Fri, 18 Feb 2011 10:07:34 -0800
7020042: G1: Partially remove fix for 6994628
Summary: Disable reference discovery and processing during concurrent marking by disabling fix for 6994628.
Reviewed-by: tonyp, ysr
1 /*
2 * Copyright (c) 2001, 2011, 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 *
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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).
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.
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20 * or visit www.oracle.com if you need additional information or have any
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23 */
25 #include "precompiled.hpp"
26 #include "gc_implementation/g1/g1BlockOffsetTable.inline.hpp"
27 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
28 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
29 #include "gc_implementation/g1/heapRegion.inline.hpp"
30 #include "gc_implementation/g1/heapRegionRemSet.hpp"
31 #include "gc_implementation/g1/heapRegionSeq.inline.hpp"
32 #include "memory/genOopClosures.inline.hpp"
33 #include "memory/iterator.hpp"
34 #include "oops/oop.inline.hpp"
36 int HeapRegion::LogOfHRGrainBytes = 0;
37 int HeapRegion::LogOfHRGrainWords = 0;
38 int HeapRegion::GrainBytes = 0;
39 int HeapRegion::GrainWords = 0;
40 int HeapRegion::CardsPerRegion = 0;
42 HeapRegionDCTOC::HeapRegionDCTOC(G1CollectedHeap* g1,
43 HeapRegion* hr, OopClosure* cl,
44 CardTableModRefBS::PrecisionStyle precision,
45 FilterKind fk) :
46 ContiguousSpaceDCTOC(hr, cl, precision, NULL),
47 _hr(hr), _fk(fk), _g1(g1)
48 {}
50 FilterOutOfRegionClosure::FilterOutOfRegionClosure(HeapRegion* r,
51 OopClosure* oc) :
52 _r_bottom(r->bottom()), _r_end(r->end()),
53 _oc(oc), _out_of_region(0)
54 {}
56 class VerifyLiveClosure: public OopClosure {
57 private:
58 G1CollectedHeap* _g1h;
59 CardTableModRefBS* _bs;
60 oop _containing_obj;
61 bool _failures;
62 int _n_failures;
63 bool _use_prev_marking;
64 public:
65 // use_prev_marking == true -> use "prev" marking information,
66 // use_prev_marking == false -> use "next" marking information
67 VerifyLiveClosure(G1CollectedHeap* g1h, bool use_prev_marking) :
68 _g1h(g1h), _bs(NULL), _containing_obj(NULL),
69 _failures(false), _n_failures(0), _use_prev_marking(use_prev_marking)
70 {
71 BarrierSet* bs = _g1h->barrier_set();
72 if (bs->is_a(BarrierSet::CardTableModRef))
73 _bs = (CardTableModRefBS*)bs;
74 }
76 void set_containing_obj(oop obj) {
77 _containing_obj = obj;
78 }
80 bool failures() { return _failures; }
81 int n_failures() { return _n_failures; }
83 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
84 virtual void do_oop( oop* p) { do_oop_work(p); }
86 void print_object(outputStream* out, oop obj) {
87 #ifdef PRODUCT
88 klassOop k = obj->klass();
89 const char* class_name = instanceKlass::cast(k)->external_name();
90 out->print_cr("class name %s", class_name);
91 #else // PRODUCT
92 obj->print_on(out);
93 #endif // PRODUCT
94 }
96 template <class T> void do_oop_work(T* p) {
97 assert(_containing_obj != NULL, "Precondition");
98 assert(!_g1h->is_obj_dead_cond(_containing_obj, _use_prev_marking),
99 "Precondition");
100 T heap_oop = oopDesc::load_heap_oop(p);
101 if (!oopDesc::is_null(heap_oop)) {
102 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
103 bool failed = false;
104 if (!_g1h->is_in_closed_subset(obj) ||
105 _g1h->is_obj_dead_cond(obj, _use_prev_marking)) {
106 if (!_failures) {
107 gclog_or_tty->print_cr("");
108 gclog_or_tty->print_cr("----------");
109 }
110 if (!_g1h->is_in_closed_subset(obj)) {
111 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
112 gclog_or_tty->print_cr("Field "PTR_FORMAT
113 " of live obj "PTR_FORMAT" in region "
114 "["PTR_FORMAT", "PTR_FORMAT")",
115 p, (void*) _containing_obj,
116 from->bottom(), from->end());
117 print_object(gclog_or_tty, _containing_obj);
118 gclog_or_tty->print_cr("points to obj "PTR_FORMAT" not in the heap",
119 (void*) obj);
120 } else {
121 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
122 HeapRegion* to = _g1h->heap_region_containing((HeapWord*)obj);
123 gclog_or_tty->print_cr("Field "PTR_FORMAT
124 " of live obj "PTR_FORMAT" in region "
125 "["PTR_FORMAT", "PTR_FORMAT")",
126 p, (void*) _containing_obj,
127 from->bottom(), from->end());
128 print_object(gclog_or_tty, _containing_obj);
129 gclog_or_tty->print_cr("points to dead obj "PTR_FORMAT" in region "
130 "["PTR_FORMAT", "PTR_FORMAT")",
131 (void*) obj, to->bottom(), to->end());
132 print_object(gclog_or_tty, obj);
133 }
134 gclog_or_tty->print_cr("----------");
135 _failures = true;
136 failed = true;
137 _n_failures++;
138 }
140 if (!_g1h->full_collection()) {
141 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
142 HeapRegion* to = _g1h->heap_region_containing(obj);
143 if (from != NULL && to != NULL &&
144 from != to &&
145 !to->isHumongous()) {
146 jbyte cv_obj = *_bs->byte_for_const(_containing_obj);
147 jbyte cv_field = *_bs->byte_for_const(p);
148 const jbyte dirty = CardTableModRefBS::dirty_card_val();
150 bool is_bad = !(from->is_young()
151 || to->rem_set()->contains_reference(p)
152 || !G1HRRSFlushLogBuffersOnVerify && // buffers were not flushed
153 (_containing_obj->is_objArray() ?
154 cv_field == dirty
155 : cv_obj == dirty || cv_field == dirty));
156 if (is_bad) {
157 if (!_failures) {
158 gclog_or_tty->print_cr("");
159 gclog_or_tty->print_cr("----------");
160 }
161 gclog_or_tty->print_cr("Missing rem set entry:");
162 gclog_or_tty->print_cr("Field "PTR_FORMAT
163 " of obj "PTR_FORMAT
164 ", in region %d ["PTR_FORMAT
165 ", "PTR_FORMAT"),",
166 p, (void*) _containing_obj,
167 from->hrs_index(),
168 from->bottom(),
169 from->end());
170 _containing_obj->print_on(gclog_or_tty);
171 gclog_or_tty->print_cr("points to obj "PTR_FORMAT
172 " in region %d ["PTR_FORMAT
173 ", "PTR_FORMAT").",
174 (void*) obj, to->hrs_index(),
175 to->bottom(), to->end());
176 obj->print_on(gclog_or_tty);
177 gclog_or_tty->print_cr("Obj head CTE = %d, field CTE = %d.",
178 cv_obj, cv_field);
179 gclog_or_tty->print_cr("----------");
180 _failures = true;
181 if (!failed) _n_failures++;
182 }
183 }
184 }
185 }
186 }
187 };
189 template<class ClosureType>
190 HeapWord* walk_mem_region_loop(ClosureType* cl, G1CollectedHeap* g1h,
191 HeapRegion* hr,
192 HeapWord* cur, HeapWord* top) {
193 oop cur_oop = oop(cur);
194 int oop_size = cur_oop->size();
195 HeapWord* next_obj = cur + oop_size;
196 while (next_obj < top) {
197 // Keep filtering the remembered set.
198 if (!g1h->is_obj_dead(cur_oop, hr)) {
199 // Bottom lies entirely below top, so we can call the
200 // non-memRegion version of oop_iterate below.
201 cur_oop->oop_iterate(cl);
202 }
203 cur = next_obj;
204 cur_oop = oop(cur);
205 oop_size = cur_oop->size();
206 next_obj = cur + oop_size;
207 }
208 return cur;
209 }
211 void HeapRegionDCTOC::walk_mem_region_with_cl(MemRegion mr,
212 HeapWord* bottom,
213 HeapWord* top,
214 OopClosure* cl) {
215 G1CollectedHeap* g1h = _g1;
217 int oop_size;
219 OopClosure* cl2 = cl;
220 FilterIntoCSClosure intoCSFilt(this, g1h, cl);
221 FilterOutOfRegionClosure outOfRegionFilt(_hr, cl);
222 switch (_fk) {
223 case IntoCSFilterKind: cl2 = &intoCSFilt; break;
224 case OutOfRegionFilterKind: cl2 = &outOfRegionFilt; break;
225 }
227 // Start filtering what we add to the remembered set. If the object is
228 // not considered dead, either because it is marked (in the mark bitmap)
229 // or it was allocated after marking finished, then we add it. Otherwise
230 // we can safely ignore the object.
231 if (!g1h->is_obj_dead(oop(bottom), _hr)) {
232 oop_size = oop(bottom)->oop_iterate(cl2, mr);
233 } else {
234 oop_size = oop(bottom)->size();
235 }
237 bottom += oop_size;
239 if (bottom < top) {
240 // We replicate the loop below for several kinds of possible filters.
241 switch (_fk) {
242 case NoFilterKind:
243 bottom = walk_mem_region_loop(cl, g1h, _hr, bottom, top);
244 break;
245 case IntoCSFilterKind: {
246 FilterIntoCSClosure filt(this, g1h, cl);
247 bottom = walk_mem_region_loop(&filt, g1h, _hr, bottom, top);
248 break;
249 }
250 case OutOfRegionFilterKind: {
251 FilterOutOfRegionClosure filt(_hr, cl);
252 bottom = walk_mem_region_loop(&filt, g1h, _hr, bottom, top);
253 break;
254 }
255 default:
256 ShouldNotReachHere();
257 }
259 // Last object. Need to do dead-obj filtering here too.
260 if (!g1h->is_obj_dead(oop(bottom), _hr)) {
261 oop(bottom)->oop_iterate(cl2, mr);
262 }
263 }
264 }
266 // Minimum region size; we won't go lower than that.
267 // We might want to decrease this in the future, to deal with small
268 // heaps a bit more efficiently.
269 #define MIN_REGION_SIZE ( 1024 * 1024 )
271 // Maximum region size; we don't go higher than that. There's a good
272 // reason for having an upper bound. We don't want regions to get too
273 // large, otherwise cleanup's effectiveness would decrease as there
274 // will be fewer opportunities to find totally empty regions after
275 // marking.
276 #define MAX_REGION_SIZE ( 32 * 1024 * 1024 )
278 // The automatic region size calculation will try to have around this
279 // many regions in the heap (based on the min heap size).
280 #define TARGET_REGION_NUMBER 2048
282 void HeapRegion::setup_heap_region_size(uintx min_heap_size) {
283 // region_size in bytes
284 uintx region_size = G1HeapRegionSize;
285 if (FLAG_IS_DEFAULT(G1HeapRegionSize)) {
286 // We base the automatic calculation on the min heap size. This
287 // can be problematic if the spread between min and max is quite
288 // wide, imagine -Xms128m -Xmx32g. But, if we decided it based on
289 // the max size, the region size might be way too large for the
290 // min size. Either way, some users might have to set the region
291 // size manually for some -Xms / -Xmx combos.
293 region_size = MAX2(min_heap_size / TARGET_REGION_NUMBER,
294 (uintx) MIN_REGION_SIZE);
295 }
297 int region_size_log = log2_long((jlong) region_size);
298 // Recalculate the region size to make sure it's a power of
299 // 2. This means that region_size is the largest power of 2 that's
300 // <= what we've calculated so far.
301 region_size = ((uintx)1 << region_size_log);
303 // Now make sure that we don't go over or under our limits.
304 if (region_size < MIN_REGION_SIZE) {
305 region_size = MIN_REGION_SIZE;
306 } else if (region_size > MAX_REGION_SIZE) {
307 region_size = MAX_REGION_SIZE;
308 }
310 // And recalculate the log.
311 region_size_log = log2_long((jlong) region_size);
313 // Now, set up the globals.
314 guarantee(LogOfHRGrainBytes == 0, "we should only set it once");
315 LogOfHRGrainBytes = region_size_log;
317 guarantee(LogOfHRGrainWords == 0, "we should only set it once");
318 LogOfHRGrainWords = LogOfHRGrainBytes - LogHeapWordSize;
320 guarantee(GrainBytes == 0, "we should only set it once");
321 // The cast to int is safe, given that we've bounded region_size by
322 // MIN_REGION_SIZE and MAX_REGION_SIZE.
323 GrainBytes = (int) region_size;
325 guarantee(GrainWords == 0, "we should only set it once");
326 GrainWords = GrainBytes >> LogHeapWordSize;
327 guarantee(1 << LogOfHRGrainWords == GrainWords, "sanity");
329 guarantee(CardsPerRegion == 0, "we should only set it once");
330 CardsPerRegion = GrainBytes >> CardTableModRefBS::card_shift;
331 }
333 void HeapRegion::reset_after_compaction() {
334 G1OffsetTableContigSpace::reset_after_compaction();
335 // After a compaction the mark bitmap is invalid, so we must
336 // treat all objects as being inside the unmarked area.
337 zero_marked_bytes();
338 init_top_at_mark_start();
339 }
341 DirtyCardToOopClosure*
342 HeapRegion::new_dcto_closure(OopClosure* cl,
343 CardTableModRefBS::PrecisionStyle precision,
344 HeapRegionDCTOC::FilterKind fk) {
345 return new HeapRegionDCTOC(G1CollectedHeap::heap(),
346 this, cl, precision, fk);
347 }
349 void HeapRegion::hr_clear(bool par, bool clear_space) {
350 assert(_humongous_type == NotHumongous,
351 "we should have already filtered out humongous regions");
352 assert(_humongous_start_region == NULL,
353 "we should have already filtered out humongous regions");
354 assert(_end == _orig_end,
355 "we should have already filtered out humongous regions");
357 _in_collection_set = false;
358 _is_gc_alloc_region = false;
360 set_young_index_in_cset(-1);
361 uninstall_surv_rate_group();
362 set_young_type(NotYoung);
363 reset_pre_dummy_top();
365 if (!par) {
366 // If this is parallel, this will be done later.
367 HeapRegionRemSet* hrrs = rem_set();
368 if (hrrs != NULL) hrrs->clear();
369 _claimed = InitialClaimValue;
370 }
371 zero_marked_bytes();
372 set_sort_index(-1);
374 _offsets.resize(HeapRegion::GrainWords);
375 init_top_at_mark_start();
376 if (clear_space) clear(SpaceDecorator::Mangle);
377 }
379 // <PREDICTION>
380 void HeapRegion::calc_gc_efficiency() {
381 G1CollectedHeap* g1h = G1CollectedHeap::heap();
382 _gc_efficiency = (double) garbage_bytes() /
383 g1h->predict_region_elapsed_time_ms(this, false);
384 }
385 // </PREDICTION>
387 void HeapRegion::set_startsHumongous(HeapWord* new_top, HeapWord* new_end) {
388 assert(!isHumongous(), "sanity / pre-condition");
389 assert(end() == _orig_end,
390 "Should be normal before the humongous object allocation");
391 assert(top() == bottom(), "should be empty");
392 assert(bottom() <= new_top && new_top <= new_end, "pre-condition");
394 _humongous_type = StartsHumongous;
395 _humongous_start_region = this;
397 set_end(new_end);
398 _offsets.set_for_starts_humongous(new_top);
399 }
401 void HeapRegion::set_continuesHumongous(HeapRegion* first_hr) {
402 assert(!isHumongous(), "sanity / pre-condition");
403 assert(end() == _orig_end,
404 "Should be normal before the humongous object allocation");
405 assert(top() == bottom(), "should be empty");
406 assert(first_hr->startsHumongous(), "pre-condition");
408 _humongous_type = ContinuesHumongous;
409 _humongous_start_region = first_hr;
410 }
412 void HeapRegion::set_notHumongous() {
413 assert(isHumongous(), "pre-condition");
415 if (startsHumongous()) {
416 assert(top() <= end(), "pre-condition");
417 set_end(_orig_end);
418 if (top() > end()) {
419 // at least one "continues humongous" region after it
420 set_top(end());
421 }
422 } else {
423 // continues humongous
424 assert(end() == _orig_end, "sanity");
425 }
427 assert(capacity() == (size_t) HeapRegion::GrainBytes, "pre-condition");
428 _humongous_type = NotHumongous;
429 _humongous_start_region = NULL;
430 }
432 bool HeapRegion::claimHeapRegion(jint claimValue) {
433 jint current = _claimed;
434 if (current != claimValue) {
435 jint res = Atomic::cmpxchg(claimValue, &_claimed, current);
436 if (res == current) {
437 return true;
438 }
439 }
440 return false;
441 }
443 HeapWord* HeapRegion::next_block_start_careful(HeapWord* addr) {
444 HeapWord* low = addr;
445 HeapWord* high = end();
446 while (low < high) {
447 size_t diff = pointer_delta(high, low);
448 // Must add one below to bias toward the high amount. Otherwise, if
449 // "high" were at the desired value, and "low" were one less, we
450 // would not converge on "high". This is not symmetric, because
451 // we set "high" to a block start, which might be the right one,
452 // which we don't do for "low".
453 HeapWord* middle = low + (diff+1)/2;
454 if (middle == high) return high;
455 HeapWord* mid_bs = block_start_careful(middle);
456 if (mid_bs < addr) {
457 low = middle;
458 } else {
459 high = mid_bs;
460 }
461 }
462 assert(low == high && low >= addr, "Didn't work.");
463 return low;
464 }
466 void HeapRegion::initialize(MemRegion mr, bool clear_space, bool mangle_space) {
467 G1OffsetTableContigSpace::initialize(mr, false, mangle_space);
468 hr_clear(false/*par*/, clear_space);
469 }
470 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
471 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
472 #endif // _MSC_VER
475 HeapRegion::
476 HeapRegion(G1BlockOffsetSharedArray* sharedOffsetArray,
477 MemRegion mr, bool is_zeroed)
478 : G1OffsetTableContigSpace(sharedOffsetArray, mr, is_zeroed),
479 _next_fk(HeapRegionDCTOC::NoFilterKind),
480 _hrs_index(-1),
481 _humongous_type(NotHumongous), _humongous_start_region(NULL),
482 _in_collection_set(false), _is_gc_alloc_region(false),
483 _next_in_special_set(NULL), _orig_end(NULL),
484 _claimed(InitialClaimValue), _evacuation_failed(false),
485 _prev_marked_bytes(0), _next_marked_bytes(0), _sort_index(-1),
486 _young_type(NotYoung), _next_young_region(NULL),
487 _next_dirty_cards_region(NULL), _next(NULL), _pending_removal(false),
488 #ifdef ASSERT
489 _containing_set(NULL),
490 #endif // ASSERT
491 _young_index_in_cset(-1), _surv_rate_group(NULL), _age_index(-1),
492 _rem_set(NULL), _recorded_rs_length(0), _predicted_elapsed_time_ms(0),
493 _predicted_bytes_to_copy(0)
494 {
495 _orig_end = mr.end();
496 // Note that initialize() will set the start of the unmarked area of the
497 // region.
498 this->initialize(mr, !is_zeroed, SpaceDecorator::Mangle);
499 set_top(bottom());
500 set_saved_mark();
502 _rem_set = new HeapRegionRemSet(sharedOffsetArray, this);
504 assert(HeapRegionRemSet::num_par_rem_sets() > 0, "Invariant.");
505 // In case the region is allocated during a pause, note the top.
506 // We haven't done any counting on a brand new region.
507 _top_at_conc_mark_count = bottom();
508 }
510 class NextCompactionHeapRegionClosure: public HeapRegionClosure {
511 const HeapRegion* _target;
512 bool _target_seen;
513 HeapRegion* _last;
514 CompactibleSpace* _res;
515 public:
516 NextCompactionHeapRegionClosure(const HeapRegion* target) :
517 _target(target), _target_seen(false), _res(NULL) {}
518 bool doHeapRegion(HeapRegion* cur) {
519 if (_target_seen) {
520 if (!cur->isHumongous()) {
521 _res = cur;
522 return true;
523 }
524 } else if (cur == _target) {
525 _target_seen = true;
526 }
527 return false;
528 }
529 CompactibleSpace* result() { return _res; }
530 };
532 CompactibleSpace* HeapRegion::next_compaction_space() const {
533 G1CollectedHeap* g1h = G1CollectedHeap::heap();
534 // cast away const-ness
535 HeapRegion* r = (HeapRegion*) this;
536 NextCompactionHeapRegionClosure blk(r);
537 g1h->heap_region_iterate_from(r, &blk);
538 return blk.result();
539 }
541 void HeapRegion::save_marks() {
542 set_saved_mark();
543 }
545 void HeapRegion::oops_in_mr_iterate(MemRegion mr, OopClosure* cl) {
546 HeapWord* p = mr.start();
547 HeapWord* e = mr.end();
548 oop obj;
549 while (p < e) {
550 obj = oop(p);
551 p += obj->oop_iterate(cl);
552 }
553 assert(p == e, "bad memregion: doesn't end on obj boundary");
554 }
556 #define HeapRegion_OOP_SINCE_SAVE_MARKS_DEFN(OopClosureType, nv_suffix) \
557 void HeapRegion::oop_since_save_marks_iterate##nv_suffix(OopClosureType* cl) { \
558 ContiguousSpace::oop_since_save_marks_iterate##nv_suffix(cl); \
559 }
560 SPECIALIZED_SINCE_SAVE_MARKS_CLOSURES(HeapRegion_OOP_SINCE_SAVE_MARKS_DEFN)
563 void HeapRegion::oop_before_save_marks_iterate(OopClosure* cl) {
564 oops_in_mr_iterate(MemRegion(bottom(), saved_mark_word()), cl);
565 }
567 HeapWord*
568 HeapRegion::object_iterate_mem_careful(MemRegion mr,
569 ObjectClosure* cl) {
570 G1CollectedHeap* g1h = G1CollectedHeap::heap();
571 // We used to use "block_start_careful" here. But we're actually happy
572 // to update the BOT while we do this...
573 HeapWord* cur = block_start(mr.start());
574 mr = mr.intersection(used_region());
575 if (mr.is_empty()) return NULL;
576 // Otherwise, find the obj that extends onto mr.start().
578 assert(cur <= mr.start()
579 && (oop(cur)->klass_or_null() == NULL ||
580 cur + oop(cur)->size() > mr.start()),
581 "postcondition of block_start");
582 oop obj;
583 while (cur < mr.end()) {
584 obj = oop(cur);
585 if (obj->klass_or_null() == NULL) {
586 // Ran into an unparseable point.
587 return cur;
588 } else if (!g1h->is_obj_dead(obj)) {
589 cl->do_object(obj);
590 }
591 if (cl->abort()) return cur;
592 // The check above must occur before the operation below, since an
593 // abort might invalidate the "size" operation.
594 cur += obj->size();
595 }
596 return NULL;
597 }
599 HeapWord*
600 HeapRegion::
601 oops_on_card_seq_iterate_careful(MemRegion mr,
602 FilterOutOfRegionClosure* cl,
603 bool filter_young) {
604 G1CollectedHeap* g1h = G1CollectedHeap::heap();
606 // If we're within a stop-world GC, then we might look at a card in a
607 // GC alloc region that extends onto a GC LAB, which may not be
608 // parseable. Stop such at the "saved_mark" of the region.
609 if (G1CollectedHeap::heap()->is_gc_active()) {
610 mr = mr.intersection(used_region_at_save_marks());
611 } else {
612 mr = mr.intersection(used_region());
613 }
614 if (mr.is_empty()) return NULL;
615 // Otherwise, find the obj that extends onto mr.start().
617 // The intersection of the incoming mr (for the card) and the
618 // allocated part of the region is non-empty. This implies that
619 // we have actually allocated into this region. The code in
620 // G1CollectedHeap.cpp that allocates a new region sets the
621 // is_young tag on the region before allocating. Thus we
622 // safely know if this region is young.
623 if (is_young() && filter_young) {
624 return NULL;
625 }
627 assert(!is_young(), "check value of filter_young");
629 // We used to use "block_start_careful" here. But we're actually happy
630 // to update the BOT while we do this...
631 HeapWord* cur = block_start(mr.start());
632 assert(cur <= mr.start(), "Postcondition");
634 while (cur <= mr.start()) {
635 if (oop(cur)->klass_or_null() == NULL) {
636 // Ran into an unparseable point.
637 return cur;
638 }
639 // Otherwise...
640 int sz = oop(cur)->size();
641 if (cur + sz > mr.start()) break;
642 // Otherwise, go on.
643 cur = cur + sz;
644 }
645 oop obj;
646 obj = oop(cur);
647 // If we finish this loop...
648 assert(cur <= mr.start()
649 && obj->klass_or_null() != NULL
650 && cur + obj->size() > mr.start(),
651 "Loop postcondition");
652 if (!g1h->is_obj_dead(obj)) {
653 obj->oop_iterate(cl, mr);
654 }
656 HeapWord* next;
657 while (cur < mr.end()) {
658 obj = oop(cur);
659 if (obj->klass_or_null() == NULL) {
660 // Ran into an unparseable point.
661 return cur;
662 };
663 // Otherwise:
664 next = (cur + obj->size());
665 if (!g1h->is_obj_dead(obj)) {
666 if (next < mr.end()) {
667 obj->oop_iterate(cl);
668 } else {
669 // this obj spans the boundary. If it's an array, stop at the
670 // boundary.
671 if (obj->is_objArray()) {
672 obj->oop_iterate(cl, mr);
673 } else {
674 obj->oop_iterate(cl);
675 }
676 }
677 }
678 cur = next;
679 }
680 return NULL;
681 }
683 void HeapRegion::print() const { print_on(gclog_or_tty); }
684 void HeapRegion::print_on(outputStream* st) const {
685 if (isHumongous()) {
686 if (startsHumongous())
687 st->print(" HS");
688 else
689 st->print(" HC");
690 } else {
691 st->print(" ");
692 }
693 if (in_collection_set())
694 st->print(" CS");
695 else if (is_gc_alloc_region())
696 st->print(" A ");
697 else
698 st->print(" ");
699 if (is_young())
700 st->print(is_survivor() ? " SU" : " Y ");
701 else
702 st->print(" ");
703 if (is_empty())
704 st->print(" F");
705 else
706 st->print(" ");
707 st->print(" %5d", _gc_time_stamp);
708 st->print(" PTAMS "PTR_FORMAT" NTAMS "PTR_FORMAT,
709 prev_top_at_mark_start(), next_top_at_mark_start());
710 G1OffsetTableContigSpace::print_on(st);
711 }
713 void HeapRegion::verify(bool allow_dirty) const {
714 bool dummy = false;
715 verify(allow_dirty, /* use_prev_marking */ true, /* failures */ &dummy);
716 }
718 // This really ought to be commoned up into OffsetTableContigSpace somehow.
719 // We would need a mechanism to make that code skip dead objects.
721 void HeapRegion::verify(bool allow_dirty,
722 bool use_prev_marking,
723 bool* failures) const {
724 G1CollectedHeap* g1 = G1CollectedHeap::heap();
725 *failures = false;
726 HeapWord* p = bottom();
727 HeapWord* prev_p = NULL;
728 VerifyLiveClosure vl_cl(g1, use_prev_marking);
729 bool is_humongous = isHumongous();
730 bool do_bot_verify = !is_young();
731 size_t object_num = 0;
732 while (p < top()) {
733 oop obj = oop(p);
734 size_t obj_size = obj->size();
735 object_num += 1;
737 if (is_humongous != g1->isHumongous(obj_size)) {
738 gclog_or_tty->print_cr("obj "PTR_FORMAT" is of %shumongous size ("
739 SIZE_FORMAT" words) in a %shumongous region",
740 p, g1->isHumongous(obj_size) ? "" : "non-",
741 obj_size, is_humongous ? "" : "non-");
742 *failures = true;
743 return;
744 }
746 // If it returns false, verify_for_object() will output the
747 // appropriate messasge.
748 if (do_bot_verify && !_offsets.verify_for_object(p, obj_size)) {
749 *failures = true;
750 return;
751 }
753 if (!g1->is_obj_dead_cond(obj, this, use_prev_marking)) {
754 if (obj->is_oop()) {
755 klassOop klass = obj->klass();
756 if (!klass->is_perm()) {
757 gclog_or_tty->print_cr("klass "PTR_FORMAT" of object "PTR_FORMAT" "
758 "not in perm", klass, obj);
759 *failures = true;
760 return;
761 } else if (!klass->is_klass()) {
762 gclog_or_tty->print_cr("klass "PTR_FORMAT" of object "PTR_FORMAT" "
763 "not a klass", klass, obj);
764 *failures = true;
765 return;
766 } else {
767 vl_cl.set_containing_obj(obj);
768 obj->oop_iterate(&vl_cl);
769 if (vl_cl.failures()) {
770 *failures = true;
771 }
772 if (G1MaxVerifyFailures >= 0 &&
773 vl_cl.n_failures() >= G1MaxVerifyFailures) {
774 return;
775 }
776 }
777 } else {
778 gclog_or_tty->print_cr(PTR_FORMAT" no an oop", obj);
779 *failures = true;
780 return;
781 }
782 }
783 prev_p = p;
784 p += obj_size;
785 }
787 if (p != top()) {
788 gclog_or_tty->print_cr("end of last object "PTR_FORMAT" "
789 "does not match top "PTR_FORMAT, p, top());
790 *failures = true;
791 return;
792 }
794 HeapWord* the_end = end();
795 assert(p == top(), "it should still hold");
796 // Do some extra BOT consistency checking for addresses in the
797 // range [top, end). BOT look-ups in this range should yield
798 // top. No point in doing that if top == end (there's nothing there).
799 if (p < the_end) {
800 // Look up top
801 HeapWord* addr_1 = p;
802 HeapWord* b_start_1 = _offsets.block_start_const(addr_1);
803 if (b_start_1 != p) {
804 gclog_or_tty->print_cr("BOT look up for top: "PTR_FORMAT" "
805 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
806 addr_1, b_start_1, p);
807 *failures = true;
808 return;
809 }
811 // Look up top + 1
812 HeapWord* addr_2 = p + 1;
813 if (addr_2 < the_end) {
814 HeapWord* b_start_2 = _offsets.block_start_const(addr_2);
815 if (b_start_2 != p) {
816 gclog_or_tty->print_cr("BOT look up for top + 1: "PTR_FORMAT" "
817 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
818 addr_2, b_start_2, p);
819 *failures = true;
820 return;
821 }
822 }
824 // Look up an address between top and end
825 size_t diff = pointer_delta(the_end, p) / 2;
826 HeapWord* addr_3 = p + diff;
827 if (addr_3 < the_end) {
828 HeapWord* b_start_3 = _offsets.block_start_const(addr_3);
829 if (b_start_3 != p) {
830 gclog_or_tty->print_cr("BOT look up for top + diff: "PTR_FORMAT" "
831 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
832 addr_3, b_start_3, p);
833 *failures = true;
834 return;
835 }
836 }
838 // Loook up end - 1
839 HeapWord* addr_4 = the_end - 1;
840 HeapWord* b_start_4 = _offsets.block_start_const(addr_4);
841 if (b_start_4 != p) {
842 gclog_or_tty->print_cr("BOT look up for end - 1: "PTR_FORMAT" "
843 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
844 addr_4, b_start_4, p);
845 *failures = true;
846 return;
847 }
848 }
850 if (is_humongous && object_num > 1) {
851 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] is humongous "
852 "but has "SIZE_FORMAT", objects",
853 bottom(), end(), object_num);
854 *failures = true;
855 return;
856 }
857 }
859 // G1OffsetTableContigSpace code; copied from space.cpp. Hope this can go
860 // away eventually.
862 void G1OffsetTableContigSpace::initialize(MemRegion mr, bool clear_space, bool mangle_space) {
863 // false ==> we'll do the clearing if there's clearing to be done.
864 ContiguousSpace::initialize(mr, false, mangle_space);
865 _offsets.zero_bottom_entry();
866 _offsets.initialize_threshold();
867 if (clear_space) clear(mangle_space);
868 }
870 void G1OffsetTableContigSpace::clear(bool mangle_space) {
871 ContiguousSpace::clear(mangle_space);
872 _offsets.zero_bottom_entry();
873 _offsets.initialize_threshold();
874 }
876 void G1OffsetTableContigSpace::set_bottom(HeapWord* new_bottom) {
877 Space::set_bottom(new_bottom);
878 _offsets.set_bottom(new_bottom);
879 }
881 void G1OffsetTableContigSpace::set_end(HeapWord* new_end) {
882 Space::set_end(new_end);
883 _offsets.resize(new_end - bottom());
884 }
886 void G1OffsetTableContigSpace::print() const {
887 print_short();
888 gclog_or_tty->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", "
889 INTPTR_FORMAT ", " INTPTR_FORMAT ")",
890 bottom(), top(), _offsets.threshold(), end());
891 }
893 HeapWord* G1OffsetTableContigSpace::initialize_threshold() {
894 return _offsets.initialize_threshold();
895 }
897 HeapWord* G1OffsetTableContigSpace::cross_threshold(HeapWord* start,
898 HeapWord* end) {
899 _offsets.alloc_block(start, end);
900 return _offsets.threshold();
901 }
903 HeapWord* G1OffsetTableContigSpace::saved_mark_word() const {
904 G1CollectedHeap* g1h = G1CollectedHeap::heap();
905 assert( _gc_time_stamp <= g1h->get_gc_time_stamp(), "invariant" );
906 if (_gc_time_stamp < g1h->get_gc_time_stamp())
907 return top();
908 else
909 return ContiguousSpace::saved_mark_word();
910 }
912 void G1OffsetTableContigSpace::set_saved_mark() {
913 G1CollectedHeap* g1h = G1CollectedHeap::heap();
914 unsigned curr_gc_time_stamp = g1h->get_gc_time_stamp();
916 if (_gc_time_stamp < curr_gc_time_stamp) {
917 // The order of these is important, as another thread might be
918 // about to start scanning this region. If it does so after
919 // set_saved_mark and before _gc_time_stamp = ..., then the latter
920 // will be false, and it will pick up top() as the high water mark
921 // of region. If it does so after _gc_time_stamp = ..., then it
922 // will pick up the right saved_mark_word() as the high water mark
923 // of the region. Either way, the behaviour will be correct.
924 ContiguousSpace::set_saved_mark();
925 OrderAccess::storestore();
926 _gc_time_stamp = curr_gc_time_stamp;
927 // No need to do another barrier to flush the writes above. If
928 // this is called in parallel with other threads trying to
929 // allocate into the region, the caller should call this while
930 // holding a lock and when the lock is released the writes will be
931 // flushed.
932 }
933 }
935 G1OffsetTableContigSpace::
936 G1OffsetTableContigSpace(G1BlockOffsetSharedArray* sharedOffsetArray,
937 MemRegion mr, bool is_zeroed) :
938 _offsets(sharedOffsetArray, mr),
939 _par_alloc_lock(Mutex::leaf, "OffsetTableContigSpace par alloc lock", true),
940 _gc_time_stamp(0)
941 {
942 _offsets.set_space(this);
943 initialize(mr, !is_zeroed, SpaceDecorator::Mangle);
944 }