SimplifyCFG.cpp revision abf706703fcbcde8fdc69b1bbdfb34e874813107
101d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner//===- SimplifyCFG.cpp - Code to perform CFG simplification ---------------===// 2fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukman// 3b576c94c15af9a440f69d9d03c2afead7971118cJohn Criswell// The LLVM Compiler Infrastructure 4b576c94c15af9a440f69d9d03c2afead7971118cJohn Criswell// 54ee451de366474b9c228b4e5fa573795a715216dChris Lattner// This file is distributed under the University of Illinois Open Source 64ee451de366474b9c228b4e5fa573795a715216dChris Lattner// License. See LICENSE.TXT for details. 7fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukman// 8b576c94c15af9a440f69d9d03c2afead7971118cJohn Criswell//===----------------------------------------------------------------------===// 901d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner// 10bb190ac8dafdcc5e604da3695987d69ee8632195Chris Lattner// Peephole optimize the CFG. 1101d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner// 1201d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner//===----------------------------------------------------------------------===// 1301d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner 14218a8223e62c41ae6318e28e8f4c672fcfbb5082Chris Lattner#define DEBUG_TYPE "simplifycfg" 1501d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner#include "llvm/Transforms/Utils/Local.h" 16723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner#include "llvm/Constants.h" 17723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner#include "llvm/Instructions.h" 18383d7ed9158576aef5cde872548225a17e3c0155Devang Patel#include "llvm/IntrinsicInst.h" 190d56008f53587531718ec36af82cc24576580b36Chris Lattner#include "llvm/Type.h" 20c10305743c313558405079452138f03124e87581Reid Spencer#include "llvm/DerivedTypes.h" 21f8bc3008214c8327ff987573a111fc0dcefb7d25Dale Johannesen#include "llvm/GlobalVariable.h" 2201d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner#include "llvm/Support/CFG.h" 23551ccae044b0ff658fe629dd67edd5ffe75d10e8Reid Spencer#include "llvm/Support/Debug.h" 24ce63ffb52f249b62cdf2d250c128007b13f27e71Daniel Dunbar#include "llvm/Support/raw_ostream.h" 2579066fa6acce02c97c714a5a6e151ed8a249721cChris Lattner#include "llvm/Analysis/ConstantFolding.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" 3301d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner#include <algorithm> 34d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner#include <set> 35698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner#include <map> 36f7703df4968084c18c248c1feea9961c19a32e6aChris Lattnerusing namespace llvm; 37d0fde30ce850b78371fd1386338350591f9ff494Brian Gaeke 38502a4f5162498ec420e3cb22f667808d726dd7daEvan ChengSTATISTIC(NumSpeculations, "Number of speculative executed instructions"); 39502a4f5162498ec420e3cb22f667808d726dd7daEvan Cheng 4058e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesennamespace { 4158e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesenclass SimplifyCFGOpt { 4258e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen const TargetData *const TD; 4358e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen 4458e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen Value *isValueEqualityComparison(TerminatorInst *TI); 4558e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen BasicBlock *GetValueEqualityComparisonCases(TerminatorInst *TI, 4658e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen std::vector<std::pair<ConstantInt*, BasicBlock*> > &Cases); 4758e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen bool SimplifyEqualityComparisonWithOnlyPredecessor(TerminatorInst *TI, 4858e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen BasicBlock *Pred); 4958e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen bool FoldValueComparisonIntoPredecessors(TerminatorInst *TI); 5058e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen 5158e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesenpublic: 5258e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen explicit SimplifyCFGOpt(const TargetData *td) : TD(td) {} 5358e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen bool run(BasicBlock *BB); 5458e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen}; 5558e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen} 5658e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen 572bdcb56146279009f233933a101cb3dd54a951cdChris Lattner/// SafeToMergeTerminators - Return true if it is safe to merge these two 582bdcb56146279009f233933a101cb3dd54a951cdChris Lattner/// terminator instructions together. 592bdcb56146279009f233933a101cb3dd54a951cdChris Lattner/// 602bdcb56146279009f233933a101cb3dd54a951cdChris Lattnerstatic bool SafeToMergeTerminators(TerminatorInst *SI1, TerminatorInst *SI2) { 612bdcb56146279009f233933a101cb3dd54a951cdChris Lattner if (SI1 == SI2) return false; // Can't merge with self! 622bdcb56146279009f233933a101cb3dd54a951cdChris Lattner 632bdcb56146279009f233933a101cb3dd54a951cdChris Lattner // It is not safe to merge these two switch instructions if they have a common 642bdcb56146279009f233933a101cb3dd54a951cdChris Lattner // successor, and if that successor has a PHI node, and if *that* PHI node has 652bdcb56146279009f233933a101cb3dd54a951cdChris Lattner // conflicting incoming values from the two switch blocks. 662bdcb56146279009f233933a101cb3dd54a951cdChris Lattner BasicBlock *SI1BB = SI1->getParent(); 672bdcb56146279009f233933a101cb3dd54a951cdChris Lattner BasicBlock *SI2BB = SI2->getParent(); 68c9951231822215d6aea7a9b50947c18d8d745609Chris Lattner SmallPtrSet<BasicBlock*, 16> SI1Succs(succ_begin(SI1BB), succ_end(SI1BB)); 692bdcb56146279009f233933a101cb3dd54a951cdChris Lattner 702bdcb56146279009f233933a101cb3dd54a951cdChris Lattner for (succ_iterator I = succ_begin(SI2BB), E = succ_end(SI2BB); I != E; ++I) 712bdcb56146279009f233933a101cb3dd54a951cdChris Lattner if (SI1Succs.count(*I)) 722bdcb56146279009f233933a101cb3dd54a951cdChris Lattner for (BasicBlock::iterator BBI = (*I)->begin(); 732bdcb56146279009f233933a101cb3dd54a951cdChris Lattner isa<PHINode>(BBI); ++BBI) { 742bdcb56146279009f233933a101cb3dd54a951cdChris Lattner PHINode *PN = cast<PHINode>(BBI); 752bdcb56146279009f233933a101cb3dd54a951cdChris Lattner if (PN->getIncomingValueForBlock(SI1BB) != 762bdcb56146279009f233933a101cb3dd54a951cdChris Lattner PN->getIncomingValueForBlock(SI2BB)) 772bdcb56146279009f233933a101cb3dd54a951cdChris Lattner return false; 782bdcb56146279009f233933a101cb3dd54a951cdChris Lattner } 792bdcb56146279009f233933a101cb3dd54a951cdChris Lattner 802bdcb56146279009f233933a101cb3dd54a951cdChris Lattner return true; 812bdcb56146279009f233933a101cb3dd54a951cdChris Lattner} 822bdcb56146279009f233933a101cb3dd54a951cdChris Lattner 832bdcb56146279009f233933a101cb3dd54a951cdChris Lattner/// AddPredecessorToBlock - Update PHI nodes in Succ to indicate that there will 842bdcb56146279009f233933a101cb3dd54a951cdChris Lattner/// now be entries in it from the 'NewPred' block. The values that will be 852bdcb56146279009f233933a101cb3dd54a951cdChris Lattner/// flowing into the PHI nodes will be the same as those coming in from 862bdcb56146279009f233933a101cb3dd54a951cdChris Lattner/// ExistPred, an existing predecessor of Succ. 872bdcb56146279009f233933a101cb3dd54a951cdChris Lattnerstatic void AddPredecessorToBlock(BasicBlock *Succ, BasicBlock *NewPred, 882bdcb56146279009f233933a101cb3dd54a951cdChris Lattner BasicBlock *ExistPred) { 892bdcb56146279009f233933a101cb3dd54a951cdChris Lattner assert(std::find(succ_begin(ExistPred), succ_end(ExistPred), Succ) != 902bdcb56146279009f233933a101cb3dd54a951cdChris Lattner succ_end(ExistPred) && "ExistPred is not a predecessor of Succ!"); 912bdcb56146279009f233933a101cb3dd54a951cdChris Lattner if (!isa<PHINode>(Succ->begin())) return; // Quick exit if nothing to do 922bdcb56146279009f233933a101cb3dd54a951cdChris Lattner 93093a4385027235459ab6972b2e2fdc79061773cfChris Lattner PHINode *PN; 94093a4385027235459ab6972b2e2fdc79061773cfChris Lattner for (BasicBlock::iterator I = Succ->begin(); 95093a4385027235459ab6972b2e2fdc79061773cfChris Lattner (PN = dyn_cast<PHINode>(I)); ++I) 96093a4385027235459ab6972b2e2fdc79061773cfChris Lattner PN->addIncoming(PN->getIncomingValueForBlock(ExistPred), NewPred); 972bdcb56146279009f233933a101cb3dd54a951cdChris Lattner} 982bdcb56146279009f233933a101cb3dd54a951cdChris Lattner 997e66348cba4384d07b37ad1c186e67ba6d26babdChris Lattner 100723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner/// GetIfCondition - Given a basic block (BB) with two predecessors (and 101723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner/// presumably PHI nodes in it), check to see if the merge at this block is due 102723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner/// to an "if condition". If so, return the boolean condition that determines 103723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner/// which entry into BB will be taken. Also, return by references the block 104723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner/// that will be entered from if the condition is true, and the block that will 105723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner/// be entered if the condition is false. 106fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukman/// 107723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner/// 108723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattnerstatic Value *GetIfCondition(BasicBlock *BB, 109723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner BasicBlock *&IfTrue, BasicBlock *&IfFalse) { 110723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner assert(std::distance(pred_begin(BB), pred_end(BB)) == 2 && 111723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner "Function can only handle blocks with 2 predecessors!"); 112723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner BasicBlock *Pred1 = *pred_begin(BB); 113723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner BasicBlock *Pred2 = *++pred_begin(BB); 114723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner 115723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // We can only handle branches. Other control flow will be lowered to 116723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // branches if possible anyway. 117723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner if (!isa<BranchInst>(Pred1->getTerminator()) || 118723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner !isa<BranchInst>(Pred2->getTerminator())) 119723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner return 0; 120723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner BranchInst *Pred1Br = cast<BranchInst>(Pred1->getTerminator()); 121723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner BranchInst *Pred2Br = cast<BranchInst>(Pred2->getTerminator()); 122723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner 123723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // Eliminate code duplication by ensuring that Pred1Br is conditional if 124723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // either are. 125723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner if (Pred2Br->isConditional()) { 126723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // If both branches are conditional, we don't have an "if statement". In 127723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // reality, we could transform this case, but since the condition will be 128723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // required anyway, we stand no chance of eliminating it, so the xform is 129723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // probably not profitable. 130723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner if (Pred1Br->isConditional()) 131723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner return 0; 132723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner 133723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner std::swap(Pred1, Pred2); 134723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner std::swap(Pred1Br, Pred2Br); 135723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner } 136723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner 137723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner if (Pred1Br->isConditional()) { 138723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // If we found a conditional branch predecessor, make sure that it branches 139723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // to BB and Pred2Br. If it doesn't, this isn't an "if statement". 140723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner if (Pred1Br->getSuccessor(0) == BB && 141723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner Pred1Br->getSuccessor(1) == Pred2) { 142723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner IfTrue = Pred1; 143723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner IfFalse = Pred2; 144723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner } else if (Pred1Br->getSuccessor(0) == Pred2 && 145723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner Pred1Br->getSuccessor(1) == BB) { 146723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner IfTrue = Pred2; 147723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner IfFalse = Pred1; 148723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner } else { 149723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // We know that one arm of the conditional goes to BB, so the other must 150723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // go somewhere unrelated, and this must not be an "if statement". 151723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner return 0; 152723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner } 153723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner 154723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // The only thing we have to watch out for here is to make sure that Pred2 155723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // doesn't have incoming edges from other blocks. If it does, the condition 156723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // doesn't dominate BB. 157723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner if (++pred_begin(Pred2) != pred_end(Pred2)) 158723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner return 0; 159723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner 160723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner return Pred1Br->getCondition(); 161723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner } 162723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner 163723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // Ok, if we got here, both predecessors end with an unconditional branch to 164723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // BB. Don't panic! If both blocks only have a single (identical) 165723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // predecessor, and THAT is a conditional branch, then we're all ok! 166723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner if (pred_begin(Pred1) == pred_end(Pred1) || 167723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner ++pred_begin(Pred1) != pred_end(Pred1) || 168723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner pred_begin(Pred2) == pred_end(Pred2) || 169723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner ++pred_begin(Pred2) != pred_end(Pred2) || 170723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner *pred_begin(Pred1) != *pred_begin(Pred2)) 171723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner return 0; 172723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner 173723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // Otherwise, if this is a conditional branch, then we can use it! 174723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner BasicBlock *CommonPred = *pred_begin(Pred1); 175723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner if (BranchInst *BI = dyn_cast<BranchInst>(CommonPred->getTerminator())) { 176723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner assert(BI->isConditional() && "Two successors but not conditional?"); 177723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner if (BI->getSuccessor(0) == Pred1) { 178723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner IfTrue = Pred1; 179723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner IfFalse = Pred2; 180723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner } else { 181723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner IfTrue = Pred2; 182723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner IfFalse = Pred1; 183723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner } 184723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner return BI->getCondition(); 185723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner } 186723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner return 0; 187723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner} 188723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner 1895049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// DominatesMergePoint - If we have a merge point of an "if condition" as 1905049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// accepted above, return true if the specified value dominates the block. We 1915049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// don't handle the true generality of domination here, just a special case 1925049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// which works well enough for us. 1935049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// 1945049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// If AggressiveInsts is non-null, and if V does not dominate BB, we check to 1955049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// see if V (which must be an instruction) is cheap to compute and is 1965049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// non-trapping. If both are true, the instruction is inserted into the set 1975049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// and true is returned. 1989c07866ef861e072395306e9811c329c7fe5bbe8Chris Lattnerstatic bool DominatesMergePoint(Value *V, BasicBlock *BB, 1999c07866ef861e072395306e9811c329c7fe5bbe8Chris Lattner std::set<Instruction*> *AggressiveInsts) { 200570751c2a7d8851bc61e408746a903b0253d2d21Chris Lattner Instruction *I = dyn_cast<Instruction>(V); 201b74b1816305affe25da32c2f29532df41a23cd55Chris Lattner if (!I) { 202b74b1816305affe25da32c2f29532df41a23cd55Chris Lattner // Non-instructions all dominate instructions, but not all constantexprs 203b74b1816305affe25da32c2f29532df41a23cd55Chris Lattner // can be executed unconditionally. 204b74b1816305affe25da32c2f29532df41a23cd55Chris Lattner if (ConstantExpr *C = dyn_cast<ConstantExpr>(V)) 205b74b1816305affe25da32c2f29532df41a23cd55Chris Lattner if (C->canTrap()) 206b74b1816305affe25da32c2f29532df41a23cd55Chris Lattner return false; 207b74b1816305affe25da32c2f29532df41a23cd55Chris Lattner return true; 208b74b1816305affe25da32c2f29532df41a23cd55Chris Lattner } 209570751c2a7d8851bc61e408746a903b0253d2d21Chris Lattner BasicBlock *PBB = I->getParent(); 210570751c2a7d8851bc61e408746a903b0253d2d21Chris Lattner 211da895d63377b421dc50117befb2bec80d2973526Chris Lattner // We don't want to allow weird loops that might have the "if condition" in 212570751c2a7d8851bc61e408746a903b0253d2d21Chris Lattner // the bottom of this block. 213570751c2a7d8851bc61e408746a903b0253d2d21Chris Lattner if (PBB == BB) return false; 214570751c2a7d8851bc61e408746a903b0253d2d21Chris Lattner 215570751c2a7d8851bc61e408746a903b0253d2d21Chris Lattner // If this instruction is defined in a block that contains an unconditional 216570751c2a7d8851bc61e408746a903b0253d2d21Chris Lattner // branch to BB, then it must be in the 'conditional' part of the "if 217570751c2a7d8851bc61e408746a903b0253d2d21Chris Lattner // statement". 218570751c2a7d8851bc61e408746a903b0253d2d21Chris Lattner if (BranchInst *BI = dyn_cast<BranchInst>(PBB->getTerminator())) 219570751c2a7d8851bc61e408746a903b0253d2d21Chris Lattner if (BI->isUnconditional() && BI->getSuccessor(0) == BB) { 2209c07866ef861e072395306e9811c329c7fe5bbe8Chris Lattner if (!AggressiveInsts) return false; 221570751c2a7d8851bc61e408746a903b0253d2d21Chris Lattner // Okay, it looks like the instruction IS in the "condition". Check to 2224bb31bfaa3ed2495dd99304316344dbe54f1d756Dan Gohman // see if it's a cheap instruction to unconditionally compute, and if it 223570751c2a7d8851bc61e408746a903b0253d2d21Chris Lattner // only uses stuff defined outside of the condition. If so, hoist it out. 2240b79a7727d68a507837e827803859424cf3d997bEli Friedman if (!I->isSafeToSpeculativelyExecute()) 2250b79a7727d68a507837e827803859424cf3d997bEli Friedman return false; 2260b79a7727d68a507837e827803859424cf3d997bEli Friedman 227570751c2a7d8851bc61e408746a903b0253d2d21Chris Lattner switch (I->getOpcode()) { 228570751c2a7d8851bc61e408746a903b0253d2d21Chris Lattner default: return false; // Cannot hoist this out safely. 2293a56d146413ee344b10bbcb2b7d8dffaadc9fadeDale Johannesen case Instruction::Load: { 2300b79a7727d68a507837e827803859424cf3d997bEli Friedman // We have to check to make sure there are no instructions before the 2310b79a7727d68a507837e827803859424cf3d997bEli Friedman // load in its basic block, as we are going to hoist the loop out to 2320b79a7727d68a507837e827803859424cf3d997bEli Friedman // its predecessor. 2333a56d146413ee344b10bbcb2b7d8dffaadc9fadeDale Johannesen BasicBlock::iterator IP = PBB->begin(); 2343a56d146413ee344b10bbcb2b7d8dffaadc9fadeDale Johannesen while (isa<DbgInfoIntrinsic>(IP)) 2353a56d146413ee344b10bbcb2b7d8dffaadc9fadeDale Johannesen IP++; 2363a56d146413ee344b10bbcb2b7d8dffaadc9fadeDale Johannesen if (IP != BasicBlock::iterator(I)) 237570751c2a7d8851bc61e408746a903b0253d2d21Chris Lattner return false; 238570751c2a7d8851bc61e408746a903b0253d2d21Chris Lattner break; 2393a56d146413ee344b10bbcb2b7d8dffaadc9fadeDale Johannesen } 240570751c2a7d8851bc61e408746a903b0253d2d21Chris Lattner case Instruction::Add: 241570751c2a7d8851bc61e408746a903b0253d2d21Chris Lattner case Instruction::Sub: 242570751c2a7d8851bc61e408746a903b0253d2d21Chris Lattner case Instruction::And: 243570751c2a7d8851bc61e408746a903b0253d2d21Chris Lattner case Instruction::Or: 244570751c2a7d8851bc61e408746a903b0253d2d21Chris Lattner case Instruction::Xor: 245570751c2a7d8851bc61e408746a903b0253d2d21Chris Lattner case Instruction::Shl: 2463822ff5c71478c7c90a50ca57045fb676fcb5005Reid Spencer case Instruction::LShr: 2473822ff5c71478c7c90a50ca57045fb676fcb5005Reid Spencer case Instruction::AShr: 248e4d87aa2de6e52952dca73716386db09aad5a8fdReid Spencer case Instruction::ICmp: 249570751c2a7d8851bc61e408746a903b0253d2d21Chris Lattner break; // These are all cheap and non-trapping instructions. 250570751c2a7d8851bc61e408746a903b0253d2d21Chris Lattner } 251fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukman 252570751c2a7d8851bc61e408746a903b0253d2d21Chris Lattner // Okay, we can only really hoist these out if their operands are not 253570751c2a7d8851bc61e408746a903b0253d2d21Chris Lattner // defined in the conditional region. 254f7ea3638e0f85a9793e7c9f081ed6ddb1ebb832eGabor Greif for (User::op_iterator i = I->op_begin(), e = I->op_end(); i != e; ++i) 255f7ea3638e0f85a9793e7c9f081ed6ddb1ebb832eGabor Greif if (!DominatesMergePoint(*i, BB, 0)) 256570751c2a7d8851bc61e408746a903b0253d2d21Chris Lattner return false; 2579c07866ef861e072395306e9811c329c7fe5bbe8Chris Lattner // Okay, it's safe to do this! Remember this instruction. 2589c07866ef861e072395306e9811c329c7fe5bbe8Chris Lattner AggressiveInsts->insert(I); 259570751c2a7d8851bc61e408746a903b0253d2d21Chris Lattner } 260723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner 261723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner return true; 262723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner} 26301d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner 26458e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen/// GetConstantInt - Extract ConstantInt from value, looking through IntToPtr 26558e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen/// and PointerNullValue. Return NULL if value is not a constant int. 26628acc135481691771205dea7cb4edbd3927aa764Chris Lattnerstatic ConstantInt *GetConstantInt(Value *V, const TargetData *TD) { 26758e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen // Normal constant int. 26858e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen ConstantInt *CI = dyn_cast<ConstantInt>(V); 2691df9859c40492511b8aa4321eb76496005d3b75bDuncan Sands if (CI || !TD || !isa<Constant>(V) || !V->getType()->isPointerTy()) 27058e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen return CI; 27158e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen 27258e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen // This is some kind of pointer constant. Turn it into a pointer-sized 27358e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen // ConstantInt if possible. 27458e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen const IntegerType *PtrTy = TD->getIntPtrType(V->getContext()); 27558e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen 27658e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen // Null pointer means 0, see SelectionDAGBuilder::getValue(const Value*). 27758e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen if (isa<ConstantPointerNull>(V)) 27858e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen return ConstantInt::get(PtrTy, 0); 27958e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen 28058e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen // IntToPtr const int. 28158e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) 28258e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen if (CE->getOpcode() == Instruction::IntToPtr) 28358e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen if (ConstantInt *CI = dyn_cast<ConstantInt>(CE->getOperand(0))) { 28458e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen // The constant is very likely to have the right type already. 28558e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen if (CI->getType() == PtrTy) 28658e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen return CI; 28758e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen else 28858e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen return cast<ConstantInt> 28958e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen (ConstantExpr::getIntegerCast(CI, PtrTy, /*isSigned=*/false)); 29058e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen } 29158e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen return 0; 29258e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen} 29358e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen 2945049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// GatherConstantSetEQs - Given a potentially 'or'd together collection of 2955049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// icmp_eq instructions that compare a value against a constant, return the 2965049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// value being compared, and stick the constant into the Values vector. 29728acc135481691771205dea7cb4edbd3927aa764Chris Lattnerstatic Value * 29828acc135481691771205dea7cb4edbd3927aa764Chris LattnerGatherConstantSetEQs(Value *V, std::vector<ConstantInt*> &Values, 29928acc135481691771205dea7cb4edbd3927aa764Chris Lattner const TargetData *TD) { 3009a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner Instruction *Inst = dyn_cast<Instruction>(V); 3019a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (Inst == 0) return 0; 3029a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner 3039a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (Inst->getOpcode() == Instruction::ICmp && 3049a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner cast<ICmpInst>(Inst)->getPredicate() == ICmpInst::ICMP_EQ) { 30528acc135481691771205dea7cb4edbd3927aa764Chris Lattner if (ConstantInt *C = GetConstantInt(Inst->getOperand(1), TD)) { 3069a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner Values.push_back(C); 3079a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner return Inst->getOperand(0); 3080d56008f53587531718ec36af82cc24576580b36Chris Lattner } 30928acc135481691771205dea7cb4edbd3927aa764Chris Lattner if (ConstantInt *C = GetConstantInt(Inst->getOperand(0), TD)) { 3109a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner Values.push_back(C); 3119a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner return Inst->getOperand(1); 3129a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner } 3139a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner } else if (Inst->getOpcode() == Instruction::Or) { 31428acc135481691771205dea7cb4edbd3927aa764Chris Lattner if (Value *LHS = GatherConstantSetEQs(Inst->getOperand(0), Values, TD)) 31528acc135481691771205dea7cb4edbd3927aa764Chris Lattner if (Value *RHS = GatherConstantSetEQs(Inst->getOperand(1), Values, TD)) 3169a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (LHS == RHS) 3179a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner return LHS; 31807e6e56f57e8781a8d7bc601cc9034a3741d84c2Anton Korobeynikov } 3190d56008f53587531718ec36af82cc24576580b36Chris Lattner return 0; 3200d56008f53587531718ec36af82cc24576580b36Chris Lattner} 3210d56008f53587531718ec36af82cc24576580b36Chris Lattner 3225049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// GatherConstantSetNEs - Given a potentially 'and'd together collection of 3235049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// setne instructions that compare a value against a constant, return the value 3245049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// being compared, and stick the constant into the Values vector. 32528acc135481691771205dea7cb4edbd3927aa764Chris Lattnerstatic Value * 32628acc135481691771205dea7cb4edbd3927aa764Chris LattnerGatherConstantSetNEs(Value *V, std::vector<ConstantInt*> &Values, 32728acc135481691771205dea7cb4edbd3927aa764Chris Lattner const TargetData *TD) { 3289a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner Instruction *Inst = dyn_cast<Instruction>(V); 3299a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (Inst == 0) return 0; 3309a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner 3319a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (Inst->getOpcode() == Instruction::ICmp && 3329a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner cast<ICmpInst>(Inst)->getPredicate() == ICmpInst::ICMP_NE) { 33328acc135481691771205dea7cb4edbd3927aa764Chris Lattner if (ConstantInt *C = GetConstantInt(Inst->getOperand(1), TD)) { 3349a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner Values.push_back(C); 3359a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner return Inst->getOperand(0); 3360d56008f53587531718ec36af82cc24576580b36Chris Lattner } 33728acc135481691771205dea7cb4edbd3927aa764Chris Lattner if (ConstantInt *C = GetConstantInt(Inst->getOperand(0), TD)) { 3389a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner Values.push_back(C); 3399a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner return Inst->getOperand(1); 3409a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner } 3419a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner } else if (Inst->getOpcode() == Instruction::And) { 34228acc135481691771205dea7cb4edbd3927aa764Chris Lattner if (Value *LHS = GatherConstantSetNEs(Inst->getOperand(0), Values, TD)) 34328acc135481691771205dea7cb4edbd3927aa764Chris Lattner if (Value *RHS = GatherConstantSetNEs(Inst->getOperand(1), Values, TD)) 3449a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (LHS == RHS) 3459a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner return LHS; 34607e6e56f57e8781a8d7bc601cc9034a3741d84c2Anton Korobeynikov } 3470d56008f53587531718ec36af82cc24576580b36Chris Lattner return 0; 3480d56008f53587531718ec36af82cc24576580b36Chris Lattner} 3490d56008f53587531718ec36af82cc24576580b36Chris Lattner 3500d56008f53587531718ec36af82cc24576580b36Chris Lattner/// GatherValueComparisons - If the specified Cond is an 'and' or 'or' of a 3510d56008f53587531718ec36af82cc24576580b36Chris Lattner/// bunch of comparisons of one value against constants, return the value and 3520d56008f53587531718ec36af82cc24576580b36Chris Lattner/// the constants being compared. 35328acc135481691771205dea7cb4edbd3927aa764Chris Lattnerstatic bool GatherValueComparisons(Value *CondV, Value *&CompVal, 35428acc135481691771205dea7cb4edbd3927aa764Chris Lattner std::vector<ConstantInt*> &Values, 35528acc135481691771205dea7cb4edbd3927aa764Chris Lattner const TargetData *TD) { 356cd4b709d73f8705571d5680d5d7c1962a1239fdaChris Lattner Instruction *Cond = dyn_cast<Instruction>(CondV); 357cd4b709d73f8705571d5680d5d7c1962a1239fdaChris Lattner if (Cond == 0) return false; 358cd4b709d73f8705571d5680d5d7c1962a1239fdaChris Lattner 3590d56008f53587531718ec36af82cc24576580b36Chris Lattner if (Cond->getOpcode() == Instruction::Or) { 36028acc135481691771205dea7cb4edbd3927aa764Chris Lattner CompVal = GatherConstantSetEQs(Cond, Values, TD); 3610d56008f53587531718ec36af82cc24576580b36Chris Lattner 3620d56008f53587531718ec36af82cc24576580b36Chris Lattner // Return true to indicate that the condition is true if the CompVal is 3630d56008f53587531718ec36af82cc24576580b36Chris Lattner // equal to one of the constants. 3640d56008f53587531718ec36af82cc24576580b36Chris Lattner return true; 3659a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner } 3669a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (Cond->getOpcode() == Instruction::And) { 36728acc135481691771205dea7cb4edbd3927aa764Chris Lattner CompVal = GatherConstantSetNEs(Cond, Values, TD); 368fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukman 3690d56008f53587531718ec36af82cc24576580b36Chris Lattner // Return false to indicate that the condition is false if the CompVal is 3700d56008f53587531718ec36af82cc24576580b36Chris Lattner // equal to one of the constants. 3710d56008f53587531718ec36af82cc24576580b36Chris Lattner return false; 3720d56008f53587531718ec36af82cc24576580b36Chris Lattner } 3730d56008f53587531718ec36af82cc24576580b36Chris Lattner return false; 3740d56008f53587531718ec36af82cc24576580b36Chris Lattner} 3750d56008f53587531718ec36af82cc24576580b36Chris Lattner 376080efb8cea6255b4f1f373d9cb583d6a6302106bEli Friedmanstatic void EraseTerminatorInstAndDCECond(TerminatorInst *TI) { 377080efb8cea6255b4f1f373d9cb583d6a6302106bEli Friedman Instruction* Cond = 0; 378080efb8cea6255b4f1f373d9cb583d6a6302106bEli Friedman if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) { 379080efb8cea6255b4f1f373d9cb583d6a6302106bEli Friedman Cond = dyn_cast<Instruction>(SI->getCondition()); 380080efb8cea6255b4f1f373d9cb583d6a6302106bEli Friedman } else if (BranchInst *BI = dyn_cast<BranchInst>(TI)) { 381080efb8cea6255b4f1f373d9cb583d6a6302106bEli Friedman if (BI->isConditional()) 382080efb8cea6255b4f1f373d9cb583d6a6302106bEli Friedman Cond = dyn_cast<Instruction>(BI->getCondition()); 3837ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel } else if (IndirectBrInst *IBI = dyn_cast<IndirectBrInst>(TI)) { 3847ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel Cond = dyn_cast<Instruction>(IBI->getAddress()); 385080efb8cea6255b4f1f373d9cb583d6a6302106bEli Friedman } 386080efb8cea6255b4f1f373d9cb583d6a6302106bEli Friedman 387080efb8cea6255b4f1f373d9cb583d6a6302106bEli Friedman TI->eraseFromParent(); 388080efb8cea6255b4f1f373d9cb583d6a6302106bEli Friedman if (Cond) RecursivelyDeleteTriviallyDeadInstructions(Cond); 389080efb8cea6255b4f1f373d9cb583d6a6302106bEli Friedman} 390080efb8cea6255b4f1f373d9cb583d6a6302106bEli Friedman 3919fd4955c6ab9a191dec2d5afd4b2027d4b906f2eChris Lattner/// isValueEqualityComparison - Return true if the specified terminator checks 3929fd4955c6ab9a191dec2d5afd4b2027d4b906f2eChris Lattner/// to see if a value is equal to constant integer value. 39358e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund OlesenValue *SimplifyCFGOpt::isValueEqualityComparison(TerminatorInst *TI) { 39458e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen Value *CV = 0; 3954bebf08d152d84970d250feec72fb734cb8a5316Chris Lattner if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) { 3964bebf08d152d84970d250feec72fb734cb8a5316Chris Lattner // Do not permit merging of large switch instructions into their 3974bebf08d152d84970d250feec72fb734cb8a5316Chris Lattner // predecessors unless there is only one predecessor. 39858e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen if (SI->getNumSuccessors()*std::distance(pred_begin(SI->getParent()), 39958e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen pred_end(SI->getParent())) <= 128) 40058e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen CV = SI->getCondition(); 40158e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen } else if (BranchInst *BI = dyn_cast<BranchInst>(TI)) 402542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner if (BI->isConditional() && BI->getCondition()->hasOneUse()) 403e4d87aa2de6e52952dca73716386db09aad5a8fdReid Spencer if (ICmpInst *ICI = dyn_cast<ICmpInst>(BI->getCondition())) 404e4d87aa2de6e52952dca73716386db09aad5a8fdReid Spencer if ((ICI->getPredicate() == ICmpInst::ICMP_EQ || 405e4d87aa2de6e52952dca73716386db09aad5a8fdReid Spencer ICI->getPredicate() == ICmpInst::ICMP_NE) && 40628acc135481691771205dea7cb4edbd3927aa764Chris Lattner GetConstantInt(ICI->getOperand(1), TD)) 40758e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen CV = ICI->getOperand(0); 40858e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen 40958e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen // Unwrap any lossless ptrtoint cast. 41058e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen if (TD && CV && CV->getType() == TD->getIntPtrType(CV->getContext())) 41158e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen if (PtrToIntInst *PTII = dyn_cast<PtrToIntInst>(CV)) 41258e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen CV = PTII->getOperand(0); 41358e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen return CV; 414542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner} 415542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner 4165049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// GetValueEqualityComparisonCases - Given a value comparison instruction, 4175049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// decode all of the 'cases' that it represents and return the 'default' block. 41858e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund OlesenBasicBlock *SimplifyCFGOpt:: 419fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha BrukmanGetValueEqualityComparisonCases(TerminatorInst *TI, 420542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner std::vector<std::pair<ConstantInt*, 421542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner BasicBlock*> > &Cases) { 422542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) { 423542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner Cases.reserve(SI->getNumCases()); 424542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner for (unsigned i = 1, e = SI->getNumCases(); i != e; ++i) 425be54dcc8a9d14592e324d6e6ae1322782e17f09fChris Lattner Cases.push_back(std::make_pair(SI->getCaseValue(i), SI->getSuccessor(i))); 426542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner return SI->getDefaultDest(); 427542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner } 428542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner 429542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner BranchInst *BI = cast<BranchInst>(TI); 430e4d87aa2de6e52952dca73716386db09aad5a8fdReid Spencer ICmpInst *ICI = cast<ICmpInst>(BI->getCondition()); 43128acc135481691771205dea7cb4edbd3927aa764Chris Lattner Cases.push_back(std::make_pair(GetConstantInt(ICI->getOperand(1), TD), 432e4d87aa2de6e52952dca73716386db09aad5a8fdReid Spencer BI->getSuccessor(ICI->getPredicate() == 433e4d87aa2de6e52952dca73716386db09aad5a8fdReid Spencer ICmpInst::ICMP_NE))); 434e4d87aa2de6e52952dca73716386db09aad5a8fdReid Spencer return BI->getSuccessor(ICI->getPredicate() == ICmpInst::ICMP_EQ); 435542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner} 436542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner 437542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner 4385049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// EliminateBlockCases - Given a vector of bb/value pairs, remove any entries 4395049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// in the list that match the specified block. 440fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukmanstatic void EliminateBlockCases(BasicBlock *BB, 441623369ac5669a3667a94a3cbba342dea78845615Chris Lattner std::vector<std::pair<ConstantInt*, BasicBlock*> > &Cases) { 442623369ac5669a3667a94a3cbba342dea78845615Chris Lattner for (unsigned i = 0, e = Cases.size(); i != e; ++i) 443623369ac5669a3667a94a3cbba342dea78845615Chris Lattner if (Cases[i].second == BB) { 444623369ac5669a3667a94a3cbba342dea78845615Chris Lattner Cases.erase(Cases.begin()+i); 445623369ac5669a3667a94a3cbba342dea78845615Chris Lattner --i; --e; 446623369ac5669a3667a94a3cbba342dea78845615Chris Lattner } 447623369ac5669a3667a94a3cbba342dea78845615Chris Lattner} 448623369ac5669a3667a94a3cbba342dea78845615Chris Lattner 4495049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// ValuesOverlap - Return true if there are any keys in C1 that exist in C2 as 4505049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// well. 451623369ac5669a3667a94a3cbba342dea78845615Chris Lattnerstatic bool 452623369ac5669a3667a94a3cbba342dea78845615Chris LattnerValuesOverlap(std::vector<std::pair<ConstantInt*, BasicBlock*> > &C1, 453623369ac5669a3667a94a3cbba342dea78845615Chris Lattner std::vector<std::pair<ConstantInt*, BasicBlock*> > &C2) { 454623369ac5669a3667a94a3cbba342dea78845615Chris Lattner std::vector<std::pair<ConstantInt*, BasicBlock*> > *V1 = &C1, *V2 = &C2; 455623369ac5669a3667a94a3cbba342dea78845615Chris Lattner 456623369ac5669a3667a94a3cbba342dea78845615Chris Lattner // Make V1 be smaller than V2. 457623369ac5669a3667a94a3cbba342dea78845615Chris Lattner if (V1->size() > V2->size()) 458623369ac5669a3667a94a3cbba342dea78845615Chris Lattner std::swap(V1, V2); 459623369ac5669a3667a94a3cbba342dea78845615Chris Lattner 460623369ac5669a3667a94a3cbba342dea78845615Chris Lattner if (V1->size() == 0) return false; 461623369ac5669a3667a94a3cbba342dea78845615Chris Lattner if (V1->size() == 1) { 462623369ac5669a3667a94a3cbba342dea78845615Chris Lattner // Just scan V2. 463623369ac5669a3667a94a3cbba342dea78845615Chris Lattner ConstantInt *TheVal = (*V1)[0].first; 464623369ac5669a3667a94a3cbba342dea78845615Chris Lattner for (unsigned i = 0, e = V2->size(); i != e; ++i) 465623369ac5669a3667a94a3cbba342dea78845615Chris Lattner if (TheVal == (*V2)[i].first) 466623369ac5669a3667a94a3cbba342dea78845615Chris Lattner return true; 467623369ac5669a3667a94a3cbba342dea78845615Chris Lattner } 468623369ac5669a3667a94a3cbba342dea78845615Chris Lattner 469623369ac5669a3667a94a3cbba342dea78845615Chris Lattner // Otherwise, just sort both lists and compare element by element. 470fca20f507ccfd3407511cd1ccb94ab4421388107Chris Lattner array_pod_sort(V1->begin(), V1->end()); 471fca20f507ccfd3407511cd1ccb94ab4421388107Chris Lattner array_pod_sort(V2->begin(), V2->end()); 472623369ac5669a3667a94a3cbba342dea78845615Chris Lattner unsigned i1 = 0, i2 = 0, e1 = V1->size(), e2 = V2->size(); 473623369ac5669a3667a94a3cbba342dea78845615Chris Lattner while (i1 != e1 && i2 != e2) { 474623369ac5669a3667a94a3cbba342dea78845615Chris Lattner if ((*V1)[i1].first == (*V2)[i2].first) 475623369ac5669a3667a94a3cbba342dea78845615Chris Lattner return true; 476623369ac5669a3667a94a3cbba342dea78845615Chris Lattner if ((*V1)[i1].first < (*V2)[i2].first) 477623369ac5669a3667a94a3cbba342dea78845615Chris Lattner ++i1; 478623369ac5669a3667a94a3cbba342dea78845615Chris Lattner else 479623369ac5669a3667a94a3cbba342dea78845615Chris Lattner ++i2; 480623369ac5669a3667a94a3cbba342dea78845615Chris Lattner } 481623369ac5669a3667a94a3cbba342dea78845615Chris Lattner return false; 482623369ac5669a3667a94a3cbba342dea78845615Chris Lattner} 483623369ac5669a3667a94a3cbba342dea78845615Chris Lattner 4845049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// SimplifyEqualityComparisonWithOnlyPredecessor - If TI is known to be a 4855049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// terminator instruction and its block is known to only have a single 4865049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// predecessor block, check to see if that predecessor is also a value 4875049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// comparison with the same value, and if that comparison determines the 4885049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// outcome of this comparison. If so, simplify TI. This does a very limited 4895049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// form of jump threading. 49058e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesenbool SimplifyCFGOpt:: 49158e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund OlesenSimplifyEqualityComparisonWithOnlyPredecessor(TerminatorInst *TI, 49258e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen BasicBlock *Pred) { 493623369ac5669a3667a94a3cbba342dea78845615Chris Lattner Value *PredVal = isValueEqualityComparison(Pred->getTerminator()); 494623369ac5669a3667a94a3cbba342dea78845615Chris Lattner if (!PredVal) return false; // Not a value comparison in predecessor. 495623369ac5669a3667a94a3cbba342dea78845615Chris Lattner 496623369ac5669a3667a94a3cbba342dea78845615Chris Lattner Value *ThisVal = isValueEqualityComparison(TI); 497623369ac5669a3667a94a3cbba342dea78845615Chris Lattner assert(ThisVal && "This isn't a value comparison!!"); 498623369ac5669a3667a94a3cbba342dea78845615Chris Lattner if (ThisVal != PredVal) return false; // Different predicates. 499623369ac5669a3667a94a3cbba342dea78845615Chris Lattner 500623369ac5669a3667a94a3cbba342dea78845615Chris Lattner // Find out information about when control will move from Pred to TI's block. 501623369ac5669a3667a94a3cbba342dea78845615Chris Lattner std::vector<std::pair<ConstantInt*, BasicBlock*> > PredCases; 502623369ac5669a3667a94a3cbba342dea78845615Chris Lattner BasicBlock *PredDef = GetValueEqualityComparisonCases(Pred->getTerminator(), 503623369ac5669a3667a94a3cbba342dea78845615Chris Lattner PredCases); 504623369ac5669a3667a94a3cbba342dea78845615Chris Lattner EliminateBlockCases(PredDef, PredCases); // Remove default from cases. 505fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukman 506623369ac5669a3667a94a3cbba342dea78845615Chris Lattner // Find information about how control leaves this block. 507623369ac5669a3667a94a3cbba342dea78845615Chris Lattner std::vector<std::pair<ConstantInt*, BasicBlock*> > ThisCases; 508623369ac5669a3667a94a3cbba342dea78845615Chris Lattner BasicBlock *ThisDef = GetValueEqualityComparisonCases(TI, ThisCases); 509623369ac5669a3667a94a3cbba342dea78845615Chris Lattner EliminateBlockCases(ThisDef, ThisCases); // Remove default from cases. 510623369ac5669a3667a94a3cbba342dea78845615Chris Lattner 511623369ac5669a3667a94a3cbba342dea78845615Chris Lattner // If TI's block is the default block from Pred's comparison, potentially 512623369ac5669a3667a94a3cbba342dea78845615Chris Lattner // simplify TI based on this knowledge. 513623369ac5669a3667a94a3cbba342dea78845615Chris Lattner if (PredDef == TI->getParent()) { 514623369ac5669a3667a94a3cbba342dea78845615Chris Lattner // If we are here, we know that the value is none of those cases listed in 515623369ac5669a3667a94a3cbba342dea78845615Chris Lattner // PredCases. If there are any cases in ThisCases that are in PredCases, we 516623369ac5669a3667a94a3cbba342dea78845615Chris Lattner // can simplify TI. 5179a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (!ValuesOverlap(PredCases, ThisCases)) 5189a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner return false; 5199a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner 5209a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (isa<BranchInst>(TI)) { 5219a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // Okay, one of the successors of this condbr is dead. Convert it to a 5229a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // uncond br. 5239a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner assert(ThisCases.size() == 1 && "Branch can only have one case!"); 5249a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // Insert the new branch. 5259a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner Instruction *NI = BranchInst::Create(ThisDef, TI); 5269a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner (void) NI; 527623369ac5669a3667a94a3cbba342dea78845615Chris Lattner 5289a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // Remove PHI node entries for the dead edge. 5299a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner ThisCases[0].second->removePredecessor(TI->getParent()); 530623369ac5669a3667a94a3cbba342dea78845615Chris Lattner 5319a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner DEBUG(dbgs() << "Threading pred instr: " << *Pred->getTerminator() 5329a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner << "Through successor TI: " << *TI << "Leaving: " << *NI << "\n"); 533623369ac5669a3667a94a3cbba342dea78845615Chris Lattner 5349a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner EraseTerminatorInstAndDCECond(TI); 5359a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner return true; 536623369ac5669a3667a94a3cbba342dea78845615Chris Lattner } 5379a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner 5389a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner SwitchInst *SI = cast<SwitchInst>(TI); 5399a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // Okay, TI has cases that are statically dead, prune them away. 5409a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner SmallPtrSet<Constant*, 16> DeadCases; 541623369ac5669a3667a94a3cbba342dea78845615Chris Lattner for (unsigned i = 0, e = PredCases.size(); i != e; ++i) 5429a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner DeadCases.insert(PredCases[i].first); 5439a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner 5449a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner DEBUG(dbgs() << "Threading pred instr: " << *Pred->getTerminator() 5459a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner << "Through successor TI: " << *TI); 5469a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner 5479a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner for (unsigned i = SI->getNumCases()-1; i != 0; --i) 5489a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (DeadCases.count(SI->getCaseValue(i))) { 5499a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner SI->getSuccessor(i)->removePredecessor(TI->getParent()); 5509a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner SI->removeCase(i); 551623369ac5669a3667a94a3cbba342dea78845615Chris Lattner } 552623369ac5669a3667a94a3cbba342dea78845615Chris Lattner 5539a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner DEBUG(dbgs() << "Leaving: " << *TI << "\n"); 5549a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner return true; 5559a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner } 5569a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner 5579a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // Otherwise, TI's block must correspond to some matched value. Find out 5589a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // which value (or set of values) this is. 5599a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner ConstantInt *TIV = 0; 5609a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner BasicBlock *TIBB = TI->getParent(); 5619a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner for (unsigned i = 0, e = PredCases.size(); i != e; ++i) 5629a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (PredCases[i].second == TIBB) { 5639a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (TIV != 0) 5649a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner return false; // Cannot handle multiple values coming to this block. 5659a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner TIV = PredCases[i].first; 5669a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner } 5679a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner assert(TIV && "No edge from pred to succ?"); 5689a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner 5699a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // Okay, we found the one constant that our value can be if we get into TI's 5709a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // BB. Find out which successor will unconditionally be branched to. 5719a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner BasicBlock *TheRealDest = 0; 5729a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner for (unsigned i = 0, e = ThisCases.size(); i != e; ++i) 5739a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (ThisCases[i].first == TIV) { 5749a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner TheRealDest = ThisCases[i].second; 5759a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner break; 5769a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner } 5779a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner 5789a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // If not handled by any explicit cases, it is handled by the default case. 5799a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (TheRealDest == 0) TheRealDest = ThisDef; 580623369ac5669a3667a94a3cbba342dea78845615Chris Lattner 5819a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // Remove PHI node entries for dead edges. 5829a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner BasicBlock *CheckEdge = TheRealDest; 5839a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner for (succ_iterator SI = succ_begin(TIBB), e = succ_end(TIBB); SI != e; ++SI) 5849a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (*SI != CheckEdge) 5859a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner (*SI)->removePredecessor(TIBB); 5869a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner else 5879a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner CheckEdge = 0; 588623369ac5669a3667a94a3cbba342dea78845615Chris Lattner 5899a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // Insert the new branch. 5909a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner Instruction *NI = BranchInst::Create(TheRealDest, TI); 5919a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner (void) NI; 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} 599623369ac5669a3667a94a3cbba342dea78845615Chris Lattner 600c81f5445a7cbe3ba0252aec030082a40e5019eceDale Johannesennamespace { 601c81f5445a7cbe3ba0252aec030082a40e5019eceDale Johannesen /// ConstantIntOrdering - This class implements a stable ordering of constant 602c81f5445a7cbe3ba0252aec030082a40e5019eceDale Johannesen /// integers that does not depend on their address. This is important for 603c81f5445a7cbe3ba0252aec030082a40e5019eceDale Johannesen /// applications that sort ConstantInt's to ensure uniqueness. 604c81f5445a7cbe3ba0252aec030082a40e5019eceDale Johannesen struct ConstantIntOrdering { 605c81f5445a7cbe3ba0252aec030082a40e5019eceDale Johannesen bool operator()(const ConstantInt *LHS, const ConstantInt *RHS) const { 606c81f5445a7cbe3ba0252aec030082a40e5019eceDale Johannesen return LHS->getValue().ult(RHS->getValue()); 607c81f5445a7cbe3ba0252aec030082a40e5019eceDale Johannesen } 608c81f5445a7cbe3ba0252aec030082a40e5019eceDale Johannesen }; 609c81f5445a7cbe3ba0252aec030082a40e5019eceDale Johannesen} 610a9537cf3fcf9fdaac94749db9fbd34912b1f0f08Dale Johannesen 6116d4d21e29d4840236ab6f15c5247379820021d0cChris Lattnerstatic int ConstantIntSortPredicate(const void *P1, const void *P2) { 6126d4d21e29d4840236ab6f15c5247379820021d0cChris Lattner const ConstantInt *LHS = *(const ConstantInt**)P1; 6136d4d21e29d4840236ab6f15c5247379820021d0cChris Lattner const ConstantInt *RHS = *(const ConstantInt**)P2; 6146d4d21e29d4840236ab6f15c5247379820021d0cChris Lattner return LHS->getValue().ult(RHS->getValue()); 6156d4d21e29d4840236ab6f15c5247379820021d0cChris Lattner} 6166d4d21e29d4840236ab6f15c5247379820021d0cChris Lattner 6175049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// FoldValueComparisonIntoPredecessors - The specified terminator is a value 6185049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// equality comparison instruction (either a switch or a branch on "X == c"). 6195049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// See if any of the predecessors of the terminator block are value comparisons 6205049fa6bbc66534fe0cc361808dff80fd2d5cde2Bill Wendling/// on the same value. If so, and if safe to do so, fold them together. 62158e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesenbool SimplifyCFGOpt::FoldValueComparisonIntoPredecessors(TerminatorInst *TI) { 622542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner BasicBlock *BB = TI->getParent(); 623542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner Value *CV = isValueEqualityComparison(TI); // CondVal 624542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner assert(CV && "Not a comparison?"); 625542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner bool Changed = false; 626542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner 6278244243a31d636ce8838a81d4c402274fd391d2bChris Lattner SmallVector<BasicBlock*, 16> Preds(pred_begin(BB), pred_end(BB)); 628542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner while (!Preds.empty()) { 629e9d87f49063cb1bd213d8e9c339b9b63393cc2d9Dan Gohman BasicBlock *Pred = Preds.pop_back_val(); 630fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukman 631542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // See if the predecessor is a comparison with the same value. 632542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner TerminatorInst *PTI = Pred->getTerminator(); 633542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner Value *PCV = isValueEqualityComparison(PTI); // PredCondVal 634542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner 635542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner if (PCV == CV && SafeToMergeTerminators(TI, PTI)) { 636542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // Figure out which 'cases' to copy from SI to PSI. 637542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner std::vector<std::pair<ConstantInt*, BasicBlock*> > BBCases; 638542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner BasicBlock *BBDefault = GetValueEqualityComparisonCases(TI, BBCases); 639542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner 640542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner std::vector<std::pair<ConstantInt*, BasicBlock*> > PredCases; 641542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner BasicBlock *PredDefault = GetValueEqualityComparisonCases(PTI, PredCases); 642542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner 643542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // Based on whether the default edge from PTI goes to BB or not, fill in 644542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // PredCases and PredDefault with the new switch cases we would like to 645542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // build. 6468244243a31d636ce8838a81d4c402274fd391d2bChris Lattner SmallVector<BasicBlock*, 8> NewSuccessors; 647542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner 648542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner if (PredDefault == BB) { 649542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // If this is the default destination from PTI, only the edges in TI 650542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // that don't occur in PTI, or that branch to BB will be activated. 651c81f5445a7cbe3ba0252aec030082a40e5019eceDale Johannesen std::set<ConstantInt*, ConstantIntOrdering> PTIHandled; 652542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner for (unsigned i = 0, e = PredCases.size(); i != e; ++i) 653542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner if (PredCases[i].second != BB) 654542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner PTIHandled.insert(PredCases[i].first); 655542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner else { 656542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // The default destination is BB, we don't need explicit targets. 657542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner std::swap(PredCases[i], PredCases.back()); 658542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner PredCases.pop_back(); 659542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner --i; --e; 660542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner } 661542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner 662542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // Reconstruct the new switch statement we will be building. 663542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner if (PredDefault != BBDefault) { 664542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner PredDefault->removePredecessor(Pred); 665542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner PredDefault = BBDefault; 666542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner NewSuccessors.push_back(BBDefault); 667542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner } 668542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner for (unsigned i = 0, e = BBCases.size(); i != e; ++i) 669542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner if (!PTIHandled.count(BBCases[i].first) && 670542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner BBCases[i].second != BBDefault) { 671542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner PredCases.push_back(BBCases[i]); 672542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner NewSuccessors.push_back(BBCases[i].second); 673542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner } 674542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner 675542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner } else { 676542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // If this is not the default destination from PSI, only the edges 677542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // in SI that occur in PSI with a destination of BB will be 678542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // activated. 679c81f5445a7cbe3ba0252aec030082a40e5019eceDale Johannesen std::set<ConstantInt*, ConstantIntOrdering> PTIHandled; 680542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner for (unsigned i = 0, e = PredCases.size(); i != e; ++i) 681542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner if (PredCases[i].second == BB) { 682542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner PTIHandled.insert(PredCases[i].first); 683542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner std::swap(PredCases[i], PredCases.back()); 684542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner PredCases.pop_back(); 685542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner --i; --e; 686542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner } 687542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner 688542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // Okay, now we know which constants were sent to BB from the 689542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // predecessor. Figure out where they will all go now. 690542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner for (unsigned i = 0, e = BBCases.size(); i != e; ++i) 691542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner if (PTIHandled.count(BBCases[i].first)) { 692542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // If this is one we are capable of getting... 693542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner PredCases.push_back(BBCases[i]); 694542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner NewSuccessors.push_back(BBCases[i].second); 695542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner PTIHandled.erase(BBCases[i].first);// This constant is taken care of 696542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner } 697542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner 698542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // If there are any constants vectored to BB that TI doesn't handle, 699542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // they must go to the default destination of TI. 700c81f5445a7cbe3ba0252aec030082a40e5019eceDale Johannesen for (std::set<ConstantInt*, ConstantIntOrdering>::iterator I = 701c81f5445a7cbe3ba0252aec030082a40e5019eceDale Johannesen PTIHandled.begin(), 702542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner E = PTIHandled.end(); I != E; ++I) { 703542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner PredCases.push_back(std::make_pair(*I, BBDefault)); 704542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner NewSuccessors.push_back(BBDefault); 705542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner } 706542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner } 707542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner 708542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // Okay, at this point, we know which new successor Pred will get. Make 709542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // sure we update the number of entries in the PHI nodes for these 710542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // successors. 711542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner for (unsigned i = 0, e = NewSuccessors.size(); i != e; ++i) 712542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner AddPredecessorToBlock(NewSuccessors[i], Pred, BB); 713542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner 71458e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen // Convert pointer to int before we switch. 7151df9859c40492511b8aa4321eb76496005d3b75bDuncan Sands if (CV->getType()->isPointerTy()) { 71658e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen assert(TD && "Cannot switch on pointer without TargetData"); 71758e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen CV = new PtrToIntInst(CV, TD->getIntPtrType(CV->getContext()), 71858e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen "magicptr", PTI); 71958e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen } 72058e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen 721542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // Now that the successors are updated, create the new Switch instruction. 722b1dbcd886a4b5597a839f299054b78b33fb2d6dfGabor Greif SwitchInst *NewSI = SwitchInst::Create(CV, PredDefault, 723b1dbcd886a4b5597a839f299054b78b33fb2d6dfGabor Greif PredCases.size(), PTI); 724542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner for (unsigned i = 0, e = PredCases.size(); i != e; ++i) 725542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner NewSI->addCase(PredCases[i].first, PredCases[i].second); 72613b2f764c041e15af3d6033826deb9c7e669ca97Chris Lattner 727080efb8cea6255b4f1f373d9cb583d6a6302106bEli Friedman EraseTerminatorInstAndDCECond(PTI); 72813b2f764c041e15af3d6033826deb9c7e669ca97Chris Lattner 729542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // Okay, last check. If BB is still a successor of PSI, then we must 730542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // have an infinite loop case. If so, add an infinitely looping block 731542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // to handle the case to preserve the behavior of the code. 732542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner BasicBlock *InfLoopBlock = 0; 733542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner for (unsigned i = 0, e = NewSI->getNumSuccessors(); i != e; ++i) 734542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner if (NewSI->getSuccessor(i) == BB) { 735542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner if (InfLoopBlock == 0) { 736093a4385027235459ab6972b2e2fdc79061773cfChris Lattner // Insert it at the end of the function, because it's either code, 737542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner // or it won't matter if it's hot. :) 7381d0be15f89cb5056e20e2d24faa8d6afb1573bcaOwen Anderson InfLoopBlock = BasicBlock::Create(BB->getContext(), 7391d0be15f89cb5056e20e2d24faa8d6afb1573bcaOwen Anderson "infloop", BB->getParent()); 740051a950000e21935165db56695e35bade668193bGabor Greif BranchInst::Create(InfLoopBlock, InfLoopBlock); 741542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner } 742542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner NewSI->setSuccessor(i, InfLoopBlock); 743542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner } 744fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukman 745542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner Changed = true; 746542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner } 747542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner } 748542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner return Changed; 749542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner} 750542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner 751c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen// isSafeToHoistInvoke - If we would need to insert a select that uses the 752c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen// value of this invoke (comments in HoistThenElseCodeToIf explain why we 753c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen// would need to do this), we can't hoist the invoke, as there is nowhere 754c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen// to put the select in this case. 755c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesenstatic bool isSafeToHoistInvoke(BasicBlock *BB1, BasicBlock *BB2, 756c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen Instruction *I1, Instruction *I2) { 757c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen for (succ_iterator SI = succ_begin(BB1), E = succ_end(BB1); SI != E; ++SI) { 758c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen PHINode *PN; 759c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen for (BasicBlock::iterator BBI = SI->begin(); 760c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen (PN = dyn_cast<PHINode>(BBI)); ++BBI) { 761c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen Value *BB1V = PN->getIncomingValueForBlock(BB1); 762c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen Value *BB2V = PN->getIncomingValueForBlock(BB2); 763c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen if (BB1V != BB2V && (BB1V==I1 || BB2V==I2)) { 764c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen return false; 765c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen } 766c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen } 767c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen } 768c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen return true; 769c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen} 770c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen 7716306d07aa8cf71e3c7fed7f295665f53595473ebChris Lattner/// HoistThenElseCodeToIf - Given a conditional branch that goes to BB1 and 77237dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner/// BB2, hoist any common code in the two blocks up into the branch block. The 77337dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner/// caller of this function guarantees that BI's block dominates BB1 and BB2. 77437dc938bbe556a9414d063196d367c2f75d07d95Chris Lattnerstatic bool HoistThenElseCodeToIf(BranchInst *BI) { 77537dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner // This does very trivial matching, with limited scanning, to find identical 77637dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner // instructions in the two blocks. In particular, we don't want to get into 77737dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner // O(M*N) situations here where M and N are the sizes of BB1 and BB2. As 77837dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner // such, we currently just scan for obviously identical instructions in an 77937dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner // identical order. 78037dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner BasicBlock *BB1 = BI->getSuccessor(0); // The true destination. 78137dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner BasicBlock *BB2 = BI->getSuccessor(1); // The false destination 78237dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner 78365085cf7b3470b7b087f5fd7b0497879b90b32baDevang Patel BasicBlock::iterator BB1_Itr = BB1->begin(); 78465085cf7b3470b7b087f5fd7b0497879b90b32baDevang Patel BasicBlock::iterator BB2_Itr = BB2->begin(); 78565085cf7b3470b7b087f5fd7b0497879b90b32baDevang Patel 78665085cf7b3470b7b087f5fd7b0497879b90b32baDevang Patel Instruction *I1 = BB1_Itr++, *I2 = BB2_Itr++; 78765085cf7b3470b7b087f5fd7b0497879b90b32baDevang Patel while (isa<DbgInfoIntrinsic>(I1)) 78865085cf7b3470b7b087f5fd7b0497879b90b32baDevang Patel I1 = BB1_Itr++; 78965085cf7b3470b7b087f5fd7b0497879b90b32baDevang Patel while (isa<DbgInfoIntrinsic>(I2)) 79065085cf7b3470b7b087f5fd7b0497879b90b32baDevang Patel I2 = BB2_Itr++; 791c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen if (I1->getOpcode() != I2->getOpcode() || isa<PHINode>(I1) || 79258cfa3b13752579c86cf85270d49f9ced0942f2fDan Gohman !I1->isIdenticalToWhenDefined(I2) || 793c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen (isa<InvokeInst>(I1) && !isSafeToHoistInvoke(BB1, BB2, I1, I2))) 79437dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner return false; 79537dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner 79637dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner // If we get here, we can hoist at least one instruction. 79737dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner BasicBlock *BIParent = BI->getParent(); 79837dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner 79937dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner do { 80037dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner // If we are hoisting the terminator instruction, don't move one (making a 80137dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner // broken BB), instead clone it, and remove BI. 80237dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner if (isa<TerminatorInst>(I1)) 80337dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner goto HoistTerminator; 804fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukman 80537dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner // For a normal instruction, we just move one to right before the branch, 80637dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner // then replace all uses of the other with the first. Finally, we remove 80737dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner // the now redundant second instruction. 80837dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner BIParent->getInstList().splice(BI, BB1->getInstList(), I1); 80937dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner if (!I2->use_empty()) 81037dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner I2->replaceAllUsesWith(I1); 81158cfa3b13752579c86cf85270d49f9ced0942f2fDan Gohman I1->intersectOptionalDataWith(I2); 81237dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner BB2->getInstList().erase(I2); 813fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukman 81465085cf7b3470b7b087f5fd7b0497879b90b32baDevang Patel I1 = BB1_Itr++; 81565085cf7b3470b7b087f5fd7b0497879b90b32baDevang Patel while (isa<DbgInfoIntrinsic>(I1)) 81665085cf7b3470b7b087f5fd7b0497879b90b32baDevang Patel I1 = BB1_Itr++; 81765085cf7b3470b7b087f5fd7b0497879b90b32baDevang Patel I2 = BB2_Itr++; 81865085cf7b3470b7b087f5fd7b0497879b90b32baDevang Patel while (isa<DbgInfoIntrinsic>(I2)) 81965085cf7b3470b7b087f5fd7b0497879b90b32baDevang Patel I2 = BB2_Itr++; 82058cfa3b13752579c86cf85270d49f9ced0942f2fDan Gohman } while (I1->getOpcode() == I2->getOpcode() && 82158cfa3b13752579c86cf85270d49f9ced0942f2fDan Gohman I1->isIdenticalToWhenDefined(I2)); 82237dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner 82337dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner return true; 82437dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner 82537dc938bbe556a9414d063196d367c2f75d07d95Chris LattnerHoistTerminator: 826c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen // It may not be possible to hoist an invoke. 827c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen if (isa<InvokeInst>(I1) && !isSafeToHoistInvoke(BB1, BB2, I1, I2)) 828c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen return true; 829c1f104054dda0b3946abbe3b6859e960b60168f7Dale Johannesen 83037dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner // Okay, it is safe to hoist the terminator. 8316776064d190701c5bae4d5403939eed2e480d1cdNick Lewycky Instruction *NT = I1->clone(); 83237dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner BIParent->getInstList().insert(BI, NT); 833f012705c7e4ca8cf90b6b734ce1d5355daca5ba5Benjamin Kramer if (!NT->getType()->isVoidTy()) { 83437dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner I1->replaceAllUsesWith(NT); 83537dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner I2->replaceAllUsesWith(NT); 83686cc42355593dd1689f7d58d56695c451215b02bChris Lattner NT->takeName(I1); 83737dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner } 83837dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner 83937dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner // Hoisting one of the terminators from our successor is a great thing. 84037dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner // Unfortunately, the successors of the if/else blocks may have PHI nodes in 84137dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner // them. If they do, all PHI entries for BB1/BB2 must agree for all PHI 84237dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner // nodes, so we insert select instruction to compute the final result. 84337dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner std::map<std::pair<Value*,Value*>, SelectInst*> InsertedSelects; 84437dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner for (succ_iterator SI = succ_begin(BB1), E = succ_end(BB1); SI != E; ++SI) { 84537dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner PHINode *PN; 84637dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner for (BasicBlock::iterator BBI = SI->begin(); 8470f535c6fa8b03491dc110feb65d78922ee29d1fcChris Lattner (PN = dyn_cast<PHINode>(BBI)); ++BBI) { 84837dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner Value *BB1V = PN->getIncomingValueForBlock(BB1); 84937dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner Value *BB2V = PN->getIncomingValueForBlock(BB2); 8509a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (BB1V == BB2V) continue; 8519a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner 8529a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // These values do not agree. Insert a select instruction before NT 8539a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // that determines the right value. 8549a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner SelectInst *&SI = InsertedSelects[std::make_pair(BB1V, BB2V)]; 8559a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (SI == 0) 8569a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner SI = SelectInst::Create(BI->getCondition(), BB1V, BB2V, 8579a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner BB1V->getName()+"."+BB2V->getName(), NT); 8589a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // Make the PHI node use the select for all incoming values for BB1/BB2 8599a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) 8609a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (PN->getIncomingBlock(i) == BB1 || PN->getIncomingBlock(i) == BB2) 8619a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner PN->setIncomingValue(i, SI); 86237dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner } 86337dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner } 86437dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner 86537dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner // Update any PHI nodes in our new successors. 86637dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner for (succ_iterator SI = succ_begin(BB1), E = succ_end(BB1); SI != E; ++SI) 86737dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner AddPredecessorToBlock(*SI, BIParent, BB1); 868fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukman 869080efb8cea6255b4f1f373d9cb583d6a6302106bEli Friedman EraseTerminatorInstAndDCECond(BI); 87037dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner return true; 87137dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner} 87237dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner 8734d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng/// SpeculativelyExecuteBB - Given a conditional branch that goes to BB1 8744d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng/// and an BB2 and the only successor of BB1 is BB2, hoist simple code 8754d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng/// (for now, restricted to a single instruction that's side effect free) from 8764d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng/// the BB1 into the branch block to speculatively execute it. 8774d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Chengstatic bool SpeculativelyExecuteBB(BranchInst *BI, BasicBlock *BB1) { 8784d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // Only speculatively execution a single instruction (not counting the 8794d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // terminator) for now. 88006b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel Instruction *HInst = NULL; 88106b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel Instruction *Term = BB1->getTerminator(); 88206b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel for (BasicBlock::iterator BBI = BB1->begin(), BBE = BB1->end(); 88306b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel BBI != BBE; ++BBI) { 88406b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel Instruction *I = BBI; 88506b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel // Skip debug info. 8869a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (isa<DbgInfoIntrinsic>(I)) continue; 8879a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (I == Term) break; 88806b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel 8899a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (HInst) 89006b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel return false; 8919a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner HInst = I; 89206b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel } 89306b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel if (!HInst) 89406b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel return false; 8954d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng 896797d95188d00963a835db9ad66dd3c4a54aa2fafEvan Cheng // Be conservative for now. FP select instruction can often be expensive. 897797d95188d00963a835db9ad66dd3c4a54aa2fafEvan Cheng Value *BrCond = BI->getCondition(); 8989a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (isa<FCmpInst>(BrCond)) 899797d95188d00963a835db9ad66dd3c4a54aa2fafEvan Cheng return false; 900797d95188d00963a835db9ad66dd3c4a54aa2fafEvan Cheng 9014d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // If BB1 is actually on the false edge of the conditional branch, remember 9024d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // to swap the select operands later. 9034d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng bool Invert = false; 9044d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng if (BB1 != BI->getSuccessor(0)) { 9054d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng assert(BB1 == BI->getSuccessor(1) && "No edge from 'if' block?"); 9064d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng Invert = true; 9074d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng } 9084d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng 9094d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // Turn 9104d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // BB: 9114d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // %t1 = icmp 9124d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // br i1 %t1, label %BB1, label %BB2 9134d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // BB1: 9144d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // %t3 = add %t2, c 9154d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // br label BB2 9164d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // BB2: 9174d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // => 9184d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // BB: 9194d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // %t1 = icmp 9204d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // %t4 = add %t2, c 9214d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // %t3 = select i1 %t1, %t2, %t3 92206b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel switch (HInst->getOpcode()) { 9234d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng default: return false; // Not safe / profitable to hoist. 9244d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng case Instruction::Add: 9254d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng case Instruction::Sub: 926ae3a0be92e33bc716722aa600983fc1535acb122Dan Gohman // Not worth doing for vector ops. 9271df9859c40492511b8aa4321eb76496005d3b75bDuncan Sands if (HInst->getType()->isVectorTy()) 9289dd3b610dcb17f88ed52ae03022179bf21e0e132Chris Lattner return false; 9299dd3b610dcb17f88ed52ae03022179bf21e0e132Chris Lattner break; 9304d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng case Instruction::And: 9314d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng case Instruction::Or: 9324d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng case Instruction::Xor: 9334d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng case Instruction::Shl: 9344d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng case Instruction::LShr: 9354d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng case Instruction::AShr: 9369dd3b610dcb17f88ed52ae03022179bf21e0e132Chris Lattner // Don't mess with vector operations. 9371df9859c40492511b8aa4321eb76496005d3b75bDuncan Sands if (HInst->getType()->isVectorTy()) 938e5334ea518e3dffec4037ede97433eb700fa1d26Evan Cheng return false; 9394d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng break; // These are all cheap and non-trapping instructions. 9404d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng } 9416fe73bbcf3b6c1ddfd5e70e8b5188f8df439ace6Chris Lattner 9426fe73bbcf3b6c1ddfd5e70e8b5188f8df439ace6Chris Lattner // If the instruction is obviously dead, don't try to predicate it. 94306b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel if (HInst->use_empty()) { 94406b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel HInst->eraseFromParent(); 9456fe73bbcf3b6c1ddfd5e70e8b5188f8df439ace6Chris Lattner return true; 9466fe73bbcf3b6c1ddfd5e70e8b5188f8df439ace6Chris Lattner } 9474d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng 9484d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // Can we speculatively execute the instruction? And what is the value 9494d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // if the condition is false? Consider the phi uses, if the incoming value 9504d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // from the "if" block are all the same V, then V is the value of the 9514d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // select if the condition is false. 9524d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng BasicBlock *BIParent = BI->getParent(); 9534d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng SmallVector<PHINode*, 4> PHIUses; 9544d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng Value *FalseV = NULL; 9556fe73bbcf3b6c1ddfd5e70e8b5188f8df439ace6Chris Lattner 9566fe73bbcf3b6c1ddfd5e70e8b5188f8df439ace6Chris Lattner BasicBlock *BB2 = BB1->getTerminator()->getSuccessor(0); 95706b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel for (Value::use_iterator UI = HInst->use_begin(), E = HInst->use_end(); 9584d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng UI != E; ++UI) { 9596fe73bbcf3b6c1ddfd5e70e8b5188f8df439ace6Chris Lattner // Ignore any user that is not a PHI node in BB2. These can only occur in 9606fe73bbcf3b6c1ddfd5e70e8b5188f8df439ace6Chris Lattner // unreachable blocks, because they would not be dominated by the instr. 96120361b9d4d9988d7bfa2112650971642cf81d13eGabor Greif PHINode *PN = dyn_cast<PHINode>(*UI); 9626fe73bbcf3b6c1ddfd5e70e8b5188f8df439ace6Chris Lattner if (!PN || PN->getParent() != BB2) 9636fe73bbcf3b6c1ddfd5e70e8b5188f8df439ace6Chris Lattner return false; 9644d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng PHIUses.push_back(PN); 9656fe73bbcf3b6c1ddfd5e70e8b5188f8df439ace6Chris Lattner 9664d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng Value *PHIV = PN->getIncomingValueForBlock(BIParent); 9674d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng if (!FalseV) 9684d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng FalseV = PHIV; 9694d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng else if (FalseV != PHIV) 9706fe73bbcf3b6c1ddfd5e70e8b5188f8df439ace6Chris Lattner return false; // Inconsistent value when condition is false. 9714d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng } 9726fe73bbcf3b6c1ddfd5e70e8b5188f8df439ace6Chris Lattner 9736fe73bbcf3b6c1ddfd5e70e8b5188f8df439ace6Chris Lattner assert(FalseV && "Must have at least one user, and it must be a PHI"); 9744d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng 975502a4f5162498ec420e3cb22f667808d726dd7daEvan Cheng // Do not hoist the instruction if any of its operands are defined but not 976502a4f5162498ec420e3cb22f667808d726dd7daEvan Cheng // used in this BB. The transformation will prevent the operand from 977502a4f5162498ec420e3cb22f667808d726dd7daEvan Cheng // being sunk into the use block. 97806b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel for (User::op_iterator i = HInst->op_begin(), e = HInst->op_end(); 97906b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel i != e; ++i) { 980502a4f5162498ec420e3cb22f667808d726dd7daEvan Cheng Instruction *OpI = dyn_cast<Instruction>(*i); 981502a4f5162498ec420e3cb22f667808d726dd7daEvan Cheng if (OpI && OpI->getParent() == BIParent && 982502a4f5162498ec420e3cb22f667808d726dd7daEvan Cheng !OpI->isUsedInBasicBlock(BIParent)) 983502a4f5162498ec420e3cb22f667808d726dd7daEvan Cheng return false; 984502a4f5162498ec420e3cb22f667808d726dd7daEvan Cheng } 985502a4f5162498ec420e3cb22f667808d726dd7daEvan Cheng 9863d0a9a371c0ce3a46e845a7bf1f1acb7a1cf523eDevang Patel // If we get here, we can hoist the instruction. Try to place it 987990afedb3a4b7d32832d74ad5b5863c19f909e1fDale Johannesen // before the icmp instruction preceding the conditional branch. 9883d0a9a371c0ce3a46e845a7bf1f1acb7a1cf523eDevang Patel BasicBlock::iterator InsertPos = BI; 989990afedb3a4b7d32832d74ad5b5863c19f909e1fDale Johannesen if (InsertPos != BIParent->begin()) 990990afedb3a4b7d32832d74ad5b5863c19f909e1fDale Johannesen --InsertPos; 991990afedb3a4b7d32832d74ad5b5863c19f909e1fDale Johannesen // Skip debug info between condition and branch. 992990afedb3a4b7d32832d74ad5b5863c19f909e1fDale Johannesen while (InsertPos != BIParent->begin() && isa<DbgInfoIntrinsic>(InsertPos)) 9933d0a9a371c0ce3a46e845a7bf1f1acb7a1cf523eDevang Patel --InsertPos; 99420da1f07dac4d771e55ee5c7f105ccedfa4caaaaDevang Patel if (InsertPos == BrCond && !isa<PHINode>(BrCond)) { 9953d0a9a371c0ce3a46e845a7bf1f1acb7a1cf523eDevang Patel SmallPtrSet<Instruction *, 4> BB1Insns; 9963d0a9a371c0ce3a46e845a7bf1f1acb7a1cf523eDevang Patel for(BasicBlock::iterator BB1I = BB1->begin(), BB1E = BB1->end(); 9973d0a9a371c0ce3a46e845a7bf1f1acb7a1cf523eDevang Patel BB1I != BB1E; ++BB1I) 9983d0a9a371c0ce3a46e845a7bf1f1acb7a1cf523eDevang Patel BB1Insns.insert(BB1I); 9993d0a9a371c0ce3a46e845a7bf1f1acb7a1cf523eDevang Patel for(Value::use_iterator UI = BrCond->use_begin(), UE = BrCond->use_end(); 10003d0a9a371c0ce3a46e845a7bf1f1acb7a1cf523eDevang Patel UI != UE; ++UI) { 10013d0a9a371c0ce3a46e845a7bf1f1acb7a1cf523eDevang Patel Instruction *Use = cast<Instruction>(*UI); 10029a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (!BB1Insns.count(Use)) continue; 10039a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner 10049a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // If BrCond uses the instruction that place it just before 10059a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // branch instruction. 10069a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner InsertPos = BI; 10079a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner break; 10083d0a9a371c0ce3a46e845a7bf1f1acb7a1cf523eDevang Patel } 10093d0a9a371c0ce3a46e845a7bf1f1acb7a1cf523eDevang Patel } else 10103d0a9a371c0ce3a46e845a7bf1f1acb7a1cf523eDevang Patel InsertPos = BI; 101106b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel BIParent->getInstList().splice(InsertPos, BB1->getInstList(), HInst); 10124d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng 10134d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // Create a select whose true value is the speculatively executed value and 10144d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // false value is the previously determined FalseV. 10154d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng SelectInst *SI; 10164d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng if (Invert) 101706b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel SI = SelectInst::Create(BrCond, FalseV, HInst, 101806b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel FalseV->getName() + "." + HInst->getName(), BI); 10194d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng else 102006b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel SI = SelectInst::Create(BrCond, HInst, FalseV, 102106b1e67d44a6c13f9e75fbc1ac3c7de2df4776c9Devang Patel HInst->getName() + "." + FalseV->getName(), BI); 10224d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng 10234d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // Make the PHI node use the select for all incoming values for "then" and 10244d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng // "if" blocks. 10254d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng for (unsigned i = 0, e = PHIUses.size(); i != e; ++i) { 10264d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng PHINode *PN = PHIUses[i]; 10274d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng for (unsigned j = 0, ee = PN->getNumIncomingValues(); j != ee; ++j) 10289a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (PN->getIncomingBlock(j) == BB1 || PN->getIncomingBlock(j) == BIParent) 10294d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng PN->setIncomingValue(j, SI); 10304d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng } 10314d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng 1032502a4f5162498ec420e3cb22f667808d726dd7daEvan Cheng ++NumSpeculations; 10334d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng return true; 10344d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng} 10354d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng 10362e42e36698d5a34f1952ca3389f1973a6a1166f2Chris Lattner/// BlockIsSimpleEnoughToThreadThrough - Return true if we can thread a branch 10372e42e36698d5a34f1952ca3389f1973a6a1166f2Chris Lattner/// across this block. 10382e42e36698d5a34f1952ca3389f1973a6a1166f2Chris Lattnerstatic bool BlockIsSimpleEnoughToThreadThrough(BasicBlock *BB) { 10392e42e36698d5a34f1952ca3389f1973a6a1166f2Chris Lattner BranchInst *BI = cast<BranchInst>(BB->getTerminator()); 1040e9487f0dc8c6d15cb257d5b49fa96ed436d32f5fChris Lattner unsigned Size = 0; 1041e9487f0dc8c6d15cb257d5b49fa96ed436d32f5fChris Lattner 10429200c89968e52a590ee0b96092a0a589aa138a6fDevang Patel for (BasicBlock::iterator BBI = BB->begin(); &*BBI != BI; ++BBI) { 10438483e54837ede5dd40c5561f15c6a663e2bee87cDale Johannesen if (isa<DbgInfoIntrinsic>(BBI)) 10448483e54837ede5dd40c5561f15c6a663e2bee87cDale Johannesen continue; 1045e9487f0dc8c6d15cb257d5b49fa96ed436d32f5fChris Lattner if (Size > 10) return false; // Don't clone large BB's. 10468483e54837ede5dd40c5561f15c6a663e2bee87cDale Johannesen ++Size; 10472e42e36698d5a34f1952ca3389f1973a6a1166f2Chris Lattner 10488483e54837ede5dd40c5561f15c6a663e2bee87cDale Johannesen // We can only support instructions that do not define values that are 1049e9487f0dc8c6d15cb257d5b49fa96ed436d32f5fChris Lattner // live outside of the current basic block. 1050e9487f0dc8c6d15cb257d5b49fa96ed436d32f5fChris Lattner for (Value::use_iterator UI = BBI->use_begin(), E = BBI->use_end(); 1051e9487f0dc8c6d15cb257d5b49fa96ed436d32f5fChris Lattner UI != E; ++UI) { 1052e9487f0dc8c6d15cb257d5b49fa96ed436d32f5fChris Lattner Instruction *U = cast<Instruction>(*UI); 1053e9487f0dc8c6d15cb257d5b49fa96ed436d32f5fChris Lattner if (U->getParent() != BB || isa<PHINode>(U)) return false; 1054e9487f0dc8c6d15cb257d5b49fa96ed436d32f5fChris Lattner } 10552e42e36698d5a34f1952ca3389f1973a6a1166f2Chris Lattner 10562e42e36698d5a34f1952ca3389f1973a6a1166f2Chris Lattner // Looks ok, continue checking. 10572e42e36698d5a34f1952ca3389f1973a6a1166f2Chris Lattner } 1058e9487f0dc8c6d15cb257d5b49fa96ed436d32f5fChris Lattner 10592e42e36698d5a34f1952ca3389f1973a6a1166f2Chris Lattner return true; 10602e42e36698d5a34f1952ca3389f1973a6a1166f2Chris Lattner} 10612e42e36698d5a34f1952ca3389f1973a6a1166f2Chris Lattner 1062eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner/// FoldCondBranchOnPHI - If we have a conditional branch on a PHI node value 1063eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner/// that is defined in the same block as the branch and if any PHI entries are 1064eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner/// constants, thread edges corresponding to that entry to be branches to their 1065eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner/// ultimate destination. 1066eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattnerstatic bool FoldCondBranchOnPHI(BranchInst *BI) { 1067eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner BasicBlock *BB = BI->getParent(); 1068eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner PHINode *PN = dyn_cast<PHINode>(BI->getCondition()); 10699c88d9816246d260b37cdc689f313c56aec6941eChris Lattner // NOTE: we currently cannot transform this case if the PHI node is used 10709c88d9816246d260b37cdc689f313c56aec6941eChris Lattner // outside of the block. 10712e42e36698d5a34f1952ca3389f1973a6a1166f2Chris Lattner if (!PN || PN->getParent() != BB || !PN->hasOneUse()) 10722e42e36698d5a34f1952ca3389f1973a6a1166f2Chris Lattner return false; 1073eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner 1074eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner // Degenerate case of a single entry PHI. 1075eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner if (PN->getNumIncomingValues() == 1) { 107629874e0dc6c4e55bc384611273343bb358982cc3Chris Lattner FoldSingleEntryPHINodes(PN->getParent()); 1077eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner return true; 1078eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner } 1079eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner 1080eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner // Now we know that this block has multiple preds and two succs. 10812e42e36698d5a34f1952ca3389f1973a6a1166f2Chris Lattner if (!BlockIsSimpleEnoughToThreadThrough(BB)) return false; 1082eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner 1083eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner // Okay, this is a simple enough basic block. See if any phi values are 1084eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner // constants. 10856b6b6ef1677fa71b1072c2911b4c1f9524a558c9Zhou Sheng for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) { 10869a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner ConstantInt *CB = dyn_cast<ConstantInt>(PN->getIncomingValue(i)); 10879a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (CB == 0 || !CB->getType()->isIntegerTy(1)) continue; 10889a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner 10899a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // Okay, we now know that all edges from PredBB should be revectored to 10909a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // branch to RealDest. 10919a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner BasicBlock *PredBB = PN->getIncomingBlock(i); 10929a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner BasicBlock *RealDest = BI->getSuccessor(!CB->getZExtValue()); 10939a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner 10949a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (RealDest == BB) continue; // Skip self loops. 10959a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner 10969a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // The dest block might have PHI nodes, other predecessors and other 10979a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // difficult cases. Instead of being smart about this, just insert a new 10989a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // block that jumps to the destination block, effectively splitting 10999a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // the edge we are about to create. 11009a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner BasicBlock *EdgeBB = BasicBlock::Create(BB->getContext(), 11019a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner RealDest->getName()+".critedge", 11029a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner RealDest->getParent(), RealDest); 11039a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner BranchInst::Create(RealDest, EdgeBB); 11049a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner PHINode *PN; 11059a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner for (BasicBlock::iterator BBI = RealDest->begin(); 11069a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner (PN = dyn_cast<PHINode>(BBI)); ++BBI) { 11079a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner Value *V = PN->getIncomingValueForBlock(BB); 11089a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner PN->addIncoming(V, EdgeBB); 11099a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner } 11109a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner 11119a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // BB may have instructions that are being threaded over. Clone these 11129a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // instructions into EdgeBB. We know that there will be no uses of the 11139a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // cloned instructions outside of EdgeBB. 11149a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner BasicBlock::iterator InsertPt = EdgeBB->begin(); 11159a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner DenseMap<Value*, Value*> TranslateMap; // Track translated values. 11169a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner for (BasicBlock::iterator BBI = BB->begin(); &*BBI != BI; ++BBI) { 11179a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (PHINode *PN = dyn_cast<PHINode>(BBI)) { 11189a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner TranslateMap[PN] = PN->getIncomingValueForBlock(PredBB); 11199a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner continue; 11209a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner } 11219a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // Clone the instruction. 11229a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner Instruction *N = BBI->clone(); 11239a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (BBI->hasName()) N->setName(BBI->getName()+".c"); 1124eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner 11259a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // Update operands due to translation. 11269a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner for (User::op_iterator i = N->op_begin(), e = N->op_end(); 11279a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner i != e; ++i) { 11289a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner DenseMap<Value*, Value*>::iterator PI = TranslateMap.find(*i); 11299a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (PI != TranslateMap.end()) 11309a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner *i = PI->second; 11319a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner } 1132eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner 11339a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // Check for trivial simplification. 11349a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (Constant *C = ConstantFoldInstruction(N)) { 11359a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner TranslateMap[BBI] = C; 11369a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner delete N; // Constant folded away, don't need actual inst 11379a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner } else { 11389a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // Insert the new instruction into its new home. 11399a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner EdgeBB->getInstList().insert(InsertPt, N); 11409a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (!BBI->use_empty()) 11419a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner TranslateMap[BBI] = N; 1142e9487f0dc8c6d15cb257d5b49fa96ed436d32f5fChris Lattner } 11439a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner } 1144e9487f0dc8c6d15cb257d5b49fa96ed436d32f5fChris Lattner 11459a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // Loop over all of the edges from PredBB to BB, changing them to branch 11469a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // to EdgeBB instead. 11479a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner TerminatorInst *PredBBTI = PredBB->getTerminator(); 11489a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner for (unsigned i = 0, e = PredBBTI->getNumSuccessors(); i != e; ++i) 11499a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (PredBBTI->getSuccessor(i) == BB) { 11509a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner BB->removePredecessor(PredBB); 11519a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner PredBBTI->setSuccessor(i, EdgeBB); 1152e9487f0dc8c6d15cb257d5b49fa96ed436d32f5fChris Lattner } 11539a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner 11549a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // Recurse, simplifying any other constants. 11559a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner return FoldCondBranchOnPHI(BI) | true; 11566b6b6ef1677fa71b1072c2911b4c1f9524a558c9Zhou Sheng } 1157eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner 1158eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner return false; 1159eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner} 1160eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner 1161f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner/// FoldTwoEntryPHINode - Given a BB that starts with the specified two-entry 1162f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner/// PHI node, see if we can eliminate it. 1163f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattnerstatic bool FoldTwoEntryPHINode(PHINode *PN) { 1164f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // Ok, this is a two entry PHI node. Check to see if this is a simple "if 1165f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // statement", which has a very simple dominance structure. Basically, we 1166f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // are trying to find the condition that is being branched on, which 1167f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // subsequently causes this merge to happen. We really want control 1168f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // dependence information for this check, but simplifycfg can't keep it up 1169f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // to date, and this catches most of the cases we care about anyway. 1170f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // 1171f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner BasicBlock *BB = PN->getParent(); 1172f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner BasicBlock *IfTrue, *IfFalse; 1173f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner Value *IfCond = GetIfCondition(BB, IfTrue, IfFalse); 1174f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner if (!IfCond) return false; 1175f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner 1176822a87998387a4c52be5162523f09cc8e5e5afb7Chris Lattner // Okay, we found that we can merge this two-entry phi node into a select. 1177822a87998387a4c52be5162523f09cc8e5e5afb7Chris Lattner // Doing so would require us to fold *all* two entry phi nodes in this block. 1178822a87998387a4c52be5162523f09cc8e5e5afb7Chris Lattner // At some point this becomes non-profitable (particularly if the target 1179822a87998387a4c52be5162523f09cc8e5e5afb7Chris Lattner // doesn't support cmov's). Only do this transformation if there are two or 1180822a87998387a4c52be5162523f09cc8e5e5afb7Chris Lattner // fewer PHI nodes in this block. 1181822a87998387a4c52be5162523f09cc8e5e5afb7Chris Lattner unsigned NumPhis = 0; 1182822a87998387a4c52be5162523f09cc8e5e5afb7Chris Lattner for (BasicBlock::iterator I = BB->begin(); isa<PHINode>(I); ++NumPhis, ++I) 1183822a87998387a4c52be5162523f09cc8e5e5afb7Chris Lattner if (NumPhis > 2) 1184822a87998387a4c52be5162523f09cc8e5e5afb7Chris Lattner return false; 1185822a87998387a4c52be5162523f09cc8e5e5afb7Chris Lattner 118689d6fd36a26fdf068ceea90422dc2897e89700b5David Greene DEBUG(dbgs() << "FOUND IF CONDITION! " << *IfCond << " T: " 1187ce63ffb52f249b62cdf2d250c128007b13f27e71Daniel Dunbar << IfTrue->getName() << " F: " << IfFalse->getName() << "\n"); 1188f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner 1189f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // Loop over the PHI's seeing if we can promote them all to select 1190f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // instructions. While we are at it, keep track of the instructions 1191f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // that need to be moved to the dominating block. 1192f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner std::set<Instruction*> AggressiveInsts; 1193f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner 1194f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner BasicBlock::iterator AfterPHIIt = BB->begin(); 1195f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner while (isa<PHINode>(AfterPHIIt)) { 1196f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner PHINode *PN = cast<PHINode>(AfterPHIIt++); 1197f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner if (PN->getIncomingValue(0) == PN->getIncomingValue(1)) { 1198f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner if (PN->getIncomingValue(0) != PN) 1199f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner PN->replaceAllUsesWith(PN->getIncomingValue(0)); 1200f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner else 12019e9a0d5fc26878e51a58a8b57900fcbf952c2691Owen Anderson PN->replaceAllUsesWith(UndefValue::get(PN->getType())); 1202f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner } else if (!DominatesMergePoint(PN->getIncomingValue(0), BB, 1203f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner &AggressiveInsts) || 1204f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner !DominatesMergePoint(PN->getIncomingValue(1), BB, 1205f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner &AggressiveInsts)) { 1206055dc102e97316d423bd068f8b228d27fb93c90aChris Lattner return false; 1207f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner } 1208f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner } 1209f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner 1210f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // If we all PHI nodes are promotable, check to make sure that all 1211f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // instructions in the predecessor blocks can be promoted as well. If 1212f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // not, we won't be able to get rid of the control flow, so it's not 1213f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // worth promoting to select instructions. 1214f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner BasicBlock *DomBlock = 0, *IfBlock1 = 0, *IfBlock2 = 0; 1215f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner PN = cast<PHINode>(BB->begin()); 1216f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner BasicBlock *Pred = PN->getIncomingBlock(0); 1217f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner if (cast<BranchInst>(Pred->getTerminator())->isUnconditional()) { 1218f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner IfBlock1 = Pred; 1219f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner DomBlock = *pred_begin(Pred); 1220f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner for (BasicBlock::iterator I = Pred->begin(); 1221f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner !isa<TerminatorInst>(I); ++I) 1222383d7ed9158576aef5cde872548225a17e3c0155Devang Patel if (!AggressiveInsts.count(I) && !isa<DbgInfoIntrinsic>(I)) { 1223f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // This is not an aggressive instruction that we can promote. 1224f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // Because of this, we won't be able to get rid of the control 1225f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // flow, so the xform is not worth it. 1226f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner return false; 1227f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner } 1228f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner } 1229f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner 1230f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner Pred = PN->getIncomingBlock(1); 1231f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner if (cast<BranchInst>(Pred->getTerminator())->isUnconditional()) { 1232f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner IfBlock2 = Pred; 1233f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner DomBlock = *pred_begin(Pred); 1234f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner for (BasicBlock::iterator I = Pred->begin(); 1235f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner !isa<TerminatorInst>(I); ++I) 1236383d7ed9158576aef5cde872548225a17e3c0155Devang Patel if (!AggressiveInsts.count(I) && !isa<DbgInfoIntrinsic>(I)) { 1237f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // This is not an aggressive instruction that we can promote. 1238f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // Because of this, we won't be able to get rid of the control 1239f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // flow, so the xform is not worth it. 1240f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner return false; 1241f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner } 1242f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner } 1243f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner 1244f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // If we can still promote the PHI nodes after this gauntlet of tests, 1245f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // do all of the PHI's now. 1246f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner 1247f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // Move all 'aggressive' instructions, which are defined in the 1248f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // conditional parts of the if's up to the dominating block. 12499a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (IfBlock1) 1250f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner DomBlock->getInstList().splice(DomBlock->getTerminator(), 12519a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner IfBlock1->getInstList(), IfBlock1->begin(), 1252f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner IfBlock1->getTerminator()); 12539a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (IfBlock2) 1254f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner DomBlock->getInstList().splice(DomBlock->getTerminator(), 12559a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner IfBlock2->getInstList(), IfBlock2->begin(), 1256f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner IfBlock2->getTerminator()); 1257f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner 1258f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner while (PHINode *PN = dyn_cast<PHINode>(BB->begin())) { 1259f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner // Change the PHI node into a select instruction. 12609a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner Value *TrueVal = PN->getIncomingValue(PN->getIncomingBlock(0) == IfFalse); 12619a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner Value *FalseVal = PN->getIncomingValue(PN->getIncomingBlock(0) == IfTrue); 1262f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner 1263051a950000e21935165db56695e35bade668193bGabor Greif Value *NV = SelectInst::Create(IfCond, TrueVal, FalseVal, "", AfterPHIIt); 126486cc42355593dd1689f7d58d56695c451215b02bChris Lattner PN->replaceAllUsesWith(NV); 126586cc42355593dd1689f7d58d56695c451215b02bChris Lattner NV->takeName(PN); 126686cc42355593dd1689f7d58d56695c451215b02bChris Lattner 1267f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner BB->getInstList().erase(PN); 1268f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner } 1269f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner return true; 1270f58c1a578e63265abf46c395953fe8aa3f73e37cChris Lattner} 1271eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner 1272c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner/// SimplifyCondBranchToTwoReturns - If we found a conditional branch that goes 1273c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner/// to two returning blocks, try to merge them together into one return, 1274c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner/// introducing a select if the return values disagree. 1275c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattnerstatic bool SimplifyCondBranchToTwoReturns(BranchInst *BI) { 1276c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner assert(BI->isConditional() && "Must be a conditional branch"); 1277c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner BasicBlock *TrueSucc = BI->getSuccessor(0); 1278c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner BasicBlock *FalseSucc = BI->getSuccessor(1); 1279c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner ReturnInst *TrueRet = cast<ReturnInst>(TrueSucc->getTerminator()); 1280c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner ReturnInst *FalseRet = cast<ReturnInst>(FalseSucc->getTerminator()); 1281c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner 1282c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner // Check to ensure both blocks are empty (just a return) or optionally empty 1283c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner // with PHI nodes. If there are other instructions, merging would cause extra 1284c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner // computation on one path or the other. 12859a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (!TrueSucc->getFirstNonPHIOrDbg()->isTerminator()) 12862cc86a1de1cf598be384836f19d1ef1892fb50fcDevang Patel return false; 12879a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (!FalseSucc->getFirstNonPHIOrDbg()->isTerminator()) 12882cc86a1de1cf598be384836f19d1ef1892fb50fcDevang Patel return false; 1289c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner 1290c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner // Okay, we found a branch that is going to two return nodes. If 1291c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner // there is no return value for this function, just change the 1292c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner // branch into a return. 1293c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner if (FalseRet->getNumOperands() == 0) { 1294c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner TrueSucc->removePredecessor(BI->getParent()); 1295c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner FalseSucc->removePredecessor(BI->getParent()); 12961d0be15f89cb5056e20e2d24faa8d6afb1573bcaOwen Anderson ReturnInst::Create(BI->getContext(), 0, BI); 1297080efb8cea6255b4f1f373d9cb583d6a6302106bEli Friedman EraseTerminatorInstAndDCECond(BI); 1298c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner return true; 1299c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner } 1300c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner 1301fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman // Otherwise, figure out what the true and false return values are 1302fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman // so we can insert a new select instruction. 1303fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman Value *TrueValue = TrueRet->getReturnValue(); 1304fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman Value *FalseValue = FalseRet->getReturnValue(); 1305fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman 1306fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman // Unwrap any PHI nodes in the return blocks. 1307fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman if (PHINode *TVPN = dyn_cast_or_null<PHINode>(TrueValue)) 1308fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman if (TVPN->getParent() == TrueSucc) 1309fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman TrueValue = TVPN->getIncomingValueForBlock(BI->getParent()); 1310fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman if (PHINode *FVPN = dyn_cast_or_null<PHINode>(FalseValue)) 1311fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman if (FVPN->getParent() == FalseSucc) 1312fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman FalseValue = FVPN->getIncomingValueForBlock(BI->getParent()); 1313fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman 1314fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman // In order for this transformation to be safe, we must be able to 1315fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman // unconditionally execute both operands to the return. This is 1316fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman // normally the case, but we could have a potentially-trapping 1317fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman // constant expression that prevents this transformation from being 1318fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman // safe. 1319fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman if (ConstantExpr *TCV = dyn_cast_or_null<ConstantExpr>(TrueValue)) 1320fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman if (TCV->canTrap()) 1321fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman return false; 1322fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman if (ConstantExpr *FCV = dyn_cast_or_null<ConstantExpr>(FalseValue)) 1323fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman if (FCV->canTrap()) 1324fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman return false; 1325c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner 1326c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner // Okay, we collected all the mapped values and checked them for sanity, and 1327c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner // defined to really do this transformation. First, update the CFG. 1328c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner TrueSucc->removePredecessor(BI->getParent()); 1329c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner FalseSucc->removePredecessor(BI->getParent()); 1330c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner 1331c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner // Insert select instructions where needed. 1332c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner Value *BrCond = BI->getCondition(); 1333fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman if (TrueValue) { 1334c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner // Insert a select if the results differ. 1335fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman if (TrueValue == FalseValue || isa<UndefValue>(FalseValue)) { 1336fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman } else if (isa<UndefValue>(TrueValue)) { 1337fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman TrueValue = FalseValue; 1338fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman } else { 1339fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman TrueValue = SelectInst::Create(BrCond, TrueValue, 1340fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman FalseValue, "retval", BI); 1341c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner } 1342c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner } 1343c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner 1344fc74abfba5128544a750fce22fdf13eb0403e3ceDan Gohman Value *RI = !TrueValue ? 13451d0be15f89cb5056e20e2d24faa8d6afb1573bcaOwen Anderson ReturnInst::Create(BI->getContext(), BI) : 13461d0be15f89cb5056e20e2d24faa8d6afb1573bcaOwen Anderson ReturnInst::Create(BI->getContext(), TrueValue, BI); 1347e317bcc74c1f317f913e9b05db385901cfc54d0bDaniel Dunbar (void) RI; 1348c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner 134989d6fd36a26fdf068ceea90422dc2897e89700b5David Greene DEBUG(dbgs() << "\nCHANGING BRANCH TO TWO RETURNS INTO SELECT:" 1350bdff548e4dd577a72094d57b282de4e765643b96Chris Lattner << "\n " << *BI << "NewRet = " << *RI 1351bdff548e4dd577a72094d57b282de4e765643b96Chris Lattner << "TRUEBLOCK: " << *TrueSucc << "FALSEBLOCK: "<< *FalseSucc); 1352c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner 1353080efb8cea6255b4f1f373d9cb583d6a6302106bEli Friedman EraseTerminatorInstAndDCECond(BI); 1354080efb8cea6255b4f1f373d9cb583d6a6302106bEli Friedman 1355c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner return true; 1356c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner} 1357c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner 13581347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner/// FoldBranchToCommonDest - If this basic block is ONLY a setcc and a branch, 13591347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner/// and if a predecessor branches to us and one of our successors, fold the 13601347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner/// setcc into the predecessor and use logical operations to pick the right 13611347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner/// destination. 13624b35f83b91a1a313f0730c600e5178aaf7df98d6Dan Gohmanbool llvm::FoldBranchToCommonDest(BranchInst *BI) { 1363093a4385027235459ab6972b2e2fdc79061773cfChris Lattner BasicBlock *BB = BI->getParent(); 13641347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner Instruction *Cond = dyn_cast<Instruction>(BI->getCondition()); 1365e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson if (Cond == 0 || (!isa<CmpInst>(Cond) && !isa<BinaryOperator>(Cond)) || 1366e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson Cond->getParent() != BB || !Cond->hasOneUse()) 1367e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson return false; 1368093a4385027235459ab6972b2e2fdc79061773cfChris Lattner 13691347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner // Only allow this if the condition is a simple instruction that can be 13701347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner // executed unconditionally. It must be in the same block as the branch, and 13711347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner // must be at the front of the block. 1372d0a203d76f4ef77ae1c392e8e73e2f05b676a5f2Devang Patel BasicBlock::iterator FrontIt = BB->front(); 1373d0a203d76f4ef77ae1c392e8e73e2f05b676a5f2Devang Patel // Ignore dbg intrinsics. 1374d0a203d76f4ef77ae1c392e8e73e2f05b676a5f2Devang Patel while(isa<DbgInfoIntrinsic>(FrontIt)) 1375d0a203d76f4ef77ae1c392e8e73e2f05b676a5f2Devang Patel ++FrontIt; 1376e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson 1377e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson // Allow a single instruction to be hoisted in addition to the compare 1378e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson // that feeds the branch. We later ensure that any values that _it_ uses 1379e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson // were also live in the predecessor, so that we don't unnecessarily create 1380e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson // register pressure or inhibit out-of-order execution. 1381e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson Instruction *BonusInst = 0; 1382e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson if (&*FrontIt != Cond && 13832722dfa75dbf4436197f6fcf9d8cb2391975f1a1Owen Anderson FrontIt->hasOneUse() && *FrontIt->use_begin() == Cond && 13842722dfa75dbf4436197f6fcf9d8cb2391975f1a1Owen Anderson FrontIt->isSafeToSpeculativelyExecute()) { 1385e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson BonusInst = &*FrontIt; 1386e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson ++FrontIt; 1387d0a203d76f4ef77ae1c392e8e73e2f05b676a5f2Devang Patel } 13886ff645bf0fcfc0c62e9d9126e1243ec8bf10abbcChris Lattner 1389e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson // Only a single bonus inst is allowed. 1390e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson if (&*FrontIt != Cond) 1391e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson return false; 1392e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson 13931347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner // Make sure the instruction after the condition is the cond branch. 13941347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner BasicBlock::iterator CondIt = Cond; ++CondIt; 1395d0a203d76f4ef77ae1c392e8e73e2f05b676a5f2Devang Patel // Ingore dbg intrinsics. 1396d0a203d76f4ef77ae1c392e8e73e2f05b676a5f2Devang Patel while(isa<DbgInfoIntrinsic>(CondIt)) 1397d0a203d76f4ef77ae1c392e8e73e2f05b676a5f2Devang Patel ++CondIt; 1398d0a203d76f4ef77ae1c392e8e73e2f05b676a5f2Devang Patel if (&*CondIt != BI) { 1399d0a203d76f4ef77ae1c392e8e73e2f05b676a5f2Devang Patel assert (!isa<DbgInfoIntrinsic>(CondIt) && "Hey do not forget debug info!"); 14001347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner return false; 1401d0a203d76f4ef77ae1c392e8e73e2f05b676a5f2Devang Patel } 14026ff645bf0fcfc0c62e9d9126e1243ec8bf10abbcChris Lattner 14036ff645bf0fcfc0c62e9d9126e1243ec8bf10abbcChris Lattner // Cond is known to be a compare or binary operator. Check to make sure that 14046ff645bf0fcfc0c62e9d9126e1243ec8bf10abbcChris Lattner // neither operand is a potentially-trapping constant expression. 14056ff645bf0fcfc0c62e9d9126e1243ec8bf10abbcChris Lattner if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Cond->getOperand(0))) 14066ff645bf0fcfc0c62e9d9126e1243ec8bf10abbcChris Lattner if (CE->canTrap()) 14076ff645bf0fcfc0c62e9d9126e1243ec8bf10abbcChris Lattner return false; 14086ff645bf0fcfc0c62e9d9126e1243ec8bf10abbcChris Lattner if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Cond->getOperand(1))) 14096ff645bf0fcfc0c62e9d9126e1243ec8bf10abbcChris Lattner if (CE->canTrap()) 14106ff645bf0fcfc0c62e9d9126e1243ec8bf10abbcChris Lattner return false; 14116ff645bf0fcfc0c62e9d9126e1243ec8bf10abbcChris Lattner 14121347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner 14131347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner // Finally, don't infinitely unroll conditional loops. 14141347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner BasicBlock *TrueDest = BI->getSuccessor(0); 14151347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner BasicBlock *FalseDest = BI->getSuccessor(1); 14161347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner if (TrueDest == BB || FalseDest == BB) 14171347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner return false; 14181347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner 14191347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI) { 14201347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner BasicBlock *PredBlock = *PI; 14211347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner BranchInst *PBI = dyn_cast<BranchInst>(PredBlock->getTerminator()); 14226ff645bf0fcfc0c62e9d9126e1243ec8bf10abbcChris Lattner 1423093a4385027235459ab6972b2e2fdc79061773cfChris Lattner // Check that we have two conditional branches. If there is a PHI node in 1424093a4385027235459ab6972b2e2fdc79061773cfChris Lattner // the common successor, verify that the same value flows in from both 1425093a4385027235459ab6972b2e2fdc79061773cfChris Lattner // blocks. 14261347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner if (PBI == 0 || PBI->isUnconditional() || 14271347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner !SafeToMergeTerminators(BI, PBI)) 14281347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner continue; 14291347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner 1430e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson // Ensure that any values used in the bonus instruction are also used 1431e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson // by the terminator of the predecessor. This means that those values 1432e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson // must already have been resolved, so we won't be inhibiting the 1433e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson // out-of-order core by speculating them earlier. 1434e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson if (BonusInst) { 1435e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson // Collect the values used by the bonus inst 1436e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson SmallPtrSet<Value*, 4> UsedValues; 1437e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson for (Instruction::op_iterator OI = BonusInst->op_begin(), 1438e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson OE = BonusInst->op_end(); OI != OE; ++OI) { 1439e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson Value* V = *OI; 1440e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson if (!isa<Constant>(V)) 1441e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson UsedValues.insert(V); 1442e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson } 1443e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson 1444e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson SmallVector<std::pair<Value*, unsigned>, 4> Worklist; 1445e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson Worklist.push_back(std::make_pair(PBI->getOperand(0), 0)); 1446e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson 1447e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson // Walk up to four levels back up the use-def chain of the predecessor's 1448e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson // terminator to see if all those values were used. The choice of four 1449e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson // levels is arbitrary, to provide a compile-time-cost bound. 1450e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson while (!Worklist.empty()) { 1451e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson std::pair<Value*, unsigned> Pair = Worklist.back(); 1452e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson Worklist.pop_back(); 1453e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson 1454e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson if (Pair.second >= 4) continue; 1455e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson UsedValues.erase(Pair.first); 1456e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson if (UsedValues.empty()) break; 1457e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson 1458e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson if (Instruction* I = dyn_cast<Instruction>(Pair.first)) { 1459e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson for (Instruction::op_iterator OI = I->op_begin(), OE = I->op_end(); 1460e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson OI != OE; ++OI) 1461e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson Worklist.push_back(std::make_pair(OI->get(), Pair.second+1)); 1462e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson } 1463e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson } 1464e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson 1465e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson if (!UsedValues.empty()) return false; 1466e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson } 1467e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson 14683698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner Instruction::BinaryOps Opc; 14693698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner bool InvertPredCond = false; 14703698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner 14713698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner if (PBI->getSuccessor(0) == TrueDest) 14723698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner Opc = Instruction::Or; 14733698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner else if (PBI->getSuccessor(1) == FalseDest) 14743698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner Opc = Instruction::And; 14753698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner else if (PBI->getSuccessor(0) == FalseDest) 14763698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner Opc = Instruction::And, InvertPredCond = true; 14773698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner else if (PBI->getSuccessor(1) == TrueDest) 14783698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner Opc = Instruction::Or, InvertPredCond = true; 14793698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner else 14803698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner continue; 14813698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner 148289d6fd36a26fdf068ceea90422dc2897e89700b5David Greene DEBUG(dbgs() << "FOLDING BRANCH TO COMMON DEST:\n" << *PBI << *BB); 14836ff645bf0fcfc0c62e9d9126e1243ec8bf10abbcChris Lattner 14843698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner // If we need to invert the condition in the pred block to match, do so now. 14853698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner if (InvertPredCond) { 14861347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner Value *NewCond = 14874ae5126d041768ab9665cf2f11c024becd76c41fDan Gohman BinaryOperator::CreateNot(PBI->getCondition(), 14883698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner PBI->getCondition()->getName()+".not", PBI); 14891347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner PBI->setCondition(NewCond); 14901347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner BasicBlock *OldTrue = PBI->getSuccessor(0); 14911347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner BasicBlock *OldFalse = PBI->getSuccessor(1); 14921347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner PBI->setSuccessor(0, OldFalse); 14931347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner PBI->setSuccessor(1, OldTrue); 14941347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner } 149570087f31f154156bcb494dd0cf3b7d74c0c8b528Chris Lattner 1496e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson // If we have a bonus inst, clone it into the predecessor block. 1497e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson Instruction *NewBonus = 0; 1498e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson if (BonusInst) { 1499e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson NewBonus = BonusInst->clone(); 1500e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson PredBlock->getInstList().insert(PBI, NewBonus); 1501e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson NewBonus->takeName(BonusInst); 1502e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson BonusInst->setName(BonusInst->getName()+".old"); 1503e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson } 1504e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson 15053698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner // Clone Cond into the predecessor basic block, and or/and the 15063698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner // two conditions together. 15076776064d190701c5bae4d5403939eed2e480d1cdNick Lewycky Instruction *New = Cond->clone(); 1508e84178a0bd3a218238b15ef646f2e740f3a48037Owen Anderson if (BonusInst) New->replaceUsesOfWith(BonusInst, NewBonus); 15093698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner PredBlock->getInstList().insert(PBI, New); 15103698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner New->takeName(Cond); 15113698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner Cond->setName(New->getName()+".old"); 151270087f31f154156bcb494dd0cf3b7d74c0c8b528Chris Lattner 15133698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner Value *NewCond = BinaryOperator::Create(Opc, PBI->getCondition(), 15143698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner New, "or.cond", PBI); 15153698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner PBI->setCondition(NewCond); 15163698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner if (PBI->getSuccessor(0) == BB) { 15173698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner AddPredecessorToBlock(TrueDest, PredBlock, BB); 15183698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner PBI->setSuccessor(0, TrueDest); 15193698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner } 15203698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner if (PBI->getSuccessor(1) == BB) { 15213698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner AddPredecessorToBlock(FalseDest, PredBlock, BB); 15223698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner PBI->setSuccessor(1, FalseDest); 15231347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner } 15243698909623f994826b6a11fc4ea37e4b425a9589Chris Lattner return true; 15251347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner } 15261347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner return false; 15271347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner} 15281347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner 1529867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner/// SimplifyCondBranchToCondBranch - If we have a conditional branch as a 1530867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner/// predecessor of another block, this function tries to simplify it. We know 1531867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner/// that PBI and BI are both conditional branches, and BI is in one of the 1532867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner/// successor blocks of PBI - PBI branches to BI. 1533867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattnerstatic bool SimplifyCondBranchToCondBranch(BranchInst *PBI, BranchInst *BI) { 1534867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner assert(PBI->isConditional() && BI->isConditional()); 1535867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner BasicBlock *BB = BI->getParent(); 15364ae5126d041768ab9665cf2f11c024becd76c41fDan Gohman 1537867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner // If this block ends with a branch instruction, and if there is a 1538867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner // predecessor that ends on a branch of the same condition, make 1539867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner // this conditional branch redundant. 1540867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner if (PBI->getCondition() == BI->getCondition() && 1541867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner PBI->getSuccessor(0) != PBI->getSuccessor(1)) { 1542867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner // Okay, the outcome of this conditional branch is statically 1543867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner // knowable. If this block had a single pred, handle specially. 1544867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner if (BB->getSinglePredecessor()) { 1545867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner // Turn this into a branch on constant. 1546867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner bool CondIsTrue = PBI->getSuccessor(0) == BB; 15471d0be15f89cb5056e20e2d24faa8d6afb1573bcaOwen Anderson BI->setCondition(ConstantInt::get(Type::getInt1Ty(BB->getContext()), 15481d0be15f89cb5056e20e2d24faa8d6afb1573bcaOwen Anderson CondIsTrue)); 1549867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner return true; // Nuke the branch on constant. 1550867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner } 1551867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner 1552867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner // Otherwise, if there are multiple predecessors, insert a PHI that merges 1553867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner // in the constant and simplify the block result. Subsequent passes of 1554867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner // simplifycfg will thread the block. 1555867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner if (BlockIsSimpleEnoughToThreadThrough(BB)) { 15561d0be15f89cb5056e20e2d24faa8d6afb1573bcaOwen Anderson PHINode *NewPN = PHINode::Create(Type::getInt1Ty(BB->getContext()), 1557867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner BI->getCondition()->getName() + ".pr", 1558867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner BB->begin()); 1559eb388af89f15ee3de6f53359473e1a54418a667fChris Lattner // Okay, we're going to insert the PHI node. Since PBI is not the only 1560eb388af89f15ee3de6f53359473e1a54418a667fChris Lattner // predecessor, compute the PHI'd conditional value for all of the preds. 1561eb388af89f15ee3de6f53359473e1a54418a667fChris Lattner // Any predecessor where the condition is not computable we keep symbolic. 1562625398343e2673a0c4bb5228fc88f71fe4e1c629Gabor Greif for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI) { 1563625398343e2673a0c4bb5228fc88f71fe4e1c629Gabor Greif BasicBlock *P = *PI; 1564625398343e2673a0c4bb5228fc88f71fe4e1c629Gabor Greif if ((PBI = dyn_cast<BranchInst>(P->getTerminator())) && 1565867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner PBI != BI && PBI->isConditional() && 1566867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner PBI->getCondition() == BI->getCondition() && 1567867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner PBI->getSuccessor(0) != PBI->getSuccessor(1)) { 1568867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner bool CondIsTrue = PBI->getSuccessor(0) == BB; 15691d0be15f89cb5056e20e2d24faa8d6afb1573bcaOwen Anderson NewPN->addIncoming(ConstantInt::get(Type::getInt1Ty(BB->getContext()), 1570625398343e2673a0c4bb5228fc88f71fe4e1c629Gabor Greif CondIsTrue), P); 1571867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner } else { 1572625398343e2673a0c4bb5228fc88f71fe4e1c629Gabor Greif NewPN->addIncoming(BI->getCondition(), P); 1573867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner } 1574625398343e2673a0c4bb5228fc88f71fe4e1c629Gabor Greif } 1575867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner 1576867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner BI->setCondition(NewPN); 1577867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner return true; 1578867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner } 1579867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner } 1580867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner 1581867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner // If this is a conditional branch in an empty block, and if any 1582867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner // predecessors is a conditional branch to one of our destinations, 1583867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner // fold the conditions into logical ops and one cond br. 1584a8d57fe96bb870e4f69c6b522a78936d1495d0d2Zhou Sheng BasicBlock::iterator BBI = BB->begin(); 1585a8d57fe96bb870e4f69c6b522a78936d1495d0d2Zhou Sheng // Ignore dbg intrinsics. 1586a8d57fe96bb870e4f69c6b522a78936d1495d0d2Zhou Sheng while (isa<DbgInfoIntrinsic>(BBI)) 1587a8d57fe96bb870e4f69c6b522a78936d1495d0d2Zhou Sheng ++BBI; 1588a8d57fe96bb870e4f69c6b522a78936d1495d0d2Zhou Sheng if (&*BBI != BI) 1589b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner return false; 159063bf29b5b1c741038d6d502d62721cac0d2760b4Chris Lattner 159163bf29b5b1c741038d6d502d62721cac0d2760b4Chris Lattner 159263bf29b5b1c741038d6d502d62721cac0d2760b4Chris Lattner if (ConstantExpr *CE = dyn_cast<ConstantExpr>(BI->getCondition())) 159363bf29b5b1c741038d6d502d62721cac0d2760b4Chris Lattner if (CE->canTrap()) 159463bf29b5b1c741038d6d502d62721cac0d2760b4Chris Lattner return false; 1595b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner 1596b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner int PBIOp, BIOp; 1597b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner if (PBI->getSuccessor(0) == BI->getSuccessor(0)) 1598b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner PBIOp = BIOp = 0; 1599b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner else if (PBI->getSuccessor(0) == BI->getSuccessor(1)) 1600b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner PBIOp = 0, BIOp = 1; 1601b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner else if (PBI->getSuccessor(1) == BI->getSuccessor(0)) 1602b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner PBIOp = 1, BIOp = 0; 1603b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner else if (PBI->getSuccessor(1) == BI->getSuccessor(1)) 1604b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner PBIOp = BIOp = 1; 1605b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner else 1606b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner return false; 1607867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner 1608b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // Check to make sure that the other destination of this branch 1609b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // isn't BB itself. If so, this is an infinite loop that will 1610b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // keep getting unwound. 1611b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner if (PBI->getSuccessor(PBIOp) == BB) 1612b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner return false; 1613867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner 1614b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // Do not perform this transformation if it would require 1615b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // insertion of a large number of select instructions. For targets 1616b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // without predication/cmovs, this is a big pessimization. 1617b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner BasicBlock *CommonDest = PBI->getSuccessor(PBIOp); 1618867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner 1619b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner unsigned NumPhis = 0; 1620b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner for (BasicBlock::iterator II = CommonDest->begin(); 1621b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner isa<PHINode>(II); ++II, ++NumPhis) 1622b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner if (NumPhis > 2) // Disable this xform. 1623b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner return false; 1624867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner 1625b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // Finally, if everything is ok, fold the branches to logical ops. 1626b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner BasicBlock *OtherDest = BI->getSuccessor(BIOp ^ 1); 1627b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner 162889d6fd36a26fdf068ceea90422dc2897e89700b5David Greene DEBUG(dbgs() << "FOLDING BRs:" << *PBI->getParent() 1629bdff548e4dd577a72094d57b282de4e765643b96Chris Lattner << "AND: " << *BI->getParent()); 1630b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner 1631093a4385027235459ab6972b2e2fdc79061773cfChris Lattner 1632093a4385027235459ab6972b2e2fdc79061773cfChris Lattner // If OtherDest *is* BB, then BB is a basic block with a single conditional 1633093a4385027235459ab6972b2e2fdc79061773cfChris Lattner // branch in it, where one edge (OtherDest) goes back to itself but the other 1634093a4385027235459ab6972b2e2fdc79061773cfChris Lattner // exits. We don't *know* that the program avoids the infinite loop 1635093a4385027235459ab6972b2e2fdc79061773cfChris Lattner // (even though that seems likely). If we do this xform naively, we'll end up 1636093a4385027235459ab6972b2e2fdc79061773cfChris Lattner // recursively unpeeling the loop. Since we know that (after the xform is 1637093a4385027235459ab6972b2e2fdc79061773cfChris Lattner // done) that the block *is* infinite if reached, we just make it an obviously 1638093a4385027235459ab6972b2e2fdc79061773cfChris Lattner // infinite loop with no cond branch. 1639093a4385027235459ab6972b2e2fdc79061773cfChris Lattner if (OtherDest == BB) { 1640093a4385027235459ab6972b2e2fdc79061773cfChris Lattner // Insert it at the end of the function, because it's either code, 1641093a4385027235459ab6972b2e2fdc79061773cfChris Lattner // or it won't matter if it's hot. :) 16421d0be15f89cb5056e20e2d24faa8d6afb1573bcaOwen Anderson BasicBlock *InfLoopBlock = BasicBlock::Create(BB->getContext(), 16431d0be15f89cb5056e20e2d24faa8d6afb1573bcaOwen Anderson "infloop", BB->getParent()); 1644093a4385027235459ab6972b2e2fdc79061773cfChris Lattner BranchInst::Create(InfLoopBlock, InfLoopBlock); 1645093a4385027235459ab6972b2e2fdc79061773cfChris Lattner OtherDest = InfLoopBlock; 1646093a4385027235459ab6972b2e2fdc79061773cfChris Lattner } 1647093a4385027235459ab6972b2e2fdc79061773cfChris Lattner 164889d6fd36a26fdf068ceea90422dc2897e89700b5David Greene DEBUG(dbgs() << *PBI->getParent()->getParent()); 1649b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner 1650b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // BI may have other predecessors. Because of this, we leave 1651b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // it alone, but modify PBI. 1652b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner 1653b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // Make sure we get to CommonDest on True&True directions. 1654b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner Value *PBICond = PBI->getCondition(); 1655b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner if (PBIOp) 16564ae5126d041768ab9665cf2f11c024becd76c41fDan Gohman PBICond = BinaryOperator::CreateNot(PBICond, 1657b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner PBICond->getName()+".not", 1658b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner PBI); 1659b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner Value *BICond = BI->getCondition(); 1660b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner if (BIOp) 16614ae5126d041768ab9665cf2f11c024becd76c41fDan Gohman BICond = BinaryOperator::CreateNot(BICond, 1662b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner BICond->getName()+".not", 1663b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner PBI); 1664b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // Merge the conditions. 1665b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner Value *Cond = BinaryOperator::CreateOr(PBICond, BICond, "brmerge", PBI); 1666b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner 1667b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // Modify PBI to branch on the new condition to the new dests. 1668b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner PBI->setCondition(Cond); 1669b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner PBI->setSuccessor(0, CommonDest); 1670b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner PBI->setSuccessor(1, OtherDest); 1671b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner 1672b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // OtherDest may have phi nodes. If so, add an entry from PBI's 1673b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // block that are identical to the entries for BI's block. 1674b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner PHINode *PN; 1675b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner for (BasicBlock::iterator II = OtherDest->begin(); 1676b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner (PN = dyn_cast<PHINode>(II)); ++II) { 1677b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner Value *V = PN->getIncomingValueForBlock(BB); 1678b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner PN->addIncoming(V, PBI->getParent()); 1679b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner } 1680b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner 1681b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // We know that the CommonDest already had an edge from PBI to 1682b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // it. If it has PHIs though, the PHIs may have different 1683b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // entries for BB and PBI's BB. If so, insert a select to make 1684b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // them agree. 1685b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner for (BasicBlock::iterator II = CommonDest->begin(); 1686b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner (PN = dyn_cast<PHINode>(II)); ++II) { 1687b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner Value *BIV = PN->getIncomingValueForBlock(BB); 1688b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner unsigned PBBIdx = PN->getBasicBlockIndex(PBI->getParent()); 1689b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner Value *PBIV = PN->getIncomingValue(PBBIdx); 1690b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner if (BIV != PBIV) { 1691b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // Insert a select in PBI to pick the right value. 1692b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner Value *NV = SelectInst::Create(PBICond, PBIV, BIV, 1693b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner PBIV->getName()+".mux", PBI); 1694b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner PN->setIncomingValue(PBBIdx, NV); 1695867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner } 1696867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner } 1697b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner 169889d6fd36a26fdf068ceea90422dc2897e89700b5David Greene DEBUG(dbgs() << "INTO: " << *PBI->getParent()); 169989d6fd36a26fdf068ceea90422dc2897e89700b5David Greene DEBUG(dbgs() << *PBI->getParent()->getParent()); 1700b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner 1701b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // This basic block is probably dead. We know it has at least 1702b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner // one fewer predecessor. 1703b824512b8d733ccdfb1b1a2e8a6950605acf1c52Chris Lattner return true; 1704867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner} 1705867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner 17067ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel// SimplifyIndirectBrOnSelect - Replaces 17077ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel// (indirectbr (select cond, blockaddress(@fn, BlockA), 17087ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel// blockaddress(@fn, BlockB))) 17097ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel// with 17107ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel// (br cond, BlockA, BlockB). 17117ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommelstatic bool SimplifyIndirectBrOnSelect(IndirectBrInst *IBI, SelectInst *SI) { 17127ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel // Check that both operands of the select are block addresses. 17137ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel BlockAddress *TBA = dyn_cast<BlockAddress>(SI->getTrueValue()); 17147ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel BlockAddress *FBA = dyn_cast<BlockAddress>(SI->getFalseValue()); 17157ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel if (!TBA || !FBA) 17167ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel return false; 17177ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel 17187ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel // Extract the actual blocks. 17197ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel BasicBlock *TrueBB = TBA->getBasicBlock(); 17207ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel BasicBlock *FalseBB = FBA->getBasicBlock(); 17217ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel 17227ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel // Remove any superfluous successor edges from the CFG. 17237ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel // First, figure out which successors to preserve. 17247ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel // If TrueBB and FalseBB are equal, only try to preserve one copy of that 17257ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel // successor. 17267ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel BasicBlock *KeepEdge1 = TrueBB; 17277ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel BasicBlock *KeepEdge2 = TrueBB != FalseBB ? FalseBB : 0; 17287ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel 17297ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel // Then remove the rest. 17307ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel for (unsigned I = 0, E = IBI->getNumSuccessors(); I != E; ++I) { 17317ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel BasicBlock *Succ = IBI->getSuccessor(I); 17327ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel // Make sure only to keep exactly one copy of each edge. 17337ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel if (Succ == KeepEdge1) 17347ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel KeepEdge1 = 0; 17357ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel else if (Succ == KeepEdge2) 17367ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel KeepEdge2 = 0; 17377ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel else 17387ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel Succ->removePredecessor(IBI->getParent()); 17397ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel } 17407ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel 17417ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel // Insert an appropriate new terminator. 17427ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel if ((KeepEdge1 == 0) && (KeepEdge2 == 0)) { 17437ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel if (TrueBB == FalseBB) 17447ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel // We were only looking for one successor, and it was present. 17457ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel // Create an unconditional branch to it. 17467ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel BranchInst::Create(TrueBB, IBI); 17477ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel else 17487ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel // We found both of the successors we were looking for. 17497ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel // Create a conditional branch sharing the condition of the select. 17507ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel BranchInst::Create(TrueBB, FalseBB, SI->getCondition(), IBI); 17517ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel } else if (KeepEdge1 && (KeepEdge2 || TrueBB == FalseBB)) { 17527ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel // Neither of the selected blocks were successors, so this 17537ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel // indirectbr must be unreachable. 17547ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel new UnreachableInst(IBI->getContext(), IBI); 17557ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel } else { 17567ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel // One of the selected values was a successor, but the other wasn't. 17577ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel // Insert an unconditional branch to the one that was found; 17587ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel // the edge to the one that wasn't must be unreachable. 17597ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel if (KeepEdge1 == 0) 17607ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel // Only TrueBB was found. 17617ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel BranchInst::Create(TrueBB, IBI); 17627ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel else 17637ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel // Only FalseBB was found. 17647ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel BranchInst::Create(FalseBB, IBI); 17657ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel } 17667ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel 17677ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel EraseTerminatorInstAndDCECond(IBI); 17687ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel return true; 17697ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel} 17707ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel 177161c77449c772427a0d2559fca500debd93c7f97cChris Lattner/// TryToSimplifyUncondBranchWithICmpInIt - This is called when we find an icmp 177261c77449c772427a0d2559fca500debd93c7f97cChris Lattner/// instruction (a seteq/setne with a constant) as the only instruction in a 177361c77449c772427a0d2559fca500debd93c7f97cChris Lattner/// block that ends with an uncond branch. We are looking for a very specific 177461c77449c772427a0d2559fca500debd93c7f97cChris Lattner/// pattern that occurs when "A == 1 || A == 2 || A == 3" gets simplified. In 177561c77449c772427a0d2559fca500debd93c7f97cChris Lattner/// this case, we merge the first two "or's of icmp" into a switch, but then the 177661c77449c772427a0d2559fca500debd93c7f97cChris Lattner/// default value goes to an uncond block with a seteq in it, we get something 177761c77449c772427a0d2559fca500debd93c7f97cChris Lattner/// like: 177861c77449c772427a0d2559fca500debd93c7f97cChris Lattner/// 177961c77449c772427a0d2559fca500debd93c7f97cChris Lattner/// switch i8 %A, label %DEFAULT [ i8 1, label %end i8 2, label %end ] 178061c77449c772427a0d2559fca500debd93c7f97cChris Lattner/// DEFAULT: 178161c77449c772427a0d2559fca500debd93c7f97cChris Lattner/// %tmp = icmp eq i8 %A, 92 178261c77449c772427a0d2559fca500debd93c7f97cChris Lattner/// br label %end 178361c77449c772427a0d2559fca500debd93c7f97cChris Lattner/// end: 178461c77449c772427a0d2559fca500debd93c7f97cChris Lattner/// ... = phi i1 [ true, %entry ], [ %tmp, %DEFAULT ], [ true, %entry ] 178561c77449c772427a0d2559fca500debd93c7f97cChris Lattner/// 178661c77449c772427a0d2559fca500debd93c7f97cChris Lattner/// We prefer to split the edge to 'end' so that there is a true/false entry to 178761c77449c772427a0d2559fca500debd93c7f97cChris Lattner/// the PHI, merging the third icmp into the switch. 178861c77449c772427a0d2559fca500debd93c7f97cChris Lattnerstatic bool TryToSimplifyUncondBranchWithICmpInIt(ICmpInst *ICI) { 178961c77449c772427a0d2559fca500debd93c7f97cChris Lattner BasicBlock *BB = ICI->getParent(); 179061c77449c772427a0d2559fca500debd93c7f97cChris Lattner // If the block has any PHIs in it or the icmp has multiple uses, it is too 179161c77449c772427a0d2559fca500debd93c7f97cChris Lattner // complex. 179261c77449c772427a0d2559fca500debd93c7f97cChris Lattner if (isa<PHINode>(BB->begin()) || !ICI->hasOneUse()) return false; 179361c77449c772427a0d2559fca500debd93c7f97cChris Lattner 179461c77449c772427a0d2559fca500debd93c7f97cChris Lattner Value *V = ICI->getOperand(0); 179561c77449c772427a0d2559fca500debd93c7f97cChris Lattner ConstantInt *Cst = cast<ConstantInt>(ICI->getOperand(1)); 179661c77449c772427a0d2559fca500debd93c7f97cChris Lattner 179761c77449c772427a0d2559fca500debd93c7f97cChris Lattner // The pattern we're looking for is where our only predecessor is a switch on 179861c77449c772427a0d2559fca500debd93c7f97cChris Lattner // 'V' and this block is the default case for the switch. In this case we can 179961c77449c772427a0d2559fca500debd93c7f97cChris Lattner // fold the compared value into the switch to simplify things. 180061c77449c772427a0d2559fca500debd93c7f97cChris Lattner BasicBlock *Pred = BB->getSinglePredecessor(); 180161c77449c772427a0d2559fca500debd93c7f97cChris Lattner if (Pred == 0 || !isa<SwitchInst>(Pred->getTerminator())) return false; 180261c77449c772427a0d2559fca500debd93c7f97cChris Lattner 180361c77449c772427a0d2559fca500debd93c7f97cChris Lattner SwitchInst *SI = cast<SwitchInst>(Pred->getTerminator()); 180461c77449c772427a0d2559fca500debd93c7f97cChris Lattner if (SI->getCondition() != V) 180561c77449c772427a0d2559fca500debd93c7f97cChris Lattner return false; 180661c77449c772427a0d2559fca500debd93c7f97cChris Lattner 180761c77449c772427a0d2559fca500debd93c7f97cChris Lattner // If BB is reachable on a non-default case, then we simply know the value of 180861c77449c772427a0d2559fca500debd93c7f97cChris Lattner // V in this block. Substitute it and constant fold the icmp instruction 180961c77449c772427a0d2559fca500debd93c7f97cChris Lattner // away. 181061c77449c772427a0d2559fca500debd93c7f97cChris Lattner if (SI->getDefaultDest() != BB) { 181161c77449c772427a0d2559fca500debd93c7f97cChris Lattner ConstantInt *VVal = SI->findCaseDest(BB); 181261c77449c772427a0d2559fca500debd93c7f97cChris Lattner assert(VVal && "Should have a unique destination value"); 181361c77449c772427a0d2559fca500debd93c7f97cChris Lattner ICI->setOperand(0, VVal); 181461c77449c772427a0d2559fca500debd93c7f97cChris Lattner 181561c77449c772427a0d2559fca500debd93c7f97cChris Lattner if (Constant *C = ConstantFoldInstruction(ICI)) { 181661c77449c772427a0d2559fca500debd93c7f97cChris Lattner ICI->replaceAllUsesWith(C); 181761c77449c772427a0d2559fca500debd93c7f97cChris Lattner ICI->eraseFromParent(); 181861c77449c772427a0d2559fca500debd93c7f97cChris Lattner } 181961c77449c772427a0d2559fca500debd93c7f97cChris Lattner // BB is now empty, so it is likely to simplify away. 182061c77449c772427a0d2559fca500debd93c7f97cChris Lattner return SimplifyCFG(BB) | true; 182161c77449c772427a0d2559fca500debd93c7f97cChris Lattner } 182261c77449c772427a0d2559fca500debd93c7f97cChris Lattner 1823abf706703fcbcde8fdc69b1bbdfb34e874813107Chris Lattner // Ok, the block is reachable from the default dest. If the constant we're 1824abf706703fcbcde8fdc69b1bbdfb34e874813107Chris Lattner // comparing exists in one of the other edges, then we can constant fold ICI 1825abf706703fcbcde8fdc69b1bbdfb34e874813107Chris Lattner // and zap it. 1826abf706703fcbcde8fdc69b1bbdfb34e874813107Chris Lattner if (SI->findCaseValue(Cst) != 0) { 1827abf706703fcbcde8fdc69b1bbdfb34e874813107Chris Lattner Value *V; 1828abf706703fcbcde8fdc69b1bbdfb34e874813107Chris Lattner if (ICI->getPredicate() == ICmpInst::ICMP_EQ) 1829abf706703fcbcde8fdc69b1bbdfb34e874813107Chris Lattner V = ConstantInt::getFalse(BB->getContext()); 1830abf706703fcbcde8fdc69b1bbdfb34e874813107Chris Lattner else 1831abf706703fcbcde8fdc69b1bbdfb34e874813107Chris Lattner V = ConstantInt::getTrue(BB->getContext()); 1832abf706703fcbcde8fdc69b1bbdfb34e874813107Chris Lattner 1833abf706703fcbcde8fdc69b1bbdfb34e874813107Chris Lattner ICI->replaceAllUsesWith(V); 1834abf706703fcbcde8fdc69b1bbdfb34e874813107Chris Lattner ICI->eraseFromParent(); 1835abf706703fcbcde8fdc69b1bbdfb34e874813107Chris Lattner // BB is now empty, so it is likely to simplify away. 1836abf706703fcbcde8fdc69b1bbdfb34e874813107Chris Lattner return SimplifyCFG(BB) | true; 1837abf706703fcbcde8fdc69b1bbdfb34e874813107Chris Lattner } 1838abf706703fcbcde8fdc69b1bbdfb34e874813107Chris Lattner 183961c77449c772427a0d2559fca500debd93c7f97cChris Lattner // The use of the icmp has to be in the 'end' block, by the only PHI node in 184061c77449c772427a0d2559fca500debd93c7f97cChris Lattner // the block. 184161c77449c772427a0d2559fca500debd93c7f97cChris Lattner BasicBlock *SuccBlock = BB->getTerminator()->getSuccessor(0); 184261c77449c772427a0d2559fca500debd93c7f97cChris Lattner PHINode *PHIUse = dyn_cast<PHINode>(ICI->use_back()); 184361c77449c772427a0d2559fca500debd93c7f97cChris Lattner if (PHIUse == 0 || PHIUse != &SuccBlock->front() || 184461c77449c772427a0d2559fca500debd93c7f97cChris Lattner isa<PHINode>(++BasicBlock::iterator(PHIUse))) 184561c77449c772427a0d2559fca500debd93c7f97cChris Lattner return false; 184661c77449c772427a0d2559fca500debd93c7f97cChris Lattner 184761c77449c772427a0d2559fca500debd93c7f97cChris Lattner // If the icmp is a SETEQ, then the default dest gets false, the new edge gets 184861c77449c772427a0d2559fca500debd93c7f97cChris Lattner // true in the PHI. 184961c77449c772427a0d2559fca500debd93c7f97cChris Lattner Constant *DefaultCst = ConstantInt::getTrue(BB->getContext()); 185061c77449c772427a0d2559fca500debd93c7f97cChris Lattner Constant *NewCst = ConstantInt::getFalse(BB->getContext()); 185161c77449c772427a0d2559fca500debd93c7f97cChris Lattner 185261c77449c772427a0d2559fca500debd93c7f97cChris Lattner if (ICI->getPredicate() == ICmpInst::ICMP_EQ) 185361c77449c772427a0d2559fca500debd93c7f97cChris Lattner std::swap(DefaultCst, NewCst); 185461c77449c772427a0d2559fca500debd93c7f97cChris Lattner 185561c77449c772427a0d2559fca500debd93c7f97cChris Lattner // Replace ICI (which is used by the PHI for the default value) with true or 185661c77449c772427a0d2559fca500debd93c7f97cChris Lattner // false depending on if it is EQ or NE. 185761c77449c772427a0d2559fca500debd93c7f97cChris Lattner ICI->replaceAllUsesWith(DefaultCst); 185861c77449c772427a0d2559fca500debd93c7f97cChris Lattner ICI->eraseFromParent(); 185961c77449c772427a0d2559fca500debd93c7f97cChris Lattner 186061c77449c772427a0d2559fca500debd93c7f97cChris Lattner // Okay, the switch goes to this block on a default value. Add an edge from 186161c77449c772427a0d2559fca500debd93c7f97cChris Lattner // the switch to the merge point on the compared value. 186261c77449c772427a0d2559fca500debd93c7f97cChris Lattner BasicBlock *NewBB = BasicBlock::Create(BB->getContext(), "switch.edge", 186361c77449c772427a0d2559fca500debd93c7f97cChris Lattner BB->getParent(), BB); 186461c77449c772427a0d2559fca500debd93c7f97cChris Lattner SI->addCase(Cst, NewBB); 186561c77449c772427a0d2559fca500debd93c7f97cChris Lattner 186661c77449c772427a0d2559fca500debd93c7f97cChris Lattner // NewBB branches to the phi block, add the uncond branch and the phi entry. 186761c77449c772427a0d2559fca500debd93c7f97cChris Lattner BranchInst::Create(SuccBlock, NewBB); 186861c77449c772427a0d2559fca500debd93c7f97cChris Lattner PHIUse->addIncoming(NewCst, NewBB); 186961c77449c772427a0d2559fca500debd93c7f97cChris Lattner return true; 187061c77449c772427a0d2559fca500debd93c7f97cChris Lattner} 187161c77449c772427a0d2559fca500debd93c7f97cChris Lattner 187258e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesenbool SimplifyCFGOpt::run(BasicBlock *BB) { 1873dc3602bf0d27aac80e08ef8823967850acd05a14Chris Lattner bool Changed = false; 18745f28475b30cf09e946bf6cb7c8de6d597a41610eDuncan Sands Function *Fn = BB->getParent(); 187501d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner 18765f28475b30cf09e946bf6cb7c8de6d597a41610eDuncan Sands assert(BB && Fn && "Block not embedded in function!"); 187701d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner assert(BB->getTerminator() && "Degenerate basic block encountered!"); 187801d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner 1879e2c6d131d12c779a410740e0a90545def75e0f48Dan Gohman // Remove basic blocks that have no predecessors (except the entry block)... 1880e2c6d131d12c779a410740e0a90545def75e0f48Dan Gohman // or that just have themself as a predecessor. These are unreachable. 18815f28475b30cf09e946bf6cb7c8de6d597a41610eDuncan Sands if ((pred_begin(BB) == pred_end(BB) && BB != &Fn->getEntryBlock()) || 1882e2c6d131d12c779a410740e0a90545def75e0f48Dan Gohman BB->getSinglePredecessor() == BB) { 188389d6fd36a26fdf068ceea90422dc2897e89700b5David Greene DEBUG(dbgs() << "Removing BB: \n" << *BB); 188471af9b07a58a264064813545889cf6473ce23de6Chris Lattner DeleteDeadBlock(BB); 188501d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner return true; 188601d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner } 188701d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner 1888694e37f08a7c09ccc24642532106295cf7b3a1e3Chris Lattner // Check to see if we can constant propagate this terminator instruction 1889694e37f08a7c09ccc24642532106295cf7b3a1e3Chris Lattner // away... 1890dc3602bf0d27aac80e08ef8823967850acd05a14Chris Lattner Changed |= ConstantFoldTerminator(BB); 1891694e37f08a7c09ccc24642532106295cf7b3a1e3Chris Lattner 18922c63566e406974caa70ee27f35af28112e80f951Dan Gohman // Check for and eliminate duplicate PHI nodes in this block. 18932c63566e406974caa70ee27f35af28112e80f951Dan Gohman Changed |= EliminateDuplicatePHINodes(BB); 18942c63566e406974caa70ee27f35af28112e80f951Dan Gohman 1895882d87d168374ce790621e9ad4d7304b9dff0d78Dan Gohman // If there is a trivial two-entry PHI node in this basic block, and we can 1896882d87d168374ce790621e9ad4d7304b9dff0d78Dan Gohman // eliminate it, do so now. 1897882d87d168374ce790621e9ad4d7304b9dff0d78Dan Gohman if (PHINode *PN = dyn_cast<PHINode>(BB->begin())) 1898882d87d168374ce790621e9ad4d7304b9dff0d78Dan Gohman if (PN->getNumIncomingValues() == 2) 1899882d87d168374ce790621e9ad4d7304b9dff0d78Dan Gohman Changed |= FoldTwoEntryPHINode(PN); 1900882d87d168374ce790621e9ad4d7304b9dff0d78Dan Gohman 190119831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner // If this is a returning block with only PHI nodes in it, fold the return 190219831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner // instruction into any unconditional branch predecessors. 1903147af6b75f2e9a71baf46a12cf1312f627f1590bChris Lattner // 1904147af6b75f2e9a71baf46a12cf1312f627f1590bChris Lattner // If any predecessor is a conditional branch that just selects among 1905147af6b75f2e9a71baf46a12cf1312f627f1590bChris Lattner // different return values, fold the replace the branch/return with a select 1906147af6b75f2e9a71baf46a12cf1312f627f1590bChris Lattner // and return. 190719831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner if (ReturnInst *RI = dyn_cast<ReturnInst>(BB->getTerminator())) { 19089a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (BB->getFirstNonPHIOrDbg()->isTerminator()) { 1909147af6b75f2e9a71baf46a12cf1312f627f1590bChris Lattner // Find predecessors that end with branches. 19108244243a31d636ce8838a81d4c402274fd391d2bChris Lattner SmallVector<BasicBlock*, 8> UncondBranchPreds; 19118244243a31d636ce8838a81d4c402274fd391d2bChris Lattner SmallVector<BranchInst*, 8> CondBranchPreds; 191219831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI) { 191358969354238655a87677c7fd439d3e3d134fc89fGabor Greif BasicBlock *P = *PI; 191458969354238655a87677c7fd439d3e3d134fc89fGabor Greif TerminatorInst *PTI = P->getTerminator(); 191507e6e56f57e8781a8d7bc601cc9034a3741d84c2Anton Korobeynikov if (BranchInst *BI = dyn_cast<BranchInst>(PTI)) { 191619831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner if (BI->isUnconditional()) 191758969354238655a87677c7fd439d3e3d134fc89fGabor Greif UncondBranchPreds.push_back(P); 1918147af6b75f2e9a71baf46a12cf1312f627f1590bChris Lattner else 1919147af6b75f2e9a71baf46a12cf1312f627f1590bChris Lattner CondBranchPreds.push_back(BI); 192007e6e56f57e8781a8d7bc601cc9034a3741d84c2Anton Korobeynikov } 192119831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner } 1922fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukman 192319831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner // If we found some, do the transformation! 19241c85503e381423f20769582b6ab169bce9cfe2a2Bill Wendling if (!UncondBranchPreds.empty()) { 192519831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner while (!UncondBranchPreds.empty()) { 1926e9d87f49063cb1bd213d8e9c339b9b63393cc2d9Dan Gohman BasicBlock *Pred = UncondBranchPreds.pop_back_val(); 192789d6fd36a26fdf068ceea90422dc2897e89700b5David Greene DEBUG(dbgs() << "FOLDING: " << *BB 1928bdff548e4dd577a72094d57b282de4e765643b96Chris Lattner << "INTO UNCOND BRANCH PRED: " << *Pred); 192919831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner Instruction *UncondBranch = Pred->getTerminator(); 193019831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner // Clone the return and add it to the end of the predecessor. 19316776064d190701c5bae4d5403939eed2e480d1cdNick Lewycky Instruction *NewRet = RI->clone(); 193219831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner Pred->getInstList().push_back(NewRet); 193319831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner 193419831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner // If the return instruction returns a value, and if the value was a 193519831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner // PHI node in "BB", propagate the right value into the return. 1936f7ea3638e0f85a9793e7c9f081ed6ddb1ebb832eGabor Greif for (User::op_iterator i = NewRet->op_begin(), e = NewRet->op_end(); 1937f7ea3638e0f85a9793e7c9f081ed6ddb1ebb832eGabor Greif i != e; ++i) 1938f7ea3638e0f85a9793e7c9f081ed6ddb1ebb832eGabor Greif if (PHINode *PN = dyn_cast<PHINode>(*i)) 193919831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner if (PN->getParent() == BB) 1940f7ea3638e0f85a9793e7c9f081ed6ddb1ebb832eGabor Greif *i = PN->getIncomingValueForBlock(Pred); 1941ffba5821eee7b7a6139f9dfb06b8d306bf344a9dChris Lattner 194219831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner // Update any PHI nodes in the returning block to realize that we no 194319831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner // longer branch to them. 194419831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner BB->removePredecessor(Pred); 194519831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner Pred->getInstList().erase(UncondBranch); 194619831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner } 194719831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner 194819831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner // If we eliminated all predecessors of the block, delete the block now. 194919831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner if (pred_begin(BB) == pred_end(BB)) 195019831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner // We know there are no successors, so just nuke the block. 19515f28475b30cf09e946bf6cb7c8de6d597a41610eDuncan Sands Fn->getBasicBlockList().erase(BB); 195219831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner 195319831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner return true; 195419831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner } 1955147af6b75f2e9a71baf46a12cf1312f627f1590bChris Lattner 1956147af6b75f2e9a71baf46a12cf1312f627f1590bChris Lattner // Check out all of the conditional branches going to this return 1957147af6b75f2e9a71baf46a12cf1312f627f1590bChris Lattner // instruction. If any of them just select between returns, change the 1958147af6b75f2e9a71baf46a12cf1312f627f1590bChris Lattner // branch itself into a select/return pair. 1959147af6b75f2e9a71baf46a12cf1312f627f1590bChris Lattner while (!CondBranchPreds.empty()) { 1960e9d87f49063cb1bd213d8e9c339b9b63393cc2d9Dan Gohman BranchInst *BI = CondBranchPreds.pop_back_val(); 1961147af6b75f2e9a71baf46a12cf1312f627f1590bChris Lattner 1962147af6b75f2e9a71baf46a12cf1312f627f1590bChris Lattner // Check to see if the non-BB successor is also a return block. 1963c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner if (isa<ReturnInst>(BI->getSuccessor(0)->getTerminator()) && 1964c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner isa<ReturnInst>(BI->getSuccessor(1)->getTerminator()) && 1965c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner SimplifyCondBranchToTwoReturns(BI)) 1966c9e495c534b95a72502d1840293e66fa2e2d6882Chris Lattner return true; 1967147af6b75f2e9a71baf46a12cf1312f627f1590bChris Lattner } 196819831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner } 19693ed469ccd7b028a030b550d84b7336d146f5d8faReid Spencer } else if (isa<UnwindInst>(BB->begin())) { 1970e14ea0804afba2ac5824507571a220d05b0aa21dChris Lattner // Check to see if the first instruction in this block is just an unwind. 1971e14ea0804afba2ac5824507571a220d05b0aa21dChris Lattner // If so, replace any invoke instructions which use this as an exception 197211f15dbb287b5d9aa63913f84ce931569a5ebdf3Chris Lattner // destination with call instructions. 1973e14ea0804afba2ac5824507571a220d05b0aa21dChris Lattner // 19748244243a31d636ce8838a81d4c402274fd391d2bChris Lattner SmallVector<BasicBlock*, 8> Preds(pred_begin(BB), pred_end(BB)); 1975e14ea0804afba2ac5824507571a220d05b0aa21dChris Lattner while (!Preds.empty()) { 1976e14ea0804afba2ac5824507571a220d05b0aa21dChris Lattner BasicBlock *Pred = Preds.back(); 19779a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner InvokeInst *II = dyn_cast<InvokeInst>(Pred->getTerminator()); 19789a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (II && II->getUnwindDest() == BB) { 19799a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // Insert a new branch instruction before the invoke, because this 19809a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // is now a fall through. 19819a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner BranchInst *BI = BranchInst::Create(II->getNormalDest(), II); 19829a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner Pred->getInstList().remove(II); // Take out of symbol table 19839a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner 19849a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // Insert the call now. 19859a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner SmallVector<Value*,8> Args(II->op_begin(), II->op_end()-3); 19869a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner CallInst *CI = CallInst::Create(II->getCalledValue(), 19879a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner Args.begin(), Args.end(), 19889a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner II->getName(), BI); 19899a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner CI->setCallingConv(II->getCallingConv()); 19909a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner CI->setAttributes(II->getAttributes()); 19919a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // If the invoke produced a value, the Call now does instead. 19929a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner II->replaceAllUsesWith(CI); 19939a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner delete II; 19949a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner Changed = true; 19959a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner } 1996fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukman 1997e14ea0804afba2ac5824507571a220d05b0aa21dChris Lattner Preds.pop_back(); 1998e14ea0804afba2ac5824507571a220d05b0aa21dChris Lattner } 19998e509dd5e81e92a466580ab4022994079952cca9Chris Lattner 20005f28475b30cf09e946bf6cb7c8de6d597a41610eDuncan Sands // If this block is now dead (and isn't the entry block), remove it. 20015f28475b30cf09e946bf6cb7c8de6d597a41610eDuncan Sands if (pred_begin(BB) == pred_end(BB) && BB != &Fn->getEntryBlock()) { 20028e509dd5e81e92a466580ab4022994079952cca9Chris Lattner // We know there are no successors, so just nuke the block. 20035f28475b30cf09e946bf6cb7c8de6d597a41610eDuncan Sands Fn->getBasicBlockList().erase(BB); 20048e509dd5e81e92a466580ab4022994079952cca9Chris Lattner return true; 20058e509dd5e81e92a466580ab4022994079952cca9Chris Lattner } 20068e509dd5e81e92a466580ab4022994079952cca9Chris Lattner 2007623369ac5669a3667a94a3cbba342dea78845615Chris Lattner } else if (SwitchInst *SI = dyn_cast<SwitchInst>(BB->getTerminator())) { 2008623369ac5669a3667a94a3cbba342dea78845615Chris Lattner if (isValueEqualityComparison(SI)) { 2009623369ac5669a3667a94a3cbba342dea78845615Chris Lattner // If we only have one predecessor, and if it is a branch on this value, 2010623369ac5669a3667a94a3cbba342dea78845615Chris Lattner // see if that predecessor totally determines the outcome of this switch. 2011623369ac5669a3667a94a3cbba342dea78845615Chris Lattner if (BasicBlock *OnlyPred = BB->getSinglePredecessor()) 2012623369ac5669a3667a94a3cbba342dea78845615Chris Lattner if (SimplifyEqualityComparisonWithOnlyPredecessor(SI, OnlyPred)) 2013623369ac5669a3667a94a3cbba342dea78845615Chris Lattner return SimplifyCFG(BB) || 1; 2014623369ac5669a3667a94a3cbba342dea78845615Chris Lattner 2015623369ac5669a3667a94a3cbba342dea78845615Chris Lattner // If the block only contains the switch, see if we can fold the block 2016623369ac5669a3667a94a3cbba342dea78845615Chris Lattner // away into any preds. 20179a7c743fc0d45e4f2331c4092d3f29bf18351e6fZhou Sheng BasicBlock::iterator BBI = BB->begin(); 20189a7c743fc0d45e4f2331c4092d3f29bf18351e6fZhou Sheng // Ignore dbg intrinsics. 20199a7c743fc0d45e4f2331c4092d3f29bf18351e6fZhou Sheng while (isa<DbgInfoIntrinsic>(BBI)) 20209a7c743fc0d45e4f2331c4092d3f29bf18351e6fZhou Sheng ++BBI; 20219a7c743fc0d45e4f2331c4092d3f29bf18351e6fZhou Sheng if (SI == &*BBI) 2022623369ac5669a3667a94a3cbba342dea78845615Chris Lattner if (FoldValueComparisonIntoPredecessors(SI)) 2023623369ac5669a3667a94a3cbba342dea78845615Chris Lattner return SimplifyCFG(BB) || 1; 2024623369ac5669a3667a94a3cbba342dea78845615Chris Lattner } 2025542f149f00afaf1125b8f2040cad4fe05ed24c3aChris Lattner } else if (BranchInst *BI = dyn_cast<BranchInst>(BB->getTerminator())) { 20267e66348cba4384d07b37ad1c186e67ba6d26babdChris Lattner if (BI->isUnconditional()) { 2027dcb54ce3da15ba41adeee020288e6c62cfae8c42Chris Lattner // If the Terminator is the only non-phi instruction, simplify the block. 202861c77449c772427a0d2559fca500debd93c7f97cChris Lattner BasicBlock::iterator I = BB->getFirstNonPHIOrDbg(); 2029dcb54ce3da15ba41adeee020288e6c62cfae8c42Chris Lattner if (I->isTerminator() && BB != &Fn->getEntryBlock() && 2030dcb54ce3da15ba41adeee020288e6c62cfae8c42Chris Lattner TryToSimplifyUncondBranchFromEmptyBlock(BB)) 2031dcb54ce3da15ba41adeee020288e6c62cfae8c42Chris Lattner return true; 20327e66348cba4384d07b37ad1c186e67ba6d26babdChris Lattner 203361c77449c772427a0d2559fca500debd93c7f97cChris Lattner // If the only instruction in the block is a seteq/setne comparison 203461c77449c772427a0d2559fca500debd93c7f97cChris Lattner // against a constant, try to simplify the block. 203561c77449c772427a0d2559fca500debd93c7f97cChris Lattner if (ICmpInst *ICI = dyn_cast<ICmpInst>(I)) 203661c77449c772427a0d2559fca500debd93c7f97cChris Lattner if (ICI->isEquality() && isa<ConstantInt>(ICI->getOperand(1))) { 203761c77449c772427a0d2559fca500debd93c7f97cChris Lattner for (++I; isa<DbgInfoIntrinsic>(I); ++I) 203861c77449c772427a0d2559fca500debd93c7f97cChris Lattner ; 203961c77449c772427a0d2559fca500debd93c7f97cChris Lattner if (I->isTerminator() && 204061c77449c772427a0d2559fca500debd93c7f97cChris Lattner TryToSimplifyUncondBranchWithICmpInIt(ICI)) 204161c77449c772427a0d2559fca500debd93c7f97cChris Lattner return true; 204261c77449c772427a0d2559fca500debd93c7f97cChris Lattner } 204361c77449c772427a0d2559fca500debd93c7f97cChris Lattner 20447e66348cba4384d07b37ad1c186e67ba6d26babdChris Lattner } else { // Conditional branch 20453ed469ccd7b028a030b550d84b7336d146f5d8faReid Spencer if (isValueEqualityComparison(BI)) { 2046623369ac5669a3667a94a3cbba342dea78845615Chris Lattner // If we only have one predecessor, and if it is a branch on this value, 2047623369ac5669a3667a94a3cbba342dea78845615Chris Lattner // see if that predecessor totally determines the outcome of this 2048623369ac5669a3667a94a3cbba342dea78845615Chris Lattner // switch. 2049623369ac5669a3667a94a3cbba342dea78845615Chris Lattner if (BasicBlock *OnlyPred = BB->getSinglePredecessor()) 2050623369ac5669a3667a94a3cbba342dea78845615Chris Lattner if (SimplifyEqualityComparisonWithOnlyPredecessor(BI, OnlyPred)) 2051c69b4a5b8ba83863f9d24f7ca2aa02395addb868Bill Wendling return SimplifyCFG(BB) | true; 2052623369ac5669a3667a94a3cbba342dea78845615Chris Lattner 2053e67fa05036f634a4ec1e0893033c89250eb58954Chris Lattner // This block must be empty, except for the setcond inst, if it exists. 2054556b20ab46520ac53bb689d3c70160bc9d496a3fDevang Patel // Ignore dbg intrinsics. 2055e67fa05036f634a4ec1e0893033c89250eb58954Chris Lattner BasicBlock::iterator I = BB->begin(); 2056d0a203d76f4ef77ae1c392e8e73e2f05b676a5f2Devang Patel // Ignore dbg intrinsics. 2057556b20ab46520ac53bb689d3c70160bc9d496a3fDevang Patel while (isa<DbgInfoIntrinsic>(I)) 2058d0a203d76f4ef77ae1c392e8e73e2f05b676a5f2Devang Patel ++I; 2059d0a203d76f4ef77ae1c392e8e73e2f05b676a5f2Devang Patel if (&*I == BI) { 2060e67fa05036f634a4ec1e0893033c89250eb58954Chris Lattner if (FoldValueComparisonIntoPredecessors(BI)) 2061e67fa05036f634a4ec1e0893033c89250eb58954Chris Lattner return SimplifyCFG(BB) | true; 2062d0a203d76f4ef77ae1c392e8e73e2f05b676a5f2Devang Patel } else if (&*I == cast<Instruction>(BI->getCondition())){ 2063d0a203d76f4ef77ae1c392e8e73e2f05b676a5f2Devang Patel ++I; 2064d0a203d76f4ef77ae1c392e8e73e2f05b676a5f2Devang Patel // Ignore dbg intrinsics. 2065d0a203d76f4ef77ae1c392e8e73e2f05b676a5f2Devang Patel while (isa<DbgInfoIntrinsic>(I)) 2066d0a203d76f4ef77ae1c392e8e73e2f05b676a5f2Devang Patel ++I; 20679a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (&*I == BI && FoldValueComparisonIntoPredecessors(BI)) 20689a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner return SimplifyCFG(BB) | true; 2069d0a203d76f4ef77ae1c392e8e73e2f05b676a5f2Devang Patel } 2070e67fa05036f634a4ec1e0893033c89250eb58954Chris Lattner } 2071d0a203d76f4ef77ae1c392e8e73e2f05b676a5f2Devang Patel 2072eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner // If this is a branch on a phi node in the current block, thread control 2073eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner // through this block if any PHI node entries are constants. 2074eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner if (PHINode *PN = dyn_cast<PHINode>(BI->getCondition())) 2075eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner if (PN->getParent() == BI->getParent()) 2076eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner if (FoldCondBranchOnPHI(BI)) 2077eaba3a194c23ecbfc5f3da439d1ef7a08eedf02cChris Lattner return SimplifyCFG(BB) | true; 2078e67fa05036f634a4ec1e0893033c89250eb58954Chris Lattner 2079e67fa05036f634a4ec1e0893033c89250eb58954Chris Lattner // If this basic block is ONLY a setcc and a branch, and if a predecessor 2080e67fa05036f634a4ec1e0893033c89250eb58954Chris Lattner // branches to us and one of our successors, fold the setcc into the 2081e67fa05036f634a4ec1e0893033c89250eb58954Chris Lattner // predecessor and use logical operations to pick the right destination. 20821347e87c7baa78bd442d7017a8d67bd4fe674e01Chris Lattner if (FoldBranchToCommonDest(BI)) 2083c69b4a5b8ba83863f9d24f7ca2aa02395addb868Bill Wendling return SimplifyCFG(BB) | true; 2084e67fa05036f634a4ec1e0893033c89250eb58954Chris Lattner 2085867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner 2086867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner // Scan predecessor blocks for conditional branches. 20872e42e36698d5a34f1952ca3389f1973a6a1166f2Chris Lattner for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI) 20882e42e36698d5a34f1952ca3389f1973a6a1166f2Chris Lattner if (BranchInst *PBI = dyn_cast<BranchInst>((*PI)->getTerminator())) 2089867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner if (PBI != BI && PBI->isConditional()) 2090867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner if (SimplifyCondBranchToCondBranch(PBI, BI)) 2091867661ac8bd8e202bd4becf9b8e046bf69e150b1Chris Lattner return SimplifyCFG(BB) | true; 2092cd4b709d73f8705571d5680d5d7c1962a1239fdaChris Lattner 2093cd4b709d73f8705571d5680d5d7c1962a1239fdaChris Lattner 2094cd4b709d73f8705571d5680d5d7c1962a1239fdaChris Lattner // Change br (X == 0 | X == 1), T, F into a switch instruction. 2095cd4b709d73f8705571d5680d5d7c1962a1239fdaChris Lattner // If this is a bunch of seteq's or'd together, or if it's a bunch of 2096cd4b709d73f8705571d5680d5d7c1962a1239fdaChris Lattner // 'setne's and'ed together, collect them. 2097cd4b709d73f8705571d5680d5d7c1962a1239fdaChris Lattner Value *CompVal = 0; 2098cd4b709d73f8705571d5680d5d7c1962a1239fdaChris Lattner std::vector<ConstantInt*> Values; 2099cd4b709d73f8705571d5680d5d7c1962a1239fdaChris Lattner bool TrueWhenEqual = GatherValueComparisons(BI->getCondition(), CompVal, 210028acc135481691771205dea7cb4edbd3927aa764Chris Lattner Values, TD); 2101cd4b709d73f8705571d5680d5d7c1962a1239fdaChris Lattner if (CompVal) { 2102cd4b709d73f8705571d5680d5d7c1962a1239fdaChris Lattner // There might be duplicate constants in the list, which the switch 2103cd4b709d73f8705571d5680d5d7c1962a1239fdaChris Lattner // instruction can't handle, remove them now. 21046d4d21e29d4840236ab6f15c5247379820021d0cChris Lattner array_pod_sort(Values.begin(), Values.end(), ConstantIntSortPredicate); 2105cd4b709d73f8705571d5680d5d7c1962a1239fdaChris Lattner Values.erase(std::unique(Values.begin(), Values.end()), Values.end()); 2106cd4b709d73f8705571d5680d5d7c1962a1239fdaChris Lattner 2107cd4b709d73f8705571d5680d5d7c1962a1239fdaChris Lattner // Figure out which block is which destination. 2108cd4b709d73f8705571d5680d5d7c1962a1239fdaChris Lattner BasicBlock *DefaultBB = BI->getSuccessor(1); 2109cd4b709d73f8705571d5680d5d7c1962a1239fdaChris Lattner BasicBlock *EdgeBB = BI->getSuccessor(0); 2110cd4b709d73f8705571d5680d5d7c1962a1239fdaChris Lattner if (!TrueWhenEqual) std::swap(DefaultBB, EdgeBB); 2111cd4b709d73f8705571d5680d5d7c1962a1239fdaChris Lattner 2112cd4b709d73f8705571d5680d5d7c1962a1239fdaChris Lattner // Convert pointer to int before we switch. 2113cd4b709d73f8705571d5680d5d7c1962a1239fdaChris Lattner if (CompVal->getType()->isPointerTy()) { 2114cd4b709d73f8705571d5680d5d7c1962a1239fdaChris Lattner assert(TD && "Cannot switch on pointer without TargetData"); 2115cd4b709d73f8705571d5680d5d7c1962a1239fdaChris Lattner CompVal = new PtrToIntInst(CompVal, 2116cd4b709d73f8705571d5680d5d7c1962a1239fdaChris Lattner TD->getIntPtrType(CompVal->getContext()), 2117cd4b709d73f8705571d5680d5d7c1962a1239fdaChris Lattner "magicptr", BI); 2118cd4b709d73f8705571d5680d5d7c1962a1239fdaChris Lattner } 2119cd4b709d73f8705571d5680d5d7c1962a1239fdaChris Lattner 2120cd4b709d73f8705571d5680d5d7c1962a1239fdaChris Lattner // Create the new switch instruction now. 2121cd4b709d73f8705571d5680d5d7c1962a1239fdaChris Lattner SwitchInst *New = SwitchInst::Create(CompVal, DefaultBB, 2122cd4b709d73f8705571d5680d5d7c1962a1239fdaChris Lattner Values.size(), BI); 2123cd4b709d73f8705571d5680d5d7c1962a1239fdaChris Lattner 2124cd4b709d73f8705571d5680d5d7c1962a1239fdaChris Lattner // Add all of the 'cases' to the switch instruction. 2125cd4b709d73f8705571d5680d5d7c1962a1239fdaChris Lattner for (unsigned i = 0, e = Values.size(); i != e; ++i) 2126cd4b709d73f8705571d5680d5d7c1962a1239fdaChris Lattner New->addCase(Values[i], EdgeBB); 2127cd4b709d73f8705571d5680d5d7c1962a1239fdaChris Lattner 2128cd4b709d73f8705571d5680d5d7c1962a1239fdaChris Lattner // We added edges from PI to the EdgeBB. As such, if there were any 2129cd4b709d73f8705571d5680d5d7c1962a1239fdaChris Lattner // PHI nodes in EdgeBB, they need entries to be added corresponding to 2130cd4b709d73f8705571d5680d5d7c1962a1239fdaChris Lattner // the number of edges added. 2131cd4b709d73f8705571d5680d5d7c1962a1239fdaChris Lattner for (BasicBlock::iterator BBI = EdgeBB->begin(); 2132cd4b709d73f8705571d5680d5d7c1962a1239fdaChris Lattner isa<PHINode>(BBI); ++BBI) { 2133cd4b709d73f8705571d5680d5d7c1962a1239fdaChris Lattner PHINode *PN = cast<PHINode>(BBI); 2134cd4b709d73f8705571d5680d5d7c1962a1239fdaChris Lattner Value *InVal = PN->getIncomingValueForBlock(BB); 2135cd4b709d73f8705571d5680d5d7c1962a1239fdaChris Lattner for (unsigned i = 0, e = Values.size()-1; i != e; ++i) 2136cd4b709d73f8705571d5680d5d7c1962a1239fdaChris Lattner PN->addIncoming(InVal, BB); 2137cd4b709d73f8705571d5680d5d7c1962a1239fdaChris Lattner } 2138cd4b709d73f8705571d5680d5d7c1962a1239fdaChris Lattner 2139cd4b709d73f8705571d5680d5d7c1962a1239fdaChris Lattner // Erase the old branch instruction. 2140cd4b709d73f8705571d5680d5d7c1962a1239fdaChris Lattner EraseTerminatorInstAndDCECond(BI); 2141cd4b709d73f8705571d5680d5d7c1962a1239fdaChris Lattner return true; 2142cd4b709d73f8705571d5680d5d7c1962a1239fdaChris Lattner } 2143d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner } 2144698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner } else if (isa<UnreachableInst>(BB->getTerminator())) { 2145698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner // If there are any instructions immediately before the unreachable that can 2146698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner // be removed, do so. 2147698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner Instruction *Unreachable = BB->getTerminator(); 2148698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner while (Unreachable != BB->begin()) { 2149698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner BasicBlock::iterator BBI = Unreachable; 2150698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner --BBI; 2151f8131c99de2ac66be4307ae24f2db44d12bc9b3fChris Lattner // Do not delete instructions that can have side effects, like calls 2152f8131c99de2ac66be4307ae24f2db44d12bc9b3fChris Lattner // (which may never return) and volatile loads and stores. 215380b8a62fda56179b00fe463ae55d712aa8abefecDale Johannesen if (isa<CallInst>(BBI) && !isa<DbgInfoIntrinsic>(BBI)) break; 2154f8131c99de2ac66be4307ae24f2db44d12bc9b3fChris Lattner 2155f8131c99de2ac66be4307ae24f2db44d12bc9b3fChris Lattner if (StoreInst *SI = dyn_cast<StoreInst>(BBI)) 2156f8131c99de2ac66be4307ae24f2db44d12bc9b3fChris Lattner if (SI->isVolatile()) 2157f8131c99de2ac66be4307ae24f2db44d12bc9b3fChris Lattner break; 2158f8131c99de2ac66be4307ae24f2db44d12bc9b3fChris Lattner 2159f8131c99de2ac66be4307ae24f2db44d12bc9b3fChris Lattner if (LoadInst *LI = dyn_cast<LoadInst>(BBI)) 2160f8131c99de2ac66be4307ae24f2db44d12bc9b3fChris Lattner if (LI->isVolatile()) 2161f8131c99de2ac66be4307ae24f2db44d12bc9b3fChris Lattner break; 2162f8131c99de2ac66be4307ae24f2db44d12bc9b3fChris Lattner 2163698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner // Delete this instruction 2164698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner BB->getInstList().erase(BBI); 2165698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner Changed = true; 2166698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner } 2167698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner 2168698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner // If the unreachable instruction is the first in the block, take a gander 2169698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner // at all of the predecessors of this instruction, and simplify them. 2170698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner if (&BB->front() == Unreachable) { 21718244243a31d636ce8838a81d4c402274fd391d2bChris Lattner SmallVector<BasicBlock*, 8> Preds(pred_begin(BB), pred_end(BB)); 2172698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner for (unsigned i = 0, e = Preds.size(); i != e; ++i) { 2173698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner TerminatorInst *TI = Preds[i]->getTerminator(); 2174698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner 2175698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner if (BranchInst *BI = dyn_cast<BranchInst>(TI)) { 2176698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner if (BI->isUnconditional()) { 2177698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner if (BI->getSuccessor(0) == BB) { 21781d0be15f89cb5056e20e2d24faa8d6afb1573bcaOwen Anderson new UnreachableInst(TI->getContext(), TI); 2179698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner TI->eraseFromParent(); 2180698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner Changed = true; 2181698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner } 2182698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner } else { 2183698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner if (BI->getSuccessor(0) == BB) { 2184051a950000e21935165db56695e35bade668193bGabor Greif BranchInst::Create(BI->getSuccessor(1), BI); 2185080efb8cea6255b4f1f373d9cb583d6a6302106bEli Friedman EraseTerminatorInstAndDCECond(BI); 2186698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner } else if (BI->getSuccessor(1) == BB) { 2187051a950000e21935165db56695e35bade668193bGabor Greif BranchInst::Create(BI->getSuccessor(0), BI); 2188080efb8cea6255b4f1f373d9cb583d6a6302106bEli Friedman EraseTerminatorInstAndDCECond(BI); 2189698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner Changed = true; 2190698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner } 2191698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner } 2192698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner } else if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) { 2193698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner for (unsigned i = 1, e = SI->getNumCases(); i != e; ++i) 2194698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner if (SI->getSuccessor(i) == BB) { 219542eb7524ef3a994f184924e583871406cf5d1ed6Chris Lattner BB->removePredecessor(SI->getParent()); 2196698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner SI->removeCase(i); 2197698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner --i; --e; 2198698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner Changed = true; 2199698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner } 2200698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner // If the default value is unreachable, figure out the most popular 2201698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner // destination and make it the default. 2202698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner if (SI->getSuccessor(0) == BB) { 2203698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner std::map<BasicBlock*, unsigned> Popularity; 2204698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner for (unsigned i = 1, e = SI->getNumCases(); i != e; ++i) 2205698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner Popularity[SI->getSuccessor(i)]++; 2206698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner 2207698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner // Find the most popular block. 2208698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner unsigned MaxPop = 0; 2209698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner BasicBlock *MaxBlock = 0; 2210698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner for (std::map<BasicBlock*, unsigned>::iterator 2211698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner I = Popularity.begin(), E = Popularity.end(); I != E; ++I) { 2212698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner if (I->second > MaxPop) { 2213698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner MaxPop = I->second; 2214698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner MaxBlock = I->first; 2215698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner } 2216698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner } 2217698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner if (MaxBlock) { 2218698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner // Make this the new default, allowing us to delete any explicit 2219698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner // edges to it. 2220698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner SI->setSuccessor(0, MaxBlock); 2221698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner Changed = true; 2222698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner 222342eb7524ef3a994f184924e583871406cf5d1ed6Chris Lattner // If MaxBlock has phinodes in it, remove MaxPop-1 entries from 222442eb7524ef3a994f184924e583871406cf5d1ed6Chris Lattner // it. 222542eb7524ef3a994f184924e583871406cf5d1ed6Chris Lattner if (isa<PHINode>(MaxBlock->begin())) 222642eb7524ef3a994f184924e583871406cf5d1ed6Chris Lattner for (unsigned i = 0; i != MaxPop-1; ++i) 222742eb7524ef3a994f184924e583871406cf5d1ed6Chris Lattner MaxBlock->removePredecessor(SI->getParent()); 222842eb7524ef3a994f184924e583871406cf5d1ed6Chris Lattner 2229698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner for (unsigned i = 1, e = SI->getNumCases(); i != e; ++i) 2230698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner if (SI->getSuccessor(i) == MaxBlock) { 2231698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner SI->removeCase(i); 2232698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner --i; --e; 2233698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner } 2234698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner } 2235698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner } 2236698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner } else if (InvokeInst *II = dyn_cast<InvokeInst>(TI)) { 2237698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner if (II->getUnwindDest() == BB) { 2238698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner // Convert the invoke to a call instruction. This would be a good 2239698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner // place to note that the call does not throw though. 2240051a950000e21935165db56695e35bade668193bGabor Greif BranchInst *BI = BranchInst::Create(II->getNormalDest(), II); 2241698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner II->removeFromParent(); // Take out of symbol table 2242fd93908ae8b9684fe71c239e3c6cfe13ff6a2663Misha Brukman 2243698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner // Insert the call now... 2244bd44314c676a05e52f3841c5961ea0a2bc1116fbGabor Greif SmallVector<Value*, 8> Args(II->op_begin(), II->op_end()-3); 2245051a950000e21935165db56695e35bade668193bGabor Greif CallInst *CI = CallInst::Create(II->getCalledValue(), 2246051a950000e21935165db56695e35bade668193bGabor Greif Args.begin(), Args.end(), 2247051a950000e21935165db56695e35bade668193bGabor Greif II->getName(), BI); 224816d0db2da8c274f98db4a89ca7a92f970d464b9aChris Lattner CI->setCallingConv(II->getCallingConv()); 22490598866c052147c31b808391f58434ce3dbfb838Devang Patel CI->setAttributes(II->getAttributes()); 2250bd44314c676a05e52f3841c5961ea0a2bc1116fbGabor Greif // If the invoke produced a value, the call does now instead. 2251698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner II->replaceAllUsesWith(CI); 2252698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner delete II; 2253698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner Changed = true; 2254698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner } 2255698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner } 2256698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner } 2257698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner 2258698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner // If this block is now dead, remove it. 22595f28475b30cf09e946bf6cb7c8de6d597a41610eDuncan Sands if (pred_begin(BB) == pred_end(BB) && BB != &Fn->getEntryBlock()) { 2260698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner // We know there are no successors, so just nuke the block. 22615f28475b30cf09e946bf6cb7c8de6d597a41610eDuncan Sands Fn->getBasicBlockList().erase(BB); 2262698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner return true; 2263698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner } 2264698f96f7c81e45292ae4f5d76b8e06c88a88a71fChris Lattner } 22657a4994356b0e9726384edda57f7db65e5bc10673Dan Gohman } else if (IndirectBrInst *IBI = 22667a4994356b0e9726384edda57f7db65e5bc10673Dan Gohman dyn_cast<IndirectBrInst>(BB->getTerminator())) { 2267e2c6d131d12c779a410740e0a90545def75e0f48Dan Gohman // Eliminate redundant destinations. 2268e2c6d131d12c779a410740e0a90545def75e0f48Dan Gohman SmallPtrSet<Value *, 8> Succs; 2269e2c6d131d12c779a410740e0a90545def75e0f48Dan Gohman for (unsigned i = 0, e = IBI->getNumDestinations(); i != e; ++i) { 2270e2c6d131d12c779a410740e0a90545def75e0f48Dan Gohman BasicBlock *Dest = IBI->getDestination(i); 22717a4994356b0e9726384edda57f7db65e5bc10673Dan Gohman if (!Dest->hasAddressTaken() || !Succs.insert(Dest)) { 2272e2c6d131d12c779a410740e0a90545def75e0f48Dan Gohman Dest->removePredecessor(BB); 2273e2c6d131d12c779a410740e0a90545def75e0f48Dan Gohman IBI->removeDestination(i); 2274e2c6d131d12c779a410740e0a90545def75e0f48Dan Gohman --i; --e; 2275e2c6d131d12c779a410740e0a90545def75e0f48Dan Gohman Changed = true; 2276e2c6d131d12c779a410740e0a90545def75e0f48Dan Gohman } 2277e2c6d131d12c779a410740e0a90545def75e0f48Dan Gohman } 2278e2c6d131d12c779a410740e0a90545def75e0f48Dan Gohman 2279e2c6d131d12c779a410740e0a90545def75e0f48Dan Gohman if (IBI->getNumDestinations() == 0) { 2280e2c6d131d12c779a410740e0a90545def75e0f48Dan Gohman // If the indirectbr has no successors, change it to unreachable. 2281e2c6d131d12c779a410740e0a90545def75e0f48Dan Gohman new UnreachableInst(IBI->getContext(), IBI); 22827ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel EraseTerminatorInstAndDCECond(IBI); 2283e2c6d131d12c779a410740e0a90545def75e0f48Dan Gohman Changed = true; 2284e2c6d131d12c779a410740e0a90545def75e0f48Dan Gohman } else if (IBI->getNumDestinations() == 1) { 2285e2c6d131d12c779a410740e0a90545def75e0f48Dan Gohman // If the indirectbr has one successor, change it to a direct branch. 2286e2c6d131d12c779a410740e0a90545def75e0f48Dan Gohman BranchInst::Create(IBI->getDestination(0), IBI); 22877ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel EraseTerminatorInstAndDCECond(IBI); 2288e2c6d131d12c779a410740e0a90545def75e0f48Dan Gohman Changed = true; 22897ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel } else if (SelectInst *SI = dyn_cast<SelectInst>(IBI->getAddress())) { 22907ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel if (SimplifyIndirectBrOnSelect(IBI, SI)) 22917ac40c3ffabcdac9510e7efc4dc75a8ed2b32edbFrits van Bommel return SimplifyCFG(BB) | true; 2292e2c6d131d12c779a410740e0a90545def75e0f48Dan Gohman } 229319831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner } 229419831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner 229501d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner // Merge basic blocks into their predecessor if there is only one distinct 229601d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner // pred, and if there is only one distinct successor of the predecessor, and 229701d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner // if there are no PHI nodes. 229801d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner // 2299cfa94198d5a75776a600df8113ac565b25552399Owen Anderson if (MergeBlockIntoPredecessor(BB)) 2300cfa94198d5a75776a600df8113ac565b25552399Owen Anderson return true; 2301cfa94198d5a75776a600df8113ac565b25552399Owen Anderson 2302cfa94198d5a75776a600df8113ac565b25552399Owen Anderson // Otherwise, if this block only has a single predecessor, and if that block 2303cfa94198d5a75776a600df8113ac565b25552399Owen Anderson // is a conditional branch, see if we can hoist any code from this block up 2304cfa94198d5a75776a600df8113ac565b25552399Owen Anderson // into our predecessor. 23052355f948c59a2b4a78667d6898333524f9b78f27Chris Lattner pred_iterator PI(pred_begin(BB)), PE(pred_end(BB)); 2306e2c6d131d12c779a410740e0a90545def75e0f48Dan Gohman BasicBlock *OnlyPred = 0; 2307e2c6d131d12c779a410740e0a90545def75e0f48Dan Gohman for (; PI != PE; ++PI) { // Search all predecessors, see if they are all same 2308e2c6d131d12c779a410740e0a90545def75e0f48Dan Gohman if (!OnlyPred) 2309e2c6d131d12c779a410740e0a90545def75e0f48Dan Gohman OnlyPred = *PI; 2310e2c6d131d12c779a410740e0a90545def75e0f48Dan Gohman else if (*PI != OnlyPred) { 23112355f948c59a2b4a78667d6898333524f9b78f27Chris Lattner OnlyPred = 0; // There are multiple different predecessors... 23122355f948c59a2b4a78667d6898333524f9b78f27Chris Lattner break; 23132355f948c59a2b4a78667d6898333524f9b78f27Chris Lattner } 2314e2c6d131d12c779a410740e0a90545def75e0f48Dan Gohman } 2315cfa94198d5a75776a600df8113ac565b25552399Owen Anderson 23169a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (OnlyPred) { 23179a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner BranchInst *BI = dyn_cast<BranchInst>(OnlyPred->getTerminator()); 23189a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (BI && BI->isConditional()) { 23199a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // Get the other block. 23209a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner BasicBlock *OtherBB = BI->getSuccessor(BI->getSuccessor(0) == BB); 23219a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner PI = pred_begin(OtherBB); 23229a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner ++PI; 23239a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner 23249a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (PI == pred_end(OtherBB)) { 23259a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // We have a conditional branch to two blocks that are only reachable 23269a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // from the condbr. We know that the condbr dominates the two blocks, 23279a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // so see if there is any identical code in the "then" and "else" 23289a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // blocks. If so, we can hoist it up to the branching block. 23299a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner Changed |= HoistThenElseCodeToIf(BI); 23309a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner } else { 23319a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner BasicBlock* OnlySucc = NULL; 23329a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner for (succ_iterator SI = succ_begin(BB), SE = succ_end(BB); 23339a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner SI != SE; ++SI) { 23349a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (!OnlySucc) 23359a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner OnlySucc = *SI; 23369a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner else if (*SI != OnlySucc) { 23379a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner OnlySucc = 0; // There are multiple distinct successors! 23389a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner break; 23394d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng } 23409a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner } 23414d09efd7b8fdf9e8a8c89bdb821f4992091a764bEvan Cheng 23429a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner if (OnlySucc == OtherBB) { 23439a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // If BB's only successor is the other successor of the predecessor, 23449a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // i.e. a triangle, see if we can hoist any code from this block up 23459a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner // to the "if" block. 23469a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner Changed |= SpeculativelyExecuteBB(BI, BB); 23477613437db954abafd1230c961e87872df5721957Chris Lattner } 234837dc938bbe556a9414d063196d367c2f75d07d95Chris Lattner } 23499a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner } 23509a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner } 23519a2b72acc9651be04c12ba713702ddc5d449ce72Chris Lattner 2352694e37f08a7c09ccc24642532106295cf7b3a1e3Chris Lattner return Changed; 235301d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner} 235458e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen 235558e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen/// SimplifyCFG - This function is used to do simplification of a CFG. For 235658e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen/// example, it adjusts branches to branches to eliminate the extra hop, it 235758e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen/// eliminates unreachable basic blocks, and does other "peephole" optimization 235858e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen/// of the CFG. It returns true if a modification was made. 235958e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen/// 236058e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesenbool llvm::SimplifyCFG(BasicBlock *BB, const TargetData *TD) { 236158e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen return SimplifyCFGOpt(TD).run(BB); 236258e9ee85fda5083e2eea987917e8eab6ba31fe5eJakob Stoklund Olesen} 2363