1 /* 2 * Copyright (c) 2001, 2012, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "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 "memory/genOopClosures.inline.hpp" 34 #include "memory/iterator.hpp" 35 #include "oops/oop.inline.hpp" 36 37 int HeapRegion::LogOfHRGrainBytes = 0; 38 int HeapRegion::LogOfHRGrainWords = 0; 39 size_t HeapRegion::GrainBytes = 0; 40 size_t HeapRegion::GrainWords = 0; 41 size_t HeapRegion::CardsPerRegion = 0; 42 43 HeapRegionDCTOC::HeapRegionDCTOC(G1CollectedHeap* g1, 44 HeapRegion* hr, ExtendedOopClosure* cl, 45 CardTableModRefBS::PrecisionStyle precision, 46 FilterKind fk) : 47 ContiguousSpaceDCTOC(hr, cl, precision, NULL), 48 _hr(hr), _fk(fk), _g1(g1) { } 49 50 FilterOutOfRegionClosure::FilterOutOfRegionClosure(HeapRegion* r, 51 OopClosure* oc) : 52 _r_bottom(r->bottom()), _r_end(r->end()), _oc(oc) { } 53 54 template<class ClosureType> 55 HeapWord* walk_mem_region_loop(ClosureType* cl, G1CollectedHeap* g1h, 56 HeapRegion* hr, 57 HeapWord* cur, HeapWord* top) { 58 oop cur_oop = oop(cur); 59 int oop_size = cur_oop->size(); 60 HeapWord* next_obj = cur + oop_size; 61 while (next_obj < top) { 62 // Keep filtering the remembered set. 63 if (!g1h->is_obj_dead(cur_oop, hr)) { 64 // Bottom lies entirely below top, so we can call the 65 // non-memRegion version of oop_iterate below. 66 cur_oop->oop_iterate(cl); 67 } 68 cur = next_obj; 69 cur_oop = oop(cur); 70 oop_size = cur_oop->size(); 71 next_obj = cur + oop_size; 72 } 73 return cur; 74 } 75 76 void HeapRegionDCTOC::walk_mem_region_with_cl(MemRegion mr, 77 HeapWord* bottom, 78 HeapWord* top, 79 ExtendedOopClosure* cl) { 80 G1CollectedHeap* g1h = _g1; 81 int oop_size; 82 ExtendedOopClosure* cl2 = NULL; 83 84 FilterIntoCSClosure intoCSFilt(this, g1h, cl); 85 FilterOutOfRegionClosure outOfRegionFilt(_hr, cl); 86 87 switch (_fk) { 88 case NoFilterKind: cl2 = cl; break; 89 case IntoCSFilterKind: cl2 = &intoCSFilt; break; 90 case OutOfRegionFilterKind: cl2 = &outOfRegionFilt; break; 91 default: ShouldNotReachHere(); 92 } 93 94 // Start filtering what we add to the remembered set. If the object is 95 // not considered dead, either because it is marked (in the mark bitmap) 96 // or it was allocated after marking finished, then we add it. Otherwise 97 // we can safely ignore the object. 98 if (!g1h->is_obj_dead(oop(bottom), _hr)) { 99 oop_size = oop(bottom)->oop_iterate(cl2, mr); 100 } else { 101 oop_size = oop(bottom)->size(); 102 } 103 104 bottom += oop_size; 105 106 if (bottom < top) { 107 // We replicate the loop below for several kinds of possible filters. 108 switch (_fk) { 109 case NoFilterKind: 110 bottom = walk_mem_region_loop(cl, g1h, _hr, bottom, top); 111 break; 112 113 case IntoCSFilterKind: { 114 FilterIntoCSClosure filt(this, g1h, cl); 115 bottom = walk_mem_region_loop(&filt, g1h, _hr, bottom, top); 116 break; 117 } 118 119 case OutOfRegionFilterKind: { 120 FilterOutOfRegionClosure filt(_hr, cl); 121 bottom = walk_mem_region_loop(&filt, g1h, _hr, bottom, top); 122 break; 123 } 124 125 default: 126 ShouldNotReachHere(); 127 } 128 129 // Last object. Need to do dead-obj filtering here too. 130 if (!g1h->is_obj_dead(oop(bottom), _hr)) { 131 oop(bottom)->oop_iterate(cl2, mr); 132 } 133 } 134 } 135 136 // Minimum region size; we won't go lower than that. 137 // We might want to decrease this in the future, to deal with small 138 // heaps a bit more efficiently. 139 #define MIN_REGION_SIZE ( 1024 * 1024 ) 140 141 // Maximum region size; we don't go higher than that. There's a good 142 // reason for having an upper bound. We don't want regions to get too 143 // large, otherwise cleanup's effectiveness would decrease as there 144 // will be fewer opportunities to find totally empty regions after 145 // marking. 146 #define MAX_REGION_SIZE ( 32 * 1024 * 1024 ) 147 148 // The automatic region size calculation will try to have around this 149 // many regions in the heap (based on the min heap size). 150 #define TARGET_REGION_NUMBER 2048 151 152 void HeapRegion::setup_heap_region_size(uintx min_heap_size) { 153 // region_size in bytes 154 uintx region_size = G1HeapRegionSize; 155 if (FLAG_IS_DEFAULT(G1HeapRegionSize)) { 156 // We base the automatic calculation on the min heap size. This 157 // can be problematic if the spread between min and max is quite 158 // wide, imagine -Xms128m -Xmx32g. But, if we decided it based on 159 // the max size, the region size might be way too large for the 160 // min size. Either way, some users might have to set the region 161 // size manually for some -Xms / -Xmx combos. 162 163 region_size = MAX2(min_heap_size / TARGET_REGION_NUMBER, 164 (uintx) MIN_REGION_SIZE); 165 } 166 167 int region_size_log = log2_long((jlong) region_size); 168 // Recalculate the region size to make sure it's a power of 169 // 2. This means that region_size is the largest power of 2 that's 170 // <= what we've calculated so far. 171 region_size = ((uintx)1 << region_size_log); 172 173 // Now make sure that we don't go over or under our limits. 174 if (region_size < MIN_REGION_SIZE) { 175 region_size = MIN_REGION_SIZE; 176 } else if (region_size > MAX_REGION_SIZE) { 177 region_size = MAX_REGION_SIZE; 178 } 179 180 if (region_size != G1HeapRegionSize) { 181 // Update the flag to make sure that PrintFlagsFinal logs the correct value 182 FLAG_SET_ERGO(uintx, G1HeapRegionSize, region_size); 183 } 184 185 // And recalculate the log. 186 region_size_log = log2_long((jlong) region_size); 187 188 // Now, set up the globals. 189 guarantee(LogOfHRGrainBytes == 0, "we should only set it once"); 190 LogOfHRGrainBytes = region_size_log; 191 192 guarantee(LogOfHRGrainWords == 0, "we should only set it once"); 193 LogOfHRGrainWords = LogOfHRGrainBytes - LogHeapWordSize; 194 195 guarantee(GrainBytes == 0, "we should only set it once"); 196 // The cast to int is safe, given that we've bounded region_size by 197 // MIN_REGION_SIZE and MAX_REGION_SIZE. 198 GrainBytes = (size_t)region_size; 199 200 guarantee(GrainWords == 0, "we should only set it once"); 201 GrainWords = GrainBytes >> LogHeapWordSize; 202 guarantee((size_t) 1 << LogOfHRGrainWords == GrainWords, "sanity"); 203 204 guarantee(CardsPerRegion == 0, "we should only set it once"); 205 CardsPerRegion = GrainBytes >> CardTableModRefBS::card_shift; 206 } 207 208 void HeapRegion::reset_after_compaction() { 209 G1OffsetTableContigSpace::reset_after_compaction(); 210 // After a compaction the mark bitmap is invalid, so we must 211 // treat all objects as being inside the unmarked area. 212 zero_marked_bytes(); 213 init_top_at_mark_start(); 214 } 215 216 void HeapRegion::hr_clear(bool par, bool clear_space) { 217 assert(_humongous_type == NotHumongous, 218 "we should have already filtered out humongous regions"); 219 assert(_humongous_start_region == NULL, 220 "we should have already filtered out humongous regions"); 221 assert(_end == _orig_end, 222 "we should have already filtered out humongous regions"); 223 224 _in_collection_set = false; 225 226 set_young_index_in_cset(-1); 227 uninstall_surv_rate_group(); 228 set_young_type(NotYoung); 229 reset_pre_dummy_top(); 230 231 if (!par) { 232 // If this is parallel, this will be done later. 233 HeapRegionRemSet* hrrs = rem_set(); 234 hrrs->clear(); 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), _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 set_saved_mark(); 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::save_marks() { 398 set_saved_mark(); 399 } 400 401 void HeapRegion::oops_in_mr_iterate(MemRegion mr, ExtendedOopClosure* cl) { 402 HeapWord* p = mr.start(); 403 HeapWord* e = mr.end(); 404 oop obj; 405 while (p < e) { 406 obj = oop(p); 407 p += obj->oop_iterate(cl); 408 } 409 assert(p == e, "bad memregion: doesn't end on obj boundary"); 410 } 411 412 #define HeapRegion_OOP_SINCE_SAVE_MARKS_DEFN(OopClosureType, nv_suffix) \ 413 void HeapRegion::oop_since_save_marks_iterate##nv_suffix(OopClosureType* cl) { \ 414 ContiguousSpace::oop_since_save_marks_iterate##nv_suffix(cl); \ 415 } 416 SPECIALIZED_SINCE_SAVE_MARKS_CLOSURES(HeapRegion_OOP_SINCE_SAVE_MARKS_DEFN) 417 418 419 void HeapRegion::oop_before_save_marks_iterate(ExtendedOopClosure* cl) { 420 oops_in_mr_iterate(MemRegion(bottom(), saved_mark_word()), cl); 421 } 422 423 void HeapRegion::note_self_forwarding_removal_start(bool during_initial_mark, 424 bool during_conc_mark) { 425 // We always recreate the prev marking info and we'll explicitly 426 // mark all objects we find to be self-forwarded on the prev 427 // bitmap. So all objects need to be below PTAMS. 428 _prev_top_at_mark_start = top(); 429 _prev_marked_bytes = 0; 430 431 if (during_initial_mark) { 432 // During initial-mark, we'll also explicitly mark all objects 433 // we find to be self-forwarded on the next bitmap. So all 434 // objects need to be below NTAMS. 435 _next_top_at_mark_start = top(); 436 _next_marked_bytes = 0; 437 } else if (during_conc_mark) { 438 // During concurrent mark, all objects in the CSet (including 439 // the ones we find to be self-forwarded) are implicitly live. 440 // So all objects need to be above NTAMS. 441 _next_top_at_mark_start = bottom(); 442 _next_marked_bytes = 0; 443 } 444 } 445 446 void HeapRegion::note_self_forwarding_removal_end(bool during_initial_mark, 447 bool during_conc_mark, 448 size_t marked_bytes) { 449 assert(0 <= marked_bytes && marked_bytes <= used(), 450 err_msg("marked: "SIZE_FORMAT" used: "SIZE_FORMAT, 451 marked_bytes, used())); 452 _prev_marked_bytes = marked_bytes; 453 } 454 455 HeapWord* 456 HeapRegion::object_iterate_mem_careful(MemRegion mr, 457 ObjectClosure* cl) { 458 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 459 // We used to use "block_start_careful" here. But we're actually happy 460 // to update the BOT while we do this... 461 HeapWord* cur = block_start(mr.start()); 462 mr = mr.intersection(used_region()); 463 if (mr.is_empty()) return NULL; 464 // Otherwise, find the obj that extends onto mr.start(). 465 466 assert(cur <= mr.start() 467 && (oop(cur)->klass_or_null() == NULL || 468 cur + oop(cur)->size() > mr.start()), 469 "postcondition of block_start"); 470 oop obj; 471 while (cur < mr.end()) { 472 obj = oop(cur); 473 if (obj->klass_or_null() == NULL) { 474 // Ran into an unparseable point. 475 return cur; 476 } else if (!g1h->is_obj_dead(obj)) { 477 cl->do_object(obj); 478 } 479 if (cl->abort()) return cur; 480 // The check above must occur before the operation below, since an 481 // abort might invalidate the "size" operation. 482 cur += obj->size(); 483 } 484 return NULL; 485 } 486 487 HeapWord* 488 HeapRegion:: 489 oops_on_card_seq_iterate_careful(MemRegion mr, 490 FilterOutOfRegionClosure* cl, 491 bool filter_young, 492 jbyte* card_ptr) { 493 // Currently, we should only have to clean the card if filter_young 494 // is true and vice versa. 495 if (filter_young) { 496 assert(card_ptr != NULL, "pre-condition"); 497 } else { 498 assert(card_ptr == NULL, "pre-condition"); 499 } 500 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 501 502 // If we're within a stop-world GC, then we might look at a card in a 503 // GC alloc region that extends onto a GC LAB, which may not be 504 // parseable. Stop such at the "saved_mark" of the region. 505 if (g1h->is_gc_active()) { 506 mr = mr.intersection(used_region_at_save_marks()); 507 } else { 508 mr = mr.intersection(used_region()); 509 } 510 if (mr.is_empty()) return NULL; 511 // Otherwise, find the obj that extends onto mr.start(). 512 513 // The intersection of the incoming mr (for the card) and the 514 // allocated part of the region is non-empty. This implies that 515 // we have actually allocated into this region. The code in 516 // G1CollectedHeap.cpp that allocates a new region sets the 517 // is_young tag on the region before allocating. Thus we 518 // safely know if this region is young. 519 if (is_young() && filter_young) { 520 return NULL; 521 } 522 523 assert(!is_young(), "check value of filter_young"); 524 525 // We can only clean the card here, after we make the decision that 526 // the card is not young. And we only clean the card if we have been 527 // asked to (i.e., card_ptr != NULL). 528 if (card_ptr != NULL) { 529 *card_ptr = CardTableModRefBS::clean_card_val(); 530 // We must complete this write before we do any of the reads below. 531 OrderAccess::storeload(); 532 } 533 534 // Cache the boundaries of the memory region in some const locals 535 HeapWord* const start = mr.start(); 536 HeapWord* const end = mr.end(); 537 538 // We used to use "block_start_careful" here. But we're actually happy 539 // to update the BOT while we do this... 540 HeapWord* cur = block_start(start); 541 assert(cur <= start, "Postcondition"); 542 543 oop obj; 544 545 HeapWord* next = cur; 546 while (next <= start) { 547 cur = next; 548 obj = oop(cur); 549 if (obj->klass_or_null() == NULL) { 550 // Ran into an unparseable point. 551 return cur; 552 } 553 // Otherwise... 554 next = (cur + obj->size()); 555 } 556 557 // If we finish the above loop...We have a parseable object that 558 // begins on or before the start of the memory region, and ends 559 // inside or spans the entire region. 560 561 assert(obj == oop(cur), "sanity"); 562 assert(cur <= start && 563 obj->klass_or_null() != NULL && 564 (cur + obj->size()) > start, 565 "Loop postcondition"); 566 567 if (!g1h->is_obj_dead(obj)) { 568 obj->oop_iterate(cl, mr); 569 } 570 571 while (cur < end) { 572 obj = oop(cur); 573 if (obj->klass_or_null() == NULL) { 574 // Ran into an unparseable point. 575 return cur; 576 }; 577 578 // Otherwise: 579 next = (cur + obj->size()); 580 581 if (!g1h->is_obj_dead(obj)) { 582 if (next < end || !obj->is_objArray()) { 583 // This object either does not span the MemRegion 584 // boundary, or if it does it's not an array. 585 // Apply closure to whole object. 586 obj->oop_iterate(cl); 587 } else { 588 // This obj is an array that spans the boundary. 589 // Stop at the boundary. 590 obj->oop_iterate(cl, mr); 591 } 592 } 593 cur = next; 594 } 595 return NULL; 596 } 597 598 // Code roots support 599 600 void HeapRegion::add_strong_code_root(nmethod* nm) { 601 HeapRegionRemSet* hrrs = rem_set(); 602 hrrs->add_strong_code_root(nm); 603 } 604 605 void HeapRegion::remove_strong_code_root(nmethod* nm) { 606 HeapRegionRemSet* hrrs = rem_set(); 607 hrrs->remove_strong_code_root(nm); 608 } 609 610 void HeapRegion::migrate_strong_code_roots() { 611 assert(in_collection_set(), "only collection set regions"); 612 assert(!isHumongous(), "not humongous regions"); 613 614 HeapRegionRemSet* hrrs = rem_set(); 615 hrrs->migrate_strong_code_roots(); 616 } 617 618 void HeapRegion::strong_code_roots_do(CodeBlobClosure* blk) const { 619 HeapRegionRemSet* hrrs = rem_set(); 620 hrrs->strong_code_roots_do(blk); 621 } 622 623 class VerifyStrongCodeRootOopClosure: public OopClosure { 624 const HeapRegion* _hr; 625 nmethod* _nm; 626 bool _failures; 627 bool _has_oops_in_region; 628 629 template <class T> void do_oop_work(T* p) { 630 T heap_oop = oopDesc::load_heap_oop(p); 631 if (!oopDesc::is_null(heap_oop)) { 632 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 633 634 // Note: not all the oops embedded in the nmethod are in the 635 // current region. We only look at those which are. 636 if (_hr->is_in(obj)) { 637 // Object is in the region. Check that its less than top 638 if (_hr->top() <= (HeapWord*)obj) { 639 // Object is above top 640 gclog_or_tty->print_cr("Object "PTR_FORMAT" in region " 641 "["PTR_FORMAT", "PTR_FORMAT") is above " 642 "top "PTR_FORMAT, 643 obj, _hr->bottom(), _hr->end(), _hr->top()); 644 _failures = true; 645 return; 646 } 647 // Nmethod has at least one oop in the current region 648 _has_oops_in_region = true; 649 } 650 } 651 } 652 653 public: 654 VerifyStrongCodeRootOopClosure(const HeapRegion* hr, nmethod* nm): 655 _hr(hr), _failures(false), _has_oops_in_region(false) {} 656 657 void do_oop(narrowOop* p) { do_oop_work(p); } 658 void do_oop(oop* p) { do_oop_work(p); } 659 660 bool failures() { return _failures; } 661 bool has_oops_in_region() { return _has_oops_in_region; } 662 }; 663 664 class VerifyStrongCodeRootCodeBlobClosure: public CodeBlobClosure { 665 const HeapRegion* _hr; 666 bool _failures; 667 public: 668 VerifyStrongCodeRootCodeBlobClosure(const HeapRegion* hr) : 669 _hr(hr), _failures(false) {} 670 671 void do_code_blob(CodeBlob* cb) { 672 nmethod* nm = (cb == NULL) ? NULL : cb->as_nmethod_or_null(); 673 if (nm != NULL) { 674 // Verify that the nemthod is live 675 if (!nm->is_alive()) { 676 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] has dead nmethod " 677 PTR_FORMAT" in its strong code roots", 678 _hr->bottom(), _hr->end(), nm); 679 _failures = true; 680 } else { 681 VerifyStrongCodeRootOopClosure oop_cl(_hr, nm); 682 nm->oops_do(&oop_cl); 683 if (!oop_cl.has_oops_in_region()) { 684 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] has nmethod " 685 PTR_FORMAT" in its strong code roots " 686 "with no pointers into region", 687 _hr->bottom(), _hr->end(), nm); 688 _failures = true; 689 } else if (oop_cl.failures()) { 690 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] has other " 691 "failures for nmethod "PTR_FORMAT, 692 _hr->bottom(), _hr->end(), nm); 693 _failures = true; 694 } 695 } 696 } 697 } 698 699 bool failures() { return _failures; } 700 }; 701 702 void HeapRegion::verify_strong_code_roots(VerifyOption vo, bool* failures) const { 703 if (!G1VerifyHeapRegionCodeRoots) { 704 // We're not verifying code roots. 705 return; 706 } 707 if (vo == VerifyOption_G1UseMarkWord) { 708 // Marking verification during a full GC is performed after class 709 // unloading, code cache unloading, etc so the strong code roots 710 // attached to each heap region are in an inconsistent state. They won't 711 // be consistent until the strong code roots are rebuilt after the 712 // actual GC. Skip verifying the strong code roots in this particular 713 // time. 714 assert(VerifyDuringGC, "only way to get here"); 715 return; 716 } 717 718 HeapRegionRemSet* hrrs = rem_set(); 719 int strong_code_roots_length = hrrs->strong_code_roots_list_length(); 720 721 // if this region is empty then there should be no entries 722 // on its strong code root list 723 if (is_empty()) { 724 if (strong_code_roots_length > 0) { 725 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] is empty " 726 "but has "INT32_FORMAT" code root entries", 727 bottom(), end(), strong_code_roots_length); 728 *failures = true; 729 } 730 return; 731 } 732 733 // An H-region should have an empty strong code root list 734 if (isHumongous()) { 735 if (strong_code_roots_length > 0) { 736 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] is humongous " 737 "but has "INT32_FORMAT" code root entries", 738 bottom(), end(), strong_code_roots_length); 739 *failures = true; 740 } 741 return; 742 } 743 744 VerifyStrongCodeRootCodeBlobClosure cb_cl(this); 745 strong_code_roots_do(&cb_cl); 746 747 if (cb_cl.failures()) { 748 *failures = true; 749 } 750 } 751 752 void HeapRegion::print() const { print_on(gclog_or_tty); } 753 void HeapRegion::print_on(outputStream* st) const { 754 if (isHumongous()) { 755 if (startsHumongous()) 756 st->print(" HS"); 757 else 758 st->print(" HC"); 759 } else { 760 st->print(" "); 761 } 762 if (in_collection_set()) 763 st->print(" CS"); 764 else 765 st->print(" "); 766 if (is_young()) 767 st->print(is_survivor() ? " SU" : " Y "); 768 else 769 st->print(" "); 770 if (is_empty()) 771 st->print(" F"); 772 else 773 st->print(" "); 774 st->print(" TS %5d", _gc_time_stamp); 775 st->print(" PTAMS "PTR_FORMAT" NTAMS "PTR_FORMAT, 776 prev_top_at_mark_start(), next_top_at_mark_start()); 777 G1OffsetTableContigSpace::print_on(st); 778 } 779 780 class VerifyLiveClosure: public OopClosure { 781 private: 782 G1CollectedHeap* _g1h; 783 CardTableModRefBS* _bs; 784 oop _containing_obj; 785 bool _failures; 786 int _n_failures; 787 VerifyOption _vo; 788 public: 789 // _vo == UsePrevMarking -> use "prev" marking information, 790 // _vo == UseNextMarking -> use "next" marking information, 791 // _vo == UseMarkWord -> use mark word from object header. 792 VerifyLiveClosure(G1CollectedHeap* g1h, VerifyOption vo) : 793 _g1h(g1h), _bs(NULL), _containing_obj(NULL), 794 _failures(false), _n_failures(0), _vo(vo) 795 { 796 BarrierSet* bs = _g1h->barrier_set(); 797 if (bs->is_a(BarrierSet::CardTableModRef)) 798 _bs = (CardTableModRefBS*)bs; 799 } 800 801 void set_containing_obj(oop obj) { 802 _containing_obj = obj; 803 } 804 805 bool failures() { return _failures; } 806 int n_failures() { return _n_failures; } 807 808 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 809 virtual void do_oop( oop* p) { do_oop_work(p); } 810 811 void print_object(outputStream* out, oop obj) { 812 #ifdef PRODUCT 813 Klass* k = obj->klass(); 814 const char* class_name = InstanceKlass::cast(k)->external_name(); 815 out->print_cr("class name %s", class_name); 816 #else // PRODUCT 817 obj->print_on(out); 818 #endif // PRODUCT 819 } 820 821 template <class T> 822 void do_oop_work(T* p) { 823 assert(_containing_obj != NULL, "Precondition"); 824 assert(!_g1h->is_obj_dead_cond(_containing_obj, _vo), 825 "Precondition"); 826 T heap_oop = oopDesc::load_heap_oop(p); 827 if (!oopDesc::is_null(heap_oop)) { 828 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); 829 bool failed = false; 830 if (!_g1h->is_in_closed_subset(obj) || _g1h->is_obj_dead_cond(obj, _vo)) { 831 MutexLockerEx x(ParGCRareEvent_lock, 832 Mutex::_no_safepoint_check_flag); 833 834 if (!_failures) { 835 gclog_or_tty->print_cr(""); 836 gclog_or_tty->print_cr("----------"); 837 } 838 if (!_g1h->is_in_closed_subset(obj)) { 839 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p); 840 gclog_or_tty->print_cr("Field "PTR_FORMAT 841 " of live obj "PTR_FORMAT" in region " 842 "["PTR_FORMAT", "PTR_FORMAT")", 843 p, (void*) _containing_obj, 844 from->bottom(), from->end()); 845 print_object(gclog_or_tty, _containing_obj); 846 gclog_or_tty->print_cr("points to obj "PTR_FORMAT" not in the heap", 847 (void*) obj); 848 } else { 849 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p); 850 HeapRegion* to = _g1h->heap_region_containing((HeapWord*)obj); 851 gclog_or_tty->print_cr("Field "PTR_FORMAT 852 " of live obj "PTR_FORMAT" in region " 853 "["PTR_FORMAT", "PTR_FORMAT")", 854 p, (void*) _containing_obj, 855 from->bottom(), from->end()); 856 print_object(gclog_or_tty, _containing_obj); 857 gclog_or_tty->print_cr("points to dead obj "PTR_FORMAT" in region " 858 "["PTR_FORMAT", "PTR_FORMAT")", 859 (void*) obj, to->bottom(), to->end()); 860 print_object(gclog_or_tty, obj); 861 } 862 gclog_or_tty->print_cr("----------"); 863 gclog_or_tty->flush(); 864 _failures = true; 865 failed = true; 866 _n_failures++; 867 } 868 869 if (!_g1h->full_collection() || G1VerifyRSetsDuringFullGC) { 870 HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p); 871 HeapRegion* to = _g1h->heap_region_containing(obj); 872 if (from != NULL && to != NULL && 873 from != to && 874 !to->isHumongous()) { 875 jbyte cv_obj = *_bs->byte_for_const(_containing_obj); 876 jbyte cv_field = *_bs->byte_for_const(p); 877 const jbyte dirty = CardTableModRefBS::dirty_card_val(); 878 879 bool is_bad = !(from->is_young() 880 || to->rem_set()->contains_reference(p) 881 || !G1HRRSFlushLogBuffersOnVerify && // buffers were not flushed 882 (_containing_obj->is_objArray() ? 883 cv_field == dirty 884 : cv_obj == dirty || cv_field == dirty)); 885 if (is_bad) { 886 MutexLockerEx x(ParGCRareEvent_lock, 887 Mutex::_no_safepoint_check_flag); 888 889 if (!_failures) { 890 gclog_or_tty->print_cr(""); 891 gclog_or_tty->print_cr("----------"); 892 } 893 gclog_or_tty->print_cr("Missing rem set entry:"); 894 gclog_or_tty->print_cr("Field "PTR_FORMAT" " 895 "of obj "PTR_FORMAT", " 896 "in region "HR_FORMAT, 897 p, (void*) _containing_obj, 898 HR_FORMAT_PARAMS(from)); 899 _containing_obj->print_on(gclog_or_tty); 900 gclog_or_tty->print_cr("points to obj "PTR_FORMAT" " 901 "in region "HR_FORMAT, 902 (void*) obj, 903 HR_FORMAT_PARAMS(to)); 904 obj->print_on(gclog_or_tty); 905 gclog_or_tty->print_cr("Obj head CTE = %d, field CTE = %d.", 906 cv_obj, cv_field); 907 gclog_or_tty->print_cr("----------"); 908 gclog_or_tty->flush(); 909 _failures = true; 910 if (!failed) _n_failures++; 911 } 912 } 913 } 914 } 915 } 916 }; 917 918 // This really ought to be commoned up into OffsetTableContigSpace somehow. 919 // We would need a mechanism to make that code skip dead objects. 920 921 void HeapRegion::verify(VerifyOption vo, 922 bool* failures) const { 923 G1CollectedHeap* g1 = G1CollectedHeap::heap(); 924 *failures = false; 925 HeapWord* p = bottom(); 926 HeapWord* prev_p = NULL; 927 VerifyLiveClosure vl_cl(g1, vo); 928 bool is_humongous = isHumongous(); 929 bool do_bot_verify = !is_young(); 930 size_t object_num = 0; 931 while (p < top()) { 932 oop obj = oop(p); 933 size_t obj_size = obj->size(); 934 object_num += 1; 935 936 if (is_humongous != g1->isHumongous(obj_size)) { 937 gclog_or_tty->print_cr("obj "PTR_FORMAT" is of %shumongous size (" 938 SIZE_FORMAT" words) in a %shumongous region", 939 p, g1->isHumongous(obj_size) ? "" : "non-", 940 obj_size, is_humongous ? "" : "non-"); 941 *failures = true; 942 return; 943 } 944 945 // If it returns false, verify_for_object() will output the 946 // appropriate messasge. 947 if (do_bot_verify && !_offsets.verify_for_object(p, obj_size)) { 948 *failures = true; 949 return; 950 } 951 952 if (!g1->is_obj_dead_cond(obj, this, vo)) { 953 if (obj->is_oop()) { 954 Klass* klass = obj->klass(); 955 if (!klass->is_metaspace_object()) { 956 gclog_or_tty->print_cr("klass "PTR_FORMAT" of object "PTR_FORMAT" " 957 "not metadata", klass, obj); 958 *failures = true; 959 return; 960 } else if (!klass->is_klass()) { 961 gclog_or_tty->print_cr("klass "PTR_FORMAT" of object "PTR_FORMAT" " 962 "not a klass", klass, obj); 963 *failures = true; 964 return; 965 } else { 966 vl_cl.set_containing_obj(obj); 967 obj->oop_iterate_no_header(&vl_cl); 968 if (vl_cl.failures()) { 969 *failures = true; 970 } 971 if (G1MaxVerifyFailures >= 0 && 972 vl_cl.n_failures() >= G1MaxVerifyFailures) { 973 return; 974 } 975 } 976 } else { 977 gclog_or_tty->print_cr(PTR_FORMAT" no an oop", obj); 978 *failures = true; 979 return; 980 } 981 } 982 prev_p = p; 983 p += obj_size; 984 } 985 986 if (p != top()) { 987 gclog_or_tty->print_cr("end of last object "PTR_FORMAT" " 988 "does not match top "PTR_FORMAT, p, top()); 989 *failures = true; 990 return; 991 } 992 993 HeapWord* the_end = end(); 994 assert(p == top(), "it should still hold"); 995 // Do some extra BOT consistency checking for addresses in the 996 // range [top, end). BOT look-ups in this range should yield 997 // top. No point in doing that if top == end (there's nothing there). 998 if (p < the_end) { 999 // Look up top 1000 HeapWord* addr_1 = p; 1001 HeapWord* b_start_1 = _offsets.block_start_const(addr_1); 1002 if (b_start_1 != p) { 1003 gclog_or_tty->print_cr("BOT look up for top: "PTR_FORMAT" " 1004 " yielded "PTR_FORMAT", expecting "PTR_FORMAT, 1005 addr_1, b_start_1, p); 1006 *failures = true; 1007 return; 1008 } 1009 1010 // Look up top + 1 1011 HeapWord* addr_2 = p + 1; 1012 if (addr_2 < the_end) { 1013 HeapWord* b_start_2 = _offsets.block_start_const(addr_2); 1014 if (b_start_2 != p) { 1015 gclog_or_tty->print_cr("BOT look up for top + 1: "PTR_FORMAT" " 1016 " yielded "PTR_FORMAT", expecting "PTR_FORMAT, 1017 addr_2, b_start_2, p); 1018 *failures = true; 1019 return; 1020 } 1021 } 1022 1023 // Look up an address between top and end 1024 size_t diff = pointer_delta(the_end, p) / 2; 1025 HeapWord* addr_3 = p + diff; 1026 if (addr_3 < the_end) { 1027 HeapWord* b_start_3 = _offsets.block_start_const(addr_3); 1028 if (b_start_3 != p) { 1029 gclog_or_tty->print_cr("BOT look up for top + diff: "PTR_FORMAT" " 1030 " yielded "PTR_FORMAT", expecting "PTR_FORMAT, 1031 addr_3, b_start_3, p); 1032 *failures = true; 1033 return; 1034 } 1035 } 1036 1037 // Loook up end - 1 1038 HeapWord* addr_4 = the_end - 1; 1039 HeapWord* b_start_4 = _offsets.block_start_const(addr_4); 1040 if (b_start_4 != p) { 1041 gclog_or_tty->print_cr("BOT look up for end - 1: "PTR_FORMAT" " 1042 " yielded "PTR_FORMAT", expecting "PTR_FORMAT, 1043 addr_4, b_start_4, p); 1044 *failures = true; 1045 return; 1046 } 1047 } 1048 1049 if (is_humongous && object_num > 1) { 1050 gclog_or_tty->print_cr("region ["PTR_FORMAT","PTR_FORMAT"] is humongous " 1051 "but has "SIZE_FORMAT", objects", 1052 bottom(), end(), object_num); 1053 *failures = true; 1054 return; 1055 } 1056 1057 verify_strong_code_roots(vo, failures); 1058 } 1059 1060 void HeapRegion::verify() const { 1061 bool dummy = false; 1062 verify(VerifyOption_G1UsePrevMarking, /* failures */ &dummy); 1063 } 1064 1065 // G1OffsetTableContigSpace code; copied from space.cpp. Hope this can go 1066 // away eventually. 1067 1068 void G1OffsetTableContigSpace::clear(bool mangle_space) { 1069 ContiguousSpace::clear(mangle_space); 1070 _offsets.zero_bottom_entry(); 1071 _offsets.initialize_threshold(); 1072 } 1073 1074 void G1OffsetTableContigSpace::set_bottom(HeapWord* new_bottom) { 1075 Space::set_bottom(new_bottom); 1076 _offsets.set_bottom(new_bottom); 1077 } 1078 1079 void G1OffsetTableContigSpace::set_end(HeapWord* new_end) { 1080 Space::set_end(new_end); 1081 _offsets.resize(new_end - bottom()); 1082 } 1083 1084 void G1OffsetTableContigSpace::print() const { 1085 print_short(); 1086 gclog_or_tty->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " 1087 INTPTR_FORMAT ", " INTPTR_FORMAT ")", 1088 bottom(), top(), _offsets.threshold(), end()); 1089 } 1090 1091 HeapWord* G1OffsetTableContigSpace::initialize_threshold() { 1092 return _offsets.initialize_threshold(); 1093 } 1094 1095 HeapWord* G1OffsetTableContigSpace::cross_threshold(HeapWord* start, 1096 HeapWord* end) { 1097 _offsets.alloc_block(start, end); 1098 return _offsets.threshold(); 1099 } 1100 1101 HeapWord* G1OffsetTableContigSpace::saved_mark_word() const { 1102 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 1103 assert( _gc_time_stamp <= g1h->get_gc_time_stamp(), "invariant" ); 1104 if (_gc_time_stamp < g1h->get_gc_time_stamp()) 1105 return top(); 1106 else 1107 return ContiguousSpace::saved_mark_word(); 1108 } 1109 1110 void G1OffsetTableContigSpace::set_saved_mark() { 1111 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 1112 unsigned curr_gc_time_stamp = g1h->get_gc_time_stamp(); 1113 1114 if (_gc_time_stamp < curr_gc_time_stamp) { 1115 // The order of these is important, as another thread might be 1116 // about to start scanning this region. If it does so after 1117 // set_saved_mark and before _gc_time_stamp = ..., then the latter 1118 // will be false, and it will pick up top() as the high water mark 1119 // of region. If it does so after _gc_time_stamp = ..., then it 1120 // will pick up the right saved_mark_word() as the high water mark 1121 // of the region. Either way, the behaviour will be correct. 1122 ContiguousSpace::set_saved_mark(); 1123 OrderAccess::storestore(); 1124 _gc_time_stamp = curr_gc_time_stamp; 1125 // No need to do another barrier to flush the writes above. If 1126 // this is called in parallel with other threads trying to 1127 // allocate into the region, the caller should call this while 1128 // holding a lock and when the lock is released the writes will be 1129 // flushed. 1130 } 1131 } 1132 1133 G1OffsetTableContigSpace:: 1134 G1OffsetTableContigSpace(G1BlockOffsetSharedArray* sharedOffsetArray, 1135 MemRegion mr) : 1136 _offsets(sharedOffsetArray, mr), 1137 _par_alloc_lock(Mutex::leaf, "OffsetTableContigSpace par alloc lock", true), 1138 _gc_time_stamp(0) 1139 { 1140 _offsets.set_space(this); 1141 // false ==> we'll do the clearing if there's clearing to be done. 1142 ContiguousSpace::initialize(mr, false, SpaceDecorator::Mangle); 1143 _offsets.zero_bottom_entry(); 1144 _offsets.initialize_threshold(); 1145 }