gcc/hash-traits.h

   1 /* Traits for hashable types.
   2    Copyright (C) 2014-2015 Free Software Foundation, Inc.
   3
   4 This file is part of GCC.
   5
   6 GCC is free software; you can redistribute it and/or modify it under
   7 the terms of the GNU General Public License as published by the Free
   8 Software Foundation; either version 3, or (at your option) any later
   9 version.
  10
  11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14 for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GCC; see the file COPYING3.  If not see
  18 <http://www.gnu.org/licenses/>.  */
  19
  20 #ifndef hash_traits_h
  21 #define hash_traits_h
  22
  23 /* Helpful type for removing with free.  */
  24
  25 template <typename Type>
  26 struct typed_free_remove
  27 {
  28   static inline void remove (Type *p);
  29 };
  30
  31
  32 /* Remove with free.  */
  33
  34 template <typename Type>
  35 inline void
  36 typed_free_remove <Type>::remove (Type *p)
  37 {
  38   free (p);
  39 }
  40
  41
  42 /* Helpful type for a no-op remove.  */
  43
  44 template <typename Type>
  45 struct typed_noop_remove
  46 {
  47   static inline void remove (Type *p);
  48 };
  49
  50
  51 /* Remove doing nothing.  */
  52
  53 template <typename Type>
  54 inline void
  55 typed_noop_remove <Type>::remove (Type *p ATTRIBUTE_UNUSED)
  56 {
  57 }
  58
  59
  60 /* Pointer hash with a no-op remove method.  */
  61
  62 template <typename Type>
  63 struct pointer_hash : typed_noop_remove <Type>
  64 {
  65   typedef Type *value_type;
  66   typedef Type *compare_type;
  67
  68   static inline hashval_t hash (const value_type &);
  69
  70   static inline bool equal (const value_type &existing,
  71                             const compare_type &candidate);
  72 };
  73
  74 template <typename Type>
  75 inline hashval_t
  76 pointer_hash <Type>::hash (const value_type &candidate)
  77 {
  78   /* This is a really poor hash function, but it is what the current code uses,
  79      so I am reusing it to avoid an additional axis in testing.  */
  80   return (hashval_t) ((intptr_t)candidate >> 3);
  81 }
  82
  83 template <typename Type>
  84 inline bool
  85 pointer_hash <Type>::equal (const value_type &existing,
  86                            const compare_type &candidate)
  87 {
  88   return existing == candidate;
  89 }
  90
  91 /* Hasher for entry in gc memory.  */
  92
  93 template<typename T>
  94 struct ggc_hasher
  95 {
  96   typedef T value_type;
  97   typedef T compare_type;
  98
  99   static void remove (T) {}
 100
 101   static void
 102   ggc_mx (T p)
 103   {
 104     extern void gt_ggc_mx (T &);
 105     gt_ggc_mx (p);
 106   }
 107
 108   static void
 109   pch_nx (T &p)
 110   {
 111     extern void gt_pch_nx (T &);
 112     gt_pch_nx (p);
 113   }
 114
 115   static void
 116   pch_nx (T &p, gt_pointer_operator op, void *cookie)
 117   {
 118     op (&p, cookie);
 119   }
 120 };
 121
 122 /* Hasher for cache entry in gc memory.  */
 123
 124 template<typename T>
 125 struct ggc_cache_hasher
 126 {
 127   typedef T value_type;
 128   typedef T compare_type;
 129
 130   static void remove (T &) {}
 131
 132   /* Entries are weakly held because this is for caches.  */
 133
 134   static void ggc_mx (T &) {}
 135
 136   static void
 137   pch_nx (T &p)
 138   {
 139     extern void gt_pch_nx (T &);
 140     gt_pch_nx (p);
 141   }
 142
 143   static void
 144   pch_nx (T &p, gt_pointer_operator op, void *cookie)
 145   {
 146     op (&p, cookie);
 147   }
 148
 149   /* Clear out entries if they are about to be gc'd.  */
 150
 151   static void
 152   handle_cache_entry (T &e)
 153   {
 154     if (e != HTAB_EMPTY_ENTRY && e != HTAB_DELETED_ENTRY && !ggc_marked_p (e))
 155       e = static_cast<T> (HTAB_DELETED_ENTRY);
 156   }
 157 };
 158
 159 #endif