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