D3348 - [BUG] "Rotate Loop" pass kills "llvm.vectorizer.enable" metadata

llvm-svn: 206266

1 files changed, 9 insertions, 0 deletions

diff --git a/llvm/lib/Transforms/Scalar/LoopRotation.cpp b/llvm/lib/Transforms/Scalar/LoopRotation.cpp
index fde6bacb492..f0c9d5229be 100644
--- a/llvm/lib/Transforms/Scalar/LoopRotation.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopRotation.cpp
@@ -82,6 +82,9 @@ bool LoopRotate::runOnLoop(Loop *L, LPPassManager &LPM) {
   if (skipOptnoneFunction(L))
     return false;
 
+  // Save the loop metadata.
+  MDNode *LoopMD = L->getLoopID();
+
   LI = &getAnalysis<LoopInfo>();
   TTI = &getAnalysis<TargetTransformInfo>();
 
@@ -96,6 +99,12 @@ bool LoopRotate::runOnLoop(Loop *L, LPPassManager &LPM) {
     MadeChange = true;
     SimplifiedLatch = false;
   }
+
+  // Restore the loop metadata.
+  // NB! We presume LoopRotation DOESN'T ADD its own metadata.
+  if ((MadeChange || SimplifiedLatch) && LoopMD)
+    L->setLoopID(LoopMD);
+
   return MadeChange;
 }