1 /*
2 * Copyright (c) 1997, 2015, 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/specialized_oop_closures.hpp"
32 #include "memory/iterator.inline.hpp"
33 #include "oops/instanceClassLoaderKlass.inline.hpp"
34 #include "oops/instanceKlass.inline.hpp"
35 #include "oops/instanceMirrorKlass.inline.hpp"
36 #include "oops/instanceRefKlass.inline.hpp"
37 #include "oops/methodData.hpp"
38 #include "oops/objArrayKlass.inline.hpp"
39 #include "oops/oop.inline.hpp"
40 #include "oops/typeArrayOop.inline.hpp"
41 #include "utilities/macros.hpp"
42 #include "utilities/stack.inline.hpp"
43 #if INCLUDE_ALL_GCS
44 #include "gc/g1/g1StringDedup.hpp"
45 #endif // INCLUDE_ALL_GCS
46
47 uint MarkSweep::_total_invocations = 0;
48
49 STWGCTimer* MarkSweep::_gc_timer = NULL;
50 SerialOldTracer* MarkSweep::_gc_tracer = NULL;
51
52 MarkSweep::MarkSweep() :
53 _marking_stack(),
54 _objarray_stack(),
55 _preserved_mark_stack(),
56 _preserved_oop_stack(),
57 _preserved_count(0),
58 _preserved_count_max(0),
59 _preserved_marks(NULL),
60 _ref_processor(NULL),
61 keep_alive(this),
62 is_alive(this),
63 follow_root_closure(this),
64 mark_and_push_closure(this),
65 follow_stack_closure(this),
66 follow_cld_closure(&mark_and_push_closure),
67 adjust_pointer_closure(),
68 adjust_cld_closure(&adjust_pointer_closure)
69 {
70 }
71
72 MarkSweep::~MarkSweep()
73 {
74 }
75
76 inline void MarkSweep::mark_object(oop obj) {
77 #if INCLUDE_ALL_GCS
78 if (G1StringDedup::is_enabled()) {
79 // We must enqueue the object before it is marked
80 // as we otherwise can't read the object's age.
81 G1StringDedup::enqueue_from_mark(obj);
82 }
83 #endif
84 // some marks may contain information we need to preserve so we store them away
85 // and overwrite the mark. We'll restore it at the end of markSweep.
86 markOop mark = obj->mark();
87 obj->set_mark(markOopDesc::prototype()->set_marked());
88
89 if (mark->must_be_preserved(obj)) {
90 preserve_mark(obj, mark);
91 }
92 }
93
94 template <class T> inline void MarkSweep::mark_and_push(T* p) {
95 T heap_oop = oopDesc::load_heap_oop(p);
96 if (!oopDesc::is_null(heap_oop)) {
97 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
98 if (!obj->mark()->is_marked() &&
99 !is_archive_object(obj)) {
100 mark_object(obj);
101 _marking_stack.push(obj);
102 }
103 }
104 }
105
106 inline void MarkSweep::follow_klass(Klass* klass) {
107 oop op = klass->klass_holder();
108 mark_and_push(&op);
109 }
110
111 inline void MarkSweep::follow_cld(ClassLoaderData* cld) {
112 follow_cld_closure.do_cld(cld);
113 }
114
115 template <typename T>
116 inline void MarkAndPushClosure::do_oop_nv(T* p) { _ms->mark_and_push(p); }
117 void MarkAndPushClosure::do_oop(oop* p) { do_oop_nv(p); }
118 void MarkAndPushClosure::do_oop(narrowOop* p) { do_oop_nv(p); }
119 inline bool MarkAndPushClosure::do_metadata_nv() { return true; }
120 bool MarkAndPushClosure::do_metadata() { return do_metadata_nv(); }
121 inline void MarkAndPushClosure::do_klass_nv(Klass* k) { _ms->follow_klass(k); }
122 void MarkAndPushClosure::do_klass(Klass* k) { do_klass_nv(k); }
123 inline void MarkAndPushClosure::do_cld_nv(ClassLoaderData* cld) { _ms->follow_cld(cld); }
124 void MarkAndPushClosure::do_cld(ClassLoaderData* cld) { do_cld_nv(cld); }
125
126 template <class T> inline void MarkSweep::KeepAliveClosure::do_oop_work(T* p) {
127 _ms->mark_and_push(p);
128 }
129
130 void MarkSweep::push_objarray(oop obj, size_t index) {
131 ObjArrayTask task(obj, index);
132 assert(task.is_valid(), "bad ObjArrayTask");
133 _objarray_stack.push(task);
134 }
135
136 inline void MarkSweep::follow_array(objArrayOop array) {
137 follow_klass(array->klass());
138 // Don't push empty arrays to avoid unnecessary work.
139 if (array->length() > 0) {
140 push_objarray(array, 0);
141 }
142 }
143
144 inline void MarkSweep::follow_object(oop obj) {
145 assert(obj->is_gc_marked(), "should be marked");
146 if (obj->is_objArray()) {
147 // Handle object arrays explicitly to allow them to
148 // be split into chunks if needed.
149 follow_array((objArrayOop)obj);
150 } else {
151 obj->oop_iterate(&mark_and_push_closure);
152 }
153 }
154
155 void MarkSweep::follow_array_chunk(objArrayOop array, int index) {
156 const int len = array->length();
157 const int beg_index = index;
158 assert(beg_index < len || len == 0, "index too large");
159
160 const int stride = MIN2(len - beg_index, (int) ObjArrayMarkingStride);
161 const int end_index = beg_index + stride;
162
163 array->oop_iterate_range(&mark_and_push_closure, beg_index, end_index);
164
165 if (end_index < len) {
166 push_objarray(array, end_index); // Push the continuation.
167 }
168 }
169
170 void MarkSweep::follow_stack() {
171 do {
172 while (!_marking_stack.is_empty()) {
173 oop obj = _marking_stack.pop();
174 assert (obj->is_gc_marked(), "p must be marked");
175 follow_object(obj);
176 }
177 // Process ObjArrays one at a time to avoid marking stack bloat.
178 if (!_objarray_stack.is_empty()) {
179 ObjArrayTask task = _objarray_stack.pop();
180 follow_array_chunk(objArrayOop(task.obj()), task.index());
181 }
182 } while (!_marking_stack.is_empty() || !_objarray_stack.is_empty());
183 }
184
185 void MarkSweep::FollowStackClosure::do_void() { _ms->follow_stack(); }
186
187 template <class T> inline void MarkSweep::follow_root(T* p) {
188 assert(!Universe::heap()->is_in_reserved(p),
189 "roots shouldn't be things within the heap");
190 T heap_oop = oopDesc::load_heap_oop(p);
191 if (!oopDesc::is_null(heap_oop)) {
192 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
193 if (!obj->mark()->is_marked() &&
194 !is_archive_object(obj)) {
195 mark_object(obj);
196 follow_object(obj);
197 }
198 }
199 follow_stack();
200 }
201
202 void MarkSweep::FollowRootClosure::do_oop(oop* p) { _ms->follow_root(p); }
203 void MarkSweep::FollowRootClosure::do_oop(narrowOop* p) { _ms->follow_root(p); }
204
205 void PreservedMark::adjust_pointer() {
206 MarkSweep::adjust_pointer(&_obj);
207 }
208
209 void PreservedMark::restore() {
210 _obj->set_mark(_mark);
211 }
212
213 // We preserve the mark which should be replaced at the end and the location
214 // that it will go. Note that the object that this markOop belongs to isn't
215 // currently at that address but it will be after phase4
216 void MarkSweep::preserve_mark(oop obj, markOop mark) {
217 // We try to store preserved marks in the to space of the new generation since
218 // this is storage which should be available. Most of the time this should be
219 // sufficient space for the marks we need to preserve but if it isn't we fall
220 // back to using Stacks to keep track of the overflow.
221 if (_preserved_count < _preserved_count_max) {
222 _preserved_marks[_preserved_count++].init(obj, mark);
223 } else {
224 _preserved_mark_stack.push(mark);
225 _preserved_oop_stack.push(obj);
226 }
227 }
228
229 void MarkSweep::set_ref_processor(ReferenceProcessor* rp) {
230 _ref_processor = rp;
231 mark_and_push_closure.set_ref_processor(_ref_processor);
232 }
233
234 template <typename T>
235 void MarkSweep::AdjustPointerClosure::do_oop_nv(T* p) { adjust_pointer(p); }
236 void MarkSweep::AdjustPointerClosure::do_oop(oop* p) { do_oop_nv(p); }
237 void MarkSweep::AdjustPointerClosure::do_oop(narrowOop* p) { do_oop_nv(p); }
238
239 void MarkSweep::adjust_marks() {
240 assert( _preserved_oop_stack.size() == _preserved_mark_stack.size(),
241 "inconsistent preserved oop stacks");
242
243 // adjust the oops we saved earlier
244 for (size_t i = 0; i < _preserved_count; i++) {
245 _preserved_marks[i].adjust_pointer();
246 }
247
248 // deal with the overflow stack
249 StackIterator<oop, mtGC> iter(_preserved_oop_stack);
250 while (!iter.is_empty()) {
251 oop* p = iter.next_addr();
252 adjust_pointer(p);
253 }
254 }
255
256 void MarkSweep::restore_marks() {
257 assert(_preserved_oop_stack.size() == _preserved_mark_stack.size(),
258 "inconsistent preserved oop stacks");
259 log_trace(gc)("Restoring " SIZE_FORMAT " marks", _preserved_count + _preserved_oop_stack.size());
260
261 // restore the marks we saved earlier
262 for (size_t i = 0; i < _preserved_count; i++) {
263 _preserved_marks[i].restore();
264 }
265
266 // deal with the overflow
267 while (!_preserved_oop_stack.is_empty()) {
268 oop obj = _preserved_oop_stack.pop();
269 markOop mark = _preserved_mark_stack.pop();
270 obj->set_mark(mark);
271 }
272 }
273
274 bool MarkSweep::IsAliveClosure::do_object_b(oop p) { return p->is_gc_marked() || is_archive_object(p); }
275
276 void MarkSweep::KeepAliveClosure::do_oop(oop* p) { do_oop_work(p); }
277 void MarkSweep::KeepAliveClosure::do_oop(narrowOop* p) { do_oop_work(p); }
278
279 void marksweep_init() {
280 MarkSweep::_gc_timer = new (ResourceObj::C_HEAP, mtGC) STWGCTimer();
281 MarkSweep::_gc_tracer = new (ResourceObj::C_HEAP, mtGC) SerialOldTracer();
282 }
283
284 int InstanceKlass::oop_ms_adjust_pointers(oop obj, MarkSweep* ms) {
285 int size = size_helper();
286 oop_oop_iterate_oop_maps<true>(obj, &ms->adjust_pointer_closure);
287 return size;
288 }
289
290 int InstanceMirrorKlass::oop_ms_adjust_pointers(oop obj, MarkSweep* ms) {
291 int size = oop_size(obj);
292 InstanceKlass::oop_ms_adjust_pointers(obj, ms);
293
294 oop_oop_iterate_statics<true>(obj, &ms->adjust_pointer_closure);
295 return size;
296 }
297
298 int InstanceClassLoaderKlass::oop_ms_adjust_pointers(oop obj, MarkSweep* ms) {
299 return InstanceKlass::oop_ms_adjust_pointers(obj, ms);
300 }
301
302 #ifdef ASSERT
303 template <class T> static void trace_reference_gc(const char *s, oop obj,
304 T* referent_addr,
305 T* next_addr,
306 T* discovered_addr) {
307 log_develop_trace(gc, ref)("%s obj " PTR_FORMAT, s, p2i(obj));
308 log_develop_trace(gc, ref)(" referent_addr/* " PTR_FORMAT " / " PTR_FORMAT,
309 p2i(referent_addr), p2i(referent_addr ? (address)oopDesc::load_decode_heap_oop(referent_addr) : NULL));
310 log_develop_trace(gc, ref)(" next_addr/* " PTR_FORMAT " / " PTR_FORMAT,
311 p2i(next_addr), p2i(next_addr ? (address)oopDesc::load_decode_heap_oop(next_addr) : NULL));
312 log_develop_trace(gc, ref)(" discovered_addr/* " PTR_FORMAT " / " PTR_FORMAT,
313 p2i(discovered_addr), p2i(discovered_addr ? (address)oopDesc::load_decode_heap_oop(discovered_addr) : NULL));
314 }
315 #endif
316
317 template <class T> void static adjust_object_specialized(oop obj) {
318 T* referent_addr = (T*)java_lang_ref_Reference::referent_addr(obj);
319 MarkSweep::adjust_pointer(referent_addr);
320 T* next_addr = (T*)java_lang_ref_Reference::next_addr(obj);
321 MarkSweep::adjust_pointer(next_addr);
322 T* discovered_addr = (T*)java_lang_ref_Reference::discovered_addr(obj);
323 MarkSweep::adjust_pointer(discovered_addr);
324 debug_only(trace_reference_gc("InstanceRefKlass::oop_ms_adjust_pointers", obj,
325 referent_addr, next_addr, discovered_addr);)
326 }
327
328 int InstanceRefKlass::oop_ms_adjust_pointers(oop obj, MarkSweep* ms) {
329 int size = size_helper();
330 InstanceKlass::oop_ms_adjust_pointers(obj, ms);
331
332 if (UseCompressedOops) {
333 adjust_object_specialized<narrowOop>(obj);
334 } else {
335 adjust_object_specialized<oop>(obj);
336 }
337 return size;
338 }
339
340 int ObjArrayKlass::oop_ms_adjust_pointers(oop obj, MarkSweep* ms) {
341 assert(obj->is_objArray(), "obj must be obj array");
342 objArrayOop a = objArrayOop(obj);
343 // Get size before changing pointers.
344 // Don't call size() or oop_size() since that is a virtual call.
345 int size = a->object_size();
346 oop_oop_iterate_elements<true>(a, &ms->adjust_pointer_closure);
347 return size;
348 }
349
350 int TypeArrayKlass::oop_ms_adjust_pointers(oop obj, MarkSweep* /* ms */) {
351 assert(obj->is_typeArray(), "must be a type array");
352 typeArrayOop t = typeArrayOop(obj);
353 // Performance tweak: We skip iterating over the klass pointer since we
354 // know that Universe::TypeArrayKlass never moves.
355 return t->object_size();
356 }
357
358 // Generate MS specialized oop_oop_iterate functions.
359 SPECIALIZED_OOP_OOP_ITERATE_CLOSURES_MS(ALL_KLASS_OOP_OOP_ITERATE_DEFN)