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