summaryrefslogtreecommitdiff
path: root/gcc/attribs.c
blob: be360d36bf2203dbf3a3c66f7beaa1640ba7d7f6 (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
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
/* Functions dealing with attribute handling, used by most front ends.
   Copyright (C) 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001,
   2002, 2003, 2004, 2005, 2007, 2008 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 3, 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 COPYING3.  If not see
<http://www.gnu.org/licenses/>.  */

#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "tm.h"
#include "tree.h"
#include "flags.h"
#include "toplev.h"
#include "output.h"
#include "rtl.h"
#include "ggc.h"
#include "tm_p.h"
#include "cpplib.h"
#include "target.h"
#include "langhooks.h"
#include "hashtab.h"
#include "c-common.h"

static void init_attributes (void);

/* Table of the tables of attributes (common, language, format, machine)
   searched.  */
static const struct attribute_spec *attribute_tables[4];

/* Hashtable mapping names (represented as substrings) to attribute specs. */
static htab_t attribute_hash;

/* Substring representation.  */

struct substring
{
  const char *str;
  int length;
};

static bool attributes_initialized = false;

/* Default empty table of attributes.  */

static const struct attribute_spec empty_attribute_table[] =
{
  { NULL, 0, 0, false, false, false, NULL }
};

/* Return base name of the attribute.  Ie '__attr__' is turned into 'attr'.
   To avoid need for copying, we simply return length of the string.  */

static void
extract_attribute_substring (struct substring *str)
{
  if (str->length > 4 && str->str[0] == '_' && str->str[1] == '_'
      && str->str[str->length - 1] == '_' && str->str[str->length - 2] == '_')
    {
      str->length -= 4;
      str->str += 2;
    }
}

/* Simple hash function to avoid need to scan whole string.  */

static inline hashval_t
substring_hash (const char *str, int l)
{
  return str[0] + str[l - 1] * 256 + l * 65536;
}

/* Used for attribute_hash.  */

static hashval_t
hash_attr (const void *p)
{
  const struct attribute_spec *const spec = (const struct attribute_spec *) p;
  const int l = strlen (spec->name);

  return substring_hash (spec->name, l);
}

/* Used for attribute_hash.  */

static int
eq_attr (const void *p, const void *q)
{
  const struct attribute_spec *const spec = (const struct attribute_spec *) p;
  const struct substring *const str = (const struct substring *) q;

  return (!strncmp (spec->name, str->str, str->length) && !spec->name[str->length]);
}

/* Initialize attribute tables, and make some sanity checks
   if --enable-checking.  */

static void
init_attributes (void)
{
  size_t i;
  int k;

  attribute_tables[0] = lang_hooks.common_attribute_table;
  attribute_tables[1] = lang_hooks.attribute_table;
  attribute_tables[2] = lang_hooks.format_attribute_table;
  attribute_tables[3] = targetm.attribute_table;

  /* Translate NULL pointers to pointers to the empty table.  */
  for (i = 0; i < ARRAY_SIZE (attribute_tables); i++)
    if (attribute_tables[i] == NULL)
      attribute_tables[i] = empty_attribute_table;

#ifdef ENABLE_CHECKING
  /* Make some sanity checks on the attribute tables.  */
  for (i = 0; i < ARRAY_SIZE (attribute_tables); i++)
    {
      int j;

      for (j = 0; attribute_tables[i][j].name != NULL; j++)
	{
	  /* The name must not begin and end with __.  */
	  const char *name = attribute_tables[i][j].name;
	  int len = strlen (name);

	  gcc_assert (!(name[0] == '_' && name[1] == '_'
			&& name[len - 1] == '_' && name[len - 2] == '_'));

	  /* The minimum and maximum lengths must be consistent.  */
	  gcc_assert (attribute_tables[i][j].min_length >= 0);

	  gcc_assert (attribute_tables[i][j].max_length == -1
		      || (attribute_tables[i][j].max_length
			  >= attribute_tables[i][j].min_length));

	  /* An attribute cannot require both a DECL and a TYPE.  */
	  gcc_assert (!attribute_tables[i][j].decl_required
		      || !attribute_tables[i][j].type_required);

	  /* If an attribute requires a function type, in particular
	     it requires a type.  */
	  gcc_assert (!attribute_tables[i][j].function_type_required
		      || attribute_tables[i][j].type_required);
	}
    }

  /* Check that each name occurs just once in each table.  */
  for (i = 0; i < ARRAY_SIZE (attribute_tables); i++)
    {
      int j, k;
      for (j = 0; attribute_tables[i][j].name != NULL; j++)
	for (k = j + 1; attribute_tables[i][k].name != NULL; k++)
	  gcc_assert (strcmp (attribute_tables[i][j].name,
			      attribute_tables[i][k].name));
    }
  /* Check that no name occurs in more than one table.  */
  for (i = 0; i < ARRAY_SIZE (attribute_tables); i++)
    {
      size_t j, k, l;

      for (j = i + 1; j < ARRAY_SIZE (attribute_tables); j++)
	for (k = 0; attribute_tables[i][k].name != NULL; k++)
	  for (l = 0; attribute_tables[j][l].name != NULL; l++)
	    gcc_assert (strcmp (attribute_tables[i][k].name,
				attribute_tables[j][l].name));
    }
#endif

  attribute_hash = htab_create (200, hash_attr, eq_attr, NULL);
  for (i = 0; i < ARRAY_SIZE (attribute_tables); i++)
    for (k = 0; attribute_tables[i][k].name != NULL; k++)
      {
	struct substring str;
	const void **slot;

	str.str = attribute_tables[i][k].name;
	str.length = strlen (attribute_tables[i][k].name);
	slot = (const void **)htab_find_slot_with_hash (attribute_hash, &str,
					 substring_hash (str.str, str.length),
					 INSERT);
	gcc_assert (!*slot);
	*slot = &attribute_tables[i][k];
      }
  attributes_initialized = true;
}

/* Return the spec for the attribute named NAME.  */

const struct attribute_spec *
lookup_attribute_spec (tree name)
{
  struct substring attr;

  attr.str = IDENTIFIER_POINTER (name);
  attr.length = IDENTIFIER_LENGTH (name);
  extract_attribute_substring (&attr);
  return (const struct attribute_spec *)
    htab_find_with_hash (attribute_hash, &attr,
			 substring_hash (attr.str, attr.length));
}

/* Process the attributes listed in ATTRIBUTES and install them in *NODE,
   which is either a DECL (including a TYPE_DECL) or a TYPE.  If a DECL,
   it should be modified in place; if a TYPE, a copy should be created
   unless ATTR_FLAG_TYPE_IN_PLACE is set in FLAGS.  FLAGS gives further
   information, in the form of a bitwise OR of flags in enum attribute_flags
   from tree.h.  Depending on these flags, some attributes may be
   returned to be applied at a later stage (for example, to apply
   a decl attribute to the declaration rather than to its type).  */

tree
decl_attributes (tree *node, tree attributes, int flags)
{
  tree a;
  tree returned_attrs = NULL_TREE;

  if (TREE_TYPE (*node) == error_mark_node)
    return NULL_TREE;

  if (!attributes_initialized)
    init_attributes ();

  /* If this is a function and the user used #pragma GCC optimize, add the
     options to the attribute((optimize(...))) list.  */
  if (TREE_CODE (*node) == FUNCTION_DECL && current_optimize_pragma)
    {
      tree cur_attr = lookup_attribute ("optimize", attributes);
      tree opts = copy_list (current_optimize_pragma);

      if (! cur_attr)
	attributes
	  = tree_cons (get_identifier ("optimize"), opts, attributes);
      else
	TREE_VALUE (cur_attr) = chainon (opts, TREE_VALUE (cur_attr));
    }

  if (TREE_CODE (*node) == FUNCTION_DECL
      && optimization_current_node != optimization_default_node
      && !DECL_FUNCTION_SPECIFIC_OPTIMIZATION (*node))
    DECL_FUNCTION_SPECIFIC_OPTIMIZATION (*node) = optimization_current_node;

  /* If this is a function and the user used #pragma GCC target, add the
     options to the attribute((target(...))) list.  */
  if (TREE_CODE (*node) == FUNCTION_DECL
      && current_target_pragma
      && targetm.target_option.valid_attribute_p (*node, NULL_TREE,
						  current_target_pragma, 0))
    {
      tree cur_attr = lookup_attribute ("target", attributes);
      tree opts = copy_list (current_target_pragma);

      if (! cur_attr)
	attributes = tree_cons (get_identifier ("target"), opts, attributes);
      else
	TREE_VALUE (cur_attr) = chainon (opts, TREE_VALUE (cur_attr));
    }

  targetm.insert_attributes (*node, &attributes);

  for (a = attributes; a; a = TREE_CHAIN (a))
    {
      tree name = TREE_PURPOSE (a);
      tree args = TREE_VALUE (a);
      tree *anode = node;
      const struct attribute_spec *spec = lookup_attribute_spec (name);
      bool no_add_attrs = 0;
      tree fn_ptr_tmp = NULL_TREE;

      if (spec == NULL)
	{
	  warning (OPT_Wattributes, "%qs attribute directive ignored",
		   IDENTIFIER_POINTER (name));
	  continue;
	}
      else if (list_length (args) < spec->min_length
	       || (spec->max_length >= 0
		   && list_length (args) > spec->max_length))
	{
	  error ("wrong number of arguments specified for %qs attribute",
		 IDENTIFIER_POINTER (name));
	  continue;
	}
      gcc_assert (is_attribute_p (spec->name, name));

      if (spec->decl_required && !DECL_P (*anode))
	{
	  if (flags & ((int) ATTR_FLAG_DECL_NEXT
		       | (int) ATTR_FLAG_FUNCTION_NEXT
		       | (int) ATTR_FLAG_ARRAY_NEXT))
	    {
	      /* Pass on this attribute to be tried again.  */
	      returned_attrs = tree_cons (name, args, returned_attrs);
	      continue;
	    }
	  else
	    {
	      warning (OPT_Wattributes, "%qs attribute does not apply to types",
		       IDENTIFIER_POINTER (name));
	      continue;
	    }
	}

      /* If we require a type, but were passed a decl, set up to make a
	 new type and update the one in the decl.  ATTR_FLAG_TYPE_IN_PLACE
	 would have applied if we'd been passed a type, but we cannot modify
	 the decl's type in place here.  */
      if (spec->type_required && DECL_P (*anode))
	{
	  anode = &TREE_TYPE (*anode);
	  /* Allow ATTR_FLAG_TYPE_IN_PLACE for the type's naming decl.  */
	  if (!(TREE_CODE (*anode) == TYPE_DECL
		&& *anode == TYPE_NAME (TYPE_MAIN_VARIANT
					(TREE_TYPE (*anode)))))
	    flags &= ~(int) ATTR_FLAG_TYPE_IN_PLACE;
	}

      if (spec->function_type_required && TREE_CODE (*anode) != FUNCTION_TYPE
	  && TREE_CODE (*anode) != METHOD_TYPE)
	{
	  if (TREE_CODE (*anode) == POINTER_TYPE
	      && (TREE_CODE (TREE_TYPE (*anode)) == FUNCTION_TYPE
		  || TREE_CODE (TREE_TYPE (*anode)) == METHOD_TYPE))
	    {
	      /* OK, this is a bit convoluted.  We can't just make a copy
		 of the pointer type and modify its TREE_TYPE, because if
		 we change the attributes of the target type the pointer
		 type needs to have a different TYPE_MAIN_VARIANT.  So we
		 pull out the target type now, frob it as appropriate, and
		 rebuild the pointer type later.

		 This would all be simpler if attributes were part of the
		 declarator, grumble grumble.  */
	      fn_ptr_tmp = TREE_TYPE (*anode);
	      anode = &fn_ptr_tmp;
	      flags &= ~(int) ATTR_FLAG_TYPE_IN_PLACE;
	    }
	  else if (flags & (int) ATTR_FLAG_FUNCTION_NEXT)
	    {
	      /* Pass on this attribute to be tried again.  */
	      returned_attrs = tree_cons (name, args, returned_attrs);
	      continue;
	    }

	  if (TREE_CODE (*anode) != FUNCTION_TYPE
	      && TREE_CODE (*anode) != METHOD_TYPE)
	    {
	      warning (OPT_Wattributes,
		       "%qs attribute only applies to function types",
		       IDENTIFIER_POINTER (name));
	      continue;
	    }
	}

      if (TYPE_P (*anode)
	  && (flags & (int) ATTR_FLAG_TYPE_IN_PLACE)
	  && TYPE_SIZE (*anode) != NULL_TREE)
	{
	  warning (OPT_Wattributes, "type attributes ignored after type is already defined");
	  continue;
	}

      if (spec->handler != NULL)
	returned_attrs = chainon ((*spec->handler) (anode, name, args,
						    flags, &no_add_attrs),
				  returned_attrs);

      /* Layout the decl in case anything changed.  */
      if (spec->type_required && DECL_P (*node)
	  && (TREE_CODE (*node) == VAR_DECL
	      || TREE_CODE (*node) == PARM_DECL
	      || TREE_CODE (*node) == RESULT_DECL))
	relayout_decl (*node);

      if (!no_add_attrs)
	{
	  tree old_attrs;
	  tree a;

	  if (DECL_P (*anode))
	    old_attrs = DECL_ATTRIBUTES (*anode);
	  else
	    old_attrs = TYPE_ATTRIBUTES (*anode);

	  for (a = lookup_attribute (spec->name, old_attrs);
	       a != NULL_TREE;
	       a = lookup_attribute (spec->name, TREE_CHAIN (a)))
	    {
	      if (simple_cst_equal (TREE_VALUE (a), args) == 1)
		break;
	    }

	  if (a == NULL_TREE)
	    {
	      /* This attribute isn't already in the list.  */
	      if (DECL_P (*anode))
		DECL_ATTRIBUTES (*anode) = tree_cons (name, args, old_attrs);
	      else if (flags & (int) ATTR_FLAG_TYPE_IN_PLACE)
		{
		  TYPE_ATTRIBUTES (*anode) = tree_cons (name, args, old_attrs);
		  /* If this is the main variant, also push the attributes
		     out to the other variants.  */
		  if (*anode == TYPE_MAIN_VARIANT (*anode))
		    {
		      tree variant;
		      for (variant = *anode; variant;
			   variant = TYPE_NEXT_VARIANT (variant))
			{
			  if (TYPE_ATTRIBUTES (variant) == old_attrs)
			    TYPE_ATTRIBUTES (variant)
			      = TYPE_ATTRIBUTES (*anode);
			  else if (!lookup_attribute
				   (spec->name, TYPE_ATTRIBUTES (variant)))
			    TYPE_ATTRIBUTES (variant) = tree_cons
			      (name, args, TYPE_ATTRIBUTES (variant));
			}
		    }
		}
	      else
		*anode = build_type_attribute_variant (*anode,
						       tree_cons (name, args,
								  old_attrs));
	    }
	}

      if (fn_ptr_tmp)
	{
	  /* Rebuild the function pointer type and put it in the
	     appropriate place.  */
	  fn_ptr_tmp = build_pointer_type (fn_ptr_tmp);
	  if (DECL_P (*node))
	    TREE_TYPE (*node) = fn_ptr_tmp;
	  else
	    {
	      gcc_assert (TREE_CODE (*node) == POINTER_TYPE);
	      *node = fn_ptr_tmp;
	    }
	}
    }

  return returned_attrs;
}