1 /*
2 * Copyright (c) 2001, 2012, 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() || G1VerifyRSetsDuringFullGC) {
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 void HeapRegion::setup_heap_region_size(uintx min_heap_size) {
290 // region_size in bytes
291 uintx region_size = G1HeapRegionSize;
292 if (FLAG_IS_DEFAULT(G1HeapRegionSize)) {
293 // We base the automatic calculation on the min heap size. This
294 // can be problematic if the spread between min and max is quite
295 // wide, imagine -Xms128m -Xmx32g. But, if we decided it based on
296 // the max size, the region size might be way too large for the
297 // min size. Either way, some users might have to set the region
298 // size manually for some -Xms / -Xmx combos.
299
300 region_size = MAX2(min_heap_size / TARGET_REGION_NUMBER,
301 (uintx) MIN_REGION_SIZE);
302 }
303
304 int region_size_log = log2_long((jlong) region_size);
305 // Recalculate the region size to make sure it's a power of
306 // 2. This means that region_size is the largest power of 2 that's
307 // <= what we've calculated so far.
308 region_size = ((uintx)1 << region_size_log);
309
310 // Now make sure that we don't go over or under our limits.
311 if (region_size < MIN_REGION_SIZE) {
312 region_size = MIN_REGION_SIZE;
313 } else if (region_size > MAX_REGION_SIZE) {
314 region_size = MAX_REGION_SIZE;
315 }
316
317 if (region_size != G1HeapRegionSize) {
318 // Update the flag to make sure that PrintFlagsFinal logs the correct value
319 FLAG_SET_ERGO(uintx, G1HeapRegionSize, region_size);
320 }
321
322 // And recalculate the log.
323 region_size_log = log2_long((jlong) region_size);
324
325 // Now, set up the globals.
326 guarantee(LogOfHRGrainBytes == 0, "we should only set it once");
327 LogOfHRGrainBytes = region_size_log;
328
329 guarantee(LogOfHRGrainWords == 0, "we should only set it once");
330 LogOfHRGrainWords = LogOfHRGrainBytes - LogHeapWordSize;
331
332 guarantee(GrainBytes == 0, "we should only set it once");
333 // The cast to int is safe, given that we've bounded region_size by
334 // MIN_REGION_SIZE and MAX_REGION_SIZE.
335 GrainBytes = (size_t)region_size;
336
337 guarantee(GrainWords == 0, "we should only set it once");
338 GrainWords = GrainBytes >> LogHeapWordSize;
339 guarantee((size_t) 1 << LogOfHRGrainWords == GrainWords, "sanity");
340
341 guarantee(CardsPerRegion == 0, "we should only set it once");
342 CardsPerRegion = GrainBytes >> CardTableModRefBS::card_shift;
343 }
344
345 void HeapRegion::reset_after_compaction() {
346 G1OffsetTableContigSpace::reset_after_compaction();
347 // After a compaction the mark bitmap is invalid, so we must
348 // treat all objects as being inside the unmarked area.
349 zero_marked_bytes();
350 init_top_at_mark_start();
351 }
352
353 void HeapRegion::hr_clear(bool par, bool clear_space) {
354 assert(_humongous_type == NotHumongous,
355 "we should have already filtered out humongous regions");
356 assert(_humongous_start_region == NULL,
357 "we should have already filtered out humongous regions");
358 assert(_end == _orig_end,
359 "we should have already filtered out humongous regions");
360
361 _in_collection_set = false;
362
363 set_young_index_in_cset(-1);
364 uninstall_surv_rate_group();
365 set_young_type(NotYoung);
366 reset_pre_dummy_top();
367
368 if (!par) {
369 // If this is parallel, this will be done later.
370 HeapRegionRemSet* hrrs = rem_set();
371 if (hrrs != NULL) hrrs->clear();
372 _claimed = InitialClaimValue;
373 }
374 zero_marked_bytes();
375
376 _offsets.resize(HeapRegion::GrainWords);
377 init_top_at_mark_start();
378 if (clear_space) clear(SpaceDecorator::Mangle);
379 }
380
381 void HeapRegion::par_clear() {
382 assert(used() == 0, "the region should have been already cleared");
383 assert(capacity() == HeapRegion::GrainBytes, "should be back to normal");
384 HeapRegionRemSet* hrrs = rem_set();
385 hrrs->clear();
386 CardTableModRefBS* ct_bs =
387 (CardTableModRefBS*)G1CollectedHeap::heap()->barrier_set();
388 ct_bs->clear(MemRegion(bottom(), end()));
389 }
390
391 void HeapRegion::calc_gc_efficiency() {
392 // GC efficiency is the ratio of how much space would be
393 // reclaimed over how long we predict it would take to reclaim it.
394 G1CollectedHeap* g1h = G1CollectedHeap::heap();
395 G1CollectorPolicy* g1p = g1h->g1_policy();
396
397 // Retrieve a prediction of the elapsed time for this region for
398 // a mixed gc because the region will only be evacuated during a
399 // mixed gc.
400 double region_elapsed_time_ms =
401 g1p->predict_region_elapsed_time_ms(this, false /* for_young_gc */);
402 _gc_efficiency = (double) reclaimable_bytes() / region_elapsed_time_ms;
403 }
404
405 void HeapRegion::set_startsHumongous(HeapWord* new_top, HeapWord* new_end) {
406 assert(!isHumongous(), "sanity / pre-condition");
407 assert(end() == _orig_end,
408 "Should be normal before the humongous object allocation");
409 assert(top() == bottom(), "should be empty");
410 assert(bottom() <= new_top && new_top <= new_end, "pre-condition");
411
412 _humongous_type = StartsHumongous;
413 _humongous_start_region = this;
414
415 set_end(new_end);
416 _offsets.set_for_starts_humongous(new_top);
417 }
418
419 void HeapRegion::set_continuesHumongous(HeapRegion* first_hr) {
420 assert(!isHumongous(), "sanity / pre-condition");
421 assert(end() == _orig_end,
422 "Should be normal before the humongous object allocation");
423 assert(top() == bottom(), "should be empty");
424 assert(first_hr->startsHumongous(), "pre-condition");
425
426 _humongous_type = ContinuesHumongous;
427 _humongous_start_region = first_hr;
428 }
429
430 void HeapRegion::set_notHumongous() {
431 assert(isHumongous(), "pre-condition");
432
433 if (startsHumongous()) {
434 assert(top() <= end(), "pre-condition");
435 set_end(_orig_end);
436 if (top() > end()) {
437 // at least one "continues humongous" region after it
438 set_top(end());
439 }
440 } else {
441 // continues humongous
442 assert(end() == _orig_end, "sanity");
443 }
444
445 assert(capacity() == HeapRegion::GrainBytes, "pre-condition");
446 _humongous_type = NotHumongous;
447 _humongous_start_region = NULL;
448 }
449
450 bool HeapRegion::claimHeapRegion(jint claimValue) {
451 jint current = _claimed;
452 if (current != claimValue) {
453 jint res = Atomic::cmpxchg(claimValue, &_claimed, current);
454 if (res == current) {
455 return true;
456 }
457 }
458 return false;
459 }
460
461 HeapWord* HeapRegion::next_block_start_careful(HeapWord* addr) {
462 HeapWord* low = addr;
463 HeapWord* high = end();
464 while (low < high) {
465 size_t diff = pointer_delta(high, low);
466 // Must add one below to bias toward the high amount. Otherwise, if
467 // "high" were at the desired value, and "low" were one less, we
468 // would not converge on "high". This is not symmetric, because
469 // we set "high" to a block start, which might be the right one,
470 // which we don't do for "low".
471 HeapWord* middle = low + (diff+1)/2;
472 if (middle == high) return high;
473 HeapWord* mid_bs = block_start_careful(middle);
474 if (mid_bs < addr) {
475 low = middle;
476 } else {
477 high = mid_bs;
478 }
479 }
480 assert(low == high && low >= addr, "Didn't work.");
481 return low;
482 }
483
484 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
485 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
486 #endif // _MSC_VER
487
488
489 HeapRegion::HeapRegion(uint hrs_index,
490 G1BlockOffsetSharedArray* sharedOffsetArray,
491 MemRegion mr) :
492 G1OffsetTableContigSpace(sharedOffsetArray, mr),
493 _hrs_index(hrs_index),
494 _humongous_type(NotHumongous), _humongous_start_region(NULL),
495 _in_collection_set(false),
496 _next_in_special_set(NULL), _orig_end(NULL),
497 _claimed(InitialClaimValue), _evacuation_failed(false),
498 _prev_marked_bytes(0), _next_marked_bytes(0), _gc_efficiency(0.0),
499 _young_type(NotYoung), _next_young_region(NULL),
500 _next_dirty_cards_region(NULL), _next(NULL), _pending_removal(false),
501 #ifdef ASSERT
502 _containing_set(NULL),
503 #endif // ASSERT
504 _young_index_in_cset(-1), _surv_rate_group(NULL), _age_index(-1),
505 _rem_set(NULL), _recorded_rs_length(0), _predicted_elapsed_time_ms(0),
506 _predicted_bytes_to_copy(0)
507 {
508 _orig_end = mr.end();
509 // Note that initialize() will set the start of the unmarked area of the
510 // region.
511 hr_clear(false /*par*/, false /*clear_space*/);
512 set_top(bottom());
513 set_saved_mark();
514
515 _rem_set = new HeapRegionRemSet(sharedOffsetArray, this);
516
517 assert(HeapRegionRemSet::num_par_rem_sets() > 0, "Invariant.");
518 }
519
520 CompactibleSpace* HeapRegion::next_compaction_space() const {
521 // We're not using an iterator given that it will wrap around when
522 // it reaches the last region and this is not what we want here.
523 G1CollectedHeap* g1h = G1CollectedHeap::heap();
524 uint index = hrs_index() + 1;
525 while (index < g1h->n_regions()) {
526 HeapRegion* hr = g1h->region_at(index);
527 if (!hr->isHumongous()) {
528 return hr;
529 }
530 index += 1;
531 }
532 return NULL;
533 }
534
535 void HeapRegion::save_marks() {
536 set_saved_mark();
537 }
538
539 void HeapRegion::oops_in_mr_iterate(MemRegion mr, ExtendedOopClosure* cl) {
540 HeapWord* p = mr.start();
541 HeapWord* e = mr.end();
542 oop obj;
543 while (p < e) {
544 obj = oop(p);
545 p += obj->oop_iterate(cl);
546 }
547 assert(p == e, "bad memregion: doesn't end on obj boundary");
548 }
549
550 #define HeapRegion_OOP_SINCE_SAVE_MARKS_DEFN(OopClosureType, nv_suffix) \
551 void HeapRegion::oop_since_save_marks_iterate##nv_suffix(OopClosureType* cl) { \
552 ContiguousSpace::oop_since_save_marks_iterate##nv_suffix(cl); \
553 }
554 SPECIALIZED_SINCE_SAVE_MARKS_CLOSURES(HeapRegion_OOP_SINCE_SAVE_MARKS_DEFN)
555
556
557 void HeapRegion::oop_before_save_marks_iterate(ExtendedOopClosure* cl) {
558 oops_in_mr_iterate(MemRegion(bottom(), saved_mark_word()), cl);
559 }
560
561 void HeapRegion::note_self_forwarding_removal_start(bool during_initial_mark,
562 bool during_conc_mark) {
563 // We always recreate the prev marking info and we'll explicitly
564 // mark all objects we find to be self-forwarded on the prev
565 // bitmap. So all objects need to be below PTAMS.
566 _prev_top_at_mark_start = top();
567 _prev_marked_bytes = 0;
568
569 if (during_initial_mark) {
570 // During initial-mark, we'll also explicitly mark all objects
571 // we find to be self-forwarded on the next bitmap. So all
572 // objects need to be below NTAMS.
573 _next_top_at_mark_start = top();
574 _next_marked_bytes = 0;
575 } else if (during_conc_mark) {
576 // During concurrent mark, all objects in the CSet (including
577 // the ones we find to be self-forwarded) are implicitly live.
578 // So all objects need to be above NTAMS.
579 _next_top_at_mark_start = bottom();
580 _next_marked_bytes = 0;
581 }
582 }
583
584 void HeapRegion::note_self_forwarding_removal_end(bool during_initial_mark,
585 bool during_conc_mark,
586 size_t marked_bytes) {
587 assert(0 <= marked_bytes && marked_bytes <= used(),
588 err_msg("marked: "SIZE_FORMAT" used: "SIZE_FORMAT,
589 marked_bytes, used()));
590 _prev_marked_bytes = marked_bytes;
591 }
592
593 HeapWord*
594 HeapRegion::object_iterate_mem_careful(MemRegion mr,
595 ObjectClosure* cl) {
596 G1CollectedHeap* g1h = G1CollectedHeap::heap();
597 // We used to use "block_start_careful" here. But we're actually happy
598 // to update the BOT while we do this...
599 HeapWord* cur = block_start(mr.start());
600 mr = mr.intersection(used_region());
601 if (mr.is_empty()) return NULL;
602 // Otherwise, find the obj that extends onto mr.start().
603
604 assert(cur <= mr.start()
605 && (oop(cur)->klass_or_null() == NULL ||
606 cur + oop(cur)->size() > mr.start()),
607 "postcondition of block_start");
608 oop obj;
609 while (cur < mr.end()) {
610 obj = oop(cur);
611 if (obj->klass_or_null() == NULL) {
612 // Ran into an unparseable point.
613 return cur;
614 } else if (!g1h->is_obj_dead(obj)) {
615 cl->do_object(obj);
616 }
617 if (cl->abort()) return cur;
618 // The check above must occur before the operation below, since an
619 // abort might invalidate the "size" operation.
620 cur += obj->size();
621 }
622 return NULL;
623 }
624
625 HeapWord*
626 HeapRegion::
627 oops_on_card_seq_iterate_careful(MemRegion mr,
628 FilterOutOfRegionClosure* cl,
629 bool filter_young,
630 jbyte* card_ptr) {
631 // Currently, we should only have to clean the card if filter_young
632 // is true and vice versa.
633 if (filter_young) {
634 assert(card_ptr != NULL, "pre-condition");
635 } else {
636 assert(card_ptr == NULL, "pre-condition");
637 }
638 G1CollectedHeap* g1h = G1CollectedHeap::heap();
639
640 // If we're within a stop-world GC, then we might look at a card in a
641 // GC alloc region that extends onto a GC LAB, which may not be
642 // parseable. Stop such at the "saved_mark" of the region.
643 if (g1h->is_gc_active()) {
644 mr = mr.intersection(used_region_at_save_marks());
645 } else {
646 mr = mr.intersection(used_region());
647 }
648 if (mr.is_empty()) return NULL;
649 // Otherwise, find the obj that extends onto mr.start().
650
651 // The intersection of the incoming mr (for the card) and the
652 // allocated part of the region is non-empty. This implies that
653 // we have actually allocated into this region. The code in
654 // G1CollectedHeap.cpp that allocates a new region sets the
655 // is_young tag on the region before allocating. Thus we
656 // safely know if this region is young.
657 if (is_young() && filter_young) {
658 return NULL;
659 }
660
661 assert(!is_young(), "check value of filter_young");
662
663 // We can only clean the card here, after we make the decision that
664 // the card is not young. And we only clean the card if we have been
665 // asked to (i.e., card_ptr != NULL).
666 if (card_ptr != NULL) {
667 *card_ptr = CardTableModRefBS::clean_card_val();
668 // We must complete this write before we do any of the reads below.
669 OrderAccess::storeload();
670 }
671
672 // Cache the boundaries of the memory region in some const locals
673 HeapWord* const start = mr.start();
674 HeapWord* const end = mr.end();
675
676 // We used to use "block_start_careful" here. But we're actually happy
677 // to update the BOT while we do this...
678 HeapWord* cur = block_start(start);
679 assert(cur <= start, "Postcondition");
680
681 oop obj;
682
683 HeapWord* next = cur;
684 while (next <= start) {
685 cur = next;
686 obj = oop(cur);
687 if (obj->klass_or_null() == NULL) {
688 // Ran into an unparseable point.
689 return cur;
690 }
691 // Otherwise...
692 next = (cur + obj->size());
693 }
694
695 // If we finish the above loop...We have a parseable object that
696 // begins on or before the start of the memory region, and ends
697 // inside or spans the entire region.
698
699 assert(obj == oop(cur), "sanity");
700 assert(cur <= start &&
701 obj->klass_or_null() != NULL &&
702 (cur + obj->size()) > start,
703 "Loop postcondition");
704
705 if (!g1h->is_obj_dead(obj)) {
706 obj->oop_iterate(cl, mr);
707 }
708
709 while (cur < end) {
710 obj = oop(cur);
711 if (obj->klass_or_null() == NULL) {
712 // Ran into an unparseable point.
713 return cur;
714 };
715
716 // Otherwise:
717 next = (cur + obj->size());
718
719 if (!g1h->is_obj_dead(obj)) {
720 if (next < end || !obj->is_objArray()) {
721 // This object either does not span the MemRegion
722 // boundary, or if it does it's not an array.
723 // Apply closure to whole object.
724 obj->oop_iterate(cl);
725 } else {
726 // This obj is an array that spans the boundary.
727 // Stop at the boundary.
728 obj->oop_iterate(cl, mr);
729 }
730 }
731 cur = next;
732 }
733 return NULL;
734 }
735
736 void HeapRegion::print() const { print_on(gclog_or_tty); }
737 void HeapRegion::print_on(outputStream* st) const {
738 if (isHumongous()) {
739 if (startsHumongous())
740 st->print(" HS");
741 else
742 st->print(" HC");
743 } else {
744 st->print(" ");
745 }
746 if (in_collection_set())
747 st->print(" CS");
748 else
749 st->print(" ");
750 if (is_young())
751 st->print(is_survivor() ? " SU" : " Y ");
752 else
753 st->print(" ");
754 if (is_empty())
755 st->print(" F");
756 else
757 st->print(" ");
758 st->print(" TS %5d", _gc_time_stamp);
759 st->print(" PTAMS "PTR_FORMAT" NTAMS "PTR_FORMAT,
760 prev_top_at_mark_start(), next_top_at_mark_start());
761 G1OffsetTableContigSpace::print_on(st);
762 }
763
764 void HeapRegion::verify() const {
765 bool dummy = false;
766 verify(VerifyOption_G1UsePrevMarking, /* failures */ &dummy);
767 }
768
769 // This really ought to be commoned up into OffsetTableContigSpace somehow.
770 // We would need a mechanism to make that code skip dead objects.
771
772 void HeapRegion::verify(VerifyOption vo,
773 bool* failures) const {
774 G1CollectedHeap* g1 = G1CollectedHeap::heap();
775 *failures = false;
776 HeapWord* p = bottom();
777 HeapWord* prev_p = NULL;
778 VerifyLiveClosure vl_cl(g1, vo);
779 bool is_humongous = isHumongous();
780 bool do_bot_verify = !is_young();
781 size_t object_num = 0;
782 while (p < top()) {
783 oop obj = oop(p);
784 size_t obj_size = obj->size();
785 object_num += 1;
786
787 if (is_humongous != g1->isHumongous(obj_size)) {
788 gclog_or_tty->print_cr("obj "PTR_FORMAT" is of %shumongous size ("
789 SIZE_FORMAT" words) in a %shumongous region",
790 p, g1->isHumongous(obj_size) ? "" : "non-",
791 obj_size, is_humongous ? "" : "non-");
792 *failures = true;
793 return;
794 }
795
796 // If it returns false, verify_for_object() will output the
797 // appropriate messasge.
798 if (do_bot_verify && !_offsets.verify_for_object(p, obj_size)) {
799 *failures = true;
800 return;
801 }
802
803 if (!g1->is_obj_dead_cond(obj, this, vo)) {
804 if (obj->is_oop()) {
805 Klass* klass = obj->klass();
806 if (!klass->is_metaspace_object()) {
807 gclog_or_tty->print_cr("klass "PTR_FORMAT" of object "PTR_FORMAT" "
808 "not metadata", klass, obj);
809 *failures = true;
810 return;
811 } else if (!klass->is_klass()) {
812 gclog_or_tty->print_cr("klass "PTR_FORMAT" of object "PTR_FORMAT" "
813 "not a klass", klass, obj);
814 *failures = true;
815 return;
816 } else {
817 vl_cl.set_containing_obj(obj);
818 obj->oop_iterate_no_header(&vl_cl);
819 if (vl_cl.failures()) {
820 *failures = true;
821 }
822 if (G1MaxVerifyFailures >= 0 &&
823 vl_cl.n_failures() >= G1MaxVerifyFailures) {
824 return;
825 }
826 }
827 } else {
828 gclog_or_tty->print_cr(PTR_FORMAT" no an oop", obj);
829 *failures = true;
830 return;
831 }
832 }
833 prev_p = p;
834 p += obj_size;
835 }
836
837 if (p != top()) {
838 gclog_or_tty->print_cr("end of last object "PTR_FORMAT" "
839 "does not match top "PTR_FORMAT, p, top());
840 *failures = true;
841 return;
842 }
843
844 HeapWord* the_end = end();
845 assert(p == top(), "it should still hold");
846 // Do some extra BOT consistency checking for addresses in the
847 // range [top, end). BOT look-ups in this range should yield
848 // top. No point in doing that if top == end (there's nothing there).
849 if (p < the_end) {
850 // Look up top
851 HeapWord* addr_1 = p;
852 HeapWord* b_start_1 = _offsets.block_start_const(addr_1);
853 if (b_start_1 != p) {
854 gclog_or_tty->print_cr("BOT look up for top: "PTR_FORMAT" "
855 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
856 addr_1, b_start_1, p);
857 *failures = true;
858 return;
859 }
860
861 // Look up top + 1
862 HeapWord* addr_2 = p + 1;
863 if (addr_2 < the_end) {
864 HeapWord* b_start_2 = _offsets.block_start_const(addr_2);
865 if (b_start_2 != p) {
866 gclog_or_tty->print_cr("BOT look up for top + 1: "PTR_FORMAT" "
867 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
868 addr_2, b_start_2, p);
869 *failures = true;
870 return;
871 }
872 }
873
874 // Look up an address between top and end
875 size_t diff = pointer_delta(the_end, p) / 2;
876 HeapWord* addr_3 = p + diff;
877 if (addr_3 < the_end) {
878 HeapWord* b_start_3 = _offsets.block_start_const(addr_3);
879 if (b_start_3 != p) {
880 gclog_or_tty->print_cr("BOT look up for top + diff: "PTR_FORMAT" "
881 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
882 addr_3, b_start_3, p);
883 *failures = true;
884 return;
885 }
886 }
887
888 // Loook up end - 1
889 HeapWord* addr_4 = the_end - 1;
890 HeapWord* b_start_4 = _offsets.block_start_const(addr_4);
891 if (b_start_4 != p) {
892 gclog_or_tty->print_cr("BOT look up for end - 1: "PTR_FORMAT" "
893 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
894 addr_4, b_start_4, p);
895 *failures = true;
896 return;
897 }
898 }
899
900 if (is_humongous && object_num > 1) {
901 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] is humongous "
902 "but has "SIZE_FORMAT", objects",
903 bottom(), end(), object_num);
904 *failures = true;
905 return;
906 }
907 }
908
909 // G1OffsetTableContigSpace code; copied from space.cpp. Hope this can go
910 // away eventually.
911
912 void G1OffsetTableContigSpace::clear(bool mangle_space) {
913 ContiguousSpace::clear(mangle_space);
914 _offsets.zero_bottom_entry();
915 _offsets.initialize_threshold();
916 }
917
918 void G1OffsetTableContigSpace::set_bottom(HeapWord* new_bottom) {
919 Space::set_bottom(new_bottom);
920 _offsets.set_bottom(new_bottom);
921 }
922
923 void G1OffsetTableContigSpace::set_end(HeapWord* new_end) {
924 Space::set_end(new_end);
925 _offsets.resize(new_end - bottom());
926 }
927
928 void G1OffsetTableContigSpace::print() const {
929 print_short();
930 gclog_or_tty->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", "
931 INTPTR_FORMAT ", " INTPTR_FORMAT ")",
932 bottom(), top(), _offsets.threshold(), end());
933 }
934
935 HeapWord* G1OffsetTableContigSpace::initialize_threshold() {
936 return _offsets.initialize_threshold();
937 }
938
939 HeapWord* G1OffsetTableContigSpace::cross_threshold(HeapWord* start,
940 HeapWord* end) {
941 _offsets.alloc_block(start, end);
942 return _offsets.threshold();
943 }
944
945 HeapWord* G1OffsetTableContigSpace::saved_mark_word() const {
946 G1CollectedHeap* g1h = G1CollectedHeap::heap();
947 assert( _gc_time_stamp <= g1h->get_gc_time_stamp(), "invariant" );
948 if (_gc_time_stamp < g1h->get_gc_time_stamp())
949 return top();
950 else
951 return ContiguousSpace::saved_mark_word();
952 }
953
954 void G1OffsetTableContigSpace::set_saved_mark() {
955 G1CollectedHeap* g1h = G1CollectedHeap::heap();
956 unsigned curr_gc_time_stamp = g1h->get_gc_time_stamp();
957
958 if (_gc_time_stamp < curr_gc_time_stamp) {
959 // The order of these is important, as another thread might be
960 // about to start scanning this region. If it does so after
961 // set_saved_mark and before _gc_time_stamp = ..., then the latter
962 // will be false, and it will pick up top() as the high water mark
963 // of region. If it does so after _gc_time_stamp = ..., then it
964 // will pick up the right saved_mark_word() as the high water mark
965 // of the region. Either way, the behaviour will be correct.
966 ContiguousSpace::set_saved_mark();
967 OrderAccess::storestore();
968 _gc_time_stamp = curr_gc_time_stamp;
969 // No need to do another barrier to flush the writes above. If
970 // this is called in parallel with other threads trying to
971 // allocate into the region, the caller should call this while
972 // holding a lock and when the lock is released the writes will be
973 // flushed.
974 }
975 }
976
977 G1OffsetTableContigSpace::
978 G1OffsetTableContigSpace(G1BlockOffsetSharedArray* sharedOffsetArray,
979 MemRegion mr) :
980 _offsets(sharedOffsetArray, mr),
981 _par_alloc_lock(Mutex::leaf, "OffsetTableContigSpace par alloc lock", true),
982 _gc_time_stamp(0)
983 {
984 _offsets.set_space(this);
985 // false ==> we'll do the clearing if there's clearing to be done.
986 ContiguousSpace::initialize(mr, false, SpaceDecorator::Mangle);
987 _offsets.zero_bottom_entry();
988 _offsets.initialize_threshold();
989 }