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