1 /* Traits for hashable types. 2 Copyright (C) 2014-2016 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 /* Helpful type for removing with delete. */ 42 43 template <typename Type> 44 struct typed_delete_remove 45 { 46 static inline void remove (Type *p); 47 }; 48 49 50 /* Remove with delete. */ 51 52 template <typename Type> 53 inline void 54 typed_delete_remove <Type>::remove (Type *p) 55 { 56 delete p; 57 } 58 59 /* Helpful type for a no-op remove. */ 60 61 template <typename Type> 62 struct typed_noop_remove 63 { 64 static inline void remove (Type &); 65 }; 66 67 68 /* Remove doing nothing. */ 69 70 template <typename Type> 71 inline void 72 typed_noop_remove <Type>::remove (Type &) 73 { 74 } 75 76 77 /* Hasher for integer type Type in which Empty is a spare value that can be 78 used to mark empty slots. If Deleted != Empty then Deleted is another 79 spare value that can be used for deleted slots; if Deleted == Empty then 80 hash table entries cannot be deleted. */ 81 82 template <typename Type, Type Empty, Type Deleted = Empty> 83 struct int_hash : typed_noop_remove <Type> 84 { 85 typedef Type value_type; 86 typedef Type compare_type; 87 88 static inline hashval_t hash (value_type); 89 static inline bool equal (value_type existing, value_type candidate); 90 static inline void mark_deleted (Type &); 91 static inline void mark_empty (Type &); 92 static inline bool is_deleted (Type); 93 static inline bool is_empty (Type); 94 }; 95 96 template <typename Type, Type Empty, Type Deleted> 97 inline hashval_t 98 int_hash <Type, Empty, Deleted>::hash (value_type x) 99 { 100 return x; 101 } 102 103 template <typename Type, Type Empty, Type Deleted> 104 inline bool 105 int_hash <Type, Empty, Deleted>::equal (value_type x, value_type y) 106 { 107 return x == y; 108 } 109 110 template <typename Type, Type Empty, Type Deleted> 111 inline void 112 int_hash <Type, Empty, Deleted>::mark_deleted (Type &x) 113 { 114 gcc_assert (Empty != Deleted); 115 x = Deleted; 116 } 117 118 template <typename Type, Type Empty, Type Deleted> 119 inline void 120 int_hash <Type, Empty, Deleted>::mark_empty (Type &x) 121 { 122 x = Empty; 123 } 124 125 template <typename Type, Type Empty, Type Deleted> 126 inline bool 127 int_hash <Type, Empty, Deleted>::is_deleted (Type x) 128 { 129 return Empty != Deleted && x == Deleted; 130 } 131 132 template <typename Type, Type Empty, Type Deleted> 133 inline bool 134 int_hash <Type, Empty, Deleted>::is_empty (Type x) 135 { 136 return x == Empty; 137 } 138 139 /* Pointer hasher based on pointer equality. Other types of pointer hash 140 can inherit this and override the hash and equal functions with some 141 other form of equality (such as string equality). */ 142 143 template <typename Type> 144 struct pointer_hash 145 { 146 typedef Type *value_type; 147 typedef Type *compare_type; 148 149 static inline hashval_t hash (const value_type &); 150 static inline bool equal (const value_type &existing, 151 const compare_type &candidate); 152 static inline void mark_deleted (Type *&); 153 static inline void mark_empty (Type *&); 154 static inline bool is_deleted (Type *); 155 static inline bool is_empty (Type *); 156 }; 157 158 template <typename Type> 159 inline hashval_t 160 pointer_hash <Type>::hash (const value_type &candidate) 161 { 162 /* This is a really poor hash function, but it is what the current code uses, 163 so I am reusing it to avoid an additional axis in testing. */ 164 return (hashval_t) ((intptr_t)candidate >> 3); 165 } 166 167 template <typename Type> 168 inline bool 169 pointer_hash <Type>::equal (const value_type &existing, 170 const compare_type &candidate) 171 { 172 return existing == candidate; 173 } 174 175 template <typename Type> 176 inline void 177 pointer_hash <Type>::mark_deleted (Type *&e) 178 { 179 e = reinterpret_cast<Type *> (1); 180 } 181 182 template <typename Type> 183 inline void 184 pointer_hash <Type>::mark_empty (Type *&e) 185 { 186 e = NULL; 187 } 188 189 template <typename Type> 190 inline bool 191 pointer_hash <Type>::is_deleted (Type *e) 192 { 193 return e == reinterpret_cast<Type *> (1); 194 } 195 196 template <typename Type> 197 inline bool 198 pointer_hash <Type>::is_empty (Type *e) 199 { 200 return e == NULL; 201 } 202 203 /* Hasher for "const char *" strings, using string rather than pointer 204 equality. */ 205 206 struct string_hash : pointer_hash <const char> 207 { 208 static inline hashval_t hash (const char *); 209 static inline bool equal (const char *, const char *); 210 }; 211 212 inline hashval_t 213 string_hash::hash (const char *id) 214 { 215 return htab_hash_string (id); 216 } 217 218 inline bool 219 string_hash::equal (const char *id1, const char *id2) 220 { 221 return strcmp (id1, id2) == 0; 222 } 223 224 /* Remover and marker for entries in gc memory. */ 225 226 template<typename T> 227 struct ggc_remove 228 { 229 static void remove (T &) {} 230 231 static void 232 ggc_mx (T &p) 233 { 234 extern void gt_ggc_mx (T &); 235 gt_ggc_mx (p); 236 } 237 238 static void 239 pch_nx (T &p) 240 { 241 extern void gt_pch_nx (T &); 242 gt_pch_nx (p); 243 } 244 245 static void 246 pch_nx (T &p, gt_pointer_operator op, void *cookie) 247 { 248 op (&p, cookie); 249 } 250 }; 251 252 /* Remover and marker for "cache" entries in gc memory. These entries can 253 be deleted if there are no non-cache references to the data. */ 254 255 template<typename T> 256 struct ggc_cache_remove : ggc_remove<T> 257 { 258 /* Entries are weakly held because this is for caches. */ 259 static void ggc_mx (T &) {} 260 261 static int 262 keep_cache_entry (T &e) 263 { 264 return ggc_marked_p (e) ? -1 : 0; 265 } 266 }; 267 268 /* Traits for pointer elements that should not be freed when an element 269 is deleted. */ 270 271 template <typename T> 272 struct nofree_ptr_hash : pointer_hash <T>, typed_noop_remove <T *> {}; 273 274 /* Traits for pointer elements that should be freed via free() when an 275 element is deleted. */ 276 277 template <typename T> 278 struct free_ptr_hash : pointer_hash <T>, typed_free_remove <T> {}; 279 280 /* Traits for pointer elements that should be freed via delete operand when an 281 element is deleted. */ 282 283 template <typename T> 284 struct delete_ptr_hash : pointer_hash <T>, typed_delete_remove <T> {}; 285 286 /* Traits for elements that point to gc memory. The pointed-to data 287 must be kept across collections. */ 288 289 template <typename T> 290 struct ggc_ptr_hash : pointer_hash <T>, ggc_remove <T *> {}; 291 292 /* Traits for elements that point to gc memory. The elements don't 293 in themselves keep the pointed-to data alive and they can be deleted 294 if the pointed-to data is going to be collected. */ 295 296 template <typename T> 297 struct ggc_cache_ptr_hash : pointer_hash <T>, ggc_cache_remove <T *> {}; 298 299 /* Traits for string elements that should not be freed when an element 300 is deleted. */ 301 302 struct nofree_string_hash : string_hash, typed_noop_remove <const char *> {}; 303 304 template <typename T> struct default_hash_traits : T {}; 305 306 template <typename T> 307 struct default_hash_traits <T *> : ggc_ptr_hash <T> {}; 308 309 #endif 310