1 /*
2 * Copyright (c) 2017, 2023, 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/g1CollectedHeap.hpp"
27 #include "gc/g1/g1ConcurrentMarkBitMap.inline.hpp"
28 #include "gc/g1/g1FullCollector.inline.hpp"
29 #include "gc/g1/g1FullGCCompactionPoint.hpp"
30 #include "gc/g1/g1FullGCCompactTask.hpp"
31 #include "gc/g1/heapRegion.inline.hpp"
32 #include "gc/shared/gcTraceTime.inline.hpp"
33 #include "gc/shared/slidingForwarding.inline.hpp"
34 #include "logging/log.hpp"
35 #include "oops/oop.inline.hpp"
36 #include "utilities/ticks.hpp"
37
38 template <bool ALT_FWD>
39 void G1FullGCCompactTask::G1CompactRegionClosure<ALT_FWD>::clear_in_bitmap(oop obj) {
40 assert(_bitmap->is_marked(obj), "Should only compact marked objects");
41 _bitmap->clear(obj);
42 }
43
44 template <bool ALT_FWD>
45 size_t G1FullGCCompactTask::G1CompactRegionClosure<ALT_FWD>::apply(oop obj) {
46 size_t size = obj->size();
47 if (SlidingForwarding::is_forwarded(obj)) {
48 G1FullGCCompactTask::copy_object_to_new_location<ALT_FWD>(obj);
49 }
50
51 // Clear the mark for the compacted object to allow reuse of the
52 // bitmap without an additional clearing step.
53 clear_in_bitmap(obj);
54 return size;
55 }
56
57 template <bool ALT_FWD>
58 void G1FullGCCompactTask::copy_object_to_new_location(oop obj) {
59 assert(SlidingForwarding::is_forwarded(obj), "Sanity!");
60 assert(SlidingForwarding::forwardee<ALT_FWD>(obj) != obj, "Object must have a new location");
61
62 size_t size = obj->size();
63 // Copy object and reinit its mark.
64 HeapWord* obj_addr = cast_from_oop<HeapWord*>(obj);
65 HeapWord* destination = cast_from_oop<HeapWord*>(SlidingForwarding::forwardee<ALT_FWD>(obj));
66 Copy::aligned_conjoint_words(obj_addr, destination, size);
67
68 // There is no need to transform stack chunks - marking already did that.
69 cast_to_oop(destination)->init_mark();
70 assert(cast_to_oop(destination)->klass() != nullptr, "should have a class");
71 }
72
73 void G1FullGCCompactTask::compact_region(HeapRegion* hr) {
74 assert(!hr->is_humongous(), "Should be no humongous regions in compaction queue");
75
76 if (!collector()->is_free(hr->hrm_index())) {
77 // The compaction closure not only copies the object to the new
78 // location, but also clears the bitmap for it. This is needed
79 // for bitmap verification and to be able to use the bitmap
80 // for evacuation failures in the next young collection. Testing
81 // showed that it was better overall to clear bit by bit, compared
82 // to clearing the whole region at the end. This difference was
83 // clearly seen for regions with few marks.
84 if (UseAltGCForwarding) {
85 G1CompactRegionClosure<true> compact(collector()->mark_bitmap());
86 hr->apply_to_marked_objects(collector()->mark_bitmap(), &compact);
87 } else {
88 G1CompactRegionClosure<false> compact(collector()->mark_bitmap());
89 hr->apply_to_marked_objects(collector()->mark_bitmap(), &compact);
90 }
91 }
92
93 hr->reset_compacted_after_full_gc(_collector->compaction_top(hr));
94 }
95
96 void G1FullGCCompactTask::work(uint worker_id) {
97 Ticks start = Ticks::now();
98 GrowableArray<HeapRegion*>* compaction_queue = collector()->compaction_point(worker_id)->regions();
99 for (GrowableArrayIterator<HeapRegion*> it = compaction_queue->begin();
100 it != compaction_queue->end();
101 ++it) {
102 compact_region(*it);
103 }
104 }
105
106 void G1FullGCCompactTask::serial_compaction() {
107 GCTraceTime(Debug, gc, phases) tm("Phase 4: Serial Compaction", collector()->scope()->timer());
108 GrowableArray<HeapRegion*>* compaction_queue = collector()->serial_compaction_point()->regions();
109 for (GrowableArrayIterator<HeapRegion*> it = compaction_queue->begin();
110 it != compaction_queue->end();
111 ++it) {
112 compact_region(*it);
113 }
114 }
115
116 template <bool ALT_FWD>
117 void G1FullGCCompactTask::humongous_compaction_impl() {
118 for (HeapRegion* hr : collector()->humongous_compaction_regions()) {
119 assert(collector()->is_compaction_target(hr->hrm_index()), "Sanity");
120 compact_humongous_obj<ALT_FWD>(hr);
121 }
122 }
123
124 void G1FullGCCompactTask::humongous_compaction() {
125 GCTraceTime(Debug, gc, phases) tm("Phase 4: Humonguous Compaction", collector()->scope()->timer());
126 if (UseAltGCForwarding) {
127 humongous_compaction_impl<true>();
128 } else {
129 humongous_compaction_impl<false>();
130 }
131 }
132
133 template <bool ALT_FWD>
134 void G1FullGCCompactTask::compact_humongous_obj(HeapRegion* src_hr) {
135 assert(src_hr->is_starts_humongous(), "Should be start region of the humongous object");
136
137 oop obj = cast_to_oop(src_hr->bottom());
138 size_t word_size = obj->size();
139
140 uint num_regions = (uint)G1CollectedHeap::humongous_obj_size_in_regions(word_size);
141 HeapWord* destination = cast_from_oop<HeapWord*>(SlidingForwarding::forwardee<ALT_FWD>(obj));
142
143 assert(collector()->mark_bitmap()->is_marked(obj), "Should only compact marked objects");
144 collector()->mark_bitmap()->clear(obj);
145
146 copy_object_to_new_location<ALT_FWD>(obj);
147
148 uint dest_start_idx = _g1h->addr_to_region(destination);
149 // Update the metadata for the destination regions.
150 _g1h->set_humongous_metadata(_g1h->region_at(dest_start_idx), num_regions, word_size, false);
151
152 // Free the source regions that do not overlap with the destination regions.
153 uint src_start_idx = src_hr->hrm_index();
154 free_non_overlapping_regions(src_start_idx, dest_start_idx, num_regions);
155 }
156
157 void G1FullGCCompactTask::free_non_overlapping_regions(uint src_start_idx, uint dest_start_idx, uint num_regions) {
158 uint dest_end_idx = dest_start_idx + num_regions -1;
159 uint src_end_idx = src_start_idx + num_regions - 1;
160
161 uint non_overlapping_start = dest_end_idx < src_start_idx ?
162 src_start_idx :
163 dest_end_idx + 1;
164
165 for (uint i = non_overlapping_start; i <= src_end_idx; ++i) {
166 HeapRegion* hr = _g1h->region_at(i);
167 _g1h->free_humongous_region(hr, nullptr);
168 }
169 }