1 /* String pool for GCC.
2 Copyright (C) 2000-2015 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 3, 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 COPYING3. If not see
18 <http://www.gnu.org/licenses/>. */
20 /* String text, identifier text and identifier node allocator.
21 Identifiers are uniquely stored in a hash table.
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
30 #include "coretypes.h"
32 #include "ggc-internal.h"
43 /* The "" allocated string. */
44 const char empty_string
[] = "";
46 /* Character strings, each containing a single decimal digit.
47 Written this way to save space. */
48 static const char digit_vector
[] = {
49 '0', 0, '1', 0, '2', 0, '3', 0, '4', 0,
50 '5', 0, '6', 0, '7', 0, '8', 0, '9', 0
53 #define digit_string(d) (digit_vector + ((d) * 2))
55 struct ht
*ident_hash
;
57 static hashnode
alloc_node (cpp_hash_table
*);
58 static int mark_ident (struct cpp_reader
*, hashnode
, const void *);
61 stringpool_ggc_alloc (size_t x
)
63 return ggc_alloc_atomic (x
);
66 /* Initialize the string pool. */
68 init_stringpool (void)
70 /* Clean up if we're called more than once.
71 (We can't make this idempotent since identifiers contain state) */
73 ht_destroy (ident_hash
);
75 /* Create with 16K (2^14) entries. */
76 ident_hash
= ht_create (14);
77 ident_hash
->alloc_node
= alloc_node
;
78 ident_hash
->alloc_subobject
= stringpool_ggc_alloc
;
81 /* Allocate a hash node. */
83 alloc_node (cpp_hash_table
*table ATTRIBUTE_UNUSED
)
85 return GCC_IDENT_TO_HT_IDENT (make_node (IDENTIFIER_NODE
));
88 /* Allocate and return a string constant of length LENGTH, containing
89 CONTENTS. If LENGTH is -1, CONTENTS is assumed to be a
90 nul-terminated string, and the length is calculated using strlen. */
93 ggc_alloc_string (const char *contents
, int length MEM_STAT_DECL
)
98 length
= strlen (contents
);
102 if (length
== 1 && ISDIGIT (contents
[0]))
103 return digit_string (contents
[0] - '0');
105 result
= (char *) ggc_internal_cleared_alloc (length
+ 1 PASS_MEM_STAT
);
106 memcpy (result
, contents
, length
);
107 result
[length
] = '\0';
108 return (const char *) result
;
111 /* Return an IDENTIFIER_NODE whose name is TEXT (a null-terminated string).
112 If an identifier with that name has previously been referred to,
113 the same node is returned this time. */
115 #undef get_identifier
118 get_identifier (const char *text
)
120 hashnode ht_node
= ht_lookup (ident_hash
,
121 (const unsigned char *) text
,
122 strlen (text
), HT_ALLOC
);
124 /* ht_node can't be NULL here. */
125 return HT_IDENT_TO_GCC_IDENT (ht_node
);
128 /* Identical to get_identifier, except that the length is assumed
132 get_identifier_with_length (const char *text
, size_t length
)
134 hashnode ht_node
= ht_lookup (ident_hash
,
135 (const unsigned char *) text
,
138 /* ht_node can't be NULL here. */
139 return HT_IDENT_TO_GCC_IDENT (ht_node
);
142 /* If an identifier with the name TEXT (a null-terminated string) has
143 previously been referred to, return that node; otherwise return
147 maybe_get_identifier (const char *text
)
151 ht_node
= ht_lookup (ident_hash
, (const unsigned char *) text
,
152 strlen (text
), HT_NO_INSERT
);
154 return HT_IDENT_TO_GCC_IDENT (ht_node
);
159 /* Report some basic statistics about the string pool. */
162 stringpool_statistics (void)
164 ht_dump_statistics (ident_hash
);
167 /* Mark an identifier for GC. */
170 mark_ident (struct cpp_reader
*pfile ATTRIBUTE_UNUSED
, hashnode h
,
171 const void *v ATTRIBUTE_UNUSED
)
173 gt_ggc_m_9tree_node (HT_IDENT_TO_GCC_IDENT (h
));
177 /* Return true if an identifier should be removed from the table. */
180 maybe_delete_ident (struct cpp_reader
*pfile ATTRIBUTE_UNUSED
, hashnode h
,
181 const void *v ATTRIBUTE_UNUSED
)
183 return !ggc_marked_p (HT_IDENT_TO_GCC_IDENT (h
));
186 /* Mark the trees hanging off the identifier node for GGC. These are
187 handled specially (not using gengtype) because identifiers are only
188 roots during one part of compilation. */
191 ggc_mark_stringpool (void)
193 ht_forall (ident_hash
, mark_ident
, NULL
);
196 /* Purge the identifier hash of identifiers which are no longer
200 ggc_purge_stringpool (void)
202 ht_purge (ident_hash
, maybe_delete_ident
, NULL
);
205 /* Pointer-walking routine for strings (not very interesting, since
206 strings don't contain pointers). */
209 gt_pch_p_S (void *obj ATTRIBUTE_UNUSED
, void *x ATTRIBUTE_UNUSED
,
210 gt_pointer_operator op ATTRIBUTE_UNUSED
,
211 void *cookie ATTRIBUTE_UNUSED
)
215 /* PCH pointer-walking routine for strings. */
218 gt_pch_n_S (const void *x
)
220 gt_pch_note_object (CONST_CAST (void *, x
), CONST_CAST (void *, x
),
225 /* User-callable entry point for marking string X. */
228 gt_pch_nx (const char *& x
)
234 gt_pch_nx (unsigned char *& x
)
240 gt_pch_nx (unsigned char& x ATTRIBUTE_UNUSED
)
245 gt_pch_nx (unsigned char *x
, gt_pointer_operator op
, void *cookie
)
250 /* Handle saving and restoring the string pool for PCH. */
252 /* SPD is saved in the PCH file and holds the information needed
253 to restore the string pool. */
255 struct GTY(()) string_pool_data
{
257 GTY((length ("%h.nslots"),
258 nested_ptr (union tree_node
, "%h ? GCC_IDENT_TO_HT_IDENT (%h) : NULL",
259 "%h ? HT_IDENT_TO_GCC_IDENT (%h) : NULL")))
262 unsigned int nelements
;
265 static GTY(()) struct string_pool_data
* spd
;
267 /* Save the stringpool data in SPD. */
270 gt_pch_save_stringpool (void)
272 spd
= ggc_alloc
<string_pool_data
> ();
273 spd
->nslots
= ident_hash
->nslots
;
274 spd
->nelements
= ident_hash
->nelements
;
275 spd
->entries
= ggc_vec_alloc
<ht_identifier_ptr
> (spd
->nslots
);
276 memcpy (spd
->entries
, ident_hash
->entries
,
277 spd
->nslots
* sizeof (spd
->entries
[0]));
280 /* Return the stringpool to its state before gt_pch_save_stringpool
284 gt_pch_fixup_stringpool (void)
288 /* A PCH file has been restored, which loaded SPD; fill the real hash table
292 gt_pch_restore_stringpool (void)
294 ht_load (ident_hash
, spd
->entries
, spd
->nslots
, spd
->nelements
, false);
298 #include "gt-stringpool.h"