1 /*
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   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
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
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   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  *
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  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
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  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   CardTableRS* as_CardTableRS() { return this; }
 109 
 110   CardTableModRefBS* ct_bs() { return _ct_bs; }
 111 
 112   // Override.
 113   void prepare_for_younger_refs_iterate(bool parallel);
 114 
 115   // Card table entries are cleared before application; "blk" is
 116   // responsible for dirtying if the oop is still older-to-younger after
 117   // closure application.
 118   void younger_refs_iterate(Generation* g, OopsInGenClosure* blk);
 119 
 120   void inline_write_ref_field_gc(void* field, oop new_val) {
 121     jbyte* byte = _ct_bs->byte_for(field);
 122     *byte = youngergen_card;
 123   }
 124   void write_ref_field_gc_work(void* field, oop new_val) {
 125     inline_write_ref_field_gc(field, new_val);
 126   }
 127 
 128   // Override.  Might want to devirtualize this in the same fashion as
 129   // above.  Ensures that the value of the card for field says that it's
 130   // a younger card in the current collection.
 131   virtual void write_ref_field_gc_par(void* field, oop new_val);
 132 
 133   void resize_covered_region(MemRegion new_region);
 134 
 135   bool is_aligned(HeapWord* addr) {
 136     return _ct_bs->is_card_aligned(addr);
 137   }
 138 
 139   void verify();
 140   void verify_aligned_region_empty(MemRegion mr);
 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_MEMORY_CARDTABLERS_HPP