256   virtual size_t unsafe_max_tlab_alloc(Thread* thr) const;
 257   virtual HeapWord* allocate_new_tlab(size_t size);
 258 
 259   // Can a compiler initialize a new object without store barriers?
 260   // This permission only extends from the creation of a new object
 261   // via a TLAB up to the first subsequent safepoint.
 262   virtual bool can_elide_tlab_store_barriers() const {
 263     return true;
 264   }
 265 
 266   virtual bool card_mark_must_follow_store() const {
 267     return UseConcMarkSweepGC;
 268   }
 269 
 270   // We don't need barriers for stores to objects in the
 271   // young gen and, a fortiori, for initializing stores to
 272   // objects therein. This applies to DefNew+Tenured and ParNew+CMS
 273   // only and may need to be re-examined in case other
 274   // kinds of collectors are implemented in the future.
 275   virtual bool can_elide_initializing_store_barrier(oop new_obj) {
 276     // We wanted to assert that:-
 277     // assert(UseSerialGC || UseConcMarkSweepGC,
 278     //       "Check can_elide_initializing_store_barrier() for this collector");
 279     // but unfortunately the flag UseSerialGC need not necessarily always
 280     // be set when DefNew+Tenured are being used.
 281     return is_in_young(new_obj);
 282   }
 283 
 284   // The "requestor" generation is performing some garbage collection
 285   // action for which it would be useful to have scratch space.  The
 286   // requestor promises to allocate no more than "max_alloc_words" in any
 287   // older generation (via promotion say.)   Any blocks of space that can
 288   // be provided are returned as a list of ScratchBlocks, sorted by
 289   // decreasing size.
 290   ScratchBlock* gather_scratch(Generation* requestor, size_t max_alloc_words);
 291   // Allow each generation to reset any scratch space that it has
 292   // contributed as it needs.
 293   void release_scratch();
 294 
 295   // Ensure parsability: override
 296   virtual void ensure_parsability(bool retire_tlabs);
 297 
 298   // Time in ms since the longest time a collector ran in
 299   // in any generation.
 300   virtual jlong millis_since_last_gc();

 256   virtual size_t unsafe_max_tlab_alloc(Thread* thr) const;
 257   virtual HeapWord* allocate_new_tlab(size_t size);
 258 
 259   // Can a compiler initialize a new object without store barriers?
 260   // This permission only extends from the creation of a new object
 261   // via a TLAB up to the first subsequent safepoint.
 262   virtual bool can_elide_tlab_store_barriers() const {
 263     return true;
 264   }
 265 
 266   virtual bool card_mark_must_follow_store() const {
 267     return UseConcMarkSweepGC;
 268   }
 269 
 270   // We don't need barriers for stores to objects in the
 271   // young gen and, a fortiori, for initializing stores to
 272   // objects therein. This applies to DefNew+Tenured and ParNew+CMS
 273   // only and may need to be re-examined in case other
 274   // kinds of collectors are implemented in the future.
 275   virtual bool can_elide_initializing_store_barrier(oop new_obj) {





 276     return is_in_young(new_obj);
 277   }
 278 
 279   // The "requestor" generation is performing some garbage collection
 280   // action for which it would be useful to have scratch space.  The
 281   // requestor promises to allocate no more than "max_alloc_words" in any
 282   // older generation (via promotion say.)   Any blocks of space that can
 283   // be provided are returned as a list of ScratchBlocks, sorted by
 284   // decreasing size.
 285   ScratchBlock* gather_scratch(Generation* requestor, size_t max_alloc_words);
 286   // Allow each generation to reset any scratch space that it has
 287   // contributed as it needs.
 288   void release_scratch();
 289 
 290   // Ensure parsability: override
 291   virtual void ensure_parsability(bool retire_tlabs);
 292 
 293   // Time in ms since the longest time a collector ran in
 294   // in any generation.
 295   virtual jlong millis_since_last_gc();