1 /*
2 * Copyright (c) 2017, 2021, 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/g1FullGCCompactionPoint.hpp"
27 #include "gc/g1/heapRegion.hpp"
28 #include "oops/oop.inline.hpp"
29 #include "utilities/debug.hpp"
30
31 G1FullGCCompactionPoint::G1FullGCCompactionPoint() :
32 _current_region(NULL),
33 _compaction_top(NULL) {
34 _compaction_regions = new (ResourceObj::C_HEAP, mtGC) GrowableArray<HeapRegion*>(32, mtGC);
35 _compaction_region_iterator = _compaction_regions->begin();
36 }
37
38 G1FullGCCompactionPoint::~G1FullGCCompactionPoint() {
39 delete _compaction_regions;
40 }
41
42 void G1FullGCCompactionPoint::update() {
43 if (is_initialized()) {
44 _current_region->set_compaction_top(_compaction_top);
45 }
46 }
47
48 void G1FullGCCompactionPoint::initialize_values(bool init_threshold) {
49 _compaction_top = _current_region->compaction_top();
50 if (init_threshold) {
51 _current_region->initialize_bot_threshold();
52 }
53 }
54
55 bool G1FullGCCompactionPoint::has_regions() {
56 return !_compaction_regions->is_empty();
57 }
58
59 bool G1FullGCCompactionPoint::is_initialized() {
60 return _current_region != NULL;
61 }
62
63 void G1FullGCCompactionPoint::initialize(HeapRegion* hr, bool init_threshold) {
64 _current_region = hr;
65 initialize_values(init_threshold);
66 }
67
68 HeapRegion* G1FullGCCompactionPoint::current_region() {
69 return *_compaction_region_iterator;
70 }
71
72 HeapRegion* G1FullGCCompactionPoint::next_region() {
73 HeapRegion* next = *(++_compaction_region_iterator);
74 assert(next != NULL, "Must return valid region");
75 return next;
76 }
77
78 GrowableArray<HeapRegion*>* G1FullGCCompactionPoint::regions() {
79 return _compaction_regions;
80 }
81
82 bool G1FullGCCompactionPoint::object_will_fit(size_t size) {
83 size_t space_left = pointer_delta(_current_region->end(), _compaction_top);
84 return size <= space_left;
85 }
86
87 void G1FullGCCompactionPoint::switch_region() {
88 // Save compaction top in the region.
89 _current_region->set_compaction_top(_compaction_top);
90 // Get the next region and re-initialize the values.
91 _current_region = next_region();
92 initialize_values(true);
93 }
94
95 void G1FullGCCompactionPoint::forward(oop object, size_t size) {
96 assert(_current_region != NULL, "Must have been initialized");
97
98 // Ensure the object fit in the current region.
99 while (!object_will_fit(size)) {
100 switch_region();
101 }
102
103 // Store a forwarding pointer if the object should be moved.
104 if (cast_from_oop<HeapWord*>(object) != _compaction_top) {
105 object->forward_to(cast_to_oop(_compaction_top));
106 } else {
107 if (object->forwardee() != NULL) {
108 // Object should not move but mark-word is used so it looks like the
109 // object is forwarded. Need to clear the mark and it's no problem
110 // since it will be restored by preserved marks.
111 object->init_mark();
112 } else {
113 // Make sure object has the correct mark-word set or that it will be
114 // fixed when restoring the preserved marks.
115 assert(object->mark() == markWord::prototype() || // Correct mark
116 object->mark_must_be_preserved(), // Will be restored by PreservedMarksSet
117 "should have correct prototype obj: " PTR_FORMAT " mark: " PTR_FORMAT " prototype: " PTR_FORMAT,
118 p2i(object), object->mark().value(), markWord::prototype().value());
119 }
120 assert(object->forwardee() == NULL, "should be forwarded to NULL");
121 }
122
123 // Update compaction values.
124 _compaction_top += size;
125 _current_region->alloc_block_in_bot(_compaction_top - size, _compaction_top);
126 }
127
128 void G1FullGCCompactionPoint::add(HeapRegion* hr) {
129 _compaction_regions->append(hr);
130 }
131
132 HeapRegion* G1FullGCCompactionPoint::remove_last() {
133 return _compaction_regions->pop();
134 }