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/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/atomic.inline.hpp" 40 #include "runtime/orderAccess.inline.hpp" 41 42 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC 43 44 int HeapRegion::LogOfHRGrainBytes = 0; 45 int HeapRegion::LogOfHRGrainWords = 0; 46 size_t HeapRegion::GrainBytes = 0; 47 size_t HeapRegion::GrainWords = 0; 48 size_t HeapRegion::CardsPerRegion = 0; 49 50 HeapRegionDCTOC::HeapRegionDCTOC(G1CollectedHeap* g1, 51 HeapRegion* hr, ExtendedOopClosure* cl, 52 CardTableModRefBS::PrecisionStyle precision, 53 FilterKind fk) : 54 DirtyCardToOopClosure(hr, cl, precision, NULL), 55 _hr(hr), _fk(fk), _g1(g1) { } 56 57 FilterOutOfRegionClosure::FilterOutOfRegionClosure(HeapRegion* r, 58 OopClosure* oc) : 59 _r_bottom(r->bottom()), _r_end(r->end()), _oc(oc) { } 60 61 template<class ClosureType> 62 HeapWord* walk_mem_region_loop(ClosureType* cl, G1CollectedHeap* g1h, 63 HeapRegion* hr, 64 HeapWord* cur, HeapWord* top) { 65 oop cur_oop = oop(cur); 66 size_t oop_size = hr->block_size(cur); 67 HeapWord* next_obj = cur + oop_size; 68 while (next_obj < top) { 69 // Keep filtering the remembered set. 70 if (!g1h->is_obj_dead(cur_oop, hr)) { 71 // Bottom lies entirely below top, so we can call the 72 // non-memRegion version of oop_iterate below. 73 cur_oop->oop_iterate(cl); 74 } 75 cur = next_obj; 76 cur_oop = oop(cur); 77 oop_size = hr->block_size(cur); 78 next_obj = cur + oop_size; 79 } 80 return cur; 81 } 82 83 void HeapRegionDCTOC::walk_mem_region(MemRegion mr, 84 HeapWord* bottom, 85 HeapWord* top) { 86 G1CollectedHeap* g1h = _g1; 87 size_t oop_size; 88 ExtendedOopClosure* cl2 = NULL; 89 90 FilterIntoCSClosure intoCSFilt(this, g1h, _cl); 91 FilterOutOfRegionClosure outOfRegionFilt(_hr, _cl); 92 93 switch (_fk) { 94 case NoFilterKind: cl2 = _cl; break; 95 case IntoCSFilterKind: cl2 = &intoCSFilt; break; 96 case OutOfRegionFilterKind: cl2 = &outOfRegionFilt; break; 97 default: ShouldNotReachHere(); 98 } 99 100 // Start filtering what we add to the remembered set. If the object is 101 // not considered dead, either because it is marked (in the mark bitmap) 102 // or it was allocated after marking finished, then we add it. Otherwise 103 // we can safely ignore the object. 104 if (!g1h->is_obj_dead(oop(bottom), _hr)) { 105 oop_size = oop(bottom)->oop_iterate(cl2, mr); 106 } else { 107 oop_size = _hr->block_size(bottom); 108 } 109 110 bottom += oop_size; 111 112 if (bottom < top) { 113 // We replicate the loop below for several kinds of possible filters. 114 switch (_fk) { 115 case NoFilterKind: 116 bottom = walk_mem_region_loop(_cl, g1h, _hr, bottom, top); 117 break; 118 119 case IntoCSFilterKind: { 120 FilterIntoCSClosure filt(this, g1h, _cl); 121 bottom = walk_mem_region_loop(&filt, g1h, _hr, bottom, top); 122 break; 123 } 124 125 case OutOfRegionFilterKind: { 126 FilterOutOfRegionClosure filt(_hr, _cl); 127 bottom = walk_mem_region_loop(&filt, g1h, _hr, bottom, top); 128 break; 129 } 130 131 default: 132 ShouldNotReachHere(); 133 } 134 135 // Last object. Need to do dead-obj filtering here too. 136 if (!g1h->is_obj_dead(oop(bottom), _hr)) { 137 oop(bottom)->oop_iterate(cl2, mr); 138 } 139 } 140 } 141 142 size_t HeapRegion::max_region_size() { 143 return HeapRegionBounds::max_size(); 144 } 145 146 void HeapRegion::setup_heap_region_size(size_t initial_heap_size, size_t max_heap_size) { 147 uintx region_size = G1HeapRegionSize; 148 if (FLAG_IS_DEFAULT(G1HeapRegionSize)) { 149 size_t average_heap_size = (initial_heap_size + max_heap_size) / 2; 150 region_size = MAX2(average_heap_size / HeapRegionBounds::target_number(), 151 (uintx) HeapRegionBounds::min_size()); 152 } 153 154 int region_size_log = log2_long((jlong) region_size); 155 // Recalculate the region size to make sure it's a power of 156 // 2. This means that region_size is the largest power of 2 that's 157 // <= what we've calculated so far. 158 region_size = ((uintx)1 << region_size_log); 159 160 // Now make sure that we don't go over or under our limits. 161 if (region_size < HeapRegionBounds::min_size()) { 162 region_size = HeapRegionBounds::min_size(); 163 } else if (region_size > HeapRegionBounds::max_size()) { 164 region_size = HeapRegionBounds::max_size(); 165 } 166 167 // And recalculate the log. 168 region_size_log = log2_long((jlong) region_size); 169 170 // Now, set up the globals. 171 guarantee(LogOfHRGrainBytes == 0, "we should only set it once"); 172 LogOfHRGrainBytes = region_size_log; 173 174 guarantee(LogOfHRGrainWords == 0, "we should only set it once"); 175 LogOfHRGrainWords = LogOfHRGrainBytes - LogHeapWordSize; 176 177 guarantee(GrainBytes == 0, "we should only set it once"); 178 // The cast to int is safe, given that we've bounded region_size by 179 // MIN_REGION_SIZE and MAX_REGION_SIZE. 180 GrainBytes = (size_t)region_size; 181 182 guarantee(GrainWords == 0, "we should only set it once"); 183 GrainWords = GrainBytes >> LogHeapWordSize; 184 guarantee((size_t) 1 << LogOfHRGrainWords == GrainWords, "sanity"); 185 186 guarantee(CardsPerRegion == 0, "we should only set it once"); 187 CardsPerRegion = GrainBytes >> CardTableModRefBS::card_shift; 188 } 189 190 void HeapRegion::reset_after_compaction() { 191 G1OffsetTableContigSpace::reset_after_compaction(); 192 // After a compaction the mark bitmap is invalid, so we must 193 // treat all objects as being inside the unmarked area. 194 zero_marked_bytes(); 195 init_top_at_mark_start(); 196 } 197 198 void HeapRegion::hr_clear(bool par, bool clear_space, bool locked) { 199 assert(_humongous_start_region == NULL, 200 "we should have already filtered out humongous regions"); 201 assert(_end == orig_end(), 202 "we should have already filtered out humongous regions"); 203 204 _in_collection_set = false; 205 206 set_allocation_context(AllocationContext::system()); 207 set_young_index_in_cset(-1); 208 uninstall_surv_rate_group(); 209 set_free(); 210 reset_pre_dummy_top(); 211 212 if (!par) { 213 // If this is parallel, this will be done later. 214 HeapRegionRemSet* hrrs = rem_set(); 215 if (locked) { 216 hrrs->clear_locked(); 217 } else { 218 hrrs->clear(); 219 } 220 } 221 zero_marked_bytes(); 222 223 _offsets.resize(HeapRegion::GrainWords); 224 init_top_at_mark_start(); 225 if (clear_space) clear(SpaceDecorator::Mangle); 226 } 227 228 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 } 237 238 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(); 243 244 // 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 } 251 252 void HeapRegion::set_starts_humongous(HeapWord* new_top, HeapWord* new_end) { 253 assert(!is_humongous(), "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"); 258 259 _type.set_starts_humongous(); 260 _humongous_start_region = this; 261 262 set_end(new_end); 263 _offsets.set_for_starts_humongous(new_top); 264 } 265 266 void HeapRegion::set_continues_humongous(HeapRegion* first_hr) { 267 assert(!is_humongous(), "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->is_starts_humongous(), "pre-condition"); 272 273 _type.set_continues_humongous(); 274 _humongous_start_region = first_hr; 275 } 276 277 void HeapRegion::clear_humongous() { 278 assert(is_humongous(), "pre-condition"); 279 280 if (is_starts_humongous()) { 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 } 291 292 assert(capacity() == HeapRegion::GrainBytes, "pre-condition"); 293 _humongous_start_region = NULL; 294 } 295 296 HeapRegion::HeapRegion(uint hrm_index, 297 G1BlockOffsetSharedArray* sharedOffsetArray, 298 MemRegion mr) : 299 G1OffsetTableContigSpace(sharedOffsetArray, mr), 300 _hrm_index(hrm_index), 301 _allocation_context(AllocationContext::system()), 302 _humongous_start_region(NULL), 303 _in_collection_set(false), 304 _next_in_special_set(NULL), 305 _evacuation_failed(false), 306 _prev_marked_bytes(0), _next_marked_bytes(0), _gc_efficiency(0.0), 307 _next_young_region(NULL), 308 _next_dirty_cards_region(NULL), _next(NULL), _prev(NULL), 309 #ifdef ASSERT 310 _containing_set(NULL), 311 #endif // ASSERT 312 _young_index_in_cset(-1), _surv_rate_group(NULL), _age_index(-1), 313 _rem_set(NULL), _recorded_rs_length(0), _predicted_elapsed_time_ms(0), 314 _predicted_bytes_to_copy(0) 315 { 316 _rem_set = new HeapRegionRemSet(sharedOffsetArray, this); 317 assert(HeapRegionRemSet::num_par_rem_sets() > 0, "Invariant."); 318 319 initialize(mr); 320 } 321 322 void HeapRegion::initialize(MemRegion mr, bool clear_space, bool mangle_space) { 323 assert(_rem_set->is_empty(), "Remembered set must be empty"); 324 325 G1OffsetTableContigSpace::initialize(mr, clear_space, mangle_space); 326 327 hr_clear(false /*par*/, false /*clear_space*/); 328 set_top(bottom()); 329 record_top_and_timestamp(); 330 331 assert(mr.end() == orig_end(), 332 err_msg("Given region end address " PTR_FORMAT " should match exactly " 333 "bottom plus one region size, i.e. " PTR_FORMAT, 334 p2i(mr.end()), p2i(orig_end()))); 335 } 336 337 CompactibleSpace* HeapRegion::next_compaction_space() const { 338 return G1CollectedHeap::heap()->next_compaction_region(this); 339 } 340 341 void HeapRegion::note_self_forwarding_removal_start(bool during_initial_mark, 342 bool during_conc_mark) { 343 // We always recreate the prev marking info and we'll explicitly 344 // mark all objects we find to be self-forwarded on the prev 345 // bitmap. So all objects need to be below PTAMS. 346 _prev_marked_bytes = 0; 347 348 if (during_initial_mark) { 349 // During initial-mark, we'll also explicitly mark all objects 350 // we find to be self-forwarded on the next bitmap. So all 351 // objects need to be below NTAMS. 352 _next_top_at_mark_start = top(); 353 _next_marked_bytes = 0; 354 } else if (during_conc_mark) { 355 // During concurrent mark, all objects in the CSet (including 356 // the ones we find to be self-forwarded) are implicitly live. 357 // So all objects need to be above NTAMS. 358 _next_top_at_mark_start = bottom(); 359 _next_marked_bytes = 0; 360 } 361 } 362 363 void HeapRegion::note_self_forwarding_removal_end(bool during_initial_mark, 364 bool during_conc_mark, 365 size_t marked_bytes) { 366 assert(0 <= marked_bytes && marked_bytes <= used(), 367 err_msg("marked: "SIZE_FORMAT" used: "SIZE_FORMAT, 368 marked_bytes, used())); 369 _prev_top_at_mark_start = top(); 370 _prev_marked_bytes = marked_bytes; 371 } 372 373 HeapWord* 374 HeapRegion::object_iterate_mem_careful(MemRegion mr, 375 ObjectClosure* cl) { 376 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 377 // We used to use "block_start_careful" here. But we're actually happy 378 // to update the BOT while we do this... 379 HeapWord* cur = block_start(mr.start()); 380 mr = mr.intersection(used_region()); 381 if (mr.is_empty()) return NULL; 382 // Otherwise, find the obj that extends onto mr.start(). 383 384 assert(cur <= mr.start() 385 && (oop(cur)->klass_or_null() == NULL || 386 cur + oop(cur)->size() > mr.start()), 387 "postcondition of block_start"); 388 oop obj; 389 while (cur < mr.end()) { 390 obj = oop(cur); 391 if (obj->klass_or_null() == NULL) { 392 // Ran into an unparseable point. 393 return cur; 394 } else if (!g1h->is_obj_dead(obj)) { 395 cl->do_object(obj); 396 } 397 cur += block_size(cur); 398 } 399 return NULL; 400 } 401 402 HeapWord* 403 HeapRegion:: 404 oops_on_card_seq_iterate_careful(MemRegion mr, 405 FilterOutOfRegionClosure* cl, 406 bool filter_young, 407 jbyte* card_ptr) { 408 // Currently, we should only have to clean the card if filter_young 409 // is true and vice versa. 410 if (filter_young) { 411 assert(card_ptr != NULL, "pre-condition"); 412 } else { 413 assert(card_ptr == NULL, "pre-condition"); 414 } 415 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 416 417 // If we're within a stop-world GC, then we might look at a card in a 418 // GC alloc region that extends onto a GC LAB, which may not be 419 // parseable. Stop such at the "saved_mark" of the region. 420 if (g1h->is_gc_active()) { 421 mr = mr.intersection(used_region_at_save_marks()); 422 } else { 423 mr = mr.intersection(used_region()); 424 } 425 if (mr.is_empty()) return NULL; 426 // Otherwise, find the obj that extends onto mr.start(). 427 428 // The intersection of the incoming mr (for the card) and the 429 // allocated part of the region is non-empty. This implies that 430 // we have actually allocated into this region. The code in 431 // G1CollectedHeap.cpp that allocates a new region sets the 432 // is_young tag on the region before allocating. Thus we 433 // safely know if this region is young. 434 if (is_young() && filter_young) { 435 return NULL; 436 } 437 438 assert(!is_young(), "check value of filter_young"); 439 440 // We can only clean the card here, after we make the decision that 441 // the card is not young. And we only clean the card if we have been 442 // asked to (i.e., card_ptr != NULL). 443 if (card_ptr != NULL) { 444 *card_ptr = CardTableModRefBS::clean_card_val(); 445 // We must complete this write before we do any of the reads below. 446 OrderAccess::storeload(); 447 } 448 449 // Cache the boundaries of the memory region in some const locals 450 HeapWord* const start = mr.start(); 451 HeapWord* const end = mr.end(); 452 453 // We used to use "block_start_careful" here. But we're actually happy 454 // to update the BOT while we do this... 455 HeapWord* cur = block_start(start); 456 assert(cur <= start, "Postcondition"); 457 458 oop obj; 459 460 HeapWord* next = cur; 461 while (next <= start) { 462 cur = next; 463 obj = oop(cur); 464 if (obj->klass_or_null() == NULL) { 465 // Ran into an unparseable point. 466 return cur; 467 } 468 // Otherwise... 469 next = cur + block_size(cur); 470 } 471 472 // If we finish the above loop...We have a parseable object that 473 // begins on or before the start of the memory region, and ends 474 // inside or spans the entire region. 475 476 assert(obj == oop(cur), "sanity"); 477 assert(cur <= start, "Loop postcondition"); 478 assert(obj->klass_or_null() != NULL, "Loop postcondition"); 479 assert((cur + block_size(cur)) > start, "Loop postcondition"); 480 481 if (!g1h->is_obj_dead(obj)) { 482 obj->oop_iterate(cl, mr); 483 } 484 485 while (cur < end) { 486 obj = oop(cur); 487 if (obj->klass_or_null() == NULL) { 488 // Ran into an unparseable point. 489 return cur; 490 }; 491 492 // Otherwise: 493 next = cur + block_size(cur); 494 495 if (!g1h->is_obj_dead(obj)) { 496 if (next < end || !obj->is_objArray()) { 497 // This object either does not span the MemRegion 498 // boundary, or if it does it's not an array. 499 // Apply closure to whole object. 500 obj->oop_iterate(cl); 501 } else { 502 // This obj is an array that spans the boundary. 503 // Stop at the boundary. 504 obj->oop_iterate(cl, mr); 505 } 506 } 507 cur = next; 508 } 509 return NULL; 510 } 511 512 // Code roots support 513 514 void HeapRegion::add_strong_code_root(nmethod* nm) { 515 HeapRegionRemSet* hrrs = rem_set(); 516 hrrs->add_strong_code_root(nm); 517 } 518 519 void HeapRegion::add_strong_code_root_locked(nmethod* nm) { 520 assert_locked_or_safepoint(CodeCache_lock); 521 HeapRegionRemSet* hrrs = rem_set(); 522 hrrs->add_strong_code_root_locked(nm); 523 } 524 525 void HeapRegion::remove_strong_code_root(nmethod* nm) { 526 HeapRegionRemSet* hrrs = rem_set(); 527 hrrs->remove_strong_code_root(nm); 528 } 529 530 void HeapRegion::strong_code_roots_do(CodeBlobClosure* blk) const { 531 HeapRegionRemSet* hrrs = rem_set(); 532 hrrs->strong_code_roots_do(blk); 533 } 534 535 class VerifyStrongCodeRootOopClosure: public OopClosure { 536 const HeapRegion* _hr; 537 nmethod* _nm; 538 bool _failures; 539 bool _has_oops_in_region; 540 541 template <class T> void do_oop_work(T* p) { 542 T heap_oop = oopDesc::load_heap_oop(p); 543 if (!oopDesc::is_null(heap_oop)) { 544 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 545 546 // Note: not all the oops embedded in the nmethod are in the 547 // current region. We only look at those which are. 548 if (_hr->is_in(obj)) { 549 // Object is in the region. Check that its less than top 550 if (_hr->top() <= (HeapWord*)obj) { 551 // Object is above top 552 gclog_or_tty->print_cr("Object "PTR_FORMAT" in region " 553 "["PTR_FORMAT", "PTR_FORMAT") is above " 554 "top "PTR_FORMAT, 555 (void *)obj, _hr->bottom(), _hr->end(), _hr->top()); 556 _failures = true; 557 return; 558 } 559 // Nmethod has at least one oop in the current region 560 _has_oops_in_region = true; 561 } 562 } 563 } 564 565 public: 566 VerifyStrongCodeRootOopClosure(const HeapRegion* hr, nmethod* nm): 567 _hr(hr), _failures(false), _has_oops_in_region(false) {} 568 569 void do_oop(narrowOop* p) { do_oop_work(p); } 570 void do_oop(oop* p) { do_oop_work(p); } 571 572 bool failures() { return _failures; } 573 bool has_oops_in_region() { return _has_oops_in_region; } 574 }; 575 576 class VerifyStrongCodeRootCodeBlobClosure: public CodeBlobClosure { 577 const HeapRegion* _hr; 578 bool _failures; 579 public: 580 VerifyStrongCodeRootCodeBlobClosure(const HeapRegion* hr) : 581 _hr(hr), _failures(false) {} 582 583 void do_code_blob(CodeBlob* cb) { 584 nmethod* nm = (cb == NULL) ? NULL : cb->as_nmethod_or_null(); 585 if (nm != NULL) { 586 // Verify that the nemthod is live 587 if (!nm->is_alive()) { 588 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] has dead nmethod " 589 PTR_FORMAT" in its strong code roots", 590 _hr->bottom(), _hr->end(), nm); 591 _failures = true; 592 } else { 593 VerifyStrongCodeRootOopClosure oop_cl(_hr, nm); 594 nm->oops_do(&oop_cl); 595 if (!oop_cl.has_oops_in_region()) { 596 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] has nmethod " 597 PTR_FORMAT" in its strong code roots " 598 "with no pointers into region", 599 _hr->bottom(), _hr->end(), nm); 600 _failures = true; 601 } else if (oop_cl.failures()) { 602 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] has other " 603 "failures for nmethod "PTR_FORMAT, 604 _hr->bottom(), _hr->end(), nm); 605 _failures = true; 606 } 607 } 608 } 609 } 610 611 bool failures() { return _failures; } 612 }; 613 614 void HeapRegion::verify_strong_code_roots(VerifyOption vo, bool* failures) const { 615 if (!G1VerifyHeapRegionCodeRoots) { 616 // We're not verifying code roots. 617 return; 618 } 619 if (vo == VerifyOption_G1UseMarkWord) { 620 // Marking verification during a full GC is performed after class 621 // unloading, code cache unloading, etc so the strong code roots 622 // attached to each heap region are in an inconsistent state. They won't 623 // be consistent until the strong code roots are rebuilt after the 624 // actual GC. Skip verifying the strong code roots in this particular 625 // time. 626 assert(VerifyDuringGC, "only way to get here"); 627 return; 628 } 629 630 HeapRegionRemSet* hrrs = rem_set(); 631 size_t strong_code_roots_length = hrrs->strong_code_roots_list_length(); 632 633 // if this region is empty then there should be no entries 634 // on its strong code root list 635 if (is_empty()) { 636 if (strong_code_roots_length > 0) { 637 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] is empty " 638 "but has "SIZE_FORMAT" code root entries", 639 bottom(), end(), strong_code_roots_length); 640 *failures = true; 641 } 642 return; 643 } 644 645 if (is_continues_humongous()) { 646 if (strong_code_roots_length > 0) { 647 gclog_or_tty->print_cr("region "HR_FORMAT" is a continuation of a humongous " 648 "region but has "SIZE_FORMAT" code root entries", 649 HR_FORMAT_PARAMS(this), strong_code_roots_length); 650 *failures = true; 651 } 652 return; 653 } 654 655 VerifyStrongCodeRootCodeBlobClosure cb_cl(this); 656 strong_code_roots_do(&cb_cl); 657 658 if (cb_cl.failures()) { 659 *failures = true; 660 } 661 } 662 663 void HeapRegion::print() const { print_on(gclog_or_tty); } 664 void HeapRegion::print_on(outputStream* st) const { 665 st->print("AC%4u", allocation_context()); 666 667 st->print(" %2s", get_short_type_str()); 668 if (in_collection_set()) 669 st->print(" CS"); 670 else 671 st->print(" "); 672 st->print(" TS %5d", _gc_time_stamp); 673 st->print(" PTAMS "PTR_FORMAT" NTAMS "PTR_FORMAT, 674 prev_top_at_mark_start(), next_top_at_mark_start()); 675 G1OffsetTableContigSpace::print_on(st); 676 } 677 678 class VerifyLiveClosure: public OopClosure { 679 private: 680 G1CollectedHeap* _g1h; 681 CardTableModRefBS* _bs; 682 oop _containing_obj; 683 bool _failures; 684 int _n_failures; 685 VerifyOption _vo; 686 public: 687 // _vo == UsePrevMarking -> use "prev" marking information, 688 // _vo == UseNextMarking -> use "next" marking information, 689 // _vo == UseMarkWord -> use mark word from object header. 690 VerifyLiveClosure(G1CollectedHeap* g1h, VerifyOption vo) : 691 _g1h(g1h), _bs(NULL), _containing_obj(NULL), 692 _failures(false), _n_failures(0), _vo(vo) 693 { 694 BarrierSet* bs = _g1h->barrier_set(); 695 if (bs->is_a(BarrierSet::CardTableModRef)) 696 _bs = (CardTableModRefBS*)bs; 697 } 698 699 void set_containing_obj(oop obj) { 700 _containing_obj = obj; 701 } 702 703 bool failures() { return _failures; } 704 int n_failures() { return _n_failures; } 705 706 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 707 virtual void do_oop( oop* p) { do_oop_work(p); } 708 709 void print_object(outputStream* out, oop obj) { 710 #ifdef PRODUCT 711 Klass* k = obj->klass(); 712 const char* class_name = InstanceKlass::cast(k)->external_name(); 713 out->print_cr("class name %s", class_name); 714 #else // PRODUCT 715 obj->print_on(out); 716 #endif // PRODUCT 717 } 718 719 template <class T> 720 void do_oop_work(T* p) { 721 assert(_containing_obj != NULL, "Precondition"); 722 assert(!_g1h->is_obj_dead_cond(_containing_obj, _vo), 723 "Precondition"); 724 T heap_oop = oopDesc::load_heap_oop(p); 725 if (!oopDesc::is_null(heap_oop)) { 726 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 727 bool failed = false; 728 if (!_g1h->is_in_closed_subset(obj) || _g1h->is_obj_dead_cond(obj, _vo)) { 729 MutexLockerEx x(ParGCRareEvent_lock, 730 Mutex::_no_safepoint_check_flag); 731 732 if (!_failures) { 733 gclog_or_tty->cr(); 734 gclog_or_tty->print_cr("----------"); 735 } 736 if (!_g1h->is_in_closed_subset(obj)) { 737 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p); 738 gclog_or_tty->print_cr("Field "PTR_FORMAT 739 " of live obj "PTR_FORMAT" in region " 740 "["PTR_FORMAT", "PTR_FORMAT")", 741 p, (void*) _containing_obj, 742 from->bottom(), from->end()); 743 print_object(gclog_or_tty, _containing_obj); 744 gclog_or_tty->print_cr("points to obj "PTR_FORMAT" not in the heap", 745 (void*) obj); 746 } else { 747 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p); 748 HeapRegion* to = _g1h->heap_region_containing((HeapWord*)obj); 749 gclog_or_tty->print_cr("Field "PTR_FORMAT 750 " of live obj "PTR_FORMAT" in region " 751 "["PTR_FORMAT", "PTR_FORMAT")", 752 p, (void*) _containing_obj, 753 from->bottom(), from->end()); 754 print_object(gclog_or_tty, _containing_obj); 755 gclog_or_tty->print_cr("points to dead obj "PTR_FORMAT" in region " 756 "["PTR_FORMAT", "PTR_FORMAT")", 757 (void*) obj, to->bottom(), to->end()); 758 print_object(gclog_or_tty, obj); 759 } 760 gclog_or_tty->print_cr("----------"); 761 gclog_or_tty->flush(); 762 _failures = true; 763 failed = true; 764 _n_failures++; 765 } 766 767 if (!_g1h->full_collection() || G1VerifyRSetsDuringFullGC) { 768 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p); 769 HeapRegion* to = _g1h->heap_region_containing(obj); 770 if (from != NULL && to != NULL && 771 from != to && 772 !to->is_humongous()) { 773 jbyte cv_obj = *_bs->byte_for_const(_containing_obj); 774 jbyte cv_field = *_bs->byte_for_const(p); 775 const jbyte dirty = CardTableModRefBS::dirty_card_val(); 776 777 bool is_bad = !(from->is_young() 778 || to->rem_set()->contains_reference(p) 779 || !G1HRRSFlushLogBuffersOnVerify && // buffers were not flushed 780 (_containing_obj->is_objArray() ? 781 cv_field == dirty 782 : cv_obj == dirty || cv_field == dirty)); 783 if (is_bad) { 784 MutexLockerEx x(ParGCRareEvent_lock, 785 Mutex::_no_safepoint_check_flag); 786 787 if (!_failures) { 788 gclog_or_tty->cr(); 789 gclog_or_tty->print_cr("----------"); 790 } 791 gclog_or_tty->print_cr("Missing rem set entry:"); 792 gclog_or_tty->print_cr("Field "PTR_FORMAT" " 793 "of obj "PTR_FORMAT", " 794 "in region "HR_FORMAT, 795 p, (void*) _containing_obj, 796 HR_FORMAT_PARAMS(from)); 797 _containing_obj->print_on(gclog_or_tty); 798 gclog_or_tty->print_cr("points to obj "PTR_FORMAT" " 799 "in region "HR_FORMAT, 800 (void*) obj, 801 HR_FORMAT_PARAMS(to)); 802 obj->print_on(gclog_or_tty); 803 gclog_or_tty->print_cr("Obj head CTE = %d, field CTE = %d.", 804 cv_obj, cv_field); 805 gclog_or_tty->print_cr("----------"); 806 gclog_or_tty->flush(); 807 _failures = true; 808 if (!failed) _n_failures++; 809 } 810 } 811 } 812 } 813 } 814 }; 815 816 // This really ought to be commoned up into OffsetTableContigSpace somehow. 817 // We would need a mechanism to make that code skip dead objects. 818 819 void HeapRegion::verify(VerifyOption vo, 820 bool* failures) const { 821 G1CollectedHeap* g1 = G1CollectedHeap::heap(); 822 *failures = false; 823 HeapWord* p = bottom(); 824 HeapWord* prev_p = NULL; 825 VerifyLiveClosure vl_cl(g1, vo); 826 bool is_region_humongous = is_humongous(); 827 size_t object_num = 0; 828 while (p < top()) { 829 oop obj = oop(p); 830 size_t obj_size = block_size(p); 831 object_num += 1; 832 833 if (is_region_humongous != g1->is_humongous(obj_size) && 834 !g1->is_obj_dead(obj, this)) { // Dead objects may have bigger block_size since they span several objects. 835 gclog_or_tty->print_cr("obj "PTR_FORMAT" is of %shumongous size (" 836 SIZE_FORMAT" words) in a %shumongous region", 837 p, g1->is_humongous(obj_size) ? "" : "non-", 838 obj_size, is_region_humongous ? "" : "non-"); 839 *failures = true; 840 return; 841 } 842 843 if (!g1->is_obj_dead_cond(obj, this, vo)) { 844 if (obj->is_oop()) { 845 Klass* klass = obj->klass(); 846 bool is_metaspace_object = Metaspace::contains(klass) || 847 (vo == VerifyOption_G1UsePrevMarking && 848 ClassLoaderDataGraph::unload_list_contains(klass)); 849 if (!is_metaspace_object) { 850 gclog_or_tty->print_cr("klass "PTR_FORMAT" of object "PTR_FORMAT" " 851 "not metadata", klass, (void *)obj); 852 *failures = true; 853 return; 854 } else if (!klass->is_klass()) { 855 gclog_or_tty->print_cr("klass "PTR_FORMAT" of object "PTR_FORMAT" " 856 "not a klass", klass, (void *)obj); 857 *failures = true; 858 return; 859 } else { 860 vl_cl.set_containing_obj(obj); 861 obj->oop_iterate_no_header(&vl_cl); 862 if (vl_cl.failures()) { 863 *failures = true; 864 } 865 if (G1MaxVerifyFailures >= 0 && 866 vl_cl.n_failures() >= G1MaxVerifyFailures) { 867 return; 868 } 869 } 870 } else { 871 gclog_or_tty->print_cr(PTR_FORMAT" no an oop", (void *)obj); 872 *failures = true; 873 return; 874 } 875 } 876 prev_p = p; 877 p += obj_size; 878 } 879 880 if (!is_young() && !is_empty()) { 881 _offsets.verify(); 882 } 883 884 if (p != top()) { 885 gclog_or_tty->print_cr("end of last object "PTR_FORMAT" " 886 "does not match top "PTR_FORMAT, p, top()); 887 *failures = true; 888 return; 889 } 890 891 HeapWord* the_end = end(); 892 assert(p == top(), "it should still hold"); 893 // Do some extra BOT consistency checking for addresses in the 894 // range [top, end). BOT look-ups in this range should yield 895 // top. No point in doing that if top == end (there's nothing there). 896 if (p < the_end) { 897 // Look up top 898 HeapWord* addr_1 = p; 899 HeapWord* b_start_1 = _offsets.block_start_const(addr_1); 900 if (b_start_1 != p) { 901 gclog_or_tty->print_cr("BOT look up for top: "PTR_FORMAT" " 902 " yielded "PTR_FORMAT", expecting "PTR_FORMAT, 903 addr_1, b_start_1, p); 904 *failures = true; 905 return; 906 } 907 908 // Look up top + 1 909 HeapWord* addr_2 = p + 1; 910 if (addr_2 < the_end) { 911 HeapWord* b_start_2 = _offsets.block_start_const(addr_2); 912 if (b_start_2 != p) { 913 gclog_or_tty->print_cr("BOT look up for top + 1: "PTR_FORMAT" " 914 " yielded "PTR_FORMAT", expecting "PTR_FORMAT, 915 addr_2, b_start_2, p); 916 *failures = true; 917 return; 918 } 919 } 920 921 // Look up an address between top and end 922 size_t diff = pointer_delta(the_end, p) / 2; 923 HeapWord* addr_3 = p + diff; 924 if (addr_3 < the_end) { 925 HeapWord* b_start_3 = _offsets.block_start_const(addr_3); 926 if (b_start_3 != p) { 927 gclog_or_tty->print_cr("BOT look up for top + diff: "PTR_FORMAT" " 928 " yielded "PTR_FORMAT", expecting "PTR_FORMAT, 929 addr_3, b_start_3, p); 930 *failures = true; 931 return; 932 } 933 } 934 935 // Look up end - 1 936 HeapWord* addr_4 = the_end - 1; 937 HeapWord* b_start_4 = _offsets.block_start_const(addr_4); 938 if (b_start_4 != p) { 939 gclog_or_tty->print_cr("BOT look up for end - 1: "PTR_FORMAT" " 940 " yielded "PTR_FORMAT", expecting "PTR_FORMAT, 941 addr_4, b_start_4, p); 942 *failures = true; 943 return; 944 } 945 } 946 947 if (is_region_humongous && object_num > 1) { 948 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] is humongous " 949 "but has "SIZE_FORMAT", objects", 950 bottom(), end(), object_num); 951 *failures = true; 952 return; 953 } 954 955 verify_strong_code_roots(vo, failures); 956 } 957 958 void HeapRegion::verify() const { 959 bool dummy = false; 960 verify(VerifyOption_G1UsePrevMarking, /* failures */ &dummy); 961 } 962 963 void HeapRegion::prepare_for_compaction(CompactPoint* cp) { 964 scan_and_forward(this, cp); 965 } 966 967 // G1OffsetTableContigSpace code; copied from space.cpp. Hope this can go 968 // away eventually. 969 970 void G1OffsetTableContigSpace::clear(bool mangle_space) { 971 set_top(bottom()); 972 set_saved_mark_word(bottom()); 973 CompactibleSpace::clear(mangle_space); 974 reset_bot(); 975 } 976 977 void G1OffsetTableContigSpace::set_bottom(HeapWord* new_bottom) { 978 Space::set_bottom(new_bottom); 979 _offsets.set_bottom(new_bottom); 980 } 981 982 void G1OffsetTableContigSpace::set_end(HeapWord* new_end) { 983 Space::set_end(new_end); 984 _offsets.resize(new_end - bottom()); 985 } 986 987 void G1OffsetTableContigSpace::print() const { 988 print_short(); 989 gclog_or_tty->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " 990 INTPTR_FORMAT ", " INTPTR_FORMAT ")", 991 bottom(), top(), _offsets.threshold(), end()); 992 } 993 994 HeapWord* G1OffsetTableContigSpace::initialize_threshold() { 995 return _offsets.initialize_threshold(); 996 } 997 998 HeapWord* G1OffsetTableContigSpace::cross_threshold(HeapWord* start, 999 HeapWord* end) { 1000 _offsets.alloc_block(start, end); 1001 return _offsets.threshold(); 1002 } 1003 1004 HeapWord* G1OffsetTableContigSpace::saved_mark_word() const { 1005 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 1006 assert( _gc_time_stamp <= g1h->get_gc_time_stamp(), "invariant" ); 1007 HeapWord* local_top = top(); 1008 OrderAccess::loadload(); 1009 if (_gc_time_stamp < g1h->get_gc_time_stamp()) { 1010 return local_top; 1011 } else { 1012 return Space::saved_mark_word(); 1013 } 1014 } 1015 1016 void G1OffsetTableContigSpace::record_top_and_timestamp() { 1017 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 1018 unsigned curr_gc_time_stamp = g1h->get_gc_time_stamp(); 1019 1020 if (_gc_time_stamp < curr_gc_time_stamp) { 1021 // The order of these is important, as another thread might be 1022 // about to start scanning this region. If it does so after 1023 // set_saved_mark and before _gc_time_stamp = ..., then the latter 1024 // will be false, and it will pick up top() as the high water mark 1025 // of region. If it does so after _gc_time_stamp = ..., then it 1026 // will pick up the right saved_mark_word() as the high water mark 1027 // of the region. Either way, the behavior will be correct. 1028 Space::set_saved_mark_word(top()); 1029 OrderAccess::storestore(); 1030 _gc_time_stamp = curr_gc_time_stamp; 1031 // No need to do another barrier to flush the writes above. If 1032 // this is called in parallel with other threads trying to 1033 // allocate into the region, the caller should call this while 1034 // holding a lock and when the lock is released the writes will be 1035 // flushed. 1036 } 1037 } 1038 1039 void G1OffsetTableContigSpace::safe_object_iterate(ObjectClosure* blk) { 1040 object_iterate(blk); 1041 } 1042 1043 void G1OffsetTableContigSpace::object_iterate(ObjectClosure* blk) { 1044 HeapWord* p = bottom(); 1045 while (p < top()) { 1046 if (block_is_obj(p)) { 1047 blk->do_object(oop(p)); 1048 } 1049 p += block_size(p); 1050 } 1051 } 1052 1053 G1OffsetTableContigSpace:: 1054 G1OffsetTableContigSpace(G1BlockOffsetSharedArray* sharedOffsetArray, 1055 MemRegion mr) : 1056 _offsets(sharedOffsetArray, mr), 1057 _par_alloc_lock(Mutex::leaf, "OffsetTableContigSpace par alloc lock", true), 1058 _gc_time_stamp(0) 1059 { 1060 _offsets.set_space(this); 1061 } 1062 1063 void G1OffsetTableContigSpace::initialize(MemRegion mr, bool clear_space, bool mangle_space) { 1064 CompactibleSpace::initialize(mr, clear_space, mangle_space); 1065 _top = bottom(); 1066 reset_bot(); 1067 } 1068