1 /*
   2  * Copyright (c) 2001, 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/g1/concurrentG1Refine.hpp"
  27 #include "gc/g1/g1BlockOffsetTable.inline.hpp"
  28 #include "gc/g1/g1CollectedHeap.inline.hpp"
  29 #include "gc/g1/heapRegionManager.inline.hpp"
  30 #include "gc/g1/heapRegionRemSet.hpp"
  31 #include "gc/shared/space.inline.hpp"
  32 #include "memory/allocation.hpp"
  33 #include "memory/padded.inline.hpp"
  34 #include "oops/oop.inline.hpp"
  35 #include "runtime/atomic.inline.hpp"
  36 #include "utilities/bitMap.inline.hpp"
  37 #include "utilities/globalDefinitions.hpp"
  38 #include "utilities/growableArray.hpp"
  39 
  40 class PerRegionTable: public CHeapObj<mtGC> {
  41   friend class OtherRegionsTable;
  42   friend class HeapRegionRemSetIterator;
  43 
  44   HeapRegion*     _hr;
  45   BitMap          _bm;
  46   jint            _occupied;
  47 
  48   // next pointer for free/allocated 'all' list
  49   PerRegionTable* _next;
  50 
  51   // prev pointer for the allocated 'all' list
  52   PerRegionTable* _prev;
  53 
  54   // next pointer in collision list
  55   PerRegionTable * _collision_list_next;
  56 
  57   // Global free list of PRTs
  58   static PerRegionTable* _free_list;
  59 
  60 protected:
  61   // We need access in order to union things into the base table.
  62   BitMap* bm() { return &_bm; }
  63 
  64   void recount_occupied() {
  65     _occupied = (jint) bm()->count_one_bits();
  66   }
  67 
  68   PerRegionTable(HeapRegion* hr) :
  69     _hr(hr),
  70     _occupied(0),
  71     _bm(HeapRegion::CardsPerRegion, false /* in-resource-area */),
  72     _collision_list_next(NULL), _next(NULL), _prev(NULL)
  73   {}
  74 
  75   void add_card_work(CardIdx_t from_card, bool par) {
  76     if (!_bm.at(from_card)) {
  77       if (par) {
  78         if (_bm.par_at_put(from_card, 1)) {
  79           Atomic::inc(&_occupied);
  80         }
  81       } else {
  82         _bm.at_put(from_card, 1);
  83         _occupied++;
  84       }
  85     }
  86   }
  87 
  88   void add_reference_work(OopOrNarrowOopStar from, bool par) {
  89     // Must make this robust in case "from" is not in "_hr", because of
  90     // concurrency.
  91 
  92     HeapRegion* loc_hr = hr();
  93     // If the test below fails, then this table was reused concurrently
  94     // with this operation.  This is OK, since the old table was coarsened,
  95     // and adding a bit to the new table is never incorrect.
  96     // If the table used to belong to a continues humongous region and is
  97     // now reused for the corresponding start humongous region, we need to
  98     // make sure that we detect this. Thus, we call is_in_reserved_raw()
  99     // instead of just is_in_reserved() here.
 100     if (loc_hr->is_in_reserved(from)) {
 101       size_t hw_offset = pointer_delta((HeapWord*)from, loc_hr->bottom());
 102       CardIdx_t from_card = (CardIdx_t)
 103           hw_offset >> (CardTableModRefBS::card_shift - LogHeapWordSize);
 104 
 105       assert(0 <= from_card && (size_t)from_card < HeapRegion::CardsPerRegion,
 106              "Must be in range.");
 107       add_card_work(from_card, par);
 108     }
 109   }
 110 
 111 public:
 112 
 113   HeapRegion* hr() const { return _hr; }
 114 
 115   jint occupied() const {
 116     // Overkill, but if we ever need it...
 117     // guarantee(_occupied == _bm.count_one_bits(), "Check");
 118     return _occupied;
 119   }
 120 
 121   void init(HeapRegion* hr, bool clear_links_to_all_list) {
 122     if (clear_links_to_all_list) {
 123       set_next(NULL);
 124       set_prev(NULL);
 125     }
 126     _hr = hr;
 127     _collision_list_next = NULL;
 128     _occupied = 0;
 129     _bm.clear();
 130   }
 131 
 132   void add_reference(OopOrNarrowOopStar from) {
 133     add_reference_work(from, /*parallel*/ true);
 134   }
 135 
 136   void seq_add_reference(OopOrNarrowOopStar from) {
 137     add_reference_work(from, /*parallel*/ false);
 138   }
 139 
 140   void scrub(CardTableModRefBS* ctbs, BitMap* card_bm) {
 141     HeapWord* hr_bot = hr()->bottom();
 142     size_t hr_first_card_index = ctbs->index_for(hr_bot);
 143     bm()->set_intersection_at_offset(*card_bm, hr_first_card_index);
 144     recount_occupied();
 145   }
 146 
 147   void add_card(CardIdx_t from_card_index) {
 148     add_card_work(from_card_index, /*parallel*/ true);
 149   }
 150 
 151   void seq_add_card(CardIdx_t from_card_index) {
 152     add_card_work(from_card_index, /*parallel*/ false);
 153   }
 154 
 155   // (Destructively) union the bitmap of the current table into the given
 156   // bitmap (which is assumed to be of the same size.)
 157   void union_bitmap_into(BitMap* bm) {
 158     bm->set_union(_bm);
 159   }
 160 
 161   // Mem size in bytes.
 162   size_t mem_size() const {
 163     return sizeof(PerRegionTable) + _bm.size_in_words() * HeapWordSize;
 164   }
 165 
 166   // Requires "from" to be in "hr()".
 167   bool contains_reference(OopOrNarrowOopStar from) const {
 168     assert(hr()->is_in_reserved(from), "Precondition.");
 169     size_t card_ind = pointer_delta(from, hr()->bottom(),
 170                                     CardTableModRefBS::card_size);
 171     return _bm.at(card_ind);
 172   }
 173 
 174   // Bulk-free the PRTs from prt to last, assumes that they are
 175   // linked together using their _next field.
 176   static void bulk_free(PerRegionTable* prt, PerRegionTable* last) {
 177     while (true) {
 178       PerRegionTable* fl = _free_list;
 179       last->set_next(fl);
 180       PerRegionTable* res = (PerRegionTable*) Atomic::cmpxchg_ptr(prt, &_free_list, fl);
 181       if (res == fl) {
 182         return;
 183       }
 184     }
 185     ShouldNotReachHere();
 186   }
 187 
 188   static void free(PerRegionTable* prt) {
 189     bulk_free(prt, prt);
 190   }
 191 
 192   // Returns an initialized PerRegionTable instance.
 193   static PerRegionTable* alloc(HeapRegion* hr) {
 194     PerRegionTable* fl = _free_list;
 195     while (fl != NULL) {
 196       PerRegionTable* nxt = fl->next();
 197       PerRegionTable* res =
 198         (PerRegionTable*)
 199         Atomic::cmpxchg_ptr(nxt, &_free_list, fl);
 200       if (res == fl) {
 201         fl->init(hr, true);
 202         return fl;
 203       } else {
 204         fl = _free_list;
 205       }
 206     }
 207     assert(fl == NULL, "Loop condition.");
 208     return new PerRegionTable(hr);
 209   }
 210 
 211   PerRegionTable* next() const { return _next; }
 212   void set_next(PerRegionTable* next) { _next = next; }
 213   PerRegionTable* prev() const { return _prev; }
 214   void set_prev(PerRegionTable* prev) { _prev = prev; }
 215 
 216   // Accessor and Modification routines for the pointer for the
 217   // singly linked collision list that links the PRTs within the
 218   // OtherRegionsTable::_fine_grain_regions hash table.
 219   //
 220   // It might be useful to also make the collision list doubly linked
 221   // to avoid iteration over the collisions list during scrubbing/deletion.
 222   // OTOH there might not be many collisions.
 223 
 224   PerRegionTable* collision_list_next() const {
 225     return _collision_list_next;
 226   }
 227 
 228   void set_collision_list_next(PerRegionTable* next) {
 229     _collision_list_next = next;
 230   }
 231 
 232   PerRegionTable** collision_list_next_addr() {
 233     return &_collision_list_next;
 234   }
 235 
 236   static size_t fl_mem_size() {
 237     PerRegionTable* cur = _free_list;
 238     size_t res = 0;
 239     while (cur != NULL) {
 240       res += cur->mem_size();
 241       cur = cur->next();
 242     }
 243     return res;
 244   }
 245 
 246   static void test_fl_mem_size();
 247 };
 248 
 249 PerRegionTable* PerRegionTable::_free_list = NULL;
 250 
 251 size_t OtherRegionsTable::_max_fine_entries = 0;
 252 size_t OtherRegionsTable::_mod_max_fine_entries_mask = 0;
 253 size_t OtherRegionsTable::_fine_eviction_stride = 0;
 254 size_t OtherRegionsTable::_fine_eviction_sample_size = 0;
 255 
 256 OtherRegionsTable::OtherRegionsTable(HeapRegion* hr, Mutex* m) :
 257   _g1h(G1CollectedHeap::heap()),
 258   _hr(hr), _m(m),
 259   _coarse_map(G1CollectedHeap::heap()->max_regions(),
 260               false /* in-resource-area */),
 261   _fine_grain_regions(NULL),
 262   _first_all_fine_prts(NULL), _last_all_fine_prts(NULL),
 263   _n_fine_entries(0), _n_coarse_entries(0),
 264   _fine_eviction_start(0),
 265   _sparse_table(hr)
 266 {
 267   typedef PerRegionTable* PerRegionTablePtr;
 268 
 269   if (_max_fine_entries == 0) {
 270     assert(_mod_max_fine_entries_mask == 0, "Both or none.");
 271     size_t max_entries_log = (size_t)log2_long((jlong)G1RSetRegionEntries);
 272     _max_fine_entries = (size_t)1 << max_entries_log;
 273     _mod_max_fine_entries_mask = _max_fine_entries - 1;
 274 
 275     assert(_fine_eviction_sample_size == 0
 276            && _fine_eviction_stride == 0, "All init at same time.");
 277     _fine_eviction_sample_size = MAX2((size_t)4, max_entries_log);
 278     _fine_eviction_stride = _max_fine_entries / _fine_eviction_sample_size;
 279   }
 280 
 281   _fine_grain_regions = NEW_C_HEAP_ARRAY3(PerRegionTablePtr, _max_fine_entries,
 282                         mtGC, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
 283 
 284   if (_fine_grain_regions == NULL) {
 285     vm_exit_out_of_memory(sizeof(void*)*_max_fine_entries, OOM_MALLOC_ERROR,
 286                           "Failed to allocate _fine_grain_entries.");
 287   }
 288 
 289   for (size_t i = 0; i < _max_fine_entries; i++) {
 290     _fine_grain_regions[i] = NULL;
 291   }
 292 }
 293 
 294 void OtherRegionsTable::link_to_all(PerRegionTable* prt) {
 295   // We always append to the beginning of the list for convenience;
 296   // the order of entries in this list does not matter.
 297   if (_first_all_fine_prts != NULL) {
 298     assert(_first_all_fine_prts->prev() == NULL, "invariant");
 299     _first_all_fine_prts->set_prev(prt);
 300     prt->set_next(_first_all_fine_prts);
 301   } else {
 302     // this is the first element we insert. Adjust the "last" pointer
 303     _last_all_fine_prts = prt;
 304     assert(prt->next() == NULL, "just checking");
 305   }
 306   // the new element is always the first element without a predecessor
 307   prt->set_prev(NULL);
 308   _first_all_fine_prts = prt;
 309 
 310   assert(prt->prev() == NULL, "just checking");
 311   assert(_first_all_fine_prts == prt, "just checking");
 312   assert((_first_all_fine_prts == NULL && _last_all_fine_prts == NULL) ||
 313          (_first_all_fine_prts != NULL && _last_all_fine_prts != NULL),
 314          "just checking");
 315   assert(_last_all_fine_prts == NULL || _last_all_fine_prts->next() == NULL,
 316          "just checking");
 317   assert(_first_all_fine_prts == NULL || _first_all_fine_prts->prev() == NULL,
 318          "just checking");
 319 }
 320 
 321 void OtherRegionsTable::unlink_from_all(PerRegionTable* prt) {
 322   if (prt->prev() != NULL) {
 323     assert(_first_all_fine_prts != prt, "just checking");
 324     prt->prev()->set_next(prt->next());
 325     // removing the last element in the list?
 326     if (_last_all_fine_prts == prt) {
 327       _last_all_fine_prts = prt->prev();
 328     }
 329   } else {
 330     assert(_first_all_fine_prts == prt, "just checking");
 331     _first_all_fine_prts = prt->next();
 332     // list is empty now?
 333     if (_first_all_fine_prts == NULL) {
 334       _last_all_fine_prts = NULL;
 335     }
 336   }
 337 
 338   if (prt->next() != NULL) {
 339     prt->next()->set_prev(prt->prev());
 340   }
 341 
 342   prt->set_next(NULL);
 343   prt->set_prev(NULL);
 344 
 345   assert((_first_all_fine_prts == NULL && _last_all_fine_prts == NULL) ||
 346          (_first_all_fine_prts != NULL && _last_all_fine_prts != NULL),
 347          "just checking");
 348   assert(_last_all_fine_prts == NULL || _last_all_fine_prts->next() == NULL,
 349          "just checking");
 350   assert(_first_all_fine_prts == NULL || _first_all_fine_prts->prev() == NULL,
 351          "just checking");
 352 }
 353 
 354 void OtherRegionsTable::add_reference(OopOrNarrowOopStar from, uint tid) {
 355   uint cur_hrm_ind = _hr->hrm_index();
 356 
 357   int from_card = (int)(uintptr_t(from) >> CardTableModRefBS::card_shift);
 358 
 359   if (G1FromCardCache::contains_or_replace(tid, cur_hrm_ind, from_card)) {
 360     assert(contains_reference(from), "We just added it!");
 361     return;
 362   }
 363 
 364   // Note that this may be a continued H region.
 365   HeapRegion* from_hr = _g1h->heap_region_containing(from);
 366   RegionIdx_t from_hrm_ind = (RegionIdx_t) from_hr->hrm_index();
 367 
 368   // If the region is already coarsened, return.
 369   if (_coarse_map.at(from_hrm_ind)) {
 370     assert(contains_reference(from), "We just added it!");
 371     return;
 372   }
 373 
 374   // Otherwise find a per-region table to add it to.
 375   size_t ind = from_hrm_ind & _mod_max_fine_entries_mask;
 376   PerRegionTable* prt = find_region_table(ind, from_hr);
 377   if (prt == NULL) {
 378     MutexLockerEx x(_m, Mutex::_no_safepoint_check_flag);
 379     // Confirm that it's really not there...
 380     prt = find_region_table(ind, from_hr);
 381     if (prt == NULL) {
 382 
 383       uintptr_t from_hr_bot_card_index =
 384         uintptr_t(from_hr->bottom())
 385           >> CardTableModRefBS::card_shift;
 386       CardIdx_t card_index = from_card - from_hr_bot_card_index;
 387       assert(0 <= card_index && (size_t)card_index < HeapRegion::CardsPerRegion,
 388              "Must be in range.");
 389       if (G1HRRSUseSparseTable &&
 390           _sparse_table.add_card(from_hrm_ind, card_index)) {
 391         assert(contains_reference_locked(from), "We just added it!");
 392         return;
 393       }
 394 
 395       if (_n_fine_entries == _max_fine_entries) {
 396         prt = delete_region_table();
 397         // There is no need to clear the links to the 'all' list here:
 398         // prt will be reused immediately, i.e. remain in the 'all' list.
 399         prt->init(from_hr, false /* clear_links_to_all_list */);
 400       } else {
 401         prt = PerRegionTable::alloc(from_hr);
 402         link_to_all(prt);
 403       }
 404 
 405       PerRegionTable* first_prt = _fine_grain_regions[ind];
 406       prt->set_collision_list_next(first_prt);
 407       // The assignment into _fine_grain_regions allows the prt to
 408       // start being used concurrently. In addition to
 409       // collision_list_next which must be visible (else concurrent
 410       // parsing of the list, if any, may fail to see other entries),
 411       // the content of the prt must be visible (else for instance
 412       // some mark bits may not yet seem cleared or a 'later' update
 413       // performed by a concurrent thread could be undone when the
 414       // zeroing becomes visible). This requires store ordering.
 415       OrderAccess::release_store_ptr((volatile PerRegionTable*)&_fine_grain_regions[ind], prt);
 416       _n_fine_entries++;
 417 
 418       if (G1HRRSUseSparseTable) {
 419         // Transfer from sparse to fine-grain.
 420         SparsePRTEntry *sprt_entry = _sparse_table.get_entry(from_hrm_ind);
 421         assert(sprt_entry != NULL, "There should have been an entry");
 422         for (int i = 0; i < SparsePRTEntry::cards_num(); i++) {
 423           CardIdx_t c = sprt_entry->card(i);
 424           if (c != SparsePRTEntry::NullEntry) {
 425             prt->add_card(c);
 426           }
 427         }
 428         // Now we can delete the sparse entry.
 429         bool res = _sparse_table.delete_entry(from_hrm_ind);
 430         assert(res, "It should have been there.");
 431       }
 432     }
 433     assert(prt != NULL && prt->hr() == from_hr, "consequence");
 434   }
 435   // Note that we can't assert "prt->hr() == from_hr", because of the
 436   // possibility of concurrent reuse.  But see head comment of
 437   // OtherRegionsTable for why this is OK.
 438   assert(prt != NULL, "Inv");
 439 
 440   prt->add_reference(from);
 441   assert(contains_reference(from), "We just added it!");
 442 }
 443 
 444 PerRegionTable*
 445 OtherRegionsTable::find_region_table(size_t ind, HeapRegion* hr) const {
 446   assert(ind < _max_fine_entries, "Preconditions.");
 447   PerRegionTable* prt = _fine_grain_regions[ind];
 448   while (prt != NULL && prt->hr() != hr) {
 449     prt = prt->collision_list_next();
 450   }
 451   // Loop postcondition is the method postcondition.
 452   return prt;
 453 }
 454 
 455 jint OtherRegionsTable::_n_coarsenings = 0;
 456 
 457 PerRegionTable* OtherRegionsTable::delete_region_table() {
 458   assert(_m->owned_by_self(), "Precondition");
 459   assert(_n_fine_entries == _max_fine_entries, "Precondition");
 460   PerRegionTable* max = NULL;
 461   jint max_occ = 0;
 462   PerRegionTable** max_prev = NULL;
 463   size_t max_ind;
 464 
 465   size_t i = _fine_eviction_start;
 466   for (size_t k = 0; k < _fine_eviction_sample_size; k++) {
 467     size_t ii = i;
 468     // Make sure we get a non-NULL sample.
 469     while (_fine_grain_regions[ii] == NULL) {
 470       ii++;
 471       if (ii == _max_fine_entries) ii = 0;
 472       guarantee(ii != i, "We must find one.");
 473     }
 474     PerRegionTable** prev = &_fine_grain_regions[ii];
 475     PerRegionTable* cur = *prev;
 476     while (cur != NULL) {
 477       jint cur_occ = cur->occupied();
 478       if (max == NULL || cur_occ > max_occ) {
 479         max = cur;
 480         max_prev = prev;
 481         max_ind = i;
 482         max_occ = cur_occ;
 483       }
 484       prev = cur->collision_list_next_addr();
 485       cur = cur->collision_list_next();
 486     }
 487     i = i + _fine_eviction_stride;
 488     if (i >= _n_fine_entries) i = i - _n_fine_entries;
 489   }
 490 
 491   _fine_eviction_start++;
 492 
 493   if (_fine_eviction_start >= _n_fine_entries) {
 494     _fine_eviction_start -= _n_fine_entries;
 495   }
 496 
 497   guarantee(max != NULL, "Since _n_fine_entries > 0");
 498   guarantee(max_prev != NULL, "Since max != NULL.");
 499 
 500   // Set the corresponding coarse bit.
 501   size_t max_hrm_index = (size_t) max->hr()->hrm_index();
 502   if (!_coarse_map.at(max_hrm_index)) {
 503     _coarse_map.at_put(max_hrm_index, true);
 504     _n_coarse_entries++;
 505   }
 506 
 507   // Unsplice.
 508   *max_prev = max->collision_list_next();
 509   Atomic::inc(&_n_coarsenings);
 510   _n_fine_entries--;
 511   return max;
 512 }
 513 
 514 void OtherRegionsTable::scrub(CardTableModRefBS* ctbs,
 515                               BitMap* region_bm, BitMap* card_bm) {
 516   // First eliminated garbage regions from the coarse map.
 517   log_develop_trace(gc, remset, scrub)("Scrubbing region %u:", _hr->hrm_index());
 518 
 519   assert(_coarse_map.size() == region_bm->size(), "Precondition");
 520   log_develop_trace(gc, remset, scrub)("   Coarse map: before = " SIZE_FORMAT "...", _n_coarse_entries);
 521   _coarse_map.set_intersection(*region_bm);
 522   _n_coarse_entries = _coarse_map.count_one_bits();
 523   log_develop_trace(gc, remset, scrub)("   after = " SIZE_FORMAT ".", _n_coarse_entries);
 524 
 525   // Now do the fine-grained maps.
 526   for (size_t i = 0; i < _max_fine_entries; i++) {
 527     PerRegionTable* cur = _fine_grain_regions[i];
 528     PerRegionTable** prev = &_fine_grain_regions[i];
 529     while (cur != NULL) {
 530       PerRegionTable* nxt = cur->collision_list_next();
 531       // If the entire region is dead, eliminate.
 532       log_develop_trace(gc, remset, scrub)("     For other region %u:", cur->hr()->hrm_index());
 533       if (!region_bm->at((size_t) cur->hr()->hrm_index())) {
 534         *prev = nxt;
 535         cur->set_collision_list_next(NULL);
 536         _n_fine_entries--;
 537         log_develop_trace(gc, remset, scrub)("          deleted via region map.");
 538         unlink_from_all(cur);
 539         PerRegionTable::free(cur);
 540       } else {
 541         // Do fine-grain elimination.
 542         log_develop_trace(gc, remset, scrub)("          occ: before = %4d.", cur->occupied());
 543         cur->scrub(ctbs, card_bm);
 544         log_develop_trace(gc, remset, scrub)("          after = %4d.", cur->occupied());
 545         // Did that empty the table completely?
 546         if (cur->occupied() == 0) {
 547           *prev = nxt;
 548           cur->set_collision_list_next(NULL);
 549           _n_fine_entries--;
 550           unlink_from_all(cur);
 551           PerRegionTable::free(cur);
 552         } else {
 553           prev = cur->collision_list_next_addr();
 554         }
 555       }
 556       cur = nxt;
 557     }
 558   }
 559   // Since we may have deleted a from_card_cache entry from the RS, clear
 560   // the FCC.
 561   clear_fcc();
 562 }
 563 
 564 bool OtherRegionsTable::occupancy_less_or_equal_than(size_t limit) const {
 565   if (limit <= (size_t)G1RSetSparseRegionEntries) {
 566     return occ_coarse() == 0 && _first_all_fine_prts == NULL && occ_sparse() <= limit;
 567   } else {
 568     // Current uses of this method may only use values less than G1RSetSparseRegionEntries
 569     // for the limit. The solution, comparing against occupied() would be too slow
 570     // at this time.
 571     Unimplemented();
 572     return false;
 573   }
 574 }
 575 
 576 bool OtherRegionsTable::is_empty() const {
 577   return occ_sparse() == 0 && occ_coarse() == 0 && _first_all_fine_prts == NULL;
 578 }
 579 
 580 size_t OtherRegionsTable::occupied() const {
 581   size_t sum = occ_fine();
 582   sum += occ_sparse();
 583   sum += occ_coarse();
 584   return sum;
 585 }
 586 
 587 size_t OtherRegionsTable::occ_fine() const {
 588   size_t sum = 0;
 589 
 590   size_t num = 0;
 591   PerRegionTable * cur = _first_all_fine_prts;
 592   while (cur != NULL) {
 593     sum += cur->occupied();
 594     cur = cur->next();
 595     num++;
 596   }
 597   guarantee(num == _n_fine_entries, "just checking");
 598   return sum;
 599 }
 600 
 601 size_t OtherRegionsTable::occ_coarse() const {
 602   return (_n_coarse_entries * HeapRegion::CardsPerRegion);
 603 }
 604 
 605 size_t OtherRegionsTable::occ_sparse() const {
 606   return _sparse_table.occupied();
 607 }
 608 
 609 size_t OtherRegionsTable::mem_size() const {
 610   size_t sum = 0;
 611   // all PRTs are of the same size so it is sufficient to query only one of them.
 612   if (_first_all_fine_prts != NULL) {
 613     assert(_last_all_fine_prts != NULL &&
 614       _first_all_fine_prts->mem_size() == _last_all_fine_prts->mem_size(), "check that mem_size() is constant");
 615     sum += _first_all_fine_prts->mem_size() * _n_fine_entries;
 616   }
 617   sum += (sizeof(PerRegionTable*) * _max_fine_entries);
 618   sum += (_coarse_map.size_in_words() * HeapWordSize);
 619   sum += (_sparse_table.mem_size());
 620   sum += sizeof(OtherRegionsTable) - sizeof(_sparse_table); // Avoid double counting above.
 621   return sum;
 622 }
 623 
 624 size_t OtherRegionsTable::static_mem_size() {
 625   return G1FromCardCache::static_mem_size();
 626 }
 627 
 628 size_t OtherRegionsTable::fl_mem_size() {
 629   return PerRegionTable::fl_mem_size();
 630 }
 631 
 632 void OtherRegionsTable::clear_fcc() {
 633   G1FromCardCache::clear(_hr->hrm_index());
 634 }
 635 
 636 void OtherRegionsTable::clear() {
 637   // if there are no entries, skip this step
 638   if (_first_all_fine_prts != NULL) {
 639     guarantee(_first_all_fine_prts != NULL && _last_all_fine_prts != NULL, "just checking");
 640     PerRegionTable::bulk_free(_first_all_fine_prts, _last_all_fine_prts);
 641     memset(_fine_grain_regions, 0, _max_fine_entries * sizeof(_fine_grain_regions[0]));
 642   } else {
 643     guarantee(_first_all_fine_prts == NULL && _last_all_fine_prts == NULL, "just checking");
 644   }
 645 
 646   _first_all_fine_prts = _last_all_fine_prts = NULL;
 647   _sparse_table.clear();
 648   _coarse_map.clear();
 649   _n_fine_entries = 0;
 650   _n_coarse_entries = 0;
 651 
 652   clear_fcc();
 653 }
 654 
 655 bool OtherRegionsTable::contains_reference(OopOrNarrowOopStar from) const {
 656   // Cast away const in this case.
 657   MutexLockerEx x((Mutex*)_m, Mutex::_no_safepoint_check_flag);
 658   return contains_reference_locked(from);
 659 }
 660 
 661 bool OtherRegionsTable::contains_reference_locked(OopOrNarrowOopStar from) const {
 662   HeapRegion* hr = _g1h->heap_region_containing(from);
 663   RegionIdx_t hr_ind = (RegionIdx_t) hr->hrm_index();
 664   // Is this region in the coarse map?
 665   if (_coarse_map.at(hr_ind)) return true;
 666 
 667   PerRegionTable* prt = find_region_table(hr_ind & _mod_max_fine_entries_mask,
 668                                      hr);
 669   if (prt != NULL) {
 670     return prt->contains_reference(from);
 671 
 672   } else {
 673     uintptr_t from_card =
 674       (uintptr_t(from) >> CardTableModRefBS::card_shift);
 675     uintptr_t hr_bot_card_index =
 676       uintptr_t(hr->bottom()) >> CardTableModRefBS::card_shift;
 677     assert(from_card >= hr_bot_card_index, "Inv");
 678     CardIdx_t card_index = from_card - hr_bot_card_index;
 679     assert(0 <= card_index && (size_t)card_index < HeapRegion::CardsPerRegion,
 680            "Must be in range.");
 681     return _sparse_table.contains_card(hr_ind, card_index);
 682   }
 683 }
 684 
 685 void
 686 OtherRegionsTable::do_cleanup_work(HRRSCleanupTask* hrrs_cleanup_task) {
 687   _sparse_table.do_cleanup_work(hrrs_cleanup_task);
 688 }
 689 
 690 HeapRegionRemSet::HeapRegionRemSet(G1BlockOffsetTable* bot,
 691                                    HeapRegion* hr)
 692   : _bot(bot),
 693     _m(Mutex::leaf, FormatBuffer<128>("HeapRegionRemSet lock #%u", hr->hrm_index()), true, Monitor::_safepoint_check_never),
 694     _code_roots(), _other_regions(hr, &_m), _iter_state(Unclaimed), _iter_claimed(0) {
 695   reset_for_par_iteration();
 696 }
 697 
 698 void HeapRegionRemSet::setup_remset_size() {
 699   // Setup sparse and fine-grain tables sizes.
 700   // table_size = base * (log(region_size / 1M) + 1)
 701   const int LOG_M = 20;
 702   int region_size_log_mb = MAX2(HeapRegion::LogOfHRGrainBytes - LOG_M, 0);
 703   if (FLAG_IS_DEFAULT(G1RSetSparseRegionEntries)) {
 704     G1RSetSparseRegionEntries = G1RSetSparseRegionEntriesBase * (region_size_log_mb + 1);
 705   }
 706   if (FLAG_IS_DEFAULT(G1RSetRegionEntries)) {
 707     G1RSetRegionEntries = G1RSetRegionEntriesBase * (region_size_log_mb + 1);
 708   }
 709   guarantee(G1RSetSparseRegionEntries > 0 && G1RSetRegionEntries > 0 , "Sanity");
 710 }
 711 
 712 bool HeapRegionRemSet::claim_iter() {
 713   if (_iter_state != Unclaimed) return false;
 714   jint res = Atomic::cmpxchg(Claimed, (jint*)(&_iter_state), Unclaimed);
 715   return (res == Unclaimed);
 716 }
 717 
 718 void HeapRegionRemSet::set_iter_complete() {
 719   _iter_state = Complete;
 720 }
 721 
 722 bool HeapRegionRemSet::iter_is_complete() {
 723   return _iter_state == Complete;
 724 }
 725 
 726 #ifndef PRODUCT
 727 void HeapRegionRemSet::print() {
 728   HeapRegionRemSetIterator iter(this);
 729   size_t card_index;
 730   while (iter.has_next(card_index)) {
 731     HeapWord* card_start = _bot->address_for_index(card_index);
 732     tty->print_cr("  Card " PTR_FORMAT, p2i(card_start));
 733   }
 734   if (iter.n_yielded() != occupied()) {
 735     tty->print_cr("Yielded disagrees with occupied:");
 736     tty->print_cr("  " SIZE_FORMAT_W(6) " yielded (" SIZE_FORMAT_W(6)
 737                   " coarse, " SIZE_FORMAT_W(6) " fine).",
 738                   iter.n_yielded(),
 739                   iter.n_yielded_coarse(), iter.n_yielded_fine());
 740     tty->print_cr("  " SIZE_FORMAT_W(6) " occ     (" SIZE_FORMAT_W(6)
 741                            " coarse, " SIZE_FORMAT_W(6) " fine).",
 742                   occupied(), occ_coarse(), occ_fine());
 743   }
 744   guarantee(iter.n_yielded() == occupied(),
 745             "We should have yielded all the represented cards.");
 746 }
 747 #endif
 748 
 749 void HeapRegionRemSet::cleanup() {
 750   SparsePRT::cleanup_all();
 751 }
 752 
 753 void HeapRegionRemSet::clear() {
 754   MutexLockerEx x(&_m, Mutex::_no_safepoint_check_flag);
 755   clear_locked();
 756 }
 757 
 758 void HeapRegionRemSet::clear_locked() {
 759   _code_roots.clear();
 760   _other_regions.clear();
 761   assert(occupied_locked() == 0, "Should be clear.");
 762   reset_for_par_iteration();
 763 }
 764 
 765 void HeapRegionRemSet::reset_for_par_iteration() {
 766   _iter_state = Unclaimed;
 767   _iter_claimed = 0;
 768   // It's good to check this to make sure that the two methods are in sync.
 769   assert(verify_ready_for_par_iteration(), "post-condition");
 770 }
 771 
 772 void HeapRegionRemSet::scrub(CardTableModRefBS* ctbs,
 773                              BitMap* region_bm, BitMap* card_bm) {
 774   _other_regions.scrub(ctbs, region_bm, card_bm);
 775 }
 776 
 777 // Code roots support
 778 //
 779 // The code root set is protected by two separate locking schemes
 780 // When at safepoint the per-hrrs lock must be held during modifications
 781 // except when doing a full gc.
 782 // When not at safepoint the CodeCache_lock must be held during modifications.
 783 // When concurrent readers access the contains() function
 784 // (during the evacuation phase) no removals are allowed.
 785 
 786 void HeapRegionRemSet::add_strong_code_root(nmethod* nm) {
 787   assert(nm != NULL, "sanity");
 788   // Optimistic unlocked contains-check
 789   if (!_code_roots.contains(nm)) {
 790     MutexLockerEx ml(&_m, Mutex::_no_safepoint_check_flag);
 791     add_strong_code_root_locked(nm);
 792   }
 793 }
 794 
 795 void HeapRegionRemSet::add_strong_code_root_locked(nmethod* nm) {
 796   assert(nm != NULL, "sanity");
 797   _code_roots.add(nm);
 798 }
 799 
 800 void HeapRegionRemSet::remove_strong_code_root(nmethod* nm) {
 801   assert(nm != NULL, "sanity");
 802   assert_locked_or_safepoint(CodeCache_lock);
 803 
 804   MutexLockerEx ml(CodeCache_lock->owned_by_self() ? NULL : &_m, Mutex::_no_safepoint_check_flag);
 805   _code_roots.remove(nm);
 806 
 807   // Check that there were no duplicates
 808   guarantee(!_code_roots.contains(nm), "duplicate entry found");
 809 }
 810 
 811 void HeapRegionRemSet::strong_code_roots_do(CodeBlobClosure* blk) const {
 812   _code_roots.nmethods_do(blk);
 813 }
 814 
 815 void HeapRegionRemSet::clean_strong_code_roots(HeapRegion* hr) {
 816   _code_roots.clean(hr);
 817 }
 818 
 819 size_t HeapRegionRemSet::strong_code_roots_mem_size() {
 820   return _code_roots.mem_size();
 821 }
 822 
 823 HeapRegionRemSetIterator:: HeapRegionRemSetIterator(HeapRegionRemSet* hrrs) :
 824   _hrrs(hrrs),
 825   _g1h(G1CollectedHeap::heap()),
 826   _coarse_map(&hrrs->_other_regions._coarse_map),
 827   _bot(hrrs->_bot),
 828   _is(Sparse),
 829   // Set these values so that we increment to the first region.
 830   _coarse_cur_region_index(-1),
 831   _coarse_cur_region_cur_card(HeapRegion::CardsPerRegion-1),
 832   _cur_card_in_prt(HeapRegion::CardsPerRegion),
 833   _fine_cur_prt(NULL),
 834   _n_yielded_coarse(0),
 835   _n_yielded_fine(0),
 836   _n_yielded_sparse(0),
 837   _sparse_iter(&hrrs->_other_regions._sparse_table) {}
 838 
 839 bool HeapRegionRemSetIterator::coarse_has_next(size_t& card_index) {
 840   if (_hrrs->_other_regions._n_coarse_entries == 0) return false;
 841   // Go to the next card.
 842   _coarse_cur_region_cur_card++;
 843   // Was the last the last card in the current region?
 844   if (_coarse_cur_region_cur_card == HeapRegion::CardsPerRegion) {
 845     // Yes: find the next region.  This may leave _coarse_cur_region_index
 846     // Set to the last index, in which case there are no more coarse
 847     // regions.
 848     _coarse_cur_region_index =
 849       (int) _coarse_map->get_next_one_offset(_coarse_cur_region_index + 1);
 850     if ((size_t)_coarse_cur_region_index < _coarse_map->size()) {
 851       _coarse_cur_region_cur_card = 0;
 852       HeapWord* r_bot =
 853         _g1h->region_at((uint) _coarse_cur_region_index)->bottom();
 854       _cur_region_card_offset = _bot->index_for(r_bot);
 855     } else {
 856       return false;
 857     }
 858   }
 859   // If we didn't return false above, then we can yield a card.
 860   card_index = _cur_region_card_offset + _coarse_cur_region_cur_card;
 861   return true;
 862 }
 863 
 864 bool HeapRegionRemSetIterator::fine_has_next(size_t& card_index) {
 865   if (fine_has_next()) {
 866     _cur_card_in_prt =
 867       _fine_cur_prt->_bm.get_next_one_offset(_cur_card_in_prt + 1);
 868   }
 869   if (_cur_card_in_prt == HeapRegion::CardsPerRegion) {
 870     // _fine_cur_prt may still be NULL in case if there are not PRTs at all for
 871     // the remembered set.
 872     if (_fine_cur_prt == NULL || _fine_cur_prt->next() == NULL) {
 873       return false;
 874     }
 875     PerRegionTable* next_prt = _fine_cur_prt->next();
 876     switch_to_prt(next_prt);
 877     _cur_card_in_prt = _fine_cur_prt->_bm.get_next_one_offset(_cur_card_in_prt + 1);
 878   }
 879 
 880   card_index = _cur_region_card_offset + _cur_card_in_prt;
 881   guarantee(_cur_card_in_prt < HeapRegion::CardsPerRegion,
 882             "Card index " SIZE_FORMAT " must be within the region", _cur_card_in_prt);
 883   return true;
 884 }
 885 
 886 bool HeapRegionRemSetIterator::fine_has_next() {
 887   return _cur_card_in_prt != HeapRegion::CardsPerRegion;
 888 }
 889 
 890 void HeapRegionRemSetIterator::switch_to_prt(PerRegionTable* prt) {
 891   assert(prt != NULL, "Cannot switch to NULL prt");
 892   _fine_cur_prt = prt;
 893 
 894   HeapWord* r_bot = _fine_cur_prt->hr()->bottom();
 895   _cur_region_card_offset = _bot->index_for(r_bot);
 896 
 897   // The bitmap scan for the PRT always scans from _cur_region_cur_card + 1.
 898   // To avoid special-casing this start case, and not miss the first bitmap
 899   // entry, initialize _cur_region_cur_card with -1 instead of 0.
 900   _cur_card_in_prt = (size_t)-1;
 901 }
 902 
 903 bool HeapRegionRemSetIterator::has_next(size_t& card_index) {
 904   switch (_is) {
 905   case Sparse: {
 906     if (_sparse_iter.has_next(card_index)) {
 907       _n_yielded_sparse++;
 908       return true;
 909     }
 910     // Otherwise, deliberate fall-through
 911     _is = Fine;
 912     PerRegionTable* initial_fine_prt = _hrrs->_other_regions._first_all_fine_prts;
 913     if (initial_fine_prt != NULL) {
 914       switch_to_prt(_hrrs->_other_regions._first_all_fine_prts);
 915     }
 916   }
 917   case Fine:
 918     if (fine_has_next(card_index)) {
 919       _n_yielded_fine++;
 920       return true;
 921     }
 922     // Otherwise, deliberate fall-through
 923     _is = Coarse;
 924   case Coarse:
 925     if (coarse_has_next(card_index)) {
 926       _n_yielded_coarse++;
 927       return true;
 928     }
 929     // Otherwise...
 930     break;
 931   }
 932   assert(ParallelGCThreads > 1 ||
 933          n_yielded() == _hrrs->occupied(),
 934          "Should have yielded all the cards in the rem set "
 935          "(in the non-par case).");
 936   return false;
 937 }
 938 
 939 void HeapRegionRemSet::reset_for_cleanup_tasks() {
 940   SparsePRT::reset_for_cleanup_tasks();
 941 }
 942 
 943 void HeapRegionRemSet::do_cleanup_work(HRRSCleanupTask* hrrs_cleanup_task) {
 944   _other_regions.do_cleanup_work(hrrs_cleanup_task);
 945 }
 946 
 947 void
 948 HeapRegionRemSet::finish_cleanup_task(HRRSCleanupTask* hrrs_cleanup_task) {
 949   SparsePRT::finish_cleanup_task(hrrs_cleanup_task);
 950 }
 951 
 952 #ifndef PRODUCT
 953 void HeapRegionRemSet::test() {
 954   os::sleep(Thread::current(), (jlong)5000, false);
 955   G1CollectedHeap* g1h = G1CollectedHeap::heap();
 956 
 957   // Run with "-XX:G1LogRSetRegionEntries=2", so that 1 and 5 end up in same
 958   // hash bucket.
 959   HeapRegion* hr0 = g1h->region_at(0);
 960   HeapRegion* hr1 = g1h->region_at(1);
 961   HeapRegion* hr2 = g1h->region_at(5);
 962   HeapRegion* hr3 = g1h->region_at(6);
 963   HeapRegion* hr4 = g1h->region_at(7);
 964   HeapRegion* hr5 = g1h->region_at(8);
 965 
 966   HeapWord* hr1_start = hr1->bottom();
 967   HeapWord* hr1_mid = hr1_start + HeapRegion::GrainWords/2;
 968   HeapWord* hr1_last = hr1->end() - 1;
 969 
 970   HeapWord* hr2_start = hr2->bottom();
 971   HeapWord* hr2_mid = hr2_start + HeapRegion::GrainWords/2;
 972   HeapWord* hr2_last = hr2->end() - 1;
 973 
 974   HeapWord* hr3_start = hr3->bottom();
 975   HeapWord* hr3_mid = hr3_start + HeapRegion::GrainWords/2;
 976   HeapWord* hr3_last = hr3->end() - 1;
 977 
 978   HeapRegionRemSet* hrrs = hr0->rem_set();
 979 
 980   // Make three references from region 0x101...
 981   hrrs->add_reference((OopOrNarrowOopStar)hr1_start);
 982   hrrs->add_reference((OopOrNarrowOopStar)hr1_mid);
 983   hrrs->add_reference((OopOrNarrowOopStar)hr1_last);
 984 
 985   hrrs->add_reference((OopOrNarrowOopStar)hr2_start);
 986   hrrs->add_reference((OopOrNarrowOopStar)hr2_mid);
 987   hrrs->add_reference((OopOrNarrowOopStar)hr2_last);
 988 
 989   hrrs->add_reference((OopOrNarrowOopStar)hr3_start);
 990   hrrs->add_reference((OopOrNarrowOopStar)hr3_mid);
 991   hrrs->add_reference((OopOrNarrowOopStar)hr3_last);
 992 
 993   // Now cause a coarsening.
 994   hrrs->add_reference((OopOrNarrowOopStar)hr4->bottom());
 995   hrrs->add_reference((OopOrNarrowOopStar)hr5->bottom());
 996 
 997   // Now, does iteration yield these three?
 998   HeapRegionRemSetIterator iter(hrrs);
 999   size_t sum = 0;
1000   size_t card_index;
1001   while (iter.has_next(card_index)) {
1002     HeapWord* card_start =
1003       G1CollectedHeap::heap()->bot()->address_for_index(card_index);
1004     tty->print_cr("  Card " PTR_FORMAT ".", p2i(card_start));
1005     sum++;
1006   }
1007   guarantee(sum == 11 - 3 + 2048, "Failure");
1008   guarantee(sum == hrrs->occupied(), "Failure");
1009 }
1010 #endif