1 /*
2 * Copyright (c) 2017, 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/g1FullGCCompactionPoint.hpp"
27 #include "gc/g1/heapRegion.hpp"
28 #include "gc/shared/slidingForwarding.inline.hpp"
29 #include "oops/oop.inline.hpp"
30 #include "utilities/debug.hpp"
31
32 G1FullGCCompactionPoint::G1FullGCCompactionPoint() :
33 _current_region(NULL),
34 _threshold(NULL),
35 _compaction_top(NULL) {
36 _compaction_regions = new (ResourceObj::C_HEAP, mtGC) GrowableArray<HeapRegion*>(32, mtGC);
37 _compaction_region_iterator = _compaction_regions->begin();
38 }
39
40 G1FullGCCompactionPoint::~G1FullGCCompactionPoint() {
41 delete _compaction_regions;
42 }
43
44 void G1FullGCCompactionPoint::update() {
45 if (is_initialized()) {
46 _current_region->set_compaction_top(_compaction_top);
47 }
48 }
49
50 void G1FullGCCompactionPoint::initialize_values(bool init_threshold) {
51 _compaction_top = _current_region->compaction_top();
52 if (init_threshold) {
53 _threshold = _current_region->initialize_threshold();
54 }
55 }
56
57 bool G1FullGCCompactionPoint::has_regions() {
58 return !_compaction_regions->is_empty();
59 }
60
61 bool G1FullGCCompactionPoint::is_initialized() {
62 return _current_region != NULL;
63 }
64
65 void G1FullGCCompactionPoint::initialize(HeapRegion* hr, bool init_threshold) {
66 _current_region = hr;
67 initialize_values(init_threshold);
68 }
69
70 HeapRegion* G1FullGCCompactionPoint::current_region() {
71 return *_compaction_region_iterator;
72 }
73
74 HeapRegion* G1FullGCCompactionPoint::next_region() {
75 HeapRegion* next = *(++_compaction_region_iterator);
76 assert(next != NULL, "Must return valid region");
77 return next;
78 }
79
80 GrowableArray<HeapRegion*>* G1FullGCCompactionPoint::regions() {
81 return _compaction_regions;
82 }
83
84 bool G1FullGCCompactionPoint::object_will_fit(size_t size) {
85 size_t space_left = pointer_delta(_current_region->end(), _compaction_top);
86 return size <= space_left;
87 }
88
89 void G1FullGCCompactionPoint::switch_region() {
90 // Save compaction top in the region.
91 _current_region->set_compaction_top(_compaction_top);
92 // Get the next region and re-initialize the values.
93 _current_region = next_region();
94 initialize_values(true);
95 }
96
97 template <bool ALT_FWD>
98 void G1FullGCCompactionPoint::forward(oop object, size_t size) {
99 assert(_current_region != NULL, "Must have been initialized");
100
101 // Ensure the object fit in the current region.
102 while (!object_will_fit(size)) {
103 switch_region();
104 }
105
106 // Store a forwarding pointer if the object should be moved.
107 if (cast_from_oop<HeapWord*>(object) != _compaction_top) {
108 SlidingForwarding::forward_to<ALT_FWD>(object, cast_to_oop(_compaction_top));
109 } else {
110 assert(!SlidingForwarding::is_forwarded(object), "should not be forwarded");
111 /*
112 if (object->forwardee() != NULL) {
113 // Object should not move but mark-word is used so it looks like the
114 // object is forwarded. Need to clear the mark and it's no problem
115 // since it will be restored by preserved marks. There is an exception
116 // with BiasedLocking, in this case forwardee() will return NULL
117 // even if the mark-word is used. This is no problem since
118 // forwardee() will return NULL in the compaction phase as well.
119 object->init_mark();
120 } else {
121 // Make sure object has the correct mark-word set or that it will be
122 // fixed when restoring the preserved marks.
123 assert(object->mark() == markWord::prototype_for_klass(object->klass()) || // Correct mark
124 object->mark_must_be_preserved() || // Will be restored by PreservedMarksSet
125 (UseBiasedLocking && object->has_bias_pattern()), // Will be restored by BiasedLocking
126 "should have correct prototype obj: " PTR_FORMAT " mark: " PTR_FORMAT " prototype: " PTR_FORMAT,
127 p2i(object), object->mark().value(), markWord::prototype_for_klass(object->klass()).value());
128 }
129 assert(object->forwardee() == NULL, "should be forwarded to NULL");
130 */
131 }
132
133 // Update compaction values.
134 _compaction_top += size;
135 if (_compaction_top > _threshold) {
136 _threshold = _current_region->cross_threshold(_compaction_top - size, _compaction_top);
137 }
138 }
139
140 template void G1FullGCCompactionPoint::forward<true>(oop object, size_t size);
141 template void G1FullGCCompactionPoint::forward<false>(oop object, size_t size);
142
143 void G1FullGCCompactionPoint::add(HeapRegion* hr) {
144 _compaction_regions->append(hr);
145 }
146
147 HeapRegion* G1FullGCCompactionPoint::remove_last() {
148 return _compaction_regions->pop();
149 }