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/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