--- old/src/share/vm/oops/objArrayKlass.hpp	2019-01-28 17:44:05.000000000 +0800
+++ new/src/share/vm/oops/objArrayKlass.hpp	2019-01-28 17:44:05.000000000 +0800
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2014, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2019, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -96,6 +96,11 @@
     return (ObjArrayKlass*) k;
   }
 
+  static const ObjArrayKlass* cast(const Klass* k) {
+    assert(k->oop_is_objArray(), "cast to ObjArrayKlass");
+    return static_cast<const ObjArrayKlass*>(k);
+  }
+
   // Sizing
   static int header_size()                { return sizeof(ObjArrayKlass)/HeapWordSize; }
   int size() const                        { return ArrayKlass::static_size(header_size()); }