1 /*
2 * Copyright (c) 2001, 2013, 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 "code/nmethod.hpp"
27 #include "gc_implementation/g1/g1BlockOffsetTable.inline.hpp"
28 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
29 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
30 #include "gc_implementation/g1/heapRegion.inline.hpp"
31 #include "gc_implementation/g1/heapRegionRemSet.hpp"
32 #include "gc_implementation/g1/heapRegionSeq.inline.hpp"
33 #include "memory/genOopClosures.inline.hpp"
34 #include "memory/iterator.hpp"
35 #include "oops/oop.inline.hpp"
36
37 int HeapRegion::LogOfHRGrainBytes = 0;
38 int HeapRegion::LogOfHRGrainWords = 0;
39 size_t HeapRegion::GrainBytes = 0;
40 size_t HeapRegion::GrainWords = 0;
41 size_t HeapRegion::CardsPerRegion = 0;
42
43 HeapRegionDCTOC::HeapRegionDCTOC(G1CollectedHeap* g1,
44 HeapRegion* hr, ExtendedOopClosure* cl,
45 CardTableModRefBS::PrecisionStyle precision,
46 FilterKind fk) :
47 ContiguousSpaceDCTOC(hr, cl, precision, NULL),
48 _hr(hr), _fk(fk), _g1(g1) { }
49
50 FilterOutOfRegionClosure::FilterOutOfRegionClosure(HeapRegion* r,
51 OopClosure* oc) :
52 _r_bottom(r->bottom()), _r_end(r->end()), _oc(oc) { }
53
54 template<class ClosureType>
55 HeapWord* walk_mem_region_loop(ClosureType* cl, G1CollectedHeap* g1h,
56 HeapRegion* hr,
57 HeapWord* cur, HeapWord* top) {
58 oop cur_oop = oop(cur);
59 int oop_size = cur_oop->size();
60 HeapWord* next_obj = cur + oop_size;
61 while (next_obj < top) {
62 // Keep filtering the remembered set.
63 if (!g1h->is_obj_dead(cur_oop, hr)) {
64 // Bottom lies entirely below top, so we can call the
65 // non-memRegion version of oop_iterate below.
66 cur_oop->oop_iterate(cl);
67 }
68 cur = next_obj;
69 cur_oop = oop(cur);
70 oop_size = cur_oop->size();
71 next_obj = cur + oop_size;
72 }
73 return cur;
74 }
75
76 void HeapRegionDCTOC::walk_mem_region_with_cl(MemRegion mr,
77 HeapWord* bottom,
78 HeapWord* top,
79 ExtendedOopClosure* cl) {
80 G1CollectedHeap* g1h = _g1;
81 int oop_size;
82 ExtendedOopClosure* cl2 = NULL;
83
84 FilterIntoCSClosure intoCSFilt(this, g1h, cl);
85 FilterOutOfRegionClosure outOfRegionFilt(_hr, cl);
86
87 switch (_fk) {
88 case NoFilterKind: cl2 = cl; break;
89 case IntoCSFilterKind: cl2 = &intoCSFilt; break;
90 case OutOfRegionFilterKind: cl2 = &outOfRegionFilt; break;
91 default: ShouldNotReachHere();
92 }
93
94 // Start filtering what we add to the remembered set. If the object is
95 // not considered dead, either because it is marked (in the mark bitmap)
96 // or it was allocated after marking finished, then we add it. Otherwise
97 // we can safely ignore the object.
98 if (!g1h->is_obj_dead(oop(bottom), _hr)) {
99 oop_size = oop(bottom)->oop_iterate(cl2, mr);
100 } else {
101 oop_size = oop(bottom)->size();
102 }
103
104 bottom += oop_size;
105
106 if (bottom < top) {
107 // We replicate the loop below for several kinds of possible filters.
108 switch (_fk) {
109 case NoFilterKind:
110 bottom = walk_mem_region_loop(cl, g1h, _hr, bottom, top);
111 break;
112
113 case IntoCSFilterKind: {
114 FilterIntoCSClosure filt(this, g1h, cl);
115 bottom = walk_mem_region_loop(&filt, g1h, _hr, bottom, top);
116 break;
117 }
118
119 case OutOfRegionFilterKind: {
120 FilterOutOfRegionClosure filt(_hr, cl);
121 bottom = walk_mem_region_loop(&filt, g1h, _hr, bottom, top);
122 break;
123 }
124
125 default:
126 ShouldNotReachHere();
127 }
128
129 // Last object. Need to do dead-obj filtering here too.
130 if (!g1h->is_obj_dead(oop(bottom), _hr)) {
131 oop(bottom)->oop_iterate(cl2, mr);
132 }
133 }
134 }
135
136 // Minimum region size; we won't go lower than that.
137 // We might want to decrease this in the future, to deal with small
138 // heaps a bit more efficiently.
139 #define MIN_REGION_SIZE ( 1024 * 1024 )
140
141 // Maximum region size; we don't go higher than that. There's a good
142 // reason for having an upper bound. We don't want regions to get too
143 // large, otherwise cleanup's effectiveness would decrease as there
144 // will be fewer opportunities to find totally empty regions after
145 // marking.
146 #define MAX_REGION_SIZE ( 32 * 1024 * 1024 )
147
148 // The automatic region size calculation will try to have around this
149 // many regions in the heap (based on the min heap size).
150 #define TARGET_REGION_NUMBER 2048
151
152 size_t HeapRegion::max_region_size() {
153 return (size_t)MAX_REGION_SIZE;
154 }
155
156 void HeapRegion::setup_heap_region_size(size_t initial_heap_size, size_t max_heap_size) {
157 uintx region_size = G1HeapRegionSize;
158 if (FLAG_IS_DEFAULT(G1HeapRegionSize)) {
159 size_t average_heap_size = (initial_heap_size + max_heap_size) / 2;
160 region_size = MAX2(average_heap_size / TARGET_REGION_NUMBER,
161 (uintx) MIN_REGION_SIZE);
162 }
163
164 int region_size_log = log2_long((jlong) region_size);
165 // Recalculate the region size to make sure it's a power of
166 // 2. This means that region_size is the largest power of 2 that's
167 // <= what we've calculated so far.
168 region_size = ((uintx)1 << region_size_log);
169
170 // Now make sure that we don't go over or under our limits.
171 if (region_size < MIN_REGION_SIZE) {
172 region_size = MIN_REGION_SIZE;
173 } else if (region_size > MAX_REGION_SIZE) {
174 region_size = MAX_REGION_SIZE;
175 }
176
177 // And recalculate the log.
178 region_size_log = log2_long((jlong) region_size);
179
180 // Now, set up the globals.
181 guarantee(LogOfHRGrainBytes == 0, "we should only set it once");
182 LogOfHRGrainBytes = region_size_log;
183
184 guarantee(LogOfHRGrainWords == 0, "we should only set it once");
185 LogOfHRGrainWords = LogOfHRGrainBytes - LogHeapWordSize;
186
187 guarantee(GrainBytes == 0, "we should only set it once");
188 // The cast to int is safe, given that we've bounded region_size by
189 // MIN_REGION_SIZE and MAX_REGION_SIZE.
190 GrainBytes = (size_t)region_size;
191
192 guarantee(GrainWords == 0, "we should only set it once");
193 GrainWords = GrainBytes >> LogHeapWordSize;
194 guarantee((size_t) 1 << LogOfHRGrainWords == GrainWords, "sanity");
195
196 guarantee(CardsPerRegion == 0, "we should only set it once");
197 CardsPerRegion = GrainBytes >> CardTableModRefBS::card_shift;
198 }
199
200 void HeapRegion::reset_after_compaction() {
201 G1OffsetTableContigSpace::reset_after_compaction();
202 // After a compaction the mark bitmap is invalid, so we must
203 // treat all objects as being inside the unmarked area.
204 zero_marked_bytes();
205 init_top_at_mark_start();
206 }
207
208 void HeapRegion::hr_clear(bool par, bool clear_space) {
209 assert(_humongous_type == NotHumongous,
210 "we should have already filtered out humongous regions");
211 assert(_humongous_start_region == NULL,
212 "we should have already filtered out humongous regions");
213 assert(_end == _orig_end,
214 "we should have already filtered out humongous regions");
215
216 _in_collection_set = false;
217
218 set_young_index_in_cset(-1);
219 uninstall_surv_rate_group();
220 set_young_type(NotYoung);
221 reset_pre_dummy_top();
222
223 if (!par) {
224 // If this is parallel, this will be done later.
225 HeapRegionRemSet* hrrs = rem_set();
226 hrrs->clear();
227 _claimed = InitialClaimValue;
228 }
229 zero_marked_bytes();
230
231 _offsets.resize(HeapRegion::GrainWords);
232 init_top_at_mark_start();
233 if (clear_space) clear(SpaceDecorator::Mangle);
234 }
235
236 void HeapRegion::par_clear() {
237 assert(used() == 0, "the region should have been already cleared");
238 assert(capacity() == HeapRegion::GrainBytes, "should be back to normal");
239 HeapRegionRemSet* hrrs = rem_set();
240 hrrs->clear();
241 CardTableModRefBS* ct_bs =
242 (CardTableModRefBS*)G1CollectedHeap::heap()->barrier_set();
243 ct_bs->clear(MemRegion(bottom(), end()));
244 }
245
246 void HeapRegion::calc_gc_efficiency() {
247 // GC efficiency is the ratio of how much space would be
248 // reclaimed over how long we predict it would take to reclaim it.
249 G1CollectedHeap* g1h = G1CollectedHeap::heap();
250 G1CollectorPolicy* g1p = g1h->g1_policy();
251
252 // Retrieve a prediction of the elapsed time for this region for
253 // a mixed gc because the region will only be evacuated during a
254 // mixed gc.
255 double region_elapsed_time_ms =
256 g1p->predict_region_elapsed_time_ms(this, false /* for_young_gc */);
257 _gc_efficiency = (double) reclaimable_bytes() / region_elapsed_time_ms;
258 }
259
260 void HeapRegion::set_startsHumongous(HeapWord* new_top, HeapWord* new_end) {
261 assert(!isHumongous(), "sanity / pre-condition");
262 assert(end() == _orig_end,
263 "Should be normal before the humongous object allocation");
264 assert(top() == bottom(), "should be empty");
265 assert(bottom() <= new_top && new_top <= new_end, "pre-condition");
266
267 _humongous_type = StartsHumongous;
268 _humongous_start_region = this;
269
270 set_end(new_end);
271 _offsets.set_for_starts_humongous(new_top);
272 }
273
274 void HeapRegion::set_continuesHumongous(HeapRegion* first_hr) {
275 assert(!isHumongous(), "sanity / pre-condition");
276 assert(end() == _orig_end,
277 "Should be normal before the humongous object allocation");
278 assert(top() == bottom(), "should be empty");
279 assert(first_hr->startsHumongous(), "pre-condition");
280
281 _humongous_type = ContinuesHumongous;
282 _humongous_start_region = first_hr;
283 }
284
285 void HeapRegion::set_notHumongous() {
286 assert(isHumongous(), "pre-condition");
287
288 if (startsHumongous()) {
289 assert(top() <= end(), "pre-condition");
290 set_end(_orig_end);
291 if (top() > end()) {
292 // at least one "continues humongous" region after it
293 set_top(end());
294 }
295 } else {
296 // continues humongous
297 assert(end() == _orig_end, "sanity");
298 }
299
300 assert(capacity() == HeapRegion::GrainBytes, "pre-condition");
301 _humongous_type = NotHumongous;
302 _humongous_start_region = NULL;
303 }
304
305 bool HeapRegion::claimHeapRegion(jint claimValue) {
306 jint current = _claimed;
307 if (current != claimValue) {
308 jint res = Atomic::cmpxchg(claimValue, &_claimed, current);
309 if (res == current) {
310 return true;
311 }
312 }
313 return false;
314 }
315
316 HeapWord* HeapRegion::next_block_start_careful(HeapWord* addr) {
317 HeapWord* low = addr;
318 HeapWord* high = end();
319 while (low < high) {
320 size_t diff = pointer_delta(high, low);
321 // Must add one below to bias toward the high amount. Otherwise, if
322 // "high" were at the desired value, and "low" were one less, we
323 // would not converge on "high". This is not symmetric, because
324 // we set "high" to a block start, which might be the right one,
325 // which we don't do for "low".
326 HeapWord* middle = low + (diff+1)/2;
327 if (middle == high) return high;
328 HeapWord* mid_bs = block_start_careful(middle);
329 if (mid_bs < addr) {
330 low = middle;
331 } else {
332 high = mid_bs;
333 }
334 }
335 assert(low == high && low >= addr, "Didn't work.");
336 return low;
337 }
338
339 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
340 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
341 #endif // _MSC_VER
342
343
344 HeapRegion::HeapRegion(uint hrs_index,
345 G1BlockOffsetSharedArray* sharedOffsetArray,
346 MemRegion mr) :
347 G1OffsetTableContigSpace(sharedOffsetArray, mr),
348 _hrs_index(hrs_index),
349 _humongous_type(NotHumongous), _humongous_start_region(NULL),
350 _in_collection_set(false),
351 _next_in_special_set(NULL), _orig_end(NULL),
352 _claimed(InitialClaimValue), _evacuation_failed(false),
353 _prev_marked_bytes(0), _next_marked_bytes(0), _gc_efficiency(0.0),
354 _young_type(NotYoung), _next_young_region(NULL),
355 _next_dirty_cards_region(NULL), _next(NULL), _pending_removal(false),
356 #ifdef ASSERT
357 _containing_set(NULL),
358 #endif // ASSERT
359 _young_index_in_cset(-1), _surv_rate_group(NULL), _age_index(-1),
360 _rem_set(NULL), _recorded_rs_length(0), _predicted_elapsed_time_ms(0),
361 _predicted_bytes_to_copy(0)
362 {
363 _rem_set = new HeapRegionRemSet(sharedOffsetArray, this);
364 _orig_end = mr.end();
365 // Note that initialize() will set the start of the unmarked area of the
366 // region.
367 hr_clear(false /*par*/, false /*clear_space*/);
368 set_top(bottom());
369 set_saved_mark();
370
371 assert(HeapRegionRemSet::num_par_rem_sets() > 0, "Invariant.");
372 }
373
374 CompactibleSpace* HeapRegion::next_compaction_space() const {
375 // We're not using an iterator given that it will wrap around when
376 // it reaches the last region and this is not what we want here.
377 G1CollectedHeap* g1h = G1CollectedHeap::heap();
378 uint index = hrs_index() + 1;
379 while (index < g1h->n_regions()) {
380 HeapRegion* hr = g1h->region_at(index);
381 if (!hr->isHumongous()) {
382 return hr;
383 }
384 index += 1;
385 }
386 return NULL;
387 }
388
389 void HeapRegion::save_marks() {
390 set_saved_mark();
391 }
392
393 void HeapRegion::oops_in_mr_iterate(MemRegion mr, ExtendedOopClosure* cl) {
394 HeapWord* p = mr.start();
395 HeapWord* e = mr.end();
396 oop obj;
397 while (p < e) {
398 obj = oop(p);
399 p += obj->oop_iterate(cl);
400 }
401 assert(p == e, "bad memregion: doesn't end on obj boundary");
402 }
403
404 #define HeapRegion_OOP_SINCE_SAVE_MARKS_DEFN(OopClosureType, nv_suffix) \
405 void HeapRegion::oop_since_save_marks_iterate##nv_suffix(OopClosureType* cl) { \
406 ContiguousSpace::oop_since_save_marks_iterate##nv_suffix(cl); \
407 }
408 SPECIALIZED_SINCE_SAVE_MARKS_CLOSURES(HeapRegion_OOP_SINCE_SAVE_MARKS_DEFN)
409
410
411 void HeapRegion::oop_before_save_marks_iterate(ExtendedOopClosure* cl) {
412 oops_in_mr_iterate(MemRegion(bottom(), saved_mark_word()), cl);
413 }
414
415 void HeapRegion::note_self_forwarding_removal_start(bool during_initial_mark,
416 bool during_conc_mark) {
417 // We always recreate the prev marking info and we'll explicitly
418 // mark all objects we find to be self-forwarded on the prev
419 // bitmap. So all objects need to be below PTAMS.
420 _prev_top_at_mark_start = top();
421 _prev_marked_bytes = 0;
422
423 if (during_initial_mark) {
424 // During initial-mark, we'll also explicitly mark all objects
425 // we find to be self-forwarded on the next bitmap. So all
426 // objects need to be below NTAMS.
427 _next_top_at_mark_start = top();
428 _next_marked_bytes = 0;
429 } else if (during_conc_mark) {
430 // During concurrent mark, all objects in the CSet (including
431 // the ones we find to be self-forwarded) are implicitly live.
432 // So all objects need to be above NTAMS.
433 _next_top_at_mark_start = bottom();
434 _next_marked_bytes = 0;
435 }
436 }
437
438 void HeapRegion::note_self_forwarding_removal_end(bool during_initial_mark,
439 bool during_conc_mark,
440 size_t marked_bytes) {
441 assert(0 <= marked_bytes && marked_bytes <= used(),
442 err_msg("marked: "SIZE_FORMAT" used: "SIZE_FORMAT,
443 marked_bytes, used()));
444 _prev_marked_bytes = marked_bytes;
445 }
446
447 HeapWord*
448 HeapRegion::object_iterate_mem_careful(MemRegion mr,
449 ObjectClosure* cl) {
450 G1CollectedHeap* g1h = G1CollectedHeap::heap();
451 // We used to use "block_start_careful" here. But we're actually happy
452 // to update the BOT while we do this...
453 HeapWord* cur = block_start(mr.start());
454 mr = mr.intersection(used_region());
455 if (mr.is_empty()) return NULL;
456 // Otherwise, find the obj that extends onto mr.start().
457
458 assert(cur <= mr.start()
459 && (oop(cur)->klass_or_null() == NULL ||
460 cur + oop(cur)->size() > mr.start()),
461 "postcondition of block_start");
462 oop obj;
463 while (cur < mr.end()) {
464 obj = oop(cur);
465 if (obj->klass_or_null() == NULL) {
466 // Ran into an unparseable point.
467 return cur;
468 } else if (!g1h->is_obj_dead(obj)) {
469 cl->do_object(obj);
470 }
471 if (cl->abort()) return cur;
472 // The check above must occur before the operation below, since an
473 // abort might invalidate the "size" operation.
474 cur += obj->size();
475 }
476 return NULL;
477 }
478
479 HeapWord*
480 HeapRegion::
481 oops_on_card_seq_iterate_careful(MemRegion mr,
482 FilterOutOfRegionClosure* cl,
483 bool filter_young,
484 jbyte* card_ptr) {
485 // Currently, we should only have to clean the card if filter_young
486 // is true and vice versa.
487 if (filter_young) {
488 assert(card_ptr != NULL, "pre-condition");
489 } else {
490 assert(card_ptr == NULL, "pre-condition");
491 }
492 G1CollectedHeap* g1h = G1CollectedHeap::heap();
493
494 // If we're within a stop-world GC, then we might look at a card in a
495 // GC alloc region that extends onto a GC LAB, which may not be
496 // parseable. Stop such at the "saved_mark" of the region.
497 if (g1h->is_gc_active()) {
498 mr = mr.intersection(used_region_at_save_marks());
499 } else {
500 mr = mr.intersection(used_region());
501 }
502 if (mr.is_empty()) return NULL;
503 // Otherwise, find the obj that extends onto mr.start().
504
505 // The intersection of the incoming mr (for the card) and the
506 // allocated part of the region is non-empty. This implies that
507 // we have actually allocated into this region. The code in
508 // G1CollectedHeap.cpp that allocates a new region sets the
509 // is_young tag on the region before allocating. Thus we
510 // safely know if this region is young.
511 if (is_young() && filter_young) {
512 return NULL;
513 }
514
515 assert(!is_young(), "check value of filter_young");
516
517 // We can only clean the card here, after we make the decision that
518 // the card is not young. And we only clean the card if we have been
519 // asked to (i.e., card_ptr != NULL).
520 if (card_ptr != NULL) {
521 *card_ptr = CardTableModRefBS::clean_card_val();
522 // We must complete this write before we do any of the reads below.
523 OrderAccess::storeload();
524 }
525
526 // Cache the boundaries of the memory region in some const locals
527 HeapWord* const start = mr.start();
528 HeapWord* const end = mr.end();
529
530 // We used to use "block_start_careful" here. But we're actually happy
531 // to update the BOT while we do this...
532 HeapWord* cur = block_start(start);
533 assert(cur <= start, "Postcondition");
534
535 oop obj;
536
537 HeapWord* next = cur;
538 while (next <= start) {
539 cur = next;
540 obj = oop(cur);
541 if (obj->klass_or_null() == NULL) {
542 // Ran into an unparseable point.
543 return cur;
544 }
545 // Otherwise...
546 next = (cur + obj->size());
547 }
548
549 // If we finish the above loop...We have a parseable object that
550 // begins on or before the start of the memory region, and ends
551 // inside or spans the entire region.
552
553 assert(obj == oop(cur), "sanity");
554 assert(cur <= start &&
555 obj->klass_or_null() != NULL &&
556 (cur + obj->size()) > start,
557 "Loop postcondition");
558
559 if (!g1h->is_obj_dead(obj)) {
560 obj->oop_iterate(cl, mr);
561 }
562
563 while (cur < end) {
564 obj = oop(cur);
565 if (obj->klass_or_null() == NULL) {
566 // Ran into an unparseable point.
567 return cur;
568 };
569
570 // Otherwise:
571 next = (cur + obj->size());
572
573 if (!g1h->is_obj_dead(obj)) {
574 if (next < end || !obj->is_objArray()) {
575 // This object either does not span the MemRegion
576 // boundary, or if it does it's not an array.
577 // Apply closure to whole object.
578 obj->oop_iterate(cl);
579 } else {
580 // This obj is an array that spans the boundary.
581 // Stop at the boundary.
582 obj->oop_iterate(cl, mr);
583 }
584 }
585 cur = next;
586 }
587 return NULL;
588 }
589
590 // Code roots support
591
592 void HeapRegion::add_strong_code_root(nmethod* nm) {
593 HeapRegionRemSet* hrrs = rem_set();
594 hrrs->add_strong_code_root(nm);
595 }
596
597 void HeapRegion::remove_strong_code_root(nmethod* nm) {
598 HeapRegionRemSet* hrrs = rem_set();
599 hrrs->remove_strong_code_root(nm);
600 }
601
602 void HeapRegion::migrate_strong_code_roots() {
603 assert(in_collection_set(), "only collection set regions");
604 assert(!isHumongous(),
605 err_msg("humongous region "HR_FORMAT" should not have been added to collection set",
606 HR_FORMAT_PARAMS(this)));
607
608 HeapRegionRemSet* hrrs = rem_set();
609 hrrs->migrate_strong_code_roots();
610 }
611
612 void HeapRegion::strong_code_roots_do(CodeBlobClosure* blk) const {
613 HeapRegionRemSet* hrrs = rem_set();
614 hrrs->strong_code_roots_do(blk);
615 }
616
617 class VerifyStrongCodeRootOopClosure: public OopClosure {
618 const HeapRegion* _hr;
619 nmethod* _nm;
620 bool _failures;
621 bool _has_oops_in_region;
622
623 template <class T> void do_oop_work(T* p) {
624 T heap_oop = oopDesc::load_heap_oop(p);
625 if (!oopDesc::is_null(heap_oop)) {
626 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
627
628 // Note: not all the oops embedded in the nmethod are in the
629 // current region. We only look at those which are.
630 if (_hr->is_in(obj)) {
631 // Object is in the region. Check that its less than top
632 if (_hr->top() <= (HeapWord*)obj) {
633 // Object is above top
634 gclog_or_tty->print_cr("Object "PTR_FORMAT" in region "
635 "["PTR_FORMAT", "PTR_FORMAT") is above "
636 "top "PTR_FORMAT,
637 (void *)obj, _hr->bottom(), _hr->end(), _hr->top());
638 _failures = true;
639 return;
640 }
641 // Nmethod has at least one oop in the current region
642 _has_oops_in_region = true;
643 }
644 }
645 }
646
647 public:
648 VerifyStrongCodeRootOopClosure(const HeapRegion* hr, nmethod* nm):
649 _hr(hr), _failures(false), _has_oops_in_region(false) {}
650
651 void do_oop(narrowOop* p) { do_oop_work(p); }
652 void do_oop(oop* p) { do_oop_work(p); }
653
654 bool failures() { return _failures; }
655 bool has_oops_in_region() { return _has_oops_in_region; }
656 };
657
658 class VerifyStrongCodeRootCodeBlobClosure: public CodeBlobClosure {
659 const HeapRegion* _hr;
660 bool _failures;
661 public:
662 VerifyStrongCodeRootCodeBlobClosure(const HeapRegion* hr) :
663 _hr(hr), _failures(false) {}
664
665 void do_code_blob(CodeBlob* cb) {
666 nmethod* nm = (cb == NULL) ? NULL : cb->as_nmethod_or_null();
667 if (nm != NULL) {
668 // Verify that the nemthod is live
669 if (!nm->is_alive()) {
670 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] has dead nmethod "
671 PTR_FORMAT" in its strong code roots",
672 _hr->bottom(), _hr->end(), nm);
673 _failures = true;
674 } else {
675 VerifyStrongCodeRootOopClosure oop_cl(_hr, nm);
676 nm->oops_do(&oop_cl);
677 if (!oop_cl.has_oops_in_region()) {
678 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] has nmethod "
679 PTR_FORMAT" in its strong code roots "
680 "with no pointers into region",
681 _hr->bottom(), _hr->end(), nm);
682 _failures = true;
683 } else if (oop_cl.failures()) {
684 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] has other "
685 "failures for nmethod "PTR_FORMAT,
686 _hr->bottom(), _hr->end(), nm);
687 _failures = true;
688 }
689 }
690 }
691 }
692
693 bool failures() { return _failures; }
694 };
695
696 void HeapRegion::verify_strong_code_roots(VerifyOption vo, bool* failures) const {
697 if (!G1VerifyHeapRegionCodeRoots) {
698 // We're not verifying code roots.
699 return;
700 }
701 if (vo == VerifyOption_G1UseMarkWord) {
702 // Marking verification during a full GC is performed after class
703 // unloading, code cache unloading, etc so the strong code roots
704 // attached to each heap region are in an inconsistent state. They won't
705 // be consistent until the strong code roots are rebuilt after the
706 // actual GC. Skip verifying the strong code roots in this particular
707 // time.
708 assert(VerifyDuringGC, "only way to get here");
709 return;
710 }
711
712 HeapRegionRemSet* hrrs = rem_set();
713 int strong_code_roots_length = hrrs->strong_code_roots_list_length();
714
715 // if this region is empty then there should be no entries
716 // on its strong code root list
717 if (is_empty()) {
718 if (strong_code_roots_length > 0) {
719 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] is empty "
720 "but has "INT32_FORMAT" code root entries",
721 bottom(), end(), strong_code_roots_length);
722 *failures = true;
723 }
724 return;
725 }
726
727 if (continuesHumongous()) {
728 if (strong_code_roots_length > 0) {
729 gclog_or_tty->print_cr("region "HR_FORMAT" is a continuation of a humongous "
730 "region but has "INT32_FORMAT" code root entries",
731 HR_FORMAT_PARAMS(this), strong_code_roots_length);
732 *failures = true;
733 }
734 return;
735 }
736
737 VerifyStrongCodeRootCodeBlobClosure cb_cl(this);
738 strong_code_roots_do(&cb_cl);
739
740 if (cb_cl.failures()) {
741 *failures = true;
742 }
743 }
744
745 void HeapRegion::print() const { print_on(gclog_or_tty); }
746 void HeapRegion::print_on(outputStream* st) const {
747 if (isHumongous()) {
748 if (startsHumongous())
749 st->print(" HS");
750 else
751 st->print(" HC");
752 } else {
753 st->print(" ");
754 }
755 if (in_collection_set())
756 st->print(" CS");
757 else
758 st->print(" ");
759 if (is_young())
760 st->print(is_survivor() ? " SU" : " Y ");
761 else
762 st->print(" ");
763 if (is_empty())
764 st->print(" F");
765 else
766 st->print(" ");
767 st->print(" TS %5d", _gc_time_stamp);
768 st->print(" PTAMS "PTR_FORMAT" NTAMS "PTR_FORMAT,
769 prev_top_at_mark_start(), next_top_at_mark_start());
770 G1OffsetTableContigSpace::print_on(st);
771 }
772
773 class VerifyLiveClosure: public OopClosure {
774 private:
775 G1CollectedHeap* _g1h;
776 CardTableModRefBS* _bs;
777 oop _containing_obj;
778 bool _failures;
779 int _n_failures;
780 VerifyOption _vo;
781 public:
782 // _vo == UsePrevMarking -> use "prev" marking information,
783 // _vo == UseNextMarking -> use "next" marking information,
784 // _vo == UseMarkWord -> use mark word from object header.
785 VerifyLiveClosure(G1CollectedHeap* g1h, VerifyOption vo) :
786 _g1h(g1h), _bs(NULL), _containing_obj(NULL),
787 _failures(false), _n_failures(0), _vo(vo)
788 {
789 BarrierSet* bs = _g1h->barrier_set();
790 if (bs->is_a(BarrierSet::CardTableModRef))
791 _bs = (CardTableModRefBS*)bs;
792 }
793
794 void set_containing_obj(oop obj) {
795 _containing_obj = obj;
796 }
797
798 bool failures() { return _failures; }
799 int n_failures() { return _n_failures; }
800
801 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
802 virtual void do_oop( oop* p) { do_oop_work(p); }
803
804 void print_object(outputStream* out, oop obj) {
805 #ifdef PRODUCT
806 Klass* k = obj->klass();
807 const char* class_name = InstanceKlass::cast(k)->external_name();
808 out->print_cr("class name %s", class_name);
809 #else // PRODUCT
810 obj->print_on(out);
811 #endif // PRODUCT
812 }
813
814 template <class T>
815 void do_oop_work(T* p) {
816 assert(_containing_obj != NULL, "Precondition");
817 assert(!_g1h->is_obj_dead_cond(_containing_obj, _vo),
818 "Precondition");
819 T heap_oop = oopDesc::load_heap_oop(p);
820 if (!oopDesc::is_null(heap_oop)) {
821 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
822 bool failed = false;
823 if (!_g1h->is_in_closed_subset(obj) || _g1h->is_obj_dead_cond(obj, _vo)) {
824 MutexLockerEx x(ParGCRareEvent_lock,
825 Mutex::_no_safepoint_check_flag);
826
827 if (!_failures) {
828 gclog_or_tty->print_cr("");
829 gclog_or_tty->print_cr("----------");
830 }
831 if (!_g1h->is_in_closed_subset(obj)) {
832 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
833 gclog_or_tty->print_cr("Field "PTR_FORMAT
834 " of live obj "PTR_FORMAT" in region "
835 "["PTR_FORMAT", "PTR_FORMAT")",
836 p, (void*) _containing_obj,
837 from->bottom(), from->end());
838 print_object(gclog_or_tty, _containing_obj);
839 gclog_or_tty->print_cr("points to obj "PTR_FORMAT" not in the heap",
840 (void*) obj);
841 } else {
842 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
843 HeapRegion* to = _g1h->heap_region_containing((HeapWord*)obj);
844 gclog_or_tty->print_cr("Field "PTR_FORMAT
845 " of live obj "PTR_FORMAT" in region "
846 "["PTR_FORMAT", "PTR_FORMAT")",
847 p, (void*) _containing_obj,
848 from->bottom(), from->end());
849 print_object(gclog_or_tty, _containing_obj);
850 gclog_or_tty->print_cr("points to dead obj "PTR_FORMAT" in region "
851 "["PTR_FORMAT", "PTR_FORMAT")",
852 (void*) obj, to->bottom(), to->end());
853 print_object(gclog_or_tty, obj);
854 }
855 gclog_or_tty->print_cr("----------");
856 gclog_or_tty->flush();
857 _failures = true;
858 failed = true;
859 _n_failures++;
860 }
861
862 if (!_g1h->full_collection() || G1VerifyRSetsDuringFullGC) {
863 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
864 HeapRegion* to = _g1h->heap_region_containing(obj);
865 if (from != NULL && to != NULL &&
866 from != to &&
867 !to->isHumongous()) {
868 jbyte cv_obj = *_bs->byte_for_const(_containing_obj);
869 jbyte cv_field = *_bs->byte_for_const(p);
870 const jbyte dirty = CardTableModRefBS::dirty_card_val();
871
872 bool is_bad = !(from->is_young()
873 || to->rem_set()->contains_reference(p)
874 || !G1HRRSFlushLogBuffersOnVerify && // buffers were not flushed
875 (_containing_obj->is_objArray() ?
876 cv_field == dirty
877 : cv_obj == dirty || cv_field == dirty));
878 if (is_bad) {
879 MutexLockerEx x(ParGCRareEvent_lock,
880 Mutex::_no_safepoint_check_flag);
881
882 if (!_failures) {
883 gclog_or_tty->print_cr("");
884 gclog_or_tty->print_cr("----------");
885 }
886 gclog_or_tty->print_cr("Missing rem set entry:");
887 gclog_or_tty->print_cr("Field "PTR_FORMAT" "
888 "of obj "PTR_FORMAT", "
889 "in region "HR_FORMAT,
890 p, (void*) _containing_obj,
891 HR_FORMAT_PARAMS(from));
892 _containing_obj->print_on(gclog_or_tty);
893 gclog_or_tty->print_cr("points to obj "PTR_FORMAT" "
894 "in region "HR_FORMAT,
895 (void*) obj,
896 HR_FORMAT_PARAMS(to));
897 obj->print_on(gclog_or_tty);
898 gclog_or_tty->print_cr("Obj head CTE = %d, field CTE = %d.",
899 cv_obj, cv_field);
900 gclog_or_tty->print_cr("----------");
901 gclog_or_tty->flush();
902 _failures = true;
903 if (!failed) _n_failures++;
904 }
905 }
906 }
907 }
908 }
909 };
910
911 // This really ought to be commoned up into OffsetTableContigSpace somehow.
912 // We would need a mechanism to make that code skip dead objects.
913
914 void HeapRegion::verify(VerifyOption vo,
915 bool* failures) const {
916 G1CollectedHeap* g1 = G1CollectedHeap::heap();
917 *failures = false;
918 HeapWord* p = bottom();
919 HeapWord* prev_p = NULL;
920 VerifyLiveClosure vl_cl(g1, vo);
921 bool is_humongous = isHumongous();
922 bool do_bot_verify = !is_young();
923 size_t object_num = 0;
924 while (p < top()) {
925 oop obj = oop(p);
926 size_t obj_size = obj->size();
927 object_num += 1;
928
929 if (is_humongous != g1->isHumongous(obj_size)) {
930 gclog_or_tty->print_cr("obj "PTR_FORMAT" is of %shumongous size ("
931 SIZE_FORMAT" words) in a %shumongous region",
932 p, g1->isHumongous(obj_size) ? "" : "non-",
933 obj_size, is_humongous ? "" : "non-");
934 *failures = true;
935 return;
936 }
937
938 // If it returns false, verify_for_object() will output the
939 // appropriate messasge.
940 if (do_bot_verify && !_offsets.verify_for_object(p, obj_size)) {
941 *failures = true;
942 return;
943 }
944
945 if (!g1->is_obj_dead_cond(obj, this, vo)) {
946 if (obj->is_oop()) {
947 Klass* klass = obj->klass();
948 if (!klass->is_metaspace_object()) {
949 gclog_or_tty->print_cr("klass "PTR_FORMAT" of object "PTR_FORMAT" "
950 "not metadata", klass, (void *)obj);
951 *failures = true;
952 return;
953 } else if (!klass->is_klass()) {
954 gclog_or_tty->print_cr("klass "PTR_FORMAT" of object "PTR_FORMAT" "
955 "not a klass", klass, (void *)obj);
956 *failures = true;
957 return;
958 } else {
959 vl_cl.set_containing_obj(obj);
960 obj->oop_iterate_no_header(&vl_cl);
961 if (vl_cl.failures()) {
962 *failures = true;
963 }
964 if (G1MaxVerifyFailures >= 0 &&
965 vl_cl.n_failures() >= G1MaxVerifyFailures) {
966 return;
967 }
968 }
969 } else {
970 gclog_or_tty->print_cr(PTR_FORMAT" no an oop", (void *)obj);
971 *failures = true;
972 return;
973 }
974 }
975 prev_p = p;
976 p += obj_size;
977 }
978
979 if (p != top()) {
980 gclog_or_tty->print_cr("end of last object "PTR_FORMAT" "
981 "does not match top "PTR_FORMAT, p, top());
982 *failures = true;
983 return;
984 }
985
986 HeapWord* the_end = end();
987 assert(p == top(), "it should still hold");
988 // Do some extra BOT consistency checking for addresses in the
989 // range [top, end). BOT look-ups in this range should yield
990 // top. No point in doing that if top == end (there's nothing there).
991 if (p < the_end) {
992 // Look up top
993 HeapWord* addr_1 = p;
994 HeapWord* b_start_1 = _offsets.block_start_const(addr_1);
995 if (b_start_1 != p) {
996 gclog_or_tty->print_cr("BOT look up for top: "PTR_FORMAT" "
997 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
998 addr_1, b_start_1, p);
999 *failures = true;
1000 return;
1001 }
1002
1003 // Look up top + 1
1004 HeapWord* addr_2 = p + 1;
1005 if (addr_2 < the_end) {
1006 HeapWord* b_start_2 = _offsets.block_start_const(addr_2);
1007 if (b_start_2 != p) {
1008 gclog_or_tty->print_cr("BOT look up for top + 1: "PTR_FORMAT" "
1009 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
1010 addr_2, b_start_2, p);
1011 *failures = true;
1012 return;
1013 }
1014 }
1015
1016 // Look up an address between top and end
1017 size_t diff = pointer_delta(the_end, p) / 2;
1018 HeapWord* addr_3 = p + diff;
1019 if (addr_3 < the_end) {
1020 HeapWord* b_start_3 = _offsets.block_start_const(addr_3);
1021 if (b_start_3 != p) {
1022 gclog_or_tty->print_cr("BOT look up for top + diff: "PTR_FORMAT" "
1023 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
1024 addr_3, b_start_3, p);
1025 *failures = true;
1026 return;
1027 }
1028 }
1029
1030 // Look up end - 1
1031 HeapWord* addr_4 = the_end - 1;
1032 HeapWord* b_start_4 = _offsets.block_start_const(addr_4);
1033 if (b_start_4 != p) {
1034 gclog_or_tty->print_cr("BOT look up for end - 1: "PTR_FORMAT" "
1035 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
1036 addr_4, b_start_4, p);
1037 *failures = true;
1038 return;
1039 }
1040 }
1041
1042 if (is_humongous && object_num > 1) {
1043 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] is humongous "
1044 "but has "SIZE_FORMAT", objects",
1045 bottom(), end(), object_num);
1046 *failures = true;
1047 return;
1048 }
1049
1050 verify_strong_code_roots(vo, failures);
1051 }
1052
1053 void HeapRegion::verify() const {
1054 bool dummy = false;
1055 verify(VerifyOption_G1UsePrevMarking, /* failures */ &dummy);
1056 }
1057
1058 // G1OffsetTableContigSpace code; copied from space.cpp. Hope this can go
1059 // away eventually.
1060
1061 void G1OffsetTableContigSpace::clear(bool mangle_space) {
1062 ContiguousSpace::clear(mangle_space);
1063 _offsets.zero_bottom_entry();
1064 _offsets.initialize_threshold();
1065 }
1066
1067 void G1OffsetTableContigSpace::set_bottom(HeapWord* new_bottom) {
1068 Space::set_bottom(new_bottom);
1069 _offsets.set_bottom(new_bottom);
1070 }
1071
1072 void G1OffsetTableContigSpace::set_end(HeapWord* new_end) {
1073 Space::set_end(new_end);
1074 _offsets.resize(new_end - bottom());
1075 }
1076
1077 void G1OffsetTableContigSpace::print() const {
1078 print_short();
1079 gclog_or_tty->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", "
1080 INTPTR_FORMAT ", " INTPTR_FORMAT ")",
1081 bottom(), top(), _offsets.threshold(), end());
1082 }
1083
1084 HeapWord* G1OffsetTableContigSpace::initialize_threshold() {
1085 return _offsets.initialize_threshold();
1086 }
1087
1088 HeapWord* G1OffsetTableContigSpace::cross_threshold(HeapWord* start,
1089 HeapWord* end) {
1090 _offsets.alloc_block(start, end);
1091 return _offsets.threshold();
1092 }
1093
1094 HeapWord* G1OffsetTableContigSpace::saved_mark_word() const {
1095 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1096 assert( _gc_time_stamp <= g1h->get_gc_time_stamp(), "invariant" );
1097 if (_gc_time_stamp < g1h->get_gc_time_stamp())
1098 return top();
1099 else
1100 return ContiguousSpace::saved_mark_word();
1101 }
1102
1103 void G1OffsetTableContigSpace::set_saved_mark() {
1104 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1105 unsigned curr_gc_time_stamp = g1h->get_gc_time_stamp();
1106
1107 if (_gc_time_stamp < curr_gc_time_stamp) {
1108 // The order of these is important, as another thread might be
1109 // about to start scanning this region. If it does so after
1110 // set_saved_mark and before _gc_time_stamp = ..., then the latter
1111 // will be false, and it will pick up top() as the high water mark
1112 // of region. If it does so after _gc_time_stamp = ..., then it
1113 // will pick up the right saved_mark_word() as the high water mark
1114 // of the region. Either way, the behavior will be correct.
1115 ContiguousSpace::set_saved_mark();
1116 OrderAccess::storestore();
1117 _gc_time_stamp = curr_gc_time_stamp;
1118 // No need to do another barrier to flush the writes above. If
1119 // this is called in parallel with other threads trying to
1120 // allocate into the region, the caller should call this while
1121 // holding a lock and when the lock is released the writes will be
1122 // flushed.
1123 }
1124 }
1125
1126 G1OffsetTableContigSpace::
1127 G1OffsetTableContigSpace(G1BlockOffsetSharedArray* sharedOffsetArray,
1128 MemRegion mr) :
1129 _offsets(sharedOffsetArray, mr),
1130 _par_alloc_lock(Mutex::leaf, "OffsetTableContigSpace par alloc lock", true),
1131 _gc_time_stamp(0)
1132 {
1133 _offsets.set_space(this);
1134 // false ==> we'll do the clearing if there's clearing to be done.
1135 ContiguousSpace::initialize(mr, false, SpaceDecorator::Mangle);
1136 _offsets.zero_bottom_entry();
1137 _offsets.initialize_threshold();
1138 }