1 /*
2 * Copyright (c) 2001, 2018, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "gc/g1/g1CardTable.hpp"
27 #include "gc/g1/g1CollectedHeap.inline.hpp"
28 #include "gc/shared/memset_with_concurrent_readers.hpp"
29 #include "logging/log.hpp"
30 #include "runtime/atomic.hpp"
31 #include "runtime/orderAccess.hpp"
32
mark_card_deferred(size_t card_index)33 bool G1CardTable::mark_card_deferred(size_t card_index) {
34 jbyte val = _byte_map[card_index];
35 // It's already processed
36 if ((val & (clean_card_mask_val() | deferred_card_val())) == deferred_card_val()) {
37 return false;
38 }
39
40 // Cached bit can be installed either on a clean card or on a claimed card.
41 jbyte new_val = val;
42 if (val == clean_card_val()) {
43 new_val = (jbyte)deferred_card_val();
44 } else {
45 if (val & claimed_card_val()) {
46 new_val = val | (jbyte)deferred_card_val();
47 }
48 }
49 if (new_val != val) {
50 Atomic::cmpxchg(new_val, &_byte_map[card_index], val);
51 }
52 return true;
53 }
54
g1_mark_as_young(const MemRegion & mr)55 void G1CardTable::g1_mark_as_young(const MemRegion& mr) {
56 jbyte *const first = byte_for(mr.start());
57 jbyte *const last = byte_after(mr.last());
58
59 memset_with_concurrent_readers(first, g1_young_gen, last - first);
60 }
61
62 #ifndef PRODUCT
verify_g1_young_region(MemRegion mr)63 void G1CardTable::verify_g1_young_region(MemRegion mr) {
64 verify_region(mr, g1_young_gen, true);
65 }
66 #endif
67
on_commit(uint start_idx,size_t num_regions,bool zero_filled)68 void G1CardTableChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
69 // Default value for a clean card on the card table is -1. So we cannot take advantage of the zero_filled parameter.
70 MemRegion mr(G1CollectedHeap::heap()->bottom_addr_for_region(start_idx), num_regions * HeapRegion::GrainWords);
71 _card_table->clear(mr);
72 }
73
initialize(G1RegionToSpaceMapper * mapper)74 void G1CardTable::initialize(G1RegionToSpaceMapper* mapper) {
75 mapper->set_mapping_changed_listener(&_listener);
76
77 _byte_map_size = mapper->reserved().byte_size();
78
79 _guard_index = cards_required(_whole_heap.word_size()) - 1;
80 _last_valid_index = _guard_index - 1;
81
82 HeapWord* low_bound = _whole_heap.start();
83 HeapWord* high_bound = _whole_heap.end();
84
85 _cur_covered_regions = 1;
86 _covered[0] = _whole_heap;
87
88 _byte_map = (jbyte*) mapper->reserved().start();
89 _byte_map_base = _byte_map - (uintptr_t(low_bound) >> card_shift);
90 assert(byte_for(low_bound) == &_byte_map[0], "Checking start of map");
91 assert(byte_for(high_bound-1) <= &_byte_map[_last_valid_index], "Checking end of map");
92
93 log_trace(gc, barrier)("G1CardTable::G1CardTable: ");
94 log_trace(gc, barrier)(" &_byte_map[0]: " INTPTR_FORMAT " &_byte_map[_last_valid_index]: " INTPTR_FORMAT,
95 p2i(&_byte_map[0]), p2i(&_byte_map[_last_valid_index]));
96 log_trace(gc, barrier)(" _byte_map_base: " INTPTR_FORMAT, p2i(_byte_map_base));
97 }
98
is_in_young(oop obj) const99 bool G1CardTable::is_in_young(oop obj) const {
100 volatile jbyte* p = byte_for(obj);
101 return *p == G1CardTable::g1_young_card_val();
102 }
103