1 /*
2 * Copyright (c) 1997, 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 "compiler/compileBroker.hpp"
27 #include "gc/serial/markSweep.inline.hpp"
28 #include "gc/shared/collectedHeap.inline.hpp"
29 #include "gc/shared/gcTimer.hpp"
30 #include "gc/shared/gcTrace.hpp"
31 #include "gc/shared/gc_globals.hpp"
32 #include "memory/iterator.inline.hpp"
33 #include "memory/universe.hpp"
34 #include "oops/access.inline.hpp"
35 #include "oops/compressedOops.inline.hpp"
36 #include "oops/instanceClassLoaderKlass.inline.hpp"
37 #include "oops/instanceKlass.inline.hpp"
38 #include "oops/instanceMirrorKlass.inline.hpp"
39 #include "oops/instanceRefKlass.inline.hpp"
40 #include "oops/methodData.hpp"
41 #include "oops/objArrayKlass.inline.hpp"
42 #include "oops/oop.inline.hpp"
43 #include "oops/typeArrayOop.inline.hpp"
44 #include "utilities/macros.hpp"
45 #include "utilities/stack.inline.hpp"
46
47 uint MarkSweep::_total_invocations = 0;
48
49 Stack<oop, mtGC> MarkSweep::_marking_stack;
50 Stack<ObjArrayTask, mtGC> MarkSweep::_objarray_stack;
51
52 Stack<oop, mtGC> MarkSweep::_preserved_oop_stack;
53 Stack<markWord, mtGC> MarkSweep::_preserved_mark_stack;
54 size_t MarkSweep::_preserved_count = 0;
55 size_t MarkSweep::_preserved_count_max = 0;
56 PreservedMark* MarkSweep::_preserved_marks = NULL;
57 ReferenceProcessor* MarkSweep::_ref_processor = NULL;
58 STWGCTimer* MarkSweep::_gc_timer = NULL;
59 SerialOldTracer* MarkSweep::_gc_tracer = NULL;
60
61 MarkSweep::FollowRootClosure MarkSweep::follow_root_closure;
62
63 MarkAndPushClosure MarkSweep::mark_and_push_closure;
64 CLDToOopClosure MarkSweep::follow_cld_closure(&mark_and_push_closure, ClassLoaderData::_claim_strong);
65 CLDToOopClosure MarkSweep::adjust_cld_closure(&adjust_pointer_closure, ClassLoaderData::_claim_strong);
66
67 template <class T> inline void MarkSweep::KeepAliveClosure::do_oop_work(T* p) {
68 mark_and_push(p);
69 }
70
71 void MarkSweep::push_objarray(oop obj, size_t index) {
72 ObjArrayTask task(obj, index);
73 assert(task.is_valid(), "bad ObjArrayTask");
74 _objarray_stack.push(task);
75 }
76
77 inline void MarkSweep::follow_array(objArrayOop array) {
78 MarkSweep::follow_klass(array->klass());
79 // Don't push empty arrays to avoid unnecessary work.
80 if (array->length() > 0) {
81 MarkSweep::push_objarray(array, 0);
82 }
83 }
84
85 inline void MarkSweep::follow_object(oop obj) {
86 assert(obj->is_gc_marked(), "should be marked");
87 if (obj->is_objArray()) {
88 // Handle object arrays explicitly to allow them to
89 // be split into chunks if needed.
90 MarkSweep::follow_array((objArrayOop)obj);
91 } else {
92 obj->oop_iterate(&mark_and_push_closure);
93 }
94 }
95
96 void MarkSweep::follow_array_chunk(objArrayOop array, int index) {
97 const int len = array->length();
98 const int beg_index = index;
99 assert(beg_index < len || len == 0, "index too large");
100
101 const int stride = MIN2(len - beg_index, (int) ObjArrayMarkingStride);
102 const int end_index = beg_index + stride;
103
104 array->oop_iterate_range(&mark_and_push_closure, beg_index, end_index);
105
106 if (end_index < len) {
107 MarkSweep::push_objarray(array, end_index); // Push the continuation.
108 }
109 }
110
111 void MarkSweep::follow_stack() {
112 do {
113 while (!_marking_stack.is_empty()) {
114 oop obj = _marking_stack.pop();
115 assert (obj->is_gc_marked(), "p must be marked");
116 follow_object(obj);
117 }
118 // Process ObjArrays one at a time to avoid marking stack bloat.
119 if (!_objarray_stack.is_empty()) {
120 ObjArrayTask task = _objarray_stack.pop();
121 follow_array_chunk(objArrayOop(task.obj()), task.index());
122 }
123 } while (!_marking_stack.is_empty() || !_objarray_stack.is_empty());
124 }
125
126 MarkSweep::FollowStackClosure MarkSweep::follow_stack_closure;
127
128 void MarkSweep::FollowStackClosure::do_void() { follow_stack(); }
129
130 template <class T> inline void MarkSweep::follow_root(T* p) {
131 assert(!Universe::heap()->is_in(p),
132 "roots shouldn't be things within the heap");
133 T heap_oop = RawAccess<>::oop_load(p);
134 if (!CompressedOops::is_null(heap_oop)) {
135 oop obj = CompressedOops::decode_not_null(heap_oop);
136 if (!obj->mark().is_marked()) {
137 mark_object(obj);
138 follow_object(obj);
139 }
140 }
141 follow_stack();
142 }
143
144 void MarkSweep::FollowRootClosure::do_oop(oop* p) { follow_root(p); }
145 void MarkSweep::FollowRootClosure::do_oop(narrowOop* p) { follow_root(p); }
146
147 void PreservedMark::adjust_pointer() {
148 MarkSweep::adjust_pointer(&_obj);
149 }
150
151 void PreservedMark::restore() {
152 _obj->set_mark(_mark);
153 }
154
155 // We preserve the mark which should be replaced at the end and the location
156 // that it will go. Note that the object that this markWord belongs to isn't
157 // currently at that address but it will be after phase4
158 void MarkSweep::preserve_mark(oop obj, markWord mark) {
159 // We try to store preserved marks in the to space of the new generation since
160 // this is storage which should be available. Most of the time this should be
161 // sufficient space for the marks we need to preserve but if it isn't we fall
162 // back to using Stacks to keep track of the overflow.
163 if (_preserved_count < _preserved_count_max) {
164 _preserved_marks[_preserved_count++].init(obj, mark);
165 } else {
166 _preserved_mark_stack.push(mark);
167 _preserved_oop_stack.push(obj);
168 }
169 }
170
171 void MarkSweep::set_ref_processor(ReferenceProcessor* rp) {
172 _ref_processor = rp;
173 mark_and_push_closure.set_ref_discoverer(_ref_processor);
174 }
175
176 AdjustPointerClosure MarkSweep::adjust_pointer_closure;
177
178 void MarkSweep::adjust_marks() {
179 assert( _preserved_oop_stack.size() == _preserved_mark_stack.size(),
180 "inconsistent preserved oop stacks");
181
182 // adjust the oops we saved earlier
183 for (size_t i = 0; i < _preserved_count; i++) {
184 _preserved_marks[i].adjust_pointer();
185 }
186
187 // deal with the overflow stack
188 StackIterator<oop, mtGC> iter(_preserved_oop_stack);
189 while (!iter.is_empty()) {
190 oop* p = iter.next_addr();
191 adjust_pointer(p);
192 }
193 }
194
195 void MarkSweep::restore_marks() {
196 assert(_preserved_oop_stack.size() == _preserved_mark_stack.size(),
197 "inconsistent preserved oop stacks");
198 log_trace(gc)("Restoring " SIZE_FORMAT " marks", _preserved_count + _preserved_oop_stack.size());
199
200 // restore the marks we saved earlier
201 for (size_t i = 0; i < _preserved_count; i++) {
202 _preserved_marks[i].restore();
203 }
204
205 // deal with the overflow
206 while (!_preserved_oop_stack.is_empty()) {
207 oop obj = _preserved_oop_stack.pop();
208 markWord mark = _preserved_mark_stack.pop();
209 obj->set_mark(mark);
210 }
211 }
212
213 MarkSweep::IsAliveClosure MarkSweep::is_alive;
214
215 bool MarkSweep::IsAliveClosure::do_object_b(oop p) { return p->is_gc_marked(); }
216
217 MarkSweep::KeepAliveClosure MarkSweep::keep_alive;
218
219 void MarkSweep::KeepAliveClosure::do_oop(oop* p) { MarkSweep::KeepAliveClosure::do_oop_work(p); }
220 void MarkSweep::KeepAliveClosure::do_oop(narrowOop* p) { MarkSweep::KeepAliveClosure::do_oop_work(p); }
221
222 void MarkSweep::initialize() {
223 MarkSweep::_gc_timer = new (ResourceObj::C_HEAP, mtGC) STWGCTimer();
224 MarkSweep::_gc_tracer = new (ResourceObj::C_HEAP, mtGC) SerialOldTracer();
225 }