From 76f6bf2a288762f49978d6cd24625d2aefd24d29 Mon Sep 17 00:00:00 2001
From: Max Kazantsev <max.kazantsev@azul.com>
Date: Tue, 24 Apr 2018 02:08:05 +0000
Subject: [PATCH] [NFC] Add clarification comment

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@330677 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Transforms/Utils/LoopRotationUtils.cpp | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/lib/Transforms/Utils/LoopRotationUtils.cpp b/lib/Transforms/Utils/LoopRotationUtils.cpp
index d2a2e40518f..a7dc34f24eb 100644
--- a/lib/Transforms/Utils/LoopRotationUtils.cpp
+++ b/lib/Transforms/Utils/LoopRotationUtils.cpp
@@ -259,8 +259,10 @@ bool LoopRotate::rotateLoop(Loop *L, bool SimplifiedLatch) {
     return false;
 
   // Anything ScalarEvolution may know about this loop or the PHI nodes
-  // in its header will soon be invalidated, and it can also affect its parent
-  // loops as well.
+  // in its header will soon be invalidated. We should also invalidate
+  // all outer loops because insertion and deletion of blocks that happens
+  // during the rotation may violate invariants related to backedge taken
+  // infos in them.
   if (SE)
     SE->forgetTopmostLoop(L);