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/serial/defNewGeneration.hpp" 29 #include "gc/shared/blockOffsetTable.inline.hpp" 30 #include "gc/shared/collectedHeap.inline.hpp" 31 #include "gc/shared/genCollectedHeap.hpp" 32 #include "gc/shared/genOopClosures.inline.hpp" 33 #include "gc/shared/liveRange.hpp" 34 #include "gc/shared/space.hpp" 35 #include "gc/shared/space.inline.hpp" 36 #include "gc/shared/spaceDecorator.hpp" 37 #include "memory/universe.inline.hpp" 38 #include "oops/oop.inline.hpp" 39 #include "runtime/atomic.inline.hpp" 40 #include "runtime/java.hpp" 41 #include "runtime/orderAccess.inline.hpp" 42 #include "runtime/prefetch.inline.hpp" 43 #include "runtime/safepoint.hpp" 44 #include "utilities/copy.hpp" 45 #include "utilities/globalDefinitions.hpp" 46 #include "utilities/macros.hpp" 47 48 HeapWord* DirtyCardToOopClosure::get_actual_top(HeapWord* top, 49 HeapWord* top_obj) { 50 if (top_obj != NULL) { 51 if (_sp->block_is_obj(top_obj)) { 52 if (_precision == CardTableModRefBS::ObjHeadPreciseArray) { 53 if (oop(top_obj)->is_objArray() || oop(top_obj)->is_typeArray()) { 54 // An arrayOop is starting on the dirty card - since we do exact 55 // store checks for objArrays we are done. 56 } else { 57 // Otherwise, it is possible that the object starting on the dirty 58 // card spans the entire card, and that the store happened on a 59 // later card. Figure out where the object ends. 60 // Use the block_size() method of the space over which 61 // the iteration is being done. That space (e.g. CMS) may have 62 // specific requirements on object sizes which will 63 // be reflected in the block_size() method. 64 top = top_obj + oop(top_obj)->size(); 65 } 66 } 67 } else { 68 top = top_obj; 69 } 70 } else { 71 assert(top == _sp->end(), "only case where top_obj == NULL"); 72 } 73 return top; 74 } 75 76 void DirtyCardToOopClosure::walk_mem_region(MemRegion mr, 77 HeapWord* bottom, 78 HeapWord* top) { 79 // 1. Blocks may or may not be objects. 80 // 2. Even when a block_is_obj(), it may not entirely 81 // occupy the block if the block quantum is larger than 82 // the object size. 83 // We can and should try to optimize by calling the non-MemRegion 84 // version of oop_iterate() for all but the extremal objects 85 // (for which we need to call the MemRegion version of 86 // oop_iterate()) To be done post-beta XXX 87 for (; bottom < top; bottom += _sp->block_size(bottom)) { 88 // As in the case of contiguous space above, we'd like to 89 // just use the value returned by oop_iterate to increment the 90 // current pointer; unfortunately, that won't work in CMS because 91 // we'd need an interface change (it seems) to have the space 92 // "adjust the object size" (for instance pad it up to its 93 // block alignment or minimum block size restrictions. XXX 94 if (_sp->block_is_obj(bottom) && 95 !_sp->obj_allocated_since_save_marks(oop(bottom))) { 96 oop(bottom)->oop_iterate(_cl, mr); 97 } 98 } 99 } 100 101 // We get called with "mr" representing the dirty region 102 // that we want to process. Because of imprecise marking, 103 // we may need to extend the incoming "mr" to the right, 104 // and scan more. However, because we may already have 105 // scanned some of that extended region, we may need to 106 // trim its right-end back some so we do not scan what 107 // we (or another worker thread) may already have scanned 108 // or planning to scan. 109 void DirtyCardToOopClosure::do_MemRegion(MemRegion mr) { 110 111 // Some collectors need to do special things whenever their dirty 112 // cards are processed. For instance, CMS must remember mutator updates 113 // (i.e. dirty cards) so as to re-scan mutated objects. 114 // Such work can be piggy-backed here on dirty card scanning, so as to make 115 // it slightly more efficient than doing a complete non-destructive pre-scan 116 // of the card table. 117 MemRegionClosure* pCl = _sp->preconsumptionDirtyCardClosure(); 118 if (pCl != NULL) { 119 pCl->do_MemRegion(mr); 120 } 121 122 HeapWord* bottom = mr.start(); 123 HeapWord* last = mr.last(); 124 HeapWord* top = mr.end(); 125 HeapWord* bottom_obj; 126 HeapWord* top_obj; 127 128 assert(_precision == CardTableModRefBS::ObjHeadPreciseArray || 129 _precision == CardTableModRefBS::Precise, 130 "Only ones we deal with for now."); 131 132 assert(_precision != CardTableModRefBS::ObjHeadPreciseArray || 133 _cl->idempotent() || _last_bottom == NULL || 134 top <= _last_bottom, 135 "Not decreasing"); 136 NOT_PRODUCT(_last_bottom = mr.start()); 137 138 bottom_obj = _sp->block_start(bottom); 139 top_obj = _sp->block_start(last); 140 141 assert(bottom_obj <= bottom, "just checking"); 142 assert(top_obj <= top, "just checking"); 143 144 // Given what we think is the top of the memory region and 145 // the start of the object at the top, get the actual 146 // value of the top. 147 top = get_actual_top(top, top_obj); 148 149 // If the previous call did some part of this region, don't redo. 150 if (_precision == CardTableModRefBS::ObjHeadPreciseArray && 151 _min_done != NULL && 152 _min_done < top) { 153 top = _min_done; 154 } 155 156 // Top may have been reset, and in fact may be below bottom, 157 // e.g. the dirty card region is entirely in a now free object 158 // -- something that could happen with a concurrent sweeper. 159 bottom = MIN2(bottom, top); 160 MemRegion extended_mr = MemRegion(bottom, top); 161 assert(bottom <= top && 162 (_precision != CardTableModRefBS::ObjHeadPreciseArray || 163 _min_done == NULL || 164 top <= _min_done), 165 "overlap!"); 166 167 // Walk the region if it is not empty; otherwise there is nothing to do. 168 if (!extended_mr.is_empty()) { 169 walk_mem_region(extended_mr, bottom_obj, top); 170 } 171 172 // An idempotent closure might be applied in any order, so we don't 173 // record a _min_done for it. 174 if (!_cl->idempotent()) { 175 _min_done = bottom; 176 } else { 177 assert(_min_done == _last_explicit_min_done, 178 "Don't update _min_done for idempotent cl"); 179 } 180 } 181 182 DirtyCardToOopClosure* Space::new_dcto_cl(ExtendedOopClosure* cl, 183 CardTableModRefBS::PrecisionStyle precision, 184 HeapWord* boundary) { 185 return new DirtyCardToOopClosure(this, cl, precision, boundary); 186 } 187 188 HeapWord* ContiguousSpaceDCTOC::get_actual_top(HeapWord* top, 189 HeapWord* top_obj) { 190 if (top_obj != NULL && top_obj < (_sp->toContiguousSpace())->top()) { 191 if (_precision == CardTableModRefBS::ObjHeadPreciseArray) { 192 if (oop(top_obj)->is_objArray() || oop(top_obj)->is_typeArray()) { 193 // An arrayOop is starting on the dirty card - since we do exact 194 // store checks for objArrays we are done. 195 } else { 196 // Otherwise, it is possible that the object starting on the dirty 197 // card spans the entire card, and that the store happened on a 198 // later card. Figure out where the object ends. 199 assert(_sp->block_size(top_obj) == (size_t) oop(top_obj)->size(), 200 "Block size and object size mismatch"); 201 top = top_obj + oop(top_obj)->size(); 202 } 203 } 204 } else { 205 top = (_sp->toContiguousSpace())->top(); 206 } 207 return top; 208 } 209 210 void Filtering_DCTOC::walk_mem_region(MemRegion mr, 211 HeapWord* bottom, 212 HeapWord* top) { 213 // Note that this assumption won't hold if we have a concurrent 214 // collector in this space, which may have freed up objects after 215 // they were dirtied and before the stop-the-world GC that is 216 // examining cards here. 217 assert(bottom < top, "ought to be at least one obj on a dirty card."); 218 219 if (_boundary != NULL) { 220 // We have a boundary outside of which we don't want to look 221 // at objects, so create a filtering closure around the 222 // oop closure before walking the region. 223 FilteringClosure filter(_boundary, _cl); 224 walk_mem_region_with_cl(mr, bottom, top, &filter); 225 } else { 226 // No boundary, simply walk the heap with the oop closure. 227 walk_mem_region_with_cl(mr, bottom, top, _cl); 228 } 229 230 } 231 232 // We must replicate this so that the static type of "FilteringClosure" 233 // (see above) is apparent at the oop_iterate calls. 234 #define ContiguousSpaceDCTOC__walk_mem_region_with_cl_DEFN(ClosureType) \ 235 void ContiguousSpaceDCTOC::walk_mem_region_with_cl(MemRegion mr, \ 236 HeapWord* bottom, \ 237 HeapWord* top, \ 238 ClosureType* cl) { \ 239 bottom += oop(bottom)->oop_iterate(cl, mr); \ 240 if (bottom < top) { \ 241 HeapWord* next_obj = bottom + oop(bottom)->size(); \ 242 while (next_obj < top) { \ 243 /* Bottom lies entirely below top, so we can call the */ \ 244 /* non-memRegion version of oop_iterate below. */ \ 245 oop(bottom)->oop_iterate(cl); \ 246 bottom = next_obj; \ 247 next_obj = bottom + oop(bottom)->size(); \ 248 } \ 249 /* Last object. */ \ 250 oop(bottom)->oop_iterate(cl, mr); \ 251 } \ 252 } 253 254 // (There are only two of these, rather than N, because the split is due 255 // only to the introduction of the FilteringClosure, a local part of the 256 // impl of this abstraction.) 257 ContiguousSpaceDCTOC__walk_mem_region_with_cl_DEFN(ExtendedOopClosure) 258 ContiguousSpaceDCTOC__walk_mem_region_with_cl_DEFN(FilteringClosure) 259 260 DirtyCardToOopClosure* 261 ContiguousSpace::new_dcto_cl(ExtendedOopClosure* cl, 262 CardTableModRefBS::PrecisionStyle precision, 263 HeapWord* boundary) { 264 return new ContiguousSpaceDCTOC(this, cl, precision, boundary); 265 } 266 267 void Space::initialize(MemRegion mr, 268 bool clear_space, 269 bool mangle_space) { 270 HeapWord* bottom = mr.start(); 271 HeapWord* end = mr.end(); 272 assert(Universe::on_page_boundary(bottom) && Universe::on_page_boundary(end), 273 "invalid space boundaries"); 274 set_bottom(bottom); 275 set_end(end); 276 if (clear_space) clear(mangle_space); 277 } 278 279 void Space::clear(bool mangle_space) { 280 if (ZapUnusedHeapArea && mangle_space) { 281 mangle_unused_area(); 282 } 283 } 284 285 ContiguousSpace::ContiguousSpace(): CompactibleSpace(), _top(NULL), 286 _concurrent_iteration_safe_limit(NULL) { 287 _mangler = new GenSpaceMangler(this); 288 } 289 290 ContiguousSpace::~ContiguousSpace() { 291 delete _mangler; 292 } 293 294 void ContiguousSpace::initialize(MemRegion mr, 295 bool clear_space, 296 bool mangle_space) 297 { 298 CompactibleSpace::initialize(mr, clear_space, mangle_space); 299 set_concurrent_iteration_safe_limit(top()); 300 } 301 302 void ContiguousSpace::clear(bool mangle_space) { 303 set_top(bottom()); 304 set_saved_mark(); 305 CompactibleSpace::clear(mangle_space); 306 } 307 308 bool ContiguousSpace::is_free_block(const HeapWord* p) const { 309 return p >= _top; 310 } 311 312 void OffsetTableContigSpace::clear(bool mangle_space) { 313 ContiguousSpace::clear(mangle_space); 314 _offsets.initialize_threshold(); 315 } 316 317 void OffsetTableContigSpace::set_bottom(HeapWord* new_bottom) { 318 Space::set_bottom(new_bottom); 319 _offsets.set_bottom(new_bottom); 320 } 321 322 void OffsetTableContigSpace::set_end(HeapWord* new_end) { 323 // Space should not advertise an increase in size 324 // until after the underlying offset table has been enlarged. 325 _offsets.resize(pointer_delta(new_end, bottom())); 326 Space::set_end(new_end); 327 } 328 329 #ifndef PRODUCT 330 331 void ContiguousSpace::set_top_for_allocations(HeapWord* v) { 332 mangler()->set_top_for_allocations(v); 333 } 334 void ContiguousSpace::set_top_for_allocations() { 335 mangler()->set_top_for_allocations(top()); 336 } 337 void ContiguousSpace::check_mangled_unused_area(HeapWord* limit) { 338 mangler()->check_mangled_unused_area(limit); 339 } 340 341 void ContiguousSpace::check_mangled_unused_area_complete() { 342 mangler()->check_mangled_unused_area_complete(); 343 } 344 345 // Mangled only the unused space that has not previously 346 // been mangled and that has not been allocated since being 347 // mangled. 348 void ContiguousSpace::mangle_unused_area() { 349 mangler()->mangle_unused_area(); 350 } 351 void ContiguousSpace::mangle_unused_area_complete() { 352 mangler()->mangle_unused_area_complete(); 353 } 354 #endif // NOT_PRODUCT 355 356 void CompactibleSpace::initialize(MemRegion mr, 357 bool clear_space, 358 bool mangle_space) { 359 Space::initialize(mr, clear_space, mangle_space); 360 set_compaction_top(bottom()); 361 _next_compaction_space = NULL; 362 } 363 364 void CompactibleSpace::clear(bool mangle_space) { 365 Space::clear(mangle_space); 366 _compaction_top = bottom(); 367 } 368 369 HeapWord* CompactibleSpace::forward(oop q, size_t size, 370 CompactPoint* cp, HeapWord* compact_top) { 371 // q is alive 372 // First check if we should switch compaction space 373 assert(this == cp->space, "'this' should be current compaction space."); 374 size_t compaction_max_size = pointer_delta(end(), compact_top); 375 while (size > compaction_max_size) { 376 // switch to next compaction space 377 cp->space->set_compaction_top(compact_top); 378 cp->space = cp->space->next_compaction_space(); 379 if (cp->space == NULL) { 380 cp->gen = GenCollectedHeap::heap()->young_gen(); 381 assert(cp->gen != NULL, "compaction must succeed"); 382 cp->space = cp->gen->first_compaction_space(); 383 assert(cp->space != NULL, "generation must have a first compaction space"); 384 } 385 compact_top = cp->space->bottom(); 386 cp->space->set_compaction_top(compact_top); 387 cp->threshold = cp->space->initialize_threshold(); 388 compaction_max_size = pointer_delta(cp->space->end(), compact_top); 389 } 390 391 // store the forwarding pointer into the mark word 392 if ((HeapWord*)q != compact_top) { 393 q->forward_to(oop(compact_top)); 394 assert(q->is_gc_marked(), "encoding the pointer should preserve the mark"); 395 } else { 396 // if the object isn't moving we can just set the mark to the default 397 // mark and handle it specially later on. 398 q->init_mark(); 399 assert(q->forwardee() == NULL, "should be forwarded to NULL"); 400 } 401 402 compact_top += size; 403 404 // we need to update the offset table so that the beginnings of objects can be 405 // found during scavenge. Note that we are updating the offset table based on 406 // where the object will be once the compaction phase finishes. 407 if (compact_top > cp->threshold) 408 cp->threshold = 409 cp->space->cross_threshold(compact_top - size, compact_top); 410 return compact_top; 411 } 412 413 414 bool CompactibleSpace::insert_deadspace(size_t& allowed_deadspace_words, 415 HeapWord* q, size_t deadlength) { 416 if (allowed_deadspace_words >= deadlength) { 417 allowed_deadspace_words -= deadlength; 418 CollectedHeap::fill_with_object(q, deadlength); 419 oop(q)->set_mark(oop(q)->mark()->set_marked()); 420 assert((int) deadlength == oop(q)->size(), "bad filler object size"); 421 // Recall that we required "q == compaction_top". 422 return true; 423 } else { 424 allowed_deadspace_words = 0; 425 return false; 426 } 427 } 428 429 void ContiguousSpace::prepare_for_compaction(CompactPoint* cp) { 430 scan_and_forward(this, cp); 431 } 432 433 void CompactibleSpace::adjust_pointers() { 434 // Check first is there is any work to do. 435 if (used() == 0) { 436 return; // Nothing to do. 437 } 438 439 scan_and_adjust_pointers(this); 440 } 441 442 void CompactibleSpace::compact() { 443 scan_and_compact(this); 444 } 445 446 void Space::print_short() const { print_short_on(tty); } 447 448 void Space::print_short_on(outputStream* st) const { 449 st->print(" space " SIZE_FORMAT "K, %3d%% used", capacity() / K, 450 (int) ((double) used() * 100 / capacity())); 451 } 452 453 void Space::print() const { print_on(tty); } 454 455 void Space::print_on(outputStream* st) const { 456 print_short_on(st); 457 st->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ")", 458 p2i(bottom()), p2i(end())); 459 } 460 461 void ContiguousSpace::print_on(outputStream* st) const { 462 print_short_on(st); 463 st->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")", 464 p2i(bottom()), p2i(top()), p2i(end())); 465 } 466 467 void OffsetTableContigSpace::print_on(outputStream* st) const { 468 print_short_on(st); 469 st->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " 470 INTPTR_FORMAT ", " INTPTR_FORMAT ")", 471 p2i(bottom()), p2i(top()), p2i(_offsets.threshold()), p2i(end())); 472 } 473 474 void ContiguousSpace::verify() const { 475 HeapWord* p = bottom(); 476 HeapWord* t = top(); 477 HeapWord* prev_p = NULL; 478 while (p < t) { 479 oop(p)->verify(); 480 prev_p = p; 481 p += oop(p)->size(); 482 } 483 guarantee(p == top(), "end of last object must match end of space"); 484 if (top() != end()) { 485 guarantee(top() == block_start_const(end()-1) && 486 top() == block_start_const(top()), 487 "top should be start of unallocated block, if it exists"); 488 } 489 } 490 491 void Space::oop_iterate(ExtendedOopClosure* blk) { 492 ObjectToOopClosure blk2(blk); 493 object_iterate(&blk2); 494 } 495 496 bool Space::obj_is_alive(const HeapWord* p) const { 497 assert (block_is_obj(p), "The address should point to an object"); 498 return true; 499 } 500 501 #if INCLUDE_ALL_GCS 502 #define ContigSpace_PAR_OOP_ITERATE_DEFN(OopClosureType, nv_suffix) \ 503 \ 504 void ContiguousSpace::par_oop_iterate(MemRegion mr, OopClosureType* blk) {\ 505 HeapWord* obj_addr = mr.start(); \ 506 HeapWord* t = mr.end(); \ 507 while (obj_addr < t) { \ 508 assert(oop(obj_addr)->is_oop(), "Should be an oop"); \ 509 obj_addr += oop(obj_addr)->oop_iterate(blk); \ 510 } \ 511 } 512 513 ALL_PAR_OOP_ITERATE_CLOSURES(ContigSpace_PAR_OOP_ITERATE_DEFN) 514 515 #undef ContigSpace_PAR_OOP_ITERATE_DEFN 516 #endif // INCLUDE_ALL_GCS 517 518 void ContiguousSpace::oop_iterate(ExtendedOopClosure* blk) { 519 if (is_empty()) return; 520 HeapWord* obj_addr = bottom(); 521 HeapWord* t = top(); 522 // Could call objects iterate, but this is easier. 523 while (obj_addr < t) { 524 obj_addr += oop(obj_addr)->oop_iterate(blk); 525 } 526 } 527 528 void ContiguousSpace::object_iterate(ObjectClosure* blk) { 529 if (is_empty()) return; 530 WaterMark bm = bottom_mark(); 531 object_iterate_from(bm, blk); 532 } 533 534 // For a ContiguousSpace object_iterate() and safe_object_iterate() 535 // are the same. 536 void ContiguousSpace::safe_object_iterate(ObjectClosure* blk) { 537 object_iterate(blk); 538 } 539 540 void ContiguousSpace::object_iterate_from(WaterMark mark, ObjectClosure* blk) { 541 assert(mark.space() == this, "Mark does not match space"); 542 HeapWord* p = mark.point(); 543 while (p < top()) { 544 blk->do_object(oop(p)); 545 p += oop(p)->size(); 546 } 547 } 548 549 HeapWord* 550 ContiguousSpace::object_iterate_careful(ObjectClosureCareful* blk) { 551 HeapWord * limit = concurrent_iteration_safe_limit(); 552 assert(limit <= top(), "sanity check"); 553 for (HeapWord* p = bottom(); p < limit;) { 554 size_t size = blk->do_object_careful(oop(p)); 555 if (size == 0) { 556 return p; // failed at p 557 } else { 558 p += size; 559 } 560 } 561 return NULL; // all done 562 } 563 564 #define ContigSpace_OOP_SINCE_SAVE_MARKS_DEFN(OopClosureType, nv_suffix) \ 565 \ 566 void ContiguousSpace:: \ 567 oop_since_save_marks_iterate##nv_suffix(OopClosureType* blk) { \ 568 HeapWord* t; \ 569 HeapWord* p = saved_mark_word(); \ 570 assert(p != NULL, "expected saved mark"); \ 571 \ 572 const intx interval = PrefetchScanIntervalInBytes; \ 573 do { \ 574 t = top(); \ 575 while (p < t) { \ 576 Prefetch::write(p, interval); \ 577 debug_only(HeapWord* prev = p); \ 578 oop m = oop(p); \ 579 p += m->oop_iterate(blk); \ 580 } \ 581 } while (t < top()); \ 582 \ 583 set_saved_mark_word(p); \ 584 } 585 586 ALL_SINCE_SAVE_MARKS_CLOSURES(ContigSpace_OOP_SINCE_SAVE_MARKS_DEFN) 587 588 #undef ContigSpace_OOP_SINCE_SAVE_MARKS_DEFN 589 590 // Very general, slow implementation. 591 HeapWord* ContiguousSpace::block_start_const(const void* p) const { 592 assert(MemRegion(bottom(), end()).contains(p), 593 err_msg("p (" PTR_FORMAT ") not in space [" PTR_FORMAT ", " PTR_FORMAT ")", 594 p2i(p), p2i(bottom()), p2i(end()))); 595 if (p >= top()) { 596 return top(); 597 } else { 598 HeapWord* last = bottom(); 599 HeapWord* cur = last; 600 while (cur <= p) { 601 last = cur; 602 cur += oop(cur)->size(); 603 } 604 assert(oop(last)->is_oop(), 605 err_msg(PTR_FORMAT " should be an object start", p2i(last))); 606 return last; 607 } 608 } 609 610 size_t ContiguousSpace::block_size(const HeapWord* p) const { 611 assert(MemRegion(bottom(), end()).contains(p), 612 err_msg("p (" PTR_FORMAT ") not in space [" PTR_FORMAT ", " PTR_FORMAT ")", 613 p2i(p), p2i(bottom()), p2i(end()))); 614 HeapWord* current_top = top(); 615 assert(p <= current_top, 616 err_msg("p > current top - p: " PTR_FORMAT ", current top: " PTR_FORMAT, 617 p2i(p), p2i(current_top))); 618 assert(p == current_top || oop(p)->is_oop(), 619 err_msg("p (" PTR_FORMAT ") is not a block start - " 620 "current_top: " PTR_FORMAT ", is_oop: %s", 621 p2i(p), p2i(current_top), BOOL_TO_STR(oop(p)->is_oop()))); 622 if (p < current_top) { 623 return oop(p)->size(); 624 } else { 625 assert(p == current_top, "just checking"); 626 return pointer_delta(end(), (HeapWord*) p); 627 } 628 } 629 630 // This version requires locking. 631 inline HeapWord* ContiguousSpace::allocate_impl(size_t size) { 632 assert(Heap_lock->owned_by_self() || 633 (SafepointSynchronize::is_at_safepoint() && Thread::current()->is_VM_thread()), 634 "not locked"); 635 HeapWord* obj = top(); 636 if (pointer_delta(end(), obj) >= size) { 637 HeapWord* new_top = obj + size; 638 set_top(new_top); 639 assert(is_aligned(obj) && is_aligned(new_top), "checking alignment"); 640 return obj; 641 } else { 642 return NULL; 643 } 644 } 645 646 // This version is lock-free. 647 inline HeapWord* ContiguousSpace::par_allocate_impl(size_t size) { 648 do { 649 HeapWord* obj = top(); 650 if (pointer_delta(end(), obj) >= size) { 651 HeapWord* new_top = obj + size; 652 HeapWord* result = (HeapWord*)Atomic::cmpxchg_ptr(new_top, top_addr(), obj); 653 // result can be one of two: 654 // the old top value: the exchange succeeded 655 // otherwise: the new value of the top is returned. 656 if (result == obj) { 657 assert(is_aligned(obj) && is_aligned(new_top), "checking alignment"); 658 return obj; 659 } 660 } else { 661 return NULL; 662 } 663 } while (true); 664 } 665 666 HeapWord* ContiguousSpace::allocate_aligned(size_t size) { 667 assert(Heap_lock->owned_by_self() || (SafepointSynchronize::is_at_safepoint() && Thread::current()->is_VM_thread()), "not locked"); 668 HeapWord* end_value = end(); 669 670 HeapWord* obj = CollectedHeap::align_allocation_or_fail(top(), end_value, SurvivorAlignmentInBytes); 671 if (obj == NULL) { 672 return NULL; 673 } 674 675 if (pointer_delta(end_value, obj) >= size) { 676 HeapWord* new_top = obj + size; 677 set_top(new_top); 678 assert(is_ptr_aligned(obj, SurvivorAlignmentInBytes) && is_aligned(new_top), 679 "checking alignment"); 680 return obj; 681 } else { 682 set_top(obj); 683 return NULL; 684 } 685 } 686 687 // Requires locking. 688 HeapWord* ContiguousSpace::allocate(size_t size) { 689 return allocate_impl(size); 690 } 691 692 // Lock-free. 693 HeapWord* ContiguousSpace::par_allocate(size_t size) { 694 return par_allocate_impl(size); 695 } 696 697 void ContiguousSpace::allocate_temporary_filler(int factor) { 698 // allocate temporary type array decreasing free size with factor 'factor' 699 assert(factor >= 0, "just checking"); 700 size_t size = pointer_delta(end(), top()); 701 702 // if space is full, return 703 if (size == 0) return; 704 705 if (factor > 0) { 706 size -= size/factor; 707 } 708 size = align_object_size(size); 709 710 const size_t array_header_size = typeArrayOopDesc::header_size(T_INT); 711 if (size >= (size_t)align_object_size(array_header_size)) { 712 size_t length = (size - array_header_size) * (HeapWordSize / sizeof(jint)); 713 // allocate uninitialized int array 714 typeArrayOop t = (typeArrayOop) allocate(size); 715 assert(t != NULL, "allocation should succeed"); 716 t->set_mark(markOopDesc::prototype()); 717 t->set_klass(Universe::intArrayKlassObj()); 718 t->set_length((int)length); 719 } else { 720 assert(size == CollectedHeap::min_fill_size(), 721 "size for smallest fake object doesn't match"); 722 instanceOop obj = (instanceOop) allocate(size); 723 obj->set_mark(markOopDesc::prototype()); 724 obj->set_klass_gap(0); 725 obj->set_klass(SystemDictionary::Object_klass()); 726 } 727 } 728 729 HeapWord* OffsetTableContigSpace::initialize_threshold() { 730 return _offsets.initialize_threshold(); 731 } 732 733 HeapWord* OffsetTableContigSpace::cross_threshold(HeapWord* start, HeapWord* end) { 734 _offsets.alloc_block(start, end); 735 return _offsets.threshold(); 736 } 737 738 OffsetTableContigSpace::OffsetTableContigSpace(BlockOffsetSharedArray* sharedOffsetArray, 739 MemRegion mr) : 740 _offsets(sharedOffsetArray, mr), 741 _par_alloc_lock(Mutex::leaf, "OffsetTableContigSpace par alloc lock", true) 742 { 743 _offsets.set_contig_space(this); 744 initialize(mr, SpaceDecorator::Clear, SpaceDecorator::Mangle); 745 } 746 747 #define OBJ_SAMPLE_INTERVAL 0 748 #define BLOCK_SAMPLE_INTERVAL 100 749 750 void OffsetTableContigSpace::verify() const { 751 HeapWord* p = bottom(); 752 HeapWord* prev_p = NULL; 753 int objs = 0; 754 int blocks = 0; 755 756 if (VerifyObjectStartArray) { 757 _offsets.verify(); 758 } 759 760 while (p < top()) { 761 size_t size = oop(p)->size(); 762 // For a sampling of objects in the space, find it using the 763 // block offset table. 764 if (blocks == BLOCK_SAMPLE_INTERVAL) { 765 guarantee(p == block_start_const(p + (size/2)), 766 "check offset computation"); 767 blocks = 0; 768 } else { 769 blocks++; 770 } 771 772 if (objs == OBJ_SAMPLE_INTERVAL) { 773 oop(p)->verify(); 774 objs = 0; 775 } else { 776 objs++; 777 } 778 prev_p = p; 779 p += size; 780 } 781 guarantee(p == top(), "end of last object must match end of space"); 782 } 783 784 785 size_t TenuredSpace::allowed_dead_ratio() const { 786 return MarkSweepDeadRatio; 787 }