1 /*
2 * Copyright (c) 2001, 2011, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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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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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
35 // This kind of "GenRemSet" uses a card table both as shared data structure
36 // for a mod ref barrier set and for the rem set information.
37
38 class CardTableRS: public GenRemSet {
39 friend class VMStructs;
40 // Below are private classes used in impl.
41 friend class VerifyCTSpaceClosure;
42 friend class ClearNoncleanCardWrapper;
43
44 static jbyte clean_card_val() {
45 return CardTableModRefBS::clean_card;
46 }
47
48 static bool
49 card_is_dirty_wrt_gen_iter(jbyte cv) {
50 return CardTableModRefBS::card_is_dirty_wrt_gen_iter(cv);
51 }
52
53 CardTableModRefBSForCTRS* _ct_bs;
54
55 virtual void younger_refs_in_space_iterate(Space* sp, OopsInGenClosure* cl);
56
57 void verify_space(Space* s, HeapWord* gen_start);
58
59 enum ExtendedCardValue {
60 youngergen_card = CardTableModRefBS::CT_MR_BS_last_reserved + 1,
61 // These are for parallel collection.
62 // There are three P (parallel) youngergen card values. In general, this
63 // needs to be more than the number of generations (including the perm
64 // gen) that might have younger_refs_do invoked on them separately. So
65 // if we add more gens, we have to add more values.
66 youngergenP1_card = CardTableModRefBS::CT_MR_BS_last_reserved + 2,
67 youngergenP2_card = CardTableModRefBS::CT_MR_BS_last_reserved + 3,
68 youngergenP3_card = CardTableModRefBS::CT_MR_BS_last_reserved + 4,
69 cur_youngergen_and_prev_nonclean_card =
70 CardTableModRefBS::CT_MR_BS_last_reserved + 5
71 };
72
73 // An array that contains, for each generation, the card table value last
74 // used as the current value for a younger_refs_do iteration of that
75 // portion of the table. (The perm gen is index 0; other gens are at
76 // their level plus 1. They youngest gen is in the table, but will
77 // always have the value "clean_card".)
78 jbyte* _last_cur_val_in_gen;
79
80 jbyte _cur_youngergen_card_val;
81
82 int _regions_to_iterate;
83
84 jbyte cur_youngergen_card_val() {
85 return _cur_youngergen_card_val;
86 }
87 void set_cur_youngergen_card_val(jbyte v) {
88 _cur_youngergen_card_val = v;
89 }
90 bool is_prev_youngergen_card_val(jbyte v) {
91 return
92 youngergen_card <= v &&
93 v < cur_youngergen_and_prev_nonclean_card &&
94 v != _cur_youngergen_card_val;
95 }
96 // Return a youngergen_card_value that is not currently in use.
97 jbyte find_unused_youngergenP_card_value();
98
99 public:
100 CardTableRS(MemRegion whole_heap, int max_covered_regions);
101
102 // *** GenRemSet functions.
103 GenRemSet::Name rs_kind() { return GenRemSet::CardTable; }
104
105 CardTableRS* as_CardTableRS() { return this; }
106
107 CardTableModRefBS* ct_bs() { return _ct_bs; }
108
109 // Override.
110 void prepare_for_younger_refs_iterate(bool parallel);
111
112 // Card table entries are cleared before application; "blk" is
113 // responsible for dirtying if the oop is still older-to-younger after
114 // closure application.
115 void younger_refs_iterate(Generation* g, OopsInGenClosure* blk);
116
117 void inline_write_ref_field_gc(void* field, oop new_val) {
118 jbyte* byte = _ct_bs->byte_for(field);
119 *byte = youngergen_card;
120 }
121 void write_ref_field_gc_work(void* field, oop new_val) {
122 inline_write_ref_field_gc(field, new_val);
123 }
124
125 // Override. Might want to devirtualize this in the same fashion as
126 // above. Ensures that the value of the card for field says that it's
127 // a younger card in the current collection.
128 virtual void write_ref_field_gc_par(void* field, oop new_val);
129
130 void resize_covered_region(MemRegion new_region);
131
132 bool is_aligned(HeapWord* addr) {
133 return _ct_bs->is_card_aligned(addr);
134 }
135
136 void verify();
137 void verify_aligned_region_empty(MemRegion mr);
138
139 void clear(MemRegion mr) { _ct_bs->clear(mr); }
140 void clear_into_younger(Generation* gen, bool clear_perm);
141
142 void invalidate(MemRegion mr, bool whole_heap = false) {
143 _ct_bs->invalidate(mr, whole_heap);
144 }
145 void invalidate_or_clear(Generation* gen, bool younger, bool perm);
146
147 static uintx ct_max_alignment_constraint() {
148 return CardTableModRefBS::ct_max_alignment_constraint();
149 }
150
151 jbyte* byte_for(void* p) { return _ct_bs->byte_for(p); }
152 jbyte* byte_after(void* p) { return _ct_bs->byte_after(p); }
153 HeapWord* addr_for(jbyte* p) { return _ct_bs->addr_for(p); }
154
155 bool is_prev_nonclean_card_val(jbyte v) {
156 return
157 youngergen_card <= v &&
158 v <= cur_youngergen_and_prev_nonclean_card &&
159 v != _cur_youngergen_card_val;
160 }
161
162 static bool youngergen_may_have_been_dirty(jbyte cv) {
163 return cv == CardTableRS::cur_youngergen_and_prev_nonclean_card;
164 }
165
166 };
167
168 class ClearNoncleanCardWrapper: public MemRegionClosure {
169 DirtyCardToOopClosure* _dirty_card_closure;
170 CardTableRS* _ct;
171 bool _is_par;
172 private:
173 // Clears the given card, return true if the corresponding card should be
174 // processed.
175 inline bool clear_card(jbyte* entry);
176 // Work methods called by the clear_card()
177 inline bool clear_card_serial(jbyte* entry);
178 inline bool clear_card_parallel(jbyte* entry);
179
180 public:
181 ClearNoncleanCardWrapper(DirtyCardToOopClosure* dirty_card_closure, CardTableRS* ct);
182 void do_MemRegion(MemRegion mr);
183 };
184
185 #endif // SHARE_VM_MEMORY_CARDTABLERS_HPP