1/*
2 * Copyright (c) 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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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
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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
30class CardTableRS;
31class DirtyCardToOopClosure;
32class OopsInGenClosure;
33
34// A specialization for the CardTableRS gen rem set.
35class CardTableModRefBSForCTRS: public CardTableModRefBS {
36  friend class CardTableRS;
37
38public:
39  CardTableModRefBSForCTRS(MemRegion whole_heap);
40  ~CardTableModRefBSForCTRS();
41
42  virtual void initialize();
43
44  void set_CTRS(CardTableRS* rs) { _rs = rs; }
45
46private:
47  CardTableRS* _rs;
48
49  // *** Support for parallel card scanning.
50
51  // dirty and precleaned are equivalent wrt younger_refs_iter.
52  static bool card_is_dirty_wrt_gen_iter(jbyte cv) {
53    return cv == dirty_card || cv == precleaned_card;
54  }
55
56  // Returns "true" iff the value "cv" will cause the card containing it
57  // to be scanned in the current traversal.  May be overridden by
58  // subtypes.
59  bool card_will_be_scanned(jbyte cv);
60
61  // Returns "true" iff the value "cv" may have represented a dirty card at
62  // some point.
63  bool card_may_have_been_dirty(jbyte cv);
64
65  // Iterate over the portion of the card-table which covers the given
66  // region mr in the given space and apply cl to any dirty sub-regions
67  // of mr. Clears the dirty cards as they are processed.
68  void non_clean_card_iterate_possibly_parallel(Space* sp, MemRegion mr,
69                                                OopsInGenClosure* cl, CardTableRS* ct,
70                                                uint n_threads);
71
72  // Work method used to implement non_clean_card_iterate_possibly_parallel()
73  // above in the parallel case.
74  void non_clean_card_iterate_parallel_work(Space* sp, MemRegion mr,
75                                            OopsInGenClosure* cl, CardTableRS* ct,
76                                            uint n_threads);
77
78  // This is an array, one element per covered region of the card table.
79  // Each entry is itself an array, with one element per chunk in the
80  // covered region.  Each entry of these arrays is the lowest non-clean
81  // card of the corresponding chunk containing part of an object from the
82  // previous chunk, or else NULL.
83  typedef jbyte*  CardPtr;
84  typedef CardPtr* CardArr;
85  CardArr* _lowest_non_clean;
86  size_t*  _lowest_non_clean_chunk_size;
87  uintptr_t* _lowest_non_clean_base_chunk_index;
88  volatile int* _last_LNC_resizing_collection;
89
90  // Initializes "lowest_non_clean" to point to the array for the region
91  // covering "sp", and "lowest_non_clean_base_chunk_index" to the chunk
92  // index of the corresponding to the first element of that array.
93  // Ensures that these arrays are of sufficient size, allocating if necessary.
94  // May be called by several threads concurrently.
95  void get_LNC_array_for_space(Space* sp,
96                               jbyte**& lowest_non_clean,
97                               uintptr_t& lowest_non_clean_base_chunk_index,
98                               size_t& lowest_non_clean_chunk_size);
99
100  // Returns the number of chunks necessary to cover "mr".
101  size_t chunks_to_cover(MemRegion mr) {
102    return (size_t)(addr_to_chunk_index(mr.last()) -
103                    addr_to_chunk_index(mr.start()) + 1);
104  }
105
106  // Returns the index of the chunk in a stride which
107  // covers the given address.
108  uintptr_t addr_to_chunk_index(const void* addr) {
109    uintptr_t card = (uintptr_t) byte_for(addr);
110    return card / ParGCCardsPerStrideChunk;
111  }
112
113  // Apply cl, which must either itself apply dcto_cl or be dcto_cl,
114  // to the cards in the stride (of n_strides) within the given space.
115  void process_stride(Space* sp,
116                      MemRegion used,
117                      jint stride, int n_strides,
118                      OopsInGenClosure* cl,
119                      CardTableRS* ct,
120                      jbyte** lowest_non_clean,
121                      uintptr_t lowest_non_clean_base_chunk_index,
122                      size_t lowest_non_clean_chunk_size);
123
124  // Makes sure that chunk boundaries are handled appropriately, by
125  // adjusting the min_done of dcto_cl, and by using a special card-table
126  // value to indicate how min_done should be set.
127  void process_chunk_boundaries(Space* sp,
128                                DirtyCardToOopClosure* dcto_cl,
129                                MemRegion chunk_mr,
130                                MemRegion used,
131                                jbyte** lowest_non_clean,
132                                uintptr_t lowest_non_clean_base_chunk_index,
133                                size_t    lowest_non_clean_chunk_size);
134
135};
136
137template<>
138struct BarrierSet::GetName<CardTableModRefBSForCTRS> {
139  static const BarrierSet::Name value = BarrierSet::CardTableForRS;
140};
141
142#endif // include guard
143
144