--- a/src/hotspot/share/gc/g1/heapRegionSet.hpp	Fri Dec 21 18:26:55 2018 +0000
+++ b/src/hotspot/share/gc/g1/heapRegionSet.hpp	Fri Dec 21 08:18:59 2018 -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