1 /* String pool for GCC.
2 Copyright (C) 2000, 2001, 2002, 2003 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 2, 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 COPYING. If not, write to the Free
18 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
21 /* String text, identifier text and identifier node allocator. Strings
22 allocated by ggc_alloc_string are stored in an obstack which is
23 never shrunk. Identifiers are uniquely stored in a hash table.
25 We have our own private hash table implementation. libiberty's
26 hashtab.c is not used because it requires 100% average space
27 overhead per string, which is unacceptable. Also, this algorithm
32 #include "coretypes.h"
36 #include "hashtable.h"
39 /* The "" allocated string. */
40 const char empty_string[] = "";
42 /* Character strings, each containing a single decimal digit.
43 Written this way to save space. */
44 const char digit_vector[] = {
45 '0', 0, '1', 0, '2', 0, '3', 0, '4', 0,
46 '5', 0, '6', 0, '7', 0, '8', 0, '9', 0
49 struct ht *ident_hash;
50 static struct obstack string_stack;
52 static hashnode alloc_node (hash_table *);
53 static int mark_ident (struct cpp_reader *, hashnode, const void *);
54 static int ht_copy_and_clear (struct cpp_reader *, hashnode, const void *);
56 /* Initialize the string pool. */
58 init_stringpool (void)
60 /* Create with 16K (2^14) entries. */
61 ident_hash = ht_create (14);
62 ident_hash->alloc_node = alloc_node;
63 gcc_obstack_init (&string_stack);
66 /* Allocate a hash node. */
68 alloc_node (hash_table *table ATTRIBUTE_UNUSED)
70 return GCC_IDENT_TO_HT_IDENT (make_node (IDENTIFIER_NODE));
73 /* Allocate and return a string constant of length LENGTH, containing
74 CONTENTS. If LENGTH is -1, CONTENTS is assumed to be a
75 nul-terminated string, and the length is calculated using strlen.
76 If the same string constant has been allocated before, that copy is
77 returned this time too. */
80 ggc_alloc_string (const char *contents, int length)
83 length = strlen (contents);
87 if (length == 1 && ISDIGIT (contents[0]))
88 return digit_string (contents[0] - '0');
90 obstack_grow0 (&string_stack, contents, length);
91 return obstack_finish (&string_stack);
94 /* Return an IDENTIFIER_NODE whose name is TEXT (a null-terminated string).
95 If an identifier with that name has previously been referred to,
96 the same node is returned this time. */
101 get_identifier (const char *text)
103 hashnode ht_node = ht_lookup (ident_hash,
104 (const unsigned char *) text,
105 strlen (text), HT_ALLOC);
107 /* ht_node can't be NULL here. */
108 return HT_IDENT_TO_GCC_IDENT (ht_node);
111 /* Identical to get_identifier, except that the length is assumed
115 get_identifier_with_length (const char *text, size_t length)
117 hashnode ht_node = ht_lookup (ident_hash,
118 (const unsigned char *) text,
121 /* ht_node can't be NULL here. */
122 return HT_IDENT_TO_GCC_IDENT (ht_node);
125 /* If an identifier with the name TEXT (a null-terminated string) has
126 previously been referred to, return that node; otherwise return
130 maybe_get_identifier (const char *text)
134 ht_node = ht_lookup (ident_hash, (const unsigned char *) text,
135 strlen (text), HT_NO_INSERT);
137 return HT_IDENT_TO_GCC_IDENT (ht_node);
142 /* Report some basic statistics about the string pool. */
145 stringpool_statistics (void)
147 ht_dump_statistics (ident_hash);
150 /* Mark an identifier for GC. */
153 mark_ident (struct cpp_reader *pfile ATTRIBUTE_UNUSED, hashnode h,
154 const void *v ATTRIBUTE_UNUSED)
156 gt_ggc_m_9tree_node (HT_IDENT_TO_GCC_IDENT (h));
160 /* Mark the trees hanging off the identifier node for GGC. These are
161 handled specially (not using gengtype) because of the special
162 treatment for strings. */
165 ggc_mark_stringpool (void)
167 ht_forall (ident_hash, mark_ident, NULL);
170 /* Strings are _not_ GCed, but this routine exists so that a separate
171 roots table isn't needed for the few global variables that refer
175 gt_ggc_m_S (void *x ATTRIBUTE_UNUSED)
179 /* Pointer-walking routine for strings (not very interesting, since
180 strings don't contain pointers). */
183 gt_pch_p_S (void *obj ATTRIBUTE_UNUSED, void *x ATTRIBUTE_UNUSED,
184 gt_pointer_operator op ATTRIBUTE_UNUSED,
185 void *cookie ATTRIBUTE_UNUSED)
189 /* PCH pointer-walking routine for strings. */
192 gt_pch_n_S (const void *x)
194 gt_pch_note_object ((void *)x, (void *)x, >_pch_p_S);
197 /* Handle saving and restoring the string pool for PCH. */
199 struct string_pool_data GTY(())
201 tree * GTY((length ("%h.nslots"))) entries;
203 unsigned int nelements;
206 static GTY(()) struct string_pool_data * spd;
209 ht_copy_and_clear (cpp_reader *r ATTRIBUTE_UNUSED, hashnode hp, const void *ht2_p)
211 cpp_hashnode *h = CPP_HASHNODE (hp);
212 struct ht *ht2 = (struct ht *) ht2_p;
214 if (h->type != NT_VOID
215 && (h->flags & NODE_BUILTIN) == 0)
217 cpp_hashnode *h2 = CPP_HASHNODE (ht_lookup (ht2,
222 memcpy (&h2->value, &h->value, sizeof (h->value));
225 memset (&h->value, 0, sizeof (h->value));
230 static struct ht *saved_ident_hash;
233 gt_pch_save_stringpool (void)
237 spd = ggc_alloc (sizeof (*spd));
238 spd->nslots = ident_hash->nslots;
239 spd->nelements = ident_hash->nelements;
240 spd->entries = ggc_alloc (sizeof (tree *) * spd->nslots);
241 for (i = 0; i < spd->nslots; i++)
242 if (ident_hash->entries[i] != NULL)
243 spd->entries[i] = HT_IDENT_TO_GCC_IDENT (ident_hash->entries[i]);
245 spd->entries[i] = NULL;
247 saved_ident_hash = ht_create (14);
248 saved_ident_hash->alloc_node = alloc_node;
249 ht_forall (ident_hash, ht_copy_and_clear, saved_ident_hash);
253 gt_pch_fixup_stringpool (void)
255 ht_forall (saved_ident_hash, ht_copy_and_clear, ident_hash);
256 ht_destroy (saved_ident_hash);
257 saved_ident_hash = 0;
261 gt_pch_restore_stringpool (void)
265 ident_hash->nslots = spd->nslots;
266 ident_hash->nelements = spd->nelements;
267 ident_hash->entries = xrealloc (ident_hash->entries,
268 sizeof (hashnode) * spd->nslots);
269 for (i = 0; i < spd->nslots; i++)
270 if (spd->entries[i] != NULL)
271 ident_hash->entries[i] = GCC_IDENT_TO_HT_IDENT (spd->entries[i]);
273 ident_hash->entries[i] = NULL;
278 #include "gt-stringpool.h"