1 /*
2 * Copyright (c) 2001, 2013, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "code/nmethod.hpp"
27 #include "gc_implementation/g1/g1BlockOffsetTable.inline.hpp"
28 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
29 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
30 #include "gc_implementation/g1/heapRegion.inline.hpp"
31 #include "gc_implementation/g1/heapRegionRemSet.hpp"
32 #include "gc_implementation/g1/heapRegionSeq.inline.hpp"
33 #include "memory/genOopClosures.inline.hpp"
34 #include "memory/iterator.hpp"
35 #include "oops/oop.inline.hpp"
36
37 int HeapRegion::LogOfHRGrainBytes = 0;
38 int HeapRegion::LogOfHRGrainWords = 0;
39 size_t HeapRegion::GrainBytes = 0;
40 size_t HeapRegion::GrainWords = 0;
41 size_t HeapRegion::CardsPerRegion = 0;
42
43 HeapRegionDCTOC::HeapRegionDCTOC(G1CollectedHeap* g1,
44 HeapRegion* hr, ExtendedOopClosure* cl,
45 CardTableModRefBS::PrecisionStyle precision,
46 FilterKind fk) :
47 ContiguousSpaceDCTOC(hr, cl, precision, NULL),
48 _hr(hr), _fk(fk), _g1(g1) { }
49
50 FilterOutOfRegionClosure::FilterOutOfRegionClosure(HeapRegion* r,
51 OopClosure* oc) :
52 _r_bottom(r->bottom()), _r_end(r->end()), _oc(oc) { }
53
54 template<class ClosureType>
55 HeapWord* walk_mem_region_loop(ClosureType* cl, G1CollectedHeap* g1h,
56 HeapRegion* hr,
57 HeapWord* cur, HeapWord* top) {
58 oop cur_oop = oop(cur);
59 int oop_size = cur_oop->size();
60 HeapWord* next_obj = cur + oop_size;
61 while (next_obj < top) {
62 // Keep filtering the remembered set.
63 if (!g1h->is_obj_dead(cur_oop, hr)) {
64 // Bottom lies entirely below top, so we can call the
65 // non-memRegion version of oop_iterate below.
66 cur_oop->oop_iterate(cl);
67 }
68 cur = next_obj;
69 cur_oop = oop(cur);
70 oop_size = cur_oop->size();
71 next_obj = cur + oop_size;
72 }
73 return cur;
74 }
75
76 void HeapRegionDCTOC::walk_mem_region_with_cl(MemRegion mr,
77 HeapWord* bottom,
78 HeapWord* top,
79 ExtendedOopClosure* cl) {
80 G1CollectedHeap* g1h = _g1;
81 int oop_size;
82 ExtendedOopClosure* cl2 = NULL;
83
84 FilterIntoCSClosure intoCSFilt(this, g1h, cl);
85 FilterOutOfRegionClosure outOfRegionFilt(_hr, cl);
86
87 switch (_fk) {
88 case NoFilterKind: cl2 = cl; break;
89 case IntoCSFilterKind: cl2 = &intoCSFilt; break;
90 case OutOfRegionFilterKind: cl2 = &outOfRegionFilt; break;
91 default: ShouldNotReachHere();
92 }
93
94 // Start filtering what we add to the remembered set. If the object is
95 // not considered dead, either because it is marked (in the mark bitmap)
96 // or it was allocated after marking finished, then we add it. Otherwise
97 // we can safely ignore the object.
98 if (!g1h->is_obj_dead(oop(bottom), _hr)) {
99 oop_size = oop(bottom)->oop_iterate(cl2, mr);
100 } else {
101 oop_size = oop(bottom)->size();
102 }
103
104 bottom += oop_size;
105
106 if (bottom < top) {
107 // We replicate the loop below for several kinds of possible filters.
108 switch (_fk) {
109 case NoFilterKind:
110 bottom = walk_mem_region_loop(cl, g1h, _hr, bottom, top);
111 break;
112
113 case IntoCSFilterKind: {
114 FilterIntoCSClosure filt(this, g1h, cl);
115 bottom = walk_mem_region_loop(&filt, g1h, _hr, bottom, top);
116 break;
117 }
118
119 case OutOfRegionFilterKind: {
120 FilterOutOfRegionClosure filt(_hr, cl);
121 bottom = walk_mem_region_loop(&filt, g1h, _hr, bottom, top);
122 break;
123 }
124
125 default:
126 ShouldNotReachHere();
127 }
128
129 // Last object. Need to do dead-obj filtering here too.
130 if (!g1h->is_obj_dead(oop(bottom), _hr)) {
131 oop(bottom)->oop_iterate(cl2, mr);
132 }
133 }
134 }
135
136 // Minimum region size; we won't go lower than that.
137 // We might want to decrease this in the future, to deal with small
138 // heaps a bit more efficiently.
139 #define MIN_REGION_SIZE ( 1024 * 1024 )
140
141 // Maximum region size; we don't go higher than that. There's a good
142 // reason for having an upper bound. We don't want regions to get too
143 // large, otherwise cleanup's effectiveness would decrease as there
144 // will be fewer opportunities to find totally empty regions after
145 // marking.
146 #define MAX_REGION_SIZE ( 32 * 1024 * 1024 )
147
148 // The automatic region size calculation will try to have around this
149 // many regions in the heap (based on the min heap size).
150 #define TARGET_REGION_NUMBER 2048
151
152 size_t HeapRegion::max_heap_alignment() {
153 return (size_t)MAX_REGION_SIZE;
154 }
155
156 void HeapRegion::setup_heap_region_size(uintx min_heap_size) {
157 // region_size in bytes
158 uintx region_size = G1HeapRegionSize;
159 if (FLAG_IS_DEFAULT(G1HeapRegionSize)) {
160 // We base the automatic calculation on the min heap size. This
161 // can be problematic if the spread between min and max is quite
162 // wide, imagine -Xms128m -Xmx32g. But, if we decided it based on
163 // the max size, the region size might be way too large for the
164 // min size. Either way, some users might have to set the region
165 // size manually for some -Xms / -Xmx combos.
166
167 region_size = MAX2(min_heap_size / TARGET_REGION_NUMBER,
168 (uintx) MIN_REGION_SIZE);
169 }
170
171 int region_size_log = log2_long((jlong) region_size);
172 // Recalculate the region size to make sure it's a power of
173 // 2. This means that region_size is the largest power of 2 that's
174 // <= what we've calculated so far.
175 region_size = ((uintx)1 << region_size_log);
176
177 // Now make sure that we don't go over or under our limits.
178 if (region_size < MIN_REGION_SIZE) {
179 region_size = MIN_REGION_SIZE;
180 } else if (region_size > MAX_REGION_SIZE) {
181 region_size = MAX_REGION_SIZE;
182 }
183
184 if (region_size != G1HeapRegionSize) {
185 // Update the flag to make sure that PrintFlagsFinal logs the correct value
186 FLAG_SET_ERGO(uintx, G1HeapRegionSize, region_size);
187 }
188
189 // And recalculate the log.
190 region_size_log = log2_long((jlong) region_size);
191
192 // Now, set up the globals.
193 guarantee(LogOfHRGrainBytes == 0, "we should only set it once");
194 LogOfHRGrainBytes = region_size_log;
195
196 guarantee(LogOfHRGrainWords == 0, "we should only set it once");
197 LogOfHRGrainWords = LogOfHRGrainBytes - LogHeapWordSize;
198
199 guarantee(GrainBytes == 0, "we should only set it once");
200 // The cast to int is safe, given that we've bounded region_size by
201 // MIN_REGION_SIZE and MAX_REGION_SIZE.
202 GrainBytes = (size_t)region_size;
203
204 guarantee(GrainWords == 0, "we should only set it once");
205 GrainWords = GrainBytes >> LogHeapWordSize;
206 guarantee((size_t) 1 << LogOfHRGrainWords == GrainWords, "sanity");
207
208 guarantee(CardsPerRegion == 0, "we should only set it once");
209 CardsPerRegion = GrainBytes >> CardTableModRefBS::card_shift;
210 }
211
212 void HeapRegion::reset_after_compaction() {
213 G1OffsetTableContigSpace::reset_after_compaction();
214 // After a compaction the mark bitmap is invalid, so we must
215 // treat all objects as being inside the unmarked area.
216 zero_marked_bytes();
217 init_top_at_mark_start();
218 }
219
220 void HeapRegion::hr_clear(bool par, bool clear_space) {
221 assert(_humongous_type == NotHumongous,
222 "we should have already filtered out humongous regions");
223 assert(_humongous_start_region == NULL,
224 "we should have already filtered out humongous regions");
225 assert(_end == _orig_end,
226 "we should have already filtered out humongous regions");
227
228 _in_collection_set = false;
229
230 set_young_index_in_cset(-1);
231 uninstall_surv_rate_group();
232 set_young_type(NotYoung);
233 reset_pre_dummy_top();
234
235 if (!par) {
236 // If this is parallel, this will be done later.
237 HeapRegionRemSet* hrrs = rem_set();
238 hrrs->clear();
239 _claimed = InitialClaimValue;
240 }
241 zero_marked_bytes();
242
243 _offsets.resize(HeapRegion::GrainWords);
244 init_top_at_mark_start();
245 if (clear_space) clear(SpaceDecorator::Mangle);
246 }
247
248 void HeapRegion::par_clear() {
249 assert(used() == 0, "the region should have been already cleared");
250 assert(capacity() == HeapRegion::GrainBytes, "should be back to normal");
251 HeapRegionRemSet* hrrs = rem_set();
252 hrrs->clear();
253 CardTableModRefBS* ct_bs =
254 (CardTableModRefBS*)G1CollectedHeap::heap()->barrier_set();
255 ct_bs->clear(MemRegion(bottom(), end()));
256 }
257
258 void HeapRegion::calc_gc_efficiency() {
259 // GC efficiency is the ratio of how much space would be
260 // reclaimed over how long we predict it would take to reclaim it.
261 G1CollectedHeap* g1h = G1CollectedHeap::heap();
262 G1CollectorPolicy* g1p = g1h->g1_policy();
263
264 // Retrieve a prediction of the elapsed time for this region for
265 // a mixed gc because the region will only be evacuated during a
266 // mixed gc.
267 double region_elapsed_time_ms =
268 g1p->predict_region_elapsed_time_ms(this, false /* for_young_gc */);
269 _gc_efficiency = (double) reclaimable_bytes() / region_elapsed_time_ms;
270 }
271
272 void HeapRegion::set_startsHumongous(HeapWord* new_top, HeapWord* new_end) {
273 assert(!isHumongous(), "sanity / pre-condition");
274 assert(end() == _orig_end,
275 "Should be normal before the humongous object allocation");
276 assert(top() == bottom(), "should be empty");
277 assert(bottom() <= new_top && new_top <= new_end, "pre-condition");
278
279 _humongous_type = StartsHumongous;
280 _humongous_start_region = this;
281
282 set_end(new_end);
283 _offsets.set_for_starts_humongous(new_top);
284 }
285
286 void HeapRegion::set_continuesHumongous(HeapRegion* first_hr) {
287 assert(!isHumongous(), "sanity / pre-condition");
288 assert(end() == _orig_end,
289 "Should be normal before the humongous object allocation");
290 assert(top() == bottom(), "should be empty");
291 assert(first_hr->startsHumongous(), "pre-condition");
292
293 _humongous_type = ContinuesHumongous;
294 _humongous_start_region = first_hr;
295 }
296
297 void HeapRegion::set_notHumongous() {
298 assert(isHumongous(), "pre-condition");
299
300 if (startsHumongous()) {
301 assert(top() <= end(), "pre-condition");
302 set_end(_orig_end);
303 if (top() > end()) {
304 // at least one "continues humongous" region after it
305 set_top(end());
306 }
307 } else {
308 // continues humongous
309 assert(end() == _orig_end, "sanity");
310 }
311
312 assert(capacity() == HeapRegion::GrainBytes, "pre-condition");
313 _humongous_type = NotHumongous;
314 _humongous_start_region = NULL;
315 }
316
317 bool HeapRegion::claimHeapRegion(jint claimValue) {
318 jint current = _claimed;
319 if (current != claimValue) {
320 jint res = Atomic::cmpxchg(claimValue, &_claimed, current);
321 if (res == current) {
322 return true;
323 }
324 }
325 return false;
326 }
327
328 HeapWord* HeapRegion::next_block_start_careful(HeapWord* addr) {
329 HeapWord* low = addr;
330 HeapWord* high = end();
331 while (low < high) {
332 size_t diff = pointer_delta(high, low);
333 // Must add one below to bias toward the high amount. Otherwise, if
334 // "high" were at the desired value, and "low" were one less, we
335 // would not converge on "high". This is not symmetric, because
336 // we set "high" to a block start, which might be the right one,
337 // which we don't do for "low".
338 HeapWord* middle = low + (diff+1)/2;
339 if (middle == high) return high;
340 HeapWord* mid_bs = block_start_careful(middle);
341 if (mid_bs < addr) {
342 low = middle;
343 } else {
344 high = mid_bs;
345 }
346 }
347 assert(low == high && low >= addr, "Didn't work.");
348 return low;
349 }
350
351 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
352 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
353 #endif // _MSC_VER
354
355
356 HeapRegion::HeapRegion(uint hrs_index,
357 G1BlockOffsetSharedArray* sharedOffsetArray,
358 MemRegion mr) :
359 G1OffsetTableContigSpace(sharedOffsetArray, mr),
360 _hrs_index(hrs_index),
361 _humongous_type(NotHumongous), _humongous_start_region(NULL),
362 _in_collection_set(false),
363 _next_in_special_set(NULL), _orig_end(NULL),
364 _claimed(InitialClaimValue), _evacuation_failed(false),
365 _prev_marked_bytes(0), _next_marked_bytes(0), _gc_efficiency(0.0),
366 _young_type(NotYoung), _next_young_region(NULL),
367 _next_dirty_cards_region(NULL), _next(NULL), _pending_removal(false),
368 #ifdef ASSERT
369 _containing_set(NULL),
370 #endif // ASSERT
371 _young_index_in_cset(-1), _surv_rate_group(NULL), _age_index(-1),
372 _rem_set(NULL), _recorded_rs_length(0), _predicted_elapsed_time_ms(0),
373 _predicted_bytes_to_copy(0)
374 {
375 _rem_set = new HeapRegionRemSet(sharedOffsetArray, this);
376 _orig_end = mr.end();
377 // Note that initialize() will set the start of the unmarked area of the
378 // region.
379 hr_clear(false /*par*/, false /*clear_space*/);
380 set_top(bottom());
381 set_saved_mark();
382
383 assert(HeapRegionRemSet::num_par_rem_sets() > 0, "Invariant.");
384 }
385
386 CompactibleSpace* HeapRegion::next_compaction_space() const {
387 // We're not using an iterator given that it will wrap around when
388 // it reaches the last region and this is not what we want here.
389 G1CollectedHeap* g1h = G1CollectedHeap::heap();
390 uint index = hrs_index() + 1;
391 while (index < g1h->n_regions()) {
392 HeapRegion* hr = g1h->region_at(index);
393 if (!hr->isHumongous()) {
394 return hr;
395 }
396 index += 1;
397 }
398 return NULL;
399 }
400
401 void HeapRegion::save_marks() {
402 set_saved_mark();
403 }
404
405 void HeapRegion::oops_in_mr_iterate(MemRegion mr, ExtendedOopClosure* cl) {
406 HeapWord* p = mr.start();
407 HeapWord* e = mr.end();
408 oop obj;
409 while (p < e) {
410 obj = oop(p);
411 p += obj->oop_iterate(cl);
412 }
413 assert(p == e, "bad memregion: doesn't end on obj boundary");
414 }
415
416 #define HeapRegion_OOP_SINCE_SAVE_MARKS_DEFN(OopClosureType, nv_suffix) \
417 void HeapRegion::oop_since_save_marks_iterate##nv_suffix(OopClosureType* cl) { \
418 ContiguousSpace::oop_since_save_marks_iterate##nv_suffix(cl); \
419 }
420 SPECIALIZED_SINCE_SAVE_MARKS_CLOSURES(HeapRegion_OOP_SINCE_SAVE_MARKS_DEFN)
421
422
423 void HeapRegion::oop_before_save_marks_iterate(ExtendedOopClosure* cl) {
424 oops_in_mr_iterate(MemRegion(bottom(), saved_mark_word()), cl);
425 }
426
427 void HeapRegion::note_self_forwarding_removal_start(bool during_initial_mark,
428 bool during_conc_mark) {
429 // We always recreate the prev marking info and we'll explicitly
430 // mark all objects we find to be self-forwarded on the prev
431 // bitmap. So all objects need to be below PTAMS.
432 _prev_top_at_mark_start = top();
433 _prev_marked_bytes = 0;
434
435 if (during_initial_mark) {
436 // During initial-mark, we'll also explicitly mark all objects
437 // we find to be self-forwarded on the next bitmap. So all
438 // objects need to be below NTAMS.
439 _next_top_at_mark_start = top();
440 _next_marked_bytes = 0;
441 } else if (during_conc_mark) {
442 // During concurrent mark, all objects in the CSet (including
443 // the ones we find to be self-forwarded) are implicitly live.
444 // So all objects need to be above NTAMS.
445 _next_top_at_mark_start = bottom();
446 _next_marked_bytes = 0;
447 }
448 }
449
450 void HeapRegion::note_self_forwarding_removal_end(bool during_initial_mark,
451 bool during_conc_mark,
452 size_t marked_bytes) {
453 assert(0 <= marked_bytes && marked_bytes <= used(),
454 err_msg("marked: "SIZE_FORMAT" used: "SIZE_FORMAT,
455 marked_bytes, used()));
456 _prev_marked_bytes = marked_bytes;
457 }
458
459 HeapWord*
460 HeapRegion::object_iterate_mem_careful(MemRegion mr,
461 ObjectClosure* cl) {
462 G1CollectedHeap* g1h = G1CollectedHeap::heap();
463 // We used to use "block_start_careful" here. But we're actually happy
464 // to update the BOT while we do this...
465 HeapWord* cur = block_start(mr.start());
466 mr = mr.intersection(used_region());
467 if (mr.is_empty()) return NULL;
468 // Otherwise, find the obj that extends onto mr.start().
469
470 assert(cur <= mr.start()
471 && (oop(cur)->klass_or_null() == NULL ||
472 cur + oop(cur)->size() > mr.start()),
473 "postcondition of block_start");
474 oop obj;
475 while (cur < mr.end()) {
476 obj = oop(cur);
477 if (obj->klass_or_null() == NULL) {
478 // Ran into an unparseable point.
479 return cur;
480 } else if (!g1h->is_obj_dead(obj)) {
481 cl->do_object(obj);
482 }
483 if (cl->abort()) return cur;
484 // The check above must occur before the operation below, since an
485 // abort might invalidate the "size" operation.
486 cur += obj->size();
487 }
488 return NULL;
489 }
490
491 HeapWord*
492 HeapRegion::
493 oops_on_card_seq_iterate_careful(MemRegion mr,
494 FilterOutOfRegionClosure* cl,
495 bool filter_young,
496 jbyte* card_ptr) {
497 // Currently, we should only have to clean the card if filter_young
498 // is true and vice versa.
499 if (filter_young) {
500 assert(card_ptr != NULL, "pre-condition");
501 } else {
502 assert(card_ptr == NULL, "pre-condition");
503 }
504 G1CollectedHeap* g1h = G1CollectedHeap::heap();
505
506 // If we're within a stop-world GC, then we might look at a card in a
507 // GC alloc region that extends onto a GC LAB, which may not be
508 // parseable. Stop such at the "saved_mark" of the region.
509 if (g1h->is_gc_active()) {
510 mr = mr.intersection(used_region_at_save_marks());
511 } else {
512 mr = mr.intersection(used_region());
513 }
514 if (mr.is_empty()) return NULL;
515 // Otherwise, find the obj that extends onto mr.start().
516
517 // The intersection of the incoming mr (for the card) and the
518 // allocated part of the region is non-empty. This implies that
519 // we have actually allocated into this region. The code in
520 // G1CollectedHeap.cpp that allocates a new region sets the
521 // is_young tag on the region before allocating. Thus we
522 // safely know if this region is young.
523 if (is_young() && filter_young) {
524 return NULL;
525 }
526
527 assert(!is_young(), "check value of filter_young");
528
529 // We can only clean the card here, after we make the decision that
530 // the card is not young. And we only clean the card if we have been
531 // asked to (i.e., card_ptr != NULL).
532 if (card_ptr != NULL) {
533 *card_ptr = CardTableModRefBS::clean_card_val();
534 // We must complete this write before we do any of the reads below.
535 OrderAccess::storeload();
536 }
537
538 // Cache the boundaries of the memory region in some const locals
539 HeapWord* const start = mr.start();
540 HeapWord* const end = mr.end();
541
542 // We used to use "block_start_careful" here. But we're actually happy
543 // to update the BOT while we do this...
544 HeapWord* cur = block_start(start);
545 assert(cur <= start, "Postcondition");
546
547 oop obj;
548
549 HeapWord* next = cur;
550 while (next <= start) {
551 cur = next;
552 obj = oop(cur);
553 if (obj->klass_or_null() == NULL) {
554 // Ran into an unparseable point.
555 return cur;
556 }
557 // Otherwise...
558 next = (cur + obj->size());
559 }
560
561 // If we finish the above loop...We have a parseable object that
562 // begins on or before the start of the memory region, and ends
563 // inside or spans the entire region.
564
565 assert(obj == oop(cur), "sanity");
566 assert(cur <= start &&
567 obj->klass_or_null() != NULL &&
568 (cur + obj->size()) > start,
569 "Loop postcondition");
570
571 if (!g1h->is_obj_dead(obj)) {
572 obj->oop_iterate(cl, mr);
573 }
574
575 while (cur < end) {
576 obj = oop(cur);
577 if (obj->klass_or_null() == NULL) {
578 // Ran into an unparseable point.
579 return cur;
580 };
581
582 // Otherwise:
583 next = (cur + obj->size());
584
585 if (!g1h->is_obj_dead(obj)) {
586 if (next < end || !obj->is_objArray()) {
587 // This object either does not span the MemRegion
588 // boundary, or if it does it's not an array.
589 // Apply closure to whole object.
590 obj->oop_iterate(cl);
591 } else {
592 // This obj is an array that spans the boundary.
593 // Stop at the boundary.
594 obj->oop_iterate(cl, mr);
595 }
596 }
597 cur = next;
598 }
599 return NULL;
600 }
601
602 // Code roots support
603
604 void HeapRegion::add_strong_code_root(nmethod* nm) {
605 HeapRegionRemSet* hrrs = rem_set();
606 hrrs->add_strong_code_root(nm);
607 }
608
609 void HeapRegion::remove_strong_code_root(nmethod* nm) {
610 HeapRegionRemSet* hrrs = rem_set();
611 hrrs->remove_strong_code_root(nm);
612 }
613
614 void HeapRegion::migrate_strong_code_roots() {
615 assert(in_collection_set(), "only collection set regions");
616 assert(!isHumongous(), "not humongous regions");
617
618 HeapRegionRemSet* hrrs = rem_set();
619 hrrs->migrate_strong_code_roots();
620 }
621
622 void HeapRegion::strong_code_roots_do(CodeBlobClosure* blk) const {
623 HeapRegionRemSet* hrrs = rem_set();
624 hrrs->strong_code_roots_do(blk);
625 }
626
627 class VerifyStrongCodeRootOopClosure: public OopClosure {
628 const HeapRegion* _hr;
629 nmethod* _nm;
630 bool _failures;
631 bool _has_oops_in_region;
632
633 template <class T> void do_oop_work(T* p) {
634 T heap_oop = oopDesc::load_heap_oop(p);
635 if (!oopDesc::is_null(heap_oop)) {
636 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
637
638 // Note: not all the oops embedded in the nmethod are in the
639 // current region. We only look at those which are.
640 if (_hr->is_in(obj)) {
641 // Object is in the region. Check that its less than top
642 if (_hr->top() <= (HeapWord*)obj) {
643 // Object is above top
644 gclog_or_tty->print_cr("Object "PTR_FORMAT" in region "
645 "["PTR_FORMAT", "PTR_FORMAT") is above "
646 "top "PTR_FORMAT,
647 obj, _hr->bottom(), _hr->end(), _hr->top());
648 _failures = true;
649 return;
650 }
651 // Nmethod has at least one oop in the current region
652 _has_oops_in_region = true;
653 }
654 }
655 }
656
657 public:
658 VerifyStrongCodeRootOopClosure(const HeapRegion* hr, nmethod* nm):
659 _hr(hr), _failures(false), _has_oops_in_region(false) {}
660
661 void do_oop(narrowOop* p) { do_oop_work(p); }
662 void do_oop(oop* p) { do_oop_work(p); }
663
664 bool failures() { return _failures; }
665 bool has_oops_in_region() { return _has_oops_in_region; }
666 };
667
668 class VerifyStrongCodeRootCodeBlobClosure: public CodeBlobClosure {
669 const HeapRegion* _hr;
670 bool _failures;
671 public:
672 VerifyStrongCodeRootCodeBlobClosure(const HeapRegion* hr) :
673 _hr(hr), _failures(false) {}
674
675 void do_code_blob(CodeBlob* cb) {
676 nmethod* nm = (cb == NULL) ? NULL : cb->as_nmethod_or_null();
677 if (nm != NULL) {
678 // Verify that the nemthod is live
679 if (!nm->is_alive()) {
680 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] has dead nmethod "
681 PTR_FORMAT" in its strong code roots",
682 _hr->bottom(), _hr->end(), nm);
683 _failures = true;
684 } else {
685 VerifyStrongCodeRootOopClosure oop_cl(_hr, nm);
686 nm->oops_do(&oop_cl);
687 if (!oop_cl.has_oops_in_region()) {
688 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] has nmethod "
689 PTR_FORMAT" in its strong code roots "
690 "with no pointers into region",
691 _hr->bottom(), _hr->end(), nm);
692 _failures = true;
693 } else if (oop_cl.failures()) {
694 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] has other "
695 "failures for nmethod "PTR_FORMAT,
696 _hr->bottom(), _hr->end(), nm);
697 _failures = true;
698 }
699 }
700 }
701 }
702
703 bool failures() { return _failures; }
704 };
705
706 void HeapRegion::verify_strong_code_roots(VerifyOption vo, bool* failures) const {
707 if (!G1VerifyHeapRegionCodeRoots) {
708 // We're not verifying code roots.
709 return;
710 }
711 if (vo == VerifyOption_G1UseMarkWord) {
712 // Marking verification during a full GC is performed after class
713 // unloading, code cache unloading, etc so the strong code roots
714 // attached to each heap region are in an inconsistent state. They won't
715 // be consistent until the strong code roots are rebuilt after the
716 // actual GC. Skip verifying the strong code roots in this particular
717 // time.
718 assert(VerifyDuringGC, "only way to get here");
719 return;
720 }
721
722 HeapRegionRemSet* hrrs = rem_set();
723 int strong_code_roots_length = hrrs->strong_code_roots_list_length();
724
725 // if this region is empty then there should be no entries
726 // on its strong code root list
727 if (is_empty()) {
728 if (strong_code_roots_length > 0) {
729 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] is empty "
730 "but has "INT32_FORMAT" code root entries",
731 bottom(), end(), strong_code_roots_length);
732 *failures = true;
733 }
734 return;
735 }
736
737 // An H-region should have an empty strong code root list
738 if (isHumongous()) {
739 if (strong_code_roots_length > 0) {
740 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] is humongous "
741 "but has "INT32_FORMAT" code root entries",
742 bottom(), end(), strong_code_roots_length);
743 *failures = true;
744 }
745 return;
746 }
747
748 VerifyStrongCodeRootCodeBlobClosure cb_cl(this);
749 strong_code_roots_do(&cb_cl);
750
751 if (cb_cl.failures()) {
752 *failures = true;
753 }
754 }
755
756 void HeapRegion::print() const { print_on(gclog_or_tty); }
757 void HeapRegion::print_on(outputStream* st) const {
758 if (isHumongous()) {
759 if (startsHumongous())
760 st->print(" HS");
761 else
762 st->print(" HC");
763 } else {
764 st->print(" ");
765 }
766 if (in_collection_set())
767 st->print(" CS");
768 else
769 st->print(" ");
770 if (is_young())
771 st->print(is_survivor() ? " SU" : " Y ");
772 else
773 st->print(" ");
774 if (is_empty())
775 st->print(" F");
776 else
777 st->print(" ");
778 st->print(" TS %5d", _gc_time_stamp);
779 st->print(" PTAMS "PTR_FORMAT" NTAMS "PTR_FORMAT,
780 prev_top_at_mark_start(), next_top_at_mark_start());
781 G1OffsetTableContigSpace::print_on(st);
782 }
783
784 class VerifyLiveClosure: public OopClosure {
785 private:
786 G1CollectedHeap* _g1h;
787 CardTableModRefBS* _bs;
788 oop _containing_obj;
789 bool _failures;
790 int _n_failures;
791 VerifyOption _vo;
792 public:
793 // _vo == UsePrevMarking -> use "prev" marking information,
794 // _vo == UseNextMarking -> use "next" marking information,
795 // _vo == UseMarkWord -> use mark word from object header.
796 VerifyLiveClosure(G1CollectedHeap* g1h, VerifyOption vo) :
797 _g1h(g1h), _bs(NULL), _containing_obj(NULL),
798 _failures(false), _n_failures(0), _vo(vo)
799 {
800 BarrierSet* bs = _g1h->barrier_set();
801 if (bs->is_a(BarrierSet::CardTableModRef))
802 _bs = (CardTableModRefBS*)bs;
803 }
804
805 void set_containing_obj(oop obj) {
806 _containing_obj = obj;
807 }
808
809 bool failures() { return _failures; }
810 int n_failures() { return _n_failures; }
811
812 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
813 virtual void do_oop( oop* p) { do_oop_work(p); }
814
815 void print_object(outputStream* out, oop obj) {
816 #ifdef PRODUCT
817 Klass* k = obj->klass();
818 const char* class_name = InstanceKlass::cast(k)->external_name();
819 out->print_cr("class name %s", class_name);
820 #else // PRODUCT
821 obj->print_on(out);
822 #endif // PRODUCT
823 }
824
825 template <class T>
826 void do_oop_work(T* p) {
827 assert(_containing_obj != NULL, "Precondition");
828 assert(!_g1h->is_obj_dead_cond(_containing_obj, _vo),
829 "Precondition");
830 T heap_oop = oopDesc::load_heap_oop(p);
831 if (!oopDesc::is_null(heap_oop)) {
832 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
833 bool failed = false;
834 if (!_g1h->is_in_closed_subset(obj) || _g1h->is_obj_dead_cond(obj, _vo)) {
835 MutexLockerEx x(ParGCRareEvent_lock,
836 Mutex::_no_safepoint_check_flag);
837
838 if (!_failures) {
839 gclog_or_tty->print_cr("");
840 gclog_or_tty->print_cr("----------");
841 }
842 if (!_g1h->is_in_closed_subset(obj)) {
843 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
844 gclog_or_tty->print_cr("Field "PTR_FORMAT
845 " of live obj "PTR_FORMAT" in region "
846 "["PTR_FORMAT", "PTR_FORMAT")",
847 p, (void*) _containing_obj,
848 from->bottom(), from->end());
849 print_object(gclog_or_tty, _containing_obj);
850 gclog_or_tty->print_cr("points to obj "PTR_FORMAT" not in the heap",
851 (void*) obj);
852 } else {
853 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
854 HeapRegion* to = _g1h->heap_region_containing((HeapWord*)obj);
855 gclog_or_tty->print_cr("Field "PTR_FORMAT
856 " of live obj "PTR_FORMAT" in region "
857 "["PTR_FORMAT", "PTR_FORMAT")",
858 p, (void*) _containing_obj,
859 from->bottom(), from->end());
860 print_object(gclog_or_tty, _containing_obj);
861 gclog_or_tty->print_cr("points to dead obj "PTR_FORMAT" in region "
862 "["PTR_FORMAT", "PTR_FORMAT")",
863 (void*) obj, to->bottom(), to->end());
864 print_object(gclog_or_tty, obj);
865 }
866 gclog_or_tty->print_cr("----------");
867 gclog_or_tty->flush();
868 _failures = true;
869 failed = true;
870 _n_failures++;
871 }
872
873 if (!_g1h->full_collection() || G1VerifyRSetsDuringFullGC) {
874 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
875 HeapRegion* to = _g1h->heap_region_containing(obj);
876 if (from != NULL && to != NULL &&
877 from != to &&
878 !to->isHumongous()) {
879 jbyte cv_obj = *_bs->byte_for_const(_containing_obj);
880 jbyte cv_field = *_bs->byte_for_const(p);
881 const jbyte dirty = CardTableModRefBS::dirty_card_val();
882
883 bool is_bad = !(from->is_young()
884 || to->rem_set()->contains_reference(p)
885 || !G1HRRSFlushLogBuffersOnVerify && // buffers were not flushed
886 (_containing_obj->is_objArray() ?
887 cv_field == dirty
888 : cv_obj == dirty || cv_field == dirty));
889 if (is_bad) {
890 MutexLockerEx x(ParGCRareEvent_lock,
891 Mutex::_no_safepoint_check_flag);
892
893 if (!_failures) {
894 gclog_or_tty->print_cr("");
895 gclog_or_tty->print_cr("----------");
896 }
897 gclog_or_tty->print_cr("Missing rem set entry:");
898 gclog_or_tty->print_cr("Field "PTR_FORMAT" "
899 "of obj "PTR_FORMAT", "
900 "in region "HR_FORMAT,
901 p, (void*) _containing_obj,
902 HR_FORMAT_PARAMS(from));
903 _containing_obj->print_on(gclog_or_tty);
904 gclog_or_tty->print_cr("points to obj "PTR_FORMAT" "
905 "in region "HR_FORMAT,
906 (void*) obj,
907 HR_FORMAT_PARAMS(to));
908 obj->print_on(gclog_or_tty);
909 gclog_or_tty->print_cr("Obj head CTE = %d, field CTE = %d.",
910 cv_obj, cv_field);
911 gclog_or_tty->print_cr("----------");
912 gclog_or_tty->flush();
913 _failures = true;
914 if (!failed) _n_failures++;
915 }
916 }
917 }
918 }
919 }
920 };
921
922 // This really ought to be commoned up into OffsetTableContigSpace somehow.
923 // We would need a mechanism to make that code skip dead objects.
924
925 void HeapRegion::verify(VerifyOption vo,
926 bool* failures) const {
927 G1CollectedHeap* g1 = G1CollectedHeap::heap();
928 *failures = false;
929 HeapWord* p = bottom();
930 HeapWord* prev_p = NULL;
931 VerifyLiveClosure vl_cl(g1, vo);
932 bool is_humongous = isHumongous();
933 bool do_bot_verify = !is_young();
934 size_t object_num = 0;
935 while (p < top()) {
936 oop obj = oop(p);
937 size_t obj_size = obj->size();
938 object_num += 1;
939
940 if (is_humongous != g1->isHumongous(obj_size)) {
941 gclog_or_tty->print_cr("obj "PTR_FORMAT" is of %shumongous size ("
942 SIZE_FORMAT" words) in a %shumongous region",
943 p, g1->isHumongous(obj_size) ? "" : "non-",
944 obj_size, is_humongous ? "" : "non-");
945 *failures = true;
946 return;
947 }
948
949 // If it returns false, verify_for_object() will output the
950 // appropriate messasge.
951 if (do_bot_verify && !_offsets.verify_for_object(p, obj_size)) {
952 *failures = true;
953 return;
954 }
955
956 if (!g1->is_obj_dead_cond(obj, this, vo)) {
957 if (obj->is_oop()) {
958 Klass* klass = obj->klass();
959 if (!klass->is_metaspace_object()) {
960 gclog_or_tty->print_cr("klass "PTR_FORMAT" of object "PTR_FORMAT" "
961 "not metadata", klass, obj);
962 *failures = true;
963 return;
964 } else if (!klass->is_klass()) {
965 gclog_or_tty->print_cr("klass "PTR_FORMAT" of object "PTR_FORMAT" "
966 "not a klass", klass, obj);
967 *failures = true;
968 return;
969 } else {
970 vl_cl.set_containing_obj(obj);
971 obj->oop_iterate_no_header(&vl_cl);
972 if (vl_cl.failures()) {
973 *failures = true;
974 }
975 if (G1MaxVerifyFailures >= 0 &&
976 vl_cl.n_failures() >= G1MaxVerifyFailures) {
977 return;
978 }
979 }
980 } else {
981 gclog_or_tty->print_cr(PTR_FORMAT" no an oop", obj);
982 *failures = true;
983 return;
984 }
985 }
986 prev_p = p;
987 p += obj_size;
988 }
989
990 if (p != top()) {
991 gclog_or_tty->print_cr("end of last object "PTR_FORMAT" "
992 "does not match top "PTR_FORMAT, p, top());
993 *failures = true;
994 return;
995 }
996
997 HeapWord* the_end = end();
998 assert(p == top(), "it should still hold");
999 // Do some extra BOT consistency checking for addresses in the
1000 // range [top, end). BOT look-ups in this range should yield
1001 // top. No point in doing that if top == end (there's nothing there).
1002 if (p < the_end) {
1003 // Look up top
1004 HeapWord* addr_1 = p;
1005 HeapWord* b_start_1 = _offsets.block_start_const(addr_1);
1006 if (b_start_1 != p) {
1007 gclog_or_tty->print_cr("BOT look up for top: "PTR_FORMAT" "
1008 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
1009 addr_1, b_start_1, p);
1010 *failures = true;
1011 return;
1012 }
1013
1014 // Look up top + 1
1015 HeapWord* addr_2 = p + 1;
1016 if (addr_2 < the_end) {
1017 HeapWord* b_start_2 = _offsets.block_start_const(addr_2);
1018 if (b_start_2 != p) {
1019 gclog_or_tty->print_cr("BOT look up for top + 1: "PTR_FORMAT" "
1020 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
1021 addr_2, b_start_2, p);
1022 *failures = true;
1023 return;
1024 }
1025 }
1026
1027 // Look up an address between top and end
1028 size_t diff = pointer_delta(the_end, p) / 2;
1029 HeapWord* addr_3 = p + diff;
1030 if (addr_3 < the_end) {
1031 HeapWord* b_start_3 = _offsets.block_start_const(addr_3);
1032 if (b_start_3 != p) {
1033 gclog_or_tty->print_cr("BOT look up for top + diff: "PTR_FORMAT" "
1034 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
1035 addr_3, b_start_3, p);
1036 *failures = true;
1037 return;
1038 }
1039 }
1040
1041 // Loook up end - 1
1042 HeapWord* addr_4 = the_end - 1;
1043 HeapWord* b_start_4 = _offsets.block_start_const(addr_4);
1044 if (b_start_4 != p) {
1045 gclog_or_tty->print_cr("BOT look up for end - 1: "PTR_FORMAT" "
1046 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
1047 addr_4, b_start_4, p);
1048 *failures = true;
1049 return;
1050 }
1051 }
1052
1053 if (is_humongous && object_num > 1) {
1054 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] is humongous "
1055 "but has "SIZE_FORMAT", objects",
1056 bottom(), end(), object_num);
1057 *failures = true;
1058 return;
1059 }
1060
1061 verify_strong_code_roots(vo, failures);
1062 }
1063
1064 void HeapRegion::verify() const {
1065 bool dummy = false;
1066 verify(VerifyOption_G1UsePrevMarking, /* failures */ &dummy);
1067 }
1068
1069 // G1OffsetTableContigSpace code; copied from space.cpp. Hope this can go
1070 // away eventually.
1071
1072 void G1OffsetTableContigSpace::clear(bool mangle_space) {
1073 ContiguousSpace::clear(mangle_space);
1074 _offsets.zero_bottom_entry();
1075 _offsets.initialize_threshold();
1076 }
1077
1078 void G1OffsetTableContigSpace::set_bottom(HeapWord* new_bottom) {
1079 Space::set_bottom(new_bottom);
1080 _offsets.set_bottom(new_bottom);
1081 }
1082
1083 void G1OffsetTableContigSpace::set_end(HeapWord* new_end) {
1084 Space::set_end(new_end);
1085 _offsets.resize(new_end - bottom());
1086 }
1087
1088 void G1OffsetTableContigSpace::print() const {
1089 print_short();
1090 gclog_or_tty->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", "
1091 INTPTR_FORMAT ", " INTPTR_FORMAT ")",
1092 bottom(), top(), _offsets.threshold(), end());
1093 }
1094
1095 HeapWord* G1OffsetTableContigSpace::initialize_threshold() {
1096 return _offsets.initialize_threshold();
1097 }
1098
1099 HeapWord* G1OffsetTableContigSpace::cross_threshold(HeapWord* start,
1100 HeapWord* end) {
1101 _offsets.alloc_block(start, end);
1102 return _offsets.threshold();
1103 }
1104
1105 HeapWord* G1OffsetTableContigSpace::saved_mark_word() const {
1106 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1107 assert( _gc_time_stamp <= g1h->get_gc_time_stamp(), "invariant" );
1108 if (_gc_time_stamp < g1h->get_gc_time_stamp())
1109 return top();
1110 else
1111 return ContiguousSpace::saved_mark_word();
1112 }
1113
1114 void G1OffsetTableContigSpace::set_saved_mark() {
1115 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1116 unsigned curr_gc_time_stamp = g1h->get_gc_time_stamp();
1117
1118 if (_gc_time_stamp < curr_gc_time_stamp) {
1119 // The order of these is important, as another thread might be
1120 // about to start scanning this region. If it does so after
1121 // set_saved_mark and before _gc_time_stamp = ..., then the latter
1122 // will be false, and it will pick up top() as the high water mark
1123 // of region. If it does so after _gc_time_stamp = ..., then it
1124 // will pick up the right saved_mark_word() as the high water mark
1125 // of the region. Either way, the behaviour will be correct.
1126 ContiguousSpace::set_saved_mark();
1127 OrderAccess::storestore();
1128 _gc_time_stamp = curr_gc_time_stamp;
1129 // No need to do another barrier to flush the writes above. If
1130 // this is called in parallel with other threads trying to
1131 // allocate into the region, the caller should call this while
1132 // holding a lock and when the lock is released the writes will be
1133 // flushed.
1134 }
1135 }
1136
1137 G1OffsetTableContigSpace::
1138 G1OffsetTableContigSpace(G1BlockOffsetSharedArray* sharedOffsetArray,
1139 MemRegion mr) :
1140 _offsets(sharedOffsetArray, mr),
1141 _par_alloc_lock(Mutex::leaf, "OffsetTableContigSpace par alloc lock", true),
1142 _gc_time_stamp(0)
1143 {
1144 _offsets.set_space(this);
1145 // false ==> we'll do the clearing if there's clearing to be done.
1146 ContiguousSpace::initialize(mr, false, SpaceDecorator::Mangle);
1147 _offsets.zero_bottom_entry();
1148 _offsets.initialize_threshold();
1149 }