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.
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.
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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_GC_SHARED_CARDTABLERS_HPP
26 #define SHARE_VM_GC_SHARED_CARDTABLERS_HPP
27
28 #include "gc/shared/cardTableModRefBSForCTRS.hpp"
29 #include "memory/memRegion.hpp"
30
31 class Space;
32 class OopsInGenClosure;
33
34 // Helper to remember modified oops in all klasses.
35 class KlassRemSet {
36 bool _accumulate_modified_oops;
37 public:
38 KlassRemSet() : _accumulate_modified_oops(false) {}
39 void set_accumulate_modified_oops(bool value) { _accumulate_modified_oops = value; }
40 bool accumulate_modified_oops() { return _accumulate_modified_oops; }
41 bool mod_union_is_clear();
42 void clear_mod_union();
43 };
44
45 // This RemSet uses a card table both as shared data structure
46 // for a mod ref barrier set and for the rem set information.
47
48 class CardTableRS: public CHeapObj<mtGC> {
49 friend class VMStructs;
50 // Below are private classes used in impl.
51 friend class VerifyCTSpaceClosure;
52 friend class ClearNoncleanCardWrapper;
53
54 static jbyte clean_card_val() {
55 return CardTableModRefBSForCTRS::clean_card;
56 }
57
58 static intptr_t clean_card_row() {
59 return CardTableModRefBSForCTRS::clean_card_row;
60 }
61
62 static bool
63 card_is_dirty_wrt_gen_iter(jbyte cv) {
64 return CardTableModRefBSForCTRS::card_is_dirty_wrt_gen_iter(cv);
65 }
66
67 KlassRemSet _klass_rem_set;
68 BarrierSet* _bs;
69
70 CardTableModRefBSForCTRS* _ct_bs;
71
72 void verify_space(Space* s, HeapWord* gen_start);
73
74 enum ExtendedCardValue {
75 youngergen_card = CardTableModRefBSForCTRS::CT_MR_BS_last_reserved + 1,
76 // These are for parallel collection.
77 // There are three P (parallel) youngergen card values. In general, this
78 // needs to be more than the number of generations (including the perm
79 // gen) that might have younger_refs_do invoked on them separately. So
80 // if we add more gens, we have to add more values.
81 youngergenP1_card = CardTableModRefBSForCTRS::CT_MR_BS_last_reserved + 2,
82 youngergenP2_card = CardTableModRefBSForCTRS::CT_MR_BS_last_reserved + 3,
83 youngergenP3_card = CardTableModRefBSForCTRS::CT_MR_BS_last_reserved + 4,
84 cur_youngergen_and_prev_nonclean_card =
85 CardTableModRefBSForCTRS::CT_MR_BS_last_reserved + 5
86 };
87
88 // An array that contains, for each generation, the card table value last
89 // used as the current value for a younger_refs_do iteration of that
90 // portion of the table. The perm gen is index 0. The young gen is index 1,
91 // but will always have the value "clean_card". The old gen is index 2.
92 jbyte* _last_cur_val_in_gen;
93
94 jbyte _cur_youngergen_card_val;
95
96 // Number of generations, plus one for lingering PermGen issues in CardTableRS.
97 static const int _regions_to_iterate = 3;
98
99 jbyte cur_youngergen_card_val() {
100 return _cur_youngergen_card_val;
101 }
102 void set_cur_youngergen_card_val(jbyte v) {
103 _cur_youngergen_card_val = v;
104 }
105 bool is_prev_youngergen_card_val(jbyte v) {
106 return
107 youngergen_card <= v &&
108 v < cur_youngergen_and_prev_nonclean_card &&
109 v != _cur_youngergen_card_val;
110 }
111 // Return a youngergen_card_value that is not currently in use.
112 jbyte find_unused_youngergenP_card_value();
113
114 public:
115 CardTableRS(MemRegion whole_heap);
116 ~CardTableRS();
117
118 // Return the barrier set associated with "this."
119 BarrierSet* bs() { return _bs; }
120
121 // Set the barrier set.
122 void set_bs(BarrierSet* bs) { _bs = bs; }
123
124 KlassRemSet* klass_rem_set() { return &_klass_rem_set; }
125
126 CardTableModRefBSForCTRS* ct_bs() { return _ct_bs; }
127
128 void younger_refs_in_space_iterate(Space* sp, OopsInGenClosure* cl, uint n_threads);
129
130 // Override.
131 void prepare_for_younger_refs_iterate(bool parallel);
132
133 // Card table entries are cleared before application; "blk" is
134 // responsible for dirtying if the oop is still older-to-younger after
135 // closure application.
136 void younger_refs_iterate(Generation* g, OopsInGenClosure* blk, uint n_threads);
137
138 void inline_write_ref_field_gc(void* field, oop new_val) {
139 jbyte* byte = _ct_bs->byte_for(field);
140 *byte = youngergen_card;
141 }
142 void write_ref_field_gc_work(void* field, oop new_val) {
143 inline_write_ref_field_gc(field, new_val);
144 }
145
146 // Override. Might want to devirtualize this in the same fashion as
147 // above. Ensures that the value of the card for field says that it's
148 // a younger card in the current collection.
149 virtual void write_ref_field_gc_par(void* field, oop new_val);
150
151 void resize_covered_region(MemRegion new_region);
152
153 bool is_aligned(HeapWord* addr) {
154 return _ct_bs->is_card_aligned(addr);
155 }
156
157 void verify();
158
159 void clear(MemRegion mr) { _ct_bs->clear(mr); }
160 void clear_into_younger(Generation* old_gen);
161
162 void invalidate(MemRegion mr) {
163 _ct_bs->invalidate(mr);
164 }
165 void invalidate_or_clear(Generation* old_gen);
166
167 static uintx ct_max_alignment_constraint() {
168 return CardTableModRefBSForCTRS::ct_max_alignment_constraint();
169 }
170
171 jbyte* byte_for(void* p) { return _ct_bs->byte_for(p); }
172 jbyte* byte_after(void* p) { return _ct_bs->byte_after(p); }
173 HeapWord* addr_for(jbyte* p) { return _ct_bs->addr_for(p); }
174
175 bool is_prev_nonclean_card_val(jbyte v) {
176 return
177 youngergen_card <= v &&
178 v <= cur_youngergen_and_prev_nonclean_card &&
179 v != _cur_youngergen_card_val;
180 }
181
182 static bool youngergen_may_have_been_dirty(jbyte cv) {
183 return cv == CardTableRS::cur_youngergen_and_prev_nonclean_card;
184 }
185
186 };
187
188 class ClearNoncleanCardWrapper: public MemRegionClosure {
189 DirtyCardToOopClosure* _dirty_card_closure;
190 CardTableRS* _ct;
191 bool _is_par;
192 private:
193 // Clears the given card, return true if the corresponding card should be
194 // processed.
195 inline bool clear_card(jbyte* entry);
196 // Work methods called by the clear_card()
197 inline bool clear_card_serial(jbyte* entry);
198 inline bool clear_card_parallel(jbyte* entry);
199 // check alignment of pointer
200 bool is_word_aligned(jbyte* entry);
201
202 public:
203 ClearNoncleanCardWrapper(DirtyCardToOopClosure* dirty_card_closure, CardTableRS* ct, bool is_par);
204 void do_MemRegion(MemRegion mr);
205 };
206
207 #endif // SHARE_VM_GC_SHARED_CARDTABLERS_HPP