1 /*
2 * Copyright (c) 2000, 2012, 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 "memory/allocation.inline.hpp"
27 #include "memory/cardTableModRefBS.hpp"
28 #include "memory/cardTableRS.hpp"
29 #include "memory/sharedHeap.hpp"
30 #include "memory/space.hpp"
31 #include "memory/space.inline.hpp"
32 #include "memory/universe.hpp"
33 #include "runtime/java.hpp"
34 #include "runtime/mutexLocker.hpp"
35 #include "runtime/virtualspace.hpp"
36 #include "services/memTracker.hpp"
37 #include "utilities/macros.hpp"
38 #ifdef COMPILER1
39 #include "c1/c1_LIR.hpp"
40 #include "c1/c1_LIRGenerator.hpp"
41 #endif
42
43 // This kind of "BarrierSet" allows a "CollectedHeap" to detect and
44 // enumerate ref fields that have been modified (since the last
45 // enumeration.)
46
47 size_t CardTableModRefBS::cards_required(size_t covered_words)
48 {
49 // Add one for a guard card, used to detect errors.
50 const size_t words = align_size_up(covered_words, card_size_in_words);
51 return words / card_size_in_words + 1;
52 }
53
54 size_t CardTableModRefBS::compute_byte_map_size()
55 {
56 assert(_guard_index == cards_required(_whole_heap.word_size()) - 1,
57 "unitialized, check declaration order");
58 assert(_page_size != 0, "unitialized, check declaration order");
59 const size_t granularity = os::vm_allocation_granularity();
60 return align_size_up(_guard_index + 1, MAX2(_page_size, granularity));
61 }
62
63 CardTableModRefBS::CardTableModRefBS(MemRegion whole_heap,
64 int max_covered_regions):
65 ModRefBarrierSet(max_covered_regions),
66 _whole_heap(whole_heap),
67 _guard_index(cards_required(whole_heap.word_size()) - 1),
68 _last_valid_index(_guard_index - 1),
69 _page_size(os::vm_page_size()),
70 _byte_map_size(compute_byte_map_size())
71 {
72 _kind = BarrierSet::CardTableModRef;
73
74 HeapWord* low_bound = _whole_heap.start();
75 HeapWord* high_bound = _whole_heap.end();
76 assert((uintptr_t(low_bound) & (card_size - 1)) == 0, "heap must start at card boundary");
77 assert((uintptr_t(high_bound) & (card_size - 1)) == 0, "heap must end at card boundary");
78
79 assert(card_size <= 512, "card_size must be less than 512"); // why?
80
81 _covered = new MemRegion[max_covered_regions];
82 _committed = new MemRegion[max_covered_regions];
83 if (_covered == NULL || _committed == NULL)
84 vm_exit_during_initialization("couldn't alloc card table covered region set.");
85 int i;
86 for (i = 0; i < max_covered_regions; i++) {
87 _covered[i].set_word_size(0);
88 _committed[i].set_word_size(0);
89 }
90 _cur_covered_regions = 0;
91
92 const size_t rs_align = _page_size == (size_t) os::vm_page_size() ? 0 :
93 MAX2(_page_size, (size_t) os::vm_allocation_granularity());
94 ReservedSpace heap_rs(_byte_map_size, rs_align, false);
95
96 MemTracker::record_virtual_memory_type((address)heap_rs.base(), mtGC);
97
98 os::trace_page_sizes("card table", _guard_index + 1, _guard_index + 1,
99 _page_size, heap_rs.base(), heap_rs.size());
100 if (!heap_rs.is_reserved()) {
101 vm_exit_during_initialization("Could not reserve enough space for the "
102 "card marking array");
103 }
104
105 // The assember store_check code will do an unsigned shift of the oop,
106 // then add it to byte_map_base, i.e.
107 //
108 // _byte_map = byte_map_base + (uintptr_t(low_bound) >> card_shift)
109 _byte_map = (jbyte*) heap_rs.base();
110 byte_map_base = _byte_map - (uintptr_t(low_bound) >> card_shift);
111 assert(byte_for(low_bound) == &_byte_map[0], "Checking start of map");
112 assert(byte_for(high_bound-1) <= &_byte_map[_last_valid_index], "Checking end of map");
113
114 jbyte* guard_card = &_byte_map[_guard_index];
115 uintptr_t guard_page = align_size_down((uintptr_t)guard_card, _page_size);
116 _guard_region = MemRegion((HeapWord*)guard_page, _page_size);
117 if (!os::commit_memory((char*)guard_page, _page_size, _page_size)) {
118 // Do better than this for Merlin
119 vm_exit_out_of_memory(_page_size, OOM_MMAP_ERROR, "card table last card");
120 }
121
122 *guard_card = last_card;
123
124 _lowest_non_clean =
125 NEW_C_HEAP_ARRAY(CardArr, max_covered_regions, mtGC);
126 _lowest_non_clean_chunk_size =
127 NEW_C_HEAP_ARRAY(size_t, max_covered_regions, mtGC);
128 _lowest_non_clean_base_chunk_index =
129 NEW_C_HEAP_ARRAY(uintptr_t, max_covered_regions, mtGC);
130 _last_LNC_resizing_collection =
131 NEW_C_HEAP_ARRAY(int, max_covered_regions, mtGC);
132 if (_lowest_non_clean == NULL
133 || _lowest_non_clean_chunk_size == NULL
134 || _lowest_non_clean_base_chunk_index == NULL
135 || _last_LNC_resizing_collection == NULL)
136 vm_exit_during_initialization("couldn't allocate an LNC array.");
137 for (i = 0; i < max_covered_regions; i++) {
138 _lowest_non_clean[i] = NULL;
139 _lowest_non_clean_chunk_size[i] = 0;
140 _last_LNC_resizing_collection[i] = -1;
141 }
142
143 if (TraceCardTableModRefBS) {
144 gclog_or_tty->print_cr("CardTableModRefBS::CardTableModRefBS: ");
145 gclog_or_tty->print_cr(" "
146 " &_byte_map[0]: " INTPTR_FORMAT
147 " &_byte_map[_last_valid_index]: " INTPTR_FORMAT,
148 &_byte_map[0],
149 &_byte_map[_last_valid_index]);
150 gclog_or_tty->print_cr(" "
151 " byte_map_base: " INTPTR_FORMAT,
152 byte_map_base);
153 }
154 }
155
156 int CardTableModRefBS::find_covering_region_by_base(HeapWord* base) {
157 int i;
158 for (i = 0; i < _cur_covered_regions; i++) {
159 if (_covered[i].start() == base) return i;
160 if (_covered[i].start() > base) break;
161 }
162 // If we didn't find it, create a new one.
163 assert(_cur_covered_regions < _max_covered_regions,
164 "too many covered regions");
165 // Move the ones above up, to maintain sorted order.
166 for (int j = _cur_covered_regions; j > i; j--) {
167 _covered[j] = _covered[j-1];
168 _committed[j] = _committed[j-1];
169 }
170 int res = i;
171 _cur_covered_regions++;
172 _covered[res].set_start(base);
173 _covered[res].set_word_size(0);
174 jbyte* ct_start = byte_for(base);
175 uintptr_t ct_start_aligned = align_size_down((uintptr_t)ct_start, _page_size);
176 _committed[res].set_start((HeapWord*)ct_start_aligned);
177 _committed[res].set_word_size(0);
178 return res;
179 }
180
181 int CardTableModRefBS::find_covering_region_containing(HeapWord* addr) {
182 for (int i = 0; i < _cur_covered_regions; i++) {
183 if (_covered[i].contains(addr)) {
184 return i;
185 }
186 }
187 assert(0, "address outside of heap?");
188 return -1;
189 }
190
191 HeapWord* CardTableModRefBS::largest_prev_committed_end(int ind) const {
192 HeapWord* max_end = NULL;
193 for (int j = 0; j < ind; j++) {
194 HeapWord* this_end = _committed[j].end();
195 if (this_end > max_end) max_end = this_end;
196 }
197 return max_end;
198 }
199
200 MemRegion CardTableModRefBS::committed_unique_to_self(int self,
201 MemRegion mr) const {
202 MemRegion result = mr;
203 for (int r = 0; r < _cur_covered_regions; r += 1) {
204 if (r != self) {
205 result = result.minus(_committed[r]);
206 }
207 }
208 // Never include the guard page.
209 result = result.minus(_guard_region);
210 return result;
211 }
212
213 void CardTableModRefBS::resize_covered_region(MemRegion new_region) {
214 // We don't change the start of a region, only the end.
215 assert(_whole_heap.contains(new_region),
216 "attempt to cover area not in reserved area");
217 debug_only(verify_guard();)
218 // collided is true if the expansion would push into another committed region
219 debug_only(bool collided = false;)
220 int const ind = find_covering_region_by_base(new_region.start());
221 MemRegion const old_region = _covered[ind];
222 assert(old_region.start() == new_region.start(), "just checking");
223 if (new_region.word_size() != old_region.word_size()) {
224 // Commit new or uncommit old pages, if necessary.
225 MemRegion cur_committed = _committed[ind];
226 // Extend the end of this _commited region
227 // to cover the end of any lower _committed regions.
228 // This forms overlapping regions, but never interior regions.
229 HeapWord* const max_prev_end = largest_prev_committed_end(ind);
230 if (max_prev_end > cur_committed.end()) {
231 cur_committed.set_end(max_prev_end);
232 }
233 // Align the end up to a page size (starts are already aligned).
234 jbyte* const new_end = byte_after(new_region.last());
235 HeapWord* new_end_aligned =
236 (HeapWord*) align_size_up((uintptr_t)new_end, _page_size);
237 assert(new_end_aligned >= (HeapWord*) new_end,
238 "align up, but less");
239 // Check the other regions (excludes "ind") to ensure that
240 // the new_end_aligned does not intrude onto the committed
241 // space of another region.
242 int ri = 0;
243 for (ri = 0; ri < _cur_covered_regions; ri++) {
244 if (ri != ind) {
245 if (_committed[ri].contains(new_end_aligned)) {
246 // The prior check included in the assert
247 // (new_end_aligned >= _committed[ri].start())
248 // is redundant with the "contains" test.
249 // Any region containing the new end
250 // should start at or beyond the region found (ind)
251 // for the new end (committed regions are not expected to
252 // be proper subsets of other committed regions).
253 assert(_committed[ri].start() >= _committed[ind].start(),
254 "New end of committed region is inconsistent");
255 new_end_aligned = _committed[ri].start();
256 // new_end_aligned can be equal to the start of its
257 // committed region (i.e., of "ind") if a second
258 // region following "ind" also start at the same location
259 // as "ind".
260 assert(new_end_aligned >= _committed[ind].start(),
261 "New end of committed region is before start");
262 debug_only(collided = true;)
263 // Should only collide with 1 region
264 break;
265 }
266 }
267 }
268 #ifdef ASSERT
269 for (++ri; ri < _cur_covered_regions; ri++) {
270 assert(!_committed[ri].contains(new_end_aligned),
271 "New end of committed region is in a second committed region");
272 }
273 #endif
274 // The guard page is always committed and should not be committed over.
275 // "guarded" is used for assertion checking below and recalls the fact
276 // that the would-be end of the new committed region would have
277 // penetrated the guard page.
278 HeapWord* new_end_for_commit = new_end_aligned;
279
280 DEBUG_ONLY(bool guarded = false;)
281 if (new_end_for_commit > _guard_region.start()) {
282 new_end_for_commit = _guard_region.start();
283 DEBUG_ONLY(guarded = true;)
284 }
285
286 if (new_end_for_commit > cur_committed.end()) {
287 // Must commit new pages.
288 MemRegion const new_committed =
289 MemRegion(cur_committed.end(), new_end_for_commit);
290
291 assert(!new_committed.is_empty(), "Region should not be empty here");
292 if (!os::commit_memory((char*)new_committed.start(),
293 new_committed.byte_size(), _page_size)) {
294 // Do better than this for Merlin
295 vm_exit_out_of_memory(new_committed.byte_size(), OOM_MMAP_ERROR,
296 "card table expansion");
297 }
298 // Use new_end_aligned (as opposed to new_end_for_commit) because
299 // the cur_committed region may include the guard region.
300 } else if (new_end_aligned < cur_committed.end()) {
301 // Must uncommit pages.
302 MemRegion const uncommit_region =
303 committed_unique_to_self(ind, MemRegion(new_end_aligned,
304 cur_committed.end()));
305 if (!uncommit_region.is_empty()) {
306 // It is not safe to uncommit cards if the boundary between
307 // the generations is moving. A shrink can uncommit cards
308 // owned by generation A but being used by generation B.
309 if (!UseAdaptiveGCBoundary) {
310 if (!os::uncommit_memory((char*)uncommit_region.start(),
311 uncommit_region.byte_size())) {
312 assert(false, "Card table contraction failed");
313 // The call failed so don't change the end of the
314 // committed region. This is better than taking the
315 // VM down.
316 new_end_aligned = _committed[ind].end();
317 }
318 } else {
319 new_end_aligned = _committed[ind].end();
320 }
321 }
322 }
323 // In any case, we can reset the end of the current committed entry.
324 _committed[ind].set_end(new_end_aligned);
325
326 #ifdef ASSERT
327 // Check that the last card in the new region is committed according
328 // to the tables.
329 bool covered = false;
330 for (int cr = 0; cr < _cur_covered_regions; cr++) {
331 if (_committed[cr].contains(new_end - 1)) {
332 covered = true;
333 break;
334 }
335 }
336 assert(covered, "Card for end of new region not committed");
337 #endif
338
339 // The default of 0 is not necessarily clean cards.
340 jbyte* entry;
341 if (old_region.last() < _whole_heap.start()) {
342 entry = byte_for(_whole_heap.start());
343 } else {
344 entry = byte_after(old_region.last());
345 }
346 assert(index_for(new_region.last()) < _guard_index,
347 "The guard card will be overwritten");
348 // This line commented out cleans the newly expanded region and
349 // not the aligned up expanded region.
350 // jbyte* const end = byte_after(new_region.last());
351 jbyte* const end = (jbyte*) new_end_for_commit;
352 assert((end >= byte_after(new_region.last())) || collided || guarded,
353 "Expect to be beyond new region unless impacting another region");
354 // do nothing if we resized downward.
355 #ifdef ASSERT
356 for (int ri = 0; ri < _cur_covered_regions; ri++) {
357 if (ri != ind) {
358 // The end of the new committed region should not
359 // be in any existing region unless it matches
360 // the start of the next region.
361 assert(!_committed[ri].contains(end) ||
362 (_committed[ri].start() == (HeapWord*) end),
363 "Overlapping committed regions");
364 }
365 }
366 #endif
367 if (entry < end) {
368 memset(entry, clean_card, pointer_delta(end, entry, sizeof(jbyte)));
369 }
370 }
371 // In any case, the covered size changes.
372 _covered[ind].set_word_size(new_region.word_size());
373 if (TraceCardTableModRefBS) {
374 gclog_or_tty->print_cr("CardTableModRefBS::resize_covered_region: ");
375 gclog_or_tty->print_cr(" "
376 " _covered[%d].start(): " INTPTR_FORMAT
377 " _covered[%d].last(): " INTPTR_FORMAT,
378 ind, _covered[ind].start(),
379 ind, _covered[ind].last());
380 gclog_or_tty->print_cr(" "
381 " _committed[%d].start(): " INTPTR_FORMAT
382 " _committed[%d].last(): " INTPTR_FORMAT,
383 ind, _committed[ind].start(),
384 ind, _committed[ind].last());
385 gclog_or_tty->print_cr(" "
386 " byte_for(start): " INTPTR_FORMAT
387 " byte_for(last): " INTPTR_FORMAT,
388 byte_for(_covered[ind].start()),
389 byte_for(_covered[ind].last()));
390 gclog_or_tty->print_cr(" "
391 " addr_for(start): " INTPTR_FORMAT
392 " addr_for(last): " INTPTR_FORMAT,
393 addr_for((jbyte*) _committed[ind].start()),
394 addr_for((jbyte*) _committed[ind].last()));
395 }
396 // Touch the last card of the covered region to show that it
397 // is committed (or SEGV).
398 debug_only(*byte_for(_covered[ind].last());)
399 debug_only(verify_guard();)
400 }
401
402 // Note that these versions are precise! The scanning code has to handle the
403 // fact that the write barrier may be either precise or imprecise.
404
405 void CardTableModRefBS::write_ref_field_work(void* field, oop newVal) {
406 inline_write_ref_field(field, newVal);
407 }
408
409 /*
410 Claimed and deferred bits are used together in G1 during the evacuation
411 pause. These bits can have the following state transitions:
412 1. The claimed bit can be put over any other card state. Except that
413 the "dirty -> dirty and claimed" transition is checked for in
414 G1 code and is not used.
415 2. Deferred bit can be set only if the previous state of the card
416 was either clean or claimed. mark_card_deferred() is wait-free.
417 We do not care if the operation is be successful because if
418 it does not it will only result in duplicate entry in the update
419 buffer because of the "cache-miss". So it's not worth spinning.
420 */
421
422
423 bool CardTableModRefBS::claim_card(size_t card_index) {
424 jbyte val = _byte_map[card_index];
425 assert(val != dirty_card_val(), "Shouldn't claim a dirty card");
426 while (val == clean_card_val() ||
427 (val & (clean_card_mask_val() | claimed_card_val())) != claimed_card_val()) {
428 jbyte new_val = val;
429 if (val == clean_card_val()) {
430 new_val = (jbyte)claimed_card_val();
431 } else {
432 new_val = val | (jbyte)claimed_card_val();
433 }
434 jbyte res = Atomic::cmpxchg(new_val, &_byte_map[card_index], val);
435 if (res == val) {
436 return true;
437 }
438 val = res;
439 }
440 return false;
441 }
442
443 bool CardTableModRefBS::mark_card_deferred(size_t card_index) {
444 jbyte val = _byte_map[card_index];
445 // It's already processed
446 if ((val & (clean_card_mask_val() | deferred_card_val())) == deferred_card_val()) {
447 return false;
448 }
449 // Cached bit can be installed either on a clean card or on a claimed card.
450 jbyte new_val = val;
451 if (val == clean_card_val()) {
452 new_val = (jbyte)deferred_card_val();
453 } else {
454 if (val & claimed_card_val()) {
455 new_val = val | (jbyte)deferred_card_val();
456 }
457 }
458 if (new_val != val) {
459 Atomic::cmpxchg(new_val, &_byte_map[card_index], val);
460 }
461 return true;
462 }
463
464 void CardTableModRefBS::non_clean_card_iterate_possibly_parallel(Space* sp,
465 MemRegion mr,
466 OopsInGenClosure* cl,
467 CardTableRS* ct) {
468 if (!mr.is_empty()) {
469 // Caller (process_strong_roots()) claims that all GC threads
470 // execute this call. With UseDynamicNumberOfGCThreads now all
471 // active GC threads execute this call. The number of active GC
472 // threads needs to be passed to par_non_clean_card_iterate_work()
473 // to get proper partitioning and termination.
474 //
475 // This is an example of where n_par_threads() is used instead
476 // of workers()->active_workers(). n_par_threads can be set to 0 to
477 // turn off parallelism. For example when this code is called as
478 // part of verification and SharedHeap::process_strong_roots() is being
479 // used, then n_par_threads() may have been set to 0. active_workers
480 // is not overloaded with the meaning that it is a switch to disable
481 // parallelism and so keeps the meaning of the number of
482 // active gc workers. If parallelism has not been shut off by
483 // setting n_par_threads to 0, then n_par_threads should be
484 // equal to active_workers. When a different mechanism for shutting
485 // off parallelism is used, then active_workers can be used in
486 // place of n_par_threads.
487 // This is an example of a path where n_par_threads is
488 // set to 0 to turn off parallism.
489 // [7] CardTableModRefBS::non_clean_card_iterate()
490 // [8] CardTableRS::younger_refs_in_space_iterate()
491 // [9] Generation::younger_refs_in_space_iterate()
492 // [10] OneContigSpaceCardGeneration::younger_refs_iterate()
493 // [11] CompactingPermGenGen::younger_refs_iterate()
494 // [12] CardTableRS::younger_refs_iterate()
495 // [13] SharedHeap::process_strong_roots()
496 // [14] G1CollectedHeap::verify()
497 // [15] Universe::verify()
498 // [16] G1CollectedHeap::do_collection_pause_at_safepoint()
499 //
500 int n_threads = SharedHeap::heap()->n_par_threads();
501 bool is_par = n_threads > 0;
502 if (is_par) {
503 #if INCLUDE_ALL_GCS
504 assert(SharedHeap::heap()->n_par_threads() ==
505 SharedHeap::heap()->workers()->active_workers(), "Mismatch");
506 non_clean_card_iterate_parallel_work(sp, mr, cl, ct, n_threads);
507 #else // INCLUDE_ALL_GCS
508 fatal("Parallel gc not supported here.");
509 #endif // INCLUDE_ALL_GCS
510 } else {
511 // We do not call the non_clean_card_iterate_serial() version below because
512 // we want to clear the cards (which non_clean_card_iterate_serial() does not
513 // do for us): clear_cl here does the work of finding contiguous dirty ranges
514 // of cards to process and clear.
515
516 DirtyCardToOopClosure* dcto_cl = sp->new_dcto_cl(cl, precision(),
517 cl->gen_boundary());
518 ClearNoncleanCardWrapper clear_cl(dcto_cl, ct);
519
520 clear_cl.do_MemRegion(mr);
521 }
522 }
523 }
524
525 // The iterator itself is not MT-aware, but
526 // MT-aware callers and closures can use this to
527 // accomplish dirty card iteration in parallel. The
528 // iterator itself does not clear the dirty cards, or
529 // change their values in any manner.
530 void CardTableModRefBS::non_clean_card_iterate_serial(MemRegion mr,
531 MemRegionClosure* cl) {
532 bool is_par = (SharedHeap::heap()->n_par_threads() > 0);
533 assert(!is_par ||
534 (SharedHeap::heap()->n_par_threads() ==
535 SharedHeap::heap()->workers()->active_workers()), "Mismatch");
536 for (int i = 0; i < _cur_covered_regions; i++) {
537 MemRegion mri = mr.intersection(_covered[i]);
538 if (mri.word_size() > 0) {
539 jbyte* cur_entry = byte_for(mri.last());
540 jbyte* limit = byte_for(mri.start());
541 while (cur_entry >= limit) {
542 jbyte* next_entry = cur_entry - 1;
543 if (*cur_entry != clean_card) {
544 size_t non_clean_cards = 1;
545 // Should the next card be included in this range of dirty cards.
546 while (next_entry >= limit && *next_entry != clean_card) {
547 non_clean_cards++;
548 cur_entry = next_entry;
549 next_entry--;
550 }
551 // The memory region may not be on a card boundary. So that
552 // objects beyond the end of the region are not processed, make
553 // cur_cards precise with regard to the end of the memory region.
554 MemRegion cur_cards(addr_for(cur_entry),
555 non_clean_cards * card_size_in_words);
556 MemRegion dirty_region = cur_cards.intersection(mri);
557 cl->do_MemRegion(dirty_region);
558 }
559 cur_entry = next_entry;
560 }
561 }
562 }
563 }
564
565 void CardTableModRefBS::dirty_MemRegion(MemRegion mr) {
566 assert((HeapWord*)align_size_down((uintptr_t)mr.start(), HeapWordSize) == mr.start(), "Unaligned start");
567 assert((HeapWord*)align_size_up ((uintptr_t)mr.end(), HeapWordSize) == mr.end(), "Unaligned end" );
568 jbyte* cur = byte_for(mr.start());
569 jbyte* last = byte_after(mr.last());
570 while (cur < last) {
571 *cur = dirty_card;
572 cur++;
573 }
574 }
575
576 void CardTableModRefBS::invalidate(MemRegion mr, bool whole_heap) {
577 assert((HeapWord*)align_size_down((uintptr_t)mr.start(), HeapWordSize) == mr.start(), "Unaligned start");
578 assert((HeapWord*)align_size_up ((uintptr_t)mr.end(), HeapWordSize) == mr.end(), "Unaligned end" );
579 for (int i = 0; i < _cur_covered_regions; i++) {
580 MemRegion mri = mr.intersection(_covered[i]);
581 if (!mri.is_empty()) dirty_MemRegion(mri);
582 }
583 }
584
585 void CardTableModRefBS::clear_MemRegion(MemRegion mr) {
586 // Be conservative: only clean cards entirely contained within the
587 // region.
588 jbyte* cur;
589 if (mr.start() == _whole_heap.start()) {
590 cur = byte_for(mr.start());
591 } else {
592 assert(mr.start() > _whole_heap.start(), "mr is not covered.");
593 cur = byte_after(mr.start() - 1);
594 }
595 jbyte* last = byte_after(mr.last());
596 memset(cur, clean_card, pointer_delta(last, cur, sizeof(jbyte)));
597 }
598
599 void CardTableModRefBS::clear(MemRegion mr) {
600 for (int i = 0; i < _cur_covered_regions; i++) {
601 MemRegion mri = mr.intersection(_covered[i]);
602 if (!mri.is_empty()) clear_MemRegion(mri);
603 }
604 }
605
606 void CardTableModRefBS::dirty(MemRegion mr) {
607 jbyte* first = byte_for(mr.start());
608 jbyte* last = byte_after(mr.last());
609 memset(first, dirty_card, last-first);
610 }
611
612 // Unlike several other card table methods, dirty_card_iterate()
613 // iterates over dirty cards ranges in increasing address order.
614 void CardTableModRefBS::dirty_card_iterate(MemRegion mr,
615 MemRegionClosure* cl) {
616 for (int i = 0; i < _cur_covered_regions; i++) {
617 MemRegion mri = mr.intersection(_covered[i]);
618 if (!mri.is_empty()) {
619 jbyte *cur_entry, *next_entry, *limit;
620 for (cur_entry = byte_for(mri.start()), limit = byte_for(mri.last());
621 cur_entry <= limit;
622 cur_entry = next_entry) {
623 next_entry = cur_entry + 1;
624 if (*cur_entry == dirty_card) {
625 size_t dirty_cards;
626 // Accumulate maximal dirty card range, starting at cur_entry
627 for (dirty_cards = 1;
628 next_entry <= limit && *next_entry == dirty_card;
629 dirty_cards++, next_entry++);
630 MemRegion cur_cards(addr_for(cur_entry),
631 dirty_cards*card_size_in_words);
632 cl->do_MemRegion(cur_cards);
633 }
634 }
635 }
636 }
637 }
638
639 MemRegion CardTableModRefBS::dirty_card_range_after_reset(MemRegion mr,
640 bool reset,
641 int reset_val) {
642 for (int i = 0; i < _cur_covered_regions; i++) {
643 MemRegion mri = mr.intersection(_covered[i]);
644 if (!mri.is_empty()) {
645 jbyte* cur_entry, *next_entry, *limit;
646 for (cur_entry = byte_for(mri.start()), limit = byte_for(mri.last());
647 cur_entry <= limit;
648 cur_entry = next_entry) {
649 next_entry = cur_entry + 1;
650 if (*cur_entry == dirty_card) {
651 size_t dirty_cards;
652 // Accumulate maximal dirty card range, starting at cur_entry
653 for (dirty_cards = 1;
654 next_entry <= limit && *next_entry == dirty_card;
655 dirty_cards++, next_entry++);
656 MemRegion cur_cards(addr_for(cur_entry),
657 dirty_cards*card_size_in_words);
658 if (reset) {
659 for (size_t i = 0; i < dirty_cards; i++) {
660 cur_entry[i] = reset_val;
661 }
662 }
663 return cur_cards;
664 }
665 }
666 }
667 }
668 return MemRegion(mr.end(), mr.end());
669 }
670
671 uintx CardTableModRefBS::ct_max_alignment_constraint() {
672 return card_size * os::vm_page_size();
673 }
674
675 void CardTableModRefBS::verify_guard() {
676 // For product build verification
677 guarantee(_byte_map[_guard_index] == last_card,
678 "card table guard has been modified");
679 }
680
681 void CardTableModRefBS::verify() {
682 verify_guard();
683 }
684
685 #ifndef PRODUCT
686 void CardTableModRefBS::verify_region(MemRegion mr,
687 jbyte val, bool val_equals) {
688 jbyte* start = byte_for(mr.start());
689 jbyte* end = byte_for(mr.last());
690 bool failures = false;
691 for (jbyte* curr = start; curr <= end; ++curr) {
692 jbyte curr_val = *curr;
693 bool failed = (val_equals) ? (curr_val != val) : (curr_val == val);
694 if (failed) {
695 if (!failures) {
696 tty->cr();
697 tty->print_cr("== CT verification failed: ["PTR_FORMAT","PTR_FORMAT"]", start, end);
698 tty->print_cr("== %sexpecting value: %d",
699 (val_equals) ? "" : "not ", val);
700 failures = true;
701 }
702 tty->print_cr("== card "PTR_FORMAT" ["PTR_FORMAT","PTR_FORMAT"], "
703 "val: %d", curr, addr_for(curr),
704 (HeapWord*) (((size_t) addr_for(curr)) + card_size),
705 (int) curr_val);
706 }
707 }
708 guarantee(!failures, "there should not have been any failures");
709 }
710
711 void CardTableModRefBS::verify_not_dirty_region(MemRegion mr) {
712 verify_region(mr, dirty_card, false /* val_equals */);
713 }
714
715 void CardTableModRefBS::verify_dirty_region(MemRegion mr) {
716 verify_region(mr, dirty_card, true /* val_equals */);
717 }
718 #endif
719
720 void CardTableModRefBS::print_on(outputStream* st) const {
721 st->print_cr("Card table byte_map: [" INTPTR_FORMAT "," INTPTR_FORMAT "] byte_map_base: " INTPTR_FORMAT,
722 _byte_map, _byte_map + _byte_map_size, byte_map_base);
723 }
724
725 bool CardTableModRefBSForCTRS::card_will_be_scanned(jbyte cv) {
726 return
727 CardTableModRefBS::card_will_be_scanned(cv) ||
728 _rs->is_prev_nonclean_card_val(cv);
729 };
730
731 bool CardTableModRefBSForCTRS::card_may_have_been_dirty(jbyte cv) {
732 return
733 cv != clean_card &&
734 (CardTableModRefBS::card_may_have_been_dirty(cv) ||
735 CardTableRS::youngergen_may_have_been_dirty(cv));
736 };