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