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comparison src/share/vm/memory/referenceProcessor.cpp @ 845:df6caf649ff7

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6700789: G1: Enable use of compressed oops with G1 heaps Summary: Modifications to G1 so as to allow the use of compressed oops. Reviewed-by: apetrusenko, coleenp, jmasa, kvn, never, phh, tonyp
author ysr
date Tue, 14 Jul 2009 15:40:39 -0700
parents 0fbdb4381b99
children 05f89f00a864
comparison
equal deleted inserted replaced
839:bb18957ad21e 845:df6caf649ff7
1011 assert(_discovery_is_mt, "!_discovery_is_mt should have been handled by caller"); 1011 assert(_discovery_is_mt, "!_discovery_is_mt should have been handled by caller");
1012 // First we must make sure this object is only enqueued once. CAS in a non null 1012 // First we must make sure this object is only enqueued once. CAS in a non null
1013 // discovered_addr. 1013 // discovered_addr.
1014 oop current_head = refs_list.head(); 1014 oop current_head = refs_list.head();
1015 1015
1016 // Note: In the case of G1, this pre-barrier is strictly 1016 // Note: In the case of G1, this specific pre-barrier is strictly
1017 // not necessary because the only case we are interested in 1017 // not necessary because the only case we are interested in
1018 // here is when *discovered_addr is NULL, so this will expand to 1018 // here is when *discovered_addr is NULL (see the CAS further below),
1019 // nothing. As a result, I am just manually eliding this out for G1. 1019 // so this will expand to nothing. As a result, we have manually
1020 // elided this out for G1, but left in the test for some future
1021 // collector that might have need for a pre-barrier here.
1020 if (_discovered_list_needs_barrier && !UseG1GC) { 1022 if (_discovered_list_needs_barrier && !UseG1GC) {
1021 _bs->write_ref_field_pre((void*)discovered_addr, current_head); guarantee(false, "Needs to be fixed: YSR"); 1023 if (UseCompressedOops) {
1024 _bs->write_ref_field_pre((narrowOop*)discovered_addr, current_head);
1025 } else {
1026 _bs->write_ref_field_pre((oop*)discovered_addr, current_head);
1027 }
1028 guarantee(false, "Need to check non-G1 collector");
1022 } 1029 }
1023 oop retest = oopDesc::atomic_compare_exchange_oop(current_head, discovered_addr, 1030 oop retest = oopDesc::atomic_compare_exchange_oop(current_head, discovered_addr,
1024 NULL); 1031 NULL);
1025 if (retest == NULL) { 1032 if (retest == NULL) {
1026 // This thread just won the right to enqueue the object. 1033 // This thread just won the right to enqueue the object.
1027 // We have separate lists for enqueueing so no synchronization 1034 // We have separate lists for enqueueing so no synchronization
1028 // is necessary. 1035 // is necessary.
1029 refs_list.set_head(obj); 1036 refs_list.set_head(obj);
1030 refs_list.inc_length(1); 1037 refs_list.inc_length(1);
1031 if (_discovered_list_needs_barrier) { 1038 if (_discovered_list_needs_barrier) {
1032 _bs->write_ref_field((void*)discovered_addr, current_head); guarantee(false, "Needs to be fixed: YSR"); 1039 _bs->write_ref_field((void*)discovered_addr, current_head);
1033 } 1040 }
1034
1035 } else { 1041 } else {
1036 // If retest was non NULL, another thread beat us to it: 1042 // If retest was non NULL, another thread beat us to it:
1037 // The reference has already been discovered... 1043 // The reference has already been discovered...
1038 if (TraceReferenceGC) { 1044 if (TraceReferenceGC) {
1039 gclog_or_tty->print_cr("Already enqueued reference (" INTPTR_FORMAT ": %s)", 1045 gclog_or_tty->print_cr("Already enqueued reference (" INTPTR_FORMAT ": %s)",
1175 oop current_head = list->head(); 1181 oop current_head = list->head();
1176 // As in the case further above, since we are over-writing a NULL 1182 // As in the case further above, since we are over-writing a NULL
1177 // pre-value, we can safely elide the pre-barrier here for the case of G1. 1183 // pre-value, we can safely elide the pre-barrier here for the case of G1.
1178 assert(discovered == NULL, "control point invariant"); 1184 assert(discovered == NULL, "control point invariant");
1179 if (_discovered_list_needs_barrier && !UseG1GC) { // safe to elide for G1 1185 if (_discovered_list_needs_barrier && !UseG1GC) { // safe to elide for G1
1180 _bs->write_ref_field_pre((oop*)discovered_addr, current_head); 1186 if (UseCompressedOops) {
1187 _bs->write_ref_field_pre((narrowOop*)discovered_addr, current_head);
1188 } else {
1189 _bs->write_ref_field_pre((oop*)discovered_addr, current_head);
1190 }
1191 guarantee(false, "Need to check non-G1 collector");
1181 } 1192 }
1182 oop_store_raw(discovered_addr, current_head); 1193 oop_store_raw(discovered_addr, current_head);
1183 if (_discovered_list_needs_barrier) { 1194 if (_discovered_list_needs_barrier) {
1184 _bs->write_ref_field((oop*)discovered_addr, current_head); 1195 _bs->write_ref_field((void*)discovered_addr, current_head);
1185 } 1196 }
1186 list->set_head(obj); 1197 list->set_head(obj);
1187 list->inc_length(1); 1198 list->inc_length(1);
1188 } 1199 }
1189 1200