diff options
Diffstat (limited to 'llvm/lib/Transforms')
| -rw-r--r-- | llvm/lib/Transforms/Scalar/JumpThreading.cpp | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/llvm/lib/Transforms/Scalar/JumpThreading.cpp b/llvm/lib/Transforms/Scalar/JumpThreading.cpp index 95313115518..3a65c98195e 100644 --- a/llvm/lib/Transforms/Scalar/JumpThreading.cpp +++ b/llvm/lib/Transforms/Scalar/JumpThreading.cpp @@ -451,6 +451,12 @@ static unsigned GetBestDestForJumpOnUndef(BasicBlock *BB) { /// ProcessBlock - If there are any predecessors whose control can be threaded /// through to a successor, transform them now. bool JumpThreading::ProcessBlock(BasicBlock *BB) { + // If the block is trivially dead, just return and let the caller nuke it. + // This simplifies other transformations. + if (pred_begin(BB) == pred_end(BB) && + BB != &BB->getParent()->getEntryBlock()) + return false; + // If this block has a single predecessor, and if that pred has a single // successor, merge the blocks. This encourages recursive jump threading // because now the condition in this block can be threaded through |
