Fix bug in IdempotentOperationChecker where an assumption would not get updated properly.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@112309 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Checker/IdempotentOperationChecker.cpp b/lib/Checker/IdempotentOperationChecker.cpp
index 4b26d46..35fb83e 100644
--- a/lib/Checker/IdempotentOperationChecker.cpp
+++ b/lib/Checker/IdempotentOperationChecker.cpp
@@ -386,6 +386,10 @@
 // Updates the current assumption given the new assumption
 inline void IdempotentOperationChecker::UpdateAssumption(Assumption &A,
                                                         const Assumption &New) {
+// If the assumption is the same, there is nothing to do
+  if (A == New)
+    return;
+
   switch (A) {
   // If we don't currently have an assumption, set it
   case Possible: