aboutsummaryrefslogtreecommitdiff
path: root/gcc/stringpool.c
blob: b3cfcc45a096b82726a09a7d90bbddef2f550ff1 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
/* String pool for GCC.
   Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005
   Free Software Foundation, Inc.

This file is part of GCC.

GCC is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free
Software Foundation; either version 2, or (at your option) any later
version.

GCC is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
for more details.

You should have received a copy of the GNU General Public License
along with GCC; see the file COPYING.  If not, write to the Free
Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
02110-1301, USA.  */

/* String text, identifier text and identifier node allocator.  Strings
   allocated by ggc_alloc_string are stored in an obstack which is
   never shrunk.  Identifiers are uniquely stored in a hash table.

   We use cpplib's hash table implementation.  libiberty's
   hashtab.c is not used because it requires 100% average space
   overhead per string, which is unacceptable.  Also, this algorithm
   is faster.  */

#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "tm.h"
#include "ggc.h"
#include "tree.h"
#include "symtab.h"
#include "cpplib.h"

/* The "" allocated string.  */
const char empty_string[] = "";

/* Character strings, each containing a single decimal digit.
   Written this way to save space.  */
const char digit_vector[] = {
  '0', 0, '1', 0, '2', 0, '3', 0, '4', 0,
  '5', 0, '6', 0, '7', 0, '8', 0, '9', 0
};

struct ht *ident_hash;
static struct obstack string_stack;

static hashnode alloc_node (hash_table *);
static int mark_ident (struct cpp_reader *, hashnode, const void *);

static void *
stringpool_ggc_alloc (size_t x)
{
  return ggc_alloc (x);
}

/* Initialize the string pool.  */
void
init_stringpool (void)
{
  /* Create with 16K (2^14) entries.  */
  ident_hash = ht_create (14);
  ident_hash->alloc_node = alloc_node;
  ident_hash->alloc_subobject = stringpool_ggc_alloc;
  gcc_obstack_init (&string_stack);
}

/* Allocate a hash node.  */
static hashnode
alloc_node (hash_table *table ATTRIBUTE_UNUSED)
{
  return GCC_IDENT_TO_HT_IDENT (make_node (IDENTIFIER_NODE));
}

/* Allocate and return a string constant of length LENGTH, containing
   CONTENTS.  If LENGTH is -1, CONTENTS is assumed to be a
   nul-terminated string, and the length is calculated using strlen.
   If the same string constant has been allocated before, that copy is
   returned this time too.  */

const char *
ggc_alloc_string (const char *contents, int length)
{
  if (length == -1)
    length = strlen (contents);

  if (length == 0)
    return empty_string;
  if (length == 1 && ISDIGIT (contents[0]))
    return digit_string (contents[0] - '0');

  obstack_grow0 (&string_stack, contents, length);
  return XOBFINISH (&string_stack, const char *);
}

/* Return an IDENTIFIER_NODE whose name is TEXT (a null-terminated string).
   If an identifier with that name has previously been referred to,
   the same node is returned this time.  */

#undef get_identifier

tree
get_identifier (const char *text)
{
  hashnode ht_node = ht_lookup (ident_hash,
				(const unsigned char *) text,
				strlen (text), HT_ALLOC);

  /* ht_node can't be NULL here.  */
  return HT_IDENT_TO_GCC_IDENT (ht_node);
}

/* Identical to get_identifier, except that the length is assumed
   known.  */

tree
get_identifier_with_length (const char *text, size_t length)
{
  hashnode ht_node = ht_lookup (ident_hash,
				(const unsigned char *) text,
				length, HT_ALLOC);

  /* ht_node can't be NULL here.  */
  return HT_IDENT_TO_GCC_IDENT (ht_node);
}

/* If an identifier with the name TEXT (a null-terminated string) has
   previously been referred to, return that node; otherwise return
   NULL_TREE.  */

tree
maybe_get_identifier (const char *text)
{
  hashnode ht_node;

  ht_node = ht_lookup (ident_hash, (const unsigned char *) text,
		       strlen (text), HT_NO_INSERT);
  if (ht_node)
    return HT_IDENT_TO_GCC_IDENT (ht_node);

  return NULL_TREE;
}

/* Report some basic statistics about the string pool.  */

void
stringpool_statistics (void)
{
  ht_dump_statistics (ident_hash);
}

/* Mark an identifier for GC.  */

static int
mark_ident (struct cpp_reader *pfile ATTRIBUTE_UNUSED, hashnode h,
	    const void *v ATTRIBUTE_UNUSED)
{
  gt_ggc_m_9tree_node (HT_IDENT_TO_GCC_IDENT (h));
  return 1;
}

/* Mark the trees hanging off the identifier node for GGC.  These are
   handled specially (not using gengtype) because of the special
   treatment for strings.  */

void
ggc_mark_stringpool (void)
{
  ht_forall (ident_hash, mark_ident, NULL);
}

/* Strings are _not_ GCed, but this routine exists so that a separate
   roots table isn't needed for the few global variables that refer
   to strings.  */

void
gt_ggc_m_S (void *x ATTRIBUTE_UNUSED)
{
}

/* Pointer-walking routine for strings (not very interesting, since
   strings don't contain pointers).  */

void
gt_pch_p_S (void *obj ATTRIBUTE_UNUSED, void *x ATTRIBUTE_UNUSED,
	    gt_pointer_operator op ATTRIBUTE_UNUSED,
	    void *cookie ATTRIBUTE_UNUSED)
{
}

/* PCH pointer-walking routine for strings.  */

void
gt_pch_n_S (const void *x)
{
  gt_pch_note_object ((void *)x, (void *)x, &gt_pch_p_S,
		      gt_types_enum_last);
}

/* Handle saving and restoring the string pool for PCH.  */

/* SPD is saved in the PCH file and holds the information needed
   to restore the string pool.  */

struct string_pool_data GTY(())
{
  struct ht_identifier * * 
    GTY((length ("%h.nslots"),
	 nested_ptr (union tree_node, "%h ? GCC_IDENT_TO_HT_IDENT (%h) : NULL",
		     "%h ? HT_IDENT_TO_GCC_IDENT (%h) : NULL")))
    entries;
  unsigned int nslots;
  unsigned int nelements;
};

static GTY(()) struct string_pool_data * spd;

/* Save the stringpool data in SPD.  */

void
gt_pch_save_stringpool (void)
{
  spd = ggc_alloc (sizeof (*spd));
  spd->nslots = ident_hash->nslots;
  spd->nelements = ident_hash->nelements;
  spd->entries = ggc_alloc (sizeof (spd->entries[0]) * spd->nslots);
  memcpy (spd->entries, ident_hash->entries,
	  spd->nslots * sizeof (spd->entries[0]));
}

/* Return the stringpool to its state before gt_pch_save_stringpool
   was called.  */

void
gt_pch_fixup_stringpool (void)
{
}

/* A PCH file has been restored, which loaded SPD; fill the real hash table
   from SPD.  */

void
gt_pch_restore_stringpool (void)
{
  ht_load (ident_hash, spd->entries, spd->nslots, spd->nelements, false);
  spd = NULL;
}

#include "gt-stringpool.h"