--- a/src/hotspot/share/gc/shared/collectedHeap.hpp	Wed Oct 03 15:22:16 2018 +0200
+++ b/src/hotspot/share/gc/shared/collectedHeap.hpp	Wed Oct 10 10:58:48 2018 +0200
@@ -576,6 +576,8 @@
 
   virtual bool is_oop(oop object) const;
 
+  virtual size_t obj_size(oop obj) const;
+
   // Non product verification and debugging.
 #ifndef PRODUCT
   // Support for PromotionFailureALot.  Return true if it's time to cause a