Loop Rotation pass preserves dominator tree and frontier.

llvm-svn: 40603

llvm/lib/Transforms/Scalar/LoopRotation.cpp

@@ -62,6 +62,8 @@ namespace {
       AU.addPreserved<LoopInfo>();
       AU.addRequiredID(LoopSimplifyID);
       AU.addPreservedID(LoopSimplifyID);
+      AU.addPreserved<DominatorTree>();
+      AU.addPreserved<DominanceFrontier>();
     }
 
     // Helper functions