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/g1Log.hpp"
30 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
31 #include "gc_implementation/g1/heapRegion.inline.hpp"
32 #include "gc_implementation/g1/heapRegionRemSet.hpp"
33 #include "gc_implementation/g1/heapRegionSeq.inline.hpp"
34 #include "memory/genOopClosures.inline.hpp"
35 #include "memory/iterator.hpp"
36 #include "oops/oop.inline.hpp"
37
38 int HeapRegion::LogOfHRGrainBytes = 0;
39 int HeapRegion::LogOfHRGrainWords = 0;
40 size_t HeapRegion::GrainBytes = 0;
41 size_t HeapRegion::GrainWords = 0;
42 size_t HeapRegion::CardsPerRegion = 0;
43
44 HeapRegionDCTOC::HeapRegionDCTOC(G1CollectedHeap* g1,
45 HeapRegion* hr, ExtendedOopClosure* cl,
46 CardTableModRefBS::PrecisionStyle precision,
47 FilterKind fk) :
48 ContiguousSpaceDCTOC(hr, cl, precision, NULL),
49 _hr(hr), _fk(fk), _g1(g1) { }
50
51 FilterOutOfRegionClosure::FilterOutOfRegionClosure(HeapRegion* r,
52 OopClosure* oc) :
53 _r_bottom(r->bottom()), _r_end(r->end()), _oc(oc) { }
54
55 template<class ClosureType>
56 HeapWord* walk_mem_region_loop(ClosureType* cl, G1CollectedHeap* g1h,
57 HeapRegion* hr,
58 HeapWord* cur, HeapWord* top) {
59 oop cur_oop = oop(cur);
60 int oop_size = cur_oop->size();
61 HeapWord* next_obj = cur + oop_size;
62 while (next_obj < top) {
63 // Keep filtering the remembered set.
64 if (!g1h->is_obj_dead(cur_oop, hr)) {
65 // Bottom lies entirely below top, so we can call the
66 // non-memRegion version of oop_iterate below.
67 cur_oop->oop_iterate(cl);
68 }
69 cur = next_obj;
70 cur_oop = oop(cur);
71 oop_size = cur_oop->size();
72 next_obj = cur + oop_size;
73 }
74 return cur;
75 }
76
77 void HeapRegionDCTOC::walk_mem_region_with_cl(MemRegion mr,
78 HeapWord* bottom,
79 HeapWord* top,
80 ExtendedOopClosure* cl) {
81 G1CollectedHeap* g1h = _g1;
82 int oop_size;
83 ExtendedOopClosure* cl2 = NULL;
84
85 FilterIntoCSClosure intoCSFilt(this, g1h, cl);
86 FilterOutOfRegionClosure outOfRegionFilt(_hr, cl);
87
88 switch (_fk) {
89 case NoFilterKind: cl2 = cl; break;
90 case IntoCSFilterKind: cl2 = &intoCSFilt; break;
91 case OutOfRegionFilterKind: cl2 = &outOfRegionFilt; break;
92 default: ShouldNotReachHere();
93 }
94
95 // Start filtering what we add to the remembered set. If the object is
96 // not considered dead, either because it is marked (in the mark bitmap)
97 // or it was allocated after marking finished, then we add it. Otherwise
98 // we can safely ignore the object.
99 if (!g1h->is_obj_dead(oop(bottom), _hr)) {
100 oop_size = oop(bottom)->oop_iterate(cl2, mr);
101 } else {
102 oop_size = oop(bottom)->size();
103 }
104
105 bottom += oop_size;
106
107 if (bottom < top) {
108 // We replicate the loop below for several kinds of possible filters.
109 switch (_fk) {
110 case NoFilterKind:
111 bottom = walk_mem_region_loop(cl, g1h, _hr, bottom, top);
112 break;
113
114 case IntoCSFilterKind: {
115 FilterIntoCSClosure filt(this, g1h, cl);
116 bottom = walk_mem_region_loop(&filt, g1h, _hr, bottom, top);
117 break;
118 }
119
120 case OutOfRegionFilterKind: {
121 FilterOutOfRegionClosure filt(_hr, cl);
122 bottom = walk_mem_region_loop(&filt, g1h, _hr, bottom, top);
123 break;
124 }
125
126 default:
127 ShouldNotReachHere();
128 }
129
130 // Last object. Need to do dead-obj filtering here too.
131 if (!g1h->is_obj_dead(oop(bottom), _hr)) {
132 oop(bottom)->oop_iterate(cl2, mr);
133 }
134 }
135 }
136
137 // Minimum region size; we won't go lower than that.
138 // We might want to decrease this in the future, to deal with small
139 // heaps a bit more efficiently.
140 #define MIN_REGION_SIZE ( 1024 * 1024 )
141
142 // Maximum region size; we don't go higher than that. There's a good
143 // reason for having an upper bound. We don't want regions to get too
144 // large, otherwise cleanup's effectiveness would decrease as there
145 // will be fewer opportunities to find totally empty regions after
146 // marking.
147 #define MAX_REGION_SIZE ( 32 * 1024 * 1024 )
148
149 // The automatic region size calculation will try to have around this
150 // many regions in the heap (based on the min heap size).
151 #define TARGET_REGION_NUMBER 2048
152
153 void HeapRegion::setup_heap_region_size(size_t initial_heap_size, size_t max_heap_size) {
154 uintx region_size = G1HeapRegionSize;
155 if (FLAG_IS_DEFAULT(G1HeapRegionSize)) {
156 size_t average_heap_size = (initial_heap_size + max_heap_size) / 2;
157 region_size = MAX2(average_heap_size / TARGET_REGION_NUMBER,
158 (uintx) MIN_REGION_SIZE);
159 }
160
161 int region_size_log = log2_long((jlong) region_size);
162 // Recalculate the region size to make sure it's a power of
163 // 2. This means that region_size is the largest power of 2 that's
164 // <= what we've calculated so far.
165 region_size = ((uintx)1 << region_size_log);
166
167 // Now make sure that we don't go over or under our limits.
168 if (region_size < MIN_REGION_SIZE) {
169 region_size = MIN_REGION_SIZE;
170 } else if (region_size > MAX_REGION_SIZE) {
171 region_size = MAX_REGION_SIZE;
172 }
173
174 if (region_size != G1HeapRegionSize) {
175 // Update the flag to make sure that PrintFlagsFinal logs the correct value
176 FLAG_SET_ERGO(uintx, G1HeapRegionSize, region_size);
177 }
178
179 // And recalculate the log.
180 region_size_log = log2_long((jlong) region_size);
181
182 if (G1Log::fine()) {
183 gclog_or_tty->print_cr("G1 Heap region size: " SIZE_FORMAT "M", region_size / M);
184 }
185
186 // Now, set up the globals.
187 guarantee(LogOfHRGrainBytes == 0, "we should only set it once");
188 LogOfHRGrainBytes = region_size_log;
189
190 guarantee(LogOfHRGrainWords == 0, "we should only set it once");
191 LogOfHRGrainWords = LogOfHRGrainBytes - LogHeapWordSize;
192
193 guarantee(GrainBytes == 0, "we should only set it once");
194 // The cast to int is safe, given that we've bounded region_size by
195 // MIN_REGION_SIZE and MAX_REGION_SIZE.
196 GrainBytes = (size_t)region_size;
197
198 guarantee(GrainWords == 0, "we should only set it once");
199 GrainWords = GrainBytes >> LogHeapWordSize;
200 guarantee((size_t) 1 << LogOfHRGrainWords == GrainWords, "sanity");
201
202 guarantee(CardsPerRegion == 0, "we should only set it once");
203 CardsPerRegion = GrainBytes >> CardTableModRefBS::card_shift;
204 }
205
206 void HeapRegion::reset_after_compaction() {
207 G1OffsetTableContigSpace::reset_after_compaction();
208 // After a compaction the mark bitmap is invalid, so we must
209 // treat all objects as being inside the unmarked area.
210 zero_marked_bytes();
211 init_top_at_mark_start();
212 }
213
214 void HeapRegion::hr_clear(bool par, bool clear_space) {
215 assert(_humongous_type == NotHumongous,
216 "we should have already filtered out humongous regions");
217 assert(_humongous_start_region == NULL,
218 "we should have already filtered out humongous regions");
219 assert(_end == _orig_end,
220 "we should have already filtered out humongous regions");
221
222 _in_collection_set = false;
223
224 set_young_index_in_cset(-1);
225 uninstall_surv_rate_group();
226 set_young_type(NotYoung);
227 reset_pre_dummy_top();
228
229 if (!par) {
230 // If this is parallel, this will be done later.
231 HeapRegionRemSet* hrrs = rem_set();
232 hrrs->clear();
233 _claimed = InitialClaimValue;
234 }
235 zero_marked_bytes();
236
237 _offsets.resize(HeapRegion::GrainWords);
238 init_top_at_mark_start();
239 if (clear_space) clear(SpaceDecorator::Mangle);
240 }
241
242 void HeapRegion::par_clear() {
243 assert(used() == 0, "the region should have been already cleared");
244 assert(capacity() == HeapRegion::GrainBytes, "should be back to normal");
245 HeapRegionRemSet* hrrs = rem_set();
246 hrrs->clear();
247 CardTableModRefBS* ct_bs =
248 (CardTableModRefBS*)G1CollectedHeap::heap()->barrier_set();
249 ct_bs->clear(MemRegion(bottom(), end()));
250 }
251
252 void HeapRegion::calc_gc_efficiency() {
253 // GC efficiency is the ratio of how much space would be
254 // reclaimed over how long we predict it would take to reclaim it.
255 G1CollectedHeap* g1h = G1CollectedHeap::heap();
256 G1CollectorPolicy* g1p = g1h->g1_policy();
257
258 // Retrieve a prediction of the elapsed time for this region for
259 // a mixed gc because the region will only be evacuated during a
260 // mixed gc.
261 double region_elapsed_time_ms =
262 g1p->predict_region_elapsed_time_ms(this, false /* for_young_gc */);
263 _gc_efficiency = (double) reclaimable_bytes() / region_elapsed_time_ms;
264 }
265
266 void HeapRegion::set_startsHumongous(HeapWord* new_top, HeapWord* new_end) {
267 assert(!isHumongous(), "sanity / pre-condition");
268 assert(end() == _orig_end,
269 "Should be normal before the humongous object allocation");
270 assert(top() == bottom(), "should be empty");
271 assert(bottom() <= new_top && new_top <= new_end, "pre-condition");
272
273 _humongous_type = StartsHumongous;
274 _humongous_start_region = this;
275
276 set_end(new_end);
277 _offsets.set_for_starts_humongous(new_top);
278 }
279
280 void HeapRegion::set_continuesHumongous(HeapRegion* first_hr) {
281 assert(!isHumongous(), "sanity / pre-condition");
282 assert(end() == _orig_end,
283 "Should be normal before the humongous object allocation");
284 assert(top() == bottom(), "should be empty");
285 assert(first_hr->startsHumongous(), "pre-condition");
286
287 _humongous_type = ContinuesHumongous;
288 _humongous_start_region = first_hr;
289 }
290
291 void HeapRegion::set_notHumongous() {
292 assert(isHumongous(), "pre-condition");
293
294 if (startsHumongous()) {
295 assert(top() <= end(), "pre-condition");
296 set_end(_orig_end);
297 if (top() > end()) {
298 // at least one "continues humongous" region after it
299 set_top(end());
300 }
301 } else {
302 // continues humongous
303 assert(end() == _orig_end, "sanity");
304 }
305
306 assert(capacity() == HeapRegion::GrainBytes, "pre-condition");
307 _humongous_type = NotHumongous;
308 _humongous_start_region = NULL;
309 }
310
311 bool HeapRegion::claimHeapRegion(jint claimValue) {
312 jint current = _claimed;
313 if (current != claimValue) {
314 jint res = Atomic::cmpxchg(claimValue, &_claimed, current);
315 if (res == current) {
316 return true;
317 }
318 }
319 return false;
320 }
321
322 HeapWord* HeapRegion::next_block_start_careful(HeapWord* addr) {
323 HeapWord* low = addr;
324 HeapWord* high = end();
325 while (low < high) {
326 size_t diff = pointer_delta(high, low);
327 // Must add one below to bias toward the high amount. Otherwise, if
328 // "high" were at the desired value, and "low" were one less, we
329 // would not converge on "high". This is not symmetric, because
330 // we set "high" to a block start, which might be the right one,
331 // which we don't do for "low".
332 HeapWord* middle = low + (diff+1)/2;
333 if (middle == high) return high;
334 HeapWord* mid_bs = block_start_careful(middle);
335 if (mid_bs < addr) {
336 low = middle;
337 } else {
338 high = mid_bs;
339 }
340 }
341 assert(low == high && low >= addr, "Didn't work.");
342 return low;
343 }
344
345 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
346 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
347 #endif // _MSC_VER
348
349
350 HeapRegion::HeapRegion(uint hrs_index,
351 G1BlockOffsetSharedArray* sharedOffsetArray,
352 MemRegion mr) :
353 G1OffsetTableContigSpace(sharedOffsetArray, mr),
354 _hrs_index(hrs_index),
355 _humongous_type(NotHumongous), _humongous_start_region(NULL),
356 _in_collection_set(false),
357 _next_in_special_set(NULL), _orig_end(NULL),
358 _claimed(InitialClaimValue), _evacuation_failed(false),
359 _prev_marked_bytes(0), _next_marked_bytes(0), _gc_efficiency(0.0),
360 _young_type(NotYoung), _next_young_region(NULL),
361 _next_dirty_cards_region(NULL), _next(NULL), _pending_removal(false),
362 #ifdef ASSERT
363 _containing_set(NULL),
364 #endif // ASSERT
365 _young_index_in_cset(-1), _surv_rate_group(NULL), _age_index(-1),
366 _rem_set(NULL), _recorded_rs_length(0), _predicted_elapsed_time_ms(0),
367 _predicted_bytes_to_copy(0)
368 {
369 _rem_set = new HeapRegionRemSet(sharedOffsetArray, this);
370 _orig_end = mr.end();
371 // Note that initialize() will set the start of the unmarked area of the
372 // region.
373 hr_clear(false /*par*/, false /*clear_space*/);
374 set_top(bottom());
375 set_saved_mark();
376
377 assert(HeapRegionRemSet::num_par_rem_sets() > 0, "Invariant.");
378 }
379
380 CompactibleSpace* HeapRegion::next_compaction_space() const {
381 // We're not using an iterator given that it will wrap around when
382 // it reaches the last region and this is not what we want here.
383 G1CollectedHeap* g1h = G1CollectedHeap::heap();
384 uint index = hrs_index() + 1;
385 while (index < g1h->n_regions()) {
386 HeapRegion* hr = g1h->region_at(index);
387 if (!hr->isHumongous()) {
388 return hr;
389 }
390 index += 1;
391 }
392 return NULL;
393 }
394
395 void HeapRegion::save_marks() {
396 set_saved_mark();
397 }
398
399 void HeapRegion::oops_in_mr_iterate(MemRegion mr, ExtendedOopClosure* cl) {
400 HeapWord* p = mr.start();
401 HeapWord* e = mr.end();
402 oop obj;
403 while (p < e) {
404 obj = oop(p);
405 p += obj->oop_iterate(cl);
406 }
407 assert(p == e, "bad memregion: doesn't end on obj boundary");
408 }
409
410 #define HeapRegion_OOP_SINCE_SAVE_MARKS_DEFN(OopClosureType, nv_suffix) \
411 void HeapRegion::oop_since_save_marks_iterate##nv_suffix(OopClosureType* cl) { \
412 ContiguousSpace::oop_since_save_marks_iterate##nv_suffix(cl); \
413 }
414 SPECIALIZED_SINCE_SAVE_MARKS_CLOSURES(HeapRegion_OOP_SINCE_SAVE_MARKS_DEFN)
415
416
417 void HeapRegion::oop_before_save_marks_iterate(ExtendedOopClosure* cl) {
418 oops_in_mr_iterate(MemRegion(bottom(), saved_mark_word()), cl);
419 }
420
421 void HeapRegion::note_self_forwarding_removal_start(bool during_initial_mark,
422 bool during_conc_mark) {
423 // We always recreate the prev marking info and we'll explicitly
424 // mark all objects we find to be self-forwarded on the prev
425 // bitmap. So all objects need to be below PTAMS.
426 _prev_top_at_mark_start = top();
427 _prev_marked_bytes = 0;
428
429 if (during_initial_mark) {
430 // During initial-mark, we'll also explicitly mark all objects
431 // we find to be self-forwarded on the next bitmap. So all
432 // objects need to be below NTAMS.
433 _next_top_at_mark_start = top();
434 _next_marked_bytes = 0;
435 } else if (during_conc_mark) {
436 // During concurrent mark, all objects in the CSet (including
437 // the ones we find to be self-forwarded) are implicitly live.
438 // So all objects need to be above NTAMS.
439 _next_top_at_mark_start = bottom();
440 _next_marked_bytes = 0;
441 }
442 }
443
444 void HeapRegion::note_self_forwarding_removal_end(bool during_initial_mark,
445 bool during_conc_mark,
446 size_t marked_bytes) {
447 assert(0 <= marked_bytes && marked_bytes <= used(),
448 err_msg("marked: "SIZE_FORMAT" used: "SIZE_FORMAT,
449 marked_bytes, used()));
450 _prev_marked_bytes = marked_bytes;
451 }
452
453 HeapWord*
454 HeapRegion::object_iterate_mem_careful(MemRegion mr,
455 ObjectClosure* cl) {
456 G1CollectedHeap* g1h = G1CollectedHeap::heap();
457 // We used to use "block_start_careful" here. But we're actually happy
458 // to update the BOT while we do this...
459 HeapWord* cur = block_start(mr.start());
460 mr = mr.intersection(used_region());
461 if (mr.is_empty()) return NULL;
462 // Otherwise, find the obj that extends onto mr.start().
463
464 assert(cur <= mr.start()
465 && (oop(cur)->klass_or_null() == NULL ||
466 cur + oop(cur)->size() > mr.start()),
467 "postcondition of block_start");
468 oop obj;
469 while (cur < mr.end()) {
470 obj = oop(cur);
471 if (obj->klass_or_null() == NULL) {
472 // Ran into an unparseable point.
473 return cur;
474 } else if (!g1h->is_obj_dead(obj)) {
475 cl->do_object(obj);
476 }
477 if (cl->abort()) return cur;
478 // The check above must occur before the operation below, since an
479 // abort might invalidate the "size" operation.
480 cur += obj->size();
481 }
482 return NULL;
483 }
484
485 HeapWord*
486 HeapRegion::
487 oops_on_card_seq_iterate_careful(MemRegion mr,
488 FilterOutOfRegionClosure* cl,
489 bool filter_young,
490 jbyte* card_ptr) {
491 // Currently, we should only have to clean the card if filter_young
492 // is true and vice versa.
493 if (filter_young) {
494 assert(card_ptr != NULL, "pre-condition");
495 } else {
496 assert(card_ptr == NULL, "pre-condition");
497 }
498 G1CollectedHeap* g1h = G1CollectedHeap::heap();
499
500 // If we're within a stop-world GC, then we might look at a card in a
501 // GC alloc region that extends onto a GC LAB, which may not be
502 // parseable. Stop such at the "saved_mark" of the region.
503 if (g1h->is_gc_active()) {
504 mr = mr.intersection(used_region_at_save_marks());
505 } else {
506 mr = mr.intersection(used_region());
507 }
508 if (mr.is_empty()) return NULL;
509 // Otherwise, find the obj that extends onto mr.start().
510
511 // The intersection of the incoming mr (for the card) and the
512 // allocated part of the region is non-empty. This implies that
513 // we have actually allocated into this region. The code in
514 // G1CollectedHeap.cpp that allocates a new region sets the
515 // is_young tag on the region before allocating. Thus we
516 // safely know if this region is young.
517 if (is_young() && filter_young) {
518 return NULL;
519 }
520
521 assert(!is_young(), "check value of filter_young");
522
523 // We can only clean the card here, after we make the decision that
524 // the card is not young. And we only clean the card if we have been
525 // asked to (i.e., card_ptr != NULL).
526 if (card_ptr != NULL) {
527 *card_ptr = CardTableModRefBS::clean_card_val();
528 // We must complete this write before we do any of the reads below.
529 OrderAccess::storeload();
530 }
531
532 // Cache the boundaries of the memory region in some const locals
533 HeapWord* const start = mr.start();
534 HeapWord* const end = mr.end();
535
536 // We used to use "block_start_careful" here. But we're actually happy
537 // to update the BOT while we do this...
538 HeapWord* cur = block_start(start);
539 assert(cur <= start, "Postcondition");
540
541 oop obj;
542
543 HeapWord* next = cur;
544 while (next <= start) {
545 cur = next;
546 obj = oop(cur);
547 if (obj->klass_or_null() == NULL) {
548 // Ran into an unparseable point.
549 return cur;
550 }
551 // Otherwise...
552 next = (cur + obj->size());
553 }
554
555 // If we finish the above loop...We have a parseable object that
556 // begins on or before the start of the memory region, and ends
557 // inside or spans the entire region.
558
559 assert(obj == oop(cur), "sanity");
560 assert(cur <= start &&
561 obj->klass_or_null() != NULL &&
562 (cur + obj->size()) > start,
563 "Loop postcondition");
564
565 if (!g1h->is_obj_dead(obj)) {
566 obj->oop_iterate(cl, mr);
567 }
568
569 while (cur < end) {
570 obj = oop(cur);
571 if (obj->klass_or_null() == NULL) {
572 // Ran into an unparseable point.
573 return cur;
574 };
575
576 // Otherwise:
577 next = (cur + obj->size());
578
579 if (!g1h->is_obj_dead(obj)) {
580 if (next < end || !obj->is_objArray()) {
581 // This object either does not span the MemRegion
582 // boundary, or if it does it's not an array.
583 // Apply closure to whole object.
584 obj->oop_iterate(cl);
585 } else {
586 // This obj is an array that spans the boundary.
587 // Stop at the boundary.
588 obj->oop_iterate(cl, mr);
589 }
590 }
591 cur = next;
592 }
593 return NULL;
594 }
595
596 // Code roots support
597
598 void HeapRegion::add_strong_code_root(nmethod* nm) {
599 HeapRegionRemSet* hrrs = rem_set();
600 hrrs->add_strong_code_root(nm);
601 }
602
603 void HeapRegion::remove_strong_code_root(nmethod* nm) {
604 HeapRegionRemSet* hrrs = rem_set();
605 hrrs->remove_strong_code_root(nm);
606 }
607
608 void HeapRegion::migrate_strong_code_roots() {
609 assert(in_collection_set(), "only collection set regions");
610 assert(!isHumongous(), "not humongous regions");
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 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 int 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 "INT32_FORMAT" code root entries",
725 bottom(), end(), strong_code_roots_length);
726 *failures = true;
727 }
728 return;
729 }
730
731 // An H-region should have an empty strong code root list
732 if (isHumongous()) {
733 if (strong_code_roots_length > 0) {
734 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] is humongous "
735 "but has "INT32_FORMAT" code root entries",
736 bottom(), end(), strong_code_roots_length);
737 *failures = true;
738 }
739 return;
740 }
741
742 VerifyStrongCodeRootCodeBlobClosure cb_cl(this);
743 strong_code_roots_do(&cb_cl);
744
745 if (cb_cl.failures()) {
746 *failures = true;
747 }
748 }
749
750 void HeapRegion::print() const { print_on(gclog_or_tty); }
751 void HeapRegion::print_on(outputStream* st) const {
752 if (isHumongous()) {
753 if (startsHumongous())
754 st->print(" HS");
755 else
756 st->print(" HC");
757 } else {
758 st->print(" ");
759 }
760 if (in_collection_set())
761 st->print(" CS");
762 else
763 st->print(" ");
764 if (is_young())
765 st->print(is_survivor() ? " SU" : " Y ");
766 else
767 st->print(" ");
768 if (is_empty())
769 st->print(" F");
770 else
771 st->print(" ");
772 st->print(" TS %5d", _gc_time_stamp);
773 st->print(" PTAMS "PTR_FORMAT" NTAMS "PTR_FORMAT,
774 prev_top_at_mark_start(), next_top_at_mark_start());
775 G1OffsetTableContigSpace::print_on(st);
776 }
777
778 class VerifyLiveClosure: public OopClosure {
779 private:
780 G1CollectedHeap* _g1h;
781 CardTableModRefBS* _bs;
782 oop _containing_obj;
783 bool _failures;
784 int _n_failures;
785 VerifyOption _vo;
786 public:
787 // _vo == UsePrevMarking -> use "prev" marking information,
788 // _vo == UseNextMarking -> use "next" marking information,
789 // _vo == UseMarkWord -> use mark word from object header.
790 VerifyLiveClosure(G1CollectedHeap* g1h, VerifyOption vo) :
791 _g1h(g1h), _bs(NULL), _containing_obj(NULL),
792 _failures(false), _n_failures(0), _vo(vo)
793 {
794 BarrierSet* bs = _g1h->barrier_set();
795 if (bs->is_a(BarrierSet::CardTableModRef))
796 _bs = (CardTableModRefBS*)bs;
797 }
798
799 void set_containing_obj(oop obj) {
800 _containing_obj = obj;
801 }
802
803 bool failures() { return _failures; }
804 int n_failures() { return _n_failures; }
805
806 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
807 virtual void do_oop( oop* p) { do_oop_work(p); }
808
809 void print_object(outputStream* out, oop obj) {
810 #ifdef PRODUCT
811 Klass* k = obj->klass();
812 const char* class_name = InstanceKlass::cast(k)->external_name();
813 out->print_cr("class name %s", class_name);
814 #else // PRODUCT
815 obj->print_on(out);
816 #endif // PRODUCT
817 }
818
819 template <class T>
820 void do_oop_work(T* p) {
821 assert(_containing_obj != NULL, "Precondition");
822 assert(!_g1h->is_obj_dead_cond(_containing_obj, _vo),
823 "Precondition");
824 T heap_oop = oopDesc::load_heap_oop(p);
825 if (!oopDesc::is_null(heap_oop)) {
826 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
827 bool failed = false;
828 if (!_g1h->is_in_closed_subset(obj) || _g1h->is_obj_dead_cond(obj, _vo)) {
829 MutexLockerEx x(ParGCRareEvent_lock,
830 Mutex::_no_safepoint_check_flag);
831
832 if (!_failures) {
833 gclog_or_tty->print_cr("");
834 gclog_or_tty->print_cr("----------");
835 }
836 if (!_g1h->is_in_closed_subset(obj)) {
837 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
838 gclog_or_tty->print_cr("Field "PTR_FORMAT
839 " of live obj "PTR_FORMAT" in region "
840 "["PTR_FORMAT", "PTR_FORMAT")",
841 p, (void*) _containing_obj,
842 from->bottom(), from->end());
843 print_object(gclog_or_tty, _containing_obj);
844 gclog_or_tty->print_cr("points to obj "PTR_FORMAT" not in the heap",
845 (void*) obj);
846 } else {
847 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
848 HeapRegion* to = _g1h->heap_region_containing((HeapWord*)obj);
849 gclog_or_tty->print_cr("Field "PTR_FORMAT
850 " of live obj "PTR_FORMAT" in region "
851 "["PTR_FORMAT", "PTR_FORMAT")",
852 p, (void*) _containing_obj,
853 from->bottom(), from->end());
854 print_object(gclog_or_tty, _containing_obj);
855 gclog_or_tty->print_cr("points to dead obj "PTR_FORMAT" in region "
856 "["PTR_FORMAT", "PTR_FORMAT")",
857 (void*) obj, to->bottom(), to->end());
858 print_object(gclog_or_tty, obj);
859 }
860 gclog_or_tty->print_cr("----------");
861 gclog_or_tty->flush();
862 _failures = true;
863 failed = true;
864 _n_failures++;
865 }
866
867 if (!_g1h->full_collection() || G1VerifyRSetsDuringFullGC) {
868 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
869 HeapRegion* to = _g1h->heap_region_containing(obj);
870 if (from != NULL && to != NULL &&
871 from != to &&
872 !to->isHumongous()) {
873 jbyte cv_obj = *_bs->byte_for_const(_containing_obj);
874 jbyte cv_field = *_bs->byte_for_const(p);
875 const jbyte dirty = CardTableModRefBS::dirty_card_val();
876
877 bool is_bad = !(from->is_young()
878 || to->rem_set()->contains_reference(p)
879 || !G1HRRSFlushLogBuffersOnVerify && // buffers were not flushed
880 (_containing_obj->is_objArray() ?
881 cv_field == dirty
882 : cv_obj == dirty || cv_field == dirty));
883 if (is_bad) {
884 MutexLockerEx x(ParGCRareEvent_lock,
885 Mutex::_no_safepoint_check_flag);
886
887 if (!_failures) {
888 gclog_or_tty->print_cr("");
889 gclog_or_tty->print_cr("----------");
890 }
891 gclog_or_tty->print_cr("Missing rem set entry:");
892 gclog_or_tty->print_cr("Field "PTR_FORMAT" "
893 "of obj "PTR_FORMAT", "
894 "in region "HR_FORMAT,
895 p, (void*) _containing_obj,
896 HR_FORMAT_PARAMS(from));
897 _containing_obj->print_on(gclog_or_tty);
898 gclog_or_tty->print_cr("points to obj "PTR_FORMAT" "
899 "in region "HR_FORMAT,
900 (void*) obj,
901 HR_FORMAT_PARAMS(to));
902 obj->print_on(gclog_or_tty);
903 gclog_or_tty->print_cr("Obj head CTE = %d, field CTE = %d.",
904 cv_obj, cv_field);
905 gclog_or_tty->print_cr("----------");
906 gclog_or_tty->flush();
907 _failures = true;
908 if (!failed) _n_failures++;
909 }
910 }
911 }
912 }
913 }
914 };
915
916 // This really ought to be commoned up into OffsetTableContigSpace somehow.
917 // We would need a mechanism to make that code skip dead objects.
918
919 void HeapRegion::verify(VerifyOption vo,
920 bool* failures) const {
921 G1CollectedHeap* g1 = G1CollectedHeap::heap();
922 *failures = false;
923 HeapWord* p = bottom();
924 HeapWord* prev_p = NULL;
925 VerifyLiveClosure vl_cl(g1, vo);
926 bool is_humongous = isHumongous();
927 bool do_bot_verify = !is_young();
928 size_t object_num = 0;
929 while (p < top()) {
930 oop obj = oop(p);
931 size_t obj_size = obj->size();
932 object_num += 1;
933
934 if (is_humongous != g1->isHumongous(obj_size)) {
935 gclog_or_tty->print_cr("obj "PTR_FORMAT" is of %shumongous size ("
936 SIZE_FORMAT" words) in a %shumongous region",
937 p, g1->isHumongous(obj_size) ? "" : "non-",
938 obj_size, is_humongous ? "" : "non-");
939 *failures = true;
940 return;
941 }
942
943 // If it returns false, verify_for_object() will output the
944 // appropriate messasge.
945 if (do_bot_verify && !_offsets.verify_for_object(p, obj_size)) {
946 *failures = true;
947 return;
948 }
949
950 if (!g1->is_obj_dead_cond(obj, this, vo)) {
951 if (obj->is_oop()) {
952 Klass* klass = obj->klass();
953 if (!klass->is_metaspace_object()) {
954 gclog_or_tty->print_cr("klass "PTR_FORMAT" of object "PTR_FORMAT" "
955 "not metadata", klass, obj);
956 *failures = true;
957 return;
958 } else if (!klass->is_klass()) {
959 gclog_or_tty->print_cr("klass "PTR_FORMAT" of object "PTR_FORMAT" "
960 "not a klass", klass, obj);
961 *failures = true;
962 return;
963 } else {
964 vl_cl.set_containing_obj(obj);
965 obj->oop_iterate_no_header(&vl_cl);
966 if (vl_cl.failures()) {
967 *failures = true;
968 }
969 if (G1MaxVerifyFailures >= 0 &&
970 vl_cl.n_failures() >= G1MaxVerifyFailures) {
971 return;
972 }
973 }
974 } else {
975 gclog_or_tty->print_cr(PTR_FORMAT" no an oop", obj);
976 *failures = true;
977 return;
978 }
979 }
980 prev_p = p;
981 p += obj_size;
982 }
983
984 if (p != top()) {
985 gclog_or_tty->print_cr("end of last object "PTR_FORMAT" "
986 "does not match top "PTR_FORMAT, p, top());
987 *failures = true;
988 return;
989 }
990
991 HeapWord* the_end = end();
992 assert(p == top(), "it should still hold");
993 // Do some extra BOT consistency checking for addresses in the
994 // range [top, end). BOT look-ups in this range should yield
995 // top. No point in doing that if top == end (there's nothing there).
996 if (p < the_end) {
997 // Look up top
998 HeapWord* addr_1 = p;
999 HeapWord* b_start_1 = _offsets.block_start_const(addr_1);
1000 if (b_start_1 != p) {
1001 gclog_or_tty->print_cr("BOT look up for top: "PTR_FORMAT" "
1002 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
1003 addr_1, b_start_1, p);
1004 *failures = true;
1005 return;
1006 }
1007
1008 // Look up top + 1
1009 HeapWord* addr_2 = p + 1;
1010 if (addr_2 < the_end) {
1011 HeapWord* b_start_2 = _offsets.block_start_const(addr_2);
1012 if (b_start_2 != p) {
1013 gclog_or_tty->print_cr("BOT look up for top + 1: "PTR_FORMAT" "
1014 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
1015 addr_2, b_start_2, p);
1016 *failures = true;
1017 return;
1018 }
1019 }
1020
1021 // Look up an address between top and end
1022 size_t diff = pointer_delta(the_end, p) / 2;
1023 HeapWord* addr_3 = p + diff;
1024 if (addr_3 < the_end) {
1025 HeapWord* b_start_3 = _offsets.block_start_const(addr_3);
1026 if (b_start_3 != p) {
1027 gclog_or_tty->print_cr("BOT look up for top + diff: "PTR_FORMAT" "
1028 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
1029 addr_3, b_start_3, p);
1030 *failures = true;
1031 return;
1032 }
1033 }
1034
1035 // Loook up end - 1
1036 HeapWord* addr_4 = the_end - 1;
1037 HeapWord* b_start_4 = _offsets.block_start_const(addr_4);
1038 if (b_start_4 != p) {
1039 gclog_or_tty->print_cr("BOT look up for end - 1: "PTR_FORMAT" "
1040 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
1041 addr_4, b_start_4, p);
1042 *failures = true;
1043 return;
1044 }
1045 }
1046
1047 if (is_humongous && object_num > 1) {
1048 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] is humongous "
1049 "but has "SIZE_FORMAT", objects",
1050 bottom(), end(), object_num);
1051 *failures = true;
1052 return;
1053 }
1054
1055 verify_strong_code_roots(vo, failures);
1056 }
1057
1058 void HeapRegion::verify() const {
1059 bool dummy = false;
1060 verify(VerifyOption_G1UsePrevMarking, /* failures */ &dummy);
1061 }
1062
1063 // G1OffsetTableContigSpace code; copied from space.cpp. Hope this can go
1064 // away eventually.
1065
1066 void G1OffsetTableContigSpace::clear(bool mangle_space) {
1067 ContiguousSpace::clear(mangle_space);
1068 _offsets.zero_bottom_entry();
1069 _offsets.initialize_threshold();
1070 }
1071
1072 void G1OffsetTableContigSpace::set_bottom(HeapWord* new_bottom) {
1073 Space::set_bottom(new_bottom);
1074 _offsets.set_bottom(new_bottom);
1075 }
1076
1077 void G1OffsetTableContigSpace::set_end(HeapWord* new_end) {
1078 Space::set_end(new_end);
1079 _offsets.resize(new_end - bottom());
1080 }
1081
1082 void G1OffsetTableContigSpace::print() const {
1083 print_short();
1084 gclog_or_tty->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", "
1085 INTPTR_FORMAT ", " INTPTR_FORMAT ")",
1086 bottom(), top(), _offsets.threshold(), end());
1087 }
1088
1089 HeapWord* G1OffsetTableContigSpace::initialize_threshold() {
1090 return _offsets.initialize_threshold();
1091 }
1092
1093 HeapWord* G1OffsetTableContigSpace::cross_threshold(HeapWord* start,
1094 HeapWord* end) {
1095 _offsets.alloc_block(start, end);
1096 return _offsets.threshold();
1097 }
1098
1099 HeapWord* G1OffsetTableContigSpace::saved_mark_word() const {
1100 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1101 assert( _gc_time_stamp <= g1h->get_gc_time_stamp(), "invariant" );
1102 if (_gc_time_stamp < g1h->get_gc_time_stamp())
1103 return top();
1104 else
1105 return ContiguousSpace::saved_mark_word();
1106 }
1107
1108 void G1OffsetTableContigSpace::set_saved_mark() {
1109 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1110 unsigned curr_gc_time_stamp = g1h->get_gc_time_stamp();
1111
1112 if (_gc_time_stamp < curr_gc_time_stamp) {
1113 // The order of these is important, as another thread might be
1114 // about to start scanning this region. If it does so after
1115 // set_saved_mark and before _gc_time_stamp = ..., then the latter
1116 // will be false, and it will pick up top() as the high water mark
1117 // of region. If it does so after _gc_time_stamp = ..., then it
1118 // will pick up the right saved_mark_word() as the high water mark
1119 // of the region. Either way, the behaviour will be correct.
1120 ContiguousSpace::set_saved_mark();
1121 OrderAccess::storestore();
1122 _gc_time_stamp = curr_gc_time_stamp;
1123 // No need to do another barrier to flush the writes above. If
1124 // this is called in parallel with other threads trying to
1125 // allocate into the region, the caller should call this while
1126 // holding a lock and when the lock is released the writes will be
1127 // flushed.
1128 }
1129 }
1130
1131 G1OffsetTableContigSpace::
1132 G1OffsetTableContigSpace(G1BlockOffsetSharedArray* sharedOffsetArray,
1133 MemRegion mr) :
1134 _offsets(sharedOffsetArray, mr),
1135 _par_alloc_lock(Mutex::leaf, "OffsetTableContigSpace par alloc lock", true),
1136 _gc_time_stamp(0)
1137 {
1138 _offsets.set_space(this);
1139 // false ==> we'll do the clearing if there's clearing to be done.
1140 ContiguousSpace::initialize(mr, false, SpaceDecorator::Mangle);
1141 _offsets.zero_bottom_entry();
1142 _offsets.initialize_threshold();
1143 }