1 /* String pool for GCC. 2 Copyright (C) 2000-2018 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 "tree.h" 32 33 struct ht *ident_hash; 34 35 static hashnode alloc_node (cpp_hash_table *); 36 static int mark_ident (struct cpp_reader *, hashnode, const void *); 37 38 static void * 39 stringpool_ggc_alloc (size_t x) 40 { 41 return ggc_alloc_atomic (x); 42 } 43 44 /* Initialize the string pool. */ 45 void 46 init_stringpool (void) 47 { 48 /* Clean up if we're called more than once. 49 (We can't make this idempotent since identifiers contain state) */ 50 if (ident_hash) 51 ht_destroy (ident_hash); 52 53 /* Create with 16K (2^14) entries. */ 54 ident_hash = ht_create (14); 55 ident_hash->alloc_node = alloc_node; 56 ident_hash->alloc_subobject = stringpool_ggc_alloc; 57 } 58 59 /* Allocate a hash node. */ 60 static hashnode 61 alloc_node (cpp_hash_table *table ATTRIBUTE_UNUSED) 62 { 63 return GCC_IDENT_TO_HT_IDENT (make_node (IDENTIFIER_NODE)); 64 } 65 66 /* Allocate and return a string constant of length LENGTH, containing 67 CONTENTS. If LENGTH is -1, CONTENTS is assumed to be a 68 nul-terminated string, and the length is calculated using strlen. */ 69 70 const char * 71 ggc_alloc_string (const char *contents, int length MEM_STAT_DECL) 72 { 73 if (length == -1) 74 length = strlen (contents); 75 76 if (!length) 77 return ""; 78 79 char *result = (char *) ggc_alloc_atomic (length + 1); 80 memcpy (result, contents, length); 81 result[length] = '\0'; 82 83 return (const char *) result; 84 } 85 86 /* Return an IDENTIFIER_NODE whose name is TEXT (a null-terminated string). 87 If an identifier with that name has previously been referred to, 88 the same node is returned this time. */ 89 90 #undef get_identifier 91 92 tree 93 get_identifier (const char *text) 94 { 95 hashnode ht_node = ht_lookup (ident_hash, 96 (const unsigned char *) text, 97 strlen (text), HT_ALLOC); 98 99 /* ht_node can't be NULL here. */ 100 return HT_IDENT_TO_GCC_IDENT (ht_node); 101 } 102 103 /* Identical to get_identifier, except that the length is assumed 104 known. */ 105 106 tree 107 get_identifier_with_length (const char *text, size_t length) 108 { 109 hashnode ht_node = ht_lookup (ident_hash, 110 (const unsigned char *) text, 111 length, HT_ALLOC); 112 113 /* ht_node can't be NULL here. */ 114 return HT_IDENT_TO_GCC_IDENT (ht_node); 115 } 116 117 /* If an identifier with the name TEXT (a null-terminated string) has 118 previously been referred to, return that node; otherwise return 119 NULL_TREE. */ 120 121 tree 122 maybe_get_identifier (const char *text) 123 { 124 hashnode ht_node; 125 126 ht_node = ht_lookup (ident_hash, (const unsigned char *) text, 127 strlen (text), HT_NO_INSERT); 128 if (ht_node) 129 return HT_IDENT_TO_GCC_IDENT (ht_node); 130 131 return NULL_TREE; 132 } 133 134 /* Report some basic statistics about the string pool. */ 135 136 void 137 stringpool_statistics (void) 138 { 139 ht_dump_statistics (ident_hash); 140 } 141 142 /* Mark an identifier for GC. */ 143 144 static int 145 mark_ident (struct cpp_reader *pfile ATTRIBUTE_UNUSED, hashnode h, 146 const void *v ATTRIBUTE_UNUSED) 147 { 148 gt_ggc_m_9tree_node (HT_IDENT_TO_GCC_IDENT (h)); 149 return 1; 150 } 151 152 /* Return true if an identifier should be removed from the table. */ 153 154 static int 155 maybe_delete_ident (struct cpp_reader *pfile ATTRIBUTE_UNUSED, hashnode h, 156 const void *v ATTRIBUTE_UNUSED) 157 { 158 return !ggc_marked_p (HT_IDENT_TO_GCC_IDENT (h)); 159 } 160 161 /* Mark the trees hanging off the identifier node for GGC. These are 162 handled specially (not using gengtype) because identifiers are only 163 roots during one part of compilation. */ 164 165 void 166 ggc_mark_stringpool (void) 167 { 168 ht_forall (ident_hash, mark_ident, NULL); 169 } 170 171 /* Purge the identifier hash of identifiers which are no longer 172 referenced. */ 173 174 void 175 ggc_purge_stringpool (void) 176 { 177 ht_purge (ident_hash, maybe_delete_ident, NULL); 178 } 179 180 /* Pointer-walking routine for strings (not very interesting, since 181 strings don't contain pointers). */ 182 183 void 184 gt_pch_p_S (void *obj ATTRIBUTE_UNUSED, void *x ATTRIBUTE_UNUSED, 185 gt_pointer_operator op ATTRIBUTE_UNUSED, 186 void *cookie ATTRIBUTE_UNUSED) 187 { 188 } 189 190 /* PCH pointer-walking routine for strings. */ 191 192 void 193 gt_pch_n_S (const void *x) 194 { 195 gt_pch_note_object (CONST_CAST (void *, x), CONST_CAST (void *, x), 196 >_pch_p_S); 197 } 198 199 200 /* User-callable entry point for marking string X. */ 201 202 void 203 gt_pch_nx (const char *& x) 204 { 205 gt_pch_n_S (x); 206 } 207 208 void 209 gt_pch_nx (unsigned char *& x) 210 { 211 gt_pch_n_S (x); 212 } 213 214 void 215 gt_pch_nx (unsigned char& x ATTRIBUTE_UNUSED) 216 { 217 } 218 219 void 220 gt_pch_nx (unsigned char *x, gt_pointer_operator op, void *cookie) 221 { 222 op (x, cookie); 223 } 224 225 /* Handle saving and restoring the string pool for PCH. */ 226 227 /* SPD is saved in the PCH file and holds the information needed 228 to restore the string pool. */ 229 230 struct GTY(()) string_pool_data { 231 ht_identifier_ptr * 232 GTY((length ("%h.nslots"), 233 nested_ptr (union tree_node, "%h ? GCC_IDENT_TO_HT_IDENT (%h) : NULL", 234 "%h ? HT_IDENT_TO_GCC_IDENT (%h) : NULL"))) 235 entries; 236 unsigned int nslots; 237 unsigned int nelements; 238 }; 239 240 static GTY(()) struct string_pool_data * spd; 241 242 /* Save the stringpool data in SPD. */ 243 244 void 245 gt_pch_save_stringpool (void) 246 { 247 spd = ggc_alloc<string_pool_data> (); 248 spd->nslots = ident_hash->nslots; 249 spd->nelements = ident_hash->nelements; 250 spd->entries = ggc_vec_alloc<ht_identifier_ptr> (spd->nslots); 251 memcpy (spd->entries, ident_hash->entries, 252 spd->nslots * sizeof (spd->entries[0])); 253 } 254 255 /* Return the stringpool to its state before gt_pch_save_stringpool 256 was called. */ 257 258 void 259 gt_pch_fixup_stringpool (void) 260 { 261 } 262 263 /* A PCH file has been restored, which loaded SPD; fill the real hash table 264 from SPD. */ 265 266 void 267 gt_pch_restore_stringpool (void) 268 { 269 ht_load (ident_hash, spd->entries, spd->nslots, spd->nelements, false); 270 spd = NULL; 271 } 272 273 #include "gt-stringpool.h" 274