1 /*
2 * Copyright (c) 2001, 2014, 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 #include "precompiled.hpp"
26 #include "gc_implementation/g1/concurrentG1Refine.hpp"
27 #include "gc_implementation/g1/g1BlockOffsetTable.inline.hpp"
28 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
29 #include "gc_implementation/g1/heapRegionRemSet.hpp"
30 #include "gc_implementation/g1/heapRegionManager.inline.hpp"
31 #include "memory/allocation.hpp"
32 #include "memory/padded.inline.hpp"
33 #include "memory/space.inline.hpp"
34 #include "oops/oop.inline.hpp"
35 #include "runtime/atomic.inline.hpp"
36 #include "utilities/bitMap.inline.hpp"
37 #include "utilities/globalDefinitions.hpp"
38 #include "utilities/growableArray.hpp"
39
40 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
41
42 class PerRegionTable: public CHeapObj<mtGC> {
43 friend class OtherRegionsTable;
44 friend class HeapRegionRemSetIterator;
45
46 HeapRegion* _hr;
47 BitMap _bm;
48 jint _occupied;
49
50 // next pointer for free/allocated 'all' list
51 PerRegionTable* _next;
52
53 // prev pointer for the allocated 'all' list
54 PerRegionTable* _prev;
55
56 // next pointer in collision list
57 PerRegionTable * _collision_list_next;
58
59 // Global free list of PRTs
60 static PerRegionTable* _free_list;
61
62 protected:
63 // We need access in order to union things into the base table.
64 BitMap* bm() { return &_bm; }
65
66 void recount_occupied() {
67 _occupied = (jint) bm()->count_one_bits();
68 }
69
70 PerRegionTable(HeapRegion* hr) :
71 _hr(hr),
72 _occupied(0),
73 _bm(HeapRegion::CardsPerRegion, false /* in-resource-area */),
74 _collision_list_next(NULL), _next(NULL), _prev(NULL)
75 {}
76
77 void add_card_work(CardIdx_t from_card, bool par) {
78 if (!_bm.at(from_card)) {
79 if (par) {
80 if (_bm.par_at_put(from_card, 1)) {
81 Atomic::inc(&_occupied);
82 }
83 } else {
84 _bm.at_put(from_card, 1);
85 _occupied++;
86 }
87 }
88 }
89
90 void add_reference_work(OopOrNarrowOopStar from, bool par) {
91 // Must make this robust in case "from" is not in "_hr", because of
92 // concurrency.
93
94 if (G1TraceHeapRegionRememberedSet) {
95 gclog_or_tty->print_cr(" PRT::Add_reference_work(" PTR_FORMAT "->" PTR_FORMAT").",
96 from,
97 UseCompressedOops
98 ? (void *)oopDesc::load_decode_heap_oop((narrowOop*)from)
99 : (void *)oopDesc::load_decode_heap_oop((oop*)from));
100 }
101
102 HeapRegion* loc_hr = hr();
103 // If the test below fails, then this table was reused concurrently
104 // with this operation. This is OK, since the old table was coarsened,
105 // and adding a bit to the new table is never incorrect.
106 // If the table used to belong to a continues humongous region and is
107 // now reused for the corresponding start humongous region, we need to
108 // make sure that we detect this. Thus, we call is_in_reserved_raw()
109 // instead of just is_in_reserved() here.
110 if (loc_hr->is_in_reserved_raw(from)) {
111 size_t hw_offset = pointer_delta((HeapWord*)from, loc_hr->bottom());
112 CardIdx_t from_card = (CardIdx_t)
113 hw_offset >> (CardTableModRefBS::card_shift - LogHeapWordSize);
114
115 assert(0 <= from_card && (size_t)from_card < HeapRegion::CardsPerRegion,
116 "Must be in range.");
117 add_card_work(from_card, par);
118 }
119 }
120
121 public:
122
123 HeapRegion* hr() const { return _hr; }
124
125 jint occupied() const {
126 // Overkill, but if we ever need it...
127 // guarantee(_occupied == _bm.count_one_bits(), "Check");
128 return _occupied;
129 }
130
131 void init(HeapRegion* hr, bool clear_links_to_all_list) {
132 if (clear_links_to_all_list) {
133 set_next(NULL);
134 set_prev(NULL);
135 }
136 _hr = hr;
137 _collision_list_next = NULL;
138 _occupied = 0;
139 _bm.clear();
140 }
141
142 void add_reference(OopOrNarrowOopStar from) {
143 add_reference_work(from, /*parallel*/ true);
144 }
145
146 void seq_add_reference(OopOrNarrowOopStar from) {
147 add_reference_work(from, /*parallel*/ false);
148 }
149
150 void scrub(CardTableModRefBS* ctbs, BitMap* card_bm) {
151 HeapWord* hr_bot = hr()->bottom();
152 size_t hr_first_card_index = ctbs->index_for(hr_bot);
153 bm()->set_intersection_at_offset(*card_bm, hr_first_card_index);
154 recount_occupied();
155 }
156
157 void add_card(CardIdx_t from_card_index) {
158 add_card_work(from_card_index, /*parallel*/ true);
159 }
160
161 void seq_add_card(CardIdx_t from_card_index) {
162 add_card_work(from_card_index, /*parallel*/ false);
163 }
164
165 // (Destructively) union the bitmap of the current table into the given
166 // bitmap (which is assumed to be of the same size.)
167 void union_bitmap_into(BitMap* bm) {
168 bm->set_union(_bm);
169 }
170
171 // Mem size in bytes.
172 size_t mem_size() const {
173 return sizeof(PerRegionTable) + _bm.size_in_words() * HeapWordSize;
174 }
175
176 // Requires "from" to be in "hr()".
177 bool contains_reference(OopOrNarrowOopStar from) const {
178 assert(hr()->is_in_reserved(from), "Precondition.");
179 size_t card_ind = pointer_delta(from, hr()->bottom(),
180 CardTableModRefBS::card_size);
181 return _bm.at(card_ind);
182 }
183
184 // Bulk-free the PRTs from prt to last, assumes that they are
185 // linked together using their _next field.
186 static void bulk_free(PerRegionTable* prt, PerRegionTable* last) {
187 while (true) {
188 PerRegionTable* fl = _free_list;
189 last->set_next(fl);
190 PerRegionTable* res = (PerRegionTable*) Atomic::cmpxchg_ptr(prt, &_free_list, fl);
191 if (res == fl) {
192 return;
193 }
194 }
195 ShouldNotReachHere();
196 }
197
198 static void free(PerRegionTable* prt) {
199 bulk_free(prt, prt);
200 }
201
202 // Returns an initialized PerRegionTable instance.
203 static PerRegionTable* alloc(HeapRegion* hr) {
204 PerRegionTable* fl = _free_list;
205 while (fl != NULL) {
206 PerRegionTable* nxt = fl->next();
207 PerRegionTable* res =
208 (PerRegionTable*)
209 Atomic::cmpxchg_ptr(nxt, &_free_list, fl);
210 if (res == fl) {
211 fl->init(hr, true);
212 return fl;
213 } else {
214 fl = _free_list;
215 }
216 }
217 assert(fl == NULL, "Loop condition.");
218 return new PerRegionTable(hr);
219 }
220
221 PerRegionTable* next() const { return _next; }
222 void set_next(PerRegionTable* next) { _next = next; }
223 PerRegionTable* prev() const { return _prev; }
224 void set_prev(PerRegionTable* prev) { _prev = prev; }
225
226 // Accessor and Modification routines for the pointer for the
227 // singly linked collision list that links the PRTs within the
228 // OtherRegionsTable::_fine_grain_regions hash table.
229 //
230 // It might be useful to also make the collision list doubly linked
231 // to avoid iteration over the collisions list during scrubbing/deletion.
232 // OTOH there might not be many collisions.
233
234 PerRegionTable* collision_list_next() const {
235 return _collision_list_next;
236 }
237
238 void set_collision_list_next(PerRegionTable* next) {
239 _collision_list_next = next;
240 }
241
242 PerRegionTable** collision_list_next_addr() {
243 return &_collision_list_next;
244 }
245
246 static size_t fl_mem_size() {
247 PerRegionTable* cur = _free_list;
248 size_t res = 0;
249 while (cur != NULL) {
250 res += cur->mem_size();
251 cur = cur->next();
252 }
253 return res;
254 }
255
256 static void test_fl_mem_size();
257 };
258
259 PerRegionTable* PerRegionTable::_free_list = NULL;
260
261 size_t OtherRegionsTable::_max_fine_entries = 0;
262 size_t OtherRegionsTable::_mod_max_fine_entries_mask = 0;
263 size_t OtherRegionsTable::_fine_eviction_stride = 0;
264 size_t OtherRegionsTable::_fine_eviction_sample_size = 0;
265
266 OtherRegionsTable::OtherRegionsTable(HeapRegion* hr, Mutex* m) :
267 _g1h(G1CollectedHeap::heap()),
268 _hr(hr), _m(m),
269 _coarse_map(G1CollectedHeap::heap()->max_regions(),
270 false /* in-resource-area */),
271 _fine_grain_regions(NULL),
272 _first_all_fine_prts(NULL), _last_all_fine_prts(NULL),
273 _n_fine_entries(0), _n_coarse_entries(0),
274 _fine_eviction_start(0),
275 _sparse_table(hr)
276 {
277 typedef PerRegionTable* PerRegionTablePtr;
278
279 if (_max_fine_entries == 0) {
280 assert(_mod_max_fine_entries_mask == 0, "Both or none.");
281 size_t max_entries_log = (size_t)log2_long((jlong)G1RSetRegionEntries);
282 _max_fine_entries = (size_t)1 << max_entries_log;
283 _mod_max_fine_entries_mask = _max_fine_entries - 1;
284
285 assert(_fine_eviction_sample_size == 0
286 && _fine_eviction_stride == 0, "All init at same time.");
287 _fine_eviction_sample_size = MAX2((size_t)4, max_entries_log);
288 _fine_eviction_stride = _max_fine_entries / _fine_eviction_sample_size;
289 }
290
291 _fine_grain_regions = NEW_C_HEAP_ARRAY3(PerRegionTablePtr, _max_fine_entries,
292 mtGC, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
293
294 if (_fine_grain_regions == NULL) {
295 vm_exit_out_of_memory(sizeof(void*)*_max_fine_entries, OOM_MALLOC_ERROR,
296 "Failed to allocate _fine_grain_entries.");
297 }
298
299 for (size_t i = 0; i < _max_fine_entries; i++) {
300 _fine_grain_regions[i] = NULL;
301 }
302 }
303
304 void OtherRegionsTable::link_to_all(PerRegionTable* prt) {
305 // We always append to the beginning of the list for convenience;
306 // the order of entries in this list does not matter.
307 if (_first_all_fine_prts != NULL) {
308 assert(_first_all_fine_prts->prev() == NULL, "invariant");
309 _first_all_fine_prts->set_prev(prt);
310 prt->set_next(_first_all_fine_prts);
311 } else {
312 // this is the first element we insert. Adjust the "last" pointer
313 _last_all_fine_prts = prt;
314 assert(prt->next() == NULL, "just checking");
315 }
316 // the new element is always the first element without a predecessor
317 prt->set_prev(NULL);
318 _first_all_fine_prts = prt;
319
320 assert(prt->prev() == NULL, "just checking");
321 assert(_first_all_fine_prts == prt, "just checking");
322 assert((_first_all_fine_prts == NULL && _last_all_fine_prts == NULL) ||
323 (_first_all_fine_prts != NULL && _last_all_fine_prts != NULL),
324 "just checking");
325 assert(_last_all_fine_prts == NULL || _last_all_fine_prts->next() == NULL,
326 "just checking");
327 assert(_first_all_fine_prts == NULL || _first_all_fine_prts->prev() == NULL,
328 "just checking");
329 }
330
331 void OtherRegionsTable::unlink_from_all(PerRegionTable* prt) {
332 if (prt->prev() != NULL) {
333 assert(_first_all_fine_prts != prt, "just checking");
334 prt->prev()->set_next(prt->next());
335 // removing the last element in the list?
336 if (_last_all_fine_prts == prt) {
337 _last_all_fine_prts = prt->prev();
338 }
339 } else {
340 assert(_first_all_fine_prts == prt, "just checking");
341 _first_all_fine_prts = prt->next();
342 // list is empty now?
343 if (_first_all_fine_prts == NULL) {
344 _last_all_fine_prts = NULL;
345 }
346 }
347
348 if (prt->next() != NULL) {
349 prt->next()->set_prev(prt->prev());
350 }
351
352 prt->set_next(NULL);
353 prt->set_prev(NULL);
354
355 assert((_first_all_fine_prts == NULL && _last_all_fine_prts == NULL) ||
356 (_first_all_fine_prts != NULL && _last_all_fine_prts != NULL),
357 "just checking");
358 assert(_last_all_fine_prts == NULL || _last_all_fine_prts->next() == NULL,
359 "just checking");
360 assert(_first_all_fine_prts == NULL || _first_all_fine_prts->prev() == NULL,
361 "just checking");
362 }
363
364 int** FromCardCache::_cache = NULL;
365 uint FromCardCache::_max_regions = 0;
366 size_t FromCardCache::_static_mem_size = 0;
367
368 void FromCardCache::initialize(uint n_par_rs, uint max_num_regions) {
369 guarantee(_cache == NULL, "Should not call this multiple times");
370
371 _max_regions = max_num_regions;
372 _cache = Padded2DArray<int, mtGC>::create_unfreeable(n_par_rs,
373 _max_regions,
374 &_static_mem_size);
375
376 invalidate(0, _max_regions);
377 }
378
379 void FromCardCache::invalidate(uint start_idx, size_t new_num_regions) {
380 guarantee((size_t)start_idx + new_num_regions <= max_uintx,
381 err_msg("Trying to invalidate beyond maximum region, from %u size "SIZE_FORMAT,
382 start_idx, new_num_regions));
383 for (uint i = 0; i < HeapRegionRemSet::num_par_rem_sets(); i++) {
384 uint end_idx = (start_idx + (uint)new_num_regions);
385 assert(end_idx <= _max_regions, "Must be within max.");
386 for (uint j = start_idx; j < end_idx; j++) {
387 set(i, j, InvalidCard);
388 }
389 }
390 }
391
392 #ifndef PRODUCT
393 void FromCardCache::print(outputStream* out) {
394 for (uint i = 0; i < HeapRegionRemSet::num_par_rem_sets(); i++) {
395 for (uint j = 0; j < _max_regions; j++) {
396 out->print_cr("_from_card_cache[%u][%u] = %d.",
397 i, j, at(i, j));
398 }
399 }
400 }
401 #endif
402
403 void FromCardCache::clear(uint region_idx) {
404 uint num_par_remsets = HeapRegionRemSet::num_par_rem_sets();
405 for (uint i = 0; i < num_par_remsets; i++) {
406 set(i, region_idx, InvalidCard);
407 }
408 }
409
410 void OtherRegionsTable::add_reference(OopOrNarrowOopStar from, uint tid) {
411 uint cur_hrm_ind = _hr->hrm_index();
412
413 if (G1TraceHeapRegionRememberedSet) {
414 gclog_or_tty->print_cr("ORT::add_reference_work(" PTR_FORMAT "->" PTR_FORMAT ").",
415 from,
416 UseCompressedOops
417 ? (void *)oopDesc::load_decode_heap_oop((narrowOop*)from)
418 : (void *)oopDesc::load_decode_heap_oop((oop*)from));
419 }
420
421 int from_card = (int)(uintptr_t(from) >> CardTableModRefBS::card_shift);
422
423 if (G1TraceHeapRegionRememberedSet) {
424 gclog_or_tty->print_cr("Table for [" PTR_FORMAT "...): card %d (cache = %d)",
425 _hr->bottom(), from_card,
426 FromCardCache::at(tid, cur_hrm_ind));
427 }
428
429 if (FromCardCache::contains_or_replace(tid, cur_hrm_ind, from_card)) {
430 if (G1TraceHeapRegionRememberedSet) {
431 gclog_or_tty->print_cr(" from-card cache hit.");
432 }
433 assert(contains_reference(from), "We just added it!");
434 return;
435 }
436
437 // Note that this may be a continued H region.
438 HeapRegion* from_hr = _g1h->heap_region_containing_raw(from);
439 RegionIdx_t from_hrm_ind = (RegionIdx_t) from_hr->hrm_index();
440
441 // If the region is already coarsened, return.
442 if (_coarse_map.at(from_hrm_ind)) {
443 if (G1TraceHeapRegionRememberedSet) {
444 gclog_or_tty->print_cr(" coarse map hit.");
445 }
446 assert(contains_reference(from), "We just added it!");
447 return;
448 }
449
450 // Otherwise find a per-region table to add it to.
451 size_t ind = from_hrm_ind & _mod_max_fine_entries_mask;
452 PerRegionTable* prt = find_region_table(ind, from_hr);
453 if (prt == NULL) {
454 MutexLockerEx x(_m, Mutex::_no_safepoint_check_flag);
455 // Confirm that it's really not there...
456 prt = find_region_table(ind, from_hr);
457 if (prt == NULL) {
458
459 uintptr_t from_hr_bot_card_index =
460 uintptr_t(from_hr->bottom())
461 >> CardTableModRefBS::card_shift;
462 CardIdx_t card_index = from_card - from_hr_bot_card_index;
463 assert(0 <= card_index && (size_t)card_index < HeapRegion::CardsPerRegion,
464 "Must be in range.");
465 if (G1HRRSUseSparseTable &&
466 _sparse_table.add_card(from_hrm_ind, card_index)) {
467 if (G1RecordHRRSOops) {
468 HeapRegionRemSet::record(_hr, from);
469 if (G1TraceHeapRegionRememberedSet) {
470 gclog_or_tty->print(" Added card " PTR_FORMAT " to region "
471 "[" PTR_FORMAT "...) for ref " PTR_FORMAT ".\n",
472 align_size_down(uintptr_t(from),
473 CardTableModRefBS::card_size),
474 _hr->bottom(), from);
475 }
476 }
477 if (G1TraceHeapRegionRememberedSet) {
478 gclog_or_tty->print_cr(" added card to sparse table.");
479 }
480 assert(contains_reference_locked(from), "We just added it!");
481 return;
482 } else {
483 if (G1TraceHeapRegionRememberedSet) {
484 gclog_or_tty->print_cr(" [tid %u] sparse table entry "
485 "overflow(f: %d, t: %u)",
486 tid, from_hrm_ind, cur_hrm_ind);
487 }
488 }
489
490 if (_n_fine_entries == _max_fine_entries) {
491 prt = delete_region_table();
492 // There is no need to clear the links to the 'all' list here:
493 // prt will be reused immediately, i.e. remain in the 'all' list.
494 prt->init(from_hr, false /* clear_links_to_all_list */);
495 } else {
496 prt = PerRegionTable::alloc(from_hr);
497 link_to_all(prt);
498 }
499
500 PerRegionTable* first_prt = _fine_grain_regions[ind];
501 prt->set_collision_list_next(first_prt);
502 _fine_grain_regions[ind] = prt;
503 _n_fine_entries++;
504
505 if (G1HRRSUseSparseTable) {
506 // Transfer from sparse to fine-grain.
507 SparsePRTEntry *sprt_entry = _sparse_table.get_entry(from_hrm_ind);
508 assert(sprt_entry != NULL, "There should have been an entry");
509 for (int i = 0; i < SparsePRTEntry::cards_num(); i++) {
510 CardIdx_t c = sprt_entry->card(i);
511 if (c != SparsePRTEntry::NullEntry) {
512 prt->add_card(c);
513 }
514 }
515 // Now we can delete the sparse entry.
516 bool res = _sparse_table.delete_entry(from_hrm_ind);
517 assert(res, "It should have been there.");
518 }
519 }
520 assert(prt != NULL && prt->hr() == from_hr, "consequence");
521 }
522 // Note that we can't assert "prt->hr() == from_hr", because of the
523 // possibility of concurrent reuse. But see head comment of
524 // OtherRegionsTable for why this is OK.
525 assert(prt != NULL, "Inv");
526
527 prt->add_reference(from);
528
529 if (G1RecordHRRSOops) {
530 HeapRegionRemSet::record(_hr, from);
531 if (G1TraceHeapRegionRememberedSet) {
532 gclog_or_tty->print("Added card " PTR_FORMAT " to region "
533 "[" PTR_FORMAT "...) for ref " PTR_FORMAT ".\n",
534 align_size_down(uintptr_t(from),
535 CardTableModRefBS::card_size),
536 _hr->bottom(), from);
537 }
538 }
539 assert(contains_reference(from), "We just added it!");
540 }
541
542 PerRegionTable*
543 OtherRegionsTable::find_region_table(size_t ind, HeapRegion* hr) const {
544 assert(0 <= ind && ind < _max_fine_entries, "Preconditions.");
545 PerRegionTable* prt = _fine_grain_regions[ind];
546 while (prt != NULL && prt->hr() != hr) {
547 prt = prt->collision_list_next();
548 }
549 // Loop postcondition is the method postcondition.
550 return prt;
551 }
552
553 jint OtherRegionsTable::_n_coarsenings = 0;
554
555 PerRegionTable* OtherRegionsTable::delete_region_table() {
556 assert(_m->owned_by_self(), "Precondition");
557 assert(_n_fine_entries == _max_fine_entries, "Precondition");
558 PerRegionTable* max = NULL;
559 jint max_occ = 0;
560 PerRegionTable** max_prev;
561 size_t max_ind;
562
563 size_t i = _fine_eviction_start;
564 for (size_t k = 0; k < _fine_eviction_sample_size; k++) {
565 size_t ii = i;
566 // Make sure we get a non-NULL sample.
567 while (_fine_grain_regions[ii] == NULL) {
568 ii++;
569 if (ii == _max_fine_entries) ii = 0;
570 guarantee(ii != i, "We must find one.");
571 }
572 PerRegionTable** prev = &_fine_grain_regions[ii];
573 PerRegionTable* cur = *prev;
574 while (cur != NULL) {
575 jint cur_occ = cur->occupied();
576 if (max == NULL || cur_occ > max_occ) {
577 max = cur;
578 max_prev = prev;
579 max_ind = i;
580 max_occ = cur_occ;
581 }
582 prev = cur->collision_list_next_addr();
583 cur = cur->collision_list_next();
584 }
585 i = i + _fine_eviction_stride;
586 if (i >= _n_fine_entries) i = i - _n_fine_entries;
587 }
588
589 _fine_eviction_start++;
590
591 if (_fine_eviction_start >= _n_fine_entries) {
592 _fine_eviction_start -= _n_fine_entries;
593 }
594
595 guarantee(max != NULL, "Since _n_fine_entries > 0");
596
597 // Set the corresponding coarse bit.
598 size_t max_hrm_index = (size_t) max->hr()->hrm_index();
599 if (!_coarse_map.at(max_hrm_index)) {
600 _coarse_map.at_put(max_hrm_index, true);
601 _n_coarse_entries++;
602 if (G1TraceHeapRegionRememberedSet) {
603 gclog_or_tty->print("Coarsened entry in region [" PTR_FORMAT "...] "
604 "for region [" PTR_FORMAT "...] (" SIZE_FORMAT " coarse entries).\n",
605 _hr->bottom(),
606 max->hr()->bottom(),
607 _n_coarse_entries);
608 }
609 }
610
611 // Unsplice.
612 *max_prev = max->collision_list_next();
613 Atomic::inc(&_n_coarsenings);
614 _n_fine_entries--;
615 return max;
616 }
617
618 void OtherRegionsTable::scrub(CardTableModRefBS* ctbs,
619 BitMap* region_bm, BitMap* card_bm) {
620 // First eliminated garbage regions from the coarse map.
621 if (G1RSScrubVerbose) {
622 gclog_or_tty->print_cr("Scrubbing region %u:", _hr->hrm_index());
623 }
624
625 assert(_coarse_map.size() == region_bm->size(), "Precondition");
626 if (G1RSScrubVerbose) {
627 gclog_or_tty->print(" Coarse map: before = "SIZE_FORMAT"...",
628 _n_coarse_entries);
629 }
630 _coarse_map.set_intersection(*region_bm);
631 _n_coarse_entries = _coarse_map.count_one_bits();
632 if (G1RSScrubVerbose) {
633 gclog_or_tty->print_cr(" after = "SIZE_FORMAT".", _n_coarse_entries);
634 }
635
636 // Now do the fine-grained maps.
637 for (size_t i = 0; i < _max_fine_entries; i++) {
638 PerRegionTable* cur = _fine_grain_regions[i];
639 PerRegionTable** prev = &_fine_grain_regions[i];
640 while (cur != NULL) {
641 PerRegionTable* nxt = cur->collision_list_next();
642 // If the entire region is dead, eliminate.
643 if (G1RSScrubVerbose) {
644 gclog_or_tty->print_cr(" For other region %u:",
645 cur->hr()->hrm_index());
646 }
647 if (!region_bm->at((size_t) cur->hr()->hrm_index())) {
648 *prev = nxt;
649 cur->set_collision_list_next(NULL);
650 _n_fine_entries--;
651 if (G1RSScrubVerbose) {
652 gclog_or_tty->print_cr(" deleted via region map.");
653 }
654 unlink_from_all(cur);
655 PerRegionTable::free(cur);
656 } else {
657 // Do fine-grain elimination.
658 if (G1RSScrubVerbose) {
659 gclog_or_tty->print(" occ: before = %4d.", cur->occupied());
660 }
661 cur->scrub(ctbs, card_bm);
662 if (G1RSScrubVerbose) {
663 gclog_or_tty->print_cr(" after = %4d.", cur->occupied());
664 }
665 // Did that empty the table completely?
666 if (cur->occupied() == 0) {
667 *prev = nxt;
668 cur->set_collision_list_next(NULL);
669 _n_fine_entries--;
670 unlink_from_all(cur);
671 PerRegionTable::free(cur);
672 } else {
673 prev = cur->collision_list_next_addr();
674 }
675 }
676 cur = nxt;
677 }
678 }
679 // Since we may have deleted a from_card_cache entry from the RS, clear
680 // the FCC.
681 clear_fcc();
682 }
683
684 bool OtherRegionsTable::is_empty() const {
685 return occ_sparse() == 0 && occ_coarse() == 0 && _first_all_fine_prts == NULL;
686 }
687
688 size_t OtherRegionsTable::occupied() const {
689 size_t sum = occ_fine();
690 sum += occ_sparse();
691 sum += occ_coarse();
692 return sum;
693 }
694
695 size_t OtherRegionsTable::occ_fine() const {
696 size_t sum = 0;
697
698 size_t num = 0;
699 PerRegionTable * cur = _first_all_fine_prts;
700 while (cur != NULL) {
701 sum += cur->occupied();
702 cur = cur->next();
703 num++;
704 }
705 guarantee(num == _n_fine_entries, "just checking");
706 return sum;
707 }
708
709 size_t OtherRegionsTable::occ_coarse() const {
710 return (_n_coarse_entries * HeapRegion::CardsPerRegion);
711 }
712
713 size_t OtherRegionsTable::occ_sparse() const {
714 return _sparse_table.occupied();
715 }
716
717 size_t OtherRegionsTable::mem_size() const {
718 size_t sum = 0;
719 // all PRTs are of the same size so it is sufficient to query only one of them.
720 if (_first_all_fine_prts != NULL) {
721 assert(_last_all_fine_prts != NULL &&
722 _first_all_fine_prts->mem_size() == _last_all_fine_prts->mem_size(), "check that mem_size() is constant");
723 sum += _first_all_fine_prts->mem_size() * _n_fine_entries;
724 }
725 sum += (sizeof(PerRegionTable*) * _max_fine_entries);
726 sum += (_coarse_map.size_in_words() * HeapWordSize);
727 sum += (_sparse_table.mem_size());
728 sum += sizeof(OtherRegionsTable) - sizeof(_sparse_table); // Avoid double counting above.
729 return sum;
730 }
731
732 size_t OtherRegionsTable::static_mem_size() {
733 return FromCardCache::static_mem_size();
734 }
735
736 size_t OtherRegionsTable::fl_mem_size() {
737 return PerRegionTable::fl_mem_size();
738 }
739
740 void OtherRegionsTable::clear_fcc() {
741 FromCardCache::clear(_hr->hrm_index());
742 }
743
744 void OtherRegionsTable::clear() {
745 // if there are no entries, skip this step
746 if (_first_all_fine_prts != NULL) {
747 guarantee(_first_all_fine_prts != NULL && _last_all_fine_prts != NULL, "just checking");
748 PerRegionTable::bulk_free(_first_all_fine_prts, _last_all_fine_prts);
749 memset(_fine_grain_regions, 0, _max_fine_entries * sizeof(_fine_grain_regions[0]));
750 } else {
751 guarantee(_first_all_fine_prts == NULL && _last_all_fine_prts == NULL, "just checking");
752 }
753
754 _first_all_fine_prts = _last_all_fine_prts = NULL;
755 _sparse_table.clear();
756 _coarse_map.clear();
757 _n_fine_entries = 0;
758 _n_coarse_entries = 0;
759
760 clear_fcc();
761 }
762
763 bool OtherRegionsTable::contains_reference(OopOrNarrowOopStar from) const {
764 // Cast away const in this case.
765 MutexLockerEx x((Mutex*)_m, Mutex::_no_safepoint_check_flag);
766 return contains_reference_locked(from);
767 }
768
769 bool OtherRegionsTable::contains_reference_locked(OopOrNarrowOopStar from) const {
770 HeapRegion* hr = _g1h->heap_region_containing_raw(from);
771 RegionIdx_t hr_ind = (RegionIdx_t) hr->hrm_index();
772 // Is this region in the coarse map?
773 if (_coarse_map.at(hr_ind)) return true;
774
775 PerRegionTable* prt = find_region_table(hr_ind & _mod_max_fine_entries_mask,
776 hr);
777 if (prt != NULL) {
778 return prt->contains_reference(from);
779
780 } else {
781 uintptr_t from_card =
782 (uintptr_t(from) >> CardTableModRefBS::card_shift);
783 uintptr_t hr_bot_card_index =
784 uintptr_t(hr->bottom()) >> CardTableModRefBS::card_shift;
785 assert(from_card >= hr_bot_card_index, "Inv");
786 CardIdx_t card_index = from_card - hr_bot_card_index;
787 assert(0 <= card_index && (size_t)card_index < HeapRegion::CardsPerRegion,
788 "Must be in range.");
789 return _sparse_table.contains_card(hr_ind, card_index);
790 }
791 }
792
793 void
794 OtherRegionsTable::do_cleanup_work(HRRSCleanupTask* hrrs_cleanup_task) {
795 _sparse_table.do_cleanup_work(hrrs_cleanup_task);
796 }
797
798 // Determines how many threads can add records to an rset in parallel.
799 // This can be done by either mutator threads together with the
800 // concurrent refinement threads or GC threads.
801 uint HeapRegionRemSet::num_par_rem_sets() {
802 return MAX2(DirtyCardQueueSet::num_par_ids() + ConcurrentG1Refine::thread_num(), (uint)ParallelGCThreads);
803 }
804
805 HeapRegionRemSet::HeapRegionRemSet(G1BlockOffsetSharedArray* bosa,
806 HeapRegion* hr)
807 : _bosa(bosa),
808 _m(Mutex::leaf, FormatBuffer<128>("HeapRegionRemSet lock #%u", hr->hrm_index()), true),
809 _code_roots(), _other_regions(hr, &_m), _iter_state(Unclaimed), _iter_claimed(0) {
810 reset_for_par_iteration();
811 }
812
813 void HeapRegionRemSet::setup_remset_size() {
814 // Setup sparse and fine-grain tables sizes.
815 // table_size = base * (log(region_size / 1M) + 1)
816 const int LOG_M = 20;
817 int region_size_log_mb = MAX2(HeapRegion::LogOfHRGrainBytes - LOG_M, 0);
818 if (FLAG_IS_DEFAULT(G1RSetSparseRegionEntries)) {
819 G1RSetSparseRegionEntries = G1RSetSparseRegionEntriesBase * (region_size_log_mb + 1);
820 }
821 if (FLAG_IS_DEFAULT(G1RSetRegionEntries)) {
822 G1RSetRegionEntries = G1RSetRegionEntriesBase * (region_size_log_mb + 1);
823 }
824 guarantee(G1RSetSparseRegionEntries > 0 && G1RSetRegionEntries > 0 , "Sanity");
825 }
826
827 bool HeapRegionRemSet::claim_iter() {
828 if (_iter_state != Unclaimed) return false;
829 jint res = Atomic::cmpxchg(Claimed, (jint*)(&_iter_state), Unclaimed);
830 return (res == Unclaimed);
831 }
832
833 void HeapRegionRemSet::set_iter_complete() {
834 _iter_state = Complete;
835 }
836
837 bool HeapRegionRemSet::iter_is_complete() {
838 return _iter_state == Complete;
839 }
840
841 #ifndef PRODUCT
842 void HeapRegionRemSet::print() {
843 HeapRegionRemSetIterator iter(this);
844 size_t card_index;
845 while (iter.has_next(card_index)) {
846 HeapWord* card_start =
847 G1CollectedHeap::heap()->bot_shared()->address_for_index(card_index);
848 gclog_or_tty->print_cr(" Card " PTR_FORMAT, card_start);
849 }
850 if (iter.n_yielded() != occupied()) {
851 gclog_or_tty->print_cr("Yielded disagrees with occupied:");
852 gclog_or_tty->print_cr(" " SIZE_FORMAT_W(6) " yielded (" SIZE_FORMAT_W(6)
853 " coarse, " SIZE_FORMAT_W(6) " fine).",
854 iter.n_yielded(),
855 iter.n_yielded_coarse(), iter.n_yielded_fine());
856 gclog_or_tty->print_cr(" " SIZE_FORMAT_W(6) " occ (" SIZE_FORMAT_W(6)
857 " coarse, " SIZE_FORMAT_W(6) " fine).",
858 occupied(), occ_coarse(), occ_fine());
859 }
860 guarantee(iter.n_yielded() == occupied(),
861 "We should have yielded all the represented cards.");
862 }
863 #endif
864
865 void HeapRegionRemSet::cleanup() {
866 SparsePRT::cleanup_all();
867 }
868
869 void HeapRegionRemSet::clear() {
870 MutexLockerEx x(&_m, Mutex::_no_safepoint_check_flag);
871 clear_locked();
872 }
873
874 void HeapRegionRemSet::clear_locked() {
875 _code_roots.clear();
876 _other_regions.clear();
877 assert(occupied_locked() == 0, "Should be clear.");
878 reset_for_par_iteration();
879 }
880
881 void HeapRegionRemSet::reset_for_par_iteration() {
882 _iter_state = Unclaimed;
883 _iter_claimed = 0;
884 // It's good to check this to make sure that the two methods are in sync.
885 assert(verify_ready_for_par_iteration(), "post-condition");
886 }
887
888 void HeapRegionRemSet::scrub(CardTableModRefBS* ctbs,
889 BitMap* region_bm, BitMap* card_bm) {
890 _other_regions.scrub(ctbs, region_bm, card_bm);
891 }
892
893 // Code roots support
894 //
895 // The code root set is protected by two separate locking schemes
896 // When at safepoint the per-hrrs lock must be held during modifications
897 // except when doing a full gc.
898 // When not at safepoint the CodeCache_lock must be held during modifications.
899 // When concurrent readers access the contains() function
900 // (during the evacuation phase) no removals are allowed.
901
902 void HeapRegionRemSet::add_strong_code_root(nmethod* nm) {
903 assert(nm != NULL, "sanity");
904 // Optimistic unlocked contains-check
905 if (!_code_roots.contains(nm)) {
906 MutexLockerEx ml(&_m, Mutex::_no_safepoint_check_flag);
907 add_strong_code_root_locked(nm);
908 }
909 }
910
911 void HeapRegionRemSet::add_strong_code_root_locked(nmethod* nm) {
912 assert(nm != NULL, "sanity");
913 _code_roots.add(nm);
914 }
915
916 void HeapRegionRemSet::remove_strong_code_root(nmethod* nm) {
917 assert(nm != NULL, "sanity");
918 assert_locked_or_safepoint(CodeCache_lock);
919
920 MutexLockerEx ml(CodeCache_lock->owned_by_self() ? NULL : &_m, Mutex::_no_safepoint_check_flag);
921 _code_roots.remove(nm);
922
923 // Check that there were no duplicates
924 guarantee(!_code_roots.contains(nm), "duplicate entry found");
925 }
926
927 void HeapRegionRemSet::strong_code_roots_do(CodeBlobClosure* blk) const {
928 _code_roots.nmethods_do(blk);
929 }
930
931 void HeapRegionRemSet::clean_strong_code_roots(HeapRegion* hr) {
932 _code_roots.clean(hr);
933 }
934
935 size_t HeapRegionRemSet::strong_code_roots_mem_size() {
936 return _code_roots.mem_size();
937 }
938
939 HeapRegionRemSetIterator:: HeapRegionRemSetIterator(HeapRegionRemSet* hrrs) :
940 _hrrs(hrrs),
941 _g1h(G1CollectedHeap::heap()),
942 _coarse_map(&hrrs->_other_regions._coarse_map),
943 _bosa(hrrs->_bosa),
944 _is(Sparse),
945 // Set these values so that we increment to the first region.
946 _coarse_cur_region_index(-1),
947 _coarse_cur_region_cur_card(HeapRegion::CardsPerRegion-1),
948 _cur_card_in_prt(HeapRegion::CardsPerRegion),
949 _fine_cur_prt(NULL),
950 _n_yielded_coarse(0),
951 _n_yielded_fine(0),
952 _n_yielded_sparse(0),
953 _sparse_iter(&hrrs->_other_regions._sparse_table) {}
954
955 bool HeapRegionRemSetIterator::coarse_has_next(size_t& card_index) {
956 if (_hrrs->_other_regions._n_coarse_entries == 0) return false;
957 // Go to the next card.
958 _coarse_cur_region_cur_card++;
959 // Was the last the last card in the current region?
960 if (_coarse_cur_region_cur_card == HeapRegion::CardsPerRegion) {
961 // Yes: find the next region. This may leave _coarse_cur_region_index
962 // Set to the last index, in which case there are no more coarse
963 // regions.
964 _coarse_cur_region_index =
965 (int) _coarse_map->get_next_one_offset(_coarse_cur_region_index + 1);
966 if ((size_t)_coarse_cur_region_index < _coarse_map->size()) {
967 _coarse_cur_region_cur_card = 0;
968 HeapWord* r_bot =
969 _g1h->region_at((uint) _coarse_cur_region_index)->bottom();
970 _cur_region_card_offset = _bosa->index_for(r_bot);
971 } else {
972 return false;
973 }
974 }
975 // If we didn't return false above, then we can yield a card.
976 card_index = _cur_region_card_offset + _coarse_cur_region_cur_card;
977 return true;
978 }
979
980 bool HeapRegionRemSetIterator::fine_has_next(size_t& card_index) {
981 if (fine_has_next()) {
982 _cur_card_in_prt =
983 _fine_cur_prt->_bm.get_next_one_offset(_cur_card_in_prt + 1);
984 }
985 if (_cur_card_in_prt == HeapRegion::CardsPerRegion) {
986 // _fine_cur_prt may still be NULL in case if there are not PRTs at all for
987 // the remembered set.
988 if (_fine_cur_prt == NULL || _fine_cur_prt->next() == NULL) {
989 return false;
990 }
991 PerRegionTable* next_prt = _fine_cur_prt->next();
992 switch_to_prt(next_prt);
993 _cur_card_in_prt = _fine_cur_prt->_bm.get_next_one_offset(_cur_card_in_prt + 1);
994 }
995
996 card_index = _cur_region_card_offset + _cur_card_in_prt;
997 guarantee(_cur_card_in_prt < HeapRegion::CardsPerRegion,
998 err_msg("Card index "SIZE_FORMAT" must be within the region", _cur_card_in_prt));
999 return true;
1000 }
1001
1002 bool HeapRegionRemSetIterator::fine_has_next() {
1003 return _cur_card_in_prt != HeapRegion::CardsPerRegion;
1004 }
1005
1006 void HeapRegionRemSetIterator::switch_to_prt(PerRegionTable* prt) {
1007 assert(prt != NULL, "Cannot switch to NULL prt");
1008 _fine_cur_prt = prt;
1009
1010 HeapWord* r_bot = _fine_cur_prt->hr()->bottom();
1011 _cur_region_card_offset = _bosa->index_for(r_bot);
1012
1013 // The bitmap scan for the PRT always scans from _cur_region_cur_card + 1.
1014 // To avoid special-casing this start case, and not miss the first bitmap
1015 // entry, initialize _cur_region_cur_card with -1 instead of 0.
1016 _cur_card_in_prt = (size_t)-1;
1017 }
1018
1019 bool HeapRegionRemSetIterator::has_next(size_t& card_index) {
1020 switch (_is) {
1021 case Sparse: {
1022 if (_sparse_iter.has_next(card_index)) {
1023 _n_yielded_sparse++;
1024 return true;
1025 }
1026 // Otherwise, deliberate fall-through
1027 _is = Fine;
1028 PerRegionTable* initial_fine_prt = _hrrs->_other_regions._first_all_fine_prts;
1029 if (initial_fine_prt != NULL) {
1030 switch_to_prt(_hrrs->_other_regions._first_all_fine_prts);
1031 }
1032 }
1033 case Fine:
1034 if (fine_has_next(card_index)) {
1035 _n_yielded_fine++;
1036 return true;
1037 }
1038 // Otherwise, deliberate fall-through
1039 _is = Coarse;
1040 case Coarse:
1041 if (coarse_has_next(card_index)) {
1042 _n_yielded_coarse++;
1043 return true;
1044 }
1045 // Otherwise...
1046 break;
1047 }
1048 assert(ParallelGCThreads > 1 ||
1049 n_yielded() == _hrrs->occupied(),
1050 "Should have yielded all the cards in the rem set "
1051 "(in the non-par case).");
1052 return false;
1053 }
1054
1055
1056
1057 OopOrNarrowOopStar* HeapRegionRemSet::_recorded_oops = NULL;
1058 HeapWord** HeapRegionRemSet::_recorded_cards = NULL;
1059 HeapRegion** HeapRegionRemSet::_recorded_regions = NULL;
1060 int HeapRegionRemSet::_n_recorded = 0;
1061
1062 HeapRegionRemSet::Event* HeapRegionRemSet::_recorded_events = NULL;
1063 int* HeapRegionRemSet::_recorded_event_index = NULL;
1064 int HeapRegionRemSet::_n_recorded_events = 0;
1065
1066 void HeapRegionRemSet::record(HeapRegion* hr, OopOrNarrowOopStar f) {
1067 if (_recorded_oops == NULL) {
1068 assert(_n_recorded == 0
1069 && _recorded_cards == NULL
1070 && _recorded_regions == NULL,
1071 "Inv");
1072 _recorded_oops = NEW_C_HEAP_ARRAY(OopOrNarrowOopStar, MaxRecorded, mtGC);
1073 _recorded_cards = NEW_C_HEAP_ARRAY(HeapWord*, MaxRecorded, mtGC);
1074 _recorded_regions = NEW_C_HEAP_ARRAY(HeapRegion*, MaxRecorded, mtGC);
1075 }
1076 if (_n_recorded == MaxRecorded) {
1077 gclog_or_tty->print_cr("Filled up 'recorded' (%d).", MaxRecorded);
1078 } else {
1079 _recorded_cards[_n_recorded] =
1080 (HeapWord*)align_size_down(uintptr_t(f),
1081 CardTableModRefBS::card_size);
1082 _recorded_oops[_n_recorded] = f;
1083 _recorded_regions[_n_recorded] = hr;
1084 _n_recorded++;
1085 }
1086 }
1087
1088 void HeapRegionRemSet::record_event(Event evnt) {
1089 if (!G1RecordHRRSEvents) return;
1090
1091 if (_recorded_events == NULL) {
1092 assert(_n_recorded_events == 0
1093 && _recorded_event_index == NULL,
1094 "Inv");
1095 _recorded_events = NEW_C_HEAP_ARRAY(Event, MaxRecordedEvents, mtGC);
1096 _recorded_event_index = NEW_C_HEAP_ARRAY(int, MaxRecordedEvents, mtGC);
1097 }
1098 if (_n_recorded_events == MaxRecordedEvents) {
1099 gclog_or_tty->print_cr("Filled up 'recorded_events' (%d).", MaxRecordedEvents);
1100 } else {
1101 _recorded_events[_n_recorded_events] = evnt;
1102 _recorded_event_index[_n_recorded_events] = _n_recorded;
1103 _n_recorded_events++;
1104 }
1105 }
1106
1107 void HeapRegionRemSet::print_event(outputStream* str, Event evnt) {
1108 switch (evnt) {
1109 case Event_EvacStart:
1110 str->print("Evac Start");
1111 break;
1112 case Event_EvacEnd:
1113 str->print("Evac End");
1114 break;
1115 case Event_RSUpdateEnd:
1116 str->print("RS Update End");
1117 break;
1118 }
1119 }
1120
1121 void HeapRegionRemSet::print_recorded() {
1122 int cur_evnt = 0;
1123 Event cur_evnt_kind;
1124 int cur_evnt_ind = 0;
1125 if (_n_recorded_events > 0) {
1126 cur_evnt_kind = _recorded_events[cur_evnt];
1127 cur_evnt_ind = _recorded_event_index[cur_evnt];
1128 }
1129
1130 for (int i = 0; i < _n_recorded; i++) {
1131 while (cur_evnt < _n_recorded_events && i == cur_evnt_ind) {
1132 gclog_or_tty->print("Event: ");
1133 print_event(gclog_or_tty, cur_evnt_kind);
1134 gclog_or_tty->cr();
1135 cur_evnt++;
1136 if (cur_evnt < MaxRecordedEvents) {
1137 cur_evnt_kind = _recorded_events[cur_evnt];
1138 cur_evnt_ind = _recorded_event_index[cur_evnt];
1139 }
1140 }
1141 gclog_or_tty->print("Added card " PTR_FORMAT " to region [" PTR_FORMAT "...]"
1142 " for ref " PTR_FORMAT ".\n",
1143 _recorded_cards[i], _recorded_regions[i]->bottom(),
1144 _recorded_oops[i]);
1145 }
1146 }
1147
1148 void HeapRegionRemSet::reset_for_cleanup_tasks() {
1149 SparsePRT::reset_for_cleanup_tasks();
1150 }
1151
1152 void HeapRegionRemSet::do_cleanup_work(HRRSCleanupTask* hrrs_cleanup_task) {
1153 _other_regions.do_cleanup_work(hrrs_cleanup_task);
1154 }
1155
1156 void
1157 HeapRegionRemSet::finish_cleanup_task(HRRSCleanupTask* hrrs_cleanup_task) {
1158 SparsePRT::finish_cleanup_task(hrrs_cleanup_task);
1159 }
1160
1161 #ifndef PRODUCT
1162 void PerRegionTable::test_fl_mem_size() {
1163 PerRegionTable* dummy = alloc(NULL);
1164
1165 size_t min_prt_size = sizeof(void*) + dummy->bm()->size_in_words() * HeapWordSize;
1166 assert(dummy->mem_size() > min_prt_size,
1167 err_msg("PerRegionTable memory usage is suspiciously small, only has "SIZE_FORMAT" bytes. "
1168 "Should be at least "SIZE_FORMAT" bytes.", dummy->mem_size(), min_prt_size));
1169 free(dummy);
1170 guarantee(dummy->mem_size() == fl_mem_size(), "fl_mem_size() does not return the correct element size");
1171 // try to reset the state
1172 _free_list = NULL;
1173 delete dummy;
1174 }
1175
1176 void HeapRegionRemSet::test_prt() {
1177 PerRegionTable::test_fl_mem_size();
1178 }
1179
1180 void HeapRegionRemSet::test() {
1181 os::sleep(Thread::current(), (jlong)5000, false);
1182 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1183
1184 // Run with "-XX:G1LogRSetRegionEntries=2", so that 1 and 5 end up in same
1185 // hash bucket.
1186 HeapRegion* hr0 = g1h->region_at(0);
1187 HeapRegion* hr1 = g1h->region_at(1);
1188 HeapRegion* hr2 = g1h->region_at(5);
1189 HeapRegion* hr3 = g1h->region_at(6);
1190 HeapRegion* hr4 = g1h->region_at(7);
1191 HeapRegion* hr5 = g1h->region_at(8);
1192
1193 HeapWord* hr1_start = hr1->bottom();
1194 HeapWord* hr1_mid = hr1_start + HeapRegion::GrainWords/2;
1195 HeapWord* hr1_last = hr1->end() - 1;
1196
1197 HeapWord* hr2_start = hr2->bottom();
1198 HeapWord* hr2_mid = hr2_start + HeapRegion::GrainWords/2;
1199 HeapWord* hr2_last = hr2->end() - 1;
1200
1201 HeapWord* hr3_start = hr3->bottom();
1202 HeapWord* hr3_mid = hr3_start + HeapRegion::GrainWords/2;
1203 HeapWord* hr3_last = hr3->end() - 1;
1204
1205 HeapRegionRemSet* hrrs = hr0->rem_set();
1206
1207 // Make three references from region 0x101...
1208 hrrs->add_reference((OopOrNarrowOopStar)hr1_start);
1209 hrrs->add_reference((OopOrNarrowOopStar)hr1_mid);
1210 hrrs->add_reference((OopOrNarrowOopStar)hr1_last);
1211
1212 hrrs->add_reference((OopOrNarrowOopStar)hr2_start);
1213 hrrs->add_reference((OopOrNarrowOopStar)hr2_mid);
1214 hrrs->add_reference((OopOrNarrowOopStar)hr2_last);
1215
1216 hrrs->add_reference((OopOrNarrowOopStar)hr3_start);
1217 hrrs->add_reference((OopOrNarrowOopStar)hr3_mid);
1218 hrrs->add_reference((OopOrNarrowOopStar)hr3_last);
1219
1220 // Now cause a coarsening.
1221 hrrs->add_reference((OopOrNarrowOopStar)hr4->bottom());
1222 hrrs->add_reference((OopOrNarrowOopStar)hr5->bottom());
1223
1224 // Now, does iteration yield these three?
1225 HeapRegionRemSetIterator iter(hrrs);
1226 size_t sum = 0;
1227 size_t card_index;
1228 while (iter.has_next(card_index)) {
1229 HeapWord* card_start =
1230 G1CollectedHeap::heap()->bot_shared()->address_for_index(card_index);
1231 gclog_or_tty->print_cr(" Card " PTR_FORMAT ".", card_start);
1232 sum++;
1233 }
1234 guarantee(sum == 11 - 3 + 2048, "Failure");
1235 guarantee(sum == hrrs->occupied(), "Failure");
1236 }
1237 #endif