris Lattner BasicBlock *SuccBlock = BB->getTerminator()->getSuccessor(0); 206361c77449c772427a0d2559fca500debd93c7f97cChris Lattner PHINode *PHIUse = dyn_cast<PHINode>(ICI->use_back()); 206461c77449c772427a0d2559fca500debd93c7f97cChris Lattner if (PHIUse == 0 || PHIUse != &SuccBlock->front() || 206561c77449c772427a0d2559fca500debd93c7f97cChris Lattner isa<PHINode>(++BasicBlock::iterator(PHIUse))) 206661c77449c772427a0d2559fca500debd93c7f97cChris Lattner return false; 206761c77449c772427a0d2559fca500debd93c7f97cChris Lattner 206861c77449c772427a0d2559fca500debd93c7f97cChris Lattner // If the icmp is a SETEQ, then the default dest gets false, the new edge gets 206961c77449c772427a0d2559fca500debd93c7f97cChris Lattner // true in the PHI. 207061c77449c772427a0d2559fca500debd93c7f97cChris Lattner Constant *DefaultCst = ConstantInt::getTrue(BB->getContext()); 207161c77449c772427a0d2559fca500debd93c7f97cChris Lattner Constant *NewCst = ConstantInt::getFalse(BB->getContext()); 207261c77449c772427a0d2559fca500debd93c7f97cChris Lattner 207361c77449c772427a0d2559fca500debd93c7f97cChris Lattner if (ICI->getPredicate() == ICmpInst::ICMP_EQ) 207461c77449c772427a0d2559fca500debd93c7f97cChris Lattner std::swap(DefaultCst, NewCst); 207561c77449c772427a0d2559fca500debd93c7f97cChris Lattner 207661c77449c772427a0d2559fca500debd93c7f97cChris Lattner // Replace ICI (which is used by the PHI for the default value) with true or 207761c77449c772427a0d2559fca500debd93c7f97cChris Lattner // false depending on if it is EQ or NE. 207861c77449c772427a0d2559fca500debd93c7f97cChris Lattner ICI->replaceAllUsesWith(DefaultCst); 207961c77449c772427a0d2559fca500debd93c7f97cChris Lattner ICI->eraseFromParent(); 208061c77449c772427a0d2559fca500debd93c7f97cChris Lattner 208161c77449c772427a0d2559fca500debd93c7f97cChris Lattner // Okay, the switch goes to this block on a default value. Add an edge from 208261c77449c772427a0d2559fca500debd93c7f97cChris Lattner // the switch to the merge point on the compared value. 208361c77449c772427a0d2559fca500debd93c7f97cChris Lattner BasicBlock *NewBB = BasicBlock::Create(BB->getContext(), "switch.edge", 208461c77449c772427a0d2559fca500debd93c7f97cChris Lattner BB->getParent(), BB); 208561c77449c772427a0d2559fca500debd93c7f97cChris Lattner SI->addCase(Cst, NewBB); 208661c77449c772427a0d2559fca500debd93c7f97cChris Lattner 208761c77449c772427a0d2559fca500debd93c7f97cChris Lattner // NewBB branches to the phi block, add the uncond branch and the phi entry. 2088a23812cfbd23604d2fc103cf232cde8fa270a491Devang Patel Builder.SetInsertPoint(NewBB); 2089a23812cfbd23604d2fc103cf232cde8fa270a491Devang Patel Builder.SetCurrentDebugLocation(SI->getDebugLoc()); 2090a23812cfbd23604d2fc103cf232cde8fa270a491Devang Patel Builder.CreateBr(SuccBlock); 209161c77449c772427a0d2559fca500debd93c7f97cChris Lattner PHIUse->addIncoming(NewCst, NewBB); 209261c77449c772427a0d2559fca500debd93c7f97cChris Lattner return true; 209361c77449c772427a0d2559fca500debd93c7f97cChris Lattner} 209461c77449c772427a0d2559fca500debd93c7f97cChris Lattner 209597fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner/// SimplifyBranchOnICmpChain - The specified branch is a conditional branch. 209697fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner/// Check to see if it is branching on an or/and chain of icmp instructions, and 209797fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner/// fold it into a switch instruction if so. 209802dd5418d29c2a43f225df887923e144e12e7ec6Devang Patelstatic bool SimplifyBranchOnICmpChain(BranchInst *BI, const TargetData *TD, 209902dd5418d29c2a43f225df887923e144e12e7ec6Devang Patel IRBuilder<> &Builder) { 210097fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner Instruction *Cond = dyn_cast<Instruction>(BI->getCondition()); 210197fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner if (Cond == 0) return false; 210297fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner 210397fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner 210497fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner // Change br (X == 0 | X == 1), T, F into a switch instruction. 210597fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner // If this is a bunch of seteq's or'd together, or if it's a bunch of 210697fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner // 'setne's and'ed together, collect them. 210797fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner Value *CompVal = 0; 210897fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner std::vector<ConstantInt*> Values; 210997fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner bool TrueWhenEqual = true; 211097fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner Value *ExtraCase = 0; 211133828bcb24176aae72afac0e4953e4b7f9560ef1Benjamin Kramer unsigned UsedICmps = 0; 211297fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner 211397fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner if (Cond->getOpcode() == Instruction::Or) { 211433828bcb24176aae72afac0e4953e4b7f9560ef1Benjamin Kramer CompVal = GatherConstantCompares(Cond, Values, ExtraCase, TD, true, 211533828bcb24176aae72afac0e4953e4b7f9560ef1Benjamin Kramer UsedICmps); 211697fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner } else if (Cond->getOpcode() == Instruction::And) { 211733828bcb24176aae72afac0e4953e4b7f9560ef1Benjamin Kramer CompVal = GatherConstantCompares(Cond, Values, ExtraCase, TD, false, 211833828bcb24176aae72afac0e4953e4b7f9560ef1Benjamin Kramer UsedICmps); 211997fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner TrueWhenEqual = false; 212097fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner } 212197fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner 212297fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner // If we didn't have a multiply compared value, fail. 212397fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner if (CompVal == 0) return false; 212497fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner 212533828bcb24176aae72afac0e4953e4b7f9560ef1Benjamin Kramer // Avoid turning single icmps into a switch. 212633828bcb24176aae72afac0e4953e4b7f9560ef1Benjamin Kramer if (UsedICmps <= 1) 212733828bcb24176aae72afac0e4953e4b7f9560ef1Benjamin Kramer return false; 212833828bcb24176aae72afac0e4953e4b7f9560ef1Benjamin Kramer 212997fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner // There might be duplicate constants in the list, which the switch 213097fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner // instruction can't handle, remove them now. 213197fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner array_pod_sort(Values.begin(), Values.end(), ConstantIntSortPredicate); 213297fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner Values.erase(std::unique(Values.begin(), Values.end()), Values.end()); 213397fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner 213497fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner // If Extra was used, we require at least two switch values to do the 213597fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner // transformation. A switch with one value is just an cond branch. 213697fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner if (ExtraCase && Values.size() < 2) return false; 213797fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner 213897fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner // Figure out which block is which destination. 213997fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner BasicBlock *DefaultBB = BI->getSuccessor(1); 214097fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner BasicBlock *EdgeBB = BI->getSuccessor(0); 214197fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner if (!TrueWhenEqual) std::swap(DefaultBB, EdgeBB); 214297fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner 214397fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner BasicBlock *BB = BI->getParent(); 214497fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner 2145302ba6fc1cb26248b0d6524fc42c740370926d6dChris Lattner DEBUG(dbgs() << "Converting 'icmp' chain with " << Values.size() 2146117f8cffc5499217ff8824eb0d6a0f6b1b78d96eChris Lattner << " cases into SWITCH. BB is:\n" << *BB); 2147117f8cffc5499217ff8824eb0d6a0f6b1b78d96eChris Lattner 214897fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner // If there are any extra values that couldn't be folded into the switch 214997fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner // then we evaluate them with an explicit branch first. Split the block 215097fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner // right before the condbr to handle it. 215197fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner if (ExtraCase) { 215297fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner BasicBlock *NewBB = BB->splitBasicBlock(BI, "switch.early.test"); 215397fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner // Remove the uncond branch added to the old block. 215497fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner TerminatorInst *OldTI = BB->getTerminator(); 215502dd5418d29c2a43f225df887923e144e12e7ec6Devang Patel Builder.SetInsertPoint(OldTI); 215602dd5418d29c2a43f225df887923e144e12e7ec6Devang Patel 2157117f8cffc5499217ff8824eb0d6a0f6b1b78d96eChris Lattner if (TrueWhenEqual) 215802dd5418d29c2a43f225df887923e144e12e7ec6Devang Patel Builder.CreateCondBr(ExtraCase, EdgeBB, NewBB); 2159117f8cffc5499217ff8824eb0d6a0f6b1b78d96eChris Lattner else 216002dd5418d29c2a43f225df887923e144e12e7ec6Devang Patel Builder.CreateCondBr(ExtraCase, NewBB, EdgeBB); 2161117f8cffc5499217ff8824eb0d6a0f6b1b78d96eChris Lattner 216297fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner OldTI->eraseFromParent(); 216397bd89ece3fff29ab7e0eaa38f85183abd962f42Chris Lattner 216497bd89ece3fff29ab7e0eaa38f85183abd962f42Chris Lattner // If there are PHI nodes in EdgeBB, then we need to add a new entry to them 216597bd89ece3fff29ab7e0eaa38f85183abd962f42Chris Lattner // for the edge we just added. 21666de0a28dfb84095ebd7775f371dd4085cf955076Chris Lattner AddPredecessorToBlock(EdgeBB, BB, NewBB); 2167302ba6fc1cb26248b0d6524fc42c740370926d6dChris Lattner 2168302ba6fc1cb26248b0d6524fc42c740370926d6dChris Lattner DEBUG(dbgs() << " ** 'icmp' chain unhandled condition: " << *ExtraCase 2169302ba6fc1cb26248b0d6524fc42c740370926d6dChris Lattner << "\nEXTRABB = " << *BB); 217097fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner BB = NewBB; 217197fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner } 217202dd5418d29c2a43f225df887923e144e12e7ec6Devang Patel 217302dd5418d29c2a43f225df887923e144e12e7ec6Devang Patel Builder.SetInsertPoint(BI); 217497fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner // Convert pointer to int before we switch. 217597fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner if (CompVal->getType()->isPointerTy()) { 217697fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner assert(TD && "Cannot switch on pointer without TargetData"); 217702dd5418d29c2a43f225df887923e144e12e7ec6Devang Patel CompVal = Builder.CreatePtrToInt(CompVal, 217802dd5418d29c2a43f225df887923e144e12e7ec6Devang Patel TD->getIntPtrType(CompVal->getContext()), 217902dd5418d29c2a43f225df887923e144e12e7ec6Devang Patel "magicptr"); 218097fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner } 218197fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner 218297fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner // Create the new switch instruction now. 218302dd5418d29c2a43f225df887923e144e12e7ec6Devang Patel SwitchInst *New = Builder.CreateSwitch(CompVal, DefaultBB, Values.size()); 2184d80e8ed2fa20c7ad51af49c3b2650525edbdcd08Devang Patel 218597fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner // Add all of the 'cases' to the switch instruction. 218697fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner for (unsigned i = 0, e = Values.size(); i != e; ++i) 218797fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner New->addCase(Values[i], EdgeBB); 218897fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner 218997fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner // We added edges from PI to the EdgeBB. As such, if there were any 219097fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner // PHI nodes in EdgeBB, they need entries to be added corresponding to 219197fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner // the number of edges added. 219297fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner for (BasicBlock::iterator BBI = EdgeBB->begin(); 219397fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner isa<PHINode>(BBI); ++BBI) { 219497fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner PHINode *PN = cast<PHINode>(BBI); 219597fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner Value *InVal = PN->getIncomingValueForBlock(BB); 219697fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner for (unsigned i = 0, e = Values.size()-1; i != e; ++i) 219797fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner PN->addIncoming(InVal, BB); 219897fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner } 219997fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner 220097fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner // Erase the old branch instruction. 220197fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner EraseTerminatorInstAndDCECond(BI); 2202117f8cffc5499217ff8824eb0d6a0f6b1b78d96eChris Lattner 2203302ba6fc1cb26248b0d6524fc42c740370926d6dChris Lattner DEBUG(dbgs() << " ** 'icmp' chain result is:\n" << *BB << '\n'); 220497fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner return true; 220597fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner} 220697fdb898f5350e51bb40afd58e3f4e1d18e348dbChris Lattner 2207ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sandsbool SimplifyCFGOpt::SimplifyResume(ResumeInst *RI, IRBuilder<> &Builder) { 2208ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands // If this is a trivial landing pad that just continues unwinding the caught 2209ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands // exception then zap the landing pad, turning its invokes into calls. 2210ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands BasicBlock *BB = RI->getParent(); 2211ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands LandingPadInst *LPInst = dyn_cast<LandingPadInst>(BB->getFirstNonPHI()); 2212ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands if (RI->getValue() != LPInst) 2213ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands // Not a landing pad, or the resume is not unwinding the exception that 2214ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands // caused control to branch here. 2215ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands return false; 2216ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands 2217ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands // Check that there are no other instructions except for debug intrinsics. 2218ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands BasicBlock::iterator I = LPInst, E = RI; 2219ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands while (++I != E) 2220ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands if (!isa<DbgInfoIntrinsic>(I)) 2221ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands return false; 2222ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands 2223ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands // Turn all invokes that unwind here into calls and delete the basic block. 2224ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands for (pred_iterator PI = pred_begin(BB), PE = pred_end(BB); PI != PE;) { 2225ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands InvokeInst *II = cast<InvokeInst>((*PI++)->getTerminator()); 2226ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands SmallVector<Value*, 8> Args(II->op_begin(), II->op_end() - 3); 2227ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands // Insert a call instruction before the invoke. 2228ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands CallInst *Call = CallInst::Create(II->getCalledValue(), Args, "", II); 2229ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands Call->takeName(II); 2230ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands Call->setCallingConv(II->getCallingConv()); 2231ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands Call->setAttributes(II->getAttributes()); 2232ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands Call->setDebugLoc(II->getDebugLoc()); 2233ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands 2234ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands // Anything that used the value produced by the invoke instruction now uses 2235ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands // the value produced by the call instruction. Note that we do this even 2236ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands // for void functions and calls with no uses so that the callgraph edge is 2237ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands // updated. 2238ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands II->replaceAllUsesWith(Call); 2239ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands BB->removePredecessor(II->getParent()); 2240ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands 2241ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands // Insert a branch to the normal destination right before the invoke. 2242ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands BranchInst::Create(II->getNormalDest(), II); 2243ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands 2244ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands // Finally, delete the invoke instruction! 2245ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands II->eraseFromParent(); 2246ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands } 2247ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands 2248ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands // The landingpad is now unreachable. Zap it. 2249ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands BB->eraseFromParent(); 2250ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands return true; 2251ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands} 2252ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands 2253176ec40cb18c51c14fccbb38ee0db5deafb6baa9Devang Patelbool SimplifyCFGOpt::SimplifyReturn(ReturnInst *RI, IRBuilder<> &Builder) { 22543d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BasicBlock *BB = RI->getParent(); 22553d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (!BB->getFirstNonPHIOrDbg()->isTerminator()) return false; 22563d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 22573d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // Find predecessors that end with branches. 22583d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner SmallVector<BasicBlock*, 8> UncondBranchPreds; 22593d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner SmallVector<BranchInst*, 8> CondBranchPreds; 22603d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI) { 22613d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BasicBlock *P = *PI; 22623d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner TerminatorInst *PTI = P->getTerminator(); 22633d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (BranchInst *BI = dyn_cast<BranchInst>(PTI)) { 22643d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (BI->isUnconditional()) 22653d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner UncondBranchPreds.push_back(P); 22663d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner else 22673d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner CondBranchPreds.push_back(BI); 22683d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } 22693d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } 22703d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 22713d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // If we found some, do the transformation! 2272c3f507f98a0747bd256e1c13536060b6fc5c4b62Evan Cheng if (!UncondBranchPreds.empty() && DupRet) { 22733d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner while (!UncondBranchPreds.empty()) { 22743d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BasicBlock *Pred = UncondBranchPreds.pop_back_val(); 22753d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner DEBUG(dbgs() << "FOLDING: " << *BB 22763d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner << "INTO UNCOND BRANCH PRED: " << *Pred); 2277c3f507f98a0747bd256e1c13536060b6fc5c4b62Evan Cheng (void)FoldReturnIntoUncondBranch(RI, BB, Pred); 22783d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } 22793d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 22803d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // If we eliminated all predecessors of the block, delete the block now. 22813d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (pred_begin(BB) == pred_end(BB)) 22823d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // We know there are no successors, so just nuke the block. 22833d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BB->eraseFromParent(); 22843d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 228501d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner return true; 228601d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner } 22873d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 22883d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // Check out all of the conditional branches going to this return 22893d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // instruction. If any of them just select between returns, change the 22903d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // branch itself into a select/return pair. 22913d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner while (!CondBranchPreds.empty()) { 22923d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BranchInst *BI = CondBranchPreds.pop_back_val(); 22933d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 22943d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // Check to see if the non-BB successor is also a return block. 22953d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (isa<ReturnInst>(BI->getSuccessor(0)->getTerminator()) && 22963d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner isa<ReturnInst>(BI->getSuccessor(1)->getTerminator()) && 2297176ec40cb18c51c14fccbb38ee0db5deafb6baa9Devang Patel SimplifyCondBranchToTwoReturns(BI, Builder)) 22983d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner return true; 22993d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } 23003d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner return false; 23013d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner} 230201d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner 2303d46ba26a6b513086ad575e5db0069b03d41fca13Devang Patelbool SimplifyCFGOpt::SimplifyUnwind(UnwindInst *UI, IRBuilder<> &Builder) { 23043d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // Check to see if the first instruction in this block is just an unwind. 23053d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // If so, replace any invoke instructions which use this as an exception 23063d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // destination with call instructions. 23073d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BasicBlock *BB = UI->getParent(); 23083d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (!BB->getFirstNonPHIOrDbg()->isTerminator()) return false; 23092c63566e406974caa70ee27f35af28112e80f951Dan Gohman 23103d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner bool Changed = false; 23113d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner SmallVector<BasicBlock*, 8> Preds(pred_begin(BB), pred_end(BB)); 23123d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner while (!Preds.empty()) { 23133d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BasicBlock *Pred = Preds.back(); 23143d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner InvokeInst *II = dyn_cast<InvokeInst>(Pred->getTerminator()); 23153d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (II && II->getUnwindDest() == BB) { 23163d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // Insert a new branch instruction before the invoke, because this 23173d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // is now a fall through. 2318d46ba26a6b513086ad575e5db0069b03d41fca13Devang Patel Builder.SetInsertPoint(II); 2319d46ba26a6b513086ad575e5db0069b03d41fca13Devang Patel BranchInst *BI = Builder.CreateBr(II->getNormalDest()); 23203d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner Pred->getInstList().remove(II); // Take out of symbol table 23213d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 23223d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // Insert the call now. 23233d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner SmallVector<Value*,8> Args(II->op_begin(), II->op_end()-3); 2324d46ba26a6b513086ad575e5db0069b03d41fca13Devang Patel Builder.SetInsertPoint(BI); 2325d46ba26a6b513086ad575e5db0069b03d41fca13Devang Patel CallInst *CI = Builder.CreateCall(II->getCalledValue(), 2326a3efbb15ddd5aa9006564cd79086723640084878Jay Foad Args, II->getName()); 23273d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner CI->setCallingConv(II->getCallingConv()); 23283d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner CI->setAttributes(II->getAttributes()); 23293d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // If the invoke produced a value, the Call now does instead. 23303d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner II->replaceAllUsesWith(CI); 23313d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner delete II; 23323d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner Changed = true; 23333d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } 23343d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 23353d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner Preds.pop_back(); 23363d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } 23373d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 23383d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // If this block is now dead (and isn't the entry block), remove it. 23393d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (pred_begin(BB) == pred_end(BB) && 23403d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BB != &BB->getParent()->getEntryBlock()) { 23413d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // We know there are no successors, so just nuke the block. 23423d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BB->eraseFromParent(); 2343ddb97a2bf1f06d7d1b0a1af8e74c67917b43b606Chris Lattner return true; 23443d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } 2345ddb97a2bf1f06d7d1b0a1af8e74c67917b43b606Chris Lattner 23463d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner return Changed; 23473d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner} 2348882d87d168374ce790621e9ad4d7304b9dff0d78Dan Gohman 23493d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattnerbool SimplifyCFGOpt::SimplifyUnreachable(UnreachableInst *UI) { 23503d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BasicBlock *BB = UI->getParent(); 23513d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 23523d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner bool Changed = false; 23533d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 23543d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // If there are any instructions immediately before the unreachable that can 23553d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // be removed, do so. 23563d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner while (UI != BB->begin()) { 23573d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BasicBlock::iterator BBI = UI; 23583d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner --BBI; 23598176388d65083339efdfa5bee63e620c6bd05aa1Eli Friedman // Do not delete instructions that can have side effects which might cause 23608176388d65083339efdfa5bee63e620c6bd05aa1Eli Friedman // the unreachable to not be reachable; specifically, calls and volatile 23618176388d65083339efdfa5bee63e620c6bd05aa1Eli Friedman // operations may have this effect. 23623d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (isa<CallInst>(BBI) && !isa<DbgInfoIntrinsic>(BBI)) break; 23638176388d65083339efdfa5bee63e620c6bd05aa1Eli Friedman 23648176388d65083339efdfa5bee63e620c6bd05aa1Eli Friedman if (BBI->mayHaveSideEffects()) { 23658176388d65083339efdfa5bee63e620c6bd05aa1Eli Friedman if (StoreInst *SI = dyn_cast<StoreInst>(BBI)) { 23668176388d65083339efdfa5bee63e620c6bd05aa1Eli Friedman if (SI->isVolatile()) 23678176388d65083339efdfa5bee63e620c6bd05aa1Eli Friedman break; 23688176388d65083339efdfa5bee63e620c6bd05aa1Eli Friedman } else if (LoadInst *LI = dyn_cast<LoadInst>(BBI)) { 23698176388d65083339efdfa5bee63e620c6bd05aa1Eli Friedman if (LI->isVolatile()) 23708176388d65083339efdfa5bee63e620c6bd05aa1Eli Friedman break; 23718176388d65083339efdfa5bee63e620c6bd05aa1Eli Friedman } else if (AtomicRMWInst *RMWI = dyn_cast<AtomicRMWInst>(BBI)) { 23728176388d65083339efdfa5bee63e620c6bd05aa1Eli Friedman if (RMWI->isVolatile()) 23738176388d65083339efdfa5bee63e620c6bd05aa1Eli Friedman break; 23748176388d65083339efdfa5bee63e620c6bd05aa1Eli Friedman } else if (AtomicCmpXchgInst *CXI = dyn_cast<AtomicCmpXchgInst>(BBI)) { 23758176388d65083339efdfa5bee63e620c6bd05aa1Eli Friedman if (CXI->isVolatile()) 23768176388d65083339efdfa5bee63e620c6bd05aa1Eli Friedman break; 23778176388d65083339efdfa5bee63e620c6bd05aa1Eli Friedman } else if (!isa<FenceInst>(BBI) && !isa<VAArgInst>(BBI) && 23788176388d65083339efdfa5bee63e620c6bd05aa1Eli Friedman !isa<LandingPadInst>(BBI)) { 23793d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner break; 23808176388d65083339efdfa5bee63e620c6bd05aa1Eli Friedman } 238123b49ba6d55972fdffdfd4ed37edcf067bb60f3cBill Wendling // Note that deleting LandingPad's here is in fact okay, although it 238223b49ba6d55972fdffdfd4ed37edcf067bb60f3cBill Wendling // involves a bit of subtle reasoning. If this inst is a LandingPad, 238323b49ba6d55972fdffdfd4ed37edcf067bb60f3cBill Wendling // all the predecessors of this block will be the unwind edges of Invokes, 238423b49ba6d55972fdffdfd4ed37edcf067bb60f3cBill Wendling // and we can therefore guarantee this block will be erased. 23858176388d65083339efdfa5bee63e620c6bd05aa1Eli Friedman } 23868176388d65083339efdfa5bee63e620c6bd05aa1Eli Friedman 23872adc5b6a17268834b08fda444b1a84550e8c5ae8Eli Friedman // Delete this instruction (any uses are guaranteed to be dead) 23882adc5b6a17268834b08fda444b1a84550e8c5ae8Eli Friedman if (!BBI->use_empty()) 23892adc5b6a17268834b08fda444b1a84550e8c5ae8Eli Friedman BBI->replaceAllUsesWith(UndefValue::get(BBI->getType())); 2390302ba6fc1cb26248b0d6524fc42c740370926d6dChris Lattner BBI->eraseFromParent(); 23913d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner Changed = true; 23923d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } 23933d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 23943d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // If the unreachable instruction is the first in the block, take a gander 23953d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // at all of the predecessors of this instruction, and simplify them. 23963d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (&BB->front() != UI) return Changed; 23973d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 23983d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner SmallVector<BasicBlock*, 8> Preds(pred_begin(BB), pred_end(BB)); 23993d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner for (unsigned i = 0, e = Preds.size(); i != e; ++i) { 24003d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner TerminatorInst *TI = Preds[i]->getTerminator(); 24011aa89a2f91948993a5d535e3d59513af7f3e7dc9Devang Patel IRBuilder<> Builder(TI); 24023d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (BranchInst *BI = dyn_cast<BranchInst>(TI)) { 24033d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (BI->isUnconditional()) { 24043d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (BI->getSuccessor(0) == BB) { 24053d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner new UnreachableInst(TI->getContext(), TI); 24063d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner TI->eraseFromParent(); 24073d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner Changed = true; 24083d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } 24093d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } else { 24103d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (BI->getSuccessor(0) == BB) { 24111aa89a2f91948993a5d535e3d59513af7f3e7dc9Devang Patel Builder.CreateBr(BI->getSuccessor(1)); 24123d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner EraseTerminatorInstAndDCECond(BI); 24133d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } else if (BI->getSuccessor(1) == BB) { 24141aa89a2f91948993a5d535e3d59513af7f3e7dc9Devang Patel Builder.CreateBr(BI->getSuccessor(0)); 24153d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner EraseTerminatorInstAndDCECond(BI); 24163d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner Changed = true; 241707e6e56f57e8781a8d7bc601cc9034a3741d84c2Anton Korobeynikov } 241819831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner } 24193d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } else if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) { 24203d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner for (unsigned i = 1, e = SI->getNumCases(); i != e; ++i) 24213d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (SI->getSuccessor(i) == BB) { 24223d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BB->removePredecessor(SI->getParent()); 24233d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner SI->removeCase(i); 24243d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner --i; --e; 24253d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner Changed = true; 24263d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } 24273d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // If the default value is unreachable, figure out the most popular 24283d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // destination and make it the default. 24293d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (SI->getSuccessor(0) == BB) { 2430b1a6eab655adce4f84a15afa9092e814b9aaabdaEli Friedman std::map<BasicBlock*, std::pair<unsigned, unsigned> > Popularity; 2431b1a6eab655adce4f84a15afa9092e814b9aaabdaEli Friedman for (unsigned i = 1, e = SI->getNumCases(); i != e; ++i) { 24329d5231022283ff20b0291eb5711a449de262d3feNick Lewycky std::pair<unsigned, unsigned> &entry = 2433b1a6eab655adce4f84a15afa9092e814b9aaabdaEli Friedman Popularity[SI->getSuccessor(i)]; 2434b1a6eab655adce4f84a15afa9092e814b9aaabdaEli Friedman if (entry.first == 0) { 2435b1a6eab655adce4f84a15afa9092e814b9aaabdaEli Friedman entry.first = 1; 2436b1a6eab655adce4f84a15afa9092e814b9aaabdaEli Friedman entry.second = i; 2437b1a6eab655adce4f84a15afa9092e814b9aaabdaEli Friedman } else { 2438b1a6eab655adce4f84a15afa9092e814b9aaabdaEli Friedman entry.first++; 2439b1a6eab655adce4f84a15afa9092e814b9aaabdaEli Friedman } 2440b1a6eab655adce4f84a15afa9092e814b9aaabdaEli Friedman } 2441b1a6eab655adce4f84a15afa9092e814b9aaabdaEli Friedman 24423d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // Find the most popular block. 24433d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner unsigned MaxPop = 0; 2444b1a6eab655adce4f84a15afa9092e814b9aaabdaEli Friedman unsigned MaxIndex = 0; 24453d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BasicBlock *MaxBlock = 0; 2446b1a6eab655adce4f84a15afa9092e814b9aaabdaEli Friedman for (std::map<BasicBlock*, std::pair<unsigned, unsigned> >::iterator 24473d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner I = Popularity.begin(), E = Popularity.end(); I != E; ++I) { 2448b1a6eab655adce4f84a15afa9092e814b9aaabdaEli Friedman if (I->second.first > MaxPop || 2449b1a6eab655adce4f84a15afa9092e814b9aaabdaEli Friedman (I->second.first == MaxPop && MaxIndex > I->second.second)) { 2450b1a6eab655adce4f84a15afa9092e814b9aaabdaEli Friedman MaxPop = I->second.first; 2451b1a6eab655adce4f84a15afa9092e814b9aaabdaEli Friedman MaxIndex = I->second.second; 24523d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner MaxBlock = I->first; 24533d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } 24543d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } 24553d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (MaxBlock) { 24563d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // Make this the new default, allowing us to delete any explicit 24573d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // edges to it. 24583d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner SI->setSuccessor(0, MaxBlock); 24593d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner Changed = true; 2460ffba5821eee7b7a6139f9dfb06b8d306bf344a9dChris Lattner 24613d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // If MaxBlock has phinodes in it, remove MaxPop-1 entries from 24623d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // it. 24633d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (isa<PHINode>(MaxBlock->begin())) 24643d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner for (unsigned i = 0; i != MaxPop-1; ++i) 24653d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner MaxBlock->removePredecessor(SI->getParent()); 24663d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 24673d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner for (unsigned i = 1, e = SI->getNumCases(); i != e; ++i) 24683d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (SI->getSuccessor(i) == MaxBlock) { 24693d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner SI->removeCase(i); 24703d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner --i; --e; 24713d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } 247219831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner } 247319831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner } 24743d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } else if (InvokeInst *II = dyn_cast<InvokeInst>(TI)) { 24753d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (II->getUnwindDest() == BB) { 24763d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // Convert the invoke to a call instruction. This would be a good 24773d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // place to note that the call does not throw though. 24781aa89a2f91948993a5d535e3d59513af7f3e7dc9Devang Patel BranchInst *BI = Builder.CreateBr(II->getNormalDest()); 24793d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner II->removeFromParent(); // Take out of symbol table 24803d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 24813d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // Insert the call now... 24823d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner SmallVector<Value*, 8> Args(II->op_begin(), II->op_end()-3); 24831aa89a2f91948993a5d535e3d59513af7f3e7dc9Devang Patel Builder.SetInsertPoint(BI); 24841aa89a2f91948993a5d535e3d59513af7f3e7dc9Devang Patel CallInst *CI = Builder.CreateCall(II->getCalledValue(), 2485a3efbb15ddd5aa9006564cd79086723640084878Jay Foad Args, II->getName()); 24869a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner CI->setCallingConv(II->getCallingConv()); 24879a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner CI->setAttributes(II->getAttributes()); 24883d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // If the invoke produced a value, the call does now instead. 24899a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner II->replaceAllUsesWith(CI); 24909a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner delete II; 24919a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner Changed = true; 24929a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner } 2493e14ea0804afba2ac5824507571a220d05b0aa21dChris Lattner } 24943d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } 24953d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 24963d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // If this block is now dead, remove it. 24973d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (pred_begin(BB) == pred_end(BB) && 24983d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BB != &BB->getParent()->getEntryBlock()) { 24993d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // We know there are no successors, so just nuke the block. 25003d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BB->eraseFromParent(); 25013d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner return true; 25023d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } 25038e509dd5e81e92a466580ab4022994079952cca9Chris Lattner 25043d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner return Changed; 25053d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner} 25068e509dd5e81e92a466580ab4022994079952cca9Chris Lattner 250756442dfdcf7b07c04b585de5205b9427b1739895Benjamin Kramer/// TurnSwitchRangeIntoICmp - Turns a switch with that contains only a 250856442dfdcf7b07c04b585de5205b9427b1739895Benjamin Kramer/// integer range comparison into a sub, an icmp and a branch. 2509007349dafda47296177fd7481aff9764d4179f42Devang Patelstatic bool TurnSwitchRangeIntoICmp(SwitchInst *SI, IRBuilder<> &Builder) { 251056442dfdcf7b07c04b585de5205b9427b1739895Benjamin Kramer assert(SI->getNumCases() > 2 && "Degenerate switch?"); 2511042b27f40e4b1dcae70c0e98c3b4f5760dd8fa9bBenjamin Kramer 2512042b27f40e4b1dcae70c0e98c3b4f5760dd8fa9bBenjamin Kramer // Make sure all cases point to the same destination and gather the values. 2513042b27f40e4b1dcae70c0e98c3b4f5760dd8fa9bBenjamin Kramer SmallVector<ConstantInt *, 16> Cases; 2514042b27f40e4b1dcae70c0e98c3b4f5760dd8fa9bBenjamin Kramer Cases.push_back(SI->getCaseValue(1)); 2515042b27f40e4b1dcae70c0e98c3b4f5760dd8fa9bBenjamin Kramer for (unsigned I = 2, E = SI->getNumCases(); I != E; ++I) { 2516042b27f40e4b1dcae70c0e98c3b4f5760dd8fa9bBenjamin Kramer if (SI->getSuccessor(I-1) != SI->getSuccessor(I)) 251756442dfdcf7b07c04b585de5205b9427b1739895Benjamin Kramer return false; 2518042b27f40e4b1dcae70c0e98c3b4f5760dd8fa9bBenjamin Kramer Cases.push_back(SI->getCaseValue(I)); 2519042b27f40e4b1dcae70c0e98c3b4f5760dd8fa9bBenjamin Kramer } 2520042b27f40e4b1dcae70c0e98c3b4f5760dd8fa9bBenjamin Kramer assert(Cases.size() == SI->getNumCases()-1 && "Not all cases gathered"); 2521042b27f40e4b1dcae70c0e98c3b4f5760dd8fa9bBenjamin Kramer 2522042b27f40e4b1dcae70c0e98c3b4f5760dd8fa9bBenjamin Kramer // Sort the case values, then check if they form a range we can transform. 2523042b27f40e4b1dcae70c0e98c3b4f5760dd8fa9bBenjamin Kramer array_pod_sort(Cases.begin(), Cases.end(), ConstantIntSortPredicate); 2524042b27f40e4b1dcae70c0e98c3b4f5760dd8fa9bBenjamin Kramer for (unsigned I = 1, E = Cases.size(); I != E; ++I) { 2525042b27f40e4b1dcae70c0e98c3b4f5760dd8fa9bBenjamin Kramer if (Cases[I-1]->getValue() != Cases[I]->getValue()+1) 2526042b27f40e4b1dcae70c0e98c3b4f5760dd8fa9bBenjamin Kramer return false; 2527042b27f40e4b1dcae70c0e98c3b4f5760dd8fa9bBenjamin Kramer } 252856442dfdcf7b07c04b585de5205b9427b1739895Benjamin Kramer 2529042b27f40e4b1dcae70c0e98c3b4f5760dd8fa9bBenjamin Kramer Constant *Offset = ConstantExpr::getNeg(Cases.back()); 253056442dfdcf7b07c04b585de5205b9427b1739895Benjamin Kramer Constant *NumCases = ConstantInt::get(Offset->getType(), SI->getNumCases()-1); 253156442dfdcf7b07c04b585de5205b9427b1739895Benjamin Kramer 253233828bcb24176aae72afac0e4953e4b7f9560ef1Benjamin Kramer Value *Sub = SI->getCondition(); 253333828bcb24176aae72afac0e4953e4b7f9560ef1Benjamin Kramer if (!Offset->isNullValue()) 25341f5812bd995afc97d32061c532aaa0aedbead9ffDevang Patel Sub = Builder.CreateAdd(Sub, Offset, Sub->getName()+".off"); 25351f5812bd995afc97d32061c532aaa0aedbead9ffDevang Patel Value *Cmp = Builder.CreateICmpULT(Sub, NumCases, "switch"); 2536007349dafda47296177fd7481aff9764d4179f42Devang Patel Builder.CreateCondBr(Cmp, SI->getSuccessor(1), SI->getDefaultDest()); 253756442dfdcf7b07c04b585de5205b9427b1739895Benjamin Kramer 253856442dfdcf7b07c04b585de5205b9427b1739895Benjamin Kramer // Prune obsolete incoming values off the successor's PHI nodes. 253956442dfdcf7b07c04b585de5205b9427b1739895Benjamin Kramer for (BasicBlock::iterator BBI = SI->getSuccessor(1)->begin(); 254056442dfdcf7b07c04b585de5205b9427b1739895Benjamin Kramer isa<PHINode>(BBI); ++BBI) { 254156442dfdcf7b07c04b585de5205b9427b1739895Benjamin Kramer for (unsigned I = 0, E = SI->getNumCases()-2; I != E; ++I) 254256442dfdcf7b07c04b585de5205b9427b1739895Benjamin Kramer cast<PHINode>(BBI)->removeIncomingValue(SI->getParent()); 254356442dfdcf7b07c04b585de5205b9427b1739895Benjamin Kramer } 254456442dfdcf7b07c04b585de5205b9427b1739895Benjamin Kramer SI->eraseFromParent(); 254556442dfdcf7b07c04b585de5205b9427b1739895Benjamin Kramer 254656442dfdcf7b07c04b585de5205b9427b1739895Benjamin Kramer return true; 254756442dfdcf7b07c04b585de5205b9427b1739895Benjamin Kramer} 2548d0a203d76f4ef77ae1c392e8e73e2f05b676a5f2Devang Patel 254910fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer/// EliminateDeadSwitchCases - Compute masked bits for the condition of a switch 255010fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer/// and use it to remove dead cases. 255110fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramerstatic bool EliminateDeadSwitchCases(SwitchInst *SI) { 255210fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer Value *Cond = SI->getCondition(); 255310fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer unsigned Bits = cast<IntegerType>(Cond->getType())->getBitWidth(); 255410fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer APInt KnownZero(Bits, 0), KnownOne(Bits, 0); 255510fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer ComputeMaskedBits(Cond, APInt::getAllOnesValue(Bits), KnownZero, KnownOne); 255610fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer 255710fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer // Gather dead cases. 255810fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer SmallVector<ConstantInt*, 8> DeadCases; 255910fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer for (unsigned I = 1, E = SI->getNumCases(); I != E; ++I) { 256010fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer if ((SI->getCaseValue(I)->getValue() & KnownZero) != 0 || 256110fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer (SI->getCaseValue(I)->getValue() & KnownOne) != KnownOne) { 256210fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer DeadCases.push_back(SI->getCaseValue(I)); 256310fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer DEBUG(dbgs() << "SimplifyCFG: switch case '" 256410fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer << SI->getCaseValue(I)->getValue() << "' is dead.\n"); 256510fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer } 256610fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer } 256710fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer 256810fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer // Remove dead cases from the switch. 256910fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer for (unsigned I = 0, E = DeadCases.size(); I != E; ++I) { 257010fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer unsigned Case = SI->findCaseValue(DeadCases[I]); 257110fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer // Prune unused values from PHI nodes. 257210fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer SI->getSuccessor(Case)->removePredecessor(SI->getParent()); 257310fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer SI->removeCase(Case); 257410fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer } 257510fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer 257610fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer return !DeadCases.empty(); 257710fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer} 257810fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer 2579448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg/// FindPHIForConditionForwarding - If BB would be eligible for simplification 2580448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg/// by TryToSimplifyUncondBranchFromEmptyBlock (i.e. it is empty and terminated 2581448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg/// by an unconditional branch), look at the phi node for BB in the successor 2582448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg/// block and see if the incoming value is equal to CaseValue. If so, return 2583448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg/// the phi node, and set PhiIndex to BB's index in the phi node. 2584448da519cca87cbcba620188e1e595dc1f120512Hans Wennborgstatic PHINode *FindPHIForConditionForwarding(ConstantInt *CaseValue, 2585448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg BasicBlock *BB, 2586448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg int *PhiIndex) { 2587448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg if (BB->getFirstNonPHIOrDbg() != BB->getTerminator()) 2588448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg return NULL; // BB must be empty to be a candidate for simplification. 2589448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg if (!BB->getSinglePredecessor()) 2590448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg return NULL; // BB must be dominated by the switch. 2591448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg 2592448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg BranchInst *Branch = dyn_cast<BranchInst>(BB->getTerminator()); 2593448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg if (!Branch || !Branch->isUnconditional()) 2594448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg return NULL; // Terminator must be unconditional branch. 2595448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg 2596448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg BasicBlock *Succ = Branch->getSuccessor(0); 2597448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg 2598448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg BasicBlock::iterator I = Succ->begin(); 2599448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg while (PHINode *PHI = dyn_cast<PHINode>(I++)) { 2600448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg int Idx = PHI->getBasicBlockIndex(BB); 2601448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg assert(Idx >= 0 && "PHI has no entry for predecessor?"); 2602448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg 2603448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg Value *InValue = PHI->getIncomingValue(Idx); 2604448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg if (InValue != CaseValue) continue; 2605448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg 2606448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg *PhiIndex = Idx; 2607448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg return PHI; 2608448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg } 2609448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg 2610448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg return NULL; 2611448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg} 2612448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg 2613448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg/// ForwardSwitchConditionToPHI - Try to forward the condition of a switch 2614448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg/// instruction to a phi node dominated by the switch, if that would mean that 2615448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg/// some of the destination blocks of the switch can be folded away. 2616448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg/// Returns true if a change is made. 2617448da519cca87cbcba620188e1e595dc1f120512Hans Wennborgstatic bool ForwardSwitchConditionToPHI(SwitchInst *SI) { 2618448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg typedef DenseMap<PHINode*, SmallVector<int,4> > ForwardingNodesMap; 2619448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg ForwardingNodesMap ForwardingNodes; 2620448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg 2621448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg for (unsigned I = 1; I < SI->getNumCases(); ++I) { // 0 is the default case. 2622448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg ConstantInt *CaseValue = SI->getCaseValue(I); 2623448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg BasicBlock *CaseDest = SI->getSuccessor(I); 2624448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg 2625448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg int PhiIndex; 2626448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg PHINode *PHI = FindPHIForConditionForwarding(CaseValue, CaseDest, 2627448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg &PhiIndex); 2628448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg if (!PHI) continue; 2629448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg 2630448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg ForwardingNodes[PHI].push_back(PhiIndex); 2631448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg } 2632448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg 2633448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg bool Changed = false; 2634448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg 2635448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg for (ForwardingNodesMap::iterator I = ForwardingNodes.begin(), 2636448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg E = ForwardingNodes.end(); I != E; ++I) { 2637448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg PHINode *Phi = I->first; 2638448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg SmallVector<int,4> &Indexes = I->second; 2639448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg 2640448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg if (Indexes.size() < 2) continue; 2641448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg 2642448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg for (size_t I = 0, E = Indexes.size(); I != E; ++I) 2643448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg Phi->setIncomingValue(Indexes[I], SI->getCondition()); 2644448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg Changed = true; 2645448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg } 2646448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg 2647448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg return Changed; 2648448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg} 2649448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg 2650007349dafda47296177fd7481aff9764d4179f42Devang Patelbool SimplifyCFGOpt::SimplifySwitch(SwitchInst *SI, IRBuilder<> &Builder) { 26513d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // If this switch is too complex to want to look at, ignore it. 26523d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (!isValueEqualityComparison(SI)) 26533d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner return false; 2654e67fa05036f634a4ec1e0893033c89250eb58954Chris Lattner 26553d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BasicBlock *BB = SI->getParent(); 26563d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 26573d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // If we only have one predecessor, and if it is a branch on this value, 26583d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // see if that predecessor totally determines the outcome of this switch. 26593d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (BasicBlock *OnlyPred = BB->getSinglePredecessor()) 2660007349dafda47296177fd7481aff9764d4179f42Devang Patel if (SimplifyEqualityComparisonWithOnlyPredecessor(SI, OnlyPred, Builder)) 2661021c9d3bd41bc446ef0860c05a073e32afa5e20fChris Lattner return SimplifyCFG(BB) | true; 2662f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel 2663f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel Value *Cond = SI->getCondition(); 2664f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel if (SelectInst *Select = dyn_cast<SelectInst>(Cond)) 2665f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel if (SimplifySwitchOnSelect(SI, Select)) 2666f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel return SimplifyCFG(BB) | true; 2667f7b2a9d7df0020d5120fbeb3232f9dce57dec6e7Frits van Bommel 26683d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // If the block only contains the switch, see if we can fold the block 26693d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // away into any preds. 26703d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BasicBlock::iterator BBI = BB->begin(); 26713d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // Ignore dbg intrinsics. 26723d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner while (isa<DbgInfoIntrinsic>(BBI)) 26733d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner ++BBI; 26743d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (SI == &*BBI) 2675b55d924b1e33341d08b1bead78e86fce56617784Devang Patel if (FoldValueComparisonIntoPredecessors(SI, Builder)) 2676021c9d3bd41bc446ef0860c05a073e32afa5e20fChris Lattner return SimplifyCFG(BB) | true; 267756442dfdcf7b07c04b585de5205b9427b1739895Benjamin Kramer 267856442dfdcf7b07c04b585de5205b9427b1739895Benjamin Kramer // Try to transform the switch into an icmp and a branch. 2679007349dafda47296177fd7481aff9764d4179f42Devang Patel if (TurnSwitchRangeIntoICmp(SI, Builder)) 268056442dfdcf7b07c04b585de5205b9427b1739895Benjamin Kramer return SimplifyCFG(BB) | true; 268110fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer 268210fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer // Remove unreachable cases. 268310fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer if (EliminateDeadSwitchCases(SI)) 268410fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer return SimplifyCFG(BB) | true; 268510fcfb53fdc77061841e815e8b4cd62b48d5767dBenjamin Kramer 2686448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg if (ForwardSwitchConditionToPHI(SI)) 2687448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg return SimplifyCFG(BB) | true; 2688448da519cca87cbcba620188e1e595dc1f120512Hans Wennborg 26893d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner return false; 26903d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner} 26913d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 26923d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattnerbool SimplifyCFGOpt::SimplifyIndirectBr(IndirectBrInst *IBI) { 26933d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BasicBlock *BB = IBI->getParent(); 26943d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner bool Changed = false; 26953d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 26963d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // Eliminate redundant destinations. 26973d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner SmallPtrSet<Value *, 8> Succs; 26983d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner for (unsigned i = 0, e = IBI->getNumDestinations(); i != e; ++i) { 26993d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BasicBlock *Dest = IBI->getDestination(i); 27003d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (!Dest->hasAddressTaken() || !Succs.insert(Dest)) { 27013d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner Dest->removePredecessor(BB); 27023d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner IBI->removeDestination(i); 27033d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner --i; --e; 2704698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner Changed = true; 2705698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner } 27063d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } 2707698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner 27083d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (IBI->getNumDestinations() == 0) { 27093d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // If the indirectbr has no successors, change it to unreachable. 27103d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner new UnreachableInst(IBI->getContext(), IBI); 27113d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner EraseTerminatorInstAndDCECond(IBI); 27123d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner return true; 27133d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } 27143d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 27153d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (IBI->getNumDestinations() == 1) { 27163d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // If the indirectbr has one successor, change it to a direct branch. 27173d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BranchInst::Create(IBI->getDestination(0), IBI); 27183d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner EraseTerminatorInstAndDCECond(IBI); 27193d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner return true; 27203d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } 27213d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 27223d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (SelectInst *SI = dyn_cast<SelectInst>(IBI->getAddress())) { 27233d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (SimplifyIndirectBrOnSelect(IBI, SI)) 27243d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner return SimplifyCFG(BB) | true; 27253d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } 27263d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner return Changed; 27273d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner} 2728698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner 2729a23812cfbd23604d2fc103cf232cde8fa270a491Devang Patelbool SimplifyCFGOpt::SimplifyUncondBranch(BranchInst *BI, IRBuilder<> &Builder){ 27303d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BasicBlock *BB = BI->getParent(); 27313d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 27323d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // If the Terminator is the only non-phi instruction, simplify the block. 273377a2c372face15a302f4c9e5cb9acc035b8b3bd3Rafael Espindola BasicBlock::iterator I = BB->getFirstNonPHIOrDbgOrLifetime(); 27343d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (I->isTerminator() && BB != &BB->getParent()->getEntryBlock() && 27353d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner TryToSimplifyUncondBranchFromEmptyBlock(BB)) 27363d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner return true; 27373d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 27383d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // If the only instruction in the block is a seteq/setne comparison 27393d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // against a constant, try to simplify the block. 27403d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (ICmpInst *ICI = dyn_cast<ICmpInst>(I)) 27413d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (ICI->isEquality() && isa<ConstantInt>(ICI->getOperand(1))) { 27423d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner for (++I; isa<DbgInfoIntrinsic>(I); ++I) 27433d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner ; 27449d5231022283ff20b0291eb5711a449de262d3feNick Lewycky if (I->isTerminator() && 27459d5231022283ff20b0291eb5711a449de262d3feNick Lewycky TryToSimplifyUncondBranchWithICmpInIt(ICI, TD, Builder)) 2746698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner return true; 2747698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner } 27483d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 27493d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner return false; 27503d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner} 2751e2c6d131d12c779a410740e0a90545def75e0f48Dan Gohman 27523d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 2753007349dafda47296177fd7481aff9764d4179f42Devang Patelbool SimplifyCFGOpt::SimplifyCondBranch(BranchInst *BI, IRBuilder<> &Builder) { 27543d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BasicBlock *BB = BI->getParent(); 27553d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 27563d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // Conditional branch 27573d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (isValueEqualityComparison(BI)) { 27583d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // If we only have one predecessor, and if it is a branch on this value, 27593d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // see if that predecessor totally determines the outcome of this 27603d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // switch. 27613d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (BasicBlock *OnlyPred = BB->getSinglePredecessor()) 2762007349dafda47296177fd7481aff9764d4179f42Devang Patel if (SimplifyEqualityComparisonWithOnlyPredecessor(BI, OnlyPred, Builder)) 27633d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner return SimplifyCFG(BB) | true; 27643d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 27653d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // This block must be empty, except for the setcond inst, if it exists. 27663d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // Ignore dbg intrinsics. 27673d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BasicBlock::iterator I = BB->begin(); 27683d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // Ignore dbg intrinsics. 27693d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner while (isa<DbgInfoIntrinsic>(I)) 27703d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner ++I; 27713d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (&*I == BI) { 2772b55d924b1e33341d08b1bead78e86fce56617784Devang Patel if (FoldValueComparisonIntoPredecessors(BI, Builder)) 27733d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner return SimplifyCFG(BB) | true; 27743d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } else if (&*I == cast<Instruction>(BI->getCondition())){ 27753d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner ++I; 27763d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // Ignore dbg intrinsics. 27773d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner while (isa<DbgInfoIntrinsic>(I)) 27783d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner ++I; 2779b55d924b1e33341d08b1bead78e86fce56617784Devang Patel if (&*I == BI && FoldValueComparisonIntoPredecessors(BI, Builder)) 27803d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner return SimplifyCFG(BB) | true; 27813d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } 27823d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } 27833d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 27843d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // Try to turn "br (X == 0 | X == 1), T, F" into a switch instruction. 278502dd5418d29c2a43f225df887923e144e12e7ec6Devang Patel if (SimplifyBranchOnICmpChain(BI, TD, Builder)) 27863d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner return true; 27873d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 27883d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // We have a conditional branch to two blocks that are only reachable 27893d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // from BI. We know that the condbr dominates the two blocks, so see if 27903d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // there is any identical code in the "then" and "else" blocks. If so, we 27913d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // can hoist it up to the branching block. 27923d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (BI->getSuccessor(0)->getSinglePredecessor() != 0) { 27933d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (BI->getSuccessor(1)->getSinglePredecessor() != 0) { 2794216dde91d1def3e08002d6251e11f3dfa5cb3656Rafael Espindola if (HoistThenElseCodeToIf(BI)) 27957ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel return SimplifyCFG(BB) | true; 27963d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } else { 27973d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // If Successor #1 has multiple preds, we may be able to conditionally 27983d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // execute Successor #0 if it branches to successor #1. 27993d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner TerminatorInst *Succ0TI = BI->getSuccessor(0)->getTerminator(); 28003d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (Succ0TI->getNumSuccessors() == 1 && 28013d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner Succ0TI->getSuccessor(0) == BI->getSuccessor(1)) 2802216dde91d1def3e08002d6251e11f3dfa5cb3656Rafael Espindola if (SpeculativelyExecuteBB(BI, BI->getSuccessor(0))) 28033d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner return SimplifyCFG(BB) | true; 2804e2c6d131d12c779a410740e0a90545def75e0f48Dan Gohman } 28053d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } else if (BI->getSuccessor(1)->getSinglePredecessor() != 0) { 28063d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // If Successor #0 has multiple preds, we may be able to conditionally 28073d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // execute Successor #1 if it branches to successor #0. 28083d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner TerminatorInst *Succ1TI = BI->getSuccessor(1)->getTerminator(); 28093d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (Succ1TI->getNumSuccessors() == 1 && 28103d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner Succ1TI->getSuccessor(0) == BI->getSuccessor(0)) 2811216dde91d1def3e08002d6251e11f3dfa5cb3656Rafael Espindola if (SpeculativelyExecuteBB(BI, BI->getSuccessor(1))) 28123d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner return SimplifyCFG(BB) | true; 281319831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner } 28143d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 28153d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // If this is a branch on a phi node in the current block, thread control 28163d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // through this block if any PHI node entries are constants. 28173d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (PHINode *PN = dyn_cast<PHINode>(BI->getCondition())) 28183d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (PN->getParent() == BI->getParent()) 2819302ba6fc1cb26248b0d6524fc42c740370926d6dChris Lattner if (FoldCondBranchOnPHI(BI, TD)) 28203d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner return SimplifyCFG(BB) | true; 28213d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 28229d5231022283ff20b0291eb5711a449de262d3feNick Lewycky // If this basic block is ONLY a compare and a branch, and if a predecessor 28239d5231022283ff20b0291eb5711a449de262d3feNick Lewycky // branches to us and one of our successors, fold the comparison into the 28243d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // predecessor and use logical operations to pick the right destination. 28253d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (FoldBranchToCommonDest(BI)) 28262d9220e8f5b45390d64e943fa4eef1562b87f04bOwen Anderson return SimplifyCFG(BB) | true; 28273d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 28283d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // Scan predecessor blocks for conditional branches. 28293d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI) 28303d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (BranchInst *PBI = dyn_cast<BranchInst>((*PI)->getTerminator())) 28313d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (PBI != BI && PBI->isConditional()) 28323d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (SimplifyCondBranchToCondBranch(PBI, BI)) 28333d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner return SimplifyCFG(BB) | true; 28343d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 28353d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner return false; 28363d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner} 28373d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 283898d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer/// Check if passing a value to an instruction will cause undefined behavior. 283998d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramerstatic bool passingValueIsAlwaysUndefined(Value *V, Instruction *I) { 284098d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer Constant *C = dyn_cast<Constant>(V); 284198d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer if (!C) 284298d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer return false; 284398d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer 28449bb5488dbd152de41ffcaedccf94bfc43b069becBenjamin Kramer if (!I->hasOneUse()) // Only look at single-use instructions, for compile time 284598d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer return false; 284698d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer 284798d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer if (C->isNullValue()) { 284898d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer Instruction *Use = I->use_back(); 284998d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer 285098d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer // Now make sure that there are no instructions in between that can alter 285198d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer // control flow (eg. calls) 285298d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer for (BasicBlock::iterator i = ++BasicBlock::iterator(I); &*i != Use; ++i) 28539bb5488dbd152de41ffcaedccf94bfc43b069becBenjamin Kramer if (i == I->getParent()->end() || i->mayHaveSideEffects()) 285498d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer return false; 285598d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer 285698d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer // Look through GEPs. A load from a GEP derived from NULL is still undefined 285798d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Use)) 285898d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer if (GEP->getPointerOperand() == I) 285998d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer return passingValueIsAlwaysUndefined(V, GEP); 286098d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer 286198d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer // Look through bitcasts. 286298d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer if (BitCastInst *BC = dyn_cast<BitCastInst>(Use)) 286398d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer return passingValueIsAlwaysUndefined(V, BC); 286498d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer 28659bb5488dbd152de41ffcaedccf94bfc43b069becBenjamin Kramer // Load from null is undefined. 28669bb5488dbd152de41ffcaedccf94bfc43b069becBenjamin Kramer if (LoadInst *LI = dyn_cast<LoadInst>(Use)) 28679bb5488dbd152de41ffcaedccf94bfc43b069becBenjamin Kramer return LI->getPointerAddressSpace() == 0; 286898d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer 28699bb5488dbd152de41ffcaedccf94bfc43b069becBenjamin Kramer // Store to null is undefined. 28709bb5488dbd152de41ffcaedccf94bfc43b069becBenjamin Kramer if (StoreInst *SI = dyn_cast<StoreInst>(Use)) 28719bb5488dbd152de41ffcaedccf94bfc43b069becBenjamin Kramer return SI->getPointerAddressSpace() == 0 && SI->getPointerOperand() == I; 287298d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer } 287398d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer return false; 287498d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer} 287598d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer 287698d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer/// If BB has an incoming value that will always trigger undefined behavior 28779d5231022283ff20b0291eb5711a449de262d3feNick Lewycky/// (eg. null pointer dereference), remove the branch leading here. 287898d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramerstatic bool removeUndefIntroducingPredecessor(BasicBlock *BB) { 287998d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer for (BasicBlock::iterator i = BB->begin(); 288098d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer PHINode *PHI = dyn_cast<PHINode>(i); ++i) 288198d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer for (unsigned i = 0, e = PHI->getNumIncomingValues(); i != e; ++i) 288298d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer if (passingValueIsAlwaysUndefined(PHI->getIncomingValue(i), PHI)) { 288398d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer TerminatorInst *T = PHI->getIncomingBlock(i)->getTerminator(); 288498d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer IRBuilder<> Builder(T); 288598d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer if (BranchInst *BI = dyn_cast<BranchInst>(T)) { 288698d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer BB->removePredecessor(PHI->getIncomingBlock(i)); 288798d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer // Turn uncoditional branches into unreachables and remove the dead 288898d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer // destination from conditional branches. 288998d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer if (BI->isUnconditional()) 289098d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer Builder.CreateUnreachable(); 289198d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer else 289298d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer Builder.CreateBr(BI->getSuccessor(0) == BB ? BI->getSuccessor(1) : 289398d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer BI->getSuccessor(0)); 289498d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer BI->eraseFromParent(); 289598d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer return true; 289698d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer } 289798d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer // TODO: SwitchInst. 289898d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer } 289998d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer 290098d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer return false; 290198d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer} 290298d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer 29033d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattnerbool SimplifyCFGOpt::run(BasicBlock *BB) { 29043d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner bool Changed = false; 29053d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 2906302ba6fc1cb26248b0d6524fc42c740370926d6dChris Lattner assert(BB && BB->getParent() && "Block not embedded in function!"); 29073d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner assert(BB->getTerminator() && "Degenerate basic block encountered!"); 29083d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 29093d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // Remove basic blocks that have no predecessors (except the entry block)... 29103d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // or that just have themself as a predecessor. These are unreachable. 2911302ba6fc1cb26248b0d6524fc42c740370926d6dChris Lattner if ((pred_begin(BB) == pred_end(BB) && 2912302ba6fc1cb26248b0d6524fc42c740370926d6dChris Lattner BB != &BB->getParent()->getEntryBlock()) || 29133d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner BB->getSinglePredecessor() == BB) { 29143d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner DEBUG(dbgs() << "Removing BB: \n" << *BB); 29153d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner DeleteDeadBlock(BB); 29163d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner return true; 29173d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } 29183d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 29193d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // Check to see if we can constant propagate this terminator instruction 29203d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // away... 29215649ba70fb39f2fda4791d255ae8bb373071874fFrits van Bommel Changed |= ConstantFoldTerminator(BB, true); 29223d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 29233d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // Check for and eliminate duplicate PHI nodes in this block. 29243d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner Changed |= EliminateDuplicatePHINodes(BB); 29253d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 292698d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer // Check for and remove branches that will always cause undefined behavior. 292798d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer Changed |= removeUndefIntroducingPredecessor(BB); 292898d6d2372feb2f8bb4c3941b278027499cbfc00bBenjamin Kramer 29293d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // Merge basic blocks into their predecessor if there is only one distinct 29303d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // pred, and if there is only one distinct successor of the predecessor, and 29313d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // if there are no PHI nodes. 29323d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // 29333d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (MergeBlockIntoPredecessor(BB)) 29343d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner return true; 29353d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 29363e410c6607192bbf28ba3708245cb70a0f983556Devang Patel IRBuilder<> Builder(BB); 29373e410c6607192bbf28ba3708245cb70a0f983556Devang Patel 29383d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // If there is a trivial two-entry PHI node in this basic block, and we can 29393d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner // eliminate it, do so now. 29403d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (PHINode *PN = dyn_cast<PHINode>(BB->begin())) 29413d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (PN->getNumIncomingValues() == 2) 2942d3a1788da15311781f661c1cbfe48cd5f98ae778Devang Patel Changed |= FoldTwoEntryPHINode(PN, TD); 29433d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 2944007349dafda47296177fd7481aff9764d4179f42Devang Patel Builder.SetInsertPoint(BB->getTerminator()); 29453d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner if (BranchInst *BI = dyn_cast<BranchInst>(BB->getTerminator())) { 2946021c9d3bd41bc446ef0860c05a073e32afa5e20fChris Lattner if (BI->isUnconditional()) { 2947a23812cfbd23604d2fc103cf232cde8fa270a491Devang Patel if (SimplifyUncondBranch(BI, Builder)) return true; 2948021c9d3bd41bc446ef0860c05a073e32afa5e20fChris Lattner } else { 2949007349dafda47296177fd7481aff9764d4179f42Devang Patel if (SimplifyCondBranch(BI, Builder)) return true; 2950021c9d3bd41bc446ef0860c05a073e32afa5e20fChris Lattner } 2951ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands } else if (ResumeInst *RI = dyn_cast<ResumeInst>(BB->getTerminator())) { 2952ad99ef8bf59adf151ac217e3b2ae6abec41f76e6Duncan Sands if (SimplifyResume(RI, Builder)) return true; 2953021c9d3bd41bc446ef0860c05a073e32afa5e20fChris Lattner } else if (ReturnInst *RI = dyn_cast<ReturnInst>(BB->getTerminator())) { 2954176ec40cb18c51c14fccbb38ee0db5deafb6baa9Devang Patel if (SimplifyReturn(RI, Builder)) return true; 2955021c9d3bd41bc446ef0860c05a073e32afa5e20fChris Lattner } else if (SwitchInst *SI = dyn_cast<SwitchInst>(BB->getTerminator())) { 2956007349dafda47296177fd7481aff9764d4179f42Devang Patel if (SimplifySwitch(SI, Builder)) return true; 2957021c9d3bd41bc446ef0860c05a073e32afa5e20fChris Lattner } else if (UnreachableInst *UI = 2958021c9d3bd41bc446ef0860c05a073e32afa5e20fChris Lattner dyn_cast<UnreachableInst>(BB->getTerminator())) { 2959021c9d3bd41bc446ef0860c05a073e32afa5e20fChris Lattner if (SimplifyUnreachable(UI)) return true; 2960021c9d3bd41bc446ef0860c05a073e32afa5e20fChris Lattner } else if (UnwindInst *UI = dyn_cast<UnwindInst>(BB->getTerminator())) { 2961d46ba26a6b513086ad575e5db0069b03d41fca13Devang Patel if (SimplifyUnwind(UI, Builder)) return true; 2962021c9d3bd41bc446ef0860c05a073e32afa5e20fChris Lattner } else if (IndirectBrInst *IBI = 2963021c9d3bd41bc446ef0860c05a073e32afa5e20fChris Lattner dyn_cast<IndirectBrInst>(BB->getTerminator())) { 2964021c9d3bd41bc446ef0860c05a073e32afa5e20fChris Lattner if (SimplifyIndirectBr(IBI)) return true; 29653d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner } 29663d5121314ab4af435e1abf5bc09b45c305f2f4b0Chris Lattner 2967694e37f08a7c09ccc24642532106295cf7b3a1e3Chris Lattner return Changed; 296801d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner} 296958e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen 297058e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen/// SimplifyCFG - This function is used to do simplification of a CFG. For 297158e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen/// example, it adjusts branches to branches to eliminate the extra hop, it 297258e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen/// eliminates unreachable basic blocks, and does other "peephole" optimization 297358e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen/// of the CFG. It returns true if a modification was made. 297458e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen/// 297558e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesenbool llvm::SimplifyCFG(BasicBlock *BB, const TargetData *TD) { 297658e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen return SimplifyCFGOpt(TD).run(BB); 297758e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen} 2978