Mon, 21 Jul 2014 10:00:31 +0200
8048112: G1 Full GC needs to support the case when the very first region is not available
Summary: Refactor preparation for compaction during Full GC so that it lazily initializes the first compaction point. This also avoids problems later when the first region may not be committed. Also reviewed by K. Barrett.
Reviewed-by: brutisso
1 /*
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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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 "gc_implementation/shared/liveRange.hpp"
34 #include "memory/genOopClosures.inline.hpp"
35 #include "memory/iterator.hpp"
36 #include "memory/space.inline.hpp"
37 #include "oops/oop.inline.hpp"
38 #include "runtime/orderAccess.inline.hpp"
40 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
42 int HeapRegion::LogOfHRGrainBytes = 0;
43 int HeapRegion::LogOfHRGrainWords = 0;
44 size_t HeapRegion::GrainBytes = 0;
45 size_t HeapRegion::GrainWords = 0;
46 size_t HeapRegion::CardsPerRegion = 0;
48 HeapRegionDCTOC::HeapRegionDCTOC(G1CollectedHeap* g1,
49 HeapRegion* hr, ExtendedOopClosure* cl,
50 CardTableModRefBS::PrecisionStyle precision,
51 FilterKind fk) :
52 DirtyCardToOopClosure(hr, cl, precision, NULL),
53 _hr(hr), _fk(fk), _g1(g1) { }
55 FilterOutOfRegionClosure::FilterOutOfRegionClosure(HeapRegion* r,
56 OopClosure* oc) :
57 _r_bottom(r->bottom()), _r_end(r->end()), _oc(oc) { }
59 template<class ClosureType>
60 HeapWord* walk_mem_region_loop(ClosureType* cl, G1CollectedHeap* g1h,
61 HeapRegion* hr,
62 HeapWord* cur, HeapWord* top) {
63 oop cur_oop = oop(cur);
64 size_t oop_size = hr->block_size(cur);
65 HeapWord* next_obj = cur + oop_size;
66 while (next_obj < top) {
67 // Keep filtering the remembered set.
68 if (!g1h->is_obj_dead(cur_oop, hr)) {
69 // Bottom lies entirely below top, so we can call the
70 // non-memRegion version of oop_iterate below.
71 cur_oop->oop_iterate(cl);
72 }
73 cur = next_obj;
74 cur_oop = oop(cur);
75 oop_size = hr->block_size(cur);
76 next_obj = cur + oop_size;
77 }
78 return cur;
79 }
81 void HeapRegionDCTOC::walk_mem_region(MemRegion mr,
82 HeapWord* bottom,
83 HeapWord* top) {
84 G1CollectedHeap* g1h = _g1;
85 size_t oop_size;
86 ExtendedOopClosure* cl2 = NULL;
88 FilterIntoCSClosure intoCSFilt(this, g1h, _cl);
89 FilterOutOfRegionClosure outOfRegionFilt(_hr, _cl);
91 switch (_fk) {
92 case NoFilterKind: cl2 = _cl; break;
93 case IntoCSFilterKind: cl2 = &intoCSFilt; break;
94 case OutOfRegionFilterKind: cl2 = &outOfRegionFilt; break;
95 default: ShouldNotReachHere();
96 }
98 // Start filtering what we add to the remembered set. If the object is
99 // not considered dead, either because it is marked (in the mark bitmap)
100 // or it was allocated after marking finished, then we add it. Otherwise
101 // we can safely ignore the object.
102 if (!g1h->is_obj_dead(oop(bottom), _hr)) {
103 oop_size = oop(bottom)->oop_iterate(cl2, mr);
104 } else {
105 oop_size = _hr->block_size(bottom);
106 }
108 bottom += oop_size;
110 if (bottom < top) {
111 // We replicate the loop below for several kinds of possible filters.
112 switch (_fk) {
113 case NoFilterKind:
114 bottom = walk_mem_region_loop(_cl, g1h, _hr, bottom, top);
115 break;
117 case IntoCSFilterKind: {
118 FilterIntoCSClosure filt(this, g1h, _cl);
119 bottom = walk_mem_region_loop(&filt, g1h, _hr, bottom, top);
120 break;
121 }
123 case OutOfRegionFilterKind: {
124 FilterOutOfRegionClosure filt(_hr, _cl);
125 bottom = walk_mem_region_loop(&filt, g1h, _hr, bottom, top);
126 break;
127 }
129 default:
130 ShouldNotReachHere();
131 }
133 // Last object. Need to do dead-obj filtering here too.
134 if (!g1h->is_obj_dead(oop(bottom), _hr)) {
135 oop(bottom)->oop_iterate(cl2, mr);
136 }
137 }
138 }
140 // Minimum region size; we won't go lower than that.
141 // We might want to decrease this in the future, to deal with small
142 // heaps a bit more efficiently.
143 #define MIN_REGION_SIZE ( 1024 * 1024 )
145 // Maximum region size; we don't go higher than that. There's a good
146 // reason for having an upper bound. We don't want regions to get too
147 // large, otherwise cleanup's effectiveness would decrease as there
148 // will be fewer opportunities to find totally empty regions after
149 // marking.
150 #define MAX_REGION_SIZE ( 32 * 1024 * 1024 )
152 // The automatic region size calculation will try to have around this
153 // many regions in the heap (based on the min heap size).
154 #define TARGET_REGION_NUMBER 2048
156 size_t HeapRegion::max_region_size() {
157 return (size_t)MAX_REGION_SIZE;
158 }
160 void HeapRegion::setup_heap_region_size(size_t initial_heap_size, size_t max_heap_size) {
161 uintx region_size = G1HeapRegionSize;
162 if (FLAG_IS_DEFAULT(G1HeapRegionSize)) {
163 size_t average_heap_size = (initial_heap_size + max_heap_size) / 2;
164 region_size = MAX2(average_heap_size / TARGET_REGION_NUMBER,
165 (uintx) MIN_REGION_SIZE);
166 }
168 int region_size_log = log2_long((jlong) region_size);
169 // Recalculate the region size to make sure it's a power of
170 // 2. This means that region_size is the largest power of 2 that's
171 // <= what we've calculated so far.
172 region_size = ((uintx)1 << region_size_log);
174 // Now make sure that we don't go over or under our limits.
175 if (region_size < MIN_REGION_SIZE) {
176 region_size = MIN_REGION_SIZE;
177 } else if (region_size > MAX_REGION_SIZE) {
178 region_size = MAX_REGION_SIZE;
179 }
181 // And recalculate the log.
182 region_size_log = log2_long((jlong) region_size);
184 // Now, set up the globals.
185 guarantee(LogOfHRGrainBytes == 0, "we should only set it once");
186 LogOfHRGrainBytes = region_size_log;
188 guarantee(LogOfHRGrainWords == 0, "we should only set it once");
189 LogOfHRGrainWords = LogOfHRGrainBytes - LogHeapWordSize;
191 guarantee(GrainBytes == 0, "we should only set it once");
192 // The cast to int is safe, given that we've bounded region_size by
193 // MIN_REGION_SIZE and MAX_REGION_SIZE.
194 GrainBytes = (size_t)region_size;
196 guarantee(GrainWords == 0, "we should only set it once");
197 GrainWords = GrainBytes >> LogHeapWordSize;
198 guarantee((size_t) 1 << LogOfHRGrainWords == GrainWords, "sanity");
200 guarantee(CardsPerRegion == 0, "we should only set it once");
201 CardsPerRegion = GrainBytes >> CardTableModRefBS::card_shift;
202 }
204 void HeapRegion::reset_after_compaction() {
205 G1OffsetTableContigSpace::reset_after_compaction();
206 // After a compaction the mark bitmap is invalid, so we must
207 // treat all objects as being inside the unmarked area.
208 zero_marked_bytes();
209 init_top_at_mark_start();
210 }
212 void HeapRegion::hr_clear(bool par, bool clear_space, bool locked) {
213 assert(_humongous_type == NotHumongous,
214 "we should have already filtered out humongous regions");
215 assert(_humongous_start_region == NULL,
216 "we should have already filtered out humongous regions");
217 assert(_end == _orig_end,
218 "we should have already filtered out humongous regions");
220 _in_collection_set = false;
222 set_young_index_in_cset(-1);
223 uninstall_surv_rate_group();
224 set_young_type(NotYoung);
225 reset_pre_dummy_top();
227 if (!par) {
228 // If this is parallel, this will be done later.
229 HeapRegionRemSet* hrrs = rem_set();
230 if (locked) {
231 hrrs->clear_locked();
232 } else {
233 hrrs->clear();
234 }
235 _claimed = InitialClaimValue;
236 }
237 zero_marked_bytes();
239 _offsets.resize(HeapRegion::GrainWords);
240 init_top_at_mark_start();
241 if (clear_space) clear(SpaceDecorator::Mangle);
242 }
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 }
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();
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 }
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");
275 _humongous_type = StartsHumongous;
276 _humongous_start_region = this;
278 set_end(new_end);
279 _offsets.set_for_starts_humongous(new_top);
280 }
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");
289 _humongous_type = ContinuesHumongous;
290 _humongous_start_region = first_hr;
291 }
293 void HeapRegion::set_notHumongous() {
294 assert(isHumongous(), "pre-condition");
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 }
308 assert(capacity() == HeapRegion::GrainBytes, "pre-condition");
309 _humongous_type = NotHumongous;
310 _humongous_start_region = NULL;
311 }
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 }
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 }
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
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), _prev(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 record_top_and_timestamp();
379 assert(HeapRegionRemSet::num_par_rem_sets() > 0, "Invariant.");
380 }
382 CompactibleSpace* HeapRegion::next_compaction_space() const {
383 return G1CollectedHeap::heap()->next_compaction_region(this);
384 }
386 void HeapRegion::note_self_forwarding_removal_start(bool during_initial_mark,
387 bool during_conc_mark) {
388 // We always recreate the prev marking info and we'll explicitly
389 // mark all objects we find to be self-forwarded on the prev
390 // bitmap. So all objects need to be below PTAMS.
391 _prev_marked_bytes = 0;
393 if (during_initial_mark) {
394 // During initial-mark, we'll also explicitly mark all objects
395 // we find to be self-forwarded on the next bitmap. So all
396 // objects need to be below NTAMS.
397 _next_top_at_mark_start = top();
398 _next_marked_bytes = 0;
399 } else if (during_conc_mark) {
400 // During concurrent mark, all objects in the CSet (including
401 // the ones we find to be self-forwarded) are implicitly live.
402 // So all objects need to be above NTAMS.
403 _next_top_at_mark_start = bottom();
404 _next_marked_bytes = 0;
405 }
406 }
408 void HeapRegion::note_self_forwarding_removal_end(bool during_initial_mark,
409 bool during_conc_mark,
410 size_t marked_bytes) {
411 assert(0 <= marked_bytes && marked_bytes <= used(),
412 err_msg("marked: "SIZE_FORMAT" used: "SIZE_FORMAT,
413 marked_bytes, used()));
414 _prev_top_at_mark_start = top();
415 _prev_marked_bytes = marked_bytes;
416 }
418 HeapWord*
419 HeapRegion::object_iterate_mem_careful(MemRegion mr,
420 ObjectClosure* cl) {
421 G1CollectedHeap* g1h = G1CollectedHeap::heap();
422 // We used to use "block_start_careful" here. But we're actually happy
423 // to update the BOT while we do this...
424 HeapWord* cur = block_start(mr.start());
425 mr = mr.intersection(used_region());
426 if (mr.is_empty()) return NULL;
427 // Otherwise, find the obj that extends onto mr.start().
429 assert(cur <= mr.start()
430 && (oop(cur)->klass_or_null() == NULL ||
431 cur + oop(cur)->size() > mr.start()),
432 "postcondition of block_start");
433 oop obj;
434 while (cur < mr.end()) {
435 obj = oop(cur);
436 if (obj->klass_or_null() == NULL) {
437 // Ran into an unparseable point.
438 return cur;
439 } else if (!g1h->is_obj_dead(obj)) {
440 cl->do_object(obj);
441 }
442 if (cl->abort()) return cur;
443 // The check above must occur before the operation below, since an
444 // abort might invalidate the "size" operation.
445 cur += block_size(cur);
446 }
447 return NULL;
448 }
450 HeapWord*
451 HeapRegion::
452 oops_on_card_seq_iterate_careful(MemRegion mr,
453 FilterOutOfRegionClosure* cl,
454 bool filter_young,
455 jbyte* card_ptr) {
456 // Currently, we should only have to clean the card if filter_young
457 // is true and vice versa.
458 if (filter_young) {
459 assert(card_ptr != NULL, "pre-condition");
460 } else {
461 assert(card_ptr == NULL, "pre-condition");
462 }
463 G1CollectedHeap* g1h = G1CollectedHeap::heap();
465 // If we're within a stop-world GC, then we might look at a card in a
466 // GC alloc region that extends onto a GC LAB, which may not be
467 // parseable. Stop such at the "saved_mark" of the region.
468 if (g1h->is_gc_active()) {
469 mr = mr.intersection(used_region_at_save_marks());
470 } else {
471 mr = mr.intersection(used_region());
472 }
473 if (mr.is_empty()) return NULL;
474 // Otherwise, find the obj that extends onto mr.start().
476 // The intersection of the incoming mr (for the card) and the
477 // allocated part of the region is non-empty. This implies that
478 // we have actually allocated into this region. The code in
479 // G1CollectedHeap.cpp that allocates a new region sets the
480 // is_young tag on the region before allocating. Thus we
481 // safely know if this region is young.
482 if (is_young() && filter_young) {
483 return NULL;
484 }
486 assert(!is_young(), "check value of filter_young");
488 // We can only clean the card here, after we make the decision that
489 // the card is not young. And we only clean the card if we have been
490 // asked to (i.e., card_ptr != NULL).
491 if (card_ptr != NULL) {
492 *card_ptr = CardTableModRefBS::clean_card_val();
493 // We must complete this write before we do any of the reads below.
494 OrderAccess::storeload();
495 }
497 // Cache the boundaries of the memory region in some const locals
498 HeapWord* const start = mr.start();
499 HeapWord* const end = mr.end();
501 // We used to use "block_start_careful" here. But we're actually happy
502 // to update the BOT while we do this...
503 HeapWord* cur = block_start(start);
504 assert(cur <= start, "Postcondition");
506 oop obj;
508 HeapWord* next = cur;
509 while (next <= start) {
510 cur = next;
511 obj = oop(cur);
512 if (obj->klass_or_null() == NULL) {
513 // Ran into an unparseable point.
514 return cur;
515 }
516 // Otherwise...
517 next = cur + block_size(cur);
518 }
520 // If we finish the above loop...We have a parseable object that
521 // begins on or before the start of the memory region, and ends
522 // inside or spans the entire region.
524 assert(obj == oop(cur), "sanity");
525 assert(cur <= start, "Loop postcondition");
526 assert(obj->klass_or_null() != NULL, "Loop postcondition");
527 assert((cur + block_size(cur)) > start, "Loop postcondition");
529 if (!g1h->is_obj_dead(obj)) {
530 obj->oop_iterate(cl, mr);
531 }
533 while (cur < end) {
534 obj = oop(cur);
535 if (obj->klass_or_null() == NULL) {
536 // Ran into an unparseable point.
537 return cur;
538 };
540 // Otherwise:
541 next = cur + block_size(cur);
543 if (!g1h->is_obj_dead(obj)) {
544 if (next < end || !obj->is_objArray()) {
545 // This object either does not span the MemRegion
546 // boundary, or if it does it's not an array.
547 // Apply closure to whole object.
548 obj->oop_iterate(cl);
549 } else {
550 // This obj is an array that spans the boundary.
551 // Stop at the boundary.
552 obj->oop_iterate(cl, mr);
553 }
554 }
555 cur = next;
556 }
557 return NULL;
558 }
560 // Code roots support
562 void HeapRegion::add_strong_code_root(nmethod* nm) {
563 HeapRegionRemSet* hrrs = rem_set();
564 hrrs->add_strong_code_root(nm);
565 }
567 void HeapRegion::remove_strong_code_root(nmethod* nm) {
568 HeapRegionRemSet* hrrs = rem_set();
569 hrrs->remove_strong_code_root(nm);
570 }
572 void HeapRegion::migrate_strong_code_roots() {
573 assert(in_collection_set(), "only collection set regions");
574 assert(!isHumongous(),
575 err_msg("humongous region "HR_FORMAT" should not have been added to collection set",
576 HR_FORMAT_PARAMS(this)));
578 HeapRegionRemSet* hrrs = rem_set();
579 hrrs->migrate_strong_code_roots();
580 }
582 void HeapRegion::strong_code_roots_do(CodeBlobClosure* blk) const {
583 HeapRegionRemSet* hrrs = rem_set();
584 hrrs->strong_code_roots_do(blk);
585 }
587 class VerifyStrongCodeRootOopClosure: public OopClosure {
588 const HeapRegion* _hr;
589 nmethod* _nm;
590 bool _failures;
591 bool _has_oops_in_region;
593 template <class T> void do_oop_work(T* p) {
594 T heap_oop = oopDesc::load_heap_oop(p);
595 if (!oopDesc::is_null(heap_oop)) {
596 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
598 // Note: not all the oops embedded in the nmethod are in the
599 // current region. We only look at those which are.
600 if (_hr->is_in(obj)) {
601 // Object is in the region. Check that its less than top
602 if (_hr->top() <= (HeapWord*)obj) {
603 // Object is above top
604 gclog_or_tty->print_cr("Object "PTR_FORMAT" in region "
605 "["PTR_FORMAT", "PTR_FORMAT") is above "
606 "top "PTR_FORMAT,
607 (void *)obj, _hr->bottom(), _hr->end(), _hr->top());
608 _failures = true;
609 return;
610 }
611 // Nmethod has at least one oop in the current region
612 _has_oops_in_region = true;
613 }
614 }
615 }
617 public:
618 VerifyStrongCodeRootOopClosure(const HeapRegion* hr, nmethod* nm):
619 _hr(hr), _failures(false), _has_oops_in_region(false) {}
621 void do_oop(narrowOop* p) { do_oop_work(p); }
622 void do_oop(oop* p) { do_oop_work(p); }
624 bool failures() { return _failures; }
625 bool has_oops_in_region() { return _has_oops_in_region; }
626 };
628 class VerifyStrongCodeRootCodeBlobClosure: public CodeBlobClosure {
629 const HeapRegion* _hr;
630 bool _failures;
631 public:
632 VerifyStrongCodeRootCodeBlobClosure(const HeapRegion* hr) :
633 _hr(hr), _failures(false) {}
635 void do_code_blob(CodeBlob* cb) {
636 nmethod* nm = (cb == NULL) ? NULL : cb->as_nmethod_or_null();
637 if (nm != NULL) {
638 // Verify that the nemthod is live
639 if (!nm->is_alive()) {
640 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] has dead nmethod "
641 PTR_FORMAT" in its strong code roots",
642 _hr->bottom(), _hr->end(), nm);
643 _failures = true;
644 } else {
645 VerifyStrongCodeRootOopClosure oop_cl(_hr, nm);
646 nm->oops_do(&oop_cl);
647 if (!oop_cl.has_oops_in_region()) {
648 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] has nmethod "
649 PTR_FORMAT" in its strong code roots "
650 "with no pointers into region",
651 _hr->bottom(), _hr->end(), nm);
652 _failures = true;
653 } else if (oop_cl.failures()) {
654 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] has other "
655 "failures for nmethod "PTR_FORMAT,
656 _hr->bottom(), _hr->end(), nm);
657 _failures = true;
658 }
659 }
660 }
661 }
663 bool failures() { return _failures; }
664 };
666 void HeapRegion::verify_strong_code_roots(VerifyOption vo, bool* failures) const {
667 if (!G1VerifyHeapRegionCodeRoots) {
668 // We're not verifying code roots.
669 return;
670 }
671 if (vo == VerifyOption_G1UseMarkWord) {
672 // Marking verification during a full GC is performed after class
673 // unloading, code cache unloading, etc so the strong code roots
674 // attached to each heap region are in an inconsistent state. They won't
675 // be consistent until the strong code roots are rebuilt after the
676 // actual GC. Skip verifying the strong code roots in this particular
677 // time.
678 assert(VerifyDuringGC, "only way to get here");
679 return;
680 }
682 HeapRegionRemSet* hrrs = rem_set();
683 size_t strong_code_roots_length = hrrs->strong_code_roots_list_length();
685 // if this region is empty then there should be no entries
686 // on its strong code root list
687 if (is_empty()) {
688 if (strong_code_roots_length > 0) {
689 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] is empty "
690 "but has "SIZE_FORMAT" code root entries",
691 bottom(), end(), strong_code_roots_length);
692 *failures = true;
693 }
694 return;
695 }
697 if (continuesHumongous()) {
698 if (strong_code_roots_length > 0) {
699 gclog_or_tty->print_cr("region "HR_FORMAT" is a continuation of a humongous "
700 "region but has "SIZE_FORMAT" code root entries",
701 HR_FORMAT_PARAMS(this), strong_code_roots_length);
702 *failures = true;
703 }
704 return;
705 }
707 VerifyStrongCodeRootCodeBlobClosure cb_cl(this);
708 strong_code_roots_do(&cb_cl);
710 if (cb_cl.failures()) {
711 *failures = true;
712 }
713 }
715 void HeapRegion::print() const { print_on(gclog_or_tty); }
716 void HeapRegion::print_on(outputStream* st) const {
717 if (isHumongous()) {
718 if (startsHumongous())
719 st->print(" HS");
720 else
721 st->print(" HC");
722 } else {
723 st->print(" ");
724 }
725 if (in_collection_set())
726 st->print(" CS");
727 else
728 st->print(" ");
729 if (is_young())
730 st->print(is_survivor() ? " SU" : " Y ");
731 else
732 st->print(" ");
733 if (is_empty())
734 st->print(" F");
735 else
736 st->print(" ");
737 st->print(" TS %5d", _gc_time_stamp);
738 st->print(" PTAMS "PTR_FORMAT" NTAMS "PTR_FORMAT,
739 prev_top_at_mark_start(), next_top_at_mark_start());
740 G1OffsetTableContigSpace::print_on(st);
741 }
743 class VerifyLiveClosure: public OopClosure {
744 private:
745 G1CollectedHeap* _g1h;
746 CardTableModRefBS* _bs;
747 oop _containing_obj;
748 bool _failures;
749 int _n_failures;
750 VerifyOption _vo;
751 public:
752 // _vo == UsePrevMarking -> use "prev" marking information,
753 // _vo == UseNextMarking -> use "next" marking information,
754 // _vo == UseMarkWord -> use mark word from object header.
755 VerifyLiveClosure(G1CollectedHeap* g1h, VerifyOption vo) :
756 _g1h(g1h), _bs(NULL), _containing_obj(NULL),
757 _failures(false), _n_failures(0), _vo(vo)
758 {
759 BarrierSet* bs = _g1h->barrier_set();
760 if (bs->is_a(BarrierSet::CardTableModRef))
761 _bs = (CardTableModRefBS*)bs;
762 }
764 void set_containing_obj(oop obj) {
765 _containing_obj = obj;
766 }
768 bool failures() { return _failures; }
769 int n_failures() { return _n_failures; }
771 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
772 virtual void do_oop( oop* p) { do_oop_work(p); }
774 void print_object(outputStream* out, oop obj) {
775 #ifdef PRODUCT
776 Klass* k = obj->klass();
777 const char* class_name = InstanceKlass::cast(k)->external_name();
778 out->print_cr("class name %s", class_name);
779 #else // PRODUCT
780 obj->print_on(out);
781 #endif // PRODUCT
782 }
784 template <class T>
785 void do_oop_work(T* p) {
786 assert(_containing_obj != NULL, "Precondition");
787 assert(!_g1h->is_obj_dead_cond(_containing_obj, _vo),
788 "Precondition");
789 T heap_oop = oopDesc::load_heap_oop(p);
790 if (!oopDesc::is_null(heap_oop)) {
791 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
792 bool failed = false;
793 if (!_g1h->is_in_closed_subset(obj) || _g1h->is_obj_dead_cond(obj, _vo)) {
794 MutexLockerEx x(ParGCRareEvent_lock,
795 Mutex::_no_safepoint_check_flag);
797 if (!_failures) {
798 gclog_or_tty->cr();
799 gclog_or_tty->print_cr("----------");
800 }
801 if (!_g1h->is_in_closed_subset(obj)) {
802 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
803 gclog_or_tty->print_cr("Field "PTR_FORMAT
804 " of live obj "PTR_FORMAT" in region "
805 "["PTR_FORMAT", "PTR_FORMAT")",
806 p, (void*) _containing_obj,
807 from->bottom(), from->end());
808 print_object(gclog_or_tty, _containing_obj);
809 gclog_or_tty->print_cr("points to obj "PTR_FORMAT" not in the heap",
810 (void*) obj);
811 } else {
812 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
813 HeapRegion* to = _g1h->heap_region_containing((HeapWord*)obj);
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 dead obj "PTR_FORMAT" in region "
821 "["PTR_FORMAT", "PTR_FORMAT")",
822 (void*) obj, to->bottom(), to->end());
823 print_object(gclog_or_tty, obj);
824 }
825 gclog_or_tty->print_cr("----------");
826 gclog_or_tty->flush();
827 _failures = true;
828 failed = true;
829 _n_failures++;
830 }
832 if (!_g1h->full_collection() || G1VerifyRSetsDuringFullGC) {
833 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
834 HeapRegion* to = _g1h->heap_region_containing(obj);
835 if (from != NULL && to != NULL &&
836 from != to &&
837 !to->isHumongous()) {
838 jbyte cv_obj = *_bs->byte_for_const(_containing_obj);
839 jbyte cv_field = *_bs->byte_for_const(p);
840 const jbyte dirty = CardTableModRefBS::dirty_card_val();
842 bool is_bad = !(from->is_young()
843 || to->rem_set()->contains_reference(p)
844 || !G1HRRSFlushLogBuffersOnVerify && // buffers were not flushed
845 (_containing_obj->is_objArray() ?
846 cv_field == dirty
847 : cv_obj == dirty || cv_field == dirty));
848 if (is_bad) {
849 MutexLockerEx x(ParGCRareEvent_lock,
850 Mutex::_no_safepoint_check_flag);
852 if (!_failures) {
853 gclog_or_tty->cr();
854 gclog_or_tty->print_cr("----------");
855 }
856 gclog_or_tty->print_cr("Missing rem set entry:");
857 gclog_or_tty->print_cr("Field "PTR_FORMAT" "
858 "of obj "PTR_FORMAT", "
859 "in region "HR_FORMAT,
860 p, (void*) _containing_obj,
861 HR_FORMAT_PARAMS(from));
862 _containing_obj->print_on(gclog_or_tty);
863 gclog_or_tty->print_cr("points to obj "PTR_FORMAT" "
864 "in region "HR_FORMAT,
865 (void*) obj,
866 HR_FORMAT_PARAMS(to));
867 obj->print_on(gclog_or_tty);
868 gclog_or_tty->print_cr("Obj head CTE = %d, field CTE = %d.",
869 cv_obj, cv_field);
870 gclog_or_tty->print_cr("----------");
871 gclog_or_tty->flush();
872 _failures = true;
873 if (!failed) _n_failures++;
874 }
875 }
876 }
877 }
878 }
879 };
881 // This really ought to be commoned up into OffsetTableContigSpace somehow.
882 // We would need a mechanism to make that code skip dead objects.
884 void HeapRegion::verify(VerifyOption vo,
885 bool* failures) const {
886 G1CollectedHeap* g1 = G1CollectedHeap::heap();
887 *failures = false;
888 HeapWord* p = bottom();
889 HeapWord* prev_p = NULL;
890 VerifyLiveClosure vl_cl(g1, vo);
891 bool is_humongous = isHumongous();
892 bool do_bot_verify = !is_young();
893 size_t object_num = 0;
894 while (p < top()) {
895 oop obj = oop(p);
896 size_t obj_size = block_size(p);
897 object_num += 1;
899 if (is_humongous != g1->isHumongous(obj_size) &&
900 !g1->is_obj_dead(obj, this)) { // Dead objects may have bigger block_size since they span several objects.
901 gclog_or_tty->print_cr("obj "PTR_FORMAT" is of %shumongous size ("
902 SIZE_FORMAT" words) in a %shumongous region",
903 p, g1->isHumongous(obj_size) ? "" : "non-",
904 obj_size, is_humongous ? "" : "non-");
905 *failures = true;
906 return;
907 }
909 // If it returns false, verify_for_object() will output the
910 // appropriate messasge.
911 if (do_bot_verify &&
912 !g1->is_obj_dead(obj, this) &&
913 !_offsets.verify_for_object(p, obj_size)) {
914 *failures = true;
915 return;
916 }
918 if (!g1->is_obj_dead_cond(obj, this, vo)) {
919 if (obj->is_oop()) {
920 Klass* klass = obj->klass();
921 bool is_metaspace_object = Metaspace::contains(klass) ||
922 (vo == VerifyOption_G1UsePrevMarking &&
923 ClassLoaderDataGraph::unload_list_contains(klass));
924 if (!is_metaspace_object) {
925 gclog_or_tty->print_cr("klass "PTR_FORMAT" of object "PTR_FORMAT" "
926 "not metadata", klass, (void *)obj);
927 *failures = true;
928 return;
929 } else if (!klass->is_klass()) {
930 gclog_or_tty->print_cr("klass "PTR_FORMAT" of object "PTR_FORMAT" "
931 "not a klass", klass, (void *)obj);
932 *failures = true;
933 return;
934 } else {
935 vl_cl.set_containing_obj(obj);
936 obj->oop_iterate_no_header(&vl_cl);
937 if (vl_cl.failures()) {
938 *failures = true;
939 }
940 if (G1MaxVerifyFailures >= 0 &&
941 vl_cl.n_failures() >= G1MaxVerifyFailures) {
942 return;
943 }
944 }
945 } else {
946 gclog_or_tty->print_cr(PTR_FORMAT" no an oop", (void *)obj);
947 *failures = true;
948 return;
949 }
950 }
951 prev_p = p;
952 p += obj_size;
953 }
955 if (p != top()) {
956 gclog_or_tty->print_cr("end of last object "PTR_FORMAT" "
957 "does not match top "PTR_FORMAT, p, top());
958 *failures = true;
959 return;
960 }
962 HeapWord* the_end = end();
963 assert(p == top(), "it should still hold");
964 // Do some extra BOT consistency checking for addresses in the
965 // range [top, end). BOT look-ups in this range should yield
966 // top. No point in doing that if top == end (there's nothing there).
967 if (p < the_end) {
968 // Look up top
969 HeapWord* addr_1 = p;
970 HeapWord* b_start_1 = _offsets.block_start_const(addr_1);
971 if (b_start_1 != p) {
972 gclog_or_tty->print_cr("BOT look up for top: "PTR_FORMAT" "
973 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
974 addr_1, b_start_1, p);
975 *failures = true;
976 return;
977 }
979 // Look up top + 1
980 HeapWord* addr_2 = p + 1;
981 if (addr_2 < the_end) {
982 HeapWord* b_start_2 = _offsets.block_start_const(addr_2);
983 if (b_start_2 != p) {
984 gclog_or_tty->print_cr("BOT look up for top + 1: "PTR_FORMAT" "
985 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
986 addr_2, b_start_2, p);
987 *failures = true;
988 return;
989 }
990 }
992 // Look up an address between top and end
993 size_t diff = pointer_delta(the_end, p) / 2;
994 HeapWord* addr_3 = p + diff;
995 if (addr_3 < the_end) {
996 HeapWord* b_start_3 = _offsets.block_start_const(addr_3);
997 if (b_start_3 != p) {
998 gclog_or_tty->print_cr("BOT look up for top + diff: "PTR_FORMAT" "
999 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
1000 addr_3, b_start_3, p);
1001 *failures = true;
1002 return;
1003 }
1004 }
1006 // Loook up end - 1
1007 HeapWord* addr_4 = the_end - 1;
1008 HeapWord* b_start_4 = _offsets.block_start_const(addr_4);
1009 if (b_start_4 != p) {
1010 gclog_or_tty->print_cr("BOT look up for end - 1: "PTR_FORMAT" "
1011 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
1012 addr_4, b_start_4, p);
1013 *failures = true;
1014 return;
1015 }
1016 }
1018 if (is_humongous && object_num > 1) {
1019 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] is humongous "
1020 "but has "SIZE_FORMAT", objects",
1021 bottom(), end(), object_num);
1022 *failures = true;
1023 return;
1024 }
1026 verify_strong_code_roots(vo, failures);
1027 }
1029 void HeapRegion::verify() const {
1030 bool dummy = false;
1031 verify(VerifyOption_G1UsePrevMarking, /* failures */ &dummy);
1032 }
1034 // G1OffsetTableContigSpace code; copied from space.cpp. Hope this can go
1035 // away eventually.
1037 void G1OffsetTableContigSpace::clear(bool mangle_space) {
1038 set_top(bottom());
1039 set_saved_mark_word(bottom());
1040 CompactibleSpace::clear(mangle_space);
1041 _offsets.zero_bottom_entry();
1042 _offsets.initialize_threshold();
1043 }
1045 void G1OffsetTableContigSpace::set_bottom(HeapWord* new_bottom) {
1046 Space::set_bottom(new_bottom);
1047 _offsets.set_bottom(new_bottom);
1048 }
1050 void G1OffsetTableContigSpace::set_end(HeapWord* new_end) {
1051 Space::set_end(new_end);
1052 _offsets.resize(new_end - bottom());
1053 }
1055 void G1OffsetTableContigSpace::print() const {
1056 print_short();
1057 gclog_or_tty->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", "
1058 INTPTR_FORMAT ", " INTPTR_FORMAT ")",
1059 bottom(), top(), _offsets.threshold(), end());
1060 }
1062 HeapWord* G1OffsetTableContigSpace::initialize_threshold() {
1063 return _offsets.initialize_threshold();
1064 }
1066 HeapWord* G1OffsetTableContigSpace::cross_threshold(HeapWord* start,
1067 HeapWord* end) {
1068 _offsets.alloc_block(start, end);
1069 return _offsets.threshold();
1070 }
1072 HeapWord* G1OffsetTableContigSpace::saved_mark_word() const {
1073 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1074 assert( _gc_time_stamp <= g1h->get_gc_time_stamp(), "invariant" );
1075 if (_gc_time_stamp < g1h->get_gc_time_stamp())
1076 return top();
1077 else
1078 return Space::saved_mark_word();
1079 }
1081 void G1OffsetTableContigSpace::record_top_and_timestamp() {
1082 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1083 unsigned curr_gc_time_stamp = g1h->get_gc_time_stamp();
1085 if (_gc_time_stamp < curr_gc_time_stamp) {
1086 // The order of these is important, as another thread might be
1087 // about to start scanning this region. If it does so after
1088 // set_saved_mark and before _gc_time_stamp = ..., then the latter
1089 // will be false, and it will pick up top() as the high water mark
1090 // of region. If it does so after _gc_time_stamp = ..., then it
1091 // will pick up the right saved_mark_word() as the high water mark
1092 // of the region. Either way, the behaviour will be correct.
1093 Space::set_saved_mark_word(top());
1094 OrderAccess::storestore();
1095 _gc_time_stamp = curr_gc_time_stamp;
1096 // No need to do another barrier to flush the writes above. If
1097 // this is called in parallel with other threads trying to
1098 // allocate into the region, the caller should call this while
1099 // holding a lock and when the lock is released the writes will be
1100 // flushed.
1101 }
1102 }
1104 void G1OffsetTableContigSpace::safe_object_iterate(ObjectClosure* blk) {
1105 object_iterate(blk);
1106 }
1108 void G1OffsetTableContigSpace::object_iterate(ObjectClosure* blk) {
1109 HeapWord* p = bottom();
1110 while (p < top()) {
1111 if (block_is_obj(p)) {
1112 blk->do_object(oop(p));
1113 }
1114 p += block_size(p);
1115 }
1116 }
1118 #define block_is_always_obj(q) true
1119 void G1OffsetTableContigSpace::prepare_for_compaction(CompactPoint* cp) {
1120 SCAN_AND_FORWARD(cp, top, block_is_always_obj, block_size);
1121 }
1122 #undef block_is_always_obj
1124 G1OffsetTableContigSpace::
1125 G1OffsetTableContigSpace(G1BlockOffsetSharedArray* sharedOffsetArray,
1126 MemRegion mr) :
1127 _offsets(sharedOffsetArray, mr),
1128 _par_alloc_lock(Mutex::leaf, "OffsetTableContigSpace par alloc lock", true),
1129 _gc_time_stamp(0)
1130 {
1131 _offsets.set_space(this);
1132 // false ==> we'll do the clearing if there's clearing to be done.
1133 CompactibleSpace::initialize(mr, false, SpaceDecorator::Mangle);
1134 _top = bottom();
1135 _offsets.zero_bottom_entry();
1136 _offsets.initialize_threshold();
1137 }