diff --git a/lib/Transforms/Utils/SimplifyCFG.cpp b/lib/Transforms/Utils/SimplifyCFG.cpp index 4c3ceed8525..7a56c508643 100644 --- a/lib/Transforms/Utils/SimplifyCFG.cpp +++ b/lib/Transforms/Utils/SimplifyCFG.cpp @@ -105,20 +105,21 @@ static void AddPredecessorToBlock(BasicBlock *Succ, BasicBlock *NewPred, } -/// GetIfCondition - Given a basic block (BB) with two predecessors (and -/// presumably PHI nodes in it), check to see if the merge at this block is due +/// GetIfCondition - Given a basic block (BB) with two predecessors (and at +/// least one PHI node in it), check to see if the merge at this block is due /// to an "if condition". If so, return the boolean condition that determines /// which entry into BB will be taken. Also, return by references the block /// that will be entered from if the condition is true, and the block that will /// be entered if the condition is false. /// /// -static Value *GetIfCondition(BasicBlock *BB, - BasicBlock *&IfTrue, BasicBlock *&IfFalse) { - assert(std::distance(pred_begin(BB), pred_end(BB)) == 2 && +static Value *GetIfCondition(BasicBlock *BB, BasicBlock *&IfTrue, + BasicBlock *&IfFalse) { + PHINode *SomePHI = cast(BB->begin()); + assert(SomePHI->getNumIncomingValues() == 2 && "Function can only handle blocks with 2 predecessors!"); - BasicBlock *Pred1 = *pred_begin(BB); - BasicBlock *Pred2 = *++pred_begin(BB); + BasicBlock *Pred1 = SomePHI->getIncomingBlock(0); + BasicBlock *Pred2 = SomePHI->getIncomingBlock(1); // We can only handle branches. Other control flow will be lowered to // branches if possible anyway. @@ -1147,14 +1148,13 @@ static bool FoldCondBranchOnPHI(BranchInst *BI, const TargetData *TD) { /// FoldTwoEntryPHINode - Given a BB that starts with the specified two-entry /// PHI node, see if we can eliminate it. -static bool FoldTwoEntryPHINode(PHINode *PN) { +static bool FoldTwoEntryPHINode(PHINode *PN, const TargetData *TD) { // Ok, this is a two entry PHI node. Check to see if this is a simple "if // statement", which has a very simple dominance structure. Basically, we // are trying to find the condition that is being branched on, which // subsequently causes this merge to happen. We really want control // dependence information for this check, but simplifycfg can't keep it up // to date, and this catches most of the cases we care about anyway. - // BasicBlock *BB = PN->getParent(); BasicBlock *IfTrue, *IfFalse; Value *IfCond = GetIfCondition(BB, IfTrue, IfFalse); @@ -1247,10 +1247,19 @@ static bool FoldTwoEntryPHINode(PHINode *PN) { Value *TrueVal = PN->getIncomingValue(PN->getIncomingBlock(0) == IfFalse); Value *FalseVal = PN->getIncomingValue(PN->getIncomingBlock(0) == IfTrue); - Value *NV = SelectInst::Create(IfCond, TrueVal, FalseVal, "", AfterPHIIt); + Value *NV; + if (Value *V = SimplifySelectInst(IfCond, TrueVal, FalseVal, TD)) + NV = V; + else if (TrueVal->getType()->isIntegerTy(1) && isa(TrueVal) && + cast(TrueVal)->isOne()) { + if (Value *V = SimplifyOrInst(IfCond, FalseVal, TD)) + NV = V; + else + NV = BinaryOperator::CreateOr(IfCond, FalseVal, "", AfterPHIIt); + } else + NV = SelectInst::Create(IfCond, TrueVal, FalseVal, "", AfterPHIIt); PN->replaceAllUsesWith(NV); NV->takeName(PN); - PN->eraseFromParent(); } return true; @@ -2415,7 +2424,7 @@ bool SimplifyCFGOpt::run(BasicBlock *BB) { // eliminate it, do so now. if (PHINode *PN = dyn_cast(BB->begin())) if (PN->getNumIncomingValues() == 2) - Changed |= FoldTwoEntryPHINode(PN); + Changed |= FoldTwoEntryPHINode(PN, TD); if (BranchInst *BI = dyn_cast(BB->getTerminator())) { if (BI->isUnconditional()) {