--- a/src/hotspot/share/gc/shared/collectedHeap.hpp	Mon Apr 01 08:21:45 2019 -0700
+++ b/src/hotspot/share/gc/shared/collectedHeap.hpp	Mon Apr 01 18:34:39 2019 +0200
@@ -510,11 +510,11 @@
   void print_heap_after_gc();
 
   // Registering and unregistering an nmethod (compiled code) with the heap.
-  // Override with specific mechanism for each specialized heap type.
-  virtual void register_nmethod(nmethod* nm) {}
-  virtual void unregister_nmethod(nmethod* nm) {}
-  virtual void flush_nmethod(nmethod* nm) {}
-  virtual void verify_nmethod(nmethod* nmethod) {}
+  virtual void register_nmethod(nmethod* nm) = 0;
+  virtual void unregister_nmethod(nmethod* nm) = 0;
+  // Callback for when nmethod is about to be deleted.
+  virtual void flush_nmethod(nmethod* nm) = 0;
+  virtual void verify_nmethod(nmethod* nm) = 0;
 
   void trace_heap_before_gc(const GCTracer* gc_tracer);
   void trace_heap_after_gc(const GCTracer* gc_tracer);