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