1 /*
2 * Copyright (c) 2001, 2015, 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/heapRegionBounds.inline.hpp"
32 #include "gc_implementation/g1/heapRegionRemSet.hpp"
33 #include "gc_implementation/g1/heapRegionManager.inline.hpp"
34 #include "gc_implementation/shared/liveRange.hpp"
35 #include "memory/genOopClosures.inline.hpp"
36 #include "memory/iterator.hpp"
37 #include "memory/space.inline.hpp"
38 #include "oops/oop.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 size_t HeapRegion::max_region_size() {
142 return HeapRegionBounds::max_size();
143 }
144
145 void HeapRegion::setup_heap_region_size(size_t initial_heap_size, size_t max_heap_size) {
146 uintx region_size = G1HeapRegionSize;
147 if (FLAG_IS_DEFAULT(G1HeapRegionSize)) {
148 size_t average_heap_size = (initial_heap_size + max_heap_size) / 2;
149 region_size = MAX2(average_heap_size / HeapRegionBounds::target_number(),
150 (uintx) HeapRegionBounds::min_size());
151 }
152
153 int region_size_log = log2_long((jlong) region_size);
154 // Recalculate the region size to make sure it's a power of
155 // 2. This means that region_size is the largest power of 2 that's
156 // <= what we've calculated so far.
157 region_size = ((uintx)1 << region_size_log);
158
159 // Now make sure that we don't go over or under our limits.
160 if (region_size < HeapRegionBounds::min_size()) {
161 region_size = HeapRegionBounds::min_size();
162 } else if (region_size > HeapRegionBounds::max_size()) {
163 region_size = HeapRegionBounds::max_size();
164 }
165
166 // And recalculate the log.
167 region_size_log = log2_long((jlong) region_size);
168
169 // Now, set up the globals.
170 guarantee(LogOfHRGrainBytes == 0, "we should only set it once");
171 LogOfHRGrainBytes = region_size_log;
172
173 guarantee(LogOfHRGrainWords == 0, "we should only set it once");
174 LogOfHRGrainWords = LogOfHRGrainBytes - LogHeapWordSize;
175
176 guarantee(GrainBytes == 0, "we should only set it once");
177 // The cast to int is safe, given that we've bounded region_size by
178 // MIN_REGION_SIZE and MAX_REGION_SIZE.
179 GrainBytes = (size_t)region_size;
180
181 guarantee(GrainWords == 0, "we should only set it once");
182 GrainWords = GrainBytes >> LogHeapWordSize;
183 guarantee((size_t) 1 << LogOfHRGrainWords == GrainWords, "sanity");
184
185 guarantee(CardsPerRegion == 0, "we should only set it once");
186 CardsPerRegion = GrainBytes >> CardTableModRefBS::card_shift;
187 }
188
189 void HeapRegion::reset_after_compaction() {
190 G1OffsetTableContigSpace::reset_after_compaction();
191 // After a compaction the mark bitmap is invalid, so we must
192 // treat all objects as being inside the unmarked area.
193 zero_marked_bytes();
194 init_top_at_mark_start();
195 }
196
197 void HeapRegion::hr_clear(bool par, bool clear_space, bool locked) {
198 assert(_humongous_start_region == NULL,
199 "we should have already filtered out humongous regions");
200 assert(_end == _orig_end,
201 "we should have already filtered out humongous regions");
202
203 _in_collection_set = false;
204
205 set_allocation_context(AllocationContext::system());
206 set_young_index_in_cset(-1);
207 uninstall_surv_rate_group();
208 set_free();
209 reset_pre_dummy_top();
210
211 if (!par) {
212 // If this is parallel, this will be done later.
213 HeapRegionRemSet* hrrs = rem_set();
214 if (locked) {
215 hrrs->clear_locked();
216 } else {
217 hrrs->clear();
218 }
219 _claimed = InitialClaimValue;
220 }
221 zero_marked_bytes();
222
223 _offsets.resize(HeapRegion::GrainWords);
224 init_top_at_mark_start();
225 if (clear_space) clear(SpaceDecorator::Mangle);
226 }
227
228 void HeapRegion::par_clear() {
229 assert(used() == 0, "the region should have been already cleared");
230 assert(capacity() == HeapRegion::GrainBytes, "should be back to normal");
231 HeapRegionRemSet* hrrs = rem_set();
232 hrrs->clear();
233 CardTableModRefBS* ct_bs =
234 (CardTableModRefBS*)G1CollectedHeap::heap()->barrier_set();
235 ct_bs->clear(MemRegion(bottom(), end()));
236 }
237
238 void HeapRegion::calc_gc_efficiency() {
239 // GC efficiency is the ratio of how much space would be
240 // reclaimed over how long we predict it would take to reclaim it.
241 G1CollectedHeap* g1h = G1CollectedHeap::heap();
242 G1CollectorPolicy* g1p = g1h->g1_policy();
243
244 // Retrieve a prediction of the elapsed time for this region for
245 // a mixed gc because the region will only be evacuated during a
246 // mixed gc.
247 double region_elapsed_time_ms =
248 g1p->predict_region_elapsed_time_ms(this, false /* for_young_gc */);
249 _gc_efficiency = (double) reclaimable_bytes() / region_elapsed_time_ms;
250 }
251
252 void HeapRegion::set_startsHumongous(HeapWord* new_top, HeapWord* new_end) {
253 assert(!isHumongous(), "sanity / pre-condition");
254 assert(end() == _orig_end,
255 "Should be normal before the humongous object allocation");
256 assert(top() == bottom(), "should be empty");
257 assert(bottom() <= new_top && new_top <= new_end, "pre-condition");
258
259 _type.set_starts_humongous();
260 _humongous_start_region = this;
261
262 set_end(new_end);
263 _offsets.set_for_starts_humongous(new_top);
264 }
265
266 void HeapRegion::set_continuesHumongous(HeapRegion* first_hr) {
267 assert(!isHumongous(), "sanity / pre-condition");
268 assert(end() == _orig_end,
269 "Should be normal before the humongous object allocation");
270 assert(top() == bottom(), "should be empty");
271 assert(first_hr->startsHumongous(), "pre-condition");
272
273 _type.set_continues_humongous();
274 _humongous_start_region = first_hr;
275 }
276
277 void HeapRegion::clear_humongous() {
278 assert(isHumongous(), "pre-condition");
279
280 if (startsHumongous()) {
281 assert(top() <= end(), "pre-condition");
282 set_end(_orig_end);
283 if (top() > end()) {
284 // at least one "continues humongous" region after it
285 set_top(end());
286 }
287 } else {
288 // continues humongous
289 assert(end() == _orig_end, "sanity");
290 }
291
292 assert(capacity() == HeapRegion::GrainBytes, "pre-condition");
293 _humongous_start_region = NULL;
294 }
295
296 bool HeapRegion::claimHeapRegion(jint claimValue) {
297 jint current = _claimed;
298 if (current != claimValue) {
299 jint res = Atomic::cmpxchg(claimValue, &_claimed, current);
300 if (res == current) {
301 return true;
302 }
303 }
304 return false;
305 }
306
307 HeapRegion::HeapRegion(uint hrm_index,
308 G1BlockOffsetSharedArray* sharedOffsetArray,
309 MemRegion mr) :
310 G1OffsetTableContigSpace(sharedOffsetArray, mr),
311 _hrm_index(hrm_index),
312 _allocation_context(AllocationContext::system()),
313 _humongous_start_region(NULL),
314 _in_collection_set(false),
315 _next_in_special_set(NULL), _orig_end(NULL),
316 _claimed(InitialClaimValue), _evacuation_failed(false),
317 _prev_marked_bytes(0), _next_marked_bytes(0), _gc_efficiency(0.0),
318 _next_young_region(NULL),
319 _next_dirty_cards_region(NULL), _next(NULL), _prev(NULL),
320 #ifdef ASSERT
321 _containing_set(NULL),
322 #endif // ASSERT
323 _young_index_in_cset(-1), _surv_rate_group(NULL), _age_index(-1),
324 _rem_set(NULL), _recorded_rs_length(0), _predicted_elapsed_time_ms(0),
325 _predicted_bytes_to_copy(0)
326 {
327 _rem_set = new HeapRegionRemSet(sharedOffsetArray, this);
328 assert(HeapRegionRemSet::num_par_rem_sets() > 0, "Invariant.");
329
330 initialize(mr);
331 }
332
333 void HeapRegion::initialize(MemRegion mr, bool clear_space, bool mangle_space) {
334 assert(_rem_set->is_empty(), "Remembered set must be empty");
335
336 G1OffsetTableContigSpace::initialize(mr, clear_space, mangle_space);
337
338 _orig_end = mr.end();
339 hr_clear(false /*par*/, false /*clear_space*/);
340 set_top(bottom());
341 record_timestamp();
342 }
343
344 CompactibleSpace* HeapRegion::next_compaction_space() const {
345 return G1CollectedHeap::heap()->next_compaction_region(this);
346 }
347
348 void HeapRegion::note_self_forwarding_removal_start(bool during_initial_mark,
349 bool during_conc_mark) {
350 // We always recreate the prev marking info and we'll explicitly
351 // mark all objects we find to be self-forwarded on the prev
352 // bitmap. So all objects need to be below PTAMS.
353 _prev_marked_bytes = 0;
354
355 if (during_initial_mark) {
356 // During initial-mark, we'll also explicitly mark all objects
357 // we find to be self-forwarded on the next bitmap. So all
358 // objects need to be below NTAMS.
359 _next_top_at_mark_start = top();
360 _next_marked_bytes = 0;
361 } else if (during_conc_mark) {
362 // During concurrent mark, all objects in the CSet (including
363 // the ones we find to be self-forwarded) are implicitly live.
364 // So all objects need to be above NTAMS.
365 _next_top_at_mark_start = bottom();
366 _next_marked_bytes = 0;
367 }
368 }
369
370 void HeapRegion::note_self_forwarding_removal_end(bool during_initial_mark,
371 bool during_conc_mark,
372 size_t marked_bytes) {
373 assert(0 <= marked_bytes && marked_bytes <= used(),
374 err_msg("marked: "SIZE_FORMAT" used: "SIZE_FORMAT,
375 marked_bytes, used()));
376 _prev_top_at_mark_start = top();
377 _prev_marked_bytes = marked_bytes;
378 }
379
380 HeapWord*
381 HeapRegion::object_iterate_mem_careful(MemRegion mr,
382 ObjectClosure* cl) {
383 G1CollectedHeap* g1h = G1CollectedHeap::heap();
384 // We used to use "block_start_careful" here. But we're actually happy
385 // to update the BOT while we do this...
386 HeapWord* cur = block_start(mr.start());
387 mr = mr.intersection(used_region());
388 if (mr.is_empty()) return NULL;
389 // Otherwise, find the obj that extends onto mr.start().
390
391 assert(cur <= mr.start()
392 && (oop(cur)->klass_or_null() == NULL ||
393 cur + oop(cur)->size() > mr.start()),
394 "postcondition of block_start");
395 oop obj;
396 while (cur < mr.end()) {
397 obj = oop(cur);
398 if (obj->klass_or_null() == NULL) {
399 // Ran into an unparseable point.
400 return cur;
401 } else if (!g1h->is_obj_dead(obj)) {
402 cl->do_object(obj);
403 }
404 if (cl->abort()) return cur;
405 // The check above must occur before the operation below, since an
406 // abort might invalidate the "size" operation.
407 cur += block_size(cur);
408 }
409 return NULL;
410 }
411
412 HeapWord*
413 HeapRegion::
414 oops_on_card_seq_iterate_careful(MemRegion mr,
415 FilterOutOfRegionClosure* cl,
416 bool filter_young,
417 jbyte* card_ptr) {
418 // Currently, we should only have to clean the card if filter_young
419 // is true and vice versa.
420 if (filter_young) {
421 assert(card_ptr != NULL, "pre-condition");
422 } else {
423 assert(card_ptr == NULL, "pre-condition");
424 }
425 G1CollectedHeap* g1h = G1CollectedHeap::heap();
426
427 // If we're within a stop-world GC, then we might look at a card in a
428 // GC alloc region that extends onto a GC LAB, which may not be
429 // parseable. Stop such at the "scan_top" of the region.
430 if (g1h->is_gc_active()) {
431 mr = mr.intersection(MemRegion(bottom(), scan_top()));
432 } else {
433 mr = mr.intersection(used_region());
434 }
435 if (mr.is_empty()) return NULL;
436 // Otherwise, find the obj that extends onto mr.start().
437
438 // The intersection of the incoming mr (for the card) and the
439 // allocated part of the region is non-empty. This implies that
440 // we have actually allocated into this region. The code in
441 // G1CollectedHeap.cpp that allocates a new region sets the
442 // is_young tag on the region before allocating. Thus we
443 // safely know if this region is young.
444 if (is_young() && filter_young) {
445 return NULL;
446 }
447
448 assert(!is_young(), "check value of filter_young");
449
450 // We can only clean the card here, after we make the decision that
451 // the card is not young. And we only clean the card if we have been
452 // asked to (i.e., card_ptr != NULL).
453 if (card_ptr != NULL) {
454 *card_ptr = CardTableModRefBS::clean_card_val();
455 // We must complete this write before we do any of the reads below.
456 OrderAccess::storeload();
457 }
458
459 // Cache the boundaries of the memory region in some const locals
460 HeapWord* const start = mr.start();
461 HeapWord* const end = mr.end();
462
463 // We used to use "block_start_careful" here. But we're actually happy
464 // to update the BOT while we do this...
465 HeapWord* cur = block_start(start);
466 assert(cur <= start, "Postcondition");
467
468 oop obj;
469
470 HeapWord* next = cur;
471 do {
472 cur = next;
473 obj = oop(cur);
474 if (obj->klass_or_null() == NULL) {
475 // Ran into an unparseable point.
476 return cur;
477 }
478 // Otherwise...
479 next = cur + block_size(cur);
480 } while (next <= start);
481
482 // If we finish the above loop...We have a parseable object that
483 // begins on or before the start of the memory region, and ends
484 // inside or spans the entire region.
485 assert(cur <= start, "Loop postcondition");
486 assert(obj->klass_or_null() != NULL, "Loop postcondition");
487
488 do {
489 obj = oop(cur);
490 assert((cur + block_size(cur)) > (HeapWord*)obj, "Loop invariant");
491 if (obj->klass_or_null() == NULL) {
492 // Ran into an unparseable point.
493 return cur;
494 }
495
496 // Advance the current pointer. "obj" still points to the object to iterate.
497 cur = cur + block_size(cur);
498
499 if (!g1h->is_obj_dead(obj)) {
500 // Non-objArrays are sometimes marked imprecise at the object start. We
501 // always need to iterate over them in full.
502 // We only iterate over object arrays in full if they are completely contained
503 // in the memory region.
504 if (!obj->is_objArray() || (((HeapWord*)obj) >= start && cur <= end)) {
505 obj->oop_iterate(cl);
506 } else {
507 obj->oop_iterate(cl, mr);
508 }
509 }
510 } while (cur < end);
511
512 return NULL;
513 }
514
515 // Code roots support
516
517 void HeapRegion::add_strong_code_root(nmethod* nm) {
518 HeapRegionRemSet* hrrs = rem_set();
519 hrrs->add_strong_code_root(nm);
520 }
521
522 void HeapRegion::add_strong_code_root_locked(nmethod* nm) {
523 assert_locked_or_safepoint(CodeCache_lock);
524 HeapRegionRemSet* hrrs = rem_set();
525 hrrs->add_strong_code_root_locked(nm);
526 }
527
528 void HeapRegion::remove_strong_code_root(nmethod* nm) {
529 HeapRegionRemSet* hrrs = rem_set();
530 hrrs->remove_strong_code_root(nm);
531 }
532
533 void HeapRegion::strong_code_roots_do(CodeBlobClosure* blk) const {
534 HeapRegionRemSet* hrrs = rem_set();
535 hrrs->strong_code_roots_do(blk);
536 }
537
538 class VerifyStrongCodeRootOopClosure: public OopClosure {
539 const HeapRegion* _hr;
540 nmethod* _nm;
541 bool _failures;
542 bool _has_oops_in_region;
543
544 template <class T> void do_oop_work(T* p) {
545 T heap_oop = oopDesc::load_heap_oop(p);
546 if (!oopDesc::is_null(heap_oop)) {
547 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
548
549 // Note: not all the oops embedded in the nmethod are in the
550 // current region. We only look at those which are.
551 if (_hr->is_in(obj)) {
552 // Object is in the region. Check that its less than top
553 if (_hr->top() <= (HeapWord*)obj) {
554 // Object is above top
555 gclog_or_tty->print_cr("Object "PTR_FORMAT" in region "
556 "["PTR_FORMAT", "PTR_FORMAT") is above "
557 "top "PTR_FORMAT,
558 (void *)obj, _hr->bottom(), _hr->end(), _hr->top());
559 _failures = true;
560 return;
561 }
562 // Nmethod has at least one oop in the current region
563 _has_oops_in_region = true;
564 }
565 }
566 }
567
568 public:
569 VerifyStrongCodeRootOopClosure(const HeapRegion* hr, nmethod* nm):
570 _hr(hr), _failures(false), _has_oops_in_region(false) {}
571
572 void do_oop(narrowOop* p) { do_oop_work(p); }
573 void do_oop(oop* p) { do_oop_work(p); }
574
575 bool failures() { return _failures; }
576 bool has_oops_in_region() { return _has_oops_in_region; }
577 };
578
579 class VerifyStrongCodeRootCodeBlobClosure: public CodeBlobClosure {
580 const HeapRegion* _hr;
581 bool _failures;
582 public:
583 VerifyStrongCodeRootCodeBlobClosure(const HeapRegion* hr) :
584 _hr(hr), _failures(false) {}
585
586 void do_code_blob(CodeBlob* cb) {
587 nmethod* nm = (cb == NULL) ? NULL : cb->as_nmethod_or_null();
588 if (nm != NULL) {
589 // Verify that the nemthod is live
590 if (!nm->is_alive()) {
591 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] has dead nmethod "
592 PTR_FORMAT" in its strong code roots",
593 _hr->bottom(), _hr->end(), nm);
594 _failures = true;
595 } else {
596 VerifyStrongCodeRootOopClosure oop_cl(_hr, nm);
597 nm->oops_do(&oop_cl);
598 if (!oop_cl.has_oops_in_region()) {
599 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] has nmethod "
600 PTR_FORMAT" in its strong code roots "
601 "with no pointers into region",
602 _hr->bottom(), _hr->end(), nm);
603 _failures = true;
604 } else if (oop_cl.failures()) {
605 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] has other "
606 "failures for nmethod "PTR_FORMAT,
607 _hr->bottom(), _hr->end(), nm);
608 _failures = true;
609 }
610 }
611 }
612 }
613
614 bool failures() { return _failures; }
615 };
616
617 void HeapRegion::verify_strong_code_roots(VerifyOption vo, bool* failures) const {
618 if (!G1VerifyHeapRegionCodeRoots) {
619 // We're not verifying code roots.
620 return;
621 }
622 if (vo == VerifyOption_G1UseMarkWord) {
623 // Marking verification during a full GC is performed after class
624 // unloading, code cache unloading, etc so the strong code roots
625 // attached to each heap region are in an inconsistent state. They won't
626 // be consistent until the strong code roots are rebuilt after the
627 // actual GC. Skip verifying the strong code roots in this particular
628 // time.
629 assert(VerifyDuringGC, "only way to get here");
630 return;
631 }
632
633 HeapRegionRemSet* hrrs = rem_set();
634 size_t strong_code_roots_length = hrrs->strong_code_roots_list_length();
635
636 // if this region is empty then there should be no entries
637 // on its strong code root list
638 if (is_empty()) {
639 if (strong_code_roots_length > 0) {
640 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] is empty "
641 "but has "SIZE_FORMAT" code root entries",
642 bottom(), end(), strong_code_roots_length);
643 *failures = true;
644 }
645 return;
646 }
647
648 if (continuesHumongous()) {
649 if (strong_code_roots_length > 0) {
650 gclog_or_tty->print_cr("region "HR_FORMAT" is a continuation of a humongous "
651 "region but has "SIZE_FORMAT" code root entries",
652 HR_FORMAT_PARAMS(this), strong_code_roots_length);
653 *failures = true;
654 }
655 return;
656 }
657
658 VerifyStrongCodeRootCodeBlobClosure cb_cl(this);
659 strong_code_roots_do(&cb_cl);
660
661 if (cb_cl.failures()) {
662 *failures = true;
663 }
664 }
665
666 void HeapRegion::print() const { print_on(gclog_or_tty); }
667 void HeapRegion::print_on(outputStream* st) const {
668 st->print("AC%4u", allocation_context());
669 st->print(" %2s", get_short_type_str());
670 if (in_collection_set())
671 st->print(" CS");
672 else
673 st->print(" ");
674 st->print(" TS %5d", _gc_time_stamp);
675 st->print(" PTAMS "PTR_FORMAT" NTAMS "PTR_FORMAT,
676 prev_top_at_mark_start(), next_top_at_mark_start());
677 G1OffsetTableContigSpace::print_on(st);
678 }
679
680 class VerifyLiveClosure: public OopClosure {
681 private:
682 G1CollectedHeap* _g1h;
683 CardTableModRefBS* _bs;
684 oop _containing_obj;
685 bool _failures;
686 int _n_failures;
687 VerifyOption _vo;
688 public:
689 // _vo == UsePrevMarking -> use "prev" marking information,
690 // _vo == UseNextMarking -> use "next" marking information,
691 // _vo == UseMarkWord -> use mark word from object header.
692 VerifyLiveClosure(G1CollectedHeap* g1h, VerifyOption vo) :
693 _g1h(g1h), _bs(NULL), _containing_obj(NULL),
694 _failures(false), _n_failures(0), _vo(vo)
695 {
696 BarrierSet* bs = _g1h->barrier_set();
697 if (bs->is_a(BarrierSet::CardTableModRef))
698 _bs = (CardTableModRefBS*)bs;
699 }
700
701 void set_containing_obj(oop obj) {
702 _containing_obj = obj;
703 }
704
705 bool failures() { return _failures; }
706 int n_failures() { return _n_failures; }
707
708 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
709 virtual void do_oop( oop* p) { do_oop_work(p); }
710
711 void print_object(outputStream* out, oop obj) {
712 #ifdef PRODUCT
713 Klass* k = obj->klass();
714 const char* class_name = InstanceKlass::cast(k)->external_name();
715 out->print_cr("class name %s", class_name);
716 #else // PRODUCT
717 obj->print_on(out);
718 #endif // PRODUCT
719 }
720
721 template <class T>
722 void do_oop_work(T* p) {
723 assert(_containing_obj != NULL, "Precondition");
724 assert(!_g1h->is_obj_dead_cond(_containing_obj, _vo),
725 "Precondition");
726 T heap_oop = oopDesc::load_heap_oop(p);
727 if (!oopDesc::is_null(heap_oop)) {
728 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
729 bool failed = false;
730 if (!_g1h->is_in_closed_subset(obj) || _g1h->is_obj_dead_cond(obj, _vo)) {
731 MutexLockerEx x(ParGCRareEvent_lock,
732 Mutex::_no_safepoint_check_flag);
733
734 if (!_failures) {
735 gclog_or_tty->cr();
736 gclog_or_tty->print_cr("----------");
737 }
738 if (!_g1h->is_in_closed_subset(obj)) {
739 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
740 gclog_or_tty->print_cr("Field "PTR_FORMAT
741 " of live obj "PTR_FORMAT" in region "
742 "["PTR_FORMAT", "PTR_FORMAT")",
743 p, (void*) _containing_obj,
744 from->bottom(), from->end());
745 print_object(gclog_or_tty, _containing_obj);
746 gclog_or_tty->print_cr("points to obj "PTR_FORMAT" not in the heap",
747 (void*) obj);
748 } else {
749 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
750 HeapRegion* to = _g1h->heap_region_containing((HeapWord*)obj);
751 gclog_or_tty->print_cr("Field "PTR_FORMAT
752 " of live obj "PTR_FORMAT" in region "
753 "["PTR_FORMAT", "PTR_FORMAT")",
754 p, (void*) _containing_obj,
755 from->bottom(), from->end());
756 print_object(gclog_or_tty, _containing_obj);
757 gclog_or_tty->print_cr("points to dead obj "PTR_FORMAT" in region "
758 "["PTR_FORMAT", "PTR_FORMAT")",
759 (void*) obj, to->bottom(), to->end());
760 print_object(gclog_or_tty, obj);
761 }
762 gclog_or_tty->print_cr("----------");
763 gclog_or_tty->flush();
764 _failures = true;
765 failed = true;
766 _n_failures++;
767 }
768
769 if (!_g1h->full_collection() || G1VerifyRSetsDuringFullGC) {
770 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
771 HeapRegion* to = _g1h->heap_region_containing(obj);
772 if (from != NULL && to != NULL &&
773 from != to &&
774 !to->isHumongous()) {
775 jbyte cv_obj = *_bs->byte_for_const(_containing_obj);
776 jbyte cv_field = *_bs->byte_for_const(p);
777 const jbyte dirty = CardTableModRefBS::dirty_card_val();
778
779 bool is_bad = !(from->is_young()
780 || to->rem_set()->contains_reference(p)
781 || !G1HRRSFlushLogBuffersOnVerify && // buffers were not flushed
782 (_containing_obj->is_objArray() ?
783 cv_field == dirty
784 : cv_obj == dirty || cv_field == dirty));
785 if (is_bad) {
786 MutexLockerEx x(ParGCRareEvent_lock,
787 Mutex::_no_safepoint_check_flag);
788
789 if (!_failures) {
790 gclog_or_tty->cr();
791 gclog_or_tty->print_cr("----------");
792 }
793 gclog_or_tty->print_cr("Missing rem set entry:");
794 gclog_or_tty->print_cr("Field "PTR_FORMAT" "
795 "of obj "PTR_FORMAT", "
796 "in region "HR_FORMAT,
797 p, (void*) _containing_obj,
798 HR_FORMAT_PARAMS(from));
799 _containing_obj->print_on(gclog_or_tty);
800 gclog_or_tty->print_cr("points to obj "PTR_FORMAT" "
801 "in region "HR_FORMAT,
802 (void*) obj,
803 HR_FORMAT_PARAMS(to));
804 obj->print_on(gclog_or_tty);
805 gclog_or_tty->print_cr("Obj head CTE = %d, field CTE = %d.",
806 cv_obj, cv_field);
807 gclog_or_tty->print_cr("----------");
808 gclog_or_tty->flush();
809 _failures = true;
810 if (!failed) _n_failures++;
811 }
812 }
813 }
814 }
815 }
816 };
817
818 // This really ought to be commoned up into OffsetTableContigSpace somehow.
819 // We would need a mechanism to make that code skip dead objects.
820
821 void HeapRegion::verify(VerifyOption vo,
822 bool* failures) const {
823 G1CollectedHeap* g1 = G1CollectedHeap::heap();
824 *failures = false;
825 HeapWord* p = bottom();
826 HeapWord* prev_p = NULL;
827 VerifyLiveClosure vl_cl(g1, vo);
828 bool is_humongous = isHumongous();
829 bool do_bot_verify = !is_young();
830 size_t object_num = 0;
831 while (p < top()) {
832 oop obj = oop(p);
833 size_t obj_size = block_size(p);
834 object_num += 1;
835
836 if (is_humongous != g1->isHumongous(obj_size) &&
837 !g1->is_obj_dead(obj, this)) { // Dead objects may have bigger block_size since they span several objects.
838 gclog_or_tty->print_cr("obj "PTR_FORMAT" is of %shumongous size ("
839 SIZE_FORMAT" words) in a %shumongous region",
840 p, g1->isHumongous(obj_size) ? "" : "non-",
841 obj_size, is_humongous ? "" : "non-");
842 *failures = true;
843 return;
844 }
845
846 // If it returns false, verify_for_object() will output the
847 // appropriate message.
848 if (do_bot_verify &&
849 !g1->is_obj_dead(obj, this) &&
850 !_offsets.verify_for_object(p, obj_size)) {
851 *failures = true;
852 return;
853 }
854
855 if (!g1->is_obj_dead_cond(obj, this, vo)) {
856 if (obj->is_oop()) {
857 Klass* klass = obj->klass();
858 bool is_metaspace_object = Metaspace::contains(klass) ||
859 (vo == VerifyOption_G1UsePrevMarking &&
860 ClassLoaderDataGraph::unload_list_contains(klass));
861 if (!is_metaspace_object) {
862 gclog_or_tty->print_cr("klass "PTR_FORMAT" of object "PTR_FORMAT" "
863 "not metadata", klass, (void *)obj);
864 *failures = true;
865 return;
866 } else if (!klass->is_klass()) {
867 gclog_or_tty->print_cr("klass "PTR_FORMAT" of object "PTR_FORMAT" "
868 "not a klass", klass, (void *)obj);
869 *failures = true;
870 return;
871 } else {
872 vl_cl.set_containing_obj(obj);
873 obj->oop_iterate_no_header(&vl_cl);
874 if (vl_cl.failures()) {
875 *failures = true;
876 }
877 if (G1MaxVerifyFailures >= 0 &&
878 vl_cl.n_failures() >= G1MaxVerifyFailures) {
879 return;
880 }
881 }
882 } else {
883 gclog_or_tty->print_cr(PTR_FORMAT" no an oop", (void *)obj);
884 *failures = true;
885 return;
886 }
887 }
888 prev_p = p;
889 p += obj_size;
890 }
891
892 if (p != top()) {
893 gclog_or_tty->print_cr("end of last object "PTR_FORMAT" "
894 "does not match top "PTR_FORMAT, p, top());
895 *failures = true;
896 return;
897 }
898
899 HeapWord* the_end = end();
900 assert(p == top(), "it should still hold");
901 // Do some extra BOT consistency checking for addresses in the
902 // range [top, end). BOT look-ups in this range should yield
903 // top. No point in doing that if top == end (there's nothing there).
904 if (p < the_end) {
905 // Look up top
906 HeapWord* addr_1 = p;
907 HeapWord* b_start_1 = _offsets.block_start_const(addr_1);
908 if (b_start_1 != p) {
909 gclog_or_tty->print_cr("BOT look up for top: "PTR_FORMAT" "
910 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
911 addr_1, b_start_1, p);
912 *failures = true;
913 return;
914 }
915
916 // Look up top + 1
917 HeapWord* addr_2 = p + 1;
918 if (addr_2 < the_end) {
919 HeapWord* b_start_2 = _offsets.block_start_const(addr_2);
920 if (b_start_2 != p) {
921 gclog_or_tty->print_cr("BOT look up for top + 1: "PTR_FORMAT" "
922 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
923 addr_2, b_start_2, p);
924 *failures = true;
925 return;
926 }
927 }
928
929 // Look up an address between top and end
930 size_t diff = pointer_delta(the_end, p) / 2;
931 HeapWord* addr_3 = p + diff;
932 if (addr_3 < the_end) {
933 HeapWord* b_start_3 = _offsets.block_start_const(addr_3);
934 if (b_start_3 != p) {
935 gclog_or_tty->print_cr("BOT look up for top + diff: "PTR_FORMAT" "
936 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
937 addr_3, b_start_3, p);
938 *failures = true;
939 return;
940 }
941 }
942
943 // Loook up end - 1
944 HeapWord* addr_4 = the_end - 1;
945 HeapWord* b_start_4 = _offsets.block_start_const(addr_4);
946 if (b_start_4 != p) {
947 gclog_or_tty->print_cr("BOT look up for end - 1: "PTR_FORMAT" "
948 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
949 addr_4, b_start_4, p);
950 *failures = true;
951 return;
952 }
953 }
954
955 if (is_humongous && object_num > 1) {
956 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] is humongous "
957 "but has "SIZE_FORMAT", objects",
958 bottom(), end(), object_num);
959 *failures = true;
960 return;
961 }
962
963 verify_strong_code_roots(vo, failures);
964 }
965
966 void HeapRegion::verify() const {
967 bool dummy = false;
968 verify(VerifyOption_G1UsePrevMarking, /* failures */ &dummy);
969 }
970
971 // G1OffsetTableContigSpace code; copied from space.cpp. Hope this can go
972 // away eventually.
973
974 void G1OffsetTableContigSpace::clear(bool mangle_space) {
975 set_top(bottom());
976 _scan_top = bottom();
977 CompactibleSpace::clear(mangle_space);
978 reset_bot();
979 }
980
981 void G1OffsetTableContigSpace::set_bottom(HeapWord* new_bottom) {
982 Space::set_bottom(new_bottom);
983 _offsets.set_bottom(new_bottom);
984 }
985
986 void G1OffsetTableContigSpace::set_end(HeapWord* new_end) {
987 Space::set_end(new_end);
988 _offsets.resize(new_end - bottom());
989 }
990
991 void G1OffsetTableContigSpace::print() const {
992 print_short();
993 gclog_or_tty->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", "
994 INTPTR_FORMAT ", " INTPTR_FORMAT ")",
995 bottom(), top(), _offsets.threshold(), end());
996 }
997
998 HeapWord* G1OffsetTableContigSpace::initialize_threshold() {
999 return _offsets.initialize_threshold();
1000 }
1001
1002 HeapWord* G1OffsetTableContigSpace::cross_threshold(HeapWord* start,
1003 HeapWord* end) {
1004 _offsets.alloc_block(start, end);
1005 return _offsets.threshold();
1006 }
1007
1008 HeapWord* G1OffsetTableContigSpace::scan_top() const {
1009 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1010 HeapWord* local_top = top();
1011 OrderAccess::loadload();
1012 const unsigned local_time_stamp = _gc_time_stamp;
1013 assert(local_time_stamp <= g1h->get_gc_time_stamp(), "invariant");
1014 if (local_time_stamp < g1h->get_gc_time_stamp()) {
1015 return local_top;
1016 } else {
1017 return _scan_top;
1018 }
1019 }
1020
1021 void G1OffsetTableContigSpace::record_timestamp() {
1022 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1023 unsigned curr_gc_time_stamp = g1h->get_gc_time_stamp();
1024
1025 if (_gc_time_stamp < curr_gc_time_stamp) {
1026 // Setting the time stamp here tells concurrent readers to look at
1027 // scan_top to know the maximum allowed address to look at.
1028
1029 // scan_top should be bottom for all regions except for the
1030 // retained old alloc region which should have scan_top == top
1031 HeapWord* st = _scan_top;
1032 guarantee(st == _bottom || st == _top, "invariant");
1033
1034 _gc_time_stamp = curr_gc_time_stamp;
1035 }
1036 }
1037
1038 void G1OffsetTableContigSpace::record_retained_region() {
1039 // scan_top is the maximum address where it's safe for the next gc to
1040 // scan this region.
1041 _scan_top = top();
1042 }
1043
1044 void G1OffsetTableContigSpace::safe_object_iterate(ObjectClosure* blk) {
1045 object_iterate(blk);
1046 }
1047
1048 void G1OffsetTableContigSpace::object_iterate(ObjectClosure* blk) {
1049 HeapWord* p = bottom();
1050 while (p < top()) {
1051 if (block_is_obj(p)) {
1052 blk->do_object(oop(p));
1053 }
1054 p += block_size(p);
1055 }
1056 }
1057
1058 #define block_is_always_obj(q) true
1059 void G1OffsetTableContigSpace::prepare_for_compaction(CompactPoint* cp) {
1060 SCAN_AND_FORWARD(cp, top, block_is_always_obj, block_size);
1061 }
1062 #undef block_is_always_obj
1063
1064 G1OffsetTableContigSpace::
1065 G1OffsetTableContigSpace(G1BlockOffsetSharedArray* sharedOffsetArray,
1066 MemRegion mr) :
1067 _offsets(sharedOffsetArray, mr),
1068 _par_alloc_lock(Mutex::leaf, "OffsetTableContigSpace par alloc lock", true),
1069 _gc_time_stamp(0)
1070 {
1071 _offsets.set_space(this);
1072 }
1073
1074 void G1OffsetTableContigSpace::initialize(MemRegion mr, bool clear_space, bool mangle_space) {
1075 CompactibleSpace::initialize(mr, clear_space, mangle_space);
1076 _top = bottom();
1077 _scan_top = bottom();
1078 set_saved_mark_word(NULL);
1079 reset_bot();
1080 }
1081