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