1 /* 2 * Copyright (c) 2001, 2013, 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. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 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 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 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 ~CardTableRS(); 106 107 // *** GenRemSet functions. 108 GenRemSet::Name rs_kind() { return GenRemSet::CardTable; } 109 110 CardTableRS* as_CardTableRS() { return this; } 111 112 CardTableModRefBS* ct_bs() { return _ct_bs; } 113 114 // Override. 115 void prepare_for_younger_refs_iterate(bool parallel); 116 117 // Card table entries are cleared before application; "blk" is 118 // responsible for dirtying if the oop is still older-to-younger after 119 // closure application. 120 void younger_refs_iterate(Generation* g, OopsInGenClosure* blk); 121 122 void inline_write_ref_field_gc(void* field, oop new_val) { 123 jbyte* byte = _ct_bs->byte_for(field); 124 *byte = youngergen_card; 125 } 126 void write_ref_field_gc_work(void* field, oop new_val) { 127 inline_write_ref_field_gc(field, new_val); 128 } 129 130 // Override. Might want to devirtualize this in the same fashion as 131 // above. Ensures that the value of the card for field says that it's 132 // a younger card in the current collection. 133 virtual void write_ref_field_gc_par(void* field, oop new_val); 134 135 void resize_covered_region(MemRegion new_region); 136 137 bool is_aligned(HeapWord* addr) { 138 return _ct_bs->is_card_aligned(addr); 139 } 140 141 void verify(); 142 void verify_aligned_region_empty(MemRegion mr); 143 144 void clear(MemRegion mr) { _ct_bs->clear(mr); } 145 void clear_into_younger(Generation* old_gen); 146 147 void invalidate(MemRegion mr, bool whole_heap = false) { 148 _ct_bs->invalidate(mr, whole_heap); 149 } 150 void invalidate_or_clear(Generation* old_gen); 151 152 static uintx ct_max_alignment_constraint() { 153 return CardTableModRefBS::ct_max_alignment_constraint(); 154 } 155 156 jbyte* byte_for(void* p) { return _ct_bs->byte_for(p); } 157 jbyte* byte_after(void* p) { return _ct_bs->byte_after(p); } 158 HeapWord* addr_for(jbyte* p) { return _ct_bs->addr_for(p); } 159 160 bool is_prev_nonclean_card_val(jbyte v) { 161 return 162 youngergen_card <= v && 163 v <= cur_youngergen_and_prev_nonclean_card && 164 v != _cur_youngergen_card_val; 165 } 166 167 static bool youngergen_may_have_been_dirty(jbyte cv) { 168 return cv == CardTableRS::cur_youngergen_and_prev_nonclean_card; 169 } 170 171 }; 172 173 class ClearNoncleanCardWrapper: public MemRegionClosure { 174 DirtyCardToOopClosure* _dirty_card_closure; 175 CardTableRS* _ct; 176 bool _is_par; 177 private: 178 // Clears the given card, return true if the corresponding card should be 179 // processed. 180 inline bool clear_card(jbyte* entry); 181 // Work methods called by the clear_card() 182 inline bool clear_card_serial(jbyte* entry); 183 inline bool clear_card_parallel(jbyte* entry); 184 // check alignment of pointer 185 bool is_word_aligned(jbyte* entry); 186 187 public: 188 ClearNoncleanCardWrapper(DirtyCardToOopClosure* dirty_card_closure, CardTableRS* ct); 189 void do_MemRegion(MemRegion mr); 190 }; 191 192 #endif // SHARE_VM_MEMORY_CARDTABLERS_HPP