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 *
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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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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/g1ConcurrentMarkObjArrayProcessor.inline.hpp"
31 #include "gc/g1/suspendibleThreadSet.hpp"
32 #include "gc/shared/taskqueue.inline.hpp"
33 #include "utilities/bitMap.inline.hpp"
34
35 inline bool G1ConcurrentMark::par_mark(oop obj) {
36 return _nextMarkBitMap->parMark((HeapWord*)obj);
37 }
38
39 inline bool G1CMBitMapRO::iterate(BitMapClosure* cl, MemRegion mr) {
40 HeapWord* start_addr = MAX2(startWord(), mr.start());
41 HeapWord* end_addr = MIN2(endWord(), mr.end());
42
43 if (end_addr > start_addr) {
44 // Right-open interval [start-offset, end-offset).
45 BitMap::idx_t start_offset = heapWordToOffset(start_addr);
46 BitMap::idx_t end_offset = heapWordToOffset(end_addr);
47
48 start_offset = _bm.get_next_one_offset(start_offset, end_offset);
49 while (start_offset < end_offset) {
50 if (!cl->do_bit(start_offset)) {
51 return false;
52 }
53 HeapWord* next_addr = MIN2(nextObject(offsetToHeapWord(start_offset)), end_addr);
54 BitMap::idx_t next_offset = heapWordToOffset(next_addr);
55 start_offset = _bm.get_next_one_offset(next_offset, end_offset);
56 }
57 }
58 return true;
59 }
60
61 // The argument addr should be the start address of a valid object
62 HeapWord* G1CMBitMapRO::nextObject(HeapWord* addr) {
63 oop obj = (oop) addr;
64 HeapWord* res = addr + obj->size();
65 assert(offsetToHeapWord(heapWordToOffset(res)) == res, "sanity");
66 return res;
67 }
68
69 #define check_mark(addr) \
70 assert(_bmStartWord <= (addr) && (addr) < (_bmStartWord + _bmWordSize), \
71 "outside underlying space?"); \
72 assert(G1CollectedHeap::heap()->is_in_exact(addr), \
73 "Trying to access not available bitmap " PTR_FORMAT \
74 " corresponding to " PTR_FORMAT " (%u)", \
75 p2i(this), p2i(addr), G1CollectedHeap::heap()->addr_to_region(addr));
76
77 inline void G1CMBitMap::mark(HeapWord* addr) {
78 check_mark(addr);
79 _bm.set_bit(heapWordToOffset(addr));
80 }
81
82 inline void G1CMBitMap::clear(HeapWord* addr) {
83 check_mark(addr);
84 _bm.clear_bit(heapWordToOffset(addr));
85 }
86
87 inline bool G1CMBitMap::parMark(HeapWord* addr) {
88 check_mark(addr);
89 return _bm.par_set_bit(heapWordToOffset(addr));
90 }
91
92 #undef check_mark
93
94 #ifndef PRODUCT
95 template<typename Fn>
96 inline void G1CMMarkStack::iterate(Fn fn) const {
97 assert_at_safepoint(true);
98
99 size_t num_chunks = 0;
100
101 TaskQueueEntryChunk* cur = _chunk_list;
102 while (cur != NULL) {
103 guarantee(num_chunks <= _chunks_in_chunk_list, "Found " SIZE_FORMAT " oop chunks which is more than there should be", num_chunks);
104
105 for (size_t i = 0; i < EntriesPerChunk; ++i) {
106 if (cur->data[i].is_null()) {
107 break;
108 }
109 fn(cur->data[i]);
110 }
111 cur = cur->next;
112 num_chunks++;
113 }
114 }
115 #endif
116
117 // It scans an object and visits its children.
118 inline void G1CMTask::scan_task_entry(G1TaskQueueEntry task_entry) { process_grey_task_entry<true>(task_entry); }
119
120 inline void G1CMTask::push(G1TaskQueueEntry task_entry) {
121 assert(task_entry.is_array_slice() || _g1h->is_in_g1_reserved(task_entry.obj()), "invariant");
122 assert(task_entry.is_array_slice() || !_g1h->is_on_master_free_list(
123 _g1h->heap_region_containing(task_entry.obj())), "invariant");
124 assert(task_entry.is_array_slice() || !_g1h->is_obj_ill(task_entry.obj()), "invariant"); // FIXME!!!
125 assert(task_entry.is_array_slice() || _nextMarkBitMap->isMarked((HeapWord*)task_entry.obj()), "invariant");
126
127 if (!_task_queue->push(task_entry)) {
128 // The local task queue looks full. We need to push some entries
129 // to the global stack.
130 move_entries_to_global_stack();
131
132 // this should succeed since, even if we overflow the global
133 // stack, we should have definitely removed some entries from the
134 // local queue. So, there must be space on it.
135 bool success = _task_queue->push(task_entry);
136 assert(success, "invariant");
137 }
138 }
139
140 inline bool G1CMTask::is_below_finger(oop obj, HeapWord* global_finger) const {
141 // If obj is above the global finger, then the mark bitmap scan
142 // will find it later, and no push is needed. Similarly, if we have
143 // a current region and obj is between the local finger and the
144 // end of the current region, then no push is needed. The tradeoff
145 // of checking both vs only checking the global finger is that the
146 // local check will be more accurate and so result in fewer pushes,
147 // but may also be a little slower.
148 HeapWord* objAddr = (HeapWord*)obj;
149 if (_finger != NULL) {
150 // We have a current region.
151
152 // Finger and region values are all NULL or all non-NULL. We
153 // use _finger to check since we immediately use its value.
154 assert(_curr_region != NULL, "invariant");
155 assert(_region_limit != NULL, "invariant");
156 assert(_region_limit <= global_finger, "invariant");
157
158 // True if obj is less than the local finger, or is between
159 // the region limit and the global finger.
160 if (objAddr < _finger) {
161 return true;
162 } else if (objAddr < _region_limit) {
163 return false;
164 } // Else check global finger.
165 }
166 // Check global finger.
167 return objAddr < global_finger;
168 }
169
170 template<bool scan>
171 inline void G1CMTask::process_grey_task_entry(G1TaskQueueEntry task_entry) {
172 assert(scan || (task_entry.is_oop() && task_entry.obj()->is_typeArray()), "Skipping scan of grey non-typeArray");
173 assert(task_entry.is_array_slice() || _nextMarkBitMap->isMarked((HeapWord*)task_entry.obj()),
174 "Any stolen object should be a slice or marked");
175
176 if (scan) {
177 if (task_entry.is_array_slice()) {
178 _words_scanned += _objArray_processor.process_slice(task_entry.slice());
179 } else {
180 oop obj = task_entry.obj();
181 if (G1CMObjArrayProcessor::should_be_sliced(obj)) {
182 _words_scanned += _objArray_processor.process_obj(obj);
183 } else {
184 _words_scanned += obj->oop_iterate_size(_cm_oop_closure);;
185 }
186 }
187 }
188 check_limits();
189 }
190
191 inline size_t G1CMTask::scan_objArray(objArrayOop obj, MemRegion mr) {
192 obj->oop_iterate(_cm_oop_closure, mr);
193 return mr.word_size();
194 }
195
196 inline void G1CMTask::make_reference_grey(oop obj) {
197 if (_cm->par_mark(obj)) {
198 // No OrderAccess:store_load() is needed. It is implicit in the
199 // CAS done in G1CMBitMap::parMark() call in the routine above.
200 HeapWord* global_finger = _cm->finger();
201
202 // We only need to push a newly grey object on the mark
203 // stack if it is in a section of memory the mark bitmap
204 // scan has already examined. Mark bitmap scanning
205 // maintains progress "fingers" for determining that.
206 //
207 // Notice that the global finger might be moving forward
208 // concurrently. This is not a problem. In the worst case, we
209 // mark the object while it is above the global finger and, by
210 // the time we read the global finger, it has moved forward
211 // past this object. In this case, the object will probably
212 // be visited when a task is scanning the region and will also
213 // be pushed on the stack. So, some duplicate work, but no
214 // correctness problems.
215 if (is_below_finger(obj, global_finger)) {
216 G1TaskQueueEntry entry = G1TaskQueueEntry::from_oop(obj);
217 if (obj->is_typeArray()) {
218 // Immediately process arrays of primitive types, rather
219 // than pushing on the mark stack. This keeps us from
220 // adding humongous objects to the mark stack that might
221 // be reclaimed before the entry is processed - see
222 // selection of candidates for eager reclaim of humongous
223 // objects. The cost of the additional type test is
224 // mitigated by avoiding a trip through the mark stack,
225 // by only doing a bookkeeping update and avoiding the
226 // actual scan of the object - a typeArray contains no
227 // references, and the metadata is built-in.
228 process_grey_task_entry<false>(entry);
229 } else {
230 push(entry);
231 }
232 }
233 }
234 }
235
236 inline void G1CMTask::deal_with_reference(oop obj) {
237 increment_refs_reached();
238
239 HeapWord* objAddr = (HeapWord*) obj;
240 assert(obj->is_oop_or_null(true /* ignore mark word */), "Expected an oop or NULL at " PTR_FORMAT, p2i(obj));
241 if (_g1h->is_in_g1_reserved(objAddr)) {
242 assert(obj != NULL, "null check is implicit");
243 if (!_nextMarkBitMap->isMarked(objAddr)) {
244 // Only get the containing region if the object is not marked on the
245 // bitmap (otherwise, it's a waste of time since we won't do
246 // anything with it).
247 HeapRegion* hr = _g1h->heap_region_containing(obj);
248 if (!hr->obj_allocated_since_next_marking(obj)) {
249 make_reference_grey(obj);
250 }
251 }
252 }
253 }
254
255 inline void G1ConcurrentMark::markPrev(oop p) {
256 assert(!_prevMarkBitMap->isMarked((HeapWord*) p), "sanity");
257 // Note we are overriding the read-only view of the prev map here, via
258 // the cast.
259 ((G1CMBitMap*)_prevMarkBitMap)->mark((HeapWord*) p);
260 }
261
262 bool G1ConcurrentMark::isPrevMarked(oop p) const {
263 assert(p != NULL && p->is_oop(), "expected an oop");
264 HeapWord* addr = (HeapWord*)p;
265 assert(addr >= _prevMarkBitMap->startWord() ||
266 addr < _prevMarkBitMap->endWord(), "in a region");
267
268 return _prevMarkBitMap->isMarked(addr);
269 }
270
271 inline void G1ConcurrentMark::grayRoot(oop obj, HeapRegion* hr) {
272 assert(obj != NULL, "pre-condition");
273 HeapWord* addr = (HeapWord*) obj;
274 if (hr == NULL) {
275 hr = _g1h->heap_region_containing(addr);
276 } else {
277 assert(hr->is_in(addr), "pre-condition");
278 }
279 assert(hr != NULL, "sanity");
280 // Given that we're looking for a region that contains an object
281 // header it's impossible to get back a HC region.
282 assert(!hr->is_continues_humongous(), "sanity");
283
284 if (addr < hr->next_top_at_mark_start()) {
285 if (!_nextMarkBitMap->isMarked(addr)) {
286 par_mark(obj);
287 }
288 }
289 }
290
291 inline bool G1ConcurrentMark::do_yield_check() {
292 if (SuspendibleThreadSet::should_yield()) {
293 SuspendibleThreadSet::yield();
294 return true;
295 } else {
296 return false;
297 }
298 }
299
300 #endif // SHARE_VM_GC_G1_G1CONCURRENTMARK_INLINE_HPP