SimplifyCFG.cpp revision d52c261cf801331bebda9711acd54c7c5377a6bd
101d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner//===- SimplifyCFG.cpp - Code to perform CFG simplification ---------------===// 2b576c94c15af9a440f69d9d03c2afead7971118cJohn Criswell// 3b576c94c15af9a440f69d9d03c2afead7971118cJohn Criswell// The LLVM Compiler Infrastructure 4b576c94c15af9a440f69d9d03c2afead7971118cJohn Criswell// 5b576c94c15af9a440f69d9d03c2afead7971118cJohn Criswell// This file was developed by the LLVM research group and is distributed under 6b576c94c15af9a440f69d9d03c2afead7971118cJohn Criswell// the University of Illinois Open Source License. See LICENSE.TXT for details. 7b576c94c15af9a440f69d9d03c2afead7971118cJohn Criswell// 8b576c94c15af9a440f69d9d03c2afead7971118cJohn Criswell//===----------------------------------------------------------------------===// 901d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner// 10bb190ac8dafdcc5e604da3695987d69ee8632195Chris Lattner// Peephole optimize the CFG. 1101d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner// 1201d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner//===----------------------------------------------------------------------===// 1301d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner 1401d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner#include "llvm/Transforms/Utils/Local.h" 15723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner#include "llvm/Constants.h" 16723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner#include "llvm/Instructions.h" 170d56008f53587531718ec36af82cc24576580b36Chris Lattner#include "llvm/Type.h" 1801d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner#include "llvm/Support/CFG.h" 1901d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner#include <algorithm> 2001d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner#include <functional> 21d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner#include <set> 22f7703df4968084c18c248c1feea9961c19a32e6aChris Lattnerusing namespace llvm; 23d0fde30ce850b78371fd1386338350591f9ff494Brian Gaeke 240d56008f53587531718ec36af82cc24576580b36Chris Lattner// PropagatePredecessorsForPHIs - This gets "Succ" ready to have the 250d56008f53587531718ec36af82cc24576580b36Chris Lattner// predecessors from "BB". This is a little tricky because "Succ" has PHI 260d56008f53587531718ec36af82cc24576580b36Chris Lattner// nodes, which need to have extra slots added to them to hold the merge edges 270d56008f53587531718ec36af82cc24576580b36Chris Lattner// from BB's predecessors, and BB itself might have had PHI nodes in it. This 280d56008f53587531718ec36af82cc24576580b36Chris Lattner// function returns true (failure) if the Succ BB already has a predecessor that 290d56008f53587531718ec36af82cc24576580b36Chris Lattner// is a predecessor of BB and incoming PHI arguments would not be discernible. 3001d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner// 3101d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner// Assumption: Succ is the single successor for BB. 3201d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner// 33a3bbcb5b664c1c851b87392119608901b2e1837cMisha Brukmanstatic bool PropagatePredecessorsForPHIs(BasicBlock *BB, BasicBlock *Succ) { 3401d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner assert(*succ_begin(BB) == Succ && "Succ is not successor of BB!"); 353abb95df01ff2ea5a6a35a1b47351072d4cb4c73Chris Lattner 363abb95df01ff2ea5a6a35a1b47351072d4cb4c73Chris Lattner if (!isa<PHINode>(Succ->front())) 373abb95df01ff2ea5a6a35a1b47351072d4cb4c73Chris Lattner return false; // We can make the transformation, no problem. 3801d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner 3901d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner // If there is more than one predecessor, and there are PHI nodes in 4001d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner // the successor, then we need to add incoming edges for the PHI nodes 4101d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner // 4201d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner const std::vector<BasicBlock*> BBPreds(pred_begin(BB), pred_end(BB)); 4301d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner 4401d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner // Check to see if one of the predecessors of BB is already a predecessor of 45e2ca540e7c29703c3b943a96fed7e383c7bd35c0Chris Lattner // Succ. If so, we cannot do the transformation if there are any PHI nodes 46e2ca540e7c29703c3b943a96fed7e383c7bd35c0Chris Lattner // with incompatible values coming in from the two edges! 4701d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner // 48e2ca540e7c29703c3b943a96fed7e383c7bd35c0Chris Lattner for (pred_iterator PI = pred_begin(Succ), PE = pred_end(Succ); PI != PE; ++PI) 49e2ca540e7c29703c3b943a96fed7e383c7bd35c0Chris Lattner if (find(BBPreds.begin(), BBPreds.end(), *PI) != BBPreds.end()) { 50e2ca540e7c29703c3b943a96fed7e383c7bd35c0Chris Lattner // Loop over all of the PHI nodes checking to see if there are 51e2ca540e7c29703c3b943a96fed7e383c7bd35c0Chris Lattner // incompatible values coming in. 5246a5f1f6e4a3be3d53b4e0016b78d108a2353f4cChris Lattner for (BasicBlock::iterator I = Succ->begin(); 53e408e25132b8de8c757db1e3ddcd70432dfeb24dChris Lattner PHINode *PN = dyn_cast<PHINode>(I); ++I) { 54e2ca540e7c29703c3b943a96fed7e383c7bd35c0Chris Lattner // Loop up the entries in the PHI node for BB and for *PI if the values 55e2ca540e7c29703c3b943a96fed7e383c7bd35c0Chris Lattner // coming in are non-equal, we cannot merge these two blocks (instead we 56e2ca540e7c29703c3b943a96fed7e383c7bd35c0Chris Lattner // should insert a conditional move or something, then merge the 57e2ca540e7c29703c3b943a96fed7e383c7bd35c0Chris Lattner // blocks). 58e2ca540e7c29703c3b943a96fed7e383c7bd35c0Chris Lattner int Idx1 = PN->getBasicBlockIndex(BB); 59e2ca540e7c29703c3b943a96fed7e383c7bd35c0Chris Lattner int Idx2 = PN->getBasicBlockIndex(*PI); 60e2ca540e7c29703c3b943a96fed7e383c7bd35c0Chris Lattner assert(Idx1 != -1 && Idx2 != -1 && 61e2ca540e7c29703c3b943a96fed7e383c7bd35c0Chris Lattner "Didn't have entries for my predecessors??"); 62e2ca540e7c29703c3b943a96fed7e383c7bd35c0Chris Lattner if (PN->getIncomingValue(Idx1) != PN->getIncomingValue(Idx2)) 63e2ca540e7c29703c3b943a96fed7e383c7bd35c0Chris Lattner return true; // Values are not equal... 64e2ca540e7c29703c3b943a96fed7e383c7bd35c0Chris Lattner } 65e2ca540e7c29703c3b943a96fed7e383c7bd35c0Chris Lattner } 6601d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner 6701d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner // Loop over all of the PHI nodes in the successor BB 6801d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner for (BasicBlock::iterator I = Succ->begin(); 69e408e25132b8de8c757db1e3ddcd70432dfeb24dChris Lattner PHINode *PN = dyn_cast<PHINode>(I); ++I) { 70bb190ac8dafdcc5e604da3695987d69ee8632195Chris Lattner Value *OldVal = PN->removeIncomingValue(BB, false); 7101d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner assert(OldVal && "No entry in PHI for Pred BB!"); 7201d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner 7346a5f1f6e4a3be3d53b4e0016b78d108a2353f4cChris Lattner // If this incoming value is one of the PHI nodes in BB... 7446a5f1f6e4a3be3d53b4e0016b78d108a2353f4cChris Lattner if (isa<PHINode>(OldVal) && cast<PHINode>(OldVal)->getParent() == BB) { 7546a5f1f6e4a3be3d53b4e0016b78d108a2353f4cChris Lattner PHINode *OldValPN = cast<PHINode>(OldVal); 7646a5f1f6e4a3be3d53b4e0016b78d108a2353f4cChris Lattner for (std::vector<BasicBlock*>::const_iterator PredI = BBPreds.begin(), 7746a5f1f6e4a3be3d53b4e0016b78d108a2353f4cChris Lattner End = BBPreds.end(); PredI != End; ++PredI) { 7846a5f1f6e4a3be3d53b4e0016b78d108a2353f4cChris Lattner PN->addIncoming(OldValPN->getIncomingValueForBlock(*PredI), *PredI); 7946a5f1f6e4a3be3d53b4e0016b78d108a2353f4cChris Lattner } 8046a5f1f6e4a3be3d53b4e0016b78d108a2353f4cChris Lattner } else { 8146a5f1f6e4a3be3d53b4e0016b78d108a2353f4cChris Lattner for (std::vector<BasicBlock*>::const_iterator PredI = BBPreds.begin(), 8246a5f1f6e4a3be3d53b4e0016b78d108a2353f4cChris Lattner End = BBPreds.end(); PredI != End; ++PredI) { 8346a5f1f6e4a3be3d53b4e0016b78d108a2353f4cChris Lattner // Add an incoming value for each of the new incoming values... 8446a5f1f6e4a3be3d53b4e0016b78d108a2353f4cChris Lattner PN->addIncoming(OldVal, *PredI); 8546a5f1f6e4a3be3d53b4e0016b78d108a2353f4cChris Lattner } 8601d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner } 8701d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner } 8801d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner return false; 8901d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner} 9001d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner 91723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner/// GetIfCondition - Given a basic block (BB) with two predecessors (and 92723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner/// presumably PHI nodes in it), check to see if the merge at this block is due 93723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner/// to an "if condition". If so, return the boolean condition that determines 94723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner/// which entry into BB will be taken. Also, return by references the block 95723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner/// that will be entered from if the condition is true, and the block that will 96723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner/// be entered if the condition is false. 97723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner/// 98723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner/// 99723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattnerstatic Value *GetIfCondition(BasicBlock *BB, 100723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner BasicBlock *&IfTrue, BasicBlock *&IfFalse) { 101723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner assert(std::distance(pred_begin(BB), pred_end(BB)) == 2 && 102723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner "Function can only handle blocks with 2 predecessors!"); 103723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner BasicBlock *Pred1 = *pred_begin(BB); 104723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner BasicBlock *Pred2 = *++pred_begin(BB); 105723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner 106723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // We can only handle branches. Other control flow will be lowered to 107723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // branches if possible anyway. 108723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner if (!isa<BranchInst>(Pred1->getTerminator()) || 109723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner !isa<BranchInst>(Pred2->getTerminator())) 110723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner return 0; 111723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner BranchInst *Pred1Br = cast<BranchInst>(Pred1->getTerminator()); 112723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner BranchInst *Pred2Br = cast<BranchInst>(Pred2->getTerminator()); 113723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner 114723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // Eliminate code duplication by ensuring that Pred1Br is conditional if 115723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // either are. 116723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner if (Pred2Br->isConditional()) { 117723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // If both branches are conditional, we don't have an "if statement". In 118723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // reality, we could transform this case, but since the condition will be 119723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // required anyway, we stand no chance of eliminating it, so the xform is 120723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // probably not profitable. 121723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner if (Pred1Br->isConditional()) 122723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner return 0; 123723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner 124723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner std::swap(Pred1, Pred2); 125723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner std::swap(Pred1Br, Pred2Br); 126723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner } 127723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner 128723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner if (Pred1Br->isConditional()) { 129723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // If we found a conditional branch predecessor, make sure that it branches 130723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // to BB and Pred2Br. If it doesn't, this isn't an "if statement". 131723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner if (Pred1Br->getSuccessor(0) == BB && 132723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner Pred1Br->getSuccessor(1) == Pred2) { 133723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner IfTrue = Pred1; 134723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner IfFalse = Pred2; 135723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner } else if (Pred1Br->getSuccessor(0) == Pred2 && 136723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner Pred1Br->getSuccessor(1) == BB) { 137723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner IfTrue = Pred2; 138723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner IfFalse = Pred1; 139723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner } else { 140723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // We know that one arm of the conditional goes to BB, so the other must 141723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // go somewhere unrelated, and this must not be an "if statement". 142723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner return 0; 143723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner } 144723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner 145723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // The only thing we have to watch out for here is to make sure that Pred2 146723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // doesn't have incoming edges from other blocks. If it does, the condition 147723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // doesn't dominate BB. 148723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner if (++pred_begin(Pred2) != pred_end(Pred2)) 149723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner return 0; 150723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner 151723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner return Pred1Br->getCondition(); 152723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner } 153723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner 154723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // Ok, if we got here, both predecessors end with an unconditional branch to 155723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // BB. Don't panic! If both blocks only have a single (identical) 156723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // predecessor, and THAT is a conditional branch, then we're all ok! 157723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner if (pred_begin(Pred1) == pred_end(Pred1) || 158723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner ++pred_begin(Pred1) != pred_end(Pred1) || 159723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner pred_begin(Pred2) == pred_end(Pred2) || 160723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner ++pred_begin(Pred2) != pred_end(Pred2) || 161723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner *pred_begin(Pred1) != *pred_begin(Pred2)) 162723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner return 0; 163723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner 164723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // Otherwise, if this is a conditional branch, then we can use it! 165723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner BasicBlock *CommonPred = *pred_begin(Pred1); 166723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner if (BranchInst *BI = dyn_cast<BranchInst>(CommonPred->getTerminator())) { 167723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner assert(BI->isConditional() && "Two successors but not conditional?"); 168723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner if (BI->getSuccessor(0) == Pred1) { 169723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner IfTrue = Pred1; 170723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner IfFalse = Pred2; 171723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner } else { 172723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner IfTrue = Pred2; 173723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner IfFalse = Pred1; 174723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner } 175723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner return BI->getCondition(); 176723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner } 177723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner return 0; 178723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner} 179723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner 180723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner 181723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner// If we have a merge point of an "if condition" as accepted above, return true 182723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner// if the specified value dominates the block. We don't handle the true 183723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner// generality of domination here, just a special case which works well enough 184723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner// for us. 185723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattnerstatic bool DominatesMergePoint(Value *V, BasicBlock *BB) { 186723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner if (Instruction *I = dyn_cast<Instruction>(V)) { 187723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner BasicBlock *PBB = I->getParent(); 188723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // If this instruction is defined in a block that contains an unconditional 189723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // branch to BB, then it must be in the 'conditional' part of the "if 190723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // statement". 191723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner if (isa<BranchInst>(PBB->getTerminator()) && 192723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner cast<BranchInst>(PBB->getTerminator())->isUnconditional() && 193723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner cast<BranchInst>(PBB->getTerminator())->getSuccessor(0) == BB) 194723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner return false; 195723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner 196723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // We also don't want to allow wierd loops that might have the "if 197723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // condition" in the bottom of this block. 198723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner if (PBB == BB) return false; 199723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner } 200723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner 201723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // Non-instructions all dominate instructions. 202723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner return true; 203723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner} 20401d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner 2050d56008f53587531718ec36af82cc24576580b36Chris Lattner// GatherConstantSetEQs - Given a potentially 'or'd together collection of seteq 2060d56008f53587531718ec36af82cc24576580b36Chris Lattner// instructions that compare a value against a constant, return the value being 2070d56008f53587531718ec36af82cc24576580b36Chris Lattner// compared, and stick the constant into the Values vector. 2080d56008f53587531718ec36af82cc24576580b36Chris Lattnerstatic Value *GatherConstantSetEQs(Value *V, std::vector<Constant*> &Values) { 2090d56008f53587531718ec36af82cc24576580b36Chris Lattner if (Instruction *Inst = dyn_cast<Instruction>(V)) 2100d56008f53587531718ec36af82cc24576580b36Chris Lattner if (Inst->getOpcode() == Instruction::SetEQ) { 2110d56008f53587531718ec36af82cc24576580b36Chris Lattner if (Constant *C = dyn_cast<Constant>(Inst->getOperand(1))) { 2120d56008f53587531718ec36af82cc24576580b36Chris Lattner Values.push_back(C); 2130d56008f53587531718ec36af82cc24576580b36Chris Lattner return Inst->getOperand(0); 2140d56008f53587531718ec36af82cc24576580b36Chris Lattner } else if (Constant *C = dyn_cast<Constant>(Inst->getOperand(0))) { 2150d56008f53587531718ec36af82cc24576580b36Chris Lattner Values.push_back(C); 2160d56008f53587531718ec36af82cc24576580b36Chris Lattner return Inst->getOperand(1); 2170d56008f53587531718ec36af82cc24576580b36Chris Lattner } 2180d56008f53587531718ec36af82cc24576580b36Chris Lattner } else if (Inst->getOpcode() == Instruction::Or) { 2190d56008f53587531718ec36af82cc24576580b36Chris Lattner if (Value *LHS = GatherConstantSetEQs(Inst->getOperand(0), Values)) 2200d56008f53587531718ec36af82cc24576580b36Chris Lattner if (Value *RHS = GatherConstantSetEQs(Inst->getOperand(1), Values)) 2210d56008f53587531718ec36af82cc24576580b36Chris Lattner if (LHS == RHS) 2220d56008f53587531718ec36af82cc24576580b36Chris Lattner return LHS; 2230d56008f53587531718ec36af82cc24576580b36Chris Lattner } 2240d56008f53587531718ec36af82cc24576580b36Chris Lattner return 0; 2250d56008f53587531718ec36af82cc24576580b36Chris Lattner} 2260d56008f53587531718ec36af82cc24576580b36Chris Lattner 2270d56008f53587531718ec36af82cc24576580b36Chris Lattner// GatherConstantSetNEs - Given a potentially 'and'd together collection of 2280d56008f53587531718ec36af82cc24576580b36Chris Lattner// setne instructions that compare a value against a constant, return the value 2290d56008f53587531718ec36af82cc24576580b36Chris Lattner// being compared, and stick the constant into the Values vector. 2300d56008f53587531718ec36af82cc24576580b36Chris Lattnerstatic Value *GatherConstantSetNEs(Value *V, std::vector<Constant*> &Values) { 2310d56008f53587531718ec36af82cc24576580b36Chris Lattner if (Instruction *Inst = dyn_cast<Instruction>(V)) 2320d56008f53587531718ec36af82cc24576580b36Chris Lattner if (Inst->getOpcode() == Instruction::SetNE) { 2330d56008f53587531718ec36af82cc24576580b36Chris Lattner if (Constant *C = dyn_cast<Constant>(Inst->getOperand(1))) { 2340d56008f53587531718ec36af82cc24576580b36Chris Lattner Values.push_back(C); 2350d56008f53587531718ec36af82cc24576580b36Chris Lattner return Inst->getOperand(0); 2360d56008f53587531718ec36af82cc24576580b36Chris Lattner } else if (Constant *C = dyn_cast<Constant>(Inst->getOperand(0))) { 2370d56008f53587531718ec36af82cc24576580b36Chris Lattner Values.push_back(C); 2380d56008f53587531718ec36af82cc24576580b36Chris Lattner return Inst->getOperand(1); 2390d56008f53587531718ec36af82cc24576580b36Chris Lattner } 2400d56008f53587531718ec36af82cc24576580b36Chris Lattner } else if (Inst->getOpcode() == Instruction::Cast) { 2410d56008f53587531718ec36af82cc24576580b36Chris Lattner // Cast of X to bool is really a comparison against zero. 2420d56008f53587531718ec36af82cc24576580b36Chris Lattner assert(Inst->getType() == Type::BoolTy && "Can only handle bool values!"); 2430d56008f53587531718ec36af82cc24576580b36Chris Lattner Values.push_back(Constant::getNullValue(Inst->getOperand(0)->getType())); 2440d56008f53587531718ec36af82cc24576580b36Chris Lattner return Inst->getOperand(0); 2450d56008f53587531718ec36af82cc24576580b36Chris Lattner } else if (Inst->getOpcode() == Instruction::And) { 2460d56008f53587531718ec36af82cc24576580b36Chris Lattner if (Value *LHS = GatherConstantSetNEs(Inst->getOperand(0), Values)) 2470d56008f53587531718ec36af82cc24576580b36Chris Lattner if (Value *RHS = GatherConstantSetNEs(Inst->getOperand(1), Values)) 2480d56008f53587531718ec36af82cc24576580b36Chris Lattner if (LHS == RHS) 2490d56008f53587531718ec36af82cc24576580b36Chris Lattner return LHS; 2500d56008f53587531718ec36af82cc24576580b36Chris Lattner } 2510d56008f53587531718ec36af82cc24576580b36Chris Lattner return 0; 2520d56008f53587531718ec36af82cc24576580b36Chris Lattner} 2530d56008f53587531718ec36af82cc24576580b36Chris Lattner 2540d56008f53587531718ec36af82cc24576580b36Chris Lattner 2550d56008f53587531718ec36af82cc24576580b36Chris Lattner 2560d56008f53587531718ec36af82cc24576580b36Chris Lattner/// GatherValueComparisons - If the specified Cond is an 'and' or 'or' of a 2570d56008f53587531718ec36af82cc24576580b36Chris Lattner/// bunch of comparisons of one value against constants, return the value and 2580d56008f53587531718ec36af82cc24576580b36Chris Lattner/// the constants being compared. 2590d56008f53587531718ec36af82cc24576580b36Chris Lattnerstatic bool GatherValueComparisons(Instruction *Cond, Value *&CompVal, 2600d56008f53587531718ec36af82cc24576580b36Chris Lattner std::vector<Constant*> &Values) { 2610d56008f53587531718ec36af82cc24576580b36Chris Lattner if (Cond->getOpcode() == Instruction::Or) { 2620d56008f53587531718ec36af82cc24576580b36Chris Lattner CompVal = GatherConstantSetEQs(Cond, Values); 2630d56008f53587531718ec36af82cc24576580b36Chris Lattner 2640d56008f53587531718ec36af82cc24576580b36Chris Lattner // Return true to indicate that the condition is true if the CompVal is 2650d56008f53587531718ec36af82cc24576580b36Chris Lattner // equal to one of the constants. 2660d56008f53587531718ec36af82cc24576580b36Chris Lattner return true; 2670d56008f53587531718ec36af82cc24576580b36Chris Lattner } else if (Cond->getOpcode() == Instruction::And) { 2680d56008f53587531718ec36af82cc24576580b36Chris Lattner CompVal = GatherConstantSetNEs(Cond, Values); 2690d56008f53587531718ec36af82cc24576580b36Chris Lattner 2700d56008f53587531718ec36af82cc24576580b36Chris Lattner // Return false to indicate that the condition is false if the CompVal is 2710d56008f53587531718ec36af82cc24576580b36Chris Lattner // equal to one of the constants. 2720d56008f53587531718ec36af82cc24576580b36Chris Lattner return false; 2730d56008f53587531718ec36af82cc24576580b36Chris Lattner } 2740d56008f53587531718ec36af82cc24576580b36Chris Lattner return false; 2750d56008f53587531718ec36af82cc24576580b36Chris Lattner} 2760d56008f53587531718ec36af82cc24576580b36Chris Lattner 2770d56008f53587531718ec36af82cc24576580b36Chris Lattner/// ErasePossiblyDeadInstructionTree - If the specified instruction is dead and 2780d56008f53587531718ec36af82cc24576580b36Chris Lattner/// has no side effects, nuke it. If it uses any instructions that become dead 2790d56008f53587531718ec36af82cc24576580b36Chris Lattner/// because the instruction is now gone, nuke them too. 2800d56008f53587531718ec36af82cc24576580b36Chris Lattnerstatic void ErasePossiblyDeadInstructionTree(Instruction *I) { 2810d56008f53587531718ec36af82cc24576580b36Chris Lattner if (isInstructionTriviallyDead(I)) { 2820d56008f53587531718ec36af82cc24576580b36Chris Lattner std::vector<Value*> Operands(I->op_begin(), I->op_end()); 2830d56008f53587531718ec36af82cc24576580b36Chris Lattner I->getParent()->getInstList().erase(I); 2840d56008f53587531718ec36af82cc24576580b36Chris Lattner for (unsigned i = 0, e = Operands.size(); i != e; ++i) 2850d56008f53587531718ec36af82cc24576580b36Chris Lattner if (Instruction *OpI = dyn_cast<Instruction>(Operands[i])) 2860d56008f53587531718ec36af82cc24576580b36Chris Lattner ErasePossiblyDeadInstructionTree(OpI); 2870d56008f53587531718ec36af82cc24576580b36Chris Lattner } 2880d56008f53587531718ec36af82cc24576580b36Chris Lattner} 2890d56008f53587531718ec36af82cc24576580b36Chris Lattner 290d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner/// SafeToMergeTerminators - Return true if it is safe to merge these two 291d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner/// terminator instructions together. 292d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner/// 293d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattnerstatic bool SafeToMergeTerminators(TerminatorInst *SI1, TerminatorInst *SI2) { 294d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner if (SI1 == SI2) return false; // Can't merge with self! 295d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner 296d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner // It is not safe to merge these two switch instructions if they have a common 297d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner // successor, and if that successor has a PHI node, and if that PHI node has 298d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner // conflicting incoming values from the two switch blocks. 299d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner BasicBlock *SI1BB = SI1->getParent(); 300d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner BasicBlock *SI2BB = SI2->getParent(); 301d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner std::set<BasicBlock*> SI1Succs(succ_begin(SI1BB), succ_end(SI1BB)); 302d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner 303d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner for (succ_iterator I = succ_begin(SI2BB), E = succ_end(SI2BB); I != E; ++I) 304d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner if (SI1Succs.count(*I)) 305d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner for (BasicBlock::iterator BBI = (*I)->begin(); 306d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner PHINode *PN = dyn_cast<PHINode>(BBI); ++BBI) 307d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner if (PN->getIncomingValueForBlock(SI1BB) != 308d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner PN->getIncomingValueForBlock(SI2BB)) 309d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner return false; 310d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner 311d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner return true; 312d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner} 313d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner 314d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner/// AddPredecessorToBlock - Update PHI nodes in Succ to indicate that there will 315d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner/// now be entries in it from the 'NewPred' block. The values that will be 316d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner/// flowing into the PHI nodes will be the same as those coming in from 317d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner/// ExistPred, and existing predecessor of Succ. 318d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattnerstatic void AddPredecessorToBlock(BasicBlock *Succ, BasicBlock *NewPred, 319d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner BasicBlock *ExistPred) { 320d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner assert(std::find(succ_begin(ExistPred), succ_end(ExistPred), Succ) != 321d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner succ_end(ExistPred) && "ExistPred is not a predecessor of Succ!"); 322d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner if (!isa<PHINode>(Succ->begin())) return; // Quick exit if nothing to do 323d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner 324d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner for (BasicBlock::iterator I = Succ->begin(); 325d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner PHINode *PN = dyn_cast<PHINode>(I); ++I) { 326d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner Value *V = PN->getIncomingValueForBlock(ExistPred); 327d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner PN->addIncoming(V, NewPred); 328d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner } 329d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner} 330d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner 33101d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner// SimplifyCFG - This function is used to do simplification of a CFG. For 33201d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner// example, it adjusts branches to branches to eliminate the extra hop, it 33301d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner// eliminates unreachable basic blocks, and does other "peephole" optimization 334e2ca540e7c29703c3b943a96fed7e383c7bd35c0Chris Lattner// of the CFG. It returns true if a modification was made. 33501d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner// 33601d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner// WARNING: The entry node of a function may not be simplified. 33701d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner// 338f7703df4968084c18c248c1feea9961c19a32e6aChris Lattnerbool llvm::SimplifyCFG(BasicBlock *BB) { 339dc3602bf0d27aac80e08ef8823967850acd05a14Chris Lattner bool Changed = false; 34001d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner Function *M = BB->getParent(); 34101d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner 34201d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner assert(BB && BB->getParent() && "Block not embedded in function!"); 34301d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner assert(BB->getTerminator() && "Degenerate basic block encountered!"); 34418961504fc2b299578dba817900a0696cf3ccc4dChris Lattner assert(&BB->getParent()->front() != BB && "Can't Simplify entry block!"); 34501d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner 34601d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner // Remove basic blocks that have no predecessors... which are unreachable. 347d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner if (pred_begin(BB) == pred_end(BB) || 348d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner *pred_begin(BB) == BB && ++pred_begin(BB) == pred_end(BB)) { 34901d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner //cerr << "Removing BB: \n" << BB; 35001d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner 35101d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner // Loop through all of our successors and make sure they know that one 35201d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner // of their predecessors is going away. 35301d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner for_each(succ_begin(BB), succ_end(BB), 35401d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner std::bind2nd(std::mem_fun(&BasicBlock::removePredecessor), BB)); 35501d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner 35601d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner while (!BB->empty()) { 35718961504fc2b299578dba817900a0696cf3ccc4dChris Lattner Instruction &I = BB->back(); 35801d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner // If this instruction is used, replace uses with an arbitrary 35901d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner // constant value. Because control flow can't get here, we don't care 36001d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner // what we replace the value with. Note that since this block is 36101d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner // unreachable, and all values contained within it must dominate their 36201d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner // uses, that all uses will eventually be removed. 36318961504fc2b299578dba817900a0696cf3ccc4dChris Lattner if (!I.use_empty()) 36401d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner // Make all users of this instruction reference the constant instead 36518961504fc2b299578dba817900a0696cf3ccc4dChris Lattner I.replaceAllUsesWith(Constant::getNullValue(I.getType())); 36601d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner 36701d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner // Remove the instruction from the basic block 36818961504fc2b299578dba817900a0696cf3ccc4dChris Lattner BB->getInstList().pop_back(); 36901d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner } 37018961504fc2b299578dba817900a0696cf3ccc4dChris Lattner M->getBasicBlockList().erase(BB); 37101d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner return true; 37201d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner } 37301d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner 374694e37f08a7c09ccc24642532106295cf7b3a1e3Chris Lattner // Check to see if we can constant propagate this terminator instruction 375694e37f08a7c09ccc24642532106295cf7b3a1e3Chris Lattner // away... 376dc3602bf0d27aac80e08ef8823967850acd05a14Chris Lattner Changed |= ConstantFoldTerminator(BB); 377694e37f08a7c09ccc24642532106295cf7b3a1e3Chris Lattner 37846a5f1f6e4a3be3d53b4e0016b78d108a2353f4cChris Lattner // Check to see if this block has no non-phi instructions and only a single 37946a5f1f6e4a3be3d53b4e0016b78d108a2353f4cChris Lattner // successor. If so, replace references to this basic block with references 38046a5f1f6e4a3be3d53b4e0016b78d108a2353f4cChris Lattner // to the successor. 38101d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner succ_iterator SI(succ_begin(BB)); 38201d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner if (SI != succ_end(BB) && ++SI == succ_end(BB)) { // One succ? 38346a5f1f6e4a3be3d53b4e0016b78d108a2353f4cChris Lattner 38446a5f1f6e4a3be3d53b4e0016b78d108a2353f4cChris Lattner BasicBlock::iterator BBI = BB->begin(); // Skip over phi nodes... 38546a5f1f6e4a3be3d53b4e0016b78d108a2353f4cChris Lattner while (isa<PHINode>(*BBI)) ++BBI; 38646a5f1f6e4a3be3d53b4e0016b78d108a2353f4cChris Lattner 38746a5f1f6e4a3be3d53b4e0016b78d108a2353f4cChris Lattner if (BBI->isTerminator()) { // Terminator is the only non-phi instruction! 38801d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner BasicBlock *Succ = *succ_begin(BB); // There is exactly one successor 38901d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner 39001d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner if (Succ != BB) { // Arg, don't hurt infinite loops! 39101d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner // If our successor has PHI nodes, then we need to update them to 39201d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner // include entries for BB's predecessors, not for BB itself. 39301d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner // Be careful though, if this transformation fails (returns true) then 39401d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner // we cannot do this transformation! 39501d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner // 396a3bbcb5b664c1c851b87392119608901b2e1837cMisha Brukman if (!PropagatePredecessorsForPHIs(BB, Succ)) { 39701d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner //cerr << "Killing Trivial BB: \n" << BB; 39818961504fc2b299578dba817900a0696cf3ccc4dChris Lattner std::string OldName = BB->getName(); 39918961504fc2b299578dba817900a0696cf3ccc4dChris Lattner 4003a43837d859bddfdc24bc0c2d87669a6300c7bfeChris Lattner std::vector<BasicBlock*> 4013a43837d859bddfdc24bc0c2d87669a6300c7bfeChris Lattner OldSuccPreds(pred_begin(Succ), pred_end(Succ)); 4023a43837d859bddfdc24bc0c2d87669a6300c7bfeChris Lattner 40346a5f1f6e4a3be3d53b4e0016b78d108a2353f4cChris Lattner // Move all PHI nodes in BB to Succ if they are alive, otherwise 40446a5f1f6e4a3be3d53b4e0016b78d108a2353f4cChris Lattner // delete them. 40546a5f1f6e4a3be3d53b4e0016b78d108a2353f4cChris Lattner while (PHINode *PN = dyn_cast<PHINode>(&BB->front())) 40646a5f1f6e4a3be3d53b4e0016b78d108a2353f4cChris Lattner if (PN->use_empty()) 40746a5f1f6e4a3be3d53b4e0016b78d108a2353f4cChris Lattner BB->getInstList().erase(BB->begin()); // Nuke instruction... 40846a5f1f6e4a3be3d53b4e0016b78d108a2353f4cChris Lattner else { 40946a5f1f6e4a3be3d53b4e0016b78d108a2353f4cChris Lattner // The instruction is alive, so this means that Succ must have 41046a5f1f6e4a3be3d53b4e0016b78d108a2353f4cChris Lattner // *ONLY* had BB as a predecessor, and the PHI node is still valid 4113a43837d859bddfdc24bc0c2d87669a6300c7bfeChris Lattner // now. Simply move it into Succ, because we know that BB 4123a43837d859bddfdc24bc0c2d87669a6300c7bfeChris Lattner // strictly dominated Succ. 41346a5f1f6e4a3be3d53b4e0016b78d108a2353f4cChris Lattner BB->getInstList().remove(BB->begin()); 41446a5f1f6e4a3be3d53b4e0016b78d108a2353f4cChris Lattner Succ->getInstList().push_front(PN); 4153a43837d859bddfdc24bc0c2d87669a6300c7bfeChris Lattner 4163a43837d859bddfdc24bc0c2d87669a6300c7bfeChris Lattner // We need to add new entries for the PHI node to account for 4173a43837d859bddfdc24bc0c2d87669a6300c7bfeChris Lattner // predecessors of Succ that the PHI node does not take into 4183a43837d859bddfdc24bc0c2d87669a6300c7bfeChris Lattner // account. At this point, since we know that BB dominated succ, 4193a43837d859bddfdc24bc0c2d87669a6300c7bfeChris Lattner // this means that we should any newly added incoming edges should 4203a43837d859bddfdc24bc0c2d87669a6300c7bfeChris Lattner // use the PHI node as the value for these edges, because they are 4213a43837d859bddfdc24bc0c2d87669a6300c7bfeChris Lattner // loop back edges. 4223a43837d859bddfdc24bc0c2d87669a6300c7bfeChris Lattner 4233a43837d859bddfdc24bc0c2d87669a6300c7bfeChris Lattner for (unsigned i = 0, e = OldSuccPreds.size(); i != e; ++i) 4243a43837d859bddfdc24bc0c2d87669a6300c7bfeChris Lattner if (OldSuccPreds[i] != BB) 4253a43837d859bddfdc24bc0c2d87669a6300c7bfeChris Lattner PN->addIncoming(PN, OldSuccPreds[i]); 42646a5f1f6e4a3be3d53b4e0016b78d108a2353f4cChris Lattner } 42746a5f1f6e4a3be3d53b4e0016b78d108a2353f4cChris Lattner 4283a43837d859bddfdc24bc0c2d87669a6300c7bfeChris Lattner // Everything that jumped to BB now goes to Succ... 4293a43837d859bddfdc24bc0c2d87669a6300c7bfeChris Lattner BB->replaceAllUsesWith(Succ); 4303a43837d859bddfdc24bc0c2d87669a6300c7bfeChris Lattner 43118961504fc2b299578dba817900a0696cf3ccc4dChris Lattner // Delete the old basic block... 43218961504fc2b299578dba817900a0696cf3ccc4dChris Lattner M->getBasicBlockList().erase(BB); 43301d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner 43418961504fc2b299578dba817900a0696cf3ccc4dChris Lattner if (!OldName.empty() && !Succ->hasName()) // Transfer name if we can 43518961504fc2b299578dba817900a0696cf3ccc4dChris Lattner Succ->setName(OldName); 43601d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner 43701d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner //cerr << "Function after removal: \n" << M; 43801d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner return true; 43901d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner } 44001d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner } 44101d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner } 44201d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner } 44301d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner 44419831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner // If this is a returning block with only PHI nodes in it, fold the return 44519831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner // instruction into any unconditional branch predecessors. 44619831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner if (ReturnInst *RI = dyn_cast<ReturnInst>(BB->getTerminator())) { 44719831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner BasicBlock::iterator BBI = BB->getTerminator(); 44819831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner if (BBI == BB->begin() || isa<PHINode>(--BBI)) { 44919831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner // Find predecessors that end with unconditional branches. 45019831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner std::vector<BasicBlock*> UncondBranchPreds; 45119831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI) { 45219831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner TerminatorInst *PTI = (*PI)->getTerminator(); 45319831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner if (BranchInst *BI = dyn_cast<BranchInst>(PTI)) 45419831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner if (BI->isUnconditional()) 45519831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner UncondBranchPreds.push_back(*PI); 45619831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner } 45719831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner 45819831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner // If we found some, do the transformation! 45919831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner if (!UncondBranchPreds.empty()) { 46019831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner while (!UncondBranchPreds.empty()) { 46119831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner BasicBlock *Pred = UncondBranchPreds.back(); 46219831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner UncondBranchPreds.pop_back(); 46319831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner Instruction *UncondBranch = Pred->getTerminator(); 46419831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner // Clone the return and add it to the end of the predecessor. 46519831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner Instruction *NewRet = RI->clone(); 46619831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner Pred->getInstList().push_back(NewRet); 46719831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner 46819831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner // If the return instruction returns a value, and if the value was a 46919831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner // PHI node in "BB", propagate the right value into the return. 47019831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner if (NewRet->getNumOperands() == 1) 47119831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner if (PHINode *PN = dyn_cast<PHINode>(NewRet->getOperand(0))) 47219831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner if (PN->getParent() == BB) 47319831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner NewRet->setOperand(0, PN->getIncomingValueForBlock(Pred)); 47419831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner // Update any PHI nodes in the returning block to realize that we no 47519831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner // longer branch to them. 47619831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner BB->removePredecessor(Pred); 47719831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner Pred->getInstList().erase(UncondBranch); 47819831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner } 47919831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner 48019831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner // If we eliminated all predecessors of the block, delete the block now. 48119831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner if (pred_begin(BB) == pred_end(BB)) 48219831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner // We know there are no successors, so just nuke the block. 48319831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner M->getBasicBlockList().erase(BB); 48419831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner 48519831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner return true; 48619831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner } 48719831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner } 488e14ea0804afba2ac5824507571a220d05b0aa21dChris Lattner } else if (UnwindInst *UI = dyn_cast<UnwindInst>(BB->begin())) { 489e14ea0804afba2ac5824507571a220d05b0aa21dChris Lattner // Check to see if the first instruction in this block is just an unwind. 490e14ea0804afba2ac5824507571a220d05b0aa21dChris Lattner // If so, replace any invoke instructions which use this as an exception 491e14ea0804afba2ac5824507571a220d05b0aa21dChris Lattner // destination with call instructions. 492e14ea0804afba2ac5824507571a220d05b0aa21dChris Lattner // 493e14ea0804afba2ac5824507571a220d05b0aa21dChris Lattner std::vector<BasicBlock*> Preds(pred_begin(BB), pred_end(BB)); 494e14ea0804afba2ac5824507571a220d05b0aa21dChris Lattner while (!Preds.empty()) { 495e14ea0804afba2ac5824507571a220d05b0aa21dChris Lattner BasicBlock *Pred = Preds.back(); 496e14ea0804afba2ac5824507571a220d05b0aa21dChris Lattner if (InvokeInst *II = dyn_cast<InvokeInst>(Pred->getTerminator())) 497e14ea0804afba2ac5824507571a220d05b0aa21dChris Lattner if (II->getUnwindDest() == BB) { 498e14ea0804afba2ac5824507571a220d05b0aa21dChris Lattner // Insert a new branch instruction before the invoke, because this 499e14ea0804afba2ac5824507571a220d05b0aa21dChris Lattner // is now a fall through... 500e14ea0804afba2ac5824507571a220d05b0aa21dChris Lattner BranchInst *BI = new BranchInst(II->getNormalDest(), II); 501e14ea0804afba2ac5824507571a220d05b0aa21dChris Lattner Pred->getInstList().remove(II); // Take out of symbol table 502e14ea0804afba2ac5824507571a220d05b0aa21dChris Lattner 503e14ea0804afba2ac5824507571a220d05b0aa21dChris Lattner // Insert the call now... 504e14ea0804afba2ac5824507571a220d05b0aa21dChris Lattner std::vector<Value*> Args(II->op_begin()+3, II->op_end()); 505e14ea0804afba2ac5824507571a220d05b0aa21dChris Lattner CallInst *CI = new CallInst(II->getCalledValue(), Args, 506e14ea0804afba2ac5824507571a220d05b0aa21dChris Lattner II->getName(), BI); 507e14ea0804afba2ac5824507571a220d05b0aa21dChris Lattner // If the invoke produced a value, the Call now does instead 508e14ea0804afba2ac5824507571a220d05b0aa21dChris Lattner II->replaceAllUsesWith(CI); 509e14ea0804afba2ac5824507571a220d05b0aa21dChris Lattner delete II; 510e14ea0804afba2ac5824507571a220d05b0aa21dChris Lattner Changed = true; 511e14ea0804afba2ac5824507571a220d05b0aa21dChris Lattner } 512e14ea0804afba2ac5824507571a220d05b0aa21dChris Lattner 513e14ea0804afba2ac5824507571a220d05b0aa21dChris Lattner Preds.pop_back(); 514e14ea0804afba2ac5824507571a220d05b0aa21dChris Lattner } 515d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner } else if (SwitchInst *SI = dyn_cast<SwitchInst>(BB->begin())) { 516d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner // If the only instruction in this block is a switch instruction, see if we 517d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner // can fold the switch instruction into a switch in a predecessor block. 518d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner std::vector<BasicBlock*> Preds(pred_begin(BB), pred_end(BB)); 519d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner while (!Preds.empty()) { 520d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner BasicBlock *Pred = Preds.back(); 521d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner Preds.pop_back(); 522d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner 523d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner // If the two blocks are switching on the same value, we can merge this 524d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner // switch into the predecessor's switch. 525d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner if (SwitchInst *PSI = dyn_cast<SwitchInst>(Pred->getTerminator())) 526d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner if (PSI->getCondition() == SI->getCondition() && 527d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner SafeToMergeTerminators(SI, PSI)) { 528d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner // Figure out which 'cases' to copy from SI to PSI. 529d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner std::vector<std::pair<Constant*, BasicBlock*> > Cases; 530d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner BasicBlock *NewDefault = 0; 531d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner if (PSI->getDefaultDest() == BB) { 532d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner // If this is the default destination from PSI, only the edges in SI 533d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner // that don't occur in PSI, or that branch to BB will be activated. 534d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner std::set<Constant*> PSIHandled; 535d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner for (unsigned i = 1, e = PSI->getNumSuccessors(); i != e; ++i) 536d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner if (PSI->getSuccessor(i) != BB) 537d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner PSIHandled.insert(PSI->getCaseValue(i)); 538d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner else { 539d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner // This entry will be replaced. 540d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner PSI->removeCase(i); 541d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner --i; --e; 542d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner } 543d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner 544d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner NewDefault = SI->getDefaultDest(); 545d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner for (unsigned i = 1, e = SI->getNumSuccessors(); i != e; ++i) { 546d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner Constant *C = SI->getCaseValue(i); 547d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner if (!PSIHandled.count(C)) 548d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner Cases.push_back(std::make_pair(C, SI->getSuccessor(i))); 549d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner } 550d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner 551d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner } else { 552d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner // If this is not the default destination from PSI, only the edges 553d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner // in SI that occur in PSI with a destination of BB will be 554d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner // activated. 555d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner std::set<Constant*> PSIHandled; 556d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner for (unsigned i = 1, e = PSI->getNumSuccessors(); i != e; ++i) 557d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner if (PSI->getSuccessor(i) == BB) { 558d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner // We know that BB doesn't have any PHI nodes in it, so just 559d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner // drop the edges. 560d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner PSIHandled.insert(PSI->getCaseValue(i)); 561d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner PSI->removeCase(i); 562d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner --i; --e; 563d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner } 564d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner 565d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner // Okay, now we know which constants were sent to BB from the 566d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner // predecessor. Figure out where they will all go now. 567d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner for (unsigned i = 1, e = SI->getNumSuccessors(); i != e; ++i) { 568d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner Constant *C = SI->getCaseValue(i); 569d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner if (PSIHandled.count(C)) { 570d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner // If this is one we are capable of getting... 571d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner Cases.push_back(std::make_pair(C, SI->getSuccessor(i))); 572d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner PSIHandled.erase(C); // This constant is taken care of 573d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner } 574d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner } 575d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner 576d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner // If there are any constants vectored to BB that SI doesn't handle, 577d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner // they must go to the default destination of SI. 578d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner for (std::set<Constant*>::iterator I = PSIHandled.begin(), 579d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner E = PSIHandled.end(); I != E; ++I) 580d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner Cases.push_back(std::make_pair(*I, SI->getDefaultDest())); 581d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner } 582d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner 583d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner // Okay, at this point, we know which cases need to be added to the 584d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner // PSI switch and which destinations they go to. If PSI needs its 585d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner // default destination changed, NewDefault is set. Start changing 586d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner // stuff now. 587d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner if (NewDefault) { 588d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner AddPredecessorToBlock(NewDefault, Pred, BB); 589d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner PSI->setSuccessor(0, NewDefault); 590d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner } 591d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner 592d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner // Okay, add all of the cases now. 593d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner for (unsigned i = 0, e = Cases.size(); i != e; ++i) { 594d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner AddPredecessorToBlock(Cases[i].second, Pred, BB); 595d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner PSI->addCase(Cases[i].first, Cases[i].second); 596d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner } 597d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner 598d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner // Okay, last check. If BB is still a successor of PSI, then we must 599d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner // have an infinite loop case. If so, add an infinitely looping block 600d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner // to handle the case to preserve the behavior of the code. 601d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner BasicBlock *InfLoopBlock = 0; 602d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner for (unsigned i = 0, e = PSI->getNumSuccessors(); i != e; ++i) 603d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner if (PSI->getSuccessor(i) == BB) { 604d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner if (InfLoopBlock == 0) { 605d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner // Insert it at the end of the loop, because it's either code, 606d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner // or it won't matter if it's hot. :) 607d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner InfLoopBlock = new BasicBlock("infloop", BB->getParent()); 608d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner new BranchInst(InfLoopBlock, InfLoopBlock); 609d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner } 610d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner PSI->setSuccessor(i, InfLoopBlock); 611d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner } 612d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner 613d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner Changed = true; 614d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner } 615d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner } 616d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner 617d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner // If we removed all predecessors of this block, recursively call 618d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner // SimplifyCFG to remove it. 619d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner if (pred_begin(BB) == pred_end(BB)) 620d52c261cf801331bebda9711acd54c7c5377a6bdChris Lattner return SimplifyCFG(BB); 62119831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner } 62219831ec8531b0710629c1b0a8c0323e70ae0ef07Chris Lattner 62301d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner // Merge basic blocks into their predecessor if there is only one distinct 62401d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner // pred, and if there is only one distinct successor of the predecessor, and 62501d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner // if there are no PHI nodes. 62601d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner // 6272355f948c59a2b4a78667d6898333524f9b78f27Chris Lattner pred_iterator PI(pred_begin(BB)), PE(pred_end(BB)); 6282355f948c59a2b4a78667d6898333524f9b78f27Chris Lattner BasicBlock *OnlyPred = *PI++; 6292355f948c59a2b4a78667d6898333524f9b78f27Chris Lattner for (; PI != PE; ++PI) // Search all predecessors, see if they are all same 6302355f948c59a2b4a78667d6898333524f9b78f27Chris Lattner if (*PI != OnlyPred) { 6312355f948c59a2b4a78667d6898333524f9b78f27Chris Lattner OnlyPred = 0; // There are multiple different predecessors... 6322355f948c59a2b4a78667d6898333524f9b78f27Chris Lattner break; 6332355f948c59a2b4a78667d6898333524f9b78f27Chris Lattner } 6342355f948c59a2b4a78667d6898333524f9b78f27Chris Lattner 6352355f948c59a2b4a78667d6898333524f9b78f27Chris Lattner BasicBlock *OnlySucc = 0; 6362355f948c59a2b4a78667d6898333524f9b78f27Chris Lattner if (OnlyPred && OnlyPred != BB && // Don't break self loops 6372355f948c59a2b4a78667d6898333524f9b78f27Chris Lattner OnlyPred->getTerminator()->getOpcode() != Instruction::Invoke) { 6382355f948c59a2b4a78667d6898333524f9b78f27Chris Lattner // Check to see if there is only one distinct successor... 6392355f948c59a2b4a78667d6898333524f9b78f27Chris Lattner succ_iterator SI(succ_begin(OnlyPred)), SE(succ_end(OnlyPred)); 6402355f948c59a2b4a78667d6898333524f9b78f27Chris Lattner OnlySucc = BB; 6412355f948c59a2b4a78667d6898333524f9b78f27Chris Lattner for (; SI != SE; ++SI) 6422355f948c59a2b4a78667d6898333524f9b78f27Chris Lattner if (*SI != OnlySucc) { 6432355f948c59a2b4a78667d6898333524f9b78f27Chris Lattner OnlySucc = 0; // There are multiple distinct successors! 64401d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner break; 64501d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner } 6462355f948c59a2b4a78667d6898333524f9b78f27Chris Lattner } 64701d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner 6482355f948c59a2b4a78667d6898333524f9b78f27Chris Lattner if (OnlySucc) { 6492355f948c59a2b4a78667d6898333524f9b78f27Chris Lattner //cerr << "Merging: " << BB << "into: " << OnlyPred; 6502355f948c59a2b4a78667d6898333524f9b78f27Chris Lattner TerminatorInst *Term = OnlyPred->getTerminator(); 65101d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner 6522355f948c59a2b4a78667d6898333524f9b78f27Chris Lattner // Resolve any PHI nodes at the start of the block. They are all 6532355f948c59a2b4a78667d6898333524f9b78f27Chris Lattner // guaranteed to have exactly one entry if they exist, unless there are 6542355f948c59a2b4a78667d6898333524f9b78f27Chris Lattner // multiple duplicate (but guaranteed to be equal) entries for the 6552355f948c59a2b4a78667d6898333524f9b78f27Chris Lattner // incoming edges. This occurs when there are multiple edges from 6562355f948c59a2b4a78667d6898333524f9b78f27Chris Lattner // OnlyPred to OnlySucc. 6572355f948c59a2b4a78667d6898333524f9b78f27Chris Lattner // 6582355f948c59a2b4a78667d6898333524f9b78f27Chris Lattner while (PHINode *PN = dyn_cast<PHINode>(&BB->front())) { 6592355f948c59a2b4a78667d6898333524f9b78f27Chris Lattner PN->replaceAllUsesWith(PN->getIncomingValue(0)); 6602355f948c59a2b4a78667d6898333524f9b78f27Chris Lattner BB->getInstList().pop_front(); // Delete the phi node... 6612355f948c59a2b4a78667d6898333524f9b78f27Chris Lattner } 66291b65c0b42b3d5dece246bdb366441d6f5593396Chris Lattner 6632355f948c59a2b4a78667d6898333524f9b78f27Chris Lattner // Delete the unconditional branch from the predecessor... 6642355f948c59a2b4a78667d6898333524f9b78f27Chris Lattner OnlyPred->getInstList().pop_back(); 66501d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner 6662355f948c59a2b4a78667d6898333524f9b78f27Chris Lattner // Move all definitions in the successor to the predecessor... 6672355f948c59a2b4a78667d6898333524f9b78f27Chris Lattner OnlyPred->getInstList().splice(OnlyPred->end(), BB->getInstList()); 66818961504fc2b299578dba817900a0696cf3ccc4dChris Lattner 6692355f948c59a2b4a78667d6898333524f9b78f27Chris Lattner // Make all PHI nodes that referred to BB now refer to Pred as their 6702355f948c59a2b4a78667d6898333524f9b78f27Chris Lattner // source... 6712355f948c59a2b4a78667d6898333524f9b78f27Chris Lattner BB->replaceAllUsesWith(OnlyPred); 67218961504fc2b299578dba817900a0696cf3ccc4dChris Lattner 6732355f948c59a2b4a78667d6898333524f9b78f27Chris Lattner std::string OldName = BB->getName(); 67418961504fc2b299578dba817900a0696cf3ccc4dChris Lattner 6752355f948c59a2b4a78667d6898333524f9b78f27Chris Lattner // Erase basic block from the function... 6762355f948c59a2b4a78667d6898333524f9b78f27Chris Lattner M->getBasicBlockList().erase(BB); 67718961504fc2b299578dba817900a0696cf3ccc4dChris Lattner 6782355f948c59a2b4a78667d6898333524f9b78f27Chris Lattner // Inherit predecessors name if it exists... 6792355f948c59a2b4a78667d6898333524f9b78f27Chris Lattner if (!OldName.empty() && !OnlyPred->hasName()) 6802355f948c59a2b4a78667d6898333524f9b78f27Chris Lattner OnlyPred->setName(OldName); 68101d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner 6822355f948c59a2b4a78667d6898333524f9b78f27Chris Lattner return true; 68301d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner } 684723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner 6850d56008f53587531718ec36af82cc24576580b36Chris Lattner for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI) 6860d56008f53587531718ec36af82cc24576580b36Chris Lattner if (BranchInst *BI = dyn_cast<BranchInst>((*PI)->getTerminator())) 6870d56008f53587531718ec36af82cc24576580b36Chris Lattner // Change br (X == 0 | X == 1), T, F into a switch instruction. 6880d56008f53587531718ec36af82cc24576580b36Chris Lattner if (BI->isConditional() && isa<Instruction>(BI->getCondition())) { 6890d56008f53587531718ec36af82cc24576580b36Chris Lattner Instruction *Cond = cast<Instruction>(BI->getCondition()); 6900d56008f53587531718ec36af82cc24576580b36Chris Lattner // If this is a bunch of seteq's or'd together, or if it's a bunch of 6910d56008f53587531718ec36af82cc24576580b36Chris Lattner // 'setne's and'ed together, collect them. 6920d56008f53587531718ec36af82cc24576580b36Chris Lattner Value *CompVal = 0; 6930d56008f53587531718ec36af82cc24576580b36Chris Lattner std::vector<Constant*> Values; 6940d56008f53587531718ec36af82cc24576580b36Chris Lattner bool TrueWhenEqual = GatherValueComparisons(Cond, CompVal, Values); 6950d56008f53587531718ec36af82cc24576580b36Chris Lattner if (CompVal && CompVal->getType()->isInteger()) { 6960d56008f53587531718ec36af82cc24576580b36Chris Lattner // There might be duplicate constants in the list, which the switch 6970d56008f53587531718ec36af82cc24576580b36Chris Lattner // instruction can't handle, remove them now. 6980d56008f53587531718ec36af82cc24576580b36Chris Lattner std::sort(Values.begin(), Values.end()); 6990d56008f53587531718ec36af82cc24576580b36Chris Lattner Values.erase(std::unique(Values.begin(), Values.end()), Values.end()); 7000d56008f53587531718ec36af82cc24576580b36Chris Lattner 7010d56008f53587531718ec36af82cc24576580b36Chris Lattner // Figure out which block is which destination. 7020d56008f53587531718ec36af82cc24576580b36Chris Lattner BasicBlock *DefaultBB = BI->getSuccessor(1); 7030d56008f53587531718ec36af82cc24576580b36Chris Lattner BasicBlock *EdgeBB = BI->getSuccessor(0); 7040d56008f53587531718ec36af82cc24576580b36Chris Lattner if (!TrueWhenEqual) std::swap(DefaultBB, EdgeBB); 7050d56008f53587531718ec36af82cc24576580b36Chris Lattner 7060d56008f53587531718ec36af82cc24576580b36Chris Lattner // Create the new switch instruction now. 7070d56008f53587531718ec36af82cc24576580b36Chris Lattner SwitchInst *New = new SwitchInst(CompVal, DefaultBB, BI); 7080d56008f53587531718ec36af82cc24576580b36Chris Lattner 7090d56008f53587531718ec36af82cc24576580b36Chris Lattner // Add all of the 'cases' to the switch instruction. 7100d56008f53587531718ec36af82cc24576580b36Chris Lattner for (unsigned i = 0, e = Values.size(); i != e; ++i) 7110d56008f53587531718ec36af82cc24576580b36Chris Lattner New->addCase(Values[i], EdgeBB); 7120d56008f53587531718ec36af82cc24576580b36Chris Lattner 7130d56008f53587531718ec36af82cc24576580b36Chris Lattner // We added edges from PI to the EdgeBB. As such, if there were any 7140d56008f53587531718ec36af82cc24576580b36Chris Lattner // PHI nodes in EdgeBB, they need entries to be added corresponding to 7150d56008f53587531718ec36af82cc24576580b36Chris Lattner // the number of edges added. 7160d56008f53587531718ec36af82cc24576580b36Chris Lattner for (BasicBlock::iterator BBI = EdgeBB->begin(); 7170d56008f53587531718ec36af82cc24576580b36Chris Lattner PHINode *PN = dyn_cast<PHINode>(BBI); ++BBI) { 7180d56008f53587531718ec36af82cc24576580b36Chris Lattner Value *InVal = PN->getIncomingValueForBlock(*PI); 7190d56008f53587531718ec36af82cc24576580b36Chris Lattner for (unsigned i = 0, e = Values.size()-1; i != e; ++i) 7200d56008f53587531718ec36af82cc24576580b36Chris Lattner PN->addIncoming(InVal, *PI); 7210d56008f53587531718ec36af82cc24576580b36Chris Lattner } 7220d56008f53587531718ec36af82cc24576580b36Chris Lattner 7230d56008f53587531718ec36af82cc24576580b36Chris Lattner // Erase the old branch instruction. 7240d56008f53587531718ec36af82cc24576580b36Chris Lattner (*PI)->getInstList().erase(BI); 7250d56008f53587531718ec36af82cc24576580b36Chris Lattner 7260d56008f53587531718ec36af82cc24576580b36Chris Lattner // Erase the potentially condition tree that was used to computed the 7270d56008f53587531718ec36af82cc24576580b36Chris Lattner // branch condition. 7280d56008f53587531718ec36af82cc24576580b36Chris Lattner ErasePossiblyDeadInstructionTree(Cond); 7290d56008f53587531718ec36af82cc24576580b36Chris Lattner return true; 7300d56008f53587531718ec36af82cc24576580b36Chris Lattner } 7310d56008f53587531718ec36af82cc24576580b36Chris Lattner } 7320d56008f53587531718ec36af82cc24576580b36Chris Lattner 733723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // If there is a trivial two-entry PHI node in this basic block, and we can 734723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // eliminate it, do so now. 735723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner if (PHINode *PN = dyn_cast<PHINode>(BB->begin())) 736723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner if (PN->getNumIncomingValues() == 2) { 737723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // Ok, this is a two entry PHI node. Check to see if this is a simple "if 738723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // statement", which has a very simple dominance structure. Basically, we 739723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // are trying to find the condition that is being branched on, which 740723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // subsequently causes this merge to happen. We really want control 741723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // dependence information for this check, but simplifycfg can't keep it up 742723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // to date, and this catches most of the cases we care about anyway. 743723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // 744723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner BasicBlock *IfTrue, *IfFalse; 745723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner if (Value *IfCond = GetIfCondition(BB, IfTrue, IfFalse)) { 746723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner //std::cerr << "FOUND IF CONDITION! " << *IfCond << " T: " 747723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // << IfTrue->getName() << " F: " << IfFalse->getName() << "\n"; 748723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner 749723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // Figure out where to insert instructions as necessary. 750723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner BasicBlock::iterator AfterPHIIt = BB->begin(); 751723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner while (isa<PHINode>(AfterPHIIt)) ++AfterPHIIt; 752723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner 753723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner BasicBlock::iterator I = BB->begin(); 754723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner while (PHINode *PN = dyn_cast<PHINode>(I)) { 755723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner ++I; 756723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner 757723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // If we can eliminate this PHI by directly computing it based on the 758723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // condition, do so now. We can't eliminate PHI nodes where the 759723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // incoming values are defined in the conditional parts of the branch, 760723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // so check for this. 761723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // 762723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner if (DominatesMergePoint(PN->getIncomingValue(0), BB) && 763723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner DominatesMergePoint(PN->getIncomingValue(1), BB)) { 764723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner Value *TrueVal = 765723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner PN->getIncomingValue(PN->getIncomingBlock(0) == IfFalse); 766723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner Value *FalseVal = 767723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner PN->getIncomingValue(PN->getIncomingBlock(0) == IfTrue); 768723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner 769723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // FIXME: when we have a 'select' statement, we can be completely 770723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // generic and clean here and let the instcombine pass clean up 771723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // after us, by folding the select instructions away when possible. 772723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // 773723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner if (TrueVal == FalseVal) { 774723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // Degenerate case... 775723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner PN->replaceAllUsesWith(TrueVal); 776723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner BB->getInstList().erase(PN); 777723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner Changed = true; 778723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner } else if (isa<ConstantBool>(TrueVal) && 779723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner isa<ConstantBool>(FalseVal)) { 780723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner if (TrueVal == ConstantBool::True) { 781723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // The PHI node produces the same thing as the condition. 782723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner PN->replaceAllUsesWith(IfCond); 783723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner } else { 784723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // The PHI node produces the inverse of the condition. Insert a 785723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // "NOT" instruction, which is really a XOR. 786723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner Value *InverseCond = 787723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner BinaryOperator::createNot(IfCond, IfCond->getName()+".inv", 788723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner AfterPHIIt); 789723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner PN->replaceAllUsesWith(InverseCond); 790723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner } 791723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner BB->getInstList().erase(PN); 792723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner Changed = true; 793723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner } else if (isa<ConstantInt>(TrueVal) && isa<ConstantInt>(FalseVal)){ 794723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // If this is a PHI of two constant integers, we insert a cast of 795723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // the boolean to the integer type in question, giving us 0 or 1. 796723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // Then we multiply this by the difference of the two constants, 797723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // giving us 0 if false, and the difference if true. We add this 798723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // result to the base constant, giving us our final value. We 799723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // rely on the instruction combiner to eliminate many special 800723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // cases, like turning multiplies into shifts when possible. 801723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner std::string Name = PN->getName(); PN->setName(""); 802723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner Value *TheCast = new CastInst(IfCond, TrueVal->getType(), 803723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner Name, AfterPHIIt); 804723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner Constant *TheDiff = ConstantExpr::get(Instruction::Sub, 805723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner cast<Constant>(TrueVal), 806723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner cast<Constant>(FalseVal)); 807723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner Value *V = TheCast; 808723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner if (TheDiff != ConstantInt::get(TrueVal->getType(), 1)) 809723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner V = BinaryOperator::create(Instruction::Mul, TheCast, 810723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner TheDiff, TheCast->getName()+".scale", 811723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner AfterPHIIt); 812723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner if (!cast<Constant>(FalseVal)->isNullValue()) 813723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner V = BinaryOperator::create(Instruction::Add, V, FalseVal, 814723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner V->getName()+".offs", AfterPHIIt); 815723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner PN->replaceAllUsesWith(V); 816723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner BB->getInstList().erase(PN); 817723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner Changed = true; 818723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner } else if (isa<ConstantInt>(FalseVal) && 819723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner cast<Constant>(FalseVal)->isNullValue()) { 820723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // If the false condition is an integral zero value, we can 821723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // compute the PHI by multiplying the condition by the other 822723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // value. 823723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner std::string Name = PN->getName(); PN->setName(""); 824723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner Value *TheCast = new CastInst(IfCond, TrueVal->getType(), 825723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner Name+".c", AfterPHIIt); 826723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner Value *V = BinaryOperator::create(Instruction::Mul, TrueVal, 827723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner TheCast, Name, AfterPHIIt); 828723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner PN->replaceAllUsesWith(V); 829723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner BB->getInstList().erase(PN); 830723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner Changed = true; 831723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner } else if (isa<ConstantInt>(TrueVal) && 832723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner cast<Constant>(TrueVal)->isNullValue()) { 833723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // If the true condition is an integral zero value, we can compute 834723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // the PHI by multiplying the inverse condition by the other 835723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner // value. 836723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner std::string Name = PN->getName(); PN->setName(""); 837723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner Value *NotCond = BinaryOperator::createNot(IfCond, Name+".inv", 838723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner AfterPHIIt); 839723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner Value *TheCast = new CastInst(NotCond, TrueVal->getType(), 840723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner Name+".inv", AfterPHIIt); 841723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner Value *V = BinaryOperator::create(Instruction::Mul, FalseVal, 842723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner TheCast, Name, AfterPHIIt); 843723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner PN->replaceAllUsesWith(V); 844723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner BB->getInstList().erase(PN); 845723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner Changed = true; 846723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner } 847723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner } 848723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner } 849723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner } 850723c66d4c0aa081ea8fa221617c5097e31333e6cChris Lattner } 85101d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner 852694e37f08a7c09ccc24642532106295cf7b3a1e3Chris Lattner return Changed; 85301d1ee3a4c4153c80c3c415e4612db6c27e37acbChris Lattner} 854