1 /* String pool for GCC.
2 Copyright (C) 2000-2015 Free Software Foundation, Inc.
4 This file is part of GCC.
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
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
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/>. */
20 /* String text, identifier text and identifier node allocator.
21 Identifiers are uniquely stored in a hash table.
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
30 #include "coretypes.h"
32 #include "ggc-internal.h"
36 #include "double-int.h"
46 /* The "" allocated string. */
47 const char empty_string[] = "";
49 /* Character strings, each containing a single decimal digit.
50 Written this way to save space. */
51 static const char digit_vector[] = {
52 '0', 0, '1', 0, '2', 0, '3', 0, '4', 0,
53 '5', 0, '6', 0, '7', 0, '8', 0, '9', 0
56 #define digit_string(d) (digit_vector + ((d) * 2))
58 struct ht *ident_hash;
60 static hashnode alloc_node (cpp_hash_table *);
61 static int mark_ident (struct cpp_reader *, hashnode, const void *);
64 stringpool_ggc_alloc (size_t x)
66 return ggc_alloc_atomic (x);
69 /* Initialize the string pool. */
71 init_stringpool (void)
73 /* Clean up if we're called more than once.
74 (We can't make this idempotent since identifiers contain state) */
76 ht_destroy (ident_hash);
78 /* Create with 16K (2^14) entries. */
79 ident_hash = ht_create (14);
80 ident_hash->alloc_node = alloc_node;
81 ident_hash->alloc_subobject = stringpool_ggc_alloc;
84 /* Allocate a hash node. */
86 alloc_node (cpp_hash_table *table ATTRIBUTE_UNUSED)
88 return GCC_IDENT_TO_HT_IDENT (make_node (IDENTIFIER_NODE));
91 /* Allocate and return a string constant of length LENGTH, containing
92 CONTENTS. If LENGTH is -1, CONTENTS is assumed to be a
93 nul-terminated string, and the length is calculated using strlen. */
96 ggc_alloc_string (const char *contents, int length MEM_STAT_DECL)
101 length = strlen (contents);
105 if (length == 1 && ISDIGIT (contents[0]))
106 return digit_string (contents[0] - '0');
108 result = (char *) ggc_internal_cleared_alloc (length + 1 PASS_MEM_STAT);
109 memcpy (result, contents, length);
110 result[length] = '\0';
111 return (const char *) result;
114 /* Return an IDENTIFIER_NODE whose name is TEXT (a null-terminated string).
115 If an identifier with that name has previously been referred to,
116 the same node is returned this time. */
118 #undef get_identifier
121 get_identifier (const char *text)
123 hashnode ht_node = ht_lookup (ident_hash,
124 (const unsigned char *) text,
125 strlen (text), HT_ALLOC);
127 /* ht_node can't be NULL here. */
128 return HT_IDENT_TO_GCC_IDENT (ht_node);
131 /* Identical to get_identifier, except that the length is assumed
135 get_identifier_with_length (const char *text, size_t length)
137 hashnode ht_node = ht_lookup (ident_hash,
138 (const unsigned char *) text,
141 /* ht_node can't be NULL here. */
142 return HT_IDENT_TO_GCC_IDENT (ht_node);
145 /* If an identifier with the name TEXT (a null-terminated string) has
146 previously been referred to, return that node; otherwise return
150 maybe_get_identifier (const char *text)
154 ht_node = ht_lookup (ident_hash, (const unsigned char *) text,
155 strlen (text), HT_NO_INSERT);
157 return HT_IDENT_TO_GCC_IDENT (ht_node);
162 /* Report some basic statistics about the string pool. */
165 stringpool_statistics (void)
167 ht_dump_statistics (ident_hash);
170 /* Mark an identifier for GC. */
173 mark_ident (struct cpp_reader *pfile ATTRIBUTE_UNUSED, hashnode h,
174 const void *v ATTRIBUTE_UNUSED)
176 gt_ggc_m_9tree_node (HT_IDENT_TO_GCC_IDENT (h));
180 /* Return true if an identifier should be removed from the table. */
183 maybe_delete_ident (struct cpp_reader *pfile ATTRIBUTE_UNUSED, hashnode h,
184 const void *v ATTRIBUTE_UNUSED)
186 return !ggc_marked_p (HT_IDENT_TO_GCC_IDENT (h));
189 /* Mark the trees hanging off the identifier node for GGC. These are
190 handled specially (not using gengtype) because identifiers are only
191 roots during one part of compilation. */
194 ggc_mark_stringpool (void)
196 ht_forall (ident_hash, mark_ident, NULL);
199 /* Purge the identifier hash of identifiers which are no longer
203 ggc_purge_stringpool (void)
205 ht_purge (ident_hash, maybe_delete_ident, NULL);
208 /* Pointer-walking routine for strings (not very interesting, since
209 strings don't contain pointers). */
212 gt_pch_p_S (void *obj ATTRIBUTE_UNUSED, void *x ATTRIBUTE_UNUSED,
213 gt_pointer_operator op ATTRIBUTE_UNUSED,
214 void *cookie ATTRIBUTE_UNUSED)
218 /* PCH pointer-walking routine for strings. */
221 gt_pch_n_S (const void *x)
223 gt_pch_note_object (CONST_CAST (void *, x), CONST_CAST (void *, x),
228 /* User-callable entry point for marking string X. */
231 gt_pch_nx (const char *& x)
237 gt_pch_nx (unsigned char *& x)
243 gt_pch_nx (unsigned char& x ATTRIBUTE_UNUSED)
248 gt_pch_nx (unsigned char *x, gt_pointer_operator op, void *cookie)
253 /* Handle saving and restoring the string pool for PCH. */
255 /* SPD is saved in the PCH file and holds the information needed
256 to restore the string pool. */
258 struct GTY(()) string_pool_data {
260 GTY((length ("%h.nslots"),
261 nested_ptr (union tree_node, "%h ? GCC_IDENT_TO_HT_IDENT (%h) : NULL",
262 "%h ? HT_IDENT_TO_GCC_IDENT (%h) : NULL")))
265 unsigned int nelements;
268 static GTY(()) struct string_pool_data * spd;
270 /* Save the stringpool data in SPD. */
273 gt_pch_save_stringpool (void)
275 spd = ggc_alloc<string_pool_data> ();
276 spd->nslots = ident_hash->nslots;
277 spd->nelements = ident_hash->nelements;
278 spd->entries = ggc_vec_alloc<ht_identifier_ptr> (spd->nslots);
279 memcpy (spd->entries, ident_hash->entries,
280 spd->nslots * sizeof (spd->entries[0]));
283 /* Return the stringpool to its state before gt_pch_save_stringpool
287 gt_pch_fixup_stringpool (void)
291 /* A PCH file has been restored, which loaded SPD; fill the real hash table
295 gt_pch_restore_stringpool (void)
297 ht_load (ident_hash, spd->entries, spd->nslots, spd->nelements, false);
301 #include "gt-stringpool.h"