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 "oops/oop.inline.hpp"
36
37 int HeapRegion::LogOfHRGrainBytes = 0;
38 int HeapRegion::LogOfHRGrainWords = 0;
39 size_t HeapRegion::GrainBytes = 0;
40 size_t HeapRegion::GrainWords = 0;
41 size_t HeapRegion::CardsPerRegion = 0;
42
43 HeapRegionDCTOC::HeapRegionDCTOC(G1CollectedHeap* g1,
44 HeapRegion* hr, ExtendedOopClosure* cl,
45 CardTableModRefBS::PrecisionStyle precision,
46 FilterKind fk) :
47 ContiguousSpaceDCTOC(hr, cl, precision, NULL),
48 _hr(hr), _fk(fk), _g1(g1) { }
49
50 FilterOutOfRegionClosure::FilterOutOfRegionClosure(HeapRegion* r,
51 OopClosure* oc) :
52 _r_bottom(r->bottom()), _r_end(r->end()), _oc(oc) { }
53
54 template<class ClosureType>
55 HeapWord* walk_mem_region_loop(ClosureType* cl, G1CollectedHeap* g1h,
56 HeapRegion* hr,
57 HeapWord* cur, HeapWord* top) {
58 oop cur_oop = oop(cur);
59 int oop_size = cur_oop->size();
60 HeapWord* next_obj = cur + oop_size;
61 while (next_obj < top) {
62 // Keep filtering the remembered set.
63 if (!g1h->is_obj_dead(cur_oop, hr)) {
64 // Bottom lies entirely below top, so we can call the
65 // non-memRegion version of oop_iterate below.
66 cur_oop->oop_iterate(cl);
67 }
68 cur = next_obj;
69 cur_oop = oop(cur);
70 oop_size = cur_oop->size();
71 next_obj = cur + oop_size;
72 }
73 return cur;
74 }
75
76 void HeapRegionDCTOC::walk_mem_region_with_cl(MemRegion mr,
77 HeapWord* bottom,
78 HeapWord* top,
79 ExtendedOopClosure* cl) {
80 G1CollectedHeap* g1h = _g1;
81 int oop_size;
82 ExtendedOopClosure* cl2 = NULL;
83
84 FilterIntoCSClosure intoCSFilt(this, g1h, cl);
85 FilterOutOfRegionClosure outOfRegionFilt(_hr, cl);
86
87 switch (_fk) {
88 case NoFilterKind: cl2 = cl; break;
89 case IntoCSFilterKind: cl2 = &intoCSFilt; break;
90 case OutOfRegionFilterKind: cl2 = &outOfRegionFilt; break;
91 default: ShouldNotReachHere();
92 }
93
94 // Start filtering what we add to the remembered set. If the object is
95 // not considered dead, either because it is marked (in the mark bitmap)
96 // or it was allocated after marking finished, then we add it. Otherwise
97 // we can safely ignore the object.
98 if (!g1h->is_obj_dead(oop(bottom), _hr)) {
99 oop_size = oop(bottom)->oop_iterate(cl2, mr);
100 } else {
101 oop_size = oop(bottom)->size();
102 }
103
104 bottom += oop_size;
105
106 if (bottom < top) {
107 // We replicate the loop below for several kinds of possible filters.
108 switch (_fk) {
109 case NoFilterKind:
110 bottom = walk_mem_region_loop(cl, g1h, _hr, bottom, top);
111 break;
112
113 case IntoCSFilterKind: {
114 FilterIntoCSClosure filt(this, g1h, cl);
115 bottom = walk_mem_region_loop(&filt, g1h, _hr, bottom, top);
116 break;
117 }
118
119 case OutOfRegionFilterKind: {
120 FilterOutOfRegionClosure filt(_hr, cl);
121 bottom = walk_mem_region_loop(&filt, g1h, _hr, bottom, top);
122 break;
123 }
124
125 default:
126 ShouldNotReachHere();
127 }
128
129 // Last object. Need to do dead-obj filtering here too.
130 if (!g1h->is_obj_dead(oop(bottom), _hr)) {
131 oop(bottom)->oop_iterate(cl2, mr);
132 }
133 }
134 }
135
136 // Minimum region size; we won't go lower than that.
137 // We might want to decrease this in the future, to deal with small
138 // heaps a bit more efficiently.
139 #define MIN_REGION_SIZE ( 1024 * 1024 )
140
141 // Maximum region size; we don't go higher than that. There's a good
142 // reason for having an upper bound. We don't want regions to get too
143 // large, otherwise cleanup's effectiveness would decrease as there
144 // will be fewer opportunities to find totally empty regions after
145 // marking.
146 #define MAX_REGION_SIZE ( 32 * 1024 * 1024 )
147
148 // The automatic region size calculation will try to have around this
149 // many regions in the heap (based on the min heap size).
150 #define TARGET_REGION_NUMBER 2048
151
152 size_t HeapRegion::max_region_size() {
153 return (size_t)MAX_REGION_SIZE;
154 }
155
156 void HeapRegion::setup_heap_region_size(size_t initial_heap_size, size_t max_heap_size) {
157 uintx region_size = G1HeapRegionSize;
158 if (FLAG_IS_DEFAULT(G1HeapRegionSize)) {
159 size_t average_heap_size = (initial_heap_size + max_heap_size) / 2;
160 region_size = MAX2(average_heap_size / TARGET_REGION_NUMBER,
161 (uintx) MIN_REGION_SIZE);
162 }
163
164 int region_size_log = log2_long((jlong) region_size);
165 // Recalculate the region size to make sure it's a power of
166 // 2. This means that region_size is the largest power of 2 that's
167 // <= what we've calculated so far.
168 region_size = ((uintx)1 << region_size_log);
169
170 // Now make sure that we don't go over or under our limits.
171 if (region_size < MIN_REGION_SIZE) {
172 region_size = MIN_REGION_SIZE;
173 } else if (region_size > MAX_REGION_SIZE) {
174 region_size = MAX_REGION_SIZE;
175 }
176
177 // And recalculate the log.
178 region_size_log = log2_long((jlong) region_size);
179
180 // Now, set up the globals.
181 guarantee(LogOfHRGrainBytes == 0, "we should only set it once");
182 LogOfHRGrainBytes = region_size_log;
183
184 guarantee(LogOfHRGrainWords == 0, "we should only set it once");
185 LogOfHRGrainWords = LogOfHRGrainBytes - LogHeapWordSize;
186
187 guarantee(GrainBytes == 0, "we should only set it once");
188 // The cast to int is safe, given that we've bounded region_size by
189 // MIN_REGION_SIZE and MAX_REGION_SIZE.
190 GrainBytes = (size_t)region_size;
191
192 guarantee(GrainWords == 0, "we should only set it once");
193 GrainWords = GrainBytes >> LogHeapWordSize;
194 guarantee((size_t) 1 << LogOfHRGrainWords == GrainWords, "sanity");
195
196 guarantee(CardsPerRegion == 0, "we should only set it once");
197 CardsPerRegion = GrainBytes >> CardTableModRefBS::card_shift;
198 }
199
200 void HeapRegion::reset_after_compaction() {
201 G1OffsetTableContigSpace::reset_after_compaction();
202 // After a compaction the mark bitmap is invalid, so we must
203 // treat all objects as being inside the unmarked area.
204 zero_marked_bytes();
205 init_top_at_mark_start();
206 }
207
208 void HeapRegion::hr_clear(bool par, bool clear_space, bool locked) {
209 assert(_humongous_type == NotHumongous,
210 "we should have already filtered out humongous regions");
211 assert(_humongous_start_region == NULL,
212 "we should have already filtered out humongous regions");
213 assert(_end == _orig_end,
214 "we should have already filtered out humongous regions");
215
216 _in_collection_set = false;
217
218 set_young_index_in_cset(-1);
219 uninstall_surv_rate_group();
220 set_young_type(NotYoung);
221 reset_pre_dummy_top();
222
223 if (!par) {
224 // If this is parallel, this will be done later.
225 HeapRegionRemSet* hrrs = rem_set();
226 if (locked) {
227 hrrs->clear_locked();
228 } else {
229 hrrs->clear();
230 }
231 _claimed = InitialClaimValue;
232 }
233 zero_marked_bytes();
234
235 _offsets.resize(HeapRegion::GrainWords);
236 init_top_at_mark_start();
237 if (clear_space) clear(SpaceDecorator::Mangle);
238 }
239
240 void HeapRegion::par_clear() {
241 assert(used() == 0, "the region should have been already cleared");
242 assert(capacity() == HeapRegion::GrainBytes, "should be back to normal");
243 HeapRegionRemSet* hrrs = rem_set();
244 hrrs->clear();
245 CardTableModRefBS* ct_bs =
246 (CardTableModRefBS*)G1CollectedHeap::heap()->barrier_set();
247 ct_bs->clear(MemRegion(bottom(), end()));
248 }
249
250 void HeapRegion::calc_gc_efficiency() {
251 // GC efficiency is the ratio of how much space would be
252 // reclaimed over how long we predict it would take to reclaim it.
253 G1CollectedHeap* g1h = G1CollectedHeap::heap();
254 G1CollectorPolicy* g1p = g1h->g1_policy();
255
256 // Retrieve a prediction of the elapsed time for this region for
257 // a mixed gc because the region will only be evacuated during a
258 // mixed gc.
259 double region_elapsed_time_ms =
260 g1p->predict_region_elapsed_time_ms(this, false /* for_young_gc */);
261 _gc_efficiency = (double) reclaimable_bytes() / region_elapsed_time_ms;
262 }
263
264 void HeapRegion::set_startsHumongous(HeapWord* new_top, HeapWord* new_end) {
265 assert(!isHumongous(), "sanity / pre-condition");
266 assert(end() == _orig_end,
267 "Should be normal before the humongous object allocation");
268 assert(top() == bottom(), "should be empty");
269 assert(bottom() <= new_top && new_top <= new_end, "pre-condition");
270
271 _humongous_type = StartsHumongous;
272 _humongous_start_region = this;
273
274 set_end(new_end);
275 _offsets.set_for_starts_humongous(new_top);
276 }
277
278 void HeapRegion::set_continuesHumongous(HeapRegion* first_hr) {
279 assert(!isHumongous(), "sanity / pre-condition");
280 assert(end() == _orig_end,
281 "Should be normal before the humongous object allocation");
282 assert(top() == bottom(), "should be empty");
283 assert(first_hr->startsHumongous(), "pre-condition");
284
285 _humongous_type = ContinuesHumongous;
286 _humongous_start_region = first_hr;
287 }
288
289 void HeapRegion::set_notHumongous() {
290 assert(isHumongous(), "pre-condition");
291
292 if (startsHumongous()) {
293 assert(top() <= end(), "pre-condition");
294 set_end(_orig_end);
295 if (top() > end()) {
296 // at least one "continues humongous" region after it
297 set_top(end());
298 }
299 } else {
300 // continues humongous
301 assert(end() == _orig_end, "sanity");
302 }
303
304 assert(capacity() == HeapRegion::GrainBytes, "pre-condition");
305 _humongous_type = NotHumongous;
306 _humongous_start_region = NULL;
307 }
308
309 bool HeapRegion::claimHeapRegion(jint claimValue) {
310 jint current = _claimed;
311 if (current != claimValue) {
312 jint res = Atomic::cmpxchg(claimValue, &_claimed, current);
313 if (res == current) {
314 return true;
315 }
316 }
317 return false;
318 }
319
320 HeapWord* HeapRegion::next_block_start_careful(HeapWord* addr) {
321 HeapWord* low = addr;
322 HeapWord* high = end();
323 while (low < high) {
324 size_t diff = pointer_delta(high, low);
325 // Must add one below to bias toward the high amount. Otherwise, if
326 // "high" were at the desired value, and "low" were one less, we
327 // would not converge on "high". This is not symmetric, because
328 // we set "high" to a block start, which might be the right one,
329 // which we don't do for "low".
330 HeapWord* middle = low + (diff+1)/2;
331 if (middle == high) return high;
332 HeapWord* mid_bs = block_start_careful(middle);
333 if (mid_bs < addr) {
334 low = middle;
335 } else {
336 high = mid_bs;
337 }
338 }
339 assert(low == high && low >= addr, "Didn't work.");
340 return low;
341 }
342
343 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
344 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
345 #endif // _MSC_VER
346
347
348 HeapRegion::HeapRegion(uint hrs_index,
349 G1BlockOffsetSharedArray* sharedOffsetArray,
350 MemRegion mr) :
351 G1OffsetTableContigSpace(sharedOffsetArray, mr),
352 _hrs_index(hrs_index),
353 _humongous_type(NotHumongous), _humongous_start_region(NULL),
354 _in_collection_set(false),
355 _next_in_special_set(NULL), _orig_end(NULL),
356 _claimed(InitialClaimValue), _evacuation_failed(false),
357 _prev_marked_bytes(0), _next_marked_bytes(0), _gc_efficiency(0.0),
358 _young_type(NotYoung), _next_young_region(NULL),
359 _next_dirty_cards_region(NULL), _next(NULL), _pending_removal(false),
360 #ifdef ASSERT
361 _containing_set(NULL),
362 #endif // ASSERT
363 _young_index_in_cset(-1), _surv_rate_group(NULL), _age_index(-1),
364 _rem_set(NULL), _recorded_rs_length(0), _predicted_elapsed_time_ms(0),
365 _predicted_bytes_to_copy(0)
366 {
367 _rem_set = new HeapRegionRemSet(sharedOffsetArray, this);
368 _orig_end = mr.end();
369 // Note that initialize() will set the start of the unmarked area of the
370 // region.
371 hr_clear(false /*par*/, false /*clear_space*/);
372 set_top(bottom());
373 set_saved_mark();
374
375 assert(HeapRegionRemSet::num_par_rem_sets() > 0, "Invariant.");
376 }
377
378 CompactibleSpace* HeapRegion::next_compaction_space() const {
379 // We're not using an iterator given that it will wrap around when
380 // it reaches the last region and this is not what we want here.
381 G1CollectedHeap* g1h = G1CollectedHeap::heap();
382 uint index = hrs_index() + 1;
383 while (index < g1h->n_regions()) {
384 HeapRegion* hr = g1h->region_at(index);
385 if (!hr->isHumongous()) {
386 return hr;
387 }
388 index += 1;
389 }
390 return NULL;
391 }
392
393 void HeapRegion::save_marks() {
394 set_saved_mark();
395 }
396
397 void HeapRegion::oops_in_mr_iterate(MemRegion mr, ExtendedOopClosure* cl) {
398 HeapWord* p = mr.start();
399 HeapWord* e = mr.end();
400 oop obj;
401 while (p < e) {
402 obj = oop(p);
403 p += obj->oop_iterate(cl);
404 }
405 assert(p == e, "bad memregion: doesn't end on obj boundary");
406 }
407
408 #define HeapRegion_OOP_SINCE_SAVE_MARKS_DEFN(OopClosureType, nv_suffix) \
409 void HeapRegion::oop_since_save_marks_iterate##nv_suffix(OopClosureType* cl) { \
410 ContiguousSpace::oop_since_save_marks_iterate##nv_suffix(cl); \
411 }
412 SPECIALIZED_SINCE_SAVE_MARKS_CLOSURES(HeapRegion_OOP_SINCE_SAVE_MARKS_DEFN)
413
414
415 void HeapRegion::oop_before_save_marks_iterate(ExtendedOopClosure* cl) {
416 oops_in_mr_iterate(MemRegion(bottom(), saved_mark_word()), cl);
417 }
418
419 void HeapRegion::note_self_forwarding_removal_start(bool during_initial_mark,
420 bool during_conc_mark) {
421 // We always recreate the prev marking info and we'll explicitly
422 // mark all objects we find to be self-forwarded on the prev
423 // bitmap. So all objects need to be below PTAMS.
424 _prev_top_at_mark_start = top();
425 _prev_marked_bytes = 0;
426
427 if (during_initial_mark) {
428 // During initial-mark, we'll also explicitly mark all objects
429 // we find to be self-forwarded on the next bitmap. So all
430 // objects need to be below NTAMS.
431 _next_top_at_mark_start = top();
432 _next_marked_bytes = 0;
433 } else if (during_conc_mark) {
434 // During concurrent mark, all objects in the CSet (including
435 // the ones we find to be self-forwarded) are implicitly live.
436 // So all objects need to be above NTAMS.
437 _next_top_at_mark_start = bottom();
438 _next_marked_bytes = 0;
439 }
440 }
441
442 void HeapRegion::note_self_forwarding_removal_end(bool during_initial_mark,
443 bool during_conc_mark,
444 size_t marked_bytes) {
445 assert(0 <= marked_bytes && marked_bytes <= used(),
446 err_msg("marked: "SIZE_FORMAT" used: "SIZE_FORMAT,
447 marked_bytes, used()));
448 _prev_marked_bytes = marked_bytes;
449 }
450
451 HeapWord*
452 HeapRegion::object_iterate_mem_careful(MemRegion mr,
453 ObjectClosure* cl) {
454 G1CollectedHeap* g1h = G1CollectedHeap::heap();
455 // We used to use "block_start_careful" here. But we're actually happy
456 // to update the BOT while we do this...
457 HeapWord* cur = block_start(mr.start());
458 mr = mr.intersection(used_region());
459 if (mr.is_empty()) return NULL;
460 // Otherwise, find the obj that extends onto mr.start().
461
462 assert(cur <= mr.start()
463 && (oop(cur)->klass_or_null() == NULL ||
464 cur + oop(cur)->size() > mr.start()),
465 "postcondition of block_start");
466 oop obj;
467 while (cur < mr.end()) {
468 obj = oop(cur);
469 if (obj->klass_or_null() == NULL) {
470 // Ran into an unparseable point.
471 return cur;
472 } else if (!g1h->is_obj_dead(obj)) {
473 cl->do_object(obj);
474 }
475 if (cl->abort()) return cur;
476 // The check above must occur before the operation below, since an
477 // abort might invalidate the "size" operation.
478 cur += obj->size();
479 }
480 return NULL;
481 }
482
483 HeapWord*
484 HeapRegion::
485 oops_on_card_seq_iterate_careful(MemRegion mr,
486 FilterOutOfRegionClosure* cl,
487 bool filter_young,
488 jbyte* card_ptr) {
489 // Currently, we should only have to clean the card if filter_young
490 // is true and vice versa.
491 if (filter_young) {
492 assert(card_ptr != NULL, "pre-condition");
493 } else {
494 assert(card_ptr == NULL, "pre-condition");
495 }
496 G1CollectedHeap* g1h = G1CollectedHeap::heap();
497
498 // If we're within a stop-world GC, then we might look at a card in a
499 // GC alloc region that extends onto a GC LAB, which may not be
500 // parseable. Stop such at the "saved_mark" of the region.
501 if (g1h->is_gc_active()) {
502 mr = mr.intersection(used_region_at_save_marks());
503 } else {
504 mr = mr.intersection(used_region());
505 }
506 if (mr.is_empty()) return NULL;
507 // Otherwise, find the obj that extends onto mr.start().
508
509 // The intersection of the incoming mr (for the card) and the
510 // allocated part of the region is non-empty. This implies that
511 // we have actually allocated into this region. The code in
512 // G1CollectedHeap.cpp that allocates a new region sets the
513 // is_young tag on the region before allocating. Thus we
514 // safely know if this region is young.
515 if (is_young() && filter_young) {
516 return NULL;
517 }
518
519 assert(!is_young(), "check value of filter_young");
520
521 // We can only clean the card here, after we make the decision that
522 // the card is not young. And we only clean the card if we have been
523 // asked to (i.e., card_ptr != NULL).
524 if (card_ptr != NULL) {
525 *card_ptr = CardTableModRefBS::clean_card_val();
526 // We must complete this write before we do any of the reads below.
527 OrderAccess::storeload();
528 }
529
530 // Cache the boundaries of the memory region in some const locals
531 HeapWord* const start = mr.start();
532 HeapWord* const end = mr.end();
533
534 // We used to use "block_start_careful" here. But we're actually happy
535 // to update the BOT while we do this...
536 HeapWord* cur = block_start(start);
537 assert(cur <= start, "Postcondition");
538
539 oop obj;
540
541 HeapWord* next = cur;
542 while (next <= start) {
543 cur = next;
544 obj = oop(cur);
545 if (obj->klass_or_null() == NULL) {
546 // Ran into an unparseable point.
547 return cur;
548 }
549 // Otherwise...
550 next = (cur + obj->size());
551 }
552
553 // If we finish the above loop...We have a parseable object that
554 // begins on or before the start of the memory region, and ends
555 // inside or spans the entire region.
556
557 assert(obj == oop(cur), "sanity");
558 assert(cur <= start &&
559 obj->klass_or_null() != NULL &&
560 (cur + obj->size()) > start,
561 "Loop postcondition");
562
563 if (!g1h->is_obj_dead(obj)) {
564 obj->oop_iterate(cl, mr);
565 }
566
567 while (cur < end) {
568 obj = oop(cur);
569 if (obj->klass_or_null() == NULL) {
570 // Ran into an unparseable point.
571 return cur;
572 };
573
574 // Otherwise:
575 next = (cur + obj->size());
576
577 if (!g1h->is_obj_dead(obj)) {
578 if (next < end || !obj->is_objArray()) {
579 // This object either does not span the MemRegion
580 // boundary, or if it does it's not an array.
581 // Apply closure to whole object.
582 obj->oop_iterate(cl);
583 } else {
584 // This obj is an array that spans the boundary.
585 // Stop at the boundary.
586 obj->oop_iterate(cl, mr);
587 }
588 }
589 cur = next;
590 }
591 return NULL;
592 }
593
594 // Code roots support
595
596 void HeapRegion::add_strong_code_root(nmethod* nm) {
597 HeapRegionRemSet* hrrs = rem_set();
598 hrrs->add_strong_code_root(nm);
599 }
600
601 void HeapRegion::remove_strong_code_root(nmethod* nm) {
602 HeapRegionRemSet* hrrs = rem_set();
603 hrrs->remove_strong_code_root(nm);
604 }
605
606 void HeapRegion::migrate_strong_code_roots() {
607 assert(in_collection_set(), "only collection set regions");
608 assert(!isHumongous(),
609 err_msg("humongous region "HR_FORMAT" should not have been added to collection set",
610 HR_FORMAT_PARAMS(this)));
611
612 HeapRegionRemSet* hrrs = rem_set();
613 hrrs->migrate_strong_code_roots();
614 }
615
616 void HeapRegion::strong_code_roots_do(CodeBlobClosure* blk) const {
617 HeapRegionRemSet* hrrs = rem_set();
618 hrrs->strong_code_roots_do(blk);
619 }
620
621 class VerifyStrongCodeRootOopClosure: public OopClosure {
622 const HeapRegion* _hr;
623 nmethod* _nm;
624 bool _failures;
625 bool _has_oops_in_region;
626
627 template <class T> void do_oop_work(T* p) {
628 T heap_oop = oopDesc::load_heap_oop(p);
629 if (!oopDesc::is_null(heap_oop)) {
630 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
631
632 // Note: not all the oops embedded in the nmethod are in the
633 // current region. We only look at those which are.
634 if (_hr->is_in(obj)) {
635 // Object is in the region. Check that its less than top
636 if (_hr->top() <= (HeapWord*)obj) {
637 // Object is above top
638 gclog_or_tty->print_cr("Object "PTR_FORMAT" in region "
639 "["PTR_FORMAT", "PTR_FORMAT") is above "
640 "top "PTR_FORMAT,
641 (void *)obj, _hr->bottom(), _hr->end(), _hr->top());
642 _failures = true;
643 return;
644 }
645 // Nmethod has at least one oop in the current region
646 _has_oops_in_region = true;
647 }
648 }
649 }
650
651 public:
652 VerifyStrongCodeRootOopClosure(const HeapRegion* hr, nmethod* nm):
653 _hr(hr), _failures(false), _has_oops_in_region(false) {}
654
655 void do_oop(narrowOop* p) { do_oop_work(p); }
656 void do_oop(oop* p) { do_oop_work(p); }
657
658 bool failures() { return _failures; }
659 bool has_oops_in_region() { return _has_oops_in_region; }
660 };
661
662 class VerifyStrongCodeRootCodeBlobClosure: public CodeBlobClosure {
663 const HeapRegion* _hr;
664 bool _failures;
665 public:
666 VerifyStrongCodeRootCodeBlobClosure(const HeapRegion* hr) :
667 _hr(hr), _failures(false) {}
668
669 void do_code_blob(CodeBlob* cb) {
670 nmethod* nm = (cb == NULL) ? NULL : cb->as_nmethod_or_null();
671 if (nm != NULL) {
672 // Verify that the nemthod is live
673 if (!nm->is_alive()) {
674 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] has dead nmethod "
675 PTR_FORMAT" in its strong code roots",
676 _hr->bottom(), _hr->end(), nm);
677 _failures = true;
678 } else {
679 VerifyStrongCodeRootOopClosure oop_cl(_hr, nm);
680 nm->oops_do(&oop_cl);
681 if (!oop_cl.has_oops_in_region()) {
682 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] has nmethod "
683 PTR_FORMAT" in its strong code roots "
684 "with no pointers into region",
685 _hr->bottom(), _hr->end(), nm);
686 _failures = true;
687 } else if (oop_cl.failures()) {
688 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] has other "
689 "failures for nmethod "PTR_FORMAT,
690 _hr->bottom(), _hr->end(), nm);
691 _failures = true;
692 }
693 }
694 }
695 }
696
697 bool failures() { return _failures; }
698 };
699
700 void HeapRegion::verify_strong_code_roots(VerifyOption vo, bool* failures) const {
701 if (!G1VerifyHeapRegionCodeRoots) {
702 // We're not verifying code roots.
703 return;
704 }
705 if (vo == VerifyOption_G1UseMarkWord) {
706 // Marking verification during a full GC is performed after class
707 // unloading, code cache unloading, etc so the strong code roots
708 // attached to each heap region are in an inconsistent state. They won't
709 // be consistent until the strong code roots are rebuilt after the
710 // actual GC. Skip verifying the strong code roots in this particular
711 // time.
712 assert(VerifyDuringGC, "only way to get here");
713 return;
714 }
715
716 HeapRegionRemSet* hrrs = rem_set();
717 size_t strong_code_roots_length = hrrs->strong_code_roots_list_length();
718
719 // if this region is empty then there should be no entries
720 // on its strong code root list
721 if (is_empty()) {
722 if (strong_code_roots_length > 0) {
723 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] is empty "
724 "but has "SIZE_FORMAT" code root entries",
725 bottom(), end(), strong_code_roots_length);
726 *failures = true;
727 }
728 return;
729 }
730
731 if (continuesHumongous()) {
732 if (strong_code_roots_length > 0) {
733 gclog_or_tty->print_cr("region "HR_FORMAT" is a continuation of a humongous "
734 "region but has "SIZE_FORMAT" code root entries",
735 HR_FORMAT_PARAMS(this), strong_code_roots_length);
736 *failures = true;
737 }
738 return;
739 }
740
741 VerifyStrongCodeRootCodeBlobClosure cb_cl(this);
742 strong_code_roots_do(&cb_cl);
743
744 if (cb_cl.failures()) {
745 *failures = true;
746 }
747 }
748
749 void HeapRegion::print() const { print_on(gclog_or_tty); }
750 void HeapRegion::print_on(outputStream* st) const {
751 if (isHumongous()) {
752 if (startsHumongous())
753 st->print(" HS");
754 else
755 st->print(" HC");
756 } else {
757 st->print(" ");
758 }
759 if (in_collection_set())
760 st->print(" CS");
761 else
762 st->print(" ");
763 if (is_young())
764 st->print(is_survivor() ? " SU" : " Y ");
765 else
766 st->print(" ");
767 if (is_empty())
768 st->print(" F");
769 else
770 st->print(" ");
771 st->print(" TS %5d", _gc_time_stamp);
772 st->print(" PTAMS "PTR_FORMAT" NTAMS "PTR_FORMAT,
773 prev_top_at_mark_start(), next_top_at_mark_start());
774 G1OffsetTableContigSpace::print_on(st);
775 }
776
777 class VerifyLiveClosure: public OopClosure {
778 private:
779 G1CollectedHeap* _g1h;
780 CardTableModRefBS* _bs;
781 oop _containing_obj;
782 bool _failures;
783 int _n_failures;
784 VerifyOption _vo;
785 public:
786 // _vo == UsePrevMarking -> use "prev" marking information,
787 // _vo == UseNextMarking -> use "next" marking information,
788 // _vo == UseMarkWord -> use mark word from object header.
789 VerifyLiveClosure(G1CollectedHeap* g1h, VerifyOption vo) :
790 _g1h(g1h), _bs(NULL), _containing_obj(NULL),
791 _failures(false), _n_failures(0), _vo(vo)
792 {
793 BarrierSet* bs = _g1h->barrier_set();
794 if (bs->is_a(BarrierSet::CardTableModRef))
795 _bs = (CardTableModRefBS*)bs;
796 }
797
798 void set_containing_obj(oop obj) {
799 _containing_obj = obj;
800 }
801
802 bool failures() { return _failures; }
803 int n_failures() { return _n_failures; }
804
805 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
806 virtual void do_oop( oop* p) { do_oop_work(p); }
807
808 void print_object(outputStream* out, oop obj) {
809 #ifdef PRODUCT
810 Klass* k = obj->klass();
811 const char* class_name = InstanceKlass::cast(k)->external_name();
812 out->print_cr("class name %s", class_name);
813 #else // PRODUCT
814 obj->print_on(out);
815 #endif // PRODUCT
816 }
817
818 template <class T>
819 void do_oop_work(T* p) {
820 assert(_containing_obj != NULL, "Precondition");
821 assert(!_g1h->is_obj_dead_cond(_containing_obj, _vo),
822 "Precondition");
823 T heap_oop = oopDesc::load_heap_oop(p);
824 if (!oopDesc::is_null(heap_oop)) {
825 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
826 bool failed = false;
827 if (!_g1h->is_in_closed_subset(obj) || _g1h->is_obj_dead_cond(obj, _vo)) {
828 MutexLockerEx x(ParGCRareEvent_lock,
829 Mutex::_no_safepoint_check_flag);
830
831 if (!_failures) {
832 gclog_or_tty->print_cr("");
833 gclog_or_tty->print_cr("----------");
834 }
835 if (!_g1h->is_in_closed_subset(obj)) {
836 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
837 gclog_or_tty->print_cr("Field "PTR_FORMAT
838 " of live obj "PTR_FORMAT" in region "
839 "["PTR_FORMAT", "PTR_FORMAT")",
840 p, (void*) _containing_obj,
841 from->bottom(), from->end());
842 print_object(gclog_or_tty, _containing_obj);
843 gclog_or_tty->print_cr("points to obj "PTR_FORMAT" not in the heap",
844 (void*) obj);
845 } else {
846 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
847 HeapRegion* to = _g1h->heap_region_containing((HeapWord*)obj);
848 gclog_or_tty->print_cr("Field "PTR_FORMAT
849 " of live obj "PTR_FORMAT" in region "
850 "["PTR_FORMAT", "PTR_FORMAT")",
851 p, (void*) _containing_obj,
852 from->bottom(), from->end());
853 print_object(gclog_or_tty, _containing_obj);
854 gclog_or_tty->print_cr("points to dead obj "PTR_FORMAT" in region "
855 "["PTR_FORMAT", "PTR_FORMAT")",
856 (void*) obj, to->bottom(), to->end());
857 print_object(gclog_or_tty, obj);
858 }
859 gclog_or_tty->print_cr("----------");
860 gclog_or_tty->flush();
861 _failures = true;
862 failed = true;
863 _n_failures++;
864 }
865
866 if (!_g1h->full_collection() || G1VerifyRSetsDuringFullGC) {
867 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
868 HeapRegion* to = _g1h->heap_region_containing(obj);
869 if (from != NULL && to != NULL &&
870 from != to &&
871 !to->isHumongous()) {
872 jbyte cv_obj = *_bs->byte_for_const(_containing_obj);
873 jbyte cv_field = *_bs->byte_for_const(p);
874 const jbyte dirty = CardTableModRefBS::dirty_card_val();
875
876 bool is_bad = !(from->is_young()
877 || to->rem_set()->contains_reference(p)
878 || !G1HRRSFlushLogBuffersOnVerify && // buffers were not flushed
879 (_containing_obj->is_objArray() ?
880 cv_field == dirty
881 : cv_obj == dirty || cv_field == dirty));
882 if (is_bad) {
883 MutexLockerEx x(ParGCRareEvent_lock,
884 Mutex::_no_safepoint_check_flag);
885
886 if (!_failures) {
887 gclog_or_tty->print_cr("");
888 gclog_or_tty->print_cr("----------");
889 }
890 gclog_or_tty->print_cr("Missing rem set entry:");
891 gclog_or_tty->print_cr("Field "PTR_FORMAT" "
892 "of obj "PTR_FORMAT", "
893 "in region "HR_FORMAT,
894 p, (void*) _containing_obj,
895 HR_FORMAT_PARAMS(from));
896 _containing_obj->print_on(gclog_or_tty);
897 gclog_or_tty->print_cr("points to obj "PTR_FORMAT" "
898 "in region "HR_FORMAT,
899 (void*) obj,
900 HR_FORMAT_PARAMS(to));
901 obj->print_on(gclog_or_tty);
902 gclog_or_tty->print_cr("Obj head CTE = %d, field CTE = %d.",
903 cv_obj, cv_field);
904 gclog_or_tty->print_cr("----------");
905 gclog_or_tty->flush();
906 _failures = true;
907 if (!failed) _n_failures++;
908 }
909 }
910 }
911 }
912 }
913 };
914
915 // This really ought to be commoned up into OffsetTableContigSpace somehow.
916 // We would need a mechanism to make that code skip dead objects.
917
918 void HeapRegion::verify(VerifyOption vo,
919 bool* failures) const {
920 G1CollectedHeap* g1 = G1CollectedHeap::heap();
921 *failures = false;
922 HeapWord* p = bottom();
923 HeapWord* prev_p = NULL;
924 VerifyLiveClosure vl_cl(g1, vo);
925 bool is_humongous = isHumongous();
926 bool do_bot_verify = !is_young();
927 size_t object_num = 0;
928 while (p < top()) {
929 oop obj = oop(p);
930 size_t obj_size = obj->size();
931 object_num += 1;
932
933 if (is_humongous != g1->isHumongous(obj_size)) {
934 gclog_or_tty->print_cr("obj "PTR_FORMAT" is of %shumongous size ("
935 SIZE_FORMAT" words) in a %shumongous region",
936 p, g1->isHumongous(obj_size) ? "" : "non-",
937 obj_size, is_humongous ? "" : "non-");
938 *failures = true;
939 return;
940 }
941
942 // If it returns false, verify_for_object() will output the
943 // appropriate messasge.
944 if (do_bot_verify && !_offsets.verify_for_object(p, obj_size)) {
945 *failures = true;
946 return;
947 }
948
949 if (!g1->is_obj_dead_cond(obj, this, vo)) {
950 if (obj->is_oop()) {
951 Klass* klass = obj->klass();
952 if (!klass->is_metaspace_object()) {
953 gclog_or_tty->print_cr("klass "PTR_FORMAT" of object "PTR_FORMAT" "
954 "not metadata", klass, (void *)obj);
955 *failures = true;
956 return;
957 } else if (!klass->is_klass()) {
958 gclog_or_tty->print_cr("klass "PTR_FORMAT" of object "PTR_FORMAT" "
959 "not a klass", klass, (void *)obj);
960 *failures = true;
961 return;
962 } else {
963 vl_cl.set_containing_obj(obj);
964 obj->oop_iterate_no_header(&vl_cl);
965 if (vl_cl.failures()) {
966 *failures = true;
967 }
968 if (G1MaxVerifyFailures >= 0 &&
969 vl_cl.n_failures() >= G1MaxVerifyFailures) {
970 return;
971 }
972 }
973 } else {
974 gclog_or_tty->print_cr(PTR_FORMAT" no an oop", (void *)obj);
975 *failures = true;
976 return;
977 }
978 }
979 prev_p = p;
980 p += obj_size;
981 }
982
983 if (p != top()) {
984 gclog_or_tty->print_cr("end of last object "PTR_FORMAT" "
985 "does not match top "PTR_FORMAT, p, top());
986 *failures = true;
987 return;
988 }
989
990 HeapWord* the_end = end();
991 assert(p == top(), "it should still hold");
992 // Do some extra BOT consistency checking for addresses in the
993 // range [top, end). BOT look-ups in this range should yield
994 // top. No point in doing that if top == end (there's nothing there).
995 if (p < the_end) {
996 // Look up top
997 HeapWord* addr_1 = p;
998 HeapWord* b_start_1 = _offsets.block_start_const(addr_1);
999 if (b_start_1 != p) {
1000 gclog_or_tty->print_cr("BOT look up for top: "PTR_FORMAT" "
1001 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
1002 addr_1, b_start_1, p);
1003 *failures = true;
1004 return;
1005 }
1006
1007 // Look up top + 1
1008 HeapWord* addr_2 = p + 1;
1009 if (addr_2 < the_end) {
1010 HeapWord* b_start_2 = _offsets.block_start_const(addr_2);
1011 if (b_start_2 != p) {
1012 gclog_or_tty->print_cr("BOT look up for top + 1: "PTR_FORMAT" "
1013 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
1014 addr_2, b_start_2, p);
1015 *failures = true;
1016 return;
1017 }
1018 }
1019
1020 // Look up an address between top and end
1021 size_t diff = pointer_delta(the_end, p) / 2;
1022 HeapWord* addr_3 = p + diff;
1023 if (addr_3 < the_end) {
1024 HeapWord* b_start_3 = _offsets.block_start_const(addr_3);
1025 if (b_start_3 != p) {
1026 gclog_or_tty->print_cr("BOT look up for top + diff: "PTR_FORMAT" "
1027 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
1028 addr_3, b_start_3, p);
1029 *failures = true;
1030 return;
1031 }
1032 }
1033
1034 // Look up end - 1
1035 HeapWord* addr_4 = the_end - 1;
1036 HeapWord* b_start_4 = _offsets.block_start_const(addr_4);
1037 if (b_start_4 != p) {
1038 gclog_or_tty->print_cr("BOT look up for end - 1: "PTR_FORMAT" "
1039 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
1040 addr_4, b_start_4, p);
1041 *failures = true;
1042 return;
1043 }
1044 }
1045
1046 if (is_humongous && object_num > 1) {
1047 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] is humongous "
1048 "but has "SIZE_FORMAT", objects",
1049 bottom(), end(), object_num);
1050 *failures = true;
1051 return;
1052 }
1053
1054 verify_strong_code_roots(vo, failures);
1055 }
1056
1057 void HeapRegion::verify() const {
1058 bool dummy = false;
1059 verify(VerifyOption_G1UsePrevMarking, /* failures */ &dummy);
1060 }
1061
1062 // G1OffsetTableContigSpace code; copied from space.cpp. Hope this can go
1063 // away eventually.
1064
1065 void G1OffsetTableContigSpace::clear(bool mangle_space) {
1066 ContiguousSpace::clear(mangle_space);
1067 _offsets.zero_bottom_entry();
1068 _offsets.initialize_threshold();
1069 }
1070
1071 void G1OffsetTableContigSpace::set_bottom(HeapWord* new_bottom) {
1072 Space::set_bottom(new_bottom);
1073 _offsets.set_bottom(new_bottom);
1074 }
1075
1076 void G1OffsetTableContigSpace::set_end(HeapWord* new_end) {
1077 Space::set_end(new_end);
1078 _offsets.resize(new_end - bottom());
1079 }
1080
1081 void G1OffsetTableContigSpace::print() const {
1082 print_short();
1083 gclog_or_tty->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", "
1084 INTPTR_FORMAT ", " INTPTR_FORMAT ")",
1085 bottom(), top(), _offsets.threshold(), end());
1086 }
1087
1088 HeapWord* G1OffsetTableContigSpace::initialize_threshold() {
1089 return _offsets.initialize_threshold();
1090 }
1091
1092 HeapWord* G1OffsetTableContigSpace::cross_threshold(HeapWord* start,
1093 HeapWord* end) {
1094 _offsets.alloc_block(start, end);
1095 return _offsets.threshold();
1096 }
1097
1098 HeapWord* G1OffsetTableContigSpace::saved_mark_word() const {
1099 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1100 assert( _gc_time_stamp <= g1h->get_gc_time_stamp(), "invariant" );
1101 if (_gc_time_stamp < g1h->get_gc_time_stamp())
1102 return top();
1103 else
1104 return ContiguousSpace::saved_mark_word();
1105 }
1106
1107 void G1OffsetTableContigSpace::set_saved_mark() {
1108 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1109 unsigned curr_gc_time_stamp = g1h->get_gc_time_stamp();
1110
1111 if (_gc_time_stamp < curr_gc_time_stamp) {
1112 // The order of these is important, as another thread might be
1113 // about to start scanning this region. If it does so after
1114 // set_saved_mark and before _gc_time_stamp = ..., then the latter
1115 // will be false, and it will pick up top() as the high water mark
1116 // of region. If it does so after _gc_time_stamp = ..., then it
1117 // will pick up the right saved_mark_word() as the high water mark
1118 // of the region. Either way, the behavior will be correct.
1119 ContiguousSpace::set_saved_mark();
1120 OrderAccess::storestore();
1121 _gc_time_stamp = curr_gc_time_stamp;
1122 // No need to do another barrier to flush the writes above. If
1123 // this is called in parallel with other threads trying to
1124 // allocate into the region, the caller should call this while
1125 // holding a lock and when the lock is released the writes will be
1126 // flushed.
1127 }
1128 }
1129
1130 G1OffsetTableContigSpace::
1131 G1OffsetTableContigSpace(G1BlockOffsetSharedArray* sharedOffsetArray,
1132 MemRegion mr) :
1133 _offsets(sharedOffsetArray, mr),
1134 _par_alloc_lock(Mutex::leaf, "OffsetTableContigSpace par alloc lock", true),
1135 _gc_time_stamp(0)
1136 {
1137 _offsets.set_space(this);
1138 // false ==> we'll do the clearing if there's clearing to be done.
1139 ContiguousSpace::initialize(mr, false, SpaceDecorator::Mangle);
1140 _offsets.zero_bottom_entry();
1141 _offsets.initialize_threshold();
1142 }