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     if (G1TraceHeapRegionRememberedSet) {
  93       gclog_or_tty->print_cr("    PRT::Add_reference_work(" PTR_FORMAT "->" PTR_FORMAT ").",
  94                              p2i(from),
  95                              UseCompressedOops
  96                              ? p2i(oopDesc::load_decode_heap_oop((narrowOop*)from))
  97                              : p2i(oopDesc::load_decode_heap_oop((oop*)from)));
  98     }
  99 
 100     HeapRegion* loc_hr = hr();
 101     // If the test below fails, then this table was reused concurrently
 102     // with this operation.  This is OK, since the old table was coarsened,
 103     // and adding a bit to the new table is never incorrect.
 104     // If the table used to belong to a continues humongous region and is
 105     // now reused for the corresponding start humongous region, we need to
 106     // make sure that we detect this. Thus, we call is_in_reserved_raw()
 107     // instead of just is_in_reserved() here.
 108     if (loc_hr->is_in_reserved(from)) {
 109       size_t hw_offset = pointer_delta((HeapWord*)from, loc_hr->bottom());
 110       CardIdx_t from_card = (CardIdx_t)
 111           hw_offset >> (CardTableModRefBS::card_shift - LogHeapWordSize);
 112 
 113       assert(0 <= from_card && (size_t)from_card < HeapRegion::CardsPerRegion,
 114              "Must be in range.");
 115       add_card_work(from_card, par);
 116     }
 117   }
 118 
 119 public:
 120 
 121   HeapRegion* hr() const { return _hr; }
 122 
 123   jint occupied() const {
 124     // Overkill, but if we ever need it...
 125     // guarantee(_occupied == _bm.count_one_bits(), "Check");
 126     return _occupied;
 127   }
 128 
 129   void init(HeapRegion* hr, bool clear_links_to_all_list) {
 130     if (clear_links_to_all_list) {
 131       set_next(NULL);
 132       set_prev(NULL);
 133     }
 134     _hr = hr;
 135     _collision_list_next = NULL;
 136     _occupied = 0;
 137     _bm.clear();
 138   }
 139 
 140   void add_reference(OopOrNarrowOopStar from) {
 141     add_reference_work(from, /*parallel*/ true);
 142   }
 143 
 144   void seq_add_reference(OopOrNarrowOopStar from) {
 145     add_reference_work(from, /*parallel*/ false);
 146   }
 147 
 148   void scrub(CardTableModRefBS* ctbs, BitMap* card_bm) {
 149     HeapWord* hr_bot = hr()->bottom();
 150     size_t hr_first_card_index = ctbs->index_for(hr_bot);
 151     bm()->set_intersection_at_offset(*card_bm, hr_first_card_index);
 152     recount_occupied();
 153   }
 154 
 155   void add_card(CardIdx_t from_card_index) {
 156     add_card_work(from_card_index, /*parallel*/ true);
 157   }
 158 
 159   void seq_add_card(CardIdx_t from_card_index) {
 160     add_card_work(from_card_index, /*parallel*/ false);
 161   }
 162 
 163   // (Destructively) union the bitmap of the current table into the given
 164   // bitmap (which is assumed to be of the same size.)
 165   void union_bitmap_into(BitMap* bm) {
 166     bm->set_union(_bm);
 167   }
 168 
 169   // Mem size in bytes.
 170   size_t mem_size() const {
 171     return sizeof(PerRegionTable) + _bm.size_in_words() * HeapWordSize;
 172   }
 173 
 174   // Requires "from" to be in "hr()".
 175   bool contains_reference(OopOrNarrowOopStar from) const {
 176     assert(hr()->is_in_reserved(from), "Precondition.");
 177     size_t card_ind = pointer_delta(from, hr()->bottom(),
 178                                     CardTableModRefBS::card_size);
 179     return _bm.at(card_ind);
 180   }
 181 
 182   // Bulk-free the PRTs from prt to last, assumes that they are
 183   // linked together using their _next field.
 184   static void bulk_free(PerRegionTable* prt, PerRegionTable* last) {
 185     while (true) {
 186       PerRegionTable* fl = _free_list;
 187       last->set_next(fl);
 188       PerRegionTable* res = (PerRegionTable*) Atomic::cmpxchg_ptr(prt, &_free_list, fl);
 189       if (res == fl) {
 190         return;
 191       }
 192     }
 193     ShouldNotReachHere();
 194   }
 195 
 196   static void free(PerRegionTable* prt) {
 197     bulk_free(prt, prt);
 198   }
 199 
 200   // Returns an initialized PerRegionTable instance.
 201   static PerRegionTable* alloc(HeapRegion* hr) {
 202     PerRegionTable* fl = _free_list;
 203     while (fl != NULL) {
 204       PerRegionTable* nxt = fl->next();
 205       PerRegionTable* res =
 206         (PerRegionTable*)
 207         Atomic::cmpxchg_ptr(nxt, &_free_list, fl);
 208       if (res == fl) {
 209         fl->init(hr, true);
 210         return fl;
 211       } else {
 212         fl = _free_list;
 213       }
 214     }
 215     assert(fl == NULL, "Loop condition.");
 216     return new PerRegionTable(hr);
 217   }
 218 
 219   PerRegionTable* next() const { return _next; }
 220   void set_next(PerRegionTable* next) { _next = next; }
 221   PerRegionTable* prev() const { return _prev; }
 222   void set_prev(PerRegionTable* prev) { _prev = prev; }
 223 
 224   // Accessor and Modification routines for the pointer for the
 225   // singly linked collision list that links the PRTs within the
 226   // OtherRegionsTable::_fine_grain_regions hash table.
 227   //
 228   // It might be useful to also make the collision list doubly linked
 229   // to avoid iteration over the collisions list during scrubbing/deletion.
 230   // OTOH there might not be many collisions.
 231 
 232   PerRegionTable* collision_list_next() const {
 233     return _collision_list_next;
 234   }
 235 
 236   void set_collision_list_next(PerRegionTable* next) {
 237     _collision_list_next = next;
 238   }
 239 
 240   PerRegionTable** collision_list_next_addr() {
 241     return &_collision_list_next;
 242   }
 243 
 244   static size_t fl_mem_size() {
 245     PerRegionTable* cur = _free_list;
 246     size_t res = 0;
 247     while (cur != NULL) {
 248       res += cur->mem_size();
 249       cur = cur->next();
 250     }
 251     return res;
 252   }
 253 
 254   static void test_fl_mem_size();
 255 };
 256 
 257 PerRegionTable* PerRegionTable::_free_list = NULL;
 258 
 259 size_t OtherRegionsTable::_max_fine_entries = 0;
 260 size_t OtherRegionsTable::_mod_max_fine_entries_mask = 0;
 261 size_t OtherRegionsTable::_fine_eviction_stride = 0;
 262 size_t OtherRegionsTable::_fine_eviction_sample_size = 0;
 263 
 264 OtherRegionsTable::OtherRegionsTable(HeapRegion* hr, Mutex* m) :
 265   _g1h(G1CollectedHeap::heap()),
 266   _hr(hr), _m(m),
 267   _coarse_map(G1CollectedHeap::heap()->max_regions(),
 268               false /* in-resource-area */),
 269   _fine_grain_regions(NULL),
 270   _first_all_fine_prts(NULL), _last_all_fine_prts(NULL),
 271   _n_fine_entries(0), _n_coarse_entries(0),
 272   _fine_eviction_start(0),
 273   _sparse_table(hr)
 274 {
 275   typedef PerRegionTable* PerRegionTablePtr;
 276 
 277   if (_max_fine_entries == 0) {
 278     assert(_mod_max_fine_entries_mask == 0, "Both or none.");
 279     size_t max_entries_log = (size_t)log2_long((jlong)G1RSetRegionEntries);
 280     _max_fine_entries = (size_t)1 << max_entries_log;
 281     _mod_max_fine_entries_mask = _max_fine_entries - 1;
 282 
 283     assert(_fine_eviction_sample_size == 0
 284            && _fine_eviction_stride == 0, "All init at same time.");
 285     _fine_eviction_sample_size = MAX2((size_t)4, max_entries_log);
 286     _fine_eviction_stride = _max_fine_entries / _fine_eviction_sample_size;
 287   }
 288 
 289   _fine_grain_regions = NEW_C_HEAP_ARRAY3(PerRegionTablePtr, _max_fine_entries,
 290                         mtGC, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
 291 
 292   if (_fine_grain_regions == NULL) {
 293     vm_exit_out_of_memory(sizeof(void*)*_max_fine_entries, OOM_MALLOC_ERROR,
 294                           "Failed to allocate _fine_grain_entries.");
 295   }
 296 
 297   for (size_t i = 0; i < _max_fine_entries; i++) {
 298     _fine_grain_regions[i] = NULL;
 299   }
 300 }
 301 
 302 void OtherRegionsTable::link_to_all(PerRegionTable* prt) {
 303   // We always append to the beginning of the list for convenience;
 304   // the order of entries in this list does not matter.
 305   if (_first_all_fine_prts != NULL) {
 306     assert(_first_all_fine_prts->prev() == NULL, "invariant");
 307     _first_all_fine_prts->set_prev(prt);
 308     prt->set_next(_first_all_fine_prts);
 309   } else {
 310     // this is the first element we insert. Adjust the "last" pointer
 311     _last_all_fine_prts = prt;
 312     assert(prt->next() == NULL, "just checking");
 313   }
 314   // the new element is always the first element without a predecessor
 315   prt->set_prev(NULL);
 316   _first_all_fine_prts = prt;
 317 
 318   assert(prt->prev() == NULL, "just checking");
 319   assert(_first_all_fine_prts == prt, "just checking");
 320   assert((_first_all_fine_prts == NULL && _last_all_fine_prts == NULL) ||
 321          (_first_all_fine_prts != NULL && _last_all_fine_prts != NULL),
 322          "just checking");
 323   assert(_last_all_fine_prts == NULL || _last_all_fine_prts->next() == NULL,
 324          "just checking");
 325   assert(_first_all_fine_prts == NULL || _first_all_fine_prts->prev() == NULL,
 326          "just checking");
 327 }
 328 
 329 void OtherRegionsTable::unlink_from_all(PerRegionTable* prt) {
 330   if (prt->prev() != NULL) {
 331     assert(_first_all_fine_prts != prt, "just checking");
 332     prt->prev()->set_next(prt->next());
 333     // removing the last element in the list?
 334     if (_last_all_fine_prts == prt) {
 335       _last_all_fine_prts = prt->prev();
 336     }
 337   } else {
 338     assert(_first_all_fine_prts == prt, "just checking");
 339     _first_all_fine_prts = prt->next();
 340     // list is empty now?
 341     if (_first_all_fine_prts == NULL) {
 342       _last_all_fine_prts = NULL;
 343     }
 344   }
 345 
 346   if (prt->next() != NULL) {
 347     prt->next()->set_prev(prt->prev());
 348   }
 349 
 350   prt->set_next(NULL);
 351   prt->set_prev(NULL);
 352 
 353   assert((_first_all_fine_prts == NULL && _last_all_fine_prts == NULL) ||
 354          (_first_all_fine_prts != NULL && _last_all_fine_prts != NULL),
 355          "just checking");
 356   assert(_last_all_fine_prts == NULL || _last_all_fine_prts->next() == NULL,
 357          "just checking");
 358   assert(_first_all_fine_prts == NULL || _first_all_fine_prts->prev() == NULL,
 359          "just checking");
 360 }
 361 
 362 int**  FromCardCache::_cache = NULL;
 363 uint   FromCardCache::_max_regions = 0;
 364 size_t FromCardCache::_static_mem_size = 0;
 365 
 366 void FromCardCache::initialize(uint n_par_rs, uint max_num_regions) {
 367   guarantee(_cache == NULL, "Should not call this multiple times");
 368 
 369   _max_regions = max_num_regions;
 370   _cache = Padded2DArray<int, mtGC>::create_unfreeable(n_par_rs,
 371                                                        _max_regions,
 372                                                        &_static_mem_size);
 373 
 374   invalidate(0, _max_regions);
 375 }
 376 
 377 void FromCardCache::invalidate(uint start_idx, size_t new_num_regions) {
 378   guarantee((size_t)start_idx + new_num_regions <= max_uintx,
 379             "Trying to invalidate beyond maximum region, from %u size " SIZE_FORMAT,
 380             start_idx, new_num_regions);
 381   for (uint i = 0; i < HeapRegionRemSet::num_par_rem_sets(); i++) {
 382     uint end_idx = (start_idx + (uint)new_num_regions);
 383     assert(end_idx <= _max_regions, "Must be within max.");
 384     for (uint j = start_idx; j < end_idx; j++) {
 385       set(i, j, InvalidCard);
 386     }
 387   }
 388 }
 389 
 390 #ifndef PRODUCT
 391 void FromCardCache::print(outputStream* out) {
 392   for (uint i = 0; i < HeapRegionRemSet::num_par_rem_sets(); i++) {
 393     for (uint j = 0; j < _max_regions; j++) {
 394       out->print_cr("_from_card_cache[%u][%u] = %d.",
 395                     i, j, at(i, j));
 396     }
 397   }
 398 }
 399 #endif
 400 
 401 void FromCardCache::clear(uint region_idx) {
 402   uint num_par_remsets = HeapRegionRemSet::num_par_rem_sets();
 403   for (uint i = 0; i < num_par_remsets; i++) {
 404     set(i, region_idx, InvalidCard);
 405   }
 406 }
 407 
 408 void OtherRegionsTable::add_reference(OopOrNarrowOopStar from, uint tid) {
 409   uint cur_hrm_ind = _hr->hrm_index();
 410 
 411   if (G1TraceHeapRegionRememberedSet) {
 412     gclog_or_tty->print_cr("ORT::add_reference_work(" PTR_FORMAT "->" PTR_FORMAT ").",
 413                                                     p2i(from),
 414                                                     UseCompressedOops
 415                                                     ? p2i(oopDesc::load_decode_heap_oop((narrowOop*)from))
 416                                                     : p2i(oopDesc::load_decode_heap_oop((oop*)from)));
 417   }
 418 
 419   int from_card = (int)(uintptr_t(from) >> CardTableModRefBS::card_shift);
 420 
 421   if (G1TraceHeapRegionRememberedSet) {
 422     gclog_or_tty->print_cr("Table for [" PTR_FORMAT "...): card %d (cache = %d)",
 423                   p2i(_hr->bottom()), from_card,
 424                   FromCardCache::at(tid, cur_hrm_ind));
 425   }
 426 
 427   if (FromCardCache::contains_or_replace(tid, cur_hrm_ind, from_card)) {
 428     if (G1TraceHeapRegionRememberedSet) {
 429       gclog_or_tty->print_cr("  from-card cache hit.");
 430     }
 431     assert(contains_reference(from), "We just added it!");
 432     return;
 433   }
 434 
 435   // Note that this may be a continued H region.
 436   HeapRegion* from_hr = _g1h->heap_region_containing(from);
 437   RegionIdx_t from_hrm_ind = (RegionIdx_t) from_hr->hrm_index();
 438 
 439   // If the region is already coarsened, return.
 440   if (_coarse_map.at(from_hrm_ind)) {
 441     if (G1TraceHeapRegionRememberedSet) {
 442       gclog_or_tty->print_cr("  coarse map hit.");
 443     }
 444     assert(contains_reference(from), "We just added it!");
 445     return;
 446   }
 447 
 448   // Otherwise find a per-region table to add it to.
 449   size_t ind = from_hrm_ind & _mod_max_fine_entries_mask;
 450   PerRegionTable* prt = find_region_table(ind, from_hr);
 451   if (prt == NULL) {
 452     MutexLockerEx x(_m, Mutex::_no_safepoint_check_flag);
 453     // Confirm that it's really not there...
 454     prt = find_region_table(ind, from_hr);
 455     if (prt == NULL) {
 456 
 457       uintptr_t from_hr_bot_card_index =
 458         uintptr_t(from_hr->bottom())
 459           >> CardTableModRefBS::card_shift;
 460       CardIdx_t card_index = from_card - from_hr_bot_card_index;
 461       assert(0 <= card_index && (size_t)card_index < HeapRegion::CardsPerRegion,
 462              "Must be in range.");
 463       if (G1HRRSUseSparseTable &&
 464           _sparse_table.add_card(from_hrm_ind, card_index)) {
 465         if (G1RecordHRRSOops) {
 466           HeapRegionRemSet::record(_hr, from);
 467           if (G1TraceHeapRegionRememberedSet) {
 468             gclog_or_tty->print("   Added card " PTR_FORMAT " to region "
 469                                 "[" PTR_FORMAT "...) for ref " PTR_FORMAT ".\n",
 470                                 align_size_down(uintptr_t(from),
 471                                                 CardTableModRefBS::card_size),
 472                                 p2i(_hr->bottom()), p2i(from));
 473           }
 474         }
 475         if (G1TraceHeapRegionRememberedSet) {
 476           gclog_or_tty->print_cr("   added card to sparse table.");
 477         }
 478         assert(contains_reference_locked(from), "We just added it!");
 479         return;
 480       } else {
 481         if (G1TraceHeapRegionRememberedSet) {
 482           gclog_or_tty->print_cr("   [tid %u] sparse table entry "
 483                         "overflow(f: %d, t: %u)",
 484                         tid, from_hrm_ind, cur_hrm_ind);
 485         }
 486       }
 487 
 488       if (_n_fine_entries == _max_fine_entries) {
 489         prt = delete_region_table();
 490         // There is no need to clear the links to the 'all' list here:
 491         // prt will be reused immediately, i.e. remain in the 'all' list.
 492         prt->init(from_hr, false /* clear_links_to_all_list */);
 493       } else {
 494         prt = PerRegionTable::alloc(from_hr);
 495         link_to_all(prt);
 496       }
 497 
 498       PerRegionTable* first_prt = _fine_grain_regions[ind];
 499       prt->set_collision_list_next(first_prt);
 500       // The assignment into _fine_grain_regions allows the prt to
 501       // start being used concurrently. In addition to
 502       // collision_list_next which must be visible (else concurrent
 503       // parsing of the list, if any, may fail to see other entries),
 504       // the content of the prt must be visible (else for instance
 505       // some mark bits may not yet seem cleared or a 'later' update
 506       // performed by a concurrent thread could be undone when the
 507       // zeroing becomes visible). This requires store ordering.
 508       OrderAccess::release_store_ptr((volatile PerRegionTable*)&_fine_grain_regions[ind], prt);
 509       _n_fine_entries++;
 510 
 511       if (G1HRRSUseSparseTable) {
 512         // Transfer from sparse to fine-grain.
 513         SparsePRTEntry *sprt_entry = _sparse_table.get_entry(from_hrm_ind);
 514         assert(sprt_entry != NULL, "There should have been an entry");
 515         for (int i = 0; i < SparsePRTEntry::cards_num(); i++) {
 516           CardIdx_t c = sprt_entry->card(i);
 517           if (c != SparsePRTEntry::NullEntry) {
 518             prt->add_card(c);
 519           }
 520         }
 521         // Now we can delete the sparse entry.
 522         bool res = _sparse_table.delete_entry(from_hrm_ind);
 523         assert(res, "It should have been there.");
 524       }
 525     }
 526     assert(prt != NULL && prt->hr() == from_hr, "consequence");
 527   }
 528   // Note that we can't assert "prt->hr() == from_hr", because of the
 529   // possibility of concurrent reuse.  But see head comment of
 530   // OtherRegionsTable for why this is OK.
 531   assert(prt != NULL, "Inv");
 532 
 533   prt->add_reference(from);
 534 
 535   if (G1RecordHRRSOops) {
 536     HeapRegionRemSet::record(_hr, from);
 537     if (G1TraceHeapRegionRememberedSet) {
 538       gclog_or_tty->print("Added card " PTR_FORMAT " to region "
 539                           "[" PTR_FORMAT "...) for ref " PTR_FORMAT ".\n",
 540                           align_size_down(uintptr_t(from),
 541                                           CardTableModRefBS::card_size),
 542                           p2i(_hr->bottom()), p2i(from));
 543     }
 544   }
 545   assert(contains_reference(from), "We just added it!");
 546 }
 547 
 548 PerRegionTable*
 549 OtherRegionsTable::find_region_table(size_t ind, HeapRegion* hr) const {
 550   assert(ind < _max_fine_entries, "Preconditions.");
 551   PerRegionTable* prt = _fine_grain_regions[ind];
 552   while (prt != NULL && prt->hr() != hr) {
 553     prt = prt->collision_list_next();
 554   }
 555   // Loop postcondition is the method postcondition.
 556   return prt;
 557 }
 558 
 559 jint OtherRegionsTable::_n_coarsenings = 0;
 560 
 561 PerRegionTable* OtherRegionsTable::delete_region_table() {
 562   assert(_m->owned_by_self(), "Precondition");
 563   assert(_n_fine_entries == _max_fine_entries, "Precondition");
 564   PerRegionTable* max = NULL;
 565   jint max_occ = 0;
 566   PerRegionTable** max_prev = NULL;
 567   size_t max_ind;
 568 
 569   size_t i = _fine_eviction_start;
 570   for (size_t k = 0; k < _fine_eviction_sample_size; k++) {
 571     size_t ii = i;
 572     // Make sure we get a non-NULL sample.
 573     while (_fine_grain_regions[ii] == NULL) {
 574       ii++;
 575       if (ii == _max_fine_entries) ii = 0;
 576       guarantee(ii != i, "We must find one.");
 577     }
 578     PerRegionTable** prev = &_fine_grain_regions[ii];
 579     PerRegionTable* cur = *prev;
 580     while (cur != NULL) {
 581       jint cur_occ = cur->occupied();
 582       if (max == NULL || cur_occ > max_occ) {
 583         max = cur;
 584         max_prev = prev;
 585         max_ind = i;
 586         max_occ = cur_occ;
 587       }
 588       prev = cur->collision_list_next_addr();
 589       cur = cur->collision_list_next();
 590     }
 591     i = i + _fine_eviction_stride;
 592     if (i >= _n_fine_entries) i = i - _n_fine_entries;
 593   }
 594 
 595   _fine_eviction_start++;
 596 
 597   if (_fine_eviction_start >= _n_fine_entries) {
 598     _fine_eviction_start -= _n_fine_entries;
 599   }
 600 
 601   guarantee(max != NULL, "Since _n_fine_entries > 0");
 602   guarantee(max_prev != NULL, "Since max != NULL.");
 603 
 604   // Set the corresponding coarse bit.
 605   size_t max_hrm_index = (size_t) max->hr()->hrm_index();
 606   if (!_coarse_map.at(max_hrm_index)) {
 607     _coarse_map.at_put(max_hrm_index, true);
 608     _n_coarse_entries++;
 609     if (G1TraceHeapRegionRememberedSet) {
 610       gclog_or_tty->print("Coarsened entry in region [" PTR_FORMAT "...] "
 611                  "for region [" PTR_FORMAT "...] (" SIZE_FORMAT " coarse entries).\n",
 612                  p2i(_hr->bottom()),
 613                  p2i(max->hr()->bottom()),
 614                  _n_coarse_entries);
 615     }
 616   }
 617 
 618   // Unsplice.
 619   *max_prev = max->collision_list_next();
 620   Atomic::inc(&_n_coarsenings);
 621   _n_fine_entries--;
 622   return max;
 623 }
 624 
 625 void OtherRegionsTable::scrub(CardTableModRefBS* ctbs,
 626                               BitMap* region_bm, BitMap* card_bm) {
 627   // First eliminated garbage regions from the coarse map.
 628   if (G1RSScrubVerbose) {
 629     gclog_or_tty->print_cr("Scrubbing region %u:", _hr->hrm_index());
 630   }
 631 
 632   assert(_coarse_map.size() == region_bm->size(), "Precondition");
 633   if (G1RSScrubVerbose) {
 634     gclog_or_tty->print("   Coarse map: before = " SIZE_FORMAT "...",
 635                         _n_coarse_entries);
 636   }
 637   _coarse_map.set_intersection(*region_bm);
 638   _n_coarse_entries = _coarse_map.count_one_bits();
 639   if (G1RSScrubVerbose) {
 640     gclog_or_tty->print_cr("   after = " SIZE_FORMAT ".", _n_coarse_entries);
 641   }
 642 
 643   // Now do the fine-grained maps.
 644   for (size_t i = 0; i < _max_fine_entries; i++) {
 645     PerRegionTable* cur = _fine_grain_regions[i];
 646     PerRegionTable** prev = &_fine_grain_regions[i];
 647     while (cur != NULL) {
 648       PerRegionTable* nxt = cur->collision_list_next();
 649       // If the entire region is dead, eliminate.
 650       if (G1RSScrubVerbose) {
 651         gclog_or_tty->print_cr("     For other region %u:",
 652                                cur->hr()->hrm_index());
 653       }
 654       if (!region_bm->at((size_t) cur->hr()->hrm_index())) {
 655         *prev = nxt;
 656         cur->set_collision_list_next(NULL);
 657         _n_fine_entries--;
 658         if (G1RSScrubVerbose) {
 659           gclog_or_tty->print_cr("          deleted via region map.");
 660         }
 661         unlink_from_all(cur);
 662         PerRegionTable::free(cur);
 663       } else {
 664         // Do fine-grain elimination.
 665         if (G1RSScrubVerbose) {
 666           gclog_or_tty->print("          occ: before = %4d.", cur->occupied());
 667         }
 668         cur->scrub(ctbs, card_bm);
 669         if (G1RSScrubVerbose) {
 670           gclog_or_tty->print_cr("          after = %4d.", cur->occupied());
 671         }
 672         // Did that empty the table completely?
 673         if (cur->occupied() == 0) {
 674           *prev = nxt;
 675           cur->set_collision_list_next(NULL);
 676           _n_fine_entries--;
 677           unlink_from_all(cur);
 678           PerRegionTable::free(cur);
 679         } else {
 680           prev = cur->collision_list_next_addr();
 681         }
 682       }
 683       cur = nxt;
 684     }
 685   }
 686   // Since we may have deleted a from_card_cache entry from the RS, clear
 687   // the FCC.
 688   clear_fcc();
 689 }
 690 
 691 bool OtherRegionsTable::occupancy_less_or_equal_than(size_t limit) const {
 692   if (limit <= (size_t)G1RSetSparseRegionEntries) {
 693     return occ_coarse() == 0 && _first_all_fine_prts == NULL && occ_sparse() <= limit;
 694   } else {
 695     // Current uses of this method may only use values less than G1RSetSparseRegionEntries
 696     // for the limit. The solution, comparing against occupied() would be too slow
 697     // at this time.
 698     Unimplemented();
 699     return false;
 700   }
 701 }
 702 
 703 bool OtherRegionsTable::is_empty() const {
 704   return occ_sparse() == 0 && occ_coarse() == 0 && _first_all_fine_prts == NULL;
 705 }
 706 
 707 size_t OtherRegionsTable::occupied() const {
 708   size_t sum = occ_fine();
 709   sum += occ_sparse();
 710   sum += occ_coarse();
 711   return sum;
 712 }
 713 
 714 size_t OtherRegionsTable::occ_fine() const {
 715   size_t sum = 0;
 716 
 717   size_t num = 0;
 718   PerRegionTable * cur = _first_all_fine_prts;
 719   while (cur != NULL) {
 720     sum += cur->occupied();
 721     cur = cur->next();
 722     num++;
 723   }
 724   guarantee(num == _n_fine_entries, "just checking");
 725   return sum;
 726 }
 727 
 728 size_t OtherRegionsTable::occ_coarse() const {
 729   return (_n_coarse_entries * HeapRegion::CardsPerRegion);
 730 }
 731 
 732 size_t OtherRegionsTable::occ_sparse() const {
 733   return _sparse_table.occupied();
 734 }
 735 
 736 size_t OtherRegionsTable::mem_size() const {
 737   size_t sum = 0;
 738   // all PRTs are of the same size so it is sufficient to query only one of them.
 739   if (_first_all_fine_prts != NULL) {
 740     assert(_last_all_fine_prts != NULL &&
 741       _first_all_fine_prts->mem_size() == _last_all_fine_prts->mem_size(), "check that mem_size() is constant");
 742     sum += _first_all_fine_prts->mem_size() * _n_fine_entries;
 743   }
 744   sum += (sizeof(PerRegionTable*) * _max_fine_entries);
 745   sum += (_coarse_map.size_in_words() * HeapWordSize);
 746   sum += (_sparse_table.mem_size());
 747   sum += sizeof(OtherRegionsTable) - sizeof(_sparse_table); // Avoid double counting above.
 748   return sum;
 749 }
 750 
 751 size_t OtherRegionsTable::static_mem_size() {
 752   return FromCardCache::static_mem_size();
 753 }
 754 
 755 size_t OtherRegionsTable::fl_mem_size() {
 756   return PerRegionTable::fl_mem_size();
 757 }
 758 
 759 void OtherRegionsTable::clear_fcc() {
 760   FromCardCache::clear(_hr->hrm_index());
 761 }
 762 
 763 void OtherRegionsTable::clear() {
 764   // if there are no entries, skip this step
 765   if (_first_all_fine_prts != NULL) {
 766     guarantee(_first_all_fine_prts != NULL && _last_all_fine_prts != NULL, "just checking");
 767     PerRegionTable::bulk_free(_first_all_fine_prts, _last_all_fine_prts);
 768     memset(_fine_grain_regions, 0, _max_fine_entries * sizeof(_fine_grain_regions[0]));
 769   } else {
 770     guarantee(_first_all_fine_prts == NULL && _last_all_fine_prts == NULL, "just checking");
 771   }
 772 
 773   _first_all_fine_prts = _last_all_fine_prts = NULL;
 774   _sparse_table.clear();
 775   _coarse_map.clear();
 776   _n_fine_entries = 0;
 777   _n_coarse_entries = 0;
 778 
 779   clear_fcc();
 780 }
 781 
 782 bool OtherRegionsTable::contains_reference(OopOrNarrowOopStar from) const {
 783   // Cast away const in this case.
 784   MutexLockerEx x((Mutex*)_m, Mutex::_no_safepoint_check_flag);
 785   return contains_reference_locked(from);
 786 }
 787 
 788 bool OtherRegionsTable::contains_reference_locked(OopOrNarrowOopStar from) const {
 789   HeapRegion* hr = _g1h->heap_region_containing(from);
 790   RegionIdx_t hr_ind = (RegionIdx_t) hr->hrm_index();
 791   // Is this region in the coarse map?
 792   if (_coarse_map.at(hr_ind)) return true;
 793 
 794   PerRegionTable* prt = find_region_table(hr_ind & _mod_max_fine_entries_mask,
 795                                      hr);
 796   if (prt != NULL) {
 797     return prt->contains_reference(from);
 798 
 799   } else {
 800     uintptr_t from_card =
 801       (uintptr_t(from) >> CardTableModRefBS::card_shift);
 802     uintptr_t hr_bot_card_index =
 803       uintptr_t(hr->bottom()) >> CardTableModRefBS::card_shift;
 804     assert(from_card >= hr_bot_card_index, "Inv");
 805     CardIdx_t card_index = from_card - hr_bot_card_index;
 806     assert(0 <= card_index && (size_t)card_index < HeapRegion::CardsPerRegion,
 807            "Must be in range.");
 808     return _sparse_table.contains_card(hr_ind, card_index);
 809   }
 810 }
 811 
 812 void
 813 OtherRegionsTable::do_cleanup_work(HRRSCleanupTask* hrrs_cleanup_task) {
 814   _sparse_table.do_cleanup_work(hrrs_cleanup_task);
 815 }
 816 
 817 // Determines how many threads can add records to an rset in parallel.
 818 // This can be done by either mutator threads together with the
 819 // concurrent refinement threads or GC threads.
 820 uint HeapRegionRemSet::num_par_rem_sets() {
 821   return MAX2(DirtyCardQueueSet::num_par_ids() + ConcurrentG1Refine::thread_num(), ParallelGCThreads);
 822 }
 823 
 824 HeapRegionRemSet::HeapRegionRemSet(G1BlockOffsetSharedArray* bosa,
 825                                    HeapRegion* hr)
 826   : _bosa(bosa),
 827     _m(Mutex::leaf, FormatBuffer<128>("HeapRegionRemSet lock #%u", hr->hrm_index()), true, Monitor::_safepoint_check_never),
 828     _code_roots(), _other_regions(hr, &_m), _iter_state(Unclaimed), _iter_claimed(0) {
 829   reset_for_par_iteration();
 830 }
 831 
 832 void HeapRegionRemSet::setup_remset_size() {
 833   // Setup sparse and fine-grain tables sizes.
 834   // table_size = base * (log(region_size / 1M) + 1)
 835   const int LOG_M = 20;
 836   int region_size_log_mb = MAX2(HeapRegion::LogOfHRGrainBytes - LOG_M, 0);
 837   if (FLAG_IS_DEFAULT(G1RSetSparseRegionEntries)) {
 838     G1RSetSparseRegionEntries = G1RSetSparseRegionEntriesBase * (region_size_log_mb + 1);
 839   }
 840   if (FLAG_IS_DEFAULT(G1RSetRegionEntries)) {
 841     G1RSetRegionEntries = G1RSetRegionEntriesBase * (region_size_log_mb + 1);
 842   }
 843   guarantee(G1RSetSparseRegionEntries > 0 && G1RSetRegionEntries > 0 , "Sanity");
 844 }
 845 
 846 bool HeapRegionRemSet::claim_iter() {
 847   if (_iter_state != Unclaimed) return false;
 848   jint res = Atomic::cmpxchg(Claimed, (jint*)(&_iter_state), Unclaimed);
 849   return (res == Unclaimed);
 850 }
 851 
 852 void HeapRegionRemSet::set_iter_complete() {
 853   _iter_state = Complete;
 854 }
 855 
 856 bool HeapRegionRemSet::iter_is_complete() {
 857   return _iter_state == Complete;
 858 }
 859 
 860 #ifndef PRODUCT
 861 void HeapRegionRemSet::print() {
 862   HeapRegionRemSetIterator iter(this);
 863   size_t card_index;
 864   while (iter.has_next(card_index)) {
 865     HeapWord* card_start =
 866       G1CollectedHeap::heap()->bot_shared()->address_for_index(card_index);
 867     gclog_or_tty->print_cr("  Card " PTR_FORMAT, p2i(card_start));
 868   }
 869   if (iter.n_yielded() != occupied()) {
 870     gclog_or_tty->print_cr("Yielded disagrees with occupied:");
 871     gclog_or_tty->print_cr("  " SIZE_FORMAT_W(6) " yielded (" SIZE_FORMAT_W(6)
 872                   " coarse, " SIZE_FORMAT_W(6) " fine).",
 873                   iter.n_yielded(),
 874                   iter.n_yielded_coarse(), iter.n_yielded_fine());
 875     gclog_or_tty->print_cr("  " SIZE_FORMAT_W(6) " occ     (" SIZE_FORMAT_W(6)
 876                            " coarse, " SIZE_FORMAT_W(6) " fine).",
 877                   occupied(), occ_coarse(), occ_fine());
 878   }
 879   guarantee(iter.n_yielded() == occupied(),
 880             "We should have yielded all the represented cards.");
 881 }
 882 #endif
 883 
 884 void HeapRegionRemSet::cleanup() {
 885   SparsePRT::cleanup_all();
 886 }
 887 
 888 void HeapRegionRemSet::clear() {
 889   MutexLockerEx x(&_m, Mutex::_no_safepoint_check_flag);
 890   clear_locked();
 891 }
 892 
 893 void HeapRegionRemSet::clear_locked() {
 894   _code_roots.clear();
 895   _other_regions.clear();
 896   assert(occupied_locked() == 0, "Should be clear.");
 897   reset_for_par_iteration();
 898 }
 899 
 900 void HeapRegionRemSet::reset_for_par_iteration() {
 901   _iter_state = Unclaimed;
 902   _iter_claimed = 0;
 903   // It's good to check this to make sure that the two methods are in sync.
 904   assert(verify_ready_for_par_iteration(), "post-condition");
 905 }
 906 
 907 void HeapRegionRemSet::scrub(CardTableModRefBS* ctbs,
 908                              BitMap* region_bm, BitMap* card_bm) {
 909   _other_regions.scrub(ctbs, region_bm, card_bm);
 910 }
 911 
 912 // Code roots support
 913 //
 914 // The code root set is protected by two separate locking schemes
 915 // When at safepoint the per-hrrs lock must be held during modifications
 916 // except when doing a full gc.
 917 // When not at safepoint the CodeCache_lock must be held during modifications.
 918 // When concurrent readers access the contains() function
 919 // (during the evacuation phase) no removals are allowed.
 920 
 921 void HeapRegionRemSet::add_strong_code_root(nmethod* nm) {
 922   assert(nm != NULL, "sanity");
 923   // Optimistic unlocked contains-check
 924   if (!_code_roots.contains(nm)) {
 925     MutexLockerEx ml(&_m, Mutex::_no_safepoint_check_flag);
 926     add_strong_code_root_locked(nm);
 927   }
 928 }
 929 
 930 void HeapRegionRemSet::add_strong_code_root_locked(nmethod* nm) {
 931   assert(nm != NULL, "sanity");
 932   _code_roots.add(nm);
 933 }
 934 
 935 void HeapRegionRemSet::remove_strong_code_root(nmethod* nm) {
 936   assert(nm != NULL, "sanity");
 937   assert_locked_or_safepoint(CodeCache_lock);
 938 
 939   MutexLockerEx ml(CodeCache_lock->owned_by_self() ? NULL : &_m, Mutex::_no_safepoint_check_flag);
 940   _code_roots.remove(nm);
 941 
 942   // Check that there were no duplicates
 943   guarantee(!_code_roots.contains(nm), "duplicate entry found");
 944 }
 945 
 946 void HeapRegionRemSet::strong_code_roots_do(CodeBlobClosure* blk) const {
 947   _code_roots.nmethods_do(blk);
 948 }
 949 
 950 void HeapRegionRemSet::clean_strong_code_roots(HeapRegion* hr) {
 951   _code_roots.clean(hr);
 952 }
 953 
 954 size_t HeapRegionRemSet::strong_code_roots_mem_size() {
 955   return _code_roots.mem_size();
 956 }
 957 
 958 HeapRegionRemSetIterator:: HeapRegionRemSetIterator(HeapRegionRemSet* hrrs) :
 959   _hrrs(hrrs),
 960   _g1h(G1CollectedHeap::heap()),
 961   _coarse_map(&hrrs->_other_regions._coarse_map),
 962   _bosa(hrrs->_bosa),
 963   _is(Sparse),
 964   // Set these values so that we increment to the first region.
 965   _coarse_cur_region_index(-1),
 966   _coarse_cur_region_cur_card(HeapRegion::CardsPerRegion-1),
 967   _cur_card_in_prt(HeapRegion::CardsPerRegion),
 968   _fine_cur_prt(NULL),
 969   _n_yielded_coarse(0),
 970   _n_yielded_fine(0),
 971   _n_yielded_sparse(0),
 972   _sparse_iter(&hrrs->_other_regions._sparse_table) {}
 973 
 974 bool HeapRegionRemSetIterator::coarse_has_next(size_t& card_index) {
 975   if (_hrrs->_other_regions._n_coarse_entries == 0) return false;
 976   // Go to the next card.
 977   _coarse_cur_region_cur_card++;
 978   // Was the last the last card in the current region?
 979   if (_coarse_cur_region_cur_card == HeapRegion::CardsPerRegion) {
 980     // Yes: find the next region.  This may leave _coarse_cur_region_index
 981     // Set to the last index, in which case there are no more coarse
 982     // regions.
 983     _coarse_cur_region_index =
 984       (int) _coarse_map->get_next_one_offset(_coarse_cur_region_index + 1);
 985     if ((size_t)_coarse_cur_region_index < _coarse_map->size()) {
 986       _coarse_cur_region_cur_card = 0;
 987       HeapWord* r_bot =
 988         _g1h->region_at((uint) _coarse_cur_region_index)->bottom();
 989       _cur_region_card_offset = _bosa->index_for(r_bot);
 990     } else {
 991       return false;
 992     }
 993   }
 994   // If we didn't return false above, then we can yield a card.
 995   card_index = _cur_region_card_offset + _coarse_cur_region_cur_card;
 996   return true;
 997 }
 998 
 999 bool HeapRegionRemSetIterator::fine_has_next(size_t& card_index) {
1000   if (fine_has_next()) {
1001     _cur_card_in_prt =
1002       _fine_cur_prt->_bm.get_next_one_offset(_cur_card_in_prt + 1);
1003   }
1004   if (_cur_card_in_prt == HeapRegion::CardsPerRegion) {
1005     // _fine_cur_prt may still be NULL in case if there are not PRTs at all for
1006     // the remembered set.
1007     if (_fine_cur_prt == NULL || _fine_cur_prt->next() == NULL) {
1008       return false;
1009     }
1010     PerRegionTable* next_prt = _fine_cur_prt->next();
1011     switch_to_prt(next_prt);
1012     _cur_card_in_prt = _fine_cur_prt->_bm.get_next_one_offset(_cur_card_in_prt + 1);
1013   }
1014 
1015   card_index = _cur_region_card_offset + _cur_card_in_prt;
1016   guarantee(_cur_card_in_prt < HeapRegion::CardsPerRegion,
1017             "Card index " SIZE_FORMAT " must be within the region", _cur_card_in_prt);
1018   return true;
1019 }
1020 
1021 bool HeapRegionRemSetIterator::fine_has_next() {
1022   return _cur_card_in_prt != HeapRegion::CardsPerRegion;
1023 }
1024 
1025 void HeapRegionRemSetIterator::switch_to_prt(PerRegionTable* prt) {
1026   assert(prt != NULL, "Cannot switch to NULL prt");
1027   _fine_cur_prt = prt;
1028 
1029   HeapWord* r_bot = _fine_cur_prt->hr()->bottom();
1030   _cur_region_card_offset = _bosa->index_for(r_bot);
1031 
1032   // The bitmap scan for the PRT always scans from _cur_region_cur_card + 1.
1033   // To avoid special-casing this start case, and not miss the first bitmap
1034   // entry, initialize _cur_region_cur_card with -1 instead of 0.
1035   _cur_card_in_prt = (size_t)-1;
1036 }
1037 
1038 bool HeapRegionRemSetIterator::has_next(size_t& card_index) {
1039   switch (_is) {
1040   case Sparse: {
1041     if (_sparse_iter.has_next(card_index)) {
1042       _n_yielded_sparse++;
1043       return true;
1044     }
1045     // Otherwise, deliberate fall-through
1046     _is = Fine;
1047     PerRegionTable* initial_fine_prt = _hrrs->_other_regions._first_all_fine_prts;
1048     if (initial_fine_prt != NULL) {
1049       switch_to_prt(_hrrs->_other_regions._first_all_fine_prts);
1050     }
1051   }
1052   case Fine:
1053     if (fine_has_next(card_index)) {
1054       _n_yielded_fine++;
1055       return true;
1056     }
1057     // Otherwise, deliberate fall-through
1058     _is = Coarse;
1059   case Coarse:
1060     if (coarse_has_next(card_index)) {
1061       _n_yielded_coarse++;
1062       return true;
1063     }
1064     // Otherwise...
1065     break;
1066   }
1067   assert(ParallelGCThreads > 1 ||
1068          n_yielded() == _hrrs->occupied(),
1069          "Should have yielded all the cards in the rem set "
1070          "(in the non-par case).");
1071   return false;
1072 }
1073 
1074 
1075 
1076 OopOrNarrowOopStar* HeapRegionRemSet::_recorded_oops = NULL;
1077 HeapWord**          HeapRegionRemSet::_recorded_cards = NULL;
1078 HeapRegion**        HeapRegionRemSet::_recorded_regions = NULL;
1079 int                 HeapRegionRemSet::_n_recorded = 0;
1080 
1081 HeapRegionRemSet::Event* HeapRegionRemSet::_recorded_events = NULL;
1082 int*         HeapRegionRemSet::_recorded_event_index = NULL;
1083 int          HeapRegionRemSet::_n_recorded_events = 0;
1084 
1085 void HeapRegionRemSet::record(HeapRegion* hr, OopOrNarrowOopStar f) {
1086   if (_recorded_oops == NULL) {
1087     assert(_n_recorded == 0
1088            && _recorded_cards == NULL
1089            && _recorded_regions == NULL,
1090            "Inv");
1091     _recorded_oops    = NEW_C_HEAP_ARRAY(OopOrNarrowOopStar, MaxRecorded, mtGC);
1092     _recorded_cards   = NEW_C_HEAP_ARRAY(HeapWord*,          MaxRecorded, mtGC);
1093     _recorded_regions = NEW_C_HEAP_ARRAY(HeapRegion*,        MaxRecorded, mtGC);
1094   }
1095   if (_n_recorded == MaxRecorded) {
1096     gclog_or_tty->print_cr("Filled up 'recorded' (%d).", MaxRecorded);
1097   } else {
1098     _recorded_cards[_n_recorded] =
1099       (HeapWord*)align_size_down(uintptr_t(f),
1100                                  CardTableModRefBS::card_size);
1101     _recorded_oops[_n_recorded] = f;
1102     _recorded_regions[_n_recorded] = hr;
1103     _n_recorded++;
1104   }
1105 }
1106 
1107 void HeapRegionRemSet::record_event(Event evnt) {
1108   if (!G1RecordHRRSEvents) return;
1109 
1110   if (_recorded_events == NULL) {
1111     assert(_n_recorded_events == 0
1112            && _recorded_event_index == NULL,
1113            "Inv");
1114     _recorded_events = NEW_C_HEAP_ARRAY(Event, MaxRecordedEvents, mtGC);
1115     _recorded_event_index = NEW_C_HEAP_ARRAY(int, MaxRecordedEvents, mtGC);
1116   }
1117   if (_n_recorded_events == MaxRecordedEvents) {
1118     gclog_or_tty->print_cr("Filled up 'recorded_events' (%d).", MaxRecordedEvents);
1119   } else {
1120     _recorded_events[_n_recorded_events] = evnt;
1121     _recorded_event_index[_n_recorded_events] = _n_recorded;
1122     _n_recorded_events++;
1123   }
1124 }
1125 
1126 void HeapRegionRemSet::print_event(outputStream* str, Event evnt) {
1127   switch (evnt) {
1128   case Event_EvacStart:
1129     str->print("Evac Start");
1130     break;
1131   case Event_EvacEnd:
1132     str->print("Evac End");
1133     break;
1134   case Event_RSUpdateEnd:
1135     str->print("RS Update End");
1136     break;
1137   }
1138 }
1139 
1140 void HeapRegionRemSet::print_recorded() {
1141   int cur_evnt = 0;
1142   Event cur_evnt_kind = Event_illegal;
1143   int cur_evnt_ind = 0;
1144   if (_n_recorded_events > 0) {
1145     cur_evnt_kind = _recorded_events[cur_evnt];
1146     cur_evnt_ind = _recorded_event_index[cur_evnt];
1147   }
1148 
1149   for (int i = 0; i < _n_recorded; i++) {
1150     while (cur_evnt < _n_recorded_events && i == cur_evnt_ind) {
1151       gclog_or_tty->print("Event: ");
1152       print_event(gclog_or_tty, cur_evnt_kind);
1153       gclog_or_tty->cr();
1154       cur_evnt++;
1155       if (cur_evnt < MaxRecordedEvents) {
1156         cur_evnt_kind = _recorded_events[cur_evnt];
1157         cur_evnt_ind = _recorded_event_index[cur_evnt];
1158       }
1159     }
1160     gclog_or_tty->print("Added card " PTR_FORMAT " to region [" PTR_FORMAT "...]"
1161                         " for ref " PTR_FORMAT ".\n",
1162                         p2i(_recorded_cards[i]), p2i(_recorded_regions[i]->bottom()),
1163                         p2i(_recorded_oops[i]));
1164   }
1165 }
1166 
1167 void HeapRegionRemSet::reset_for_cleanup_tasks() {
1168   SparsePRT::reset_for_cleanup_tasks();
1169 }
1170 
1171 void HeapRegionRemSet::do_cleanup_work(HRRSCleanupTask* hrrs_cleanup_task) {
1172   _other_regions.do_cleanup_work(hrrs_cleanup_task);
1173 }
1174 
1175 void
1176 HeapRegionRemSet::finish_cleanup_task(HRRSCleanupTask* hrrs_cleanup_task) {
1177   SparsePRT::finish_cleanup_task(hrrs_cleanup_task);
1178 }
1179 
1180 #ifndef PRODUCT
1181 void PerRegionTable::test_fl_mem_size() {
1182   PerRegionTable* dummy = alloc(NULL);
1183 
1184   size_t min_prt_size = sizeof(void*) + dummy->bm()->size_in_words() * HeapWordSize;
1185   assert(dummy->mem_size() > min_prt_size,
1186          "PerRegionTable memory usage is suspiciously small, only has " SIZE_FORMAT " bytes. "
1187          "Should be at least " SIZE_FORMAT " bytes.", dummy->mem_size(), min_prt_size);
1188   free(dummy);
1189   guarantee(dummy->mem_size() == fl_mem_size(), "fl_mem_size() does not return the correct element size");
1190   // try to reset the state
1191   _free_list = NULL;
1192   delete dummy;
1193 }
1194 
1195 void HeapRegionRemSet::test_prt() {
1196   PerRegionTable::test_fl_mem_size();
1197 }
1198 
1199 void HeapRegionRemSet::test() {
1200   os::sleep(Thread::current(), (jlong)5000, false);
1201   G1CollectedHeap* g1h = G1CollectedHeap::heap();
1202 
1203   // Run with "-XX:G1LogRSetRegionEntries=2", so that 1 and 5 end up in same
1204   // hash bucket.
1205   HeapRegion* hr0 = g1h->region_at(0);
1206   HeapRegion* hr1 = g1h->region_at(1);
1207   HeapRegion* hr2 = g1h->region_at(5);
1208   HeapRegion* hr3 = g1h->region_at(6);
1209   HeapRegion* hr4 = g1h->region_at(7);
1210   HeapRegion* hr5 = g1h->region_at(8);
1211 
1212   HeapWord* hr1_start = hr1->bottom();
1213   HeapWord* hr1_mid = hr1_start + HeapRegion::GrainWords/2;
1214   HeapWord* hr1_last = hr1->end() - 1;
1215 
1216   HeapWord* hr2_start = hr2->bottom();
1217   HeapWord* hr2_mid = hr2_start + HeapRegion::GrainWords/2;
1218   HeapWord* hr2_last = hr2->end() - 1;
1219 
1220   HeapWord* hr3_start = hr3->bottom();
1221   HeapWord* hr3_mid = hr3_start + HeapRegion::GrainWords/2;
1222   HeapWord* hr3_last = hr3->end() - 1;
1223 
1224   HeapRegionRemSet* hrrs = hr0->rem_set();
1225 
1226   // Make three references from region 0x101...
1227   hrrs->add_reference((OopOrNarrowOopStar)hr1_start);
1228   hrrs->add_reference((OopOrNarrowOopStar)hr1_mid);
1229   hrrs->add_reference((OopOrNarrowOopStar)hr1_last);
1230 
1231   hrrs->add_reference((OopOrNarrowOopStar)hr2_start);
1232   hrrs->add_reference((OopOrNarrowOopStar)hr2_mid);
1233   hrrs->add_reference((OopOrNarrowOopStar)hr2_last);
1234 
1235   hrrs->add_reference((OopOrNarrowOopStar)hr3_start);
1236   hrrs->add_reference((OopOrNarrowOopStar)hr3_mid);
1237   hrrs->add_reference((OopOrNarrowOopStar)hr3_last);
1238 
1239   // Now cause a coarsening.
1240   hrrs->add_reference((OopOrNarrowOopStar)hr4->bottom());
1241   hrrs->add_reference((OopOrNarrowOopStar)hr5->bottom());
1242 
1243   // Now, does iteration yield these three?
1244   HeapRegionRemSetIterator iter(hrrs);
1245   size_t sum = 0;
1246   size_t card_index;
1247   while (iter.has_next(card_index)) {
1248     HeapWord* card_start =
1249       G1CollectedHeap::heap()->bot_shared()->address_for_index(card_index);
1250     gclog_or_tty->print_cr("  Card " PTR_FORMAT ".", p2i(card_start));
1251     sum++;
1252   }
1253   guarantee(sum == 11 - 3 + 2048, "Failure");
1254   guarantee(sum == hrrs->occupied(), "Failure");
1255 }
1256 #endif