1 /* String pool for GCC.
2 Copyright (C) 2000-2022 Free Software Foundation, Inc.
3
4 This file is part of GCC.
5
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.
10
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.
15
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/>. */
19
20 /* String text, identifier text and identifier node allocator.
21 Identifiers are uniquely stored in a hash table.
22
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. */
27
28 #include "config.h"
29 #include "system.h"
30 #include "coretypes.h"
31 #include "tree.h"
32
33 struct ht *ident_hash;
34
35 static hashnode alloc_node (cpp_hash_table *);
36 static int mark_ident (struct cpp_reader *, hashnode, const void *);
37
38 static void *
stringpool_ggc_alloc(size_t x)39 stringpool_ggc_alloc (size_t x)
40 {
41 return ggc_alloc_atomic (x);
42 }
43
44 /* Initialize the string pool. */
45 void
init_stringpool(void)46 init_stringpool (void)
47 {
48 /* Clean up if we're called more than once.
49 (We can't make this idempotent since identifiers contain state) */
50 if (ident_hash)
51 ht_destroy (ident_hash);
52
53 /* Create with 16K (2^14) entries. */
54 ident_hash = ht_create (14);
55 ident_hash->alloc_node = alloc_node;
56 ident_hash->alloc_subobject = stringpool_ggc_alloc;
57 }
58
59 /* Allocate a hash node. */
60 static hashnode
alloc_node(cpp_hash_table * table ATTRIBUTE_UNUSED)61 alloc_node (cpp_hash_table *table ATTRIBUTE_UNUSED)
62 {
63 return GCC_IDENT_TO_HT_IDENT (make_node (IDENTIFIER_NODE));
64 }
65
66 /* Allocate and return a string constant of length LENGTH, containing
67 CONTENTS. If LENGTH is -1, CONTENTS is assumed to be a
68 nul-terminated string, and the length is calculated using strlen. */
69
70 const char *
ggc_alloc_string(const char * contents,int length MEM_STAT_DECL)71 ggc_alloc_string (const char *contents, int length MEM_STAT_DECL)
72 {
73 if (length == -1)
74 length = strlen (contents);
75
76 if (!length)
77 return "";
78
79 char *result = (char *) ggc_alloc_atomic (length + 1);
80 memcpy (result, contents, length);
81 result[length] = '\0';
82
83 return (const char *) result;
84 }
85
86 /* Return an IDENTIFIER_NODE whose name is TEXT (a null-terminated string).
87 If an identifier with that name has previously been referred to,
88 the same node is returned this time. */
89
90 #undef get_identifier
91
92 tree
get_identifier(const char * text)93 get_identifier (const char *text)
94 {
95 hashnode ht_node = ht_lookup (ident_hash,
96 (const unsigned char *) text,
97 strlen (text), HT_ALLOC);
98
99 /* ht_node can't be NULL here. */
100 return HT_IDENT_TO_GCC_IDENT (ht_node);
101 }
102
103 /* Identical to get_identifier, except that the length is assumed
104 known. */
105
106 tree
get_identifier_with_length(const char * text,size_t length)107 get_identifier_with_length (const char *text, size_t length)
108 {
109 hashnode ht_node = ht_lookup (ident_hash,
110 (const unsigned char *) text,
111 length, HT_ALLOC);
112
113 /* ht_node can't be NULL here. */
114 return HT_IDENT_TO_GCC_IDENT (ht_node);
115 }
116
117 /* If an identifier with the name TEXT (a null-terminated string) has
118 previously been referred to, return that node; otherwise return
119 NULL_TREE. */
120
121 tree
maybe_get_identifier(const char * text)122 maybe_get_identifier (const char *text)
123 {
124 hashnode ht_node;
125
126 ht_node = ht_lookup (ident_hash, (const unsigned char *) text,
127 strlen (text), HT_NO_INSERT);
128 if (ht_node)
129 return HT_IDENT_TO_GCC_IDENT (ht_node);
130
131 return NULL_TREE;
132 }
133
134 /* Report some basic statistics about the string pool. */
135
136 void
stringpool_statistics(void)137 stringpool_statistics (void)
138 {
139 ht_dump_statistics (ident_hash);
140 }
141
142 /* Mark an identifier for GC. */
143
144 static int
mark_ident(struct cpp_reader * pfile ATTRIBUTE_UNUSED,hashnode h,const void * v ATTRIBUTE_UNUSED)145 mark_ident (struct cpp_reader *pfile ATTRIBUTE_UNUSED, hashnode h,
146 const void *v ATTRIBUTE_UNUSED)
147 {
148 gt_ggc_m_9tree_node (HT_IDENT_TO_GCC_IDENT (h));
149 return 1;
150 }
151
152 /* Return true if an identifier should be removed from the table. */
153
154 static int
maybe_delete_ident(struct cpp_reader * pfile ATTRIBUTE_UNUSED,hashnode h,const void * v ATTRIBUTE_UNUSED)155 maybe_delete_ident (struct cpp_reader *pfile ATTRIBUTE_UNUSED, hashnode h,
156 const void *v ATTRIBUTE_UNUSED)
157 {
158 return !ggc_marked_p (HT_IDENT_TO_GCC_IDENT (h));
159 }
160
161 /* Mark the trees hanging off the identifier node for GGC. These are
162 handled specially (not using gengtype) because identifiers are only
163 roots during one part of compilation. */
164
165 void
ggc_mark_stringpool(void)166 ggc_mark_stringpool (void)
167 {
168 ht_forall (ident_hash, mark_ident, NULL);
169 }
170
171 /* Purge the identifier hash of identifiers which are no longer
172 referenced. */
173
174 void
ggc_purge_stringpool(void)175 ggc_purge_stringpool (void)
176 {
177 ht_purge (ident_hash, maybe_delete_ident, NULL);
178 }
179
180 /* Pointer-walking routine for strings (not very interesting, since
181 strings don't contain pointers). */
182
183 void
gt_pch_p_S(void * obj ATTRIBUTE_UNUSED,void * x ATTRIBUTE_UNUSED,gt_pointer_operator op ATTRIBUTE_UNUSED,void * cookie ATTRIBUTE_UNUSED)184 gt_pch_p_S (void *obj ATTRIBUTE_UNUSED, void *x ATTRIBUTE_UNUSED,
185 gt_pointer_operator op ATTRIBUTE_UNUSED,
186 void *cookie ATTRIBUTE_UNUSED)
187 {
188 }
189
190 /* PCH pointer-walking routine for strings. */
191
192 void
gt_pch_n_S(const void * x)193 gt_pch_n_S (const void *x)
194 {
195 gt_pch_note_object (CONST_CAST (void *, x), CONST_CAST (void *, x),
196 >_pch_p_S);
197 }
198
199
200 /* User-callable entry point for marking string X. */
201
202 void
gt_pch_nx(const char * & x)203 gt_pch_nx (const char *& x)
204 {
205 gt_pch_n_S (x);
206 }
207
208 void
gt_pch_nx(char * & x)209 gt_pch_nx (char *& x)
210 {
211 gt_pch_n_S (x);
212 }
213
214 void
gt_pch_nx(unsigned char * & x)215 gt_pch_nx (unsigned char *& x)
216 {
217 gt_pch_n_S (x);
218 }
219
220 void
gt_pch_nx(unsigned char & x ATTRIBUTE_UNUSED)221 gt_pch_nx (unsigned char& x ATTRIBUTE_UNUSED)
222 {
223 }
224
225 void
gt_pch_nx(unsigned char * x,gt_pointer_operator op,void * cookie)226 gt_pch_nx (unsigned char *x, gt_pointer_operator op, void *cookie)
227 {
228 op (x, NULL, cookie);
229 }
230
231 /* Handle saving and restoring the string pool for PCH. */
232
233 /* SPD is saved in the PCH file and holds the information needed
234 to restore the string pool. */
235
236 struct GTY(()) string_pool_data {
237 ht_identifier_ptr *
238 GTY((length ("%h.nslots"),
239 nested_ptr (union tree_node, "%h ? GCC_IDENT_TO_HT_IDENT (%h) : NULL",
240 "%h ? HT_IDENT_TO_GCC_IDENT (%h) : NULL")))
241 entries;
242 unsigned int nslots;
243 unsigned int nelements;
244 };
245
246 static GTY(()) struct string_pool_data * spd;
247
248 /* Save the stringpool data in SPD. */
249
250 void
gt_pch_save_stringpool(void)251 gt_pch_save_stringpool (void)
252 {
253 spd = ggc_alloc<string_pool_data> ();
254 spd->nslots = ident_hash->nslots;
255 spd->nelements = ident_hash->nelements;
256 spd->entries = ggc_vec_alloc<ht_identifier_ptr> (spd->nslots);
257 memcpy (spd->entries, ident_hash->entries,
258 spd->nslots * sizeof (spd->entries[0]));
259 }
260
261 /* Return the stringpool to its state before gt_pch_save_stringpool
262 was called. */
263
264 void
gt_pch_fixup_stringpool(void)265 gt_pch_fixup_stringpool (void)
266 {
267 }
268
269 /* A PCH file has been restored, which loaded SPD; fill the real hash table
270 from SPD. */
271
272 void
gt_pch_restore_stringpool(void)273 gt_pch_restore_stringpool (void)
274 {
275 ht_load (ident_hash, spd->entries, spd->nslots, spd->nelements, false);
276 spd = NULL;
277 }
278
279 #include "gt-stringpool.h"
280