1 /*
2 * Copyright (c) 2001, 2012, 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 void HeapRegion::setup_heap_region_size(uintx min_heap_size) {
153 // region_size in bytes
154 uintx region_size = G1HeapRegionSize;
155 if (FLAG_IS_DEFAULT(G1HeapRegionSize)) {
156 // We base the automatic calculation on the min heap size. This
157 // can be problematic if the spread between min and max is quite
158 // wide, imagine -Xms128m -Xmx32g. But, if we decided it based on
159 // the max size, the region size might be way too large for the
160 // min size. Either way, some users might have to set the region
161 // size manually for some -Xms / -Xmx combos.
162
163 region_size = MAX2(min_heap_size / TARGET_REGION_NUMBER,
164 (uintx) MIN_REGION_SIZE);
165 }
166
167 int region_size_log = log2_long((jlong) region_size);
168 // Recalculate the region size to make sure it's a power of
169 // 2. This means that region_size is the largest power of 2 that's
170 // <= what we've calculated so far.
171 region_size = ((uintx)1 << region_size_log);
172
173 // Now make sure that we don't go over or under our limits.
174 if (region_size < MIN_REGION_SIZE) {
175 region_size = MIN_REGION_SIZE;
176 } else if (region_size > MAX_REGION_SIZE) {
177 region_size = MAX_REGION_SIZE;
178 }
179
180 // And recalculate the log.
181 region_size_log = log2_long((jlong) region_size);
182
183 // Now, set up the globals.
184 guarantee(LogOfHRGrainBytes == 0, "we should only set it once");
185 LogOfHRGrainBytes = region_size_log;
186
187 guarantee(LogOfHRGrainWords == 0, "we should only set it once");
188 LogOfHRGrainWords = LogOfHRGrainBytes - LogHeapWordSize;
189
190 guarantee(GrainBytes == 0, "we should only set it once");
191 // The cast to int is safe, given that we've bounded region_size by
192 // MIN_REGION_SIZE and MAX_REGION_SIZE.
193 GrainBytes = (size_t)region_size;
194
195 guarantee(GrainWords == 0, "we should only set it once");
196 GrainWords = GrainBytes >> LogHeapWordSize;
197 guarantee((size_t) 1 << LogOfHRGrainWords == GrainWords, "sanity");
198
199 guarantee(CardsPerRegion == 0, "we should only set it once");
200 CardsPerRegion = GrainBytes >> CardTableModRefBS::card_shift;
201 }
202
203 void HeapRegion::reset_after_compaction() {
204 G1OffsetTableContigSpace::reset_after_compaction();
205 // After a compaction the mark bitmap is invalid, so we must
206 // treat all objects as being inside the unmarked area.
207 zero_marked_bytes();
208 init_top_at_mark_start();
209 }
210
211 void HeapRegion::hr_clear(bool par, bool clear_space) {
212 assert(_humongous_type == NotHumongous,
213 "we should have already filtered out humongous regions");
214 assert(_humongous_start_region == NULL,
215 "we should have already filtered out humongous regions");
216 assert(_end == _orig_end,
217 "we should have already filtered out humongous regions");
218
219 _in_collection_set = false;
220
221 set_young_index_in_cset(-1);
222 uninstall_surv_rate_group();
223 set_young_type(NotYoung);
224 reset_pre_dummy_top();
225
226 if (!par) {
227 // If this is parallel, this will be done later.
228 HeapRegionRemSet* hrrs = rem_set();
229 hrrs->clear();
230 _claimed = InitialClaimValue;
231 }
232 zero_marked_bytes();
233
234 _offsets.resize(HeapRegion::GrainWords);
235 init_top_at_mark_start();
236 if (clear_space) clear(SpaceDecorator::Mangle);
237 }
238
239 void HeapRegion::par_clear() {
240 assert(used() == 0, "the region should have been already cleared");
241 assert(capacity() == HeapRegion::GrainBytes, "should be back to normal");
242 HeapRegionRemSet* hrrs = rem_set();
243 hrrs->clear();
244 CardTableModRefBS* ct_bs =
245 (CardTableModRefBS*)G1CollectedHeap::heap()->barrier_set();
246 ct_bs->clear(MemRegion(bottom(), end()));
247 }
248
249 void HeapRegion::calc_gc_efficiency() {
250 // GC efficiency is the ratio of how much space would be
251 // reclaimed over how long we predict it would take to reclaim it.
252 G1CollectedHeap* g1h = G1CollectedHeap::heap();
253 G1CollectorPolicy* g1p = g1h->g1_policy();
254
255 // Retrieve a prediction of the elapsed time for this region for
256 // a mixed gc because the region will only be evacuated during a
257 // mixed gc.
258 double region_elapsed_time_ms =
259 g1p->predict_region_elapsed_time_ms(this, false /* for_young_gc */);
260 _gc_efficiency = (double) reclaimable_bytes() / region_elapsed_time_ms;
261 }
262
263 void HeapRegion::set_startsHumongous(HeapWord* new_top, HeapWord* new_end) {
264 assert(!isHumongous(), "sanity / pre-condition");
265 assert(end() == _orig_end,
266 "Should be normal before the humongous object allocation");
267 assert(top() == bottom(), "should be empty");
268 assert(bottom() <= new_top && new_top <= new_end, "pre-condition");
269
270 _humongous_type = StartsHumongous;
271 _humongous_start_region = this;
272
273 set_end(new_end);
274 _offsets.set_for_starts_humongous(new_top);
275 }
276
277 void HeapRegion::set_continuesHumongous(HeapRegion* first_hr) {
278 assert(!isHumongous(), "sanity / pre-condition");
279 assert(end() == _orig_end,
280 "Should be normal before the humongous object allocation");
281 assert(top() == bottom(), "should be empty");
282 assert(first_hr->startsHumongous(), "pre-condition");
283
284 _humongous_type = ContinuesHumongous;
285 _humongous_start_region = first_hr;
286 }
287
288 void HeapRegion::set_notHumongous() {
289 assert(isHumongous(), "pre-condition");
290
291 if (startsHumongous()) {
292 assert(top() <= end(), "pre-condition");
293 set_end(_orig_end);
294 if (top() > end()) {
295 // at least one "continues humongous" region after it
296 set_top(end());
297 }
298 } else {
299 // continues humongous
300 assert(end() == _orig_end, "sanity");
301 }
302
303 assert(capacity() == HeapRegion::GrainBytes, "pre-condition");
304 _humongous_type = NotHumongous;
305 _humongous_start_region = NULL;
306 }
307
308 bool HeapRegion::claimHeapRegion(jint claimValue) {
309 jint current = _claimed;
310 if (current != claimValue) {
311 jint res = Atomic::cmpxchg(claimValue, &_claimed, current);
312 if (res == current) {
313 return true;
314 }
315 }
316 return false;
317 }
318
319 HeapWord* HeapRegion::next_block_start_careful(HeapWord* addr) {
320 HeapWord* low = addr;
321 HeapWord* high = end();
322 while (low < high) {
323 size_t diff = pointer_delta(high, low);
324 // Must add one below to bias toward the high amount. Otherwise, if
325 // "high" were at the desired value, and "low" were one less, we
326 // would not converge on "high". This is not symmetric, because
327 // we set "high" to a block start, which might be the right one,
328 // which we don't do for "low".
329 HeapWord* middle = low + (diff+1)/2;
330 if (middle == high) return high;
331 HeapWord* mid_bs = block_start_careful(middle);
332 if (mid_bs < addr) {
333 low = middle;
334 } else {
335 high = mid_bs;
336 }
337 }
338 assert(low == high && low >= addr, "Didn't work.");
339 return low;
340 }
341
342 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
343 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
344 #endif // _MSC_VER
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), _pending_removal(false),
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 _orig_end = mr.end();
368 // Note that initialize() will set the start of the unmarked area of the
369 // region.
370 hr_clear(false /*par*/, false /*clear_space*/);
371 set_top(bottom());
372 set_saved_mark();
373
374 assert(HeapRegionRemSet::num_par_rem_sets() > 0, "Invariant.");
375 }
376
377 CompactibleSpace* HeapRegion::next_compaction_space() const {
378 // We're not using an iterator given that it will wrap around when
379 // it reaches the last region and this is not what we want here.
380 G1CollectedHeap* g1h = G1CollectedHeap::heap();
381 uint index = hrs_index() + 1;
382 while (index < g1h->n_regions()) {
383 HeapRegion* hr = g1h->region_at(index);
384 if (!hr->isHumongous()) {
385 return hr;
386 }
387 index += 1;
388 }
389 return NULL;
390 }
391
392 void HeapRegion::save_marks() {
393 set_saved_mark();
394 }
395
396 void HeapRegion::oops_in_mr_iterate(MemRegion mr, ExtendedOopClosure* cl) {
397 HeapWord* p = mr.start();
398 HeapWord* e = mr.end();
399 oop obj;
400 while (p < e) {
401 obj = oop(p);
402 p += obj->oop_iterate(cl);
403 }
404 assert(p == e, "bad memregion: doesn't end on obj boundary");
405 }
406
407 #define HeapRegion_OOP_SINCE_SAVE_MARKS_DEFN(OopClosureType, nv_suffix) \
408 void HeapRegion::oop_since_save_marks_iterate##nv_suffix(OopClosureType* cl) { \
409 ContiguousSpace::oop_since_save_marks_iterate##nv_suffix(cl); \
410 }
411 SPECIALIZED_SINCE_SAVE_MARKS_CLOSURES(HeapRegion_OOP_SINCE_SAVE_MARKS_DEFN)
412
413
414 void HeapRegion::oop_before_save_marks_iterate(ExtendedOopClosure* cl) {
415 oops_in_mr_iterate(MemRegion(bottom(), saved_mark_word()), cl);
416 }
417
418 void HeapRegion::note_self_forwarding_removal_start(bool during_initial_mark,
419 bool during_conc_mark) {
420 // We always recreate the prev marking info and we'll explicitly
421 // mark all objects we find to be self-forwarded on the prev
422 // bitmap. So all objects need to be below PTAMS.
423 _prev_top_at_mark_start = top();
424 _prev_marked_bytes = 0;
425
426 if (during_initial_mark) {
427 // During initial-mark, we'll also explicitly mark all objects
428 // we find to be self-forwarded on the next bitmap. So all
429 // objects need to be below NTAMS.
430 _next_top_at_mark_start = top();
431 _next_marked_bytes = 0;
432 } else if (during_conc_mark) {
433 // During concurrent mark, all objects in the CSet (including
434 // the ones we find to be self-forwarded) are implicitly live.
435 // So all objects need to be above NTAMS.
436 _next_top_at_mark_start = bottom();
437 _next_marked_bytes = 0;
438 }
439 }
440
441 void HeapRegion::note_self_forwarding_removal_end(bool during_initial_mark,
442 bool during_conc_mark,
443 size_t marked_bytes) {
444 assert(0 <= marked_bytes && marked_bytes <= used(),
445 err_msg("marked: "SIZE_FORMAT" used: "SIZE_FORMAT,
446 marked_bytes, used()));
447 _prev_marked_bytes = marked_bytes;
448 }
449
450 HeapWord*
451 HeapRegion::object_iterate_mem_careful(MemRegion mr,
452 ObjectClosure* cl) {
453 G1CollectedHeap* g1h = G1CollectedHeap::heap();
454 // We used to use "block_start_careful" here. But we're actually happy
455 // to update the BOT while we do this...
456 HeapWord* cur = block_start(mr.start());
457 mr = mr.intersection(used_region());
458 if (mr.is_empty()) return NULL;
459 // Otherwise, find the obj that extends onto mr.start().
460
461 assert(cur <= mr.start()
462 && (oop(cur)->klass_or_null() == NULL ||
463 cur + oop(cur)->size() > mr.start()),
464 "postcondition of block_start");
465 oop obj;
466 while (cur < mr.end()) {
467 obj = oop(cur);
468 if (obj->klass_or_null() == NULL) {
469 // Ran into an unparseable point.
470 return cur;
471 } else if (!g1h->is_obj_dead(obj)) {
472 cl->do_object(obj);
473 }
474 if (cl->abort()) return cur;
475 // The check above must occur before the operation below, since an
476 // abort might invalidate the "size" operation.
477 cur += obj->size();
478 }
479 return NULL;
480 }
481
482 HeapWord*
483 HeapRegion::
484 oops_on_card_seq_iterate_careful(MemRegion mr,
485 FilterOutOfRegionClosure* cl,
486 bool filter_young,
487 jbyte* card_ptr) {
488 // Currently, we should only have to clean the card if filter_young
489 // is true and vice versa.
490 if (filter_young) {
491 assert(card_ptr != NULL, "pre-condition");
492 } else {
493 assert(card_ptr == NULL, "pre-condition");
494 }
495 G1CollectedHeap* g1h = G1CollectedHeap::heap();
496
497 // If we're within a stop-world GC, then we might look at a card in a
498 // GC alloc region that extends onto a GC LAB, which may not be
499 // parseable. Stop such at the "saved_mark" of the region.
500 if (g1h->is_gc_active()) {
501 mr = mr.intersection(used_region_at_save_marks());
502 } else {
503 mr = mr.intersection(used_region());
504 }
505 if (mr.is_empty()) return NULL;
506 // Otherwise, find the obj that extends onto mr.start().
507
508 // The intersection of the incoming mr (for the card) and the
509 // allocated part of the region is non-empty. This implies that
510 // we have actually allocated into this region. The code in
511 // G1CollectedHeap.cpp that allocates a new region sets the
512 // is_young tag on the region before allocating. Thus we
513 // safely know if this region is young.
514 if (is_young() && filter_young) {
515 return NULL;
516 }
517
518 assert(!is_young(), "check value of filter_young");
519
520 // We can only clean the card here, after we make the decision that
521 // the card is not young. And we only clean the card if we have been
522 // asked to (i.e., card_ptr != NULL).
523 if (card_ptr != NULL) {
524 *card_ptr = CardTableModRefBS::clean_card_val();
525 // We must complete this write before we do any of the reads below.
526 OrderAccess::storeload();
527 }
528
529 // Cache the boundaries of the memory region in some const locals
530 HeapWord* const start = mr.start();
531 HeapWord* const end = mr.end();
532
533 // We used to use "block_start_careful" here. But we're actually happy
534 // to update the BOT while we do this...
535 HeapWord* cur = block_start(start);
536 assert(cur <= start, "Postcondition");
537
538 oop obj;
539
540 HeapWord* next = cur;
541 while (next <= start) {
542 cur = next;
543 obj = oop(cur);
544 if (obj->klass_or_null() == NULL) {
545 // Ran into an unparseable point.
546 return cur;
547 }
548 // Otherwise...
549 next = (cur + obj->size());
550 }
551
552 // If we finish the above loop...We have a parseable object that
553 // begins on or before the start of the memory region, and ends
554 // inside or spans the entire region.
555
556 assert(obj == oop(cur), "sanity");
557 assert(cur <= start &&
558 obj->klass_or_null() != NULL &&
559 (cur + obj->size()) > start,
560 "Loop postcondition");
561
562 if (!g1h->is_obj_dead(obj)) {
563 obj->oop_iterate(cl, mr);
564 }
565
566 while (cur < end) {
567 obj = oop(cur);
568 if (obj->klass_or_null() == NULL) {
569 // Ran into an unparseable point.
570 return cur;
571 };
572
573 // Otherwise:
574 next = (cur + obj->size());
575
576 if (!g1h->is_obj_dead(obj)) {
577 if (next < end || !obj->is_objArray()) {
578 // This object either does not span the MemRegion
579 // boundary, or if it does it's not an array.
580 // Apply closure to whole object.
581 obj->oop_iterate(cl);
582 } else {
583 // This obj is an array that spans the boundary.
584 // Stop at the boundary.
585 obj->oop_iterate(cl, mr);
586 }
587 }
588 cur = next;
589 }
590 return NULL;
591 }
592
593 // Code roots support
594
595 void HeapRegion::add_strong_code_root(nmethod* nm) {
596 HeapRegionRemSet* hrrs = rem_set();
597 hrrs->add_strong_code_root(nm);
598 }
599
600 void HeapRegion::remove_strong_code_root(nmethod* nm) {
601 HeapRegionRemSet* hrrs = rem_set();
602 hrrs->remove_strong_code_root(nm);
603 }
604
605 void HeapRegion::migrate_strong_code_roots() {
606 assert(in_collection_set(), "only collection set regions");
607 assert(!isHumongous(), "not humongous regions");
608
609 HeapRegionRemSet* hrrs = rem_set();
610 hrrs->migrate_strong_code_roots();
611 }
612
613 void HeapRegion::strong_code_roots_do(CodeBlobClosure* blk) const {
614 HeapRegionRemSet* hrrs = rem_set();
615 hrrs->strong_code_roots_do(blk);
616 }
617
618 class VerifyStrongCodeRootOopClosure: public OopClosure {
619 const HeapRegion* _hr;
620 nmethod* _nm;
621 bool _failures;
622 bool _has_oops_in_region;
623
624 template <class T> void do_oop_work(T* p) {
625 T heap_oop = oopDesc::load_heap_oop(p);
626 if (!oopDesc::is_null(heap_oop)) {
627 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
628
629 // Note: not all the oops embedded in the nmethod are in the
630 // current region. We only look at those which are.
631 if (_hr->is_in(obj)) {
632 // Object is in the region. Check that its less than top
633 if (_hr->top() <= (HeapWord*)obj) {
634 // Object is above top
635 gclog_or_tty->print_cr("Object "PTR_FORMAT" in region "
636 "["PTR_FORMAT", "PTR_FORMAT") is above "
637 "top "PTR_FORMAT,
638 obj, _hr->bottom(), _hr->end(), _hr->top());
639 _failures = true;
640 return;
641 }
642 // Nmethod has at least one oop in the current region
643 _has_oops_in_region = true;
644 }
645 }
646 }
647
648 public:
649 VerifyStrongCodeRootOopClosure(const HeapRegion* hr, nmethod* nm):
650 _hr(hr), _failures(false), _has_oops_in_region(false) {}
651
652 void do_oop(narrowOop* p) { do_oop_work(p); }
653 void do_oop(oop* p) { do_oop_work(p); }
654
655 bool failures() { return _failures; }
656 bool has_oops_in_region() { return _has_oops_in_region; }
657 };
658
659 class VerifyStrongCodeRootCodeBlobClosure: public CodeBlobClosure {
660 const HeapRegion* _hr;
661 bool _failures;
662 public:
663 VerifyStrongCodeRootCodeBlobClosure(const HeapRegion* hr) :
664 _hr(hr), _failures(false) {}
665
666 void do_code_blob(CodeBlob* cb) {
667 nmethod* nm = (cb == NULL) ? NULL : cb->as_nmethod_or_null();
668 if (nm != NULL) {
669 // Verify that the nemthod is live
670 if (!nm->is_alive()) {
671 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] has dead nmethod "
672 PTR_FORMAT" in its strong code roots",
673 _hr->bottom(), _hr->end(), nm);
674 _failures = true;
675 } else {
676 VerifyStrongCodeRootOopClosure oop_cl(_hr, nm);
677 nm->oops_do(&oop_cl);
678 if (!oop_cl.has_oops_in_region()) {
679 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] has nmethod "
680 PTR_FORMAT" in its strong code roots "
681 "with no pointers into region",
682 _hr->bottom(), _hr->end(), nm);
683 _failures = true;
684 } else if (oop_cl.failures()) {
685 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] has other "
686 "failures for nmethod "PTR_FORMAT,
687 _hr->bottom(), _hr->end(), nm);
688 _failures = true;
689 }
690 }
691 }
692 }
693
694 bool failures() { return _failures; }
695 };
696
697 void HeapRegion::verify_strong_code_roots(VerifyOption vo, bool* failures) const {
698 if (!G1VerifyHeapRegionCodeRoots) {
699 // We're not verifying code roots.
700 return;
701 }
702 if (vo == VerifyOption_G1UseMarkWord) {
703 // Marking verification during a full GC is performed after class
704 // unloading, code cache unloading, etc so the strong code roots
705 // attached to each heap region are in an inconsistent state. They won't
706 // be consistent until the strong code roots are rebuilt after the
707 // actual GC. Skip verifying the strong code roots in this particular
708 // time.
709 assert(VerifyDuringGC, "only way to get here");
710 return;
711 }
712
713 HeapRegionRemSet* hrrs = rem_set();
714 int strong_code_roots_length = hrrs->strong_code_roots_list_length();
715
716 // if this region is empty then there should be no entries
717 // on its strong code root list
718 if (is_empty()) {
719 if (strong_code_roots_length > 0) {
720 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] is empty "
721 "but has "INT32_FORMAT" code root entries",
722 bottom(), end(), strong_code_roots_length);
723 *failures = true;
724 }
725 return;
726 }
727
728 // An H-region should have an empty strong code root list
729 if (isHumongous()) {
730 if (strong_code_roots_length > 0) {
731 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] is humongous "
732 "but has "INT32_FORMAT" code root entries",
733 bottom(), end(), strong_code_roots_length);
734 *failures = true;
735 }
736 return;
737 }
738
739 VerifyStrongCodeRootCodeBlobClosure cb_cl(this);
740 strong_code_roots_do(&cb_cl);
741
742 if (cb_cl.failures()) {
743 *failures = true;
744 }
745 }
746
747 void HeapRegion::print() const { print_on(gclog_or_tty); }
748 void HeapRegion::print_on(outputStream* st) const {
749 if (isHumongous()) {
750 if (startsHumongous())
751 st->print(" HS");
752 else
753 st->print(" HC");
754 } else {
755 st->print(" ");
756 }
757 if (in_collection_set())
758 st->print(" CS");
759 else
760 st->print(" ");
761 if (is_young())
762 st->print(is_survivor() ? " SU" : " Y ");
763 else
764 st->print(" ");
765 if (is_empty())
766 st->print(" F");
767 else
768 st->print(" ");
769 st->print(" TS %5d", _gc_time_stamp);
770 st->print(" PTAMS "PTR_FORMAT" NTAMS "PTR_FORMAT,
771 prev_top_at_mark_start(), next_top_at_mark_start());
772 G1OffsetTableContigSpace::print_on(st);
773 }
774
775 class VerifyLiveClosure: public OopClosure {
776 private:
777 G1CollectedHeap* _g1h;
778 CardTableModRefBS* _bs;
779 oop _containing_obj;
780 bool _failures;
781 int _n_failures;
782 VerifyOption _vo;
783 public:
784 // _vo == UsePrevMarking -> use "prev" marking information,
785 // _vo == UseNextMarking -> use "next" marking information,
786 // _vo == UseMarkWord -> use mark word from object header.
787 VerifyLiveClosure(G1CollectedHeap* g1h, VerifyOption vo) :
788 _g1h(g1h), _bs(NULL), _containing_obj(NULL),
789 _failures(false), _n_failures(0), _vo(vo)
790 {
791 BarrierSet* bs = _g1h->barrier_set();
792 if (bs->is_a(BarrierSet::CardTableModRef))
793 _bs = (CardTableModRefBS*)bs;
794 }
795
796 void set_containing_obj(oop obj) {
797 _containing_obj = obj;
798 }
799
800 bool failures() { return _failures; }
801 int n_failures() { return _n_failures; }
802
803 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
804 virtual void do_oop( oop* p) { do_oop_work(p); }
805
806 void print_object(outputStream* out, oop obj) {
807 #ifdef PRODUCT
808 Klass* k = obj->klass();
809 const char* class_name = InstanceKlass::cast(k)->external_name();
810 out->print_cr("class name %s", class_name);
811 #else // PRODUCT
812 obj->print_on(out);
813 #endif // PRODUCT
814 }
815
816 template <class T>
817 void do_oop_work(T* p) {
818 assert(_containing_obj != NULL, "Precondition");
819 assert(!_g1h->is_obj_dead_cond(_containing_obj, _vo),
820 "Precondition");
821 T heap_oop = oopDesc::load_heap_oop(p);
822 if (!oopDesc::is_null(heap_oop)) {
823 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
824 bool failed = false;
825 if (!_g1h->is_in_closed_subset(obj) || _g1h->is_obj_dead_cond(obj, _vo)) {
826 MutexLockerEx x(ParGCRareEvent_lock,
827 Mutex::_no_safepoint_check_flag);
828
829 if (!_failures) {
830 gclog_or_tty->print_cr("");
831 gclog_or_tty->print_cr("----------");
832 }
833 if (!_g1h->is_in_closed_subset(obj)) {
834 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
835 gclog_or_tty->print_cr("Field "PTR_FORMAT
836 " of live obj "PTR_FORMAT" in region "
837 "["PTR_FORMAT", "PTR_FORMAT")",
838 p, (void*) _containing_obj,
839 from->bottom(), from->end());
840 print_object(gclog_or_tty, _containing_obj);
841 gclog_or_tty->print_cr("points to obj "PTR_FORMAT" not in the heap",
842 (void*) obj);
843 } else {
844 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
845 HeapRegion* to = _g1h->heap_region_containing((HeapWord*)obj);
846 gclog_or_tty->print_cr("Field "PTR_FORMAT
847 " of live obj "PTR_FORMAT" in region "
848 "["PTR_FORMAT", "PTR_FORMAT")",
849 p, (void*) _containing_obj,
850 from->bottom(), from->end());
851 print_object(gclog_or_tty, _containing_obj);
852 gclog_or_tty->print_cr("points to dead obj "PTR_FORMAT" in region "
853 "["PTR_FORMAT", "PTR_FORMAT")",
854 (void*) obj, to->bottom(), to->end());
855 print_object(gclog_or_tty, obj);
856 }
857 gclog_or_tty->print_cr("----------");
858 gclog_or_tty->flush();
859 _failures = true;
860 failed = true;
861 _n_failures++;
862 }
863
864 if (!_g1h->full_collection() || G1VerifyRSetsDuringFullGC) {
865 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
866 HeapRegion* to = _g1h->heap_region_containing(obj);
867 if (from != NULL && to != NULL &&
868 from != to &&
869 !to->isHumongous()) {
870 jbyte cv_obj = *_bs->byte_for_const(_containing_obj);
871 jbyte cv_field = *_bs->byte_for_const(p);
872 const jbyte dirty = CardTableModRefBS::dirty_card_val();
873
874 bool is_bad = !(from->is_young()
875 || to->rem_set()->contains_reference(p)
876 || !G1HRRSFlushLogBuffersOnVerify && // buffers were not flushed
877 (_containing_obj->is_objArray() ?
878 cv_field == dirty
879 : cv_obj == dirty || cv_field == dirty));
880 if (is_bad) {
881 MutexLockerEx x(ParGCRareEvent_lock,
882 Mutex::_no_safepoint_check_flag);
883
884 if (!_failures) {
885 gclog_or_tty->print_cr("");
886 gclog_or_tty->print_cr("----------");
887 }
888 gclog_or_tty->print_cr("Missing rem set entry:");
889 gclog_or_tty->print_cr("Field "PTR_FORMAT" "
890 "of obj "PTR_FORMAT", "
891 "in region "HR_FORMAT,
892 p, (void*) _containing_obj,
893 HR_FORMAT_PARAMS(from));
894 _containing_obj->print_on(gclog_or_tty);
895 gclog_or_tty->print_cr("points to obj "PTR_FORMAT" "
896 "in region "HR_FORMAT,
897 (void*) obj,
898 HR_FORMAT_PARAMS(to));
899 obj->print_on(gclog_or_tty);
900 gclog_or_tty->print_cr("Obj head CTE = %d, field CTE = %d.",
901 cv_obj, cv_field);
902 gclog_or_tty->print_cr("----------");
903 gclog_or_tty->flush();
904 _failures = true;
905 if (!failed) _n_failures++;
906 }
907 }
908 }
909 }
910 }
911 };
912
913 // This really ought to be commoned up into OffsetTableContigSpace somehow.
914 // We would need a mechanism to make that code skip dead objects.
915
916 void HeapRegion::verify(VerifyOption vo,
917 bool* failures) const {
918 G1CollectedHeap* g1 = G1CollectedHeap::heap();
919 *failures = false;
920 HeapWord* p = bottom();
921 HeapWord* prev_p = NULL;
922 VerifyLiveClosure vl_cl(g1, vo);
923 bool is_humongous = isHumongous();
924 bool do_bot_verify = !is_young();
925 size_t object_num = 0;
926 while (p < top()) {
927 oop obj = oop(p);
928 size_t obj_size = obj->size();
929 object_num += 1;
930
931 if (is_humongous != g1->isHumongous(obj_size)) {
932 gclog_or_tty->print_cr("obj "PTR_FORMAT" is of %shumongous size ("
933 SIZE_FORMAT" words) in a %shumongous region",
934 p, g1->isHumongous(obj_size) ? "" : "non-",
935 obj_size, is_humongous ? "" : "non-");
936 *failures = true;
937 return;
938 }
939
940 // If it returns false, verify_for_object() will output the
941 // appropriate messasge.
942 if (do_bot_verify && !_offsets.verify_for_object(p, obj_size)) {
943 *failures = true;
944 return;
945 }
946
947 if (!g1->is_obj_dead_cond(obj, this, vo)) {
948 if (obj->is_oop()) {
949 Klass* klass = obj->klass();
950 if (!klass->is_metadata()) {
951 gclog_or_tty->print_cr("klass "PTR_FORMAT" of object "PTR_FORMAT" "
952 "not metadata", klass, obj);
953 *failures = true;
954 return;
955 } else if (!klass->is_klass()) {
956 gclog_or_tty->print_cr("klass "PTR_FORMAT" of object "PTR_FORMAT" "
957 "not a klass", klass, obj);
958 *failures = true;
959 return;
960 } else {
961 vl_cl.set_containing_obj(obj);
962 obj->oop_iterate_no_header(&vl_cl);
963 if (vl_cl.failures()) {
964 *failures = true;
965 }
966 if (G1MaxVerifyFailures >= 0 &&
967 vl_cl.n_failures() >= G1MaxVerifyFailures) {
968 return;
969 }
970 }
971 } else {
972 gclog_or_tty->print_cr(PTR_FORMAT" no an oop", obj);
973 *failures = true;
974 return;
975 }
976 }
977 prev_p = p;
978 p += obj_size;
979 }
980
981 if (p != top()) {
982 gclog_or_tty->print_cr("end of last object "PTR_FORMAT" "
983 "does not match top "PTR_FORMAT, p, top());
984 *failures = true;
985 return;
986 }
987
988 HeapWord* the_end = end();
989 assert(p == top(), "it should still hold");
990 // Do some extra BOT consistency checking for addresses in the
991 // range [top, end). BOT look-ups in this range should yield
992 // top. No point in doing that if top == end (there's nothing there).
993 if (p < the_end) {
994 // Look up top
995 HeapWord* addr_1 = p;
996 HeapWord* b_start_1 = _offsets.block_start_const(addr_1);
997 if (b_start_1 != p) {
998 gclog_or_tty->print_cr("BOT look up for top: "PTR_FORMAT" "
999 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
1000 addr_1, b_start_1, p);
1001 *failures = true;
1002 return;
1003 }
1004
1005 // Look up top + 1
1006 HeapWord* addr_2 = p + 1;
1007 if (addr_2 < the_end) {
1008 HeapWord* b_start_2 = _offsets.block_start_const(addr_2);
1009 if (b_start_2 != p) {
1010 gclog_or_tty->print_cr("BOT look up for top + 1: "PTR_FORMAT" "
1011 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
1012 addr_2, b_start_2, p);
1013 *failures = true;
1014 return;
1015 }
1016 }
1017
1018 // Look up an address between top and end
1019 size_t diff = pointer_delta(the_end, p) / 2;
1020 HeapWord* addr_3 = p + diff;
1021 if (addr_3 < the_end) {
1022 HeapWord* b_start_3 = _offsets.block_start_const(addr_3);
1023 if (b_start_3 != p) {
1024 gclog_or_tty->print_cr("BOT look up for top + diff: "PTR_FORMAT" "
1025 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
1026 addr_3, b_start_3, p);
1027 *failures = true;
1028 return;
1029 }
1030 }
1031
1032 // Loook up end - 1
1033 HeapWord* addr_4 = the_end - 1;
1034 HeapWord* b_start_4 = _offsets.block_start_const(addr_4);
1035 if (b_start_4 != p) {
1036 gclog_or_tty->print_cr("BOT look up for end - 1: "PTR_FORMAT" "
1037 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
1038 addr_4, b_start_4, p);
1039 *failures = true;
1040 return;
1041 }
1042 }
1043
1044 if (is_humongous && object_num > 1) {
1045 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] is humongous "
1046 "but has "SIZE_FORMAT", objects",
1047 bottom(), end(), object_num);
1048 *failures = true;
1049 return;
1050 }
1051
1052 verify_strong_code_roots(vo, failures);
1053 }
1054
1055 void HeapRegion::verify() const {
1056 bool dummy = false;
1057 verify(VerifyOption_G1UsePrevMarking, /* failures */ &dummy);
1058 }
1059
1060 // G1OffsetTableContigSpace code; copied from space.cpp. Hope this can go
1061 // away eventually.
1062
1063 void G1OffsetTableContigSpace::clear(bool mangle_space) {
1064 ContiguousSpace::clear(mangle_space);
1065 _offsets.zero_bottom_entry();
1066 _offsets.initialize_threshold();
1067 }
1068
1069 void G1OffsetTableContigSpace::set_bottom(HeapWord* new_bottom) {
1070 Space::set_bottom(new_bottom);
1071 _offsets.set_bottom(new_bottom);
1072 }
1073
1074 void G1OffsetTableContigSpace::set_end(HeapWord* new_end) {
1075 Space::set_end(new_end);
1076 _offsets.resize(new_end - bottom());
1077 }
1078
1079 void G1OffsetTableContigSpace::print() const {
1080 print_short();
1081 gclog_or_tty->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", "
1082 INTPTR_FORMAT ", " INTPTR_FORMAT ")",
1083 bottom(), top(), _offsets.threshold(), end());
1084 }
1085
1086 HeapWord* G1OffsetTableContigSpace::initialize_threshold() {
1087 return _offsets.initialize_threshold();
1088 }
1089
1090 HeapWord* G1OffsetTableContigSpace::cross_threshold(HeapWord* start,
1091 HeapWord* end) {
1092 _offsets.alloc_block(start, end);
1093 return _offsets.threshold();
1094 }
1095
1096 HeapWord* G1OffsetTableContigSpace::saved_mark_word() const {
1097 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1098 assert( _gc_time_stamp <= g1h->get_gc_time_stamp(), "invariant" );
1099 if (_gc_time_stamp < g1h->get_gc_time_stamp())
1100 return top();
1101 else
1102 return ContiguousSpace::saved_mark_word();
1103 }
1104
1105 void G1OffsetTableContigSpace::set_saved_mark() {
1106 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1107 unsigned curr_gc_time_stamp = g1h->get_gc_time_stamp();
1108
1109 if (_gc_time_stamp < curr_gc_time_stamp) {
1110 // The order of these is important, as another thread might be
1111 // about to start scanning this region. If it does so after
1112 // set_saved_mark and before _gc_time_stamp = ..., then the latter
1113 // will be false, and it will pick up top() as the high water mark
1114 // of region. If it does so after _gc_time_stamp = ..., then it
1115 // will pick up the right saved_mark_word() as the high water mark
1116 // of the region. Either way, the behaviour will be correct.
1117 ContiguousSpace::set_saved_mark();
1118 OrderAccess::storestore();
1119 _gc_time_stamp = curr_gc_time_stamp;
1120 // No need to do another barrier to flush the writes above. If
1121 // this is called in parallel with other threads trying to
1122 // allocate into the region, the caller should call this while
1123 // holding a lock and when the lock is released the writes will be
1124 // flushed.
1125 }
1126 }
1127
1128 G1OffsetTableContigSpace::
1129 G1OffsetTableContigSpace(G1BlockOffsetSharedArray* sharedOffsetArray,
1130 MemRegion mr) :
1131 _offsets(sharedOffsetArray, mr),
1132 _par_alloc_lock(Mutex::leaf, "OffsetTableContigSpace par alloc lock", true),
1133 _gc_time_stamp(0)
1134 {
1135 _offsets.set_space(this);
1136 // false ==> we'll do the clearing if there's clearing to be done.
1137 ContiguousSpace::initialize(mr, false, SpaceDecorator::Mangle);
1138 _offsets.zero_bottom_entry();
1139 _offsets.initialize_threshold();
1140 }