1 /*
2 * Copyright (c) 2000, 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 "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::compute_byte_map_size()
48 {
49 assert(_guard_index == cards_required(_whole_heap.word_size()) - 1,
50 "uninitialized, check declaration order");
51 assert(_page_size != 0, "uninitialized, check declaration order");
52 const size_t granularity = os::vm_allocation_granularity();
53 return align_size_up(_guard_index + 1, MAX2(_page_size, granularity));
54 }
55
56 CardTableModRefBS::CardTableModRefBS(MemRegion whole_heap,
57 int max_covered_regions):
58 ModRefBarrierSet(max_covered_regions),
59 _whole_heap(whole_heap),
60 _guard_index(0),
61 _guard_region(),
62 _last_valid_index(0),
63 _page_size(os::vm_page_size()),
64 _byte_map_size(0),
65 _covered(NULL),
66 _committed(NULL),
67 _cur_covered_regions(0),
68 _byte_map(NULL),
69 byte_map_base(NULL),
70 // LNC functionality
71 _lowest_non_clean(NULL),
72 _lowest_non_clean_chunk_size(NULL),
73 _lowest_non_clean_base_chunk_index(NULL),
74 _last_LNC_resizing_collection(NULL)
75 {
76 _kind = BarrierSet::CardTableModRef;
77
78 assert((uintptr_t(_whole_heap.start()) & (card_size - 1)) == 0, "heap must start at card boundary");
79 assert((uintptr_t(_whole_heap.end()) & (card_size - 1)) == 0, "heap must end at card boundary");
80
81 assert(card_size <= 512, "card_size must be less than 512"); // why?
82
83 _covered = new MemRegion[_max_covered_regions];
84 if (_covered == NULL) {
85 vm_exit_during_initialization("Could not allocate card table covered region set.");
86 }
87 }
88
89 void CardTableModRefBS::initialize() {
90 _guard_index = cards_required(_whole_heap.word_size()) - 1;
91 _last_valid_index = _guard_index - 1;
92
93 _byte_map_size = compute_byte_map_size();
94
95 HeapWord* low_bound = _whole_heap.start();
96 HeapWord* high_bound = _whole_heap.end();
97
98 _cur_covered_regions = 0;
99 _committed = new MemRegion[_max_covered_regions];
100 if (_committed == NULL) {
101 vm_exit_during_initialization("Could not allocate card table committed region set.");
102 }
103
104 const size_t rs_align = _page_size == (size_t) os::vm_page_size() ? 0 :
105 MAX2(_page_size, (size_t) os::vm_allocation_granularity());
106 ReservedSpace heap_rs(_byte_map_size, rs_align, false);
107
108 MemTracker::record_virtual_memory_type((address)heap_rs.base(), mtGC);
109
110 os::trace_page_sizes("card table", _guard_index + 1, _guard_index + 1,
111 _page_size, heap_rs.base(), heap_rs.size());
112 if (!heap_rs.is_reserved()) {
113 vm_exit_during_initialization("Could not reserve enough space for the "
114 "card marking array");
115 }
116
117 // The assembler store_check code will do an unsigned shift of the oop,
118 // then add it to byte_map_base, i.e.
119 //
120 // _byte_map = byte_map_base + (uintptr_t(low_bound) >> card_shift)
121 _byte_map = (jbyte*) heap_rs.base();
122 byte_map_base = _byte_map - (uintptr_t(low_bound) >> card_shift);
123 assert(byte_for(low_bound) == &_byte_map[0], "Checking start of map");
124 assert(byte_for(high_bound-1) <= &_byte_map[_last_valid_index], "Checking end of map");
125
126 jbyte* guard_card = &_byte_map[_guard_index];
127 uintptr_t guard_page = align_size_down((uintptr_t)guard_card, _page_size);
128 _guard_region = MemRegion((HeapWord*)guard_page, _page_size);
129 os::commit_memory_or_exit((char*)guard_page, _page_size, _page_size,
130 !ExecMem, "card table last card");
131 *guard_card = last_card;
132
133 _lowest_non_clean =
134 NEW_C_HEAP_ARRAY(CardArr, _max_covered_regions, mtGC);
135 _lowest_non_clean_chunk_size =
136 NEW_C_HEAP_ARRAY(size_t, _max_covered_regions, mtGC);
137 _lowest_non_clean_base_chunk_index =
138 NEW_C_HEAP_ARRAY(uintptr_t, _max_covered_regions, mtGC);
139 _last_LNC_resizing_collection =
140 NEW_C_HEAP_ARRAY(int, _max_covered_regions, mtGC);
141 if (_lowest_non_clean == NULL
142 || _lowest_non_clean_chunk_size == NULL
143 || _lowest_non_clean_base_chunk_index == NULL
144 || _last_LNC_resizing_collection == NULL)
145 vm_exit_during_initialization("couldn't allocate an LNC array.");
146 for (int i = 0; i < _max_covered_regions; i++) {
147 _lowest_non_clean[i] = NULL;
148 _lowest_non_clean_chunk_size[i] = 0;
149 _last_LNC_resizing_collection[i] = -1;
150 }
151
152 if (TraceCardTableModRefBS) {
153 gclog_or_tty->print_cr("CardTableModRefBS::CardTableModRefBS: ");
154 gclog_or_tty->print_cr(" "
155 " &_byte_map[0]: " INTPTR_FORMAT
156 " &_byte_map[_last_valid_index]: " INTPTR_FORMAT,
157 p2i(&_byte_map[0]),
158 p2i(&_byte_map[_last_valid_index]));
159 gclog_or_tty->print_cr(" "
160 " byte_map_base: " INTPTR_FORMAT,
161 p2i(byte_map_base));
162 }
163 }
164
165 CardTableModRefBS::~CardTableModRefBS() {
166 if (_covered) {
167 delete[] _covered;
168 _covered = NULL;
169 }
170 if (_committed) {
171 delete[] _committed;
172 _committed = NULL;
173 }
174 if (_lowest_non_clean) {
175 FREE_C_HEAP_ARRAY(CardArr, _lowest_non_clean, mtGC);
176 _lowest_non_clean = NULL;
177 }
178 if (_lowest_non_clean_chunk_size) {
179 FREE_C_HEAP_ARRAY(size_t, _lowest_non_clean_chunk_size, mtGC);
180 _lowest_non_clean_chunk_size = NULL;
181 }
182 if (_lowest_non_clean_base_chunk_index) {
183 FREE_C_HEAP_ARRAY(uintptr_t, _lowest_non_clean_base_chunk_index, mtGC);
184 _lowest_non_clean_base_chunk_index = NULL;
185 }
186 if (_last_LNC_resizing_collection) {
187 FREE_C_HEAP_ARRAY(int, _last_LNC_resizing_collection, mtGC);
188 _last_LNC_resizing_collection = NULL;
189 }
190 }
191
192 int CardTableModRefBS::find_covering_region_by_base(HeapWord* base) {
193 int i;
194 for (i = 0; i < _cur_covered_regions; i++) {
195 if (_covered[i].start() == base) return i;
196 if (_covered[i].start() > base) break;
197 }
198 // If we didn't find it, create a new one.
199 assert(_cur_covered_regions < _max_covered_regions,
200 "too many covered regions");
201 // Move the ones above up, to maintain sorted order.
202 for (int j = _cur_covered_regions; j > i; j--) {
203 _covered[j] = _covered[j-1];
204 _committed[j] = _committed[j-1];
205 }
206 int res = i;
207 _cur_covered_regions++;
208 _covered[res].set_start(base);
209 _covered[res].set_word_size(0);
210 jbyte* ct_start = byte_for(base);
211 uintptr_t ct_start_aligned = align_size_down((uintptr_t)ct_start, _page_size);
212 _committed[res].set_start((HeapWord*)ct_start_aligned);
213 _committed[res].set_word_size(0);
214 return res;
215 }
216
217 int CardTableModRefBS::find_covering_region_containing(HeapWord* addr) {
218 for (int i = 0; i < _cur_covered_regions; i++) {
219 if (_covered[i].contains(addr)) {
220 return i;
221 }
222 }
223 assert(0, "address outside of heap?");
224 return -1;
225 }
226
227 HeapWord* CardTableModRefBS::largest_prev_committed_end(int ind) const {
228 HeapWord* max_end = NULL;
229 for (int j = 0; j < ind; j++) {
230 HeapWord* this_end = _committed[j].end();
231 if (this_end > max_end) max_end = this_end;
232 }
233 return max_end;
234 }
235
236 MemRegion CardTableModRefBS::committed_unique_to_self(int self,
237 MemRegion mr) const {
238 MemRegion result = mr;
239 for (int r = 0; r < _cur_covered_regions; r += 1) {
240 if (r != self) {
241 result = result.minus(_committed[r]);
242 }
243 }
244 // Never include the guard page.
245 result = result.minus(_guard_region);
246 return result;
247 }
248
249 void CardTableModRefBS::resize_covered_region(MemRegion new_region) {
250 // We don't change the start of a region, only the end.
251 assert(_whole_heap.contains(new_region),
252 "attempt to cover area not in reserved area");
253 debug_only(verify_guard();)
254 // collided is true if the expansion would push into another committed region
255 debug_only(bool collided = false;)
256 int const ind = find_covering_region_by_base(new_region.start());
257 MemRegion const old_region = _covered[ind];
258 assert(old_region.start() == new_region.start(), "just checking");
259 if (new_region.word_size() != old_region.word_size()) {
260 // Commit new or uncommit old pages, if necessary.
261 MemRegion cur_committed = _committed[ind];
262 // Extend the end of this _committed region
263 // to cover the end of any lower _committed regions.
264 // This forms overlapping regions, but never interior regions.
265 HeapWord* const max_prev_end = largest_prev_committed_end(ind);
266 if (max_prev_end > cur_committed.end()) {
267 cur_committed.set_end(max_prev_end);
268 }
269 // Align the end up to a page size (starts are already aligned).
270 jbyte* const new_end = byte_after(new_region.last());
271 HeapWord* new_end_aligned =
272 (HeapWord*) align_size_up((uintptr_t)new_end, _page_size);
273 assert(new_end_aligned >= (HeapWord*) new_end,
274 "align up, but less");
275 // Check the other regions (excludes "ind") to ensure that
276 // the new_end_aligned does not intrude onto the committed
277 // space of another region.
278 int ri = 0;
279 for (ri = 0; ri < _cur_covered_regions; ri++) {
280 if (ri != ind) {
281 if (_committed[ri].contains(new_end_aligned)) {
282 // The prior check included in the assert
283 // (new_end_aligned >= _committed[ri].start())
284 // is redundant with the "contains" test.
285 // Any region containing the new end
286 // should start at or beyond the region found (ind)
287 // for the new end (committed regions are not expected to
288 // be proper subsets of other committed regions).
289 assert(_committed[ri].start() >= _committed[ind].start(),
290 "New end of committed region is inconsistent");
291 new_end_aligned = _committed[ri].start();
292 // new_end_aligned can be equal to the start of its
293 // committed region (i.e., of "ind") if a second
294 // region following "ind" also start at the same location
295 // as "ind".
296 assert(new_end_aligned >= _committed[ind].start(),
297 "New end of committed region is before start");
298 debug_only(collided = true;)
299 // Should only collide with 1 region
300 break;
301 }
302 }
303 }
304 #ifdef ASSERT
305 for (++ri; ri < _cur_covered_regions; ri++) {
306 assert(!_committed[ri].contains(new_end_aligned),
307 "New end of committed region is in a second committed region");
308 }
309 #endif
310 // The guard page is always committed and should not be committed over.
311 // "guarded" is used for assertion checking below and recalls the fact
312 // that the would-be end of the new committed region would have
313 // penetrated the guard page.
314 HeapWord* new_end_for_commit = new_end_aligned;
315
316 DEBUG_ONLY(bool guarded = false;)
317 if (new_end_for_commit > _guard_region.start()) {
318 new_end_for_commit = _guard_region.start();
319 DEBUG_ONLY(guarded = true;)
320 }
321
322 if (new_end_for_commit > cur_committed.end()) {
323 // Must commit new pages.
324 MemRegion const new_committed =
325 MemRegion(cur_committed.end(), new_end_for_commit);
326
327 assert(!new_committed.is_empty(), "Region should not be empty here");
328 os::commit_memory_or_exit((char*)new_committed.start(),
329 new_committed.byte_size(), _page_size,
330 !ExecMem, "card table expansion");
331 // Use new_end_aligned (as opposed to new_end_for_commit) because
332 // the cur_committed region may include the guard region.
333 } else if (new_end_aligned < cur_committed.end()) {
334 // Must uncommit pages.
335 MemRegion const uncommit_region =
336 committed_unique_to_self(ind, MemRegion(new_end_aligned,
337 cur_committed.end()));
338 if (!uncommit_region.is_empty()) {
339 // It is not safe to uncommit cards if the boundary between
340 // the generations is moving. A shrink can uncommit cards
341 // owned by generation A but being used by generation B.
342 if (!UseAdaptiveGCBoundary) {
343 if (!os::uncommit_memory((char*)uncommit_region.start(),
344 uncommit_region.byte_size())) {
345 assert(false, "Card table contraction failed");
346 // The call failed so don't change the end of the
347 // committed region. This is better than taking the
348 // VM down.
349 new_end_aligned = _committed[ind].end();
350 }
351 } else {
352 new_end_aligned = _committed[ind].end();
353 }
354 }
355 }
356 // In any case, we can reset the end of the current committed entry.
357 _committed[ind].set_end(new_end_aligned);
358
359 #ifdef ASSERT
360 // Check that the last card in the new region is committed according
361 // to the tables.
362 bool covered = false;
363 for (int cr = 0; cr < _cur_covered_regions; cr++) {
364 if (_committed[cr].contains(new_end - 1)) {
365 covered = true;
366 break;
367 }
368 }
369 assert(covered, "Card for end of new region not committed");
370 #endif
371
372 // The default of 0 is not necessarily clean cards.
373 jbyte* entry;
374 if (old_region.last() < _whole_heap.start()) {
375 entry = byte_for(_whole_heap.start());
376 } else {
377 entry = byte_after(old_region.last());
378 }
379 assert(index_for(new_region.last()) < _guard_index,
380 "The guard card will be overwritten");
381 // This line commented out cleans the newly expanded region and
382 // not the aligned up expanded region.
383 // jbyte* const end = byte_after(new_region.last());
384 jbyte* const end = (jbyte*) new_end_for_commit;
385 assert((end >= byte_after(new_region.last())) || collided || guarded,
386 "Expect to be beyond new region unless impacting another region");
387 // do nothing if we resized downward.
388 #ifdef ASSERT
389 for (int ri = 0; ri < _cur_covered_regions; ri++) {
390 if (ri != ind) {
391 // The end of the new committed region should not
392 // be in any existing region unless it matches
393 // the start of the next region.
394 assert(!_committed[ri].contains(end) ||
395 (_committed[ri].start() == (HeapWord*) end),
396 "Overlapping committed regions");
397 }
398 }
399 #endif
400 if (entry < end) {
401 memset(entry, clean_card, pointer_delta(end, entry, sizeof(jbyte)));
402 }
403 }
404 // In any case, the covered size changes.
405 _covered[ind].set_word_size(new_region.word_size());
406 if (TraceCardTableModRefBS) {
407 gclog_or_tty->print_cr("CardTableModRefBS::resize_covered_region: ");
408 gclog_or_tty->print_cr(" "
409 " _covered[%d].start(): " INTPTR_FORMAT
410 " _covered[%d].last(): " INTPTR_FORMAT,
411 ind, p2i(_covered[ind].start()),
412 ind, p2i(_covered[ind].last()));
413 gclog_or_tty->print_cr(" "
414 " _committed[%d].start(): " INTPTR_FORMAT
415 " _committed[%d].last(): " INTPTR_FORMAT,
416 ind, p2i(_committed[ind].start()),
417 ind, p2i(_committed[ind].last()));
418 gclog_or_tty->print_cr(" "
419 " byte_for(start): " INTPTR_FORMAT
420 " byte_for(last): " INTPTR_FORMAT,
421 p2i(byte_for(_covered[ind].start())),
422 p2i(byte_for(_covered[ind].last())));
423 gclog_or_tty->print_cr(" "
424 " addr_for(start): " INTPTR_FORMAT
425 " addr_for(last): " INTPTR_FORMAT,
426 p2i(addr_for((jbyte*) _committed[ind].start())),
427 p2i(addr_for((jbyte*) _committed[ind].last())));
428 }
429 // Touch the last card of the covered region to show that it
430 // is committed (or SEGV).
431 debug_only((void) (*byte_for(_covered[ind].last()));)
432 debug_only(verify_guard();)
433 }
434
435 // Note that these versions are precise! The scanning code has to handle the
436 // fact that the write barrier may be either precise or imprecise.
437
438 void CardTableModRefBS::write_ref_field_work(void* field, oop newVal, bool release) {
439 inline_write_ref_field(field, newVal, release);
440 }
441
442
443 void CardTableModRefBS::non_clean_card_iterate_possibly_parallel(Space* sp,
444 MemRegion mr,
445 OopsInGenClosure* cl,
446 CardTableRS* ct) {
447 if (!mr.is_empty()) {
448 // Caller (process_roots()) claims that all GC threads
449 // execute this call. With UseDynamicNumberOfGCThreads now all
450 // active GC threads execute this call. The number of active GC
451 // threads needs to be passed to par_non_clean_card_iterate_work()
452 // to get proper partitioning and termination.
453 //
454 // This is an example of where n_par_threads() is used instead
455 // of workers()->active_workers(). n_par_threads can be set to 0 to
456 // turn off parallelism. For example when this code is called as
457 // part of verification and SharedHeap::process_roots() is being
458 // used, then n_par_threads() may have been set to 0. active_workers
459 // is not overloaded with the meaning that it is a switch to disable
460 // parallelism and so keeps the meaning of the number of
461 // active gc workers. If parallelism has not been shut off by
462 // setting n_par_threads to 0, then n_par_threads should be
463 // equal to active_workers. When a different mechanism for shutting
464 // off parallelism is used, then active_workers can be used in
465 // place of n_par_threads.
466 // This is an example of a path where n_par_threads is
467 // set to 0 to turn off parallelism.
468 // [7] CardTableModRefBS::non_clean_card_iterate()
469 // [8] CardTableRS::younger_refs_in_space_iterate()
470 // [9] Generation::younger_refs_in_space_iterate()
471 // [10] OneContigSpaceCardGeneration::younger_refs_iterate()
472 // [11] CompactingPermGenGen::younger_refs_iterate()
473 // [12] CardTableRS::younger_refs_iterate()
474 // [13] SharedHeap::process_strong_roots()
475 // [14] G1CollectedHeap::verify()
476 // [15] Universe::verify()
477 // [16] G1CollectedHeap::do_collection_pause_at_safepoint()
478 //
479 int n_threads = SharedHeap::heap()->n_par_threads();
480 bool is_par = n_threads > 0;
481 if (is_par) {
482 #if INCLUDE_ALL_GCS
483 assert(SharedHeap::heap()->n_par_threads() ==
484 SharedHeap::heap()->workers()->active_workers(), "Mismatch");
485 non_clean_card_iterate_parallel_work(sp, mr, cl, ct, n_threads);
486 #else // INCLUDE_ALL_GCS
487 fatal("Parallel gc not supported here.");
488 #endif // INCLUDE_ALL_GCS
489 } else {
490 // We do not call the non_clean_card_iterate_serial() version below because
491 // we want to clear the cards (which non_clean_card_iterate_serial() does not
492 // do for us): clear_cl here does the work of finding contiguous dirty ranges
493 // of cards to process and clear.
494
495 DirtyCardToOopClosure* dcto_cl = sp->new_dcto_cl(cl, precision(),
496 cl->gen_boundary());
497 ClearNoncleanCardWrapper clear_cl(dcto_cl, ct);
498
499 clear_cl.do_MemRegion(mr);
500 }
501 }
502 }
503
504 // The iterator itself is not MT-aware, but
505 // MT-aware callers and closures can use this to
506 // accomplish dirty card iteration in parallel. The
507 // iterator itself does not clear the dirty cards, or
508 // change their values in any manner.
509 void CardTableModRefBS::non_clean_card_iterate_serial(MemRegion mr,
510 MemRegionClosure* cl) {
511 bool is_par = (SharedHeap::heap()->n_par_threads() > 0);
512 assert(!is_par ||
513 (SharedHeap::heap()->n_par_threads() ==
514 SharedHeap::heap()->workers()->active_workers()), "Mismatch");
515 for (int i = 0; i < _cur_covered_regions; i++) {
516 MemRegion mri = mr.intersection(_covered[i]);
517 if (mri.word_size() > 0) {
518 jbyte* cur_entry = byte_for(mri.last());
519 jbyte* limit = byte_for(mri.start());
520 while (cur_entry >= limit) {
521 jbyte* next_entry = cur_entry - 1;
522 if (*cur_entry != clean_card) {
523 size_t non_clean_cards = 1;
524 // Should the next card be included in this range of dirty cards.
525 while (next_entry >= limit && *next_entry != clean_card) {
526 non_clean_cards++;
527 cur_entry = next_entry;
528 next_entry--;
529 }
530 // The memory region may not be on a card boundary. So that
531 // objects beyond the end of the region are not processed, make
532 // cur_cards precise with regard to the end of the memory region.
533 MemRegion cur_cards(addr_for(cur_entry),
534 non_clean_cards * card_size_in_words);
535 MemRegion dirty_region = cur_cards.intersection(mri);
536 cl->do_MemRegion(dirty_region);
537 }
538 cur_entry = next_entry;
539 }
540 }
541 }
542 }
543
544 void CardTableModRefBS::dirty_MemRegion(MemRegion mr) {
545 assert((HeapWord*)align_size_down((uintptr_t)mr.start(), HeapWordSize) == mr.start(), "Unaligned start");
546 assert((HeapWord*)align_size_up ((uintptr_t)mr.end(), HeapWordSize) == mr.end(), "Unaligned end" );
547 jbyte* cur = byte_for(mr.start());
548 jbyte* last = byte_after(mr.last());
549 while (cur < last) {
550 *cur = dirty_card;
551 cur++;
552 }
553 }
554
555 void CardTableModRefBS::invalidate(MemRegion mr, bool whole_heap) {
556 assert((HeapWord*)align_size_down((uintptr_t)mr.start(), HeapWordSize) == mr.start(), "Unaligned start");
557 assert((HeapWord*)align_size_up ((uintptr_t)mr.end(), HeapWordSize) == mr.end(), "Unaligned end" );
558 for (int i = 0; i < _cur_covered_regions; i++) {
559 MemRegion mri = mr.intersection(_covered[i]);
560 if (!mri.is_empty()) dirty_MemRegion(mri);
561 }
562 }
563
564 void CardTableModRefBS::clear_MemRegion(MemRegion mr) {
565 // Be conservative: only clean cards entirely contained within the
566 // region.
567 jbyte* cur;
568 if (mr.start() == _whole_heap.start()) {
569 cur = byte_for(mr.start());
570 } else {
571 assert(mr.start() > _whole_heap.start(), "mr is not covered.");
572 cur = byte_after(mr.start() - 1);
573 }
574 jbyte* last = byte_after(mr.last());
575 memset(cur, clean_card, pointer_delta(last, cur, sizeof(jbyte)));
576 }
577
578 void CardTableModRefBS::clear(MemRegion mr) {
579 for (int i = 0; i < _cur_covered_regions; i++) {
580 MemRegion mri = mr.intersection(_covered[i]);
581 if (!mri.is_empty()) clear_MemRegion(mri);
582 }
583 }
584
585 void CardTableModRefBS::dirty(MemRegion mr) {
586 jbyte* first = byte_for(mr.start());
587 jbyte* last = byte_after(mr.last());
588 memset(first, dirty_card, last-first);
589 }
590
591 // Unlike several other card table methods, dirty_card_iterate()
592 // iterates over dirty cards ranges in increasing address order.
593 void CardTableModRefBS::dirty_card_iterate(MemRegion mr,
594 MemRegionClosure* cl) {
595 for (int i = 0; i < _cur_covered_regions; i++) {
596 MemRegion mri = mr.intersection(_covered[i]);
597 if (!mri.is_empty()) {
598 jbyte *cur_entry, *next_entry, *limit;
599 for (cur_entry = byte_for(mri.start()), limit = byte_for(mri.last());
600 cur_entry <= limit;
601 cur_entry = next_entry) {
602 next_entry = cur_entry + 1;
603 if (*cur_entry == dirty_card) {
604 size_t dirty_cards;
605 // Accumulate maximal dirty card range, starting at cur_entry
606 for (dirty_cards = 1;
607 next_entry <= limit && *next_entry == dirty_card;
608 dirty_cards++, next_entry++);
609 MemRegion cur_cards(addr_for(cur_entry),
610 dirty_cards*card_size_in_words);
611 cl->do_MemRegion(cur_cards);
612 }
613 }
614 }
615 }
616 }
617
618 MemRegion CardTableModRefBS::dirty_card_range_after_reset(MemRegion mr,
619 bool reset,
620 int reset_val) {
621 for (int i = 0; i < _cur_covered_regions; i++) {
622 MemRegion mri = mr.intersection(_covered[i]);
623 if (!mri.is_empty()) {
624 jbyte* cur_entry, *next_entry, *limit;
625 for (cur_entry = byte_for(mri.start()), limit = byte_for(mri.last());
626 cur_entry <= limit;
627 cur_entry = next_entry) {
628 next_entry = cur_entry + 1;
629 if (*cur_entry == dirty_card) {
630 size_t dirty_cards;
631 // Accumulate maximal dirty card range, starting at cur_entry
632 for (dirty_cards = 1;
633 next_entry <= limit && *next_entry == dirty_card;
634 dirty_cards++, next_entry++);
635 MemRegion cur_cards(addr_for(cur_entry),
636 dirty_cards*card_size_in_words);
637 if (reset) {
638 for (size_t i = 0; i < dirty_cards; i++) {
639 cur_entry[i] = reset_val;
640 }
641 }
642 return cur_cards;
643 }
644 }
645 }
646 }
647 return MemRegion(mr.end(), mr.end());
648 }
649
650 uintx CardTableModRefBS::ct_max_alignment_constraint() {
651 return card_size * os::vm_page_size();
652 }
653
654 void CardTableModRefBS::verify_guard() {
655 // For product build verification
656 guarantee(_byte_map[_guard_index] == last_card,
657 "card table guard has been modified");
658 }
659
660 void CardTableModRefBS::verify() {
661 verify_guard();
662 }
663
664 #ifndef PRODUCT
665 void CardTableModRefBS::verify_region(MemRegion mr,
666 jbyte val, bool val_equals) {
667 jbyte* start = byte_for(mr.start());
668 jbyte* end = byte_for(mr.last());
669 bool failures = false;
670 for (jbyte* curr = start; curr <= end; ++curr) {
671 jbyte curr_val = *curr;
672 bool failed = (val_equals) ? (curr_val != val) : (curr_val == val);
673 if (failed) {
674 if (!failures) {
675 tty->cr();
676 tty->print_cr("== CT verification failed: [" INTPTR_FORMAT "," INTPTR_FORMAT "]", p2i(start), p2i(end));
677 tty->print_cr("== %sexpecting value: %d",
678 (val_equals) ? "" : "not ", val);
679 failures = true;
680 }
681 tty->print_cr("== card "PTR_FORMAT" ["PTR_FORMAT","PTR_FORMAT"], "
682 "val: %d", p2i(curr), p2i(addr_for(curr)),
683 p2i((HeapWord*) (((size_t) addr_for(curr)) + card_size)),
684 (int) curr_val);
685 }
686 }
687 guarantee(!failures, "there should not have been any failures");
688 }
689
690 void CardTableModRefBS::verify_not_dirty_region(MemRegion mr) {
691 verify_region(mr, dirty_card, false /* val_equals */);
692 }
693
694 void CardTableModRefBS::verify_dirty_region(MemRegion mr) {
695 verify_region(mr, dirty_card, true /* val_equals */);
696 }
697 #endif
698
699 void CardTableModRefBS::print_on(outputStream* st) const {
700 st->print_cr("Card table byte_map: [" INTPTR_FORMAT "," INTPTR_FORMAT "] byte_map_base: " INTPTR_FORMAT,
701 p2i(_byte_map), p2i(_byte_map + _byte_map_size), p2i(byte_map_base));
702 }
703
704 bool CardTableModRefBSForCTRS::card_will_be_scanned(jbyte cv) {
705 return
706 CardTableModRefBS::card_will_be_scanned(cv) ||
707 _rs->is_prev_nonclean_card_val(cv);
708 };
709
710 bool CardTableModRefBSForCTRS::card_may_have_been_dirty(jbyte cv) {
711 return
712 cv != clean_card &&
713 (CardTableModRefBS::card_may_have_been_dirty(cv) ||
714 CardTableRS::youngergen_may_have_been_dirty(cv));
715 };