1 /*
2 * Copyright (c) 2016, 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/shared/preservedMarks.inline.hpp"
27 #include "gc/shared/slidingForwarding.inline.hpp"
28 #include "gc/shared/workgroup.hpp"
29 #include "memory/allocation.inline.hpp"
30 #include "memory/resourceArea.hpp"
31 #include "oops/oop.inline.hpp"
32 #include "runtime/atomic.hpp"
33 #include "utilities/macros.hpp"
34
35 void PreservedMarks::restore() {
36 while (!_stack.is_empty()) {
37 const OopAndMarkWord elem = _stack.pop();
38 elem.set_mark();
39 }
40 assert_empty();
41 }
42
43 template <bool ALT_FWD>
44 void PreservedMarks::adjust_during_full_gc_impl() {
45 StackIterator<OopAndMarkWord, mtGC> iter(_stack);
46 while (!iter.is_empty()) {
47 OopAndMarkWord* elem = iter.next_addr();
48
49 oop obj = elem->get_oop();
50 if (SlidingForwarding::is_forwarded(obj)) {
51 elem->set_oop(SlidingForwarding::forwardee<ALT_FWD>(obj));
52 }
53 }
54 }
55
56 void PreservedMarks::adjust_during_full_gc() {
57 if (UseAltGCForwarding) {
58 adjust_during_full_gc_impl<true>();
59 } else {
60 adjust_during_full_gc_impl<false>();
61 }
62 }
63
64 void PreservedMarks::restore_and_increment(volatile size_t* const total_size_addr) {
65 const size_t stack_size = size();
66 restore();
67 // Only do the atomic add if the size is > 0.
68 if (stack_size > 0) {
69 Atomic::add(total_size_addr, stack_size);
70 }
71 }
72
73 #ifndef PRODUCT
74 void PreservedMarks::assert_empty() {
75 assert(_stack.is_empty(), "stack expected to be empty, size = " SIZE_FORMAT,
76 _stack.size());
77 assert(_stack.cache_size() == 0,
78 "stack expected to have no cached segments, cache size = " SIZE_FORMAT,
79 _stack.cache_size());
80 }
81 #endif // ndef PRODUCT
82
83 void RemoveForwardedPointerClosure::do_object(oop obj) {
84 if (obj->is_forwarded()) {
85 PreservedMarks::init_forwarded_mark(obj);
86 }
87 }
88
89 void PreservedMarksSet::init(uint num) {
90 assert(_stacks == nullptr && _num == 0, "do not re-initialize");
91 assert(num > 0, "pre-condition");
92 if (_in_c_heap) {
93 _stacks = NEW_C_HEAP_ARRAY(Padded<PreservedMarks>, num, mtGC);
94 } else {
95 _stacks = NEW_RESOURCE_ARRAY(Padded<PreservedMarks>, num);
96 }
97 for (uint i = 0; i < num; i += 1) {
98 ::new (_stacks + i) PreservedMarks();
99 }
100 _num = num;
101
102 assert_empty();
103 }
104
105 class RestorePreservedMarksTask : public AbstractGangTask {
106 PreservedMarksSet* const _preserved_marks_set;
107 SequentialSubTasksDone _sub_tasks;
108 volatile size_t _total_size;
109 #ifdef ASSERT
110 size_t _total_size_before;
111 #endif // ASSERT
112
113 public:
114 void work(uint worker_id) override {
115 uint task_id = 0;
116 while (_sub_tasks.try_claim_task(task_id)) {
117 _preserved_marks_set->get(task_id)->restore_and_increment(&_total_size);
118 }
119 }
120
121 RestorePreservedMarksTask(PreservedMarksSet* preserved_marks_set)
122 : AbstractGangTask("Restore Preserved Marks"),
123 _preserved_marks_set(preserved_marks_set),
124 _sub_tasks(preserved_marks_set->num()),
125 _total_size(0)
126 DEBUG_ONLY(COMMA _total_size_before(0)) {
127 #ifdef ASSERT
128 // This is to make sure the total_size we'll calculate below is correct.
129 for (uint i = 0; i < _preserved_marks_set->num(); ++i) {
130 _total_size_before += _preserved_marks_set->get(i)->size();
131 }
132 #endif // ASSERT
133 }
134
135 ~RestorePreservedMarksTask() {
136 assert(_total_size == _total_size_before, "total_size = %zu before = %zu", _total_size, _total_size_before);
137
138 log_trace(gc)("Restored %zu marks", _total_size);
139 }
140 };
141
142 void PreservedMarksSet::restore(WorkGang* workers) {
143 {
144 RestorePreservedMarksTask cl(this);
145 if (workers == nullptr) {
146 cl.work(0);
147 } else {
148 workers->run_task(&cl);
149 }
150 }
151
152 assert_empty();
153 }
154
155 AbstractGangTask* PreservedMarksSet::create_task() {
156 return new RestorePreservedMarksTask(this);
157 }
158
159 void PreservedMarksSet::reclaim() {
160 assert_empty();
161
162 for (uint i = 0; i < _num; i += 1) {
163 _stacks[i].~Padded<PreservedMarks>();
164 }
165
166 if (_in_c_heap) {
167 FREE_C_HEAP_ARRAY(Padded<PreservedMarks>, _stacks);
168 } else {
169 // the array was resource-allocated, so nothing to do
170 }
171 _stacks = nullptr;
172 _num = 0;
173 }
174
175 #ifndef PRODUCT
176 void PreservedMarksSet::assert_empty() {
177 assert(_stacks != nullptr && _num > 0, "should have been initialized");
178 for (uint i = 0; i < _num; i += 1) {
179 get(i)->assert_empty();
180 }
181 }
182 #endif // ndef PRODUCT