diff -r 4ebc2e2fb97c -r 71c04702a3d5 src/hotspot/share/gc/g1/heapRegionRemSet.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/share/gc/g1/heapRegionRemSet.cpp	Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,973 @@
+/*
+ * Copyright (c) 2001, 2017, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+#include "precompiled.hpp"
+#include "gc/g1/concurrentG1Refine.hpp"
+#include "gc/g1/g1BlockOffsetTable.inline.hpp"
+#include "gc/g1/g1CollectedHeap.inline.hpp"
+#include "gc/g1/g1CardLiveData.inline.hpp"
+#include "gc/g1/heapRegionManager.inline.hpp"
+#include "gc/g1/heapRegionRemSet.hpp"
+#include "gc/shared/space.inline.hpp"
+#include "memory/allocation.hpp"
+#include "memory/padded.inline.hpp"
+#include "oops/oop.inline.hpp"
+#include "runtime/atomic.hpp"
+#include "utilities/bitMap.inline.hpp"
+#include "utilities/debug.hpp"
+#include "utilities/formatBuffer.hpp"
+#include "utilities/globalDefinitions.hpp"
+#include "utilities/growableArray.hpp"
+
+class PerRegionTable: public CHeapObj<mtGC> {
+  friend class OtherRegionsTable;
+  friend class HeapRegionRemSetIterator;
+
+  HeapRegion*     _hr;
+  CHeapBitMap     _bm;
+  jint            _occupied;
+
+  // next pointer for free/allocated 'all' list
+  PerRegionTable* _next;
+
+  // prev pointer for the allocated 'all' list
+  PerRegionTable* _prev;
+
+  // next pointer in collision list
+  PerRegionTable * _collision_list_next;
+
+  // Global free list of PRTs
+  static PerRegionTable* volatile _free_list;
+
+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),
+    _occupied(0),
+    _bm(HeapRegion::CardsPerRegion, mtGC),
+    _collision_list_next(NULL), _next(NULL), _prev(NULL)
+  {}
+
+  void add_card_work(CardIdx_t from_card, bool par) {
+    if (!_bm.at(from_card)) {
+      if (par) {
+        if (_bm.par_at_put(from_card, 1)) {
+          Atomic::inc(&_occupied);
+        }
+      } else {
+        _bm.at_put(from_card, 1);
+        _occupied++;
+      }
+    }
+  }
+
+  void add_reference_work(OopOrNarrowOopStar from, bool par) {
+    // Must make this robust in case "from" is not in "_hr", because of
+    // concurrency.
+
+    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 the table used to belong to a continues humongous region and is
+    // now reused for the corresponding start humongous region, we need to
+    // make sure that we detect this. Thus, we call is_in_reserved_raw()
+    // instead of just is_in_reserved() here.
+    if (loc_hr->is_in_reserved(from)) {
+      size_t hw_offset = pointer_delta((HeapWord*)from, loc_hr->bottom());
+      CardIdx_t from_card = (CardIdx_t)
+          hw_offset >> (CardTableModRefBS::card_shift - LogHeapWordSize);
+
+      assert((size_t)from_card < HeapRegion::CardsPerRegion,
+             "Must be in range.");
+      add_card_work(from_card, par);
+    }
+  }
+
+public:
+
+  HeapRegion* hr() const {
+    return (HeapRegion*) OrderAccess::load_ptr_acquire(&_hr);
+  }
+
+  jint occupied() const {
+    // Overkill, but if we ever need it...
+    // guarantee(_occupied == _bm.count_one_bits(), "Check");
+    return _occupied;
+  }
+
+  void init(HeapRegion* hr, bool clear_links_to_all_list) {
+    if (clear_links_to_all_list) {
+      set_next(NULL);
+      set_prev(NULL);
+    }
+    _collision_list_next = NULL;
+    _occupied = 0;
+    _bm.clear();
+    // Make sure that the bitmap clearing above has been finished before publishing
+    // this PRT to concurrent threads.
+    OrderAccess::release_store_ptr(&_hr, hr);
+  }
+
+  void add_reference(OopOrNarrowOopStar from) {
+    add_reference_work(from, /*parallel*/ true);
+  }
+
+  void seq_add_reference(OopOrNarrowOopStar from) {
+    add_reference_work(from, /*parallel*/ false);
+  }
+
+  void scrub(G1CardLiveData* live_data) {
+    live_data->remove_nonlive_cards(hr()->hrm_index(), &_bm);
+    recount_occupied();
+  }
+
+  void add_card(CardIdx_t from_card_index) {
+    add_card_work(from_card_index, /*parallel*/ true);
+  }
+
+  void seq_add_card(CardIdx_t 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(PerRegionTable) + _bm.size_in_words() * HeapWordSize;
+  }
+
+  // Requires "from" to be in "hr()".
+  bool contains_reference(OopOrNarrowOopStar 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);
+  }
+
+  // Bulk-free the PRTs from prt to last, assumes that they are
+  // linked together using their _next field.
+  static void bulk_free(PerRegionTable* prt, PerRegionTable* last) {
+    while (true) {
+      PerRegionTable* fl = _free_list;
+      last->set_next(fl);
+      PerRegionTable* res = (PerRegionTable*) Atomic::cmpxchg_ptr(prt, &_free_list, fl);
+      if (res == fl) {
+        return;
+      }
+    }
+    ShouldNotReachHere();
+  }
+
+  static void free(PerRegionTable* prt) {
+    bulk_free(prt, prt);
+  }
+
+  // Returns an initialized PerRegionTable instance.
+  static PerRegionTable* alloc(HeapRegion* hr) {
+    PerRegionTable* fl = _free_list;
+    while (fl != NULL) {
+      PerRegionTable* nxt = fl->next();
+      PerRegionTable* res =
+        (PerRegionTable*)
+        Atomic::cmpxchg_ptr(nxt, &_free_list, fl);
+      if (res == fl) {
+        fl->init(hr, true);
+        return fl;
+      } else {
+        fl = _free_list;
+      }
+    }
+    assert(fl == NULL, "Loop condition.");
+    return new PerRegionTable(hr);
+  }
+
+  PerRegionTable* next() const { return _next; }
+  void set_next(PerRegionTable* next) { _next = next; }
+  PerRegionTable* prev() const { return _prev; }
+  void set_prev(PerRegionTable* prev) { _prev = prev; }
+
+  // Accessor and Modification routines for the pointer for the
+  // singly linked collision list that links the PRTs within the
+  // OtherRegionsTable::_fine_grain_regions hash table.
+  //
+  // It might be useful to also make the collision list doubly linked
+  // to avoid iteration over the collisions list during scrubbing/deletion.
+  // OTOH there might not be many collisions.
+
+  PerRegionTable* collision_list_next() const {
+    return _collision_list_next;
+  }
+
+  void set_collision_list_next(PerRegionTable* next) {
+    _collision_list_next = next;
+  }
+
+  PerRegionTable** collision_list_next_addr() {
+    return &_collision_list_next;
+  }
+
+  static size_t fl_mem_size() {
+    PerRegionTable* cur = _free_list;
+    size_t res = 0;
+    while (cur != NULL) {
+      res += cur->mem_size();
+      cur = cur->next();
+    }
+    return res;
+  }
+
+  static void test_fl_mem_size();
+};
+
+PerRegionTable* volatile PerRegionTable::_free_list = NULL;
+
+size_t OtherRegionsTable::_max_fine_entries = 0;
+size_t OtherRegionsTable::_mod_max_fine_entries_mask = 0;
+size_t OtherRegionsTable::_fine_eviction_stride = 0;
+size_t OtherRegionsTable::_fine_eviction_sample_size = 0;
+
+OtherRegionsTable::OtherRegionsTable(HeapRegion* hr, Mutex* m) :
+  _g1h(G1CollectedHeap::heap()),
+  _hr(hr), _m(m),
+  _coarse_map(G1CollectedHeap::heap()->max_regions(), mtGC),
+  _fine_grain_regions(NULL),
+  _first_all_fine_prts(NULL), _last_all_fine_prts(NULL),
+  _n_fine_entries(0), _n_coarse_entries(0),
+  _fine_eviction_start(0),
+  _sparse_table(hr)
+{
+  typedef PerRegionTable* PerRegionTablePtr;
+
+  if (_max_fine_entries == 0) {
+    assert(_mod_max_fine_entries_mask == 0, "Both or none.");
+    size_t max_entries_log = (size_t)log2_long((jlong)G1RSetRegionEntries);
+    _max_fine_entries = (size_t)1 << max_entries_log;
+    _mod_max_fine_entries_mask = _max_fine_entries - 1;
+
+    assert(_fine_eviction_sample_size == 0
+           && _fine_eviction_stride == 0, "All init at same time.");
+    _fine_eviction_sample_size = MAX2((size_t)4, max_entries_log);
+    _fine_eviction_stride = _max_fine_entries / _fine_eviction_sample_size;
+  }
+
+  _fine_grain_regions = NEW_C_HEAP_ARRAY3(PerRegionTablePtr, _max_fine_entries,
+                        mtGC, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
+
+  if (_fine_grain_regions == NULL) {
+    vm_exit_out_of_memory(sizeof(void*)*_max_fine_entries, OOM_MALLOC_ERROR,
+                          "Failed to allocate _fine_grain_entries.");
+  }
+
+  for (size_t i = 0; i < _max_fine_entries; i++) {
+    _fine_grain_regions[i] = NULL;
+  }
+}
+
+void OtherRegionsTable::link_to_all(PerRegionTable* prt) {
+  // We always append to the beginning of the list for convenience;
+  // the order of entries in this list does not matter.
+  if (_first_all_fine_prts != NULL) {
+    assert(_first_all_fine_prts->prev() == NULL, "invariant");
+    _first_all_fine_prts->set_prev(prt);
+    prt->set_next(_first_all_fine_prts);
+  } else {
+    // this is the first element we insert. Adjust the "last" pointer
+    _last_all_fine_prts = prt;
+    assert(prt->next() == NULL, "just checking");
+  }
+  // the new element is always the first element without a predecessor
+  prt->set_prev(NULL);
+  _first_all_fine_prts = prt;
+
+  assert(prt->prev() == NULL, "just checking");
+  assert(_first_all_fine_prts == prt, "just checking");
+  assert((_first_all_fine_prts == NULL && _last_all_fine_prts == NULL) ||
+         (_first_all_fine_prts != NULL && _last_all_fine_prts != NULL),
+         "just checking");
+  assert(_last_all_fine_prts == NULL || _last_all_fine_prts->next() == NULL,
+         "just checking");
+  assert(_first_all_fine_prts == NULL || _first_all_fine_prts->prev() == NULL,
+         "just checking");
+}
+
+void OtherRegionsTable::unlink_from_all(PerRegionTable* prt) {
+  if (prt->prev() != NULL) {
+    assert(_first_all_fine_prts != prt, "just checking");
+    prt->prev()->set_next(prt->next());
+    // removing the last element in the list?
+    if (_last_all_fine_prts == prt) {
+      _last_all_fine_prts = prt->prev();
+    }
+  } else {
+    assert(_first_all_fine_prts == prt, "just checking");
+    _first_all_fine_prts = prt->next();
+    // list is empty now?
+    if (_first_all_fine_prts == NULL) {
+      _last_all_fine_prts = NULL;
+    }
+  }
+
+  if (prt->next() != NULL) {
+    prt->next()->set_prev(prt->prev());
+  }
+
+  prt->set_next(NULL);
+  prt->set_prev(NULL);
+
+  assert((_first_all_fine_prts == NULL && _last_all_fine_prts == NULL) ||
+         (_first_all_fine_prts != NULL && _last_all_fine_prts != NULL),
+         "just checking");
+  assert(_last_all_fine_prts == NULL || _last_all_fine_prts->next() == NULL,
+         "just checking");
+  assert(_first_all_fine_prts == NULL || _first_all_fine_prts->prev() == NULL,
+         "just checking");
+}
+
+void OtherRegionsTable::add_reference(OopOrNarrowOopStar from, uint tid) {
+  uint cur_hrm_ind = _hr->hrm_index();
+
+  int from_card = (int)(uintptr_t(from) >> CardTableModRefBS::card_shift);
+
+  if (G1FromCardCache::contains_or_replace(tid, cur_hrm_ind, from_card)) {
+    assert(contains_reference(from), "We just found " PTR_FORMAT " in the FromCardCache", p2i(from));
+    return;
+  }
+
+  // Note that this may be a continued H region.
+  HeapRegion* from_hr = _g1h->heap_region_containing(from);
+  RegionIdx_t from_hrm_ind = (RegionIdx_t) from_hr->hrm_index();
+
+  // If the region is already coarsened, return.
+  if (_coarse_map.at(from_hrm_ind)) {
+    assert(contains_reference(from), "We just found " PTR_FORMAT " in the Coarse table", p2i(from));
+    return;
+  }
+
+  // Otherwise find a per-region table to add it to.
+  size_t ind = from_hrm_ind & _mod_max_fine_entries_mask;
+  PerRegionTable* 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;
+      CardIdx_t card_index = from_card - from_hr_bot_card_index;
+      assert((size_t)card_index < HeapRegion::CardsPerRegion,
+             "Must be in range.");
+      if (G1HRRSUseSparseTable &&
+          _sparse_table.add_card(from_hrm_ind, card_index)) {
+        assert(contains_reference_locked(from), "We just added " PTR_FORMAT " to the Sparse table", p2i(from));
+        return;
+      }
+
+      if (_n_fine_entries == _max_fine_entries) {
+        prt = delete_region_table();
+        // There is no need to clear the links to the 'all' list here:
+        // prt will be reused immediately, i.e. remain in the 'all' list.
+        prt->init(from_hr, false /* clear_links_to_all_list */);
+      } else {
+        prt = PerRegionTable::alloc(from_hr);
+        link_to_all(prt);
+      }
+
+      PerRegionTable* first_prt = _fine_grain_regions[ind];
+      prt->set_collision_list_next(first_prt);
+      // The assignment into _fine_grain_regions allows the prt to
+      // start being used concurrently. In addition to
+      // collision_list_next which must be visible (else concurrent
+      // parsing of the list, if any, may fail to see other entries),
+      // the content of the prt must be visible (else for instance
+      // some mark bits may not yet seem cleared or a 'later' update
+      // performed by a concurrent thread could be undone when the
+      // zeroing becomes visible). This requires store ordering.
+      OrderAccess::release_store_ptr((volatile PerRegionTable*)&_fine_grain_regions[ind], prt);
+      _n_fine_entries++;
+
+      if (G1HRRSUseSparseTable) {
+        // Transfer from sparse to fine-grain.
+        SparsePRTEntry *sprt_entry = _sparse_table.get_entry(from_hrm_ind);
+        assert(sprt_entry != NULL, "There should have been an entry");
+        for (int i = 0; i < sprt_entry->num_valid_cards(); i++) {
+          CardIdx_t c = sprt_entry->card(i);
+          prt->add_card(c);
+        }
+        // Now we can delete the sparse entry.
+        bool res = _sparse_table.delete_entry(from_hrm_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);
+  assert(contains_reference(from), "We just added " PTR_FORMAT " to the PRT", p2i(from));
+}
+
+PerRegionTable*
+OtherRegionsTable::find_region_table(size_t ind, HeapRegion* hr) const {
+  assert(ind < _max_fine_entries, "Preconditions.");
+  PerRegionTable* prt = _fine_grain_regions[ind];
+  while (prt != NULL && prt->hr() != hr) {
+    prt = prt->collision_list_next();
+  }
+  // Loop postcondition is the method postcondition.
+  return prt;
+}
+
+jint OtherRegionsTable::_n_coarsenings = 0;
+
+PerRegionTable* OtherRegionsTable::delete_region_table() {
+  assert(_m->owned_by_self(), "Precondition");
+  assert(_n_fine_entries == _max_fine_entries, "Precondition");
+  PerRegionTable* max = NULL;
+  jint max_occ = 0;
+  PerRegionTable** max_prev = NULL;
+  size_t max_ind;
+
+  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.");
+    }
+    PerRegionTable** prev = &_fine_grain_regions[ii];
+    PerRegionTable* 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->collision_list_next_addr();
+      cur = cur->collision_list_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;
+  }
+
+  guarantee(max != NULL, "Since _n_fine_entries > 0");
+  guarantee(max_prev != NULL, "Since max != NULL.");
+
+  // Set the corresponding coarse bit.
+  size_t max_hrm_index = (size_t) max->hr()->hrm_index();
+  if (!_coarse_map.at(max_hrm_index)) {
+    _coarse_map.at_put(max_hrm_index, true);
+    _n_coarse_entries++;
+  }
+
+  // Unsplice.
+  *max_prev = max->collision_list_next();
+  Atomic::inc(&_n_coarsenings);
+  _n_fine_entries--;
+  return max;
+}
+
+void OtherRegionsTable::scrub(G1CardLiveData* live_data) {
+  // First eliminated garbage regions from the coarse map.
+  log_develop_trace(gc, remset, scrub)("Scrubbing region %u:", _hr->hrm_index());
+
+  log_develop_trace(gc, remset, scrub)("   Coarse map: before = " SIZE_FORMAT "...", _n_coarse_entries);
+  if (_n_coarse_entries > 0) {
+    live_data->remove_nonlive_regions(&_coarse_map);
+    _n_coarse_entries = _coarse_map.count_one_bits();
+  }
+  log_develop_trace(gc, remset, scrub)("   after = " SIZE_FORMAT ".", _n_coarse_entries);
+
+  // Now do the fine-grained maps.
+  for (size_t i = 0; i < _max_fine_entries; i++) {
+    PerRegionTable* cur = _fine_grain_regions[i];
+    PerRegionTable** prev = &_fine_grain_regions[i];
+    while (cur != NULL) {
+      PerRegionTable* nxt = cur->collision_list_next();
+      // If the entire region is dead, eliminate.
+      log_develop_trace(gc, remset, scrub)("     For other region %u:", cur->hr()->hrm_index());
+      if (!live_data->is_region_live(cur->hr()->hrm_index())) {
+        *prev = nxt;
+        cur->set_collision_list_next(NULL);
+        _n_fine_entries--;
+        log_develop_trace(gc, remset, scrub)("          deleted via region map.");
+        unlink_from_all(cur);
+        PerRegionTable::free(cur);
+      } else {
+        // Do fine-grain elimination.
+        log_develop_trace(gc, remset, scrub)("          occ: before = %4d.", cur->occupied());
+        cur->scrub(live_data);
+        log_develop_trace(gc, remset, scrub)("          after = %4d.", cur->occupied());
+        // Did that empty the table completely?
+        if (cur->occupied() == 0) {
+          *prev = nxt;
+          cur->set_collision_list_next(NULL);
+          _n_fine_entries--;
+          unlink_from_all(cur);
+          PerRegionTable::free(cur);
+        } else {
+          prev = cur->collision_list_next_addr();
+        }
+      }
+      cur = nxt;
+    }
+  }
+  // Since we may have deleted a from_card_cache entry from the RS, clear
+  // the FCC.
+  clear_fcc();
+}
+
+bool OtherRegionsTable::occupancy_less_or_equal_than(size_t limit) const {
+  if (limit <= (size_t)G1RSetSparseRegionEntries) {
+    return occ_coarse() == 0 && _first_all_fine_prts == NULL && occ_sparse() <= limit;
+  } else {
+    // Current uses of this method may only use values less than G1RSetSparseRegionEntries
+    // for the limit. The solution, comparing against occupied() would be too slow
+    // at this time.
+    Unimplemented();
+    return false;
+  }
+}
+
+bool OtherRegionsTable::is_empty() const {
+  return occ_sparse() == 0 && occ_coarse() == 0 && _first_all_fine_prts == NULL;
+}
+
+size_t OtherRegionsTable::occupied() const {
+  size_t sum = occ_fine();
+  sum += occ_sparse();
+  sum += occ_coarse();
+  return sum;
+}
+
+size_t OtherRegionsTable::occ_fine() const {
+  size_t sum = 0;
+
+  size_t num = 0;
+  PerRegionTable * cur = _first_all_fine_prts;
+  while (cur != NULL) {
+    sum += cur->occupied();
+    cur = cur->next();
+    num++;
+  }
+  guarantee(num == _n_fine_entries, "just checking");
+  return sum;
+}
+
+size_t OtherRegionsTable::occ_coarse() const {
+  return (_n_coarse_entries * HeapRegion::CardsPerRegion);
+}
+
+size_t OtherRegionsTable::occ_sparse() const {
+  return _sparse_table.occupied();
+}
+
+size_t OtherRegionsTable::mem_size() const {
+  size_t sum = 0;
+  // all PRTs are of the same size so it is sufficient to query only one of them.
+  if (_first_all_fine_prts != NULL) {
+    assert(_last_all_fine_prts != NULL &&
+      _first_all_fine_prts->mem_size() == _last_all_fine_prts->mem_size(), "check that mem_size() is constant");
+    sum += _first_all_fine_prts->mem_size() * _n_fine_entries;
+  }
+  sum += (sizeof(PerRegionTable*) * _max_fine_entries);
+  sum += (_coarse_map.size_in_words() * HeapWordSize);
+  sum += (_sparse_table.mem_size());
+  sum += sizeof(OtherRegionsTable) - sizeof(_sparse_table); // Avoid double counting above.
+  return sum;
+}
+
+size_t OtherRegionsTable::static_mem_size() {
+  return G1FromCardCache::static_mem_size();
+}
+
+size_t OtherRegionsTable::fl_mem_size() {
+  return PerRegionTable::fl_mem_size();
+}
+
+void OtherRegionsTable::clear_fcc() {
+  G1FromCardCache::clear(_hr->hrm_index());
+}
+
+void OtherRegionsTable::clear() {
+  // if there are no entries, skip this step
+  if (_first_all_fine_prts != NULL) {
+    guarantee(_first_all_fine_prts != NULL && _last_all_fine_prts != NULL, "just checking");
+    PerRegionTable::bulk_free(_first_all_fine_prts, _last_all_fine_prts);
+    memset(_fine_grain_regions, 0, _max_fine_entries * sizeof(_fine_grain_regions[0]));
+  } else {
+    guarantee(_first_all_fine_prts == NULL && _last_all_fine_prts == NULL, "just checking");
+  }
+
+  _first_all_fine_prts = _last_all_fine_prts = NULL;
+  _sparse_table.clear();
+  if (_n_coarse_entries > 0) {
+    _coarse_map.clear();
+  }
+  _n_fine_entries = 0;
+  _n_coarse_entries = 0;
+
+  clear_fcc();
+}
+
+bool OtherRegionsTable::contains_reference(OopOrNarrowOopStar 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(OopOrNarrowOopStar from) const {
+  HeapRegion* hr = _g1h->heap_region_containing(from);
+  RegionIdx_t hr_ind = (RegionIdx_t) hr->hrm_index();
+  // Is this region in the coarse map?
+  if (_coarse_map.at(hr_ind)) return true;
+
+  PerRegionTable* 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");
+    CardIdx_t card_index = from_card - hr_bot_card_index;
+    assert((size_t)card_index < HeapRegion::CardsPerRegion,
+           "Must be in range.");
+    return _sparse_table.contains_card(hr_ind, card_index);
+  }
+}
+
+void
+OtherRegionsTable::do_cleanup_work(HRRSCleanupTask* hrrs_cleanup_task) {
+  _sparse_table.do_cleanup_work(hrrs_cleanup_task);
+}
+
+HeapRegionRemSet::HeapRegionRemSet(G1BlockOffsetTable* bot,
+                                   HeapRegion* hr)
+  : _bot(bot),
+    _m(Mutex::leaf, FormatBuffer<128>("HeapRegionRemSet lock #%u", hr->hrm_index()), true, Monitor::_safepoint_check_never),
+    _code_roots(),
+    _other_regions(hr, &_m) {
+}
+
+void HeapRegionRemSet::setup_remset_size() {
+  // Setup sparse and fine-grain tables sizes.
+  // table_size = base * (log(region_size / 1M) + 1)
+  const int LOG_M = 20;
+  int region_size_log_mb = MAX2(HeapRegion::LogOfHRGrainBytes - LOG_M, 0);
+  if (FLAG_IS_DEFAULT(G1RSetSparseRegionEntries)) {
+    G1RSetSparseRegionEntries = G1RSetSparseRegionEntriesBase * (region_size_log_mb + 1);
+  }
+  if (FLAG_IS_DEFAULT(G1RSetRegionEntries)) {
+    G1RSetRegionEntries = G1RSetRegionEntriesBase * (region_size_log_mb + 1);
+  }
+  guarantee(G1RSetSparseRegionEntries > 0 && G1RSetRegionEntries > 0 , "Sanity");
+}
+
+void HeapRegionRemSet::cleanup() {
+  SparsePRT::cleanup_all();
+}
+
+void HeapRegionRemSet::clear() {
+  MutexLockerEx x(&_m, Mutex::_no_safepoint_check_flag);
+  clear_locked();
+}
+
+void HeapRegionRemSet::clear_locked() {
+  _code_roots.clear();
+  _other_regions.clear();
+  assert(occupied_locked() == 0, "Should be clear.");
+}
+
+void HeapRegionRemSet::scrub(G1CardLiveData* live_data) {
+  _other_regions.scrub(live_data);
+}
+
+// Code roots support
+//
+// The code root set is protected by two separate locking schemes
+// When at safepoint the per-hrrs lock must be held during modifications
+// except when doing a full gc.
+// When not at safepoint the CodeCache_lock must be held during modifications.
+// When concurrent readers access the contains() function
+// (during the evacuation phase) no removals are allowed.
+
+void HeapRegionRemSet::add_strong_code_root(nmethod* nm) {
+  assert(nm != NULL, "sanity");
+  assert((!CodeCache_lock->owned_by_self() || SafepointSynchronize::is_at_safepoint()),
+          "should call add_strong_code_root_locked instead. CodeCache_lock->owned_by_self(): %s, is_at_safepoint(): %s",
+          BOOL_TO_STR(CodeCache_lock->owned_by_self()), BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()));
+  // Optimistic unlocked contains-check
+  if (!_code_roots.contains(nm)) {
+    MutexLockerEx ml(&_m, Mutex::_no_safepoint_check_flag);
+    add_strong_code_root_locked(nm);
+  }
+}
+
+void HeapRegionRemSet::add_strong_code_root_locked(nmethod* nm) {
+  assert(nm != NULL, "sanity");
+  assert((CodeCache_lock->owned_by_self() ||
+         (SafepointSynchronize::is_at_safepoint() &&
+          (_m.owned_by_self() || Thread::current()->is_VM_thread()))),
+          "not safely locked. CodeCache_lock->owned_by_self(): %s, is_at_safepoint(): %s, _m.owned_by_self(): %s, Thread::current()->is_VM_thread(): %s",
+          BOOL_TO_STR(CodeCache_lock->owned_by_self()), BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()),
+          BOOL_TO_STR(_m.owned_by_self()), BOOL_TO_STR(Thread::current()->is_VM_thread()));
+  _code_roots.add(nm);
+}
+
+void HeapRegionRemSet::remove_strong_code_root(nmethod* nm) {
+  assert(nm != NULL, "sanity");
+  assert_locked_or_safepoint(CodeCache_lock);
+
+  MutexLockerEx ml(CodeCache_lock->owned_by_self() ? NULL : &_m, Mutex::_no_safepoint_check_flag);
+  _code_roots.remove(nm);
+
+  // Check that there were no duplicates
+  guarantee(!_code_roots.contains(nm), "duplicate entry found");
+}
+
+void HeapRegionRemSet::strong_code_roots_do(CodeBlobClosure* blk) const {
+  _code_roots.nmethods_do(blk);
+}
+
+void HeapRegionRemSet::clean_strong_code_roots(HeapRegion* hr) {
+  _code_roots.clean(hr);
+}
+
+size_t HeapRegionRemSet::strong_code_roots_mem_size() {
+  return _code_roots.mem_size();
+}
+
+HeapRegionRemSetIterator:: HeapRegionRemSetIterator(HeapRegionRemSet* hrrs) :
+  _hrrs(hrrs),
+  _g1h(G1CollectedHeap::heap()),
+  _coarse_map(&hrrs->_other_regions._coarse_map),
+  _bot(hrrs->_bot),
+  _is(Sparse),
+  // Set these values so that we increment to the first region.
+  _coarse_cur_region_index(-1),
+  _coarse_cur_region_cur_card(HeapRegion::CardsPerRegion-1),
+  _cur_card_in_prt(HeapRegion::CardsPerRegion),
+  _fine_cur_prt(NULL),
+  _n_yielded_coarse(0),
+  _n_yielded_fine(0),
+  _n_yielded_sparse(0),
+  _sparse_iter(&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 == HeapRegion::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((uint) _coarse_cur_region_index)->bottom();
+      _cur_region_card_offset = _bot->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;
+}
+
+bool HeapRegionRemSetIterator::fine_has_next(size_t& card_index) {
+  if (fine_has_next()) {
+    _cur_card_in_prt =
+      _fine_cur_prt->_bm.get_next_one_offset(_cur_card_in_prt + 1);
+  }
+  if (_cur_card_in_prt == HeapRegion::CardsPerRegion) {
+    // _fine_cur_prt may still be NULL in case if there are not PRTs at all for
+    // the remembered set.
+    if (_fine_cur_prt == NULL || _fine_cur_prt->next() == NULL) {
+      return false;
+    }
+    PerRegionTable* next_prt = _fine_cur_prt->next();
+    switch_to_prt(next_prt);
+    _cur_card_in_prt = _fine_cur_prt->_bm.get_next_one_offset(_cur_card_in_prt + 1);
+  }
+
+  card_index = _cur_region_card_offset + _cur_card_in_prt;
+  guarantee(_cur_card_in_prt < HeapRegion::CardsPerRegion,
+            "Card index " SIZE_FORMAT " must be within the region", _cur_card_in_prt);
+  return true;
+}
+
+bool HeapRegionRemSetIterator::fine_has_next() {
+  return _cur_card_in_prt != HeapRegion::CardsPerRegion;
+}
+
+void HeapRegionRemSetIterator::switch_to_prt(PerRegionTable* prt) {
+  assert(prt != NULL, "Cannot switch to NULL prt");
+  _fine_cur_prt = prt;
+
+  HeapWord* r_bot = _fine_cur_prt->hr()->bottom();
+  _cur_region_card_offset = _bot->index_for(r_bot);
+
+  // The bitmap scan for the PRT always scans from _cur_region_cur_card + 1.
+  // To avoid special-casing this start case, and not miss the first bitmap
+  // entry, initialize _cur_region_cur_card with -1 instead of 0.
+  _cur_card_in_prt = (size_t)-1;
+}
+
+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;
+    PerRegionTable* initial_fine_prt = _hrrs->_other_regions._first_all_fine_prts;
+    if (initial_fine_prt != NULL) {
+      switch_to_prt(_hrrs->_other_regions._first_all_fine_prts);
+    }
+  }
+  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;
+  }
+  return false;
+}
+
+void HeapRegionRemSet::reset_for_cleanup_tasks() {
+  SparsePRT::reset_for_cleanup_tasks();
+}
+
+void HeapRegionRemSet::do_cleanup_work(HRRSCleanupTask* hrrs_cleanup_task) {
+  _other_regions.do_cleanup_work(hrrs_cleanup_task);
+}
+
+void
+HeapRegionRemSet::finish_cleanup_task(HRRSCleanupTask* hrrs_cleanup_task) {
+  SparsePRT::finish_cleanup_task(hrrs_cleanup_task);
+}
+
+#ifndef PRODUCT
+void HeapRegionRemSet::test() {
+  os::sleep(Thread::current(), (jlong)5000, false);
+  G1CollectedHeap* g1h = G1CollectedHeap::heap();
+
+  // Run with "-XX:G1LogRSetRegionEntries=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((OopOrNarrowOopStar)hr1_start);
+  hrrs->add_reference((OopOrNarrowOopStar)hr1_mid);
+  hrrs->add_reference((OopOrNarrowOopStar)hr1_last);
+
+  hrrs->add_reference((OopOrNarrowOopStar)hr2_start);
+  hrrs->add_reference((OopOrNarrowOopStar)hr2_mid);
+  hrrs->add_reference((OopOrNarrowOopStar)hr2_last);
+
+  hrrs->add_reference((OopOrNarrowOopStar)hr3_start);
+  hrrs->add_reference((OopOrNarrowOopStar)hr3_mid);
+  hrrs->add_reference((OopOrNarrowOopStar)hr3_last);
+
+  // Now cause a coarsening.
+  hrrs->add_reference((OopOrNarrowOopStar)hr4->bottom());
+  hrrs->add_reference((OopOrNarrowOopStar)hr5->bottom());
+
+  // Now, does iteration yield these three?
+  HeapRegionRemSetIterator iter(hrrs);
+  size_t sum = 0;
+  size_t card_index;
+  while (iter.has_next(card_index)) {
+    HeapWord* card_start =
+      G1CollectedHeap::heap()->bot()->address_for_index(card_index);
+    tty->print_cr("  Card " PTR_FORMAT ".", p2i(card_start));
+    sum++;
+  }
+  guarantee(sum == 11 - 3 + 2048, "Failure");
+  guarantee(sum == hrrs->occupied(), "Failure");
+}
+#endif