1 /*
2 * Copyright (c) 2001, 2014, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "code/nmethod.hpp"
27 #include "gc_implementation/g1/g1BlockOffsetTable.inline.hpp"
28 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
29 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
30 #include "gc_implementation/g1/heapRegion.inline.hpp"
31 #include "gc_implementation/g1/heapRegionRemSet.hpp"
32 #include "gc_implementation/g1/heapRegionSeq.inline.hpp"
33 #include "gc_implementation/shared/liveRange.hpp"
34 #include "memory/genOopClosures.inline.hpp"
35 #include "memory/iterator.hpp"
36 #include "memory/space.inline.hpp"
37 #include "oops/oop.inline.hpp"
38 #include "runtime/orderAccess.inline.hpp"
39
40 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
41
42 int HeapRegion::LogOfHRGrainBytes = 0;
43 int HeapRegion::LogOfHRGrainWords = 0;
44 size_t HeapRegion::GrainBytes = 0;
45 size_t HeapRegion::GrainWords = 0;
46 size_t HeapRegion::CardsPerRegion = 0;
47
48 HeapRegionDCTOC::HeapRegionDCTOC(G1CollectedHeap* g1,
49 HeapRegion* hr, ExtendedOopClosure* cl,
50 CardTableModRefBS::PrecisionStyle precision,
51 FilterKind fk) :
52 DirtyCardToOopClosure(hr, cl, precision, NULL),
53 _hr(hr), _fk(fk), _g1(g1) { }
54
55 FilterOutOfRegionClosure::FilterOutOfRegionClosure(HeapRegion* r,
56 OopClosure* oc) :
57 _r_bottom(r->bottom()), _r_end(r->end()), _oc(oc) { }
58
59 template<class ClosureType>
60 HeapWord* walk_mem_region_loop(ClosureType* cl, G1CollectedHeap* g1h,
61 HeapRegion* hr,
62 HeapWord* cur, HeapWord* top) {
63 oop cur_oop = oop(cur);
64 size_t oop_size = hr->block_size(cur);
65 HeapWord* next_obj = cur + oop_size;
66 while (next_obj < top) {
67 // Keep filtering the remembered set.
68 if (!g1h->is_obj_dead(cur_oop, hr)) {
69 // Bottom lies entirely below top, so we can call the
70 // non-memRegion version of oop_iterate below.
71 cur_oop->oop_iterate(cl);
72 }
73 cur = next_obj;
74 cur_oop = oop(cur);
75 oop_size = hr->block_size(cur);
76 next_obj = cur + oop_size;
77 }
78 return cur;
79 }
80
81 void HeapRegionDCTOC::walk_mem_region(MemRegion mr,
82 HeapWord* bottom,
83 HeapWord* top) {
84 G1CollectedHeap* g1h = _g1;
85 size_t oop_size;
86 ExtendedOopClosure* cl2 = NULL;
87
88 FilterIntoCSClosure intoCSFilt(this, g1h, _cl);
89 FilterOutOfRegionClosure outOfRegionFilt(_hr, _cl);
90
91 switch (_fk) {
92 case NoFilterKind: cl2 = _cl; break;
93 case IntoCSFilterKind: cl2 = &intoCSFilt; break;
94 case OutOfRegionFilterKind: cl2 = &outOfRegionFilt; break;
95 default: ShouldNotReachHere();
96 }
97
98 // Start filtering what we add to the remembered set. If the object is
99 // not considered dead, either because it is marked (in the mark bitmap)
100 // or it was allocated after marking finished, then we add it. Otherwise
101 // we can safely ignore the object.
102 if (!g1h->is_obj_dead(oop(bottom), _hr)) {
103 oop_size = oop(bottom)->oop_iterate(cl2, mr);
104 } else {
105 oop_size = _hr->block_size(bottom);
106 }
107
108 bottom += oop_size;
109
110 if (bottom < top) {
111 // We replicate the loop below for several kinds of possible filters.
112 switch (_fk) {
113 case NoFilterKind:
114 bottom = walk_mem_region_loop(_cl, g1h, _hr, bottom, top);
115 break;
116
117 case IntoCSFilterKind: {
118 FilterIntoCSClosure filt(this, g1h, _cl);
119 bottom = walk_mem_region_loop(&filt, g1h, _hr, bottom, top);
120 break;
121 }
122
123 case OutOfRegionFilterKind: {
124 FilterOutOfRegionClosure filt(_hr, _cl);
125 bottom = walk_mem_region_loop(&filt, g1h, _hr, bottom, top);
126 break;
127 }
128
129 default:
130 ShouldNotReachHere();
131 }
132
133 // Last object. Need to do dead-obj filtering here too.
134 if (!g1h->is_obj_dead(oop(bottom), _hr)) {
135 oop(bottom)->oop_iterate(cl2, mr);
136 }
137 }
138 }
139
140 // Minimum region size; we won't go lower than that.
141 // We might want to decrease this in the future, to deal with small
142 // heaps a bit more efficiently.
143 #define MIN_REGION_SIZE ( 1024 * 1024 )
144
145 // Maximum region size; we don't go higher than that. There's a good
146 // reason for having an upper bound. We don't want regions to get too
147 // large, otherwise cleanup's effectiveness would decrease as there
148 // will be fewer opportunities to find totally empty regions after
149 // marking.
150 #define MAX_REGION_SIZE ( 32 * 1024 * 1024 )
151
152 // The automatic region size calculation will try to have around this
153 // many regions in the heap (based on the min heap size).
154 #define TARGET_REGION_NUMBER 2048
155
156 size_t HeapRegion::max_region_size() {
157 return (size_t)MAX_REGION_SIZE;
158 }
159
160 void HeapRegion::setup_heap_region_size(size_t initial_heap_size, size_t max_heap_size) {
161 uintx region_size = G1HeapRegionSize;
162 if (FLAG_IS_DEFAULT(G1HeapRegionSize)) {
163 size_t average_heap_size = (initial_heap_size + max_heap_size) / 2;
164 region_size = MAX2(average_heap_size / TARGET_REGION_NUMBER,
165 (uintx) MIN_REGION_SIZE);
166 }
167
168 int region_size_log = log2_long((jlong) region_size);
169 // Recalculate the region size to make sure it's a power of
170 // 2. This means that region_size is the largest power of 2 that's
171 // <= what we've calculated so far.
172 region_size = ((uintx)1 << region_size_log);
173
174 // Now make sure that we don't go over or under our limits.
175 if (region_size < MIN_REGION_SIZE) {
176 region_size = MIN_REGION_SIZE;
177 } else if (region_size > MAX_REGION_SIZE) {
178 region_size = MAX_REGION_SIZE;
179 }
180
181 // And recalculate the log.
182 region_size_log = log2_long((jlong) region_size);
183
184 // Now, set up the globals.
185 guarantee(LogOfHRGrainBytes == 0, "we should only set it once");
186 LogOfHRGrainBytes = region_size_log;
187
188 guarantee(LogOfHRGrainWords == 0, "we should only set it once");
189 LogOfHRGrainWords = LogOfHRGrainBytes - LogHeapWordSize;
190
191 guarantee(GrainBytes == 0, "we should only set it once");
192 // The cast to int is safe, given that we've bounded region_size by
193 // MIN_REGION_SIZE and MAX_REGION_SIZE.
194 GrainBytes = (size_t)region_size;
195
196 guarantee(GrainWords == 0, "we should only set it once");
197 GrainWords = GrainBytes >> LogHeapWordSize;
198 guarantee((size_t) 1 << LogOfHRGrainWords == GrainWords, "sanity");
199
200 guarantee(CardsPerRegion == 0, "we should only set it once");
201 CardsPerRegion = GrainBytes >> CardTableModRefBS::card_shift;
202 }
203
204 void HeapRegion::reset_after_compaction() {
205 G1OffsetTableContigSpace::reset_after_compaction();
206 // After a compaction the mark bitmap is invalid, so we must
207 // treat all objects as being inside the unmarked area.
208 zero_marked_bytes();
209 init_top_at_mark_start();
210 }
211
212 void HeapRegion::hr_clear(bool par, bool clear_space, bool locked) {
213 assert(_humongous_type == NotHumongous,
214 "we should have already filtered out humongous regions");
215 assert(_humongous_start_region == NULL,
216 "we should have already filtered out humongous regions");
217 assert(_end == _orig_end,
218 "we should have already filtered out humongous regions");
219
220 _in_collection_set = false;
221
222 set_young_index_in_cset(-1);
223 uninstall_surv_rate_group();
224 set_young_type(NotYoung);
225 reset_pre_dummy_top();
226
227 if (!par) {
228 // If this is parallel, this will be done later.
229 HeapRegionRemSet* hrrs = rem_set();
230 if (locked) {
231 hrrs->clear_locked();
232 } else {
233 hrrs->clear();
234 }
235 _claimed = InitialClaimValue;
236 }
237 zero_marked_bytes();
238
239 _offsets.resize(HeapRegion::GrainWords);
240 init_top_at_mark_start();
241 if (clear_space) clear(SpaceDecorator::Mangle);
242 }
243
244 void HeapRegion::par_clear() {
245 assert(used() == 0, "the region should have been already cleared");
246 assert(capacity() == HeapRegion::GrainBytes, "should be back to normal");
247 HeapRegionRemSet* hrrs = rem_set();
248 hrrs->clear();
249 CardTableModRefBS* ct_bs =
250 (CardTableModRefBS*)G1CollectedHeap::heap()->barrier_set();
251 ct_bs->clear(MemRegion(bottom(), end()));
252 }
253
254 void HeapRegion::calc_gc_efficiency() {
255 // GC efficiency is the ratio of how much space would be
256 // reclaimed over how long we predict it would take to reclaim it.
257 G1CollectedHeap* g1h = G1CollectedHeap::heap();
258 G1CollectorPolicy* g1p = g1h->g1_policy();
259
260 // Retrieve a prediction of the elapsed time for this region for
261 // a mixed gc because the region will only be evacuated during a
262 // mixed gc.
263 double region_elapsed_time_ms =
264 g1p->predict_region_elapsed_time_ms(this, false /* for_young_gc */);
265 _gc_efficiency = (double) reclaimable_bytes() / region_elapsed_time_ms;
266 }
267
268 void HeapRegion::set_startsHumongous(HeapWord* new_top, HeapWord* new_end) {
269 assert(!isHumongous(), "sanity / pre-condition");
270 assert(end() == _orig_end,
271 "Should be normal before the humongous object allocation");
272 assert(top() == bottom(), "should be empty");
273 assert(bottom() <= new_top && new_top <= new_end, "pre-condition");
274
275 _humongous_type = StartsHumongous;
276 _humongous_start_region = this;
277
278 set_end(new_end);
279 _offsets.set_for_starts_humongous(new_top);
280 }
281
282 void HeapRegion::set_continuesHumongous(HeapRegion* first_hr) {
283 assert(!isHumongous(), "sanity / pre-condition");
284 assert(end() == _orig_end,
285 "Should be normal before the humongous object allocation");
286 assert(top() == bottom(), "should be empty");
287 assert(first_hr->startsHumongous(), "pre-condition");
288
289 _humongous_type = ContinuesHumongous;
290 _humongous_start_region = first_hr;
291 }
292
293 void HeapRegion::set_notHumongous() {
294 assert(isHumongous(), "pre-condition");
295
296 if (startsHumongous()) {
297 assert(top() <= end(), "pre-condition");
298 set_end(_orig_end);
299 if (top() > end()) {
300 // at least one "continues humongous" region after it
301 set_top(end());
302 }
303 } else {
304 // continues humongous
305 assert(end() == _orig_end, "sanity");
306 }
307
308 assert(capacity() == HeapRegion::GrainBytes, "pre-condition");
309 _humongous_type = NotHumongous;
310 _humongous_start_region = NULL;
311 }
312
313 bool HeapRegion::claimHeapRegion(jint claimValue) {
314 jint current = _claimed;
315 if (current != claimValue) {
316 jint res = Atomic::cmpxchg(claimValue, &_claimed, current);
317 if (res == current) {
318 return true;
319 }
320 }
321 return false;
322 }
323
324 HeapWord* HeapRegion::next_block_start_careful(HeapWord* addr) {
325 HeapWord* low = addr;
326 HeapWord* high = end();
327 while (low < high) {
328 size_t diff = pointer_delta(high, low);
329 // Must add one below to bias toward the high amount. Otherwise, if
330 // "high" were at the desired value, and "low" were one less, we
331 // would not converge on "high". This is not symmetric, because
332 // we set "high" to a block start, which might be the right one,
333 // which we don't do for "low".
334 HeapWord* middle = low + (diff+1)/2;
335 if (middle == high) return high;
336 HeapWord* mid_bs = block_start_careful(middle);
337 if (mid_bs < addr) {
338 low = middle;
339 } else {
340 high = mid_bs;
341 }
342 }
343 assert(low == high && low >= addr, "Didn't work.");
344 return low;
345 }
346
347 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
348 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
349 #endif // _MSC_VER
350
351
352 HeapRegion::HeapRegion(uint hrs_index,
353 G1BlockOffsetSharedArray* sharedOffsetArray,
354 MemRegion mr) :
355 G1OffsetTableContigSpace(sharedOffsetArray, mr),
356 _hrs_index(hrs_index),
357 _humongous_type(NotHumongous), _humongous_start_region(NULL),
358 _in_collection_set(false),
359 _next_in_special_set(NULL), _orig_end(NULL),
360 _claimed(InitialClaimValue), _evacuation_failed(false),
361 _prev_marked_bytes(0), _next_marked_bytes(0), _gc_efficiency(0.0),
362 _young_type(NotYoung), _next_young_region(NULL),
363 _next_dirty_cards_region(NULL), _next(NULL), _prev(NULL), _pending_removal(false),
364 #ifdef ASSERT
365 _containing_set(NULL),
366 #endif // ASSERT
367 _young_index_in_cset(-1), _surv_rate_group(NULL), _age_index(-1),
368 _rem_set(NULL), _recorded_rs_length(0), _predicted_elapsed_time_ms(0),
369 _predicted_bytes_to_copy(0)
370 {
371 _rem_set = new HeapRegionRemSet(sharedOffsetArray, this);
372 _orig_end = mr.end();
373 // Note that initialize() will set the start of the unmarked area of the
374 // region.
375 hr_clear(false /*par*/, false /*clear_space*/);
376 set_top(bottom());
377 record_top_and_timestamp();
378
379 assert(HeapRegionRemSet::num_par_rem_sets() > 0, "Invariant.");
380 }
381
382 CompactibleSpace* HeapRegion::next_compaction_space() const {
383 // We're not using an iterator given that it will wrap around when
384 // it reaches the last region and this is not what we want here.
385 G1CollectedHeap* g1h = G1CollectedHeap::heap();
386 uint index = hrs_index() + 1;
387 while (index < g1h->n_regions()) {
388 HeapRegion* hr = g1h->region_at(index);
389 if (!hr->isHumongous()) {
390 return hr;
391 }
392 index += 1;
393 }
394 return NULL;
395 }
396
397 void HeapRegion::note_self_forwarding_removal_start(bool during_initial_mark,
398 bool during_conc_mark) {
399 // We always recreate the prev marking info and we'll explicitly
400 // mark all objects we find to be self-forwarded on the prev
401 // bitmap. So all objects need to be below PTAMS.
402 _prev_top_at_mark_start = top();
403 _prev_marked_bytes = 0;
404
405 if (during_initial_mark) {
406 // During initial-mark, we'll also explicitly mark all objects
407 // we find to be self-forwarded on the next bitmap. So all
408 // objects need to be below NTAMS.
409 _next_top_at_mark_start = top();
410 _next_marked_bytes = 0;
411 } else if (during_conc_mark) {
412 // During concurrent mark, all objects in the CSet (including
413 // the ones we find to be self-forwarded) are implicitly live.
414 // So all objects need to be above NTAMS.
415 _next_top_at_mark_start = bottom();
416 _next_marked_bytes = 0;
417 }
418 }
419
420 void HeapRegion::note_self_forwarding_removal_end(bool during_initial_mark,
421 bool during_conc_mark,
422 size_t marked_bytes) {
423 assert(0 <= marked_bytes && marked_bytes <= used(),
424 err_msg("marked: "SIZE_FORMAT" used: "SIZE_FORMAT,
425 marked_bytes, used()));
426 _prev_marked_bytes = marked_bytes;
427 }
428
429 HeapWord*
430 HeapRegion::object_iterate_mem_careful(MemRegion mr,
431 ObjectClosure* cl) {
432 G1CollectedHeap* g1h = G1CollectedHeap::heap();
433 // We used to use "block_start_careful" here. But we're actually happy
434 // to update the BOT while we do this...
435 HeapWord* cur = block_start(mr.start());
436 mr = mr.intersection(used_region());
437 if (mr.is_empty()) return NULL;
438 // Otherwise, find the obj that extends onto mr.start().
439
440 assert(cur <= mr.start()
441 && (oop(cur)->klass_or_null() == NULL ||
442 cur + oop(cur)->size() > mr.start()),
443 "postcondition of block_start");
444 oop obj;
445 while (cur < mr.end()) {
446 obj = oop(cur);
447 if (obj->klass_or_null() == NULL) {
448 // Ran into an unparseable point.
449 return cur;
450 } else if (!g1h->is_obj_dead(obj)) {
451 cl->do_object(obj);
452 }
453 cur += block_size(cur);
454 }
455 return NULL;
456 }
457
458 HeapWord*
459 HeapRegion::
460 oops_on_card_seq_iterate_careful(MemRegion mr,
461 FilterOutOfRegionClosure* cl,
462 bool filter_young,
463 jbyte* card_ptr) {
464 // Currently, we should only have to clean the card if filter_young
465 // is true and vice versa.
466 if (filter_young) {
467 assert(card_ptr != NULL, "pre-condition");
468 } else {
469 assert(card_ptr == NULL, "pre-condition");
470 }
471 G1CollectedHeap* g1h = G1CollectedHeap::heap();
472
473 // If we're within a stop-world GC, then we might look at a card in a
474 // GC alloc region that extends onto a GC LAB, which may not be
475 // parseable. Stop such at the "saved_mark" of the region.
476 if (g1h->is_gc_active()) {
477 mr = mr.intersection(used_region_at_save_marks());
478 } else {
479 mr = mr.intersection(used_region());
480 }
481 if (mr.is_empty()) return NULL;
482 // Otherwise, find the obj that extends onto mr.start().
483
484 // The intersection of the incoming mr (for the card) and the
485 // allocated part of the region is non-empty. This implies that
486 // we have actually allocated into this region. The code in
487 // G1CollectedHeap.cpp that allocates a new region sets the
488 // is_young tag on the region before allocating. Thus we
489 // safely know if this region is young.
490 if (is_young() && filter_young) {
491 return NULL;
492 }
493
494 assert(!is_young(), "check value of filter_young");
495
496 // We can only clean the card here, after we make the decision that
497 // the card is not young. And we only clean the card if we have been
498 // asked to (i.e., card_ptr != NULL).
499 if (card_ptr != NULL) {
500 *card_ptr = CardTableModRefBS::clean_card_val();
501 // We must complete this write before we do any of the reads below.
502 OrderAccess::storeload();
503 }
504
505 // Cache the boundaries of the memory region in some const locals
506 HeapWord* const start = mr.start();
507 HeapWord* const end = mr.end();
508
509 // We used to use "block_start_careful" here. But we're actually happy
510 // to update the BOT while we do this...
511 HeapWord* cur = block_start(start);
512 assert(cur <= start, "Postcondition");
513
514 oop obj;
515
516 HeapWord* next = cur;
517 while (next <= start) {
518 cur = next;
519 obj = oop(cur);
520 if (obj->klass_or_null() == NULL) {
521 // Ran into an unparseable point.
522 return cur;
523 }
524 // Otherwise...
525 next = cur + block_size(cur);
526 }
527
528 // If we finish the above loop...We have a parseable object that
529 // begins on or before the start of the memory region, and ends
530 // inside or spans the entire region.
531
532 assert(obj == oop(cur), "sanity");
533 assert(cur <= start, "Loop postcondition");
534 assert(obj->klass_or_null() != NULL, "Loop postcondition");
535 assert((cur + block_size(cur)) > start, "Loop postcondition");
536
537 if (!g1h->is_obj_dead(obj)) {
538 obj->oop_iterate(cl, mr);
539 }
540
541 while (cur < end) {
542 obj = oop(cur);
543 if (obj->klass_or_null() == NULL) {
544 // Ran into an unparseable point.
545 return cur;
546 };
547
548 // Otherwise:
549 next = cur + block_size(cur);
550
551 if (!g1h->is_obj_dead(obj)) {
552 if (next < end || !obj->is_objArray()) {
553 // This object either does not span the MemRegion
554 // boundary, or if it does it's not an array.
555 // Apply closure to whole object.
556 obj->oop_iterate(cl);
557 } else {
558 // This obj is an array that spans the boundary.
559 // Stop at the boundary.
560 obj->oop_iterate(cl, mr);
561 }
562 }
563 cur = next;
564 }
565 return NULL;
566 }
567
568 // Code roots support
569
570 void HeapRegion::add_strong_code_root(nmethod* nm) {
571 HeapRegionRemSet* hrrs = rem_set();
572 hrrs->add_strong_code_root(nm);
573 }
574
575 void HeapRegion::remove_strong_code_root(nmethod* nm) {
576 HeapRegionRemSet* hrrs = rem_set();
577 hrrs->remove_strong_code_root(nm);
578 }
579
580 void HeapRegion::migrate_strong_code_roots() {
581 assert(in_collection_set(), "only collection set regions");
582 assert(!isHumongous(),
583 err_msg("humongous region "HR_FORMAT" should not have been added to collection set",
584 HR_FORMAT_PARAMS(this)));
585
586 HeapRegionRemSet* hrrs = rem_set();
587 hrrs->migrate_strong_code_roots();
588 }
589
590 void HeapRegion::strong_code_roots_do(CodeBlobClosure* blk) const {
591 HeapRegionRemSet* hrrs = rem_set();
592 hrrs->strong_code_roots_do(blk);
593 }
594
595 class VerifyStrongCodeRootOopClosure: public OopClosure {
596 const HeapRegion* _hr;
597 nmethod* _nm;
598 bool _failures;
599 bool _has_oops_in_region;
600
601 template <class T> void do_oop_work(T* p) {
602 T heap_oop = oopDesc::load_heap_oop(p);
603 if (!oopDesc::is_null(heap_oop)) {
604 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
605
606 // Note: not all the oops embedded in the nmethod are in the
607 // current region. We only look at those which are.
608 if (_hr->is_in(obj)) {
609 // Object is in the region. Check that its less than top
610 if (_hr->top() <= (HeapWord*)obj) {
611 // Object is above top
612 gclog_or_tty->print_cr("Object "PTR_FORMAT" in region "
613 "["PTR_FORMAT", "PTR_FORMAT") is above "
614 "top "PTR_FORMAT,
615 (void *)obj, _hr->bottom(), _hr->end(), _hr->top());
616 _failures = true;
617 return;
618 }
619 // Nmethod has at least one oop in the current region
620 _has_oops_in_region = true;
621 }
622 }
623 }
624
625 public:
626 VerifyStrongCodeRootOopClosure(const HeapRegion* hr, nmethod* nm):
627 _hr(hr), _failures(false), _has_oops_in_region(false) {}
628
629 void do_oop(narrowOop* p) { do_oop_work(p); }
630 void do_oop(oop* p) { do_oop_work(p); }
631
632 bool failures() { return _failures; }
633 bool has_oops_in_region() { return _has_oops_in_region; }
634 };
635
636 class VerifyStrongCodeRootCodeBlobClosure: public CodeBlobClosure {
637 const HeapRegion* _hr;
638 bool _failures;
639 public:
640 VerifyStrongCodeRootCodeBlobClosure(const HeapRegion* hr) :
641 _hr(hr), _failures(false) {}
642
643 void do_code_blob(CodeBlob* cb) {
644 nmethod* nm = (cb == NULL) ? NULL : cb->as_nmethod_or_null();
645 if (nm != NULL) {
646 // Verify that the nemthod is live
647 if (!nm->is_alive()) {
648 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] has dead nmethod "
649 PTR_FORMAT" in its strong code roots",
650 _hr->bottom(), _hr->end(), nm);
651 _failures = true;
652 } else {
653 VerifyStrongCodeRootOopClosure oop_cl(_hr, nm);
654 nm->oops_do(&oop_cl);
655 if (!oop_cl.has_oops_in_region()) {
656 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] has nmethod "
657 PTR_FORMAT" in its strong code roots "
658 "with no pointers into region",
659 _hr->bottom(), _hr->end(), nm);
660 _failures = true;
661 } else if (oop_cl.failures()) {
662 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] has other "
663 "failures for nmethod "PTR_FORMAT,
664 _hr->bottom(), _hr->end(), nm);
665 _failures = true;
666 }
667 }
668 }
669 }
670
671 bool failures() { return _failures; }
672 };
673
674 void HeapRegion::verify_strong_code_roots(VerifyOption vo, bool* failures) const {
675 if (!G1VerifyHeapRegionCodeRoots) {
676 // We're not verifying code roots.
677 return;
678 }
679 if (vo == VerifyOption_G1UseMarkWord) {
680 // Marking verification during a full GC is performed after class
681 // unloading, code cache unloading, etc so the strong code roots
682 // attached to each heap region are in an inconsistent state. They won't
683 // be consistent until the strong code roots are rebuilt after the
684 // actual GC. Skip verifying the strong code roots in this particular
685 // time.
686 assert(VerifyDuringGC, "only way to get here");
687 return;
688 }
689
690 HeapRegionRemSet* hrrs = rem_set();
691 size_t strong_code_roots_length = hrrs->strong_code_roots_list_length();
692
693 // if this region is empty then there should be no entries
694 // on its strong code root list
695 if (is_empty()) {
696 if (strong_code_roots_length > 0) {
697 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] is empty "
698 "but has "SIZE_FORMAT" code root entries",
699 bottom(), end(), strong_code_roots_length);
700 *failures = true;
701 }
702 return;
703 }
704
705 if (continuesHumongous()) {
706 if (strong_code_roots_length > 0) {
707 gclog_or_tty->print_cr("region "HR_FORMAT" is a continuation of a humongous "
708 "region but has "SIZE_FORMAT" code root entries",
709 HR_FORMAT_PARAMS(this), strong_code_roots_length);
710 *failures = true;
711 }
712 return;
713 }
714
715 VerifyStrongCodeRootCodeBlobClosure cb_cl(this);
716 strong_code_roots_do(&cb_cl);
717
718 if (cb_cl.failures()) {
719 *failures = true;
720 }
721 }
722
723 void HeapRegion::print() const { print_on(gclog_or_tty); }
724 void HeapRegion::print_on(outputStream* st) const {
725 if (isHumongous()) {
726 if (startsHumongous())
727 st->print(" HS");
728 else
729 st->print(" HC");
730 } else {
731 st->print(" ");
732 }
733 if (in_collection_set())
734 st->print(" CS");
735 else
736 st->print(" ");
737 if (is_young())
738 st->print(is_survivor() ? " SU" : " Y ");
739 else
740 st->print(" ");
741 if (is_empty())
742 st->print(" F");
743 else
744 st->print(" ");
745 st->print(" TS %5d", _gc_time_stamp);
746 st->print(" PTAMS "PTR_FORMAT" NTAMS "PTR_FORMAT,
747 prev_top_at_mark_start(), next_top_at_mark_start());
748 G1OffsetTableContigSpace::print_on(st);
749 }
750
751 class VerifyLiveClosure: public OopClosure {
752 private:
753 G1CollectedHeap* _g1h;
754 CardTableModRefBS* _bs;
755 oop _containing_obj;
756 bool _failures;
757 int _n_failures;
758 VerifyOption _vo;
759 public:
760 // _vo == UsePrevMarking -> use "prev" marking information,
761 // _vo == UseNextMarking -> use "next" marking information,
762 // _vo == UseMarkWord -> use mark word from object header.
763 VerifyLiveClosure(G1CollectedHeap* g1h, VerifyOption vo) :
764 _g1h(g1h), _bs(NULL), _containing_obj(NULL),
765 _failures(false), _n_failures(0), _vo(vo)
766 {
767 BarrierSet* bs = _g1h->barrier_set();
768 if (bs->is_a(BarrierSet::CardTableModRef))
769 _bs = (CardTableModRefBS*)bs;
770 }
771
772 void set_containing_obj(oop obj) {
773 _containing_obj = obj;
774 }
775
776 bool failures() { return _failures; }
777 int n_failures() { return _n_failures; }
778
779 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
780 virtual void do_oop( oop* p) { do_oop_work(p); }
781
782 void print_object(outputStream* out, oop obj) {
783 #ifdef PRODUCT
784 Klass* k = obj->klass();
785 const char* class_name = InstanceKlass::cast(k)->external_name();
786 out->print_cr("class name %s", class_name);
787 #else // PRODUCT
788 obj->print_on(out);
789 #endif // PRODUCT
790 }
791
792 template <class T>
793 void do_oop_work(T* p) {
794 assert(_containing_obj != NULL, "Precondition");
795 assert(!_g1h->is_obj_dead_cond(_containing_obj, _vo),
796 "Precondition");
797 T heap_oop = oopDesc::load_heap_oop(p);
798 if (!oopDesc::is_null(heap_oop)) {
799 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
800 bool failed = false;
801 if (!_g1h->is_in_closed_subset(obj) || _g1h->is_obj_dead_cond(obj, _vo)) {
802 MutexLockerEx x(ParGCRareEvent_lock,
803 Mutex::_no_safepoint_check_flag);
804
805 if (!_failures) {
806 gclog_or_tty->cr();
807 gclog_or_tty->print_cr("----------");
808 }
809 if (!_g1h->is_in_closed_subset(obj)) {
810 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
811 gclog_or_tty->print_cr("Field "PTR_FORMAT
812 " of live obj "PTR_FORMAT" in region "
813 "["PTR_FORMAT", "PTR_FORMAT")",
814 p, (void*) _containing_obj,
815 from->bottom(), from->end());
816 print_object(gclog_or_tty, _containing_obj);
817 gclog_or_tty->print_cr("points to obj "PTR_FORMAT" not in the heap",
818 (void*) obj);
819 } else {
820 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
821 HeapRegion* to = _g1h->heap_region_containing((HeapWord*)obj);
822 gclog_or_tty->print_cr("Field "PTR_FORMAT
823 " of live obj "PTR_FORMAT" in region "
824 "["PTR_FORMAT", "PTR_FORMAT")",
825 p, (void*) _containing_obj,
826 from->bottom(), from->end());
827 print_object(gclog_or_tty, _containing_obj);
828 gclog_or_tty->print_cr("points to dead obj "PTR_FORMAT" in region "
829 "["PTR_FORMAT", "PTR_FORMAT")",
830 (void*) obj, to->bottom(), to->end());
831 print_object(gclog_or_tty, obj);
832 }
833 gclog_or_tty->print_cr("----------");
834 gclog_or_tty->flush();
835 _failures = true;
836 failed = true;
837 _n_failures++;
838 }
839
840 if (!_g1h->full_collection() || G1VerifyRSetsDuringFullGC) {
841 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
842 HeapRegion* to = _g1h->heap_region_containing(obj);
843 if (from != NULL && to != NULL &&
844 from != to &&
845 !to->isHumongous()) {
846 jbyte cv_obj = *_bs->byte_for_const(_containing_obj);
847 jbyte cv_field = *_bs->byte_for_const(p);
848 const jbyte dirty = CardTableModRefBS::dirty_card_val();
849
850 bool is_bad = !(from->is_young()
851 || to->rem_set()->contains_reference(p)
852 || !G1HRRSFlushLogBuffersOnVerify && // buffers were not flushed
853 (_containing_obj->is_objArray() ?
854 cv_field == dirty
855 : cv_obj == dirty || cv_field == dirty));
856 if (is_bad) {
857 MutexLockerEx x(ParGCRareEvent_lock,
858 Mutex::_no_safepoint_check_flag);
859
860 if (!_failures) {
861 gclog_or_tty->cr();
862 gclog_or_tty->print_cr("----------");
863 }
864 gclog_or_tty->print_cr("Missing rem set entry:");
865 gclog_or_tty->print_cr("Field "PTR_FORMAT" "
866 "of obj "PTR_FORMAT", "
867 "in region "HR_FORMAT,
868 p, (void*) _containing_obj,
869 HR_FORMAT_PARAMS(from));
870 _containing_obj->print_on(gclog_or_tty);
871 gclog_or_tty->print_cr("points to obj "PTR_FORMAT" "
872 "in region "HR_FORMAT,
873 (void*) obj,
874 HR_FORMAT_PARAMS(to));
875 obj->print_on(gclog_or_tty);
876 gclog_or_tty->print_cr("Obj head CTE = %d, field CTE = %d.",
877 cv_obj, cv_field);
878 gclog_or_tty->print_cr("----------");
879 gclog_or_tty->flush();
880 _failures = true;
881 if (!failed) _n_failures++;
882 }
883 }
884 }
885 }
886 }
887 };
888
889 // This really ought to be commoned up into OffsetTableContigSpace somehow.
890 // We would need a mechanism to make that code skip dead objects.
891
892 void HeapRegion::verify(VerifyOption vo,
893 bool* failures) const {
894 G1CollectedHeap* g1 = G1CollectedHeap::heap();
895 *failures = false;
896 HeapWord* p = bottom();
897 HeapWord* prev_p = NULL;
898 VerifyLiveClosure vl_cl(g1, vo);
899 bool is_humongous = isHumongous();
900 bool do_bot_verify = !is_young();
901 size_t object_num = 0;
902 while (p < top()) {
903 oop obj = oop(p);
904 size_t obj_size = block_size(p);
905 object_num += 1;
906
907 if (is_humongous != g1->isHumongous(obj_size)) {
908 gclog_or_tty->print_cr("obj "PTR_FORMAT" is of %shumongous size ("
909 SIZE_FORMAT" words) in a %shumongous region",
910 p, g1->isHumongous(obj_size) ? "" : "non-",
911 obj_size, is_humongous ? "" : "non-");
912 *failures = true;
913 return;
914 }
915
916 // If it returns false, verify_for_object() will output the
917 // appropriate messasge.
918 if (do_bot_verify && !_offsets.verify_for_object(p, obj_size)) {
919 *failures = true;
920 return;
921 }
922
923 if (!g1->is_obj_dead_cond(obj, this, vo)) {
924 if (obj->is_oop()) {
925 Klass* klass = obj->klass();
926 if (!klass->is_metaspace_object()) {
927 gclog_or_tty->print_cr("klass "PTR_FORMAT" of object "PTR_FORMAT" "
928 "not metadata", klass, (void *)obj);
929 *failures = true;
930 return;
931 } else if (!klass->is_klass()) {
932 gclog_or_tty->print_cr("klass "PTR_FORMAT" of object "PTR_FORMAT" "
933 "not a klass", klass, (void *)obj);
934 *failures = true;
935 return;
936 } else {
937 vl_cl.set_containing_obj(obj);
938 obj->oop_iterate_no_header(&vl_cl);
939 if (vl_cl.failures()) {
940 *failures = true;
941 }
942 if (G1MaxVerifyFailures >= 0 &&
943 vl_cl.n_failures() >= G1MaxVerifyFailures) {
944 return;
945 }
946 }
947 } else {
948 gclog_or_tty->print_cr(PTR_FORMAT" no an oop", (void *)obj);
949 *failures = true;
950 return;
951 }
952 }
953 prev_p = p;
954 p += obj_size;
955 }
956
957 if (p != top()) {
958 gclog_or_tty->print_cr("end of last object "PTR_FORMAT" "
959 "does not match top "PTR_FORMAT, p, top());
960 *failures = true;
961 return;
962 }
963
964 HeapWord* the_end = end();
965 assert(p == top(), "it should still hold");
966 // Do some extra BOT consistency checking for addresses in the
967 // range [top, end). BOT look-ups in this range should yield
968 // top. No point in doing that if top == end (there's nothing there).
969 if (p < the_end) {
970 // Look up top
971 HeapWord* addr_1 = p;
972 HeapWord* b_start_1 = _offsets.block_start_const(addr_1);
973 if (b_start_1 != p) {
974 gclog_or_tty->print_cr("BOT look up for top: "PTR_FORMAT" "
975 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
976 addr_1, b_start_1, p);
977 *failures = true;
978 return;
979 }
980
981 // Look up top + 1
982 HeapWord* addr_2 = p + 1;
983 if (addr_2 < the_end) {
984 HeapWord* b_start_2 = _offsets.block_start_const(addr_2);
985 if (b_start_2 != p) {
986 gclog_or_tty->print_cr("BOT look up for top + 1: "PTR_FORMAT" "
987 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
988 addr_2, b_start_2, p);
989 *failures = true;
990 return;
991 }
992 }
993
994 // Look up an address between top and end
995 size_t diff = pointer_delta(the_end, p) / 2;
996 HeapWord* addr_3 = p + diff;
997 if (addr_3 < the_end) {
998 HeapWord* b_start_3 = _offsets.block_start_const(addr_3);
999 if (b_start_3 != p) {
1000 gclog_or_tty->print_cr("BOT look up for top + diff: "PTR_FORMAT" "
1001 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
1002 addr_3, b_start_3, p);
1003 *failures = true;
1004 return;
1005 }
1006 }
1007
1008 // Look up end - 1
1009 HeapWord* addr_4 = the_end - 1;
1010 HeapWord* b_start_4 = _offsets.block_start_const(addr_4);
1011 if (b_start_4 != p) {
1012 gclog_or_tty->print_cr("BOT look up for end - 1: "PTR_FORMAT" "
1013 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
1014 addr_4, b_start_4, p);
1015 *failures = true;
1016 return;
1017 }
1018 }
1019
1020 if (is_humongous && object_num > 1) {
1021 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] is humongous "
1022 "but has "SIZE_FORMAT", objects",
1023 bottom(), end(), object_num);
1024 *failures = true;
1025 return;
1026 }
1027
1028 verify_strong_code_roots(vo, failures);
1029 }
1030
1031 void HeapRegion::verify() const {
1032 bool dummy = false;
1033 verify(VerifyOption_G1UsePrevMarking, /* failures */ &dummy);
1034 }
1035
1036 // G1OffsetTableContigSpace code; copied from space.cpp. Hope this can go
1037 // away eventually.
1038
1039 void G1OffsetTableContigSpace::clear(bool mangle_space) {
1040 set_top(bottom());
1041 set_saved_mark_word(bottom());
1042 CompactibleSpace::clear(mangle_space);
1043 _offsets.zero_bottom_entry();
1044 _offsets.initialize_threshold();
1045 }
1046
1047 void G1OffsetTableContigSpace::set_bottom(HeapWord* new_bottom) {
1048 Space::set_bottom(new_bottom);
1049 _offsets.set_bottom(new_bottom);
1050 }
1051
1052 void G1OffsetTableContigSpace::set_end(HeapWord* new_end) {
1053 Space::set_end(new_end);
1054 _offsets.resize(new_end - bottom());
1055 }
1056
1057 void G1OffsetTableContigSpace::print() const {
1058 print_short();
1059 gclog_or_tty->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", "
1060 INTPTR_FORMAT ", " INTPTR_FORMAT ")",
1061 bottom(), top(), _offsets.threshold(), end());
1062 }
1063
1064 HeapWord* G1OffsetTableContigSpace::initialize_threshold() {
1065 return _offsets.initialize_threshold();
1066 }
1067
1068 HeapWord* G1OffsetTableContigSpace::cross_threshold(HeapWord* start,
1069 HeapWord* end) {
1070 _offsets.alloc_block(start, end);
1071 return _offsets.threshold();
1072 }
1073
1074 HeapWord* G1OffsetTableContigSpace::saved_mark_word() const {
1075 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1076 assert( _gc_time_stamp <= g1h->get_gc_time_stamp(), "invariant" );
1077 if (_gc_time_stamp < g1h->get_gc_time_stamp())
1078 return top();
1079 else
1080 return Space::saved_mark_word();
1081 }
1082
1083 void G1OffsetTableContigSpace::record_top_and_timestamp() {
1084 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1085 unsigned curr_gc_time_stamp = g1h->get_gc_time_stamp();
1086
1087 if (_gc_time_stamp < curr_gc_time_stamp) {
1088 // The order of these is important, as another thread might be
1089 // about to start scanning this region. If it does so after
1090 // set_saved_mark and before _gc_time_stamp = ..., then the latter
1091 // will be false, and it will pick up top() as the high water mark
1092 // of region. If it does so after _gc_time_stamp = ..., then it
1093 // will pick up the right saved_mark_word() as the high water mark
1094 // of the region. Either way, the behavior will be correct.
1095 Space::set_saved_mark_word(top());
1096 OrderAccess::storestore();
1097 _gc_time_stamp = curr_gc_time_stamp;
1098 // No need to do another barrier to flush the writes above. If
1099 // this is called in parallel with other threads trying to
1100 // allocate into the region, the caller should call this while
1101 // holding a lock and when the lock is released the writes will be
1102 // flushed.
1103 }
1104 }
1105
1106 void G1OffsetTableContigSpace::safe_object_iterate(ObjectClosure* blk) {
1107 object_iterate(blk);
1108 }
1109
1110 void G1OffsetTableContigSpace::object_iterate(ObjectClosure* blk) {
1111 HeapWord* p = bottom();
1112 while (p < top()) {
1113 if (block_is_obj(p)) {
1114 blk->do_object(oop(p));
1115 }
1116 p += block_size(p);
1117 }
1118 }
1119
1120 #define block_is_always_obj(q) true
1121 void G1OffsetTableContigSpace::prepare_for_compaction(CompactPoint* cp) {
1122 SCAN_AND_FORWARD(cp, top, block_is_always_obj, block_size);
1123 }
1124 #undef block_is_always_obj
1125
1126 G1OffsetTableContigSpace::
1127 G1OffsetTableContigSpace(G1BlockOffsetSharedArray* sharedOffsetArray,
1128 MemRegion mr) :
1129 _offsets(sharedOffsetArray, mr),
1130 _par_alloc_lock(Mutex::leaf, "OffsetTableContigSpace par alloc lock", true),
1131 _gc_time_stamp(0)
1132 {
1133 _offsets.set_space(this);
1134 // false ==> we'll do the clearing if there's clearing to be done.
1135 CompactibleSpace::initialize(mr, false, SpaceDecorator::Mangle);
1136 _top = bottom();
1137 _offsets.zero_bottom_entry();
1138 _offsets.initialize_threshold();
1139 }