--- old/src/hotspot/share/gc/g1/heapRegionSet.hpp	2018-11-19 14:07:44.373466100 -0800
+++ new/src/hotspot/share/gc/g1/heapRegionSet.hpp	2018-11-19 14:07:43.303377900 -0800
@@ -194,6 +194,8 @@
   void remove_starting_at(HeapRegion* first, uint num_regions);
 
   virtual void verify();
+
+  uint num_of_regions_in_range(uint start, uint end) const;
 };
 
 // Iterator class that provides a convenient way to iterate over the