diff -r e47074d2d8cc -r c8208421a860 src/hotspot/share/classfile/javaClasses.inline.hpp
--- a/src/hotspot/share/classfile/javaClasses.inline.hpp	Fri Jan 18 14:43:25 2019 +0900
+++ b/src/hotspot/share/classfile/javaClasses.inline.hpp	Fri Jan 18 08:00:05 2019 +0100
@@ -190,6 +190,13 @@
   return is_primitive;
 }
 
+inline int java_lang_Class::oop_size_raw(oop java_class) {
+  assert(_oop_size_offset != 0, "must be set");
+  int size = java_class->int_field_raw(_oop_size_offset);
+  assert(size > 0, "Oop size must be greater than zero, not %d", size);
+  return size;
+}
+
 inline bool java_lang_invoke_DirectMethodHandle::is_instance(oop obj) {
   return obj != NULL && is_subclass(obj->klass());
 }