1 /*

     2  * Copyright (c) 2015, 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_SHARED_CARDTABLEMODREFBSFORCTRS_HPP

    26 #define SHARE_VM_GC_SHARED_CARDTABLEMODREFBSFORCTRS_HPP

    27 

    28 #include "gc/shared/cardTableModRefBS.hpp"

    29 

    30 class CardTableRS;

    31 class DirtyCardToOopClosure;

    32 class OopsInGenClosure;

    33 

    34 // A specialization for the CardTableRS gen rem set.

    35 class CardTableModRefBSForCTRS: public CardTableModRefBS {

    36   friend class CardTableRS;

    37 

    38 public:

    39   CardTableModRefBSForCTRS(MemRegion whole_heap);

    40   ~CardTableModRefBSForCTRS();

    41 

    42   virtual void initialize();

    43 

    44   void set_CTRS(CardTableRS* rs) { _rs = rs; }

    45 

    46   virtual bool card_mark_must_follow_store() const {

    47     return UseConcMarkSweepGC;

    48   }

    49 

    50   virtual bool is_in_young(oop obj) const;

    51 

    52 private:

    53   CardTableRS* _rs;

    54 

    55   // *** Support for parallel card scanning.

    56 

    57   // dirty and precleaned are equivalent wrt younger_refs_iter.

    58   static bool card_is_dirty_wrt_gen_iter(jbyte cv) {

    59     return cv == dirty_card || cv == precleaned_card;

    60   }

    61 

    62   // Returns "true" iff the value "cv" will cause the card containing it

    63   // to be scanned in the current traversal.  May be overridden by

    64   // subtypes.

    65   bool card_will_be_scanned(jbyte cv);

    66 

    67   // Returns "true" iff the value "cv" may have represented a dirty card at

    68   // some point.

    69   bool card_may_have_been_dirty(jbyte cv);

    70 

    71   // Iterate over the portion of the card-table which covers the given

    72   // region mr in the given space and apply cl to any dirty sub-regions

    73   // of mr. Clears the dirty cards as they are processed.

    74   void non_clean_card_iterate_possibly_parallel(Space* sp, MemRegion mr,

    75                                                 OopsInGenClosure* cl, CardTableRS* ct,

    76                                                 uint n_threads);

    77 

    78   // Work method used to implement non_clean_card_iterate_possibly_parallel()

    79   // above in the parallel case.

    80   void non_clean_card_iterate_parallel_work(Space* sp, MemRegion mr,

    81                                             OopsInGenClosure* cl, CardTableRS* ct,

    82                                             uint n_threads);

    83 

    84   // This is an array, one element per covered region of the card table.

    85   // Each entry is itself an array, with one element per chunk in the

    86   // covered region.  Each entry of these arrays is the lowest non-clean

    87   // card of the corresponding chunk containing part of an object from the

    88   // previous chunk, or else NULL.

    89   typedef jbyte*  CardPtr;

    90   typedef CardPtr* CardArr;

    91   CardArr* _lowest_non_clean;

    92   size_t*  _lowest_non_clean_chunk_size;

    93   uintptr_t* _lowest_non_clean_base_chunk_index;

    94   volatile int* _last_LNC_resizing_collection;

    95 

    96   // Initializes "lowest_non_clean" to point to the array for the region

    97   // covering "sp", and "lowest_non_clean_base_chunk_index" to the chunk

    98   // index of the corresponding to the first element of that array.

    99   // Ensures that these arrays are of sufficient size, allocating if necessary.

   100   // May be called by several threads concurrently.

   101   void get_LNC_array_for_space(Space* sp,

   102                                jbyte**& lowest_non_clean,

   103                                uintptr_t& lowest_non_clean_base_chunk_index,

   104                                size_t& lowest_non_clean_chunk_size);

   105 

   106   // Returns the number of chunks necessary to cover "mr".

   107   size_t chunks_to_cover(MemRegion mr) {

   108     return (size_t)(addr_to_chunk_index(mr.last()) -

   109                     addr_to_chunk_index(mr.start()) + 1);

   110   }

   111 

   112   // Returns the index of the chunk in a stride which

   113   // covers the given address.

   114   uintptr_t addr_to_chunk_index(const void* addr) {

   115     uintptr_t card = (uintptr_t) byte_for(addr);

   116     return card / ParGCCardsPerStrideChunk;

   117   }

   118 

   119   // Apply cl, which must either itself apply dcto_cl or be dcto_cl,

   120   // to the cards in the stride (of n_strides) within the given space.

   121   void process_stride(Space* sp,

   122                       MemRegion used,

   123                       jint stride, int n_strides,

   124                       OopsInGenClosure* cl,

   125                       CardTableRS* ct,

   126                       jbyte** lowest_non_clean,

   127                       uintptr_t lowest_non_clean_base_chunk_index,

   128                       size_t lowest_non_clean_chunk_size);

   129 

   130   // Makes sure that chunk boundaries are handled appropriately, by

   131   // adjusting the min_done of dcto_cl, and by using a special card-table

   132   // value to indicate how min_done should be set.

   133   void process_chunk_boundaries(Space* sp,

   134                                 DirtyCardToOopClosure* dcto_cl,

   135                                 MemRegion chunk_mr,

   136                                 MemRegion used,

   137                                 jbyte** lowest_non_clean,

   138                                 uintptr_t lowest_non_clean_base_chunk_index,

   139                                 size_t    lowest_non_clean_chunk_size);

   140 

   141 };

   142 

   143 template<>

   144 struct BarrierSet::GetName<CardTableModRefBSForCTRS> {

   145   static const BarrierSet::Name value = BarrierSet::CardTableForRS;

   146 };

   147 

   148 template<>

   149 struct BarrierSet::GetType<BarrierSet::CardTableForRS> {

   150   typedef CardTableModRefBSForCTRS type;

   151 };

   152 

   153 #endif // SHARE_VM_GC_SHARED_CARDTABLEMODREFBSFORCTRS_HPP