// PHINode simplification
//
Instruction *InstCombiner::visitPHINode(PHINode &PN) {
- // If the PHI node only has one incoming value, eliminate the PHI node...
- if (PN.getNumIncomingValues() == 1)
- return ReplaceInstUsesWith(PN, PN.getIncomingValue(0));
-
- // Otherwise if all of the incoming values are the same for the PHI, replace
- // the PHI node with the incoming value.
- //
- 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);
+ if (Value *V = hasConstantValue(&PN))
+ return ReplaceInstUsesWith(PN, V);
+ return 0;
}