8325134: Serial: Remove Generation::used_region

Reviewed-by: tschatzl, iwalulya

src/hotspot/share/gc/serial/generation.hpp

@@ -113,10 +113,6 @@ class Generation: public CHeapObj<mtGC> {
 
   MemRegion reserved() const { return _reserved; }
 
-  // Returns a region guaranteed to contain all the objects in the
-  // generation.
-  virtual MemRegion used_region() const { return _reserved; }
-
   /* Returns "TRUE" iff "p" points into the reserved area of the generation. */
   bool is_in_reserved(const void* p) const {
     return _reserved.contains(p);

src/hotspot/share/gc/serial/tenuredGeneration.hpp

@@ -29,6 +29,7 @@
 #include "gc/serial/generation.hpp"
 #include "gc/shared/gcStats.hpp"
 #include "gc/shared/generationCounters.hpp"
+#include "gc/shared/space.hpp"
 #include "utilities/macros.hpp"
 
 class SerialBlockOffsetSharedArray;
@@ -92,8 +93,8 @@ class TenuredGeneration: public Generation {
   size_t capacity() const;
   size_t used() const;
   size_t free() const;
-  MemRegion used_region() const;
 
+  MemRegion used_region() const { return space()->used_region(); }
   MemRegion prev_used_region() const { return _prev_used_region; }
   void save_used_region()   { _prev_used_region = used_region(); }
 

src/hotspot/share/gc/serial/tenuredGeneration.inline.hpp

@@ -41,10 +41,6 @@ inline size_t TenuredGeneration::free() const {
   return space()->free();
 }
 
-inline MemRegion TenuredGeneration::used_region() const {
-  return space()->used_region();
-}
-
 inline bool TenuredGeneration::is_in(const void* p) const {
   return space()->is_in(p);
 }