Thu, 26 Jun 2014 10:00:00 +0200
8047821: G1 Does not use the save_marks functionality as intended
Summary: Rename save_marks to record_top_and_timestamp and remove som unused but related methods
Reviewed-by: stefank, ehelin
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
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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).
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16 * 2 along with this work; if not, write to the Free Software Foundation,
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23 */
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 "memory/space.inline.hpp"
36 #include "oops/oop.inline.hpp"
37 #include "runtime/orderAccess.inline.hpp"
39 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
41 int HeapRegion::LogOfHRGrainBytes = 0;
42 int HeapRegion::LogOfHRGrainWords = 0;
43 size_t HeapRegion::GrainBytes = 0;
44 size_t HeapRegion::GrainWords = 0;
45 size_t HeapRegion::CardsPerRegion = 0;
47 HeapRegionDCTOC::HeapRegionDCTOC(G1CollectedHeap* g1,
48 HeapRegion* hr, ExtendedOopClosure* cl,
49 CardTableModRefBS::PrecisionStyle precision,
50 FilterKind fk) :
51 DirtyCardToOopClosure(hr, cl, precision, NULL),
52 _hr(hr), _fk(fk), _g1(g1) { }
54 FilterOutOfRegionClosure::FilterOutOfRegionClosure(HeapRegion* r,
55 OopClosure* oc) :
56 _r_bottom(r->bottom()), _r_end(r->end()), _oc(oc) { }
58 template<class ClosureType>
59 HeapWord* walk_mem_region_loop(ClosureType* cl, G1CollectedHeap* g1h,
60 HeapRegion* hr,
61 HeapWord* cur, HeapWord* top) {
62 oop cur_oop = oop(cur);
63 int oop_size = cur_oop->size();
64 HeapWord* next_obj = cur + oop_size;
65 while (next_obj < top) {
66 // Keep filtering the remembered set.
67 if (!g1h->is_obj_dead(cur_oop, hr)) {
68 // Bottom lies entirely below top, so we can call the
69 // non-memRegion version of oop_iterate below.
70 cur_oop->oop_iterate(cl);
71 }
72 cur = next_obj;
73 cur_oop = oop(cur);
74 oop_size = cur_oop->size();
75 next_obj = cur + oop_size;
76 }
77 return cur;
78 }
80 void HeapRegionDCTOC::walk_mem_region(MemRegion mr,
81 HeapWord* bottom,
82 HeapWord* top) {
83 G1CollectedHeap* g1h = _g1;
84 int oop_size;
85 ExtendedOopClosure* cl2 = NULL;
87 FilterIntoCSClosure intoCSFilt(this, g1h, _cl);
88 FilterOutOfRegionClosure outOfRegionFilt(_hr, _cl);
90 switch (_fk) {
91 case NoFilterKind: cl2 = _cl; break;
92 case IntoCSFilterKind: cl2 = &intoCSFilt; break;
93 case OutOfRegionFilterKind: cl2 = &outOfRegionFilt; break;
94 default: ShouldNotReachHere();
95 }
97 // Start filtering what we add to the remembered set. If the object is
98 // not considered dead, either because it is marked (in the mark bitmap)
99 // or it was allocated after marking finished, then we add it. Otherwise
100 // we can safely ignore the object.
101 if (!g1h->is_obj_dead(oop(bottom), _hr)) {
102 oop_size = oop(bottom)->oop_iterate(cl2, mr);
103 } else {
104 oop_size = oop(bottom)->size();
105 }
107 bottom += oop_size;
109 if (bottom < top) {
110 // We replicate the loop below for several kinds of possible filters.
111 switch (_fk) {
112 case NoFilterKind:
113 bottom = walk_mem_region_loop(_cl, g1h, _hr, bottom, top);
114 break;
116 case IntoCSFilterKind: {
117 FilterIntoCSClosure filt(this, g1h, _cl);
118 bottom = walk_mem_region_loop(&filt, g1h, _hr, bottom, top);
119 break;
120 }
122 case OutOfRegionFilterKind: {
123 FilterOutOfRegionClosure filt(_hr, _cl);
124 bottom = walk_mem_region_loop(&filt, g1h, _hr, bottom, top);
125 break;
126 }
128 default:
129 ShouldNotReachHere();
130 }
132 // Last object. Need to do dead-obj filtering here too.
133 if (!g1h->is_obj_dead(oop(bottom), _hr)) {
134 oop(bottom)->oop_iterate(cl2, mr);
135 }
136 }
137 }
139 // Minimum region size; we won't go lower than that.
140 // We might want to decrease this in the future, to deal with small
141 // heaps a bit more efficiently.
142 #define MIN_REGION_SIZE ( 1024 * 1024 )
144 // Maximum region size; we don't go higher than that. There's a good
145 // reason for having an upper bound. We don't want regions to get too
146 // large, otherwise cleanup's effectiveness would decrease as there
147 // will be fewer opportunities to find totally empty regions after
148 // marking.
149 #define MAX_REGION_SIZE ( 32 * 1024 * 1024 )
151 // The automatic region size calculation will try to have around this
152 // many regions in the heap (based on the min heap size).
153 #define TARGET_REGION_NUMBER 2048
155 size_t HeapRegion::max_region_size() {
156 return (size_t)MAX_REGION_SIZE;
157 }
159 void HeapRegion::setup_heap_region_size(size_t initial_heap_size, size_t max_heap_size) {
160 uintx region_size = G1HeapRegionSize;
161 if (FLAG_IS_DEFAULT(G1HeapRegionSize)) {
162 size_t average_heap_size = (initial_heap_size + max_heap_size) / 2;
163 region_size = MAX2(average_heap_size / TARGET_REGION_NUMBER,
164 (uintx) MIN_REGION_SIZE);
165 }
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);
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 }
180 // And recalculate the log.
181 region_size_log = log2_long((jlong) region_size);
183 // Now, set up the globals.
184 guarantee(LogOfHRGrainBytes == 0, "we should only set it once");
185 LogOfHRGrainBytes = region_size_log;
187 guarantee(LogOfHRGrainWords == 0, "we should only set it once");
188 LogOfHRGrainWords = LogOfHRGrainBytes - LogHeapWordSize;
190 guarantee(GrainBytes == 0, "we should only set it once");
191 // The cast to int is safe, given that we've bounded region_size by
192 // MIN_REGION_SIZE and MAX_REGION_SIZE.
193 GrainBytes = (size_t)region_size;
195 guarantee(GrainWords == 0, "we should only set it once");
196 GrainWords = GrainBytes >> LogHeapWordSize;
197 guarantee((size_t) 1 << LogOfHRGrainWords == GrainWords, "sanity");
199 guarantee(CardsPerRegion == 0, "we should only set it once");
200 CardsPerRegion = GrainBytes >> CardTableModRefBS::card_shift;
201 }
203 void HeapRegion::reset_after_compaction() {
204 G1OffsetTableContigSpace::reset_after_compaction();
205 // After a compaction the mark bitmap is invalid, so we must
206 // treat all objects as being inside the unmarked area.
207 zero_marked_bytes();
208 init_top_at_mark_start();
209 }
211 void HeapRegion::hr_clear(bool par, bool clear_space, bool locked) {
212 assert(_humongous_type == NotHumongous,
213 "we should have already filtered out humongous regions");
214 assert(_humongous_start_region == NULL,
215 "we should have already filtered out humongous regions");
216 assert(_end == _orig_end,
217 "we should have already filtered out humongous regions");
219 _in_collection_set = false;
221 set_young_index_in_cset(-1);
222 uninstall_surv_rate_group();
223 set_young_type(NotYoung);
224 reset_pre_dummy_top();
226 if (!par) {
227 // If this is parallel, this will be done later.
228 HeapRegionRemSet* hrrs = rem_set();
229 if (locked) {
230 hrrs->clear_locked();
231 } else {
232 hrrs->clear();
233 }
234 _claimed = InitialClaimValue;
235 }
236 zero_marked_bytes();
238 _offsets.resize(HeapRegion::GrainWords);
239 init_top_at_mark_start();
240 if (clear_space) clear(SpaceDecorator::Mangle);
241 }
243 void HeapRegion::par_clear() {
244 assert(used() == 0, "the region should have been already cleared");
245 assert(capacity() == HeapRegion::GrainBytes, "should be back to normal");
246 HeapRegionRemSet* hrrs = rem_set();
247 hrrs->clear();
248 CardTableModRefBS* ct_bs =
249 (CardTableModRefBS*)G1CollectedHeap::heap()->barrier_set();
250 ct_bs->clear(MemRegion(bottom(), end()));
251 }
253 void HeapRegion::calc_gc_efficiency() {
254 // GC efficiency is the ratio of how much space would be
255 // reclaimed over how long we predict it would take to reclaim it.
256 G1CollectedHeap* g1h = G1CollectedHeap::heap();
257 G1CollectorPolicy* g1p = g1h->g1_policy();
259 // Retrieve a prediction of the elapsed time for this region for
260 // a mixed gc because the region will only be evacuated during a
261 // mixed gc.
262 double region_elapsed_time_ms =
263 g1p->predict_region_elapsed_time_ms(this, false /* for_young_gc */);
264 _gc_efficiency = (double) reclaimable_bytes() / region_elapsed_time_ms;
265 }
267 void HeapRegion::set_startsHumongous(HeapWord* new_top, HeapWord* new_end) {
268 assert(!isHumongous(), "sanity / pre-condition");
269 assert(end() == _orig_end,
270 "Should be normal before the humongous object allocation");
271 assert(top() == bottom(), "should be empty");
272 assert(bottom() <= new_top && new_top <= new_end, "pre-condition");
274 _humongous_type = StartsHumongous;
275 _humongous_start_region = this;
277 set_end(new_end);
278 _offsets.set_for_starts_humongous(new_top);
279 }
281 void HeapRegion::set_continuesHumongous(HeapRegion* first_hr) {
282 assert(!isHumongous(), "sanity / pre-condition");
283 assert(end() == _orig_end,
284 "Should be normal before the humongous object allocation");
285 assert(top() == bottom(), "should be empty");
286 assert(first_hr->startsHumongous(), "pre-condition");
288 _humongous_type = ContinuesHumongous;
289 _humongous_start_region = first_hr;
290 }
292 void HeapRegion::set_notHumongous() {
293 assert(isHumongous(), "pre-condition");
295 if (startsHumongous()) {
296 assert(top() <= end(), "pre-condition");
297 set_end(_orig_end);
298 if (top() > end()) {
299 // at least one "continues humongous" region after it
300 set_top(end());
301 }
302 } else {
303 // continues humongous
304 assert(end() == _orig_end, "sanity");
305 }
307 assert(capacity() == HeapRegion::GrainBytes, "pre-condition");
308 _humongous_type = NotHumongous;
309 _humongous_start_region = NULL;
310 }
312 bool HeapRegion::claimHeapRegion(jint claimValue) {
313 jint current = _claimed;
314 if (current != claimValue) {
315 jint res = Atomic::cmpxchg(claimValue, &_claimed, current);
316 if (res == current) {
317 return true;
318 }
319 }
320 return false;
321 }
323 HeapWord* HeapRegion::next_block_start_careful(HeapWord* addr) {
324 HeapWord* low = addr;
325 HeapWord* high = end();
326 while (low < high) {
327 size_t diff = pointer_delta(high, low);
328 // Must add one below to bias toward the high amount. Otherwise, if
329 // "high" were at the desired value, and "low" were one less, we
330 // would not converge on "high". This is not symmetric, because
331 // we set "high" to a block start, which might be the right one,
332 // which we don't do for "low".
333 HeapWord* middle = low + (diff+1)/2;
334 if (middle == high) return high;
335 HeapWord* mid_bs = block_start_careful(middle);
336 if (mid_bs < addr) {
337 low = middle;
338 } else {
339 high = mid_bs;
340 }
341 }
342 assert(low == high && low >= addr, "Didn't work.");
343 return low;
344 }
346 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
347 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
348 #endif // _MSC_VER
351 HeapRegion::HeapRegion(uint hrs_index,
352 G1BlockOffsetSharedArray* sharedOffsetArray,
353 MemRegion mr) :
354 G1OffsetTableContigSpace(sharedOffsetArray, mr),
355 _hrs_index(hrs_index),
356 _humongous_type(NotHumongous), _humongous_start_region(NULL),
357 _in_collection_set(false),
358 _next_in_special_set(NULL), _orig_end(NULL),
359 _claimed(InitialClaimValue), _evacuation_failed(false),
360 _prev_marked_bytes(0), _next_marked_bytes(0), _gc_efficiency(0.0),
361 _young_type(NotYoung), _next_young_region(NULL),
362 _next_dirty_cards_region(NULL), _next(NULL), _prev(NULL), _pending_removal(false),
363 #ifdef ASSERT
364 _containing_set(NULL),
365 #endif // ASSERT
366 _young_index_in_cset(-1), _surv_rate_group(NULL), _age_index(-1),
367 _rem_set(NULL), _recorded_rs_length(0), _predicted_elapsed_time_ms(0),
368 _predicted_bytes_to_copy(0)
369 {
370 _rem_set = new HeapRegionRemSet(sharedOffsetArray, this);
371 _orig_end = mr.end();
372 // Note that initialize() will set the start of the unmarked area of the
373 // region.
374 hr_clear(false /*par*/, false /*clear_space*/);
375 set_top(bottom());
376 record_top_and_timestamp();
378 assert(HeapRegionRemSet::num_par_rem_sets() > 0, "Invariant.");
379 }
381 CompactibleSpace* HeapRegion::next_compaction_space() const {
382 // We're not using an iterator given that it will wrap around when
383 // it reaches the last region and this is not what we want here.
384 G1CollectedHeap* g1h = G1CollectedHeap::heap();
385 uint index = hrs_index() + 1;
386 while (index < g1h->n_regions()) {
387 HeapRegion* hr = g1h->region_at(index);
388 if (!hr->isHumongous()) {
389 return hr;
390 }
391 index += 1;
392 }
393 return NULL;
394 }
396 void HeapRegion::note_self_forwarding_removal_start(bool during_initial_mark,
397 bool during_conc_mark) {
398 // We always recreate the prev marking info and we'll explicitly
399 // mark all objects we find to be self-forwarded on the prev
400 // bitmap. So all objects need to be below PTAMS.
401 _prev_top_at_mark_start = top();
402 _prev_marked_bytes = 0;
404 if (during_initial_mark) {
405 // During initial-mark, we'll also explicitly mark all objects
406 // we find to be self-forwarded on the next bitmap. So all
407 // objects need to be below NTAMS.
408 _next_top_at_mark_start = top();
409 _next_marked_bytes = 0;
410 } else if (during_conc_mark) {
411 // During concurrent mark, all objects in the CSet (including
412 // the ones we find to be self-forwarded) are implicitly live.
413 // So all objects need to be above NTAMS.
414 _next_top_at_mark_start = bottom();
415 _next_marked_bytes = 0;
416 }
417 }
419 void HeapRegion::note_self_forwarding_removal_end(bool during_initial_mark,
420 bool during_conc_mark,
421 size_t marked_bytes) {
422 assert(0 <= marked_bytes && marked_bytes <= used(),
423 err_msg("marked: "SIZE_FORMAT" used: "SIZE_FORMAT,
424 marked_bytes, used()));
425 _prev_marked_bytes = marked_bytes;
426 }
428 HeapWord*
429 HeapRegion::object_iterate_mem_careful(MemRegion mr,
430 ObjectClosure* cl) {
431 G1CollectedHeap* g1h = G1CollectedHeap::heap();
432 // We used to use "block_start_careful" here. But we're actually happy
433 // to update the BOT while we do this...
434 HeapWord* cur = block_start(mr.start());
435 mr = mr.intersection(used_region());
436 if (mr.is_empty()) return NULL;
437 // Otherwise, find the obj that extends onto mr.start().
439 assert(cur <= mr.start()
440 && (oop(cur)->klass_or_null() == NULL ||
441 cur + oop(cur)->size() > mr.start()),
442 "postcondition of block_start");
443 oop obj;
444 while (cur < mr.end()) {
445 obj = oop(cur);
446 if (obj->klass_or_null() == NULL) {
447 // Ran into an unparseable point.
448 return cur;
449 } else if (!g1h->is_obj_dead(obj)) {
450 cl->do_object(obj);
451 }
452 if (cl->abort()) return cur;
453 // The check above must occur before the operation below, since an
454 // abort might invalidate the "size" operation.
455 cur += obj->size();
456 }
457 return NULL;
458 }
460 HeapWord*
461 HeapRegion::
462 oops_on_card_seq_iterate_careful(MemRegion mr,
463 FilterOutOfRegionClosure* cl,
464 bool filter_young,
465 jbyte* card_ptr) {
466 // Currently, we should only have to clean the card if filter_young
467 // is true and vice versa.
468 if (filter_young) {
469 assert(card_ptr != NULL, "pre-condition");
470 } else {
471 assert(card_ptr == NULL, "pre-condition");
472 }
473 G1CollectedHeap* g1h = G1CollectedHeap::heap();
475 // If we're within a stop-world GC, then we might look at a card in a
476 // GC alloc region that extends onto a GC LAB, which may not be
477 // parseable. Stop such at the "saved_mark" of the region.
478 if (g1h->is_gc_active()) {
479 mr = mr.intersection(used_region_at_save_marks());
480 } else {
481 mr = mr.intersection(used_region());
482 }
483 if (mr.is_empty()) return NULL;
484 // Otherwise, find the obj that extends onto mr.start().
486 // The intersection of the incoming mr (for the card) and the
487 // allocated part of the region is non-empty. This implies that
488 // we have actually allocated into this region. The code in
489 // G1CollectedHeap.cpp that allocates a new region sets the
490 // is_young tag on the region before allocating. Thus we
491 // safely know if this region is young.
492 if (is_young() && filter_young) {
493 return NULL;
494 }
496 assert(!is_young(), "check value of filter_young");
498 // We can only clean the card here, after we make the decision that
499 // the card is not young. And we only clean the card if we have been
500 // asked to (i.e., card_ptr != NULL).
501 if (card_ptr != NULL) {
502 *card_ptr = CardTableModRefBS::clean_card_val();
503 // We must complete this write before we do any of the reads below.
504 OrderAccess::storeload();
505 }
507 // Cache the boundaries of the memory region in some const locals
508 HeapWord* const start = mr.start();
509 HeapWord* const end = mr.end();
511 // We used to use "block_start_careful" here. But we're actually happy
512 // to update the BOT while we do this...
513 HeapWord* cur = block_start(start);
514 assert(cur <= start, "Postcondition");
516 oop obj;
518 HeapWord* next = cur;
519 while (next <= start) {
520 cur = next;
521 obj = oop(cur);
522 if (obj->klass_or_null() == NULL) {
523 // Ran into an unparseable point.
524 return cur;
525 }
526 // Otherwise...
527 next = (cur + obj->size());
528 }
530 // If we finish the above loop...We have a parseable object that
531 // begins on or before the start of the memory region, and ends
532 // inside or spans the entire region.
534 assert(obj == oop(cur), "sanity");
535 assert(cur <= start &&
536 obj->klass_or_null() != NULL &&
537 (cur + obj->size()) > start,
538 "Loop postcondition");
540 if (!g1h->is_obj_dead(obj)) {
541 obj->oop_iterate(cl, mr);
542 }
544 while (cur < end) {
545 obj = oop(cur);
546 if (obj->klass_or_null() == NULL) {
547 // Ran into an unparseable point.
548 return cur;
549 };
551 // Otherwise:
552 next = (cur + obj->size());
554 if (!g1h->is_obj_dead(obj)) {
555 if (next < end || !obj->is_objArray()) {
556 // This object either does not span the MemRegion
557 // boundary, or if it does it's not an array.
558 // Apply closure to whole object.
559 obj->oop_iterate(cl);
560 } else {
561 // This obj is an array that spans the boundary.
562 // Stop at the boundary.
563 obj->oop_iterate(cl, mr);
564 }
565 }
566 cur = next;
567 }
568 return NULL;
569 }
571 // Code roots support
573 void HeapRegion::add_strong_code_root(nmethod* nm) {
574 HeapRegionRemSet* hrrs = rem_set();
575 hrrs->add_strong_code_root(nm);
576 }
578 void HeapRegion::remove_strong_code_root(nmethod* nm) {
579 HeapRegionRemSet* hrrs = rem_set();
580 hrrs->remove_strong_code_root(nm);
581 }
583 void HeapRegion::migrate_strong_code_roots() {
584 assert(in_collection_set(), "only collection set regions");
585 assert(!isHumongous(),
586 err_msg("humongous region "HR_FORMAT" should not have been added to collection set",
587 HR_FORMAT_PARAMS(this)));
589 HeapRegionRemSet* hrrs = rem_set();
590 hrrs->migrate_strong_code_roots();
591 }
593 void HeapRegion::strong_code_roots_do(CodeBlobClosure* blk) const {
594 HeapRegionRemSet* hrrs = rem_set();
595 hrrs->strong_code_roots_do(blk);
596 }
598 class VerifyStrongCodeRootOopClosure: public OopClosure {
599 const HeapRegion* _hr;
600 nmethod* _nm;
601 bool _failures;
602 bool _has_oops_in_region;
604 template <class T> void do_oop_work(T* p) {
605 T heap_oop = oopDesc::load_heap_oop(p);
606 if (!oopDesc::is_null(heap_oop)) {
607 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
609 // Note: not all the oops embedded in the nmethod are in the
610 // current region. We only look at those which are.
611 if (_hr->is_in(obj)) {
612 // Object is in the region. Check that its less than top
613 if (_hr->top() <= (HeapWord*)obj) {
614 // Object is above top
615 gclog_or_tty->print_cr("Object "PTR_FORMAT" in region "
616 "["PTR_FORMAT", "PTR_FORMAT") is above "
617 "top "PTR_FORMAT,
618 (void *)obj, _hr->bottom(), _hr->end(), _hr->top());
619 _failures = true;
620 return;
621 }
622 // Nmethod has at least one oop in the current region
623 _has_oops_in_region = true;
624 }
625 }
626 }
628 public:
629 VerifyStrongCodeRootOopClosure(const HeapRegion* hr, nmethod* nm):
630 _hr(hr), _failures(false), _has_oops_in_region(false) {}
632 void do_oop(narrowOop* p) { do_oop_work(p); }
633 void do_oop(oop* p) { do_oop_work(p); }
635 bool failures() { return _failures; }
636 bool has_oops_in_region() { return _has_oops_in_region; }
637 };
639 class VerifyStrongCodeRootCodeBlobClosure: public CodeBlobClosure {
640 const HeapRegion* _hr;
641 bool _failures;
642 public:
643 VerifyStrongCodeRootCodeBlobClosure(const HeapRegion* hr) :
644 _hr(hr), _failures(false) {}
646 void do_code_blob(CodeBlob* cb) {
647 nmethod* nm = (cb == NULL) ? NULL : cb->as_nmethod_or_null();
648 if (nm != NULL) {
649 // Verify that the nemthod is live
650 if (!nm->is_alive()) {
651 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] has dead nmethod "
652 PTR_FORMAT" in its strong code roots",
653 _hr->bottom(), _hr->end(), nm);
654 _failures = true;
655 } else {
656 VerifyStrongCodeRootOopClosure oop_cl(_hr, nm);
657 nm->oops_do(&oop_cl);
658 if (!oop_cl.has_oops_in_region()) {
659 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] has nmethod "
660 PTR_FORMAT" in its strong code roots "
661 "with no pointers into region",
662 _hr->bottom(), _hr->end(), nm);
663 _failures = true;
664 } else if (oop_cl.failures()) {
665 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] has other "
666 "failures for nmethod "PTR_FORMAT,
667 _hr->bottom(), _hr->end(), nm);
668 _failures = true;
669 }
670 }
671 }
672 }
674 bool failures() { return _failures; }
675 };
677 void HeapRegion::verify_strong_code_roots(VerifyOption vo, bool* failures) const {
678 if (!G1VerifyHeapRegionCodeRoots) {
679 // We're not verifying code roots.
680 return;
681 }
682 if (vo == VerifyOption_G1UseMarkWord) {
683 // Marking verification during a full GC is performed after class
684 // unloading, code cache unloading, etc so the strong code roots
685 // attached to each heap region are in an inconsistent state. They won't
686 // be consistent until the strong code roots are rebuilt after the
687 // actual GC. Skip verifying the strong code roots in this particular
688 // time.
689 assert(VerifyDuringGC, "only way to get here");
690 return;
691 }
693 HeapRegionRemSet* hrrs = rem_set();
694 size_t strong_code_roots_length = hrrs->strong_code_roots_list_length();
696 // if this region is empty then there should be no entries
697 // on its strong code root list
698 if (is_empty()) {
699 if (strong_code_roots_length > 0) {
700 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] is empty "
701 "but has "SIZE_FORMAT" code root entries",
702 bottom(), end(), strong_code_roots_length);
703 *failures = true;
704 }
705 return;
706 }
708 if (continuesHumongous()) {
709 if (strong_code_roots_length > 0) {
710 gclog_or_tty->print_cr("region "HR_FORMAT" is a continuation of a humongous "
711 "region but has "SIZE_FORMAT" code root entries",
712 HR_FORMAT_PARAMS(this), strong_code_roots_length);
713 *failures = true;
714 }
715 return;
716 }
718 VerifyStrongCodeRootCodeBlobClosure cb_cl(this);
719 strong_code_roots_do(&cb_cl);
721 if (cb_cl.failures()) {
722 *failures = true;
723 }
724 }
726 void HeapRegion::print() const { print_on(gclog_or_tty); }
727 void HeapRegion::print_on(outputStream* st) const {
728 if (isHumongous()) {
729 if (startsHumongous())
730 st->print(" HS");
731 else
732 st->print(" HC");
733 } else {
734 st->print(" ");
735 }
736 if (in_collection_set())
737 st->print(" CS");
738 else
739 st->print(" ");
740 if (is_young())
741 st->print(is_survivor() ? " SU" : " Y ");
742 else
743 st->print(" ");
744 if (is_empty())
745 st->print(" F");
746 else
747 st->print(" ");
748 st->print(" TS %5d", _gc_time_stamp);
749 st->print(" PTAMS "PTR_FORMAT" NTAMS "PTR_FORMAT,
750 prev_top_at_mark_start(), next_top_at_mark_start());
751 G1OffsetTableContigSpace::print_on(st);
752 }
754 class VerifyLiveClosure: public OopClosure {
755 private:
756 G1CollectedHeap* _g1h;
757 CardTableModRefBS* _bs;
758 oop _containing_obj;
759 bool _failures;
760 int _n_failures;
761 VerifyOption _vo;
762 public:
763 // _vo == UsePrevMarking -> use "prev" marking information,
764 // _vo == UseNextMarking -> use "next" marking information,
765 // _vo == UseMarkWord -> use mark word from object header.
766 VerifyLiveClosure(G1CollectedHeap* g1h, VerifyOption vo) :
767 _g1h(g1h), _bs(NULL), _containing_obj(NULL),
768 _failures(false), _n_failures(0), _vo(vo)
769 {
770 BarrierSet* bs = _g1h->barrier_set();
771 if (bs->is_a(BarrierSet::CardTableModRef))
772 _bs = (CardTableModRefBS*)bs;
773 }
775 void set_containing_obj(oop obj) {
776 _containing_obj = obj;
777 }
779 bool failures() { return _failures; }
780 int n_failures() { return _n_failures; }
782 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
783 virtual void do_oop( oop* p) { do_oop_work(p); }
785 void print_object(outputStream* out, oop obj) {
786 #ifdef PRODUCT
787 Klass* k = obj->klass();
788 const char* class_name = InstanceKlass::cast(k)->external_name();
789 out->print_cr("class name %s", class_name);
790 #else // PRODUCT
791 obj->print_on(out);
792 #endif // PRODUCT
793 }
795 template <class T>
796 void do_oop_work(T* p) {
797 assert(_containing_obj != NULL, "Precondition");
798 assert(!_g1h->is_obj_dead_cond(_containing_obj, _vo),
799 "Precondition");
800 T heap_oop = oopDesc::load_heap_oop(p);
801 if (!oopDesc::is_null(heap_oop)) {
802 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
803 bool failed = false;
804 if (!_g1h->is_in_closed_subset(obj) || _g1h->is_obj_dead_cond(obj, _vo)) {
805 MutexLockerEx x(ParGCRareEvent_lock,
806 Mutex::_no_safepoint_check_flag);
808 if (!_failures) {
809 gclog_or_tty->cr();
810 gclog_or_tty->print_cr("----------");
811 }
812 if (!_g1h->is_in_closed_subset(obj)) {
813 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
814 gclog_or_tty->print_cr("Field "PTR_FORMAT
815 " of live obj "PTR_FORMAT" in region "
816 "["PTR_FORMAT", "PTR_FORMAT")",
817 p, (void*) _containing_obj,
818 from->bottom(), from->end());
819 print_object(gclog_or_tty, _containing_obj);
820 gclog_or_tty->print_cr("points to obj "PTR_FORMAT" not in the heap",
821 (void*) obj);
822 } else {
823 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
824 HeapRegion* to = _g1h->heap_region_containing((HeapWord*)obj);
825 gclog_or_tty->print_cr("Field "PTR_FORMAT
826 " of live obj "PTR_FORMAT" in region "
827 "["PTR_FORMAT", "PTR_FORMAT")",
828 p, (void*) _containing_obj,
829 from->bottom(), from->end());
830 print_object(gclog_or_tty, _containing_obj);
831 gclog_or_tty->print_cr("points to dead obj "PTR_FORMAT" in region "
832 "["PTR_FORMAT", "PTR_FORMAT")",
833 (void*) obj, to->bottom(), to->end());
834 print_object(gclog_or_tty, obj);
835 }
836 gclog_or_tty->print_cr("----------");
837 gclog_or_tty->flush();
838 _failures = true;
839 failed = true;
840 _n_failures++;
841 }
843 if (!_g1h->full_collection() || G1VerifyRSetsDuringFullGC) {
844 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
845 HeapRegion* to = _g1h->heap_region_containing(obj);
846 if (from != NULL && to != NULL &&
847 from != to &&
848 !to->isHumongous()) {
849 jbyte cv_obj = *_bs->byte_for_const(_containing_obj);
850 jbyte cv_field = *_bs->byte_for_const(p);
851 const jbyte dirty = CardTableModRefBS::dirty_card_val();
853 bool is_bad = !(from->is_young()
854 || to->rem_set()->contains_reference(p)
855 || !G1HRRSFlushLogBuffersOnVerify && // buffers were not flushed
856 (_containing_obj->is_objArray() ?
857 cv_field == dirty
858 : cv_obj == dirty || cv_field == dirty));
859 if (is_bad) {
860 MutexLockerEx x(ParGCRareEvent_lock,
861 Mutex::_no_safepoint_check_flag);
863 if (!_failures) {
864 gclog_or_tty->cr();
865 gclog_or_tty->print_cr("----------");
866 }
867 gclog_or_tty->print_cr("Missing rem set entry:");
868 gclog_or_tty->print_cr("Field "PTR_FORMAT" "
869 "of obj "PTR_FORMAT", "
870 "in region "HR_FORMAT,
871 p, (void*) _containing_obj,
872 HR_FORMAT_PARAMS(from));
873 _containing_obj->print_on(gclog_or_tty);
874 gclog_or_tty->print_cr("points to obj "PTR_FORMAT" "
875 "in region "HR_FORMAT,
876 (void*) obj,
877 HR_FORMAT_PARAMS(to));
878 obj->print_on(gclog_or_tty);
879 gclog_or_tty->print_cr("Obj head CTE = %d, field CTE = %d.",
880 cv_obj, cv_field);
881 gclog_or_tty->print_cr("----------");
882 gclog_or_tty->flush();
883 _failures = true;
884 if (!failed) _n_failures++;
885 }
886 }
887 }
888 }
889 }
890 };
892 // This really ought to be commoned up into OffsetTableContigSpace somehow.
893 // We would need a mechanism to make that code skip dead objects.
895 void HeapRegion::verify(VerifyOption vo,
896 bool* failures) const {
897 G1CollectedHeap* g1 = G1CollectedHeap::heap();
898 *failures = false;
899 HeapWord* p = bottom();
900 HeapWord* prev_p = NULL;
901 VerifyLiveClosure vl_cl(g1, vo);
902 bool is_humongous = isHumongous();
903 bool do_bot_verify = !is_young();
904 size_t object_num = 0;
905 while (p < top()) {
906 oop obj = oop(p);
907 size_t obj_size = obj->size();
908 object_num += 1;
910 if (is_humongous != g1->isHumongous(obj_size)) {
911 gclog_or_tty->print_cr("obj "PTR_FORMAT" is of %shumongous size ("
912 SIZE_FORMAT" words) in a %shumongous region",
913 p, g1->isHumongous(obj_size) ? "" : "non-",
914 obj_size, is_humongous ? "" : "non-");
915 *failures = true;
916 return;
917 }
919 // If it returns false, verify_for_object() will output the
920 // appropriate messasge.
921 if (do_bot_verify && !_offsets.verify_for_object(p, obj_size)) {
922 *failures = true;
923 return;
924 }
926 if (!g1->is_obj_dead_cond(obj, this, vo)) {
927 if (obj->is_oop()) {
928 Klass* klass = obj->klass();
929 if (!klass->is_metaspace_object()) {
930 gclog_or_tty->print_cr("klass "PTR_FORMAT" of object "PTR_FORMAT" "
931 "not metadata", klass, (void *)obj);
932 *failures = true;
933 return;
934 } else if (!klass->is_klass()) {
935 gclog_or_tty->print_cr("klass "PTR_FORMAT" of object "PTR_FORMAT" "
936 "not a klass", klass, (void *)obj);
937 *failures = true;
938 return;
939 } else {
940 vl_cl.set_containing_obj(obj);
941 obj->oop_iterate_no_header(&vl_cl);
942 if (vl_cl.failures()) {
943 *failures = true;
944 }
945 if (G1MaxVerifyFailures >= 0 &&
946 vl_cl.n_failures() >= G1MaxVerifyFailures) {
947 return;
948 }
949 }
950 } else {
951 gclog_or_tty->print_cr(PTR_FORMAT" no an oop", (void *)obj);
952 *failures = true;
953 return;
954 }
955 }
956 prev_p = p;
957 p += obj_size;
958 }
960 if (p != top()) {
961 gclog_or_tty->print_cr("end of last object "PTR_FORMAT" "
962 "does not match top "PTR_FORMAT, p, top());
963 *failures = true;
964 return;
965 }
967 HeapWord* the_end = end();
968 assert(p == top(), "it should still hold");
969 // Do some extra BOT consistency checking for addresses in the
970 // range [top, end). BOT look-ups in this range should yield
971 // top. No point in doing that if top == end (there's nothing there).
972 if (p < the_end) {
973 // Look up top
974 HeapWord* addr_1 = p;
975 HeapWord* b_start_1 = _offsets.block_start_const(addr_1);
976 if (b_start_1 != p) {
977 gclog_or_tty->print_cr("BOT look up for top: "PTR_FORMAT" "
978 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
979 addr_1, b_start_1, p);
980 *failures = true;
981 return;
982 }
984 // Look up top + 1
985 HeapWord* addr_2 = p + 1;
986 if (addr_2 < the_end) {
987 HeapWord* b_start_2 = _offsets.block_start_const(addr_2);
988 if (b_start_2 != p) {
989 gclog_or_tty->print_cr("BOT look up for top + 1: "PTR_FORMAT" "
990 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
991 addr_2, b_start_2, p);
992 *failures = true;
993 return;
994 }
995 }
997 // Look up an address between top and end
998 size_t diff = pointer_delta(the_end, p) / 2;
999 HeapWord* addr_3 = p + diff;
1000 if (addr_3 < the_end) {
1001 HeapWord* b_start_3 = _offsets.block_start_const(addr_3);
1002 if (b_start_3 != p) {
1003 gclog_or_tty->print_cr("BOT look up for top + diff: "PTR_FORMAT" "
1004 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
1005 addr_3, b_start_3, p);
1006 *failures = true;
1007 return;
1008 }
1009 }
1011 // Loook up end - 1
1012 HeapWord* addr_4 = the_end - 1;
1013 HeapWord* b_start_4 = _offsets.block_start_const(addr_4);
1014 if (b_start_4 != p) {
1015 gclog_or_tty->print_cr("BOT look up for end - 1: "PTR_FORMAT" "
1016 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
1017 addr_4, b_start_4, p);
1018 *failures = true;
1019 return;
1020 }
1021 }
1023 if (is_humongous && object_num > 1) {
1024 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] is humongous "
1025 "but has "SIZE_FORMAT", objects",
1026 bottom(), end(), object_num);
1027 *failures = true;
1028 return;
1029 }
1031 verify_strong_code_roots(vo, failures);
1032 }
1034 void HeapRegion::verify() const {
1035 bool dummy = false;
1036 verify(VerifyOption_G1UsePrevMarking, /* failures */ &dummy);
1037 }
1039 // G1OffsetTableContigSpace code; copied from space.cpp. Hope this can go
1040 // away eventually.
1042 void G1OffsetTableContigSpace::clear(bool mangle_space) {
1043 ContiguousSpace::clear(mangle_space);
1044 _offsets.zero_bottom_entry();
1045 _offsets.initialize_threshold();
1046 }
1048 void G1OffsetTableContigSpace::set_bottom(HeapWord* new_bottom) {
1049 Space::set_bottom(new_bottom);
1050 _offsets.set_bottom(new_bottom);
1051 }
1053 void G1OffsetTableContigSpace::set_end(HeapWord* new_end) {
1054 Space::set_end(new_end);
1055 _offsets.resize(new_end - bottom());
1056 }
1058 void G1OffsetTableContigSpace::print() const {
1059 print_short();
1060 gclog_or_tty->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", "
1061 INTPTR_FORMAT ", " INTPTR_FORMAT ")",
1062 bottom(), top(), _offsets.threshold(), end());
1063 }
1065 HeapWord* G1OffsetTableContigSpace::initialize_threshold() {
1066 return _offsets.initialize_threshold();
1067 }
1069 HeapWord* G1OffsetTableContigSpace::cross_threshold(HeapWord* start,
1070 HeapWord* end) {
1071 _offsets.alloc_block(start, end);
1072 return _offsets.threshold();
1073 }
1075 HeapWord* G1OffsetTableContigSpace::saved_mark_word() const {
1076 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1077 assert( _gc_time_stamp <= g1h->get_gc_time_stamp(), "invariant" );
1078 if (_gc_time_stamp < g1h->get_gc_time_stamp())
1079 return top();
1080 else
1081 return ContiguousSpace::saved_mark_word();
1082 }
1084 void G1OffsetTableContigSpace::record_top_and_timestamp() {
1085 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1086 unsigned curr_gc_time_stamp = g1h->get_gc_time_stamp();
1088 if (_gc_time_stamp < curr_gc_time_stamp) {
1089 // The order of these is important, as another thread might be
1090 // about to start scanning this region. If it does so after
1091 // set_saved_mark and before _gc_time_stamp = ..., then the latter
1092 // will be false, and it will pick up top() as the high water mark
1093 // of region. If it does so after _gc_time_stamp = ..., then it
1094 // will pick up the right saved_mark_word() as the high water mark
1095 // of the region. Either way, the behaviour will be correct.
1096 ContiguousSpace::set_saved_mark();
1097 OrderAccess::storestore();
1098 _gc_time_stamp = curr_gc_time_stamp;
1099 // No need to do another barrier to flush the writes above. If
1100 // this is called in parallel with other threads trying to
1101 // allocate into the region, the caller should call this while
1102 // holding a lock and when the lock is released the writes will be
1103 // flushed.
1104 }
1105 }
1107 G1OffsetTableContigSpace::
1108 G1OffsetTableContigSpace(G1BlockOffsetSharedArray* sharedOffsetArray,
1109 MemRegion mr) :
1110 _offsets(sharedOffsetArray, mr),
1111 _par_alloc_lock(Mutex::leaf, "OffsetTableContigSpace par alloc lock", true),
1112 _gc_time_stamp(0)
1113 {
1114 _offsets.set_space(this);
1115 // false ==> we'll do the clearing if there's clearing to be done.
1116 ContiguousSpace::initialize(mr, false, SpaceDecorator::Mangle);
1117 _offsets.zero_bottom_entry();
1118 _offsets.initialize_threshold();
1119 }