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Fix an issue with the MergeBasicBlockIntoOnlyPred() helper function where it did 

not properly handle the case where the predecessor block was the entry block to
the function.  The only in-tree client of this is JumpThreading, which worked
around the issue in its own code.  This patch moves the solution into the helper
so that JumpThreading (and other clients) do not have to replicate the same fix
everywhere.

llvm-svn: 212875
This commit is contained in:
Owen Anderson 2014-07-12 07:12:47 +00:00
parent d8442b1b21
commit a8d1c3e74e
2 changed files with 5 additions and 5 deletions
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5
llvm/lib/Transforms/Scalar/JumpThreading.cpp
View File

@ -669,14 +669,9 @@ bool JumpThreading::ProcessBlock(BasicBlock *BB) {
if (LoopHeaders.erase(SinglePred))
LoopHeaders.insert(BB);
// 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();
LVI->eraseBlock(SinglePred);
MergeBasicBlockIntoOnlyPred(BB);
if (isEntry && BB != &BB->getParent()->getEntryBlock())
BB->moveBefore(&BB->getParent()->getEntryBlock());
return true;
}
}

5
llvm/lib/Transforms/Utils/Local.cpp
View File

@ -509,6 +509,11 @@ void llvm::MergeBasicBlockIntoOnlyPred(BasicBlock *DestBB, Pass *P) {
PredBB->getTerminator()->eraseFromParent();
DestBB->getInstList().splice(DestBB->begin(), PredBB->getInstList());
// If the PredBB is the entry block of the function, move DestBB up to
// become the entry block after we erase PredBB.
if (PredBB == &DestBB->getParent()->getEntryBlock())
DestBB->moveAfter(PredBB);
if (P) {
if (DominatorTreeWrapperPass *DTWP =
P->getAnalysisIfAvailable<DominatorTreeWrapperPass>()) {