1 /*
2 * Copyright (c) 2001, 2010, 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
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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
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23 */
24
25 #ifndef SHARE_VM_MEMORY_CARDTABLERS_HPP
26 #define SHARE_VM_MEMORY_CARDTABLERS_HPP
27
28 #include "memory/cardTableModRefBS.hpp"
29 #include "memory/genRemSet.hpp"
30 #include "memory/memRegion.hpp"
31
32 class Space;
33 class OopsInGenClosure;
34 class DirtyCardToOopClosure;
35
36 // This kind of "GenRemSet" uses a card table both as shared data structure
37 // for a mod ref barrier set and for the rem set information.
38
39 class CardTableRS: public GenRemSet {
40 friend class VMStructs;
41 // Below are private classes used in impl.
42 friend class VerifyCTSpaceClosure;
43 friend class ClearNoncleanCardWrapper;
44
45 static jbyte clean_card_val() {
46 return CardTableModRefBS::clean_card;
47 }
48
49 static bool
50 card_is_dirty_wrt_gen_iter(jbyte cv) {
51 return CardTableModRefBS::card_is_dirty_wrt_gen_iter(cv);
52 }
53
54 CardTableModRefBSForCTRS* _ct_bs;
55
56 virtual void younger_refs_in_space_iterate(Space* sp, OopsInGenClosure* cl);
57
58 void verify_space(Space* s, HeapWord* gen_start);
59
60 enum ExtendedCardValue {
61 youngergen_card = CardTableModRefBS::CT_MR_BS_last_reserved + 1,
62 // These are for parallel collection.
63 // There are three P (parallel) youngergen card values. In general, this
64 // needs to be more than the number of generations (including the perm
65 // gen) that might have younger_refs_do invoked on them separately. So
66 // if we add more gens, we have to add more values.
67 youngergenP1_card = CardTableModRefBS::CT_MR_BS_last_reserved + 2,
68 youngergenP2_card = CardTableModRefBS::CT_MR_BS_last_reserved + 3,
69 youngergenP3_card = CardTableModRefBS::CT_MR_BS_last_reserved + 4,
70 cur_youngergen_and_prev_nonclean_card =
71 CardTableModRefBS::CT_MR_BS_last_reserved + 5
72 };
73
74 // An array that contains, for each generation, the card table value last
75 // used as the current value for a younger_refs_do iteration of that
76 // portion of the table. (The perm gen is index 0; other gens are at
77 // their level plus 1. They youngest gen is in the table, but will
78 // always have the value "clean_card".)
79 jbyte* _last_cur_val_in_gen;
80
81 jbyte _cur_youngergen_card_val;
82
83 int _regions_to_iterate;
84
85 jbyte cur_youngergen_card_val() {
86 return _cur_youngergen_card_val;
87 }
88 void set_cur_youngergen_card_val(jbyte v) {
89 _cur_youngergen_card_val = v;
90 }
91 bool is_prev_youngergen_card_val(jbyte v) {
92 return
93 youngergen_card <= v &&
94 v < cur_youngergen_and_prev_nonclean_card &&
95 v != _cur_youngergen_card_val;
96 }
97 // Return a youngergen_card_value that is not currently in use.
98 jbyte find_unused_youngergenP_card_value();
99
100 public:
101 CardTableRS(MemRegion whole_heap, int max_covered_regions);
102
103 // *** GenRemSet functions.
104 GenRemSet::Name rs_kind() { return GenRemSet::CardTable; }
105
106 CardTableRS* as_CardTableRS() { return this; }
107
108 CardTableModRefBS* ct_bs() { return _ct_bs; }
109
110 // Override.
111 void prepare_for_younger_refs_iterate(bool parallel);
112
113 // Card table entries are cleared before application; "blk" is
114 // responsible for dirtying if the oop is still older-to-younger after
115 // closure application.
116 void younger_refs_iterate(Generation* g, OopsInGenClosure* blk);
117
118 void inline_write_ref_field_gc(void* field, oop new_val) {
119 jbyte* byte = _ct_bs->byte_for(field);
120 *byte = youngergen_card;
121 }
122 void write_ref_field_gc_work(void* field, oop new_val) {
123 inline_write_ref_field_gc(field, new_val);
124 }
125
126 // Override. Might want to devirtualize this in the same fashion as
127 // above. Ensures that the value of the card for field says that it's
128 // a younger card in the current collection.
129 virtual void write_ref_field_gc_par(void* field, oop new_val);
130
131 void resize_covered_region(MemRegion new_region);
132
133 bool is_aligned(HeapWord* addr) {
134 return _ct_bs->is_card_aligned(addr);
135 }
136
137 void verify();
138 void verify_aligned_region_empty(MemRegion mr);
139
140 void clear(MemRegion mr) { _ct_bs->clear(mr); }
141 void clear_into_younger(Generation* gen, bool clear_perm);
142
143 void invalidate(MemRegion mr, bool whole_heap = false) {
144 _ct_bs->invalidate(mr, whole_heap);
145 }
146 void invalidate_or_clear(Generation* gen, bool younger, bool perm);
147
148 static uintx ct_max_alignment_constraint() {
149 return CardTableModRefBS::ct_max_alignment_constraint();
150 }
151
152 jbyte* byte_for(void* p) { return _ct_bs->byte_for(p); }
153 jbyte* byte_after(void* p) { return _ct_bs->byte_after(p); }
154 HeapWord* addr_for(jbyte* p) { return _ct_bs->addr_for(p); }
155
156 bool is_prev_nonclean_card_val(jbyte v) {
157 return
158 youngergen_card <= v &&
159 v <= cur_youngergen_and_prev_nonclean_card &&
160 v != _cur_youngergen_card_val;
161 }
162
163 static bool youngergen_may_have_been_dirty(jbyte cv) {
164 return cv == CardTableRS::cur_youngergen_and_prev_nonclean_card;
165 }
166
167 };
168
169 #endif // SHARE_VM_MEMORY_CARDTABLERS_HPP