1 /*
2 * Copyright (c) 2001, 2017, 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.
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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23 */
24
25 #ifndef SHARE_VM_GC_G1_G1CONCURRENTMARK_INLINE_HPP
26 #define SHARE_VM_GC_G1_G1CONCURRENTMARK_INLINE_HPP
27
28 #include "gc/g1/g1CollectedHeap.inline.hpp"
29 #include "gc/g1/g1ConcurrentMark.hpp"
30 #include "gc/g1/g1ConcurrentMarkBitMap.inline.hpp"
31 #include "gc/g1/g1ConcurrentMarkObjArrayProcessor.inline.hpp"
32 #include "gc/g1/suspendibleThreadSet.hpp"
33 #include "gc/shared/taskqueue.inline.hpp"
34 #include "utilities/bitMap.inline.hpp"
35
36 inline bool G1ConcurrentMark::par_mark(oop obj) {
37 return _nextMarkBitMap->par_mark((HeapWord*)obj);
38 }
39
40 #ifndef PRODUCT
41 template<typename Fn>
42 inline void G1CMMarkStack::iterate(Fn fn) const {
43 assert_at_safepoint(true);
44
45 size_t num_chunks = 0;
46
47 TaskQueueEntryChunk* cur = _chunk_list;
48 while (cur != NULL) {
49 guarantee(num_chunks <= _chunks_in_chunk_list, "Found " SIZE_FORMAT " oop chunks which is more than there should be", num_chunks);
50
51 for (size_t i = 0; i < EntriesPerChunk; ++i) {
52 if (cur->data[i].is_null()) {
53 break;
54 }
55 fn(cur->data[i]);
56 }
57 cur = cur->next;
58 num_chunks++;
59 }
60 }
61 #endif
62
63 // It scans an object and visits its children.
64 inline void G1CMTask::scan_task_entry(G1TaskQueueEntry task_entry) { process_grey_task_entry<true>(task_entry); }
65
66 inline void G1CMTask::push(G1TaskQueueEntry task_entry) {
67 assert(task_entry.is_array_slice() || _g1h->is_in_g1_reserved(task_entry.obj()), "invariant");
68 assert(task_entry.is_array_slice() || !_g1h->is_on_master_free_list(
69 _g1h->heap_region_containing(task_entry.obj())), "invariant");
70 assert(task_entry.is_array_slice() || !_g1h->is_obj_ill(task_entry.obj()), "invariant"); // FIXME!!!
71 assert(task_entry.is_array_slice() || _nextMarkBitMap->is_marked((HeapWord*)task_entry.obj()), "invariant");
72
73 if (!_task_queue->push(task_entry)) {
74 // The local task queue looks full. We need to push some entries
75 // to the global stack.
76 move_entries_to_global_stack();
77
78 // this should succeed since, even if we overflow the global
79 // stack, we should have definitely removed some entries from the
80 // local queue. So, there must be space on it.
81 bool success = _task_queue->push(task_entry);
82 assert(success, "invariant");
83 }
84 }
85
86 inline bool G1CMTask::is_below_finger(oop obj, HeapWord* global_finger) const {
87 // If obj is above the global finger, then the mark bitmap scan
88 // will find it later, and no push is needed. Similarly, if we have
89 // a current region and obj is between the local finger and the
90 // end of the current region, then no push is needed. The tradeoff
91 // of checking both vs only checking the global finger is that the
92 // local check will be more accurate and so result in fewer pushes,
93 // but may also be a little slower.
94 HeapWord* objAddr = (HeapWord*)obj;
95 if (_finger != NULL) {
96 // We have a current region.
97
98 // Finger and region values are all NULL or all non-NULL. We
99 // use _finger to check since we immediately use its value.
100 assert(_curr_region != NULL, "invariant");
101 assert(_region_limit != NULL, "invariant");
102 assert(_region_limit <= global_finger, "invariant");
103
104 // True if obj is less than the local finger, or is between
105 // the region limit and the global finger.
106 if (objAddr < _finger) {
107 return true;
108 } else if (objAddr < _region_limit) {
109 return false;
110 } // Else check global finger.
111 }
112 // Check global finger.
113 return objAddr < global_finger;
114 }
115
116 template<bool scan>
117 inline void G1CMTask::process_grey_task_entry(G1TaskQueueEntry task_entry) {
118 assert(scan || (task_entry.is_oop() && task_entry.obj()->is_typeArray()), "Skipping scan of grey non-typeArray");
119 assert(task_entry.is_array_slice() || _nextMarkBitMap->is_marked((HeapWord*)task_entry.obj()),
120 "Any stolen object should be a slice or marked");
121
122 if (scan) {
123 if (task_entry.is_array_slice()) {
124 _words_scanned += _objArray_processor.process_slice(task_entry.slice());
125 } else {
126 oop obj = task_entry.obj();
127 if (G1CMObjArrayProcessor::should_be_sliced(obj)) {
128 _words_scanned += _objArray_processor.process_obj(obj);
129 } else {
130 _words_scanned += obj->oop_iterate_size(_cm_oop_closure);;
131 }
132 }
133 }
134 check_limits();
135 }
136
137 inline size_t G1CMTask::scan_objArray(objArrayOop obj, MemRegion mr) {
138 obj->oop_iterate(_cm_oop_closure, mr);
139 return mr.word_size();
140 }
141
142 inline void G1CMTask::make_reference_grey(oop obj) {
143 if (_cm->par_mark(obj)) {
144 // No OrderAccess:store_load() is needed. It is implicit in the
145 // CAS done in G1CMBitMap::parMark() call in the routine above.
146 HeapWord* global_finger = _cm->finger();
147
148 // We only need to push a newly grey object on the mark
149 // stack if it is in a section of memory the mark bitmap
150 // scan has already examined. Mark bitmap scanning
151 // maintains progress "fingers" for determining that.
152 //
153 // Notice that the global finger might be moving forward
154 // concurrently. This is not a problem. In the worst case, we
155 // mark the object while it is above the global finger and, by
156 // the time we read the global finger, it has moved forward
157 // past this object. In this case, the object will probably
158 // be visited when a task is scanning the region and will also
159 // be pushed on the stack. So, some duplicate work, but no
160 // correctness problems.
161 if (is_below_finger(obj, global_finger)) {
162 G1TaskQueueEntry entry = G1TaskQueueEntry::from_oop(obj);
163 if (obj->is_typeArray()) {
164 // Immediately process arrays of primitive types, rather
165 // than pushing on the mark stack. This keeps us from
166 // adding humongous objects to the mark stack that might
167 // be reclaimed before the entry is processed - see
168 // selection of candidates for eager reclaim of humongous
169 // objects. The cost of the additional type test is
170 // mitigated by avoiding a trip through the mark stack,
171 // by only doing a bookkeeping update and avoiding the
172 // actual scan of the object - a typeArray contains no
173 // references, and the metadata is built-in.
174 process_grey_task_entry<false>(entry);
175 } else {
176 push(entry);
177 }
178 }
179 }
180 }
181
182 inline void G1CMTask::deal_with_reference(oop obj) {
183 increment_refs_reached();
184
185 HeapWord* objAddr = (HeapWord*) obj;
186 assert(obj->is_oop_or_null(true /* ignore mark word */), "Expected an oop or NULL at " PTR_FORMAT, p2i(obj));
187 if (_g1h->is_in_g1_reserved(objAddr)) {
188 assert(obj != NULL, "null check is implicit");
189 if (!_nextMarkBitMap->is_marked(objAddr)) {
190 // Only get the containing region if the object is not marked on the
191 // bitmap (otherwise, it's a waste of time since we won't do
192 // anything with it).
193 HeapRegion* hr = _g1h->heap_region_containing(obj);
194 if (!hr->obj_allocated_since_next_marking(obj)) {
195 make_reference_grey(obj);
196 }
197 }
198 }
199 }
200
201 inline void G1ConcurrentMark::markPrev(oop p) {
202 assert(!_prevMarkBitMap->is_marked((HeapWord*) p), "sanity");
203 _prevMarkBitMap->mark((HeapWord*) p);
204 }
205
206 bool G1ConcurrentMark::isPrevMarked(oop p) const {
207 assert(p != NULL && p->is_oop(), "expected an oop");
208 return _prevMarkBitMap->is_marked((HeapWord*)p);
209 }
210
211 inline void G1ConcurrentMark::grayRoot(oop obj, HeapRegion* hr) {
212 assert(obj != NULL, "pre-condition");
213 HeapWord* addr = (HeapWord*) obj;
214 if (hr == NULL) {
215 hr = _g1h->heap_region_containing(addr);
216 } else {
217 assert(hr->is_in(addr), "pre-condition");
218 }
219 assert(hr != NULL, "sanity");
220 // Given that we're looking for a region that contains an object
221 // header it's impossible to get back a HC region.
222 assert(!hr->is_continues_humongous(), "sanity");
223
224 if (addr < hr->next_top_at_mark_start()) {
225 if (!_nextMarkBitMap->is_marked(addr)) {
226 par_mark(obj);
227 }
228 }
229 }
230
231 inline bool G1ConcurrentMark::do_yield_check() {
232 if (SuspendibleThreadSet::should_yield()) {
233 SuspendibleThreadSet::yield();
234 return true;
235 } else {
236 return false;
237 }
238 }
239
240 #endif // SHARE_VM_GC_G1_G1CONCURRENTMARK_INLINE_HPP