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 */ 24 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/heapRegionRemSet.hpp" 32 #include "gc_implementation/g1/heapRegionSeq.inline.hpp" 33 #include "gc_implementation/shared/liveRange.hpp" 34 #include "memory/genOopClosures.inline.hpp" 35 #include "memory/iterator.hpp" 36 #include "memory/space.inline.hpp" 37 #include "oops/oop.inline.hpp" 38 #include "runtime/orderAccess.inline.hpp" 39 40 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC 41 42 int HeapRegion::LogOfHRGrainBytes = 0; 43 int HeapRegion::LogOfHRGrainWords = 0; 44 size_t HeapRegion::GrainBytes = 0; 45 size_t HeapRegion::GrainWords = 0; 46 size_t HeapRegion::CardsPerRegion = 0; 47 48 HeapRegionDCTOC::HeapRegionDCTOC(G1CollectedHeap* g1, 49 HeapRegion* hr, ExtendedOopClosure* cl, 50 CardTableModRefBS::PrecisionStyle precision, 51 FilterKind fk) : 52 DirtyCardToOopClosure(hr, cl, precision, NULL), 53 _hr(hr), _fk(fk), _g1(g1) { } 54 55 FilterOutOfRegionClosure::FilterOutOfRegionClosure(HeapRegion* r, 56 OopClosure* oc) : 57 _r_bottom(r->bottom()), _r_end(r->end()), _oc(oc) { } 58 59 template<class ClosureType> 60 HeapWord* walk_mem_region_loop(ClosureType* cl, G1CollectedHeap* g1h, 61 HeapRegion* hr, 62 HeapWord* cur, HeapWord* top) { 63 oop cur_oop = oop(cur); 64 size_t oop_size = hr->block_size(cur); 65 HeapWord* next_obj = cur + oop_size; 66 while (next_obj < top) { 67 // Keep filtering the remembered set. 68 if (!g1h->is_obj_dead(cur_oop, hr)) { 69 // Bottom lies entirely below top, so we can call the 70 // non-memRegion version of oop_iterate below. 71 cur_oop->oop_iterate(cl); 72 } 73 cur = next_obj; 74 cur_oop = oop(cur); 75 oop_size = hr->block_size(cur); 76 next_obj = cur + oop_size; 77 } 78 return cur; 79 } 80 81 void HeapRegionDCTOC::walk_mem_region(MemRegion mr, 82 HeapWord* bottom, 83 HeapWord* top) { 84 G1CollectedHeap* g1h = _g1; 85 size_t oop_size; 86 ExtendedOopClosure* cl2 = NULL; 87 88 FilterIntoCSClosure intoCSFilt(this, g1h, _cl); 89 FilterOutOfRegionClosure outOfRegionFilt(_hr, _cl); 90 91 switch (_fk) { 92 case NoFilterKind: cl2 = _cl; break; 93 case IntoCSFilterKind: cl2 = &intoCSFilt; break; 94 case OutOfRegionFilterKind: cl2 = &outOfRegionFilt; break; 95 default: ShouldNotReachHere(); 96 } 97 98 // Start filtering what we add to the remembered set. If the object is 99 // not considered dead, either because it is marked (in the mark bitmap) 100 // or it was allocated after marking finished, then we add it. Otherwise 101 // we can safely ignore the object. 102 if (!g1h->is_obj_dead(oop(bottom), _hr)) { 103 oop_size = oop(bottom)->oop_iterate(cl2, mr); 104 } else { 105 oop_size = _hr->block_size(bottom); 106 } 107 108 bottom += oop_size; 109 110 if (bottom < top) { 111 // We replicate the loop below for several kinds of possible filters. 112 switch (_fk) { 113 case NoFilterKind: 114 bottom = walk_mem_region_loop(_cl, g1h, _hr, bottom, top); 115 break; 116 117 case IntoCSFilterKind: { 118 FilterIntoCSClosure filt(this, g1h, _cl); 119 bottom = walk_mem_region_loop(&filt, g1h, _hr, bottom, top); 120 break; 121 } 122 123 case OutOfRegionFilterKind: { 124 FilterOutOfRegionClosure filt(_hr, _cl); 125 bottom = walk_mem_region_loop(&filt, g1h, _hr, bottom, top); 126 break; 127 } 128 129 default: 130 ShouldNotReachHere(); 131 } 132 133 // Last object. Need to do dead-obj filtering here too. 134 if (!g1h->is_obj_dead(oop(bottom), _hr)) { 135 oop(bottom)->oop_iterate(cl2, mr); 136 } 137 } 138 } 139 140 // Minimum region size; we won't go lower than that. 141 // We might want to decrease this in the future, to deal with small 142 // heaps a bit more efficiently. 143 #define MIN_REGION_SIZE ( 1024 * 1024 ) 144 145 // Maximum region size; we don't go higher than that. There's a good 146 // reason for having an upper bound. We don't want regions to get too 147 // large, otherwise cleanup's effectiveness would decrease as there 148 // will be fewer opportunities to find totally empty regions after 149 // marking. 150 #define MAX_REGION_SIZE ( 32 * 1024 * 1024 ) 151 152 // The automatic region size calculation will try to have around this 153 // many regions in the heap (based on the min heap size). 154 #define TARGET_REGION_NUMBER 2048 155 156 size_t HeapRegion::max_region_size() { 157 return (size_t)MAX_REGION_SIZE; 158 } 159 160 void HeapRegion::setup_heap_region_size(size_t initial_heap_size, size_t max_heap_size) { 161 uintx region_size = G1HeapRegionSize; 162 if (FLAG_IS_DEFAULT(G1HeapRegionSize)) { 163 size_t average_heap_size = (initial_heap_size + max_heap_size) / 2; 164 region_size = MAX2(average_heap_size / TARGET_REGION_NUMBER, 165 (uintx) MIN_REGION_SIZE); 166 } 167 168 int region_size_log = log2_long((jlong) region_size); 169 // Recalculate the region size to make sure it's a power of 170 // 2. This means that region_size is the largest power of 2 that's 171 // <= what we've calculated so far. 172 region_size = ((uintx)1 << region_size_log); 173 174 // Now make sure that we don't go over or under our limits. 175 if (region_size < MIN_REGION_SIZE) { 176 region_size = MIN_REGION_SIZE; 177 } else if (region_size > MAX_REGION_SIZE) { 178 region_size = MAX_REGION_SIZE; 179 } 180 181 // And recalculate the log. 182 region_size_log = log2_long((jlong) region_size); 183 184 // Now, set up the globals. 185 guarantee(LogOfHRGrainBytes == 0, "we should only set it once"); 186 LogOfHRGrainBytes = region_size_log; 187 188 guarantee(LogOfHRGrainWords == 0, "we should only set it once"); 189 LogOfHRGrainWords = LogOfHRGrainBytes - LogHeapWordSize; 190 191 guarantee(GrainBytes == 0, "we should only set it once"); 192 // The cast to int is safe, given that we've bounded region_size by 193 // MIN_REGION_SIZE and MAX_REGION_SIZE. 194 GrainBytes = (size_t)region_size; 195 196 guarantee(GrainWords == 0, "we should only set it once"); 197 GrainWords = GrainBytes >> LogHeapWordSize; 198 guarantee((size_t) 1 << LogOfHRGrainWords == GrainWords, "sanity"); 199 200 guarantee(CardsPerRegion == 0, "we should only set it once"); 201 CardsPerRegion = GrainBytes >> CardTableModRefBS::card_shift; 202 } 203 204 void HeapRegion::reset_after_compaction() { 205 G1OffsetTableContigSpace::reset_after_compaction(); 206 // After a compaction the mark bitmap is invalid, so we must 207 // treat all objects as being inside the unmarked area. 208 zero_marked_bytes(); 209 init_top_at_mark_start(); 210 } 211 212 void HeapRegion::hr_clear(bool par, bool clear_space, bool locked) { 213 assert(_humongous_type == NotHumongous, 214 "we should have already filtered out humongous regions"); 215 assert(_humongous_start_region == NULL, 216 "we should have already filtered out humongous regions"); 217 assert(_end == _orig_end, 218 "we should have already filtered out humongous regions"); 219 220 _in_collection_set = false; 221 222 set_young_index_in_cset(-1); 223 uninstall_surv_rate_group(); 224 set_young_type(NotYoung); 225 reset_pre_dummy_top(); 226 227 if (!par) { 228 // If this is parallel, this will be done later. 229 HeapRegionRemSet* hrrs = rem_set(); 230 if (locked) { 231 hrrs->clear_locked(); 232 } else { 233 hrrs->clear(); 234 } 235 _claimed = InitialClaimValue; 236 } 237 zero_marked_bytes(); 238 239 _offsets.resize(HeapRegion::GrainWords); 240 init_top_at_mark_start(); 241 if (clear_space) clear(SpaceDecorator::Mangle); 242 } 243 244 void HeapRegion::par_clear() { 245 assert(used() == 0, "the region should have been already cleared"); 246 assert(capacity() == HeapRegion::GrainBytes, "should be back to normal"); 247 HeapRegionRemSet* hrrs = rem_set(); 248 hrrs->clear(); 249 CardTableModRefBS* ct_bs = 250 (CardTableModRefBS*)G1CollectedHeap::heap()->barrier_set(); 251 ct_bs->clear(MemRegion(bottom(), end())); 252 } 253 254 void HeapRegion::calc_gc_efficiency() { 255 // GC efficiency is the ratio of how much space would be 256 // reclaimed over how long we predict it would take to reclaim it. 257 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 258 G1CollectorPolicy* g1p = g1h->g1_policy(); 259 260 // Retrieve a prediction of the elapsed time for this region for 261 // a mixed gc because the region will only be evacuated during a 262 // mixed gc. 263 double region_elapsed_time_ms = 264 g1p->predict_region_elapsed_time_ms(this, false /* for_young_gc */); 265 _gc_efficiency = (double) reclaimable_bytes() / region_elapsed_time_ms; 266 } 267 268 void HeapRegion::set_startsHumongous(HeapWord* new_top, HeapWord* new_end) { 269 assert(!isHumongous(), "sanity / pre-condition"); 270 assert(end() == _orig_end, 271 "Should be normal before the humongous object allocation"); 272 assert(top() == bottom(), "should be empty"); 273 assert(bottom() <= new_top && new_top <= new_end, "pre-condition"); 274 275 _humongous_type = StartsHumongous; 276 _humongous_start_region = this; 277 278 set_end(new_end); 279 _offsets.set_for_starts_humongous(new_top); 280 } 281 282 void HeapRegion::set_continuesHumongous(HeapRegion* first_hr) { 283 assert(!isHumongous(), "sanity / pre-condition"); 284 assert(end() == _orig_end, 285 "Should be normal before the humongous object allocation"); 286 assert(top() == bottom(), "should be empty"); 287 assert(first_hr->startsHumongous(), "pre-condition"); 288 289 _humongous_type = ContinuesHumongous; 290 _humongous_start_region = first_hr; 291 } 292 293 void HeapRegion::set_notHumongous() { 294 assert(isHumongous(), "pre-condition"); 295 296 if (startsHumongous()) { 297 assert(top() <= end(), "pre-condition"); 298 set_end(_orig_end); 299 if (top() > end()) { 300 // at least one "continues humongous" region after it 301 set_top(end()); 302 } 303 } else { 304 // continues humongous 305 assert(end() == _orig_end, "sanity"); 306 } 307 308 assert(capacity() == HeapRegion::GrainBytes, "pre-condition"); 309 _humongous_type = NotHumongous; 310 _humongous_start_region = NULL; 311 } 312 313 bool HeapRegion::claimHeapRegion(jint claimValue) { 314 jint current = _claimed; 315 if (current != claimValue) { 316 jint res = Atomic::cmpxchg(claimValue, &_claimed, current); 317 if (res == current) { 318 return true; 319 } 320 } 321 return false; 322 } 323 324 HeapWord* HeapRegion::next_block_start_careful(HeapWord* addr) { 325 HeapWord* low = addr; 326 HeapWord* high = end(); 327 while (low < high) { 328 size_t diff = pointer_delta(high, low); 329 // Must add one below to bias toward the high amount. Otherwise, if 330 // "high" were at the desired value, and "low" were one less, we 331 // would not converge on "high". This is not symmetric, because 332 // we set "high" to a block start, which might be the right one, 333 // which we don't do for "low". 334 HeapWord* middle = low + (diff+1)/2; 335 if (middle == high) return high; 336 HeapWord* mid_bs = block_start_careful(middle); 337 if (mid_bs < addr) { 338 low = middle; 339 } else { 340 high = mid_bs; 341 } 342 } 343 assert(low == high && low >= addr, "Didn't work."); 344 return low; 345 } 346 347 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away 348 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list 349 #endif // _MSC_VER 350 351 352 HeapRegion::HeapRegion(uint hrs_index, 353 G1BlockOffsetSharedArray* sharedOffsetArray, 354 MemRegion mr) : 355 G1OffsetTableContigSpace(sharedOffsetArray, mr), 356 _hrs_index(hrs_index), 357 _humongous_type(NotHumongous), _humongous_start_region(NULL), 358 _in_collection_set(false), 359 _next_in_special_set(NULL), _orig_end(NULL), 360 _claimed(InitialClaimValue), _evacuation_failed(false), 361 _prev_marked_bytes(0), _next_marked_bytes(0), _gc_efficiency(0.0), 362 _young_type(NotYoung), _next_young_region(NULL), 363 _next_dirty_cards_region(NULL), _next(NULL), _prev(NULL), _pending_removal(false), 364 #ifdef ASSERT 365 _containing_set(NULL), 366 #endif // ASSERT 367 _young_index_in_cset(-1), _surv_rate_group(NULL), _age_index(-1), 368 _rem_set(NULL), _recorded_rs_length(0), _predicted_elapsed_time_ms(0), 369 _predicted_bytes_to_copy(0) 370 { 371 _rem_set = new HeapRegionRemSet(sharedOffsetArray, this); 372 _orig_end = mr.end(); 373 // Note that initialize() will set the start of the unmarked area of the 374 // region. 375 hr_clear(false /*par*/, false /*clear_space*/); 376 set_top(bottom()); 377 record_top_and_timestamp(); 378 379 assert(HeapRegionRemSet::num_par_rem_sets() > 0, "Invariant."); 380 } 381 382 CompactibleSpace* HeapRegion::next_compaction_space() const { 383 // We're not using an iterator given that it will wrap around when 384 // it reaches the last region and this is not what we want here. 385 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 386 uint index = hrs_index() + 1; 387 while (index < g1h->n_regions()) { 388 HeapRegion* hr = g1h->region_at(index); 389 if (!hr->isHumongous()) { 390 return hr; 391 } 392 index += 1; 393 } 394 return NULL; 395 } 396 397 void HeapRegion::oops_in_mr_iterate(MemRegion mr, ExtendedOopClosure* cl) { 398 HeapWord* p = mr.start(); 399 HeapWord* e = mr.end(); 400 oop obj; 401 while (p < e) { 402 obj = oop(p); 403 p += obj->oop_iterate(cl); 404 } 405 assert(p == e, "bad memregion: doesn't end on obj boundary"); 406 } 407 408 void HeapRegion::note_self_forwarding_removal_start(bool during_initial_mark, 409 bool during_conc_mark) { 410 // We always recreate the prev marking info and we'll explicitly 411 // mark all objects we find to be self-forwarded on the prev 412 // bitmap. So all objects need to be below PTAMS. 413 _prev_top_at_mark_start = top(); 414 _prev_marked_bytes = 0; 415 416 if (during_initial_mark) { 417 // During initial-mark, we'll also explicitly mark all objects 418 // we find to be self-forwarded on the next bitmap. So all 419 // objects need to be below NTAMS. 420 _next_top_at_mark_start = top(); 421 _next_marked_bytes = 0; 422 } else if (during_conc_mark) { 423 // During concurrent mark, all objects in the CSet (including 424 // the ones we find to be self-forwarded) are implicitly live. 425 // So all objects need to be above NTAMS. 426 _next_top_at_mark_start = bottom(); 427 _next_marked_bytes = 0; 428 } 429 } 430 431 void HeapRegion::note_self_forwarding_removal_end(bool during_initial_mark, 432 bool during_conc_mark, 433 size_t marked_bytes) { 434 assert(0 <= marked_bytes && marked_bytes <= used(), 435 err_msg("marked: "SIZE_FORMAT" used: "SIZE_FORMAT, 436 marked_bytes, used())); 437 _prev_marked_bytes = marked_bytes; 438 } 439 440 HeapWord* 441 HeapRegion::object_iterate_mem_careful(MemRegion mr, 442 ObjectClosure* cl) { 443 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 444 // We used to use "block_start_careful" here. But we're actually happy 445 // to update the BOT while we do this... 446 HeapWord* cur = block_start(mr.start()); 447 mr = mr.intersection(used_region()); 448 if (mr.is_empty()) return NULL; 449 // Otherwise, find the obj that extends onto mr.start(). 450 451 assert(cur <= mr.start() 452 && (oop(cur)->klass_or_null() == NULL || 453 cur + oop(cur)->size() > mr.start()), 454 "postcondition of block_start"); 455 oop obj; 456 while (cur < mr.end()) { 457 obj = oop(cur); 458 if (obj->klass_or_null() == NULL) { 459 // Ran into an unparseable point. 460 return cur; 461 } else if (!g1h->is_obj_dead(obj)) { 462 cl->do_object(obj); 463 } 464 cur += block_size(cur); 465 } 466 return NULL; 467 } 468 469 HeapWord* 470 HeapRegion:: 471 oops_on_card_seq_iterate_careful(MemRegion mr, 472 FilterOutOfRegionClosure* cl, 473 bool filter_young, 474 jbyte* card_ptr) { 475 // Currently, we should only have to clean the card if filter_young 476 // is true and vice versa. 477 if (filter_young) { 478 assert(card_ptr != NULL, "pre-condition"); 479 } else { 480 assert(card_ptr == NULL, "pre-condition"); 481 } 482 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 483 484 // If we're within a stop-world GC, then we might look at a card in a 485 // GC alloc region that extends onto a GC LAB, which may not be 486 // parseable. Stop such at the "saved_mark" of the region. 487 if (g1h->is_gc_active()) { 488 mr = mr.intersection(used_region_at_save_marks()); 489 } else { 490 mr = mr.intersection(used_region()); 491 } 492 if (mr.is_empty()) return NULL; 493 // Otherwise, find the obj that extends onto mr.start(). 494 495 // The intersection of the incoming mr (for the card) and the 496 // allocated part of the region is non-empty. This implies that 497 // we have actually allocated into this region. The code in 498 // G1CollectedHeap.cpp that allocates a new region sets the 499 // is_young tag on the region before allocating. Thus we 500 // safely know if this region is young. 501 if (is_young() && filter_young) { 502 return NULL; 503 } 504 505 assert(!is_young(), "check value of filter_young"); 506 507 // We can only clean the card here, after we make the decision that 508 // the card is not young. And we only clean the card if we have been 509 // asked to (i.e., card_ptr != NULL). 510 if (card_ptr != NULL) { 511 *card_ptr = CardTableModRefBS::clean_card_val(); 512 // We must complete this write before we do any of the reads below. 513 OrderAccess::storeload(); 514 } 515 516 // Cache the boundaries of the memory region in some const locals 517 HeapWord* const start = mr.start(); 518 HeapWord* const end = mr.end(); 519 520 // We used to use "block_start_careful" here. But we're actually happy 521 // to update the BOT while we do this... 522 HeapWord* cur = block_start(start); 523 assert(cur <= start, "Postcondition"); 524 525 oop obj; 526 527 HeapWord* next = cur; 528 while (next <= start) { 529 cur = next; 530 obj = oop(cur); 531 if (obj->klass_or_null() == NULL) { 532 // Ran into an unparseable point. 533 return cur; 534 } 535 // Otherwise... 536 next = cur + block_size(cur); 537 } 538 539 // If we finish the above loop...We have a parseable object that 540 // begins on or before the start of the memory region, and ends 541 // inside or spans the entire region. 542 543 assert(obj == oop(cur), "sanity"); 544 assert(cur <= start, "Loop postcondition"); 545 assert(obj->klass_or_null() != NULL, "Loop postcondition"); 546 assert((cur + block_size(cur)) > start, "Loop postcondition"); 547 548 if (!g1h->is_obj_dead(obj)) { 549 obj->oop_iterate(cl, mr); 550 } 551 552 while (cur < end) { 553 obj = oop(cur); 554 if (obj->klass_or_null() == NULL) { 555 // Ran into an unparseable point. 556 return cur; 557 }; 558 559 // Otherwise: 560 next = cur + block_size(cur); 561 562 if (!g1h->is_obj_dead(obj)) { 563 if (next < end || !obj->is_objArray()) { 564 // This object either does not span the MemRegion 565 // boundary, or if it does it's not an array. 566 // Apply closure to whole object. 567 obj->oop_iterate(cl); 568 } else { 569 // This obj is an array that spans the boundary. 570 // Stop at the boundary. 571 obj->oop_iterate(cl, mr); 572 } 573 } 574 cur = next; 575 } 576 return NULL; 577 } 578 579 // Code roots support 580 581 void HeapRegion::add_strong_code_root(nmethod* nm) { 582 HeapRegionRemSet* hrrs = rem_set(); 583 hrrs->add_strong_code_root(nm); 584 } 585 586 void HeapRegion::remove_strong_code_root(nmethod* nm) { 587 HeapRegionRemSet* hrrs = rem_set(); 588 hrrs->remove_strong_code_root(nm); 589 } 590 591 void HeapRegion::migrate_strong_code_roots() { 592 assert(in_collection_set(), "only collection set regions"); 593 assert(!isHumongous(), 594 err_msg("humongous region "HR_FORMAT" should not have been added to collection set", 595 HR_FORMAT_PARAMS(this))); 596 597 HeapRegionRemSet* hrrs = rem_set(); 598 hrrs->migrate_strong_code_roots(); 599 } 600 601 void HeapRegion::strong_code_roots_do(CodeBlobClosure* blk) const { 602 HeapRegionRemSet* hrrs = rem_set(); 603 hrrs->strong_code_roots_do(blk); 604 } 605 606 class VerifyStrongCodeRootOopClosure: public OopClosure { 607 const HeapRegion* _hr; 608 nmethod* _nm; 609 bool _failures; 610 bool _has_oops_in_region; 611 612 template <class T> void do_oop_work(T* p) { 613 T heap_oop = oopDesc::load_heap_oop(p); 614 if (!oopDesc::is_null(heap_oop)) { 615 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 616 617 // Note: not all the oops embedded in the nmethod are in the 618 // current region. We only look at those which are. 619 if (_hr->is_in(obj)) { 620 // Object is in the region. Check that its less than top 621 if (_hr->top() <= (HeapWord*)obj) { 622 // Object is above top 623 gclog_or_tty->print_cr("Object "PTR_FORMAT" in region " 624 "["PTR_FORMAT", "PTR_FORMAT") is above " 625 "top "PTR_FORMAT, 626 (void *)obj, _hr->bottom(), _hr->end(), _hr->top()); 627 _failures = true; 628 return; 629 } 630 // Nmethod has at least one oop in the current region 631 _has_oops_in_region = true; 632 } 633 } 634 } 635 636 public: 637 VerifyStrongCodeRootOopClosure(const HeapRegion* hr, nmethod* nm): 638 _hr(hr), _failures(false), _has_oops_in_region(false) {} 639 640 void do_oop(narrowOop* p) { do_oop_work(p); } 641 void do_oop(oop* p) { do_oop_work(p); } 642 643 bool failures() { return _failures; } 644 bool has_oops_in_region() { return _has_oops_in_region; } 645 }; 646 647 class VerifyStrongCodeRootCodeBlobClosure: public CodeBlobClosure { 648 const HeapRegion* _hr; 649 bool _failures; 650 public: 651 VerifyStrongCodeRootCodeBlobClosure(const HeapRegion* hr) : 652 _hr(hr), _failures(false) {} 653 654 void do_code_blob(CodeBlob* cb) { 655 nmethod* nm = (cb == NULL) ? NULL : cb->as_nmethod_or_null(); 656 if (nm != NULL) { 657 // Verify that the nemthod is live 658 if (!nm->is_alive()) { 659 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] has dead nmethod " 660 PTR_FORMAT" in its strong code roots", 661 _hr->bottom(), _hr->end(), nm); 662 _failures = true; 663 } else { 664 VerifyStrongCodeRootOopClosure oop_cl(_hr, nm); 665 nm->oops_do(&oop_cl); 666 if (!oop_cl.has_oops_in_region()) { 667 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] has nmethod " 668 PTR_FORMAT" in its strong code roots " 669 "with no pointers into region", 670 _hr->bottom(), _hr->end(), nm); 671 _failures = true; 672 } else if (oop_cl.failures()) { 673 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] has other " 674 "failures for nmethod "PTR_FORMAT, 675 _hr->bottom(), _hr->end(), nm); 676 _failures = true; 677 } 678 } 679 } 680 } 681 682 bool failures() { return _failures; } 683 }; 684 685 void HeapRegion::verify_strong_code_roots(VerifyOption vo, bool* failures) const { 686 if (!G1VerifyHeapRegionCodeRoots) { 687 // We're not verifying code roots. 688 return; 689 } 690 if (vo == VerifyOption_G1UseMarkWord) { 691 // Marking verification during a full GC is performed after class 692 // unloading, code cache unloading, etc so the strong code roots 693 // attached to each heap region are in an inconsistent state. They won't 694 // be consistent until the strong code roots are rebuilt after the 695 // actual GC. Skip verifying the strong code roots in this particular 696 // time. 697 assert(VerifyDuringGC, "only way to get here"); 698 return; 699 } 700 701 HeapRegionRemSet* hrrs = rem_set(); 702 size_t strong_code_roots_length = hrrs->strong_code_roots_list_length(); 703 704 // if this region is empty then there should be no entries 705 // on its strong code root list 706 if (is_empty()) { 707 if (strong_code_roots_length > 0) { 708 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] is empty " 709 "but has "SIZE_FORMAT" code root entries", 710 bottom(), end(), strong_code_roots_length); 711 *failures = true; 712 } 713 return; 714 } 715 716 if (continuesHumongous()) { 717 if (strong_code_roots_length > 0) { 718 gclog_or_tty->print_cr("region "HR_FORMAT" is a continuation of a humongous " 719 "region but has "SIZE_FORMAT" code root entries", 720 HR_FORMAT_PARAMS(this), strong_code_roots_length); 721 *failures = true; 722 } 723 return; 724 } 725 726 VerifyStrongCodeRootCodeBlobClosure cb_cl(this); 727 strong_code_roots_do(&cb_cl); 728 729 if (cb_cl.failures()) { 730 *failures = true; 731 } 732 } 733 734 void HeapRegion::print() const { print_on(gclog_or_tty); } 735 void HeapRegion::print_on(outputStream* st) const { 736 if (isHumongous()) { 737 if (startsHumongous()) 738 st->print(" HS"); 739 else 740 st->print(" HC"); 741 } else { 742 st->print(" "); 743 } 744 if (in_collection_set()) 745 st->print(" CS"); 746 else 747 st->print(" "); 748 if (is_young()) 749 st->print(is_survivor() ? " SU" : " Y "); 750 else 751 st->print(" "); 752 if (is_empty()) 753 st->print(" F"); 754 else 755 st->print(" "); 756 st->print(" TS %5d", _gc_time_stamp); 757 st->print(" PTAMS "PTR_FORMAT" NTAMS "PTR_FORMAT, 758 prev_top_at_mark_start(), next_top_at_mark_start()); 759 G1OffsetTableContigSpace::print_on(st); 760 } 761 762 class VerifyLiveClosure: public OopClosure { 763 private: 764 G1CollectedHeap* _g1h; 765 CardTableModRefBS* _bs; 766 oop _containing_obj; 767 bool _failures; 768 int _n_failures; 769 VerifyOption _vo; 770 public: 771 // _vo == UsePrevMarking -> use "prev" marking information, 772 // _vo == UseNextMarking -> use "next" marking information, 773 // _vo == UseMarkWord -> use mark word from object header. 774 VerifyLiveClosure(G1CollectedHeap* g1h, VerifyOption vo) : 775 _g1h(g1h), _bs(NULL), _containing_obj(NULL), 776 _failures(false), _n_failures(0), _vo(vo) 777 { 778 BarrierSet* bs = _g1h->barrier_set(); 779 if (bs->is_a(BarrierSet::CardTableModRef)) 780 _bs = (CardTableModRefBS*)bs; 781 } 782 783 void set_containing_obj(oop obj) { 784 _containing_obj = obj; 785 } 786 787 bool failures() { return _failures; } 788 int n_failures() { return _n_failures; } 789 790 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 791 virtual void do_oop( oop* p) { do_oop_work(p); } 792 793 void print_object(outputStream* out, oop obj) { 794 #ifdef PRODUCT 795 Klass* k = obj->klass(); 796 const char* class_name = InstanceKlass::cast(k)->external_name(); 797 out->print_cr("class name %s", class_name); 798 #else // PRODUCT 799 obj->print_on(out); 800 #endif // PRODUCT 801 } 802 803 template <class T> 804 void do_oop_work(T* p) { 805 assert(_containing_obj != NULL, "Precondition"); 806 assert(!_g1h->is_obj_dead_cond(_containing_obj, _vo), 807 "Precondition"); 808 T heap_oop = oopDesc::load_heap_oop(p); 809 if (!oopDesc::is_null(heap_oop)) { 810 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 811 bool failed = false; 812 if (!_g1h->is_in_closed_subset(obj) || _g1h->is_obj_dead_cond(obj, _vo)) { 813 MutexLockerEx x(ParGCRareEvent_lock, 814 Mutex::_no_safepoint_check_flag); 815 816 if (!_failures) { 817 gclog_or_tty->cr(); 818 gclog_or_tty->print_cr("----------"); 819 } 820 if (!_g1h->is_in_closed_subset(obj)) { 821 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p); 822 gclog_or_tty->print_cr("Field "PTR_FORMAT 823 " of live obj "PTR_FORMAT" in region " 824 "["PTR_FORMAT", "PTR_FORMAT")", 825 p, (void*) _containing_obj, 826 from->bottom(), from->end()); 827 print_object(gclog_or_tty, _containing_obj); 828 gclog_or_tty->print_cr("points to obj "PTR_FORMAT" not in the heap", 829 (void*) obj); 830 } else { 831 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p); 832 HeapRegion* to = _g1h->heap_region_containing((HeapWord*)obj); 833 gclog_or_tty->print_cr("Field "PTR_FORMAT 834 " of live obj "PTR_FORMAT" in region " 835 "["PTR_FORMAT", "PTR_FORMAT")", 836 p, (void*) _containing_obj, 837 from->bottom(), from->end()); 838 print_object(gclog_or_tty, _containing_obj); 839 gclog_or_tty->print_cr("points to dead obj "PTR_FORMAT" in region " 840 "["PTR_FORMAT", "PTR_FORMAT")", 841 (void*) obj, to->bottom(), to->end()); 842 print_object(gclog_or_tty, obj); 843 } 844 gclog_or_tty->print_cr("----------"); 845 gclog_or_tty->flush(); 846 _failures = true; 847 failed = true; 848 _n_failures++; 849 } 850 851 if (!_g1h->full_collection() || G1VerifyRSetsDuringFullGC) { 852 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p); 853 HeapRegion* to = _g1h->heap_region_containing(obj); 854 if (from != NULL && to != NULL && 855 from != to && 856 !to->isHumongous()) { 857 jbyte cv_obj = *_bs->byte_for_const(_containing_obj); 858 jbyte cv_field = *_bs->byte_for_const(p); 859 const jbyte dirty = CardTableModRefBS::dirty_card_val(); 860 861 bool is_bad = !(from->is_young() 862 || to->rem_set()->contains_reference(p) 863 || !G1HRRSFlushLogBuffersOnVerify && // buffers were not flushed 864 (_containing_obj->is_objArray() ? 865 cv_field == dirty 866 : cv_obj == dirty || cv_field == dirty)); 867 if (is_bad) { 868 MutexLockerEx x(ParGCRareEvent_lock, 869 Mutex::_no_safepoint_check_flag); 870 871 if (!_failures) { 872 gclog_or_tty->cr(); 873 gclog_or_tty->print_cr("----------"); 874 } 875 gclog_or_tty->print_cr("Missing rem set entry:"); 876 gclog_or_tty->print_cr("Field "PTR_FORMAT" " 877 "of obj "PTR_FORMAT", " 878 "in region "HR_FORMAT, 879 p, (void*) _containing_obj, 880 HR_FORMAT_PARAMS(from)); 881 _containing_obj->print_on(gclog_or_tty); 882 gclog_or_tty->print_cr("points to obj "PTR_FORMAT" " 883 "in region "HR_FORMAT, 884 (void*) obj, 885 HR_FORMAT_PARAMS(to)); 886 obj->print_on(gclog_or_tty); 887 gclog_or_tty->print_cr("Obj head CTE = %d, field CTE = %d.", 888 cv_obj, cv_field); 889 gclog_or_tty->print_cr("----------"); 890 gclog_or_tty->flush(); 891 _failures = true; 892 if (!failed) _n_failures++; 893 } 894 } 895 } 896 } 897 } 898 }; 899 900 // This really ought to be commoned up into OffsetTableContigSpace somehow. 901 // We would need a mechanism to make that code skip dead objects. 902 903 void HeapRegion::verify(VerifyOption vo, 904 bool* failures) const { 905 G1CollectedHeap* g1 = G1CollectedHeap::heap(); 906 *failures = false; 907 HeapWord* p = bottom(); 908 HeapWord* prev_p = NULL; 909 VerifyLiveClosure vl_cl(g1, vo); 910 bool is_humongous = isHumongous(); 911 bool do_bot_verify = !is_young(); 912 size_t object_num = 0; 913 while (p < top()) { 914 oop obj = oop(p); 915 size_t obj_size = block_size(p); 916 object_num += 1; 917 918 if (is_humongous != g1->isHumongous(obj_size)) { 919 gclog_or_tty->print_cr("obj "PTR_FORMAT" is of %shumongous size (" 920 SIZE_FORMAT" words) in a %shumongous region", 921 p, g1->isHumongous(obj_size) ? "" : "non-", 922 obj_size, is_humongous ? "" : "non-"); 923 *failures = true; 924 return; 925 } 926 927 // If it returns false, verify_for_object() will output the 928 // appropriate messasge. 929 if (do_bot_verify && !_offsets.verify_for_object(p, obj_size)) { 930 *failures = true; 931 return; 932 } 933 934 if (!g1->is_obj_dead_cond(obj, this, vo)) { 935 if (obj->is_oop()) { 936 Klass* klass = obj->klass(); 937 if (!klass->is_metaspace_object()) { 938 gclog_or_tty->print_cr("klass "PTR_FORMAT" of object "PTR_FORMAT" " 939 "not metadata", klass, (void *)obj); 940 *failures = true; 941 return; 942 } else if (!klass->is_klass()) { 943 gclog_or_tty->print_cr("klass "PTR_FORMAT" of object "PTR_FORMAT" " 944 "not a klass", klass, (void *)obj); 945 *failures = true; 946 return; 947 } else { 948 vl_cl.set_containing_obj(obj); 949 obj->oop_iterate_no_header(&vl_cl); 950 if (vl_cl.failures()) { 951 *failures = true; 952 } 953 if (G1MaxVerifyFailures >= 0 && 954 vl_cl.n_failures() >= G1MaxVerifyFailures) { 955 return; 956 } 957 } 958 } else { 959 gclog_or_tty->print_cr(PTR_FORMAT" no an oop", (void *)obj); 960 *failures = true; 961 return; 962 } 963 } 964 prev_p = p; 965 p += obj_size; 966 } 967 968 if (p != top()) { 969 gclog_or_tty->print_cr("end of last object "PTR_FORMAT" " 970 "does not match top "PTR_FORMAT, p, top()); 971 *failures = true; 972 return; 973 } 974 975 HeapWord* the_end = end(); 976 assert(p == top(), "it should still hold"); 977 // Do some extra BOT consistency checking for addresses in the 978 // range [top, end). BOT look-ups in this range should yield 979 // top. No point in doing that if top == end (there's nothing there). 980 if (p < the_end) { 981 // Look up top 982 HeapWord* addr_1 = p; 983 HeapWord* b_start_1 = _offsets.block_start_const(addr_1); 984 if (b_start_1 != p) { 985 gclog_or_tty->print_cr("BOT look up for top: "PTR_FORMAT" " 986 " yielded "PTR_FORMAT", expecting "PTR_FORMAT, 987 addr_1, b_start_1, p); 988 *failures = true; 989 return; 990 } 991 992 // Look up top + 1 993 HeapWord* addr_2 = p + 1; 994 if (addr_2 < the_end) { 995 HeapWord* b_start_2 = _offsets.block_start_const(addr_2); 996 if (b_start_2 != p) { 997 gclog_or_tty->print_cr("BOT look up for top + 1: "PTR_FORMAT" " 998 " yielded "PTR_FORMAT", expecting "PTR_FORMAT, 999 addr_2, b_start_2, p); 1000 *failures = true; 1001 return; 1002 } 1003 } 1004 1005 // Look up an address between top and end 1006 size_t diff = pointer_delta(the_end, p) / 2; 1007 HeapWord* addr_3 = p + diff; 1008 if (addr_3 < the_end) { 1009 HeapWord* b_start_3 = _offsets.block_start_const(addr_3); 1010 if (b_start_3 != p) { 1011 gclog_or_tty->print_cr("BOT look up for top + diff: "PTR_FORMAT" " 1012 " yielded "PTR_FORMAT", expecting "PTR_FORMAT, 1013 addr_3, b_start_3, p); 1014 *failures = true; 1015 return; 1016 } 1017 } 1018 1019 // Look up end - 1 1020 HeapWord* addr_4 = the_end - 1; 1021 HeapWord* b_start_4 = _offsets.block_start_const(addr_4); 1022 if (b_start_4 != p) { 1023 gclog_or_tty->print_cr("BOT look up for end - 1: "PTR_FORMAT" " 1024 " yielded "PTR_FORMAT", expecting "PTR_FORMAT, 1025 addr_4, b_start_4, p); 1026 *failures = true; 1027 return; 1028 } 1029 } 1030 1031 if (is_humongous && object_num > 1) { 1032 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] is humongous " 1033 "but has "SIZE_FORMAT", objects", 1034 bottom(), end(), object_num); 1035 *failures = true; 1036 return; 1037 } 1038 1039 verify_strong_code_roots(vo, failures); 1040 } 1041 1042 void HeapRegion::verify() const { 1043 bool dummy = false; 1044 verify(VerifyOption_G1UsePrevMarking, /* failures */ &dummy); 1045 } 1046 1047 // G1OffsetTableContigSpace code; copied from space.cpp. Hope this can go 1048 // away eventually. 1049 1050 void G1OffsetTableContigSpace::clear(bool mangle_space) { 1051 set_top(bottom()); 1052 CompactibleSpace::clear(mangle_space); 1053 _offsets.zero_bottom_entry(); 1054 _offsets.initialize_threshold(); 1055 } 1056 1057 void G1OffsetTableContigSpace::set_bottom(HeapWord* new_bottom) { 1058 Space::set_bottom(new_bottom); 1059 _offsets.set_bottom(new_bottom); 1060 } 1061 1062 void G1OffsetTableContigSpace::set_end(HeapWord* new_end) { 1063 Space::set_end(new_end); 1064 _offsets.resize(new_end - bottom()); 1065 } 1066 1067 void G1OffsetTableContigSpace::print() const { 1068 print_short(); 1069 gclog_or_tty->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " 1070 INTPTR_FORMAT ", " INTPTR_FORMAT ")", 1071 bottom(), top(), _offsets.threshold(), end()); 1072 } 1073 1074 HeapWord* G1OffsetTableContigSpace::initialize_threshold() { 1075 return _offsets.initialize_threshold(); 1076 } 1077 1078 HeapWord* G1OffsetTableContigSpace::cross_threshold(HeapWord* start, 1079 HeapWord* end) { 1080 _offsets.alloc_block(start, end); 1081 return _offsets.threshold(); 1082 } 1083 1084 HeapWord* G1OffsetTableContigSpace::saved_mark_word() const { 1085 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 1086 assert( _gc_time_stamp <= g1h->get_gc_time_stamp(), "invariant" ); 1087 if (_gc_time_stamp < g1h->get_gc_time_stamp()) 1088 return top(); 1089 else 1090 return Space::saved_mark_word(); 1091 } 1092 1093 void G1OffsetTableContigSpace::record_top_and_timestamp() { 1094 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 1095 unsigned curr_gc_time_stamp = g1h->get_gc_time_stamp(); 1096 1097 if (_gc_time_stamp < curr_gc_time_stamp) { 1098 // The order of these is important, as another thread might be 1099 // about to start scanning this region. If it does so after 1100 // set_saved_mark and before _gc_time_stamp = ..., then the latter 1101 // will be false, and it will pick up top() as the high water mark 1102 // of region. If it does so after _gc_time_stamp = ..., then it 1103 // will pick up the right saved_mark_word() as the high water mark 1104 // of the region. Either way, the behavior will be correct. 1105 Space::set_saved_mark_word(top()); 1106 OrderAccess::storestore(); 1107 _gc_time_stamp = curr_gc_time_stamp; 1108 // No need to do another barrier to flush the writes above. If 1109 // this is called in parallel with other threads trying to 1110 // allocate into the region, the caller should call this while 1111 // holding a lock and when the lock is released the writes will be 1112 // flushed. 1113 } 1114 } 1115 1116 void G1OffsetTableContigSpace::safe_object_iterate(ObjectClosure* blk) { 1117 object_iterate(blk); 1118 } 1119 1120 void G1OffsetTableContigSpace::object_iterate(ObjectClosure* blk) { 1121 HeapWord* p = bottom(); 1122 if (!block_is_obj(p)) { 1123 p += block_size(p); 1124 } 1125 while (p < top()) { 1126 blk->do_object(oop(p)); 1127 p += block_size(p); 1128 } 1129 } 1130 1131 #define block_is_always_obj(q) true 1132 void G1OffsetTableContigSpace::prepare_for_compaction(CompactPoint* cp) { 1133 SCAN_AND_FORWARD(cp, top, block_is_always_obj, block_size); 1134 } 1135 #undef block_is_always_obj 1136 1137 G1OffsetTableContigSpace:: 1138 G1OffsetTableContigSpace(G1BlockOffsetSharedArray* sharedOffsetArray, 1139 MemRegion mr) : 1140 _top(bottom()), 1141 _offsets(sharedOffsetArray, mr), 1142 _par_alloc_lock(Mutex::leaf, "OffsetTableContigSpace par alloc lock", true), 1143 _gc_time_stamp(0) 1144 { 1145 _offsets.set_space(this); 1146 // false ==> we'll do the clearing if there's clearing to be done. 1147 CompactibleSpace::initialize(mr, false, SpaceDecorator::Mangle); 1148 _offsets.zero_bottom_entry(); 1149 _offsets.initialize_threshold(); 1150 }