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