1 /*
2 * Copyright (c) 2001, 2016, 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.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
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/suspendibleThreadSet.hpp"
31 #include "gc/shared/taskqueue.inline.hpp"
32
33 inline bool G1ConcurrentMark::par_mark(oop obj) {
34 return _nextMarkBitMap->parMark((HeapWord*)obj);
35 }
36
37 inline bool G1CMBitMapRO::iterate(BitMapClosure* cl, MemRegion mr) {
38 HeapWord* start_addr = MAX2(startWord(), mr.start());
39 HeapWord* end_addr = MIN2(endWord(), mr.end());
40
41 if (end_addr > start_addr) {
42 // Right-open interval [start-offset, end-offset).
43 BitMap::idx_t start_offset = heapWordToOffset(start_addr);
44 BitMap::idx_t end_offset = heapWordToOffset(end_addr);
45
46 start_offset = _bm.get_next_one_offset(start_offset, end_offset);
47 while (start_offset < end_offset) {
48 if (!cl->do_bit(start_offset)) {
49 return false;
50 }
51 HeapWord* next_addr = MIN2(nextObject(offsetToHeapWord(start_offset)), end_addr);
52 BitMap::idx_t next_offset = heapWordToOffset(next_addr);
53 start_offset = _bm.get_next_one_offset(next_offset, end_offset);
54 }
55 }
56 return true;
57 }
58
59 // The argument addr should be the start address of a valid object
60 HeapWord* G1CMBitMapRO::nextObject(HeapWord* addr) {
61 oop obj = (oop) addr;
62 HeapWord* res = addr + obj->size();
63 assert(offsetToHeapWord(heapWordToOffset(res)) == res, "sanity");
64 return res;
65 }
66
67 #define check_mark(addr) \
68 assert(_bmStartWord <= (addr) && (addr) < (_bmStartWord + _bmWordSize), \
69 "outside underlying space?"); \
70 assert(G1CollectedHeap::heap()->is_in_exact(addr), \
71 "Trying to access not available bitmap " PTR_FORMAT \
72 " corresponding to " PTR_FORMAT " (%u)", \
73 p2i(this), p2i(addr), G1CollectedHeap::heap()->addr_to_region(addr));
74
75 inline void G1CMBitMap::mark(HeapWord* addr) {
76 check_mark(addr);
77 _bm.set_bit(heapWordToOffset(addr));
78 }
79
80 inline void G1CMBitMap::clear(HeapWord* addr) {
81 check_mark(addr);
82 _bm.clear_bit(heapWordToOffset(addr));
83 }
84
85 inline bool G1CMBitMap::parMark(HeapWord* addr) {
86 check_mark(addr);
87 return _bm.par_set_bit(heapWordToOffset(addr));
88 }
89
90 #undef check_mark
91
92 #ifndef PRODUCT
93 template<typename Fn>
94 inline void G1CMMarkStack::iterate(Fn fn) const {
95 assert_at_safepoint(true);
96
97 size_t num_chunks = 0;
98
99 OopChunk* cur = _chunk_list;
100 while (cur != NULL) {
101 guarantee(num_chunks <= _chunks_in_chunk_list, "Found " SIZE_FORMAT " oop chunks which is more than there should be", num_chunks);
102
103 for (size_t i = 0; i < OopsPerChunk; ++i) {
104 if (cur->data[i] == NULL) {
105 break;
106 }
107 fn(cur->data[i]);
108 }
109 cur = cur->next;
110 num_chunks++;
111 }
112 }
113 #endif
114
115 // It scans an object and visits its children.
116 inline void G1CMTask::scan_object(oop obj) { process_grey_object<true>(obj); }
117
118 inline void G1CMTask::push(oop obj) {
119 HeapWord* objAddr = (HeapWord*) obj;
120 assert(_g1h->is_in_g1_reserved(objAddr), "invariant");
121 assert(!_g1h->is_on_master_free_list(
122 _g1h->heap_region_containing((HeapWord*) objAddr)), "invariant");
123 assert(!_g1h->is_obj_ill(obj), "invariant");
124 assert(_nextMarkBitMap->isMarked(objAddr), "invariant");
125
126 if (!_task_queue->push(obj)) {
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(obj);
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(oop obj) {
171 assert(scan || obj->is_typeArray(), "Skipping scan of grey non-typeArray");
172 assert(_nextMarkBitMap->isMarked((HeapWord*) obj), "invariant");
173
174 size_t obj_size = obj->size();
175 _words_scanned += obj_size;
176
177 if (scan) {
178 obj->oop_iterate(_cm_oop_closure);
179 }
180 check_limits();
181 }
182
183 inline void G1CMTask::make_reference_grey(oop obj) {
184 if (_cm->par_mark(obj)) {
185 // No OrderAccess:store_load() is needed. It is implicit in the
186 // CAS done in G1CMBitMap::parMark() call in the routine above.
187 HeapWord* global_finger = _cm->finger();
188
189 // We only need to push a newly grey object on the mark
190 // stack if it is in a section of memory the mark bitmap
191 // scan has already examined. Mark bitmap scanning
192 // maintains progress "fingers" for determining that.
193 //
194 // Notice that the global finger might be moving forward
195 // concurrently. This is not a problem. In the worst case, we
196 // mark the object while it is above the global finger and, by
197 // the time we read the global finger, it has moved forward
198 // past this object. In this case, the object will probably
199 // be visited when a task is scanning the region and will also
200 // be pushed on the stack. So, some duplicate work, but no
201 // correctness problems.
202 if (is_below_finger(obj, global_finger)) {
203 if (obj->is_typeArray()) {
204 // Immediately process arrays of primitive types, rather
205 // than pushing on the mark stack. This keeps us from
206 // adding humongous objects to the mark stack that might
207 // be reclaimed before the entry is processed - see
208 // selection of candidates for eager reclaim of humongous
209 // objects. The cost of the additional type test is
210 // mitigated by avoiding a trip through the mark stack,
211 // by only doing a bookkeeping update and avoiding the
212 // actual scan of the object - a typeArray contains no
213 // references, and the metadata is built-in.
214 process_grey_object<false>(obj);
215 } else {
216 push(obj);
217 }
218 }
219 }
220 }
221
222 inline void G1CMTask::deal_with_reference(oop obj) {
223 increment_refs_reached();
224
225 HeapWord* objAddr = (HeapWord*) obj;
226 assert(obj->is_oop_or_null(true /* ignore mark word */), "Expected an oop or NULL at " PTR_FORMAT, p2i(obj));
227 if (_g1h->is_in_g1_reserved(objAddr)) {
228 assert(obj != NULL, "null check is implicit");
229 if (!_nextMarkBitMap->isMarked(objAddr)) {
230 // Only get the containing region if the object is not marked on the
231 // bitmap (otherwise, it's a waste of time since we won't do
232 // anything with it).
233 HeapRegion* hr = _g1h->heap_region_containing(obj);
234 if (!hr->obj_allocated_since_next_marking(obj)) {
235 make_reference_grey(obj);
236 }
237 }
238 }
239 }
240
241 inline void G1ConcurrentMark::markPrev(oop p) {
242 assert(!_prevMarkBitMap->isMarked((HeapWord*) p), "sanity");
243 // Note we are overriding the read-only view of the prev map here, via
244 // the cast.
245 ((G1CMBitMap*)_prevMarkBitMap)->mark((HeapWord*) p);
246 }
247
248 bool G1ConcurrentMark::isPrevMarked(oop p) const {
249 assert(p != NULL && p->is_oop(), "expected an oop");
250 HeapWord* addr = (HeapWord*)p;
251 assert(addr >= _prevMarkBitMap->startWord() ||
252 addr < _prevMarkBitMap->endWord(), "in a region");
253
254 return _prevMarkBitMap->isMarked(addr);
255 }
256
257 inline void G1ConcurrentMark::grayRoot(oop obj, HeapRegion* hr) {
258 assert(obj != NULL, "pre-condition");
259 HeapWord* addr = (HeapWord*) obj;
260 if (hr == NULL) {
261 hr = _g1h->heap_region_containing(addr);
262 } else {
263 assert(hr->is_in(addr), "pre-condition");
264 }
265 assert(hr != NULL, "sanity");
266 // Given that we're looking for a region that contains an object
267 // header it's impossible to get back a HC region.
268 assert(!hr->is_continues_humongous(), "sanity");
269
270 if (addr < hr->next_top_at_mark_start()) {
271 if (!_nextMarkBitMap->isMarked(addr)) {
272 par_mark(obj);
273 }
274 }
275 }
276
277 inline bool G1ConcurrentMark::do_yield_check() {
278 if (SuspendibleThreadSet::should_yield()) {
279 SuspendibleThreadSet::yield();
280 return true;
281 } else {
282 return false;
283 }
284 }
285
286 #endif // SHARE_VM_GC_G1_G1CONCURRENTMARK_INLINE_HPP