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/heapRegionManager.inline.hpp"
33 #include "gc_implementation/shared/liveRange.hpp"
34 #include "memory/genOopClosures.inline.hpp"
35 #include "memory/iterator.hpp"
36 #include "memory/space.inline.hpp"
37 #include "oops/oop.inline.hpp"
38 #include "runtime/atomic.inline.hpp"
39 #include "runtime/orderAccess.inline.hpp"
40
41 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
42
43 int HeapRegion::LogOfHRGrainBytes = 0;
44 int HeapRegion::LogOfHRGrainWords = 0;
45 size_t HeapRegion::GrainBytes = 0;
46 size_t HeapRegion::GrainWords = 0;
47 size_t HeapRegion::CardsPerRegion = 0;
48
49 HeapRegionDCTOC::HeapRegionDCTOC(G1CollectedHeap* g1,
50 HeapRegion* hr, ExtendedOopClosure* cl,
51 CardTableModRefBS::PrecisionStyle precision,
52 FilterKind fk) :
53 DirtyCardToOopClosure(hr, cl, precision, NULL),
54 _hr(hr), _fk(fk), _g1(g1) { }
55
56 FilterOutOfRegionClosure::FilterOutOfRegionClosure(HeapRegion* r,
57 OopClosure* oc) :
58 _r_bottom(r->bottom()), _r_end(r->end()), _oc(oc) { }
59
60 template<class ClosureType>
61 HeapWord* walk_mem_region_loop(ClosureType* cl, G1CollectedHeap* g1h,
62 HeapRegion* hr,
63 HeapWord* cur, HeapWord* top) {
64 oop cur_oop = oop(cur);
65 size_t oop_size = hr->block_size(cur);
66 HeapWord* next_obj = cur + oop_size;
67 while (next_obj < top) {
68 // Keep filtering the remembered set.
69 if (!g1h->is_obj_dead(cur_oop, hr)) {
70 // Bottom lies entirely below top, so we can call the
71 // non-memRegion version of oop_iterate below.
72 cur_oop->oop_iterate(cl);
73 }
74 cur = next_obj;
75 cur_oop = oop(cur);
76 oop_size = hr->block_size(cur);
77 next_obj = cur + oop_size;
78 }
79 return cur;
80 }
81
82 void HeapRegionDCTOC::walk_mem_region(MemRegion mr,
83 HeapWord* bottom,
84 HeapWord* top) {
85 G1CollectedHeap* g1h = _g1;
86 size_t oop_size;
87 ExtendedOopClosure* cl2 = NULL;
88
89 FilterIntoCSClosure intoCSFilt(this, g1h, _cl);
90 FilterOutOfRegionClosure outOfRegionFilt(_hr, _cl);
91
92 switch (_fk) {
93 case NoFilterKind: cl2 = _cl; break;
94 case IntoCSFilterKind: cl2 = &intoCSFilt; break;
95 case OutOfRegionFilterKind: cl2 = &outOfRegionFilt; break;
96 default: ShouldNotReachHere();
97 }
98
99 // Start filtering what we add to the remembered set. If the object is
100 // not considered dead, either because it is marked (in the mark bitmap)
101 // or it was allocated after marking finished, then we add it. Otherwise
102 // we can safely ignore the object.
103 if (!g1h->is_obj_dead(oop(bottom), _hr)) {
104 oop_size = oop(bottom)->oop_iterate(cl2, mr);
105 } else {
106 oop_size = _hr->block_size(bottom);
107 }
108
109 bottom += oop_size;
110
111 if (bottom < top) {
112 // We replicate the loop below for several kinds of possible filters.
113 switch (_fk) {
114 case NoFilterKind:
115 bottom = walk_mem_region_loop(_cl, g1h, _hr, bottom, top);
116 break;
117
118 case IntoCSFilterKind: {
119 FilterIntoCSClosure filt(this, g1h, _cl);
120 bottom = walk_mem_region_loop(&filt, g1h, _hr, bottom, top);
121 break;
122 }
123
124 case OutOfRegionFilterKind: {
125 FilterOutOfRegionClosure filt(_hr, _cl);
126 bottom = walk_mem_region_loop(&filt, g1h, _hr, bottom, top);
127 break;
128 }
129
130 default:
131 ShouldNotReachHere();
132 }
133
134 // Last object. Need to do dead-obj filtering here too.
135 if (!g1h->is_obj_dead(oop(bottom), _hr)) {
136 oop(bottom)->oop_iterate(cl2, mr);
137 }
138 }
139 }
140
141 // Minimum region size; we won't go lower than that.
142 // We might want to decrease this in the future, to deal with small
143 // heaps a bit more efficiently.
144 #define MIN_REGION_SIZE ( 1024 * 1024 )
145
146 // Maximum region size; we don't go higher than that. There's a good
147 // reason for having an upper bound. We don't want regions to get too
148 // large, otherwise cleanup's effectiveness would decrease as there
149 // will be fewer opportunities to find totally empty regions after
150 // marking.
151 #define MAX_REGION_SIZE ( 32 * 1024 * 1024 )
152
153 // The automatic region size calculation will try to have around this
154 // many regions in the heap (based on the min heap size).
155 #define TARGET_REGION_NUMBER 2048
156
157 size_t HeapRegion::max_region_size() {
158 return (size_t)MAX_REGION_SIZE;
159 }
160
161 void HeapRegion::setup_heap_region_size(size_t initial_heap_size, size_t max_heap_size) {
162 uintx region_size = G1HeapRegionSize;
163 if (FLAG_IS_DEFAULT(G1HeapRegionSize)) {
164 size_t average_heap_size = (initial_heap_size + max_heap_size) / 2;
165 region_size = MAX2(average_heap_size / TARGET_REGION_NUMBER,
166 (uintx) MIN_REGION_SIZE);
167 }
168
169 int region_size_log = log2_long((jlong) region_size);
170 // Recalculate the region size to make sure it's a power of
171 // 2. This means that region_size is the largest power of 2 that's
172 // <= what we've calculated so far.
173 region_size = ((uintx)1 << region_size_log);
174
175 // Now make sure that we don't go over or under our limits.
176 if (region_size < MIN_REGION_SIZE) {
177 region_size = MIN_REGION_SIZE;
178 } else if (region_size > MAX_REGION_SIZE) {
179 region_size = MAX_REGION_SIZE;
180 }
181
182 // And recalculate the log.
183 region_size_log = log2_long((jlong) region_size);
184
185 // Now, set up the globals.
186 guarantee(LogOfHRGrainBytes == 0, "we should only set it once");
187 LogOfHRGrainBytes = region_size_log;
188
189 guarantee(LogOfHRGrainWords == 0, "we should only set it once");
190 LogOfHRGrainWords = LogOfHRGrainBytes - LogHeapWordSize;
191
192 guarantee(GrainBytes == 0, "we should only set it once");
193 // The cast to int is safe, given that we've bounded region_size by
194 // MIN_REGION_SIZE and MAX_REGION_SIZE.
195 GrainBytes = (size_t)region_size;
196
197 guarantee(GrainWords == 0, "we should only set it once");
198 GrainWords = GrainBytes >> LogHeapWordSize;
199 guarantee((size_t) 1 << LogOfHRGrainWords == GrainWords, "sanity");
200
201 guarantee(CardsPerRegion == 0, "we should only set it once");
202 CardsPerRegion = GrainBytes >> CardTableModRefBS::card_shift;
203 }
204
205 void HeapRegion::reset_after_compaction() {
206 G1OffsetTableContigSpace::reset_after_compaction();
207 // After a compaction the mark bitmap is invalid, so we must
208 // treat all objects as being inside the unmarked area.
209 zero_marked_bytes();
210 init_top_at_mark_start();
211 }
212
213 void HeapRegion::hr_clear(bool par, bool clear_space, bool locked) {
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_free();
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 _type.set_starts_humongous();
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 _type.set_continues_humongous();
289 _humongous_start_region = first_hr;
290 }
291
292 void HeapRegion::clear_humongous() {
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_start_region = NULL;
309 }
310
311 bool HeapRegion::claimHeapRegion(jint claimValue) {
312 jint current = _claimed;
313 if (current != claimValue) {
314 jint res = Atomic::cmpxchg(claimValue, &_claimed, current);
315 if (res == current) {
316 return true;
317 }
318 }
319 return false;
320 }
321
322 HeapRegion::HeapRegion(uint hrm_index,
323 G1BlockOffsetSharedArray* sharedOffsetArray,
324 MemRegion mr) :
325 G1OffsetTableContigSpace(sharedOffsetArray, mr),
326 _hrm_index(hrm_index),
327 _humongous_start_region(NULL),
328 _in_collection_set(false),
329 _next_in_special_set(NULL),
330 _claimed(InitialClaimValue), _evacuation_failed(false),
331 _prev_marked_bytes(0), _next_marked_bytes(0), _gc_efficiency(0.0),
332 _next_young_region(NULL),
333 _next_dirty_cards_region(NULL), _next(NULL), _prev(NULL),
334 #ifdef ASSERT
335 _containing_set(NULL),
336 #endif // ASSERT
337 _young_index_in_cset(-1), _surv_rate_group(NULL), _age_index(-1),
338 _rem_set(NULL), _recorded_rs_length(0), _predicted_elapsed_time_ms(0),
339 _predicted_bytes_to_copy(0)
340 {
341 _rem_set = new HeapRegionRemSet(sharedOffsetArray, this);
342 assert(HeapRegionRemSet::num_par_rem_sets() > 0, "Invariant.");
343
344 initialize(mr);
345 }
346
347 void HeapRegion::initialize(MemRegion mr, bool clear_space, bool mangle_space) {
348 assert(_rem_set->is_empty(), "Remembered set must be empty");
349
350 G1OffsetTableContigSpace::initialize(mr, clear_space, mangle_space);
351
352 hr_clear(false /*par*/, false /*clear_space*/);
353 set_top(bottom());
354 record_top_and_timestamp();
355
356 assert(mr.end() == orig_end(),
357 err_msg("Given region end address " PTR_FORMAT " should match exactly "
358 "bottom plus one region size, i.e. " PTR_FORMAT,
359 p2i(mr.end()), p2i(orig_end())));
360 }
361
362 CompactibleSpace* HeapRegion::next_compaction_space() const {
363 return G1CollectedHeap::heap()->next_compaction_region(this);
364 }
365
366 void HeapRegion::note_self_forwarding_removal_start(bool during_initial_mark,
367 bool during_conc_mark) {
368 // We always recreate the prev marking info and we'll explicitly
369 // mark all objects we find to be self-forwarded on the prev
370 // bitmap. So all objects need to be below PTAMS.
371 _prev_marked_bytes = 0;
372
373 if (during_initial_mark) {
374 // During initial-mark, we'll also explicitly mark all objects
375 // we find to be self-forwarded on the next bitmap. So all
376 // objects need to be below NTAMS.
377 _next_top_at_mark_start = top();
378 _next_marked_bytes = 0;
379 } else if (during_conc_mark) {
380 // During concurrent mark, all objects in the CSet (including
381 // the ones we find to be self-forwarded) are implicitly live.
382 // So all objects need to be above NTAMS.
383 _next_top_at_mark_start = bottom();
384 _next_marked_bytes = 0;
385 }
386 }
387
388 void HeapRegion::note_self_forwarding_removal_end(bool during_initial_mark,
389 bool during_conc_mark,
390 size_t marked_bytes) {
391 assert(0 <= marked_bytes && marked_bytes <= used(),
392 err_msg("marked: "SIZE_FORMAT" used: "SIZE_FORMAT,
393 marked_bytes, used()));
394 _prev_top_at_mark_start = top();
395 _prev_marked_bytes = marked_bytes;
396 }
397
398 HeapWord*
399 HeapRegion::object_iterate_mem_careful(MemRegion mr,
400 ObjectClosure* cl) {
401 G1CollectedHeap* g1h = G1CollectedHeap::heap();
402 // We used to use "block_start_careful" here. But we're actually happy
403 // to update the BOT while we do this...
404 HeapWord* cur = block_start(mr.start());
405 mr = mr.intersection(used_region());
406 if (mr.is_empty()) return NULL;
407 // Otherwise, find the obj that extends onto mr.start().
408
409 assert(cur <= mr.start()
410 && (oop(cur)->klass_or_null() == NULL ||
411 cur + oop(cur)->size() > mr.start()),
412 "postcondition of block_start");
413 oop obj;
414 while (cur < mr.end()) {
415 obj = oop(cur);
416 if (obj->klass_or_null() == NULL) {
417 // Ran into an unparseable point.
418 return cur;
419 } else if (!g1h->is_obj_dead(obj)) {
420 cl->do_object(obj);
421 }
422 cur += block_size(cur);
423 }
424 return NULL;
425 }
426
427 HeapWord*
428 HeapRegion::
429 oops_on_card_seq_iterate_careful(MemRegion mr,
430 FilterOutOfRegionClosure* cl,
431 bool filter_young,
432 jbyte* card_ptr) {
433 // Currently, we should only have to clean the card if filter_young
434 // is true and vice versa.
435 if (filter_young) {
436 assert(card_ptr != NULL, "pre-condition");
437 } else {
438 assert(card_ptr == NULL, "pre-condition");
439 }
440 G1CollectedHeap* g1h = G1CollectedHeap::heap();
441
442 // If we're within a stop-world GC, then we might look at a card in a
443 // GC alloc region that extends onto a GC LAB, which may not be
444 // parseable. Stop such at the "saved_mark" of the region.
445 if (g1h->is_gc_active()) {
446 mr = mr.intersection(used_region_at_save_marks());
447 } else {
448 mr = mr.intersection(used_region());
449 }
450 if (mr.is_empty()) return NULL;
451 // Otherwise, find the obj that extends onto mr.start().
452
453 // The intersection of the incoming mr (for the card) and the
454 // allocated part of the region is non-empty. This implies that
455 // we have actually allocated into this region. The code in
456 // G1CollectedHeap.cpp that allocates a new region sets the
457 // is_young tag on the region before allocating. Thus we
458 // safely know if this region is young.
459 if (is_young() && filter_young) {
460 return NULL;
461 }
462
463 assert(!is_young(), "check value of filter_young");
464
465 // We can only clean the card here, after we make the decision that
466 // the card is not young. And we only clean the card if we have been
467 // asked to (i.e., card_ptr != NULL).
468 if (card_ptr != NULL) {
469 *card_ptr = CardTableModRefBS::clean_card_val();
470 // We must complete this write before we do any of the reads below.
471 OrderAccess::storeload();
472 }
473
474 // Cache the boundaries of the memory region in some const locals
475 HeapWord* const start = mr.start();
476 HeapWord* const end = mr.end();
477
478 // We used to use "block_start_careful" here. But we're actually happy
479 // to update the BOT while we do this...
480 HeapWord* cur = block_start(start);
481 assert(cur <= start, "Postcondition");
482
483 oop obj;
484
485 HeapWord* next = cur;
486 while (next <= start) {
487 cur = next;
488 obj = oop(cur);
489 if (obj->klass_or_null() == NULL) {
490 // Ran into an unparseable point.
491 return cur;
492 }
493 // Otherwise...
494 next = cur + block_size(cur);
495 }
496
497 // If we finish the above loop...We have a parseable object that
498 // begins on or before the start of the memory region, and ends
499 // inside or spans the entire region.
500
501 assert(obj == oop(cur), "sanity");
502 assert(cur <= start, "Loop postcondition");
503 assert(obj->klass_or_null() != NULL, "Loop postcondition");
504 assert((cur + block_size(cur)) > start, "Loop postcondition");
505
506 if (!g1h->is_obj_dead(obj)) {
507 obj->oop_iterate(cl, mr);
508 }
509
510 while (cur < end) {
511 obj = oop(cur);
512 if (obj->klass_or_null() == NULL) {
513 // Ran into an unparseable point.
514 return cur;
515 };
516
517 // Otherwise:
518 next = cur + block_size(cur);
519
520 if (!g1h->is_obj_dead(obj)) {
521 if (next < end || !obj->is_objArray()) {
522 // This object either does not span the MemRegion
523 // boundary, or if it does it's not an array.
524 // Apply closure to whole object.
525 obj->oop_iterate(cl);
526 } else {
527 // This obj is an array that spans the boundary.
528 // Stop at the boundary.
529 obj->oop_iterate(cl, mr);
530 }
531 }
532 cur = next;
533 }
534 return NULL;
535 }
536
537 // Code roots support
538
539 void HeapRegion::add_strong_code_root(nmethod* nm) {
540 HeapRegionRemSet* hrrs = rem_set();
541 hrrs->add_strong_code_root(nm);
542 }
543
544 void HeapRegion::add_strong_code_root_locked(nmethod* nm) {
545 assert_locked_or_safepoint(CodeCache_lock);
546 HeapRegionRemSet* hrrs = rem_set();
547 hrrs->add_strong_code_root_locked(nm);
548 }
549
550 void HeapRegion::remove_strong_code_root(nmethod* nm) {
551 HeapRegionRemSet* hrrs = rem_set();
552 hrrs->remove_strong_code_root(nm);
553 }
554
555 void HeapRegion::strong_code_roots_do(CodeBlobClosure* blk) const {
556 HeapRegionRemSet* hrrs = rem_set();
557 hrrs->strong_code_roots_do(blk);
558 }
559
560 class VerifyStrongCodeRootOopClosure: public OopClosure {
561 const HeapRegion* _hr;
562 nmethod* _nm;
563 bool _failures;
564 bool _has_oops_in_region;
565
566 template <class T> void do_oop_work(T* p) {
567 T heap_oop = oopDesc::load_heap_oop(p);
568 if (!oopDesc::is_null(heap_oop)) {
569 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
570
571 // Note: not all the oops embedded in the nmethod are in the
572 // current region. We only look at those which are.
573 if (_hr->is_in(obj)) {
574 // Object is in the region. Check that its less than top
575 if (_hr->top() <= (HeapWord*)obj) {
576 // Object is above top
577 gclog_or_tty->print_cr("Object "PTR_FORMAT" in region "
578 "["PTR_FORMAT", "PTR_FORMAT") is above "
579 "top "PTR_FORMAT,
580 (void *)obj, _hr->bottom(), _hr->end(), _hr->top());
581 _failures = true;
582 return;
583 }
584 // Nmethod has at least one oop in the current region
585 _has_oops_in_region = true;
586 }
587 }
588 }
589
590 public:
591 VerifyStrongCodeRootOopClosure(const HeapRegion* hr, nmethod* nm):
592 _hr(hr), _failures(false), _has_oops_in_region(false) {}
593
594 void do_oop(narrowOop* p) { do_oop_work(p); }
595 void do_oop(oop* p) { do_oop_work(p); }
596
597 bool failures() { return _failures; }
598 bool has_oops_in_region() { return _has_oops_in_region; }
599 };
600
601 class VerifyStrongCodeRootCodeBlobClosure: public CodeBlobClosure {
602 const HeapRegion* _hr;
603 bool _failures;
604 public:
605 VerifyStrongCodeRootCodeBlobClosure(const HeapRegion* hr) :
606 _hr(hr), _failures(false) {}
607
608 void do_code_blob(CodeBlob* cb) {
609 nmethod* nm = (cb == NULL) ? NULL : cb->as_nmethod_or_null();
610 if (nm != NULL) {
611 // Verify that the nemthod is live
612 if (!nm->is_alive()) {
613 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] has dead nmethod "
614 PTR_FORMAT" in its strong code roots",
615 _hr->bottom(), _hr->end(), nm);
616 _failures = true;
617 } else {
618 VerifyStrongCodeRootOopClosure oop_cl(_hr, nm);
619 nm->oops_do(&oop_cl);
620 if (!oop_cl.has_oops_in_region()) {
621 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] has nmethod "
622 PTR_FORMAT" in its strong code roots "
623 "with no pointers into region",
624 _hr->bottom(), _hr->end(), nm);
625 _failures = true;
626 } else if (oop_cl.failures()) {
627 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] has other "
628 "failures for nmethod "PTR_FORMAT,
629 _hr->bottom(), _hr->end(), nm);
630 _failures = true;
631 }
632 }
633 }
634 }
635
636 bool failures() { return _failures; }
637 };
638
639 void HeapRegion::verify_strong_code_roots(VerifyOption vo, bool* failures) const {
640 if (!G1VerifyHeapRegionCodeRoots) {
641 // We're not verifying code roots.
642 return;
643 }
644 if (vo == VerifyOption_G1UseMarkWord) {
645 // Marking verification during a full GC is performed after class
646 // unloading, code cache unloading, etc so the strong code roots
647 // attached to each heap region are in an inconsistent state. They won't
648 // be consistent until the strong code roots are rebuilt after the
649 // actual GC. Skip verifying the strong code roots in this particular
650 // time.
651 assert(VerifyDuringGC, "only way to get here");
652 return;
653 }
654
655 HeapRegionRemSet* hrrs = rem_set();
656 size_t strong_code_roots_length = hrrs->strong_code_roots_list_length();
657
658 // if this region is empty then there should be no entries
659 // on its strong code root list
660 if (is_empty()) {
661 if (strong_code_roots_length > 0) {
662 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] is empty "
663 "but has "SIZE_FORMAT" code root entries",
664 bottom(), end(), strong_code_roots_length);
665 *failures = true;
666 }
667 return;
668 }
669
670 if (continuesHumongous()) {
671 if (strong_code_roots_length > 0) {
672 gclog_or_tty->print_cr("region "HR_FORMAT" is a continuation of a humongous "
673 "region but has "SIZE_FORMAT" code root entries",
674 HR_FORMAT_PARAMS(this), strong_code_roots_length);
675 *failures = true;
676 }
677 return;
678 }
679
680 VerifyStrongCodeRootCodeBlobClosure cb_cl(this);
681 strong_code_roots_do(&cb_cl);
682
683 if (cb_cl.failures()) {
684 *failures = true;
685 }
686 }
687
688 void HeapRegion::print() const { print_on(gclog_or_tty); }
689 void HeapRegion::print_on(outputStream* st) const {
690 st->print(" %2s", get_short_type_str());
691 if (in_collection_set())
692 st->print(" CS");
693 else
694 st->print(" ");
695 st->print(" TS %5d", _gc_time_stamp);
696 st->print(" PTAMS "PTR_FORMAT" NTAMS "PTR_FORMAT,
697 prev_top_at_mark_start(), next_top_at_mark_start());
698 G1OffsetTableContigSpace::print_on(st);
699 }
700
701 class VerifyLiveClosure: public OopClosure {
702 private:
703 G1CollectedHeap* _g1h;
704 CardTableModRefBS* _bs;
705 oop _containing_obj;
706 bool _failures;
707 int _n_failures;
708 VerifyOption _vo;
709 public:
710 // _vo == UsePrevMarking -> use "prev" marking information,
711 // _vo == UseNextMarking -> use "next" marking information,
712 // _vo == UseMarkWord -> use mark word from object header.
713 VerifyLiveClosure(G1CollectedHeap* g1h, VerifyOption vo) :
714 _g1h(g1h), _bs(NULL), _containing_obj(NULL),
715 _failures(false), _n_failures(0), _vo(vo)
716 {
717 BarrierSet* bs = _g1h->barrier_set();
718 if (bs->is_a(BarrierSet::CardTableModRef))
719 _bs = (CardTableModRefBS*)bs;
720 }
721
722 void set_containing_obj(oop obj) {
723 _containing_obj = obj;
724 }
725
726 bool failures() { return _failures; }
727 int n_failures() { return _n_failures; }
728
729 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
730 virtual void do_oop( oop* p) { do_oop_work(p); }
731
732 void print_object(outputStream* out, oop obj) {
733 #ifdef PRODUCT
734 Klass* k = obj->klass();
735 const char* class_name = InstanceKlass::cast(k)->external_name();
736 out->print_cr("class name %s", class_name);
737 #else // PRODUCT
738 obj->print_on(out);
739 #endif // PRODUCT
740 }
741
742 template <class T>
743 void do_oop_work(T* p) {
744 assert(_containing_obj != NULL, "Precondition");
745 assert(!_g1h->is_obj_dead_cond(_containing_obj, _vo),
746 "Precondition");
747 T heap_oop = oopDesc::load_heap_oop(p);
748 if (!oopDesc::is_null(heap_oop)) {
749 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
750 bool failed = false;
751 if (!_g1h->is_in_closed_subset(obj) || _g1h->is_obj_dead_cond(obj, _vo)) {
752 MutexLockerEx x(ParGCRareEvent_lock,
753 Mutex::_no_safepoint_check_flag);
754
755 if (!_failures) {
756 gclog_or_tty->cr();
757 gclog_or_tty->print_cr("----------");
758 }
759 if (!_g1h->is_in_closed_subset(obj)) {
760 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
761 gclog_or_tty->print_cr("Field "PTR_FORMAT
762 " of live obj "PTR_FORMAT" in region "
763 "["PTR_FORMAT", "PTR_FORMAT")",
764 p, (void*) _containing_obj,
765 from->bottom(), from->end());
766 print_object(gclog_or_tty, _containing_obj);
767 gclog_or_tty->print_cr("points to obj "PTR_FORMAT" not in the heap",
768 (void*) obj);
769 } else {
770 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
771 HeapRegion* to = _g1h->heap_region_containing((HeapWord*)obj);
772 gclog_or_tty->print_cr("Field "PTR_FORMAT
773 " of live obj "PTR_FORMAT" in region "
774 "["PTR_FORMAT", "PTR_FORMAT")",
775 p, (void*) _containing_obj,
776 from->bottom(), from->end());
777 print_object(gclog_or_tty, _containing_obj);
778 gclog_or_tty->print_cr("points to dead obj "PTR_FORMAT" in region "
779 "["PTR_FORMAT", "PTR_FORMAT")",
780 (void*) obj, to->bottom(), to->end());
781 print_object(gclog_or_tty, obj);
782 }
783 gclog_or_tty->print_cr("----------");
784 gclog_or_tty->flush();
785 _failures = true;
786 failed = true;
787 _n_failures++;
788 }
789
790 if (!_g1h->full_collection() || G1VerifyRSetsDuringFullGC) {
791 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
792 HeapRegion* to = _g1h->heap_region_containing(obj);
793 if (from != NULL && to != NULL &&
794 from != to &&
795 !to->isHumongous()) {
796 jbyte cv_obj = *_bs->byte_for_const(_containing_obj);
797 jbyte cv_field = *_bs->byte_for_const(p);
798 const jbyte dirty = CardTableModRefBS::dirty_card_val();
799
800 bool is_bad = !(from->is_young()
801 || to->rem_set()->contains_reference(p)
802 || !G1HRRSFlushLogBuffersOnVerify && // buffers were not flushed
803 (_containing_obj->is_objArray() ?
804 cv_field == dirty
805 : cv_obj == dirty || cv_field == dirty));
806 if (is_bad) {
807 MutexLockerEx x(ParGCRareEvent_lock,
808 Mutex::_no_safepoint_check_flag);
809
810 if (!_failures) {
811 gclog_or_tty->cr();
812 gclog_or_tty->print_cr("----------");
813 }
814 gclog_or_tty->print_cr("Missing rem set entry:");
815 gclog_or_tty->print_cr("Field "PTR_FORMAT" "
816 "of obj "PTR_FORMAT", "
817 "in region "HR_FORMAT,
818 p, (void*) _containing_obj,
819 HR_FORMAT_PARAMS(from));
820 _containing_obj->print_on(gclog_or_tty);
821 gclog_or_tty->print_cr("points to obj "PTR_FORMAT" "
822 "in region "HR_FORMAT,
823 (void*) obj,
824 HR_FORMAT_PARAMS(to));
825 obj->print_on(gclog_or_tty);
826 gclog_or_tty->print_cr("Obj head CTE = %d, field CTE = %d.",
827 cv_obj, cv_field);
828 gclog_or_tty->print_cr("----------");
829 gclog_or_tty->flush();
830 _failures = true;
831 if (!failed) _n_failures++;
832 }
833 }
834 }
835 }
836 }
837 };
838
839 // This really ought to be commoned up into OffsetTableContigSpace somehow.
840 // We would need a mechanism to make that code skip dead objects.
841
842 void HeapRegion::verify(VerifyOption vo,
843 bool* failures) const {
844 G1CollectedHeap* g1 = G1CollectedHeap::heap();
845 *failures = false;
846 HeapWord* p = bottom();
847 HeapWord* prev_p = NULL;
848 VerifyLiveClosure vl_cl(g1, vo);
849 bool is_humongous = isHumongous();
850 size_t object_num = 0;
851 while (p < top()) {
852 oop obj = oop(p);
853 size_t obj_size = block_size(p);
854 object_num += 1;
855
856 if (is_humongous != g1->isHumongous(obj_size) &&
857 !g1->is_obj_dead(obj, this)) { // Dead objects may have bigger block_size since they span several objects.
858 gclog_or_tty->print_cr("obj "PTR_FORMAT" is of %shumongous size ("
859 SIZE_FORMAT" words) in a %shumongous region",
860 p, g1->isHumongous(obj_size) ? "" : "non-",
861 obj_size, is_humongous ? "" : "non-");
862 *failures = true;
863 return;
864 }
865
866 if (!g1->is_obj_dead_cond(obj, this, vo)) {
867 if (obj->is_oop()) {
868 Klass* klass = obj->klass();
869 bool is_metaspace_object = Metaspace::contains(klass) ||
870 (vo == VerifyOption_G1UsePrevMarking &&
871 ClassLoaderDataGraph::unload_list_contains(klass));
872 if (!is_metaspace_object) {
873 gclog_or_tty->print_cr("klass "PTR_FORMAT" of object "PTR_FORMAT" "
874 "not metadata", klass, (void *)obj);
875 *failures = true;
876 return;
877 } else if (!klass->is_klass()) {
878 gclog_or_tty->print_cr("klass "PTR_FORMAT" of object "PTR_FORMAT" "
879 "not a klass", klass, (void *)obj);
880 *failures = true;
881 return;
882 } else {
883 vl_cl.set_containing_obj(obj);
884 obj->oop_iterate_no_header(&vl_cl);
885 if (vl_cl.failures()) {
886 *failures = true;
887 }
888 if (G1MaxVerifyFailures >= 0 &&
889 vl_cl.n_failures() >= G1MaxVerifyFailures) {
890 return;
891 }
892 }
893 } else {
894 gclog_or_tty->print_cr(PTR_FORMAT" no an oop", (void *)obj);
895 *failures = true;
896 return;
897 }
898 }
899 prev_p = p;
900 p += obj_size;
901 }
902
903 if (!is_young() && !is_empty()) {
904 _offsets.verify();
905 }
906
907 if (p != top()) {
908 gclog_or_tty->print_cr("end of last object "PTR_FORMAT" "
909 "does not match top "PTR_FORMAT, p, top());
910 *failures = true;
911 return;
912 }
913
914 HeapWord* the_end = end();
915 assert(p == top(), "it should still hold");
916 // Do some extra BOT consistency checking for addresses in the
917 // range [top, end). BOT look-ups in this range should yield
918 // top. No point in doing that if top == end (there's nothing there).
919 if (p < the_end) {
920 // Look up top
921 HeapWord* addr_1 = p;
922 HeapWord* b_start_1 = _offsets.block_start_const(addr_1);
923 if (b_start_1 != p) {
924 gclog_or_tty->print_cr("BOT look up for top: "PTR_FORMAT" "
925 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
926 addr_1, b_start_1, p);
927 *failures = true;
928 return;
929 }
930
931 // Look up top + 1
932 HeapWord* addr_2 = p + 1;
933 if (addr_2 < the_end) {
934 HeapWord* b_start_2 = _offsets.block_start_const(addr_2);
935 if (b_start_2 != p) {
936 gclog_or_tty->print_cr("BOT look up for top + 1: "PTR_FORMAT" "
937 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
938 addr_2, b_start_2, p);
939 *failures = true;
940 return;
941 }
942 }
943
944 // Look up an address between top and end
945 size_t diff = pointer_delta(the_end, p) / 2;
946 HeapWord* addr_3 = p + diff;
947 if (addr_3 < the_end) {
948 HeapWord* b_start_3 = _offsets.block_start_const(addr_3);
949 if (b_start_3 != p) {
950 gclog_or_tty->print_cr("BOT look up for top + diff: "PTR_FORMAT" "
951 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
952 addr_3, b_start_3, p);
953 *failures = true;
954 return;
955 }
956 }
957
958 // Look up end - 1
959 HeapWord* addr_4 = the_end - 1;
960 HeapWord* b_start_4 = _offsets.block_start_const(addr_4);
961 if (b_start_4 != p) {
962 gclog_or_tty->print_cr("BOT look up for end - 1: "PTR_FORMAT" "
963 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
964 addr_4, b_start_4, p);
965 *failures = true;
966 return;
967 }
968 }
969
970 if (is_humongous && object_num > 1) {
971 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] is humongous "
972 "but has "SIZE_FORMAT", objects",
973 bottom(), end(), object_num);
974 *failures = true;
975 return;
976 }
977
978 verify_strong_code_roots(vo, failures);
979 }
980
981 void HeapRegion::verify() const {
982 bool dummy = false;
983 verify(VerifyOption_G1UsePrevMarking, /* failures */ &dummy);
984 }
985
986 void HeapRegion::prepare_for_compaction(CompactPoint* cp) {
987 scan_and_forward(this, cp);
988 }
989
990 // G1OffsetTableContigSpace code; copied from space.cpp. Hope this can go
991 // away eventually.
992
993 void G1OffsetTableContigSpace::clear(bool mangle_space) {
994 set_top(bottom());
995 set_saved_mark_word(bottom());
996 CompactibleSpace::clear(mangle_space);
997 reset_bot();
998 }
999
1000 void G1OffsetTableContigSpace::set_bottom(HeapWord* new_bottom) {
1001 Space::set_bottom(new_bottom);
1002 _offsets.set_bottom(new_bottom);
1003 }
1004
1005 void G1OffsetTableContigSpace::set_end(HeapWord* new_end) {
1006 Space::set_end(new_end);
1007 _offsets.resize(new_end - bottom());
1008 }
1009
1010 void G1OffsetTableContigSpace::print() const {
1011 print_short();
1012 gclog_or_tty->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", "
1013 INTPTR_FORMAT ", " INTPTR_FORMAT ")",
1014 bottom(), top(), _offsets.threshold(), end());
1015 }
1016
1017 HeapWord* G1OffsetTableContigSpace::initialize_threshold() {
1018 return _offsets.initialize_threshold();
1019 }
1020
1021 HeapWord* G1OffsetTableContigSpace::cross_threshold(HeapWord* start,
1022 HeapWord* end) {
1023 _offsets.alloc_block(start, end);
1024 return _offsets.threshold();
1025 }
1026
1027 HeapWord* G1OffsetTableContigSpace::saved_mark_word() const {
1028 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1029 assert( _gc_time_stamp <= g1h->get_gc_time_stamp(), "invariant" );
1030 if (_gc_time_stamp < g1h->get_gc_time_stamp())
1031 return top();
1032 else
1033 return Space::saved_mark_word();
1034 }
1035
1036 void G1OffsetTableContigSpace::record_top_and_timestamp() {
1037 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1038 unsigned curr_gc_time_stamp = g1h->get_gc_time_stamp();
1039
1040 if (_gc_time_stamp < curr_gc_time_stamp) {
1041 // The order of these is important, as another thread might be
1042 // about to start scanning this region. If it does so after
1043 // set_saved_mark and before _gc_time_stamp = ..., then the latter
1044 // will be false, and it will pick up top() as the high water mark
1045 // of region. If it does so after _gc_time_stamp = ..., then it
1046 // will pick up the right saved_mark_word() as the high water mark
1047 // of the region. Either way, the behavior will be correct.
1048 Space::set_saved_mark_word(top());
1049 OrderAccess::storestore();
1050 _gc_time_stamp = curr_gc_time_stamp;
1051 // No need to do another barrier to flush the writes above. If
1052 // this is called in parallel with other threads trying to
1053 // allocate into the region, the caller should call this while
1054 // holding a lock and when the lock is released the writes will be
1055 // flushed.
1056 }
1057 }
1058
1059 void G1OffsetTableContigSpace::safe_object_iterate(ObjectClosure* blk) {
1060 object_iterate(blk);
1061 }
1062
1063 void G1OffsetTableContigSpace::object_iterate(ObjectClosure* blk) {
1064 HeapWord* p = bottom();
1065 while (p < top()) {
1066 if (block_is_obj(p)) {
1067 blk->do_object(oop(p));
1068 }
1069 p += block_size(p);
1070 }
1071 }
1072
1073 G1OffsetTableContigSpace::
1074 G1OffsetTableContigSpace(G1BlockOffsetSharedArray* sharedOffsetArray,
1075 MemRegion mr) :
1076 _offsets(sharedOffsetArray, mr),
1077 _par_alloc_lock(Mutex::leaf, "OffsetTableContigSpace par alloc lock", true),
1078 _gc_time_stamp(0)
1079 {
1080 _offsets.set_space(this);
1081 }
1082
1083 void G1OffsetTableContigSpace::initialize(MemRegion mr, bool clear_space, bool mangle_space) {
1084 CompactibleSpace::initialize(mr, clear_space, mangle_space);
1085 _top = bottom();
1086 reset_bot();
1087 }
1088