--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/share/vm/gc_implementation/g1/heapRegionRemSet.cpp	Thu Jun 05 15:57:56 2008 -0700
@@ -0,0 +1,1443 @@
+/*
+ * Copyright 2001-2007 Sun Microsystems, Inc.  All Rights Reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ *
+ */
+
+#include "incls/_precompiled.incl"
+#include "incls/_heapRegionRemSet.cpp.incl"
+
+#define HRRS_VERBOSE 0
+
+#define PRT_COUNT_OCCUPIED 1
+
+// OtherRegionsTable
+
+class PerRegionTable: public CHeapObj {
+  friend class OtherRegionsTable;
+  friend class HeapRegionRemSetIterator;
+
+  HeapRegion*     _hr;
+  BitMap          _bm;
+#if PRT_COUNT_OCCUPIED
+  jint            _occupied;
+#endif
+  PerRegionTable* _next_free;
+
+  PerRegionTable* next_free() { return _next_free; }
+  void set_next_free(PerRegionTable* prt) { _next_free = prt; }
+
+
+  static PerRegionTable* _free_list;
+
+#ifdef _MSC_VER
+  // For some reason even though the classes are marked as friend they are unable
+  // to access CardsPerRegion when private/protected. Only the windows c++ compiler
+  // says this Sun CC and linux gcc don't have a problem with access when private
+
+  public:
+
+#endif // _MSC_VER
+
+  enum SomePrivateConstants {
+    CardsPerRegion = HeapRegion::GrainBytes >> CardTableModRefBS::card_shift
+  };
+
+protected:
+  // We need access in order to union things into the base table.
+  BitMap* bm() { return &_bm; }
+
+  void recount_occupied() {
+    _occupied = (jint) bm()->count_one_bits();
+  }
+
+  PerRegionTable(HeapRegion* hr) :
+    _hr(hr),
+#if PRT_COUNT_OCCUPIED
+    _occupied(0),
+#endif
+    _bm(CardsPerRegion, false /* in-resource-area */)
+  {}
+
+  static void free(PerRegionTable* prt) {
+    while (true) {
+      PerRegionTable* fl = _free_list;
+      prt->set_next_free(fl);
+      PerRegionTable* res =
+        (PerRegionTable*)
+        Atomic::cmpxchg_ptr(prt, &_free_list, fl);
+      if (res == fl) return;
+    }
+    ShouldNotReachHere();
+  }
+
+  static PerRegionTable* alloc(HeapRegion* hr) {
+    PerRegionTable* fl = _free_list;
+    while (fl != NULL) {
+      PerRegionTable* nxt = fl->next_free();
+      PerRegionTable* res =
+        (PerRegionTable*)
+        Atomic::cmpxchg_ptr(nxt, &_free_list, fl);
+      if (res == fl) {
+        fl->init(hr);
+        return fl;
+      } else {
+        fl = _free_list;
+      }
+    }
+    assert(fl == NULL, "Loop condition.");
+    return new PerRegionTable(hr);
+  }
+
+  void add_card_work(short from_card, bool par) {
+    if (!_bm.at(from_card)) {
+      if (par) {
+        if (_bm.par_at_put(from_card, 1)) {
+#if PRT_COUNT_OCCUPIED
+          Atomic::inc(&_occupied);
+#endif
+        }
+      } else {
+        _bm.at_put(from_card, 1);
+#if PRT_COUNT_OCCUPIED
+        _occupied++;
+#endif
+      }
+    }
+  }
+
+  void add_reference_work(oop* from, bool par) {
+    // Must make this robust in case "from" is not in "_hr", because of
+    // concurrency.
+
+#if HRRS_VERBOSE
+    gclog_or_tty->print_cr("    PRT::Add_reference_work(" PTR_FORMAT "->" PTR_FORMAT").",
+                           from, *from);
+#endif
+
+    HeapRegion* loc_hr = hr();
+    // If the test below fails, then this table was reused concurrently
+    // with this operation.  This is OK, since the old table was coarsened,
+    // and adding a bit to the new table is never incorrect.
+    if (loc_hr->is_in_reserved(from)) {
+      size_t hw_offset = pointer_delta((HeapWord*)from, loc_hr->bottom());
+      size_t from_card =
+        hw_offset >>
+        (CardTableModRefBS::card_shift - LogHeapWordSize);
+
+      add_card_work((short) from_card, par);
+    }
+  }
+
+public:
+
+  HeapRegion* hr() const { return _hr; }
+
+#if PRT_COUNT_OCCUPIED
+  jint occupied() const {
+    // Overkill, but if we ever need it...
+    // guarantee(_occupied == _bm.count_one_bits(), "Check");
+    return _occupied;
+  }
+#else
+  jint occupied() const {
+    return _bm.count_one_bits();
+  }
+#endif
+
+  void init(HeapRegion* hr) {
+    _hr = hr;
+#if PRT_COUNT_OCCUPIED
+    _occupied = 0;
+#endif
+    _bm.clear();
+  }
+
+  void add_reference(oop* from) {
+    add_reference_work(from, /*parallel*/ true);
+  }
+
+  void seq_add_reference(oop* from) {
+    add_reference_work(from, /*parallel*/ false);
+  }
+
+  void scrub(CardTableModRefBS* ctbs, BitMap* card_bm) {
+    HeapWord* hr_bot = hr()->bottom();
+    int hr_first_card_index = ctbs->index_for(hr_bot);
+    bm()->set_intersection_at_offset(*card_bm, hr_first_card_index);
+#if PRT_COUNT_OCCUPIED
+    recount_occupied();
+#endif
+  }
+
+  void add_card(short from_card_index) {
+    add_card_work(from_card_index, /*parallel*/ true);
+  }
+
+  void seq_add_card(short from_card_index) {
+    add_card_work(from_card_index, /*parallel*/ false);
+  }
+
+  // (Destructively) union the bitmap of the current table into the given
+  // bitmap (which is assumed to be of the same size.)
+  void union_bitmap_into(BitMap* bm) {
+    bm->set_union(_bm);
+  }
+
+  // Mem size in bytes.
+  size_t mem_size() const {
+    return sizeof(this) + _bm.size_in_words() * HeapWordSize;
+  }
+
+  static size_t fl_mem_size() {
+    PerRegionTable* cur = _free_list;
+    size_t res = 0;
+    while (cur != NULL) {
+      res += sizeof(PerRegionTable);
+      cur = cur->next_free();
+    }
+    return res;
+  }
+
+  // Requires "from" to be in "hr()".
+  bool contains_reference(oop* from) const {
+    assert(hr()->is_in_reserved(from), "Precondition.");
+    size_t card_ind = pointer_delta(from, hr()->bottom(),
+                                    CardTableModRefBS::card_size);
+    return _bm.at(card_ind);
+  }
+};
+
+PerRegionTable* PerRegionTable::_free_list = NULL;
+
+
+#define COUNT_PAR_EXPANDS 0
+
+#if COUNT_PAR_EXPANDS
+static jint n_par_expands = 0;
+static jint n_par_contracts = 0;
+static jint par_expand_list_len = 0;
+static jint max_par_expand_list_len = 0;
+
+static void print_par_expand() {
+  Atomic::inc(&n_par_expands);
+  Atomic::inc(&par_expand_list_len);
+  if (par_expand_list_len > max_par_expand_list_len) {
+    max_par_expand_list_len = par_expand_list_len;
+  }
+  if ((n_par_expands % 10) == 0) {
+    gclog_or_tty->print_cr("\n\n%d par expands: %d contracts, "
+                  "len = %d, max_len = %d\n.",
+                  n_par_expands, n_par_contracts, par_expand_list_len,
+                  max_par_expand_list_len);
+  }
+}
+#endif
+
+class PosParPRT: public PerRegionTable {
+  PerRegionTable** _par_tables;
+
+  enum SomePrivateConstants {
+    ReserveParTableExpansion = 1
+  };
+
+  void par_expand() {
+    int n = HeapRegionRemSet::num_par_rem_sets()-1;
+    if (n <= 0) return;
+    if (_par_tables == NULL) {
+      PerRegionTable* res =
+        (PerRegionTable*)
+        Atomic::cmpxchg_ptr((PerRegionTable*)ReserveParTableExpansion,
+                            &_par_tables, NULL);
+      if (res != NULL) return;
+      // Otherwise, we reserved the right to do the expansion.
+
+      PerRegionTable** ptables = NEW_C_HEAP_ARRAY(PerRegionTable*, n);
+      for (int i = 0; i < n; i++) {
+        PerRegionTable* ptable = PerRegionTable::alloc(hr());
+        ptables[i] = ptable;
+      }
+      // Here we do not need an atomic.
+      _par_tables = ptables;
+#if COUNT_PAR_EXPANDS
+      print_par_expand();
+#endif
+      // We must put this table on the expanded list.
+      PosParPRT* exp_head = _par_expanded_list;
+      while (true) {
+        set_next_par_expanded(exp_head);
+        PosParPRT* res =
+          (PosParPRT*)
+          Atomic::cmpxchg_ptr(this, &_par_expanded_list, exp_head);
+        if (res == exp_head) return;
+        // Otherwise.
+        exp_head = res;
+      }
+      ShouldNotReachHere();
+    }
+  }
+
+  void par_contract() {
+    assert(_par_tables != NULL, "Precondition.");
+    int n = HeapRegionRemSet::num_par_rem_sets()-1;
+    for (int i = 0; i < n; i++) {
+      _par_tables[i]->union_bitmap_into(bm());
+      PerRegionTable::free(_par_tables[i]);
+      _par_tables[i] = NULL;
+    }
+#if PRT_COUNT_OCCUPIED
+    // We must recount the "occupied."
+    recount_occupied();
+#endif
+    FREE_C_HEAP_ARRAY(PerRegionTable*, _par_tables);
+    _par_tables = NULL;
+#if COUNT_PAR_EXPANDS
+    Atomic::inc(&n_par_contracts);
+    Atomic::dec(&par_expand_list_len);
+#endif
+  }
+
+  static PerRegionTable** _par_table_fl;
+
+  PosParPRT* _next;
+
+  static PosParPRT* _free_list;
+
+  PerRegionTable** par_tables() const {
+    assert(uintptr_t(NULL) == 0, "Assumption.");
+    if (uintptr_t(_par_tables) <= ReserveParTableExpansion)
+      return NULL;
+    else
+      return _par_tables;
+  }
+
+  PosParPRT* _next_par_expanded;
+  PosParPRT* next_par_expanded() { return _next_par_expanded; }
+  void set_next_par_expanded(PosParPRT* ppprt) { _next_par_expanded = ppprt; }
+  static PosParPRT* _par_expanded_list;
+
+public:
+
+  PosParPRT(HeapRegion* hr) : PerRegionTable(hr), _par_tables(NULL) {}
+
+  jint occupied() const {
+    jint res = PerRegionTable::occupied();
+    if (par_tables() != NULL) {
+      for (int i = 0; i < HeapRegionRemSet::num_par_rem_sets()-1; i++) {
+        res += par_tables()[i]->occupied();
+      }
+    }
+    return res;
+  }
+
+  void init(HeapRegion* hr) {
+    PerRegionTable::init(hr);
+    _next = NULL;
+    if (par_tables() != NULL) {
+      for (int i = 0; i < HeapRegionRemSet::num_par_rem_sets()-1; i++) {
+        par_tables()[i]->init(hr);
+      }
+    }
+  }
+
+  static void free(PosParPRT* prt) {
+    while (true) {
+      PosParPRT* fl = _free_list;
+      prt->set_next(fl);
+      PosParPRT* res =
+        (PosParPRT*)
+        Atomic::cmpxchg_ptr(prt, &_free_list, fl);
+      if (res == fl) return;
+    }
+    ShouldNotReachHere();
+  }
+
+  static PosParPRT* alloc(HeapRegion* hr) {
+    PosParPRT* fl = _free_list;
+    while (fl != NULL) {
+      PosParPRT* nxt = fl->next();
+      PosParPRT* res =
+        (PosParPRT*)
+        Atomic::cmpxchg_ptr(nxt, &_free_list, fl);
+      if (res == fl) {
+        fl->init(hr);
+        return fl;
+      } else {
+        fl = _free_list;
+      }
+    }
+    assert(fl == NULL, "Loop condition.");
+    return new PosParPRT(hr);
+  }
+
+  PosParPRT* next() const { return _next; }
+  void set_next(PosParPRT* nxt) { _next = nxt; }
+  PosParPRT** next_addr() { return &_next; }
+
+  void add_reference(oop* from, int tid) {
+    // Expand if necessary.
+    PerRegionTable** pt = par_tables();
+    if (par_tables() == NULL && tid > 0 && hr()->is_gc_alloc_region()) {
+      par_expand();
+      pt = par_tables();
+    }
+    if (pt != NULL) {
+      // We always have to assume that mods to table 0 are in parallel,
+      // because of the claiming scheme in parallel expansion.  A thread
+      // with tid != 0 that finds the table to be NULL, but doesn't succeed
+      // in claiming the right of expanding it, will end up in the else
+      // clause of the above if test.  That thread could be delayed, and a
+      // thread 0 add reference could see the table expanded, and come
+      // here.  Both threads would be adding in parallel.  But we get to
+      // not use atomics for tids > 0.
+      if (tid == 0) {
+        PerRegionTable::add_reference(from);
+      } else {
+        pt[tid-1]->seq_add_reference(from);
+      }
+    } else {
+      // Not expanded -- add to the base table.
+      PerRegionTable::add_reference(from);
+    }
+  }
+
+  void scrub(CardTableModRefBS* ctbs, BitMap* card_bm) {
+    assert(_par_tables == NULL, "Precondition");
+    PerRegionTable::scrub(ctbs, card_bm);
+  }
+
+  size_t mem_size() const {
+    size_t res =
+      PerRegionTable::mem_size() + sizeof(this) - sizeof(PerRegionTable);
+    if (_par_tables != NULL) {
+      for (int i = 0; i < HeapRegionRemSet::num_par_rem_sets()-1; i++) {
+        res += _par_tables[i]->mem_size();
+      }
+    }
+    return res;
+  }
+
+  static size_t fl_mem_size() {
+    PosParPRT* cur = _free_list;
+    size_t res = 0;
+    while (cur != NULL) {
+      res += sizeof(PosParPRT);
+      cur = cur->next();
+    }
+    return res;
+  }
+
+  bool contains_reference(oop* from) const {
+    if (PerRegionTable::contains_reference(from)) return true;
+    if (_par_tables != NULL) {
+      for (int i = 0; i < HeapRegionRemSet::num_par_rem_sets()-1; i++) {
+        if (_par_tables[i]->contains_reference(from)) return true;
+      }
+    }
+    return false;
+  }
+
+  static void par_contract_all();
+
+};
+
+void PosParPRT::par_contract_all() {
+  PosParPRT* hd = _par_expanded_list;
+  while (hd != NULL) {
+    PosParPRT* nxt = hd->next_par_expanded();
+    PosParPRT* res =
+      (PosParPRT*)
+      Atomic::cmpxchg_ptr(nxt, &_par_expanded_list, hd);
+    if (res == hd) {
+      // We claimed the right to contract this table.
+      hd->set_next_par_expanded(NULL);
+      hd->par_contract();
+      hd = _par_expanded_list;
+    } else {
+      hd = res;
+    }
+  }
+}
+
+PosParPRT* PosParPRT::_free_list = NULL;
+PosParPRT* PosParPRT::_par_expanded_list = NULL;
+
+jint OtherRegionsTable::_cache_probes = 0;
+jint OtherRegionsTable::_cache_hits = 0;
+
+size_t OtherRegionsTable::_max_fine_entries = 0;
+size_t OtherRegionsTable::_mod_max_fine_entries_mask = 0;
+#if SAMPLE_FOR_EVICTION
+size_t OtherRegionsTable::_fine_eviction_stride = 0;
+size_t OtherRegionsTable::_fine_eviction_sample_size = 0;
+#endif
+
+OtherRegionsTable::OtherRegionsTable(HeapRegion* hr) :
+  _g1h(G1CollectedHeap::heap()),
+  _m(Mutex::leaf, "An OtherRegionsTable lock", true),
+  _hr(hr),
+  _coarse_map(G1CollectedHeap::heap()->max_regions(),
+              false /* in-resource-area */),
+  _fine_grain_regions(NULL),
+  _n_fine_entries(0), _n_coarse_entries(0),
+#if SAMPLE_FOR_EVICTION
+  _fine_eviction_start(0),
+#endif
+  _sparse_table(hr)
+{
+  typedef PosParPRT* PosParPRTPtr;
+  if (_max_fine_entries == 0) {
+    assert(_mod_max_fine_entries_mask == 0, "Both or none.");
+    _max_fine_entries = (1 << G1LogRSRegionEntries);
+    _mod_max_fine_entries_mask = _max_fine_entries - 1;
+#if SAMPLE_FOR_EVICTION
+    assert(_fine_eviction_sample_size == 0
+           && _fine_eviction_stride == 0, "All init at same time.");
+    _fine_eviction_sample_size = MAX2((size_t)4, (size_t)G1LogRSRegionEntries);
+    _fine_eviction_stride = _max_fine_entries / _fine_eviction_sample_size;
+#endif
+  }
+  _fine_grain_regions = new PosParPRTPtr[_max_fine_entries];
+  if (_fine_grain_regions == NULL)
+    vm_exit_out_of_memory(sizeof(void*)*_max_fine_entries,
+                          "Failed to allocate _fine_grain_entries.");
+  for (size_t i = 0; i < _max_fine_entries; i++) {
+    _fine_grain_regions[i] = NULL;
+  }
+}
+
+int** OtherRegionsTable::_from_card_cache = NULL;
+size_t OtherRegionsTable::_from_card_cache_max_regions = 0;
+size_t OtherRegionsTable::_from_card_cache_mem_size = 0;
+
+void OtherRegionsTable::init_from_card_cache(size_t max_regions) {
+  _from_card_cache_max_regions = max_regions;
+
+  int n_par_rs = HeapRegionRemSet::num_par_rem_sets();
+  _from_card_cache = NEW_C_HEAP_ARRAY(int*, n_par_rs);
+  for (int i = 0; i < n_par_rs; i++) {
+    _from_card_cache[i] = NEW_C_HEAP_ARRAY(int, max_regions);
+    for (size_t j = 0; j < max_regions; j++) {
+      _from_card_cache[i][j] = -1;  // An invalid value.
+    }
+  }
+  _from_card_cache_mem_size = n_par_rs * max_regions * sizeof(int);
+}
+
+void OtherRegionsTable::shrink_from_card_cache(size_t new_n_regs) {
+  for (int i = 0; i < HeapRegionRemSet::num_par_rem_sets(); i++) {
+    assert(new_n_regs <= _from_card_cache_max_regions, "Must be within max.");
+    for (size_t j = new_n_regs; j < _from_card_cache_max_regions; j++) {
+      _from_card_cache[i][j] = -1;  // An invalid value.
+    }
+  }
+}
+
+#ifndef PRODUCT
+void OtherRegionsTable::print_from_card_cache() {
+  for (int i = 0; i < HeapRegionRemSet::num_par_rem_sets(); i++) {
+    for (size_t j = 0; j < _from_card_cache_max_regions; j++) {
+      gclog_or_tty->print_cr("_from_card_cache[%d][%d] = %d.",
+                    i, j, _from_card_cache[i][j]);
+    }
+  }
+}
+#endif
+
+void OtherRegionsTable::add_reference(oop* from, int tid) {
+  size_t cur_hrs_ind = hr()->hrs_index();
+
+#if HRRS_VERBOSE
+  gclog_or_tty->print_cr("ORT::add_reference_work(" PTR_FORMAT "->" PTR_FORMAT ").",
+                                                  from, *from);
+#endif
+
+  int from_card = (int)(uintptr_t(from) >> CardTableModRefBS::card_shift);
+
+#if HRRS_VERBOSE
+  gclog_or_tty->print_cr("Table for [" PTR_FORMAT "...): card %d (cache = %d)",
+                hr()->bottom(), from_card,
+                _from_card_cache[tid][cur_hrs_ind]);
+#endif
+
+#define COUNT_CACHE 0
+#if COUNT_CACHE
+  jint p = Atomic::add(1, &_cache_probes);
+  if ((p % 10000) == 0) {
+    jint hits = _cache_hits;
+    gclog_or_tty->print_cr("%d/%d = %5.2f%% RS cache hits.",
+                  _cache_hits, p, 100.0* (float)hits/(float)p);
+  }
+#endif
+  if (from_card == _from_card_cache[tid][cur_hrs_ind]) {
+#if HRRS_VERBOSE
+    gclog_or_tty->print_cr("  from-card cache hit.");
+#endif
+#if COUNT_CACHE
+    Atomic::inc(&_cache_hits);
+#endif
+    assert(contains_reference(from), "We just added it!");
+    return;
+  } else {
+    _from_card_cache[tid][cur_hrs_ind] = from_card;
+  }
+
+  // Note that this may be a continued H region.
+  HeapRegion* from_hr = _g1h->heap_region_containing_raw(from);
+  size_t from_hrs_ind = (size_t)from_hr->hrs_index();
+
+  // If the region is already coarsened, return.
+  if (_coarse_map.at(from_hrs_ind)) {
+#if HRRS_VERBOSE
+    gclog_or_tty->print_cr("  coarse map hit.");
+#endif
+    assert(contains_reference(from), "We just added it!");
+    return;
+  }
+
+  // Otherwise find a per-region table to add it to.
+  size_t ind = from_hrs_ind & _mod_max_fine_entries_mask;
+  PosParPRT* prt = find_region_table(ind, from_hr);
+  if (prt == NULL) {
+    MutexLockerEx x(&_m, Mutex::_no_safepoint_check_flag);
+    // Confirm that it's really not there...
+    prt = find_region_table(ind, from_hr);
+    if (prt == NULL) {
+
+      uintptr_t from_hr_bot_card_index =
+        uintptr_t(from_hr->bottom())
+          >> CardTableModRefBS::card_shift;
+      int card_index = from_card - from_hr_bot_card_index;
+      assert(0 <= card_index && card_index < PosParPRT::CardsPerRegion,
+             "Must be in range.");
+      if (G1HRRSUseSparseTable &&
+          _sparse_table.add_card((short) from_hrs_ind, card_index)) {
+        if (G1RecordHRRSOops) {
+          HeapRegionRemSet::record(hr(), from);
+#if HRRS_VERBOSE
+          gclog_or_tty->print("   Added card " PTR_FORMAT " to region "
+                              "[" PTR_FORMAT "...) for ref " PTR_FORMAT ".\n",
+                              align_size_down(uintptr_t(from),
+                                              CardTableModRefBS::card_size),
+                              hr()->bottom(), from);
+#endif
+        }
+#if HRRS_VERBOSE
+        gclog_or_tty->print_cr("   added card to sparse table.");
+#endif
+        assert(contains_reference_locked(from), "We just added it!");
+        return;
+      } else {
+#if HRRS_VERBOSE
+        gclog_or_tty->print_cr("   [tid %d] sparse table entry "
+                      "overflow(f: %d, t: %d)",
+                      tid, from_hrs_ind, cur_hrs_ind);
+#endif
+      }
+
+      // Otherwise, transfer from sparse to fine-grain.
+      short cards[SparsePRTEntry::CardsPerEntry];
+      if (G1HRRSUseSparseTable) {
+        bool res = _sparse_table.get_cards((short) from_hrs_ind, &cards[0]);
+        assert(res, "There should have been an entry");
+      }
+
+      if (_n_fine_entries == _max_fine_entries) {
+        prt = delete_region_table();
+      } else {
+        prt = PosParPRT::alloc(from_hr);
+      }
+      prt->init(from_hr);
+      // Record the outgoing pointer in the from_region's outgoing bitmap.
+      from_hr->rem_set()->add_outgoing_reference(hr());
+
+      PosParPRT* first_prt = _fine_grain_regions[ind];
+      prt->set_next(first_prt);  // XXX Maybe move to init?
+      _fine_grain_regions[ind] = prt;
+      _n_fine_entries++;
+
+      // Add in the cards from the sparse table.
+      if (G1HRRSUseSparseTable) {
+        for (int i = 0; i < SparsePRTEntry::CardsPerEntry; i++) {
+          short c = cards[i];
+          if (c != SparsePRTEntry::NullEntry) {
+            prt->add_card(c);
+          }
+        }
+        // Now we can delete the sparse entry.
+        bool res = _sparse_table.delete_entry((short) from_hrs_ind);
+        assert(res, "It should have been there.");
+      }
+    }
+    assert(prt != NULL && prt->hr() == from_hr, "consequence");
+  }
+  // Note that we can't assert "prt->hr() == from_hr", because of the
+  // possibility of concurrent reuse.  But see head comment of
+  // OtherRegionsTable for why this is OK.
+  assert(prt != NULL, "Inv");
+
+  prt->add_reference(from, tid);
+  if (G1RecordHRRSOops) {
+    HeapRegionRemSet::record(hr(), from);
+#if HRRS_VERBOSE
+    gclog_or_tty->print("Added card " PTR_FORMAT " to region "
+                        "[" PTR_FORMAT "...) for ref " PTR_FORMAT ".\n",
+                        align_size_down(uintptr_t(from),
+                                        CardTableModRefBS::card_size),
+                        hr()->bottom(), from);
+#endif
+  }
+  assert(contains_reference(from), "We just added it!");
+}
+
+PosParPRT*
+OtherRegionsTable::find_region_table(size_t ind, HeapRegion* hr) const {
+  assert(0 <= ind && ind < _max_fine_entries, "Preconditions.");
+  PosParPRT* prt = _fine_grain_regions[ind];
+  while (prt != NULL && prt->hr() != hr) {
+    prt = prt->next();
+  }
+  // Loop postcondition is the method postcondition.
+  return prt;
+}
+
+
+#define DRT_CENSUS 0
+
+#if DRT_CENSUS
+static const int HistoSize = 6;
+static int global_histo[HistoSize] = { 0, 0, 0, 0, 0, 0 };
+static int coarsenings = 0;
+static int occ_sum = 0;
+#endif
+
+jint OtherRegionsTable::_n_coarsenings = 0;
+
+PosParPRT* OtherRegionsTable::delete_region_table() {
+#if DRT_CENSUS
+  int histo[HistoSize] = { 0, 0, 0, 0, 0, 0 };
+  const int histo_limits[] = { 1, 4, 16, 64, 256, 2048 };
+#endif
+
+  assert(_m.owned_by_self(), "Precondition");
+  assert(_n_fine_entries == _max_fine_entries, "Precondition");
+  PosParPRT* max = NULL;
+  jint max_occ = 0;
+  PosParPRT** max_prev;
+  size_t max_ind;
+
+#if SAMPLE_FOR_EVICTION
+  size_t i = _fine_eviction_start;
+  for (size_t k = 0; k < _fine_eviction_sample_size; k++) {
+    size_t ii = i;
+    // Make sure we get a non-NULL sample.
+    while (_fine_grain_regions[ii] == NULL) {
+      ii++;
+      if (ii == _max_fine_entries) ii = 0;
+      guarantee(ii != i, "We must find one.");
+    }
+    PosParPRT** prev = &_fine_grain_regions[ii];
+    PosParPRT* cur = *prev;
+    while (cur != NULL) {
+      jint cur_occ = cur->occupied();
+      if (max == NULL || cur_occ > max_occ) {
+        max = cur;
+        max_prev = prev;
+        max_ind = i;
+        max_occ = cur_occ;
+      }
+      prev = cur->next_addr();
+      cur = cur->next();
+    }
+    i = i + _fine_eviction_stride;
+    if (i >= _n_fine_entries) i = i - _n_fine_entries;
+  }
+  _fine_eviction_start++;
+  if (_fine_eviction_start >= _n_fine_entries)
+    _fine_eviction_start -= _n_fine_entries;
+#else
+  for (int i = 0; i < _max_fine_entries; i++) {
+    PosParPRT** prev = &_fine_grain_regions[i];
+    PosParPRT* cur = *prev;
+    while (cur != NULL) {
+      jint cur_occ = cur->occupied();
+#if DRT_CENSUS
+      for (int k = 0; k < HistoSize; k++) {
+        if (cur_occ <= histo_limits[k]) {
+          histo[k]++; global_histo[k]++; break;
+        }
+      }
+#endif
+      if (max == NULL || cur_occ > max_occ) {
+        max = cur;
+        max_prev = prev;
+        max_ind = i;
+        max_occ = cur_occ;
+      }
+      prev = cur->next_addr();
+      cur = cur->next();
+    }
+  }
+#endif
+  // XXX
+  guarantee(max != NULL, "Since _n_fine_entries > 0");
+#if DRT_CENSUS
+  gclog_or_tty->print_cr("In a coarsening: histo of occs:");
+  for (int k = 0; k < HistoSize; k++) {
+    gclog_or_tty->print_cr("  <= %4d: %5d.", histo_limits[k], histo[k]);
+  }
+  coarsenings++;
+  occ_sum += max_occ;
+  if ((coarsenings % 100) == 0) {
+    gclog_or_tty->print_cr("\ncoarsenings = %d; global summary:", coarsenings);
+    for (int k = 0; k < HistoSize; k++) {
+      gclog_or_tty->print_cr("  <= %4d: %5d.", histo_limits[k], global_histo[k]);
+    }
+    gclog_or_tty->print_cr("Avg occ of deleted region = %6.2f.",
+                  (float)occ_sum/(float)coarsenings);
+  }
+#endif
+
+  // Set the corresponding coarse bit.
+  int max_hrs_index = max->hr()->hrs_index();
+  if (!_coarse_map.at(max_hrs_index)) {
+    _coarse_map.at_put(max_hrs_index, true);
+    _n_coarse_entries++;
+#if 0
+    gclog_or_tty->print("Coarsened entry in region [" PTR_FORMAT "...] "
+               "for region [" PTR_FORMAT "...] (%d coarse entries).\n",
+               hr()->bottom(),
+               max->hr()->bottom(),
+               _n_coarse_entries);
+#endif
+  }
+
+  // Unsplice.
+  *max_prev = max->next();
+  Atomic::inc(&_n_coarsenings);
+  _n_fine_entries--;
+  return max;
+}
+
+
+// At present, this must be called stop-world single-threaded.
+void OtherRegionsTable::scrub(CardTableModRefBS* ctbs,
+                              BitMap* region_bm, BitMap* card_bm) {
+  // First eliminated garbage regions from the coarse map.
+  if (G1RSScrubVerbose)
+    gclog_or_tty->print_cr("Scrubbing region %d:", hr()->hrs_index());
+
+  assert(_coarse_map.size() == region_bm->size(), "Precondition");
+  if (G1RSScrubVerbose)
+    gclog_or_tty->print("   Coarse map: before = %d...", _n_coarse_entries);
+  _coarse_map.set_intersection(*region_bm);
+  _n_coarse_entries = _coarse_map.count_one_bits();
+  if (G1RSScrubVerbose)
+    gclog_or_tty->print_cr("   after = %d.", _n_coarse_entries);
+
+  // Now do the fine-grained maps.
+  for (size_t i = 0; i < _max_fine_entries; i++) {
+    PosParPRT* cur = _fine_grain_regions[i];
+    PosParPRT** prev = &_fine_grain_regions[i];
+    while (cur != NULL) {
+      PosParPRT* nxt = cur->next();
+      // If the entire region is dead, eliminate.
+      if (G1RSScrubVerbose)
+        gclog_or_tty->print_cr("     For other region %d:", cur->hr()->hrs_index());
+      if (!region_bm->at(cur->hr()->hrs_index())) {
+        *prev = nxt;
+        cur->set_next(NULL);
+        _n_fine_entries--;
+        if (G1RSScrubVerbose)
+          gclog_or_tty->print_cr("          deleted via region map.");
+        PosParPRT::free(cur);
+      } else {
+        // Do fine-grain elimination.
+        if (G1RSScrubVerbose)
+          gclog_or_tty->print("          occ: before = %4d.", cur->occupied());
+        cur->scrub(ctbs, card_bm);
+        if (G1RSScrubVerbose)
+          gclog_or_tty->print_cr("          after = %4d.", cur->occupied());
+        // Did that empty the table completely?
+        if (cur->occupied() == 0) {
+          *prev = nxt;
+          cur->set_next(NULL);
+          _n_fine_entries--;
+          PosParPRT::free(cur);
+        } else {
+          prev = cur->next_addr();
+        }
+      }
+      cur = nxt;
+    }
+  }
+  // Since we may have deleted a from_card_cache entry from the RS, clear
+  // the FCC.
+  clear_fcc();
+}
+
+
+size_t OtherRegionsTable::occupied() const {
+  // Cast away const in this case.
+  MutexLockerEx x((Mutex*)&_m, Mutex::_no_safepoint_check_flag);
+  size_t sum = occ_fine();
+  sum += occ_sparse();
+  sum += occ_coarse();
+  return sum;
+}
+
+size_t OtherRegionsTable::occ_fine() const {
+  size_t sum = 0;
+  for (size_t i = 0; i < _max_fine_entries; i++) {
+    PosParPRT* cur = _fine_grain_regions[i];
+    while (cur != NULL) {
+      sum += cur->occupied();
+      cur = cur->next();
+    }
+  }
+  return sum;
+}
+
+size_t OtherRegionsTable::occ_coarse() const {
+  return (_n_coarse_entries * PosParPRT::CardsPerRegion);
+}
+
+size_t OtherRegionsTable::occ_sparse() const {
+  return _sparse_table.occupied();
+}
+
+size_t OtherRegionsTable::mem_size() const {
+  // Cast away const in this case.
+  MutexLockerEx x((Mutex*)&_m, Mutex::_no_safepoint_check_flag);
+  size_t sum = 0;
+  for (size_t i = 0; i < _max_fine_entries; i++) {
+    PosParPRT* cur = _fine_grain_regions[i];
+    while (cur != NULL) {
+      sum += cur->mem_size();
+      cur = cur->next();
+    }
+  }
+  sum += (sizeof(PosParPRT*) * _max_fine_entries);
+  sum += (_coarse_map.size_in_words() * HeapWordSize);
+  sum += (_sparse_table.mem_size());
+  sum += sizeof(*this) - sizeof(_sparse_table); // Avoid double counting above.
+  return sum;
+}
+
+size_t OtherRegionsTable::static_mem_size() {
+  return _from_card_cache_mem_size;
+}
+
+size_t OtherRegionsTable::fl_mem_size() {
+  return PerRegionTable::fl_mem_size() + PosParPRT::fl_mem_size();
+}
+
+void OtherRegionsTable::clear_fcc() {
+  for (int i = 0; i < HeapRegionRemSet::num_par_rem_sets(); i++) {
+    _from_card_cache[i][hr()->hrs_index()] = -1;
+  }
+}
+
+void OtherRegionsTable::clear() {
+  MutexLockerEx x(&_m, Mutex::_no_safepoint_check_flag);
+  for (size_t i = 0; i < _max_fine_entries; i++) {
+    PosParPRT* cur = _fine_grain_regions[i];
+    while (cur != NULL) {
+      PosParPRT* nxt = cur->next();
+      PosParPRT::free(cur);
+      cur = nxt;
+    }
+    _fine_grain_regions[i] = NULL;
+  }
+  _sparse_table.clear();
+  _coarse_map.clear();
+  _n_fine_entries = 0;
+  _n_coarse_entries = 0;
+
+  clear_fcc();
+}
+
+void OtherRegionsTable::clear_incoming_entry(HeapRegion* from_hr) {
+  MutexLockerEx x(&_m, Mutex::_no_safepoint_check_flag);
+  size_t hrs_ind = (size_t)from_hr->hrs_index();
+  size_t ind = hrs_ind & _mod_max_fine_entries_mask;
+  if (del_single_region_table(ind, from_hr)) {
+    assert(!_coarse_map.at(hrs_ind), "Inv");
+  } else {
+    _coarse_map.par_at_put(hrs_ind, 0);
+  }
+  // Check to see if any of the fcc entries come from here.
+  int hr_ind = hr()->hrs_index();
+  for (int tid = 0; tid < HeapRegionRemSet::num_par_rem_sets(); tid++) {
+    int fcc_ent = _from_card_cache[tid][hr_ind];
+    if (fcc_ent != -1) {
+      HeapWord* card_addr = (HeapWord*)
+        (uintptr_t(fcc_ent) << CardTableModRefBS::card_shift);
+      if (hr()->is_in_reserved(card_addr)) {
+        // Clear the from card cache.
+        _from_card_cache[tid][hr_ind] = -1;
+      }
+    }
+  }
+}
+
+bool OtherRegionsTable::del_single_region_table(size_t ind,
+                                                HeapRegion* hr) {
+  assert(0 <= ind && ind < _max_fine_entries, "Preconditions.");
+  PosParPRT** prev_addr = &_fine_grain_regions[ind];
+  PosParPRT* prt = *prev_addr;
+  while (prt != NULL && prt->hr() != hr) {
+    prev_addr = prt->next_addr();
+    prt = prt->next();
+  }
+  if (prt != NULL) {
+    assert(prt->hr() == hr, "Loop postcondition.");
+    *prev_addr = prt->next();
+    PosParPRT::free(prt);
+    _n_fine_entries--;
+    return true;
+  } else {
+    return false;
+  }
+}
+
+bool OtherRegionsTable::contains_reference(oop* from) const {
+  // Cast away const in this case.
+  MutexLockerEx x((Mutex*)&_m, Mutex::_no_safepoint_check_flag);
+  return contains_reference_locked(from);
+}
+
+bool OtherRegionsTable::contains_reference_locked(oop* from) const {
+  HeapRegion* hr = _g1h->heap_region_containing_raw(from);
+  if (hr == NULL) return false;
+  size_t hr_ind = hr->hrs_index();
+  // Is this region in the coarse map?
+  if (_coarse_map.at(hr_ind)) return true;
+
+  PosParPRT* prt = find_region_table(hr_ind & _mod_max_fine_entries_mask,
+                                     hr);
+  if (prt != NULL) {
+    return prt->contains_reference(from);
+
+  } else {
+    uintptr_t from_card =
+      (uintptr_t(from) >> CardTableModRefBS::card_shift);
+    uintptr_t hr_bot_card_index =
+      uintptr_t(hr->bottom()) >> CardTableModRefBS::card_shift;
+    assert(from_card >= hr_bot_card_index, "Inv");
+    int card_index = from_card - hr_bot_card_index;
+    return _sparse_table.contains_card((short)hr_ind, card_index);
+  }
+
+
+}
+
+
+bool HeapRegionRemSet::_par_traversal = false;
+
+void HeapRegionRemSet::set_par_traversal(bool b) {
+  assert(_par_traversal != b, "Proper alternation...");
+  _par_traversal = b;
+}
+
+int HeapRegionRemSet::num_par_rem_sets() {
+  // We always have at least two, so that a mutator thread can claim an
+  // id and add to a rem set.
+  return (int) MAX2(ParallelGCThreads, (size_t)2);
+}
+
+HeapRegionRemSet::HeapRegionRemSet(G1BlockOffsetSharedArray* bosa,
+                                   HeapRegion* hr)
+    : _bosa(bosa), _other_regions(hr),
+      _outgoing_region_map(G1CollectedHeap::heap()->max_regions(),
+                           false /* in-resource-area */),
+      _iter_state(Unclaimed)
+{}
+
+
+void HeapRegionRemSet::init_for_par_iteration() {
+  _iter_state = Unclaimed;
+}
+
+bool HeapRegionRemSet::claim_iter() {
+  if (_iter_state != Unclaimed) return false;
+  jint res = Atomic::cmpxchg(Claimed, (jint*)(&_iter_state), Unclaimed);
+  return (res == Unclaimed);
+}
+
+void HeapRegionRemSet::set_iter_complete() {
+  _iter_state = Complete;
+}
+
+bool HeapRegionRemSet::iter_is_complete() {
+  return _iter_state == Complete;
+}
+
+
+void HeapRegionRemSet::init_iterator(HeapRegionRemSetIterator* iter) const {
+  iter->initialize(this);
+}
+
+#ifndef PRODUCT
+void HeapRegionRemSet::print() const {
+  HeapRegionRemSetIterator iter;
+  init_iterator(&iter);
+  size_t card_index;
+  while (iter.has_next(card_index)) {
+    HeapWord* card_start =
+      G1CollectedHeap::heap()->bot_shared()->address_for_index(card_index);
+    gclog_or_tty->print_cr("  Card " PTR_FORMAT ".", card_start);
+  }
+  // XXX
+  if (iter.n_yielded() != occupied()) {
+    gclog_or_tty->print_cr("Yielded disagrees with occupied:");
+    gclog_or_tty->print_cr("  %6d yielded (%6d coarse, %6d fine).",
+                  iter.n_yielded(),
+                  iter.n_yielded_coarse(), iter.n_yielded_fine());
+    gclog_or_tty->print_cr("  %6d occ     (%6d coarse, %6d fine).",
+                  occupied(), occ_coarse(), occ_fine());
+  }
+  guarantee(iter.n_yielded() == occupied(),
+            "We should have yielded all the represented cards.");
+}
+#endif
+
+void HeapRegionRemSet::cleanup() {
+  SparsePRT::cleanup_all();
+}
+
+void HeapRegionRemSet::par_cleanup() {
+  PosParPRT::par_contract_all();
+}
+
+void HeapRegionRemSet::add_outgoing_reference(HeapRegion* to_hr) {
+  _outgoing_region_map.par_at_put(to_hr->hrs_index(), 1);
+}
+
+void HeapRegionRemSet::clear() {
+  clear_outgoing_entries();
+  _outgoing_region_map.clear();
+  _other_regions.clear();
+  assert(occupied() == 0, "Should be clear.");
+}
+
+void HeapRegionRemSet::clear_outgoing_entries() {
+  G1CollectedHeap* g1h = G1CollectedHeap::heap();
+  size_t i = _outgoing_region_map.get_next_one_offset(0);
+  while (i < _outgoing_region_map.size()) {
+    HeapRegion* to_region = g1h->region_at(i);
+    to_region->rem_set()->clear_incoming_entry(hr());
+    i = _outgoing_region_map.get_next_one_offset(i+1);
+  }
+}
+
+
+void HeapRegionRemSet::scrub(CardTableModRefBS* ctbs,
+                             BitMap* region_bm, BitMap* card_bm) {
+  _other_regions.scrub(ctbs, region_bm, card_bm);
+}
+
+//-------------------- Iteration --------------------
+
+HeapRegionRemSetIterator::
+HeapRegionRemSetIterator() :
+  _hrrs(NULL),
+  _g1h(G1CollectedHeap::heap()),
+  _bosa(NULL),
+  _sparse_iter(size_t(G1CollectedHeap::heap()->reserved_region().start())
+               >> CardTableModRefBS::card_shift)
+{}
+
+void HeapRegionRemSetIterator::initialize(const HeapRegionRemSet* hrrs) {
+  _hrrs = hrrs;
+  _coarse_map = &_hrrs->_other_regions._coarse_map;
+  _fine_grain_regions = _hrrs->_other_regions._fine_grain_regions;
+  _bosa = _hrrs->bosa();
+
+  _is = Sparse;
+  // Set these values so that we increment to the first region.
+  _coarse_cur_region_index = -1;
+  _coarse_cur_region_cur_card = (PosParPRT::CardsPerRegion-1);;
+
+  _cur_region_cur_card = 0;
+
+  _fine_array_index = -1;
+  _fine_cur_prt = NULL;
+
+  _n_yielded_coarse = 0;
+  _n_yielded_fine = 0;
+  _n_yielded_sparse = 0;
+
+  _sparse_iter.init(&hrrs->_other_regions._sparse_table);
+}
+
+bool HeapRegionRemSetIterator::coarse_has_next(size_t& card_index) {
+  if (_hrrs->_other_regions._n_coarse_entries == 0) return false;
+  // Go to the next card.
+  _coarse_cur_region_cur_card++;
+  // Was the last the last card in the current region?
+  if (_coarse_cur_region_cur_card == PosParPRT::CardsPerRegion) {
+    // Yes: find the next region.  This may leave _coarse_cur_region_index
+    // Set to the last index, in which case there are no more coarse
+    // regions.
+    _coarse_cur_region_index =
+      (int) _coarse_map->get_next_one_offset(_coarse_cur_region_index + 1);
+    if ((size_t)_coarse_cur_region_index < _coarse_map->size()) {
+      _coarse_cur_region_cur_card = 0;
+      HeapWord* r_bot =
+        _g1h->region_at(_coarse_cur_region_index)->bottom();
+      _cur_region_card_offset = _bosa->index_for(r_bot);
+    } else {
+      return false;
+    }
+  }
+  // If we didn't return false above, then we can yield a card.
+  card_index = _cur_region_card_offset + _coarse_cur_region_cur_card;
+  return true;
+}
+
+void HeapRegionRemSetIterator::fine_find_next_non_null_prt() {
+  // Otherwise, find the next bucket list in the array.
+  _fine_array_index++;
+  while (_fine_array_index < (int) OtherRegionsTable::_max_fine_entries) {
+    _fine_cur_prt = _fine_grain_regions[_fine_array_index];
+    if (_fine_cur_prt != NULL) return;
+    else _fine_array_index++;
+  }
+  assert(_fine_cur_prt == NULL, "Loop post");
+}
+
+bool HeapRegionRemSetIterator::fine_has_next(size_t& card_index) {
+  if (fine_has_next()) {
+    _cur_region_cur_card =
+      _fine_cur_prt->_bm.get_next_one_offset(_cur_region_cur_card + 1);
+  }
+  while (!fine_has_next()) {
+    if (_cur_region_cur_card == PosParPRT::CardsPerRegion) {
+      _cur_region_cur_card = 0;
+      _fine_cur_prt = _fine_cur_prt->next();
+    }
+    if (_fine_cur_prt == NULL) {
+      fine_find_next_non_null_prt();
+      if (_fine_cur_prt == NULL) return false;
+    }
+    assert(_fine_cur_prt != NULL && _cur_region_cur_card == 0,
+           "inv.");
+    HeapWord* r_bot =
+      _fine_cur_prt->hr()->bottom();
+    _cur_region_card_offset = _bosa->index_for(r_bot);
+    _cur_region_cur_card = _fine_cur_prt->_bm.get_next_one_offset(0);
+  }
+  assert(fine_has_next(), "Or else we exited the loop via the return.");
+  card_index = _cur_region_card_offset + _cur_region_cur_card;
+  return true;
+}
+
+bool HeapRegionRemSetIterator::fine_has_next() {
+  return
+    _fine_cur_prt != NULL &&
+    _cur_region_cur_card < PosParPRT::CardsPerRegion;
+}
+
+bool HeapRegionRemSetIterator::has_next(size_t& card_index) {
+  switch (_is) {
+  case Sparse:
+    if (_sparse_iter.has_next(card_index)) {
+      _n_yielded_sparse++;
+      return true;
+    }
+    // Otherwise, deliberate fall-through
+    _is = Fine;
+  case Fine:
+    if (fine_has_next(card_index)) {
+      _n_yielded_fine++;
+      return true;
+    }
+    // Otherwise, deliberate fall-through
+    _is = Coarse;
+  case Coarse:
+    if (coarse_has_next(card_index)) {
+      _n_yielded_coarse++;
+      return true;
+    }
+    // Otherwise...
+    break;
+  }
+  assert(ParallelGCThreads > 1 ||
+         n_yielded() == _hrrs->occupied(),
+         "Should have yielded all the cards in the rem set "
+         "(in the non-par case).");
+  return false;
+}
+
+
+
+oop**        HeapRegionRemSet::_recorded_oops = NULL;
+HeapWord**   HeapRegionRemSet::_recorded_cards = NULL;
+HeapRegion** HeapRegionRemSet::_recorded_regions = NULL;
+int          HeapRegionRemSet::_n_recorded = 0;
+
+HeapRegionRemSet::Event* HeapRegionRemSet::_recorded_events = NULL;
+int*         HeapRegionRemSet::_recorded_event_index = NULL;
+int          HeapRegionRemSet::_n_recorded_events = 0;
+
+void HeapRegionRemSet::record(HeapRegion* hr, oop* f) {
+  if (_recorded_oops == NULL) {
+    assert(_n_recorded == 0
+           && _recorded_cards == NULL
+           && _recorded_regions == NULL,
+           "Inv");
+    _recorded_oops = NEW_C_HEAP_ARRAY(oop*, MaxRecorded);
+    _recorded_cards = NEW_C_HEAP_ARRAY(HeapWord*, MaxRecorded);
+    _recorded_regions = NEW_C_HEAP_ARRAY(HeapRegion*, MaxRecorded);
+  }
+  if (_n_recorded == MaxRecorded) {
+    gclog_or_tty->print_cr("Filled up 'recorded' (%d).", MaxRecorded);
+  } else {
+    _recorded_cards[_n_recorded] =
+      (HeapWord*)align_size_down(uintptr_t(f),
+                                 CardTableModRefBS::card_size);
+    _recorded_oops[_n_recorded] = f;
+    _recorded_regions[_n_recorded] = hr;
+    _n_recorded++;
+  }
+}
+
+void HeapRegionRemSet::record_event(Event evnt) {
+  if (!G1RecordHRRSEvents) return;
+
+  if (_recorded_events == NULL) {
+    assert(_n_recorded_events == 0
+           && _recorded_event_index == NULL,
+           "Inv");
+    _recorded_events = NEW_C_HEAP_ARRAY(Event, MaxRecordedEvents);
+    _recorded_event_index = NEW_C_HEAP_ARRAY(int, MaxRecordedEvents);
+  }
+  if (_n_recorded_events == MaxRecordedEvents) {
+    gclog_or_tty->print_cr("Filled up 'recorded_events' (%d).", MaxRecordedEvents);
+  } else {
+    _recorded_events[_n_recorded_events] = evnt;
+    _recorded_event_index[_n_recorded_events] = _n_recorded;
+    _n_recorded_events++;
+  }
+}
+
+void HeapRegionRemSet::print_event(outputStream* str, Event evnt) {
+  switch (evnt) {
+  case Event_EvacStart:
+    str->print("Evac Start");
+    break;
+  case Event_EvacEnd:
+    str->print("Evac End");
+    break;
+  case Event_RSUpdateEnd:
+    str->print("RS Update End");
+    break;
+  }
+}
+
+void HeapRegionRemSet::print_recorded() {
+  int cur_evnt = 0;
+  Event cur_evnt_kind;
+  int cur_evnt_ind = 0;
+  if (_n_recorded_events > 0) {
+    cur_evnt_kind = _recorded_events[cur_evnt];
+    cur_evnt_ind = _recorded_event_index[cur_evnt];
+  }
+
+  for (int i = 0; i < _n_recorded; i++) {
+    while (cur_evnt < _n_recorded_events && i == cur_evnt_ind) {
+      gclog_or_tty->print("Event: ");
+      print_event(gclog_or_tty, cur_evnt_kind);
+      gclog_or_tty->print_cr("");
+      cur_evnt++;
+      if (cur_evnt < MaxRecordedEvents) {
+        cur_evnt_kind = _recorded_events[cur_evnt];
+        cur_evnt_ind = _recorded_event_index[cur_evnt];
+      }
+    }
+    gclog_or_tty->print("Added card " PTR_FORMAT " to region [" PTR_FORMAT "...]"
+                        " for ref " PTR_FORMAT ".\n",
+                        _recorded_cards[i], _recorded_regions[i]->bottom(),
+                        _recorded_oops[i]);
+  }
+}
+
+#ifndef PRODUCT
+void HeapRegionRemSet::test() {
+  os::sleep(Thread::current(), (jlong)5000, false);
+  G1CollectedHeap* g1h = G1CollectedHeap::heap();
+
+  // Run with "-XX:G1LogRSRegionEntries=2", so that 1 and 5 end up in same
+  // hash bucket.
+  HeapRegion* hr0 = g1h->region_at(0);
+  HeapRegion* hr1 = g1h->region_at(1);
+  HeapRegion* hr2 = g1h->region_at(5);
+  HeapRegion* hr3 = g1h->region_at(6);
+  HeapRegion* hr4 = g1h->region_at(7);
+  HeapRegion* hr5 = g1h->region_at(8);
+
+  HeapWord* hr1_start = hr1->bottom();
+  HeapWord* hr1_mid = hr1_start + HeapRegion::GrainWords/2;
+  HeapWord* hr1_last = hr1->end() - 1;
+
+  HeapWord* hr2_start = hr2->bottom();
+  HeapWord* hr2_mid = hr2_start + HeapRegion::GrainWords/2;
+  HeapWord* hr2_last = hr2->end() - 1;
+
+  HeapWord* hr3_start = hr3->bottom();
+  HeapWord* hr3_mid = hr3_start + HeapRegion::GrainWords/2;
+  HeapWord* hr3_last = hr3->end() - 1;
+
+  HeapRegionRemSet* hrrs = hr0->rem_set();
+
+  // Make three references from region 0x101...
+  hrrs->add_reference((oop*)hr1_start);
+  hrrs->add_reference((oop*)hr1_mid);
+  hrrs->add_reference((oop*)hr1_last);
+
+  hrrs->add_reference((oop*)hr2_start);
+  hrrs->add_reference((oop*)hr2_mid);
+  hrrs->add_reference((oop*)hr2_last);
+
+  hrrs->add_reference((oop*)hr3_start);
+  hrrs->add_reference((oop*)hr3_mid);
+  hrrs->add_reference((oop*)hr3_last);
+
+  // Now cause a coarsening.
+  hrrs->add_reference((oop*)hr4->bottom());
+  hrrs->add_reference((oop*)hr5->bottom());
+
+  // Now, does iteration yield these three?
+  HeapRegionRemSetIterator iter;
+  hrrs->init_iterator(&iter);
+  size_t sum = 0;
+  size_t card_index;
+  while (iter.has_next(card_index)) {
+    HeapWord* card_start =
+      G1CollectedHeap::heap()->bot_shared()->address_for_index(card_index);
+    gclog_or_tty->print_cr("  Card " PTR_FORMAT ".", card_start);
+    sum++;
+  }
+  guarantee(sum == 11 - 3 + 2048, "Failure");
+  guarantee(sum == hrrs->occupied(), "Failure");
+}
+#endif