--- a/src/hotspot/share/gc/shared/c2/barrierSetC2.hpp	Thu Nov 01 11:42:59 2018 -0400
+++ b/src/hotspot/share/gc/shared/c2/barrierSetC2.hpp	Wed Nov 07 20:21:35 2018 +0100
@@ -283,6 +283,11 @@
     BeforeCodeGen
   };
   virtual void verify_gc_barriers(Compile* compile, CompilePhase phase) const {}
+
+  virtual bool flatten_gc_alias_type(const TypePtr*& adr_type) const { return false; }
+#ifdef ASSERT
+  virtual bool verify_gc_alias_type(const TypePtr* adr_type, int offset) const { return false; }
+#endif
 };
 
 #endif // SHARE_GC_SHARED_C2_BARRIERSETC2_HPP