1 /*
2 * Copyright (c) 2001, 2012, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "code/nmethod.hpp"
27 #include "gc_implementation/g1/g1BlockOffsetTable.inline.hpp"
28 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
29 #include "gc_implementation/g1/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 void HeapRegion::setup_heap_region_size(uintx min_heap_size) {
153 // region_size in bytes
154 uintx region_size = G1HeapRegionSize;
155 if (FLAG_IS_DEFAULT(G1HeapRegionSize)) {
156 // We base the automatic calculation on the min heap size. This
157 // can be problematic if the spread between min and max is quite
158 // wide, imagine -Xms128m -Xmx32g. But, if we decided it based on
159 // the max size, the region size might be way too large for the
160 // min size. Either way, some users might have to set the region
161 // size manually for some -Xms / -Xmx combos.
162
163 region_size = MAX2(min_heap_size / TARGET_REGION_NUMBER,
164 (uintx) MIN_REGION_SIZE);
165 }
166
167 int region_size_log = log2_long((jlong) region_size);
168 // Recalculate the region size to make sure it's a power of
169 // 2. This means that region_size is the largest power of 2 that's
170 // <= what we've calculated so far.
171 region_size = ((uintx)1 << region_size_log);
172
173 // Now make sure that we don't go over or under our limits.
174 if (region_size < MIN_REGION_SIZE) {
175 region_size = MIN_REGION_SIZE;
176 } else if (region_size > MAX_REGION_SIZE) {
177 region_size = MAX_REGION_SIZE;
178 }
179
180 if (region_size != G1HeapRegionSize) {
181 // Update the flag to make sure that PrintFlagsFinal logs the correct value
182 FLAG_SET_ERGO(uintx, G1HeapRegionSize, region_size);
183 }
184
185 // And recalculate the log.
186 region_size_log = log2_long((jlong) region_size);
187
188 // Now, set up the globals.
189 guarantee(LogOfHRGrainBytes == 0, "we should only set it once");
190 LogOfHRGrainBytes = region_size_log;
191
192 guarantee(LogOfHRGrainWords == 0, "we should only set it once");
193 LogOfHRGrainWords = LogOfHRGrainBytes - LogHeapWordSize;
194
195 guarantee(GrainBytes == 0, "we should only set it once");
196 // The cast to int is safe, given that we've bounded region_size by
197 // MIN_REGION_SIZE and MAX_REGION_SIZE.
198 GrainBytes = (size_t)region_size;
199
200 guarantee(GrainWords == 0, "we should only set it once");
201 GrainWords = GrainBytes >> LogHeapWordSize;
202 guarantee((size_t) 1 << LogOfHRGrainWords == GrainWords, "sanity");
203
204 guarantee(CardsPerRegion == 0, "we should only set it once");
205 CardsPerRegion = GrainBytes >> CardTableModRefBS::card_shift;
206 }
207
208 void HeapRegion::reset_after_compaction() {
209 G1OffsetTableContigSpace::reset_after_compaction();
210 // After a compaction the mark bitmap is invalid, so we must
211 // treat all objects as being inside the unmarked area.
212 zero_marked_bytes();
213 init_top_at_mark_start();
214 }
215
216 void HeapRegion::hr_clear(bool par, bool clear_space) {
217 assert(_humongous_type == NotHumongous,
218 "we should have already filtered out humongous regions");
219 assert(_humongous_start_region == NULL,
220 "we should have already filtered out humongous regions");
221 assert(_end == _orig_end,
222 "we should have already filtered out humongous regions");
223
224 _in_collection_set = false;
225
226 set_young_index_in_cset(-1);
227 uninstall_surv_rate_group();
228 set_young_type(NotYoung);
229 reset_pre_dummy_top();
230
231 if (!par) {
232 // If this is parallel, this will be done later.
233 HeapRegionRemSet* hrrs = rem_set();
234 hrrs->clear();
235 _claimed = InitialClaimValue;
236 }
237 zero_marked_bytes();
238
239 _offsets.resize(HeapRegion::GrainWords);
240 init_top_at_mark_start();
241 if (clear_space) clear(SpaceDecorator::Mangle);
242 }
243
244 void HeapRegion::par_clear() {
245 assert(used() == 0, "the region should have been already cleared");
246 assert(capacity() == HeapRegion::GrainBytes, "should be back to normal");
247 HeapRegionRemSet* hrrs = rem_set();
248 hrrs->clear();
249 CardTableModRefBS* ct_bs =
250 (CardTableModRefBS*)G1CollectedHeap::heap()->barrier_set();
251 ct_bs->clear(MemRegion(bottom(), end()));
252 }
253
254 void HeapRegion::calc_gc_efficiency() {
255 // GC efficiency is the ratio of how much space would be
256 // reclaimed over how long we predict it would take to reclaim it.
257 G1CollectedHeap* g1h = G1CollectedHeap::heap();
258 G1CollectorPolicy* g1p = g1h->g1_policy();
259
260 // Retrieve a prediction of the elapsed time for this region for
261 // a mixed gc because the region will only be evacuated during a
262 // mixed gc.
263 double region_elapsed_time_ms =
264 g1p->predict_region_elapsed_time_ms(this, false /* for_young_gc */);
265 _gc_efficiency = (double) reclaimable_bytes() / region_elapsed_time_ms;
266 }
267
268 void HeapRegion::set_startsHumongous(HeapWord* new_top, HeapWord* new_end) {
269 assert(!isHumongous(), "sanity / pre-condition");
270 assert(end() == _orig_end,
271 "Should be normal before the humongous object allocation");
272 assert(top() == bottom(), "should be empty");
273 assert(bottom() <= new_top && new_top <= new_end, "pre-condition");
274
275 _humongous_type = StartsHumongous;
276 _humongous_start_region = this;
277
278 set_end(new_end);
279 _offsets.set_for_starts_humongous(new_top);
280 }
281
282 void HeapRegion::set_continuesHumongous(HeapRegion* first_hr) {
283 assert(!isHumongous(), "sanity / pre-condition");
284 assert(end() == _orig_end,
285 "Should be normal before the humongous object allocation");
286 assert(top() == bottom(), "should be empty");
287 assert(first_hr->startsHumongous(), "pre-condition");
288
289 _humongous_type = ContinuesHumongous;
290 _humongous_start_region = first_hr;
291 }
292
293 void HeapRegion::set_notHumongous() {
294 assert(isHumongous(), "pre-condition");
295
296 if (startsHumongous()) {
297 assert(top() <= end(), "pre-condition");
298 set_end(_orig_end);
299 if (top() > end()) {
300 // at least one "continues humongous" region after it
301 set_top(end());
302 }
303 } else {
304 // continues humongous
305 assert(end() == _orig_end, "sanity");
306 }
307
308 assert(capacity() == HeapRegion::GrainBytes, "pre-condition");
309 _humongous_type = NotHumongous;
310 _humongous_start_region = NULL;
311 }
312
313 bool HeapRegion::claimHeapRegion(jint claimValue) {
314 jint current = _claimed;
315 if (current != claimValue) {
316 jint res = Atomic::cmpxchg(claimValue, &_claimed, current);
317 if (res == current) {
318 return true;
319 }
320 }
321 return false;
322 }
323
324 HeapWord* HeapRegion::next_block_start_careful(HeapWord* addr) {
325 HeapWord* low = addr;
326 HeapWord* high = end();
327 while (low < high) {
328 size_t diff = pointer_delta(high, low);
329 // Must add one below to bias toward the high amount. Otherwise, if
330 // "high" were at the desired value, and "low" were one less, we
331 // would not converge on "high". This is not symmetric, because
332 // we set "high" to a block start, which might be the right one,
333 // which we don't do for "low".
334 HeapWord* middle = low + (diff+1)/2;
335 if (middle == high) return high;
336 HeapWord* mid_bs = block_start_careful(middle);
337 if (mid_bs < addr) {
338 low = middle;
339 } else {
340 high = mid_bs;
341 }
342 }
343 assert(low == high && low >= addr, "Didn't work.");
344 return low;
345 }
346
347 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
348 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
349 #endif // _MSC_VER
350
351
352 HeapRegion::HeapRegion(uint hrs_index,
353 G1BlockOffsetSharedArray* sharedOffsetArray,
354 MemRegion mr) :
355 G1OffsetTableContigSpace(sharedOffsetArray, mr),
356 _hrs_index(hrs_index),
357 _humongous_type(NotHumongous), _humongous_start_region(NULL),
358 _in_collection_set(false),
359 _next_in_special_set(NULL), _orig_end(NULL),
360 _claimed(InitialClaimValue), _evacuation_failed(false),
361 _prev_marked_bytes(0), _next_marked_bytes(0), _gc_efficiency(0.0),
362 _young_type(NotYoung), _next_young_region(NULL),
363 _next_dirty_cards_region(NULL), _next(NULL), _pending_removal(false),
364 #ifdef ASSERT
365 _containing_set(NULL),
366 #endif // ASSERT
367 _young_index_in_cset(-1), _surv_rate_group(NULL), _age_index(-1),
368 _rem_set(NULL), _recorded_rs_length(0), _predicted_elapsed_time_ms(0),
369 _predicted_bytes_to_copy(0)
370 {
371 _rem_set = new HeapRegionRemSet(sharedOffsetArray, this);
372 _orig_end = mr.end();
373 // Note that initialize() will set the start of the unmarked area of the
374 // region.
375 hr_clear(false /*par*/, false /*clear_space*/);
376 set_top(bottom());
377 set_saved_mark();
378
379 assert(HeapRegionRemSet::num_par_rem_sets() > 0, "Invariant.");
380 }
381
382 CompactibleSpace* HeapRegion::next_compaction_space() const {
383 // We're not using an iterator given that it will wrap around when
384 // it reaches the last region and this is not what we want here.
385 G1CollectedHeap* g1h = G1CollectedHeap::heap();
386 uint index = hrs_index() + 1;
387 while (index < g1h->n_regions()) {
388 HeapRegion* hr = g1h->region_at(index);
389 if (!hr->isHumongous()) {
390 return hr;
391 }
392 index += 1;
393 }
394 return NULL;
395 }
396
397 void HeapRegion::save_marks() {
398 set_saved_mark();
399 }
400
401 void HeapRegion::oops_in_mr_iterate(MemRegion mr, ExtendedOopClosure* cl) {
402 HeapWord* p = mr.start();
403 HeapWord* e = mr.end();
404 oop obj;
405 while (p < e) {
406 obj = oop(p);
407 p += obj->oop_iterate(cl);
408 }
409 assert(p == e, "bad memregion: doesn't end on obj boundary");
410 }
411
412 #define HeapRegion_OOP_SINCE_SAVE_MARKS_DEFN(OopClosureType, nv_suffix) \
413 void HeapRegion::oop_since_save_marks_iterate##nv_suffix(OopClosureType* cl) { \
414 ContiguousSpace::oop_since_save_marks_iterate##nv_suffix(cl); \
415 }
416 SPECIALIZED_SINCE_SAVE_MARKS_CLOSURES(HeapRegion_OOP_SINCE_SAVE_MARKS_DEFN)
417
418
419 void HeapRegion::oop_before_save_marks_iterate(ExtendedOopClosure* cl) {
420 oops_in_mr_iterate(MemRegion(bottom(), saved_mark_word()), cl);
421 }
422
423 void HeapRegion::note_self_forwarding_removal_start(bool during_initial_mark,
424 bool during_conc_mark) {
425 // We always recreate the prev marking info and we'll explicitly
426 // mark all objects we find to be self-forwarded on the prev
427 // bitmap. So all objects need to be below PTAMS.
428 _prev_top_at_mark_start = top();
429 _prev_marked_bytes = 0;
430
431 if (during_initial_mark) {
432 // During initial-mark, we'll also explicitly mark all objects
433 // we find to be self-forwarded on the next bitmap. So all
434 // objects need to be below NTAMS.
435 _next_top_at_mark_start = top();
436 _next_marked_bytes = 0;
437 } else if (during_conc_mark) {
438 // During concurrent mark, all objects in the CSet (including
439 // the ones we find to be self-forwarded) are implicitly live.
440 // So all objects need to be above NTAMS.
441 _next_top_at_mark_start = bottom();
442 _next_marked_bytes = 0;
443 }
444 }
445
446 void HeapRegion::note_self_forwarding_removal_end(bool during_initial_mark,
447 bool during_conc_mark,
448 size_t marked_bytes) {
449 assert(0 <= marked_bytes && marked_bytes <= used(),
450 err_msg("marked: "SIZE_FORMAT" used: "SIZE_FORMAT,
451 marked_bytes, used()));
452 _prev_marked_bytes = marked_bytes;
453 }
454
455 HeapWord*
456 HeapRegion::object_iterate_mem_careful(MemRegion mr,
457 ObjectClosure* cl) {
458 G1CollectedHeap* g1h = G1CollectedHeap::heap();
459 // We used to use "block_start_careful" here. But we're actually happy
460 // to update the BOT while we do this...
461 HeapWord* cur = block_start(mr.start());
462 mr = mr.intersection(used_region());
463 if (mr.is_empty()) return NULL;
464 // Otherwise, find the obj that extends onto mr.start().
465
466 assert(cur <= mr.start()
467 && (oop(cur)->klass_or_null() == NULL ||
468 cur + oop(cur)->size() > mr.start()),
469 "postcondition of block_start");
470 oop obj;
471 while (cur < mr.end()) {
472 obj = oop(cur);
473 if (obj->klass_or_null() == NULL) {
474 // Ran into an unparseable point.
475 return cur;
476 } else if (!g1h->is_obj_dead(obj)) {
477 cl->do_object(obj);
478 }
479 if (cl->abort()) return cur;
480 // The check above must occur before the operation below, since an
481 // abort might invalidate the "size" operation.
482 cur += obj->size();
483 }
484 return NULL;
485 }
486
487 HeapWord*
488 HeapRegion::
489 oops_on_card_seq_iterate_careful(MemRegion mr,
490 FilterOutOfRegionClosure* cl,
491 bool filter_young,
492 jbyte* card_ptr) {
493 // Currently, we should only have to clean the card if filter_young
494 // is true and vice versa.
495 if (filter_young) {
496 assert(card_ptr != NULL, "pre-condition");
497 } else {
498 assert(card_ptr == NULL, "pre-condition");
499 }
500 G1CollectedHeap* g1h = G1CollectedHeap::heap();
501
502 // If we're within a stop-world GC, then we might look at a card in a
503 // GC alloc region that extends onto a GC LAB, which may not be
504 // parseable. Stop such at the "saved_mark" of the region.
505 if (g1h->is_gc_active()) {
506 mr = mr.intersection(used_region_at_save_marks());
507 } else {
508 mr = mr.intersection(used_region());
509 }
510 if (mr.is_empty()) return NULL;
511 // Otherwise, find the obj that extends onto mr.start().
512
513 // The intersection of the incoming mr (for the card) and the
514 // allocated part of the region is non-empty. This implies that
515 // we have actually allocated into this region. The code in
516 // G1CollectedHeap.cpp that allocates a new region sets the
517 // is_young tag on the region before allocating. Thus we
518 // safely know if this region is young.
519 if (is_young() && filter_young) {
520 return NULL;
521 }
522
523 assert(!is_young(), "check value of filter_young");
524
525 // We can only clean the card here, after we make the decision that
526 // the card is not young. And we only clean the card if we have been
527 // asked to (i.e., card_ptr != NULL).
528 if (card_ptr != NULL) {
529 *card_ptr = CardTableModRefBS::clean_card_val();
530 // We must complete this write before we do any of the reads below.
531 OrderAccess::storeload();
532 }
533
534 // Cache the boundaries of the memory region in some const locals
535 HeapWord* const start = mr.start();
536 HeapWord* const end = mr.end();
537
538 // We used to use "block_start_careful" here. But we're actually happy
539 // to update the BOT while we do this...
540 HeapWord* cur = block_start(start);
541 assert(cur <= start, "Postcondition");
542
543 oop obj;
544
545 HeapWord* next = cur;
546 while (next <= start) {
547 cur = next;
548 obj = oop(cur);
549 if (obj->klass_or_null() == NULL) {
550 // Ran into an unparseable point.
551 return cur;
552 }
553 // Otherwise...
554 next = (cur + obj->size());
555 }
556
557 // If we finish the above loop...We have a parseable object that
558 // begins on or before the start of the memory region, and ends
559 // inside or spans the entire region.
560
561 assert(obj == oop(cur), "sanity");
562 assert(cur <= start &&
563 obj->klass_or_null() != NULL &&
564 (cur + obj->size()) > start,
565 "Loop postcondition");
566
567 if (!g1h->is_obj_dead(obj)) {
568 obj->oop_iterate(cl, mr);
569 }
570
571 while (cur < end) {
572 obj = oop(cur);
573 if (obj->klass_or_null() == NULL) {
574 // Ran into an unparseable point.
575 return cur;
576 };
577
578 // Otherwise:
579 next = (cur + obj->size());
580
581 if (!g1h->is_obj_dead(obj)) {
582 if (next < end || !obj->is_objArray()) {
583 // This object either does not span the MemRegion
584 // boundary, or if it does it's not an array.
585 // Apply closure to whole object.
586 obj->oop_iterate(cl);
587 } else {
588 // This obj is an array that spans the boundary.
589 // Stop at the boundary.
590 obj->oop_iterate(cl, mr);
591 }
592 }
593 cur = next;
594 }
595 return NULL;
596 }
597
598 // Code roots support
599
600 void HeapRegion::add_strong_code_root(nmethod* nm) {
601 HeapRegionRemSet* hrrs = rem_set();
602 hrrs->add_strong_code_root(nm);
603 }
604
605 void HeapRegion::remove_strong_code_root(nmethod* nm) {
606 HeapRegionRemSet* hrrs = rem_set();
607 hrrs->remove_strong_code_root(nm);
608 }
609
610 void HeapRegion::migrate_strong_code_roots() {
611 assert(in_collection_set(), "only collection set regions");
612 assert(!isHumongous(), "not humongous regions");
613
614 HeapRegionRemSet* hrrs = rem_set();
615 hrrs->migrate_strong_code_roots();
616 }
617
618 void HeapRegion::strong_code_roots_do(CodeBlobClosure* blk) const {
619 HeapRegionRemSet* hrrs = rem_set();
620 hrrs->strong_code_roots_do(blk);
621 }
622
623 class VerifyStrongCodeRootOopClosure: public OopClosure {
624 const HeapRegion* _hr;
625 nmethod* _nm;
626 bool _failures;
627 bool _has_oops_in_region;
628
629 template <class T> void do_oop_work(T* p) {
630 T heap_oop = oopDesc::load_heap_oop(p);
631 if (!oopDesc::is_null(heap_oop)) {
632 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
633
634 // Note: not all the oops embedded in the nmethod are in the
635 // current region. We only look at those which are.
636 if (_hr->is_in(obj)) {
637 // Object is in the region. Check that its less than top
638 if (_hr->top() <= (HeapWord*)obj) {
639 // Object is above top
640 gclog_or_tty->print_cr("Object "PTR_FORMAT" in region "
641 "["PTR_FORMAT", "PTR_FORMAT") is above "
642 "top "PTR_FORMAT,
643 obj, _hr->bottom(), _hr->end(), _hr->top());
644 _failures = true;
645 return;
646 }
647 // Nmethod has at least one oop in the current region
648 _has_oops_in_region = true;
649 }
650 }
651 }
652
653 public:
654 VerifyStrongCodeRootOopClosure(const HeapRegion* hr, nmethod* nm):
655 _hr(hr), _failures(false), _has_oops_in_region(false) {}
656
657 void do_oop(narrowOop* p) { do_oop_work(p); }
658 void do_oop(oop* p) { do_oop_work(p); }
659
660 bool failures() { return _failures; }
661 bool has_oops_in_region() { return _has_oops_in_region; }
662 };
663
664 class VerifyStrongCodeRootCodeBlobClosure: public CodeBlobClosure {
665 const HeapRegion* _hr;
666 bool _failures;
667 public:
668 VerifyStrongCodeRootCodeBlobClosure(const HeapRegion* hr) :
669 _hr(hr), _failures(false) {}
670
671 void do_code_blob(CodeBlob* cb) {
672 nmethod* nm = (cb == NULL) ? NULL : cb->as_nmethod_or_null();
673 if (nm != NULL) {
674 // Verify that the nemthod is live
675 if (!nm->is_alive()) {
676 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] has dead nmethod "
677 PTR_FORMAT" in its strong code roots",
678 _hr->bottom(), _hr->end(), nm);
679 _failures = true;
680 } else {
681 VerifyStrongCodeRootOopClosure oop_cl(_hr, nm);
682 nm->oops_do(&oop_cl);
683 if (!oop_cl.has_oops_in_region()) {
684 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] has nmethod "
685 PTR_FORMAT" in its strong code roots "
686 "with no pointers into region",
687 _hr->bottom(), _hr->end(), nm);
688 _failures = true;
689 } else if (oop_cl.failures()) {
690 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] has other "
691 "failures for nmethod "PTR_FORMAT,
692 _hr->bottom(), _hr->end(), nm);
693 _failures = true;
694 }
695 }
696 }
697 }
698
699 bool failures() { return _failures; }
700 };
701
702 void HeapRegion::verify_strong_code_roots(VerifyOption vo, bool* failures) const {
703 if (!G1VerifyHeapRegionCodeRoots) {
704 // We're not verifying code roots.
705 return;
706 }
707 if (vo == VerifyOption_G1UseMarkWord) {
708 // Marking verification during a full GC is performed after class
709 // unloading, code cache unloading, etc so the strong code roots
710 // attached to each heap region are in an inconsistent state. They won't
711 // be consistent until the strong code roots are rebuilt after the
712 // actual GC. Skip verifying the strong code roots in this particular
713 // time.
714 assert(VerifyDuringGC, "only way to get here");
715 return;
716 }
717
718 HeapRegionRemSet* hrrs = rem_set();
719 int strong_code_roots_length = hrrs->strong_code_roots_list_length();
720
721 // if this region is empty then there should be no entries
722 // on its strong code root list
723 if (is_empty()) {
724 if (strong_code_roots_length > 0) {
725 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] is empty "
726 "but has "INT32_FORMAT" code root entries",
727 bottom(), end(), strong_code_roots_length);
728 *failures = true;
729 }
730 return;
731 }
732
733 // An H-region should have an empty strong code root list
734 if (isHumongous()) {
735 if (strong_code_roots_length > 0) {
736 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] is humongous "
737 "but has "INT32_FORMAT" code root entries",
738 bottom(), end(), strong_code_roots_length);
739 *failures = true;
740 }
741 return;
742 }
743
744 VerifyStrongCodeRootCodeBlobClosure cb_cl(this);
745 strong_code_roots_do(&cb_cl);
746
747 if (cb_cl.failures()) {
748 *failures = true;
749 }
750 }
751
752 void HeapRegion::print() const { print_on(gclog_or_tty); }
753 void HeapRegion::print_on(outputStream* st) const {
754 if (isHumongous()) {
755 if (startsHumongous())
756 st->print(" HS");
757 else
758 st->print(" HC");
759 } else {
760 st->print(" ");
761 }
762 if (in_collection_set())
763 st->print(" CS");
764 else
765 st->print(" ");
766 if (is_young())
767 st->print(is_survivor() ? " SU" : " Y ");
768 else
769 st->print(" ");
770 if (is_empty())
771 st->print(" F");
772 else
773 st->print(" ");
774 st->print(" TS %5d", _gc_time_stamp);
775 st->print(" PTAMS "PTR_FORMAT" NTAMS "PTR_FORMAT,
776 prev_top_at_mark_start(), next_top_at_mark_start());
777 G1OffsetTableContigSpace::print_on(st);
778 }
779
780 class VerifyLiveClosure: public OopClosure {
781 private:
782 G1CollectedHeap* _g1h;
783 CardTableModRefBS* _bs;
784 oop _containing_obj;
785 bool _failures;
786 int _n_failures;
787 VerifyOption _vo;
788 public:
789 // _vo == UsePrevMarking -> use "prev" marking information,
790 // _vo == UseNextMarking -> use "next" marking information,
791 // _vo == UseMarkWord -> use mark word from object header.
792 VerifyLiveClosure(G1CollectedHeap* g1h, VerifyOption vo) :
793 _g1h(g1h), _bs(NULL), _containing_obj(NULL),
794 _failures(false), _n_failures(0), _vo(vo)
795 {
796 BarrierSet* bs = _g1h->barrier_set();
797 if (bs->is_a(BarrierSet::CardTableModRef))
798 _bs = (CardTableModRefBS*)bs;
799 }
800
801 void set_containing_obj(oop obj) {
802 _containing_obj = obj;
803 }
804
805 bool failures() { return _failures; }
806 int n_failures() { return _n_failures; }
807
808 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
809 virtual void do_oop( oop* p) { do_oop_work(p); }
810
811 void print_object(outputStream* out, oop obj) {
812 #ifdef PRODUCT
813 Klass* k = obj->klass();
814 const char* class_name = InstanceKlass::cast(k)->external_name();
815 out->print_cr("class name %s", class_name);
816 #else // PRODUCT
817 obj->print_on(out);
818 #endif // PRODUCT
819 }
820
821 template <class T>
822 void do_oop_work(T* p) {
823 assert(_containing_obj != NULL, "Precondition");
824 assert(!_g1h->is_obj_dead_cond(_containing_obj, _vo),
825 "Precondition");
826 T heap_oop = oopDesc::load_heap_oop(p);
827 if (!oopDesc::is_null(heap_oop)) {
828 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
829 bool failed = false;
830 if (!_g1h->is_in_closed_subset(obj) || _g1h->is_obj_dead_cond(obj, _vo)) {
831 MutexLockerEx x(ParGCRareEvent_lock,
832 Mutex::_no_safepoint_check_flag);
833
834 if (!_failures) {
835 gclog_or_tty->print_cr("");
836 gclog_or_tty->print_cr("----------");
837 }
838 if (!_g1h->is_in_closed_subset(obj)) {
839 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
840 gclog_or_tty->print_cr("Field "PTR_FORMAT
841 " of live obj "PTR_FORMAT" in region "
842 "["PTR_FORMAT", "PTR_FORMAT")",
843 p, (void*) _containing_obj,
844 from->bottom(), from->end());
845 print_object(gclog_or_tty, _containing_obj);
846 gclog_or_tty->print_cr("points to obj "PTR_FORMAT" not in the heap",
847 (void*) obj);
848 } else {
849 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
850 HeapRegion* to = _g1h->heap_region_containing((HeapWord*)obj);
851 gclog_or_tty->print_cr("Field "PTR_FORMAT
852 " of live obj "PTR_FORMAT" in region "
853 "["PTR_FORMAT", "PTR_FORMAT")",
854 p, (void*) _containing_obj,
855 from->bottom(), from->end());
856 print_object(gclog_or_tty, _containing_obj);
857 gclog_or_tty->print_cr("points to dead obj "PTR_FORMAT" in region "
858 "["PTR_FORMAT", "PTR_FORMAT")",
859 (void*) obj, to->bottom(), to->end());
860 print_object(gclog_or_tty, obj);
861 }
862 gclog_or_tty->print_cr("----------");
863 gclog_or_tty->flush();
864 _failures = true;
865 failed = true;
866 _n_failures++;
867 }
868
869 if (!_g1h->full_collection() || G1VerifyRSetsDuringFullGC) {
870 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
871 HeapRegion* to = _g1h->heap_region_containing(obj);
872 if (from != NULL && to != NULL &&
873 from != to &&
874 !to->isHumongous()) {
875 jbyte cv_obj = *_bs->byte_for_const(_containing_obj);
876 jbyte cv_field = *_bs->byte_for_const(p);
877 const jbyte dirty = CardTableModRefBS::dirty_card_val();
878
879 bool is_bad = !(from->is_young()
880 || to->rem_set()->contains_reference(p)
881 || !G1HRRSFlushLogBuffersOnVerify && // buffers were not flushed
882 (_containing_obj->is_objArray() ?
883 cv_field == dirty
884 : cv_obj == dirty || cv_field == dirty));
885 if (is_bad) {
886 MutexLockerEx x(ParGCRareEvent_lock,
887 Mutex::_no_safepoint_check_flag);
888
889 if (!_failures) {
890 gclog_or_tty->print_cr("");
891 gclog_or_tty->print_cr("----------");
892 }
893 gclog_or_tty->print_cr("Missing rem set entry:");
894 gclog_or_tty->print_cr("Field "PTR_FORMAT" "
895 "of obj "PTR_FORMAT", "
896 "in region "HR_FORMAT,
897 p, (void*) _containing_obj,
898 HR_FORMAT_PARAMS(from));
899 _containing_obj->print_on(gclog_or_tty);
900 gclog_or_tty->print_cr("points to obj "PTR_FORMAT" "
901 "in region "HR_FORMAT,
902 (void*) obj,
903 HR_FORMAT_PARAMS(to));
904 obj->print_on(gclog_or_tty);
905 gclog_or_tty->print_cr("Obj head CTE = %d, field CTE = %d.",
906 cv_obj, cv_field);
907 gclog_or_tty->print_cr("----------");
908 gclog_or_tty->flush();
909 _failures = true;
910 if (!failed) _n_failures++;
911 }
912 }
913 }
914 }
915 }
916 };
917
918 // This really ought to be commoned up into OffsetTableContigSpace somehow.
919 // We would need a mechanism to make that code skip dead objects.
920
921 void HeapRegion::verify(VerifyOption vo,
922 bool* failures) const {
923 G1CollectedHeap* g1 = G1CollectedHeap::heap();
924 *failures = false;
925 HeapWord* p = bottom();
926 HeapWord* prev_p = NULL;
927 VerifyLiveClosure vl_cl(g1, vo);
928 bool is_humongous = isHumongous();
929 bool do_bot_verify = !is_young();
930 size_t object_num = 0;
931 while (p < top()) {
932 oop obj = oop(p);
933 size_t obj_size = obj->size();
934 object_num += 1;
935
936 if (is_humongous != g1->isHumongous(obj_size)) {
937 gclog_or_tty->print_cr("obj "PTR_FORMAT" is of %shumongous size ("
938 SIZE_FORMAT" words) in a %shumongous region",
939 p, g1->isHumongous(obj_size) ? "" : "non-",
940 obj_size, is_humongous ? "" : "non-");
941 *failures = true;
942 return;
943 }
944
945 // If it returns false, verify_for_object() will output the
946 // appropriate messasge.
947 if (do_bot_verify && !_offsets.verify_for_object(p, obj_size)) {
948 *failures = true;
949 return;
950 }
951
952 if (!g1->is_obj_dead_cond(obj, this, vo)) {
953 if (obj->is_oop()) {
954 Klass* klass = obj->klass();
955 if (!klass->is_metaspace_object()) {
956 gclog_or_tty->print_cr("klass "PTR_FORMAT" of object "PTR_FORMAT" "
957 "not metadata", klass, obj);
958 *failures = true;
959 return;
960 } else if (!klass->is_klass()) {
961 gclog_or_tty->print_cr("klass "PTR_FORMAT" of object "PTR_FORMAT" "
962 "not a klass", klass, obj);
963 *failures = true;
964 return;
965 } else {
966 vl_cl.set_containing_obj(obj);
967 obj->oop_iterate_no_header(&vl_cl);
968 if (vl_cl.failures()) {
969 *failures = true;
970 }
971 if (G1MaxVerifyFailures >= 0 &&
972 vl_cl.n_failures() >= G1MaxVerifyFailures) {
973 return;
974 }
975 }
976 } else {
977 gclog_or_tty->print_cr(PTR_FORMAT" no an oop", obj);
978 *failures = true;
979 return;
980 }
981 }
982 prev_p = p;
983 p += obj_size;
984 }
985
986 if (p != top()) {
987 gclog_or_tty->print_cr("end of last object "PTR_FORMAT" "
988 "does not match top "PTR_FORMAT, p, top());
989 *failures = true;
990 return;
991 }
992
993 HeapWord* the_end = end();
994 assert(p == top(), "it should still hold");
995 // Do some extra BOT consistency checking for addresses in the
996 // range [top, end). BOT look-ups in this range should yield
997 // top. No point in doing that if top == end (there's nothing there).
998 if (p < the_end) {
999 // Look up top
1000 HeapWord* addr_1 = p;
1001 HeapWord* b_start_1 = _offsets.block_start_const(addr_1);
1002 if (b_start_1 != p) {
1003 gclog_or_tty->print_cr("BOT look up for top: "PTR_FORMAT" "
1004 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
1005 addr_1, b_start_1, p);
1006 *failures = true;
1007 return;
1008 }
1009
1010 // Look up top + 1
1011 HeapWord* addr_2 = p + 1;
1012 if (addr_2 < the_end) {
1013 HeapWord* b_start_2 = _offsets.block_start_const(addr_2);
1014 if (b_start_2 != p) {
1015 gclog_or_tty->print_cr("BOT look up for top + 1: "PTR_FORMAT" "
1016 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
1017 addr_2, b_start_2, p);
1018 *failures = true;
1019 return;
1020 }
1021 }
1022
1023 // Look up an address between top and end
1024 size_t diff = pointer_delta(the_end, p) / 2;
1025 HeapWord* addr_3 = p + diff;
1026 if (addr_3 < the_end) {
1027 HeapWord* b_start_3 = _offsets.block_start_const(addr_3);
1028 if (b_start_3 != p) {
1029 gclog_or_tty->print_cr("BOT look up for top + diff: "PTR_FORMAT" "
1030 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
1031 addr_3, b_start_3, p);
1032 *failures = true;
1033 return;
1034 }
1035 }
1036
1037 // Loook up end - 1
1038 HeapWord* addr_4 = the_end - 1;
1039 HeapWord* b_start_4 = _offsets.block_start_const(addr_4);
1040 if (b_start_4 != p) {
1041 gclog_or_tty->print_cr("BOT look up for end - 1: "PTR_FORMAT" "
1042 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
1043 addr_4, b_start_4, p);
1044 *failures = true;
1045 return;
1046 }
1047 }
1048
1049 if (is_humongous && object_num > 1) {
1050 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] is humongous "
1051 "but has "SIZE_FORMAT", objects",
1052 bottom(), end(), object_num);
1053 *failures = true;
1054 return;
1055 }
1056
1057 verify_strong_code_roots(vo, failures);
1058 }
1059
1060 void HeapRegion::verify() const {
1061 bool dummy = false;
1062 verify(VerifyOption_G1UsePrevMarking, /* failures */ &dummy);
1063 }
1064
1065 // G1OffsetTableContigSpace code; copied from space.cpp. Hope this can go
1066 // away eventually.
1067
1068 void G1OffsetTableContigSpace::clear(bool mangle_space) {
1069 ContiguousSpace::clear(mangle_space);
1070 _offsets.zero_bottom_entry();
1071 _offsets.initialize_threshold();
1072 }
1073
1074 void G1OffsetTableContigSpace::set_bottom(HeapWord* new_bottom) {
1075 Space::set_bottom(new_bottom);
1076 _offsets.set_bottom(new_bottom);
1077 }
1078
1079 void G1OffsetTableContigSpace::set_end(HeapWord* new_end) {
1080 Space::set_end(new_end);
1081 _offsets.resize(new_end - bottom());
1082 }
1083
1084 void G1OffsetTableContigSpace::print() const {
1085 print_short();
1086 gclog_or_tty->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", "
1087 INTPTR_FORMAT ", " INTPTR_FORMAT ")",
1088 bottom(), top(), _offsets.threshold(), end());
1089 }
1090
1091 HeapWord* G1OffsetTableContigSpace::initialize_threshold() {
1092 return _offsets.initialize_threshold();
1093 }
1094
1095 HeapWord* G1OffsetTableContigSpace::cross_threshold(HeapWord* start,
1096 HeapWord* end) {
1097 _offsets.alloc_block(start, end);
1098 return _offsets.threshold();
1099 }
1100
1101 HeapWord* G1OffsetTableContigSpace::saved_mark_word() const {
1102 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1103 assert( _gc_time_stamp <= g1h->get_gc_time_stamp(), "invariant" );
1104 if (_gc_time_stamp < g1h->get_gc_time_stamp())
1105 return top();
1106 else
1107 return ContiguousSpace::saved_mark_word();
1108 }
1109
1110 void G1OffsetTableContigSpace::set_saved_mark() {
1111 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1112 unsigned curr_gc_time_stamp = g1h->get_gc_time_stamp();
1113
1114 if (_gc_time_stamp < curr_gc_time_stamp) {
1115 // The order of these is important, as another thread might be
1116 // about to start scanning this region. If it does so after
1117 // set_saved_mark and before _gc_time_stamp = ..., then the latter
1118 // will be false, and it will pick up top() as the high water mark
1119 // of region. If it does so after _gc_time_stamp = ..., then it
1120 // will pick up the right saved_mark_word() as the high water mark
1121 // of the region. Either way, the behaviour will be correct.
1122 ContiguousSpace::set_saved_mark();
1123 OrderAccess::storestore();
1124 _gc_time_stamp = curr_gc_time_stamp;
1125 // No need to do another barrier to flush the writes above. If
1126 // this is called in parallel with other threads trying to
1127 // allocate into the region, the caller should call this while
1128 // holding a lock and when the lock is released the writes will be
1129 // flushed.
1130 }
1131 }
1132
1133 G1OffsetTableContigSpace::
1134 G1OffsetTableContigSpace(G1BlockOffsetSharedArray* sharedOffsetArray,
1135 MemRegion mr) :
1136 _offsets(sharedOffsetArray, mr),
1137 _par_alloc_lock(Mutex::leaf, "OffsetTableContigSpace par alloc lock", true),
1138 _gc_time_stamp(0)
1139 {
1140 _offsets.set_space(this);
1141 // false ==> we'll do the clearing if there's clearing to be done.
1142 ContiguousSpace::initialize(mr, false, SpaceDecorator::Mangle);
1143 _offsets.zero_bottom_entry();
1144 _offsets.initialize_threshold();
1145 }