diff options
Diffstat (limited to 'llvm/lib/Transforms/Scalar/JumpThreading.cpp')
| -rw-r--r-- | llvm/lib/Transforms/Scalar/JumpThreading.cpp | 10 |
1 files changed, 6 insertions, 4 deletions
diff --git a/llvm/lib/Transforms/Scalar/JumpThreading.cpp b/llvm/lib/Transforms/Scalar/JumpThreading.cpp index 4056cc5cb34..c5557bef8cc 100644 --- a/llvm/lib/Transforms/Scalar/JumpThreading.cpp +++ b/llvm/lib/Transforms/Scalar/JumpThreading.cpp @@ -231,13 +231,15 @@ bool JumpThreadingPass::runImpl(Function &F, TargetLibraryInfo *TLI_, // 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. + // We should not eliminate the loop header or latch either, because + // eliminating a loop header or latch might later prevent LoopSimplify + // from transforming nested loops into simplified form. We will rely on + // later passes in backend to clean up empty blocks. if (BI && BI->isUnconditional() && BB != &BB->getParent()->getEntryBlock() && // If the terminator is the only non-phi instruction, try to nuke it. - BB->getFirstNonPHIOrDbg()->isTerminator() && !LoopHeaders.count(BB)) { + BB->getFirstNonPHIOrDbg()->isTerminator() && !LoopHeaders.count(BB) && + !LoopHeaders.count(BI->getSuccessor(0))) { // FIXME: It is always conservatively correct to drop the info // for a block even if it doesn't get erased. This isn't totally // awesome, but it allows us to use AssertingVH to prevent nasty |
