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