diff options
Diffstat (limited to 'llvm/lib/Transforms/Scalar/JumpThreading.cpp')
| -rw-r--r-- | llvm/lib/Transforms/Scalar/JumpThreading.cpp | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/llvm/lib/Transforms/Scalar/JumpThreading.cpp b/llvm/lib/Transforms/Scalar/JumpThreading.cpp index c79e756f572..2def0b54c6d 100644 --- a/llvm/lib/Transforms/Scalar/JumpThreading.cpp +++ b/llvm/lib/Transforms/Scalar/JumpThreading.cpp @@ -245,10 +245,13 @@ bool JumpThreading::runOnFunction(Function &F) { // Can't thread an unconditional jump, but if the block is "almost // empty", we can replace uses of it with uses of the successor and make // this dead. + // We should not eliminate the loop header either, because eliminating + // a loop header might later prevent LoopSimplify from transforming nested + // loops into simplified form. if (BI && BI->isUnconditional() && BB != &BB->getParent()->getEntryBlock() && // If the terminator is the only non-phi instruction, try to nuke it. - BB->getFirstNonPHIOrDbg()->isTerminator()) { + BB->getFirstNonPHIOrDbg()->isTerminator() && !LoopHeaders.count(BB)) { // Since TryToSimplifyUncondBranchFromEmptyBlock may delete the // block, we have to make sure it isn't in the LoopHeaders set. We // reinsert afterward if needed. |
