Fri, 29 Aug 2014 13:12:21 +0200
8048268: G1 Code Root Migration performs poorly
Summary: Replace G1CodeRootSet with a Hashtable based implementation, merge Code Root Migration phase into Code Root Scanning
Reviewed-by: jmasa, brutisso, tschatzl
1 /*
2 * Copyright (c) 2001, 2014, 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 */
25 #include "precompiled.hpp"
26 #include "code/nmethod.hpp"
27 #include "gc_implementation/g1/g1BlockOffsetTable.inline.hpp"
28 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
29 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
30 #include "gc_implementation/g1/heapRegion.inline.hpp"
31 #include "gc_implementation/g1/heapRegionBounds.inline.hpp"
32 #include "gc_implementation/g1/heapRegionRemSet.hpp"
33 #include "gc_implementation/g1/heapRegionManager.inline.hpp"
34 #include "gc_implementation/shared/liveRange.hpp"
35 #include "memory/genOopClosures.inline.hpp"
36 #include "memory/iterator.hpp"
37 #include "memory/space.inline.hpp"
38 #include "oops/oop.inline.hpp"
39 #include "runtime/orderAccess.inline.hpp"
41 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
43 int HeapRegion::LogOfHRGrainBytes = 0;
44 int HeapRegion::LogOfHRGrainWords = 0;
45 size_t HeapRegion::GrainBytes = 0;
46 size_t HeapRegion::GrainWords = 0;
47 size_t HeapRegion::CardsPerRegion = 0;
49 HeapRegionDCTOC::HeapRegionDCTOC(G1CollectedHeap* g1,
50 HeapRegion* hr, ExtendedOopClosure* cl,
51 CardTableModRefBS::PrecisionStyle precision,
52 FilterKind fk) :
53 DirtyCardToOopClosure(hr, cl, precision, NULL),
54 _hr(hr), _fk(fk), _g1(g1) { }
56 FilterOutOfRegionClosure::FilterOutOfRegionClosure(HeapRegion* r,
57 OopClosure* oc) :
58 _r_bottom(r->bottom()), _r_end(r->end()), _oc(oc) { }
60 template<class ClosureType>
61 HeapWord* walk_mem_region_loop(ClosureType* cl, G1CollectedHeap* g1h,
62 HeapRegion* hr,
63 HeapWord* cur, HeapWord* top) {
64 oop cur_oop = oop(cur);
65 size_t oop_size = hr->block_size(cur);
66 HeapWord* next_obj = cur + oop_size;
67 while (next_obj < top) {
68 // Keep filtering the remembered set.
69 if (!g1h->is_obj_dead(cur_oop, hr)) {
70 // Bottom lies entirely below top, so we can call the
71 // non-memRegion version of oop_iterate below.
72 cur_oop->oop_iterate(cl);
73 }
74 cur = next_obj;
75 cur_oop = oop(cur);
76 oop_size = hr->block_size(cur);
77 next_obj = cur + oop_size;
78 }
79 return cur;
80 }
82 void HeapRegionDCTOC::walk_mem_region(MemRegion mr,
83 HeapWord* bottom,
84 HeapWord* top) {
85 G1CollectedHeap* g1h = _g1;
86 size_t oop_size;
87 ExtendedOopClosure* cl2 = NULL;
89 FilterIntoCSClosure intoCSFilt(this, g1h, _cl);
90 FilterOutOfRegionClosure outOfRegionFilt(_hr, _cl);
92 switch (_fk) {
93 case NoFilterKind: cl2 = _cl; break;
94 case IntoCSFilterKind: cl2 = &intoCSFilt; break;
95 case OutOfRegionFilterKind: cl2 = &outOfRegionFilt; break;
96 default: ShouldNotReachHere();
97 }
99 // Start filtering what we add to the remembered set. If the object is
100 // not considered dead, either because it is marked (in the mark bitmap)
101 // or it was allocated after marking finished, then we add it. Otherwise
102 // we can safely ignore the object.
103 if (!g1h->is_obj_dead(oop(bottom), _hr)) {
104 oop_size = oop(bottom)->oop_iterate(cl2, mr);
105 } else {
106 oop_size = _hr->block_size(bottom);
107 }
109 bottom += oop_size;
111 if (bottom < top) {
112 // We replicate the loop below for several kinds of possible filters.
113 switch (_fk) {
114 case NoFilterKind:
115 bottom = walk_mem_region_loop(_cl, g1h, _hr, bottom, top);
116 break;
118 case IntoCSFilterKind: {
119 FilterIntoCSClosure filt(this, g1h, _cl);
120 bottom = walk_mem_region_loop(&filt, g1h, _hr, bottom, top);
121 break;
122 }
124 case OutOfRegionFilterKind: {
125 FilterOutOfRegionClosure filt(_hr, _cl);
126 bottom = walk_mem_region_loop(&filt, g1h, _hr, bottom, top);
127 break;
128 }
130 default:
131 ShouldNotReachHere();
132 }
134 // Last object. Need to do dead-obj filtering here too.
135 if (!g1h->is_obj_dead(oop(bottom), _hr)) {
136 oop(bottom)->oop_iterate(cl2, mr);
137 }
138 }
139 }
141 size_t HeapRegion::max_region_size() {
142 return HeapRegionBounds::max_size();
143 }
145 void HeapRegion::setup_heap_region_size(size_t initial_heap_size, size_t max_heap_size) {
146 uintx region_size = G1HeapRegionSize;
147 if (FLAG_IS_DEFAULT(G1HeapRegionSize)) {
148 size_t average_heap_size = (initial_heap_size + max_heap_size) / 2;
149 region_size = MAX2(average_heap_size / HeapRegionBounds::target_number(),
150 (uintx) HeapRegionBounds::min_size());
151 }
153 int region_size_log = log2_long((jlong) region_size);
154 // Recalculate the region size to make sure it's a power of
155 // 2. This means that region_size is the largest power of 2 that's
156 // <= what we've calculated so far.
157 region_size = ((uintx)1 << region_size_log);
159 // Now make sure that we don't go over or under our limits.
160 if (region_size < HeapRegionBounds::min_size()) {
161 region_size = HeapRegionBounds::min_size();
162 } else if (region_size > HeapRegionBounds::max_size()) {
163 region_size = HeapRegionBounds::max_size();
164 }
166 // And recalculate the log.
167 region_size_log = log2_long((jlong) region_size);
169 // Now, set up the globals.
170 guarantee(LogOfHRGrainBytes == 0, "we should only set it once");
171 LogOfHRGrainBytes = region_size_log;
173 guarantee(LogOfHRGrainWords == 0, "we should only set it once");
174 LogOfHRGrainWords = LogOfHRGrainBytes - LogHeapWordSize;
176 guarantee(GrainBytes == 0, "we should only set it once");
177 // The cast to int is safe, given that we've bounded region_size by
178 // MIN_REGION_SIZE and MAX_REGION_SIZE.
179 GrainBytes = (size_t)region_size;
181 guarantee(GrainWords == 0, "we should only set it once");
182 GrainWords = GrainBytes >> LogHeapWordSize;
183 guarantee((size_t) 1 << LogOfHRGrainWords == GrainWords, "sanity");
185 guarantee(CardsPerRegion == 0, "we should only set it once");
186 CardsPerRegion = GrainBytes >> CardTableModRefBS::card_shift;
187 }
189 void HeapRegion::reset_after_compaction() {
190 G1OffsetTableContigSpace::reset_after_compaction();
191 // After a compaction the mark bitmap is invalid, so we must
192 // treat all objects as being inside the unmarked area.
193 zero_marked_bytes();
194 init_top_at_mark_start();
195 }
197 void HeapRegion::hr_clear(bool par, bool clear_space, bool locked) {
198 assert(_humongous_start_region == NULL,
199 "we should have already filtered out humongous regions");
200 assert(_end == _orig_end,
201 "we should have already filtered out humongous regions");
203 _in_collection_set = false;
205 set_allocation_context(AllocationContext::system());
206 set_young_index_in_cset(-1);
207 uninstall_surv_rate_group();
208 set_free();
209 reset_pre_dummy_top();
211 if (!par) {
212 // If this is parallel, this will be done later.
213 HeapRegionRemSet* hrrs = rem_set();
214 if (locked) {
215 hrrs->clear_locked();
216 } else {
217 hrrs->clear();
218 }
219 _claimed = InitialClaimValue;
220 }
221 zero_marked_bytes();
223 _offsets.resize(HeapRegion::GrainWords);
224 init_top_at_mark_start();
225 if (clear_space) clear(SpaceDecorator::Mangle);
226 }
228 void HeapRegion::par_clear() {
229 assert(used() == 0, "the region should have been already cleared");
230 assert(capacity() == HeapRegion::GrainBytes, "should be back to normal");
231 HeapRegionRemSet* hrrs = rem_set();
232 hrrs->clear();
233 CardTableModRefBS* ct_bs =
234 (CardTableModRefBS*)G1CollectedHeap::heap()->barrier_set();
235 ct_bs->clear(MemRegion(bottom(), end()));
236 }
238 void HeapRegion::calc_gc_efficiency() {
239 // GC efficiency is the ratio of how much space would be
240 // reclaimed over how long we predict it would take to reclaim it.
241 G1CollectedHeap* g1h = G1CollectedHeap::heap();
242 G1CollectorPolicy* g1p = g1h->g1_policy();
244 // Retrieve a prediction of the elapsed time for this region for
245 // a mixed gc because the region will only be evacuated during a
246 // mixed gc.
247 double region_elapsed_time_ms =
248 g1p->predict_region_elapsed_time_ms(this, false /* for_young_gc */);
249 _gc_efficiency = (double) reclaimable_bytes() / region_elapsed_time_ms;
250 }
252 void HeapRegion::set_startsHumongous(HeapWord* new_top, HeapWord* new_end) {
253 assert(!isHumongous(), "sanity / pre-condition");
254 assert(end() == _orig_end,
255 "Should be normal before the humongous object allocation");
256 assert(top() == bottom(), "should be empty");
257 assert(bottom() <= new_top && new_top <= new_end, "pre-condition");
259 _type.set_starts_humongous();
260 _humongous_start_region = this;
262 set_end(new_end);
263 _offsets.set_for_starts_humongous(new_top);
264 }
266 void HeapRegion::set_continuesHumongous(HeapRegion* first_hr) {
267 assert(!isHumongous(), "sanity / pre-condition");
268 assert(end() == _orig_end,
269 "Should be normal before the humongous object allocation");
270 assert(top() == bottom(), "should be empty");
271 assert(first_hr->startsHumongous(), "pre-condition");
273 _type.set_continues_humongous();
274 _humongous_start_region = first_hr;
275 }
277 void HeapRegion::clear_humongous() {
278 assert(isHumongous(), "pre-condition");
280 if (startsHumongous()) {
281 assert(top() <= end(), "pre-condition");
282 set_end(_orig_end);
283 if (top() > end()) {
284 // at least one "continues humongous" region after it
285 set_top(end());
286 }
287 } else {
288 // continues humongous
289 assert(end() == _orig_end, "sanity");
290 }
292 assert(capacity() == HeapRegion::GrainBytes, "pre-condition");
293 _humongous_start_region = NULL;
294 }
296 bool HeapRegion::claimHeapRegion(jint claimValue) {
297 jint current = _claimed;
298 if (current != claimValue) {
299 jint res = Atomic::cmpxchg(claimValue, &_claimed, current);
300 if (res == current) {
301 return true;
302 }
303 }
304 return false;
305 }
307 HeapWord* HeapRegion::next_block_start_careful(HeapWord* addr) {
308 HeapWord* low = addr;
309 HeapWord* high = end();
310 while (low < high) {
311 size_t diff = pointer_delta(high, low);
312 // Must add one below to bias toward the high amount. Otherwise, if
313 // "high" were at the desired value, and "low" were one less, we
314 // would not converge on "high". This is not symmetric, because
315 // we set "high" to a block start, which might be the right one,
316 // which we don't do for "low".
317 HeapWord* middle = low + (diff+1)/2;
318 if (middle == high) return high;
319 HeapWord* mid_bs = block_start_careful(middle);
320 if (mid_bs < addr) {
321 low = middle;
322 } else {
323 high = mid_bs;
324 }
325 }
326 assert(low == high && low >= addr, "Didn't work.");
327 return low;
328 }
330 HeapRegion::HeapRegion(uint hrm_index,
331 G1BlockOffsetSharedArray* sharedOffsetArray,
332 MemRegion mr) :
333 G1OffsetTableContigSpace(sharedOffsetArray, mr),
334 _hrm_index(hrm_index),
335 _allocation_context(AllocationContext::system()),
336 _humongous_start_region(NULL),
337 _in_collection_set(false),
338 _next_in_special_set(NULL), _orig_end(NULL),
339 _claimed(InitialClaimValue), _evacuation_failed(false),
340 _prev_marked_bytes(0), _next_marked_bytes(0), _gc_efficiency(0.0),
341 _next_young_region(NULL),
342 _next_dirty_cards_region(NULL), _next(NULL), _prev(NULL),
343 #ifdef ASSERT
344 _containing_set(NULL),
345 #endif // ASSERT
346 _young_index_in_cset(-1), _surv_rate_group(NULL), _age_index(-1),
347 _rem_set(NULL), _recorded_rs_length(0), _predicted_elapsed_time_ms(0),
348 _predicted_bytes_to_copy(0)
349 {
350 _rem_set = new HeapRegionRemSet(sharedOffsetArray, this);
351 assert(HeapRegionRemSet::num_par_rem_sets() > 0, "Invariant.");
353 initialize(mr);
354 }
356 void HeapRegion::initialize(MemRegion mr, bool clear_space, bool mangle_space) {
357 assert(_rem_set->is_empty(), "Remembered set must be empty");
359 G1OffsetTableContigSpace::initialize(mr, clear_space, mangle_space);
361 _orig_end = mr.end();
362 hr_clear(false /*par*/, false /*clear_space*/);
363 set_top(bottom());
364 record_top_and_timestamp();
365 }
367 CompactibleSpace* HeapRegion::next_compaction_space() const {
368 return G1CollectedHeap::heap()->next_compaction_region(this);
369 }
371 void HeapRegion::note_self_forwarding_removal_start(bool during_initial_mark,
372 bool during_conc_mark) {
373 // We always recreate the prev marking info and we'll explicitly
374 // mark all objects we find to be self-forwarded on the prev
375 // bitmap. So all objects need to be below PTAMS.
376 _prev_marked_bytes = 0;
378 if (during_initial_mark) {
379 // During initial-mark, we'll also explicitly mark all objects
380 // we find to be self-forwarded on the next bitmap. So all
381 // objects need to be below NTAMS.
382 _next_top_at_mark_start = top();
383 _next_marked_bytes = 0;
384 } else if (during_conc_mark) {
385 // During concurrent mark, all objects in the CSet (including
386 // the ones we find to be self-forwarded) are implicitly live.
387 // So all objects need to be above NTAMS.
388 _next_top_at_mark_start = bottom();
389 _next_marked_bytes = 0;
390 }
391 }
393 void HeapRegion::note_self_forwarding_removal_end(bool during_initial_mark,
394 bool during_conc_mark,
395 size_t marked_bytes) {
396 assert(0 <= marked_bytes && marked_bytes <= used(),
397 err_msg("marked: "SIZE_FORMAT" used: "SIZE_FORMAT,
398 marked_bytes, used()));
399 _prev_top_at_mark_start = top();
400 _prev_marked_bytes = marked_bytes;
401 }
403 HeapWord*
404 HeapRegion::object_iterate_mem_careful(MemRegion mr,
405 ObjectClosure* cl) {
406 G1CollectedHeap* g1h = G1CollectedHeap::heap();
407 // We used to use "block_start_careful" here. But we're actually happy
408 // to update the BOT while we do this...
409 HeapWord* cur = block_start(mr.start());
410 mr = mr.intersection(used_region());
411 if (mr.is_empty()) return NULL;
412 // Otherwise, find the obj that extends onto mr.start().
414 assert(cur <= mr.start()
415 && (oop(cur)->klass_or_null() == NULL ||
416 cur + oop(cur)->size() > mr.start()),
417 "postcondition of block_start");
418 oop obj;
419 while (cur < mr.end()) {
420 obj = oop(cur);
421 if (obj->klass_or_null() == NULL) {
422 // Ran into an unparseable point.
423 return cur;
424 } else if (!g1h->is_obj_dead(obj)) {
425 cl->do_object(obj);
426 }
427 if (cl->abort()) return cur;
428 // The check above must occur before the operation below, since an
429 // abort might invalidate the "size" operation.
430 cur += block_size(cur);
431 }
432 return NULL;
433 }
435 HeapWord*
436 HeapRegion::
437 oops_on_card_seq_iterate_careful(MemRegion mr,
438 FilterOutOfRegionClosure* cl,
439 bool filter_young,
440 jbyte* card_ptr) {
441 // Currently, we should only have to clean the card if filter_young
442 // is true and vice versa.
443 if (filter_young) {
444 assert(card_ptr != NULL, "pre-condition");
445 } else {
446 assert(card_ptr == NULL, "pre-condition");
447 }
448 G1CollectedHeap* g1h = G1CollectedHeap::heap();
450 // If we're within a stop-world GC, then we might look at a card in a
451 // GC alloc region that extends onto a GC LAB, which may not be
452 // parseable. Stop such at the "saved_mark" of the region.
453 if (g1h->is_gc_active()) {
454 mr = mr.intersection(used_region_at_save_marks());
455 } else {
456 mr = mr.intersection(used_region());
457 }
458 if (mr.is_empty()) return NULL;
459 // Otherwise, find the obj that extends onto mr.start().
461 // The intersection of the incoming mr (for the card) and the
462 // allocated part of the region is non-empty. This implies that
463 // we have actually allocated into this region. The code in
464 // G1CollectedHeap.cpp that allocates a new region sets the
465 // is_young tag on the region before allocating. Thus we
466 // safely know if this region is young.
467 if (is_young() && filter_young) {
468 return NULL;
469 }
471 assert(!is_young(), "check value of filter_young");
473 // We can only clean the card here, after we make the decision that
474 // the card is not young. And we only clean the card if we have been
475 // asked to (i.e., card_ptr != NULL).
476 if (card_ptr != NULL) {
477 *card_ptr = CardTableModRefBS::clean_card_val();
478 // We must complete this write before we do any of the reads below.
479 OrderAccess::storeload();
480 }
482 // Cache the boundaries of the memory region in some const locals
483 HeapWord* const start = mr.start();
484 HeapWord* const end = mr.end();
486 // We used to use "block_start_careful" here. But we're actually happy
487 // to update the BOT while we do this...
488 HeapWord* cur = block_start(start);
489 assert(cur <= start, "Postcondition");
491 oop obj;
493 HeapWord* next = cur;
494 while (next <= start) {
495 cur = next;
496 obj = oop(cur);
497 if (obj->klass_or_null() == NULL) {
498 // Ran into an unparseable point.
499 return cur;
500 }
501 // Otherwise...
502 next = cur + block_size(cur);
503 }
505 // If we finish the above loop...We have a parseable object that
506 // begins on or before the start of the memory region, and ends
507 // inside or spans the entire region.
509 assert(obj == oop(cur), "sanity");
510 assert(cur <= start, "Loop postcondition");
511 assert(obj->klass_or_null() != NULL, "Loop postcondition");
512 assert((cur + block_size(cur)) > start, "Loop postcondition");
514 if (!g1h->is_obj_dead(obj)) {
515 obj->oop_iterate(cl, mr);
516 }
518 while (cur < end) {
519 obj = oop(cur);
520 if (obj->klass_or_null() == NULL) {
521 // Ran into an unparseable point.
522 return cur;
523 };
525 // Otherwise:
526 next = cur + block_size(cur);
528 if (!g1h->is_obj_dead(obj)) {
529 if (next < end || !obj->is_objArray()) {
530 // This object either does not span the MemRegion
531 // boundary, or if it does it's not an array.
532 // Apply closure to whole object.
533 obj->oop_iterate(cl);
534 } else {
535 // This obj is an array that spans the boundary.
536 // Stop at the boundary.
537 obj->oop_iterate(cl, mr);
538 }
539 }
540 cur = next;
541 }
542 return NULL;
543 }
545 // Code roots support
547 void HeapRegion::add_strong_code_root(nmethod* nm) {
548 HeapRegionRemSet* hrrs = rem_set();
549 hrrs->add_strong_code_root(nm);
550 }
552 void HeapRegion::add_strong_code_root_locked(nmethod* nm) {
553 assert_locked_or_safepoint(CodeCache_lock);
554 HeapRegionRemSet* hrrs = rem_set();
555 hrrs->add_strong_code_root_locked(nm);
556 }
558 void HeapRegion::remove_strong_code_root(nmethod* nm) {
559 HeapRegionRemSet* hrrs = rem_set();
560 hrrs->remove_strong_code_root(nm);
561 }
563 void HeapRegion::strong_code_roots_do(CodeBlobClosure* blk) const {
564 HeapRegionRemSet* hrrs = rem_set();
565 hrrs->strong_code_roots_do(blk);
566 }
568 class VerifyStrongCodeRootOopClosure: public OopClosure {
569 const HeapRegion* _hr;
570 nmethod* _nm;
571 bool _failures;
572 bool _has_oops_in_region;
574 template <class T> void do_oop_work(T* p) {
575 T heap_oop = oopDesc::load_heap_oop(p);
576 if (!oopDesc::is_null(heap_oop)) {
577 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
579 // Note: not all the oops embedded in the nmethod are in the
580 // current region. We only look at those which are.
581 if (_hr->is_in(obj)) {
582 // Object is in the region. Check that its less than top
583 if (_hr->top() <= (HeapWord*)obj) {
584 // Object is above top
585 gclog_or_tty->print_cr("Object "PTR_FORMAT" in region "
586 "["PTR_FORMAT", "PTR_FORMAT") is above "
587 "top "PTR_FORMAT,
588 (void *)obj, _hr->bottom(), _hr->end(), _hr->top());
589 _failures = true;
590 return;
591 }
592 // Nmethod has at least one oop in the current region
593 _has_oops_in_region = true;
594 }
595 }
596 }
598 public:
599 VerifyStrongCodeRootOopClosure(const HeapRegion* hr, nmethod* nm):
600 _hr(hr), _failures(false), _has_oops_in_region(false) {}
602 void do_oop(narrowOop* p) { do_oop_work(p); }
603 void do_oop(oop* p) { do_oop_work(p); }
605 bool failures() { return _failures; }
606 bool has_oops_in_region() { return _has_oops_in_region; }
607 };
609 class VerifyStrongCodeRootCodeBlobClosure: public CodeBlobClosure {
610 const HeapRegion* _hr;
611 bool _failures;
612 public:
613 VerifyStrongCodeRootCodeBlobClosure(const HeapRegion* hr) :
614 _hr(hr), _failures(false) {}
616 void do_code_blob(CodeBlob* cb) {
617 nmethod* nm = (cb == NULL) ? NULL : cb->as_nmethod_or_null();
618 if (nm != NULL) {
619 // Verify that the nemthod is live
620 if (!nm->is_alive()) {
621 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] has dead nmethod "
622 PTR_FORMAT" in its strong code roots",
623 _hr->bottom(), _hr->end(), nm);
624 _failures = true;
625 } else {
626 VerifyStrongCodeRootOopClosure oop_cl(_hr, nm);
627 nm->oops_do(&oop_cl);
628 if (!oop_cl.has_oops_in_region()) {
629 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] has nmethod "
630 PTR_FORMAT" in its strong code roots "
631 "with no pointers into region",
632 _hr->bottom(), _hr->end(), nm);
633 _failures = true;
634 } else if (oop_cl.failures()) {
635 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] has other "
636 "failures for nmethod "PTR_FORMAT,
637 _hr->bottom(), _hr->end(), nm);
638 _failures = true;
639 }
640 }
641 }
642 }
644 bool failures() { return _failures; }
645 };
647 void HeapRegion::verify_strong_code_roots(VerifyOption vo, bool* failures) const {
648 if (!G1VerifyHeapRegionCodeRoots) {
649 // We're not verifying code roots.
650 return;
651 }
652 if (vo == VerifyOption_G1UseMarkWord) {
653 // Marking verification during a full GC is performed after class
654 // unloading, code cache unloading, etc so the strong code roots
655 // attached to each heap region are in an inconsistent state. They won't
656 // be consistent until the strong code roots are rebuilt after the
657 // actual GC. Skip verifying the strong code roots in this particular
658 // time.
659 assert(VerifyDuringGC, "only way to get here");
660 return;
661 }
663 HeapRegionRemSet* hrrs = rem_set();
664 size_t strong_code_roots_length = hrrs->strong_code_roots_list_length();
666 // if this region is empty then there should be no entries
667 // on its strong code root list
668 if (is_empty()) {
669 if (strong_code_roots_length > 0) {
670 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] is empty "
671 "but has "SIZE_FORMAT" code root entries",
672 bottom(), end(), strong_code_roots_length);
673 *failures = true;
674 }
675 return;
676 }
678 if (continuesHumongous()) {
679 if (strong_code_roots_length > 0) {
680 gclog_or_tty->print_cr("region "HR_FORMAT" is a continuation of a humongous "
681 "region but has "SIZE_FORMAT" code root entries",
682 HR_FORMAT_PARAMS(this), strong_code_roots_length);
683 *failures = true;
684 }
685 return;
686 }
688 VerifyStrongCodeRootCodeBlobClosure cb_cl(this);
689 strong_code_roots_do(&cb_cl);
691 if (cb_cl.failures()) {
692 *failures = true;
693 }
694 }
696 void HeapRegion::print() const { print_on(gclog_or_tty); }
697 void HeapRegion::print_on(outputStream* st) const {
698 st->print("AC%4u", allocation_context());
699 st->print(" %2s", get_short_type_str());
700 if (in_collection_set())
701 st->print(" CS");
702 else
703 st->print(" ");
704 st->print(" TS %5d", _gc_time_stamp);
705 st->print(" PTAMS "PTR_FORMAT" NTAMS "PTR_FORMAT,
706 prev_top_at_mark_start(), next_top_at_mark_start());
707 G1OffsetTableContigSpace::print_on(st);
708 }
710 class VerifyLiveClosure: public OopClosure {
711 private:
712 G1CollectedHeap* _g1h;
713 CardTableModRefBS* _bs;
714 oop _containing_obj;
715 bool _failures;
716 int _n_failures;
717 VerifyOption _vo;
718 public:
719 // _vo == UsePrevMarking -> use "prev" marking information,
720 // _vo == UseNextMarking -> use "next" marking information,
721 // _vo == UseMarkWord -> use mark word from object header.
722 VerifyLiveClosure(G1CollectedHeap* g1h, VerifyOption vo) :
723 _g1h(g1h), _bs(NULL), _containing_obj(NULL),
724 _failures(false), _n_failures(0), _vo(vo)
725 {
726 BarrierSet* bs = _g1h->barrier_set();
727 if (bs->is_a(BarrierSet::CardTableModRef))
728 _bs = (CardTableModRefBS*)bs;
729 }
731 void set_containing_obj(oop obj) {
732 _containing_obj = obj;
733 }
735 bool failures() { return _failures; }
736 int n_failures() { return _n_failures; }
738 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
739 virtual void do_oop( oop* p) { do_oop_work(p); }
741 void print_object(outputStream* out, oop obj) {
742 #ifdef PRODUCT
743 Klass* k = obj->klass();
744 const char* class_name = InstanceKlass::cast(k)->external_name();
745 out->print_cr("class name %s", class_name);
746 #else // PRODUCT
747 obj->print_on(out);
748 #endif // PRODUCT
749 }
751 template <class T>
752 void do_oop_work(T* p) {
753 assert(_containing_obj != NULL, "Precondition");
754 assert(!_g1h->is_obj_dead_cond(_containing_obj, _vo),
755 "Precondition");
756 T heap_oop = oopDesc::load_heap_oop(p);
757 if (!oopDesc::is_null(heap_oop)) {
758 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
759 bool failed = false;
760 if (!_g1h->is_in_closed_subset(obj) || _g1h->is_obj_dead_cond(obj, _vo)) {
761 MutexLockerEx x(ParGCRareEvent_lock,
762 Mutex::_no_safepoint_check_flag);
764 if (!_failures) {
765 gclog_or_tty->cr();
766 gclog_or_tty->print_cr("----------");
767 }
768 if (!_g1h->is_in_closed_subset(obj)) {
769 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
770 gclog_or_tty->print_cr("Field "PTR_FORMAT
771 " of live obj "PTR_FORMAT" in region "
772 "["PTR_FORMAT", "PTR_FORMAT")",
773 p, (void*) _containing_obj,
774 from->bottom(), from->end());
775 print_object(gclog_or_tty, _containing_obj);
776 gclog_or_tty->print_cr("points to obj "PTR_FORMAT" not in the heap",
777 (void*) obj);
778 } else {
779 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
780 HeapRegion* to = _g1h->heap_region_containing((HeapWord*)obj);
781 gclog_or_tty->print_cr("Field "PTR_FORMAT
782 " of live obj "PTR_FORMAT" in region "
783 "["PTR_FORMAT", "PTR_FORMAT")",
784 p, (void*) _containing_obj,
785 from->bottom(), from->end());
786 print_object(gclog_or_tty, _containing_obj);
787 gclog_or_tty->print_cr("points to dead obj "PTR_FORMAT" in region "
788 "["PTR_FORMAT", "PTR_FORMAT")",
789 (void*) obj, to->bottom(), to->end());
790 print_object(gclog_or_tty, obj);
791 }
792 gclog_or_tty->print_cr("----------");
793 gclog_or_tty->flush();
794 _failures = true;
795 failed = true;
796 _n_failures++;
797 }
799 if (!_g1h->full_collection() || G1VerifyRSetsDuringFullGC) {
800 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
801 HeapRegion* to = _g1h->heap_region_containing(obj);
802 if (from != NULL && to != NULL &&
803 from != to &&
804 !to->isHumongous()) {
805 jbyte cv_obj = *_bs->byte_for_const(_containing_obj);
806 jbyte cv_field = *_bs->byte_for_const(p);
807 const jbyte dirty = CardTableModRefBS::dirty_card_val();
809 bool is_bad = !(from->is_young()
810 || to->rem_set()->contains_reference(p)
811 || !G1HRRSFlushLogBuffersOnVerify && // buffers were not flushed
812 (_containing_obj->is_objArray() ?
813 cv_field == dirty
814 : cv_obj == dirty || cv_field == dirty));
815 if (is_bad) {
816 MutexLockerEx x(ParGCRareEvent_lock,
817 Mutex::_no_safepoint_check_flag);
819 if (!_failures) {
820 gclog_or_tty->cr();
821 gclog_or_tty->print_cr("----------");
822 }
823 gclog_or_tty->print_cr("Missing rem set entry:");
824 gclog_or_tty->print_cr("Field "PTR_FORMAT" "
825 "of obj "PTR_FORMAT", "
826 "in region "HR_FORMAT,
827 p, (void*) _containing_obj,
828 HR_FORMAT_PARAMS(from));
829 _containing_obj->print_on(gclog_or_tty);
830 gclog_or_tty->print_cr("points to obj "PTR_FORMAT" "
831 "in region "HR_FORMAT,
832 (void*) obj,
833 HR_FORMAT_PARAMS(to));
834 obj->print_on(gclog_or_tty);
835 gclog_or_tty->print_cr("Obj head CTE = %d, field CTE = %d.",
836 cv_obj, cv_field);
837 gclog_or_tty->print_cr("----------");
838 gclog_or_tty->flush();
839 _failures = true;
840 if (!failed) _n_failures++;
841 }
842 }
843 }
844 }
845 }
846 };
848 // This really ought to be commoned up into OffsetTableContigSpace somehow.
849 // We would need a mechanism to make that code skip dead objects.
851 void HeapRegion::verify(VerifyOption vo,
852 bool* failures) const {
853 G1CollectedHeap* g1 = G1CollectedHeap::heap();
854 *failures = false;
855 HeapWord* p = bottom();
856 HeapWord* prev_p = NULL;
857 VerifyLiveClosure vl_cl(g1, vo);
858 bool is_humongous = isHumongous();
859 bool do_bot_verify = !is_young();
860 size_t object_num = 0;
861 while (p < top()) {
862 oop obj = oop(p);
863 size_t obj_size = block_size(p);
864 object_num += 1;
866 if (is_humongous != g1->isHumongous(obj_size) &&
867 !g1->is_obj_dead(obj, this)) { // Dead objects may have bigger block_size since they span several objects.
868 gclog_or_tty->print_cr("obj "PTR_FORMAT" is of %shumongous size ("
869 SIZE_FORMAT" words) in a %shumongous region",
870 p, g1->isHumongous(obj_size) ? "" : "non-",
871 obj_size, is_humongous ? "" : "non-");
872 *failures = true;
873 return;
874 }
876 // If it returns false, verify_for_object() will output the
877 // appropriate message.
878 if (do_bot_verify &&
879 !g1->is_obj_dead(obj, this) &&
880 !_offsets.verify_for_object(p, obj_size)) {
881 *failures = true;
882 return;
883 }
885 if (!g1->is_obj_dead_cond(obj, this, vo)) {
886 if (obj->is_oop()) {
887 Klass* klass = obj->klass();
888 bool is_metaspace_object = Metaspace::contains(klass) ||
889 (vo == VerifyOption_G1UsePrevMarking &&
890 ClassLoaderDataGraph::unload_list_contains(klass));
891 if (!is_metaspace_object) {
892 gclog_or_tty->print_cr("klass "PTR_FORMAT" of object "PTR_FORMAT" "
893 "not metadata", klass, (void *)obj);
894 *failures = true;
895 return;
896 } else if (!klass->is_klass()) {
897 gclog_or_tty->print_cr("klass "PTR_FORMAT" of object "PTR_FORMAT" "
898 "not a klass", klass, (void *)obj);
899 *failures = true;
900 return;
901 } else {
902 vl_cl.set_containing_obj(obj);
903 obj->oop_iterate_no_header(&vl_cl);
904 if (vl_cl.failures()) {
905 *failures = true;
906 }
907 if (G1MaxVerifyFailures >= 0 &&
908 vl_cl.n_failures() >= G1MaxVerifyFailures) {
909 return;
910 }
911 }
912 } else {
913 gclog_or_tty->print_cr(PTR_FORMAT" no an oop", (void *)obj);
914 *failures = true;
915 return;
916 }
917 }
918 prev_p = p;
919 p += obj_size;
920 }
922 if (p != top()) {
923 gclog_or_tty->print_cr("end of last object "PTR_FORMAT" "
924 "does not match top "PTR_FORMAT, p, top());
925 *failures = true;
926 return;
927 }
929 HeapWord* the_end = end();
930 assert(p == top(), "it should still hold");
931 // Do some extra BOT consistency checking for addresses in the
932 // range [top, end). BOT look-ups in this range should yield
933 // top. No point in doing that if top == end (there's nothing there).
934 if (p < the_end) {
935 // Look up top
936 HeapWord* addr_1 = p;
937 HeapWord* b_start_1 = _offsets.block_start_const(addr_1);
938 if (b_start_1 != p) {
939 gclog_or_tty->print_cr("BOT look up for top: "PTR_FORMAT" "
940 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
941 addr_1, b_start_1, p);
942 *failures = true;
943 return;
944 }
946 // Look up top + 1
947 HeapWord* addr_2 = p + 1;
948 if (addr_2 < the_end) {
949 HeapWord* b_start_2 = _offsets.block_start_const(addr_2);
950 if (b_start_2 != p) {
951 gclog_or_tty->print_cr("BOT look up for top + 1: "PTR_FORMAT" "
952 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
953 addr_2, b_start_2, p);
954 *failures = true;
955 return;
956 }
957 }
959 // Look up an address between top and end
960 size_t diff = pointer_delta(the_end, p) / 2;
961 HeapWord* addr_3 = p + diff;
962 if (addr_3 < the_end) {
963 HeapWord* b_start_3 = _offsets.block_start_const(addr_3);
964 if (b_start_3 != p) {
965 gclog_or_tty->print_cr("BOT look up for top + diff: "PTR_FORMAT" "
966 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
967 addr_3, b_start_3, p);
968 *failures = true;
969 return;
970 }
971 }
973 // Loook up end - 1
974 HeapWord* addr_4 = the_end - 1;
975 HeapWord* b_start_4 = _offsets.block_start_const(addr_4);
976 if (b_start_4 != p) {
977 gclog_or_tty->print_cr("BOT look up for end - 1: "PTR_FORMAT" "
978 " yielded "PTR_FORMAT", expecting "PTR_FORMAT,
979 addr_4, b_start_4, p);
980 *failures = true;
981 return;
982 }
983 }
985 if (is_humongous && object_num > 1) {
986 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] is humongous "
987 "but has "SIZE_FORMAT", objects",
988 bottom(), end(), object_num);
989 *failures = true;
990 return;
991 }
993 verify_strong_code_roots(vo, failures);
994 }
996 void HeapRegion::verify() const {
997 bool dummy = false;
998 verify(VerifyOption_G1UsePrevMarking, /* failures */ &dummy);
999 }
1001 // G1OffsetTableContigSpace code; copied from space.cpp. Hope this can go
1002 // away eventually.
1004 void G1OffsetTableContigSpace::clear(bool mangle_space) {
1005 set_top(bottom());
1006 set_saved_mark_word(bottom());
1007 CompactibleSpace::clear(mangle_space);
1008 reset_bot();
1009 }
1011 void G1OffsetTableContigSpace::set_bottom(HeapWord* new_bottom) {
1012 Space::set_bottom(new_bottom);
1013 _offsets.set_bottom(new_bottom);
1014 }
1016 void G1OffsetTableContigSpace::set_end(HeapWord* new_end) {
1017 Space::set_end(new_end);
1018 _offsets.resize(new_end - bottom());
1019 }
1021 void G1OffsetTableContigSpace::print() const {
1022 print_short();
1023 gclog_or_tty->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", "
1024 INTPTR_FORMAT ", " INTPTR_FORMAT ")",
1025 bottom(), top(), _offsets.threshold(), end());
1026 }
1028 HeapWord* G1OffsetTableContigSpace::initialize_threshold() {
1029 return _offsets.initialize_threshold();
1030 }
1032 HeapWord* G1OffsetTableContigSpace::cross_threshold(HeapWord* start,
1033 HeapWord* end) {
1034 _offsets.alloc_block(start, end);
1035 return _offsets.threshold();
1036 }
1038 HeapWord* G1OffsetTableContigSpace::saved_mark_word() const {
1039 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1040 assert( _gc_time_stamp <= g1h->get_gc_time_stamp(), "invariant" );
1041 if (_gc_time_stamp < g1h->get_gc_time_stamp())
1042 return top();
1043 else
1044 return Space::saved_mark_word();
1045 }
1047 void G1OffsetTableContigSpace::record_top_and_timestamp() {
1048 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1049 unsigned curr_gc_time_stamp = g1h->get_gc_time_stamp();
1051 if (_gc_time_stamp < curr_gc_time_stamp) {
1052 // The order of these is important, as another thread might be
1053 // about to start scanning this region. If it does so after
1054 // set_saved_mark and before _gc_time_stamp = ..., then the latter
1055 // will be false, and it will pick up top() as the high water mark
1056 // of region. If it does so after _gc_time_stamp = ..., then it
1057 // will pick up the right saved_mark_word() as the high water mark
1058 // of the region. Either way, the behaviour will be correct.
1059 Space::set_saved_mark_word(top());
1060 OrderAccess::storestore();
1061 _gc_time_stamp = curr_gc_time_stamp;
1062 // No need to do another barrier to flush the writes above. If
1063 // this is called in parallel with other threads trying to
1064 // allocate into the region, the caller should call this while
1065 // holding a lock and when the lock is released the writes will be
1066 // flushed.
1067 }
1068 }
1070 void G1OffsetTableContigSpace::safe_object_iterate(ObjectClosure* blk) {
1071 object_iterate(blk);
1072 }
1074 void G1OffsetTableContigSpace::object_iterate(ObjectClosure* blk) {
1075 HeapWord* p = bottom();
1076 while (p < top()) {
1077 if (block_is_obj(p)) {
1078 blk->do_object(oop(p));
1079 }
1080 p += block_size(p);
1081 }
1082 }
1084 #define block_is_always_obj(q) true
1085 void G1OffsetTableContigSpace::prepare_for_compaction(CompactPoint* cp) {
1086 SCAN_AND_FORWARD(cp, top, block_is_always_obj, block_size);
1087 }
1088 #undef block_is_always_obj
1090 G1OffsetTableContigSpace::
1091 G1OffsetTableContigSpace(G1BlockOffsetSharedArray* sharedOffsetArray,
1092 MemRegion mr) :
1093 _offsets(sharedOffsetArray, mr),
1094 _par_alloc_lock(Mutex::leaf, "OffsetTableContigSpace par alloc lock", true),
1095 _gc_time_stamp(0)
1096 {
1097 _offsets.set_space(this);
1098 }
1100 void G1OffsetTableContigSpace::initialize(MemRegion mr, bool clear_space, bool mangle_space) {
1101 CompactibleSpace::initialize(mr, clear_space, mangle_space);
1102 _top = bottom();
1103 reset_bot();
1104 }