1 /*
2 * Copyright (c) 2001, 2014, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "code/nmethod.hpp"
27 #include "gc_implementation/g1/g1BlockOffsetTable.inline.hpp"
28 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
29 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
30 #include "gc_implementation/g1/heapRegion.inline.hpp"
31 #include "gc_implementation/g1/heapRegionRemSet.hpp"
32 #include "gc_implementation/g1/heapRegionSeq.inline.hpp"
33 #include "memory/genOopClosures.inline.hpp"
34 #include "memory/iterator.hpp"
35 #include "memory/space.inline.hpp"
36 #include "oops/oop.inline.hpp"
37 #include "runtime/atomic.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 ContiguousSpaceDCTOC(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 int oop_size = cur_oop->size();
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 = cur_oop->size();
76 next_obj = cur + oop_size;
77 }
78 return cur;
79 }
80
81 void HeapRegionDCTOC::walk_mem_region_with_cl(MemRegion mr,
82 HeapWord* bottom,
83 HeapWord* top,
84 ExtendedOopClosure* cl) {
85 G1CollectedHeap* g1h = _g1;
86 int 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 = oop(bottom)->size();
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_type == NotHumongous,
215 "we should have already filtered out humongous regions");
216 assert(_humongous_start_region == NULL,
217 "we should have already filtered out humongous regions");
218 assert(_end == _orig_end,
219 "we should have already filtered out humongous regions");
220
221 _in_collection_set = false;
222
223 set_young_index_in_cset(-1);
224 uninstall_surv_rate_group();
225 set_young_type(NotYoung);
226 reset_pre_dummy_top();
227
228 if (!par) {
229 // If this is parallel, this will be done later.
230 HeapRegionRemSet* hrrs = rem_set();
231 if (locked) {
232 hrrs->clear_locked();
233 } else {
234 hrrs->clear();
235 }
236 _claimed = InitialClaimValue;
237 }
238 zero_marked_bytes();
239
240 _offsets.resize(HeapRegion::GrainWords);
241 init_top_at_mark_start();
242 if (clear_space) clear(SpaceDecorator::Mangle);
243 }
244
245 void HeapRegion::par_clear() {
246 assert(used() == 0, "the region should have been already cleared");
247 assert(capacity() == HeapRegion::GrainBytes, "should be back to normal");
248 HeapRegionRemSet* hrrs = rem_set();
249 hrrs->clear();
250 CardTableModRefBS* ct_bs =
251 (CardTableModRefBS*)G1CollectedHeap::heap()->barrier_set();
252 ct_bs->clear(MemRegion(bottom(), end()));
253 }
254
255 void HeapRegion::calc_gc_efficiency() {
256 // GC efficiency is the ratio of how much space would be
257 // reclaimed over how long we predict it would take to reclaim it.
258 G1CollectedHeap* g1h = G1CollectedHeap::heap();
259 G1CollectorPolicy* g1p = g1h->g1_policy();
260
261 // Retrieve a prediction of the elapsed time for this region for
262 // a mixed gc because the region will only be evacuated during a
263 // mixed gc.
264 double region_elapsed_time_ms =
265 g1p->predict_region_elapsed_time_ms(this, false /* for_young_gc */);
266 _gc_efficiency = (double) reclaimable_bytes() / region_elapsed_time_ms;
267 }
268
269 void HeapRegion::set_startsHumongous(HeapWord* new_top, HeapWord* new_end) {
270 assert(!isHumongous(), "sanity / pre-condition");
271 assert(end() == _orig_end,
272 "Should be normal before the humongous object allocation");
273 assert(top() == bottom(), "should be empty");
274 assert(bottom() <= new_top && new_top <= new_end, "pre-condition");
275
276 _humongous_type = StartsHumongous;
277 _humongous_start_region = this;
278
279 set_end(new_end);
280 _offsets.set_for_starts_humongous(new_top);
281 }
282
283 void HeapRegion::set_continuesHumongous(HeapRegion* first_hr) {
284 assert(!isHumongous(), "sanity / pre-condition");
285 assert(end() == _orig_end,
286 "Should be normal before the humongous object allocation");
287 assert(top() == bottom(), "should be empty");
288 assert(first_hr->startsHumongous(), "pre-condition");
289
290 _humongous_type = ContinuesHumongous;
291 _humongous_start_region = first_hr;
292 }
293
294 void HeapRegion::set_notHumongous() {
295 assert(isHumongous(), "pre-condition");
296
297 if (startsHumongous()) {
298 assert(top() <= end(), "pre-condition");
299 set_end(_orig_end);
300 if (top() > end()) {
301 // at least one "continues humongous" region after it
302 set_top(end());
303 }
304 } else {
305 // continues humongous
306 assert(end() == _orig_end, "sanity");
307 }
308
309 assert(capacity() == HeapRegion::GrainBytes, "pre-condition");
310 _humongous_type = NotHumongous;
311 _humongous_start_region = NULL;
312 }
313
314 bool HeapRegion::claimHeapRegion(jint claimValue) {
315 jint current = _claimed;
316 if (current != claimValue) {
317 jint res = Atomic::cmpxchg(claimValue, &_claimed, current);
318 if (res == current) {
319 return true;
320 }
321 }
322 return false;
323 }
324
325 HeapWord* HeapRegion::next_block_start_careful(HeapWord* addr) {
326 HeapWord* low = addr;
327 HeapWord* high = end();
328 while (low < high) {
329 size_t diff = pointer_delta(high, low);
330 // Must add one below to bias toward the high amount. Otherwise, if
331 // "high" were at the desired value, and "low" were one less, we
332 // would not converge on "high". This is not symmetric, because
333 // we set "high" to a block start, which might be the right one,
334 // which we don't do for "low".
335 HeapWord* middle = low + (diff+1)/2;
336 if (middle == high) return high;
337 HeapWord* mid_bs = block_start_careful(middle);
338 if (mid_bs < addr) {
339 low = middle;
340 } else {
341 high = mid_bs;
342 }
343 }
344 assert(low == high && low >= addr, "Didn't work.");
345 return low;
346 }
347
348 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
349 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
350 #endif // _MSC_VER
351
352
353 HeapRegion::HeapRegion(uint hrs_index,
354 G1BlockOffsetSharedArray* sharedOffsetArray,
355 MemRegion mr) :
356 G1OffsetTableContigSpace(sharedOffsetArray, mr),
357 _hrs_index(hrs_index),
358 _humongous_type(NotHumongous), _humongous_start_region(NULL),
359 _in_collection_set(false),
360 _next_in_special_set(NULL), _orig_end(NULL),
361 _claimed(InitialClaimValue), _evacuation_failed(false),
362 _prev_marked_bytes(0), _next_marked_bytes(0), _gc_efficiency(0.0),
363 _young_type(NotYoung), _next_young_region(NULL),
364 _next_dirty_cards_region(NULL), _next(NULL), _prev(NULL), _pending_removal(false),
365 #ifdef ASSERT
366 _containing_set(NULL),
367 #endif // ASSERT
368 _young_index_in_cset(-1), _surv_rate_group(NULL), _age_index(-1),
369 _rem_set(NULL), _recorded_rs_length(0), _predicted_elapsed_time_ms(0),
370 _predicted_bytes_to_copy(0)
371 {
372 _rem_set = new HeapRegionRemSet(sharedOffsetArray, this);
373 _orig_end = mr.end();
374 // Note that initialize() will set the start of the unmarked area of the
375 // region.
376 hr_clear(false /*par*/, false /*clear_space*/);
377 set_top(bottom());
378 set_saved_mark();
379
380 assert(HeapRegionRemSet::num_par_rem_sets() > 0, "Invariant.");
381 }
382
383 CompactibleSpace* HeapRegion::next_compaction_space() const {
384 // We're not using an iterator given that it will wrap around when
385 // it reaches the last region and this is not what we want here.
386 G1CollectedHeap* g1h = G1CollectedHeap::heap();
387 uint index = hrs_index() + 1;
388 while (index < g1h->n_regions()) {
389 HeapRegion* hr = g1h->region_at(index);
390 if (!hr->isHumongous()) {
391 return hr;
392 }
393 index += 1;
394 }
395 return NULL;
396 }
397
398 void HeapRegion::save_marks() {
399 set_saved_mark();
400 }
401
402 void HeapRegion::oops_in_mr_iterate(MemRegion mr, ExtendedOopClosure* cl) {
403 HeapWord* p = mr.start();
404 HeapWord* e = mr.end();
405 oop obj;
406 while (p < e) {
407 obj = oop(p);
408 p += obj->oop_iterate(cl);
409 }
410 assert(p == e, "bad memregion: doesn't end on obj boundary");
411 }
412
413 #define HeapRegion_OOP_SINCE_SAVE_MARKS_DEFN(OopClosureType, nv_suffix) \
414 void HeapRegion::oop_since_save_marks_iterate##nv_suffix(OopClosureType* cl) { \
415 ContiguousSpace::oop_since_save_marks_iterate##nv_suffix(cl); \
416 }
417 SPECIALIZED_SINCE_SAVE_MARKS_CLOSURES(HeapRegion_OOP_SINCE_SAVE_MARKS_DEFN)
418
419
420 void HeapRegion::oop_before_save_marks_iterate(ExtendedOopClosure* cl) {
421 oops_in_mr_iterate(MemRegion(bottom(), saved_mark_word()), cl);
422 }
423
424 void HeapRegion::note_self_forwarding_removal_start(bool during_initial_mark,
425 bool during_conc_mark) {
426 // We always recreate the prev marking info and we'll explicitly
427 // mark all objects we find to be self-forwarded on the prev
428 // bitmap. So all objects need to be below PTAMS.
429 _prev_top_at_mark_start = top();
430 _prev_marked_bytes = 0;
431
432 if (during_initial_mark) {
433 // During initial-mark, we'll also explicitly mark all objects
434 // we find to be self-forwarded on the next bitmap. So all
435 // objects need to be below NTAMS.
436 _next_top_at_mark_start = top();
437 _next_marked_bytes = 0;
438 } else if (during_conc_mark) {
439 // During concurrent mark, all objects in the CSet (including
440 // the ones we find to be self-forwarded) are implicitly live.
441 // So all objects need to be above NTAMS.
442 _next_top_at_mark_start = bottom();
443 _next_marked_bytes = 0;
444 }
445 }
446
447 void HeapRegion::note_self_forwarding_removal_end(bool during_initial_mark,
448 bool during_conc_mark,
449 size_t marked_bytes) {
450 assert(0 <= marked_bytes && marked_bytes <= used(),
451 err_msg("marked: "SIZE_FORMAT" used: "SIZE_FORMAT,
452 marked_bytes, used()));
453 _prev_marked_bytes = marked_bytes;
454 }
455
456 HeapWord*
457 HeapRegion::object_iterate_mem_careful(MemRegion mr,
458 ObjectClosure* cl) {
459 G1CollectedHeap* g1h = G1CollectedHeap::heap();
460 // We used to use "block_start_careful" here. But we're actually happy
461 // to update the BOT while we do this...
462 HeapWord* cur = block_start(mr.start());
463 mr = mr.intersection(used_region());
464 if (mr.is_empty()) return NULL;
465 // Otherwise, find the obj that extends onto mr.start().
466
467 assert(cur <= mr.start()
468 && (oop(cur)->klass_or_null() == NULL ||
469 cur + oop(cur)->size() > mr.start()),
470 "postcondition of block_start");
471 oop obj;
472 while (cur < mr.end()) {
473 obj = oop(cur);
474 if (obj->klass_or_null() == NULL) {
475 // Ran into an unparseable point.
476 return cur;
477 } else if (!g1h->is_obj_dead(obj)) {
478 cl->do_object(obj);
479 }
480 cur += obj->size();
481 }
482 return NULL;
483 }
484
485 HeapWord*
486 HeapRegion::
487 oops_on_card_seq_iterate_careful(MemRegion mr,
488 FilterOutOfRegionClosure* cl,
489 bool filter_young,
490 jbyte* card_ptr) {
491 // Currently, we should only have to clean the card if filter_young
492 // is true and vice versa.
493 if (filter_young) {
494 assert(card_ptr != NULL, "pre-condition");
495 } else {
496 assert(card_ptr == NULL, "pre-condition");
497 }
498 G1CollectedHeap* g1h = G1CollectedHeap::heap();
499
500 // If we're within a stop-world GC, then we might look at a card in a
501 // GC alloc region that extends onto a GC LAB, which may not be
502 // parseable. Stop such at the "saved_mark" of the region.
503 if (g1h->is_gc_active()) {
504 mr = mr.intersection(used_region_at_save_marks());
505 } else {
506 mr = mr.intersection(used_region());
507 }
508 if (mr.is_empty()) return NULL;
509 // Otherwise, find the obj that extends onto mr.start().
510
511 // The intersection of the incoming mr (for the card) and the
512 // allocated part of the region is non-empty. This implies that
513 // we have actually allocated into this region. The code in
514 // G1CollectedHeap.cpp that allocates a new region sets the
515 // is_young tag on the region before allocating. Thus we
516 // safely know if this region is young.
517 if (is_young() && filter_young) {
518 return NULL;
519 }
520
521 assert(!is_young(), "check value of filter_young");
522
523 // We can only clean the card here, after we make the decision that
524 // the card is not young. And we only clean the card if we have been
525 // asked to (i.e., card_ptr != NULL).
526 if (card_ptr != NULL) {
527 *card_ptr = CardTableModRefBS::clean_card_val();
528 // We must complete this write before we do any of the reads below.
529 OrderAccess::storeload();
530 }
531
532 // Cache the boundaries of the memory region in some const locals
533 HeapWord* const start = mr.start();
534 HeapWord* const end = mr.end();
535
536 // We used to use "block_start_careful" here. But we're actually happy
537 // to update the BOT while we do this...
538 HeapWord* cur = block_start(start);
539 assert(cur <= start, "Postcondition");
540
541 oop obj;
542
543 HeapWord* next = cur;
544 while (next <= start) {
545 cur = next;
546 obj = oop(cur);
547 if (obj->klass_or_null() == NULL) {
548 // Ran into an unparseable point.
549 return cur;
550 }
551 // Otherwise...
552 next = (cur + obj->size());
553 }
554
555 // If we finish the above loop...We have a parseable object that
556 // begins on or before the start of the memory region, and ends
557 // inside or spans the entire region.
558
559 assert(obj == oop(cur), "sanity");
560 assert(cur <= start &&
561 obj->klass_or_null() != NULL &&
562 (cur + obj->size()) > start,
563 "Loop postcondition");
564
565 if (!g1h->is_obj_dead(obj)) {
566 obj->oop_iterate(cl, mr);
567 }
568
569 while (cur < end) {
570 obj = oop(cur);
571 if (obj->klass_or_null() == NULL) {
572 // Ran into an unparseable point.
573 return cur;
574 };
575
576 // Otherwise:
577 next = (cur + obj->size());
578
579 if (!g1h->is_obj_dead(obj)) {
580 if (next < end || !obj->is_objArray()) {
581 // This object either does not span the MemRegion
582 // boundary, or if it does it's not an array.
583 // Apply closure to whole object.
584 obj->oop_iterate(cl);
585 } else {
586 // This obj is an array that spans the boundary.
587 // Stop at the boundary.
588 obj->oop_iterate(cl, mr);
589 }
590 }
591 cur = next;
592 }
593 return NULL;
594 }
595
596 // Code roots support
597
598 void HeapRegion::add_strong_code_root(nmethod* nm) {
599 HeapRegionRemSet* hrrs = rem_set();
600 hrrs->add_strong_code_root(nm);
601 }
602
603 void HeapRegion::remove_strong_code_root(nmethod* nm) {
604 HeapRegionRemSet* hrrs = rem_set();
605 hrrs->remove_strong_code_root(nm);
606 }
607
608 void HeapRegion::migrate_strong_code_roots() {
609 assert(in_collection_set(), "only collection set regions");
610 assert(!isHumongous(),
611 err_msg("humongous region "HR_FORMAT" should not have been added to collection set",
612 HR_FORMAT_PARAMS(this)));
613
614 HeapRegionRemSet* hrrs = rem_set();
615 hrrs->migrate_strong_code_roots();
616 }
617
618 void HeapRegion::strong_code_roots_do(CodeBlobClosure* blk) const {
619 HeapRegionRemSet* hrrs = rem_set();
620 hrrs->strong_code_roots_do(blk);
621 }
622
623 class VerifyStrongCodeRootOopClosure: public OopClosure {
624 const HeapRegion* _hr;
625 nmethod* _nm;
626 bool _failures;
627 bool _has_oops_in_region;
628
629 template <class T> void do_oop_work(T* p) {
630 T heap_oop = oopDesc::load_heap_oop(p);
631 if (!oopDesc::is_null(heap_oop)) {
632 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
633
634 // Note: not all the oops embedded in the nmethod are in the
635 // current region. We only look at those which are.
636 if (_hr->is_in(obj)) {
637 // Object is in the region. Check that its less than top
638 if (_hr->top() <= (HeapWord*)obj) {
639 // Object is above top
640 gclog_or_tty->print_cr("Object "PTR_FORMAT" in region "
641 "["PTR_FORMAT", "PTR_FORMAT") is above "
642 "top "PTR_FORMAT,
643 (void *)obj, _hr->bottom(), _hr->end(), _hr->top());
644 _failures = true;
645 return;
646 }
647 // Nmethod has at least one oop in the current region
648 _has_oops_in_region = true;
649 }
650 }
651 }
652
653 public:
654 VerifyStrongCodeRootOopClosure(const HeapRegion* hr, nmethod* nm):
655 _hr(hr), _failures(false), _has_oops_in_region(false) {}
656
657 void do_oop(narrowOop* p) { do_oop_work(p); }
658 void do_oop(oop* p) { do_oop_work(p); }
659
660 bool failures() { return _failures; }
661 bool has_oops_in_region() { return _has_oops_in_region; }
662 };
663
664 class VerifyStrongCodeRootCodeBlobClosure: public CodeBlobClosure {
665 const HeapRegion* _hr;
666 bool _failures;
667 public:
668 VerifyStrongCodeRootCodeBlobClosure(const HeapRegion* hr) :
669 _hr(hr), _failures(false) {}
670
671 void do_code_blob(CodeBlob* cb) {
672 nmethod* nm = (cb == NULL) ? NULL : cb->as_nmethod_or_null();
673 if (nm != NULL) {
674 // Verify that the nemthod is live
675 if (!nm->is_alive()) {
676 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] has dead nmethod "
677 PTR_FORMAT" in its strong code roots",
678 _hr->bottom(), _hr->end(), nm);
679 _failures = true;
680 } else {
681 VerifyStrongCodeRootOopClosure oop_cl(_hr, nm);
682 nm->oops_do(&oop_cl);
683 if (!oop_cl.has_oops_in_region()) {
684 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] has nmethod "
685 PTR_FORMAT" in its strong code roots "
686 "with no pointers into region",
687 _hr->bottom(), _hr->end(), nm);
688 _failures = true;
689 } else if (oop_cl.failures()) {
690 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] has other "
691 "failures for nmethod "PTR_FORMAT,
692 _hr->bottom(), _hr->end(), nm);
693 _failures = true;
694 }
695 }
696 }
697 }
698
699 bool failures() { return _failures; }
700 };
701
702 void HeapRegion::verify_strong_code_roots(VerifyOption vo, bool* failures) const {
703 if (!G1VerifyHeapRegionCodeRoots) {
704 // We're not verifying code roots.
705 return;
706 }
707 if (vo == VerifyOption_G1UseMarkWord) {
708 // Marking verification during a full GC is performed after class
709 // unloading, code cache unloading, etc so the strong code roots
710 // attached to each heap region are in an inconsistent state. They won't
711 // be consistent until the strong code roots are rebuilt after the
712 // actual GC. Skip verifying the strong code roots in this particular
713 // time.
714 assert(VerifyDuringGC, "only way to get here");
715 return;
716 }
717
718 HeapRegionRemSet* hrrs = rem_set();
719 size_t strong_code_roots_length = hrrs->strong_code_roots_list_length();
720
721 // if this region is empty then there should be no entries
722 // on its strong code root list
723 if (is_empty()) {
724 if (strong_code_roots_length > 0) {
725 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] is empty "
726 "but has "SIZE_FORMAT" code root entries",
727 bottom(), end(), strong_code_roots_length);
728 *failures = true;
729 }
730 return;
731 }
732
733 if (continuesHumongous()) {
734 if (strong_code_roots_length > 0) {
735 gclog_or_tty->print_cr("region "HR_FORMAT" is a continuation of a humongous "
736 "region but has "SIZE_FORMAT" code root entries",
737 HR_FORMAT_PARAMS(this), strong_code_roots_length);
738 *failures = true;
739 }
740 return;
741 }
742
743 VerifyStrongCodeRootCodeBlobClosure cb_cl(this);
744 strong_code_roots_do(&cb_cl);
745
746 if (cb_cl.failures()) {
747 *failures = true;
748 }
749 }
750
751 void HeapRegion::print() const { print_on(gclog_or_tty); }
752 void HeapRegion::print_on(outputStream* st) const {
753 if (isHumongous()) {
754 if (startsHumongous())
755 st->print(" HS");
756 else
757 st->print(" HC");
758 } else {
759 st->print(" ");
760 }
761 if (in_collection_set())
762 st->print(" CS");
763 else
764 st->print(" ");
765 if (is_young())
766 st->print(is_survivor() ? " SU" : " Y ");
767 else
768 st->print(" ");
769 if (is_empty())
770 st->print(" F");
771 else
772 st->print(" ");
773 st->print(" TS %5d", _gc_time_stamp);
774 st->print(" PTAMS "PTR_FORMAT" NTAMS "PTR_FORMAT,
775 prev_top_at_mark_start(), next_top_at_mark_start());
776 G1OffsetTableContigSpace::print_on(st);
777 }
778
779 class VerifyLiveClosure: public OopClosure {
780 private:
781 G1CollectedHeap* _g1h;
782 CardTableModRefBS* _bs;
783 oop _containing_obj;
784 bool _failures;
785 int _n_failures;
786 VerifyOption _vo;
787 public:
788 // _vo == UsePrevMarking -> use "prev" marking information,
789 // _vo == UseNextMarking -> use "next" marking information,
790 // _vo == UseMarkWord -> use mark word from object header.
791 VerifyLiveClosure(G1CollectedHeap* g1h, VerifyOption vo) :
792 _g1h(g1h), _bs(NULL), _containing_obj(NULL),
793 _failures(false), _n_failures(0), _vo(vo)
794 {
795 BarrierSet* bs = _g1h->barrier_set();
796 if (bs->is_a(BarrierSet::CardTableModRef))
797 _bs = (CardTableModRefBS*)bs;
798 }
799
800 void set_containing_obj(oop obj) {
801 _containing_obj = obj;
802 }
803
804 bool failures() { return _failures; }
805 int n_failures() { return _n_failures; }
806
807 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
808 virtual void do_oop( oop* p) { do_oop_work(p); }
809
810 void print_object(outputStream* out, oop obj) {
811 #ifdef PRODUCT
812 Klass* k = obj->klass();
813 const char* class_name = InstanceKlass::cast(k)->external_name();
814 out->print_cr("class name %s", class_name);
815 #else // PRODUCT
816 obj->print_on(out);
817 #endif // PRODUCT
818 }
819
820 template <class T>
821 void do_oop_work(T* p) {
822 assert(_containing_obj != NULL, "Precondition");
823 assert(!_g1h->is_obj_dead_cond(_containing_obj, _vo),
824 "Precondition");
825 T heap_oop = oopDesc::load_heap_oop(p);
826 if (!oopDesc::is_null(heap_oop)) {
827 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
828 bool failed = false;
829 if (!_g1h->is_in_closed_subset(obj) || _g1h->is_obj_dead_cond(obj, _vo)) {
830 MutexLockerEx x(ParGCRareEvent_lock,
831 Mutex::_no_safepoint_check_flag);
832
833 if (!_failures) {
834 gclog_or_tty->cr();
835 gclog_or_tty->print_cr("----------");
836 }
837 if (!_g1h->is_in_closed_subset(obj)) {
838 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
839 gclog_or_tty->print_cr("Field "PTR_FORMAT
840 " of live obj "PTR_FORMAT" in region "
841 "["PTR_FORMAT", "PTR_FORMAT")",
842 p, (void*) _containing_obj,
843 from->bottom(), from->end());
844 print_object(gclog_or_tty, _containing_obj);
845 gclog_or_tty->print_cr("points to obj "PTR_FORMAT" not in the heap",
846 (void*) obj);
847 } else {
848 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
849 HeapRegion* to = _g1h->heap_region_containing((HeapWord*)obj);
850 gclog_or_tty->print_cr("Field "PTR_FORMAT
851 " of live obj "PTR_FORMAT" in region "
852 "["PTR_FORMAT", "PTR_FORMAT")",
853 p, (void*) _containing_obj,
854 from->bottom(), from->end());
855 print_object(gclog_or_tty, _containing_obj);
856 gclog_or_tty->print_cr("points to dead obj "PTR_FORMAT" in region "
857 "["PTR_FORMAT", "PTR_FORMAT")",
858 (void*) obj, to->bottom(), to->end());
859 print_object(gclog_or_tty, obj);
860 }
861 gclog_or_tty->print_cr("----------");
862 gclog_or_tty->flush();
863 _failures = true;
864 failed = true;
865 _n_failures++;
866 }
867
868 if (!_g1h->full_collection() || G1VerifyRSetsDuringFullGC) {
869 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
870 HeapRegion* to = _g1h->heap_region_containing(obj);
871 if (from != NULL && to != NULL &&
872 from != to &&
873 !to->isHumongous()) {
874 jbyte cv_obj = *_bs->byte_for_const(_containing_obj);
875 jbyte cv_field = *_bs->byte_for_const(p);
876 const jbyte dirty = CardTableModRefBS::dirty_card_val();
877
878 bool is_bad = !(from->is_young()
879 || to->rem_set()->contains_reference(p)
880 || !G1HRRSFlushLogBuffersOnVerify && // buffers were not flushed
881 (_containing_obj->is_objArray() ?
882 cv_field == dirty
883 : cv_obj == dirty || cv_field == dirty));
884 if (is_bad) {
885 MutexLockerEx x(ParGCRareEvent_lock,
886 Mutex::_no_safepoint_check_flag);
887
888 if (!_failures) {
889 gclog_or_tty->cr();
890 gclog_or_tty->print_cr("----------");
891 }
892 gclog_or_tty->print_cr("Missing rem set entry:");
893 gclog_or_tty->print_cr("Field "PTR_FORMAT" "
894 "of obj "PTR_FORMAT", "
895 "in region "HR_FORMAT,
896 p, (void*) _containing_obj,
897 HR_FORMAT_PARAMS(from));
898 _containing_obj->print_on(gclog_or_tty);
899 gclog_or_tty->print_cr("points to obj "PTR_FORMAT" "
900 "in region "HR_FORMAT,
901 (void*) obj,
902 HR_FORMAT_PARAMS(to));
903 obj->print_on(gclog_or_tty);
904 gclog_or_tty->print_cr("Obj head CTE = %d, field CTE = %d.",
905 cv_obj, cv_field);
906 gclog_or_tty->print_cr("----------");
907 gclog_or_tty->flush();
908 _failures = true;
909 if (!failed) _n_failures++;
910 }
911 }
912 }
913 }
914 }
915 };
916
917 // This really ought to be commoned up into OffsetTableContigSpace somehow.
918 // We would need a mechanism to make that code skip dead objects.
919
920 void HeapRegion::verify(VerifyOption vo,
921 bool* failures) const {
922 G1CollectedHeap* g1 = G1CollectedHeap::heap();
923 *failures = false;
924 HeapWord* p = bottom();
925 HeapWord* prev_p = NULL;
926 VerifyLiveClosure vl_cl(g1, vo);
927 bool is_humongous = isHumongous();
928 bool do_bot_verify = !is_young();
929 size_t object_num = 0;
930 while (p < top()) {
931 oop obj = oop(p);
932 size_t obj_size = obj->size();
933 object_num += 1;
934
935 if (is_humongous != g1->isHumongous(obj_size)) {
936 gclog_or_tty->print_cr("obj "PTR_FORMAT" is of %shumongous size ("
937 SIZE_FORMAT" words) in a %shumongous region",
938 p, g1->isHumongous(obj_size) ? "" : "non-",
939 obj_size, is_humongous ? "" : "non-");
940 *failures = true;
941 return;
942 }
943
944 // If it returns false, verify_for_object() will output the
945 // appropriate messasge.
946 if (do_bot_verify && !_offsets.verify_for_object(p, obj_size)) {
947 *failures = true;
948 return;
949 }
950
951 if (!g1->is_obj_dead_cond(obj, this, vo)) {
952 if (obj->is_oop()) {
953 Klass* klass = obj->klass();
954 if (!klass->is_metaspace_object()) {
955 gclog_or_tty->print_cr("klass "PTR_FORMAT" of object "PTR_FORMAT" "
956 "not metadata", klass, (void *)obj);
957 *failures = true;
958 return;
959 } else if (!klass->is_klass()) {
960 gclog_or_tty->print_cr("klass "PTR_FORMAT" of object "PTR_FORMAT" "
961 "not a klass", klass, (void *)obj);
962 *failures = true;
963 return;
964 } else {
965 vl_cl.set_containing_obj(obj);
966 obj->oop_iterate_no_header(&vl_cl);
967 if (vl_cl.failures()) {
968 *failures = true;
969 }
970 if (G1MaxVerifyFailures >= 0 &&
971 vl_cl.n_failures() >= G1MaxVerifyFailures) {
972 return;
973 }
974 }
975 } else {
976 gclog_or_tty->print_cr(PTR_FORMAT" no an oop", (void *)obj);
977 *failures = true;
978 return;
979 }
980 }
981 prev_p = p;
982 p += obj_size;
983 }
984
985 if (p != top()) {
986 gclog_or_tty->print_cr("end of last object "PTR_FORMAT" "
987 "does not match top "PTR_FORMAT, p, top());
988 *failures = true;
989 return;
990 }
991
992 HeapWord* the_end = end();
993 assert(p == top(), "it should still hold");
994 // Do some extra BOT consistency checking for addresses in the
995 // range [top, end). BOT look-ups in this range should yield
996 // top. No point in doing that if top == end (there's nothing there).
997 if (p < the_end) {
998 // Look up top
999 HeapWord* addr_1 = p;
1000 HeapWord* b_start_1 = _offsets.block_start_const(addr_1);
1001 if (b_start_1 != p) {
1002 gclog_or_tty->print_cr("BOT look up for top: "PTR_FORMAT" "
1003 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
1004 addr_1, b_start_1, p);
1005 *failures = true;
1006 return;
1007 }
1008
1009 // Look up top + 1
1010 HeapWord* addr_2 = p + 1;
1011 if (addr_2 < the_end) {
1012 HeapWord* b_start_2 = _offsets.block_start_const(addr_2);
1013 if (b_start_2 != p) {
1014 gclog_or_tty->print_cr("BOT look up for top + 1: "PTR_FORMAT" "
1015 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
1016 addr_2, b_start_2, p);
1017 *failures = true;
1018 return;
1019 }
1020 }
1021
1022 // Look up an address between top and end
1023 size_t diff = pointer_delta(the_end, p) / 2;
1024 HeapWord* addr_3 = p + diff;
1025 if (addr_3 < the_end) {
1026 HeapWord* b_start_3 = _offsets.block_start_const(addr_3);
1027 if (b_start_3 != p) {
1028 gclog_or_tty->print_cr("BOT look up for top + diff: "PTR_FORMAT" "
1029 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
1030 addr_3, b_start_3, p);
1031 *failures = true;
1032 return;
1033 }
1034 }
1035
1036 // Look up end - 1
1037 HeapWord* addr_4 = the_end - 1;
1038 HeapWord* b_start_4 = _offsets.block_start_const(addr_4);
1039 if (b_start_4 != p) {
1040 gclog_or_tty->print_cr("BOT look up for end - 1: "PTR_FORMAT" "
1041 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
1042 addr_4, b_start_4, p);
1043 *failures = true;
1044 return;
1045 }
1046 }
1047
1048 if (is_humongous && object_num > 1) {
1049 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] is humongous "
1050 "but has "SIZE_FORMAT", objects",
1051 bottom(), end(), object_num);
1052 *failures = true;
1053 return;
1054 }
1055
1056 verify_strong_code_roots(vo, failures);
1057 }
1058
1059 void HeapRegion::verify() const {
1060 bool dummy = false;
1061 verify(VerifyOption_G1UsePrevMarking, /* failures */ &dummy);
1062 }
1063
1064 // G1OffsetTableContigSpace code; copied from space.cpp. Hope this can go
1065 // away eventually.
1066
1067 void G1OffsetTableContigSpace::clear(bool mangle_space) {
1068 ContiguousSpace::clear(mangle_space);
1069 _offsets.zero_bottom_entry();
1070 _offsets.initialize_threshold();
1071 }
1072
1073 void G1OffsetTableContigSpace::set_bottom(HeapWord* new_bottom) {
1074 Space::set_bottom(new_bottom);
1075 _offsets.set_bottom(new_bottom);
1076 }
1077
1078 void G1OffsetTableContigSpace::set_end(HeapWord* new_end) {
1079 Space::set_end(new_end);
1080 _offsets.resize(new_end - bottom());
1081 }
1082
1083 void G1OffsetTableContigSpace::print() const {
1084 print_short();
1085 gclog_or_tty->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", "
1086 INTPTR_FORMAT ", " INTPTR_FORMAT ")",
1087 bottom(), top(), _offsets.threshold(), end());
1088 }
1089
1090 HeapWord* G1OffsetTableContigSpace::initialize_threshold() {
1091 return _offsets.initialize_threshold();
1092 }
1093
1094 HeapWord* G1OffsetTableContigSpace::cross_threshold(HeapWord* start,
1095 HeapWord* end) {
1096 _offsets.alloc_block(start, end);
1097 return _offsets.threshold();
1098 }
1099
1100 HeapWord* G1OffsetTableContigSpace::saved_mark_word() const {
1101 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1102 assert( _gc_time_stamp <= g1h->get_gc_time_stamp(), "invariant" );
1103 if (_gc_time_stamp < g1h->get_gc_time_stamp())
1104 return top();
1105 else
1106 return ContiguousSpace::saved_mark_word();
1107 }
1108
1109 void G1OffsetTableContigSpace::set_saved_mark() {
1110 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1111 unsigned curr_gc_time_stamp = g1h->get_gc_time_stamp();
1112
1113 if (_gc_time_stamp < curr_gc_time_stamp) {
1114 // The order of these is important, as another thread might be
1115 // about to start scanning this region. If it does so after
1116 // set_saved_mark and before _gc_time_stamp = ..., then the latter
1117 // will be false, and it will pick up top() as the high water mark
1118 // of region. If it does so after _gc_time_stamp = ..., then it
1119 // will pick up the right saved_mark_word() as the high water mark
1120 // of the region. Either way, the behavior will be correct.
1121 ContiguousSpace::set_saved_mark();
1122 OrderAccess::storestore();
1123 _gc_time_stamp = curr_gc_time_stamp;
1124 // No need to do another barrier to flush the writes above. If
1125 // this is called in parallel with other threads trying to
1126 // allocate into the region, the caller should call this while
1127 // holding a lock and when the lock is released the writes will be
1128 // flushed.
1129 }
1130 }
1131
1132 G1OffsetTableContigSpace::
1133 G1OffsetTableContigSpace(G1BlockOffsetSharedArray* sharedOffsetArray,
1134 MemRegion mr) :
1135 _offsets(sharedOffsetArray, mr),
1136 _par_alloc_lock(Mutex::leaf, "OffsetTableContigSpace par alloc lock", true),
1137 _gc_time_stamp(0)
1138 {
1139 _offsets.set_space(this);
1140 // false ==> we'll do the clearing if there's clearing to be done.
1141 ContiguousSpace::initialize(mr, false, SpaceDecorator::Mangle);
1142 _offsets.zero_bottom_entry();
1143 _offsets.initialize_threshold();
1144 }