1 /*
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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24
25 #ifndef SHARE_VM_GC_G1_CONCURRENTMARK_INLINE_HPP
26 #define SHARE_VM_GC_G1_CONCURRENTMARK_INLINE_HPP
27
28 #include "gc/g1/concurrentMark.hpp"
29 #include "gc/g1/g1CollectedHeap.inline.hpp"
30 #include "gc/shared/taskqueue.inline.hpp"
31
32 // Utility routine to set an exclusive range of cards on the given
33 // card liveness bitmap
34 inline void ConcurrentMark::set_card_bitmap_range(BitMap* card_bm,
35 BitMap::idx_t start_idx,
36 BitMap::idx_t end_idx,
37 bool is_par) {
38
39 // Set the exclusive bit range [start_idx, end_idx).
40 assert((end_idx - start_idx) > 0, "at least one card");
41 assert(end_idx <= card_bm->size(), "sanity");
42
43 // Silently clip the end index
44 end_idx = MIN2(end_idx, card_bm->size());
45
46 // For small ranges use a simple loop; otherwise use set_range or
47 // use par_at_put_range (if parallel). The range is made up of the
48 // cards that are spanned by an object/mem region so 8 cards will
49 // allow up to object sizes up to 4K to be handled using the loop.
50 if ((end_idx - start_idx) <= 8) {
51 for (BitMap::idx_t i = start_idx; i < end_idx; i += 1) {
52 if (is_par) {
53 card_bm->par_set_bit(i);
54 } else {
55 card_bm->set_bit(i);
56 }
57 }
58 } else {
59 // Note BitMap::par_at_put_range() and BitMap::set_range() are exclusive.
60 if (is_par) {
61 card_bm->par_at_put_range(start_idx, end_idx, true);
62 } else {
63 card_bm->set_range(start_idx, end_idx);
64 }
65 }
66 }
67
68 // Returns the index in the liveness accounting card bitmap
69 // for the given address
70 inline BitMap::idx_t ConcurrentMark::card_bitmap_index_for(HeapWord* addr) {
71 // Below, the term "card num" means the result of shifting an address
72 // by the card shift -- address 0 corresponds to card number 0. One
73 // must subtract the card num of the bottom of the heap to obtain a
74 // card table index.
75 intptr_t card_num = intptr_t(uintptr_t(addr) >> CardTableModRefBS::card_shift);
76 return card_num - heap_bottom_card_num();
77 }
78
79 // Counts the given memory region in the given task/worker
80 // counting data structures.
81 inline void ConcurrentMark::count_region(MemRegion mr, HeapRegion* hr,
82 size_t* marked_bytes_array,
83 BitMap* task_card_bm) {
84 G1CollectedHeap* g1h = _g1h;
85 CardTableModRefBS* ct_bs = g1h->g1_barrier_set();
86
87 HeapWord* start = mr.start();
88 HeapWord* end = mr.end();
89 size_t region_size_bytes = mr.byte_size();
90 uint index = hr->hrm_index();
91
92 assert(!hr->is_continues_humongous(), "should not be HC region");
93 assert(hr == g1h->heap_region_containing(start), "sanity");
94 assert(hr == g1h->heap_region_containing(mr.last()), "sanity");
95 assert(marked_bytes_array != NULL, "pre-condition");
96 assert(task_card_bm != NULL, "pre-condition");
97
98 // Add to the task local marked bytes for this region.
99 marked_bytes_array[index] += region_size_bytes;
100
101 BitMap::idx_t start_idx = card_bitmap_index_for(start);
102 BitMap::idx_t end_idx = card_bitmap_index_for(end);
103
104 // Note: if we're looking at the last region in heap - end
105 // could be actually just beyond the end of the heap; end_idx
106 // will then correspond to a (non-existent) card that is also
107 // just beyond the heap.
108 if (g1h->is_in_g1_reserved(end) && !ct_bs->is_card_aligned(end)) {
109 // end of region is not card aligned - increment to cover
110 // all the cards spanned by the region.
111 end_idx += 1;
112 }
113 // The card bitmap is task/worker specific => no need to use
114 // the 'par' BitMap routines.
115 // Set bits in the exclusive bit range [start_idx, end_idx).
116 set_card_bitmap_range(task_card_bm, start_idx, end_idx, false /* is_par */);
117 }
118
119 // Counts the given memory region in the task/worker counting
120 // data structures for the given worker id.
121 inline void ConcurrentMark::count_region(MemRegion mr,
122 HeapRegion* hr,
123 uint worker_id) {
124 size_t* marked_bytes_array = count_marked_bytes_array_for(worker_id);
125 BitMap* task_card_bm = count_card_bitmap_for(worker_id);
126 count_region(mr, hr, marked_bytes_array, task_card_bm);
127 }
128
129 // Counts the given object in the given task/worker counting data structures.
130 inline void ConcurrentMark::count_object(oop obj,
131 HeapRegion* hr,
132 size_t* marked_bytes_array,
133 BitMap* task_card_bm) {
134 MemRegion mr((HeapWord*)obj, obj->size());
135 count_region(mr, hr, marked_bytes_array, task_card_bm);
136 }
137
138 // Attempts to mark the given object and, if successful, counts
139 // the object in the given task/worker counting structures.
140 inline bool ConcurrentMark::par_mark_and_count(oop obj,
141 HeapRegion* hr,
142 size_t* marked_bytes_array,
143 BitMap* task_card_bm) {
144 HeapWord* addr = (HeapWord*)obj;
145 if (_nextMarkBitMap->parMark(addr)) {
146 // Update the task specific count data for the object.
147 count_object(obj, hr, marked_bytes_array, task_card_bm);
148 return true;
149 }
150 return false;
151 }
152
153 // Attempts to mark the given object and, if successful, counts
154 // the object in the task/worker counting structures for the
155 // given worker id.
156 inline bool ConcurrentMark::par_mark_and_count(oop obj,
157 size_t word_size,
158 HeapRegion* hr,
159 uint worker_id) {
160 HeapWord* addr = (HeapWord*)obj;
161 if (_nextMarkBitMap->parMark(addr)) {
162 MemRegion mr(addr, word_size);
163 count_region(mr, hr, worker_id);
164 return true;
165 }
166 return false;
167 }
168
169 inline bool CMBitMapRO::iterate(BitMapClosure* cl, MemRegion mr) {
170 HeapWord* start_addr = MAX2(startWord(), mr.start());
171 HeapWord* end_addr = MIN2(endWord(), mr.end());
172
173 if (end_addr > start_addr) {
174 // Right-open interval [start-offset, end-offset).
175 BitMap::idx_t start_offset = heapWordToOffset(start_addr);
176 BitMap::idx_t end_offset = heapWordToOffset(end_addr);
177
178 start_offset = _bm.get_next_one_offset(start_offset, end_offset);
179 while (start_offset < end_offset) {
180 if (!cl->do_bit(start_offset)) {
181 return false;
182 }
183 HeapWord* next_addr = MIN2(nextObject(offsetToHeapWord(start_offset)), end_addr);
184 BitMap::idx_t next_offset = heapWordToOffset(next_addr);
185 start_offset = _bm.get_next_one_offset(next_offset, end_offset);
186 }
187 }
188 return true;
189 }
190
191 inline bool CMBitMapRO::iterate(BitMapClosure* cl) {
192 MemRegion mr(startWord(), sizeInWords());
193 return iterate(cl, mr);
194 }
195
196 #define check_mark(addr) \
197 assert(_bmStartWord <= (addr) && (addr) < (_bmStartWord + _bmWordSize), \
198 "outside underlying space?"); \
199 assert(G1CollectedHeap::heap()->is_in_exact(addr), \
200 "Trying to access not available bitmap " PTR_FORMAT \
201 " corresponding to " PTR_FORMAT " (%u)", \
202 p2i(this), p2i(addr), G1CollectedHeap::heap()->addr_to_region(addr));
203
204 inline void CMBitMap::mark(HeapWord* addr) {
205 check_mark(addr);
206 _bm.set_bit(heapWordToOffset(addr));
207 }
208
209 inline void CMBitMap::clear(HeapWord* addr) {
210 check_mark(addr);
211 _bm.clear_bit(heapWordToOffset(addr));
212 }
213
214 inline bool CMBitMap::parMark(HeapWord* addr) {
215 check_mark(addr);
216 return _bm.par_set_bit(heapWordToOffset(addr));
217 }
218
219 inline bool CMBitMap::parClear(HeapWord* addr) {
220 check_mark(addr);
221 return _bm.par_clear_bit(heapWordToOffset(addr));
222 }
223
224 #undef check_mark
225
226 template<typename Fn>
227 inline void CMMarkStack::iterate(Fn fn) {
228 assert(_saved_index == _index, "saved index: %d index: %d", _saved_index, _index);
229 for (int i = 0; i < _index; ++i) {
230 fn(_base[i]);
231 }
232 }
233
234 // It scans an object and visits its children.
235 inline void CMTask::scan_object(oop obj) { process_grey_object<true>(obj); }
236
237 inline void CMTask::push(oop obj) {
238 HeapWord* objAddr = (HeapWord*) obj;
239 assert(_g1h->is_in_g1_reserved(objAddr), "invariant");
240 assert(!_g1h->is_on_master_free_list(
241 _g1h->heap_region_containing((HeapWord*) objAddr)), "invariant");
242 assert(!_g1h->is_obj_ill(obj), "invariant");
243 assert(_nextMarkBitMap->isMarked(objAddr), "invariant");
244
245 if (_cm->verbose_high()) {
246 gclog_or_tty->print_cr("[%u] pushing " PTR_FORMAT, _worker_id, p2i((void*) obj));
247 }
248
249 if (!_task_queue->push(obj)) {
250 // The local task queue looks full. We need to push some entries
251 // to the global stack.
252
253 if (_cm->verbose_medium()) {
254 gclog_or_tty->print_cr("[%u] task queue overflow, "
255 "moving entries to the global stack",
256 _worker_id);
257 }
258 move_entries_to_global_stack();
259
260 // this should succeed since, even if we overflow the global
261 // stack, we should have definitely removed some entries from the
262 // local queue. So, there must be space on it.
263 bool success = _task_queue->push(obj);
264 assert(success, "invariant");
265 }
266
267 statsOnly( size_t tmp_size = (size_t)_task_queue->size();
268 if (tmp_size > _local_max_size) {
269 _local_max_size = tmp_size;
270 }
271 ++_local_pushes );
272 }
273
274 inline bool CMTask::is_below_finger(oop obj, HeapWord* global_finger) const {
275 // If obj is above the global finger, then the mark bitmap scan
276 // will find it later, and no push is needed. Similarly, if we have
277 // a current region and obj is between the local finger and the
278 // end of the current region, then no push is needed. The tradeoff
279 // of checking both vs only checking the global finger is that the
280 // local check will be more accurate and so result in fewer pushes,
281 // but may also be a little slower.
282 HeapWord* objAddr = (HeapWord*)obj;
283 if (_finger != NULL) {
284 // We have a current region.
285
286 // Finger and region values are all NULL or all non-NULL. We
287 // use _finger to check since we immediately use its value.
288 assert(_curr_region != NULL, "invariant");
289 assert(_region_limit != NULL, "invariant");
290 assert(_region_limit <= global_finger, "invariant");
291
292 // True if obj is less than the local finger, or is between
293 // the region limit and the global finger.
294 if (objAddr < _finger) {
295 return true;
296 } else if (objAddr < _region_limit) {
297 return false;
298 } // Else check global finger.
299 }
300 // Check global finger.
301 return objAddr < global_finger;
302 }
303
304 template<bool scan>
305 inline void CMTask::process_grey_object(oop obj) {
306 assert(scan || obj->is_typeArray(), "Skipping scan of grey non-typeArray");
307 assert(_nextMarkBitMap->isMarked((HeapWord*) obj), "invariant");
308
309 if (_cm->verbose_high()) {
310 gclog_or_tty->print_cr("[%u] processing grey object " PTR_FORMAT,
311 _worker_id, p2i((void*) obj));
312 }
313
314 size_t obj_size = obj->size();
315 _words_scanned += obj_size;
316
317 if (scan) {
318 obj->oop_iterate(_cm_oop_closure);
319 }
320 statsOnly( ++_objs_scanned );
321 check_limits();
322 }
323
324
325
326 inline void CMTask::make_reference_grey(oop obj, HeapRegion* hr) {
327 if (_cm->par_mark_and_count(obj, hr, _marked_bytes_array, _card_bm)) {
328
329 if (_cm->verbose_high()) {
330 gclog_or_tty->print_cr("[%u] marked object " PTR_FORMAT,
331 _worker_id, p2i(obj));
332 }
333
334 // No OrderAccess:store_load() is needed. It is implicit in the
335 // CAS done in CMBitMap::parMark() call in the routine above.
336 HeapWord* global_finger = _cm->finger();
337
338 // We only need to push a newly grey object on the mark
339 // stack if it is in a section of memory the mark bitmap
340 // scan has already examined. Mark bitmap scanning
341 // maintains progress "fingers" for determining that.
342 //
343 // Notice that the global finger might be moving forward
344 // concurrently. This is not a problem. In the worst case, we
345 // mark the object while it is above the global finger and, by
346 // the time we read the global finger, it has moved forward
347 // past this object. In this case, the object will probably
348 // be visited when a task is scanning the region and will also
349 // be pushed on the stack. So, some duplicate work, but no
350 // correctness problems.
351 if (is_below_finger(obj, global_finger)) {
352 if (obj->is_typeArray()) {
353 // Immediately process arrays of primitive types, rather
354 // than pushing on the mark stack. This keeps us from
355 // adding humongous objects to the mark stack that might
356 // be reclaimed before the entry is processed - see
357 // selection of candidates for eager reclaim of humongous
358 // objects. The cost of the additional type test is
359 // mitigated by avoiding a trip through the mark stack,
360 // by only doing a bookkeeping update and avoiding the
361 // actual scan of the object - a typeArray contains no
362 // references, and the metadata is built-in.
363 process_grey_object<false>(obj);
364 } else {
365 if (_cm->verbose_high()) {
366 gclog_or_tty->print_cr("[%u] below a finger (local: " PTR_FORMAT
367 ", global: " PTR_FORMAT ") pushing "
368 PTR_FORMAT " on mark stack",
369 _worker_id, p2i(_finger),
370 p2i(global_finger), p2i(obj));
371 }
372 push(obj);
373 }
374 }
375 }
376 }
377
378 inline void CMTask::deal_with_reference(oop obj) {
379 if (_cm->verbose_high()) {
380 gclog_or_tty->print_cr("[%u] we're dealing with reference = " PTR_FORMAT,
381 _worker_id, p2i((void*) obj));
382 }
383
384 increment_refs_reached();
385
386 HeapWord* objAddr = (HeapWord*) obj;
387 assert(obj->is_oop_or_null(true /* ignore mark word */), "Expected an oop or NULL at " PTR_FORMAT, p2i(obj));
388 if (_g1h->is_in_g1_reserved(objAddr)) {
389 assert(obj != NULL, "null check is implicit");
390 if (!_nextMarkBitMap->isMarked(objAddr)) {
391 // Only get the containing region if the object is not marked on the
392 // bitmap (otherwise, it's a waste of time since we won't do
393 // anything with it).
394 HeapRegion* hr = _g1h->heap_region_containing_raw(obj);
395 if (!hr->obj_allocated_since_next_marking(obj)) {
396 make_reference_grey(obj, hr);
397 }
398 }
399 }
400 }
401
402 inline void ConcurrentMark::markPrev(oop p) {
403 assert(!_prevMarkBitMap->isMarked((HeapWord*) p), "sanity");
404 // Note we are overriding the read-only view of the prev map here, via
405 // the cast.
406 ((CMBitMap*)_prevMarkBitMap)->mark((HeapWord*) p);
407 }
408
409 inline void ConcurrentMark::grayRoot(oop obj, size_t word_size,
410 uint worker_id, HeapRegion* hr) {
411 assert(obj != NULL, "pre-condition");
412 HeapWord* addr = (HeapWord*) obj;
413 if (hr == NULL) {
414 hr = _g1h->heap_region_containing_raw(addr);
415 } else {
416 assert(hr->is_in(addr), "pre-condition");
417 }
418 assert(hr != NULL, "sanity");
419 // Given that we're looking for a region that contains an object
420 // header it's impossible to get back a HC region.
421 assert(!hr->is_continues_humongous(), "sanity");
422
423 // We cannot assert that word_size == obj->size() given that obj
424 // might not be in a consistent state (another thread might be in
425 // the process of copying it). So the best thing we can do is to
426 // assert that word_size is under an upper bound which is its
427 // containing region's capacity.
428 assert(word_size * HeapWordSize <= hr->capacity(),
429 "size: " SIZE_FORMAT " capacity: " SIZE_FORMAT " " HR_FORMAT,
430 word_size * HeapWordSize, hr->capacity(),
431 HR_FORMAT_PARAMS(hr));
432
433 if (addr < hr->next_top_at_mark_start()) {
434 if (!_nextMarkBitMap->isMarked(addr)) {
435 par_mark_and_count(obj, word_size, hr, worker_id);
436 }
437 }
438 }
439
440 #endif // SHARE_VM_GC_G1_CONCURRENTMARK_INLINE_HPP