1 /* 2 * Copyright (c) 1997, 2015, 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 "gc_interface/collectedHeap.inline.hpp" 32 #include "memory/blockOffsetTable.inline.hpp" 33 #include "memory/defNewGeneration.hpp" 34 #include "memory/genCollectedHeap.hpp" 35 #include "memory/space.hpp" 36 #include "memory/space.inline.hpp" 37 #include "memory/universe.inline.hpp" 38 #include "oops/oop.inline.hpp" 39 #include "runtime/java.hpp" 40 #include "runtime/atomic.inline.hpp" 41 #include "runtime/prefetch.inline.hpp" 42 #include "runtime/orderAccess.inline.hpp" 43 #include "runtime/safepoint.hpp" 44 #include "utilities/copy.hpp" 45 #include "utilities/globalDefinitions.hpp" 46 #include "utilities/macros.hpp" 47 48 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC 49 50 HeapWord* DirtyCardToOopClosure::get_actual_top(HeapWord* top, 51 HeapWord* top_obj) { 52 if (top_obj != NULL) { 53 if (_sp->block_is_obj(top_obj)) { 54 if (_precision == CardTableModRefBS::ObjHeadPreciseArray) { 55 if (oop(top_obj)->is_objArray() || oop(top_obj)->is_typeArray()) { 56 // An arrayOop is starting on the dirty card - since we do exact 57 // store checks for objArrays we are done. 58 } else { 59 // Otherwise, it is possible that the object starting on the dirty 60 // card spans the entire card, and that the store happened on a 61 // later card. Figure out where the object ends. 62 // Use the block_size() method of the space over which 63 // the iteration is being done. That space (e.g. CMS) may have 64 // specific requirements on object sizes which will 65 // be reflected in the block_size() method. 66 top = top_obj + oop(top_obj)->size(); 67 } 68 } 69 } else { 70 top = top_obj; 71 } 72 } else { 73 assert(top == _sp->end(), "only case where top_obj == NULL"); 74 } 75 return top; 76 } 77 78 void DirtyCardToOopClosure::walk_mem_region(MemRegion mr, 79 HeapWord* bottom, 80 HeapWord* top) { 81 // 1. Blocks may or may not be objects. 82 // 2. Even when a block_is_obj(), it may not entirely 83 // occupy the block if the block quantum is larger than 84 // the object size. 85 // We can and should try to optimize by calling the non-MemRegion 86 // version of oop_iterate() for all but the extremal objects 87 // (for which we need to call the MemRegion version of 88 // oop_iterate()) To be done post-beta XXX 89 for (; bottom < top; bottom += _sp->block_size(bottom)) { 90 // As in the case of contiguous space above, we'd like to 91 // just use the value returned by oop_iterate to increment the 92 // current pointer; unfortunately, that won't work in CMS because 93 // we'd need an interface change (it seems) to have the space 94 // "adjust the object size" (for instance pad it up to its 95 // block alignment or minimum block size restrictions. XXX 96 if (_sp->block_is_obj(bottom) && 97 !_sp->obj_allocated_since_save_marks(oop(bottom))) { 98 oop(bottom)->oop_iterate(_cl, mr); 99 } 100 } 101 } 102 103 // We get called with "mr" representing the dirty region 104 // that we want to process. Because of imprecise marking, 105 // we may need to extend the incoming "mr" to the right, 106 // and scan more. However, because we may already have 107 // scanned some of that extended region, we may need to 108 // trim its right-end back some so we do not scan what 109 // we (or another worker thread) may already have scanned 110 // or planning to scan. 111 void DirtyCardToOopClosure::do_MemRegion(MemRegion mr) { 112 113 // Some collectors need to do special things whenever their dirty 114 // cards are processed. For instance, CMS must remember mutator updates 115 // (i.e. dirty cards) so as to re-scan mutated objects. 116 // Such work can be piggy-backed here on dirty card scanning, so as to make 117 // it slightly more efficient than doing a complete non-destructive pre-scan 118 // of the card table. 119 MemRegionClosure* pCl = _sp->preconsumptionDirtyCardClosure(); 120 if (pCl != NULL) { 121 pCl->do_MemRegion(mr); 122 } 123 124 HeapWord* bottom = mr.start(); 125 HeapWord* last = mr.last(); 126 HeapWord* top = mr.end(); 127 HeapWord* bottom_obj; 128 HeapWord* top_obj; 129 130 assert(_precision == CardTableModRefBS::ObjHeadPreciseArray || 131 _precision == CardTableModRefBS::Precise, 132 "Only ones we deal with for now."); 133 134 assert(_precision != CardTableModRefBS::ObjHeadPreciseArray || 135 _cl->idempotent() || _last_bottom == NULL || 136 top <= _last_bottom, 137 "Not decreasing"); 138 NOT_PRODUCT(_last_bottom = mr.start()); 139 140 bottom_obj = _sp->block_start(bottom); 141 top_obj = _sp->block_start(last); 142 143 assert(bottom_obj <= bottom, "just checking"); 144 assert(top_obj <= top, "just checking"); 145 146 // Given what we think is the top of the memory region and 147 // the start of the object at the top, get the actual 148 // value of the top. 149 top = get_actual_top(top, top_obj); 150 151 // If the previous call did some part of this region, don't redo. 152 if (_precision == CardTableModRefBS::ObjHeadPreciseArray && 153 _min_done != NULL && 154 _min_done < top) { 155 top = _min_done; 156 } 157 158 // Top may have been reset, and in fact may be below bottom, 159 // e.g. the dirty card region is entirely in a now free object 160 // -- something that could happen with a concurrent sweeper. 161 bottom = MIN2(bottom, top); 162 MemRegion extended_mr = MemRegion(bottom, top); 163 assert(bottom <= top && 164 (_precision != CardTableModRefBS::ObjHeadPreciseArray || 165 _min_done == NULL || 166 top <= _min_done), 167 "overlap!"); 168 169 // Walk the region if it is not empty; otherwise there is nothing to do. 170 if (!extended_mr.is_empty()) { 171 walk_mem_region(extended_mr, bottom_obj, top); 172 } 173 174 // An idempotent closure might be applied in any order, so we don't 175 // record a _min_done for it. 176 if (!_cl->idempotent()) { 177 _min_done = bottom; 178 } else { 179 assert(_min_done == _last_explicit_min_done, 180 "Don't update _min_done for idempotent cl"); 181 } 182 } 183 184 DirtyCardToOopClosure* Space::new_dcto_cl(ExtendedOopClosure* cl, 185 CardTableModRefBS::PrecisionStyle precision, 186 HeapWord* boundary) { 187 return new DirtyCardToOopClosure(this, cl, precision, boundary); 188 } 189 190 HeapWord* ContiguousSpaceDCTOC::get_actual_top(HeapWord* top, 191 HeapWord* top_obj) { 192 if (top_obj != NULL && top_obj < (_sp->toContiguousSpace())->top()) { 193 if (_precision == CardTableModRefBS::ObjHeadPreciseArray) { 194 if (oop(top_obj)->is_objArray() || oop(top_obj)->is_typeArray()) { 195 // An arrayOop is starting on the dirty card - since we do exact 196 // store checks for objArrays we are done. 197 } else { 198 // Otherwise, it is possible that the object starting on the dirty 199 // card spans the entire card, and that the store happened on a 200 // later card. Figure out where the object ends. 201 assert(_sp->block_size(top_obj) == (size_t) oop(top_obj)->size(), 202 "Block size and object size mismatch"); 203 top = top_obj + oop(top_obj)->size(); 204 } 205 } 206 } else { 207 top = (_sp->toContiguousSpace())->top(); 208 } 209 return top; 210 } 211 212 void Filtering_DCTOC::walk_mem_region(MemRegion mr, 213 HeapWord* bottom, 214 HeapWord* top) { 215 // Note that this assumption won't hold if we have a concurrent 216 // collector in this space, which may have freed up objects after 217 // they were dirtied and before the stop-the-world GC that is 218 // examining cards here. 219 assert(bottom < top, "ought to be at least one obj on a dirty card."); 220 221 if (_boundary != NULL) { 222 // We have a boundary outside of which we don't want to look 223 // at objects, so create a filtering closure around the 224 // oop closure before walking the region. 225 FilteringClosure filter(_boundary, _cl); 226 walk_mem_region_with_cl(mr, bottom, top, &filter); 227 } else { 228 // No boundary, simply walk the heap with the oop closure. 229 walk_mem_region_with_cl(mr, bottom, top, _cl); 230 } 231 232 } 233 234 // We must replicate this so that the static type of "FilteringClosure" 235 // (see above) is apparent at the oop_iterate calls. 236 #define ContiguousSpaceDCTOC__walk_mem_region_with_cl_DEFN(ClosureType) \ 237 void ContiguousSpaceDCTOC::walk_mem_region_with_cl(MemRegion mr, \ 238 HeapWord* bottom, \ 239 HeapWord* top, \ 240 ClosureType* cl) { \ 241 bottom += oop(bottom)->oop_iterate(cl, mr); \ 242 if (bottom < top) { \ 243 HeapWord* next_obj = bottom + oop(bottom)->size(); \ 244 while (next_obj < top) { \ 245 /* Bottom lies entirely below top, so we can call the */ \ 246 /* non-memRegion version of oop_iterate below. */ \ 247 oop(bottom)->oop_iterate(cl); \ 248 bottom = next_obj; \ 249 next_obj = bottom + oop(bottom)->size(); \ 250 } \ 251 /* Last object. */ \ 252 oop(bottom)->oop_iterate(cl, mr); \ 253 } \ 254 } 255 256 // (There are only two of these, rather than N, because the split is due 257 // only to the introduction of the FilteringClosure, a local part of the 258 // impl of this abstraction.) 259 ContiguousSpaceDCTOC__walk_mem_region_with_cl_DEFN(ExtendedOopClosure) 260 ContiguousSpaceDCTOC__walk_mem_region_with_cl_DEFN(FilteringClosure) 261 262 DirtyCardToOopClosure* 263 ContiguousSpace::new_dcto_cl(ExtendedOopClosure* cl, 264 CardTableModRefBS::PrecisionStyle precision, 265 HeapWord* boundary) { 266 return new ContiguousSpaceDCTOC(this, cl, precision, boundary); 267 } 268 269 void Space::initialize(MemRegion mr, 270 bool clear_space, 271 bool mangle_space) { 272 HeapWord* bottom = mr.start(); 273 HeapWord* end = mr.end(); 274 assert(Universe::on_page_boundary(bottom) && Universe::on_page_boundary(end), 275 "invalid space boundaries"); 276 set_bottom(bottom); 277 set_end(end); 278 if (clear_space) clear(mangle_space); 279 } 280 281 void Space::clear(bool mangle_space) { 282 if (ZapUnusedHeapArea && mangle_space) { 283 mangle_unused_area(); 284 } 285 } 286 287 ContiguousSpace::ContiguousSpace(): CompactibleSpace(), _top(NULL), 288 _concurrent_iteration_safe_limit(NULL) { 289 _mangler = new GenSpaceMangler(this); 290 } 291 292 ContiguousSpace::~ContiguousSpace() { 293 delete _mangler; 294 } 295 296 void ContiguousSpace::initialize(MemRegion mr, 297 bool clear_space, 298 bool mangle_space) 299 { 300 CompactibleSpace::initialize(mr, clear_space, mangle_space); 301 set_concurrent_iteration_safe_limit(top()); 302 } 303 304 void ContiguousSpace::clear(bool mangle_space) { 305 set_top(bottom()); 306 set_saved_mark(); 307 CompactibleSpace::clear(mangle_space); 308 } 309 310 bool ContiguousSpace::is_free_block(const HeapWord* p) const { 311 return p >= _top; 312 } 313 314 void OffsetTableContigSpace::clear(bool mangle_space) { 315 ContiguousSpace::clear(mangle_space); 316 _offsets.initialize_threshold(); 317 } 318 319 void OffsetTableContigSpace::set_bottom(HeapWord* new_bottom) { 320 Space::set_bottom(new_bottom); 321 _offsets.set_bottom(new_bottom); 322 } 323 324 void OffsetTableContigSpace::set_end(HeapWord* new_end) { 325 // Space should not advertise an increase in size 326 // until after the underlying offset table has been enlarged. 327 _offsets.resize(pointer_delta(new_end, bottom())); 328 Space::set_end(new_end); 329 } 330 331 #ifndef PRODUCT 332 333 void ContiguousSpace::set_top_for_allocations(HeapWord* v) { 334 mangler()->set_top_for_allocations(v); 335 } 336 void ContiguousSpace::set_top_for_allocations() { 337 mangler()->set_top_for_allocations(top()); 338 } 339 void ContiguousSpace::check_mangled_unused_area(HeapWord* limit) { 340 mangler()->check_mangled_unused_area(limit); 341 } 342 343 void ContiguousSpace::check_mangled_unused_area_complete() { 344 mangler()->check_mangled_unused_area_complete(); 345 } 346 347 // Mangled only the unused space that has not previously 348 // been mangled and that has not been allocated since being 349 // mangled. 350 void ContiguousSpace::mangle_unused_area() { 351 mangler()->mangle_unused_area(); 352 } 353 void ContiguousSpace::mangle_unused_area_complete() { 354 mangler()->mangle_unused_area_complete(); 355 } 356 void ContiguousSpace::mangle_region(MemRegion mr) { 357 // Although this method uses SpaceMangler::mangle_region() which 358 // is not specific to a space, the when the ContiguousSpace version 359 // is called, it is always with regard to a space and this 360 // bounds checking is appropriate. 361 MemRegion space_mr(bottom(), end()); 362 assert(space_mr.contains(mr), "Mangling outside space"); 363 SpaceMangler::mangle_region(mr); 364 } 365 #endif // NOT_PRODUCT 366 367 void CompactibleSpace::initialize(MemRegion mr, 368 bool clear_space, 369 bool mangle_space) { 370 Space::initialize(mr, clear_space, mangle_space); 371 set_compaction_top(bottom()); 372 _next_compaction_space = NULL; 373 } 374 375 void CompactibleSpace::clear(bool mangle_space) { 376 Space::clear(mangle_space); 377 _compaction_top = bottom(); 378 } 379 380 HeapWord* CompactibleSpace::forward(oop q, size_t size, 381 CompactPoint* cp, HeapWord* compact_top) { 382 // q is alive 383 // First check if we should switch compaction space 384 assert(this == cp->space, "'this' should be current compaction space."); 385 size_t compaction_max_size = pointer_delta(end(), compact_top); 386 while (size > compaction_max_size) { 387 // switch to next compaction space 388 cp->space->set_compaction_top(compact_top); 389 cp->space = cp->space->next_compaction_space(); 390 if (cp->space == NULL) { 391 cp->gen = GenCollectedHeap::heap()->prev_gen(cp->gen); 392 assert(cp->gen != NULL, "compaction must succeed"); 393 cp->space = cp->gen->first_compaction_space(); 394 assert(cp->space != NULL, "generation must have a first compaction space"); 395 } 396 compact_top = cp->space->bottom(); 397 cp->space->set_compaction_top(compact_top); 398 cp->threshold = cp->space->initialize_threshold(); 399 compaction_max_size = pointer_delta(cp->space->end(), compact_top); 400 } 401 402 // store the forwarding pointer into the mark word 403 if ((HeapWord*)q != compact_top) { 404 q->forward_to(oop(compact_top)); 405 assert(q->is_gc_marked(), "encoding the pointer should preserve the mark"); 406 } else { 407 // if the object isn't moving we can just set the mark to the default 408 // mark and handle it specially later on. 409 q->init_mark(); 410 assert(q->forwardee() == NULL, "should be forwarded to NULL"); 411 } 412 413 compact_top += size; 414 415 // we need to update the offset table so that the beginnings of objects can be 416 // found during scavenge. Note that we are updating the offset table based on 417 // where the object will be once the compaction phase finishes. 418 if (compact_top > cp->threshold) 419 cp->threshold = 420 cp->space->cross_threshold(compact_top - size, compact_top); 421 return compact_top; 422 } 423 424 425 bool CompactibleSpace::insert_deadspace(size_t& allowed_deadspace_words, 426 HeapWord* q, size_t deadlength) { 427 if (allowed_deadspace_words >= deadlength) { 428 allowed_deadspace_words -= deadlength; 429 CollectedHeap::fill_with_object(q, deadlength); 430 oop(q)->set_mark(oop(q)->mark()->set_marked()); 431 assert((int) deadlength == oop(q)->size(), "bad filler object size"); 432 // Recall that we required "q == compaction_top". 433 return true; 434 } else { 435 allowed_deadspace_words = 0; 436 return false; 437 } 438 } 439 440 void ContiguousSpace::prepare_for_compaction(CompactPoint* cp) { 441 scan_and_forward(this, cp); 442 } 443 444 void CompactibleSpace::adjust_pointers() { 445 // Check first is there is any work to do. 446 if (used() == 0) { 447 return; // Nothing to do. 448 } 449 450 scan_and_adjust_pointers(this); 451 } 452 453 void CompactibleSpace::compact() { 454 scan_and_compact(this); 455 } 456 457 void Space::print_short() const { print_short_on(tty); } 458 459 void Space::print_short_on(outputStream* st) const { 460 st->print(" space " SIZE_FORMAT "K, %3d%% used", capacity() / K, 461 (int) ((double) used() * 100 / capacity())); 462 } 463 464 void Space::print() const { print_on(tty); } 465 466 void Space::print_on(outputStream* st) const { 467 print_short_on(st); 468 st->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ")", 469 bottom(), end()); 470 } 471 472 void ContiguousSpace::print_on(outputStream* st) const { 473 print_short_on(st); 474 st->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")", 475 bottom(), top(), end()); 476 } 477 478 void OffsetTableContigSpace::print_on(outputStream* st) const { 479 print_short_on(st); 480 st->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " 481 INTPTR_FORMAT ", " INTPTR_FORMAT ")", 482 bottom(), top(), _offsets.threshold(), end()); 483 } 484 485 void ContiguousSpace::verify() const { 486 HeapWord* p = bottom(); 487 HeapWord* t = top(); 488 HeapWord* prev_p = NULL; 489 while (p < t) { 490 oop(p)->verify(); 491 prev_p = p; 492 p += oop(p)->size(); 493 } 494 guarantee(p == top(), "end of last object must match end of space"); 495 if (top() != end()) { 496 guarantee(top() == block_start_const(end()-1) && 497 top() == block_start_const(top()), 498 "top should be start of unallocated block, if it exists"); 499 } 500 } 501 502 void Space::oop_iterate(ExtendedOopClosure* blk) { 503 ObjectToOopClosure blk2(blk); 504 object_iterate(&blk2); 505 } 506 507 bool Space::obj_is_alive(const HeapWord* p) const { 508 assert (block_is_obj(p), "The address should point to an object"); 509 return true; 510 } 511 512 #if INCLUDE_ALL_GCS 513 #define ContigSpace_PAR_OOP_ITERATE_DEFN(OopClosureType, nv_suffix) \ 514 \ 515 void ContiguousSpace::par_oop_iterate(MemRegion mr, OopClosureType* blk) {\ 516 HeapWord* obj_addr = mr.start(); \ 517 HeapWord* t = mr.end(); \ 518 while (obj_addr < t) { \ 519 assert(oop(obj_addr)->is_oop(), "Should be an oop"); \ 520 obj_addr += oop(obj_addr)->oop_iterate(blk); \ 521 } \ 522 } 523 524 ALL_PAR_OOP_ITERATE_CLOSURES(ContigSpace_PAR_OOP_ITERATE_DEFN) 525 526 #undef ContigSpace_PAR_OOP_ITERATE_DEFN 527 #endif // INCLUDE_ALL_GCS 528 529 void ContiguousSpace::oop_iterate(ExtendedOopClosure* blk) { 530 if (is_empty()) return; 531 HeapWord* obj_addr = bottom(); 532 HeapWord* t = top(); 533 // Could call objects iterate, but this is easier. 534 while (obj_addr < t) { 535 obj_addr += oop(obj_addr)->oop_iterate(blk); 536 } 537 } 538 539 void ContiguousSpace::object_iterate(ObjectClosure* blk) { 540 if (is_empty()) return; 541 WaterMark bm = bottom_mark(); 542 object_iterate_from(bm, blk); 543 } 544 545 // For a ContiguousSpace object_iterate() and safe_object_iterate() 546 // are the same. 547 void ContiguousSpace::safe_object_iterate(ObjectClosure* blk) { 548 object_iterate(blk); 549 } 550 551 void ContiguousSpace::object_iterate_from(WaterMark mark, ObjectClosure* blk) { 552 assert(mark.space() == this, "Mark does not match space"); 553 HeapWord* p = mark.point(); 554 while (p < top()) { 555 blk->do_object(oop(p)); 556 p += oop(p)->size(); 557 } 558 } 559 560 HeapWord* 561 ContiguousSpace::object_iterate_careful(ObjectClosureCareful* blk) { 562 HeapWord * limit = concurrent_iteration_safe_limit(); 563 assert(limit <= top(), "sanity check"); 564 for (HeapWord* p = bottom(); p < limit;) { 565 size_t size = blk->do_object_careful(oop(p)); 566 if (size == 0) { 567 return p; // failed at p 568 } else { 569 p += size; 570 } 571 } 572 return NULL; // all done 573 } 574 575 #define ContigSpace_OOP_SINCE_SAVE_MARKS_DEFN(OopClosureType, nv_suffix) \ 576 \ 577 void ContiguousSpace:: \ 578 oop_since_save_marks_iterate##nv_suffix(OopClosureType* blk) { \ 579 HeapWord* t; \ 580 HeapWord* p = saved_mark_word(); \ 581 assert(p != NULL, "expected saved mark"); \ 582 \ 583 const intx interval = PrefetchScanIntervalInBytes; \ 584 do { \ 585 t = top(); \ 586 while (p < t) { \ 587 Prefetch::write(p, interval); \ 588 debug_only(HeapWord* prev = p); \ 589 oop m = oop(p); \ 590 p += m->oop_iterate(blk); \ 591 } \ 592 } while (t < top()); \ 593 \ 594 set_saved_mark_word(p); \ 595 } 596 597 ALL_SINCE_SAVE_MARKS_CLOSURES(ContigSpace_OOP_SINCE_SAVE_MARKS_DEFN) 598 599 #undef ContigSpace_OOP_SINCE_SAVE_MARKS_DEFN 600 601 // Very general, slow implementation. 602 HeapWord* ContiguousSpace::block_start_const(const void* p) const { 603 assert(MemRegion(bottom(), end()).contains(p), 604 err_msg("p (" PTR_FORMAT ") not in space [" PTR_FORMAT ", " PTR_FORMAT ")", 605 p, bottom(), end())); 606 if (p >= top()) { 607 return top(); 608 } else { 609 HeapWord* last = bottom(); 610 HeapWord* cur = last; 611 while (cur <= p) { 612 last = cur; 613 cur += oop(cur)->size(); 614 } 615 assert(oop(last)->is_oop(), 616 err_msg(PTR_FORMAT " should be an object start", last)); 617 return last; 618 } 619 } 620 621 size_t ContiguousSpace::block_size(const HeapWord* p) const { 622 assert(MemRegion(bottom(), end()).contains(p), 623 err_msg("p (" PTR_FORMAT ") not in space [" PTR_FORMAT ", " PTR_FORMAT ")", 624 p, bottom(), end())); 625 HeapWord* current_top = top(); 626 assert(p <= current_top, 627 err_msg("p > current top - p: " PTR_FORMAT ", current top: " PTR_FORMAT, 628 p, current_top)); 629 assert(p == current_top || oop(p)->is_oop(), 630 err_msg("p (" PTR_FORMAT ") is not a block start - " 631 "current_top: " PTR_FORMAT ", is_oop: %s", 632 p, current_top, BOOL_TO_STR(oop(p)->is_oop()))); 633 if (p < current_top) { 634 return oop(p)->size(); 635 } else { 636 assert(p == current_top, "just checking"); 637 return pointer_delta(end(), (HeapWord*) p); 638 } 639 } 640 641 // This version requires locking. 642 inline HeapWord* ContiguousSpace::allocate_impl(size_t size) { 643 assert(Heap_lock->owned_by_self() || 644 (SafepointSynchronize::is_at_safepoint() && Thread::current()->is_VM_thread()), 645 "not locked"); 646 HeapWord* obj = top(); 647 if (pointer_delta(end(), obj) >= size) { 648 HeapWord* new_top = obj + size; 649 set_top(new_top); 650 assert(is_aligned(obj) && is_aligned(new_top), "checking alignment"); 651 return obj; 652 } else { 653 return NULL; 654 } 655 } 656 657 // This version is lock-free. 658 inline HeapWord* ContiguousSpace::par_allocate_impl(size_t size) { 659 do { 660 HeapWord* obj = top(); 661 if (pointer_delta(end(), obj) >= size) { 662 HeapWord* new_top = obj + size; 663 HeapWord* result = (HeapWord*)Atomic::cmpxchg_ptr(new_top, top_addr(), obj); 664 // result can be one of two: 665 // the old top value: the exchange succeeded 666 // otherwise: the new value of the top is returned. 667 if (result == obj) { 668 assert(is_aligned(obj) && is_aligned(new_top), "checking alignment"); 669 return obj; 670 } 671 } else { 672 return NULL; 673 } 674 } while (true); 675 } 676 677 HeapWord* ContiguousSpace::allocate_aligned(size_t size) { 678 assert(Heap_lock->owned_by_self() || (SafepointSynchronize::is_at_safepoint() && Thread::current()->is_VM_thread()), "not locked"); 679 HeapWord* end_value = end(); 680 681 HeapWord* obj = CollectedHeap::align_allocation_or_fail(top(), end_value, SurvivorAlignmentInBytes); 682 if (obj == NULL) { 683 return NULL; 684 } 685 686 if (pointer_delta(end_value, obj) >= size) { 687 HeapWord* new_top = obj + size; 688 set_top(new_top); 689 assert(is_ptr_aligned(obj, SurvivorAlignmentInBytes) && is_aligned(new_top), 690 "checking alignment"); 691 return obj; 692 } else { 693 set_top(obj); 694 return NULL; 695 } 696 } 697 698 // Requires locking. 699 HeapWord* ContiguousSpace::allocate(size_t size) { 700 return allocate_impl(size); 701 } 702 703 // Lock-free. 704 HeapWord* ContiguousSpace::par_allocate(size_t size) { 705 return par_allocate_impl(size); 706 } 707 708 void ContiguousSpace::allocate_temporary_filler(int factor) { 709 // allocate temporary type array decreasing free size with factor 'factor' 710 assert(factor >= 0, "just checking"); 711 size_t size = pointer_delta(end(), top()); 712 713 // if space is full, return 714 if (size == 0) return; 715 716 if (factor > 0) { 717 size -= size/factor; 718 } 719 size = align_object_size(size); 720 721 const size_t array_header_size = typeArrayOopDesc::header_size(T_INT); 722 if (size >= (size_t)align_object_size(array_header_size)) { 723 size_t length = (size - array_header_size) * (HeapWordSize / sizeof(jint)); 724 // allocate uninitialized int array 725 typeArrayOop t = (typeArrayOop) allocate(size); 726 assert(t != NULL, "allocation should succeed"); 727 t->set_mark(markOopDesc::prototype()); 728 t->set_klass(Universe::intArrayKlassObj()); 729 t->set_length((int)length); 730 } else { 731 assert(size == CollectedHeap::min_fill_size(), 732 "size for smallest fake object doesn't match"); 733 instanceOop obj = (instanceOop) allocate(size); 734 obj->set_mark(markOopDesc::prototype()); 735 obj->set_klass_gap(0); 736 obj->set_klass(SystemDictionary::Object_klass()); 737 } 738 } 739 740 HeapWord* OffsetTableContigSpace::initialize_threshold() { 741 return _offsets.initialize_threshold(); 742 } 743 744 HeapWord* OffsetTableContigSpace::cross_threshold(HeapWord* start, HeapWord* end) { 745 _offsets.alloc_block(start, end); 746 return _offsets.threshold(); 747 } 748 749 OffsetTableContigSpace::OffsetTableContigSpace(BlockOffsetSharedArray* sharedOffsetArray, 750 MemRegion mr) : 751 _offsets(sharedOffsetArray, mr), 752 _par_alloc_lock(Mutex::leaf, "OffsetTableContigSpace par alloc lock", true) 753 { 754 _offsets.set_contig_space(this); 755 initialize(mr, SpaceDecorator::Clear, SpaceDecorator::Mangle); 756 } 757 758 #define OBJ_SAMPLE_INTERVAL 0 759 #define BLOCK_SAMPLE_INTERVAL 100 760 761 void OffsetTableContigSpace::verify() const { 762 HeapWord* p = bottom(); 763 HeapWord* prev_p = NULL; 764 int objs = 0; 765 int blocks = 0; 766 767 if (VerifyObjectStartArray) { 768 _offsets.verify(); 769 } 770 771 while (p < top()) { 772 size_t size = oop(p)->size(); 773 // For a sampling of objects in the space, find it using the 774 // block offset table. 775 if (blocks == BLOCK_SAMPLE_INTERVAL) { 776 guarantee(p == block_start_const(p + (size/2)), 777 "check offset computation"); 778 blocks = 0; 779 } else { 780 blocks++; 781 } 782 783 if (objs == OBJ_SAMPLE_INTERVAL) { 784 oop(p)->verify(); 785 objs = 0; 786 } else { 787 objs++; 788 } 789 prev_p = p; 790 p += size; 791 } 792 guarantee(p == top(), "end of last object must match end of space"); 793 } 794 795 796 size_t TenuredSpace::allowed_dead_ratio() const { 797 return MarkSweepDeadRatio; 798 }