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