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 *
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 int HeapRegion::GrainBytes = 0;
39 int HeapRegion::GrainWords = 0;
40 int HeapRegion::CardsPerRegion = 0;
41
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 { }
49
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 {}
55
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 VerifyOption _vo;
64 public:
65 // _vo == UsePrevMarking -> use "prev" marking information,
66 // _vo == UseNextMarking -> use "next" marking information,
67 // _vo == UseMarkWord -> use mark word from object header.
68 VerifyLiveClosure(G1CollectedHeap* g1h, VerifyOption vo) :
69 _g1h(g1h), _bs(NULL), _containing_obj(NULL),
70 _failures(false), _n_failures(0), _vo(vo)
71 {
72 BarrierSet* bs = _g1h->barrier_set();
73 if (bs->is_a(BarrierSet::CardTableModRef))
74 _bs = (CardTableModRefBS*)bs;
75 }
76
77 void set_containing_obj(oop obj) {
78 _containing_obj = obj;
79 }
80
81 bool failures() { return _failures; }
82 int n_failures() { return _n_failures; }
83
84 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
85 virtual void do_oop( oop* p) { do_oop_work(p); }
86
87 void print_object(outputStream* out, oop obj) {
88 #ifdef PRODUCT
89 klassOop k = obj->klass();
90 const char* class_name = instanceKlass::cast(k)->external_name();
91 out->print_cr("class name %s", class_name);
92 #else // PRODUCT
93 obj->print_on(out);
94 #endif // PRODUCT
95 }
96
97 template <class T> void do_oop_work(T* p) {
98 assert(_containing_obj != NULL, "Precondition");
99 assert(!_g1h->is_obj_dead_cond(_containing_obj, _vo),
100 "Precondition");
101 T heap_oop = oopDesc::load_heap_oop(p);
102 if (!oopDesc::is_null(heap_oop)) {
103 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
104 bool failed = false;
105 if (!_g1h->is_in_closed_subset(obj) ||
106 _g1h->is_obj_dead_cond(obj, _vo)) {
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 _failures = true;
137 failed = true;
138 _n_failures++;
139 }
140
141 if (!_g1h->full_collection()) {
142 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
143 HeapRegion* to = _g1h->heap_region_containing(obj);
144 if (from != NULL && to != NULL &&
145 from != to &&
146 !to->isHumongous()) {
147 jbyte cv_obj = *_bs->byte_for_const(_containing_obj);
148 jbyte cv_field = *_bs->byte_for_const(p);
149 const jbyte dirty = CardTableModRefBS::dirty_card_val();
150
151 bool is_bad = !(from->is_young()
152 || to->rem_set()->contains_reference(p)
153 || !G1HRRSFlushLogBuffersOnVerify && // buffers were not flushed
154 (_containing_obj->is_objArray() ?
155 cv_field == dirty
156 : cv_obj == dirty || cv_field == dirty));
157 if (is_bad) {
158 if (!_failures) {
159 gclog_or_tty->print_cr("");
160 gclog_or_tty->print_cr("----------");
161 }
162 gclog_or_tty->print_cr("Missing rem set entry:");
163 gclog_or_tty->print_cr("Field "PTR_FORMAT" "
164 "of obj "PTR_FORMAT", "
165 "in region "HR_FORMAT,
166 p, (void*) _containing_obj,
167 HR_FORMAT_PARAMS(from));
168 _containing_obj->print_on(gclog_or_tty);
169 gclog_or_tty->print_cr("points to obj "PTR_FORMAT" "
170 "in region "HR_FORMAT,
171 (void*) obj,
172 HR_FORMAT_PARAMS(to));
173 obj->print_on(gclog_or_tty);
174 gclog_or_tty->print_cr("Obj head CTE = %d, field CTE = %d.",
175 cv_obj, cv_field);
176 gclog_or_tty->print_cr("----------");
177 _failures = true;
178 if (!failed) _n_failures++;
179 }
180 }
181 }
182 }
183 }
184 };
185
186 template<class ClosureType>
187 HeapWord* walk_mem_region_loop(ClosureType* cl, G1CollectedHeap* g1h,
188 HeapRegion* hr,
189 HeapWord* cur, HeapWord* top) {
190 oop cur_oop = oop(cur);
191 int oop_size = cur_oop->size();
192 HeapWord* next_obj = cur + oop_size;
193 while (next_obj < top) {
194 // Keep filtering the remembered set.
195 if (!g1h->is_obj_dead(cur_oop, hr)) {
196 // Bottom lies entirely below top, so we can call the
197 // non-memRegion version of oop_iterate below.
198 cur_oop->oop_iterate(cl);
199 }
200 cur = next_obj;
201 cur_oop = oop(cur);
202 oop_size = cur_oop->size();
203 next_obj = cur + oop_size;
204 }
205 return cur;
206 }
207
208 void HeapRegionDCTOC::walk_mem_region_with_cl(MemRegion mr,
209 HeapWord* bottom,
210 HeapWord* top,
211 OopClosure* cl) {
212 G1CollectedHeap* g1h = _g1;
213
214 int oop_size;
215
216 OopClosure* cl2 = cl;
217
218 // If we are scanning the remembered sets looking for refs
219 // into the collection set during an evacuation pause then
220 // we will want to 'discover' reference objects that point
221 // to referents in the collection set.
222 //
223 // Unfortunately it is an instance of FilterIntoCSClosure
224 // that is iterated over the reference fields of oops in
225 // mr (and not the G1ParPushHeapRSClosure - which is the
226 // cl parameter).
227 // If we set the _ref_processor field in the FilterIntoCSClosure
228 // instance, all the reference objects that are walked
229 // (regardless of whether their referent object's are in
230 // the cset) will be 'discovered'.
231 //
232 // The G1STWIsAlive closure considers a referent object that
233 // is outside the cset as alive. The G1CopyingKeepAliveClosure
234 // skips referents that are not in the cset.
235 //
236 // Therefore reference objects in mr with a referent that is
237 // outside the cset should be OK.
238
239 ReferenceProcessor* rp = _cl->_ref_processor;
240 if (rp != NULL) {
241 assert(rp == _g1->ref_processor_stw(), "should be stw");
242 assert(_fk == IntoCSFilterKind, "should be looking for refs into CS");
243 }
244
245 FilterIntoCSClosure intoCSFilt(this, g1h, cl, rp);
246 FilterOutOfRegionClosure outOfRegionFilt(_hr, cl);
247
248 switch (_fk) {
249 case IntoCSFilterKind: cl2 = &intoCSFilt; break;
250 case OutOfRegionFilterKind: cl2 = &outOfRegionFilt; break;
251 }
252
253 // Start filtering what we add to the remembered set. If the object is
254 // not considered dead, either because it is marked (in the mark bitmap)
255 // or it was allocated after marking finished, then we add it. Otherwise
256 // we can safely ignore the object.
257 if (!g1h->is_obj_dead(oop(bottom), _hr)) {
258 oop_size = oop(bottom)->oop_iterate(cl2, mr);
259 } else {
260 oop_size = oop(bottom)->size();
261 }
262
263 bottom += oop_size;
264
265 if (bottom < top) {
266 // We replicate the loop below for several kinds of possible filters.
267 switch (_fk) {
268 case NoFilterKind:
269 bottom = walk_mem_region_loop(cl, g1h, _hr, bottom, top);
270 break;
271
272 case IntoCSFilterKind: {
273 FilterIntoCSClosure filt(this, g1h, cl, rp);
274 bottom = walk_mem_region_loop(&filt, g1h, _hr, bottom, top);
275 break;
276 }
277
278 case OutOfRegionFilterKind: {
279 FilterOutOfRegionClosure filt(_hr, cl);
280 bottom = walk_mem_region_loop(&filt, g1h, _hr, bottom, top);
281 break;
282 }
283
284 default:
285 ShouldNotReachHere();
286 }
287
288 // Last object. Need to do dead-obj filtering here too.
289 if (!g1h->is_obj_dead(oop(bottom), _hr)) {
290 oop(bottom)->oop_iterate(cl2, mr);
291 }
292 }
293 }
294
295 // Minimum region size; we won't go lower than that.
296 // We might want to decrease this in the future, to deal with small
297 // heaps a bit more efficiently.
298 #define MIN_REGION_SIZE ( 1024 * 1024 )
299
300 // Maximum region size; we don't go higher than that. There's a good
301 // reason for having an upper bound. We don't want regions to get too
302 // large, otherwise cleanup's effectiveness would decrease as there
303 // will be fewer opportunities to find totally empty regions after
304 // marking.
305 #define MAX_REGION_SIZE ( 32 * 1024 * 1024 )
306
307 // The automatic region size calculation will try to have around this
308 // many regions in the heap (based on the min heap size).
309 #define TARGET_REGION_NUMBER 2048
310
311 void HeapRegion::setup_heap_region_size(uintx min_heap_size) {
312 // region_size in bytes
313 uintx region_size = G1HeapRegionSize;
314 if (FLAG_IS_DEFAULT(G1HeapRegionSize)) {
315 // We base the automatic calculation on the min heap size. This
316 // can be problematic if the spread between min and max is quite
317 // wide, imagine -Xms128m -Xmx32g. But, if we decided it based on
318 // the max size, the region size might be way too large for the
319 // min size. Either way, some users might have to set the region
320 // size manually for some -Xms / -Xmx combos.
321
322 region_size = MAX2(min_heap_size / TARGET_REGION_NUMBER,
323 (uintx) MIN_REGION_SIZE);
324 }
325
326 int region_size_log = log2_long((jlong) region_size);
327 // Recalculate the region size to make sure it's a power of
328 // 2. This means that region_size is the largest power of 2 that's
329 // <= what we've calculated so far.
330 region_size = ((uintx)1 << region_size_log);
331
332 // Now make sure that we don't go over or under our limits.
333 if (region_size < MIN_REGION_SIZE) {
334 region_size = MIN_REGION_SIZE;
335 } else if (region_size > MAX_REGION_SIZE) {
336 region_size = MAX_REGION_SIZE;
337 }
338
339 // And recalculate the log.
340 region_size_log = log2_long((jlong) region_size);
341
342 // Now, set up the globals.
343 guarantee(LogOfHRGrainBytes == 0, "we should only set it once");
344 LogOfHRGrainBytes = region_size_log;
345
346 guarantee(LogOfHRGrainWords == 0, "we should only set it once");
347 LogOfHRGrainWords = LogOfHRGrainBytes - LogHeapWordSize;
348
349 guarantee(GrainBytes == 0, "we should only set it once");
350 // The cast to int is safe, given that we've bounded region_size by
351 // MIN_REGION_SIZE and MAX_REGION_SIZE.
352 GrainBytes = (int) region_size;
353
354 guarantee(GrainWords == 0, "we should only set it once");
355 GrainWords = GrainBytes >> LogHeapWordSize;
356 guarantee(1 << LogOfHRGrainWords == GrainWords, "sanity");
357
358 guarantee(CardsPerRegion == 0, "we should only set it once");
359 CardsPerRegion = GrainBytes >> CardTableModRefBS::card_shift;
360 }
361
362 void HeapRegion::reset_after_compaction() {
363 G1OffsetTableContigSpace::reset_after_compaction();
364 // After a compaction the mark bitmap is invalid, so we must
365 // treat all objects as being inside the unmarked area.
366 zero_marked_bytes();
367 init_top_at_mark_start();
368 }
369
370 DirtyCardToOopClosure*
371 HeapRegion::new_dcto_closure(OopClosure* cl,
372 CardTableModRefBS::PrecisionStyle precision,
373 HeapRegionDCTOC::FilterKind fk) {
374 return new HeapRegionDCTOC(G1CollectedHeap::heap(),
375 this, cl, precision, fk);
376 }
377
378 void HeapRegion::hr_clear(bool par, bool clear_space) {
379 assert(_humongous_type == NotHumongous,
380 "we should have already filtered out humongous regions");
381 assert(_humongous_start_region == NULL,
382 "we should have already filtered out humongous regions");
383 assert(_end == _orig_end,
384 "we should have already filtered out humongous regions");
385
386 _in_collection_set = false;
387
388 set_young_index_in_cset(-1);
389 uninstall_surv_rate_group();
390 set_young_type(NotYoung);
391 reset_pre_dummy_top();
392
393 if (!par) {
394 // If this is parallel, this will be done later.
395 HeapRegionRemSet* hrrs = rem_set();
396 if (hrrs != NULL) hrrs->clear();
397 _claimed = InitialClaimValue;
398 }
399 zero_marked_bytes();
400 set_sort_index(-1);
401
402 _offsets.resize(HeapRegion::GrainWords);
403 init_top_at_mark_start();
404 if (clear_space) clear(SpaceDecorator::Mangle);
405 }
406
407 void HeapRegion::par_clear() {
408 assert(used() == 0, "the region should have been already cleared");
409 assert(capacity() == (size_t) HeapRegion::GrainBytes,
410 "should be back to normal");
411 HeapRegionRemSet* hrrs = rem_set();
412 hrrs->clear();
413 CardTableModRefBS* ct_bs =
414 (CardTableModRefBS*)G1CollectedHeap::heap()->barrier_set();
415 ct_bs->clear(MemRegion(bottom(), end()));
416 }
417
418 // <PREDICTION>
419 void HeapRegion::calc_gc_efficiency() {
420 G1CollectedHeap* g1h = G1CollectedHeap::heap();
421 _gc_efficiency = (double) garbage_bytes() /
422 g1h->predict_region_elapsed_time_ms(this, false);
423 }
424 // </PREDICTION>
425
426 void HeapRegion::set_startsHumongous(HeapWord* new_top, HeapWord* new_end) {
427 assert(!isHumongous(), "sanity / pre-condition");
428 assert(end() == _orig_end,
429 "Should be normal before the humongous object allocation");
430 assert(top() == bottom(), "should be empty");
431 assert(bottom() <= new_top && new_top <= new_end, "pre-condition");
432
433 _humongous_type = StartsHumongous;
434 _humongous_start_region = this;
435
436 set_end(new_end);
437 _offsets.set_for_starts_humongous(new_top);
438 }
439
440 void HeapRegion::set_continuesHumongous(HeapRegion* first_hr) {
441 assert(!isHumongous(), "sanity / pre-condition");
442 assert(end() == _orig_end,
443 "Should be normal before the humongous object allocation");
444 assert(top() == bottom(), "should be empty");
445 assert(first_hr->startsHumongous(), "pre-condition");
446
447 _humongous_type = ContinuesHumongous;
448 _humongous_start_region = first_hr;
449 }
450
451 void HeapRegion::set_notHumongous() {
452 assert(isHumongous(), "pre-condition");
453
454 if (startsHumongous()) {
455 assert(top() <= end(), "pre-condition");
456 set_end(_orig_end);
457 if (top() > end()) {
458 // at least one "continues humongous" region after it
459 set_top(end());
460 }
461 } else {
462 // continues humongous
463 assert(end() == _orig_end, "sanity");
464 }
465
466 assert(capacity() == (size_t) HeapRegion::GrainBytes, "pre-condition");
467 _humongous_type = NotHumongous;
468 _humongous_start_region = NULL;
469 }
470
471 bool HeapRegion::claimHeapRegion(jint claimValue) {
472 jint current = _claimed;
473 if (current != claimValue) {
474 jint res = Atomic::cmpxchg(claimValue, &_claimed, current);
475 if (res == current) {
476 return true;
477 }
478 }
479 return false;
480 }
481
482 HeapWord* HeapRegion::next_block_start_careful(HeapWord* addr) {
483 HeapWord* low = addr;
484 HeapWord* high = end();
485 while (low < high) {
486 size_t diff = pointer_delta(high, low);
487 // Must add one below to bias toward the high amount. Otherwise, if
488 // "high" were at the desired value, and "low" were one less, we
489 // would not converge on "high". This is not symmetric, because
490 // we set "high" to a block start, which might be the right one,
491 // which we don't do for "low".
492 HeapWord* middle = low + (diff+1)/2;
493 if (middle == high) return high;
494 HeapWord* mid_bs = block_start_careful(middle);
495 if (mid_bs < addr) {
496 low = middle;
497 } else {
498 high = mid_bs;
499 }
500 }
501 assert(low == high && low >= addr, "Didn't work.");
502 return low;
503 }
504
505 void HeapRegion::initialize(MemRegion mr, bool clear_space, bool mangle_space) {
506 G1OffsetTableContigSpace::initialize(mr, false, mangle_space);
507 hr_clear(false/*par*/, clear_space);
508 }
509 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
510 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
511 #endif // _MSC_VER
512
513
514 HeapRegion::
515 HeapRegion(size_t hrs_index, G1BlockOffsetSharedArray* sharedOffsetArray,
516 MemRegion mr, bool is_zeroed)
517 : G1OffsetTableContigSpace(sharedOffsetArray, mr, is_zeroed),
518 _hrs_index(hrs_index),
519 _humongous_type(NotHumongous), _humongous_start_region(NULL),
520 _in_collection_set(false),
521 _next_in_special_set(NULL), _orig_end(NULL),
522 _claimed(InitialClaimValue), _evacuation_failed(false),
523 _prev_marked_bytes(0), _next_marked_bytes(0), _sort_index(-1),
524 _young_type(NotYoung), _next_young_region(NULL),
525 _next_dirty_cards_region(NULL), _next(NULL), _pending_removal(false),
526 #ifdef ASSERT
527 _containing_set(NULL),
528 #endif // ASSERT
529 _young_index_in_cset(-1), _surv_rate_group(NULL), _age_index(-1),
530 _rem_set(NULL), _recorded_rs_length(0), _predicted_elapsed_time_ms(0),
531 _predicted_bytes_to_copy(0)
532 {
533 _orig_end = mr.end();
534 // Note that initialize() will set the start of the unmarked area of the
535 // region.
536 this->initialize(mr, !is_zeroed, SpaceDecorator::Mangle);
537 set_top(bottom());
538 set_saved_mark();
539
540 _rem_set = new HeapRegionRemSet(sharedOffsetArray, this);
541
542 assert(HeapRegionRemSet::num_par_rem_sets() > 0, "Invariant.");
543 // In case the region is allocated during a pause, note the top.
544 // We haven't done any counting on a brand new region.
545 _top_at_conc_mark_count = bottom();
546 }
547
548 class NextCompactionHeapRegionClosure: public HeapRegionClosure {
549 const HeapRegion* _target;
550 bool _target_seen;
551 HeapRegion* _last;
552 CompactibleSpace* _res;
553 public:
554 NextCompactionHeapRegionClosure(const HeapRegion* target) :
555 _target(target), _target_seen(false), _res(NULL) {}
556 bool doHeapRegion(HeapRegion* cur) {
557 if (_target_seen) {
558 if (!cur->isHumongous()) {
559 _res = cur;
560 return true;
561 }
562 } else if (cur == _target) {
563 _target_seen = true;
564 }
565 return false;
566 }
567 CompactibleSpace* result() { return _res; }
568 };
569
570 CompactibleSpace* HeapRegion::next_compaction_space() const {
571 G1CollectedHeap* g1h = G1CollectedHeap::heap();
572 // cast away const-ness
573 HeapRegion* r = (HeapRegion*) this;
574 NextCompactionHeapRegionClosure blk(r);
575 g1h->heap_region_iterate_from(r, &blk);
576 return blk.result();
577 }
578
579 void HeapRegion::save_marks() {
580 set_saved_mark();
581 }
582
583 void HeapRegion::oops_in_mr_iterate(MemRegion mr, OopClosure* cl) {
584 HeapWord* p = mr.start();
585 HeapWord* e = mr.end();
586 oop obj;
587 while (p < e) {
588 obj = oop(p);
589 p += obj->oop_iterate(cl);
590 }
591 assert(p == e, "bad memregion: doesn't end on obj boundary");
592 }
593
594 #define HeapRegion_OOP_SINCE_SAVE_MARKS_DEFN(OopClosureType, nv_suffix) \
595 void HeapRegion::oop_since_save_marks_iterate##nv_suffix(OopClosureType* cl) { \
596 ContiguousSpace::oop_since_save_marks_iterate##nv_suffix(cl); \
597 }
598 SPECIALIZED_SINCE_SAVE_MARKS_CLOSURES(HeapRegion_OOP_SINCE_SAVE_MARKS_DEFN)
599
600
601 void HeapRegion::oop_before_save_marks_iterate(OopClosure* cl) {
602 oops_in_mr_iterate(MemRegion(bottom(), saved_mark_word()), cl);
603 }
604
605 HeapWord*
606 HeapRegion::object_iterate_mem_careful(MemRegion mr,
607 ObjectClosure* cl) {
608 G1CollectedHeap* g1h = G1CollectedHeap::heap();
609 // We used to use "block_start_careful" here. But we're actually happy
610 // to update the BOT while we do this...
611 HeapWord* cur = block_start(mr.start());
612 mr = mr.intersection(used_region());
613 if (mr.is_empty()) return NULL;
614 // Otherwise, find the obj that extends onto mr.start().
615
616 assert(cur <= mr.start()
617 && (oop(cur)->klass_or_null() == NULL ||
618 cur + oop(cur)->size() > mr.start()),
619 "postcondition of block_start");
620 oop obj;
621 while (cur < mr.end()) {
622 obj = oop(cur);
623 if (obj->klass_or_null() == NULL) {
624 // Ran into an unparseable point.
625 return cur;
626 } else if (!g1h->is_obj_dead(obj)) {
627 cl->do_object(obj);
628 }
629 if (cl->abort()) return cur;
630 // The check above must occur before the operation below, since an
631 // abort might invalidate the "size" operation.
632 cur += obj->size();
633 }
634 return NULL;
635 }
636
637 HeapWord*
638 HeapRegion::
639 oops_on_card_seq_iterate_careful(MemRegion mr,
640 FilterOutOfRegionClosure* cl,
641 bool filter_young,
642 jbyte* card_ptr) {
643 // Currently, we should only have to clean the card if filter_young
644 // is true and vice versa.
645 if (filter_young) {
646 assert(card_ptr != NULL, "pre-condition");
647 } else {
648 assert(card_ptr == NULL, "pre-condition");
649 }
650 G1CollectedHeap* g1h = G1CollectedHeap::heap();
651
652 // If we're within a stop-world GC, then we might look at a card in a
653 // GC alloc region that extends onto a GC LAB, which may not be
654 // parseable. Stop such at the "saved_mark" of the region.
655 if (G1CollectedHeap::heap()->is_gc_active()) {
656 mr = mr.intersection(used_region_at_save_marks());
657 } else {
658 mr = mr.intersection(used_region());
659 }
660 if (mr.is_empty()) return NULL;
661 // Otherwise, find the obj that extends onto mr.start().
662
663 // The intersection of the incoming mr (for the card) and the
664 // allocated part of the region is non-empty. This implies that
665 // we have actually allocated into this region. The code in
666 // G1CollectedHeap.cpp that allocates a new region sets the
667 // is_young tag on the region before allocating. Thus we
668 // safely know if this region is young.
669 if (is_young() && filter_young) {
670 return NULL;
671 }
672
673 assert(!is_young(), "check value of filter_young");
674
675 // We can only clean the card here, after we make the decision that
676 // the card is not young. And we only clean the card if we have been
677 // asked to (i.e., card_ptr != NULL).
678 if (card_ptr != NULL) {
679 *card_ptr = CardTableModRefBS::clean_card_val();
680 // We must complete this write before we do any of the reads below.
681 OrderAccess::storeload();
682 }
683
684 // We used to use "block_start_careful" here. But we're actually happy
685 // to update the BOT while we do this...
686 HeapWord* cur = block_start(mr.start());
687 assert(cur <= mr.start(), "Postcondition");
688
689 while (cur <= mr.start()) {
690 if (oop(cur)->klass_or_null() == NULL) {
691 // Ran into an unparseable point.
692 return cur;
693 }
694 // Otherwise...
695 int sz = oop(cur)->size();
696 if (cur + sz > mr.start()) break;
697 // Otherwise, go on.
698 cur = cur + sz;
699 }
700 oop obj;
701 obj = oop(cur);
702 // If we finish this loop...
703 assert(cur <= mr.start()
704 && obj->klass_or_null() != NULL
705 && cur + obj->size() > mr.start(),
706 "Loop postcondition");
707 if (!g1h->is_obj_dead(obj)) {
708 obj->oop_iterate(cl, mr);
709 }
710
711 HeapWord* next;
712 while (cur < mr.end()) {
713 obj = oop(cur);
714 if (obj->klass_or_null() == NULL) {
715 // Ran into an unparseable point.
716 return cur;
717 };
718 // Otherwise:
719 next = (cur + obj->size());
720 if (!g1h->is_obj_dead(obj)) {
721 if (next < mr.end()) {
722 obj->oop_iterate(cl);
723 } else {
724 // this obj spans the boundary. If it's an array, stop at the
725 // boundary.
726 if (obj->is_objArray()) {
727 obj->oop_iterate(cl, mr);
728 } else {
729 obj->oop_iterate(cl);
730 }
731 }
732 }
733 cur = next;
734 }
735 return NULL;
736 }
737
738 void HeapRegion::print() const { print_on(gclog_or_tty); }
739 void HeapRegion::print_on(outputStream* st) const {
740 if (isHumongous()) {
741 if (startsHumongous())
742 st->print(" HS");
743 else
744 st->print(" HC");
745 } else {
746 st->print(" ");
747 }
748 if (in_collection_set())
749 st->print(" CS");
750 else
751 st->print(" ");
752 if (is_young())
753 st->print(is_survivor() ? " SU" : " Y ");
754 else
755 st->print(" ");
756 if (is_empty())
757 st->print(" F");
758 else
759 st->print(" ");
760 st->print(" %5d", _gc_time_stamp);
761 st->print(" PTAMS "PTR_FORMAT" NTAMS "PTR_FORMAT,
762 prev_top_at_mark_start(), next_top_at_mark_start());
763 G1OffsetTableContigSpace::print_on(st);
764 }
765
766 void HeapRegion::verify(bool allow_dirty) const {
767 bool dummy = false;
768 verify(allow_dirty, VerifyOption_G1UsePrevMarking, /* failures */ &dummy);
769 }
770
771 // This really ought to be commoned up into OffsetTableContigSpace somehow.
772 // We would need a mechanism to make that code skip dead objects.
773
774 void HeapRegion::verify(bool allow_dirty,
775 VerifyOption vo,
776 bool* failures) const {
777 G1CollectedHeap* g1 = G1CollectedHeap::heap();
778 *failures = false;
779 HeapWord* p = bottom();
780 HeapWord* prev_p = NULL;
781 VerifyLiveClosure vl_cl(g1, vo);
782 bool is_humongous = isHumongous();
783 bool do_bot_verify = !is_young();
784 size_t object_num = 0;
785 while (p < top()) {
786 oop obj = oop(p);
787 size_t obj_size = obj->size();
788 object_num += 1;
789
790 if (is_humongous != g1->isHumongous(obj_size)) {
791 gclog_or_tty->print_cr("obj "PTR_FORMAT" is of %shumongous size ("
792 SIZE_FORMAT" words) in a %shumongous region",
793 p, g1->isHumongous(obj_size) ? "" : "non-",
794 obj_size, is_humongous ? "" : "non-");
795 *failures = true;
796 return;
797 }
798
799 // If it returns false, verify_for_object() will output the
800 // appropriate messasge.
801 if (do_bot_verify && !_offsets.verify_for_object(p, obj_size)) {
802 *failures = true;
803 return;
804 }
805
806 if (!g1->is_obj_dead_cond(obj, this, vo)) {
807 if (obj->is_oop()) {
808 klassOop klass = obj->klass();
809 if (!klass->is_perm()) {
810 gclog_or_tty->print_cr("klass "PTR_FORMAT" of object "PTR_FORMAT" "
811 "not in perm", klass, obj);
812 *failures = true;
813 return;
814 } else if (!klass->is_klass()) {
815 gclog_or_tty->print_cr("klass "PTR_FORMAT" of object "PTR_FORMAT" "
816 "not a klass", klass, obj);
817 *failures = true;
818 return;
819 } else {
820 vl_cl.set_containing_obj(obj);
821 obj->oop_iterate(&vl_cl);
822 if (vl_cl.failures()) {
823 *failures = true;
824 }
825 if (G1MaxVerifyFailures >= 0 &&
826 vl_cl.n_failures() >= G1MaxVerifyFailures) {
827 return;
828 }
829 }
830 } else {
831 gclog_or_tty->print_cr(PTR_FORMAT" no an oop", obj);
832 *failures = true;
833 return;
834 }
835 }
836 prev_p = p;
837 p += obj_size;
838 }
839
840 if (p != top()) {
841 gclog_or_tty->print_cr("end of last object "PTR_FORMAT" "
842 "does not match top "PTR_FORMAT, p, top());
843 *failures = true;
844 return;
845 }
846
847 HeapWord* the_end = end();
848 assert(p == top(), "it should still hold");
849 // Do some extra BOT consistency checking for addresses in the
850 // range [top, end). BOT look-ups in this range should yield
851 // top. No point in doing that if top == end (there's nothing there).
852 if (p < the_end) {
853 // Look up top
854 HeapWord* addr_1 = p;
855 HeapWord* b_start_1 = _offsets.block_start_const(addr_1);
856 if (b_start_1 != p) {
857 gclog_or_tty->print_cr("BOT look up for top: "PTR_FORMAT" "
858 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
859 addr_1, b_start_1, p);
860 *failures = true;
861 return;
862 }
863
864 // Look up top + 1
865 HeapWord* addr_2 = p + 1;
866 if (addr_2 < the_end) {
867 HeapWord* b_start_2 = _offsets.block_start_const(addr_2);
868 if (b_start_2 != p) {
869 gclog_or_tty->print_cr("BOT look up for top + 1: "PTR_FORMAT" "
870 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
871 addr_2, b_start_2, p);
872 *failures = true;
873 return;
874 }
875 }
876
877 // Look up an address between top and end
878 size_t diff = pointer_delta(the_end, p) / 2;
879 HeapWord* addr_3 = p + diff;
880 if (addr_3 < the_end) {
881 HeapWord* b_start_3 = _offsets.block_start_const(addr_3);
882 if (b_start_3 != p) {
883 gclog_or_tty->print_cr("BOT look up for top + diff: "PTR_FORMAT" "
884 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
885 addr_3, b_start_3, p);
886 *failures = true;
887 return;
888 }
889 }
890
891 // Loook up end - 1
892 HeapWord* addr_4 = the_end - 1;
893 HeapWord* b_start_4 = _offsets.block_start_const(addr_4);
894 if (b_start_4 != p) {
895 gclog_or_tty->print_cr("BOT look up for end - 1: "PTR_FORMAT" "
896 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
897 addr_4, b_start_4, p);
898 *failures = true;
899 return;
900 }
901 }
902
903 if (is_humongous && object_num > 1) {
904 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] is humongous "
905 "but has "SIZE_FORMAT", objects",
906 bottom(), end(), object_num);
907 *failures = true;
908 return;
909 }
910 }
911
912 // G1OffsetTableContigSpace code; copied from space.cpp. Hope this can go
913 // away eventually.
914
915 void G1OffsetTableContigSpace::initialize(MemRegion mr, bool clear_space, bool mangle_space) {
916 // false ==> we'll do the clearing if there's clearing to be done.
917 ContiguousSpace::initialize(mr, false, mangle_space);
918 _offsets.zero_bottom_entry();
919 _offsets.initialize_threshold();
920 if (clear_space) clear(mangle_space);
921 }
922
923 void G1OffsetTableContigSpace::clear(bool mangle_space) {
924 ContiguousSpace::clear(mangle_space);
925 _offsets.zero_bottom_entry();
926 _offsets.initialize_threshold();
927 }
928
929 void G1OffsetTableContigSpace::set_bottom(HeapWord* new_bottom) {
930 Space::set_bottom(new_bottom);
931 _offsets.set_bottom(new_bottom);
932 }
933
934 void G1OffsetTableContigSpace::set_end(HeapWord* new_end) {
935 Space::set_end(new_end);
936 _offsets.resize(new_end - bottom());
937 }
938
939 void G1OffsetTableContigSpace::print() const {
940 print_short();
941 gclog_or_tty->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", "
942 INTPTR_FORMAT ", " INTPTR_FORMAT ")",
943 bottom(), top(), _offsets.threshold(), end());
944 }
945
946 HeapWord* G1OffsetTableContigSpace::initialize_threshold() {
947 return _offsets.initialize_threshold();
948 }
949
950 HeapWord* G1OffsetTableContigSpace::cross_threshold(HeapWord* start,
951 HeapWord* end) {
952 _offsets.alloc_block(start, end);
953 return _offsets.threshold();
954 }
955
956 HeapWord* G1OffsetTableContigSpace::saved_mark_word() const {
957 G1CollectedHeap* g1h = G1CollectedHeap::heap();
958 assert( _gc_time_stamp <= g1h->get_gc_time_stamp(), "invariant" );
959 if (_gc_time_stamp < g1h->get_gc_time_stamp())
960 return top();
961 else
962 return ContiguousSpace::saved_mark_word();
963 }
964
965 void G1OffsetTableContigSpace::set_saved_mark() {
966 G1CollectedHeap* g1h = G1CollectedHeap::heap();
967 unsigned curr_gc_time_stamp = g1h->get_gc_time_stamp();
968
969 if (_gc_time_stamp < curr_gc_time_stamp) {
970 // The order of these is important, as another thread might be
971 // about to start scanning this region. If it does so after
972 // set_saved_mark and before _gc_time_stamp = ..., then the latter
973 // will be false, and it will pick up top() as the high water mark
974 // of region. If it does so after _gc_time_stamp = ..., then it
975 // will pick up the right saved_mark_word() as the high water mark
976 // of the region. Either way, the behaviour will be correct.
977 ContiguousSpace::set_saved_mark();
978 OrderAccess::storestore();
979 _gc_time_stamp = curr_gc_time_stamp;
980 // No need to do another barrier to flush the writes above. If
981 // this is called in parallel with other threads trying to
982 // allocate into the region, the caller should call this while
983 // holding a lock and when the lock is released the writes will be
984 // flushed.
985 }
986 }
987
988 G1OffsetTableContigSpace::
989 G1OffsetTableContigSpace(G1BlockOffsetSharedArray* sharedOffsetArray,
990 MemRegion mr, bool is_zeroed) :
991 _offsets(sharedOffsetArray, mr),
992 _par_alloc_lock(Mutex::leaf, "OffsetTableContigSpace par alloc lock", true),
993 _gc_time_stamp(0)
994 {
995 _offsets.set_space(this);
996 initialize(mr, !is_zeroed, SpaceDecorator::Mangle);
997 }