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.
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.
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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
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 private:
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 volatile 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 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 volatile 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 volatile 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 volatile jbyte** lowest_non_clean,
132 uintptr_t lowest_non_clean_base_chunk_index,
133 size_t lowest_non_clean_chunk_size);
134
135 };
136
137 template<>
138 struct BarrierSet::GetName<CardTableModRefBSForCTRS> {
139 static const BarrierSet::Name value = BarrierSet::CardTableForRS;
140 };
141
142 #endif // include guard