1275 // This permission only extends from the creation of a new object
1276 // via a TLAB up to the first subsequent safepoint. If such permission
1277 // is granted for this heap type, the compiler promises to call
1278 // defer_store_barrier() below on any slow path allocation of
1279 // a new object for which such initializing store barriers will
1280 // have been elided. G1, like CMS, allows this, but should be
1281 // ready to provide a compensating write barrier as necessary
1282 // if that storage came out of a non-young region. The efficiency
1283 // of this implementation depends crucially on being able to
1284 // answer very efficiently in constant time whether a piece of
1285 // storage in the heap comes from a young region or not.
1286 // See ReduceInitialCardMarks.
1287 virtual bool can_elide_tlab_store_barriers() const {
1288 return true;
1289 }
1290
1291 virtual bool card_mark_must_follow_store() const {
1292 return true;
1293 }
1294
1295 inline bool is_in_young(const oop obj);
1296
1297 virtual bool is_scavengable(const void* addr);
1298
1299 // We don't need barriers for initializing stores to objects
1300 // in the young gen: for the SATB pre-barrier, there is no
1301 // pre-value that needs to be remembered; for the remembered-set
1302 // update logging post-barrier, we don't maintain remembered set
1303 // information for young gen objects.
1304 virtual inline bool can_elide_initializing_store_barrier(oop new_obj);
1305
1306 // Returns "true" iff the given word_size is "very large".
1307 static bool is_humongous(size_t word_size) {
1308 // Note this has to be strictly greater-than as the TLABs
1309 // are capped at the humongous threshold and we want to
1310 // ensure that we don't try to allocate a TLAB as
1311 // humongous and that we don't allocate a humongous
1312 // object in a TLAB.
1313 return word_size > _humongous_object_threshold_in_words;
1314 }
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1275 // This permission only extends from the creation of a new object
1276 // via a TLAB up to the first subsequent safepoint. If such permission
1277 // is granted for this heap type, the compiler promises to call
1278 // defer_store_barrier() below on any slow path allocation of
1279 // a new object for which such initializing store barriers will
1280 // have been elided. G1, like CMS, allows this, but should be
1281 // ready to provide a compensating write barrier as necessary
1282 // if that storage came out of a non-young region. The efficiency
1283 // of this implementation depends crucially on being able to
1284 // answer very efficiently in constant time whether a piece of
1285 // storage in the heap comes from a young region or not.
1286 // See ReduceInitialCardMarks.
1287 virtual bool can_elide_tlab_store_barriers() const {
1288 return true;
1289 }
1290
1291 virtual bool card_mark_must_follow_store() const {
1292 return true;
1293 }
1294
1295 // The reference pending list lock is acquired from from the
1296 // ConcurrentMarkThread.
1297 virtual bool needs_reference_pending_list_locker_thread() const {
1298 return true;
1299 }
1300
1301 inline bool is_in_young(const oop obj);
1302
1303 virtual bool is_scavengable(const void* addr);
1304
1305 // We don't need barriers for initializing stores to objects
1306 // in the young gen: for the SATB pre-barrier, there is no
1307 // pre-value that needs to be remembered; for the remembered-set
1308 // update logging post-barrier, we don't maintain remembered set
1309 // information for young gen objects.
1310 virtual inline bool can_elide_initializing_store_barrier(oop new_obj);
1311
1312 // Returns "true" iff the given word_size is "very large".
1313 static bool is_humongous(size_t word_size) {
1314 // Note this has to be strictly greater-than as the TLABs
1315 // are capped at the humongous threshold and we want to
1316 // ensure that we don't try to allocate a TLAB as
1317 // humongous and that we don't allocate a humongous
1318 // object in a TLAB.
1319 return word_size > _humongous_object_threshold_in_words;
1320 }
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