Comment and clarifying assert.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@139036 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/ScalarEvolution.cpp b/lib/Analysis/ScalarEvolution.cpp
index 202e715..8859c3b 100644
--- a/lib/Analysis/ScalarEvolution.cpp
+++ b/lib/Analysis/ScalarEvolution.cpp
@@ -4090,6 +4090,7 @@
     else
       BECount = SE->getUMinFromMismatchedTypes(BECount, ENT->ExactNotTaken);
   }
+  assert(BECount && "Invalid not taken count for loop exit");
   return BECount;
 }