1275   // Can a compiler initialize a new object without store barriers?

  1276   // This permission only extends from the creation of a new object

  1277   // via a TLAB up to the first subsequent safepoint. If such permission

  1278   // is granted for this heap type, the compiler promises to call

  1279   // defer_store_barrier() below on any slow path allocation of

  1280   // a new object for which such initializing store barriers will

  1281   // have been elided. G1, like CMS, allows this, but should be

  1282   // ready to provide a compensating write barrier as necessary

  1283   // if that storage came out of a non-young region. The efficiency

  1284   // of this implementation depends crucially on being able to

  1285   // answer very efficiently in constant time whether a piece of

  1286   // storage in the heap comes from a young region or not.

  1287   // See ReduceInitialCardMarks.

  1288   virtual bool can_elide_tlab_store_barriers() const {

  1289     return true;

  1290   }

  1291 

  1292   virtual bool card_mark_must_follow_store() const {

  1293     return true;

  1294   }

  1295 

  1297 

  1298   // We don't need barriers for initializing stores to objects

  1299   // in the young gen: for the SATB pre-barrier, there is no

  1300   // pre-value that needs to be remembered; for the remembered-set

  1301   // update logging post-barrier, we don't maintain remembered set

  1302   // information for young gen objects.

  1303   virtual inline bool can_elide_initializing_store_barrier(oop new_obj);