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