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 // TODO: This method is unused, except in the gunit test. Change the test
44 // to exercise the updated method below instead, and remove this one.
45 void PreservedMarks::adjust_during_full_gc() {
46 StackIterator<OopAndMarkWord, mtGC> iter(_stack);
47 while (!iter.is_empty()) {
48 OopAndMarkWord* elem = iter.next_addr();
49
50 oop obj = elem->get_oop();
51 if (obj->is_forwarded()) {
52 elem->set_oop(obj->forwardee());
53 }
54 }
55 }
56
57 void PreservedMarks::adjust_during_full_gc(const SlidingForwarding* const forwarding) {
58 StackIterator<OopAndMarkWord, mtGC> iter(_stack);
59 while (!iter.is_empty()) {
60 OopAndMarkWord* elem = iter.next_addr();
61
62 oop obj = elem->get_oop();
63 if (obj->is_forwarded()) {
64 elem->set_oop(forwarding->forwardee(obj));
65 }
66 }
67 }
68
69 void PreservedMarks::restore_and_increment(volatile size_t* const total_size_addr) {
70 const size_t stack_size = size();
71 restore();
72 // Only do the atomic add if the size is > 0.
73 if (stack_size > 0) {
74 Atomic::add(total_size_addr, stack_size);
75 }
76 }
77
78 #ifndef PRODUCT
79 void PreservedMarks::assert_empty() {
80 assert(_stack.is_empty(), "stack expected to be empty, size = " SIZE_FORMAT,
81 _stack.size());
82 assert(_stack.cache_size() == 0,
83 "stack expected to have no cached segments, cache size = " SIZE_FORMAT,
84 _stack.cache_size());
85 }
86 #endif // ndef PRODUCT
87
88 void RemoveForwardedPointerClosure::do_object(oop obj) {
89 if (obj->is_forwarded()) {
90 #ifdef _LP64
91 if (UseCompactObjectHeaders) {
92 oop forwardee = obj->forwardee();
93 markWord header = forwardee->mark();
94 if (header.has_displaced_mark_helper()) {
95 header = header.displaced_mark_helper();
96 }
97 assert(UseCompressedClassPointers, "assume +UseCompressedClassPointers");
98 narrowKlass nklass = header.narrow_klass();
99 obj->set_mark(markWord::prototype().set_narrow_klass(nklass));
100 } else
101 #endif
102 {
103 PreservedMarks::init_forwarded_mark(obj);
104 }
105 }
106 }
107
108 void PreservedMarksSet::init(uint num) {
109 assert(_stacks == nullptr && _num == 0, "do not re-initialize");
110 assert(num > 0, "pre-condition");
111 if (_in_c_heap) {
112 _stacks = NEW_C_HEAP_ARRAY(Padded<PreservedMarks>, num, mtGC);
113 } else {
114 _stacks = NEW_RESOURCE_ARRAY(Padded<PreservedMarks>, num);
115 }
116 for (uint i = 0; i < num; i += 1) {
117 ::new (_stacks + i) PreservedMarks();
118 }
119 _num = num;
120
121 assert_empty();
122 }
123
124 class RestorePreservedMarksTask : public AbstractGangTask {
125 PreservedMarksSet* const _preserved_marks_set;
126 SequentialSubTasksDone _sub_tasks;
127 volatile size_t _total_size;
128 #ifdef ASSERT
129 size_t _total_size_before;
130 #endif // ASSERT
131
132 public:
133 void work(uint worker_id) override {
134 uint task_id = 0;
135 while (_sub_tasks.try_claim_task(task_id)) {
136 _preserved_marks_set->get(task_id)->restore_and_increment(&_total_size);
137 }
138 }
139
140 RestorePreservedMarksTask(PreservedMarksSet* preserved_marks_set)
141 : AbstractGangTask("Restore Preserved Marks"),
142 _preserved_marks_set(preserved_marks_set),
143 _sub_tasks(preserved_marks_set->num()),
144 _total_size(0)
145 DEBUG_ONLY(COMMA _total_size_before(0)) {
146 #ifdef ASSERT
147 // This is to make sure the total_size we'll calculate below is correct.
148 for (uint i = 0; i < _preserved_marks_set->num(); ++i) {
149 _total_size_before += _preserved_marks_set->get(i)->size();
150 }
151 #endif // ASSERT
152 }
153
154 ~RestorePreservedMarksTask() {
155 assert(_total_size == _total_size_before, "total_size = %zu before = %zu", _total_size, _total_size_before);
156
157 log_trace(gc)("Restored %zu marks", _total_size);
158 }
159 };
160
161 void PreservedMarksSet::restore(WorkGang* workers) {
162 {
163 RestorePreservedMarksTask cl(this);
164 if (workers == nullptr) {
165 cl.work(0);
166 } else {
167 workers->run_task(&cl);
168 }
169 }
170
171 assert_empty();
172 }
173
174 AbstractGangTask* PreservedMarksSet::create_task() {
175 return new RestorePreservedMarksTask(this);
176 }
177
178 void PreservedMarksSet::reclaim() {
179 assert_empty();
180
181 for (uint i = 0; i < _num; i += 1) {
182 _stacks[i].~Padded<PreservedMarks>();
183 }
184
185 if (_in_c_heap) {
186 FREE_C_HEAP_ARRAY(Padded<PreservedMarks>, _stacks);
187 } else {
188 // the array was resource-allocated, so nothing to do
189 }
190 _stacks = nullptr;
191 _num = 0;
192 }
193
194 #ifndef PRODUCT
195 void PreservedMarksSet::assert_empty() {
196 assert(_stacks != nullptr && _num > 0, "should have been initialized");
197 for (uint i = 0; i < _num; i += 1) {
198 get(i)->assert_empty();
199 }
200 }
201 #endif // ndef PRODUCT