cardTableRS.hpp revision 8413:92457dfb91bd 
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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
32class Space;
33class 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
38class 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
104public:
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
171class ClearNoncleanCardWrapper: public MemRegionClosure {
172  DirtyCardToOopClosure* _dirty_card_closure;
173  CardTableRS* _ct;
174  bool _is_par;
175private:
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
185public:
186  ClearNoncleanCardWrapper(DirtyCardToOopClosure* dirty_card_closure, CardTableRS* ct);
187  void do_MemRegion(MemRegion mr);
188};
189
190#endif // SHARE_VM_GC_SHARED_CARDTABLERS_HPP
191