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/heapRegionManager.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 HeapRegion::HeapRegion(uint hrm_index,
349 G1BlockOffsetSharedArray* sharedOffsetArray,
350 MemRegion mr) :
351 G1OffsetTableContigSpace(sharedOffsetArray, mr),
352 _hrm_index(hrm_index),
353 _humongous_type(NotHumongous), _humongous_start_region(NULL),
354 _in_collection_set(false),
355 _next_in_special_set(NULL), _orig_end(NULL),
356 _claimed(InitialClaimValue), _evacuation_failed(false),
357 _prev_marked_bytes(0), _next_marked_bytes(0), _gc_efficiency(0.0),
358 _young_type(NotYoung), _next_young_region(NULL),
359 _next_dirty_cards_region(NULL), _next(NULL), _prev(NULL),
360 #ifdef ASSERT
361 _containing_set(NULL),
362 #endif // ASSERT
363 _young_index_in_cset(-1), _surv_rate_group(NULL), _age_index(-1),
364 _rem_set(NULL), _recorded_rs_length(0), _predicted_elapsed_time_ms(0),
365 _predicted_bytes_to_copy(0)
366 {
367 _rem_set = new HeapRegionRemSet(sharedOffsetArray, this);
368 assert(HeapRegionRemSet::num_par_rem_sets() > 0, "Invariant.");
369
370 initialize(mr);
371 }
372
373 void HeapRegion::initialize(MemRegion mr, bool clear_space, bool mangle_space) {
374 assert(_rem_set->is_empty(), "Remembered set must be empty");
375
376 G1OffsetTableContigSpace::initialize(mr, clear_space, mangle_space);
377
378 _orig_end = mr.end();
379 hr_clear(false /*par*/, false /*clear_space*/);
380 set_top(bottom());
381 record_top_and_timestamp();
382 }
383
384 CompactibleSpace* HeapRegion::next_compaction_space() const {
385 return G1CollectedHeap::heap()->next_compaction_region(this);
386 }
387
388 void HeapRegion::note_self_forwarding_removal_start(bool during_initial_mark,
389 bool during_conc_mark) {
390 // We always recreate the prev marking info and we'll explicitly
391 // mark all objects we find to be self-forwarded on the prev
392 // bitmap. So all objects need to be below PTAMS.
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_top_at_mark_start = top();
417 _prev_marked_bytes = marked_bytes;
418 }
419
420 HeapWord*
421 HeapRegion::object_iterate_mem_careful(MemRegion mr,
422 ObjectClosure* cl) {
423 G1CollectedHeap* g1h = G1CollectedHeap::heap();
424 // We used to use "block_start_careful" here. But we're actually happy
425 // to update the BOT while we do this...
426 HeapWord* cur = block_start(mr.start());
427 mr = mr.intersection(used_region());
428 if (mr.is_empty()) return NULL;
429 // Otherwise, find the obj that extends onto mr.start().
430
431 assert(cur <= mr.start()
432 && (oop(cur)->klass_or_null() == NULL ||
433 cur + oop(cur)->size() > mr.start()),
434 "postcondition of block_start");
435 oop obj;
436 while (cur < mr.end()) {
437 obj = oop(cur);
438 if (obj->klass_or_null() == NULL) {
439 // Ran into an unparseable point.
440 return cur;
441 } else if (!g1h->is_obj_dead(obj)) {
442 cl->do_object(obj);
443 }
444 cur += block_size(cur);
445 }
446 return NULL;
447 }
448
449 HeapWord*
450 HeapRegion::
451 oops_on_card_seq_iterate_careful(MemRegion mr,
452 FilterOutOfRegionClosure* cl,
453 bool filter_young,
454 jbyte* card_ptr) {
455 // Currently, we should only have to clean the card if filter_young
456 // is true and vice versa.
457 if (filter_young) {
458 assert(card_ptr != NULL, "pre-condition");
459 } else {
460 assert(card_ptr == NULL, "pre-condition");
461 }
462 G1CollectedHeap* g1h = G1CollectedHeap::heap();
463
464 // If we're within a stop-world GC, then we might look at a card in a
465 // GC alloc region that extends onto a GC LAB, which may not be
466 // parseable. Stop such at the "saved_mark" of the region.
467 if (g1h->is_gc_active()) {
468 mr = mr.intersection(used_region_at_save_marks());
469 } else {
470 mr = mr.intersection(used_region());
471 }
472 if (mr.is_empty()) return NULL;
473 // Otherwise, find the obj that extends onto mr.start().
474
475 // The intersection of the incoming mr (for the card) and the
476 // allocated part of the region is non-empty. This implies that
477 // we have actually allocated into this region. The code in
478 // G1CollectedHeap.cpp that allocates a new region sets the
479 // is_young tag on the region before allocating. Thus we
480 // safely know if this region is young.
481 if (is_young() && filter_young) {
482 return NULL;
483 }
484
485 assert(!is_young(), "check value of filter_young");
486
487 // We can only clean the card here, after we make the decision that
488 // the card is not young. And we only clean the card if we have been
489 // asked to (i.e., card_ptr != NULL).
490 if (card_ptr != NULL) {
491 *card_ptr = CardTableModRefBS::clean_card_val();
492 // We must complete this write before we do any of the reads below.
493 OrderAccess::storeload();
494 }
495
496 // Cache the boundaries of the memory region in some const locals
497 HeapWord* const start = mr.start();
498 HeapWord* const end = mr.end();
499
500 // We used to use "block_start_careful" here. But we're actually happy
501 // to update the BOT while we do this...
502 HeapWord* cur = block_start(start);
503 assert(cur <= start, "Postcondition");
504
505 oop obj;
506
507 HeapWord* next = cur;
508 while (next <= start) {
509 cur = next;
510 obj = oop(cur);
511 if (obj->klass_or_null() == NULL) {
512 // Ran into an unparseable point.
513 return cur;
514 }
515 // Otherwise...
516 next = cur + block_size(cur);
517 }
518
519 // If we finish the above loop...We have a parseable object that
520 // begins on or before the start of the memory region, and ends
521 // inside or spans the entire region.
522
523 assert(obj == oop(cur), "sanity");
524 assert(cur <= start, "Loop postcondition");
525 assert(obj->klass_or_null() != NULL, "Loop postcondition");
526 assert((cur + block_size(cur)) > start, "Loop postcondition");
527
528 if (!g1h->is_obj_dead(obj)) {
529 obj->oop_iterate(cl, mr);
530 }
531
532 while (cur < end) {
533 obj = oop(cur);
534 if (obj->klass_or_null() == NULL) {
535 // Ran into an unparseable point.
536 return cur;
537 };
538
539 // Otherwise:
540 next = cur + block_size(cur);
541
542 if (!g1h->is_obj_dead(obj)) {
543 if (next < end || !obj->is_objArray()) {
544 // This object either does not span the MemRegion
545 // boundary, or if it does it's not an array.
546 // Apply closure to whole object.
547 obj->oop_iterate(cl);
548 } else {
549 // This obj is an array that spans the boundary.
550 // Stop at the boundary.
551 obj->oop_iterate(cl, mr);
552 }
553 }
554 cur = next;
555 }
556 return NULL;
557 }
558
559 // Code roots support
560
561 void HeapRegion::add_strong_code_root(nmethod* nm) {
562 HeapRegionRemSet* hrrs = rem_set();
563 hrrs->add_strong_code_root(nm);
564 }
565
566 void HeapRegion::remove_strong_code_root(nmethod* nm) {
567 HeapRegionRemSet* hrrs = rem_set();
568 hrrs->remove_strong_code_root(nm);
569 }
570
571 void HeapRegion::migrate_strong_code_roots() {
572 assert(in_collection_set(), "only collection set regions");
573 assert(!isHumongous(),
574 err_msg("humongous region "HR_FORMAT" should not have been added to collection set",
575 HR_FORMAT_PARAMS(this)));
576
577 HeapRegionRemSet* hrrs = rem_set();
578 hrrs->migrate_strong_code_roots();
579 }
580
581 void HeapRegion::strong_code_roots_do(CodeBlobClosure* blk) const {
582 HeapRegionRemSet* hrrs = rem_set();
583 hrrs->strong_code_roots_do(blk);
584 }
585
586 class VerifyStrongCodeRootOopClosure: public OopClosure {
587 const HeapRegion* _hr;
588 nmethod* _nm;
589 bool _failures;
590 bool _has_oops_in_region;
591
592 template <class T> void do_oop_work(T* p) {
593 T heap_oop = oopDesc::load_heap_oop(p);
594 if (!oopDesc::is_null(heap_oop)) {
595 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
596
597 // Note: not all the oops embedded in the nmethod are in the
598 // current region. We only look at those which are.
599 if (_hr->is_in(obj)) {
600 // Object is in the region. Check that its less than top
601 if (_hr->top() <= (HeapWord*)obj) {
602 // Object is above top
603 gclog_or_tty->print_cr("Object "PTR_FORMAT" in region "
604 "["PTR_FORMAT", "PTR_FORMAT") is above "
605 "top "PTR_FORMAT,
606 (void *)obj, _hr->bottom(), _hr->end(), _hr->top());
607 _failures = true;
608 return;
609 }
610 // Nmethod has at least one oop in the current region
611 _has_oops_in_region = true;
612 }
613 }
614 }
615
616 public:
617 VerifyStrongCodeRootOopClosure(const HeapRegion* hr, nmethod* nm):
618 _hr(hr), _failures(false), _has_oops_in_region(false) {}
619
620 void do_oop(narrowOop* p) { do_oop_work(p); }
621 void do_oop(oop* p) { do_oop_work(p); }
622
623 bool failures() { return _failures; }
624 bool has_oops_in_region() { return _has_oops_in_region; }
625 };
626
627 class VerifyStrongCodeRootCodeBlobClosure: public CodeBlobClosure {
628 const HeapRegion* _hr;
629 bool _failures;
630 public:
631 VerifyStrongCodeRootCodeBlobClosure(const HeapRegion* hr) :
632 _hr(hr), _failures(false) {}
633
634 void do_code_blob(CodeBlob* cb) {
635 nmethod* nm = (cb == NULL) ? NULL : cb->as_nmethod_or_null();
636 if (nm != NULL) {
637 // Verify that the nemthod is live
638 if (!nm->is_alive()) {
639 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] has dead nmethod "
640 PTR_FORMAT" in its strong code roots",
641 _hr->bottom(), _hr->end(), nm);
642 _failures = true;
643 } else {
644 VerifyStrongCodeRootOopClosure oop_cl(_hr, nm);
645 nm->oops_do(&oop_cl);
646 if (!oop_cl.has_oops_in_region()) {
647 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] has nmethod "
648 PTR_FORMAT" in its strong code roots "
649 "with no pointers into region",
650 _hr->bottom(), _hr->end(), nm);
651 _failures = true;
652 } else if (oop_cl.failures()) {
653 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] has other "
654 "failures for nmethod "PTR_FORMAT,
655 _hr->bottom(), _hr->end(), nm);
656 _failures = true;
657 }
658 }
659 }
660 }
661
662 bool failures() { return _failures; }
663 };
664
665 void HeapRegion::verify_strong_code_roots(VerifyOption vo, bool* failures) const {
666 if (!G1VerifyHeapRegionCodeRoots) {
667 // We're not verifying code roots.
668 return;
669 }
670 if (vo == VerifyOption_G1UseMarkWord) {
671 // Marking verification during a full GC is performed after class
672 // unloading, code cache unloading, etc so the strong code roots
673 // attached to each heap region are in an inconsistent state. They won't
674 // be consistent until the strong code roots are rebuilt after the
675 // actual GC. Skip verifying the strong code roots in this particular
676 // time.
677 assert(VerifyDuringGC, "only way to get here");
678 return;
679 }
680
681 HeapRegionRemSet* hrrs = rem_set();
682 size_t strong_code_roots_length = hrrs->strong_code_roots_list_length();
683
684 // if this region is empty then there should be no entries
685 // on its strong code root list
686 if (is_empty()) {
687 if (strong_code_roots_length > 0) {
688 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] is empty "
689 "but has "SIZE_FORMAT" code root entries",
690 bottom(), end(), strong_code_roots_length);
691 *failures = true;
692 }
693 return;
694 }
695
696 if (continuesHumongous()) {
697 if (strong_code_roots_length > 0) {
698 gclog_or_tty->print_cr("region "HR_FORMAT" is a continuation of a humongous "
699 "region but has "SIZE_FORMAT" code root entries",
700 HR_FORMAT_PARAMS(this), strong_code_roots_length);
701 *failures = true;
702 }
703 return;
704 }
705
706 VerifyStrongCodeRootCodeBlobClosure cb_cl(this);
707 strong_code_roots_do(&cb_cl);
708
709 if (cb_cl.failures()) {
710 *failures = true;
711 }
712 }
713
714 void HeapRegion::print() const { print_on(gclog_or_tty); }
715 void HeapRegion::print_on(outputStream* st) const {
716 if (isHumongous()) {
717 if (startsHumongous())
718 st->print(" HS");
719 else
720 st->print(" HC");
721 } else {
722 st->print(" ");
723 }
724 if (in_collection_set())
725 st->print(" CS");
726 else
727 st->print(" ");
728 if (is_young())
729 st->print(is_survivor() ? " SU" : " Y ");
730 else
731 st->print(" ");
732 if (is_empty())
733 st->print(" F");
734 else
735 st->print(" ");
736 st->print(" TS %5d", _gc_time_stamp);
737 st->print(" PTAMS "PTR_FORMAT" NTAMS "PTR_FORMAT,
738 prev_top_at_mark_start(), next_top_at_mark_start());
739 G1OffsetTableContigSpace::print_on(st);
740 }
741
742 class VerifyLiveClosure: public OopClosure {
743 private:
744 G1CollectedHeap* _g1h;
745 CardTableModRefBS* _bs;
746 oop _containing_obj;
747 bool _failures;
748 int _n_failures;
749 VerifyOption _vo;
750 public:
751 // _vo == UsePrevMarking -> use "prev" marking information,
752 // _vo == UseNextMarking -> use "next" marking information,
753 // _vo == UseMarkWord -> use mark word from object header.
754 VerifyLiveClosure(G1CollectedHeap* g1h, VerifyOption vo) :
755 _g1h(g1h), _bs(NULL), _containing_obj(NULL),
756 _failures(false), _n_failures(0), _vo(vo)
757 {
758 BarrierSet* bs = _g1h->barrier_set();
759 if (bs->is_a(BarrierSet::CardTableModRef))
760 _bs = (CardTableModRefBS*)bs;
761 }
762
763 void set_containing_obj(oop obj) {
764 _containing_obj = obj;
765 }
766
767 bool failures() { return _failures; }
768 int n_failures() { return _n_failures; }
769
770 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
771 virtual void do_oop( oop* p) { do_oop_work(p); }
772
773 void print_object(outputStream* out, oop obj) {
774 #ifdef PRODUCT
775 Klass* k = obj->klass();
776 const char* class_name = InstanceKlass::cast(k)->external_name();
777 out->print_cr("class name %s", class_name);
778 #else // PRODUCT
779 obj->print_on(out);
780 #endif // PRODUCT
781 }
782
783 template <class T>
784 void do_oop_work(T* p) {
785 assert(_containing_obj != NULL, "Precondition");
786 assert(!_g1h->is_obj_dead_cond(_containing_obj, _vo),
787 "Precondition");
788 T heap_oop = oopDesc::load_heap_oop(p);
789 if (!oopDesc::is_null(heap_oop)) {
790 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
791 bool failed = false;
792 if (!_g1h->is_in_closed_subset(obj) || _g1h->is_obj_dead_cond(obj, _vo)) {
793 MutexLockerEx x(ParGCRareEvent_lock,
794 Mutex::_no_safepoint_check_flag);
795
796 if (!_failures) {
797 gclog_or_tty->cr();
798 gclog_or_tty->print_cr("----------");
799 }
800 if (!_g1h->is_in_closed_subset(obj)) {
801 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
802 gclog_or_tty->print_cr("Field "PTR_FORMAT
803 " of live obj "PTR_FORMAT" in region "
804 "["PTR_FORMAT", "PTR_FORMAT")",
805 p, (void*) _containing_obj,
806 from->bottom(), from->end());
807 print_object(gclog_or_tty, _containing_obj);
808 gclog_or_tty->print_cr("points to obj "PTR_FORMAT" not in the heap",
809 (void*) obj);
810 } else {
811 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
812 HeapRegion* to = _g1h->heap_region_containing((HeapWord*)obj);
813 gclog_or_tty->print_cr("Field "PTR_FORMAT
814 " of live obj "PTR_FORMAT" in region "
815 "["PTR_FORMAT", "PTR_FORMAT")",
816 p, (void*) _containing_obj,
817 from->bottom(), from->end());
818 print_object(gclog_or_tty, _containing_obj);
819 gclog_or_tty->print_cr("points to dead obj "PTR_FORMAT" in region "
820 "["PTR_FORMAT", "PTR_FORMAT")",
821 (void*) obj, to->bottom(), to->end());
822 print_object(gclog_or_tty, obj);
823 }
824 gclog_or_tty->print_cr("----------");
825 gclog_or_tty->flush();
826 _failures = true;
827 failed = true;
828 _n_failures++;
829 }
830
831 if (!_g1h->full_collection() || G1VerifyRSetsDuringFullGC) {
832 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
833 HeapRegion* to = _g1h->heap_region_containing(obj);
834 if (from != NULL && to != NULL &&
835 from != to &&
836 !to->isHumongous()) {
837 jbyte cv_obj = *_bs->byte_for_const(_containing_obj);
838 jbyte cv_field = *_bs->byte_for_const(p);
839 const jbyte dirty = CardTableModRefBS::dirty_card_val();
840
841 bool is_bad = !(from->is_young()
842 || to->rem_set()->contains_reference(p)
843 || !G1HRRSFlushLogBuffersOnVerify && // buffers were not flushed
844 (_containing_obj->is_objArray() ?
845 cv_field == dirty
846 : cv_obj == dirty || cv_field == dirty));
847 if (is_bad) {
848 MutexLockerEx x(ParGCRareEvent_lock,
849 Mutex::_no_safepoint_check_flag);
850
851 if (!_failures) {
852 gclog_or_tty->cr();
853 gclog_or_tty->print_cr("----------");
854 }
855 gclog_or_tty->print_cr("Missing rem set entry:");
856 gclog_or_tty->print_cr("Field "PTR_FORMAT" "
857 "of obj "PTR_FORMAT", "
858 "in region "HR_FORMAT,
859 p, (void*) _containing_obj,
860 HR_FORMAT_PARAMS(from));
861 _containing_obj->print_on(gclog_or_tty);
862 gclog_or_tty->print_cr("points to obj "PTR_FORMAT" "
863 "in region "HR_FORMAT,
864 (void*) obj,
865 HR_FORMAT_PARAMS(to));
866 obj->print_on(gclog_or_tty);
867 gclog_or_tty->print_cr("Obj head CTE = %d, field CTE = %d.",
868 cv_obj, cv_field);
869 gclog_or_tty->print_cr("----------");
870 gclog_or_tty->flush();
871 _failures = true;
872 if (!failed) _n_failures++;
873 }
874 }
875 }
876 }
877 }
878 };
879
880 // This really ought to be commoned up into OffsetTableContigSpace somehow.
881 // We would need a mechanism to make that code skip dead objects.
882
883 void HeapRegion::verify(VerifyOption vo,
884 bool* failures) const {
885 G1CollectedHeap* g1 = G1CollectedHeap::heap();
886 *failures = false;
887 HeapWord* p = bottom();
888 HeapWord* prev_p = NULL;
889 VerifyLiveClosure vl_cl(g1, vo);
890 bool is_humongous = isHumongous();
891 bool do_bot_verify = !is_young();
892 size_t object_num = 0;
893 while (p < top()) {
894 oop obj = oop(p);
895 size_t obj_size = block_size(p);
896 object_num += 1;
897
898 if (is_humongous != g1->isHumongous(obj_size) &&
899 !g1->is_obj_dead(obj, this)) { // Dead objects may have bigger block_size since they span several objects.
900 gclog_or_tty->print_cr("obj "PTR_FORMAT" is of %shumongous size ("
901 SIZE_FORMAT" words) in a %shumongous region",
902 p, g1->isHumongous(obj_size) ? "" : "non-",
903 obj_size, is_humongous ? "" : "non-");
904 *failures = true;
905 return;
906 }
907
908 // If it returns false, verify_for_object() will output the
909 // appropriate message.
910 if (do_bot_verify &&
911 !g1->is_obj_dead(obj, this) &&
912 !_offsets.verify_for_object(p, obj_size)) {
913 *failures = true;
914 return;
915 }
916
917 if (!g1->is_obj_dead_cond(obj, this, vo)) {
918 if (obj->is_oop()) {
919 Klass* klass = obj->klass();
920 bool is_metaspace_object = Metaspace::contains(klass) ||
921 (vo == VerifyOption_G1UsePrevMarking &&
922 ClassLoaderDataGraph::unload_list_contains(klass));
923 if (!is_metaspace_object) {
924 gclog_or_tty->print_cr("klass "PTR_FORMAT" of object "PTR_FORMAT" "
925 "not metadata", klass, (void *)obj);
926 *failures = true;
927 return;
928 } else if (!klass->is_klass()) {
929 gclog_or_tty->print_cr("klass "PTR_FORMAT" of object "PTR_FORMAT" "
930 "not a klass", klass, (void *)obj);
931 *failures = true;
932 return;
933 } else {
934 vl_cl.set_containing_obj(obj);
935 obj->oop_iterate_no_header(&vl_cl);
936 if (vl_cl.failures()) {
937 *failures = true;
938 }
939 if (G1MaxVerifyFailures >= 0 &&
940 vl_cl.n_failures() >= G1MaxVerifyFailures) {
941 return;
942 }
943 }
944 } else {
945 gclog_or_tty->print_cr(PTR_FORMAT" no an oop", (void *)obj);
946 *failures = true;
947 return;
948 }
949 }
950 prev_p = p;
951 p += obj_size;
952 }
953
954 if (p != top()) {
955 gclog_or_tty->print_cr("end of last object "PTR_FORMAT" "
956 "does not match top "PTR_FORMAT, p, top());
957 *failures = true;
958 return;
959 }
960
961 HeapWord* the_end = end();
962 assert(p == top(), "it should still hold");
963 // Do some extra BOT consistency checking for addresses in the
964 // range [top, end). BOT look-ups in this range should yield
965 // top. No point in doing that if top == end (there's nothing there).
966 if (p < the_end) {
967 // Look up top
968 HeapWord* addr_1 = p;
969 HeapWord* b_start_1 = _offsets.block_start_const(addr_1);
970 if (b_start_1 != p) {
971 gclog_or_tty->print_cr("BOT look up for top: "PTR_FORMAT" "
972 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
973 addr_1, b_start_1, p);
974 *failures = true;
975 return;
976 }
977
978 // Look up top + 1
979 HeapWord* addr_2 = p + 1;
980 if (addr_2 < the_end) {
981 HeapWord* b_start_2 = _offsets.block_start_const(addr_2);
982 if (b_start_2 != p) {
983 gclog_or_tty->print_cr("BOT look up for top + 1: "PTR_FORMAT" "
984 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
985 addr_2, b_start_2, p);
986 *failures = true;
987 return;
988 }
989 }
990
991 // Look up an address between top and end
992 size_t diff = pointer_delta(the_end, p) / 2;
993 HeapWord* addr_3 = p + diff;
994 if (addr_3 < the_end) {
995 HeapWord* b_start_3 = _offsets.block_start_const(addr_3);
996 if (b_start_3 != p) {
997 gclog_or_tty->print_cr("BOT look up for top + diff: "PTR_FORMAT" "
998 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
999 addr_3, b_start_3, p);
1000 *failures = true;
1001 return;
1002 }
1003 }
1004
1005 // Look up end - 1
1006 HeapWord* addr_4 = the_end - 1;
1007 HeapWord* b_start_4 = _offsets.block_start_const(addr_4);
1008 if (b_start_4 != p) {
1009 gclog_or_tty->print_cr("BOT look up for end - 1: "PTR_FORMAT" "
1010 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
1011 addr_4, b_start_4, p);
1012 *failures = true;
1013 return;
1014 }
1015 }
1016
1017 if (is_humongous && object_num > 1) {
1018 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] is humongous "
1019 "but has "SIZE_FORMAT", objects",
1020 bottom(), end(), object_num);
1021 *failures = true;
1022 return;
1023 }
1024
1025 verify_strong_code_roots(vo, failures);
1026 }
1027
1028 void HeapRegion::verify() const {
1029 bool dummy = false;
1030 verify(VerifyOption_G1UsePrevMarking, /* failures */ &dummy);
1031 }
1032
1033 // G1OffsetTableContigSpace code; copied from space.cpp. Hope this can go
1034 // away eventually.
1035
1036 void G1OffsetTableContigSpace::clear(bool mangle_space) {
1037 set_top(bottom());
1038 set_saved_mark_word(bottom());
1039 CompactibleSpace::clear(mangle_space);
1040 reset_bot();
1041 }
1042
1043 void G1OffsetTableContigSpace::set_bottom(HeapWord* new_bottom) {
1044 Space::set_bottom(new_bottom);
1045 _offsets.set_bottom(new_bottom);
1046 }
1047
1048 void G1OffsetTableContigSpace::set_end(HeapWord* new_end) {
1049 Space::set_end(new_end);
1050 _offsets.resize(new_end - bottom());
1051 }
1052
1053 void G1OffsetTableContigSpace::print() const {
1054 print_short();
1055 gclog_or_tty->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", "
1056 INTPTR_FORMAT ", " INTPTR_FORMAT ")",
1057 bottom(), top(), _offsets.threshold(), end());
1058 }
1059
1060 HeapWord* G1OffsetTableContigSpace::initialize_threshold() {
1061 return _offsets.initialize_threshold();
1062 }
1063
1064 HeapWord* G1OffsetTableContigSpace::cross_threshold(HeapWord* start,
1065 HeapWord* end) {
1066 _offsets.alloc_block(start, end);
1067 return _offsets.threshold();
1068 }
1069
1070 HeapWord* G1OffsetTableContigSpace::saved_mark_word() const {
1071 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1072 assert( _gc_time_stamp <= g1h->get_gc_time_stamp(), "invariant" );
1073 if (_gc_time_stamp < g1h->get_gc_time_stamp())
1074 return top();
1075 else
1076 return Space::saved_mark_word();
1077 }
1078
1079 void G1OffsetTableContigSpace::record_top_and_timestamp() {
1080 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1081 unsigned curr_gc_time_stamp = g1h->get_gc_time_stamp();
1082
1083 if (_gc_time_stamp < curr_gc_time_stamp) {
1084 // The order of these is important, as another thread might be
1085 // about to start scanning this region. If it does so after
1086 // set_saved_mark and before _gc_time_stamp = ..., then the latter
1087 // will be false, and it will pick up top() as the high water mark
1088 // of region. If it does so after _gc_time_stamp = ..., then it
1089 // will pick up the right saved_mark_word() as the high water mark
1090 // of the region. Either way, the behavior will be correct.
1091 Space::set_saved_mark_word(top());
1092 OrderAccess::storestore();
1093 _gc_time_stamp = curr_gc_time_stamp;
1094 // No need to do another barrier to flush the writes above. If
1095 // this is called in parallel with other threads trying to
1096 // allocate into the region, the caller should call this while
1097 // holding a lock and when the lock is released the writes will be
1098 // flushed.
1099 }
1100 }
1101
1102 void G1OffsetTableContigSpace::safe_object_iterate(ObjectClosure* blk) {
1103 object_iterate(blk);
1104 }
1105
1106 void G1OffsetTableContigSpace::object_iterate(ObjectClosure* blk) {
1107 HeapWord* p = bottom();
1108 while (p < top()) {
1109 if (block_is_obj(p)) {
1110 blk->do_object(oop(p));
1111 }
1112 p += block_size(p);
1113 }
1114 }
1115
1116 #define block_is_always_obj(q) true
1117 void G1OffsetTableContigSpace::prepare_for_compaction(CompactPoint* cp) {
1118 SCAN_AND_FORWARD(cp, top, block_is_always_obj, block_size);
1119 }
1120 #undef block_is_always_obj
1121
1122 G1OffsetTableContigSpace::
1123 G1OffsetTableContigSpace(G1BlockOffsetSharedArray* sharedOffsetArray,
1124 MemRegion mr) :
1125 _offsets(sharedOffsetArray, mr),
1126 _par_alloc_lock(Mutex::leaf, "OffsetTableContigSpace par alloc lock", true),
1127 _gc_time_stamp(0)
1128 {
1129 _offsets.set_space(this);
1130 }
1131
1132 void G1OffsetTableContigSpace::initialize(MemRegion mr, bool clear_space, bool mangle_space) {
1133 CompactibleSpace::initialize(mr, clear_space, mangle_space);
1134 _top = bottom();
1135 reset_bot();
1136 }
1137