1 /*
2 * Copyright (c) 2001, 2009, 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.
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23 */
24
25 # include "incls/_precompiled.incl"
26 # include "incls/_cardTableRS.cpp.incl"
27
28 CardTableRS::CardTableRS(MemRegion whole_heap,
29 int max_covered_regions) :
30 GenRemSet(),
31 _cur_youngergen_card_val(youngergenP1_card),
32 _regions_to_iterate(max_covered_regions - 1)
33 {
34 #ifndef SERIALGC
35 if (UseG1GC) {
36 _ct_bs = new G1SATBCardTableLoggingModRefBS(whole_heap,
37 max_covered_regions);
38 } else {
39 _ct_bs = new CardTableModRefBSForCTRS(whole_heap, max_covered_regions);
40 }
41 #else
42 _ct_bs = new CardTableModRefBSForCTRS(whole_heap, max_covered_regions);
43 #endif
44 set_bs(_ct_bs);
45 _last_cur_val_in_gen = new jbyte[GenCollectedHeap::max_gens + 1];
46 if (_last_cur_val_in_gen == NULL) {
47 vm_exit_during_initialization("Could not last_cur_val_in_gen array.");
48 }
49 for (int i = 0; i < GenCollectedHeap::max_gens + 1; i++) {
50 _last_cur_val_in_gen[i] = clean_card_val();
51 }
52 _ct_bs->set_CTRS(this);
53 }
54
55 void CardTableRS::resize_covered_region(MemRegion new_region) {
56 _ct_bs->resize_covered_region(new_region);
57 }
58
59 jbyte CardTableRS::find_unused_youngergenP_card_value() {
60 for (jbyte v = youngergenP1_card;
61 v < cur_youngergen_and_prev_nonclean_card;
62 v++) {
63 bool seen = false;
64 for (int g = 0; g < _regions_to_iterate; g++) {
65 if (_last_cur_val_in_gen[g] == v) {
66 seen = true;
67 break;
68 }
69 }
70 if (!seen) return v;
71 }
72 ShouldNotReachHere();
73 return 0;
74 }
75
76 void CardTableRS::prepare_for_younger_refs_iterate(bool parallel) {
77 // Parallel or sequential, we must always set the prev to equal the
78 // last one written.
79 if (parallel) {
80 // Find a parallel value to be used next.
81 jbyte next_val = find_unused_youngergenP_card_value();
82 set_cur_youngergen_card_val(next_val);
83
84 } else {
85 // In an sequential traversal we will always write youngergen, so that
86 // the inline barrier is correct.
87 set_cur_youngergen_card_val(youngergen_card);
88 }
89 }
90
91 void CardTableRS::younger_refs_iterate(Generation* g,
92 OopsInGenClosure* blk) {
93 _last_cur_val_in_gen[g->level()+1] = cur_youngergen_card_val();
94 g->younger_refs_iterate(blk);
95 }
96
97 class ClearNoncleanCardWrapper: public MemRegionClosure {
98 MemRegionClosure* _dirty_card_closure;
99 CardTableRS* _ct;
100 bool _is_par;
101 private:
102 // Clears the given card, return true if the corresponding card should be
103 // processed.
104 bool clear_card(jbyte* entry) {
105 if (_is_par) {
106 while (true) {
107 // In the parallel case, we may have to do this several times.
108 jbyte entry_val = *entry;
109 assert(entry_val != CardTableRS::clean_card_val(),
110 "We shouldn't be looking at clean cards, and this should "
111 "be the only place they get cleaned.");
112 if (CardTableRS::card_is_dirty_wrt_gen_iter(entry_val)
113 || _ct->is_prev_youngergen_card_val(entry_val)) {
114 jbyte res =
115 Atomic::cmpxchg(CardTableRS::clean_card_val(), entry, entry_val);
116 if (res == entry_val) {
117 break;
118 } else {
119 assert(res == CardTableRS::cur_youngergen_and_prev_nonclean_card,
120 "The CAS above should only fail if another thread did "
121 "a GC write barrier.");
122 }
123 } else if (entry_val ==
124 CardTableRS::cur_youngergen_and_prev_nonclean_card) {
125 // Parallelism shouldn't matter in this case. Only the thread
126 // assigned to scan the card should change this value.
127 *entry = _ct->cur_youngergen_card_val();
128 break;
129 } else {
130 assert(entry_val == _ct->cur_youngergen_card_val(),
131 "Should be the only possibility.");
132 // In this case, the card was clean before, and become
133 // cur_youngergen only because of processing of a promoted object.
134 // We don't have to look at the card.
135 return false;
136 }
137 }
138 return true;
139 } else {
140 jbyte entry_val = *entry;
141 assert(entry_val != CardTableRS::clean_card_val(),
142 "We shouldn't be looking at clean cards, and this should "
143 "be the only place they get cleaned.");
144 assert(entry_val != CardTableRS::cur_youngergen_and_prev_nonclean_card,
145 "This should be possible in the sequential case.");
146 *entry = CardTableRS::clean_card_val();
147 return true;
148 }
149 }
150
151 public:
152 ClearNoncleanCardWrapper(MemRegionClosure* dirty_card_closure,
153 CardTableRS* ct) :
154 _dirty_card_closure(dirty_card_closure), _ct(ct) {
155 _is_par = (SharedHeap::heap()->n_par_threads() > 0);
156 }
157 void do_MemRegion(MemRegion mr) {
158 // We start at the high end of "mr", walking backwards
159 // while accumulating a contiguous dirty range of cards in
160 // [start_of_non_clean, end_of_non_clean) which we then
161 // process en masse.
162 HeapWord* end_of_non_clean = mr.end();
163 HeapWord* start_of_non_clean = end_of_non_clean;
164 jbyte* entry = _ct->byte_for(mr.last());
165 const jbyte* first_entry = _ct->byte_for(mr.start());
166 while (entry >= first_entry) {
167 HeapWord* cur = _ct->addr_for(entry);
168 if (!clear_card(entry)) {
169 // We hit a clean card; process any non-empty
170 // dirty range accumulated so far.
171 if (start_of_non_clean < end_of_non_clean) {
172 MemRegion mr2(start_of_non_clean, end_of_non_clean);
173 _dirty_card_closure->do_MemRegion(mr2);
174 }
175 // Reset the dirty window while continuing to
176 // look for the next dirty window to process.
177 end_of_non_clean = cur;
178 start_of_non_clean = end_of_non_clean;
179 }
180 // Open the left end of the window one card to the left.
181 start_of_non_clean = cur;
182 // Note that "entry" leads "start_of_non_clean" in
183 // its leftward excursion after this point
184 // in the loop and, when we hit the left end of "mr",
185 // will point off of the left end of the card-table
186 // for "mr".
187 entry--;
188 }
189 // If the first card of "mr" was dirty, we will have
190 // been left with a dirty window, co-initial with "mr",
191 // which we now process.
192 if (start_of_non_clean < end_of_non_clean) {
193 MemRegion mr2(start_of_non_clean, end_of_non_clean);
194 _dirty_card_closure->do_MemRegion(mr2);
195 }
196 }
197 };
198 // clean (by dirty->clean before) ==> cur_younger_gen
199 // dirty ==> cur_youngergen_and_prev_nonclean_card
200 // precleaned ==> cur_youngergen_and_prev_nonclean_card
201 // prev-younger-gen ==> cur_youngergen_and_prev_nonclean_card
202 // cur-younger-gen ==> cur_younger_gen
203 // cur_youngergen_and_prev_nonclean_card ==> no change.
204 void CardTableRS::write_ref_field_gc_par(void* field, oop new_val) {
205 jbyte* entry = ct_bs()->byte_for(field);
206 do {
207 jbyte entry_val = *entry;
208 // We put this first because it's probably the most common case.
209 if (entry_val == clean_card_val()) {
210 // No threat of contention with cleaning threads.
211 *entry = cur_youngergen_card_val();
212 return;
213 } else if (card_is_dirty_wrt_gen_iter(entry_val)
214 || is_prev_youngergen_card_val(entry_val)) {
215 // Mark it as both cur and prev youngergen; card cleaning thread will
216 // eventually remove the previous stuff.
217 jbyte new_val = cur_youngergen_and_prev_nonclean_card;
218 jbyte res = Atomic::cmpxchg(new_val, entry, entry_val);
219 // Did the CAS succeed?
220 if (res == entry_val) return;
221 // Otherwise, retry, to see the new value.
222 continue;
223 } else {
224 assert(entry_val == cur_youngergen_and_prev_nonclean_card
225 || entry_val == cur_youngergen_card_val(),
226 "should be only possibilities.");
227 return;
228 }
229 } while (true);
230 }
231
232 void CardTableRS::younger_refs_in_space_iterate(Space* sp,
233 OopsInGenClosure* cl) {
234 DirtyCardToOopClosure* dcto_cl = sp->new_dcto_cl(cl, _ct_bs->precision(),
235 cl->gen_boundary());
236 ClearNoncleanCardWrapper clear_cl(dcto_cl, this);
237
238 _ct_bs->non_clean_card_iterate(sp, sp->used_region_at_save_marks(),
239 dcto_cl, &clear_cl, false);
240 }
241
242 void CardTableRS::clear_into_younger(Generation* gen, bool clear_perm) {
243 GenCollectedHeap* gch = GenCollectedHeap::heap();
244 // Generations younger than gen have been evacuated. We can clear
245 // card table entries for gen (we know that it has no pointers
246 // to younger gens) and for those below. The card tables for
247 // the youngest gen need never be cleared, and those for perm gen
248 // will be cleared based on the parameter clear_perm.
249 // There's a bit of subtlety in the clear() and invalidate()
250 // methods that we exploit here and in invalidate_or_clear()
251 // below to avoid missing cards at the fringes. If clear() or
252 // invalidate() are changed in the future, this code should
253 // be revisited. 20040107.ysr
254 Generation* g = gen;
255 for(Generation* prev_gen = gch->prev_gen(g);
256 prev_gen != NULL;
257 g = prev_gen, prev_gen = gch->prev_gen(g)) {
258 MemRegion to_be_cleared_mr = g->prev_used_region();
259 clear(to_be_cleared_mr);
260 }
261 // Clear perm gen cards if asked to do so.
262 if (clear_perm) {
263 MemRegion to_be_cleared_mr = gch->perm_gen()->prev_used_region();
264 clear(to_be_cleared_mr);
265 }
266 }
267
268 void CardTableRS::invalidate_or_clear(Generation* gen, bool younger,
269 bool perm) {
270 GenCollectedHeap* gch = GenCollectedHeap::heap();
271 // For each generation gen (and younger and/or perm)
272 // invalidate the cards for the currently occupied part
273 // of that generation and clear the cards for the
274 // unoccupied part of the generation (if any, making use
275 // of that generation's prev_used_region to determine that
276 // region). No need to do anything for the youngest
277 // generation. Also see note#20040107.ysr above.
278 Generation* g = gen;
279 for(Generation* prev_gen = gch->prev_gen(g); prev_gen != NULL;
280 g = prev_gen, prev_gen = gch->prev_gen(g)) {
281 MemRegion used_mr = g->used_region();
282 MemRegion to_be_cleared_mr = g->prev_used_region().minus(used_mr);
283 if (!to_be_cleared_mr.is_empty()) {
284 clear(to_be_cleared_mr);
285 }
286 invalidate(used_mr);
287 if (!younger) break;
288 }
289 // Clear perm gen cards if asked to do so.
290 if (perm) {
291 g = gch->perm_gen();
292 MemRegion used_mr = g->used_region();
293 MemRegion to_be_cleared_mr = g->prev_used_region().minus(used_mr);
294 if (!to_be_cleared_mr.is_empty()) {
295 clear(to_be_cleared_mr);
296 }
297 invalidate(used_mr);
298 }
299 }
300
301
302 class VerifyCleanCardClosure: public OopClosure {
303 private:
304 HeapWord* _boundary;
305 HeapWord* _begin;
306 HeapWord* _end;
307 protected:
308 template <class T> void do_oop_work(T* p) {
309 HeapWord* jp = (HeapWord*)p;
310 if (jp >= _begin && jp < _end) {
311 oop obj = oopDesc::load_decode_heap_oop(p);
312 guarantee(obj == NULL ||
313 (HeapWord*)p < _boundary ||
314 (HeapWord*)obj >= _boundary,
315 "pointer on clean card crosses boundary");
316 }
317 }
318 public:
319 VerifyCleanCardClosure(HeapWord* b, HeapWord* begin, HeapWord* end) :
320 _boundary(b), _begin(begin), _end(end) {}
321 virtual void do_oop(oop* p) { VerifyCleanCardClosure::do_oop_work(p); }
322 virtual void do_oop(narrowOop* p) { VerifyCleanCardClosure::do_oop_work(p); }
323 };
324
325 class VerifyCTSpaceClosure: public SpaceClosure {
326 private:
327 CardTableRS* _ct;
328 HeapWord* _boundary;
329 public:
330 VerifyCTSpaceClosure(CardTableRS* ct, HeapWord* boundary) :
331 _ct(ct), _boundary(boundary) {}
332 virtual void do_space(Space* s) { _ct->verify_space(s, _boundary); }
333 };
334
335 class VerifyCTGenClosure: public GenCollectedHeap::GenClosure {
336 CardTableRS* _ct;
337 public:
338 VerifyCTGenClosure(CardTableRS* ct) : _ct(ct) {}
339 void do_generation(Generation* gen) {
340 // Skip the youngest generation.
341 if (gen->level() == 0) return;
342 // Normally, we're interested in pointers to younger generations.
343 VerifyCTSpaceClosure blk(_ct, gen->reserved().start());
344 gen->space_iterate(&blk, true);
345 }
346 };
347
348 void CardTableRS::verify_space(Space* s, HeapWord* gen_boundary) {
349 // We don't need to do young-gen spaces.
350 if (s->end() <= gen_boundary) return;
351 MemRegion used = s->used_region();
352
353 jbyte* cur_entry = byte_for(used.start());
354 jbyte* limit = byte_after(used.last());
355 while (cur_entry < limit) {
356 if (*cur_entry == CardTableModRefBS::clean_card) {
357 jbyte* first_dirty = cur_entry+1;
358 while (first_dirty < limit &&
359 *first_dirty == CardTableModRefBS::clean_card) {
360 first_dirty++;
361 }
362 // If the first object is a regular object, and it has a
363 // young-to-old field, that would mark the previous card.
364 HeapWord* boundary = addr_for(cur_entry);
365 HeapWord* end = (first_dirty >= limit) ? used.end() : addr_for(first_dirty);
366 HeapWord* boundary_block = s->block_start(boundary);
367 HeapWord* begin = boundary; // Until proven otherwise.
368 HeapWord* start_block = boundary_block; // Until proven otherwise.
369 if (boundary_block < boundary) {
370 if (s->block_is_obj(boundary_block) && s->obj_is_alive(boundary_block)) {
371 oop boundary_obj = oop(boundary_block);
372 if (!boundary_obj->is_objArray() &&
373 !boundary_obj->is_typeArray()) {
374 guarantee(cur_entry > byte_for(used.start()),
375 "else boundary would be boundary_block");
376 if (*byte_for(boundary_block) != CardTableModRefBS::clean_card) {
377 begin = boundary_block + s->block_size(boundary_block);
378 start_block = begin;
379 }
380 }
381 }
382 }
383 // Now traverse objects until end.
384 HeapWord* cur = start_block;
385 VerifyCleanCardClosure verify_blk(gen_boundary, begin, end);
386 while (cur < end) {
387 if (s->block_is_obj(cur) && s->obj_is_alive(cur)) {
388 oop(cur)->oop_iterate(&verify_blk);
389 }
390 cur += s->block_size(cur);
391 }
392 cur_entry = first_dirty;
393 } else {
394 // We'd normally expect that cur_youngergen_and_prev_nonclean_card
395 // is a transient value, that cannot be in the card table
396 // except during GC, and thus assert that:
397 // guarantee(*cur_entry != cur_youngergen_and_prev_nonclean_card,
398 // "Illegal CT value");
399 // That however, need not hold, as will become clear in the
400 // following...
401
402 // We'd normally expect that if we are in the parallel case,
403 // we can't have left a prev value (which would be different
404 // from the current value) in the card table, and so we'd like to
405 // assert that:
406 // guarantee(cur_youngergen_card_val() == youngergen_card
407 // || !is_prev_youngergen_card_val(*cur_entry),
408 // "Illegal CT value");
409 // That, however, may not hold occasionally, because of
410 // CMS or MSC in the old gen. To wit, consider the
411 // following two simple illustrative scenarios:
412 // (a) CMS: Consider the case where a large object L
413 // spanning several cards is allocated in the old
414 // gen, and has a young gen reference stored in it, dirtying
415 // some interior cards. A young collection scans the card,
416 // finds a young ref and installs a youngergenP_n value.
417 // L then goes dead. Now a CMS collection starts,
418 // finds L dead and sweeps it up. Assume that L is
419 // abutting _unallocated_blk, so _unallocated_blk is
420 // adjusted down to (below) L. Assume further that
421 // no young collection intervenes during this CMS cycle.
422 // The next young gen cycle will not get to look at this
423 // youngergenP_n card since it lies in the unoccupied
424 // part of the space.
425 // Some young collections later the blocks on this
426 // card can be re-allocated either due to direct allocation
427 // or due to absorbing promotions. At this time, the
428 // before-gc verification will fail the above assert.
429 // (b) MSC: In this case, an object L with a young reference
430 // is on a card that (therefore) holds a youngergen_n value.
431 // Suppose also that L lies towards the end of the used
432 // the used space before GC. An MSC collection
433 // occurs that compacts to such an extent that this
434 // card is no longer in the occupied part of the space.
435 // Since current code in MSC does not always clear cards
436 // in the unused part of old gen, this stale youngergen_n
437 // value is left behind and can later be covered by
438 // an object when promotion or direct allocation
439 // re-allocates that part of the heap.
440 //
441 // Fortunately, the presence of such stale card values is
442 // "only" a minor annoyance in that subsequent young collections
443 // might needlessly scan such cards, but would still never corrupt
444 // the heap as a result. However, it's likely not to be a significant
445 // performance inhibitor in practice. For instance,
446 // some recent measurements with unoccupied cards eagerly cleared
447 // out to maintain this invariant, showed next to no
448 // change in young collection times; of course one can construct
449 // degenerate examples where the cost can be significant.)
450 // Note, in particular, that if the "stale" card is modified
451 // after re-allocation, it would be dirty, not "stale". Thus,
452 // we can never have a younger ref in such a card and it is
453 // safe not to scan that card in any collection. [As we see
454 // below, we do some unnecessary scanning
455 // in some cases in the current parallel scanning algorithm.]
456 //
457 // The main point below is that the parallel card scanning code
458 // deals correctly with these stale card values. There are two main
459 // cases to consider where we have a stale "younger gen" value and a
460 // "derivative" case to consider, where we have a stale
461 // "cur_younger_gen_and_prev_non_clean" value, as will become
462 // apparent in the case analysis below.
463 // o Case 1. If the stale value corresponds to a younger_gen_n
464 // value other than the cur_younger_gen value then the code
465 // treats this as being tantamount to a prev_younger_gen
466 // card. This means that the card may be unnecessarily scanned.
467 // There are two sub-cases to consider:
468 // o Case 1a. Let us say that the card is in the occupied part
469 // of the generation at the time the collection begins. In
470 // that case the card will be either cleared when it is scanned
471 // for young pointers, or will be set to cur_younger_gen as a
472 // result of promotion. (We have elided the normal case where
473 // the scanning thread and the promoting thread interleave
474 // possibly resulting in a transient
475 // cur_younger_gen_and_prev_non_clean value before settling
476 // to cur_younger_gen. [End Case 1a.]
477 // o Case 1b. Consider now the case when the card is in the unoccupied
478 // part of the space which becomes occupied because of promotions
479 // into it during the current young GC. In this case the card
480 // will never be scanned for young references. The current
481 // code will set the card value to either
482 // cur_younger_gen_and_prev_non_clean or leave
483 // it with its stale value -- because the promotions didn't
484 // result in any younger refs on that card. Of these two
485 // cases, the latter will be covered in Case 1a during
486 // a subsequent scan. To deal with the former case, we need
487 // to further consider how we deal with a stale value of
488 // cur_younger_gen_and_prev_non_clean in our case analysis
489 // below. This we do in Case 3 below. [End Case 1b]
490 // [End Case 1]
491 // o Case 2. If the stale value corresponds to cur_younger_gen being
492 // a value not necessarily written by a current promotion, the
493 // card will not be scanned by the younger refs scanning code.
494 // (This is OK since as we argued above such cards cannot contain
495 // any younger refs.) The result is that this value will be
496 // treated as a prev_younger_gen value in a subsequent collection,
497 // which is addressed in Case 1 above. [End Case 2]
498 // o Case 3. We here consider the "derivative" case from Case 1b. above
499 // because of which we may find a stale
500 // cur_younger_gen_and_prev_non_clean card value in the table.
501 // Once again, as in Case 1, we consider two subcases, depending
502 // on whether the card lies in the occupied or unoccupied part
503 // of the space at the start of the young collection.
504 // o Case 3a. Let us say the card is in the occupied part of
505 // the old gen at the start of the young collection. In that
506 // case, the card will be scanned by the younger refs scanning
507 // code which will set it to cur_younger_gen. In a subsequent
508 // scan, the card will be considered again and get its final
509 // correct value. [End Case 3a]
510 // o Case 3b. Now consider the case where the card is in the
511 // unoccupied part of the old gen, and is occupied as a result
512 // of promotions during thus young gc. In that case,
513 // the card will not be scanned for younger refs. The presence
514 // of newly promoted objects on the card will then result in
515 // its keeping the value cur_younger_gen_and_prev_non_clean
516 // value, which we have dealt with in Case 3 here. [End Case 3b]
517 // [End Case 3]
518 //
519 // (Please refer to the code in the helper class
520 // ClearNonCleanCardWrapper and in CardTableModRefBS for details.)
521 //
522 // The informal arguments above can be tightened into a formal
523 // correctness proof and it behooves us to write up such a proof,
524 // or to use model checking to prove that there are no lingering
525 // concerns.
526 //
527 // Clearly because of Case 3b one cannot bound the time for
528 // which a card will retain what we have called a "stale" value.
529 // However, one can obtain a Loose upper bound on the redundant
530 // work as a result of such stale values. Note first that any
531 // time a stale card lies in the occupied part of the space at
532 // the start of the collection, it is scanned by younger refs
533 // code and we can define a rank function on card values that
534 // declines when this is so. Note also that when a card does not
535 // lie in the occupied part of the space at the beginning of a
536 // young collection, its rank can either decline or stay unchanged.
537 // In this case, no extra work is done in terms of redundant
538 // younger refs scanning of that card.
539 // Then, the case analysis above reveals that, in the worst case,
540 // any such stale card will be scanned unnecessarily at most twice.
541 //
542 // It is nonethelss advisable to try and get rid of some of this
543 // redundant work in a subsequent (low priority) re-design of
544 // the card-scanning code, if only to simplify the underlying
545 // state machine analysis/proof. ysr 1/28/2002. XXX
546 cur_entry++;
547 }
548 }
549 }
550
551 void CardTableRS::verify() {
552 // At present, we only know how to verify the card table RS for
553 // generational heaps.
554 VerifyCTGenClosure blk(this);
555 CollectedHeap* ch = Universe::heap();
556 // We will do the perm-gen portion of the card table, too.
557 Generation* pg = SharedHeap::heap()->perm_gen();
558 HeapWord* pg_boundary = pg->reserved().start();
559
560 if (ch->kind() == CollectedHeap::GenCollectedHeap) {
561 GenCollectedHeap::heap()->generation_iterate(&blk, false);
562 _ct_bs->verify();
563
564 // If the old gen collections also collect perm, then we are only
565 // interested in perm-to-young pointers, not perm-to-old pointers.
566 GenCollectedHeap* gch = GenCollectedHeap::heap();
567 CollectorPolicy* cp = gch->collector_policy();
568 if (cp->is_mark_sweep_policy() || cp->is_concurrent_mark_sweep_policy()) {
569 pg_boundary = gch->get_gen(1)->reserved().start();
570 }
571 }
572 VerifyCTSpaceClosure perm_space_blk(this, pg_boundary);
573 SharedHeap::heap()->perm_gen()->space_iterate(&perm_space_blk, true);
574 }
575
576
577 void CardTableRS::verify_aligned_region_empty(MemRegion mr) {
578 if (!mr.is_empty()) {
579 jbyte* cur_entry = byte_for(mr.start());
580 jbyte* limit = byte_after(mr.last());
581 // The region mr may not start on a card boundary so
582 // the first card may reflect a write to the space
583 // just prior to mr.
584 if (!is_aligned(mr.start())) {
585 cur_entry++;
586 }
587 for (;cur_entry < limit; cur_entry++) {
588 guarantee(*cur_entry == CardTableModRefBS::clean_card,
589 "Unexpected dirty card found");
590 }
591 }
592 }