[LIR] Fix mis-compilation with unwinding.

To fix PR27859, bail out if there is an instruction may throw.

Differential Revision: http://reviews.llvm.org/D20638

llvm-svn: 274673

1 files changed, 8 insertions, 0 deletions

diff --git a/llvm/lib/Transforms/Scalar/LoopIdiomRecognize.cpp b/llvm/lib/Transforms/Scalar/LoopIdiomRecognize.cpp
index a226865262e..ae0c84786e1 100644
--- a/llvm/lib/Transforms/Scalar/LoopIdiomRecognize.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopIdiomRecognize.cpp
@@ -216,6 +216,14 @@ bool LoopIdiomRecognize::runOnCountableLoop() {
                << CurLoop->getHeader()->getName() << "\n");
 
   bool MadeChange = false;
+
+  // The following transforms hoist stores/memsets into the loop pre-header.
+  // Give up if the loop has instructions may throw.
+  LoopSafetyInfo SafetyInfo;
+  computeLoopSafetyInfo(&SafetyInfo, CurLoop);
+  if (SafetyInfo.MayThrow)
+    return MadeChange;
+
   // Scan all the blocks in the loop that are not in subloops.
   for (auto *BB : CurLoop->getBlocks()) {
     // Ignore blocks in subloops.