1 /* String pool for GCC.
2 Copyright (C) 2000, 2001 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
34 #include "hashtable.h"
36 /* The "" allocated string. */
37 const char empty_string[] = "";
39 /* Character strings, each containing a single decimal digit.
40 Written this way to save space. */
41 const char digit_vector[] = {
42 '0', 0, '1', 0, '2', 0, '3', 0, '4', 0,
43 '5', 0, '6', 0, '7', 0, '8', 0, '9', 0
46 struct ht *ident_hash;
47 static struct obstack string_stack;
49 static hashnode alloc_node PARAMS ((hash_table *));
50 static int mark_ident PARAMS ((struct cpp_reader *, hashnode, const PTR));
51 static void mark_ident_hash PARAMS ((void *));
53 /* Initialize the string pool. */
57 /* Create with 16K (2^14) entries. */
58 ident_hash = ht_create (14);
59 ident_hash->alloc_node = alloc_node;
60 gcc_obstack_init (&string_stack);
61 ggc_add_root (&ident_hash, 1, sizeof ident_hash, mark_ident_hash);
64 /* Allocate a hash node. */
67 hash_table *table ATTRIBUTE_UNUSED;
69 return GCC_IDENT_TO_HT_IDENT (make_node (IDENTIFIER_NODE));
72 /* Allocate and return a string constant of length LENGTH, containing
73 CONTENTS. If LENGTH is -1, CONTENTS is assumed to be a
74 nul-terminated string, and the length is calculated using strlen.
75 If the same string constant has been allocated before, that copy is
76 returned this time too. */
79 ggc_alloc_string (contents, length)
84 length = strlen (contents);
88 if (length == 1 && ISDIGIT (contents[0]))
89 return digit_string (contents[0] - '0');
91 obstack_grow0 (&string_stack, contents, length);
92 return obstack_finish (&string_stack);
95 /* Return an IDENTIFIER_NODE whose name is TEXT (a null-terminated string).
96 If an identifier with that name has previously been referred to,
97 the same node is returned this time. */
100 get_identifier (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 (text, length)
119 hashnode ht_node = ht_lookup (ident_hash,
120 (const unsigned char *) text,
123 /* ht_node can't be NULL here. */
124 return HT_IDENT_TO_GCC_IDENT (ht_node);
127 /* If an identifier with the name TEXT (a null-terminated string) has
128 previously been referred to, return that node; otherwise return
132 maybe_get_identifier (text)
137 ht_node = ht_lookup (ident_hash, (const unsigned char *) text,
138 strlen (text), HT_NO_INSERT);
140 return HT_IDENT_TO_GCC_IDENT (ht_node);
145 /* Report some basic statistics about the string pool. */
148 stringpool_statistics ()
150 ht_dump_statistics (ident_hash);
153 /* Mark an identifier for GC. */
156 mark_ident (pfile, h, v)
157 struct cpp_reader *pfile ATTRIBUTE_UNUSED;
159 const PTR v ATTRIBUTE_UNUSED;
161 ggc_mark_tree (HT_IDENT_TO_GCC_IDENT (h));
165 /* Mark all identifiers for GC. */
168 mark_ident_hash (arg)
169 PTR arg ATTRIBUTE_UNUSED;
171 ht_forall (ident_hash, mark_ident, NULL);