--- old/src/hotspot/share/gc/g1/g1IHOPControl.hpp	2020-02-19 11:43:17.313740407 +0100
+++ new/src/hotspot/share/gc/g1/g1IHOPControl.hpp	2020-02-19 11:43:16.903727598 +0100
@@ -77,6 +77,8 @@
 
   virtual void print();
   virtual void send_trace_event(G1NewTracer* tracer);
+
+  virtual size_t predict_unrestrained_buffer_size() const { return 0; }
 };
 
 // The returned concurrent mark starting occupancy threshold is a fixed value
@@ -147,6 +149,7 @@
 
   virtual void print();
   virtual void send_trace_event(G1NewTracer* tracer);
+  virtual size_t predict_unrestrained_buffer_size() const;
 };
 
 #endif // SHARE_GC_G1_G1IHOPCONTROL_HPP