BasicAA: aliasGEP shouldn't get a PartialAlias response here
add an assert() to ensure that's the case (as I'm not convinced it won't happen)

llvm-svn: 310373
diff --git a/llvm/lib/Analysis/BasicAliasAnalysis.cpp b/llvm/lib/Analysis/BasicAliasAnalysis.cpp
index e682a64..9bd4349 100644
--- a/llvm/lib/Analysis/BasicAliasAnalysis.cpp
+++ b/llvm/lib/Analysis/BasicAliasAnalysis.cpp
@@ -1196,8 +1196,10 @@
 
     // If we get a No or May, then return it immediately, no amount of analysis
     // will improve this situation.
-    if (BaseAlias != MustAlias)
+    if (BaseAlias != MustAlias) {
+      assert(BaseAlias == NoAlias || BaseAlias == MayAlias);
       return BaseAlias;
+    }
 
     // Otherwise, we have a MustAlias.  Since the base pointers alias each other
     // exactly, see if the computed offset from the common pointer tells us