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