1 /*
   2  * Copyright (c) 2001, 2014, 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_implementation/g1/concurrentG1Refine.hpp"
  27 #include "gc_implementation/g1/g1BlockOffsetTable.inline.hpp"
  28 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
  29 #include "gc_implementation/g1/heapRegionRemSet.hpp"
  30 #include "gc_implementation/g1/heapRegionSeq.inline.hpp"
  31 #include "memory/allocation.hpp"
  32 #include "memory/padded.inline.hpp"
  33 #include "memory/space.inline.hpp"
  34 #include "oops/oop.inline.hpp"
  35 #include "utilities/bitMap.inline.hpp"
  36 #include "utilities/globalDefinitions.hpp"
  37 #include "utilities/growableArray.hpp"
  38 
  39 class PerRegionTable: public CHeapObj<mtGC> {
  40   friend class OtherRegionsTable;
  41   friend class HeapRegionRemSetIterator;
  42 
  43   HeapRegion*     _hr;
  44   BitMap          _bm;
  45   jint            _occupied;
  46 
  47   // next pointer for free/allocated 'all' list
  48   PerRegionTable* _next;
  49 
  50   // prev pointer for the allocated 'all' list
  51   PerRegionTable* _prev;
  52 
  53   // next pointer in collision list
  54   PerRegionTable * _collision_list_next;
  55 
  56   // Global free list of PRTs
  57   static PerRegionTable* _free_list;
  58 
  59 protected:
  60   // We need access in order to union things into the base table.
  61   BitMap* bm() { return &_bm; }
  62 
  63   void recount_occupied() {
  64     _occupied = (jint) bm()->count_one_bits();
  65   }
  66 
  67   PerRegionTable(HeapRegion* hr) :
  68     _hr(hr),
  69     _occupied(0),
  70     _bm(HeapRegion::CardsPerRegion, false /* in-resource-area */),
  71     _collision_list_next(NULL), _next(NULL), _prev(NULL)
  72   {}
  73 
  74   void add_card_work(CardIdx_t from_card, bool par) {
  75     if (!_bm.at(from_card)) {
  76       if (par) {
  77         if (_bm.par_at_put(from_card, 1)) {
  78           Atomic::inc(&_occupied);
  79         }
  80       } else {
  81         _bm.at_put(from_card, 1);
  82         _occupied++;
  83       }
  84     }
  85   }
  86 
  87   void add_reference_work(OopOrNarrowOopStar from, bool par) {
  88     // Must make this robust in case "from" is not in "_hr", because of
  89     // concurrency.
  90 
  91     if (G1TraceHeapRegionRememberedSet) {
  92       gclog_or_tty->print_cr("    PRT::Add_reference_work(" PTR_FORMAT "->" PTR_FORMAT").",
  93                              from,
  94                              UseCompressedOops
  95                              ? (void *)oopDesc::load_decode_heap_oop((narrowOop*)from)
  96                              : (void *)oopDesc::load_decode_heap_oop((oop*)from));
  97     }
  98 
  99     HeapRegion* loc_hr = hr();
 100     // If the test below fails, then this table was reused concurrently
 101     // with this operation.  This is OK, since the old table was coarsened,
 102     // and adding a bit to the new table is never incorrect.
 103     // If the table used to belong to a continues humongous region and is
 104     // now reused for the corresponding start humongous region, we need to
 105     // make sure that we detect this. Thus, we call is_in_reserved_raw()
 106     // instead of just is_in_reserved() here.
 107     if (loc_hr->is_in_reserved_raw(from)) {
 108       size_t hw_offset = pointer_delta((HeapWord*)from, loc_hr->bottom());
 109       CardIdx_t from_card = (CardIdx_t)
 110           hw_offset >> (CardTableModRefBS::card_shift - LogHeapWordSize);
 111 
 112       assert(0 <= from_card && (size_t)from_card < HeapRegion::CardsPerRegion,
 113              "Must be in range.");
 114       add_card_work(from_card, par);
 115     }
 116   }
 117 
 118 public:
 119 
 120   HeapRegion* hr() const { return _hr; }
 121 
 122   jint occupied() const {
 123     // Overkill, but if we ever need it...
 124     // guarantee(_occupied == _bm.count_one_bits(), "Check");
 125     return _occupied;
 126   }
 127 
 128   void init(HeapRegion* hr, bool clear_links_to_all_list) {
 129     if (clear_links_to_all_list) {
 130       set_next(NULL);
 131       set_prev(NULL);
 132     }
 133     _hr = hr;
 134     _collision_list_next = NULL;
 135     _occupied = 0;
 136     _bm.clear();
 137   }
 138 
 139   void add_reference(OopOrNarrowOopStar from) {
 140     add_reference_work(from, /*parallel*/ true);
 141   }
 142 
 143   void seq_add_reference(OopOrNarrowOopStar from) {
 144     add_reference_work(from, /*parallel*/ false);
 145   }
 146 
 147   void scrub(CardTableModRefBS* ctbs, BitMap* card_bm) {
 148     HeapWord* hr_bot = hr()->bottom();
 149     size_t hr_first_card_index = ctbs->index_for(hr_bot);
 150     bm()->set_intersection_at_offset(*card_bm, hr_first_card_index);
 151     recount_occupied();
 152   }
 153 
 154   void add_card(CardIdx_t from_card_index) {
 155     add_card_work(from_card_index, /*parallel*/ true);
 156   }
 157 
 158   void seq_add_card(CardIdx_t from_card_index) {
 159     add_card_work(from_card_index, /*parallel*/ false);
 160   }
 161 
 162   // (Destructively) union the bitmap of the current table into the given
 163   // bitmap (which is assumed to be of the same size.)
 164   void union_bitmap_into(BitMap* bm) {
 165     bm->set_union(_bm);
 166   }
 167 
 168   // Mem size in bytes.
 169   size_t mem_size() const {
 170     return sizeof(this) + _bm.size_in_words() * HeapWordSize;
 171   }
 172 
 173   // Requires "from" to be in "hr()".
 174   bool contains_reference(OopOrNarrowOopStar from) const {
 175     assert(hr()->is_in_reserved(from), "Precondition.");
 176     size_t card_ind = pointer_delta(from, hr()->bottom(),
 177                                     CardTableModRefBS::card_size);
 178     return _bm.at(card_ind);
 179   }
 180 
 181   // Bulk-free the PRTs from prt to last, assumes that they are
 182   // linked together using their _next field.
 183   static void bulk_free(PerRegionTable* prt, PerRegionTable* last) {
 184     while (true) {
 185       PerRegionTable* fl = _free_list;
 186       last->set_next(fl);
 187       PerRegionTable* res = (PerRegionTable*) Atomic::cmpxchg_ptr(prt, &_free_list, fl);
 188       if (res == fl) {
 189         return;
 190       }
 191     }
 192     ShouldNotReachHere();
 193   }
 194 
 195   static void free(PerRegionTable* prt) {
 196     bulk_free(prt, prt);
 197   }
 198 
 199   // Returns an initialized PerRegionTable instance.
 200   static PerRegionTable* alloc(HeapRegion* hr) {
 201     PerRegionTable* fl = _free_list;
 202     while (fl != NULL) {
 203       PerRegionTable* nxt = fl->next();
 204       PerRegionTable* res =
 205         (PerRegionTable*)
 206         Atomic::cmpxchg_ptr(nxt, &_free_list, fl);
 207       if (res == fl) {
 208         fl->init(hr, true);
 209         return fl;
 210       } else {
 211         fl = _free_list;
 212       }
 213     }
 214     assert(fl == NULL, "Loop condition.");
 215     return new PerRegionTable(hr);
 216   }
 217 
 218   PerRegionTable* next() const { return _next; }
 219   void set_next(PerRegionTable* next) { _next = next; }
 220   PerRegionTable* prev() const { return _prev; }
 221   void set_prev(PerRegionTable* prev) { _prev = prev; }
 222 
 223   // Accessor and Modification routines for the pointer for the
 224   // singly linked collision list that links the PRTs within the
 225   // OtherRegionsTable::_fine_grain_regions hash table.
 226   //
 227   // It might be useful to also make the collision list doubly linked
 228   // to avoid iteration over the collisions list during scrubbing/deletion.
 229   // OTOH there might not be many collisions.
 230 
 231   PerRegionTable* collision_list_next() const {
 232     return _collision_list_next;
 233   }
 234 
 235   void set_collision_list_next(PerRegionTable* next) {
 236     _collision_list_next = next;
 237   }
 238 
 239   PerRegionTable** collision_list_next_addr() {
 240     return &_collision_list_next;
 241   }
 242 
 243   static size_t fl_mem_size() {
 244     PerRegionTable* cur = _free_list;
 245     size_t res = 0;
 246     while (cur != NULL) {
 247       res += cur->mem_size();
 248       cur = cur->next();
 249     }
 250     return res;
 251   }
 252 
 253   static void test_fl_mem_size();
 254 };
 255 
 256 PerRegionTable* PerRegionTable::_free_list = NULL;
 257 
 258 size_t OtherRegionsTable::_max_fine_entries = 0;
 259 size_t OtherRegionsTable::_mod_max_fine_entries_mask = 0;
 260 size_t OtherRegionsTable::_fine_eviction_stride = 0;
 261 size_t OtherRegionsTable::_fine_eviction_sample_size = 0;
 262 
 263 OtherRegionsTable::OtherRegionsTable(HeapRegion* hr, Mutex* m) :
 264   _g1h(G1CollectedHeap::heap()),
 265   _hr(hr), _m(m),
 266   _coarse_map(G1CollectedHeap::heap()->max_regions(),
 267               false /* in-resource-area */),
 268   _fine_grain_regions(NULL),
 269   _first_all_fine_prts(NULL), _last_all_fine_prts(NULL),
 270   _n_fine_entries(0), _n_coarse_entries(0),
 271   _fine_eviction_start(0),
 272   _sparse_table(hr)
 273 {
 274   typedef PerRegionTable* PerRegionTablePtr;
 275 
 276   if (_max_fine_entries == 0) {
 277     assert(_mod_max_fine_entries_mask == 0, "Both or none.");
 278     size_t max_entries_log = (size_t)log2_long((jlong)G1RSetRegionEntries);
 279     _max_fine_entries = (size_t)1 << max_entries_log;
 280     _mod_max_fine_entries_mask = _max_fine_entries - 1;
 281 
 282     assert(_fine_eviction_sample_size == 0
 283            && _fine_eviction_stride == 0, "All init at same time.");
 284     _fine_eviction_sample_size = MAX2((size_t)4, max_entries_log);
 285     _fine_eviction_stride = _max_fine_entries / _fine_eviction_sample_size;
 286   }
 287 
 288   _fine_grain_regions = NEW_C_HEAP_ARRAY3(PerRegionTablePtr, _max_fine_entries,
 289                         mtGC, 0, AllocFailStrategy::RETURN_NULL);
 290 
 291   if (_fine_grain_regions == NULL) {
 292     vm_exit_out_of_memory(sizeof(void*)*_max_fine_entries, OOM_MALLOC_ERROR,
 293                           "Failed to allocate _fine_grain_entries.");
 294   }
 295 
 296   for (size_t i = 0; i < _max_fine_entries; i++) {
 297     _fine_grain_regions[i] = NULL;
 298   }
 299 }
 300 
 301 void OtherRegionsTable::link_to_all(PerRegionTable* prt) {
 302   // We always append to the beginning of the list for convenience;
 303   // the order of entries in this list does not matter.
 304   if (_first_all_fine_prts != NULL) {
 305     assert(_first_all_fine_prts->prev() == NULL, "invariant");
 306     _first_all_fine_prts->set_prev(prt);
 307     prt->set_next(_first_all_fine_prts);
 308   } else {
 309     // this is the first element we insert. Adjust the "last" pointer
 310     _last_all_fine_prts = prt;
 311     assert(prt->next() == NULL, "just checking");
 312   }
 313   // the new element is always the first element without a predecessor
 314   prt->set_prev(NULL);
 315   _first_all_fine_prts = prt;
 316 
 317   assert(prt->prev() == NULL, "just checking");
 318   assert(_first_all_fine_prts == prt, "just checking");
 319   assert((_first_all_fine_prts == NULL && _last_all_fine_prts == NULL) ||
 320          (_first_all_fine_prts != NULL && _last_all_fine_prts != NULL),
 321          "just checking");
 322   assert(_last_all_fine_prts == NULL || _last_all_fine_prts->next() == NULL,
 323          "just checking");
 324   assert(_first_all_fine_prts == NULL || _first_all_fine_prts->prev() == NULL,
 325          "just checking");
 326 }
 327 
 328 void OtherRegionsTable::unlink_from_all(PerRegionTable* prt) {
 329   if (prt->prev() != NULL) {
 330     assert(_first_all_fine_prts != prt, "just checking");
 331     prt->prev()->set_next(prt->next());
 332     // removing the last element in the list?
 333     if (_last_all_fine_prts == prt) {
 334       _last_all_fine_prts = prt->prev();
 335     }
 336   } else {
 337     assert(_first_all_fine_prts == prt, "just checking");
 338     _first_all_fine_prts = prt->next();
 339     // list is empty now?
 340     if (_first_all_fine_prts == NULL) {
 341       _last_all_fine_prts = NULL;
 342     }
 343   }
 344 
 345   if (prt->next() != NULL) {
 346     prt->next()->set_prev(prt->prev());
 347   }
 348 
 349   prt->set_next(NULL);
 350   prt->set_prev(NULL);
 351 
 352   assert((_first_all_fine_prts == NULL && _last_all_fine_prts == NULL) ||
 353          (_first_all_fine_prts != NULL && _last_all_fine_prts != NULL),
 354          "just checking");
 355   assert(_last_all_fine_prts == NULL || _last_all_fine_prts->next() == NULL,
 356          "just checking");
 357   assert(_first_all_fine_prts == NULL || _first_all_fine_prts->prev() == NULL,
 358          "just checking");
 359 }
 360 
 361 int**  FromCardCache::_cache = NULL;
 362 uint   FromCardCache::_max_regions = 0;
 363 size_t FromCardCache::_static_mem_size = 0;
 364 
 365 void FromCardCache::initialize(uint n_par_rs, uint max_num_regions) {
 366   guarantee(_cache == NULL, "Should not call this multiple times");
 367 
 368   _max_regions = max_num_regions;
 369   _cache = Padded2DArray<int, mtGC>::create_unfreeable(n_par_rs,
 370                                                        _max_regions,
 371                                                        &_static_mem_size);
 372 
 373   for (uint i = 0; i < n_par_rs; i++) {
 374     for (uint j = 0; j < _max_regions; j++) {
 375       set(i, j, InvalidCard);
 376     }
 377   }
 378 }
 379 
 380 void FromCardCache::shrink(uint new_num_regions) {
 381   for (uint i = 0; i < HeapRegionRemSet::num_par_rem_sets(); i++) {
 382     assert(new_num_regions <= _max_regions, "Must be within max.");
 383     for (uint j = new_num_regions; j < _max_regions; j++) {
 384       set(i, j, InvalidCard);
 385     }
 386   }
 387 }
 388 
 389 #ifndef PRODUCT
 390 void FromCardCache::print(outputStream* out) {
 391   for (uint i = 0; i < HeapRegionRemSet::num_par_rem_sets(); i++) {
 392     for (uint j = 0; j < _max_regions; j++) {
 393       out->print_cr("_from_card_cache[%u][%u] = %d.",
 394                     i, j, at(i, j));
 395     }
 396   }
 397 }
 398 #endif
 399 
 400 void FromCardCache::clear(uint region_idx) {
 401   uint num_par_remsets = HeapRegionRemSet::num_par_rem_sets();
 402   for (uint i = 0; i < num_par_remsets; i++) {
 403     set(i, region_idx, InvalidCard);
 404   }
 405 }
 406 
 407 void OtherRegionsTable::init_from_card_cache(uint max_regions) {
 408   FromCardCache::initialize(HeapRegionRemSet::num_par_rem_sets(), max_regions);
 409 }
 410 
 411 void OtherRegionsTable::shrink_from_card_cache(uint new_num_regions) {
 412   FromCardCache::shrink(new_num_regions);
 413 }
 414 
 415 void OtherRegionsTable::print_from_card_cache() {
 416   FromCardCache::print();
 417 }
 418 
 419 void OtherRegionsTable::add_reference(OopOrNarrowOopStar from, int tid) {
 420   uint cur_hrs_ind = hr()->hrs_index();
 421 
 422   if (G1TraceHeapRegionRememberedSet) {
 423     gclog_or_tty->print_cr("ORT::add_reference_work(" PTR_FORMAT "->" PTR_FORMAT ").",
 424                                                     from,
 425                                                     UseCompressedOops
 426                                                     ? (void *)oopDesc::load_decode_heap_oop((narrowOop*)from)
 427                                                     : (void *)oopDesc::load_decode_heap_oop((oop*)from));
 428   }
 429 
 430   int from_card = (int)(uintptr_t(from) >> CardTableModRefBS::card_shift);
 431 
 432   if (G1TraceHeapRegionRememberedSet) {
 433     gclog_or_tty->print_cr("Table for [" PTR_FORMAT "...): card %d (cache = %d)",
 434                   hr()->bottom(), from_card,
 435                   FromCardCache::at((uint)tid, cur_hrs_ind));
 436   }
 437 
 438   if (FromCardCache::contains_or_replace((uint)tid, cur_hrs_ind, from_card)) {
 439     if (G1TraceHeapRegionRememberedSet) {
 440       gclog_or_tty->print_cr("  from-card cache hit.");
 441     }
 442     assert(contains_reference(from), "We just added it!");
 443     return;
 444   }
 445 
 446   // Note that this may be a continued H region.
 447   HeapRegion* from_hr = _g1h->heap_region_containing_raw(from);
 448   RegionIdx_t from_hrs_ind = (RegionIdx_t) from_hr->hrs_index();
 449 
 450   // If the region is already coarsened, return.
 451   if (_coarse_map.at(from_hrs_ind)) {
 452     if (G1TraceHeapRegionRememberedSet) {
 453       gclog_or_tty->print_cr("  coarse map hit.");
 454     }
 455     assert(contains_reference(from), "We just added it!");
 456     return;
 457   }
 458 
 459   // Otherwise find a per-region table to add it to.
 460   size_t ind = from_hrs_ind & _mod_max_fine_entries_mask;
 461   PerRegionTable* prt = find_region_table(ind, from_hr);
 462   if (prt == NULL) {
 463     MutexLockerEx x(_m, Mutex::_no_safepoint_check_flag);
 464     // Confirm that it's really not there...
 465     prt = find_region_table(ind, from_hr);
 466     if (prt == NULL) {
 467 
 468       uintptr_t from_hr_bot_card_index =
 469         uintptr_t(from_hr->bottom())
 470           >> CardTableModRefBS::card_shift;
 471       CardIdx_t card_index = from_card - from_hr_bot_card_index;
 472       assert(0 <= card_index && (size_t)card_index < HeapRegion::CardsPerRegion,
 473              "Must be in range.");
 474       if (G1HRRSUseSparseTable &&
 475           _sparse_table.add_card(from_hrs_ind, card_index)) {
 476         if (G1RecordHRRSOops) {
 477           HeapRegionRemSet::record(hr(), from);
 478           if (G1TraceHeapRegionRememberedSet) {
 479             gclog_or_tty->print("   Added card " PTR_FORMAT " to region "
 480                                 "[" PTR_FORMAT "...) for ref " PTR_FORMAT ".\n",
 481                                 align_size_down(uintptr_t(from),
 482                                                 CardTableModRefBS::card_size),
 483                                 hr()->bottom(), from);
 484           }
 485         }
 486         if (G1TraceHeapRegionRememberedSet) {
 487           gclog_or_tty->print_cr("   added card to sparse table.");
 488         }
 489         assert(contains_reference_locked(from), "We just added it!");
 490         return;
 491       } else {
 492         if (G1TraceHeapRegionRememberedSet) {
 493           gclog_or_tty->print_cr("   [tid %d] sparse table entry "
 494                         "overflow(f: %d, t: %d)",
 495                         tid, from_hrs_ind, cur_hrs_ind);
 496         }
 497       }
 498 
 499       if (_n_fine_entries == _max_fine_entries) {
 500         prt = delete_region_table();
 501         // There is no need to clear the links to the 'all' list here:
 502         // prt will be reused immediately, i.e. remain in the 'all' list.
 503         prt->init(from_hr, false /* clear_links_to_all_list */);
 504       } else {
 505         prt = PerRegionTable::alloc(from_hr);
 506         link_to_all(prt);
 507       }
 508 
 509       PerRegionTable* first_prt = _fine_grain_regions[ind];
 510       prt->set_collision_list_next(first_prt);
 511       _fine_grain_regions[ind] = prt;
 512       _n_fine_entries++;
 513 
 514       if (G1HRRSUseSparseTable) {
 515         // Transfer from sparse to fine-grain.
 516         SparsePRTEntry *sprt_entry = _sparse_table.get_entry(from_hrs_ind);
 517         assert(sprt_entry != NULL, "There should have been an entry");
 518         for (int i = 0; i < SparsePRTEntry::cards_num(); i++) {
 519           CardIdx_t c = sprt_entry->card(i);
 520           if (c != SparsePRTEntry::NullEntry) {
 521             prt->add_card(c);
 522           }
 523         }
 524         // Now we can delete the sparse entry.
 525         bool res = _sparse_table.delete_entry(from_hrs_ind);
 526         assert(res, "It should have been there.");
 527       }
 528     }
 529     assert(prt != NULL && prt->hr() == from_hr, "consequence");
 530   }
 531   // Note that we can't assert "prt->hr() == from_hr", because of the
 532   // possibility of concurrent reuse.  But see head comment of
 533   // OtherRegionsTable for why this is OK.
 534   assert(prt != NULL, "Inv");
 535 
 536   prt->add_reference(from);
 537 
 538   if (G1RecordHRRSOops) {
 539     HeapRegionRemSet::record(hr(), from);
 540     if (G1TraceHeapRegionRememberedSet) {
 541       gclog_or_tty->print("Added card " PTR_FORMAT " to region "
 542                           "[" PTR_FORMAT "...) for ref " PTR_FORMAT ".\n",
 543                           align_size_down(uintptr_t(from),
 544                                           CardTableModRefBS::card_size),
 545                           hr()->bottom(), from);
 546     }
 547   }
 548   assert(contains_reference(from), "We just added it!");
 549 }
 550 
 551 PerRegionTable*
 552 OtherRegionsTable::find_region_table(size_t ind, HeapRegion* hr) const {
 553   assert(0 <= ind && ind < _max_fine_entries, "Preconditions.");
 554   PerRegionTable* prt = _fine_grain_regions[ind];
 555   while (prt != NULL && prt->hr() != hr) {
 556     prt = prt->collision_list_next();
 557   }
 558   // Loop postcondition is the method postcondition.
 559   return prt;
 560 }
 561 
 562 jint OtherRegionsTable::_n_coarsenings = 0;
 563 
 564 PerRegionTable* OtherRegionsTable::delete_region_table() {
 565   assert(_m->owned_by_self(), "Precondition");
 566   assert(_n_fine_entries == _max_fine_entries, "Precondition");
 567   PerRegionTable* max = NULL;
 568   jint max_occ = 0;
 569   PerRegionTable** max_prev;
 570   size_t max_ind;
 571 
 572   size_t i = _fine_eviction_start;
 573   for (size_t k = 0; k < _fine_eviction_sample_size; k++) {
 574     size_t ii = i;
 575     // Make sure we get a non-NULL sample.
 576     while (_fine_grain_regions[ii] == NULL) {
 577       ii++;
 578       if (ii == _max_fine_entries) ii = 0;
 579       guarantee(ii != i, "We must find one.");
 580     }
 581     PerRegionTable** prev = &_fine_grain_regions[ii];
 582     PerRegionTable* cur = *prev;
 583     while (cur != NULL) {
 584       jint cur_occ = cur->occupied();
 585       if (max == NULL || cur_occ > max_occ) {
 586         max = cur;
 587         max_prev = prev;
 588         max_ind = i;
 589         max_occ = cur_occ;
 590       }
 591       prev = cur->collision_list_next_addr();
 592       cur = cur->collision_list_next();
 593     }
 594     i = i + _fine_eviction_stride;
 595     if (i >= _n_fine_entries) i = i - _n_fine_entries;
 596   }
 597 
 598   _fine_eviction_start++;
 599 
 600   if (_fine_eviction_start >= _n_fine_entries) {
 601     _fine_eviction_start -= _n_fine_entries;
 602   }
 603 
 604   guarantee(max != NULL, "Since _n_fine_entries > 0");
 605 
 606   // Set the corresponding coarse bit.
 607   size_t max_hrs_index = (size_t) max->hr()->hrs_index();
 608   if (!_coarse_map.at(max_hrs_index)) {
 609     _coarse_map.at_put(max_hrs_index, true);
 610     _n_coarse_entries++;
 611     if (G1TraceHeapRegionRememberedSet) {
 612       gclog_or_tty->print("Coarsened entry in region [" PTR_FORMAT "...] "
 613                  "for region [" PTR_FORMAT "...] (%d coarse entries).\n",
 614                  hr()->bottom(),
 615                  max->hr()->bottom(),
 616                  _n_coarse_entries);
 617     }
 618   }
 619 
 620   // Unsplice.
 621   *max_prev = max->collision_list_next();
 622   Atomic::inc(&_n_coarsenings);
 623   _n_fine_entries--;
 624   return max;
 625 }
 626 
 627 
 628 // At present, this must be called stop-world single-threaded.
 629 void OtherRegionsTable::scrub(CardTableModRefBS* ctbs,
 630                               BitMap* region_bm, BitMap* card_bm) {
 631   // First eliminated garbage regions from the coarse map.
 632   if (G1RSScrubVerbose) {
 633     gclog_or_tty->print_cr("Scrubbing region %u:", hr()->hrs_index());
 634   }
 635 
 636   assert(_coarse_map.size() == region_bm->size(), "Precondition");
 637   if (G1RSScrubVerbose) {
 638     gclog_or_tty->print("   Coarse map: before = "SIZE_FORMAT"...",
 639                         _n_coarse_entries);
 640   }
 641   _coarse_map.set_intersection(*region_bm);
 642   _n_coarse_entries = _coarse_map.count_one_bits();
 643   if (G1RSScrubVerbose) {
 644     gclog_or_tty->print_cr("   after = "SIZE_FORMAT".", _n_coarse_entries);
 645   }
 646 
 647   // Now do the fine-grained maps.
 648   for (size_t i = 0; i < _max_fine_entries; i++) {
 649     PerRegionTable* cur = _fine_grain_regions[i];
 650     PerRegionTable** prev = &_fine_grain_regions[i];
 651     while (cur != NULL) {
 652       PerRegionTable* nxt = cur->collision_list_next();
 653       // If the entire region is dead, eliminate.
 654       if (G1RSScrubVerbose) {
 655         gclog_or_tty->print_cr("     For other region %u:",
 656                                cur->hr()->hrs_index());
 657       }
 658       if (!region_bm->at((size_t) cur->hr()->hrs_index())) {
 659         *prev = nxt;
 660         cur->set_collision_list_next(NULL);
 661         _n_fine_entries--;
 662         if (G1RSScrubVerbose) {
 663           gclog_or_tty->print_cr("          deleted via region map.");
 664         }
 665         unlink_from_all(cur);
 666         PerRegionTable::free(cur);
 667       } else {
 668         // Do fine-grain elimination.
 669         if (G1RSScrubVerbose) {
 670           gclog_or_tty->print("          occ: before = %4d.", cur->occupied());
 671         }
 672         cur->scrub(ctbs, card_bm);
 673         if (G1RSScrubVerbose) {
 674           gclog_or_tty->print_cr("          after = %4d.", cur->occupied());
 675         }
 676         // Did that empty the table completely?
 677         if (cur->occupied() == 0) {
 678           *prev = nxt;
 679           cur->set_collision_list_next(NULL);
 680           _n_fine_entries--;
 681           unlink_from_all(cur);
 682           PerRegionTable::free(cur);
 683         } else {
 684           prev = cur->collision_list_next_addr();
 685         }
 686       }
 687       cur = nxt;
 688     }
 689   }
 690   // Since we may have deleted a from_card_cache entry from the RS, clear
 691   // the FCC.
 692   clear_fcc();
 693 }
 694 
 695 
 696 size_t OtherRegionsTable::occupied() const {
 697   size_t sum = occ_fine();
 698   sum += occ_sparse();
 699   sum += occ_coarse();
 700   return sum;
 701 }
 702 
 703 size_t OtherRegionsTable::occ_fine() const {
 704   size_t sum = 0;
 705 
 706   size_t num = 0;
 707   PerRegionTable * cur = _first_all_fine_prts;
 708   while (cur != NULL) {
 709     sum += cur->occupied();
 710     cur = cur->next();
 711     num++;
 712   }
 713   guarantee(num == _n_fine_entries, "just checking");
 714   return sum;
 715 }
 716 
 717 size_t OtherRegionsTable::occ_coarse() const {
 718   return (_n_coarse_entries * HeapRegion::CardsPerRegion);
 719 }
 720 
 721 size_t OtherRegionsTable::occ_sparse() const {
 722   return _sparse_table.occupied();
 723 }
 724 
 725 size_t OtherRegionsTable::mem_size() const {
 726   size_t sum = 0;
 727   // all PRTs are of the same size so it is sufficient to query only one of them.
 728   if (_first_all_fine_prts != NULL) {
 729     assert(_last_all_fine_prts != NULL &&
 730       _first_all_fine_prts->mem_size() == _last_all_fine_prts->mem_size(), "check that mem_size() is constant");
 731     sum += _first_all_fine_prts->mem_size() * _n_fine_entries;
 732   }
 733   sum += (sizeof(PerRegionTable*) * _max_fine_entries);
 734   sum += (_coarse_map.size_in_words() * HeapWordSize);
 735   sum += (_sparse_table.mem_size());
 736   sum += sizeof(*this) - sizeof(_sparse_table); // Avoid double counting above.
 737   return sum;
 738 }
 739 
 740 size_t OtherRegionsTable::static_mem_size() {
 741   return FromCardCache::static_mem_size();
 742 }
 743 
 744 size_t OtherRegionsTable::fl_mem_size() {
 745   return PerRegionTable::fl_mem_size();
 746 }
 747 
 748 void OtherRegionsTable::clear_fcc() {
 749   FromCardCache::clear(hr()->hrs_index());
 750 }
 751 
 752 void OtherRegionsTable::clear() {
 753   // if there are no entries, skip this step
 754   if (_first_all_fine_prts != NULL) {
 755     guarantee(_first_all_fine_prts != NULL && _last_all_fine_prts != NULL, "just checking");
 756     PerRegionTable::bulk_free(_first_all_fine_prts, _last_all_fine_prts);
 757     memset(_fine_grain_regions, 0, _max_fine_entries * sizeof(_fine_grain_regions[0]));
 758   } else {
 759     guarantee(_first_all_fine_prts == NULL && _last_all_fine_prts == NULL, "just checking");
 760   }
 761 
 762   _first_all_fine_prts = _last_all_fine_prts = NULL;
 763   _sparse_table.clear();
 764   _coarse_map.clear();
 765   _n_fine_entries = 0;
 766   _n_coarse_entries = 0;
 767 
 768   clear_fcc();
 769 }
 770 
 771 bool OtherRegionsTable::del_single_region_table(size_t ind,
 772                                                 HeapRegion* hr) {
 773   assert(0 <= ind && ind < _max_fine_entries, "Preconditions.");
 774   PerRegionTable** prev_addr = &_fine_grain_regions[ind];
 775   PerRegionTable* prt = *prev_addr;
 776   while (prt != NULL && prt->hr() != hr) {
 777     prev_addr = prt->collision_list_next_addr();
 778     prt = prt->collision_list_next();
 779   }
 780   if (prt != NULL) {
 781     assert(prt->hr() == hr, "Loop postcondition.");
 782     *prev_addr = prt->collision_list_next();
 783     unlink_from_all(prt);
 784     PerRegionTable::free(prt);
 785     _n_fine_entries--;
 786     return true;
 787   } else {
 788     return false;
 789   }
 790 }
 791 
 792 bool OtherRegionsTable::contains_reference(OopOrNarrowOopStar from) const {
 793   // Cast away const in this case.
 794   MutexLockerEx x((Mutex*)_m, Mutex::_no_safepoint_check_flag);
 795   return contains_reference_locked(from);
 796 }
 797 
 798 bool OtherRegionsTable::contains_reference_locked(OopOrNarrowOopStar from) const {
 799   HeapRegion* hr = _g1h->heap_region_containing_raw(from);
 800   if (hr == NULL) return false;
 801   RegionIdx_t hr_ind = (RegionIdx_t) hr->hrs_index();
 802   // Is this region in the coarse map?
 803   if (_coarse_map.at(hr_ind)) return true;
 804 
 805   PerRegionTable* prt = find_region_table(hr_ind & _mod_max_fine_entries_mask,
 806                                      hr);
 807   if (prt != NULL) {
 808     return prt->contains_reference(from);
 809 
 810   } else {
 811     uintptr_t from_card =
 812       (uintptr_t(from) >> CardTableModRefBS::card_shift);
 813     uintptr_t hr_bot_card_index =
 814       uintptr_t(hr->bottom()) >> CardTableModRefBS::card_shift;
 815     assert(from_card >= hr_bot_card_index, "Inv");
 816     CardIdx_t card_index = from_card - hr_bot_card_index;
 817     assert(0 <= card_index && (size_t)card_index < HeapRegion::CardsPerRegion,
 818            "Must be in range.");
 819     return _sparse_table.contains_card(hr_ind, card_index);
 820   }
 821 }
 822 
 823 void
 824 OtherRegionsTable::do_cleanup_work(HRRSCleanupTask* hrrs_cleanup_task) {
 825   _sparse_table.do_cleanup_work(hrrs_cleanup_task);
 826 }
 827 
 828 // Determines how many threads can add records to an rset in parallel.
 829 // This can be done by either mutator threads together with the
 830 // concurrent refinement threads or GC threads.
 831 uint HeapRegionRemSet::num_par_rem_sets() {
 832   return MAX2(DirtyCardQueueSet::num_par_ids() + ConcurrentG1Refine::thread_num(), (uint)ParallelGCThreads);
 833 }
 834 
 835 HeapRegionRemSet::HeapRegionRemSet(G1BlockOffsetSharedArray* bosa,
 836                                    HeapRegion* hr)
 837   : _bosa(bosa),
 838     _m(Mutex::leaf, FormatBuffer<128>("HeapRegionRemSet lock #%u", hr->hrs_index()), true),
 839     _code_roots(), _other_regions(hr, &_m) {
 840   reset_for_par_iteration();
 841 }
 842 
 843 void HeapRegionRemSet::setup_remset_size() {
 844   // Setup sparse and fine-grain tables sizes.
 845   // table_size = base * (log(region_size / 1M) + 1)
 846   const int LOG_M = 20;
 847   int region_size_log_mb = MAX2(HeapRegion::LogOfHRGrainBytes - LOG_M, 0);
 848   if (FLAG_IS_DEFAULT(G1RSetSparseRegionEntries)) {
 849     G1RSetSparseRegionEntries = G1RSetSparseRegionEntriesBase * (region_size_log_mb + 1);
 850   }
 851   if (FLAG_IS_DEFAULT(G1RSetRegionEntries)) {
 852     G1RSetRegionEntries = G1RSetRegionEntriesBase * (region_size_log_mb + 1);
 853   }
 854   guarantee(G1RSetSparseRegionEntries > 0 && G1RSetRegionEntries > 0 , "Sanity");
 855 }
 856 
 857 bool HeapRegionRemSet::claim_iter() {
 858   if (_iter_state != Unclaimed) return false;
 859   jint res = Atomic::cmpxchg(Claimed, (jint*)(&_iter_state), Unclaimed);
 860   return (res == Unclaimed);
 861 }
 862 
 863 void HeapRegionRemSet::set_iter_complete() {
 864   _iter_state = Complete;
 865 }
 866 
 867 bool HeapRegionRemSet::iter_is_complete() {
 868   return _iter_state == Complete;
 869 }
 870 
 871 #ifndef PRODUCT
 872 void HeapRegionRemSet::print() {
 873   HeapRegionRemSetIterator iter(this);
 874   size_t card_index;
 875   while (iter.has_next(card_index)) {
 876     HeapWord* card_start =
 877       G1CollectedHeap::heap()->bot_shared()->address_for_index(card_index);
 878     gclog_or_tty->print_cr("  Card " PTR_FORMAT, card_start);
 879   }
 880   if (iter.n_yielded() != occupied()) {
 881     gclog_or_tty->print_cr("Yielded disagrees with occupied:");
 882     gclog_or_tty->print_cr("  %6d yielded (%6d coarse, %6d fine).",
 883                   iter.n_yielded(),
 884                   iter.n_yielded_coarse(), iter.n_yielded_fine());
 885     gclog_or_tty->print_cr("  %6d occ     (%6d coarse, %6d fine).",
 886                   occupied(), occ_coarse(), occ_fine());
 887   }
 888   guarantee(iter.n_yielded() == occupied(),
 889             "We should have yielded all the represented cards.");
 890 }
 891 #endif
 892 
 893 void HeapRegionRemSet::cleanup() {
 894   SparsePRT::cleanup_all();
 895 }
 896 
 897 void HeapRegionRemSet::clear() {
 898   MutexLockerEx x(&_m, Mutex::_no_safepoint_check_flag);
 899   clear_locked();
 900 }
 901 
 902 void HeapRegionRemSet::clear_locked() {
 903   _code_roots.clear();
 904   _other_regions.clear();
 905   assert(occupied_locked() == 0, "Should be clear.");
 906   reset_for_par_iteration();
 907 }
 908 
 909 void HeapRegionRemSet::reset_for_par_iteration() {
 910   _iter_state = Unclaimed;
 911   _iter_claimed = 0;
 912   // It's good to check this to make sure that the two methods are in sync.
 913   assert(verify_ready_for_par_iteration(), "post-condition");
 914 }
 915 
 916 void HeapRegionRemSet::scrub(CardTableModRefBS* ctbs,
 917                              BitMap* region_bm, BitMap* card_bm) {
 918   _other_regions.scrub(ctbs, region_bm, card_bm);
 919 }
 920 
 921 // Code roots support
 922 
 923 void HeapRegionRemSet::add_strong_code_root(nmethod* nm) {
 924   assert(nm != NULL, "sanity");
 925   _code_roots.add(nm);
 926 }
 927 
 928 void HeapRegionRemSet::remove_strong_code_root(nmethod* nm) {
 929   assert(nm != NULL, "sanity");
 930   _code_roots.remove(nm);
 931   // Check that there were no duplicates
 932   guarantee(!_code_roots.contains(nm), "duplicate entry found");
 933 }
 934 
 935 class NMethodMigrationOopClosure : public OopClosure {
 936   G1CollectedHeap* _g1h;
 937   HeapRegion* _from;
 938   nmethod* _nm;
 939 
 940   uint _num_self_forwarded;
 941 
 942   template <class T> void do_oop_work(T* p) {
 943     T heap_oop = oopDesc::load_heap_oop(p);
 944     if (!oopDesc::is_null(heap_oop)) {
 945       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
 946       if (_from->is_in(obj)) {
 947         // Reference still points into the source region.
 948         // Since roots are immediately evacuated this means that
 949         // we must have self forwarded the object
 950         assert(obj->is_forwarded(),
 951                err_msg("code roots should be immediately evacuated. "
 952                        "Ref: "PTR_FORMAT", "
 953                        "Obj: "PTR_FORMAT", "
 954                        "Region: "HR_FORMAT,
 955                        p, (void*) obj, HR_FORMAT_PARAMS(_from)));
 956         assert(obj->forwardee() == obj,
 957                err_msg("not self forwarded? obj = "PTR_FORMAT, (void*)obj));
 958 
 959         // The object has been self forwarded.
 960         // Note, if we're during an initial mark pause, there is
 961         // no need to explicitly mark object. It will be marked
 962         // during the regular evacuation failure handling code.
 963         _num_self_forwarded++;
 964       } else {
 965         // The reference points into a promotion or to-space region
 966         HeapRegion* to = _g1h->heap_region_containing(obj);
 967         to->rem_set()->add_strong_code_root(_nm);
 968       }
 969     }
 970   }
 971 
 972 public:
 973   NMethodMigrationOopClosure(G1CollectedHeap* g1h, HeapRegion* from, nmethod* nm):
 974     _g1h(g1h), _from(from), _nm(nm), _num_self_forwarded(0) {}
 975 
 976   void do_oop(narrowOop* p) { do_oop_work(p); }
 977   void do_oop(oop* p)       { do_oop_work(p); }
 978 
 979   uint retain() { return _num_self_forwarded > 0; }
 980 };
 981 
 982 void HeapRegionRemSet::migrate_strong_code_roots() {
 983   assert(hr()->in_collection_set(), "only collection set regions");
 984   assert(!hr()->isHumongous(),
 985          err_msg("humongous region "HR_FORMAT" should not have been added to the collection set",
 986                  HR_FORMAT_PARAMS(hr())));
 987 
 988   ResourceMark rm;
 989 
 990   // List of code blobs to retain for this region
 991   GrowableArray<nmethod*> to_be_retained(10);
 992   G1CollectedHeap* g1h = G1CollectedHeap::heap();
 993 
 994   while (!_code_roots.is_empty()) {
 995     nmethod *nm = _code_roots.pop();
 996     if (nm != NULL) {
 997       NMethodMigrationOopClosure oop_cl(g1h, hr(), nm);
 998       nm->oops_do(&oop_cl);
 999       if (oop_cl.retain()) {
1000         to_be_retained.push(nm);
1001       }
1002     }
1003   }
1004 
1005   // Now push any code roots we need to retain
1006   assert(to_be_retained.is_empty() || hr()->evacuation_failed(),
1007          "Retained nmethod list must be empty or "
1008          "evacuation of this region failed");
1009 
1010   while (to_be_retained.is_nonempty()) {
1011     nmethod* nm = to_be_retained.pop();
1012     assert(nm != NULL, "sanity");
1013     add_strong_code_root(nm);
1014   }
1015 }
1016 
1017 void HeapRegionRemSet::strong_code_roots_do(CodeBlobClosure* blk) const {
1018   _code_roots.nmethods_do(blk);
1019 }
1020 
1021 size_t HeapRegionRemSet::strong_code_roots_mem_size() {
1022   return _code_roots.mem_size();
1023 }
1024 
1025 HeapRegionRemSetIterator:: HeapRegionRemSetIterator(HeapRegionRemSet* hrrs) :
1026   _hrrs(hrrs),
1027   _g1h(G1CollectedHeap::heap()),
1028   _coarse_map(&hrrs->_other_regions._coarse_map),
1029   _bosa(hrrs->bosa()),
1030   _is(Sparse),
1031   // Set these values so that we increment to the first region.
1032   _coarse_cur_region_index(-1),
1033   _coarse_cur_region_cur_card(HeapRegion::CardsPerRegion-1),
1034   _cur_region_cur_card((size_t)HeapRegion::CardsPerRegion),
1035   _fine_cur_prt(NULL),
1036   _n_yielded_coarse(0),
1037   _n_yielded_fine(0),
1038   _n_yielded_sparse(0),
1039   _sparse_iter(&hrrs->_other_regions._sparse_table) {}
1040 
1041 bool HeapRegionRemSetIterator::coarse_has_next(size_t& card_index) {
1042   if (_hrrs->_other_regions._n_coarse_entries == 0) return false;
1043   // Go to the next card.
1044   _coarse_cur_region_cur_card++;
1045   // Was the last the last card in the current region?
1046   if (_coarse_cur_region_cur_card == HeapRegion::CardsPerRegion) {
1047     // Yes: find the next region.  This may leave _coarse_cur_region_index
1048     // Set to the last index, in which case there are no more coarse
1049     // regions.
1050     _coarse_cur_region_index =
1051       (int) _coarse_map->get_next_one_offset(_coarse_cur_region_index + 1);
1052     if ((size_t)_coarse_cur_region_index < _coarse_map->size()) {
1053       _coarse_cur_region_cur_card = 0;
1054       HeapWord* r_bot =
1055         _g1h->region_at((uint) _coarse_cur_region_index)->bottom();
1056       _cur_region_card_offset = _bosa->index_for(r_bot);
1057     } else {
1058       return false;
1059     }
1060   }
1061   // If we didn't return false above, then we can yield a card.
1062   card_index = _cur_region_card_offset + _coarse_cur_region_cur_card;
1063   return true;
1064 }
1065 
1066 bool HeapRegionRemSetIterator::fine_has_next(size_t& card_index) {
1067   if (fine_has_next()) {
1068     _cur_region_cur_card =
1069       _fine_cur_prt->_bm.get_next_one_offset(_cur_region_cur_card + 1);
1070   }
1071   if (_cur_region_cur_card == (size_t)HeapRegion::CardsPerRegion) {
1072     // _fine_cur_prt may still be NULL in case if there are not PRTs at all for
1073     // the remembered set.
1074     if (_fine_cur_prt == NULL || _fine_cur_prt->next() == NULL) {
1075       return false;
1076     }
1077     PerRegionTable* next_prt = _fine_cur_prt->next();
1078     switch_to_next_prt(next_prt);
1079     _cur_region_cur_card = _fine_cur_prt->_bm.get_next_one_offset(_cur_region_cur_card + 1);
1080   }
1081 
1082   card_index = _cur_region_card_offset + _cur_region_cur_card;
1083   guarantee(_cur_region_cur_card < HeapRegion::CardsPerRegion, "card index must be within heap");
1084   return true;
1085 }
1086 
1087 bool HeapRegionRemSetIterator::fine_has_next() {
1088   return _cur_region_cur_card != (size_t)HeapRegion::CardsPerRegion;
1089 }
1090 
1091 void HeapRegionRemSetIterator::switch_to_next_prt(PerRegionTable* prt) {
1092   assert(prt != NULL, "Cannot switch to NULL prt");
1093   _fine_cur_prt = prt;
1094 
1095   HeapWord* r_bot = _fine_cur_prt->hr()->bottom();
1096   _cur_region_card_offset = _bosa->index_for(r_bot);
1097 
1098   _cur_region_cur_card = (size_t)-1;
1099 }
1100 
1101 bool HeapRegionRemSetIterator::has_next(size_t& card_index) {
1102   switch (_is) {
1103   case Sparse: {
1104     if (_sparse_iter.has_next(card_index)) {
1105       _n_yielded_sparse++;
1106       return true;
1107     }
1108     // Otherwise, deliberate fall-through
1109     _is = Fine;
1110     PerRegionTable* initial_fine_prt = _hrrs->_other_regions._first_all_fine_prts;
1111     if (initial_fine_prt != NULL) {
1112       switch_to_next_prt(_hrrs->_other_regions._first_all_fine_prts);
1113     }
1114   }
1115   case Fine:
1116     if (fine_has_next(card_index)) {
1117       _n_yielded_fine++;
1118       return true;
1119     }
1120     // Otherwise, deliberate fall-through
1121     _is = Coarse;
1122   case Coarse:
1123     if (coarse_has_next(card_index)) {
1124       _n_yielded_coarse++;
1125       return true;
1126     }
1127     // Otherwise...
1128     break;
1129   }
1130   assert(ParallelGCThreads > 1 ||
1131          n_yielded() == _hrrs->occupied(),
1132          "Should have yielded all the cards in the rem set "
1133          "(in the non-par case).");
1134   return false;
1135 }
1136 
1137 
1138 
1139 OopOrNarrowOopStar* HeapRegionRemSet::_recorded_oops = NULL;
1140 HeapWord**          HeapRegionRemSet::_recorded_cards = NULL;
1141 HeapRegion**        HeapRegionRemSet::_recorded_regions = NULL;
1142 int                 HeapRegionRemSet::_n_recorded = 0;
1143 
1144 HeapRegionRemSet::Event* HeapRegionRemSet::_recorded_events = NULL;
1145 int*         HeapRegionRemSet::_recorded_event_index = NULL;
1146 int          HeapRegionRemSet::_n_recorded_events = 0;
1147 
1148 void HeapRegionRemSet::record(HeapRegion* hr, OopOrNarrowOopStar f) {
1149   if (_recorded_oops == NULL) {
1150     assert(_n_recorded == 0
1151            && _recorded_cards == NULL
1152            && _recorded_regions == NULL,
1153            "Inv");
1154     _recorded_oops    = NEW_C_HEAP_ARRAY(OopOrNarrowOopStar, MaxRecorded, mtGC);
1155     _recorded_cards   = NEW_C_HEAP_ARRAY(HeapWord*,          MaxRecorded, mtGC);
1156     _recorded_regions = NEW_C_HEAP_ARRAY(HeapRegion*,        MaxRecorded, mtGC);
1157   }
1158   if (_n_recorded == MaxRecorded) {
1159     gclog_or_tty->print_cr("Filled up 'recorded' (%d).", MaxRecorded);
1160   } else {
1161     _recorded_cards[_n_recorded] =
1162       (HeapWord*)align_size_down(uintptr_t(f),
1163                                  CardTableModRefBS::card_size);
1164     _recorded_oops[_n_recorded] = f;
1165     _recorded_regions[_n_recorded] = hr;
1166     _n_recorded++;
1167   }
1168 }
1169 
1170 void HeapRegionRemSet::record_event(Event evnt) {
1171   if (!G1RecordHRRSEvents) return;
1172 
1173   if (_recorded_events == NULL) {
1174     assert(_n_recorded_events == 0
1175            && _recorded_event_index == NULL,
1176            "Inv");
1177     _recorded_events = NEW_C_HEAP_ARRAY(Event, MaxRecordedEvents, mtGC);
1178     _recorded_event_index = NEW_C_HEAP_ARRAY(int, MaxRecordedEvents, mtGC);
1179   }
1180   if (_n_recorded_events == MaxRecordedEvents) {
1181     gclog_or_tty->print_cr("Filled up 'recorded_events' (%d).", MaxRecordedEvents);
1182   } else {
1183     _recorded_events[_n_recorded_events] = evnt;
1184     _recorded_event_index[_n_recorded_events] = _n_recorded;
1185     _n_recorded_events++;
1186   }
1187 }
1188 
1189 void HeapRegionRemSet::print_event(outputStream* str, Event evnt) {
1190   switch (evnt) {
1191   case Event_EvacStart:
1192     str->print("Evac Start");
1193     break;
1194   case Event_EvacEnd:
1195     str->print("Evac End");
1196     break;
1197   case Event_RSUpdateEnd:
1198     str->print("RS Update End");
1199     break;
1200   }
1201 }
1202 
1203 void HeapRegionRemSet::print_recorded() {
1204   int cur_evnt = 0;
1205   Event cur_evnt_kind;
1206   int cur_evnt_ind = 0;
1207   if (_n_recorded_events > 0) {
1208     cur_evnt_kind = _recorded_events[cur_evnt];
1209     cur_evnt_ind = _recorded_event_index[cur_evnt];
1210   }
1211 
1212   for (int i = 0; i < _n_recorded; i++) {
1213     while (cur_evnt < _n_recorded_events && i == cur_evnt_ind) {
1214       gclog_or_tty->print("Event: ");
1215       print_event(gclog_or_tty, cur_evnt_kind);
1216       gclog_or_tty->print_cr("");
1217       cur_evnt++;
1218       if (cur_evnt < MaxRecordedEvents) {
1219         cur_evnt_kind = _recorded_events[cur_evnt];
1220         cur_evnt_ind = _recorded_event_index[cur_evnt];
1221       }
1222     }
1223     gclog_or_tty->print("Added card " PTR_FORMAT " to region [" PTR_FORMAT "...]"
1224                         " for ref " PTR_FORMAT ".\n",
1225                         _recorded_cards[i], _recorded_regions[i]->bottom(),
1226                         _recorded_oops[i]);
1227   }
1228 }
1229 
1230 void HeapRegionRemSet::reset_for_cleanup_tasks() {
1231   SparsePRT::reset_for_cleanup_tasks();
1232 }
1233 
1234 void HeapRegionRemSet::do_cleanup_work(HRRSCleanupTask* hrrs_cleanup_task) {
1235   _other_regions.do_cleanup_work(hrrs_cleanup_task);
1236 }
1237 
1238 void
1239 HeapRegionRemSet::finish_cleanup_task(HRRSCleanupTask* hrrs_cleanup_task) {
1240   SparsePRT::finish_cleanup_task(hrrs_cleanup_task);
1241 }
1242 
1243 #ifndef PRODUCT
1244 void PerRegionTable::test_fl_mem_size() {
1245   PerRegionTable* dummy = alloc(NULL);
1246   free(dummy);
1247   guarantee(dummy->mem_size() == fl_mem_size(), "fl_mem_size() does not return the correct element size");
1248   // try to reset the state
1249   _free_list = NULL;
1250   delete dummy;
1251 }
1252 
1253 void HeapRegionRemSet::test_prt() {
1254   PerRegionTable::test_fl_mem_size();
1255 }
1256 
1257 void HeapRegionRemSet::test() {
1258   os::sleep(Thread::current(), (jlong)5000, false);
1259   G1CollectedHeap* g1h = G1CollectedHeap::heap();
1260 
1261   // Run with "-XX:G1LogRSetRegionEntries=2", so that 1 and 5 end up in same
1262   // hash bucket.
1263   HeapRegion* hr0 = g1h->region_at(0);
1264   HeapRegion* hr1 = g1h->region_at(1);
1265   HeapRegion* hr2 = g1h->region_at(5);
1266   HeapRegion* hr3 = g1h->region_at(6);
1267   HeapRegion* hr4 = g1h->region_at(7);
1268   HeapRegion* hr5 = g1h->region_at(8);
1269 
1270   HeapWord* hr1_start = hr1->bottom();
1271   HeapWord* hr1_mid = hr1_start + HeapRegion::GrainWords/2;
1272   HeapWord* hr1_last = hr1->end() - 1;
1273 
1274   HeapWord* hr2_start = hr2->bottom();
1275   HeapWord* hr2_mid = hr2_start + HeapRegion::GrainWords/2;
1276   HeapWord* hr2_last = hr2->end() - 1;
1277 
1278   HeapWord* hr3_start = hr3->bottom();
1279   HeapWord* hr3_mid = hr3_start + HeapRegion::GrainWords/2;
1280   HeapWord* hr3_last = hr3->end() - 1;
1281 
1282   HeapRegionRemSet* hrrs = hr0->rem_set();
1283 
1284   // Make three references from region 0x101...
1285   hrrs->add_reference((OopOrNarrowOopStar)hr1_start);
1286   hrrs->add_reference((OopOrNarrowOopStar)hr1_mid);
1287   hrrs->add_reference((OopOrNarrowOopStar)hr1_last);
1288 
1289   hrrs->add_reference((OopOrNarrowOopStar)hr2_start);
1290   hrrs->add_reference((OopOrNarrowOopStar)hr2_mid);
1291   hrrs->add_reference((OopOrNarrowOopStar)hr2_last);
1292 
1293   hrrs->add_reference((OopOrNarrowOopStar)hr3_start);
1294   hrrs->add_reference((OopOrNarrowOopStar)hr3_mid);
1295   hrrs->add_reference((OopOrNarrowOopStar)hr3_last);
1296 
1297   // Now cause a coarsening.
1298   hrrs->add_reference((OopOrNarrowOopStar)hr4->bottom());
1299   hrrs->add_reference((OopOrNarrowOopStar)hr5->bottom());
1300 
1301   // Now, does iteration yield these three?
1302   HeapRegionRemSetIterator iter(hrrs);
1303   size_t sum = 0;
1304   size_t card_index;
1305   while (iter.has_next(card_index)) {
1306     HeapWord* card_start =
1307       G1CollectedHeap::heap()->bot_shared()->address_for_index(card_index);
1308     gclog_or_tty->print_cr("  Card " PTR_FORMAT ".", card_start);
1309     sum++;
1310   }
1311   guarantee(sum == 11 - 3 + 2048, "Failure");
1312   guarantee(sum == hrrs->occupied(), "Failure");
1313 }
1314 #endif