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defensive patch: if CGP is merging a block with the entry block, make sure 

it ends up being the entry block.

llvm-svn: 60180
This commit is contained in:
Chris Lattner 2008-11-27 19:29:14 +00:00
parent 5dfbfcd80d
commit 4059f43b74
1 changed files with 8 additions and 1 deletions
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9
llvm/lib/Transforms/Scalar/CodeGenPrepare.cpp
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@ -204,8 +204,15 @@ void CodeGenPrepare::EliminateMostlyEmptyBlock(BasicBlock *BB) {
// If the destination block has a single pred, then this is a trivial edge,
// just collapse it.
if (DestBB->getSinglePredecessor()) {
if (BasicBlock *SinglePred = DestBB->getSinglePredecessor()) {
// Remember if SinglePred was the entry block of the function. If so, we
// will need to move BB back to the entry position.
bool isEntry = SinglePred == &SinglePred->getParent()->getEntryBlock();
MergeBasicBlockIntoOnlyPred(DestBB);
if (isEntry && BB != &BB->getParent()->getEntryBlock())
BB->moveBefore(&BB->getParent()->getEntryBlock());
DOUT << "AFTER:\n" << *DestBB << "\n\n\n";
return;
}