diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp index 30e143dec46..0f8ae0c6bdb 100644 --- a/lib/Transforms/Scalar/InstructionCombining.cpp +++ b/lib/Transforms/Scalar/InstructionCombining.cpp @@ -610,10 +610,19 @@ Instruction *InstCombiner::visitPHINode(PHINode &PN) { // Otherwise if all of the incoming values are the same for the PHI, replace // the PHI node with the incoming value. // - Value *InVal = PN.getIncomingValue(0); - for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) - if (PN.getIncomingValue(i) != InVal) - return 0; // Not the same, bail out. + Value *InVal = 0; + for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i) + if (PN.getIncomingValue(i) != &PN) // Not the PHI node itself... + if (InVal && PN.getIncomingValue(i) != InVal) + return 0; // Not the same, bail out. + else + InVal = PN.getIncomingValue(i); + + // The only case that could cause InVal to be null is if we have a PHI node + // that only has entries for itself. In this case, there is no entry into the + // loop, so kill the PHI. + // + if (InVal == 0) InVal = Constant::getNullValue(PN.getType()); // All of the incoming values are the same, replace the PHI node now. return ReplaceInstUsesWith(PN, InVal);