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Allow folding of basic blocks that have PHI nodes in them, fixing "bug": 

test/Regression/Transforms/SimplifyCFG/2002-06-24-PHINode.ll

llvm-svn: 3128
This commit is contained in:
Chris Lattner 2002-07-29 21:26:30 +00:00
parent 59aa81c78e
commit 1cec4d90cd
1 changed files with 11 additions and 1 deletions
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12
llvm/lib/Transforms/Utils/SimplifyCFG.cpp
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@ -143,7 +143,7 @@ bool SimplifyCFG(BasicBlock *BB) {
// pred, and if there is only one distinct successor of the predecessor, and
// if there are no PHI nodes.
//
if (!isa<PHINode>(BB->front()) && !BB->hasConstantReferences()) {
if (!BB->hasConstantReferences()) {
pred_iterator PI(pred_begin(BB)), PE(pred_end(BB));
BasicBlock *OnlyPred = *PI++;
for (; PI != PE; ++PI) // Search all predecessors, see if they are all same
@ -168,6 +168,16 @@ bool SimplifyCFG(BasicBlock *BB) {
//cerr << "Merging: " << BB << "into: " << OnlyPred;
TerminatorInst *Term = OnlyPred->getTerminator();
// Resolve any PHI nodes at the start of the block. They are all
// guaranteed to have exactly one entry if they exist.
//
while (PHINode *PN = dyn_cast<PHINode>(&BB->front())) {
assert(PN->getNumIncomingValues() == 1 && "Only one pred!");
PN->replaceAllUsesWith(PN->getIncomingValue(0));
BB->getInstList().pop_front(); // Delete the phi node...
}
// Delete the unconditional branch from the predecessor...
OnlyPred->getInstList().pop_back();