1 /* 2 * Copyright (c) 1997, 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 "classfile/systemDictionary.hpp" 27 #include "classfile/vmSymbols.hpp" 28 #include "gc_implementation/shared/liveRange.hpp" 29 #include "gc_implementation/shared/markSweep.hpp" 30 #include "gc_implementation/shared/spaceDecorator.hpp" 31 #include "memory/blockOffsetTable.inline.hpp" 32 #include "memory/defNewGeneration.hpp" 33 #include "memory/genCollectedHeap.hpp" 34 #include "memory/space.hpp" 35 #include "memory/space.inline.hpp" 36 #include "memory/universe.inline.hpp" 37 #include "oops/oop.inline.hpp" 38 #include "oops/oop.inline2.hpp" 39 #include "runtime/java.hpp" 40 #include "runtime/prefetch.inline.hpp" 41 #include "runtime/orderAccess.inline.hpp" 42 #include "runtime/safepoint.hpp" 43 #include "utilities/copy.hpp" 44 #include "utilities/globalDefinitions.hpp" 45 #include "utilities/macros.hpp" 46 47 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC 48 49 HeapWord* DirtyCardToOopClosure::get_actual_top(HeapWord* top, 50 HeapWord* top_obj) { 51 if (top_obj != NULL) { 52 if (_sp->block_is_obj(top_obj)) { 53 if (_precision == CardTableModRefBS::ObjHeadPreciseArray) { 54 if (oop(top_obj)->is_objArray() || oop(top_obj)->is_typeArray()) { 55 // An arrayOop is starting on the dirty card - since we do exact 56 // store checks for objArrays we are done. 57 } else { 58 // Otherwise, it is possible that the object starting on the dirty 59 // card spans the entire card, and that the store happened on a 60 // later card. Figure out where the object ends. 61 // Use the block_size() method of the space over which 62 // the iteration is being done. That space (e.g. CMS) may have 63 // specific requirements on object sizes which will 64 // be reflected in the block_size() method. 65 top = top_obj + oop(top_obj)->size(); 66 } 67 } 68 } else { 69 top = top_obj; 70 } 71 } else { 72 assert(top == _sp->end(), "only case where top_obj == NULL"); 73 } 74 return top; 75 } 76 77 void DirtyCardToOopClosure::walk_mem_region(MemRegion mr, 78 HeapWord* bottom, 79 HeapWord* top) { 80 // 1. Blocks may or may not be objects. 81 // 2. Even when a block_is_obj(), it may not entirely 82 // occupy the block if the block quantum is larger than 83 // the object size. 84 // We can and should try to optimize by calling the non-MemRegion 85 // version of oop_iterate() for all but the extremal objects 86 // (for which we need to call the MemRegion version of 87 // oop_iterate()) To be done post-beta XXX 88 for (; bottom < top; bottom += _sp->block_size(bottom)) { 89 // As in the case of contiguous space above, we'd like to 90 // just use the value returned by oop_iterate to increment the 91 // current pointer; unfortunately, that won't work in CMS because 92 // we'd need an interface change (it seems) to have the space 93 // "adjust the object size" (for instance pad it up to its 94 // block alignment or minimum block size restrictions. XXX 95 if (_sp->block_is_obj(bottom) && 96 !_sp->obj_allocated_since_save_marks(oop(bottom))) { 97 oop(bottom)->oop_iterate(_cl, mr); 98 } 99 } 100 } 101 102 // We get called with "mr" representing the dirty region 103 // that we want to process. Because of imprecise marking, 104 // we may need to extend the incoming "mr" to the right, 105 // and scan more. However, because we may already have 106 // scanned some of that extended region, we may need to 107 // trim its right-end back some so we do not scan what 108 // we (or another worker thread) may already have scanned 109 // or planning to scan. 110 void DirtyCardToOopClosure::do_MemRegion(MemRegion mr) { 111 112 // Some collectors need to do special things whenever their dirty 113 // cards are processed. For instance, CMS must remember mutator updates 114 // (i.e. dirty cards) so as to re-scan mutated objects. 115 // Such work can be piggy-backed here on dirty card scanning, so as to make 116 // it slightly more efficient than doing a complete non-destructive pre-scan 117 // of the card table. 118 MemRegionClosure* pCl = _sp->preconsumptionDirtyCardClosure(); 119 if (pCl != NULL) { 120 pCl->do_MemRegion(mr); 121 } 122 123 HeapWord* bottom = mr.start(); 124 HeapWord* last = mr.last(); 125 HeapWord* top = mr.end(); 126 HeapWord* bottom_obj; 127 HeapWord* top_obj; 128 129 assert(_precision == CardTableModRefBS::ObjHeadPreciseArray || 130 _precision == CardTableModRefBS::Precise, 131 "Only ones we deal with for now."); 132 133 assert(_precision != CardTableModRefBS::ObjHeadPreciseArray || 134 _cl->idempotent() || _last_bottom == NULL || 135 top <= _last_bottom, 136 "Not decreasing"); 137 NOT_PRODUCT(_last_bottom = mr.start()); 138 139 bottom_obj = _sp->block_start(bottom); 140 top_obj = _sp->block_start(last); 141 142 assert(bottom_obj <= bottom, "just checking"); 143 assert(top_obj <= top, "just checking"); 144 145 // Given what we think is the top of the memory region and 146 // the start of the object at the top, get the actual 147 // value of the top. 148 top = get_actual_top(top, top_obj); 149 150 // If the previous call did some part of this region, don't redo. 151 if (_precision == CardTableModRefBS::ObjHeadPreciseArray && 152 _min_done != NULL && 153 _min_done < top) { 154 top = _min_done; 155 } 156 157 // Top may have been reset, and in fact may be below bottom, 158 // e.g. the dirty card region is entirely in a now free object 159 // -- something that could happen with a concurrent sweeper. 160 bottom = MIN2(bottom, top); 161 MemRegion extended_mr = MemRegion(bottom, top); 162 assert(bottom <= top && 163 (_precision != CardTableModRefBS::ObjHeadPreciseArray || 164 _min_done == NULL || 165 top <= _min_done), 166 "overlap!"); 167 168 // Walk the region if it is not empty; otherwise there is nothing to do. 169 if (!extended_mr.is_empty()) { 170 walk_mem_region(extended_mr, bottom_obj, top); 171 } 172 173 // An idempotent closure might be applied in any order, so we don't 174 // record a _min_done for it. 175 if (!_cl->idempotent()) { 176 _min_done = bottom; 177 } else { 178 assert(_min_done == _last_explicit_min_done, 179 "Don't update _min_done for idempotent cl"); 180 } 181 } 182 183 DirtyCardToOopClosure* Space::new_dcto_cl(ExtendedOopClosure* cl, 184 CardTableModRefBS::PrecisionStyle precision, 185 HeapWord* boundary) { 186 return new DirtyCardToOopClosure(this, cl, precision, boundary); 187 } 188 189 HeapWord* ContiguousSpaceDCTOC::get_actual_top(HeapWord* top, 190 HeapWord* top_obj) { 191 if (top_obj != NULL && top_obj < (_sp->toContiguousSpace())->top()) { 192 if (_precision == CardTableModRefBS::ObjHeadPreciseArray) { 193 if (oop(top_obj)->is_objArray() || oop(top_obj)->is_typeArray()) { 194 // An arrayOop is starting on the dirty card - since we do exact 195 // store checks for objArrays we are done. 196 } else { 197 // Otherwise, it is possible that the object starting on the dirty 198 // card spans the entire card, and that the store happened on a 199 // later card. Figure out where the object ends. 200 assert(_sp->block_size(top_obj) == (size_t) oop(top_obj)->size(), 201 "Block size and object size mismatch"); 202 top = top_obj + oop(top_obj)->size(); 203 } 204 } 205 } else { 206 top = (_sp->toContiguousSpace())->top(); 207 } 208 return top; 209 } 210 211 void Filtering_DCTOC::walk_mem_region(MemRegion mr, 212 HeapWord* bottom, 213 HeapWord* top) { 214 // Note that this assumption won't hold if we have a concurrent 215 // collector in this space, which may have freed up objects after 216 // they were dirtied and before the stop-the-world GC that is 217 // examining cards here. 218 assert(bottom < top, "ought to be at least one obj on a dirty card."); 219 220 if (_boundary != NULL) { 221 // We have a boundary outside of which we don't want to look 222 // at objects, so create a filtering closure around the 223 // oop closure before walking the region. 224 FilteringClosure filter(_boundary, _cl); 225 walk_mem_region_with_cl(mr, bottom, top, &filter); 226 } else { 227 // No boundary, simply walk the heap with the oop closure. 228 walk_mem_region_with_cl(mr, bottom, top, _cl); 229 } 230 231 } 232 233 // We must replicate this so that the static type of "FilteringClosure" 234 // (see above) is apparent at the oop_iterate calls. 235 #define ContiguousSpaceDCTOC__walk_mem_region_with_cl_DEFN(ClosureType) \ 236 void ContiguousSpaceDCTOC::walk_mem_region_with_cl(MemRegion mr, \ 237 HeapWord* bottom, \ 238 HeapWord* top, \ 239 ClosureType* cl) { \ 240 bottom += oop(bottom)->oop_iterate(cl, mr); \ 241 if (bottom < top) { \ 242 HeapWord* next_obj = bottom + oop(bottom)->size(); \ 243 while (next_obj < top) { \ 244 /* Bottom lies entirely below top, so we can call the */ \ 245 /* non-memRegion version of oop_iterate below. */ \ 246 oop(bottom)->oop_iterate(cl); \ 247 bottom = next_obj; \ 248 next_obj = bottom + oop(bottom)->size(); \ 249 } \ 250 /* Last object. */ \ 251 oop(bottom)->oop_iterate(cl, mr); \ 252 } \ 253 } 254 255 // (There are only two of these, rather than N, because the split is due 256 // only to the introduction of the FilteringClosure, a local part of the 257 // impl of this abstraction.) 258 ContiguousSpaceDCTOC__walk_mem_region_with_cl_DEFN(ExtendedOopClosure) 259 ContiguousSpaceDCTOC__walk_mem_region_with_cl_DEFN(FilteringClosure) 260 261 DirtyCardToOopClosure* 262 ContiguousSpace::new_dcto_cl(ExtendedOopClosure* cl, 263 CardTableModRefBS::PrecisionStyle precision, 264 HeapWord* boundary) { 265 return new ContiguousSpaceDCTOC(this, cl, precision, boundary); 266 } 267 268 void Space::initialize(MemRegion mr, 269 bool clear_space, 270 bool mangle_space) { 271 HeapWord* bottom = mr.start(); 272 HeapWord* end = mr.end(); 273 assert(Universe::on_page_boundary(bottom) && Universe::on_page_boundary(end), 274 "invalid space boundaries"); 275 set_bottom(bottom); 276 set_end(end); 277 if (clear_space) clear(mangle_space); 278 } 279 280 void Space::clear(bool mangle_space) { 281 if (ZapUnusedHeapArea && mangle_space) { 282 mangle_unused_area(); 283 } 284 } 285 286 ContiguousSpace::ContiguousSpace(): CompactibleSpace(), _top(NULL), 287 _concurrent_iteration_safe_limit(NULL) { 288 _mangler = new GenSpaceMangler(this); 289 } 290 291 ContiguousSpace::~ContiguousSpace() { 292 delete _mangler; 293 } 294 295 void ContiguousSpace::initialize(MemRegion mr, 296 bool clear_space, 297 bool mangle_space) 298 { 299 CompactibleSpace::initialize(mr, clear_space, mangle_space); 300 set_concurrent_iteration_safe_limit(top()); 301 } 302 303 void ContiguousSpace::clear(bool mangle_space) { 304 set_top(bottom()); 305 set_saved_mark(); 306 CompactibleSpace::clear(mangle_space); 307 } 308 309 bool ContiguousSpace::is_free_block(const HeapWord* p) const { 310 return p >= _top; 311 } 312 313 void OffsetTableContigSpace::clear(bool mangle_space) { 314 ContiguousSpace::clear(mangle_space); 315 _offsets.initialize_threshold(); 316 } 317 318 void OffsetTableContigSpace::set_bottom(HeapWord* new_bottom) { 319 Space::set_bottom(new_bottom); 320 _offsets.set_bottom(new_bottom); 321 } 322 323 void OffsetTableContigSpace::set_end(HeapWord* new_end) { 324 // Space should not advertise an increase in size 325 // until after the underlying offset table has been enlarged. 326 _offsets.resize(pointer_delta(new_end, bottom())); 327 Space::set_end(new_end); 328 } 329 330 #ifndef PRODUCT 331 332 void ContiguousSpace::set_top_for_allocations(HeapWord* v) { 333 mangler()->set_top_for_allocations(v); 334 } 335 void ContiguousSpace::set_top_for_allocations() { 336 mangler()->set_top_for_allocations(top()); 337 } 338 void ContiguousSpace::check_mangled_unused_area(HeapWord* limit) { 339 mangler()->check_mangled_unused_area(limit); 340 } 341 342 void ContiguousSpace::check_mangled_unused_area_complete() { 343 mangler()->check_mangled_unused_area_complete(); 344 } 345 346 // Mangled only the unused space that has not previously 347 // been mangled and that has not been allocated since being 348 // mangled. 349 void ContiguousSpace::mangle_unused_area() { 350 mangler()->mangle_unused_area(); 351 } 352 void ContiguousSpace::mangle_unused_area_complete() { 353 mangler()->mangle_unused_area_complete(); 354 } 355 void ContiguousSpace::mangle_region(MemRegion mr) { 356 // Although this method uses SpaceMangler::mangle_region() which 357 // is not specific to a space, the when the ContiguousSpace version 358 // is called, it is always with regard to a space and this 359 // bounds checking is appropriate. 360 MemRegion space_mr(bottom(), end()); 361 assert(space_mr.contains(mr), "Mangling outside space"); 362 SpaceMangler::mangle_region(mr); 363 } 364 #endif // NOT_PRODUCT 365 366 void CompactibleSpace::initialize(MemRegion mr, 367 bool clear_space, 368 bool mangle_space) { 369 Space::initialize(mr, clear_space, mangle_space); 370 set_compaction_top(bottom()); 371 _next_compaction_space = NULL; 372 } 373 374 void CompactibleSpace::clear(bool mangle_space) { 375 Space::clear(mangle_space); 376 _compaction_top = bottom(); 377 } 378 379 HeapWord* CompactibleSpace::forward(oop q, size_t size, 380 CompactPoint* cp, HeapWord* compact_top) { 381 // q is alive 382 // First check if we should switch compaction space 383 assert(this == cp->space, "'this' should be current compaction space."); 384 size_t compaction_max_size = pointer_delta(end(), compact_top); 385 while (size > compaction_max_size) { 386 // switch to next compaction space 387 cp->space->set_compaction_top(compact_top); 388 cp->space = cp->space->next_compaction_space(); 389 if (cp->space == NULL) { 390 cp->gen = GenCollectedHeap::heap()->prev_gen(cp->gen); 391 assert(cp->gen != NULL, "compaction must succeed"); 392 cp->space = cp->gen->first_compaction_space(); 393 assert(cp->space != NULL, "generation must have a first compaction space"); 394 } 395 compact_top = cp->space->bottom(); 396 cp->space->set_compaction_top(compact_top); 397 cp->threshold = cp->space->initialize_threshold(); 398 compaction_max_size = pointer_delta(cp->space->end(), compact_top); 399 } 400 401 // store the forwarding pointer into the mark word 402 if ((HeapWord*)q != compact_top) { 403 q->forward_to(oop(compact_top)); 404 assert(q->is_gc_marked(), "encoding the pointer should preserve the mark"); 405 } else { 406 // if the object isn't moving we can just set the mark to the default 407 // mark and handle it specially later on. 408 q->init_mark(); 409 assert(q->forwardee() == NULL, "should be forwarded to NULL"); 410 } 411 412 compact_top += size; 413 414 // we need to update the offset table so that the beginnings of objects can be 415 // found during scavenge. Note that we are updating the offset table based on 416 // where the object will be once the compaction phase finishes. 417 if (compact_top > cp->threshold) 418 cp->threshold = 419 cp->space->cross_threshold(compact_top - size, compact_top); 420 return compact_top; 421 } 422 423 424 bool CompactibleSpace::insert_deadspace(size_t& allowed_deadspace_words, 425 HeapWord* q, size_t deadlength) { 426 if (allowed_deadspace_words >= deadlength) { 427 allowed_deadspace_words -= deadlength; 428 CollectedHeap::fill_with_object(q, deadlength); 429 oop(q)->set_mark(oop(q)->mark()->set_marked()); 430 assert((int) deadlength == oop(q)->size(), "bad filler object size"); 431 // Recall that we required "q == compaction_top". 432 return true; 433 } else { 434 allowed_deadspace_words = 0; 435 return false; 436 } 437 } 438 439 #define block_is_always_obj(q) true 440 #define obj_size(q) oop(q)->size() 441 #define adjust_obj_size(s) s 442 443 void CompactibleSpace::prepare_for_compaction(CompactPoint* cp) { 444 SCAN_AND_FORWARD(cp, end, block_is_obj, block_size); 445 } 446 447 // Faster object search. 448 void ContiguousSpace::prepare_for_compaction(CompactPoint* cp) { 449 SCAN_AND_FORWARD(cp, top, block_is_always_obj, obj_size); 450 } 451 452 void Space::adjust_pointers() { 453 // adjust all the interior pointers to point at the new locations of objects 454 // Used by MarkSweep::mark_sweep_phase3() 455 456 // First check to see if there is any work to be done. 457 if (used() == 0) { 458 return; // Nothing to do. 459 } 460 461 // Otherwise... 462 HeapWord* q = bottom(); 463 HeapWord* t = end(); 464 465 debug_only(HeapWord* prev_q = NULL); 466 while (q < t) { 467 if (oop(q)->is_gc_marked()) { 468 // q is alive 469 470 // point all the oops to the new location 471 size_t size = oop(q)->adjust_pointers(); 472 473 debug_only(prev_q = q); 474 475 q += size; 476 } else { 477 // q is not a live object. But we're not in a compactible space, 478 // So we don't have live ranges. 479 debug_only(prev_q = q); 480 q += block_size(q); 481 assert(q > prev_q, "we should be moving forward through memory"); 482 } 483 } 484 assert(q == t, "just checking"); 485 } 486 487 void CompactibleSpace::adjust_pointers() { 488 // Check first is there is any work to do. 489 if (used() == 0) { 490 return; // Nothing to do. 491 } 492 493 SCAN_AND_ADJUST_POINTERS(adjust_obj_size); 494 } 495 496 void CompactibleSpace::compact() { 497 SCAN_AND_COMPACT(obj_size); 498 } 499 500 void Space::print_short() const { print_short_on(tty); } 501 502 void Space::print_short_on(outputStream* st) const { 503 st->print(" space " SIZE_FORMAT "K, %3d%% used", capacity() / K, 504 (int) ((double) used() * 100 / capacity())); 505 } 506 507 void Space::print() const { print_on(tty); } 508 509 void Space::print_on(outputStream* st) const { 510 print_short_on(st); 511 st->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ")", 512 bottom(), end()); 513 } 514 515 void ContiguousSpace::print_on(outputStream* st) const { 516 print_short_on(st); 517 st->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")", 518 bottom(), top(), end()); 519 } 520 521 void OffsetTableContigSpace::print_on(outputStream* st) const { 522 print_short_on(st); 523 st->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " 524 INTPTR_FORMAT ", " INTPTR_FORMAT ")", 525 bottom(), top(), _offsets.threshold(), end()); 526 } 527 528 void ContiguousSpace::verify() const { 529 HeapWord* p = bottom(); 530 HeapWord* t = top(); 531 HeapWord* prev_p = NULL; 532 while (p < t) { 533 oop(p)->verify(); 534 prev_p = p; 535 p += oop(p)->size(); 536 } 537 guarantee(p == top(), "end of last object must match end of space"); 538 if (top() != end()) { 539 guarantee(top() == block_start_const(end()-1) && 540 top() == block_start_const(top()), 541 "top should be start of unallocated block, if it exists"); 542 } 543 } 544 545 void Space::oop_iterate(ExtendedOopClosure* blk) { 546 ObjectToOopClosure blk2(blk); 547 object_iterate(&blk2); 548 } 549 550 bool Space::obj_is_alive(const HeapWord* p) const { 551 assert (block_is_obj(p), "The address should point to an object"); 552 return true; 553 } 554 555 #if INCLUDE_ALL_GCS 556 #define ContigSpace_PAR_OOP_ITERATE_DEFN(OopClosureType, nv_suffix) \ 557 \ 558 void ContiguousSpace::par_oop_iterate(MemRegion mr, OopClosureType* blk) {\ 559 HeapWord* obj_addr = mr.start(); \ 560 HeapWord* t = mr.end(); \ 561 while (obj_addr < t) { \ 562 assert(oop(obj_addr)->is_oop(), "Should be an oop"); \ 563 obj_addr += oop(obj_addr)->oop_iterate(blk); \ 564 } \ 565 } 566 567 ALL_PAR_OOP_ITERATE_CLOSURES(ContigSpace_PAR_OOP_ITERATE_DEFN) 568 569 #undef ContigSpace_PAR_OOP_ITERATE_DEFN 570 #endif // INCLUDE_ALL_GCS 571 572 void ContiguousSpace::oop_iterate(ExtendedOopClosure* blk) { 573 if (is_empty()) return; 574 HeapWord* obj_addr = bottom(); 575 HeapWord* t = top(); 576 // Could call objects iterate, but this is easier. 577 while (obj_addr < t) { 578 obj_addr += oop(obj_addr)->oop_iterate(blk); 579 } 580 } 581 582 void ContiguousSpace::object_iterate(ObjectClosure* blk) { 583 if (is_empty()) return; 584 WaterMark bm = bottom_mark(); 585 object_iterate_from(bm, blk); 586 } 587 588 // For a ContiguousSpace object_iterate() and safe_object_iterate() 589 // are the same. 590 void ContiguousSpace::safe_object_iterate(ObjectClosure* blk) { 591 object_iterate(blk); 592 } 593 594 void ContiguousSpace::object_iterate_from(WaterMark mark, ObjectClosure* blk) { 595 assert(mark.space() == this, "Mark does not match space"); 596 HeapWord* p = mark.point(); 597 while (p < top()) { 598 blk->do_object(oop(p)); 599 p += oop(p)->size(); 600 } 601 } 602 603 HeapWord* 604 ContiguousSpace::object_iterate_careful(ObjectClosureCareful* blk) { 605 HeapWord * limit = concurrent_iteration_safe_limit(); 606 assert(limit <= top(), "sanity check"); 607 for (HeapWord* p = bottom(); p < limit;) { 608 size_t size = blk->do_object_careful(oop(p)); 609 if (size == 0) { 610 return p; // failed at p 611 } else { 612 p += size; 613 } 614 } 615 return NULL; // all done 616 } 617 618 #define ContigSpace_OOP_SINCE_SAVE_MARKS_DEFN(OopClosureType, nv_suffix) \ 619 \ 620 void ContiguousSpace:: \ 621 oop_since_save_marks_iterate##nv_suffix(OopClosureType* blk) { \ 622 HeapWord* t; \ 623 HeapWord* p = saved_mark_word(); \ 624 assert(p != NULL, "expected saved mark"); \ 625 \ 626 const intx interval = PrefetchScanIntervalInBytes; \ 627 do { \ 628 t = top(); \ 629 while (p < t) { \ 630 Prefetch::write(p, interval); \ 631 debug_only(HeapWord* prev = p); \ 632 oop m = oop(p); \ 633 p += m->oop_iterate(blk); \ 634 } \ 635 } while (t < top()); \ 636 \ 637 set_saved_mark_word(p); \ 638 } 639 640 ALL_SINCE_SAVE_MARKS_CLOSURES(ContigSpace_OOP_SINCE_SAVE_MARKS_DEFN) 641 642 #undef ContigSpace_OOP_SINCE_SAVE_MARKS_DEFN 643 644 // Very general, slow implementation. 645 HeapWord* ContiguousSpace::block_start_const(const void* p) const { 646 assert(MemRegion(bottom(), end()).contains(p), 647 err_msg("p (" PTR_FORMAT ") not in space [" PTR_FORMAT ", " PTR_FORMAT ")", 648 p, bottom(), end())); 649 if (p >= top()) { 650 return top(); 651 } else { 652 HeapWord* last = bottom(); 653 HeapWord* cur = last; 654 while (cur <= p) { 655 last = cur; 656 cur += oop(cur)->size(); 657 } 658 assert(oop(last)->is_oop(), 659 err_msg(PTR_FORMAT " should be an object start", last)); 660 return last; 661 } 662 } 663 664 size_t ContiguousSpace::block_size(const HeapWord* p) const { 665 assert(MemRegion(bottom(), end()).contains(p), 666 err_msg("p (" PTR_FORMAT ") not in space [" PTR_FORMAT ", " PTR_FORMAT ")", 667 p, bottom(), end())); 668 HeapWord* current_top = top(); 669 assert(p <= current_top, 670 err_msg("p > current top - p: " PTR_FORMAT ", current top: " PTR_FORMAT, 671 p, current_top)); 672 assert(p == current_top || oop(p)->is_oop(), 673 err_msg("p (" PTR_FORMAT ") is not a block start - " 674 "current_top: " PTR_FORMAT ", is_oop: %s", 675 p, current_top, BOOL_TO_STR(oop(p)->is_oop()))); 676 if (p < current_top) { 677 return oop(p)->size(); 678 } else { 679 assert(p == current_top, "just checking"); 680 return pointer_delta(end(), (HeapWord*) p); 681 } 682 } 683 684 // This version requires locking. 685 inline HeapWord* ContiguousSpace::allocate_impl(size_t size, 686 HeapWord* const end_value) { 687 assert(Heap_lock->owned_by_self() || 688 (SafepointSynchronize::is_at_safepoint() && Thread::current()->is_VM_thread()), 689 "not locked"); 690 HeapWord* obj = top(); 691 if (pointer_delta(end_value, obj) >= size) { 692 HeapWord* new_top = obj + size; 693 set_top(new_top); 694 assert(is_aligned(obj) && is_aligned(new_top), "checking alignment"); 695 return obj; 696 } else { 697 return NULL; 698 } 699 } 700 701 // This version is lock-free. 702 inline HeapWord* ContiguousSpace::par_allocate_impl(size_t size, 703 HeapWord* const end_value) { 704 do { 705 HeapWord* obj = top(); 706 if (pointer_delta(end_value, obj) >= size) { 707 HeapWord* new_top = obj + size; 708 HeapWord* result = (HeapWord*)Atomic::cmpxchg_ptr(new_top, top_addr(), obj); 709 // result can be one of two: 710 // the old top value: the exchange succeeded 711 // otherwise: the new value of the top is returned. 712 if (result == obj) { 713 assert(is_aligned(obj) && is_aligned(new_top), "checking alignment"); 714 return obj; 715 } 716 } else { 717 return NULL; 718 } 719 } while (true); 720 } 721 722 // Requires locking. 723 HeapWord* ContiguousSpace::allocate(size_t size) { 724 return allocate_impl(size, end()); 725 } 726 727 // Lock-free. 728 HeapWord* ContiguousSpace::par_allocate(size_t size) { 729 return par_allocate_impl(size, end()); 730 } 731 732 void ContiguousSpace::allocate_temporary_filler(int factor) { 733 // allocate temporary type array decreasing free size with factor 'factor' 734 assert(factor >= 0, "just checking"); 735 size_t size = pointer_delta(end(), top()); 736 737 // if space is full, return 738 if (size == 0) return; 739 740 if (factor > 0) { 741 size -= size/factor; 742 } 743 size = align_object_size(size); 744 745 const size_t array_header_size = typeArrayOopDesc::header_size(T_INT); 746 if (size >= (size_t)align_object_size(array_header_size)) { 747 size_t length = (size - array_header_size) * (HeapWordSize / sizeof(jint)); 748 // allocate uninitialized int array 749 typeArrayOop t = (typeArrayOop) allocate(size); 750 assert(t != NULL, "allocation should succeed"); 751 t->set_mark(markOopDesc::prototype()); 752 t->set_klass(Universe::intArrayKlassObj()); 753 t->set_length((int)length); 754 } else { 755 assert(size == CollectedHeap::min_fill_size(), 756 "size for smallest fake object doesn't match"); 757 instanceOop obj = (instanceOop) allocate(size); 758 obj->set_mark(markOopDesc::prototype()); 759 obj->set_klass_gap(0); 760 obj->set_klass(SystemDictionary::Object_klass()); 761 } 762 } 763 764 void EdenSpace::clear(bool mangle_space) { 765 ContiguousSpace::clear(mangle_space); 766 set_soft_end(end()); 767 } 768 769 // Requires locking. 770 HeapWord* EdenSpace::allocate(size_t size) { 771 return allocate_impl(size, soft_end()); 772 } 773 774 // Lock-free. 775 HeapWord* EdenSpace::par_allocate(size_t size) { 776 return par_allocate_impl(size, soft_end()); 777 } 778 779 HeapWord* ConcEdenSpace::par_allocate(size_t size) 780 { 781 do { 782 // The invariant is top() should be read before end() because 783 // top() can't be greater than end(), so if an update of _soft_end 784 // occurs between 'end_val = end();' and 'top_val = top();' top() 785 // also can grow up to the new end() and the condition 786 // 'top_val > end_val' is true. To ensure the loading order 787 // OrderAccess::loadload() is required after top() read. 788 HeapWord* obj = top(); 789 OrderAccess::loadload(); 790 if (pointer_delta(*soft_end_addr(), obj) >= size) { 791 HeapWord* new_top = obj + size; 792 HeapWord* result = (HeapWord*)Atomic::cmpxchg_ptr(new_top, top_addr(), obj); 793 // result can be one of two: 794 // the old top value: the exchange succeeded 795 // otherwise: the new value of the top is returned. 796 if (result == obj) { 797 assert(is_aligned(obj) && is_aligned(new_top), "checking alignment"); 798 return obj; 799 } 800 } else { 801 return NULL; 802 } 803 } while (true); 804 } 805 806 807 HeapWord* OffsetTableContigSpace::initialize_threshold() { 808 return _offsets.initialize_threshold(); 809 } 810 811 HeapWord* OffsetTableContigSpace::cross_threshold(HeapWord* start, HeapWord* end) { 812 _offsets.alloc_block(start, end); 813 return _offsets.threshold(); 814 } 815 816 OffsetTableContigSpace::OffsetTableContigSpace(BlockOffsetSharedArray* sharedOffsetArray, 817 MemRegion mr) : 818 _offsets(sharedOffsetArray, mr), 819 _par_alloc_lock(Mutex::leaf, "OffsetTableContigSpace par alloc lock", true) 820 { 821 _offsets.set_contig_space(this); 822 initialize(mr, SpaceDecorator::Clear, SpaceDecorator::Mangle); 823 } 824 825 #define OBJ_SAMPLE_INTERVAL 0 826 #define BLOCK_SAMPLE_INTERVAL 100 827 828 void OffsetTableContigSpace::verify() const { 829 HeapWord* p = bottom(); 830 HeapWord* prev_p = NULL; 831 int objs = 0; 832 int blocks = 0; 833 834 if (VerifyObjectStartArray) { 835 _offsets.verify(); 836 } 837 838 while (p < top()) { 839 size_t size = oop(p)->size(); 840 // For a sampling of objects in the space, find it using the 841 // block offset table. 842 if (blocks == BLOCK_SAMPLE_INTERVAL) { 843 guarantee(p == block_start_const(p + (size/2)), 844 "check offset computation"); 845 blocks = 0; 846 } else { 847 blocks++; 848 } 849 850 if (objs == OBJ_SAMPLE_INTERVAL) { 851 oop(p)->verify(); 852 objs = 0; 853 } else { 854 objs++; 855 } 856 prev_p = p; 857 p += size; 858 } 859 guarantee(p == top(), "end of last object must match end of space"); 860 } 861 862 863 size_t TenuredSpace::allowed_dead_ratio() const { 864 return MarkSweepDeadRatio; 865 }