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Fix Transforms/LoopUnswitch/2006-06-13-SingleEntryPHI.ll, a loop unswitch

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bug exposed by the recent lcssa work.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@28779 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2006-06-14 04:46:17 +00:00
parent 2c54676d70
commit f7a1212850
1 changed files with 13 additions and 1 deletions
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14
lib/Transforms/Scalar/LoopUnswitch.cpp
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@ -401,7 +401,7 @@ bool LoopUnswitch::UnswitchIfProfitable(Value *LoopCond, Constant *Val,Loop *L){
<< Cost << "\n");
return false;
}
// If this is a trivial condition to unswitch (which results in no code
// duplication), do it now.
Constant *CondVal;
@ -456,6 +456,18 @@ BasicBlock *LoopUnswitch::SplitEdge(BasicBlock *BB, BasicBlock *Succ) {
// If the successor only has a single pred, split the top of the successor
// block.
assert(SP == BB && "CFG broken");
// If this block has a single predecessor, remove any phi nodes. Unswitch
// expect that, after split the edges from inside the loop to the exit
// block, that there will be no phi nodes in the new exit block. Single
// entry phi nodes break this assumption.
BasicBlock::iterator I = Succ->begin();
while (PHINode *PN = dyn_cast<PHINode>(I)) {
PN->replaceAllUsesWith(PN->getIncomingValue(0));
PN->eraseFromParent();
I = Succ->begin();
}
return SplitBlock(Succ, Succ->begin());
} else {
// Otherwise, if BB has a single successor, split it at the bottom of the