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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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12
llvm/lib/Transforms/Scalar/LoopSimplify.cpp
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@ -162,6 +162,15 @@ BasicBlock *LoopSimplify::SplitBlockPredecessors(BasicBlock *BB,
// incoming edges in BB into new PHI nodes in NewBB. // incoming edges in BB into new PHI nodes in NewBB.
// //
if (!Preds.empty()) { // Is the loop not obviously dead? if (!Preds.empty()) { // Is the loop not obviously dead?
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(); for (BasicBlock::iterator I = BB->begin();
PHINode *PN = dyn_cast<PHINode>(I); ++I) { PHINode *PN = dyn_cast<PHINode>(I); ++I) {
@ -175,9 +184,10 @@ BasicBlock *LoopSimplify::SplitBlockPredecessors(BasicBlock *BB,
} }
// Add an incoming value to the PHI node in the loop for the preheader // Add an incoming value to the PHI node in the loop for the preheader
// edge // edge.
PN->addIncoming(NewPHI, NewBB); PN->addIncoming(NewPHI, NewBB);
} }
}
// Now that the PHI nodes are updated, actually move the edges from // Now that the PHI nodes are updated, actually move the edges from
// Preds to point to NewBB instead of BB. // Preds to point to NewBB instead of BB.