1 /*
2 * Copyright (c) 2001, 2015, 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).
14 *
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24
25 #ifndef SHARE_VM_GC_SHARED_CARDTABLERS_HPP
26 #define SHARE_VM_GC_SHARED_CARDTABLERS_HPP
27
28 #include "gc/shared/cardTableModRefBS.hpp"
29 #include "gc/shared/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 intptr_t clean_card_row() {
49 return CardTableModRefBS::clean_card_row;
50 }
51
52 static bool
53 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 // Number of generations, plus one for lingering PermGen issues in CardTableRS.
87 static const int _regions_to_iterate = 3;
88
89 jbyte cur_youngergen_card_val() {
90 return _cur_youngergen_card_val;
91 }
92 void set_cur_youngergen_card_val(jbyte v) {
93 _cur_youngergen_card_val = v;
94 }
95 bool is_prev_youngergen_card_val(jbyte v) {
96 return
97 youngergen_card <= v &&
98 v < cur_youngergen_and_prev_nonclean_card &&
99 v != _cur_youngergen_card_val;
100 }
101 // Return a youngergen_card_value that is not currently in use.
102 jbyte find_unused_youngergenP_card_value();
103
104 public:
105 CardTableRS(MemRegion whole_heap);
106 ~CardTableRS();
107
108 // *** GenRemSet functions.
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
142 void clear(MemRegion mr) { _ct_bs->clear(mr); }
143 void clear_into_younger(Generation* old_gen);
144
145 void invalidate(MemRegion mr, bool whole_heap = false) {
146 _ct_bs->invalidate(mr, whole_heap);
147 }
148 void invalidate_or_clear(Generation* old_gen);
149
150 static uintx ct_max_alignment_constraint() {
151 return CardTableModRefBS::ct_max_alignment_constraint();
152 }
153
154 jbyte* byte_for(void* p) { return _ct_bs->byte_for(p); }
155 jbyte* byte_after(void* p) { return _ct_bs->byte_after(p); }
156 HeapWord* addr_for(jbyte* p) { return _ct_bs->addr_for(p); }
157
158 bool is_prev_nonclean_card_val(jbyte v) {
159 return
160 youngergen_card <= v &&
161 v <= cur_youngergen_and_prev_nonclean_card &&
162 v != _cur_youngergen_card_val;
163 }
164
165 static bool youngergen_may_have_been_dirty(jbyte cv) {
166 return cv == CardTableRS::cur_youngergen_and_prev_nonclean_card;
167 }
168
169 };
170
171 class ClearNoncleanCardWrapper: public MemRegionClosure {
172 DirtyCardToOopClosure* _dirty_card_closure;
173 CardTableRS* _ct;
174 bool _is_par;
175 private:
176 // Clears the given card, return true if the corresponding card should be
177 // processed.
178 inline bool clear_card(jbyte* entry);
179 // Work methods called by the clear_card()
180 inline bool clear_card_serial(jbyte* entry);
181 inline bool clear_card_parallel(jbyte* entry);
182 // check alignment of pointer
183 bool is_word_aligned(jbyte* entry);
184
185 public:
186 ClearNoncleanCardWrapper(DirtyCardToOopClosure* dirty_card_closure, CardTableRS* ct);
187 void do_MemRegion(MemRegion mr);
188 };
189
190 #endif // SHARE_VM_GC_SHARED_CARDTABLERS_HPP