1 /*
2 * Copyright (c) 2001, 2012, 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.
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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).
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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 // making this constants into inline methods kills performance for some reason
49 static intptr_t clean_card_row() {
50 return CardTableModRefBS::clean_card_row;
51 }
52
53 static bool card_is_dirty_wrt_gen_iter(jbyte cv) {
54 return CardTableModRefBS::card_is_dirty_wrt_gen_iter(cv);
55 }
56
57 CardTableModRefBSForCTRS* _ct_bs;
58
59 virtual void younger_refs_in_space_iterate(Space* sp, OopsInGenClosure* cl);
60
61 void verify_space(Space* s, HeapWord* gen_start);
62
63 enum ExtendedCardValue {
64 youngergen_card = CardTableModRefBS::CT_MR_BS_last_reserved + 1,
65 // These are for parallel collection.
66 // There are three P (parallel) youngergen card values. In general, this
67 // needs to be more than the number of generations (including the perm
68 // gen) that might have younger_refs_do invoked on them separately. So
69 // if we add more gens, we have to add more values.
70 youngergenP1_card = CardTableModRefBS::CT_MR_BS_last_reserved + 2,
71 youngergenP2_card = CardTableModRefBS::CT_MR_BS_last_reserved + 3,
72 youngergenP3_card = CardTableModRefBS::CT_MR_BS_last_reserved + 4,
73 cur_youngergen_and_prev_nonclean_card =
74 CardTableModRefBS::CT_MR_BS_last_reserved + 5
75 };
76
77 // An array that contains, for each generation, the card table value last
78 // used as the current value for a younger_refs_do iteration of that
79 // portion of the table. (The perm gen is index 0; other gens are at
80 // their level plus 1. They youngest gen is in the table, but will
81 // always have the value "clean_card".)
82 jbyte* _last_cur_val_in_gen;
83
84 jbyte _cur_youngergen_card_val;
85
86 int _regions_to_iterate;
87
88 jbyte cur_youngergen_card_val() {
89 return _cur_youngergen_card_val;
90 }
91 void set_cur_youngergen_card_val(jbyte v) {
92 _cur_youngergen_card_val = v;
93 }
94 bool is_prev_youngergen_card_val(jbyte v) {
95 return
96 youngergen_card <= v &&
97 v < cur_youngergen_and_prev_nonclean_card &&
98 v != _cur_youngergen_card_val;
99 }
100 // Return a youngergen_card_value that is not currently in use.
101 jbyte find_unused_youngergenP_card_value();
102
103 public:
104 CardTableRS(MemRegion whole_heap, int max_covered_regions);
105
106 // *** GenRemSet functions.
107 GenRemSet::Name rs_kind() { return GenRemSet::CardTable; }
108
109 CardTableRS* as_CardTableRS() { return this; }
110
111 CardTableModRefBS* ct_bs() { return _ct_bs; }
112
113 // Override.
114 void prepare_for_younger_refs_iterate(bool parallel);
115
116 // Card table entries are cleared before application; "blk" is
117 // responsible for dirtying if the oop is still older-to-younger after
118 // closure application.
119 void younger_refs_iterate(Generation* g, OopsInGenClosure* blk);
120
121 void inline_write_ref_field_gc(void* field, oop new_val) {
122 jbyte* byte = _ct_bs->byte_for(field);
123 *byte = youngergen_card;
124 }
125 void write_ref_field_gc_work(void* field, oop new_val) {
126 inline_write_ref_field_gc(field, new_val);
127 }
128
129 // Override. Might want to devirtualize this in the same fashion as
130 // above. Ensures that the value of the card for field says that it's
131 // a younger card in the current collection.
132 virtual void write_ref_field_gc_par(void* field, oop new_val);
133
134 void resize_covered_region(MemRegion new_region);
135
136 bool is_aligned(HeapWord* addr) {
137 return _ct_bs->is_card_aligned(addr);
138 }
139
140 void verify();
141 void verify_aligned_region_empty(MemRegion mr);
142
143 void clear(MemRegion mr) { _ct_bs->clear(mr); }
144 void clear_into_younger(Generation* gen, bool clear_perm);
145
146 void invalidate(MemRegion mr, bool whole_heap = false) {
147 _ct_bs->invalidate(mr, whole_heap);
148 }
149 void invalidate_or_clear(Generation* gen, bool younger, bool perm);
150
151 static uintx ct_max_alignment_constraint() {
152 return CardTableModRefBS::ct_max_alignment_constraint();
153 }
154
155 jbyte* byte_for(void* p) { return _ct_bs->byte_for(p); }
156 jbyte* byte_after(void* p) { return _ct_bs->byte_after(p); }
157 HeapWord* addr_for(jbyte* p) { return _ct_bs->addr_for(p); }
158
159 bool is_prev_nonclean_card_val(jbyte v) {
160 return
161 youngergen_card <= v &&
162 v <= cur_youngergen_and_prev_nonclean_card &&
163 v != _cur_youngergen_card_val;
164 }
165
166 static bool youngergen_may_have_been_dirty(jbyte cv) {
167 return cv == CardTableRS::cur_youngergen_and_prev_nonclean_card;
168 }
169
170 };
171
172 class ClearNoncleanCardWrapper: public MemRegionClosure {
173 DirtyCardToOopClosure* _dirty_card_closure;
174 CardTableRS* _ct;
175 bool _is_par;
176 private:
177 // Clears the given card, return true if the corresponding card should be
178 // processed.
179 inline bool clear_card(jbyte* entry);
180 // Work methods called by the clear_card()
181 inline bool clear_card_serial(jbyte* entry);
182 inline bool clear_card_parallel(jbyte* entry);
183 // check alignment of pointer
184 bool is_word_aligned(jbyte* entry);
185
186 public:
187 ClearNoncleanCardWrapper(DirtyCardToOopClosure* dirty_card_closure, CardTableRS* ct);
188 void do_MemRegion(MemRegion mr);
189 };
190
191 #endif // SHARE_VM_MEMORY_CARDTABLERS_HPP