Fix PR3138: if we merge the entry block into another block, make sure to
move the other block back up into the entry position!
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@60179 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Scalar/JumpThreading.cpp b/lib/Transforms/Scalar/JumpThreading.cpp
index ec35a89..5de5fb3 100644
--- a/lib/Transforms/Scalar/JumpThreading.cpp
+++ b/lib/Transforms/Scalar/JumpThreading.cpp
@@ -165,7 +165,13 @@
// predecessors of our predecessor block.
if (BasicBlock *SinglePred = BB->getSinglePredecessor())
if (SinglePred->getTerminator()->getNumSuccessors() == 1) {
+ // 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(BB);
+
+ if (isEntry && BB != &BB->getParent()->getEntryBlock())
+ BB->moveBefore(&BB->getParent()->getEntryBlock());
return true;
}