1 /*
   2  * Copyright (c) 2000, 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 "gc/shared/cardTableModRefBS.inline.hpp"
  27 #include "gc/shared/cardTableRS.hpp"
  28 #include "gc/shared/collectedHeap.hpp"
  29 #include "gc/shared/genCollectedHeap.hpp"
  30 #include "gc/shared/space.hpp"
  31 #include "gc/shared/space.inline.hpp"
  32 #include "memory/allocation.inline.hpp"
  33 #include "memory/universe.hpp"
  34 #include "memory/virtualspace.hpp"
  35 #include "runtime/java.hpp"
  36 #include "runtime/mutexLocker.hpp"
  37 #include "services/memTracker.hpp"
  38 #include "utilities/macros.hpp"
  39 #ifdef COMPILER1
  40 #include "c1/c1_LIR.hpp"
  41 #include "c1/c1_LIRGenerator.hpp"
  42 #endif
  43 
  44 // This kind of "BarrierSet" allows a "CollectedHeap" to detect and
  45 // enumerate ref fields that have been modified (since the last
  46 // enumeration.)
  47 
  48 size_t CardTableModRefBS::compute_byte_map_size()
  49 {
  50   assert(_guard_index == cards_required(_whole_heap.word_size()) - 1,
  51                                         "uninitialized, check declaration order");
  52   assert(_page_size != 0, "uninitialized, check declaration order");
  53   const size_t granularity = os::vm_allocation_granularity();
  54   return align_size_up(_guard_index + 1, MAX2(_page_size, granularity));
  55 }
  56 
  57 CardTableModRefBS::CardTableModRefBS(
  58   MemRegion whole_heap,
  59   const BarrierSet::FakeRtti& fake_rtti) :
  60   ModRefBarrierSet(fake_rtti.add_tag(BarrierSet::CardTableModRef)),
  61   _whole_heap(whole_heap),
  62   _guard_index(0),
  63   _guard_region(),
  64   _last_valid_index(0),
  65   _page_size(os::vm_page_size()),
  66   _byte_map_size(0),
  67   _covered(NULL),
  68   _committed(NULL),
  69   _cur_covered_regions(0),
  70   _byte_map(NULL),
  71   byte_map_base(NULL),
  72   // LNC functionality
  73   _lowest_non_clean(NULL),
  74   _lowest_non_clean_chunk_size(NULL),
  75   _lowest_non_clean_base_chunk_index(NULL),
  76   _last_LNC_resizing_collection(NULL)
  77 {
  78   assert((uintptr_t(_whole_heap.start())  & (card_size - 1))  == 0, "heap must start at card boundary");
  79   assert((uintptr_t(_whole_heap.end()) & (card_size - 1))  == 0, "heap must end at card boundary");
  80 
  81   assert(card_size <= 512, "card_size must be less than 512"); // why?
  82 
  83   _covered   = new MemRegion[_max_covered_regions];
  84   if (_covered == NULL) {
  85     vm_exit_during_initialization("Could not allocate card table covered region set.");
  86   }
  87 }
  88 
  89 void CardTableModRefBS::initialize() {
  90   _guard_index = cards_required(_whole_heap.word_size()) - 1;
  91   _last_valid_index = _guard_index - 1;
  92 
  93   _byte_map_size = compute_byte_map_size();
  94 
  95   HeapWord* low_bound  = _whole_heap.start();
  96   HeapWord* high_bound = _whole_heap.end();
  97 
  98   _cur_covered_regions = 0;
  99   _committed = new MemRegion[_max_covered_regions];
 100   if (_committed == NULL) {
 101     vm_exit_during_initialization("Could not allocate card table committed region set.");
 102   }
 103 
 104   const size_t rs_align = _page_size == (size_t) os::vm_page_size() ? 0 :
 105     MAX2(_page_size, (size_t) os::vm_allocation_granularity());
 106   ReservedSpace heap_rs(_byte_map_size, rs_align, false);
 107 
 108   MemTracker::record_virtual_memory_type((address)heap_rs.base(), mtGC);
 109 
 110   os::trace_page_sizes("card table", _guard_index + 1, _guard_index + 1,
 111                        _page_size, heap_rs.base(), heap_rs.size());
 112   if (!heap_rs.is_reserved()) {
 113     vm_exit_during_initialization("Could not reserve enough space for the "
 114                                   "card marking array");
 115   }
 116 
 117   // The assembler store_check code will do an unsigned shift of the oop,
 118   // then add it to byte_map_base, i.e.
 119   //
 120   //   _byte_map = byte_map_base + (uintptr_t(low_bound) >> card_shift)
 121   _byte_map = (jbyte*) heap_rs.base();
 122   byte_map_base = _byte_map - (uintptr_t(low_bound) >> card_shift);
 123   assert(byte_for(low_bound) == &_byte_map[0], "Checking start of map");
 124   assert(byte_for(high_bound-1) <= &_byte_map[_last_valid_index], "Checking end of map");
 125 
 126   jbyte* guard_card = &_byte_map[_guard_index];
 127   uintptr_t guard_page = align_size_down((uintptr_t)guard_card, _page_size);
 128   _guard_region = MemRegion((HeapWord*)guard_page, _page_size);
 129   os::commit_memory_or_exit((char*)guard_page, _page_size, _page_size,
 130                             !ExecMem, "card table last card");
 131   *guard_card = last_card;
 132 
 133   _lowest_non_clean =
 134     NEW_C_HEAP_ARRAY(CardArr, _max_covered_regions, mtGC);
 135   _lowest_non_clean_chunk_size =
 136     NEW_C_HEAP_ARRAY(size_t, _max_covered_regions, mtGC);
 137   _lowest_non_clean_base_chunk_index =
 138     NEW_C_HEAP_ARRAY(uintptr_t, _max_covered_regions, mtGC);
 139   _last_LNC_resizing_collection =
 140     NEW_C_HEAP_ARRAY(int, _max_covered_regions, mtGC);
 141   if (_lowest_non_clean == NULL
 142       || _lowest_non_clean_chunk_size == NULL
 143       || _lowest_non_clean_base_chunk_index == NULL
 144       || _last_LNC_resizing_collection == NULL)
 145     vm_exit_during_initialization("couldn't allocate an LNC array.");
 146   for (int i = 0; i < _max_covered_regions; i++) {
 147     _lowest_non_clean[i] = NULL;
 148     _lowest_non_clean_chunk_size[i] = 0;
 149     _last_LNC_resizing_collection[i] = -1;
 150   }
 151 
 152   if (TraceCardTableModRefBS) {
 153     gclog_or_tty->print_cr("CardTableModRefBS::CardTableModRefBS: ");
 154     gclog_or_tty->print_cr("  "
 155                   "  &_byte_map[0]: " INTPTR_FORMAT
 156                   "  &_byte_map[_last_valid_index]: " INTPTR_FORMAT,
 157                   p2i(&_byte_map[0]),
 158                   p2i(&_byte_map[_last_valid_index]));
 159     gclog_or_tty->print_cr("  "
 160                   "  byte_map_base: " INTPTR_FORMAT,
 161                   p2i(byte_map_base));
 162   }
 163 }
 164 
 165 CardTableModRefBS::~CardTableModRefBS() {
 166   if (_covered) {
 167     delete[] _covered;
 168     _covered = NULL;
 169   }
 170   if (_committed) {
 171     delete[] _committed;
 172     _committed = NULL;
 173   }
 174   if (_lowest_non_clean) {
 175     FREE_C_HEAP_ARRAY(CardArr, _lowest_non_clean);
 176     _lowest_non_clean = NULL;
 177   }
 178   if (_lowest_non_clean_chunk_size) {
 179     FREE_C_HEAP_ARRAY(size_t, _lowest_non_clean_chunk_size);
 180     _lowest_non_clean_chunk_size = NULL;
 181   }
 182   if (_lowest_non_clean_base_chunk_index) {
 183     FREE_C_HEAP_ARRAY(uintptr_t, _lowest_non_clean_base_chunk_index);
 184     _lowest_non_clean_base_chunk_index = NULL;
 185   }
 186   if (_last_LNC_resizing_collection) {
 187     FREE_C_HEAP_ARRAY(int, _last_LNC_resizing_collection);
 188     _last_LNC_resizing_collection = NULL;
 189   }
 190 }
 191 
 192 int CardTableModRefBS::find_covering_region_by_base(HeapWord* base) {
 193   int i;
 194   for (i = 0; i < _cur_covered_regions; i++) {
 195     if (_covered[i].start() == base) return i;
 196     if (_covered[i].start() > base) break;
 197   }
 198   // If we didn't find it, create a new one.
 199   assert(_cur_covered_regions < _max_covered_regions,
 200          "too many covered regions");
 201   // Move the ones above up, to maintain sorted order.
 202   for (int j = _cur_covered_regions; j > i; j--) {
 203     _covered[j] = _covered[j-1];
 204     _committed[j] = _committed[j-1];
 205   }
 206   int res = i;
 207   _cur_covered_regions++;
 208   _covered[res].set_start(base);
 209   _covered[res].set_word_size(0);
 210   jbyte* ct_start = byte_for(base);
 211   uintptr_t ct_start_aligned = align_size_down((uintptr_t)ct_start, _page_size);
 212   _committed[res].set_start((HeapWord*)ct_start_aligned);
 213   _committed[res].set_word_size(0);
 214   return res;
 215 }
 216 
 217 int CardTableModRefBS::find_covering_region_containing(HeapWord* addr) {
 218   for (int i = 0; i < _cur_covered_regions; i++) {
 219     if (_covered[i].contains(addr)) {
 220       return i;
 221     }
 222   }
 223   assert(0, "address outside of heap?");
 224   return -1;
 225 }
 226 
 227 HeapWord* CardTableModRefBS::largest_prev_committed_end(int ind) const {
 228   HeapWord* max_end = NULL;
 229   for (int j = 0; j < ind; j++) {
 230     HeapWord* this_end = _committed[j].end();
 231     if (this_end > max_end) max_end = this_end;
 232   }
 233   return max_end;
 234 }
 235 
 236 MemRegion CardTableModRefBS::committed_unique_to_self(int self,
 237                                                       MemRegion mr) const {
 238   MemRegion result = mr;
 239   for (int r = 0; r < _cur_covered_regions; r += 1) {
 240     if (r != self) {
 241       result = result.minus(_committed[r]);
 242     }
 243   }
 244   // Never include the guard page.
 245   result = result.minus(_guard_region);
 246   return result;
 247 }
 248 
 249 void CardTableModRefBS::resize_covered_region(MemRegion new_region) {
 250   // We don't change the start of a region, only the end.
 251   assert(_whole_heap.contains(new_region),
 252            "attempt to cover area not in reserved area");
 253   debug_only(verify_guard();)
 254   // collided is true if the expansion would push into another committed region
 255   debug_only(bool collided = false;)
 256   int const ind = find_covering_region_by_base(new_region.start());
 257   MemRegion const old_region = _covered[ind];
 258   assert(old_region.start() == new_region.start(), "just checking");
 259   if (new_region.word_size() != old_region.word_size()) {
 260     // Commit new or uncommit old pages, if necessary.
 261     MemRegion cur_committed = _committed[ind];
 262     // Extend the end of this _committed region
 263     // to cover the end of any lower _committed regions.
 264     // This forms overlapping regions, but never interior regions.
 265     HeapWord* const max_prev_end = largest_prev_committed_end(ind);
 266     if (max_prev_end > cur_committed.end()) {
 267       cur_committed.set_end(max_prev_end);
 268     }
 269     // Align the end up to a page size (starts are already aligned).
 270     jbyte* const new_end = byte_after(new_region.last());
 271     HeapWord* new_end_aligned =
 272       (HeapWord*) align_size_up((uintptr_t)new_end, _page_size);
 273     assert(new_end_aligned >= (HeapWord*) new_end,
 274            "align up, but less");
 275     // Check the other regions (excludes "ind") to ensure that
 276     // the new_end_aligned does not intrude onto the committed
 277     // space of another region.
 278     int ri = 0;
 279     for (ri = ind + 1; ri < _cur_covered_regions; ri++) {
 280       if (new_end_aligned > _committed[ri].start()) {
 281         assert(new_end_aligned <= _committed[ri].end(),
 282                "An earlier committed region can't cover a later committed region");
 283         // Any region containing the new end
 284         // should start at or beyond the region found (ind)
 285         // for the new end (committed regions are not expected to
 286         // be proper subsets of other committed regions).
 287         assert(_committed[ri].start() >= _committed[ind].start(),
 288                "New end of committed region is inconsistent");
 289         new_end_aligned = _committed[ri].start();
 290         // new_end_aligned can be equal to the start of its
 291         // committed region (i.e., of "ind") if a second
 292         // region following "ind" also start at the same location
 293         // as "ind".
 294         assert(new_end_aligned >= _committed[ind].start(),
 295           "New end of committed region is before start");
 296         debug_only(collided = true;)
 297         // Should only collide with 1 region
 298         break;
 299       }
 300     }
 301 #ifdef ASSERT
 302     for (++ri; ri < _cur_covered_regions; ri++) {
 303       assert(!_committed[ri].contains(new_end_aligned),
 304         "New end of committed region is in a second committed region");
 305     }
 306 #endif
 307     // The guard page is always committed and should not be committed over.
 308     // "guarded" is used for assertion checking below and recalls the fact
 309     // that the would-be end of the new committed region would have
 310     // penetrated the guard page.
 311     HeapWord* new_end_for_commit = new_end_aligned;
 312 
 313     DEBUG_ONLY(bool guarded = false;)
 314     if (new_end_for_commit > _guard_region.start()) {
 315       new_end_for_commit = _guard_region.start();
 316       DEBUG_ONLY(guarded = true;)
 317     }
 318 
 319     if (new_end_for_commit > cur_committed.end()) {
 320       // Must commit new pages.
 321       MemRegion const new_committed =
 322         MemRegion(cur_committed.end(), new_end_for_commit);
 323 
 324       assert(!new_committed.is_empty(), "Region should not be empty here");
 325       os::commit_memory_or_exit((char*)new_committed.start(),
 326                                 new_committed.byte_size(), _page_size,
 327                                 !ExecMem, "card table expansion");
 328     // Use new_end_aligned (as opposed to new_end_for_commit) because
 329     // the cur_committed region may include the guard region.
 330     } else if (new_end_aligned < cur_committed.end()) {
 331       // Must uncommit pages.
 332       MemRegion const uncommit_region =
 333         committed_unique_to_self(ind, MemRegion(new_end_aligned,
 334                                                 cur_committed.end()));
 335       if (!uncommit_region.is_empty()) {
 336         // It is not safe to uncommit cards if the boundary between
 337         // the generations is moving.  A shrink can uncommit cards
 338         // owned by generation A but being used by generation B.
 339         if (!UseAdaptiveGCBoundary) {
 340           if (!os::uncommit_memory((char*)uncommit_region.start(),
 341                                    uncommit_region.byte_size())) {
 342             assert(false, "Card table contraction failed");
 343             // The call failed so don't change the end of the
 344             // committed region.  This is better than taking the
 345             // VM down.
 346             new_end_aligned = _committed[ind].end();
 347           }
 348         } else {
 349           new_end_aligned = _committed[ind].end();
 350         }
 351       }
 352     }
 353     // In any case, we can reset the end of the current committed entry.
 354     _committed[ind].set_end(new_end_aligned);
 355 
 356 #ifdef ASSERT
 357     // Check that the last card in the new region is committed according
 358     // to the tables.
 359     bool covered = false;
 360     for (int cr = 0; cr < _cur_covered_regions; cr++) {
 361       if (_committed[cr].contains(new_end - 1)) {
 362         covered = true;
 363         break;
 364       }
 365     }
 366     assert(covered, "Card for end of new region not committed");
 367 #endif
 368 
 369     // The default of 0 is not necessarily clean cards.
 370     jbyte* entry;
 371     if (old_region.last() < _whole_heap.start()) {
 372       entry = byte_for(_whole_heap.start());
 373     } else {
 374       entry = byte_after(old_region.last());
 375     }
 376     assert(index_for(new_region.last()) <  _guard_index,
 377       "The guard card will be overwritten");
 378     // This line commented out cleans the newly expanded region and
 379     // not the aligned up expanded region.
 380     // jbyte* const end = byte_after(new_region.last());
 381     jbyte* const end = (jbyte*) new_end_for_commit;
 382     assert((end >= byte_after(new_region.last())) || collided || guarded,
 383       "Expect to be beyond new region unless impacting another region");
 384     // do nothing if we resized downward.
 385 #ifdef ASSERT
 386     for (int ri = 0; ri < _cur_covered_regions; ri++) {
 387       if (ri != ind) {
 388         // The end of the new committed region should not
 389         // be in any existing region unless it matches
 390         // the start of the next region.
 391         assert(!_committed[ri].contains(end) ||
 392                (_committed[ri].start() == (HeapWord*) end),
 393                "Overlapping committed regions");
 394       }
 395     }
 396 #endif
 397     if (entry < end) {
 398       memset(entry, clean_card, pointer_delta(end, entry, sizeof(jbyte)));
 399     }
 400   }
 401   // In any case, the covered size changes.
 402   _covered[ind].set_word_size(new_region.word_size());
 403   if (TraceCardTableModRefBS) {
 404     gclog_or_tty->print_cr("CardTableModRefBS::resize_covered_region: ");
 405     gclog_or_tty->print_cr("  "
 406                   "  _covered[%d].start(): " INTPTR_FORMAT
 407                   "  _covered[%d].last(): " INTPTR_FORMAT,
 408                   ind, p2i(_covered[ind].start()),
 409                   ind, p2i(_covered[ind].last()));
 410     gclog_or_tty->print_cr("  "
 411                   "  _committed[%d].start(): " INTPTR_FORMAT
 412                   "  _committed[%d].last(): " INTPTR_FORMAT,
 413                   ind, p2i(_committed[ind].start()),
 414                   ind, p2i(_committed[ind].last()));
 415     gclog_or_tty->print_cr("  "
 416                   "  byte_for(start): " INTPTR_FORMAT
 417                   "  byte_for(last): " INTPTR_FORMAT,
 418                   p2i(byte_for(_covered[ind].start())),
 419                   p2i(byte_for(_covered[ind].last())));
 420     gclog_or_tty->print_cr("  "
 421                   "  addr_for(start): " INTPTR_FORMAT
 422                   "  addr_for(last): " INTPTR_FORMAT,
 423                   p2i(addr_for((jbyte*) _committed[ind].start())),
 424                   p2i(addr_for((jbyte*) _committed[ind].last())));
 425   }
 426   // Touch the last card of the covered region to show that it
 427   // is committed (or SEGV).
 428   debug_only((void) (*byte_for(_covered[ind].last()));)
 429   debug_only(verify_guard();)
 430 }
 431 
 432 // Note that these versions are precise!  The scanning code has to handle the
 433 // fact that the write barrier may be either precise or imprecise.
 434 
 435 void CardTableModRefBS::write_ref_field_work(void* field, oop newVal, bool release) {
 436   inline_write_ref_field(field, newVal, release);
 437 }
 438 
 439 
 440 void CardTableModRefBS::non_clean_card_iterate_possibly_parallel(Space* sp,
 441                                                                  MemRegion mr,
 442                                                                  OopsInGenClosure* cl,
 443                                                                  CardTableRS* ct,
 444                                                                  uint n_threads) {
 445   if (!mr.is_empty()) {
 446     if (n_threads > 0) {
 447 #if INCLUDE_ALL_GCS
 448       non_clean_card_iterate_parallel_work(sp, mr, cl, ct, n_threads);
 449 #else  // INCLUDE_ALL_GCS
 450       fatal("Parallel gc not supported here.");
 451 #endif // INCLUDE_ALL_GCS
 452     } else {
 453       // clear_cl finds contiguous dirty ranges of cards to process and clear.
 454 
 455       // This is the single-threaded version.
 456       const bool parallel = false;
 457 
 458       DirtyCardToOopClosure* dcto_cl = sp->new_dcto_cl(cl, precision(), cl->gen_boundary(), parallel);
 459       ClearNoncleanCardWrapper clear_cl(dcto_cl, ct, parallel);
 460 
 461       clear_cl.do_MemRegion(mr);
 462     }
 463   }
 464 }
 465 
 466 void CardTableModRefBS::dirty_MemRegion(MemRegion mr) {
 467   assert((HeapWord*)align_size_down((uintptr_t)mr.start(), HeapWordSize) == mr.start(), "Unaligned start");
 468   assert((HeapWord*)align_size_up  ((uintptr_t)mr.end(),   HeapWordSize) == mr.end(),   "Unaligned end"  );
 469   jbyte* cur  = byte_for(mr.start());
 470   jbyte* last = byte_after(mr.last());
 471   while (cur < last) {
 472     *cur = dirty_card;
 473     cur++;
 474   }
 475 }
 476 
 477 void CardTableModRefBS::invalidate(MemRegion mr, bool whole_heap) {
 478   assert((HeapWord*)align_size_down((uintptr_t)mr.start(), HeapWordSize) == mr.start(), "Unaligned start");
 479   assert((HeapWord*)align_size_up  ((uintptr_t)mr.end(),   HeapWordSize) == mr.end(),   "Unaligned end"  );
 480   for (int i = 0; i < _cur_covered_regions; i++) {
 481     MemRegion mri = mr.intersection(_covered[i]);
 482     if (!mri.is_empty()) dirty_MemRegion(mri);
 483   }
 484 }
 485 
 486 void CardTableModRefBS::clear_MemRegion(MemRegion mr) {
 487   // Be conservative: only clean cards entirely contained within the
 488   // region.
 489   jbyte* cur;
 490   if (mr.start() == _whole_heap.start()) {
 491     cur = byte_for(mr.start());
 492   } else {
 493     assert(mr.start() > _whole_heap.start(), "mr is not covered.");
 494     cur = byte_after(mr.start() - 1);
 495   }
 496   jbyte* last = byte_after(mr.last());
 497   memset(cur, clean_card, pointer_delta(last, cur, sizeof(jbyte)));
 498 }
 499 
 500 void CardTableModRefBS::clear(MemRegion mr) {
 501   for (int i = 0; i < _cur_covered_regions; i++) {
 502     MemRegion mri = mr.intersection(_covered[i]);
 503     if (!mri.is_empty()) clear_MemRegion(mri);
 504   }
 505 }
 506 
 507 void CardTableModRefBS::dirty(MemRegion mr) {
 508   jbyte* first = byte_for(mr.start());
 509   jbyte* last  = byte_after(mr.last());
 510   memset(first, dirty_card, last-first);
 511 }
 512 
 513 // Unlike several other card table methods, dirty_card_iterate()
 514 // iterates over dirty cards ranges in increasing address order.
 515 void CardTableModRefBS::dirty_card_iterate(MemRegion mr,
 516                                            MemRegionClosure* cl) {
 517   for (int i = 0; i < _cur_covered_regions; i++) {
 518     MemRegion mri = mr.intersection(_covered[i]);
 519     if (!mri.is_empty()) {
 520       jbyte *cur_entry, *next_entry, *limit;
 521       for (cur_entry = byte_for(mri.start()), limit = byte_for(mri.last());
 522            cur_entry <= limit;
 523            cur_entry  = next_entry) {
 524         next_entry = cur_entry + 1;
 525         if (*cur_entry == dirty_card) {
 526           size_t dirty_cards;
 527           // Accumulate maximal dirty card range, starting at cur_entry
 528           for (dirty_cards = 1;
 529                next_entry <= limit && *next_entry == dirty_card;
 530                dirty_cards++, next_entry++);
 531           MemRegion cur_cards(addr_for(cur_entry),
 532                               dirty_cards*card_size_in_words);
 533           cl->do_MemRegion(cur_cards);
 534         }
 535       }
 536     }
 537   }
 538 }
 539 
 540 MemRegion CardTableModRefBS::dirty_card_range_after_reset(MemRegion mr,
 541                                                           bool reset,
 542                                                           int reset_val) {
 543   for (int i = 0; i < _cur_covered_regions; i++) {
 544     MemRegion mri = mr.intersection(_covered[i]);
 545     if (!mri.is_empty()) {
 546       jbyte* cur_entry, *next_entry, *limit;
 547       for (cur_entry = byte_for(mri.start()), limit = byte_for(mri.last());
 548            cur_entry <= limit;
 549            cur_entry  = next_entry) {
 550         next_entry = cur_entry + 1;
 551         if (*cur_entry == dirty_card) {
 552           size_t dirty_cards;
 553           // Accumulate maximal dirty card range, starting at cur_entry
 554           for (dirty_cards = 1;
 555                next_entry <= limit && *next_entry == dirty_card;
 556                dirty_cards++, next_entry++);
 557           MemRegion cur_cards(addr_for(cur_entry),
 558                               dirty_cards*card_size_in_words);
 559           if (reset) {
 560             for (size_t i = 0; i < dirty_cards; i++) {
 561               cur_entry[i] = reset_val;
 562             }
 563           }
 564           return cur_cards;
 565         }
 566       }
 567     }
 568   }
 569   return MemRegion(mr.end(), mr.end());
 570 }
 571 
 572 uintx CardTableModRefBS::ct_max_alignment_constraint() {
 573   return card_size * os::vm_page_size();
 574 }
 575 
 576 void CardTableModRefBS::verify_guard() {
 577   // For product build verification
 578   guarantee(_byte_map[_guard_index] == last_card,
 579             "card table guard has been modified");
 580 }
 581 
 582 void CardTableModRefBS::verify() {
 583   verify_guard();
 584 }
 585 
 586 #ifndef PRODUCT
 587 void CardTableModRefBS::verify_region(MemRegion mr,
 588                                       jbyte val, bool val_equals) {
 589   jbyte* start    = byte_for(mr.start());
 590   jbyte* end      = byte_for(mr.last());
 591   bool failures = false;
 592   for (jbyte* curr = start; curr <= end; ++curr) {
 593     jbyte curr_val = *curr;
 594     bool failed = (val_equals) ? (curr_val != val) : (curr_val == val);
 595     if (failed) {
 596       if (!failures) {
 597         tty->cr();
 598         tty->print_cr("== CT verification failed: [" INTPTR_FORMAT "," INTPTR_FORMAT "]", p2i(start), p2i(end));
 599         tty->print_cr("==   %sexpecting value: %d",
 600                       (val_equals) ? "" : "not ", val);
 601         failures = true;
 602       }
 603       tty->print_cr("==   card "PTR_FORMAT" ["PTR_FORMAT","PTR_FORMAT"], "
 604                     "val: %d", p2i(curr), p2i(addr_for(curr)),
 605                     p2i((HeapWord*) (((size_t) addr_for(curr)) + card_size)),
 606                     (int) curr_val);
 607     }
 608   }
 609   guarantee(!failures, "there should not have been any failures");
 610 }
 611 
 612 void CardTableModRefBS::verify_not_dirty_region(MemRegion mr) {
 613   verify_region(mr, dirty_card, false /* val_equals */);
 614 }
 615 
 616 void CardTableModRefBS::verify_dirty_region(MemRegion mr) {
 617   verify_region(mr, dirty_card, true /* val_equals */);
 618 }
 619 #endif
 620 
 621 void CardTableModRefBS::print_on(outputStream* st) const {
 622   st->print_cr("Card table byte_map: [" INTPTR_FORMAT "," INTPTR_FORMAT "] byte_map_base: " INTPTR_FORMAT,
 623                p2i(_byte_map), p2i(_byte_map + _byte_map_size), p2i(byte_map_base));
 624 }
 625 
 626 bool CardTableModRefBSForCTRS::card_will_be_scanned(jbyte cv) {
 627   return
 628     CardTableModRefBS::card_will_be_scanned(cv) ||
 629     _rs->is_prev_nonclean_card_val(cv);
 630 };
 631 
 632 bool CardTableModRefBSForCTRS::card_may_have_been_dirty(jbyte cv) {
 633   return
 634     cv != clean_card &&
 635     (CardTableModRefBS::card_may_have_been_dirty(cv) ||
 636      CardTableRS::youngergen_may_have_been_dirty(cv));
 637 };