/cp
[official-gcc.git] / gcc / stringpool.c
blob291d355992a5e6d40be147cf9d05fa7786e9b67b
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
9 version.
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.
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
26 is faster. */
28 #include "config.h"
29 #include "system.h"
30 #include "coretypes.h"
31 #include "ggc-internal.h"
32 #include "alias.h"
33 #include "tree.h"
34 #include "options.h"
35 #include "cpplib.h"
37 /* The "" allocated string. */
38 const char empty_string[] = "";
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
47 #define digit_string(d) (digit_vector + ((d) * 2))
49 struct ht *ident_hash;
51 static hashnode alloc_node (cpp_hash_table *);
52 static int mark_ident (struct cpp_reader *, hashnode, const void *);
54 static void *
55 stringpool_ggc_alloc (size_t x)
57 return ggc_alloc_atomic (x);
60 /* Initialize the string pool. */
61 void
62 init_stringpool (void)
64 /* Clean up if we're called more than once.
65 (We can't make this idempotent since identifiers contain state) */
66 if (ident_hash)
67 ht_destroy (ident_hash);
69 /* Create with 16K (2^14) entries. */
70 ident_hash = ht_create (14);
71 ident_hash->alloc_node = alloc_node;
72 ident_hash->alloc_subobject = stringpool_ggc_alloc;
75 /* Allocate a hash node. */
76 static hashnode
77 alloc_node (cpp_hash_table *table ATTRIBUTE_UNUSED)
79 return GCC_IDENT_TO_HT_IDENT (make_node (IDENTIFIER_NODE));
82 /* Allocate and return a string constant of length LENGTH, containing
83 CONTENTS. If LENGTH is -1, CONTENTS is assumed to be a
84 nul-terminated string, and the length is calculated using strlen. */
86 const char *
87 ggc_alloc_string (const char *contents, int length MEM_STAT_DECL)
89 char *result;
91 if (length == -1)
92 length = strlen (contents);
94 if (length == 0)
95 return empty_string;
96 if (length == 1 && ISDIGIT (contents[0]))
97 return digit_string (contents[0] - '0');
99 result = (char *) ggc_internal_cleared_alloc (length + 1 PASS_MEM_STAT);
100 memcpy (result, contents, length);
101 result[length] = '\0';
102 return (const char *) result;
105 /* Return an IDENTIFIER_NODE whose name is TEXT (a null-terminated string).
106 If an identifier with that name has previously been referred to,
107 the same node is returned this time. */
109 #undef get_identifier
111 tree
112 get_identifier (const char *text)
114 hashnode ht_node = ht_lookup (ident_hash,
115 (const unsigned char *) text,
116 strlen (text), HT_ALLOC);
118 /* ht_node can't be NULL here. */
119 return HT_IDENT_TO_GCC_IDENT (ht_node);
122 /* Identical to get_identifier, except that the length is assumed
123 known. */
125 tree
126 get_identifier_with_length (const char *text, size_t length)
128 hashnode ht_node = ht_lookup (ident_hash,
129 (const unsigned char *) text,
130 length, HT_ALLOC);
132 /* ht_node can't be NULL here. */
133 return HT_IDENT_TO_GCC_IDENT (ht_node);
136 /* If an identifier with the name TEXT (a null-terminated string) has
137 previously been referred to, return that node; otherwise return
138 NULL_TREE. */
140 tree
141 maybe_get_identifier (const char *text)
143 hashnode ht_node;
145 ht_node = ht_lookup (ident_hash, (const unsigned char *) text,
146 strlen (text), HT_NO_INSERT);
147 if (ht_node)
148 return HT_IDENT_TO_GCC_IDENT (ht_node);
150 return NULL_TREE;
153 /* Report some basic statistics about the string pool. */
155 void
156 stringpool_statistics (void)
158 ht_dump_statistics (ident_hash);
161 /* Mark an identifier for GC. */
163 static int
164 mark_ident (struct cpp_reader *pfile ATTRIBUTE_UNUSED, hashnode h,
165 const void *v ATTRIBUTE_UNUSED)
167 gt_ggc_m_9tree_node (HT_IDENT_TO_GCC_IDENT (h));
168 return 1;
171 /* Return true if an identifier should be removed from the table. */
173 static int
174 maybe_delete_ident (struct cpp_reader *pfile ATTRIBUTE_UNUSED, hashnode h,
175 const void *v ATTRIBUTE_UNUSED)
177 return !ggc_marked_p (HT_IDENT_TO_GCC_IDENT (h));
180 /* Mark the trees hanging off the identifier node for GGC. These are
181 handled specially (not using gengtype) because identifiers are only
182 roots during one part of compilation. */
184 void
185 ggc_mark_stringpool (void)
187 ht_forall (ident_hash, mark_ident, NULL);
190 /* Purge the identifier hash of identifiers which are no longer
191 referenced. */
193 void
194 ggc_purge_stringpool (void)
196 ht_purge (ident_hash, maybe_delete_ident, NULL);
199 /* Pointer-walking routine for strings (not very interesting, since
200 strings don't contain pointers). */
202 void
203 gt_pch_p_S (void *obj ATTRIBUTE_UNUSED, void *x ATTRIBUTE_UNUSED,
204 gt_pointer_operator op ATTRIBUTE_UNUSED,
205 void *cookie ATTRIBUTE_UNUSED)
209 /* PCH pointer-walking routine for strings. */
211 void
212 gt_pch_n_S (const void *x)
214 gt_pch_note_object (CONST_CAST (void *, x), CONST_CAST (void *, x),
215 &gt_pch_p_S);
219 /* User-callable entry point for marking string X. */
221 void
222 gt_pch_nx (const char *& x)
224 gt_pch_n_S (x);
227 void
228 gt_pch_nx (unsigned char *& x)
230 gt_pch_n_S (x);
233 void
234 gt_pch_nx (unsigned char& x ATTRIBUTE_UNUSED)
238 void
239 gt_pch_nx (unsigned char *x, gt_pointer_operator op, void *cookie)
241 op (x, cookie);
244 /* Handle saving and restoring the string pool for PCH. */
246 /* SPD is saved in the PCH file and holds the information needed
247 to restore the string pool. */
249 struct GTY(()) string_pool_data {
250 ht_identifier_ptr *
251 GTY((length ("%h.nslots"),
252 nested_ptr (union tree_node, "%h ? GCC_IDENT_TO_HT_IDENT (%h) : NULL",
253 "%h ? HT_IDENT_TO_GCC_IDENT (%h) : NULL")))
254 entries;
255 unsigned int nslots;
256 unsigned int nelements;
259 static GTY(()) struct string_pool_data * spd;
261 /* Save the stringpool data in SPD. */
263 void
264 gt_pch_save_stringpool (void)
266 spd = ggc_alloc<string_pool_data> ();
267 spd->nslots = ident_hash->nslots;
268 spd->nelements = ident_hash->nelements;
269 spd->entries = ggc_vec_alloc<ht_identifier_ptr> (spd->nslots);
270 memcpy (spd->entries, ident_hash->entries,
271 spd->nslots * sizeof (spd->entries[0]));
274 /* Return the stringpool to its state before gt_pch_save_stringpool
275 was called. */
277 void
278 gt_pch_fixup_stringpool (void)
282 /* A PCH file has been restored, which loaded SPD; fill the real hash table
283 from SPD. */
285 void
286 gt_pch_restore_stringpool (void)
288 ht_load (ident_hash, spd->entries, spd->nslots, spd->nelements, false);
289 spd = NULL;
292 #include "gt-stringpool.h"