--- old/src/hotspot/share/utilities/bitMap.hpp	2020-01-21 14:54:40.937353518 -0800
+++ new/src/hotspot/share/utilities/bitMap.hpp	2020-01-21 14:54:40.585346614 -0800
@@ -294,6 +294,7 @@
   bool is_full() const;
   bool is_empty() const;
 
+  void write_to(bm_word_t* buffer, size_t buffer_size_in_bytes) const;
   void print_on_error(outputStream* st, const char* prefix) const;
 
 #ifndef PRODUCT