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comparison gcc/stringpool.c @ 0:a06113de4d67

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author kent <kent@cr.ie.u-ryukyu.ac.jp>
date Fri, 17 Jul 2009 14:47:48 +0900
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children 77e2b8dfacca
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-1:000000000000 0:a06113de4d67
1 /* String pool for GCC.
2 Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2007, 2008
3 Free Software Foundation, Inc.
4
5 This file is part of GCC.
6
7 GCC is free software; you can redistribute it and/or modify it under
8 the terms of the GNU General Public License as published by the Free
9 Software Foundation; either version 3, or (at your option) any later
10 version.
11
12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
15 for more details.
16
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING3. If not see
19 <http://www.gnu.org/licenses/>. */
20
21 /* String text, identifier text and identifier node allocator.
22 Identifiers are uniquely stored in a hash table.
23
24 We use cpplib's hash table implementation. libiberty's
25 hashtab.c is not used because it requires 100% average space
26 overhead per string, which is unacceptable. Also, this algorithm
27 is faster. */
28
29 #include "config.h"
30 #include "system.h"
31 #include "coretypes.h"
32 #include "tm.h"
33 #include "ggc.h"
34 #include "tree.h"
35 #include "symtab.h"
36 #include "cpplib.h"
37
38 /* The "" allocated string. */
39 const char empty_string[] = "";
40
41 /* Character strings, each containing a single decimal digit.
42 Written this way to save space. */
43 const char digit_vector[] = {
44 '0', 0, '1', 0, '2', 0, '3', 0, '4', 0,
45 '5', 0, '6', 0, '7', 0, '8', 0, '9', 0
46 };
47
48 struct ht *ident_hash;
49
50 static hashnode alloc_node (hash_table *);
51 static int mark_ident (struct cpp_reader *, hashnode, const void *);
52
53 static void *
54 stringpool_ggc_alloc (size_t x)
55 {
56 return ggc_alloc (x);
57 }
58
59 /* Initialize the string pool. */
60 void
61 init_stringpool (void)
62 {
63 /* Create with 16K (2^14) entries. */
64 ident_hash = ht_create (14);
65 ident_hash->alloc_node = alloc_node;
66 ident_hash->alloc_subobject = stringpool_ggc_alloc;
67 }
68
69 /* Allocate a hash node. */
70 static hashnode
71 alloc_node (hash_table *table ATTRIBUTE_UNUSED)
72 {
73 return GCC_IDENT_TO_HT_IDENT (make_node (IDENTIFIER_NODE));
74 }
75
76 /* Allocate and return a string constant of length LENGTH, containing
77 CONTENTS. If LENGTH is -1, CONTENTS is assumed to be a
78 nul-terminated string, and the length is calculated using strlen. */
79
80 const char *
81 ggc_alloc_string (const char *contents, int length)
82 {
83 char *result;
84
85 if (length == -1)
86 length = strlen (contents);
87
88 if (length == 0)
89 return empty_string;
90 if (length == 1 && ISDIGIT (contents[0]))
91 return digit_string (contents[0] - '0');
92
93 result = GGC_NEWVAR (char, length + 1);
94 memcpy (result, contents, length);
95 result[length] = '\0';
96 return (const char *) result;
97 }
98
99 /* Return an IDENTIFIER_NODE whose name is TEXT (a null-terminated string).
100 If an identifier with that name has previously been referred to,
101 the same node is returned this time. */
102
103 #undef get_identifier
104
105 tree
106 get_identifier (const char *text)
107 {
108 hashnode ht_node = ht_lookup (ident_hash,
109 (const unsigned char *) text,
110 strlen (text), HT_ALLOC);
111
112 /* ht_node can't be NULL here. */
113 return HT_IDENT_TO_GCC_IDENT (ht_node);
114 }
115
116 /* Identical to get_identifier, except that the length is assumed
117 known. */
118
119 tree
120 get_identifier_with_length (const char *text, size_t length)
121 {
122 hashnode ht_node = ht_lookup (ident_hash,
123 (const unsigned char *) text,
124 length, HT_ALLOC);
125
126 /* ht_node can't be NULL here. */
127 return HT_IDENT_TO_GCC_IDENT (ht_node);
128 }
129
130 /* If an identifier with the name TEXT (a null-terminated string) has
131 previously been referred to, return that node; otherwise return
132 NULL_TREE. */
133
134 tree
135 maybe_get_identifier (const char *text)
136 {
137 hashnode ht_node;
138
139 ht_node = ht_lookup (ident_hash, (const unsigned char *) text,
140 strlen (text), HT_NO_INSERT);
141 if (ht_node)
142 return HT_IDENT_TO_GCC_IDENT (ht_node);
143
144 return NULL_TREE;
145 }
146
147 /* Report some basic statistics about the string pool. */
148
149 void
150 stringpool_statistics (void)
151 {
152 ht_dump_statistics (ident_hash);
153 }
154
155 /* Mark an identifier for GC. */
156
157 static int
158 mark_ident (struct cpp_reader *pfile ATTRIBUTE_UNUSED, hashnode h,
159 const void *v ATTRIBUTE_UNUSED)
160 {
161 gt_ggc_m_9tree_node (HT_IDENT_TO_GCC_IDENT (h));
162 return 1;
163 }
164
165 /* Return true if an identifier should be removed from the table. */
166
167 static int
168 maybe_delete_ident (struct cpp_reader *pfile ATTRIBUTE_UNUSED, hashnode h,
169 const void *v ATTRIBUTE_UNUSED)
170 {
171 return !ggc_marked_p (HT_IDENT_TO_GCC_IDENT (h));
172 }
173
174 /* Mark the trees hanging off the identifier node for GGC. These are
175 handled specially (not using gengtype) because identifiers are only
176 roots during one part of compilation. */
177
178 void
179 ggc_mark_stringpool (void)
180 {
181 ht_forall (ident_hash, mark_ident, NULL);
182 }
183
184 /* Purge the identifier hash of identifiers which are no longer
185 referenced. */
186
187 void
188 ggc_purge_stringpool (void)
189 {
190 ht_purge (ident_hash, maybe_delete_ident, NULL);
191 }
192
193 /* Pointer-walking routine for strings (not very interesting, since
194 strings don't contain pointers). */
195
196 void
197 gt_pch_p_S (void *obj ATTRIBUTE_UNUSED, void *x ATTRIBUTE_UNUSED,
198 gt_pointer_operator op ATTRIBUTE_UNUSED,
199 void *cookie ATTRIBUTE_UNUSED)
200 {
201 }
202
203 /* PCH pointer-walking routine for strings. */
204
205 void
206 gt_pch_n_S (const void *x)
207 {
208 gt_pch_note_object (CONST_CAST (void *, x), CONST_CAST (void *, x),
209 &gt_pch_p_S, gt_types_enum_last);
210 }
211
212 /* Handle saving and restoring the string pool for PCH. */
213
214 /* SPD is saved in the PCH file and holds the information needed
215 to restore the string pool. */
216
217 struct string_pool_data GTY(())
218 {
219 struct ht_identifier * *
220 GTY((length ("%h.nslots"),
221 nested_ptr (union tree_node, "%h ? GCC_IDENT_TO_HT_IDENT (%h) : NULL",
222 "%h ? HT_IDENT_TO_GCC_IDENT (%h) : NULL")))
223 entries;
224 unsigned int nslots;
225 unsigned int nelements;
226 };
227
228 static GTY(()) struct string_pool_data * spd;
229
230 /* Save the stringpool data in SPD. */
231
232 void
233 gt_pch_save_stringpool (void)
234 {
235 spd = GGC_NEW (struct string_pool_data);
236 spd->nslots = ident_hash->nslots;
237 spd->nelements = ident_hash->nelements;
238 spd->entries = GGC_NEWVEC (struct ht_identifier *, spd->nslots);
239 memcpy (spd->entries, ident_hash->entries,
240 spd->nslots * sizeof (spd->entries[0]));
241 }
242
243 /* Return the stringpool to its state before gt_pch_save_stringpool
244 was called. */
245
246 void
247 gt_pch_fixup_stringpool (void)
248 {
249 }
250
251 /* A PCH file has been restored, which loaded SPD; fill the real hash table
252 from SPD. */
253
254 void
255 gt_pch_restore_stringpool (void)
256 {
257 ht_load (ident_hash, spd->entries, spd->nslots, spd->nelements, false);
258 spd = NULL;
259 }
260
261 #include "gt-stringpool.h"