1 /*
2 * Copyright (c) 2001, 2013, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "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"
35
36 int HeapRegion::LogOfHRGrainBytes = 0;
37 int HeapRegion::LogOfHRGrainWords = 0;
38 size_t HeapRegion::GrainBytes = 0;
39 size_t HeapRegion::GrainWords = 0;
40 size_t HeapRegion::CardsPerRegion = 0;
41
42 HeapRegionDCTOC::HeapRegionDCTOC(G1CollectedHeap* g1,
43 HeapRegion* hr, ExtendedOopClosure* cl,
44 CardTableModRefBS::PrecisionStyle precision,
45 FilterKind fk) :
46 ContiguousSpaceDCTOC(hr, cl, precision, NULL),
47 _hr(hr), _fk(fk), _g1(g1) { }
48
49 FilterOutOfRegionClosure::FilterOutOfRegionClosure(HeapRegion* r,
50 OopClosure* oc) :
51 _r_bottom(r->bottom()), _r_end(r->end()), _oc(oc) { }
52
53 class VerifyLiveClosure: public OopClosure {
54 private:
55 G1CollectedHeap* _g1h;
56 CardTableModRefBS* _bs;
57 oop _containing_obj;
58 bool _failures;
59 int _n_failures;
60 VerifyOption _vo;
61 public:
62 // _vo == UsePrevMarking -> use "prev" marking information,
63 // _vo == UseNextMarking -> use "next" marking information,
64 // _vo == UseMarkWord -> use mark word from object header.
65 VerifyLiveClosure(G1CollectedHeap* g1h, VerifyOption vo) :
66 _g1h(g1h), _bs(NULL), _containing_obj(NULL),
67 _failures(false), _n_failures(0), _vo(vo)
68 {
69 BarrierSet* bs = _g1h->barrier_set();
70 if (bs->is_a(BarrierSet::CardTableModRef))
71 _bs = (CardTableModRefBS*)bs;
72 }
73
74 void set_containing_obj(oop obj) {
75 _containing_obj = obj;
76 }
77
78 bool failures() { return _failures; }
79 int n_failures() { return _n_failures; }
80
81 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
82 virtual void do_oop( oop* p) { do_oop_work(p); }
83
84 void print_object(outputStream* out, oop obj) {
85 #ifdef PRODUCT
86 Klass* k = obj->klass();
87 const char* class_name = InstanceKlass::cast(k)->external_name();
88 out->print_cr("class name %s", class_name);
89 #else // PRODUCT
90 obj->print_on(out);
91 #endif // PRODUCT
92 }
93
94 template <class T>
95 void do_oop_work(T* p) {
96 assert(_containing_obj != NULL, "Precondition");
97 assert(!_g1h->is_obj_dead_cond(_containing_obj, _vo),
98 "Precondition");
99 T heap_oop = oopDesc::load_heap_oop(p);
100 if (!oopDesc::is_null(heap_oop)) {
101 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
102 bool failed = false;
103 if (!_g1h->is_in_closed_subset(obj) || _g1h->is_obj_dead_cond(obj, _vo)) {
104 MutexLockerEx x(ParGCRareEvent_lock,
105 Mutex::_no_safepoint_check_flag);
106
107 if (!_failures) {
108 gclog_or_tty->print_cr("");
109 gclog_or_tty->print_cr("----------");
110 }
111 if (!_g1h->is_in_closed_subset(obj)) {
112 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
113 gclog_or_tty->print_cr("Field "PTR_FORMAT
114 " of live obj "PTR_FORMAT" in region "
115 "["PTR_FORMAT", "PTR_FORMAT")",
116 p, (void*) _containing_obj,
117 from->bottom(), from->end());
118 print_object(gclog_or_tty, _containing_obj);
119 gclog_or_tty->print_cr("points to obj "PTR_FORMAT" not in the heap",
120 (void*) obj);
121 } else {
122 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
123 HeapRegion* to = _g1h->heap_region_containing((HeapWord*)obj);
124 gclog_or_tty->print_cr("Field "PTR_FORMAT
125 " of live obj "PTR_FORMAT" in region "
126 "["PTR_FORMAT", "PTR_FORMAT")",
127 p, (void*) _containing_obj,
128 from->bottom(), from->end());
129 print_object(gclog_or_tty, _containing_obj);
130 gclog_or_tty->print_cr("points to dead obj "PTR_FORMAT" in region "
131 "["PTR_FORMAT", "PTR_FORMAT")",
132 (void*) obj, to->bottom(), to->end());
133 print_object(gclog_or_tty, obj);
134 }
135 gclog_or_tty->print_cr("----------");
136 gclog_or_tty->flush();
137 _failures = true;
138 failed = true;
139 _n_failures++;
140 }
141
142 if (!_g1h->full_collection()) {
143 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
144 HeapRegion* to = _g1h->heap_region_containing(obj);
145 if (from != NULL && to != NULL &&
146 from != to &&
147 !to->isHumongous()) {
148 jbyte cv_obj = *_bs->byte_for_const(_containing_obj);
149 jbyte cv_field = *_bs->byte_for_const(p);
150 const jbyte dirty = CardTableModRefBS::dirty_card_val();
151
152 bool is_bad = !(from->is_young()
153 || to->rem_set()->contains_reference(p)
154 || !G1HRRSFlushLogBuffersOnVerify && // buffers were not flushed
155 (_containing_obj->is_objArray() ?
156 cv_field == dirty
157 : cv_obj == dirty || cv_field == dirty));
158 if (is_bad) {
159 MutexLockerEx x(ParGCRareEvent_lock,
160 Mutex::_no_safepoint_check_flag);
161
162 if (!_failures) {
163 gclog_or_tty->print_cr("");
164 gclog_or_tty->print_cr("----------");
165 }
166 gclog_or_tty->print_cr("Missing rem set entry:");
167 gclog_or_tty->print_cr("Field "PTR_FORMAT" "
168 "of obj "PTR_FORMAT", "
169 "in region "HR_FORMAT,
170 p, (void*) _containing_obj,
171 HR_FORMAT_PARAMS(from));
172 _containing_obj->print_on(gclog_or_tty);
173 gclog_or_tty->print_cr("points to obj "PTR_FORMAT" "
174 "in region "HR_FORMAT,
175 (void*) obj,
176 HR_FORMAT_PARAMS(to));
177 obj->print_on(gclog_or_tty);
178 gclog_or_tty->print_cr("Obj head CTE = %d, field CTE = %d.",
179 cv_obj, cv_field);
180 gclog_or_tty->print_cr("----------");
181 gclog_or_tty->flush();
182 _failures = true;
183 if (!failed) _n_failures++;
184 }
185 }
186 }
187 }
188 }
189 };
190
191 template<class ClosureType>
192 HeapWord* walk_mem_region_loop(ClosureType* cl, G1CollectedHeap* g1h,
193 HeapRegion* hr,
194 HeapWord* cur, HeapWord* top) {
195 oop cur_oop = oop(cur);
196 int oop_size = cur_oop->size();
197 HeapWord* next_obj = cur + oop_size;
198 while (next_obj < top) {
199 // Keep filtering the remembered set.
200 if (!g1h->is_obj_dead(cur_oop, hr)) {
201 // Bottom lies entirely below top, so we can call the
202 // non-memRegion version of oop_iterate below.
203 cur_oop->oop_iterate(cl);
204 }
205 cur = next_obj;
206 cur_oop = oop(cur);
207 oop_size = cur_oop->size();
208 next_obj = cur + oop_size;
209 }
210 return cur;
211 }
212
213 void HeapRegionDCTOC::walk_mem_region_with_cl(MemRegion mr,
214 HeapWord* bottom,
215 HeapWord* top,
216 ExtendedOopClosure* cl) {
217 G1CollectedHeap* g1h = _g1;
218 int oop_size;
219 ExtendedOopClosure* cl2 = NULL;
220
221 FilterIntoCSClosure intoCSFilt(this, g1h, cl);
222 FilterOutOfRegionClosure outOfRegionFilt(_hr, cl);
223
224 switch (_fk) {
225 case NoFilterKind: cl2 = cl; break;
226 case IntoCSFilterKind: cl2 = &intoCSFilt; break;
227 case OutOfRegionFilterKind: cl2 = &outOfRegionFilt; break;
228 default: ShouldNotReachHere();
229 }
230
231 // Start filtering what we add to the remembered set. If the object is
232 // not considered dead, either because it is marked (in the mark bitmap)
233 // or it was allocated after marking finished, then we add it. Otherwise
234 // we can safely ignore the object.
235 if (!g1h->is_obj_dead(oop(bottom), _hr)) {
236 oop_size = oop(bottom)->oop_iterate(cl2, mr);
237 } else {
238 oop_size = oop(bottom)->size();
239 }
240
241 bottom += oop_size;
242
243 if (bottom < top) {
244 // We replicate the loop below for several kinds of possible filters.
245 switch (_fk) {
246 case NoFilterKind:
247 bottom = walk_mem_region_loop(cl, g1h, _hr, bottom, top);
248 break;
249
250 case IntoCSFilterKind: {
251 FilterIntoCSClosure filt(this, g1h, cl);
252 bottom = walk_mem_region_loop(&filt, g1h, _hr, bottom, top);
253 break;
254 }
255
256 case OutOfRegionFilterKind: {
257 FilterOutOfRegionClosure filt(_hr, cl);
258 bottom = walk_mem_region_loop(&filt, g1h, _hr, bottom, top);
259 break;
260 }
261
262 default:
263 ShouldNotReachHere();
264 }
265
266 // Last object. Need to do dead-obj filtering here too.
267 if (!g1h->is_obj_dead(oop(bottom), _hr)) {
268 oop(bottom)->oop_iterate(cl2, mr);
269 }
270 }
271 }
272
273 // Minimum region size; we won't go lower than that.
274 // We might want to decrease this in the future, to deal with small
275 // heaps a bit more efficiently.
276 #define MIN_REGION_SIZE ( 1024 * 1024 )
277
278 // Maximum region size; we don't go higher than that. There's a good
279 // reason for having an upper bound. We don't want regions to get too
280 // large, otherwise cleanup's effectiveness would decrease as there
281 // will be fewer opportunities to find totally empty regions after
282 // marking.
283 #define MAX_REGION_SIZE ( 32 * 1024 * 1024 )
284
285 // The automatic region size calculation will try to have around this
286 // many regions in the heap (based on the min heap size).
287 #define TARGET_REGION_NUMBER 2048
288
289 size_t HeapRegion::max_heap_alignment() {
290 return (size_t) MAX_REGION_SIZE;
291 }
292
293 void HeapRegion::setup_heap_region_size(uintx min_heap_size) {
294 // region_size in bytes
295 uintx region_size = G1HeapRegionSize;
296 if (FLAG_IS_DEFAULT(G1HeapRegionSize)) {
297 // We base the automatic calculation on the min heap size. This
298 // can be problematic if the spread between min and max is quite
299 // wide, imagine -Xms128m -Xmx32g. But, if we decided it based on
300 // the max size, the region size might be way too large for the
301 // min size. Either way, some users might have to set the region
302 // size manually for some -Xms / -Xmx combos.
303
304 region_size = MAX2(min_heap_size / TARGET_REGION_NUMBER,
305 (uintx) MIN_REGION_SIZE);
306 }
307
308 int region_size_log = log2_long((jlong) region_size);
309 // Recalculate the region size to make sure it's a power of
310 // 2. This means that region_size is the largest power of 2 that's
311 // <= what we've calculated so far.
312 region_size = ((uintx)1 << region_size_log);
313
314 // Now make sure that we don't go over or under our limits.
315 if (region_size < MIN_REGION_SIZE) {
316 region_size = MIN_REGION_SIZE;
317 } else if (region_size > MAX_REGION_SIZE) {
318 region_size = MAX_REGION_SIZE;
319 }
320
321 // And recalculate the log.
322 region_size_log = log2_long((jlong) region_size);
323
324 // Now, set up the globals.
325 guarantee(LogOfHRGrainBytes == 0, "we should only set it once");
326 LogOfHRGrainBytes = region_size_log;
327
328 guarantee(LogOfHRGrainWords == 0, "we should only set it once");
329 LogOfHRGrainWords = LogOfHRGrainBytes - LogHeapWordSize;
330
331 guarantee(GrainBytes == 0, "we should only set it once");
332 // The cast to int is safe, given that we've bounded region_size by
333 // MIN_REGION_SIZE and MAX_REGION_SIZE.
334 GrainBytes = (size_t)region_size;
335
336 guarantee(GrainWords == 0, "we should only set it once");
337 GrainWords = GrainBytes >> LogHeapWordSize;
338 guarantee((size_t) 1 << LogOfHRGrainWords == GrainWords, "sanity");
339
340 guarantee(CardsPerRegion == 0, "we should only set it once");
341 CardsPerRegion = GrainBytes >> CardTableModRefBS::card_shift;
342 }
343
344 void HeapRegion::reset_after_compaction() {
345 G1OffsetTableContigSpace::reset_after_compaction();
346 // After a compaction the mark bitmap is invalid, so we must
347 // treat all objects as being inside the unmarked area.
348 zero_marked_bytes();
349 init_top_at_mark_start();
350 }
351
352 void HeapRegion::hr_clear(bool par, bool clear_space) {
353 assert(_humongous_type == NotHumongous,
354 "we should have already filtered out humongous regions");
355 assert(_humongous_start_region == NULL,
356 "we should have already filtered out humongous regions");
357 assert(_end == _orig_end,
358 "we should have already filtered out humongous regions");
359
360 _in_collection_set = false;
361
362 set_young_index_in_cset(-1);
363 uninstall_surv_rate_group();
364 set_young_type(NotYoung);
365 reset_pre_dummy_top();
366
367 if (!par) {
368 // If this is parallel, this will be done later.
369 HeapRegionRemSet* hrrs = rem_set();
370 if (hrrs != NULL) hrrs->clear();
371 _claimed = InitialClaimValue;
372 }
373 zero_marked_bytes();
374
375 _offsets.resize(HeapRegion::GrainWords);
376 init_top_at_mark_start();
377 if (clear_space) clear(SpaceDecorator::Mangle);
378 }
379
380 void HeapRegion::par_clear() {
381 assert(used() == 0, "the region should have been already cleared");
382 assert(capacity() == HeapRegion::GrainBytes, "should be back to normal");
383 HeapRegionRemSet* hrrs = rem_set();
384 hrrs->clear();
385 CardTableModRefBS* ct_bs =
386 (CardTableModRefBS*)G1CollectedHeap::heap()->barrier_set();
387 ct_bs->clear(MemRegion(bottom(), end()));
388 }
389
390 void HeapRegion::calc_gc_efficiency() {
391 // GC efficiency is the ratio of how much space would be
392 // reclaimed over how long we predict it would take to reclaim it.
393 G1CollectedHeap* g1h = G1CollectedHeap::heap();
394 G1CollectorPolicy* g1p = g1h->g1_policy();
395
396 // Retrieve a prediction of the elapsed time for this region for
397 // a mixed gc because the region will only be evacuated during a
398 // mixed gc.
399 double region_elapsed_time_ms =
400 g1p->predict_region_elapsed_time_ms(this, false /* for_young_gc */);
401 _gc_efficiency = (double) reclaimable_bytes() / region_elapsed_time_ms;
402 }
403
404 void HeapRegion::set_startsHumongous(HeapWord* new_top, HeapWord* new_end) {
405 assert(!isHumongous(), "sanity / pre-condition");
406 assert(end() == _orig_end,
407 "Should be normal before the humongous object allocation");
408 assert(top() == bottom(), "should be empty");
409 assert(bottom() <= new_top && new_top <= new_end, "pre-condition");
410
411 _humongous_type = StartsHumongous;
412 _humongous_start_region = this;
413
414 set_end(new_end);
415 _offsets.set_for_starts_humongous(new_top);
416 }
417
418 void HeapRegion::set_continuesHumongous(HeapRegion* first_hr) {
419 assert(!isHumongous(), "sanity / pre-condition");
420 assert(end() == _orig_end,
421 "Should be normal before the humongous object allocation");
422 assert(top() == bottom(), "should be empty");
423 assert(first_hr->startsHumongous(), "pre-condition");
424
425 _humongous_type = ContinuesHumongous;
426 _humongous_start_region = first_hr;
427 }
428
429 void HeapRegion::set_notHumongous() {
430 assert(isHumongous(), "pre-condition");
431
432 if (startsHumongous()) {
433 assert(top() <= end(), "pre-condition");
434 set_end(_orig_end);
435 if (top() > end()) {
436 // at least one "continues humongous" region after it
437 set_top(end());
438 }
439 } else {
440 // continues humongous
441 assert(end() == _orig_end, "sanity");
442 }
443
444 assert(capacity() == HeapRegion::GrainBytes, "pre-condition");
445 _humongous_type = NotHumongous;
446 _humongous_start_region = NULL;
447 }
448
449 bool HeapRegion::claimHeapRegion(jint claimValue) {
450 jint current = _claimed;
451 if (current != claimValue) {
452 jint res = Atomic::cmpxchg(claimValue, &_claimed, current);
453 if (res == current) {
454 return true;
455 }
456 }
457 return false;
458 }
459
460 HeapWord* HeapRegion::next_block_start_careful(HeapWord* addr) {
461 HeapWord* low = addr;
462 HeapWord* high = end();
463 while (low < high) {
464 size_t diff = pointer_delta(high, low);
465 // Must add one below to bias toward the high amount. Otherwise, if
466 // "high" were at the desired value, and "low" were one less, we
467 // would not converge on "high". This is not symmetric, because
468 // we set "high" to a block start, which might be the right one,
469 // which we don't do for "low".
470 HeapWord* middle = low + (diff+1)/2;
471 if (middle == high) return high;
472 HeapWord* mid_bs = block_start_careful(middle);
473 if (mid_bs < addr) {
474 low = middle;
475 } else {
476 high = mid_bs;
477 }
478 }
479 assert(low == high && low >= addr, "Didn't work.");
480 return low;
481 }
482
483 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
484 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
485 #endif // _MSC_VER
486
487
488 HeapRegion::HeapRegion(uint hrs_index,
489 G1BlockOffsetSharedArray* sharedOffsetArray,
490 MemRegion mr) :
491 G1OffsetTableContigSpace(sharedOffsetArray, mr),
492 _hrs_index(hrs_index),
493 _humongous_type(NotHumongous), _humongous_start_region(NULL),
494 _in_collection_set(false),
495 _next_in_special_set(NULL), _orig_end(NULL),
496 _claimed(InitialClaimValue), _evacuation_failed(false),
497 _prev_marked_bytes(0), _next_marked_bytes(0), _gc_efficiency(0.0),
498 _young_type(NotYoung), _next_young_region(NULL),
499 _next_dirty_cards_region(NULL), _next(NULL), _pending_removal(false),
500 #ifdef ASSERT
501 _containing_set(NULL),
502 #endif // ASSERT
503 _young_index_in_cset(-1), _surv_rate_group(NULL), _age_index(-1),
504 _rem_set(NULL), _recorded_rs_length(0), _predicted_elapsed_time_ms(0),
505 _predicted_bytes_to_copy(0)
506 {
507 _orig_end = mr.end();
508 // Note that initialize() will set the start of the unmarked area of the
509 // region.
510 hr_clear(false /*par*/, false /*clear_space*/);
511 set_top(bottom());
512 set_saved_mark();
513
514 _rem_set = new HeapRegionRemSet(sharedOffsetArray, this);
515
516 assert(HeapRegionRemSet::num_par_rem_sets() > 0, "Invariant.");
517 }
518
519 CompactibleSpace* HeapRegion::next_compaction_space() const {
520 // We're not using an iterator given that it will wrap around when
521 // it reaches the last region and this is not what we want here.
522 G1CollectedHeap* g1h = G1CollectedHeap::heap();
523 uint index = hrs_index() + 1;
524 while (index < g1h->n_regions()) {
525 HeapRegion* hr = g1h->region_at(index);
526 if (!hr->isHumongous()) {
527 return hr;
528 }
529 index += 1;
530 }
531 return NULL;
532 }
533
534 void HeapRegion::save_marks() {
535 set_saved_mark();
536 }
537
538 void HeapRegion::oops_in_mr_iterate(MemRegion mr, ExtendedOopClosure* cl) {
539 HeapWord* p = mr.start();
540 HeapWord* e = mr.end();
541 oop obj;
542 while (p < e) {
543 obj = oop(p);
544 p += obj->oop_iterate(cl);
545 }
546 assert(p == e, "bad memregion: doesn't end on obj boundary");
547 }
548
549 #define HeapRegion_OOP_SINCE_SAVE_MARKS_DEFN(OopClosureType, nv_suffix) \
550 void HeapRegion::oop_since_save_marks_iterate##nv_suffix(OopClosureType* cl) { \
551 ContiguousSpace::oop_since_save_marks_iterate##nv_suffix(cl); \
552 }
553 SPECIALIZED_SINCE_SAVE_MARKS_CLOSURES(HeapRegion_OOP_SINCE_SAVE_MARKS_DEFN)
554
555
556 void HeapRegion::oop_before_save_marks_iterate(ExtendedOopClosure* cl) {
557 oops_in_mr_iterate(MemRegion(bottom(), saved_mark_word()), cl);
558 }
559
560 void HeapRegion::note_self_forwarding_removal_start(bool during_initial_mark,
561 bool during_conc_mark) {
562 // We always recreate the prev marking info and we'll explicitly
563 // mark all objects we find to be self-forwarded on the prev
564 // bitmap. So all objects need to be below PTAMS.
565 _prev_top_at_mark_start = top();
566 _prev_marked_bytes = 0;
567
568 if (during_initial_mark) {
569 // During initial-mark, we'll also explicitly mark all objects
570 // we find to be self-forwarded on the next bitmap. So all
571 // objects need to be below NTAMS.
572 _next_top_at_mark_start = top();
573 _next_marked_bytes = 0;
574 } else if (during_conc_mark) {
575 // During concurrent mark, all objects in the CSet (including
576 // the ones we find to be self-forwarded) are implicitly live.
577 // So all objects need to be above NTAMS.
578 _next_top_at_mark_start = bottom();
579 _next_marked_bytes = 0;
580 }
581 }
582
583 void HeapRegion::note_self_forwarding_removal_end(bool during_initial_mark,
584 bool during_conc_mark,
585 size_t marked_bytes) {
586 assert(0 <= marked_bytes && marked_bytes <= used(),
587 err_msg("marked: "SIZE_FORMAT" used: "SIZE_FORMAT,
588 marked_bytes, used()));
589 _prev_marked_bytes = marked_bytes;
590 }
591
592 HeapWord*
593 HeapRegion::object_iterate_mem_careful(MemRegion mr,
594 ObjectClosure* cl) {
595 G1CollectedHeap* g1h = G1CollectedHeap::heap();
596 // We used to use "block_start_careful" here. But we're actually happy
597 // to update the BOT while we do this...
598 HeapWord* cur = block_start(mr.start());
599 mr = mr.intersection(used_region());
600 if (mr.is_empty()) return NULL;
601 // Otherwise, find the obj that extends onto mr.start().
602
603 assert(cur <= mr.start()
604 && (oop(cur)->klass_or_null() == NULL ||
605 cur + oop(cur)->size() > mr.start()),
606 "postcondition of block_start");
607 oop obj;
608 while (cur < mr.end()) {
609 obj = oop(cur);
610 if (obj->klass_or_null() == NULL) {
611 // Ran into an unparseable point.
612 return cur;
613 } else if (!g1h->is_obj_dead(obj)) {
614 cl->do_object(obj);
615 }
616 if (cl->abort()) return cur;
617 // The check above must occur before the operation below, since an
618 // abort might invalidate the "size" operation.
619 cur += obj->size();
620 }
621 return NULL;
622 }
623
624 HeapWord*
625 HeapRegion::
626 oops_on_card_seq_iterate_careful(MemRegion mr,
627 FilterOutOfRegionClosure* cl,
628 bool filter_young,
629 jbyte* card_ptr) {
630 // Currently, we should only have to clean the card if filter_young
631 // is true and vice versa.
632 if (filter_young) {
633 assert(card_ptr != NULL, "pre-condition");
634 } else {
635 assert(card_ptr == NULL, "pre-condition");
636 }
637 G1CollectedHeap* g1h = G1CollectedHeap::heap();
638
639 // If we're within a stop-world GC, then we might look at a card in a
640 // GC alloc region that extends onto a GC LAB, which may not be
641 // parseable. Stop such at the "saved_mark" of the region.
642 if (g1h->is_gc_active()) {
643 mr = mr.intersection(used_region_at_save_marks());
644 } else {
645 mr = mr.intersection(used_region());
646 }
647 if (mr.is_empty()) return NULL;
648 // Otherwise, find the obj that extends onto mr.start().
649
650 // The intersection of the incoming mr (for the card) and the
651 // allocated part of the region is non-empty. This implies that
652 // we have actually allocated into this region. The code in
653 // G1CollectedHeap.cpp that allocates a new region sets the
654 // is_young tag on the region before allocating. Thus we
655 // safely know if this region is young.
656 if (is_young() && filter_young) {
657 return NULL;
658 }
659
660 assert(!is_young(), "check value of filter_young");
661
662 // We can only clean the card here, after we make the decision that
663 // the card is not young. And we only clean the card if we have been
664 // asked to (i.e., card_ptr != NULL).
665 if (card_ptr != NULL) {
666 *card_ptr = CardTableModRefBS::clean_card_val();
667 // We must complete this write before we do any of the reads below.
668 OrderAccess::storeload();
669 }
670
671 // Cache the boundaries of the memory region in some const locals
672 HeapWord* const start = mr.start();
673 HeapWord* const end = mr.end();
674
675 // We used to use "block_start_careful" here. But we're actually happy
676 // to update the BOT while we do this...
677 HeapWord* cur = block_start(start);
678 assert(cur <= start, "Postcondition");
679
680 oop obj;
681
682 HeapWord* next = cur;
683 while (next <= start) {
684 cur = next;
685 obj = oop(cur);
686 if (obj->klass_or_null() == NULL) {
687 // Ran into an unparseable point.
688 return cur;
689 }
690 // Otherwise...
691 next = (cur + obj->size());
692 }
693
694 // If we finish the above loop...We have a parseable object that
695 // begins on or before the start of the memory region, and ends
696 // inside or spans the entire region.
697
698 assert(obj == oop(cur), "sanity");
699 assert(cur <= start &&
700 obj->klass_or_null() != NULL &&
701 (cur + obj->size()) > start,
702 "Loop postcondition");
703
704 if (!g1h->is_obj_dead(obj)) {
705 obj->oop_iterate(cl, mr);
706 }
707
708 while (cur < end) {
709 obj = oop(cur);
710 if (obj->klass_or_null() == NULL) {
711 // Ran into an unparseable point.
712 return cur;
713 };
714
715 // Otherwise:
716 next = (cur + obj->size());
717
718 if (!g1h->is_obj_dead(obj)) {
719 if (next < end || !obj->is_objArray()) {
720 // This object either does not span the MemRegion
721 // boundary, or if it does it's not an array.
722 // Apply closure to whole object.
723 obj->oop_iterate(cl);
724 } else {
725 // This obj is an array that spans the boundary.
726 // Stop at the boundary.
727 obj->oop_iterate(cl, mr);
728 }
729 }
730 cur = next;
731 }
732 return NULL;
733 }
734
735 void HeapRegion::print() const { print_on(gclog_or_tty); }
736 void HeapRegion::print_on(outputStream* st) const {
737 if (isHumongous()) {
738 if (startsHumongous())
739 st->print(" HS");
740 else
741 st->print(" HC");
742 } else {
743 st->print(" ");
744 }
745 if (in_collection_set())
746 st->print(" CS");
747 else
748 st->print(" ");
749 if (is_young())
750 st->print(is_survivor() ? " SU" : " Y ");
751 else
752 st->print(" ");
753 if (is_empty())
754 st->print(" F");
755 else
756 st->print(" ");
757 st->print(" TS %5d", _gc_time_stamp);
758 st->print(" PTAMS "PTR_FORMAT" NTAMS "PTR_FORMAT,
759 prev_top_at_mark_start(), next_top_at_mark_start());
760 G1OffsetTableContigSpace::print_on(st);
761 }
762
763 void HeapRegion::verify() const {
764 bool dummy = false;
765 verify(VerifyOption_G1UsePrevMarking, /* failures */ &dummy);
766 }
767
768 // This really ought to be commoned up into OffsetTableContigSpace somehow.
769 // We would need a mechanism to make that code skip dead objects.
770
771 void HeapRegion::verify(VerifyOption vo,
772 bool* failures) const {
773 G1CollectedHeap* g1 = G1CollectedHeap::heap();
774 *failures = false;
775 HeapWord* p = bottom();
776 HeapWord* prev_p = NULL;
777 VerifyLiveClosure vl_cl(g1, vo);
778 bool is_humongous = isHumongous();
779 bool do_bot_verify = !is_young();
780 size_t object_num = 0;
781 while (p < top()) {
782 oop obj = oop(p);
783 size_t obj_size = obj->size();
784 object_num += 1;
785
786 if (is_humongous != g1->isHumongous(obj_size)) {
787 gclog_or_tty->print_cr("obj "PTR_FORMAT" is of %shumongous size ("
788 SIZE_FORMAT" words) in a %shumongous region",
789 p, g1->isHumongous(obj_size) ? "" : "non-",
790 obj_size, is_humongous ? "" : "non-");
791 *failures = true;
792 return;
793 }
794
795 // If it returns false, verify_for_object() will output the
796 // appropriate messasge.
797 if (do_bot_verify && !_offsets.verify_for_object(p, obj_size)) {
798 *failures = true;
799 return;
800 }
801
802 if (!g1->is_obj_dead_cond(obj, this, vo)) {
803 if (obj->is_oop()) {
804 Klass* klass = obj->klass();
805 if (!klass->is_metadata()) {
806 gclog_or_tty->print_cr("klass "PTR_FORMAT" of object "PTR_FORMAT" "
807 "not metadata", klass, obj);
808 *failures = true;
809 return;
810 } else if (!klass->is_klass()) {
811 gclog_or_tty->print_cr("klass "PTR_FORMAT" of object "PTR_FORMAT" "
812 "not a klass", klass, obj);
813 *failures = true;
814 return;
815 } else {
816 vl_cl.set_containing_obj(obj);
817 obj->oop_iterate_no_header(&vl_cl);
818 if (vl_cl.failures()) {
819 *failures = true;
820 }
821 if (G1MaxVerifyFailures >= 0 &&
822 vl_cl.n_failures() >= G1MaxVerifyFailures) {
823 return;
824 }
825 }
826 } else {
827 gclog_or_tty->print_cr(PTR_FORMAT" no an oop", obj);
828 *failures = true;
829 return;
830 }
831 }
832 prev_p = p;
833 p += obj_size;
834 }
835
836 if (p != top()) {
837 gclog_or_tty->print_cr("end of last object "PTR_FORMAT" "
838 "does not match top "PTR_FORMAT, p, top());
839 *failures = true;
840 return;
841 }
842
843 HeapWord* the_end = end();
844 assert(p == top(), "it should still hold");
845 // Do some extra BOT consistency checking for addresses in the
846 // range [top, end). BOT look-ups in this range should yield
847 // top. No point in doing that if top == end (there's nothing there).
848 if (p < the_end) {
849 // Look up top
850 HeapWord* addr_1 = p;
851 HeapWord* b_start_1 = _offsets.block_start_const(addr_1);
852 if (b_start_1 != p) {
853 gclog_or_tty->print_cr("BOT look up for top: "PTR_FORMAT" "
854 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
855 addr_1, b_start_1, p);
856 *failures = true;
857 return;
858 }
859
860 // Look up top + 1
861 HeapWord* addr_2 = p + 1;
862 if (addr_2 < the_end) {
863 HeapWord* b_start_2 = _offsets.block_start_const(addr_2);
864 if (b_start_2 != p) {
865 gclog_or_tty->print_cr("BOT look up for top + 1: "PTR_FORMAT" "
866 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
867 addr_2, b_start_2, p);
868 *failures = true;
869 return;
870 }
871 }
872
873 // Look up an address between top and end
874 size_t diff = pointer_delta(the_end, p) / 2;
875 HeapWord* addr_3 = p + diff;
876 if (addr_3 < the_end) {
877 HeapWord* b_start_3 = _offsets.block_start_const(addr_3);
878 if (b_start_3 != p) {
879 gclog_or_tty->print_cr("BOT look up for top + diff: "PTR_FORMAT" "
880 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
881 addr_3, b_start_3, p);
882 *failures = true;
883 return;
884 }
885 }
886
887 // Loook up end - 1
888 HeapWord* addr_4 = the_end - 1;
889 HeapWord* b_start_4 = _offsets.block_start_const(addr_4);
890 if (b_start_4 != p) {
891 gclog_or_tty->print_cr("BOT look up for end - 1: "PTR_FORMAT" "
892 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
893 addr_4, b_start_4, p);
894 *failures = true;
895 return;
896 }
897 }
898
899 if (is_humongous && object_num > 1) {
900 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] is humongous "
901 "but has "SIZE_FORMAT", objects",
902 bottom(), end(), object_num);
903 *failures = true;
904 return;
905 }
906 }
907
908 // G1OffsetTableContigSpace code; copied from space.cpp. Hope this can go
909 // away eventually.
910
911 void G1OffsetTableContigSpace::clear(bool mangle_space) {
912 ContiguousSpace::clear(mangle_space);
913 _offsets.zero_bottom_entry();
914 _offsets.initialize_threshold();
915 }
916
917 void G1OffsetTableContigSpace::set_bottom(HeapWord* new_bottom) {
918 Space::set_bottom(new_bottom);
919 _offsets.set_bottom(new_bottom);
920 }
921
922 void G1OffsetTableContigSpace::set_end(HeapWord* new_end) {
923 Space::set_end(new_end);
924 _offsets.resize(new_end - bottom());
925 }
926
927 void G1OffsetTableContigSpace::print() const {
928 print_short();
929 gclog_or_tty->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", "
930 INTPTR_FORMAT ", " INTPTR_FORMAT ")",
931 bottom(), top(), _offsets.threshold(), end());
932 }
933
934 HeapWord* G1OffsetTableContigSpace::initialize_threshold() {
935 return _offsets.initialize_threshold();
936 }
937
938 HeapWord* G1OffsetTableContigSpace::cross_threshold(HeapWord* start,
939 HeapWord* end) {
940 _offsets.alloc_block(start, end);
941 return _offsets.threshold();
942 }
943
944 HeapWord* G1OffsetTableContigSpace::saved_mark_word() const {
945 G1CollectedHeap* g1h = G1CollectedHeap::heap();
946 assert( _gc_time_stamp <= g1h->get_gc_time_stamp(), "invariant" );
947 if (_gc_time_stamp < g1h->get_gc_time_stamp())
948 return top();
949 else
950 return ContiguousSpace::saved_mark_word();
951 }
952
953 void G1OffsetTableContigSpace::set_saved_mark() {
954 G1CollectedHeap* g1h = G1CollectedHeap::heap();
955 unsigned curr_gc_time_stamp = g1h->get_gc_time_stamp();
956
957 if (_gc_time_stamp < curr_gc_time_stamp) {
958 // The order of these is important, as another thread might be
959 // about to start scanning this region. If it does so after
960 // set_saved_mark and before _gc_time_stamp = ..., then the latter
961 // will be false, and it will pick up top() as the high water mark
962 // of region. If it does so after _gc_time_stamp = ..., then it
963 // will pick up the right saved_mark_word() as the high water mark
964 // of the region. Either way, the behaviour will be correct.
965 ContiguousSpace::set_saved_mark();
966 OrderAccess::storestore();
967 _gc_time_stamp = curr_gc_time_stamp;
968 // No need to do another barrier to flush the writes above. If
969 // this is called in parallel with other threads trying to
970 // allocate into the region, the caller should call this while
971 // holding a lock and when the lock is released the writes will be
972 // flushed.
973 }
974 }
975
976 G1OffsetTableContigSpace::
977 G1OffsetTableContigSpace(G1BlockOffsetSharedArray* sharedOffsetArray,
978 MemRegion mr) :
979 _offsets(sharedOffsetArray, mr),
980 _par_alloc_lock(Mutex::leaf, "OffsetTableContigSpace par alloc lock", true),
981 _gc_time_stamp(0)
982 {
983 _offsets.set_space(this);
984 // false ==> we'll do the clearing if there's clearing to be done.
985 ContiguousSpace::initialize(mr, false, SpaceDecorator::Mangle);
986 _offsets.zero_bottom_entry();
987 _offsets.initialize_threshold();
988 }