--- old/src/hotspot/share/gc/parallel/adjoiningVirtualSpaces.hpp	2018-09-04 22:28:47.869355200 -0700
+++ new/src/hotspot/share/gc/parallel/adjoiningVirtualSpaces.hpp	2018-09-04 22:28:47.283652600 -0700
@@ -59,14 +59,11 @@
 // moved up consistently.  AdjoiningVirtualSpaces provide the
 // interfaces for moving the this boundary.
 
-class AdjoiningVirtualSpaces {
+class AdjoiningVirtualSpaces : public CHeapObj<mtGC> {
   // space at the high end and the low end, respectively
   PSVirtualSpace*    _high;
   PSVirtualSpace*    _low;
 
-  // The reserved space spanned by the two spaces.
-  ReservedSpace      _reserved_space;
-
   // The minimum byte size for the low space.  It will not
   // be shrunk below this value.
   size_t _min_low_byte_size;
@@ -75,6 +72,10 @@
 
   const size_t _alignment;
 
+ protected:
+   // The reserved space spanned by the two spaces.
+   ReservedSpace      _reserved_space;
+
  public:
   // Allocates two virtual spaces that will be located at the
   // high and low ends.  Does no initialization.
@@ -84,17 +85,17 @@
                          size_t alignment);
 
   // accessors
-  PSVirtualSpace* high() { return _high; }
-  PSVirtualSpace* low()  { return _low; }
+  virtual PSVirtualSpace* high() { return _high; }
+  virtual PSVirtualSpace* low()  { return _low; }
   ReservedSpace reserved_space() { return _reserved_space; }
   size_t min_low_byte_size() { return _min_low_byte_size; }
   size_t min_high_byte_size() { return _min_high_byte_size; }
   size_t alignment() const { return _alignment; }
 
   // move boundary between the two spaces up
-  bool adjust_boundary_up(size_t size_in_bytes);
+  virtual bool adjust_boundary_up(size_t size_in_bytes);
   // and down
-  bool adjust_boundary_down(size_t size_in_bytes);
+  virtual bool adjust_boundary_down(size_t size_in_bytes);
 
   // Maximum byte size for the high space.
   size_t high_byte_size_limit() {
@@ -111,5 +112,4 @@
                   size_t init_low_byte_size,
                   size_t init_high_byte_size);
 };
-
 #endif // SHARE_VM_GC_PARALLEL_ADJOININGVIRTUALSPACES_HPP