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[official-gcc.git] / gcc / stringpool.c
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1 /* String pool for GCC.
2 Copyright (C) 2000, 2001, 2002, 2003, 2004 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
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 COPYING. If not, write to the Free
18 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
19 02111-1307, USA. */
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 use cpplib's 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
28 is faster. */
30 #include "config.h"
31 #include "system.h"
32 #include "coretypes.h"
33 #include "tm.h"
34 #include "ggc.h"
35 #include "tree.h"
36 #include "symtab.h"
37 #include "cpplib.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 *);
55 static void *
56 stringpool_ggc_alloc (size_t x)
58 return ggc_alloc (x);
61 /* Initialize the string pool. */
62 void
63 init_stringpool (void)
65 /* Create with 16K (2^14) entries. */
66 ident_hash = ht_create (14);
67 ident_hash->alloc_node = alloc_node;
68 ident_hash->alloc_subobject = stringpool_ggc_alloc;
69 gcc_obstack_init (&string_stack);
72 /* Allocate a hash node. */
73 static hashnode
74 alloc_node (hash_table *table ATTRIBUTE_UNUSED)
76 return GCC_IDENT_TO_HT_IDENT (make_node (IDENTIFIER_NODE));
79 /* Allocate and return a string constant of length LENGTH, containing
80 CONTENTS. If LENGTH is -1, CONTENTS is assumed to be a
81 nul-terminated string, and the length is calculated using strlen.
82 If the same string constant has been allocated before, that copy is
83 returned this time too. */
85 const char *
86 ggc_alloc_string (const char *contents, int length)
88 if (length == -1)
89 length = strlen (contents);
91 if (length == 0)
92 return empty_string;
93 if (length == 1 && ISDIGIT (contents[0]))
94 return digit_string (contents[0] - '0');
96 obstack_grow0 (&string_stack, contents, length);
97 return obstack_finish (&string_stack);
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. */
104 #undef get_identifier
106 tree
107 get_identifier (const char *text)
109 hashnode ht_node = ht_lookup (ident_hash,
110 (const unsigned char *) text,
111 strlen (text), HT_ALLOC);
113 /* ht_node can't be NULL here. */
114 return HT_IDENT_TO_GCC_IDENT (ht_node);
117 /* Identical to get_identifier, except that the length is assumed
118 known. */
120 tree
121 get_identifier_with_length (const char *text, size_t length)
123 hashnode ht_node = ht_lookup (ident_hash,
124 (const unsigned char *) text,
125 length, HT_ALLOC);
127 /* ht_node can't be NULL here. */
128 return HT_IDENT_TO_GCC_IDENT (ht_node);
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. */
135 tree
136 maybe_get_identifier (const char *text)
138 hashnode ht_node;
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);
145 return NULL_TREE;
148 /* Report some basic statistics about the string pool. */
150 void
151 stringpool_statistics (void)
153 ht_dump_statistics (ident_hash);
156 /* Mark an identifier for GC. */
158 static int
159 mark_ident (struct cpp_reader *pfile ATTRIBUTE_UNUSED, hashnode h,
160 const void *v ATTRIBUTE_UNUSED)
162 gt_ggc_m_9tree_node (HT_IDENT_TO_GCC_IDENT (h));
163 return 1;
166 /* Mark the trees hanging off the identifier node for GGC. These are
167 handled specially (not using gengtype) because of the special
168 treatment for strings. */
170 void
171 ggc_mark_stringpool (void)
173 ht_forall (ident_hash, mark_ident, NULL);
176 /* Strings are _not_ GCed, but this routine exists so that a separate
177 roots table isn't needed for the few global variables that refer
178 to strings. */
180 void
181 gt_ggc_m_S (void *x ATTRIBUTE_UNUSED)
185 /* Pointer-walking routine for strings (not very interesting, since
186 strings don't contain pointers). */
188 void
189 gt_pch_p_S (void *obj ATTRIBUTE_UNUSED, void *x ATTRIBUTE_UNUSED,
190 gt_pointer_operator op ATTRIBUTE_UNUSED,
191 void *cookie ATTRIBUTE_UNUSED)
195 /* PCH pointer-walking routine for strings. */
197 void
198 gt_pch_n_S (const void *x)
200 gt_pch_note_object ((void *)x, (void *)x, &gt_pch_p_S);
203 /* Handle saving and restoring the string pool for PCH. */
205 /* SPD is saved in the PCH file and holds the information needed
206 to restore the string pool. */
208 struct string_pool_data GTY(())
210 struct ht_identifier * *
211 GTY((length ("%h.nslots"),
212 nested_ptr (union tree_node, "%h ? GCC_IDENT_TO_HT_IDENT (%h) : NULL",
213 "%h ? HT_IDENT_TO_GCC_IDENT (%h) : NULL")))
214 entries;
215 unsigned int nslots;
216 unsigned int nelements;
219 static GTY(()) struct string_pool_data * spd;
221 /* Save the stringpool data in SPD. */
223 void
224 gt_pch_save_stringpool (void)
226 spd = ggc_alloc (sizeof (*spd));
227 spd->nslots = ident_hash->nslots;
228 spd->nelements = ident_hash->nelements;
229 spd->entries = ggc_alloc (sizeof (spd->entries[0]) * spd->nslots);
230 memcpy (spd->entries, ident_hash->entries,
231 spd->nslots * sizeof (spd->entries[0]));
234 /* Return the stringpool to its state before gt_pch_save_stringpool
235 was called. */
237 void
238 gt_pch_fixup_stringpool (void)
242 /* A PCH file has been restored, which loaded SPD; fill the real hash table
243 from SPD. */
245 void
246 gt_pch_restore_stringpool (void)
248 ht_load (ident_hash, spd->entries, spd->nslots, spd->nelements, false);
249 spd = NULL;
252 #include "gt-stringpool.h"