1 /*

     2  * Copyright (c) 2001, 2018, 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 #ifndef SHARE_VM_GC_G1_G1CARDTABLE_HPP

    26 #define SHARE_VM_GC_G1_G1CARDTABLE_HPP

    27 

    28 #include "gc/g1/g1RegionToSpaceMapper.hpp"

    29 #include "gc/shared/cardTable.hpp"

    30 #include "oops/oopsHierarchy.hpp"

    31 #include "utilities/macros.hpp"

    32 

    33 class G1CardTable;

    34 class G1RegionToSpaceMapper;

    35 

    36 class G1CardTableChangedListener : public G1MappingChangedListener {

    37  private:

    38   G1CardTable* _card_table;

    39  public:

    40   G1CardTableChangedListener() : _card_table(NULL) { }

    41 

    42   void set_card_table(G1CardTable* card_table) { _card_table = card_table; }

    43 

    44   virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled);

    45 };

    46 

    47 class G1CardTable: public CardTable {

    48   friend class VMStructs;

    49   friend class G1CardTableChangedListener;

    50 

    51   G1CardTableChangedListener _listener;

    52 

    53   enum G1CardValues {

    54     g1_young_gen = CT_MR_BS_last_reserved << 1

    55   };

    56 

    57 public:

    58   G1CardTable(MemRegion whole_heap): CardTable(whole_heap, /* scanned concurrently */ true), _listener() {

    59     _listener.set_card_table(this);

    60   }

    61   bool is_card_dirty(size_t card_index) {

    62     return _byte_map[card_index] == dirty_card_val();

    63   }

    64 

    65   static jbyte g1_young_card_val() { return g1_young_gen; }

    66 

    67 /*

    68    Claimed and deferred bits are used together in G1 during the evacuation

    69    pause. These bits can have the following state transitions:

    70    1. The claimed bit can be put over any other card state. Except that

    71       the "dirty -> dirty and claimed" transition is checked for in

    72       G1 code and is not used.

    73    2. Deferred bit can be set only if the previous state of the card

    74       was either clean or claimed. mark_card_deferred() is wait-free.

    75       We do not care if the operation is be successful because if

    76       it does not it will only result in duplicate entry in the update

    77       buffer because of the "cache-miss". So it's not worth spinning.

    78  */

    79 

    80   bool is_card_claimed(size_t card_index) {

    81     jbyte val = _byte_map[card_index];

    82     return (val & (clean_card_mask_val() | claimed_card_val())) == claimed_card_val();

    83   }

    84 

    85   inline void set_card_claimed(size_t card_index);

    86 

    87   void verify_g1_young_region(MemRegion mr) PRODUCT_RETURN;

    88   void g1_mark_as_young(const MemRegion& mr);

    89 

    90   bool mark_card_deferred(size_t card_index);

    91 

    92   bool is_card_deferred(size_t card_index) {

    93     jbyte val = _byte_map[card_index];

    94     return (val & (clean_card_mask_val() | deferred_card_val())) == deferred_card_val();

    95   }

    96 

    97   static size_t compute_size(size_t mem_region_size_in_words) {

    98     size_t number_of_slots = (mem_region_size_in_words / card_size_in_words);

    99     return ReservedSpace::allocation_align_size_up(number_of_slots);

   100   }

   101 

   102   // Returns how many bytes of the heap a single byte of the Card Table corresponds to.

   103   static size_t heap_map_factor() { return card_size; }

   104 

   105   void initialize() {}

   106   void initialize(G1RegionToSpaceMapper* mapper);

   107 

   108   virtual void resize_covered_region(MemRegion new_region) { ShouldNotReachHere(); }

   109 

   110   virtual bool is_in_young(oop obj) const;

   111 };

   112 

   113 #endif // SHARE_VM_GC_G1_G1CARDTABLE_HPP