1 /* 2 * Copyright (c) 2001, 2019, 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 "gc/parallel/objectStartArray.inline.hpp" 27 #include "gc/parallel/parallelScavengeHeap.inline.hpp" 28 #include "gc/parallel/psCardTable.hpp" 29 #include "gc/parallel/psPromotionManager.inline.hpp" 30 #include "gc/parallel/psScavenge.inline.hpp" 31 #include "gc/parallel/psYoungGen.hpp" 32 #include "memory/iterator.inline.hpp" 33 #include "oops/access.inline.hpp" 34 #include "oops/oop.inline.hpp" 35 #include "runtime/prefetch.inline.hpp" 36 #include "utilities/align.hpp" 37 38 // Checks an individual oop for missing precise marks. Mark 39 // may be either dirty or newgen. 40 class CheckForUnmarkedOops : public BasicOopIterateClosure { 41 private: 42 PSYoungGen* _young_gen; 43 PSCardTable* _card_table; 44 HeapWord* _unmarked_addr; 45 46 protected: 47 template <class T> void do_oop_work(T* p) { 48 oop obj = RawAccess<>::oop_load(p); 49 if (_young_gen->is_in_reserved(obj) && 50 !_card_table->addr_is_marked_imprecise(p)) { 51 // Don't overwrite the first missing card mark 52 if (_unmarked_addr == NULL) { 53 _unmarked_addr = (HeapWord*)p; 54 } 55 } 56 } 57 58 public: 59 CheckForUnmarkedOops(PSYoungGen* young_gen, PSCardTable* card_table) : 60 _young_gen(young_gen), _card_table(card_table), _unmarked_addr(NULL) { } 61 62 virtual void do_oop(oop* p) { CheckForUnmarkedOops::do_oop_work(p); } 63 virtual void do_oop(narrowOop* p) { CheckForUnmarkedOops::do_oop_work(p); } 64 65 bool has_unmarked_oop() { 66 return _unmarked_addr != NULL; 67 } 68 }; 69 70 // Checks all objects for the existence of some type of mark, 71 // precise or imprecise, dirty or newgen. 72 class CheckForUnmarkedObjects : public ObjectClosure { 73 private: 74 PSYoungGen* _young_gen; 75 PSCardTable* _card_table; 76 77 public: 78 CheckForUnmarkedObjects() { 79 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 80 _young_gen = heap->young_gen(); 81 _card_table = heap->card_table(); 82 } 83 84 // Card marks are not precise. The current system can leave us with 85 // a mismatch of precise marks and beginning of object marks. This means 86 // we test for missing precise marks first. If any are found, we don't 87 // fail unless the object head is also unmarked. 88 virtual void do_object(oop obj) { 89 CheckForUnmarkedOops object_check(_young_gen, _card_table); 90 obj->oop_iterate(&object_check); 91 if (object_check.has_unmarked_oop()) { 92 guarantee(_card_table->addr_is_marked_imprecise(obj), "Found unmarked young_gen object"); 93 } 94 } 95 }; 96 97 // Checks for precise marking of oops as newgen. 98 class CheckForPreciseMarks : public BasicOopIterateClosure { 99 private: 100 PSYoungGen* _young_gen; 101 PSCardTable* _card_table; 102 103 protected: 104 template <class T> void do_oop_work(T* p) { 105 oop obj = RawAccess<IS_NOT_NULL>::oop_load(p); 106 if (_young_gen->is_in_reserved(obj)) { 107 assert(_card_table->addr_is_marked_precise(p), "Found unmarked precise oop"); 108 _card_table->set_card_newgen(p); 109 } 110 } 111 112 public: 113 CheckForPreciseMarks(PSYoungGen* young_gen, PSCardTable* card_table) : 114 _young_gen(young_gen), _card_table(card_table) { } 115 116 virtual void do_oop(oop* p) { CheckForPreciseMarks::do_oop_work(p); } 117 virtual void do_oop(narrowOop* p) { CheckForPreciseMarks::do_oop_work(p); } 118 }; 119 120 // We get passed the space_top value to prevent us from traversing into 121 // the old_gen promotion labs, which cannot be safely parsed. 122 123 // Do not call this method if the space is empty. 124 // It is a waste to start tasks and get here only to 125 // do no work. If this method needs to be called 126 // when the space is empty, fix the calculation of 127 // end_card to allow sp_top == sp->bottom(). 128 129 void PSCardTable::scavenge_contents_parallel(ObjectStartArray* start_array, 130 MutableSpace* sp, 131 HeapWord* space_top, 132 PSPromotionManager* pm, 133 uint stripe_number, 134 uint stripe_total) { 135 int ssize = 128; // Naked constant! Work unit = 64k. 136 int dirty_card_count = 0; 137 138 // It is a waste to get here if empty. 139 assert(sp->bottom() < sp->top(), "Should not be called if empty"); 140 oop* sp_top = (oop*)space_top; 141 CardValue* start_card = byte_for(sp->bottom()); 142 CardValue* end_card = byte_for(sp_top - 1) + 1; 143 oop* last_scanned = NULL; // Prevent scanning objects more than once 144 // The width of the stripe ssize*stripe_total must be 145 // consistent with the number of stripes so that the complete slice 146 // is covered. 147 size_t slice_width = ssize * stripe_total; 148 for (CardValue* slice = start_card; slice < end_card; slice += slice_width) { 149 CardValue* worker_start_card = slice + stripe_number * ssize; 150 if (worker_start_card >= end_card) 151 return; // We're done. 152 153 CardValue* worker_end_card = worker_start_card + ssize; 154 if (worker_end_card > end_card) 155 worker_end_card = end_card; 156 157 // We do not want to scan objects more than once. In order to accomplish 158 // this, we assert that any object with an object head inside our 'slice' 159 // belongs to us. We may need to extend the range of scanned cards if the 160 // last object continues into the next 'slice'. 161 // 162 // Note! ending cards are exclusive! 163 HeapWord* slice_start = addr_for(worker_start_card); 164 HeapWord* slice_end = MIN2((HeapWord*) sp_top, addr_for(worker_end_card)); 165 166 #ifdef ASSERT 167 if (GCWorkerDelayMillis > 0) { 168 // Delay 1 worker so that it proceeds after all the work 169 // has been completed. 170 if (stripe_number < 2) { 171 os::sleep(Thread::current(), GCWorkerDelayMillis, false); 172 } 173 } 174 #endif 175 176 // If there are not objects starting within the chunk, skip it. 177 if (!start_array->object_starts_in_range(slice_start, slice_end)) { 178 continue; 179 } 180 // Update our beginning addr 181 HeapWord* first_object = start_array->object_start(slice_start); 182 debug_only(oop* first_object_within_slice = (oop*) first_object;) 183 if (first_object < slice_start) { 184 last_scanned = (oop*)(first_object + oop(first_object)->size()); 185 debug_only(first_object_within_slice = last_scanned;) 186 worker_start_card = byte_for(last_scanned); 187 } 188 189 // Update the ending addr 190 if (slice_end < (HeapWord*)sp_top) { 191 // The subtraction is important! An object may start precisely at slice_end. 192 HeapWord* last_object = start_array->object_start(slice_end - 1); 193 slice_end = last_object + oop(last_object)->size(); 194 // worker_end_card is exclusive, so bump it one past the end of last_object's 195 // covered span. 196 worker_end_card = byte_for(slice_end) + 1; 197 198 if (worker_end_card > end_card) 199 worker_end_card = end_card; 200 } 201 202 assert(slice_end <= (HeapWord*)sp_top, "Last object in slice crosses space boundary"); 203 assert(is_valid_card_address(worker_start_card), "Invalid worker start card"); 204 assert(is_valid_card_address(worker_end_card), "Invalid worker end card"); 205 // Note that worker_start_card >= worker_end_card is legal, and happens when 206 // an object spans an entire slice. 207 assert(worker_start_card <= end_card, "worker start card beyond end card"); 208 assert(worker_end_card <= end_card, "worker end card beyond end card"); 209 210 CardValue* current_card = worker_start_card; 211 while (current_card < worker_end_card) { 212 // Find an unclean card. 213 while (current_card < worker_end_card && card_is_clean(*current_card)) { 214 current_card++; 215 } 216 CardValue* first_unclean_card = current_card; 217 218 // Find the end of a run of contiguous unclean cards 219 while (current_card < worker_end_card && !card_is_clean(*current_card)) { 220 while (current_card < worker_end_card && !card_is_clean(*current_card)) { 221 current_card++; 222 } 223 224 if (current_card < worker_end_card) { 225 // Some objects may be large enough to span several cards. If such 226 // an object has more than one dirty card, separated by a clean card, 227 // we will attempt to scan it twice. The test against "last_scanned" 228 // prevents the redundant object scan, but it does not prevent newly 229 // marked cards from being cleaned. 230 HeapWord* last_object_in_dirty_region = start_array->object_start(addr_for(current_card)-1); 231 size_t size_of_last_object = oop(last_object_in_dirty_region)->size(); 232 HeapWord* end_of_last_object = last_object_in_dirty_region + size_of_last_object; 233 CardValue* ending_card_of_last_object = byte_for(end_of_last_object); 234 assert(ending_card_of_last_object <= worker_end_card, "ending_card_of_last_object is greater than worker_end_card"); 235 if (ending_card_of_last_object > current_card) { 236 // This means the object spans the next complete card. 237 // We need to bump the current_card to ending_card_of_last_object 238 current_card = ending_card_of_last_object; 239 } 240 } 241 } 242 CardValue* following_clean_card = current_card; 243 244 if (first_unclean_card < worker_end_card) { 245 oop* p = (oop*) start_array->object_start(addr_for(first_unclean_card)); 246 assert((HeapWord*)p <= addr_for(first_unclean_card), "checking"); 247 // "p" should always be >= "last_scanned" because newly GC dirtied 248 // cards are no longer scanned again (see comment at end 249 // of loop on the increment of "current_card"). Test that 250 // hypothesis before removing this code. 251 // If this code is removed, deal with the first time through 252 // the loop when the last_scanned is the object starting in 253 // the previous slice. 254 assert((p >= last_scanned) || 255 (last_scanned == first_object_within_slice), 256 "Should no longer be possible"); 257 if (p < last_scanned) { 258 // Avoid scanning more than once; this can happen because 259 // newgen cards set by GC may a different set than the 260 // originally dirty set 261 p = last_scanned; 262 } 263 oop* to = (oop*)addr_for(following_clean_card); 264 265 // Test slice_end first! 266 if ((HeapWord*)to > slice_end) { 267 to = (oop*)slice_end; 268 } else if (to > sp_top) { 269 to = sp_top; 270 } 271 272 // we know which cards to scan, now clear them 273 if (first_unclean_card <= worker_start_card+1) 274 first_unclean_card = worker_start_card+1; 275 if (following_clean_card >= worker_end_card-1) 276 following_clean_card = worker_end_card-1; 277 278 while (first_unclean_card < following_clean_card) { 279 *first_unclean_card++ = clean_card; 280 } 281 282 const int interval = PrefetchScanIntervalInBytes; 283 // scan all objects in the range 284 if (interval != 0) { 285 while (p < to) { 286 Prefetch::write(p, interval); 287 oop m = oop(p); 288 assert(oopDesc::is_oop_or_null(m), "Expected an oop or NULL for header field at " PTR_FORMAT, p2i(m)); 289 pm->push_contents(m); 290 p += m->size(); 291 } 292 pm->drain_stacks_cond_depth(); 293 } else { 294 while (p < to) { 295 oop m = oop(p); 296 assert(oopDesc::is_oop_or_null(m), "Expected an oop or NULL for header field at " PTR_FORMAT, p2i(m)); 297 pm->push_contents(m); 298 p += m->size(); 299 } 300 pm->drain_stacks_cond_depth(); 301 } 302 last_scanned = p; 303 } 304 // "current_card" is still the "following_clean_card" or 305 // the current_card is >= the worker_end_card so the 306 // loop will not execute again. 307 assert((current_card == following_clean_card) || 308 (current_card >= worker_end_card), 309 "current_card should only be incremented if it still equals " 310 "following_clean_card"); 311 // Increment current_card so that it is not processed again. 312 // It may now be dirty because a old-to-young pointer was 313 // found on it an updated. If it is now dirty, it cannot be 314 // be safely cleaned in the next iteration. 315 current_card++; 316 } 317 } 318 } 319 320 // This should be called before a scavenge. 321 void PSCardTable::verify_all_young_refs_imprecise() { 322 CheckForUnmarkedObjects check; 323 324 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 325 PSOldGen* old_gen = heap->old_gen(); 326 327 old_gen->object_iterate(&check); 328 } 329 330 // This should be called immediately after a scavenge, before mutators resume. 331 void PSCardTable::verify_all_young_refs_precise() { 332 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 333 PSOldGen* old_gen = heap->old_gen(); 334 335 CheckForPreciseMarks check(heap->young_gen(), this); 336 337 old_gen->oop_iterate(&check); 338 339 verify_all_young_refs_precise_helper(old_gen->object_space()->used_region()); 340 } 341 342 void PSCardTable::verify_all_young_refs_precise_helper(MemRegion mr) { 343 CardValue* bot = byte_for(mr.start()); 344 CardValue* top = byte_for(mr.end()); 345 while (bot <= top) { 346 assert(*bot == clean_card || *bot == verify_card, "Found unwanted or unknown card mark"); 347 if (*bot == verify_card) 348 *bot = youngergen_card; 349 bot++; 350 } 351 } 352 353 bool PSCardTable::addr_is_marked_imprecise(void *addr) { 354 CardValue* p = byte_for(addr); 355 CardValue val = *p; 356 357 if (card_is_dirty(val)) 358 return true; 359 360 if (card_is_newgen(val)) 361 return true; 362 363 if (card_is_clean(val)) 364 return false; 365 366 assert(false, "Found unhandled card mark type"); 367 368 return false; 369 } 370 371 // Also includes verify_card 372 bool PSCardTable::addr_is_marked_precise(void *addr) { 373 CardValue* p = byte_for(addr); 374 CardValue val = *p; 375 376 if (card_is_newgen(val)) 377 return true; 378 379 if (card_is_verify(val)) 380 return true; 381 382 if (card_is_clean(val)) 383 return false; 384 385 if (card_is_dirty(val)) 386 return false; 387 388 assert(false, "Found unhandled card mark type"); 389 390 return false; 391 } 392 393 // Assumes that only the base or the end changes. This allows indentification 394 // of the region that is being resized. The 395 // CardTable::resize_covered_region() is used for the normal case 396 // where the covered regions are growing or shrinking at the high end. 397 // The method resize_covered_region_by_end() is analogous to 398 // CardTable::resize_covered_region() but 399 // for regions that grow or shrink at the low end. 400 void PSCardTable::resize_covered_region(MemRegion new_region) { 401 for (int i = 0; i < _cur_covered_regions; i++) { 402 if (_covered[i].start() == new_region.start()) { 403 // Found a covered region with the same start as the 404 // new region. The region is growing or shrinking 405 // from the start of the region. 406 resize_covered_region_by_start(new_region); 407 return; 408 } 409 if (_covered[i].start() > new_region.start()) { 410 break; 411 } 412 } 413 414 int changed_region = -1; 415 for (int j = 0; j < _cur_covered_regions; j++) { 416 if (_covered[j].end() == new_region.end()) { 417 changed_region = j; 418 // This is a case where the covered region is growing or shrinking 419 // at the start of the region. 420 assert(changed_region != -1, "Don't expect to add a covered region"); 421 assert(_covered[changed_region].byte_size() != new_region.byte_size(), 422 "The sizes should be different here"); 423 resize_covered_region_by_end(changed_region, new_region); 424 return; 425 } 426 } 427 // This should only be a new covered region (where no existing 428 // covered region matches at the start or the end). 429 assert(_cur_covered_regions < _max_covered_regions, 430 "An existing region should have been found"); 431 resize_covered_region_by_start(new_region); 432 } 433 434 void PSCardTable::resize_covered_region_by_start(MemRegion new_region) { 435 CardTable::resize_covered_region(new_region); 436 debug_only(verify_guard();) 437 } 438 439 void PSCardTable::resize_covered_region_by_end(int changed_region, 440 MemRegion new_region) { 441 assert(SafepointSynchronize::is_at_safepoint(), 442 "Only expect an expansion at the low end at a GC"); 443 debug_only(verify_guard();) 444 #ifdef ASSERT 445 for (int k = 0; k < _cur_covered_regions; k++) { 446 if (_covered[k].end() == new_region.end()) { 447 assert(changed_region == k, "Changed region is incorrect"); 448 break; 449 } 450 } 451 #endif 452 453 // Commit new or uncommit old pages, if necessary. 454 if (resize_commit_uncommit(changed_region, new_region)) { 455 // Set the new start of the committed region 456 resize_update_committed_table(changed_region, new_region); 457 } 458 459 // Update card table entries 460 resize_update_card_table_entries(changed_region, new_region); 461 462 // Update the covered region 463 resize_update_covered_table(changed_region, new_region); 464 465 int ind = changed_region; 466 log_trace(gc, barrier)("CardTable::resize_covered_region: "); 467 log_trace(gc, barrier)(" _covered[%d].start(): " INTPTR_FORMAT " _covered[%d].last(): " INTPTR_FORMAT, 468 ind, p2i(_covered[ind].start()), ind, p2i(_covered[ind].last())); 469 log_trace(gc, barrier)(" _committed[%d].start(): " INTPTR_FORMAT " _committed[%d].last(): " INTPTR_FORMAT, 470 ind, p2i(_committed[ind].start()), ind, p2i(_committed[ind].last())); 471 log_trace(gc, barrier)(" byte_for(start): " INTPTR_FORMAT " byte_for(last): " INTPTR_FORMAT, 472 p2i(byte_for(_covered[ind].start())), p2i(byte_for(_covered[ind].last()))); 473 log_trace(gc, barrier)(" addr_for(start): " INTPTR_FORMAT " addr_for(last): " INTPTR_FORMAT, 474 p2i(addr_for((CardValue*) _committed[ind].start())), p2i(addr_for((CardValue*) _committed[ind].last()))); 475 476 debug_only(verify_guard();) 477 } 478 479 bool PSCardTable::resize_commit_uncommit(int changed_region, 480 MemRegion new_region) { 481 bool result = false; 482 // Commit new or uncommit old pages, if necessary. 483 MemRegion cur_committed = _committed[changed_region]; 484 assert(_covered[changed_region].end() == new_region.end(), 485 "The ends of the regions are expected to match"); 486 // Extend the start of this _committed region to 487 // to cover the start of any previous _committed region. 488 // This forms overlapping regions, but never interior regions. 489 HeapWord* min_prev_start = lowest_prev_committed_start(changed_region); 490 if (min_prev_start < cur_committed.start()) { 491 // Only really need to set start of "cur_committed" to 492 // the new start (min_prev_start) but assertion checking code 493 // below use cur_committed.end() so make it correct. 494 MemRegion new_committed = 495 MemRegion(min_prev_start, cur_committed.end()); 496 cur_committed = new_committed; 497 } 498 #ifdef ASSERT 499 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 500 assert(cur_committed.start() == align_up(cur_committed.start(), os::vm_page_size()), 501 "Starts should have proper alignment"); 502 #endif 503 504 CardValue* new_start = byte_for(new_region.start()); 505 // Round down because this is for the start address 506 HeapWord* new_start_aligned = align_down((HeapWord*)new_start, os::vm_page_size()); 507 // The guard page is always committed and should not be committed over. 508 // This method is used in cases where the generation is growing toward 509 // lower addresses but the guard region is still at the end of the 510 // card table. That still makes sense when looking for writes 511 // off the end of the card table. 512 if (new_start_aligned < cur_committed.start()) { 513 // Expand the committed region 514 // 515 // Case A 516 // |+ guard +| 517 // |+ cur committed +++++++++| 518 // |+ new committed +++++++++++++++++| 519 // 520 // Case B 521 // |+ guard +| 522 // |+ cur committed +| 523 // |+ new committed +++++++| 524 // 525 // These are not expected because the calculation of the 526 // cur committed region and the new committed region 527 // share the same end for the covered region. 528 // Case C 529 // |+ guard +| 530 // |+ cur committed +| 531 // |+ new committed +++++++++++++++++| 532 // Case D 533 // |+ guard +| 534 // |+ cur committed +++++++++++| 535 // |+ new committed +++++++| 536 537 HeapWord* new_end_for_commit = 538 MIN2(cur_committed.end(), _guard_region.start()); 539 if(new_start_aligned < new_end_for_commit) { 540 MemRegion new_committed = 541 MemRegion(new_start_aligned, new_end_for_commit); 542 os::commit_memory_or_exit((char*)new_committed.start(), 543 new_committed.byte_size(), !ExecMem, 544 "card table expansion"); 545 } 546 result = true; 547 } else if (new_start_aligned > cur_committed.start()) { 548 // Shrink the committed region 549 #if 0 // uncommitting space is currently unsafe because of the interactions 550 // of growing and shrinking regions. One region A can uncommit space 551 // that it owns but which is being used by another region B (maybe). 552 // Region B has not committed the space because it was already 553 // committed by region A. 554 MemRegion uncommit_region = committed_unique_to_self(changed_region, 555 MemRegion(cur_committed.start(), new_start_aligned)); 556 if (!uncommit_region.is_empty()) { 557 if (!os::uncommit_memory((char*)uncommit_region.start(), 558 uncommit_region.byte_size())) { 559 // If the uncommit fails, ignore it. Let the 560 // committed table resizing go even though the committed 561 // table will over state the committed space. 562 } 563 } 564 #else 565 assert(!result, "Should be false with current workaround"); 566 #endif 567 } 568 assert(_committed[changed_region].end() == cur_committed.end(), 569 "end should not change"); 570 return result; 571 } 572 573 void PSCardTable::resize_update_committed_table(int changed_region, 574 MemRegion new_region) { 575 576 CardValue* new_start = byte_for(new_region.start()); 577 // Set the new start of the committed region 578 HeapWord* new_start_aligned = align_down((HeapWord*)new_start, os::vm_page_size()); 579 MemRegion new_committed = MemRegion(new_start_aligned, 580 _committed[changed_region].end()); 581 _committed[changed_region] = new_committed; 582 _committed[changed_region].set_start(new_start_aligned); 583 } 584 585 void PSCardTable::resize_update_card_table_entries(int changed_region, 586 MemRegion new_region) { 587 debug_only(verify_guard();) 588 MemRegion original_covered = _covered[changed_region]; 589 // Initialize the card entries. Only consider the 590 // region covered by the card table (_whole_heap) 591 CardValue* entry; 592 if (new_region.start() < _whole_heap.start()) { 593 entry = byte_for(_whole_heap.start()); 594 } else { 595 entry = byte_for(new_region.start()); 596 } 597 CardValue* end = byte_for(original_covered.start()); 598 // If _whole_heap starts at the original covered regions start, 599 // this loop will not execute. 600 while (entry < end) { *entry++ = clean_card; } 601 } 602 603 void PSCardTable::resize_update_covered_table(int changed_region, 604 MemRegion new_region) { 605 // Update the covered region 606 _covered[changed_region].set_start(new_region.start()); 607 _covered[changed_region].set_word_size(new_region.word_size()); 608 609 // reorder regions. There should only be at most 1 out 610 // of order. 611 for (int i = _cur_covered_regions-1 ; i > 0; i--) { 612 if (_covered[i].start() < _covered[i-1].start()) { 613 MemRegion covered_mr = _covered[i-1]; 614 _covered[i-1] = _covered[i]; 615 _covered[i] = covered_mr; 616 MemRegion committed_mr = _committed[i-1]; 617 _committed[i-1] = _committed[i]; 618 _committed[i] = committed_mr; 619 break; 620 } 621 } 622 #ifdef ASSERT 623 for (int m = 0; m < _cur_covered_regions-1; m++) { 624 assert(_covered[m].start() <= _covered[m+1].start(), 625 "Covered regions out of order"); 626 assert(_committed[m].start() <= _committed[m+1].start(), 627 "Committed regions out of order"); 628 } 629 #endif 630 } 631 632 // Returns the start of any committed region that is lower than 633 // the target committed region (index ind) and that intersects the 634 // target region. If none, return start of target region. 635 // 636 // ------------- 637 // | | 638 // ------------- 639 // ------------ 640 // | target | 641 // ------------ 642 // ------------- 643 // | | 644 // ------------- 645 // ^ returns this 646 // 647 // ------------- 648 // | | 649 // ------------- 650 // ------------ 651 // | target | 652 // ------------ 653 // ------------- 654 // | | 655 // ------------- 656 // ^ returns this 657 658 HeapWord* PSCardTable::lowest_prev_committed_start(int ind) const { 659 assert(_cur_covered_regions >= 0, "Expecting at least on region"); 660 HeapWord* min_start = _committed[ind].start(); 661 for (int j = 0; j < ind; j++) { 662 HeapWord* this_start = _committed[j].start(); 663 if ((this_start < min_start) && 664 !(_committed[j].intersection(_committed[ind])).is_empty()) { 665 min_start = this_start; 666 } 667 } 668 return min_start; 669 } 670 671 bool PSCardTable::is_in_young(oop obj) const { 672 return ParallelScavengeHeap::heap()->is_in_young(obj); 673 }