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 "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/orderAccess.inline.hpp"
39
40 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
41
42 int HeapRegion::LogOfHRGrainBytes = 0;
43 int HeapRegion::LogOfHRGrainWords = 0;
44 size_t HeapRegion::GrainBytes = 0;
45 size_t HeapRegion::GrainWords = 0;
46 size_t HeapRegion::CardsPerRegion = 0;
47
48 HeapRegionDCTOC::HeapRegionDCTOC(G1CollectedHeap* g1,
49 HeapRegion* hr, ExtendedOopClosure* cl,
50 CardTableModRefBS::PrecisionStyle precision,
51 FilterKind fk) :
52 DirtyCardToOopClosure(hr, cl, precision, NULL),
53 _hr(hr), _fk(fk), _g1(g1) { }
54
55 FilterOutOfRegionClosure::FilterOutOfRegionClosure(HeapRegion* r,
56 OopClosure* oc) :
57 _r_bottom(r->bottom()), _r_end(r->end()), _oc(oc) { }
58
59 template<class ClosureType>
60 HeapWord* walk_mem_region_loop(ClosureType* cl, G1CollectedHeap* g1h,
61 HeapRegion* hr,
62 HeapWord* cur, HeapWord* top) {
63 oop cur_oop = oop(cur);
64 size_t oop_size = hr->block_size(cur);
65 HeapWord* next_obj = cur + oop_size;
66 while (next_obj < top) {
67 // Keep filtering the remembered set.
68 if (!g1h->is_obj_dead(cur_oop, hr)) {
69 // Bottom lies entirely below top, so we can call the
70 // non-memRegion version of oop_iterate below.
71 cur_oop->oop_iterate(cl);
72 }
73 cur = next_obj;
74 cur_oop = oop(cur);
75 oop_size = hr->block_size(cur);
76 next_obj = cur + oop_size;
77 }
78 return cur;
79 }
80
81 void HeapRegionDCTOC::walk_mem_region(MemRegion mr,
82 HeapWord* bottom,
83 HeapWord* top) {
84 G1CollectedHeap* g1h = _g1;
85 size_t oop_size;
86 ExtendedOopClosure* cl2 = NULL;
87
88 FilterIntoCSClosure intoCSFilt(this, g1h, _cl);
89 FilterOutOfRegionClosure outOfRegionFilt(_hr, _cl);
90
91 switch (_fk) {
92 case NoFilterKind: cl2 = _cl; break;
93 case IntoCSFilterKind: cl2 = &intoCSFilt; break;
94 case OutOfRegionFilterKind: cl2 = &outOfRegionFilt; break;
95 default: ShouldNotReachHere();
96 }
97
98 // Start filtering what we add to the remembered set. If the object is
99 // not considered dead, either because it is marked (in the mark bitmap)
100 // or it was allocated after marking finished, then we add it. Otherwise
101 // we can safely ignore the object.
102 if (!g1h->is_obj_dead(oop(bottom), _hr)) {
103 oop_size = oop(bottom)->oop_iterate(cl2, mr);
104 } else {
105 oop_size = _hr->block_size(bottom);
106 }
107
108 bottom += oop_size;
109
110 if (bottom < top) {
111 // We replicate the loop below for several kinds of possible filters.
112 switch (_fk) {
113 case NoFilterKind:
114 bottom = walk_mem_region_loop(_cl, g1h, _hr, bottom, top);
115 break;
116
117 case IntoCSFilterKind: {
118 FilterIntoCSClosure filt(this, g1h, _cl);
119 bottom = walk_mem_region_loop(&filt, g1h, _hr, bottom, top);
120 break;
121 }
122
123 case OutOfRegionFilterKind: {
124 FilterOutOfRegionClosure filt(_hr, _cl);
125 bottom = walk_mem_region_loop(&filt, g1h, _hr, bottom, top);
126 break;
127 }
128
129 default:
130 ShouldNotReachHere();
131 }
132
133 // Last object. Need to do dead-obj filtering here too.
134 if (!g1h->is_obj_dead(oop(bottom), _hr)) {
135 oop(bottom)->oop_iterate(cl2, mr);
136 }
137 }
138 }
139
140 // Minimum region size; we won't go lower than that.
141 // We might want to decrease this in the future, to deal with small
142 // heaps a bit more efficiently.
143 #define MIN_REGION_SIZE ( 1024 * 1024 )
144
145 // Maximum region size; we don't go higher than that. There's a good
146 // reason for having an upper bound. We don't want regions to get too
147 // large, otherwise cleanup's effectiveness would decrease as there
148 // will be fewer opportunities to find totally empty regions after
149 // marking.
150 #define MAX_REGION_SIZE ( 32 * 1024 * 1024 )
151
152 // The automatic region size calculation will try to have around this
153 // many regions in the heap (based on the min heap size).
154 #define TARGET_REGION_NUMBER 2048
155
156 size_t HeapRegion::max_region_size() {
157 return (size_t)MAX_REGION_SIZE;
158 }
159
160 void HeapRegion::setup_heap_region_size(size_t initial_heap_size, size_t max_heap_size) {
161 uintx region_size = G1HeapRegionSize;
162 if (FLAG_IS_DEFAULT(G1HeapRegionSize)) {
163 size_t average_heap_size = (initial_heap_size + max_heap_size) / 2;
164 region_size = MAX2(average_heap_size / TARGET_REGION_NUMBER,
165 (uintx) MIN_REGION_SIZE);
166 }
167
168 int region_size_log = log2_long((jlong) region_size);
169 // Recalculate the region size to make sure it's a power of
170 // 2. This means that region_size is the largest power of 2 that's
171 // <= what we've calculated so far.
172 region_size = ((uintx)1 << region_size_log);
173
174 // Now make sure that we don't go over or under our limits.
175 if (region_size < MIN_REGION_SIZE) {
176 region_size = MIN_REGION_SIZE;
177 } else if (region_size > MAX_REGION_SIZE) {
178 region_size = MAX_REGION_SIZE;
179 }
180
181 // And recalculate the log.
182 region_size_log = log2_long((jlong) region_size);
183
184 // Now, set up the globals.
185 guarantee(LogOfHRGrainBytes == 0, "we should only set it once");
186 LogOfHRGrainBytes = region_size_log;
187
188 guarantee(LogOfHRGrainWords == 0, "we should only set it once");
189 LogOfHRGrainWords = LogOfHRGrainBytes - LogHeapWordSize;
190
191 guarantee(GrainBytes == 0, "we should only set it once");
192 // The cast to int is safe, given that we've bounded region_size by
193 // MIN_REGION_SIZE and MAX_REGION_SIZE.
194 GrainBytes = (size_t)region_size;
195
196 guarantee(GrainWords == 0, "we should only set it once");
197 GrainWords = GrainBytes >> LogHeapWordSize;
198 guarantee((size_t) 1 << LogOfHRGrainWords == GrainWords, "sanity");
199
200 guarantee(CardsPerRegion == 0, "we should only set it once");
201 CardsPerRegion = GrainBytes >> CardTableModRefBS::card_shift;
202 }
203
204 void HeapRegion::reset_after_compaction() {
205 G1OffsetTableContigSpace::reset_after_compaction();
206 // After a compaction the mark bitmap is invalid, so we must
207 // treat all objects as being inside the unmarked area.
208 zero_marked_bytes();
209 init_top_at_mark_start();
210 }
211
212 void HeapRegion::hr_clear(bool par, bool clear_space, bool locked) {
213 assert(_humongous_type == NotHumongous,
214 "we should have already filtered out humongous regions");
215 assert(_humongous_start_region == NULL,
216 "we should have already filtered out humongous regions");
217 assert(_end == _orig_end,
218 "we should have already filtered out humongous regions");
219
220 _in_collection_set = false;
221
222 set_young_index_in_cset(-1);
223 uninstall_surv_rate_group();
224 set_young_type(NotYoung);
225 reset_pre_dummy_top();
226
227 if (!par) {
228 // If this is parallel, this will be done later.
229 HeapRegionRemSet* hrrs = rem_set();
230 if (locked) {
231 hrrs->clear_locked();
232 } else {
233 hrrs->clear();
234 }
235 _claimed = InitialClaimValue;
236 }
237 zero_marked_bytes();
238
239 _offsets.resize(HeapRegion::GrainWords);
240 init_top_at_mark_start();
241 if (clear_space) clear(SpaceDecorator::Mangle);
242 }
243
244 void HeapRegion::par_clear() {
245 assert(used() == 0, "the region should have been already cleared");
246 assert(capacity() == HeapRegion::GrainBytes, "should be back to normal");
247 HeapRegionRemSet* hrrs = rem_set();
248 hrrs->clear();
249 CardTableModRefBS* ct_bs =
250 (CardTableModRefBS*)G1CollectedHeap::heap()->barrier_set();
251 ct_bs->clear(MemRegion(bottom(), end()));
252 }
253
254 void HeapRegion::calc_gc_efficiency() {
255 // GC efficiency is the ratio of how much space would be
256 // reclaimed over how long we predict it would take to reclaim it.
257 G1CollectedHeap* g1h = G1CollectedHeap::heap();
258 G1CollectorPolicy* g1p = g1h->g1_policy();
259
260 // Retrieve a prediction of the elapsed time for this region for
261 // a mixed gc because the region will only be evacuated during a
262 // mixed gc.
263 double region_elapsed_time_ms =
264 g1p->predict_region_elapsed_time_ms(this, false /* for_young_gc */);
265 _gc_efficiency = (double) reclaimable_bytes() / region_elapsed_time_ms;
266 }
267
268 void HeapRegion::set_startsHumongous(HeapWord* new_top, HeapWord* new_end) {
269 assert(!isHumongous(), "sanity / pre-condition");
270 assert(end() == _orig_end,
271 "Should be normal before the humongous object allocation");
272 assert(top() == bottom(), "should be empty");
273 assert(bottom() <= new_top && new_top <= new_end, "pre-condition");
274
275 _humongous_type = StartsHumongous;
276 _humongous_start_region = this;
277
278 set_end(new_end);
279 _offsets.set_for_starts_humongous(new_top);
280 }
281
282 void HeapRegion::set_continuesHumongous(HeapRegion* first_hr) {
283 assert(!isHumongous(), "sanity / pre-condition");
284 assert(end() == _orig_end,
285 "Should be normal before the humongous object allocation");
286 assert(top() == bottom(), "should be empty");
287 assert(first_hr->startsHumongous(), "pre-condition");
288
289 _humongous_type = ContinuesHumongous;
290 _humongous_start_region = first_hr;
291 }
292
293 void HeapRegion::set_notHumongous() {
294 assert(isHumongous(), "pre-condition");
295
296 if (startsHumongous()) {
297 assert(top() <= end(), "pre-condition");
298 set_end(_orig_end);
299 if (top() > end()) {
300 // at least one "continues humongous" region after it
301 set_top(end());
302 }
303 } else {
304 // continues humongous
305 assert(end() == _orig_end, "sanity");
306 }
307
308 assert(capacity() == HeapRegion::GrainBytes, "pre-condition");
309 _humongous_type = NotHumongous;
310 _humongous_start_region = NULL;
311 }
312
313 bool HeapRegion::claimHeapRegion(jint claimValue) {
314 jint current = _claimed;
315 if (current != claimValue) {
316 jint res = Atomic::cmpxchg(claimValue, &_claimed, current);
317 if (res == current) {
318 return true;
319 }
320 }
321 return false;
322 }
323
324 HeapWord* HeapRegion::next_block_start_careful(HeapWord* addr) {
325 HeapWord* low = addr;
326 HeapWord* high = end();
327 while (low < high) {
328 size_t diff = pointer_delta(high, low);
329 // Must add one below to bias toward the high amount. Otherwise, if
330 // "high" were at the desired value, and "low" were one less, we
331 // would not converge on "high". This is not symmetric, because
332 // we set "high" to a block start, which might be the right one,
333 // which we don't do for "low".
334 HeapWord* middle = low + (diff+1)/2;
335 if (middle == high) return high;
336 HeapWord* mid_bs = block_start_careful(middle);
337 if (mid_bs < addr) {
338 low = middle;
339 } else {
340 high = mid_bs;
341 }
342 }
343 assert(low == high && low >= addr, "Didn't work.");
344 return low;
345 }
346
347 HeapRegion::HeapRegion(uint hrs_index,
348 G1BlockOffsetSharedArray* sharedOffsetArray,
349 MemRegion mr) :
350 G1OffsetTableContigSpace(sharedOffsetArray, mr),
351 _hrs_index(hrs_index),
352 _humongous_type(NotHumongous), _humongous_start_region(NULL),
353 _in_collection_set(false),
354 _next_in_special_set(NULL), _orig_end(NULL),
355 _claimed(InitialClaimValue), _evacuation_failed(false),
356 _prev_marked_bytes(0), _next_marked_bytes(0), _gc_efficiency(0.0),
357 _young_type(NotYoung), _next_young_region(NULL),
358 _next_dirty_cards_region(NULL), _next(NULL), _prev(NULL),
359 #ifdef ASSERT
360 _containing_set(NULL),
361 #endif // ASSERT
362 _young_index_in_cset(-1), _surv_rate_group(NULL), _age_index(-1),
363 _rem_set(NULL), _recorded_rs_length(0), _predicted_elapsed_time_ms(0),
364 _predicted_bytes_to_copy(0)
365 {
366 _rem_set = new HeapRegionRemSet(sharedOffsetArray, this);
367 assert(HeapRegionRemSet::num_par_rem_sets() > 0, "Invariant.");
368
369 initialize(mr);
370 }
371
372 void HeapRegion::initialize(MemRegion mr, bool clear_space, bool mangle_space) {
373 assert(_rem_set->is_empty(), "Remembered set must be empty");
374
375 G1OffsetTableContigSpace::initialize(mr, clear_space, mangle_space);
376
377 _orig_end = mr.end();
378 hr_clear(false /*par*/, false /*clear_space*/);
379 set_top(bottom());
380 record_top_and_timestamp();
381 }
382
383 CompactibleSpace* HeapRegion::next_compaction_space() const {
384 return G1CollectedHeap::heap()->next_compaction_region(this);
385 }
386
387 void HeapRegion::note_self_forwarding_removal_start(bool during_initial_mark,
388 bool during_conc_mark) {
389 // We always recreate the prev marking info and we'll explicitly
390 // mark all objects we find to be self-forwarded on the prev
391 // bitmap. So all objects need to be below PTAMS.
392 _prev_marked_bytes = 0;
393
394 if (during_initial_mark) {
395 // During initial-mark, we'll also explicitly mark all objects
396 // we find to be self-forwarded on the next bitmap. So all
397 // objects need to be below NTAMS.
398 _next_top_at_mark_start = top();
399 _next_marked_bytes = 0;
400 } else if (during_conc_mark) {
401 // During concurrent mark, all objects in the CSet (including
402 // the ones we find to be self-forwarded) are implicitly live.
403 // So all objects need to be above NTAMS.
404 _next_top_at_mark_start = bottom();
405 _next_marked_bytes = 0;
406 }
407 }
408
409 void HeapRegion::note_self_forwarding_removal_end(bool during_initial_mark,
410 bool during_conc_mark,
411 size_t marked_bytes) {
412 assert(0 <= marked_bytes && marked_bytes <= used(),
413 err_msg("marked: "SIZE_FORMAT" used: "SIZE_FORMAT,
414 marked_bytes, used()));
415 _prev_top_at_mark_start = top();
416 _prev_marked_bytes = marked_bytes;
417 }
418
419 HeapWord*
420 HeapRegion::object_iterate_mem_careful(MemRegion mr,
421 ObjectClosure* cl) {
422 G1CollectedHeap* g1h = G1CollectedHeap::heap();
423 // We used to use "block_start_careful" here. But we're actually happy
424 // to update the BOT while we do this...
425 HeapWord* cur = block_start(mr.start());
426 mr = mr.intersection(used_region());
427 if (mr.is_empty()) return NULL;
428 // Otherwise, find the obj that extends onto mr.start().
429
430 assert(cur <= mr.start()
431 && (oop(cur)->klass_or_null() == NULL ||
432 cur + oop(cur)->size() > mr.start()),
433 "postcondition of block_start");
434 oop obj;
435 while (cur < mr.end()) {
436 obj = oop(cur);
437 if (obj->klass_or_null() == NULL) {
438 // Ran into an unparseable point.
439 return cur;
440 } else if (!g1h->is_obj_dead(obj)) {
441 cl->do_object(obj);
442 }
443 if (cl->abort()) return cur;
444 // The check above must occur before the operation below, since an
445 // abort might invalidate the "size" operation.
446 cur += block_size(cur);
447 }
448 return NULL;
449 }
450
451 HeapWord*
452 HeapRegion::
453 oops_on_card_seq_iterate_careful(MemRegion mr,
454 FilterOutOfRegionClosure* cl,
455 bool filter_young,
456 jbyte* card_ptr) {
457 // Currently, we should only have to clean the card if filter_young
458 // is true and vice versa.
459 if (filter_young) {
460 assert(card_ptr != NULL, "pre-condition");
461 } else {
462 assert(card_ptr == NULL, "pre-condition");
463 }
464 G1CollectedHeap* g1h = G1CollectedHeap::heap();
465
466 // If we're within a stop-world GC, then we might look at a card in a
467 // GC alloc region that extends onto a GC LAB, which may not be
468 // parseable. Stop such at the "saved_mark" of the region.
469 if (g1h->is_gc_active()) {
470 mr = mr.intersection(used_region_at_save_marks());
471 } else {
472 mr = mr.intersection(used_region());
473 }
474 if (mr.is_empty()) return NULL;
475 // Otherwise, find the obj that extends onto mr.start().
476
477 // The intersection of the incoming mr (for the card) and the
478 // allocated part of the region is non-empty. This implies that
479 // we have actually allocated into this region. The code in
480 // G1CollectedHeap.cpp that allocates a new region sets the
481 // is_young tag on the region before allocating. Thus we
482 // safely know if this region is young.
483 if (is_young() && filter_young) {
484 return NULL;
485 }
486
487 assert(!is_young(), "check value of filter_young");
488
489 // We can only clean the card here, after we make the decision that
490 // the card is not young. And we only clean the card if we have been
491 // asked to (i.e., card_ptr != NULL).
492 if (card_ptr != NULL) {
493 *card_ptr = CardTableModRefBS::clean_card_val();
494 // We must complete this write before we do any of the reads below.
495 OrderAccess::storeload();
496 }
497
498 // Cache the boundaries of the memory region in some const locals
499 HeapWord* const start = mr.start();
500 HeapWord* const end = mr.end();
501
502 // We used to use "block_start_careful" here. But we're actually happy
503 // to update the BOT while we do this...
504 HeapWord* cur = block_start(start);
505 assert(cur <= start, "Postcondition");
506
507 oop obj;
508
509 HeapWord* next = cur;
510 while (next <= start) {
511 cur = next;
512 obj = oop(cur);
513 if (obj->klass_or_null() == NULL) {
514 // Ran into an unparseable point.
515 return cur;
516 }
517 // Otherwise...
518 next = cur + block_size(cur);
519 }
520
521 // If we finish the above loop...We have a parseable object that
522 // begins on or before the start of the memory region, and ends
523 // inside or spans the entire region.
524
525 assert(obj == oop(cur), "sanity");
526 assert(cur <= start, "Loop postcondition");
527 assert(obj->klass_or_null() != NULL, "Loop postcondition");
528 assert((cur + block_size(cur)) > start, "Loop postcondition");
529
530 if (!g1h->is_obj_dead(obj)) {
531 obj->oop_iterate(cl, mr);
532 }
533
534 while (cur < end) {
535 obj = oop(cur);
536 if (obj->klass_or_null() == NULL) {
537 // Ran into an unparseable point.
538 return cur;
539 };
540
541 // Otherwise:
542 next = cur + block_size(cur);
543
544 if (!g1h->is_obj_dead(obj)) {
545 if (next < end || !obj->is_objArray()) {
546 // This object either does not span the MemRegion
547 // boundary, or if it does it's not an array.
548 // Apply closure to whole object.
549 obj->oop_iterate(cl);
550 } else {
551 // This obj is an array that spans the boundary.
552 // Stop at the boundary.
553 obj->oop_iterate(cl, mr);
554 }
555 }
556 cur = next;
557 }
558 return NULL;
559 }
560
561 // Code roots support
562
563 void HeapRegion::add_strong_code_root(nmethod* nm) {
564 HeapRegionRemSet* hrrs = rem_set();
565 hrrs->add_strong_code_root(nm);
566 }
567
568 void HeapRegion::remove_strong_code_root(nmethod* nm) {
569 HeapRegionRemSet* hrrs = rem_set();
570 hrrs->remove_strong_code_root(nm);
571 }
572
573 void HeapRegion::migrate_strong_code_roots() {
574 assert(in_collection_set(), "only collection set regions");
575 assert(!isHumongous(),
576 err_msg("humongous region "HR_FORMAT" should not have been added to collection set",
577 HR_FORMAT_PARAMS(this)));
578
579 HeapRegionRemSet* hrrs = rem_set();
580 hrrs->migrate_strong_code_roots();
581 }
582
583 void HeapRegion::strong_code_roots_do(CodeBlobClosure* blk) const {
584 HeapRegionRemSet* hrrs = rem_set();
585 hrrs->strong_code_roots_do(blk);
586 }
587
588 class VerifyStrongCodeRootOopClosure: public OopClosure {
589 const HeapRegion* _hr;
590 nmethod* _nm;
591 bool _failures;
592 bool _has_oops_in_region;
593
594 template <class T> void do_oop_work(T* p) {
595 T heap_oop = oopDesc::load_heap_oop(p);
596 if (!oopDesc::is_null(heap_oop)) {
597 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
598
599 // Note: not all the oops embedded in the nmethod are in the
600 // current region. We only look at those which are.
601 if (_hr->is_in(obj)) {
602 // Object is in the region. Check that its less than top
603 if (_hr->top() <= (HeapWord*)obj) {
604 // Object is above top
605 gclog_or_tty->print_cr("Object "PTR_FORMAT" in region "
606 "["PTR_FORMAT", "PTR_FORMAT") is above "
607 "top "PTR_FORMAT,
608 (void *)obj, _hr->bottom(), _hr->end(), _hr->top());
609 _failures = true;
610 return;
611 }
612 // Nmethod has at least one oop in the current region
613 _has_oops_in_region = true;
614 }
615 }
616 }
617
618 public:
619 VerifyStrongCodeRootOopClosure(const HeapRegion* hr, nmethod* nm):
620 _hr(hr), _failures(false), _has_oops_in_region(false) {}
621
622 void do_oop(narrowOop* p) { do_oop_work(p); }
623 void do_oop(oop* p) { do_oop_work(p); }
624
625 bool failures() { return _failures; }
626 bool has_oops_in_region() { return _has_oops_in_region; }
627 };
628
629 class VerifyStrongCodeRootCodeBlobClosure: public CodeBlobClosure {
630 const HeapRegion* _hr;
631 bool _failures;
632 public:
633 VerifyStrongCodeRootCodeBlobClosure(const HeapRegion* hr) :
634 _hr(hr), _failures(false) {}
635
636 void do_code_blob(CodeBlob* cb) {
637 nmethod* nm = (cb == NULL) ? NULL : cb->as_nmethod_or_null();
638 if (nm != NULL) {
639 // Verify that the nemthod is live
640 if (!nm->is_alive()) {
641 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] has dead nmethod "
642 PTR_FORMAT" in its strong code roots",
643 _hr->bottom(), _hr->end(), nm);
644 _failures = true;
645 } else {
646 VerifyStrongCodeRootOopClosure oop_cl(_hr, nm);
647 nm->oops_do(&oop_cl);
648 if (!oop_cl.has_oops_in_region()) {
649 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] has nmethod "
650 PTR_FORMAT" in its strong code roots "
651 "with no pointers into region",
652 _hr->bottom(), _hr->end(), nm);
653 _failures = true;
654 } else if (oop_cl.failures()) {
655 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] has other "
656 "failures for nmethod "PTR_FORMAT,
657 _hr->bottom(), _hr->end(), nm);
658 _failures = true;
659 }
660 }
661 }
662 }
663
664 bool failures() { return _failures; }
665 };
666
667 void HeapRegion::verify_strong_code_roots(VerifyOption vo, bool* failures) const {
668 if (!G1VerifyHeapRegionCodeRoots) {
669 // We're not verifying code roots.
670 return;
671 }
672 if (vo == VerifyOption_G1UseMarkWord) {
673 // Marking verification during a full GC is performed after class
674 // unloading, code cache unloading, etc so the strong code roots
675 // attached to each heap region are in an inconsistent state. They won't
676 // be consistent until the strong code roots are rebuilt after the
677 // actual GC. Skip verifying the strong code roots in this particular
678 // time.
679 assert(VerifyDuringGC, "only way to get here");
680 return;
681 }
682
683 HeapRegionRemSet* hrrs = rem_set();
684 size_t strong_code_roots_length = hrrs->strong_code_roots_list_length();
685
686 // if this region is empty then there should be no entries
687 // on its strong code root list
688 if (is_empty()) {
689 if (strong_code_roots_length > 0) {
690 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] is empty "
691 "but has "SIZE_FORMAT" code root entries",
692 bottom(), end(), strong_code_roots_length);
693 *failures = true;
694 }
695 return;
696 }
697
698 if (continuesHumongous()) {
699 if (strong_code_roots_length > 0) {
700 gclog_or_tty->print_cr("region "HR_FORMAT" is a continuation of a humongous "
701 "region but has "SIZE_FORMAT" code root entries",
702 HR_FORMAT_PARAMS(this), strong_code_roots_length);
703 *failures = true;
704 }
705 return;
706 }
707
708 VerifyStrongCodeRootCodeBlobClosure cb_cl(this);
709 strong_code_roots_do(&cb_cl);
710
711 if (cb_cl.failures()) {
712 *failures = true;
713 }
714 }
715
716 void HeapRegion::print() const { print_on(gclog_or_tty); }
717 void HeapRegion::print_on(outputStream* st) const {
718 if (isHumongous()) {
719 if (startsHumongous())
720 st->print(" HS");
721 else
722 st->print(" HC");
723 } else {
724 st->print(" ");
725 }
726 if (in_collection_set())
727 st->print(" CS");
728 else
729 st->print(" ");
730 if (is_young())
731 st->print(is_survivor() ? " SU" : " Y ");
732 else
733 st->print(" ");
734 if (is_empty())
735 st->print(" F");
736 else
737 st->print(" ");
738 st->print(" TS %5d", _gc_time_stamp);
739 st->print(" PTAMS "PTR_FORMAT" NTAMS "PTR_FORMAT,
740 prev_top_at_mark_start(), next_top_at_mark_start());
741 G1OffsetTableContigSpace::print_on(st);
742 }
743
744 class VerifyLiveClosure: public OopClosure {
745 private:
746 G1CollectedHeap* _g1h;
747 CardTableModRefBS* _bs;
748 oop _containing_obj;
749 bool _failures;
750 int _n_failures;
751 VerifyOption _vo;
752 public:
753 // _vo == UsePrevMarking -> use "prev" marking information,
754 // _vo == UseNextMarking -> use "next" marking information,
755 // _vo == UseMarkWord -> use mark word from object header.
756 VerifyLiveClosure(G1CollectedHeap* g1h, VerifyOption vo) :
757 _g1h(g1h), _bs(NULL), _containing_obj(NULL),
758 _failures(false), _n_failures(0), _vo(vo)
759 {
760 BarrierSet* bs = _g1h->barrier_set();
761 if (bs->is_a(BarrierSet::CardTableModRef))
762 _bs = (CardTableModRefBS*)bs;
763 }
764
765 void set_containing_obj(oop obj) {
766 _containing_obj = obj;
767 }
768
769 bool failures() { return _failures; }
770 int n_failures() { return _n_failures; }
771
772 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
773 virtual void do_oop( oop* p) { do_oop_work(p); }
774
775 void print_object(outputStream* out, oop obj) {
776 #ifdef PRODUCT
777 Klass* k = obj->klass();
778 const char* class_name = InstanceKlass::cast(k)->external_name();
779 out->print_cr("class name %s", class_name);
780 #else // PRODUCT
781 obj->print_on(out);
782 #endif // PRODUCT
783 }
784
785 template <class T>
786 void do_oop_work(T* p) {
787 assert(_containing_obj != NULL, "Precondition");
788 assert(!_g1h->is_obj_dead_cond(_containing_obj, _vo),
789 "Precondition");
790 T heap_oop = oopDesc::load_heap_oop(p);
791 if (!oopDesc::is_null(heap_oop)) {
792 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
793 bool failed = false;
794 if (!_g1h->is_in_closed_subset(obj) || _g1h->is_obj_dead_cond(obj, _vo)) {
795 MutexLockerEx x(ParGCRareEvent_lock,
796 Mutex::_no_safepoint_check_flag);
797
798 if (!_failures) {
799 gclog_or_tty->cr();
800 gclog_or_tty->print_cr("----------");
801 }
802 if (!_g1h->is_in_closed_subset(obj)) {
803 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
804 gclog_or_tty->print_cr("Field "PTR_FORMAT
805 " of live obj "PTR_FORMAT" in region "
806 "["PTR_FORMAT", "PTR_FORMAT")",
807 p, (void*) _containing_obj,
808 from->bottom(), from->end());
809 print_object(gclog_or_tty, _containing_obj);
810 gclog_or_tty->print_cr("points to obj "PTR_FORMAT" not in the heap",
811 (void*) obj);
812 } else {
813 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
814 HeapRegion* to = _g1h->heap_region_containing((HeapWord*)obj);
815 gclog_or_tty->print_cr("Field "PTR_FORMAT
816 " of live obj "PTR_FORMAT" in region "
817 "["PTR_FORMAT", "PTR_FORMAT")",
818 p, (void*) _containing_obj,
819 from->bottom(), from->end());
820 print_object(gclog_or_tty, _containing_obj);
821 gclog_or_tty->print_cr("points to dead obj "PTR_FORMAT" in region "
822 "["PTR_FORMAT", "PTR_FORMAT")",
823 (void*) obj, to->bottom(), to->end());
824 print_object(gclog_or_tty, obj);
825 }
826 gclog_or_tty->print_cr("----------");
827 gclog_or_tty->flush();
828 _failures = true;
829 failed = true;
830 _n_failures++;
831 }
832
833 if (!_g1h->full_collection() || G1VerifyRSetsDuringFullGC) {
834 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
835 HeapRegion* to = _g1h->heap_region_containing(obj);
836 if (from != NULL && to != NULL &&
837 from != to &&
838 !to->isHumongous()) {
839 jbyte cv_obj = *_bs->byte_for_const(_containing_obj);
840 jbyte cv_field = *_bs->byte_for_const(p);
841 const jbyte dirty = CardTableModRefBS::dirty_card_val();
842
843 bool is_bad = !(from->is_young()
844 || to->rem_set()->contains_reference(p)
845 || !G1HRRSFlushLogBuffersOnVerify && // buffers were not flushed
846 (_containing_obj->is_objArray() ?
847 cv_field == dirty
848 : cv_obj == dirty || cv_field == dirty));
849 if (is_bad) {
850 MutexLockerEx x(ParGCRareEvent_lock,
851 Mutex::_no_safepoint_check_flag);
852
853 if (!_failures) {
854 gclog_or_tty->cr();
855 gclog_or_tty->print_cr("----------");
856 }
857 gclog_or_tty->print_cr("Missing rem set entry:");
858 gclog_or_tty->print_cr("Field "PTR_FORMAT" "
859 "of obj "PTR_FORMAT", "
860 "in region "HR_FORMAT,
861 p, (void*) _containing_obj,
862 HR_FORMAT_PARAMS(from));
863 _containing_obj->print_on(gclog_or_tty);
864 gclog_or_tty->print_cr("points to obj "PTR_FORMAT" "
865 "in region "HR_FORMAT,
866 (void*) obj,
867 HR_FORMAT_PARAMS(to));
868 obj->print_on(gclog_or_tty);
869 gclog_or_tty->print_cr("Obj head CTE = %d, field CTE = %d.",
870 cv_obj, cv_field);
871 gclog_or_tty->print_cr("----------");
872 gclog_or_tty->flush();
873 _failures = true;
874 if (!failed) _n_failures++;
875 }
876 }
877 }
878 }
879 }
880 };
881
882 // This really ought to be commoned up into OffsetTableContigSpace somehow.
883 // We would need a mechanism to make that code skip dead objects.
884
885 void HeapRegion::verify(VerifyOption vo,
886 bool* failures) const {
887 G1CollectedHeap* g1 = G1CollectedHeap::heap();
888 *failures = false;
889 HeapWord* p = bottom();
890 HeapWord* prev_p = NULL;
891 VerifyLiveClosure vl_cl(g1, vo);
892 bool is_humongous = isHumongous();
893 bool do_bot_verify = !is_young();
894 size_t object_num = 0;
895 while (p < top()) {
896 oop obj = oop(p);
897 size_t obj_size = block_size(p);
898 object_num += 1;
899
900 if (is_humongous != g1->isHumongous(obj_size) &&
901 !g1->is_obj_dead(obj, this)) { // Dead objects may have bigger block_size since they span several objects.
902 gclog_or_tty->print_cr("obj "PTR_FORMAT" is of %shumongous size ("
903 SIZE_FORMAT" words) in a %shumongous region",
904 p, g1->isHumongous(obj_size) ? "" : "non-",
905 obj_size, is_humongous ? "" : "non-");
906 *failures = true;
907 return;
908 }
909
910 // If it returns false, verify_for_object() will output the
911 // appropriate message.
912 if (do_bot_verify &&
913 !g1->is_obj_dead(obj, this) &&
914 !_offsets.verify_for_object(p, obj_size)) {
915 *failures = true;
916 return;
917 }
918
919 if (!g1->is_obj_dead_cond(obj, this, vo)) {
920 if (obj->is_oop()) {
921 Klass* klass = obj->klass();
922 bool is_metaspace_object = Metaspace::contains(klass) ||
923 (vo == VerifyOption_G1UsePrevMarking &&
924 ClassLoaderDataGraph::unload_list_contains(klass));
925 if (!is_metaspace_object) {
926 gclog_or_tty->print_cr("klass "PTR_FORMAT" of object "PTR_FORMAT" "
927 "not metadata", klass, (void *)obj);
928 *failures = true;
929 return;
930 } else if (!klass->is_klass()) {
931 gclog_or_tty->print_cr("klass "PTR_FORMAT" of object "PTR_FORMAT" "
932 "not a klass", klass, (void *)obj);
933 *failures = true;
934 return;
935 } else {
936 vl_cl.set_containing_obj(obj);
937 obj->oop_iterate_no_header(&vl_cl);
938 if (vl_cl.failures()) {
939 *failures = true;
940 }
941 if (G1MaxVerifyFailures >= 0 &&
942 vl_cl.n_failures() >= G1MaxVerifyFailures) {
943 return;
944 }
945 }
946 } else {
947 gclog_or_tty->print_cr(PTR_FORMAT" no an oop", (void *)obj);
948 *failures = true;
949 return;
950 }
951 }
952 prev_p = p;
953 p += obj_size;
954 }
955
956 if (p != top()) {
957 gclog_or_tty->print_cr("end of last object "PTR_FORMAT" "
958 "does not match top "PTR_FORMAT, p, top());
959 *failures = true;
960 return;
961 }
962
963 HeapWord* the_end = end();
964 assert(p == top(), "it should still hold");
965 // Do some extra BOT consistency checking for addresses in the
966 // range [top, end). BOT look-ups in this range should yield
967 // top. No point in doing that if top == end (there's nothing there).
968 if (p < the_end) {
969 // Look up top
970 HeapWord* addr_1 = p;
971 HeapWord* b_start_1 = _offsets.block_start_const(addr_1);
972 if (b_start_1 != p) {
973 gclog_or_tty->print_cr("BOT look up for top: "PTR_FORMAT" "
974 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
975 addr_1, b_start_1, p);
976 *failures = true;
977 return;
978 }
979
980 // Look up top + 1
981 HeapWord* addr_2 = p + 1;
982 if (addr_2 < the_end) {
983 HeapWord* b_start_2 = _offsets.block_start_const(addr_2);
984 if (b_start_2 != p) {
985 gclog_or_tty->print_cr("BOT look up for top + 1: "PTR_FORMAT" "
986 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
987 addr_2, b_start_2, p);
988 *failures = true;
989 return;
990 }
991 }
992
993 // Look up an address between top and end
994 size_t diff = pointer_delta(the_end, p) / 2;
995 HeapWord* addr_3 = p + diff;
996 if (addr_3 < the_end) {
997 HeapWord* b_start_3 = _offsets.block_start_const(addr_3);
998 if (b_start_3 != p) {
999 gclog_or_tty->print_cr("BOT look up for top + diff: "PTR_FORMAT" "
1000 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
1001 addr_3, b_start_3, p);
1002 *failures = true;
1003 return;
1004 }
1005 }
1006
1007 // Loook up end - 1
1008 HeapWord* addr_4 = the_end - 1;
1009 HeapWord* b_start_4 = _offsets.block_start_const(addr_4);
1010 if (b_start_4 != p) {
1011 gclog_or_tty->print_cr("BOT look up for end - 1: "PTR_FORMAT" "
1012 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
1013 addr_4, b_start_4, p);
1014 *failures = true;
1015 return;
1016 }
1017 }
1018
1019 if (is_humongous && object_num > 1) {
1020 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] is humongous "
1021 "but has "SIZE_FORMAT", objects",
1022 bottom(), end(), object_num);
1023 *failures = true;
1024 return;
1025 }
1026
1027 verify_strong_code_roots(vo, failures);
1028 }
1029
1030 void HeapRegion::verify() const {
1031 bool dummy = false;
1032 verify(VerifyOption_G1UsePrevMarking, /* failures */ &dummy);
1033 }
1034
1035 // G1OffsetTableContigSpace code; copied from space.cpp. Hope this can go
1036 // away eventually.
1037
1038 void G1OffsetTableContigSpace::clear(bool mangle_space) {
1039 set_top(bottom());
1040 set_saved_mark_word(bottom());
1041 CompactibleSpace::clear(mangle_space);
1042 reset_bot();
1043 }
1044
1045 void G1OffsetTableContigSpace::set_bottom(HeapWord* new_bottom) {
1046 Space::set_bottom(new_bottom);
1047 _offsets.set_bottom(new_bottom);
1048 }
1049
1050 void G1OffsetTableContigSpace::set_end(HeapWord* new_end) {
1051 Space::set_end(new_end);
1052 _offsets.resize(new_end - bottom());
1053 }
1054
1055 void G1OffsetTableContigSpace::print() const {
1056 print_short();
1057 gclog_or_tty->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", "
1058 INTPTR_FORMAT ", " INTPTR_FORMAT ")",
1059 bottom(), top(), _offsets.threshold(), end());
1060 }
1061
1062 HeapWord* G1OffsetTableContigSpace::initialize_threshold() {
1063 return _offsets.initialize_threshold();
1064 }
1065
1066 HeapWord* G1OffsetTableContigSpace::cross_threshold(HeapWord* start,
1067 HeapWord* end) {
1068 _offsets.alloc_block(start, end);
1069 return _offsets.threshold();
1070 }
1071
1072 HeapWord* G1OffsetTableContigSpace::saved_mark_word() const {
1073 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1074 assert( _gc_time_stamp <= g1h->get_gc_time_stamp(), "invariant" );
1075 if (_gc_time_stamp < g1h->get_gc_time_stamp())
1076 return top();
1077 else
1078 return Space::saved_mark_word();
1079 }
1080
1081 void G1OffsetTableContigSpace::record_top_and_timestamp() {
1082 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1083 unsigned curr_gc_time_stamp = g1h->get_gc_time_stamp();
1084
1085 if (_gc_time_stamp < curr_gc_time_stamp) {
1086 // The order of these is important, as another thread might be
1087 // about to start scanning this region. If it does so after
1088 // set_saved_mark and before _gc_time_stamp = ..., then the latter
1089 // will be false, and it will pick up top() as the high water mark
1090 // of region. If it does so after _gc_time_stamp = ..., then it
1091 // will pick up the right saved_mark_word() as the high water mark
1092 // of the region. Either way, the behaviour will be correct.
1093 Space::set_saved_mark_word(top());
1094 OrderAccess::storestore();
1095 _gc_time_stamp = curr_gc_time_stamp;
1096 // No need to do another barrier to flush the writes above. If
1097 // this is called in parallel with other threads trying to
1098 // allocate into the region, the caller should call this while
1099 // holding a lock and when the lock is released the writes will be
1100 // flushed.
1101 }
1102 }
1103
1104 void G1OffsetTableContigSpace::safe_object_iterate(ObjectClosure* blk) {
1105 object_iterate(blk);
1106 }
1107
1108 void G1OffsetTableContigSpace::object_iterate(ObjectClosure* blk) {
1109 HeapWord* p = bottom();
1110 while (p < top()) {
1111 if (block_is_obj(p)) {
1112 blk->do_object(oop(p));
1113 }
1114 p += block_size(p);
1115 }
1116 }
1117
1118 #define block_is_always_obj(q) true
1119 void G1OffsetTableContigSpace::prepare_for_compaction(CompactPoint* cp) {
1120 SCAN_AND_FORWARD(cp, top, block_is_always_obj, block_size);
1121 }
1122 #undef block_is_always_obj
1123
1124 G1OffsetTableContigSpace::
1125 G1OffsetTableContigSpace(G1BlockOffsetSharedArray* sharedOffsetArray,
1126 MemRegion mr) :
1127 _offsets(sharedOffsetArray, mr),
1128 _par_alloc_lock(Mutex::leaf, "OffsetTableContigSpace par alloc lock", true),
1129 _gc_time_stamp(0)
1130 {
1131 _offsets.set_space(this);
1132 }
1133
1134 void G1OffsetTableContigSpace::initialize(MemRegion mr, bool clear_space, bool mangle_space) {
1135 CompactibleSpace::initialize(mr, clear_space, mangle_space);
1136 _top = bottom();
1137 reset_bot();
1138 }
1139