1 /* String pool for GCC. 2 Copyright (C) 2000-2013 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 /* String text, identifier text and identifier node allocator. 21 Identifiers are uniquely stored in a hash table. 22 23 We use cpplib's hash table implementation. libiberty's 24 hashtab.c is not used because it requires 100% average space 25 overhead per string, which is unacceptable. Also, this algorithm 26 is faster. */ 27 28 #include "config.h" 29 #include "system.h" 30 #include "coretypes.h" 31 #include "ggc.h" 32 #include "ggc-internal.h" 33 #include "tree.h" 34 #include "symtab.h" 35 #include "cpplib.h" 36 37 /* The "" allocated string. */ 38 const char empty_string[] = ""; 39 40 /* Character strings, each containing a single decimal digit. 41 Written this way to save space. */ 42 static const char digit_vector[] = { 43 '0', 0, '1', 0, '2', 0, '3', 0, '4', 0, 44 '5', 0, '6', 0, '7', 0, '8', 0, '9', 0 45 }; 46 47 #define digit_string(d) (digit_vector + ((d) * 2)) 48 49 struct ht *ident_hash; 50 51 static hashnode alloc_node (cpp_hash_table *); 52 static int mark_ident (struct cpp_reader *, hashnode, const void *); 53 54 static void * 55 stringpool_ggc_alloc (size_t x) 56 { 57 return ggc_alloc_atomic (x); 58 } 59 60 /* Initialize the string pool. */ 61 void 62 init_stringpool (void) 63 { 64 /* Create with 16K (2^14) entries. */ 65 ident_hash = ht_create (14); 66 ident_hash->alloc_node = alloc_node; 67 ident_hash->alloc_subobject = stringpool_ggc_alloc; 68 } 69 70 /* Allocate a hash node. */ 71 static hashnode 72 alloc_node (cpp_hash_table *table ATTRIBUTE_UNUSED) 73 { 74 return GCC_IDENT_TO_HT_IDENT (make_node (IDENTIFIER_NODE)); 75 } 76 77 /* Allocate and return a string constant of length LENGTH, containing 78 CONTENTS. If LENGTH is -1, CONTENTS is assumed to be a 79 nul-terminated string, and the length is calculated using strlen. */ 80 81 const char * 82 ggc_alloc_string_stat (const char *contents, int length MEM_STAT_DECL) 83 { 84 char *result; 85 86 if (length == -1) 87 length = strlen (contents); 88 89 if (length == 0) 90 return empty_string; 91 if (length == 1 && ISDIGIT (contents[0])) 92 return digit_string (contents[0] - '0'); 93 94 result = (char *) ggc_alloc_atomic_stat (length + 1 PASS_MEM_STAT); 95 memcpy (result, contents, length); 96 result[length] = '\0'; 97 return (const char *) result; 98 } 99 100 /* Return an IDENTIFIER_NODE whose name is TEXT (a null-terminated string). 101 If an identifier with that name has previously been referred to, 102 the same node is returned this time. */ 103 104 #undef get_identifier 105 106 tree 107 get_identifier (const char *text) 108 { 109 hashnode ht_node = ht_lookup (ident_hash, 110 (const unsigned char *) text, 111 strlen (text), HT_ALLOC); 112 113 /* ht_node can't be NULL here. */ 114 return HT_IDENT_TO_GCC_IDENT (ht_node); 115 } 116 117 /* Identical to get_identifier, except that the length is assumed 118 known. */ 119 120 tree 121 get_identifier_with_length (const char *text, size_t length) 122 { 123 hashnode ht_node = ht_lookup (ident_hash, 124 (const unsigned char *) text, 125 length, HT_ALLOC); 126 127 /* ht_node can't be NULL here. */ 128 return HT_IDENT_TO_GCC_IDENT (ht_node); 129 } 130 131 /* If an identifier with the name TEXT (a null-terminated string) has 132 previously been referred to, return that node; otherwise return 133 NULL_TREE. */ 134 135 tree 136 maybe_get_identifier (const char *text) 137 { 138 hashnode ht_node; 139 140 ht_node = ht_lookup (ident_hash, (const unsigned char *) text, 141 strlen (text), HT_NO_INSERT); 142 if (ht_node) 143 return HT_IDENT_TO_GCC_IDENT (ht_node); 144 145 return NULL_TREE; 146 } 147 148 /* Report some basic statistics about the string pool. */ 149 150 void 151 stringpool_statistics (void) 152 { 153 ht_dump_statistics (ident_hash); 154 } 155 156 /* Mark an identifier for GC. */ 157 158 static int 159 mark_ident (struct cpp_reader *pfile ATTRIBUTE_UNUSED, hashnode h, 160 const void *v ATTRIBUTE_UNUSED) 161 { 162 gt_ggc_m_9tree_node (HT_IDENT_TO_GCC_IDENT (h)); 163 return 1; 164 } 165 166 /* Return true if an identifier should be removed from the table. */ 167 168 static int 169 maybe_delete_ident (struct cpp_reader *pfile ATTRIBUTE_UNUSED, hashnode h, 170 const void *v ATTRIBUTE_UNUSED) 171 { 172 return !ggc_marked_p (HT_IDENT_TO_GCC_IDENT (h)); 173 } 174 175 /* Mark the trees hanging off the identifier node for GGC. These are 176 handled specially (not using gengtype) because identifiers are only 177 roots during one part of compilation. */ 178 179 void 180 ggc_mark_stringpool (void) 181 { 182 ht_forall (ident_hash, mark_ident, NULL); 183 } 184 185 /* Purge the identifier hash of identifiers which are no longer 186 referenced. */ 187 188 void 189 ggc_purge_stringpool (void) 190 { 191 ht_purge (ident_hash, maybe_delete_ident, NULL); 192 } 193 194 /* Pointer-walking routine for strings (not very interesting, since 195 strings don't contain pointers). */ 196 197 void 198 gt_pch_p_S (void *obj ATTRIBUTE_UNUSED, void *x ATTRIBUTE_UNUSED, 199 gt_pointer_operator op ATTRIBUTE_UNUSED, 200 void *cookie ATTRIBUTE_UNUSED) 201 { 202 } 203 204 /* PCH pointer-walking routine for strings. */ 205 206 void 207 gt_pch_n_S (const void *x) 208 { 209 gt_pch_note_object (CONST_CAST (void *, x), CONST_CAST (void *, x), 210 >_pch_p_S); 211 } 212 213 214 /* User-callable entry point for marking string X. */ 215 216 void 217 gt_pch_nx (const char *& x) 218 { 219 gt_pch_n_S (x); 220 } 221 222 void 223 gt_pch_nx (unsigned char *& x) 224 { 225 gt_pch_n_S (x); 226 } 227 228 void 229 gt_pch_nx (unsigned char& x ATTRIBUTE_UNUSED) 230 { 231 } 232 233 void 234 gt_pch_nx (unsigned char *x, gt_pointer_operator op, void *cookie) 235 { 236 op (x, cookie); 237 } 238 239 /* Handle saving and restoring the string pool for PCH. */ 240 241 /* SPD is saved in the PCH file and holds the information needed 242 to restore the string pool. */ 243 244 struct GTY(()) string_pool_data { 245 ht_identifier_ptr * 246 GTY((length ("%h.nslots"), 247 nested_ptr (union tree_node, "%h ? GCC_IDENT_TO_HT_IDENT (%h) : NULL", 248 "%h ? HT_IDENT_TO_GCC_IDENT (%h) : NULL"))) 249 entries; 250 unsigned int nslots; 251 unsigned int nelements; 252 }; 253 254 static GTY(()) struct string_pool_data * spd; 255 256 /* Save the stringpool data in SPD. */ 257 258 void 259 gt_pch_save_stringpool (void) 260 { 261 spd = ggc_alloc_string_pool_data (); 262 spd->nslots = ident_hash->nslots; 263 spd->nelements = ident_hash->nelements; 264 spd->entries = ggc_alloc_vec_ht_identifier_ptr (spd->nslots); 265 memcpy (spd->entries, ident_hash->entries, 266 spd->nslots * sizeof (spd->entries[0])); 267 } 268 269 /* Return the stringpool to its state before gt_pch_save_stringpool 270 was called. */ 271 272 void 273 gt_pch_fixup_stringpool (void) 274 { 275 } 276 277 /* A PCH file has been restored, which loaded SPD; fill the real hash table 278 from SPD. */ 279 280 void 281 gt_pch_restore_stringpool (void) 282 { 283 ht_load (ident_hash, spd->entries, spd->nslots, spd->nelements, false); 284 spd = NULL; 285 } 286 287 #include "gt-stringpool.h" 288