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/heapRegionBounds.inline.hpp"
32 #include "gc_implementation/g1/heapRegionRemSet.hpp"
33 #include "gc_implementation/g1/heapRegionManager.inline.hpp"
34 #include "gc_implementation/shared/liveRange.hpp"
35 #include "memory/genOopClosures.inline.hpp"
36 #include "memory/iterator.hpp"
37 #include "memory/space.inline.hpp"
38 #include "oops/oop.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 size_t HeapRegion::max_region_size() {
142 return HeapRegionBounds::max_size();
143 }
144
145 void HeapRegion::setup_heap_region_size(size_t initial_heap_size, size_t max_heap_size) {
146 uintx region_size = G1HeapRegionSize;
147 if (FLAG_IS_DEFAULT(G1HeapRegionSize)) {
148 size_t average_heap_size = (initial_heap_size + max_heap_size) / 2;
149 region_size = MAX2(average_heap_size / HeapRegionBounds::target_number(),
150 (uintx) HeapRegionBounds::min_size());
151 }
152
153 int region_size_log = log2_long((jlong) region_size);
154 // Recalculate the region size to make sure it's a power of
155 // 2. This means that region_size is the largest power of 2 that's
156 // <= what we've calculated so far.
157 region_size = ((uintx)1 << region_size_log);
158
159 // Now make sure that we don't go over or under our limits.
160 if (region_size < HeapRegionBounds::min_size()) {
161 region_size = HeapRegionBounds::min_size();
162 } else if (region_size > HeapRegionBounds::max_size()) {
163 region_size = HeapRegionBounds::max_size();
164 }
165
166 // And recalculate the log.
167 region_size_log = log2_long((jlong) region_size);
168
169 // Now, set up the globals.
170 guarantee(LogOfHRGrainBytes == 0, "we should only set it once");
171 LogOfHRGrainBytes = region_size_log;
172
173 guarantee(LogOfHRGrainWords == 0, "we should only set it once");
174 LogOfHRGrainWords = LogOfHRGrainBytes - LogHeapWordSize;
175
176 guarantee(GrainBytes == 0, "we should only set it once");
177 // The cast to int is safe, given that we've bounded region_size by
178 // MIN_REGION_SIZE and MAX_REGION_SIZE.
179 GrainBytes = (size_t)region_size;
180
181 guarantee(GrainWords == 0, "we should only set it once");
182 GrainWords = GrainBytes >> LogHeapWordSize;
183 guarantee((size_t) 1 << LogOfHRGrainWords == GrainWords, "sanity");
184
185 guarantee(CardsPerRegion == 0, "we should only set it once");
186 CardsPerRegion = GrainBytes >> CardTableModRefBS::card_shift;
187 }
188
189 void HeapRegion::reset_after_compaction() {
190 G1OffsetTableContigSpace::reset_after_compaction();
191 // After a compaction the mark bitmap is invalid, so we must
192 // treat all objects as being inside the unmarked area.
193 zero_marked_bytes();
194 init_top_at_mark_start();
195 }
196
197 void HeapRegion::hr_clear(bool par, bool clear_space, bool locked) {
198 assert(_humongous_type == NotHumongous,
199 "we should have already filtered out humongous regions");
200 assert(_humongous_start_region == NULL,
201 "we should have already filtered out humongous regions");
202 assert(_end == _orig_end,
203 "we should have already filtered out humongous regions");
204
205 _in_collection_set = false;
206
207 set_allocation_context(AllocationContext::system());
208 set_young_index_in_cset(-1);
209 uninstall_surv_rate_group();
210 set_young_type(NotYoung);
211 reset_pre_dummy_top();
212
213 if (!par) {
214 // If this is parallel, this will be done later.
215 HeapRegionRemSet* hrrs = rem_set();
216 if (locked) {
217 hrrs->clear_locked();
218 } else {
219 hrrs->clear();
220 }
221 _claimed = InitialClaimValue;
222 }
223 zero_marked_bytes();
224
225 _offsets.resize(HeapRegion::GrainWords);
226 init_top_at_mark_start();
227 if (clear_space) clear(SpaceDecorator::Mangle);
228 }
229
230 void HeapRegion::par_clear() {
231 assert(used() == 0, "the region should have been already cleared");
232 assert(capacity() == HeapRegion::GrainBytes, "should be back to normal");
233 HeapRegionRemSet* hrrs = rem_set();
234 hrrs->clear();
235 CardTableModRefBS* ct_bs =
236 (CardTableModRefBS*)G1CollectedHeap::heap()->barrier_set();
237 ct_bs->clear(MemRegion(bottom(), end()));
238 }
239
240 void HeapRegion::calc_gc_efficiency() {
241 // GC efficiency is the ratio of how much space would be
242 // reclaimed over how long we predict it would take to reclaim it.
243 G1CollectedHeap* g1h = G1CollectedHeap::heap();
244 G1CollectorPolicy* g1p = g1h->g1_policy();
245
246 // Retrieve a prediction of the elapsed time for this region for
247 // a mixed gc because the region will only be evacuated during a
248 // mixed gc.
249 double region_elapsed_time_ms =
250 g1p->predict_region_elapsed_time_ms(this, false /* for_young_gc */);
251 _gc_efficiency = (double) reclaimable_bytes() / region_elapsed_time_ms;
252 }
253
254 void HeapRegion::set_startsHumongous(HeapWord* new_top, HeapWord* new_end) {
255 assert(!isHumongous(), "sanity / pre-condition");
256 assert(end() == _orig_end,
257 "Should be normal before the humongous object allocation");
258 assert(top() == bottom(), "should be empty");
259 assert(bottom() <= new_top && new_top <= new_end, "pre-condition");
260
261 _humongous_type = StartsHumongous;
262 _humongous_start_region = this;
263
264 set_end(new_end);
265 _offsets.set_for_starts_humongous(new_top);
266 }
267
268 void HeapRegion::set_continuesHumongous(HeapRegion* first_hr) {
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(first_hr->startsHumongous(), "pre-condition");
274
275 _humongous_type = ContinuesHumongous;
276 _humongous_start_region = first_hr;
277 }
278
279 void HeapRegion::set_notHumongous() {
280 assert(isHumongous(), "pre-condition");
281
282 if (startsHumongous()) {
283 assert(top() <= end(), "pre-condition");
284 set_end(_orig_end);
285 if (top() > end()) {
286 // at least one "continues humongous" region after it
287 set_top(end());
288 }
289 } else {
290 // continues humongous
291 assert(end() == _orig_end, "sanity");
292 }
293
294 assert(capacity() == HeapRegion::GrainBytes, "pre-condition");
295 _humongous_type = NotHumongous;
296 _humongous_start_region = NULL;
297 }
298
299 bool HeapRegion::claimHeapRegion(jint claimValue) {
300 jint current = _claimed;
301 if (current != claimValue) {
302 jint res = Atomic::cmpxchg(claimValue, &_claimed, current);
303 if (res == current) {
304 return true;
305 }
306 }
307 return false;
308 }
309
310 HeapWord* HeapRegion::next_block_start_careful(HeapWord* addr) {
311 HeapWord* low = addr;
312 HeapWord* high = end();
313 while (low < high) {
314 size_t diff = pointer_delta(high, low);
315 // Must add one below to bias toward the high amount. Otherwise, if
316 // "high" were at the desired value, and "low" were one less, we
317 // would not converge on "high". This is not symmetric, because
318 // we set "high" to a block start, which might be the right one,
319 // which we don't do for "low".
320 HeapWord* middle = low + (diff+1)/2;
321 if (middle == high) return high;
322 HeapWord* mid_bs = block_start_careful(middle);
323 if (mid_bs < addr) {
324 low = middle;
325 } else {
326 high = mid_bs;
327 }
328 }
329 assert(low == high && low >= addr, "Didn't work.");
330 return low;
331 }
332
333 HeapRegion::HeapRegion(uint hrm_index,
334 G1BlockOffsetSharedArray* sharedOffsetArray,
335 MemRegion mr) :
336 G1OffsetTableContigSpace(sharedOffsetArray, mr),
337 _hrm_index(hrm_index),
338 _allocation_context(AllocationContext::system()),
339 _humongous_type(NotHumongous), _humongous_start_region(NULL),
340 _in_collection_set(false),
341 _next_in_special_set(NULL), _orig_end(NULL),
342 _claimed(InitialClaimValue), _evacuation_failed(false),
343 _prev_marked_bytes(0), _next_marked_bytes(0), _gc_efficiency(0.0),
344 _young_type(NotYoung), _next_young_region(NULL),
345 _next_dirty_cards_region(NULL), _next(NULL), _prev(NULL),
346 #ifdef ASSERT
347 _containing_set(NULL),
348 #endif // ASSERT
349 _young_index_in_cset(-1), _surv_rate_group(NULL), _age_index(-1),
350 _rem_set(NULL), _recorded_rs_length(0), _predicted_elapsed_time_ms(0),
351 _predicted_bytes_to_copy(0)
352 {
353 _rem_set = new HeapRegionRemSet(sharedOffsetArray, this);
354 assert(HeapRegionRemSet::num_par_rem_sets() > 0, "Invariant.");
355
356 initialize(mr);
357 }
358
359 void HeapRegion::initialize(MemRegion mr, bool clear_space, bool mangle_space) {
360 assert(_rem_set->is_empty(), "Remembered set must be empty");
361
362 G1OffsetTableContigSpace::initialize(mr, clear_space, mangle_space);
363
364 _orig_end = mr.end();
365 hr_clear(false /*par*/, false /*clear_space*/);
366 set_top(bottom());
367 record_top_and_timestamp();
368 }
369
370 CompactibleSpace* HeapRegion::next_compaction_space() const {
371 return G1CollectedHeap::heap()->next_compaction_region(this);
372 }
373
374 void HeapRegion::note_self_forwarding_removal_start(bool during_initial_mark,
375 bool during_conc_mark) {
376 // We always recreate the prev marking info and we'll explicitly
377 // mark all objects we find to be self-forwarded on the prev
378 // bitmap. So all objects need to be below PTAMS.
379 _prev_marked_bytes = 0;
380
381 if (during_initial_mark) {
382 // During initial-mark, we'll also explicitly mark all objects
383 // we find to be self-forwarded on the next bitmap. So all
384 // objects need to be below NTAMS.
385 _next_top_at_mark_start = top();
386 _next_marked_bytes = 0;
387 } else if (during_conc_mark) {
388 // During concurrent mark, all objects in the CSet (including
389 // the ones we find to be self-forwarded) are implicitly live.
390 // So all objects need to be above NTAMS.
391 _next_top_at_mark_start = bottom();
392 _next_marked_bytes = 0;
393 }
394 }
395
396 void HeapRegion::note_self_forwarding_removal_end(bool during_initial_mark,
397 bool during_conc_mark,
398 size_t marked_bytes) {
399 assert(0 <= marked_bytes && marked_bytes <= used(),
400 err_msg("marked: "SIZE_FORMAT" used: "SIZE_FORMAT,
401 marked_bytes, used()));
402 _prev_top_at_mark_start = top();
403 _prev_marked_bytes = marked_bytes;
404 }
405
406 HeapWord*
407 HeapRegion::object_iterate_mem_careful(MemRegion mr,
408 ObjectClosure* cl) {
409 G1CollectedHeap* g1h = G1CollectedHeap::heap();
410 // We used to use "block_start_careful" here. But we're actually happy
411 // to update the BOT while we do this...
412 HeapWord* cur = block_start(mr.start());
413 mr = mr.intersection(used_region());
414 if (mr.is_empty()) return NULL;
415 // Otherwise, find the obj that extends onto mr.start().
416
417 assert(cur <= mr.start()
418 && (oop(cur)->klass_or_null() == NULL ||
419 cur + oop(cur)->size() > mr.start()),
420 "postcondition of block_start");
421 oop obj;
422 while (cur < mr.end()) {
423 obj = oop(cur);
424 if (obj->klass_or_null() == NULL) {
425 // Ran into an unparseable point.
426 return cur;
427 } else if (!g1h->is_obj_dead(obj)) {
428 cl->do_object(obj);
429 }
430 if (cl->abort()) return cur;
431 // The check above must occur before the operation below, since an
432 // abort might invalidate the "size" operation.
433 cur += block_size(cur);
434 }
435 return NULL;
436 }
437
438 HeapWord*
439 HeapRegion::
440 oops_on_card_seq_iterate_careful(MemRegion mr,
441 FilterOutOfRegionClosure* cl,
442 bool filter_young,
443 jbyte* card_ptr) {
444 // Currently, we should only have to clean the card if filter_young
445 // is true and vice versa.
446 if (filter_young) {
447 assert(card_ptr != NULL, "pre-condition");
448 } else {
449 assert(card_ptr == NULL, "pre-condition");
450 }
451 G1CollectedHeap* g1h = G1CollectedHeap::heap();
452
453 // If we're within a stop-world GC, then we might look at a card in a
454 // GC alloc region that extends onto a GC LAB, which may not be
455 // parseable. Stop such at the "saved_mark" of the region.
456 if (g1h->is_gc_active()) {
457 mr = mr.intersection(used_region_at_save_marks());
458 } else {
459 mr = mr.intersection(used_region());
460 }
461 if (mr.is_empty()) return NULL;
462 // Otherwise, find the obj that extends onto mr.start().
463
464 // The intersection of the incoming mr (for the card) and the
465 // allocated part of the region is non-empty. This implies that
466 // we have actually allocated into this region. The code in
467 // G1CollectedHeap.cpp that allocates a new region sets the
468 // is_young tag on the region before allocating. Thus we
469 // safely know if this region is young.
470 if (is_young() && filter_young) {
471 return NULL;
472 }
473
474 assert(!is_young(), "check value of filter_young");
475
476 // We can only clean the card here, after we make the decision that
477 // the card is not young. And we only clean the card if we have been
478 // asked to (i.e., card_ptr != NULL).
479 if (card_ptr != NULL) {
480 *card_ptr = CardTableModRefBS::clean_card_val();
481 // We must complete this write before we do any of the reads below.
482 OrderAccess::storeload();
483 }
484
485 // Cache the boundaries of the memory region in some const locals
486 HeapWord* const start = mr.start();
487 HeapWord* const end = mr.end();
488
489 // We used to use "block_start_careful" here. But we're actually happy
490 // to update the BOT while we do this...
491 HeapWord* cur = block_start(start);
492 assert(cur <= start, "Postcondition");
493
494 oop obj;
495
496 HeapWord* next = cur;
497 while (next <= start) {
498 cur = next;
499 obj = oop(cur);
500 if (obj->klass_or_null() == NULL) {
501 // Ran into an unparseable point.
502 return cur;
503 }
504 // Otherwise...
505 next = cur + block_size(cur);
506 }
507
508 // If we finish the above loop...We have a parseable object that
509 // begins on or before the start of the memory region, and ends
510 // inside or spans the entire region.
511
512 assert(obj == oop(cur), "sanity");
513 assert(cur <= start, "Loop postcondition");
514 assert(obj->klass_or_null() != NULL, "Loop postcondition");
515 assert((cur + block_size(cur)) > start, "Loop postcondition");
516
517 if (!g1h->is_obj_dead(obj)) {
518 obj->oop_iterate(cl, mr);
519 }
520
521 while (cur < end) {
522 obj = oop(cur);
523 if (obj->klass_or_null() == NULL) {
524 // Ran into an unparseable point.
525 return cur;
526 };
527
528 // Otherwise:
529 next = cur + block_size(cur);
530
531 if (!g1h->is_obj_dead(obj)) {
532 if (next < end || !obj->is_objArray()) {
533 // This object either does not span the MemRegion
534 // boundary, or if it does it's not an array.
535 // Apply closure to whole object.
536 obj->oop_iterate(cl);
537 } else {
538 // This obj is an array that spans the boundary.
539 // Stop at the boundary.
540 obj->oop_iterate(cl, mr);
541 }
542 }
543 cur = next;
544 }
545 return NULL;
546 }
547
548 // Code roots support
549
550 void HeapRegion::add_strong_code_root(nmethod* nm) {
551 HeapRegionRemSet* hrrs = rem_set();
552 hrrs->add_strong_code_root(nm);
553 }
554
555 void HeapRegion::remove_strong_code_root(nmethod* nm) {
556 HeapRegionRemSet* hrrs = rem_set();
557 hrrs->remove_strong_code_root(nm);
558 }
559
560 void HeapRegion::migrate_strong_code_roots() {
561 assert(in_collection_set(), "only collection set regions");
562 assert(!isHumongous(),
563 err_msg("humongous region "HR_FORMAT" should not have been added to collection set",
564 HR_FORMAT_PARAMS(this)));
565
566 HeapRegionRemSet* hrrs = rem_set();
567 hrrs->migrate_strong_code_roots();
568 }
569
570 void HeapRegion::strong_code_roots_do(CodeBlobClosure* blk) const {
571 HeapRegionRemSet* hrrs = rem_set();
572 hrrs->strong_code_roots_do(blk);
573 }
574
575 class VerifyStrongCodeRootOopClosure: public OopClosure {
576 const HeapRegion* _hr;
577 nmethod* _nm;
578 bool _failures;
579 bool _has_oops_in_region;
580
581 template <class T> void do_oop_work(T* p) {
582 T heap_oop = oopDesc::load_heap_oop(p);
583 if (!oopDesc::is_null(heap_oop)) {
584 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
585
586 // Note: not all the oops embedded in the nmethod are in the
587 // current region. We only look at those which are.
588 if (_hr->is_in(obj)) {
589 // Object is in the region. Check that its less than top
590 if (_hr->top() <= (HeapWord*)obj) {
591 // Object is above top
592 gclog_or_tty->print_cr("Object "PTR_FORMAT" in region "
593 "["PTR_FORMAT", "PTR_FORMAT") is above "
594 "top "PTR_FORMAT,
595 (void *)obj, _hr->bottom(), _hr->end(), _hr->top());
596 _failures = true;
597 return;
598 }
599 // Nmethod has at least one oop in the current region
600 _has_oops_in_region = true;
601 }
602 }
603 }
604
605 public:
606 VerifyStrongCodeRootOopClosure(const HeapRegion* hr, nmethod* nm):
607 _hr(hr), _failures(false), _has_oops_in_region(false) {}
608
609 void do_oop(narrowOop* p) { do_oop_work(p); }
610 void do_oop(oop* p) { do_oop_work(p); }
611
612 bool failures() { return _failures; }
613 bool has_oops_in_region() { return _has_oops_in_region; }
614 };
615
616 class VerifyStrongCodeRootCodeBlobClosure: public CodeBlobClosure {
617 const HeapRegion* _hr;
618 bool _failures;
619 public:
620 VerifyStrongCodeRootCodeBlobClosure(const HeapRegion* hr) :
621 _hr(hr), _failures(false) {}
622
623 void do_code_blob(CodeBlob* cb) {
624 nmethod* nm = (cb == NULL) ? NULL : cb->as_nmethod_or_null();
625 if (nm != NULL) {
626 // Verify that the nemthod is live
627 if (!nm->is_alive()) {
628 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] has dead nmethod "
629 PTR_FORMAT" in its strong code roots",
630 _hr->bottom(), _hr->end(), nm);
631 _failures = true;
632 } else {
633 VerifyStrongCodeRootOopClosure oop_cl(_hr, nm);
634 nm->oops_do(&oop_cl);
635 if (!oop_cl.has_oops_in_region()) {
636 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] has nmethod "
637 PTR_FORMAT" in its strong code roots "
638 "with no pointers into region",
639 _hr->bottom(), _hr->end(), nm);
640 _failures = true;
641 } else if (oop_cl.failures()) {
642 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] has other "
643 "failures for nmethod "PTR_FORMAT,
644 _hr->bottom(), _hr->end(), nm);
645 _failures = true;
646 }
647 }
648 }
649 }
650
651 bool failures() { return _failures; }
652 };
653
654 void HeapRegion::verify_strong_code_roots(VerifyOption vo, bool* failures) const {
655 if (!G1VerifyHeapRegionCodeRoots) {
656 // We're not verifying code roots.
657 return;
658 }
659 if (vo == VerifyOption_G1UseMarkWord) {
660 // Marking verification during a full GC is performed after class
661 // unloading, code cache unloading, etc so the strong code roots
662 // attached to each heap region are in an inconsistent state. They won't
663 // be consistent until the strong code roots are rebuilt after the
664 // actual GC. Skip verifying the strong code roots in this particular
665 // time.
666 assert(VerifyDuringGC, "only way to get here");
667 return;
668 }
669
670 HeapRegionRemSet* hrrs = rem_set();
671 size_t strong_code_roots_length = hrrs->strong_code_roots_list_length();
672
673 // if this region is empty then there should be no entries
674 // on its strong code root list
675 if (is_empty()) {
676 if (strong_code_roots_length > 0) {
677 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] is empty "
678 "but has "SIZE_FORMAT" code root entries",
679 bottom(), end(), strong_code_roots_length);
680 *failures = true;
681 }
682 return;
683 }
684
685 if (continuesHumongous()) {
686 if (strong_code_roots_length > 0) {
687 gclog_or_tty->print_cr("region "HR_FORMAT" is a continuation of a humongous "
688 "region but has "SIZE_FORMAT" code root entries",
689 HR_FORMAT_PARAMS(this), strong_code_roots_length);
690 *failures = true;
691 }
692 return;
693 }
694
695 VerifyStrongCodeRootCodeBlobClosure cb_cl(this);
696 strong_code_roots_do(&cb_cl);
697
698 if (cb_cl.failures()) {
699 *failures = true;
700 }
701 }
702
703 void HeapRegion::print() const { print_on(gclog_or_tty); }
704 void HeapRegion::print_on(outputStream* st) const {
705 st->print("AC%4u", allocation_context());
706
707 if (isHumongous()) {
708 if (startsHumongous())
709 st->print(" HS");
710 else
711 st->print(" HC");
712 } else {
713 st->print(" ");
714 }
715 if (in_collection_set())
716 st->print(" CS");
717 else
718 st->print(" ");
719 if (is_young())
720 st->print(is_survivor() ? " SU" : " Y ");
721 else
722 st->print(" ");
723 if (is_empty())
724 st->print(" F");
725 else
726 st->print(" ");
727 st->print(" TS %5d", _gc_time_stamp);
728 st->print(" PTAMS "PTR_FORMAT" NTAMS "PTR_FORMAT,
729 prev_top_at_mark_start(), next_top_at_mark_start());
730 G1OffsetTableContigSpace::print_on(st);
731 }
732
733 class VerifyLiveClosure: public OopClosure {
734 private:
735 G1CollectedHeap* _g1h;
736 CardTableModRefBS* _bs;
737 oop _containing_obj;
738 bool _failures;
739 int _n_failures;
740 VerifyOption _vo;
741 public:
742 // _vo == UsePrevMarking -> use "prev" marking information,
743 // _vo == UseNextMarking -> use "next" marking information,
744 // _vo == UseMarkWord -> use mark word from object header.
745 VerifyLiveClosure(G1CollectedHeap* g1h, VerifyOption vo) :
746 _g1h(g1h), _bs(NULL), _containing_obj(NULL),
747 _failures(false), _n_failures(0), _vo(vo)
748 {
749 BarrierSet* bs = _g1h->barrier_set();
750 if (bs->is_a(BarrierSet::CardTableModRef))
751 _bs = (CardTableModRefBS*)bs;
752 }
753
754 void set_containing_obj(oop obj) {
755 _containing_obj = obj;
756 }
757
758 bool failures() { return _failures; }
759 int n_failures() { return _n_failures; }
760
761 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
762 virtual void do_oop( oop* p) { do_oop_work(p); }
763
764 void print_object(outputStream* out, oop obj) {
765 #ifdef PRODUCT
766 Klass* k = obj->klass();
767 const char* class_name = InstanceKlass::cast(k)->external_name();
768 out->print_cr("class name %s", class_name);
769 #else // PRODUCT
770 obj->print_on(out);
771 #endif // PRODUCT
772 }
773
774 template <class T>
775 void do_oop_work(T* p) {
776 assert(_containing_obj != NULL, "Precondition");
777 assert(!_g1h->is_obj_dead_cond(_containing_obj, _vo),
778 "Precondition");
779 T heap_oop = oopDesc::load_heap_oop(p);
780 if (!oopDesc::is_null(heap_oop)) {
781 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
782 bool failed = false;
783 if (!_g1h->is_in_closed_subset(obj) || _g1h->is_obj_dead_cond(obj, _vo)) {
784 MutexLockerEx x(ParGCRareEvent_lock,
785 Mutex::_no_safepoint_check_flag);
786
787 if (!_failures) {
788 gclog_or_tty->cr();
789 gclog_or_tty->print_cr("----------");
790 }
791 if (!_g1h->is_in_closed_subset(obj)) {
792 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
793 gclog_or_tty->print_cr("Field "PTR_FORMAT
794 " of live obj "PTR_FORMAT" in region "
795 "["PTR_FORMAT", "PTR_FORMAT")",
796 p, (void*) _containing_obj,
797 from->bottom(), from->end());
798 print_object(gclog_or_tty, _containing_obj);
799 gclog_or_tty->print_cr("points to obj "PTR_FORMAT" not in the heap",
800 (void*) obj);
801 } else {
802 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
803 HeapRegion* to = _g1h->heap_region_containing((HeapWord*)obj);
804 gclog_or_tty->print_cr("Field "PTR_FORMAT
805 " of live obj "PTR_FORMAT" in region "
806 "["PTR_FORMAT", "PTR_FORMAT")",
807 p, (void*) _containing_obj,
808 from->bottom(), from->end());
809 print_object(gclog_or_tty, _containing_obj);
810 gclog_or_tty->print_cr("points to dead obj "PTR_FORMAT" in region "
811 "["PTR_FORMAT", "PTR_FORMAT")",
812 (void*) obj, to->bottom(), to->end());
813 print_object(gclog_or_tty, obj);
814 }
815 gclog_or_tty->print_cr("----------");
816 gclog_or_tty->flush();
817 _failures = true;
818 failed = true;
819 _n_failures++;
820 }
821
822 if (!_g1h->full_collection() || G1VerifyRSetsDuringFullGC) {
823 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
824 HeapRegion* to = _g1h->heap_region_containing(obj);
825 if (from != NULL && to != NULL &&
826 from != to &&
827 !to->isHumongous()) {
828 jbyte cv_obj = *_bs->byte_for_const(_containing_obj);
829 jbyte cv_field = *_bs->byte_for_const(p);
830 const jbyte dirty = CardTableModRefBS::dirty_card_val();
831
832 bool is_bad = !(from->is_young()
833 || to->rem_set()->contains_reference(p)
834 || !G1HRRSFlushLogBuffersOnVerify && // buffers were not flushed
835 (_containing_obj->is_objArray() ?
836 cv_field == dirty
837 : cv_obj == dirty || cv_field == dirty));
838 if (is_bad) {
839 MutexLockerEx x(ParGCRareEvent_lock,
840 Mutex::_no_safepoint_check_flag);
841
842 if (!_failures) {
843 gclog_or_tty->cr();
844 gclog_or_tty->print_cr("----------");
845 }
846 gclog_or_tty->print_cr("Missing rem set entry:");
847 gclog_or_tty->print_cr("Field "PTR_FORMAT" "
848 "of obj "PTR_FORMAT", "
849 "in region "HR_FORMAT,
850 p, (void*) _containing_obj,
851 HR_FORMAT_PARAMS(from));
852 _containing_obj->print_on(gclog_or_tty);
853 gclog_or_tty->print_cr("points to obj "PTR_FORMAT" "
854 "in region "HR_FORMAT,
855 (void*) obj,
856 HR_FORMAT_PARAMS(to));
857 obj->print_on(gclog_or_tty);
858 gclog_or_tty->print_cr("Obj head CTE = %d, field CTE = %d.",
859 cv_obj, cv_field);
860 gclog_or_tty->print_cr("----------");
861 gclog_or_tty->flush();
862 _failures = true;
863 if (!failed) _n_failures++;
864 }
865 }
866 }
867 }
868 }
869 };
870
871 // This really ought to be commoned up into OffsetTableContigSpace somehow.
872 // We would need a mechanism to make that code skip dead objects.
873
874 void HeapRegion::verify(VerifyOption vo,
875 bool* failures) const {
876 G1CollectedHeap* g1 = G1CollectedHeap::heap();
877 *failures = false;
878 HeapWord* p = bottom();
879 HeapWord* prev_p = NULL;
880 VerifyLiveClosure vl_cl(g1, vo);
881 bool is_humongous = isHumongous();
882 bool do_bot_verify = !is_young();
883 size_t object_num = 0;
884 while (p < top()) {
885 oop obj = oop(p);
886 size_t obj_size = block_size(p);
887 object_num += 1;
888
889 if (is_humongous != g1->isHumongous(obj_size) &&
890 !g1->is_obj_dead(obj, this)) { // Dead objects may have bigger block_size since they span several objects.
891 gclog_or_tty->print_cr("obj "PTR_FORMAT" is of %shumongous size ("
892 SIZE_FORMAT" words) in a %shumongous region",
893 p, g1->isHumongous(obj_size) ? "" : "non-",
894 obj_size, is_humongous ? "" : "non-");
895 *failures = true;
896 return;
897 }
898
899 // If it returns false, verify_for_object() will output the
900 // appropriate message.
901 if (do_bot_verify &&
902 !g1->is_obj_dead(obj, this) &&
903 !_offsets.verify_for_object(p, obj_size)) {
904 *failures = true;
905 return;
906 }
907
908 if (!g1->is_obj_dead_cond(obj, this, vo)) {
909 if (obj->is_oop()) {
910 Klass* klass = obj->klass();
911 bool is_metaspace_object = Metaspace::contains(klass) ||
912 (vo == VerifyOption_G1UsePrevMarking &&
913 ClassLoaderDataGraph::unload_list_contains(klass));
914 if (!is_metaspace_object) {
915 gclog_or_tty->print_cr("klass "PTR_FORMAT" of object "PTR_FORMAT" "
916 "not metadata", klass, (void *)obj);
917 *failures = true;
918 return;
919 } else if (!klass->is_klass()) {
920 gclog_or_tty->print_cr("klass "PTR_FORMAT" of object "PTR_FORMAT" "
921 "not a klass", klass, (void *)obj);
922 *failures = true;
923 return;
924 } else {
925 vl_cl.set_containing_obj(obj);
926 obj->oop_iterate_no_header(&vl_cl);
927 if (vl_cl.failures()) {
928 *failures = true;
929 }
930 if (G1MaxVerifyFailures >= 0 &&
931 vl_cl.n_failures() >= G1MaxVerifyFailures) {
932 return;
933 }
934 }
935 } else {
936 gclog_or_tty->print_cr(PTR_FORMAT" no an oop", (void *)obj);
937 *failures = true;
938 return;
939 }
940 }
941 prev_p = p;
942 p += obj_size;
943 }
944
945 if (p != top()) {
946 gclog_or_tty->print_cr("end of last object "PTR_FORMAT" "
947 "does not match top "PTR_FORMAT, p, top());
948 *failures = true;
949 return;
950 }
951
952 HeapWord* the_end = end();
953 assert(p == top(), "it should still hold");
954 // Do some extra BOT consistency checking for addresses in the
955 // range [top, end). BOT look-ups in this range should yield
956 // top. No point in doing that if top == end (there's nothing there).
957 if (p < the_end) {
958 // Look up top
959 HeapWord* addr_1 = p;
960 HeapWord* b_start_1 = _offsets.block_start_const(addr_1);
961 if (b_start_1 != p) {
962 gclog_or_tty->print_cr("BOT look up for top: "PTR_FORMAT" "
963 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
964 addr_1, b_start_1, p);
965 *failures = true;
966 return;
967 }
968
969 // Look up top + 1
970 HeapWord* addr_2 = p + 1;
971 if (addr_2 < the_end) {
972 HeapWord* b_start_2 = _offsets.block_start_const(addr_2);
973 if (b_start_2 != p) {
974 gclog_or_tty->print_cr("BOT look up for top + 1: "PTR_FORMAT" "
975 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
976 addr_2, b_start_2, p);
977 *failures = true;
978 return;
979 }
980 }
981
982 // Look up an address between top and end
983 size_t diff = pointer_delta(the_end, p) / 2;
984 HeapWord* addr_3 = p + diff;
985 if (addr_3 < the_end) {
986 HeapWord* b_start_3 = _offsets.block_start_const(addr_3);
987 if (b_start_3 != p) {
988 gclog_or_tty->print_cr("BOT look up for top + diff: "PTR_FORMAT" "
989 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
990 addr_3, b_start_3, p);
991 *failures = true;
992 return;
993 }
994 }
995
996 // Loook up end - 1
997 HeapWord* addr_4 = the_end - 1;
998 HeapWord* b_start_4 = _offsets.block_start_const(addr_4);
999 if (b_start_4 != p) {
1000 gclog_or_tty->print_cr("BOT look up for end - 1: "PTR_FORMAT" "
1001 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
1002 addr_4, b_start_4, p);
1003 *failures = true;
1004 return;
1005 }
1006 }
1007
1008 if (is_humongous && object_num > 1) {
1009 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] is humongous "
1010 "but has "SIZE_FORMAT", objects",
1011 bottom(), end(), object_num);
1012 *failures = true;
1013 return;
1014 }
1015
1016 verify_strong_code_roots(vo, failures);
1017 }
1018
1019 void HeapRegion::verify() const {
1020 bool dummy = false;
1021 verify(VerifyOption_G1UsePrevMarking, /* failures */ &dummy);
1022 }
1023
1024 // G1OffsetTableContigSpace code; copied from space.cpp. Hope this can go
1025 // away eventually.
1026
1027 void G1OffsetTableContigSpace::clear(bool mangle_space) {
1028 set_top(bottom());
1029 set_saved_mark_word(bottom());
1030 CompactibleSpace::clear(mangle_space);
1031 reset_bot();
1032 }
1033
1034 void G1OffsetTableContigSpace::set_bottom(HeapWord* new_bottom) {
1035 Space::set_bottom(new_bottom);
1036 _offsets.set_bottom(new_bottom);
1037 }
1038
1039 void G1OffsetTableContigSpace::set_end(HeapWord* new_end) {
1040 Space::set_end(new_end);
1041 _offsets.resize(new_end - bottom());
1042 }
1043
1044 void G1OffsetTableContigSpace::print() const {
1045 print_short();
1046 gclog_or_tty->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", "
1047 INTPTR_FORMAT ", " INTPTR_FORMAT ")",
1048 bottom(), top(), _offsets.threshold(), end());
1049 }
1050
1051 HeapWord* G1OffsetTableContigSpace::initialize_threshold() {
1052 return _offsets.initialize_threshold();
1053 }
1054
1055 HeapWord* G1OffsetTableContigSpace::cross_threshold(HeapWord* start,
1056 HeapWord* end) {
1057 _offsets.alloc_block(start, end);
1058 return _offsets.threshold();
1059 }
1060
1061 HeapWord* G1OffsetTableContigSpace::saved_mark_word() const {
1062 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1063 assert( _gc_time_stamp <= g1h->get_gc_time_stamp(), "invariant" );
1064 if (_gc_time_stamp < g1h->get_gc_time_stamp())
1065 return top();
1066 else
1067 return Space::saved_mark_word();
1068 }
1069
1070 void G1OffsetTableContigSpace::record_top_and_timestamp() {
1071 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1072 unsigned curr_gc_time_stamp = g1h->get_gc_time_stamp();
1073
1074 if (_gc_time_stamp < curr_gc_time_stamp) {
1075 // The order of these is important, as another thread might be
1076 // about to start scanning this region. If it does so after
1077 // set_saved_mark and before _gc_time_stamp = ..., then the latter
1078 // will be false, and it will pick up top() as the high water mark
1079 // of region. If it does so after _gc_time_stamp = ..., then it
1080 // will pick up the right saved_mark_word() as the high water mark
1081 // of the region. Either way, the behaviour will be correct.
1082 Space::set_saved_mark_word(top());
1083 OrderAccess::storestore();
1084 _gc_time_stamp = curr_gc_time_stamp;
1085 // No need to do another barrier to flush the writes above. If
1086 // this is called in parallel with other threads trying to
1087 // allocate into the region, the caller should call this while
1088 // holding a lock and when the lock is released the writes will be
1089 // flushed.
1090 }
1091 }
1092
1093 void G1OffsetTableContigSpace::safe_object_iterate(ObjectClosure* blk) {
1094 object_iterate(blk);
1095 }
1096
1097 void G1OffsetTableContigSpace::object_iterate(ObjectClosure* blk) {
1098 HeapWord* p = bottom();
1099 while (p < top()) {
1100 if (block_is_obj(p)) {
1101 blk->do_object(oop(p));
1102 }
1103 p += block_size(p);
1104 }
1105 }
1106
1107 #define block_is_always_obj(q) true
1108 void G1OffsetTableContigSpace::prepare_for_compaction(CompactPoint* cp) {
1109 SCAN_AND_FORWARD(cp, top, block_is_always_obj, block_size);
1110 }
1111 #undef block_is_always_obj
1112
1113 G1OffsetTableContigSpace::
1114 G1OffsetTableContigSpace(G1BlockOffsetSharedArray* sharedOffsetArray,
1115 MemRegion mr) :
1116 _offsets(sharedOffsetArray, mr),
1117 _par_alloc_lock(Mutex::leaf, "OffsetTableContigSpace par alloc lock", true),
1118 _gc_time_stamp(0)
1119 {
1120 _offsets.set_space(this);
1121 }
1122
1123 void G1OffsetTableContigSpace::initialize(MemRegion mr, bool clear_space, bool mangle_space) {
1124 CompactibleSpace::initialize(mr, clear_space, mangle_space);
1125 _top = bottom();
1126 reset_bot();
1127 }
1128