when an enum type is completed, only flush the type cache when

the enum has already been converted.  If not, there cannot be any types
built on top of it, so there is no need to flush the cache.

llvm-svn: 134841

clang/lib/CodeGen/CodeGenTypes.cpp

@@ -114,7 +114,9 @@ void CodeGenTypes::UpdateCompletedType(const TagDecl *TD) {
   // If this is an enum being completed, then we flush all non-struct types from
   // the cache.  This allows function types and other things that may be derived
   // from the enum to be recomputed.
-  if (isa<EnumDecl>(TD)) {
+  if (const EnumDecl *ED = dyn_cast<EnumDecl>(TD)) {
+    // Only flush the cache if we've actually already converted this type.
+    if (TypeCache.count(ED->getTypeForDecl()))
       TypeCache.clear();
     return;
   }