1 /* 2 * Copyright (c) 2001, 2018, 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/gcTaskManager.hpp" 27 #include "gc/parallel/objectStartArray.inline.hpp" 28 #include "gc/parallel/parallelScavengeHeap.inline.hpp" 29 #include "gc/parallel/psCardTable.hpp" 30 #include "gc/parallel/psPromotionManager.inline.hpp" 31 #include "gc/parallel/psScavenge.inline.hpp" 32 #include "gc/parallel/psYoungGen.hpp" 33 #include "memory/iterator.inline.hpp" 34 #include "oops/access.inline.hpp" 35 #include "oops/oop.inline.hpp" 36 #include "runtime/prefetch.inline.hpp" 37 #include "utilities/align.hpp" 38 39 // Checks an individual oop for missing precise marks. Mark 40 // may be either dirty or newgen. 41 class CheckForUnmarkedOops : public BasicOopIterateClosure { 42 private: 43 PSYoungGen* _young_gen; 44 PSCardTable* _card_table; 45 HeapWord* _unmarked_addr; 46 47 protected: 48 template <class T> void do_oop_work(T* p) { 49 oop obj = RawAccess<>::oop_load(p); 50 if (_young_gen->is_in_reserved(obj) && 51 !_card_table->addr_is_marked_imprecise(p)) { 52 // Don't overwrite the first missing card mark 53 if (_unmarked_addr == NULL) { 54 _unmarked_addr = (HeapWord*)p; 55 } 56 } 57 } 58 59 public: 60 CheckForUnmarkedOops(PSYoungGen* young_gen, PSCardTable* card_table) : 61 _young_gen(young_gen), _card_table(card_table), _unmarked_addr(NULL) { } 62 63 virtual void do_oop(oop* p) { CheckForUnmarkedOops::do_oop_work(p); } 64 virtual void do_oop(narrowOop* p) { CheckForUnmarkedOops::do_oop_work(p); } 65 66 bool has_unmarked_oop() { 67 return _unmarked_addr != NULL; 68 } 69 }; 70 71 // Checks all objects for the existence of some type of mark, 72 // precise or imprecise, dirty or newgen. 73 class CheckForUnmarkedObjects : public ObjectClosure { 74 private: 75 PSYoungGen* _young_gen; 76 PSCardTable* _card_table; 77 78 public: 79 CheckForUnmarkedObjects() { 80 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 81 _young_gen = heap->young_gen(); 82 _card_table = heap->card_table(); 83 } 84 85 // Card marks are not precise. The current system can leave us with 86 // a mismatch of precise marks and beginning of object marks. This means 87 // we test for missing precise marks first. If any are found, we don't 88 // fail unless the object head is also unmarked. 89 virtual void do_object(oop obj) { 90 CheckForUnmarkedOops object_check(_young_gen, _card_table); 91 obj->oop_iterate(&object_check); 92 if (object_check.has_unmarked_oop()) { 93 guarantee(_card_table->addr_is_marked_imprecise(obj), "Found unmarked young_gen object"); 94 } 95 } 96 }; 97 98 // Checks for precise marking of oops as newgen. 99 class CheckForPreciseMarks : public BasicOopIterateClosure { 100 private: 101 PSYoungGen* _young_gen; 102 PSCardTable* _card_table; 103 104 protected: 105 template <class T> void do_oop_work(T* p) { 106 oop obj = RawAccess<IS_NOT_NULL>::oop_load(p); 107 if (_young_gen->is_in_reserved(obj)) { 108 assert(_card_table->addr_is_marked_precise(p), "Found unmarked precise oop"); 109 _card_table->set_card_newgen(p); 110 } 111 } 112 113 public: 114 CheckForPreciseMarks(PSYoungGen* young_gen, PSCardTable* card_table) : 115 _young_gen(young_gen), _card_table(card_table) { } 116 117 virtual void do_oop(oop* p) { CheckForPreciseMarks::do_oop_work(p); } 118 virtual void do_oop(narrowOop* p) { CheckForPreciseMarks::do_oop_work(p); } 119 }; 120 121 // We get passed the space_top value to prevent us from traversing into 122 // the old_gen promotion labs, which cannot be safely parsed. 123 124 // Do not call this method if the space is empty. 125 // It is a waste to start tasks and get here only to 126 // do no work. If this method needs to be called 127 // when the space is empty, fix the calculation of 128 // end_card to allow sp_top == sp->bottom(). 129 130 void PSCardTable::scavenge_contents_parallel(ObjectStartArray* start_array, 131 MutableSpace* sp, 132 HeapWord* space_top, 133 PSPromotionManager* pm, 134 uint stripe_number, 135 uint stripe_total) { 136 int ssize = 128; // Naked constant! Work unit = 64k. 137 int dirty_card_count = 0; 138 139 // It is a waste to get here if empty. 140 assert(sp->bottom() < sp->top(), "Should not be called if empty"); 141 oop* sp_top = (oop*)space_top; 142 CardValue* start_card = byte_for(sp->bottom()); 143 CardValue* end_card = byte_for(sp_top - 1) + 1; 144 oop* last_scanned = NULL; // Prevent scanning objects more than once 145 // The width of the stripe ssize*stripe_total must be 146 // consistent with the number of stripes so that the complete slice 147 // is covered. 148 size_t slice_width = ssize * stripe_total; 149 for (CardValue* slice = start_card; slice < end_card; slice += slice_width) { 150 CardValue* worker_start_card = slice + stripe_number * ssize; 151 if (worker_start_card >= end_card) 152 return; // We're done. 153 154 CardValue* worker_end_card = worker_start_card + ssize; 155 if (worker_end_card > end_card) 156 worker_end_card = end_card; 157 158 // We do not want to scan objects more than once. In order to accomplish 159 // this, we assert that any object with an object head inside our 'slice' 160 // belongs to us. We may need to extend the range of scanned cards if the 161 // last object continues into the next 'slice'. 162 // 163 // Note! ending cards are exclusive! 164 HeapWord* slice_start = addr_for(worker_start_card); 165 HeapWord* slice_end = MIN2((HeapWord*) sp_top, addr_for(worker_end_card)); 166 167 #ifdef ASSERT 168 if (GCWorkerDelayMillis > 0) { 169 // Delay 1 worker so that it proceeds after all the work 170 // has been completed. 171 if (stripe_number < 2) { 172 os::sleep(Thread::current(), GCWorkerDelayMillis, false); 173 } 174 } 175 #endif 176 177 // If there are not objects starting within the chunk, skip it. 178 if (!start_array->object_starts_in_range(slice_start, slice_end)) { 179 continue; 180 } 181 // Update our beginning addr 182 HeapWord* first_object = start_array->object_start(slice_start); 183 debug_only(oop* first_object_within_slice = (oop*) first_object;) 184 if (first_object < slice_start) { 185 last_scanned = (oop*)(first_object + oop(first_object)->size()); 186 debug_only(first_object_within_slice = last_scanned;) 187 worker_start_card = byte_for(last_scanned); 188 } 189 190 // Update the ending addr 191 if (slice_end < (HeapWord*)sp_top) { 192 // The subtraction is important! An object may start precisely at slice_end. 193 HeapWord* last_object = start_array->object_start(slice_end - 1); 194 slice_end = last_object + oop(last_object)->size(); 195 // worker_end_card is exclusive, so bump it one past the end of last_object's 196 // covered span. 197 worker_end_card = byte_for(slice_end) + 1; 198 199 if (worker_end_card > end_card) 200 worker_end_card = end_card; 201 } 202 203 assert(slice_end <= (HeapWord*)sp_top, "Last object in slice crosses space boundary"); 204 assert(is_valid_card_address(worker_start_card), "Invalid worker start card"); 205 assert(is_valid_card_address(worker_end_card), "Invalid worker end card"); 206 // Note that worker_start_card >= worker_end_card is legal, and happens when 207 // an object spans an entire slice. 208 assert(worker_start_card <= end_card, "worker start card beyond end card"); 209 assert(worker_end_card <= end_card, "worker end card beyond end card"); 210 211 CardValue* current_card = worker_start_card; 212 while (current_card < worker_end_card) { 213 // Find an unclean card. 214 while (current_card < worker_end_card && card_is_clean(*current_card)) { 215 current_card++; 216 } 217 CardValue* first_unclean_card = current_card; 218 219 // Find the end of a run of contiguous unclean cards 220 while (current_card < worker_end_card && !card_is_clean(*current_card)) { 221 while (current_card < worker_end_card && !card_is_clean(*current_card)) { 222 current_card++; 223 } 224 225 if (current_card < worker_end_card) { 226 // Some objects may be large enough to span several cards. If such 227 // an object has more than one dirty card, separated by a clean card, 228 // we will attempt to scan it twice. The test against "last_scanned" 229 // prevents the redundant object scan, but it does not prevent newly 230 // marked cards from being cleaned. 231 HeapWord* last_object_in_dirty_region = start_array->object_start(addr_for(current_card)-1); 232 size_t size_of_last_object = oop(last_object_in_dirty_region)->size(); 233 HeapWord* end_of_last_object = last_object_in_dirty_region + size_of_last_object; 234 CardValue* ending_card_of_last_object = byte_for(end_of_last_object); 235 assert(ending_card_of_last_object <= worker_end_card, "ending_card_of_last_object is greater than worker_end_card"); 236 if (ending_card_of_last_object > current_card) { 237 // This means the object spans the next complete card. 238 // We need to bump the current_card to ending_card_of_last_object 239 current_card = ending_card_of_last_object; 240 } 241 } 242 } 243 CardValue* following_clean_card = current_card; 244 245 if (first_unclean_card < worker_end_card) { 246 oop* p = (oop*) start_array->object_start(addr_for(first_unclean_card)); 247 assert((HeapWord*)p <= addr_for(first_unclean_card), "checking"); 248 // "p" should always be >= "last_scanned" because newly GC dirtied 249 // cards are no longer scanned again (see comment at end 250 // of loop on the increment of "current_card"). Test that 251 // hypothesis before removing this code. 252 // If this code is removed, deal with the first time through 253 // the loop when the last_scanned is the object starting in 254 // the previous slice. 255 assert((p >= last_scanned) || 256 (last_scanned == first_object_within_slice), 257 "Should no longer be possible"); 258 if (p < last_scanned) { 259 // Avoid scanning more than once; this can happen because 260 // newgen cards set by GC may a different set than the 261 // originally dirty set 262 p = last_scanned; 263 } 264 oop* to = (oop*)addr_for(following_clean_card); 265 266 // Test slice_end first! 267 if ((HeapWord*)to > slice_end) { 268 to = (oop*)slice_end; 269 } else if (to > sp_top) { 270 to = sp_top; 271 } 272 273 // we know which cards to scan, now clear them 274 if (first_unclean_card <= worker_start_card+1) 275 first_unclean_card = worker_start_card+1; 276 if (following_clean_card >= worker_end_card-1) 277 following_clean_card = worker_end_card-1; 278 279 while (first_unclean_card < following_clean_card) { 280 *first_unclean_card++ = clean_card; 281 } 282 283 const int interval = PrefetchScanIntervalInBytes; 284 // scan all objects in the range 285 if (interval != 0) { 286 while (p < to) { 287 Prefetch::write(p, interval); 288 oop m = oop(p); 289 assert(oopDesc::is_oop_or_null(m), "Expected an oop or NULL for header field at " PTR_FORMAT, p2i(m)); 290 pm->push_contents(m); 291 p += m->size(); 292 } 293 pm->drain_stacks_cond_depth(); 294 } else { 295 while (p < to) { 296 oop m = oop(p); 297 assert(oopDesc::is_oop_or_null(m), "Expected an oop or NULL for header field at " PTR_FORMAT, p2i(m)); 298 pm->push_contents(m); 299 p += m->size(); 300 } 301 pm->drain_stacks_cond_depth(); 302 } 303 last_scanned = p; 304 } 305 // "current_card" is still the "following_clean_card" or 306 // the current_card is >= the worker_end_card so the 307 // loop will not execute again. 308 assert((current_card == following_clean_card) || 309 (current_card >= worker_end_card), 310 "current_card should only be incremented if it still equals " 311 "following_clean_card"); 312 // Increment current_card so that it is not processed again. 313 // It may now be dirty because a old-to-young pointer was 314 // found on it an updated. If it is now dirty, it cannot be 315 // be safely cleaned in the next iteration. 316 current_card++; 317 } 318 } 319 } 320 321 // This should be called before a scavenge. 322 void PSCardTable::verify_all_young_refs_imprecise() { 323 CheckForUnmarkedObjects check; 324 325 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 326 PSOldGen* old_gen = heap->old_gen(); 327 328 old_gen->object_iterate(&check); 329 } 330 331 // This should be called immediately after a scavenge, before mutators resume. 332 void PSCardTable::verify_all_young_refs_precise() { 333 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 334 PSOldGen* old_gen = heap->old_gen(); 335 336 CheckForPreciseMarks check(heap->young_gen(), this); 337 338 old_gen->oop_iterate(&check); 339 340 verify_all_young_refs_precise_helper(old_gen->object_space()->used_region()); 341 } 342 343 void PSCardTable::verify_all_young_refs_precise_helper(MemRegion mr) { 344 CardValue* bot = byte_for(mr.start()); 345 CardValue* top = byte_for(mr.end()); 346 while (bot <= top) { 347 assert(*bot == clean_card || *bot == verify_card, "Found unwanted or unknown card mark"); 348 if (*bot == verify_card) 349 *bot = youngergen_card; 350 bot++; 351 } 352 } 353 354 bool PSCardTable::addr_is_marked_imprecise(void *addr) { 355 CardValue* p = byte_for(addr); 356 CardValue val = *p; 357 358 if (card_is_dirty(val)) 359 return true; 360 361 if (card_is_newgen(val)) 362 return true; 363 364 if (card_is_clean(val)) 365 return false; 366 367 assert(false, "Found unhandled card mark type"); 368 369 return false; 370 } 371 372 // Also includes verify_card 373 bool PSCardTable::addr_is_marked_precise(void *addr) { 374 CardValue* p = byte_for(addr); 375 CardValue val = *p; 376 377 if (card_is_newgen(val)) 378 return true; 379 380 if (card_is_verify(val)) 381 return true; 382 383 if (card_is_clean(val)) 384 return false; 385 386 if (card_is_dirty(val)) 387 return false; 388 389 assert(false, "Found unhandled card mark type"); 390 391 return false; 392 } 393 394 // Assumes that only the base or the end changes. This allows indentification 395 // of the region that is being resized. The 396 // CardTable::resize_covered_region() is used for the normal case 397 // where the covered regions are growing or shrinking at the high end. 398 // The method resize_covered_region_by_end() is analogous to 399 // CardTable::resize_covered_region() but 400 // for regions that grow or shrink at the low end. 401 void PSCardTable::resize_covered_region(MemRegion new_region) { 402 for (int i = 0; i < _cur_covered_regions; i++) { 403 if (_covered[i].start() == new_region.start()) { 404 // Found a covered region with the same start as the 405 // new region. The region is growing or shrinking 406 // from the start of the region. 407 resize_covered_region_by_start(new_region); 408 return; 409 } 410 if (_covered[i].start() > new_region.start()) { 411 break; 412 } 413 } 414 415 int changed_region = -1; 416 for (int j = 0; j < _cur_covered_regions; j++) { 417 if (_covered[j].end() == new_region.end()) { 418 changed_region = j; 419 // This is a case where the covered region is growing or shrinking 420 // at the start of the region. 421 assert(changed_region != -1, "Don't expect to add a covered region"); 422 assert(_covered[changed_region].byte_size() != new_region.byte_size(), 423 "The sizes should be different here"); 424 resize_covered_region_by_end(changed_region, new_region); 425 return; 426 } 427 } 428 // This should only be a new covered region (where no existing 429 // covered region matches at the start or the end). 430 assert(_cur_covered_regions < _max_covered_regions, 431 "An existing region should have been found"); 432 resize_covered_region_by_start(new_region); 433 } 434 435 void PSCardTable::resize_covered_region_by_start(MemRegion new_region) { 436 CardTable::resize_covered_region(new_region); 437 debug_only(verify_guard();) 438 } 439 440 void PSCardTable::resize_covered_region_by_end(int changed_region, 441 MemRegion new_region) { 442 assert(SafepointSynchronize::is_at_safepoint(), 443 "Only expect an expansion at the low end at a GC"); 444 debug_only(verify_guard();) 445 #ifdef ASSERT 446 for (int k = 0; k < _cur_covered_regions; k++) { 447 if (_covered[k].end() == new_region.end()) { 448 assert(changed_region == k, "Changed region is incorrect"); 449 break; 450 } 451 } 452 #endif 453 454 // Commit new or uncommit old pages, if necessary. 455 if (resize_commit_uncommit(changed_region, new_region)) { 456 // Set the new start of the committed region 457 resize_update_committed_table(changed_region, new_region); 458 } 459 460 // Update card table entries 461 resize_update_card_table_entries(changed_region, new_region); 462 463 // Update the covered region 464 resize_update_covered_table(changed_region, new_region); 465 466 int ind = changed_region; 467 log_trace(gc, barrier)("CardTable::resize_covered_region: "); 468 log_trace(gc, barrier)(" _covered[%d].start(): " INTPTR_FORMAT " _covered[%d].last(): " INTPTR_FORMAT, 469 ind, p2i(_covered[ind].start()), ind, p2i(_covered[ind].last())); 470 log_trace(gc, barrier)(" _committed[%d].start(): " INTPTR_FORMAT " _committed[%d].last(): " INTPTR_FORMAT, 471 ind, p2i(_committed[ind].start()), ind, p2i(_committed[ind].last())); 472 log_trace(gc, barrier)(" byte_for(start): " INTPTR_FORMAT " byte_for(last): " INTPTR_FORMAT, 473 p2i(byte_for(_covered[ind].start())), p2i(byte_for(_covered[ind].last()))); 474 log_trace(gc, barrier)(" addr_for(start): " INTPTR_FORMAT " addr_for(last): " INTPTR_FORMAT, 475 p2i(addr_for((CardValue*) _committed[ind].start())), p2i(addr_for((CardValue*) _committed[ind].last()))); 476 477 debug_only(verify_guard();) 478 } 479 480 bool PSCardTable::resize_commit_uncommit(int changed_region, 481 MemRegion new_region) { 482 bool result = false; 483 // Commit new or uncommit old pages, if necessary. 484 MemRegion cur_committed = _committed[changed_region]; 485 assert(_covered[changed_region].end() == new_region.end(), 486 "The ends of the regions are expected to match"); 487 // Extend the start of this _committed region to 488 // to cover the start of any previous _committed region. 489 // This forms overlapping regions, but never interior regions. 490 HeapWord* min_prev_start = lowest_prev_committed_start(changed_region); 491 if (min_prev_start < cur_committed.start()) { 492 // Only really need to set start of "cur_committed" to 493 // the new start (min_prev_start) but assertion checking code 494 // below use cur_committed.end() so make it correct. 495 MemRegion new_committed = 496 MemRegion(min_prev_start, cur_committed.end()); 497 cur_committed = new_committed; 498 } 499 #ifdef ASSERT 500 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 501 assert(cur_committed.start() == align_up(cur_committed.start(), os::vm_page_size()), 502 "Starts should have proper alignment"); 503 #endif 504 505 CardValue* new_start = byte_for(new_region.start()); 506 // Round down because this is for the start address 507 HeapWord* new_start_aligned = align_down((HeapWord*)new_start, os::vm_page_size()); 508 // The guard page is always committed and should not be committed over. 509 // This method is used in cases where the generation is growing toward 510 // lower addresses but the guard region is still at the end of the 511 // card table. That still makes sense when looking for writes 512 // off the end of the card table. 513 if (new_start_aligned < cur_committed.start()) { 514 // Expand the committed region 515 // 516 // Case A 517 // |+ guard +| 518 // |+ cur committed +++++++++| 519 // |+ new committed +++++++++++++++++| 520 // 521 // Case B 522 // |+ guard +| 523 // |+ cur committed +| 524 // |+ new committed +++++++| 525 // 526 // These are not expected because the calculation of the 527 // cur committed region and the new committed region 528 // share the same end for the covered region. 529 // Case C 530 // |+ guard +| 531 // |+ cur committed +| 532 // |+ new committed +++++++++++++++++| 533 // Case D 534 // |+ guard +| 535 // |+ cur committed +++++++++++| 536 // |+ new committed +++++++| 537 538 HeapWord* new_end_for_commit = 539 MIN2(cur_committed.end(), _guard_region.start()); 540 if(new_start_aligned < new_end_for_commit) { 541 MemRegion new_committed = 542 MemRegion(new_start_aligned, new_end_for_commit); 543 os::commit_memory_or_exit((char*)new_committed.start(), 544 new_committed.byte_size(), !ExecMem, 545 "card table expansion"); 546 } 547 result = true; 548 } else if (new_start_aligned > cur_committed.start()) { 549 // Shrink the committed region 550 #if 0 // uncommitting space is currently unsafe because of the interactions 551 // of growing and shrinking regions. One region A can uncommit space 552 // that it owns but which is being used by another region B (maybe). 553 // Region B has not committed the space because it was already 554 // committed by region A. 555 MemRegion uncommit_region = committed_unique_to_self(changed_region, 556 MemRegion(cur_committed.start(), new_start_aligned)); 557 if (!uncommit_region.is_empty()) { 558 if (!os::uncommit_memory((char*)uncommit_region.start(), 559 uncommit_region.byte_size())) { 560 // If the uncommit fails, ignore it. Let the 561 // committed table resizing go even though the committed 562 // table will over state the committed space. 563 } 564 } 565 #else 566 assert(!result, "Should be false with current workaround"); 567 #endif 568 } 569 assert(_committed[changed_region].end() == cur_committed.end(), 570 "end should not change"); 571 return result; 572 } 573 574 void PSCardTable::resize_update_committed_table(int changed_region, 575 MemRegion new_region) { 576 577 CardValue* new_start = byte_for(new_region.start()); 578 // Set the new start of the committed region 579 HeapWord* new_start_aligned = align_down((HeapWord*)new_start, os::vm_page_size()); 580 MemRegion new_committed = MemRegion(new_start_aligned, 581 _committed[changed_region].end()); 582 _committed[changed_region] = new_committed; 583 _committed[changed_region].set_start(new_start_aligned); 584 } 585 586 void PSCardTable::resize_update_card_table_entries(int changed_region, 587 MemRegion new_region) { 588 debug_only(verify_guard();) 589 MemRegion original_covered = _covered[changed_region]; 590 // Initialize the card entries. Only consider the 591 // region covered by the card table (_whole_heap) 592 CardValue* entry; 593 if (new_region.start() < _whole_heap.start()) { 594 entry = byte_for(_whole_heap.start()); 595 } else { 596 entry = byte_for(new_region.start()); 597 } 598 CardValue* end = byte_for(original_covered.start()); 599 // If _whole_heap starts at the original covered regions start, 600 // this loop will not execute. 601 while (entry < end) { *entry++ = clean_card; } 602 } 603 604 void PSCardTable::resize_update_covered_table(int changed_region, 605 MemRegion new_region) { 606 // Update the covered region 607 _covered[changed_region].set_start(new_region.start()); 608 _covered[changed_region].set_word_size(new_region.word_size()); 609 610 // reorder regions. There should only be at most 1 out 611 // of order. 612 for (int i = _cur_covered_regions-1 ; i > 0; i--) { 613 if (_covered[i].start() < _covered[i-1].start()) { 614 MemRegion covered_mr = _covered[i-1]; 615 _covered[i-1] = _covered[i]; 616 _covered[i] = covered_mr; 617 MemRegion committed_mr = _committed[i-1]; 618 _committed[i-1] = _committed[i]; 619 _committed[i] = committed_mr; 620 break; 621 } 622 } 623 #ifdef ASSERT 624 for (int m = 0; m < _cur_covered_regions-1; m++) { 625 assert(_covered[m].start() <= _covered[m+1].start(), 626 "Covered regions out of order"); 627 assert(_committed[m].start() <= _committed[m+1].start(), 628 "Committed regions out of order"); 629 } 630 #endif 631 } 632 633 // Returns the start of any committed region that is lower than 634 // the target committed region (index ind) and that intersects the 635 // target region. If none, return start of target region. 636 // 637 // ------------- 638 // | | 639 // ------------- 640 // ------------ 641 // | target | 642 // ------------ 643 // ------------- 644 // | | 645 // ------------- 646 // ^ returns this 647 // 648 // ------------- 649 // | | 650 // ------------- 651 // ------------ 652 // | target | 653 // ------------ 654 // ------------- 655 // | | 656 // ------------- 657 // ^ returns this 658 659 HeapWord* PSCardTable::lowest_prev_committed_start(int ind) const { 660 assert(_cur_covered_regions >= 0, "Expecting at least on region"); 661 HeapWord* min_start = _committed[ind].start(); 662 for (int j = 0; j < ind; j++) { 663 HeapWord* this_start = _committed[j].start(); 664 if ((this_start < min_start) && 665 !(_committed[j].intersection(_committed[ind])).is_empty()) { 666 min_start = this_start; 667 } 668 } 669 return min_start; 670 } 671 672 bool PSCardTable::is_in_young(oop obj) const { 673 return ParallelScavengeHeap::heap()->is_in_young(obj); 674 }