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. 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_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