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Do not insert one entry PHI nodes in split exit blocks! 

llvm-svn: 10348
This commit is contained in:
Chris Lattner 2003-12-09 23:12:55 +00:00
parent ddc088a9e4
commit 6c237bcdf2
1 changed files with 24 additions and 14 deletions
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36
llvm/lib/Transforms/Scalar/LoopSimplify.cpp
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@ -162,21 +162,31 @@ BasicBlock *LoopSimplify::SplitBlockPredecessors(BasicBlock *BB,
// incoming edges in BB into new PHI nodes in NewBB.
//
if (!Preds.empty()) { // Is the loop not obviously dead?
for (BasicBlock::iterator I = BB->begin();
PHINode *PN = dyn_cast<PHINode>(I); ++I) {
// Create the new PHI node, insert it into NewBB at the end of the block
PHINode *NewPHI = new PHINode(PN->getType(), PN->getName()+".ph", BI);
// Move all of the edges from blocks outside the loop to the new PHI
for (unsigned i = 0, e = Preds.size(); i != e; ++i) {
Value *V = PN->removeIncomingValue(Preds[i]);
NewPHI->addIncoming(V, Preds[i]);
if (Preds.size() == 1) {
// No need to insert one operand PHI nodes! Instead, just update the
// incoming block ID's.
for (BasicBlock::iterator I = BB->begin();
PHINode *PN = dyn_cast<PHINode>(I); ++I) {
unsigned i = PN->getBasicBlockIndex(Preds[0]);
PN->setIncomingBlock(i, NewBB);
}
} else {
for (BasicBlock::iterator I = BB->begin();
PHINode *PN = dyn_cast<PHINode>(I); ++I) {
// Add an incoming value to the PHI node in the loop for the preheader
// edge
PN->addIncoming(NewPHI, NewBB);
// Create the new PHI node, insert it into NewBB at the end of the block
PHINode *NewPHI = new PHINode(PN->getType(), PN->getName()+".ph", BI);
// Move all of the edges from blocks outside the loop to the new PHI
for (unsigned i = 0, e = Preds.size(); i != e; ++i) {
Value *V = PN->removeIncomingValue(Preds[i]);
NewPHI->addIncoming(V, Preds[i]);
}
// Add an incoming value to the PHI node in the loop for the preheader
// edge.
PN->addIncoming(NewPHI, NewBB);
}
}
// Now that the PHI nodes are updated, actually move the edges from