Don't crash on: X = phi (X, X).

This fixes PR584 and Transforms/SimplifyCFG/2005-06-16-PHICrash.ll


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@22232 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2005-06-17 01:45:53 +00:00
parent bff44407e8
commit 0289929c62

View File

@ -1461,12 +1461,15 @@ bool llvm::SimplifyCFG(BasicBlock *BB) {
BasicBlock::iterator AfterPHIIt = BB->begin();
while (isa<PHINode>(AfterPHIIt)) {
PHINode *PN = cast<PHINode>(AfterPHIIt++);
if (PN->getIncomingValue(0) == PN->getIncomingValue(1))
PN->replaceAllUsesWith(PN->getIncomingValue(0));
else if (!DominatesMergePoint(PN->getIncomingValue(0), BB,
&AggressiveInsts) ||
!DominatesMergePoint(PN->getIncomingValue(1), BB,
&AggressiveInsts)) {
if (PN->getIncomingValue(0) == PN->getIncomingValue(1)) {
if (PN->getIncomingValue(0) != PN)
PN->replaceAllUsesWith(PN->getIncomingValue(0));
else
PN->replaceAllUsesWith(UndefValue::get(PN->getType()));
} else if (!DominatesMergePoint(PN->getIncomingValue(0), BB,
&AggressiveInsts) ||
!DominatesMergePoint(PN->getIncomingValue(1), BB,
&AggressiveInsts)) {
CanPromote = false;
break;
}