Add a comment to the commit r165187.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@165238 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 3 insertions, 1 deletions

diff --git a/lib/Transforms/Scalar/IndVarSimplify.cpp b/lib/Transforms/Scalar/IndVarSimplify.cpp
index 23d0bb51b3..af0ee34d0d 100644
--- a/lib/Transforms/Scalar/IndVarSimplify.cpp
+++ b/lib/Transforms/Scalar/IndVarSimplify.cpp
@@ -1261,10 +1261,12 @@ static bool needsLFTR(Loop *L, DominatorTree *DT) {
   if (!Phi)
     return true;
 
-  // Do LFTR if the exit condition's IV is *not* a simple counter.
+  // Do LFTR if PHI node is defined in the loop, but is *not* a counter.
   int Idx = Phi->getBasicBlockIndex(L->getLoopLatch());
   if (Idx < 0)
     return true;
+
+  // Do LFTR if the exit condition's IV is *not* a simple counter.
   Value *IncV = Phi->getIncomingValue(Idx);
   return Phi != getLoopPhiForCounter(IncV, L, DT);
 }