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