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   static inline bool equal (const value_type &existing,
  70                             const compare_type &candidate);
  71   static inline void mark_deleted (Type *&);
  72   static inline void mark_empty (Type *&);
  73   static inline bool is_deleted (Type *);
  74   static inline bool is_empty (Type *);
  75 };
  76
  77 template <typename Type>
  78 inline hashval_t
  79 pointer_hash <Type>::hash (const value_type &candidate)
  80 {
  81   /* This is a really poor hash function, but it is what the current code uses,
  82      so I am reusing it to avoid an additional axis in testing.  */
  83   return (hashval_t) ((intptr_t)candidate >> 3);
  84 }
  85
  86 template <typename Type>
  87 inline bool
  88 pointer_hash <Type>::equal (const value_type &existing,
  89                            const compare_type &candidate)
  90 {
  91   return existing == candidate;
  92 }
  93
  94 template <typename Type>
  95 inline void
  96 pointer_hash <Type>::mark_deleted (Type *&e)
  97 {
  98   e = reinterpret_cast<Type *> (1);
  99 }
 100
 101 template <typename Type>
 102 inline void
 103 pointer_hash <Type>::mark_empty (Type *&e)
 104 {
 105   e = NULL;
 106 }
 107
 108 template <typename Type>
 109 inline bool
 110 pointer_hash <Type>::is_deleted (Type *e)
 111 {
 112   return e == reinterpret_cast<Type *> (1);
 113 }
 114
 115 template <typename Type>
 116 inline bool
 117 pointer_hash <Type>::is_empty (Type *e)
 118 {
 119   return e == NULL;
 120 }
 121
 122 /* Hasher for entry in gc memory.  */
 123
 124 template<typename T>
 125 struct ggc_hasher
 126 {
 127   typedef T value_type;
 128   typedef T compare_type;
 129
 130   static void remove (T &) {}
 131
 132   static void
 133   ggc_mx (T &p)
 134   {
 135     extern void gt_ggc_mx (T &);
 136     gt_ggc_mx (p);
 137   }
 138
 139   static void
 140   pch_nx (T &p)
 141   {
 142     extern void gt_pch_nx (T &);
 143     gt_pch_nx (p);
 144   }
 145
 146   static void
 147   pch_nx (T &p, gt_pointer_operator op, void *cookie)
 148   {
 149     op (&p, cookie);
 150   }
 151 };
 152
 153 /* Hasher for cache entry in gc memory.  */
 154
 155 template<typename T>
 156 struct ggc_cache_hasher : ggc_hasher<T>
 157 {
 158   /* Entries are weakly held because this is for caches.  */
 159   static void ggc_mx (T &) {}
 160
 161   static int
 162   keep_cache_entry (T &e)
 163   {
 164     return ggc_marked_p (e) ? -1 : 0;
 165   }
 166 };
 167
 168 #endif