1 /*
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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.
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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).
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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/g1Policy.hpp"
33 #include "gc/g1/g1RegionMarkStatsCache.inline.hpp"
34 #include "gc/g1/g1RemSetTrackingPolicy.hpp"
35 #include "gc/g1/heapRegionRemSet.hpp"
36 #include "gc/g1/heapRegion.hpp"
37 #include "gc/shared/suspendibleThreadSet.hpp"
38 #include "gc/shared/taskqueue.inline.hpp"
39 #include "utilities/bitMap.inline.hpp"
40
41 inline bool G1CMIsAliveClosure::do_object_b(oop obj) {
42 if (obj == NULL) {
43 return false;
44 }
45 assert(_g1h->is_in_reserved(obj), "Asked for liveness of oop " PTR_FORMAT " outside of reserved heap.", p2i(obj));
46 // Young regions have nTAMS == bottom(), i.e. all objects there are implicitly live,
47 // so we do not need to explicitly check for region type.
48 bool result = !_g1h->is_obj_ill(obj, _g1h->heap_region_containing(obj));
49 assert(_g1h->heap_region_containing(obj)->is_old_or_humongous() || result,
50 "Oop " PTR_FORMAT " in young region %u (%s) should be live",
51 p2i(obj), _g1h->addr_to_region((HeapWord*)obj), _g1h->heap_region_containing(obj)->get_short_type_str());
52 return result;
53 }
54
55 inline bool G1CMSubjectToDiscoveryClosure::do_object_b(oop obj) {
56 if (obj == NULL) {
57 return false;
58 }
59 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj));
60 return _g1h->heap_region_containing(obj)->is_old_or_humongous();
61 }
62
63 inline bool G1ConcurrentMark::mark_in_next_bitmap(uint const worker_id, oop const obj, size_t const obj_size) {
64 HeapRegion* const hr = _g1h->heap_region_containing(obj);
65 return mark_in_next_bitmap(worker_id, hr, obj, obj_size);
66 }
67
68 inline bool G1ConcurrentMark::mark_in_next_bitmap(uint const worker_id, HeapRegion* const hr, oop const obj, size_t const obj_size) {
69 assert(hr != NULL, "just checking");
70 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());
71
72 if (hr->obj_allocated_since_next_marking(obj)) {
73 return false;
74 }
75
76 // Some callers may have stale objects to mark above nTAMS after humongous reclaim.
77 // 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.
78 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()));
79
80 HeapWord* const obj_addr = (HeapWord*)obj;
81
82 bool success = _next_mark_bitmap->par_mark(obj_addr);
83 if (success) {
84 add_to_liveness(worker_id, obj, obj_size == 0 ? obj->size() : obj_size);
85 }
86 return success;
87 }
88
89 #ifndef PRODUCT
90 template<typename Fn>
91 inline void G1CMMarkStack::iterate(Fn fn) const {
92 assert_at_safepoint_on_vm_thread();
93
94 size_t num_chunks = 0;
95
96 TaskQueueEntryChunk* cur = _chunk_list;
97 while (cur != NULL) {
98 guarantee(num_chunks <= _chunks_in_chunk_list, "Found " SIZE_FORMAT " oop chunks which is more than there should be", num_chunks);
99
100 for (size_t i = 0; i < EntriesPerChunk; ++i) {
101 if (cur->data[i].is_null()) {
102 break;
103 }
104 fn(cur->data[i]);
105 }
106 cur = cur->next;
107 num_chunks++;
108 }
109 }
110 #endif
111
112 // It scans an object and visits its children.
113 inline void G1CMTask::scan_task_entry(G1TaskQueueEntry task_entry) { process_grey_task_entry<true>(task_entry); }
114
115 inline void G1CMTask::push(G1TaskQueueEntry task_entry) {
116 assert(task_entry.is_array_slice() || _g1h->is_in_g1_reserved(task_entry.obj()), "invariant");
117 assert(task_entry.is_array_slice() || !_g1h->is_on_master_free_list(
118 _g1h->heap_region_containing(task_entry.obj())), "invariant");
119 assert(task_entry.is_array_slice() || !_g1h->is_obj_ill(task_entry.obj()), "invariant"); // FIXME!!!
120 assert(task_entry.is_array_slice() || _next_mark_bitmap->is_marked((HeapWord*)task_entry.obj()), "invariant");
121
122 if (!_task_queue->push(task_entry)) {
123 // The local task queue looks full. We need to push some entries
124 // to the global stack.
125 move_entries_to_global_stack();
126
127 // this should succeed since, even if we overflow the global
128 // stack, we should have definitely removed some entries from the
129 // local queue. So, there must be space on it.
130 bool success = _task_queue->push(task_entry);
131 assert(success, "invariant");
132 }
133 }
134
135 inline bool G1CMTask::is_below_finger(oop obj, HeapWord* global_finger) const {
136 // If obj is above the global finger, then the mark bitmap scan
137 // will find it later, and no push is needed. Similarly, if we have
138 // a current region and obj is between the local finger and the
139 // end of the current region, then no push is needed. The tradeoff
140 // of checking both vs only checking the global finger is that the
141 // local check will be more accurate and so result in fewer pushes,
142 // but may also be a little slower.
143 HeapWord* objAddr = (HeapWord*)obj;
144 if (_finger != NULL) {
145 // We have a current region.
146
147 // Finger and region values are all NULL or all non-NULL. We
148 // use _finger to check since we immediately use its value.
149 assert(_curr_region != NULL, "invariant");
150 assert(_region_limit != NULL, "invariant");
151 assert(_region_limit <= global_finger, "invariant");
152
153 // True if obj is less than the local finger, or is between
154 // the region limit and the global finger.
155 if (objAddr < _finger) {
156 return true;
157 } else if (objAddr < _region_limit) {
158 return false;
159 } // Else check global finger.
160 }
161 // Check global finger.
162 return objAddr < global_finger;
163 }
164
165 template<bool scan>
166 inline void G1CMTask::process_grey_task_entry(G1TaskQueueEntry task_entry) {
167 assert(scan || (task_entry.is_oop() && task_entry.obj()->is_typeArray()), "Skipping scan of grey non-typeArray");
168 assert(task_entry.is_array_slice() || _next_mark_bitmap->is_marked((HeapWord*)task_entry.obj()),
169 "Any stolen object should be a slice or marked");
170
171 if (scan) {
172 if (task_entry.is_array_slice()) {
173 _words_scanned += _objArray_processor.process_slice(task_entry.slice());
174 } else {
175 oop obj = task_entry.obj();
176 if (G1CMObjArrayProcessor::should_be_sliced(obj)) {
177 _words_scanned += _objArray_processor.process_obj(obj);
178 } else {
179 _words_scanned += obj->oop_iterate_size(_cm_oop_closure);;
180 }
181 }
182 }
183 check_limits();
184 }
185
186 inline size_t G1CMTask::scan_objArray(objArrayOop obj, MemRegion mr) {
187 obj->oop_iterate(_cm_oop_closure, mr);
188 return mr.word_size();
189 }
190
191 inline HeapWord* G1ConcurrentMark::top_at_rebuild_start(uint region) const {
192 assert(region < _g1h->max_regions(), "Tried to access TARS for region %u out of bounds", region);
193 return _top_at_rebuild_starts[region];
194 }
195
196 inline void G1ConcurrentMark::update_top_at_rebuild_start(HeapRegion* r) {
197 uint const region = r->hrm_index();
198 assert(region < _g1h->max_regions(), "Tried to access TARS for region %u out of bounds", region);
199 assert(_top_at_rebuild_starts[region] == NULL,
200 "TARS for region %u has already been set to " PTR_FORMAT " should be NULL",
201 region, p2i(_top_at_rebuild_starts[region]));
202 G1RemSetTrackingPolicy* tracker = _g1h->g1_policy()->remset_tracker();
203 if (tracker->needs_scan_for_rebuild(r)) {
204 _top_at_rebuild_starts[region] = r->top();
205 } else {
206 // Leave TARS at NULL.
207 }
208 }
209
210 inline void G1CMTask::update_liveness(oop const obj, const size_t obj_size) {
211 _mark_stats_cache.add_live_words(_g1h->addr_to_region((HeapWord*)obj), obj_size);
212 }
213
214 inline void G1ConcurrentMark::add_to_liveness(uint worker_id, oop const obj, size_t size) {
215 task(worker_id)->update_liveness(obj, size);
216 }
217
218 inline bool G1CMTask::make_reference_grey(oop obj) {
219 if (!_cm->mark_in_next_bitmap(_worker_id, obj)) {
220 return false;
221 }
222
223 // No OrderAccess:store_load() is needed. It is implicit in the
224 // CAS done in G1CMBitMap::parMark() call in the routine above.
225 HeapWord* global_finger = _cm->finger();
226
227 // We only need to push a newly grey object on the mark
228 // stack if it is in a section of memory the mark bitmap
229 // scan has already examined. Mark bitmap scanning
230 // maintains progress "fingers" for determining that.
231 //
232 // Notice that the global finger might be moving forward
233 // concurrently. This is not a problem. In the worst case, we
234 // mark the object while it is above the global finger and, by
235 // the time we read the global finger, it has moved forward
236 // past this object. In this case, the object will probably
237 // be visited when a task is scanning the region and will also
238 // be pushed on the stack. So, some duplicate work, but no
239 // correctness problems.
240 if (is_below_finger(obj, global_finger)) {
241 G1TaskQueueEntry entry = G1TaskQueueEntry::from_oop(obj);
242 if (obj->is_typeArray()) {
243 // Immediately process arrays of primitive types, rather
244 // than pushing on the mark stack. This keeps us from
245 // adding humongous objects to the mark stack that might
246 // be reclaimed before the entry is processed - see
247 // selection of candidates for eager reclaim of humongous
248 // objects. The cost of the additional type test is
249 // mitigated by avoiding a trip through the mark stack,
250 // by only doing a bookkeeping update and avoiding the
251 // actual scan of the object - a typeArray contains no
252 // references, and the metadata is built-in.
253 process_grey_task_entry<false>(entry);
254 } else {
255 push(entry);
256 }
257 }
258 return true;
259 }
260
261 template <class T>
262 inline bool G1CMTask::deal_with_reference(T* p) {
263 increment_refs_reached();
264 oop const obj = RawAccess<MO_VOLATILE>::oop_load(p);
265 return (obj != NULL) && make_reference_grey(obj);
266 }
267
268 inline void G1ConcurrentMark::mark_in_prev_bitmap(oop p) {
269 assert(!_prev_mark_bitmap->is_marked((HeapWord*) p), "sanity");
270 _prev_mark_bitmap->mark((HeapWord*) p);
271 }
272
273 bool G1ConcurrentMark::is_marked_in_prev_bitmap(oop p) const {
274 assert(p != NULL && oopDesc::is_oop(p), "expected an oop");
275 return _prev_mark_bitmap->is_marked((HeapWord*)p);
276 }
277
278 bool G1ConcurrentMark::is_marked_in_next_bitmap(oop p) const {
279 assert(p != NULL && oopDesc::is_oop(p), "expected an oop");
280 return _next_mark_bitmap->is_marked((HeapWord*)p);
281 }
282
283 inline bool G1ConcurrentMark::do_yield_check() {
284 if (SuspendibleThreadSet::should_yield()) {
285 SuspendibleThreadSet::yield();
286 return true;
287 } else {
288 return false;
289 }
290 }
291
292 #endif // SHARE_VM_GC_G1_G1CONCURRENTMARK_INLINE_HPP