1 /* Functions dealing with attribute handling, used by most front ends.
2 Copyright (C) 1992-2015 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/>. */
22 #include "coretypes.h"
31 #include "stringpool.h"
33 #include "stor-layout.h"
35 #include "diagnostic-core.h"
40 #include "langhooks.h"
41 #include "hash-table.h"
44 /* Table of the tables of attributes (common, language, format, machine)
46 static const struct attribute_spec *attribute_tables[4];
48 /* Substring representation. */
56 /* Simple hash function to avoid need to scan whole string. */
58 static inline hashval_t
59 substring_hash (const char *str, int l)
61 return str[0] + str[l - 1] * 256 + l * 65536;
64 /* Used for attribute_hash. */
66 struct attribute_hasher : typed_noop_remove <attribute_spec>
68 typedef attribute_spec *value_type;
69 typedef substring *compare_type;
70 static inline hashval_t hash (const attribute_spec *);
71 static inline bool equal (const attribute_spec *, const substring *);
75 attribute_hasher::hash (const attribute_spec *spec)
77 const int l = strlen (spec->name);
78 return substring_hash (spec->name, l);
82 attribute_hasher::equal (const attribute_spec *spec, const substring *str)
84 return (strncmp (spec->name, str->str, str->length) == 0
85 && !spec->name[str->length]);
88 /* Scoped attribute name representation. */
90 struct scoped_attributes
93 vec<attribute_spec> attributes;
94 hash_table<attribute_hasher> *attribute_hash;
97 /* The table of scope attributes. */
98 static vec<scoped_attributes> attributes_table;
100 static scoped_attributes* find_attribute_namespace (const char*);
101 static void register_scoped_attribute (const struct attribute_spec *,
102 scoped_attributes *);
104 static bool attributes_initialized = false;
106 /* Default empty table of attributes. */
108 static const struct attribute_spec empty_attribute_table[] =
110 { NULL, 0, 0, false, false, false, NULL, false }
113 /* Return base name of the attribute. Ie '__attr__' is turned into 'attr'.
114 To avoid need for copying, we simply return length of the string. */
117 extract_attribute_substring (struct substring *str)
119 if (str->length > 4 && str->str[0] == '_' && str->str[1] == '_'
120 && str->str[str->length - 1] == '_' && str->str[str->length - 2] == '_')
127 /* Insert an array of attributes ATTRIBUTES into a namespace. This
128 array must be NULL terminated. NS is the name of attribute
129 namespace. The function returns the namespace into which the
130 attributes have been registered. */
133 register_scoped_attributes (const struct attribute_spec * attributes,
136 scoped_attributes *result = NULL;
138 /* See if we already have attributes in the namespace NS. */
139 result = find_attribute_namespace (ns);
143 /* We don't have any namespace NS yet. Create one. */
144 scoped_attributes sa;
146 if (!attributes_table.is_empty ())
147 attributes_table.create (64);
149 memset (&sa, 0, sizeof (sa));
151 sa.attributes.create (64);
152 result = attributes_table.safe_push (sa);
153 result->attribute_hash = new hash_table<attribute_hasher> (200);
156 /* Really add the attributes to their namespace now. */
157 for (unsigned i = 0; attributes[i].name != NULL; ++i)
159 result->attributes.safe_push (attributes[i]);
160 register_scoped_attribute (&attributes[i], result);
163 gcc_assert (result != NULL);
168 /* Return the namespace which name is NS, NULL if none exist. */
170 static scoped_attributes*
171 find_attribute_namespace (const char* ns)
174 scoped_attributes *iter;
176 FOR_EACH_VEC_ELT (attributes_table, ix, iter)
180 && !strcmp (iter->ns, ns)))
185 /* Initialize attribute tables, and make some sanity checks
186 if --enable-checking. */
189 init_attributes (void)
193 if (attributes_initialized)
196 attribute_tables[0] = lang_hooks.common_attribute_table;
197 attribute_tables[1] = lang_hooks.attribute_table;
198 attribute_tables[2] = lang_hooks.format_attribute_table;
199 attribute_tables[3] = targetm.attribute_table;
201 /* Translate NULL pointers to pointers to the empty table. */
202 for (i = 0; i < ARRAY_SIZE (attribute_tables); i++)
203 if (attribute_tables[i] == NULL)
204 attribute_tables[i] = empty_attribute_table;
206 #ifdef ENABLE_CHECKING
207 /* Make some sanity checks on the attribute tables. */
208 for (i = 0; i < ARRAY_SIZE (attribute_tables); i++)
212 for (j = 0; attribute_tables[i][j].name != NULL; j++)
214 /* The name must not begin and end with __. */
215 const char *name = attribute_tables[i][j].name;
216 int len = strlen (name);
218 gcc_assert (!(name[0] == '_' && name[1] == '_'
219 && name[len - 1] == '_' && name[len - 2] == '_'));
221 /* The minimum and maximum lengths must be consistent. */
222 gcc_assert (attribute_tables[i][j].min_length >= 0);
224 gcc_assert (attribute_tables[i][j].max_length == -1
225 || (attribute_tables[i][j].max_length
226 >= attribute_tables[i][j].min_length));
228 /* An attribute cannot require both a DECL and a TYPE. */
229 gcc_assert (!attribute_tables[i][j].decl_required
230 || !attribute_tables[i][j].type_required);
232 /* If an attribute requires a function type, in particular
233 it requires a type. */
234 gcc_assert (!attribute_tables[i][j].function_type_required
235 || attribute_tables[i][j].type_required);
239 /* Check that each name occurs just once in each table. */
240 for (i = 0; i < ARRAY_SIZE (attribute_tables); i++)
243 for (j = 0; attribute_tables[i][j].name != NULL; j++)
244 for (k = j + 1; attribute_tables[i][k].name != NULL; k++)
245 gcc_assert (strcmp (attribute_tables[i][j].name,
246 attribute_tables[i][k].name));
248 /* Check that no name occurs in more than one table. Names that
249 begin with '*' are exempt, and may be overridden. */
250 for (i = 0; i < ARRAY_SIZE (attribute_tables); i++)
254 for (j = i + 1; j < ARRAY_SIZE (attribute_tables); j++)
255 for (k = 0; attribute_tables[i][k].name != NULL; k++)
256 for (l = 0; attribute_tables[j][l].name != NULL; l++)
257 gcc_assert (attribute_tables[i][k].name[0] == '*'
258 || strcmp (attribute_tables[i][k].name,
259 attribute_tables[j][l].name));
263 for (i = 0; i < ARRAY_SIZE (attribute_tables); ++i)
264 /* Put all the GNU attributes into the "gnu" namespace. */
265 register_scoped_attributes (attribute_tables[i], "gnu");
267 invoke_plugin_callbacks (PLUGIN_ATTRIBUTES, NULL);
268 attributes_initialized = true;
271 /* Insert a single ATTR into the attribute table. */
274 register_attribute (const struct attribute_spec *attr)
276 register_scoped_attribute (attr, find_attribute_namespace ("gnu"));
279 /* Insert a single attribute ATTR into a namespace of attributes. */
282 register_scoped_attribute (const struct attribute_spec *attr,
283 scoped_attributes *name_space)
285 struct substring str;
286 attribute_spec **slot;
288 gcc_assert (attr != NULL && name_space != NULL);
290 gcc_assert (name_space->attribute_hash);
292 str.str = attr->name;
293 str.length = strlen (str.str);
295 /* Attribute names in the table must be in the form 'text' and not
296 in the form '__text__'. */
297 gcc_assert (str.length > 0 && str.str[0] != '_');
299 slot = name_space->attribute_hash
300 ->find_slot_with_hash (&str, substring_hash (str.str, str.length),
302 gcc_assert (!*slot || attr->name[0] == '*');
303 *slot = CONST_CAST (struct attribute_spec *, attr);
306 /* Return the spec for the scoped attribute with namespace NS and
309 static const struct attribute_spec *
310 lookup_scoped_attribute_spec (const_tree ns, const_tree name)
312 struct substring attr;
313 scoped_attributes *attrs;
315 const char *ns_str = (ns != NULL_TREE) ? IDENTIFIER_POINTER (ns): NULL;
317 attrs = find_attribute_namespace (ns_str);
322 attr.str = IDENTIFIER_POINTER (name);
323 attr.length = IDENTIFIER_LENGTH (name);
324 extract_attribute_substring (&attr);
325 return attrs->attribute_hash->find_with_hash (&attr,
326 substring_hash (attr.str,
330 /* Return the spec for the attribute named NAME. If NAME is a TREE_LIST,
331 it also specifies the attribute namespace. */
333 const struct attribute_spec *
334 lookup_attribute_spec (const_tree name)
337 if (TREE_CODE (name) == TREE_LIST)
339 ns = TREE_PURPOSE (name);
340 name = TREE_VALUE (name);
343 ns = get_identifier ("gnu");
344 return lookup_scoped_attribute_spec (ns, name);
348 /* Return the namespace of the attribute ATTR. This accessor works on
349 GNU and C++11 (scoped) attributes. On GNU attributes,
350 it returns an identifier tree for the string "gnu".
352 Please read the comments of cxx11_attribute_p to understand the
353 format of attributes. */
356 get_attribute_namespace (const_tree attr)
358 if (cxx11_attribute_p (attr))
359 return TREE_PURPOSE (TREE_PURPOSE (attr));
360 return get_identifier ("gnu");
364 /* Process the attributes listed in ATTRIBUTES and install them in *NODE,
365 which is either a DECL (including a TYPE_DECL) or a TYPE. If a DECL,
366 it should be modified in place; if a TYPE, a copy should be created
367 unless ATTR_FLAG_TYPE_IN_PLACE is set in FLAGS. FLAGS gives further
368 information, in the form of a bitwise OR of flags in enum attribute_flags
369 from tree.h. Depending on these flags, some attributes may be
370 returned to be applied at a later stage (for example, to apply
371 a decl attribute to the declaration rather than to its type). */
374 decl_attributes (tree *node, tree attributes, int flags)
377 tree returned_attrs = NULL_TREE;
379 if (TREE_TYPE (*node) == error_mark_node || attributes == error_mark_node)
382 if (!attributes_initialized)
385 /* If this is a function and the user used #pragma GCC optimize, add the
386 options to the attribute((optimize(...))) list. */
387 if (TREE_CODE (*node) == FUNCTION_DECL && current_optimize_pragma)
389 tree cur_attr = lookup_attribute ("optimize", attributes);
390 tree opts = copy_list (current_optimize_pragma);
394 = tree_cons (get_identifier ("optimize"), opts, attributes);
396 TREE_VALUE (cur_attr) = chainon (opts, TREE_VALUE (cur_attr));
399 if (TREE_CODE (*node) == FUNCTION_DECL
400 && optimization_current_node != optimization_default_node
401 && !DECL_FUNCTION_SPECIFIC_OPTIMIZATION (*node))
402 DECL_FUNCTION_SPECIFIC_OPTIMIZATION (*node) = optimization_current_node;
404 /* If this is a function and the user used #pragma GCC target, add the
405 options to the attribute((target(...))) list. */
406 if (TREE_CODE (*node) == FUNCTION_DECL
407 && current_target_pragma
408 && targetm.target_option.valid_attribute_p (*node, NULL_TREE,
409 current_target_pragma, 0))
411 tree cur_attr = lookup_attribute ("target", attributes);
412 tree opts = copy_list (current_target_pragma);
415 attributes = tree_cons (get_identifier ("target"), opts, attributes);
417 TREE_VALUE (cur_attr) = chainon (opts, TREE_VALUE (cur_attr));
420 /* A "naked" function attribute implies "noinline" and "noclone" for
421 those targets that support it. */
422 if (TREE_CODE (*node) == FUNCTION_DECL
424 && lookup_attribute_spec (get_identifier ("naked"))
425 && lookup_attribute ("naked", attributes) != NULL)
427 if (lookup_attribute ("noinline", attributes) == NULL)
428 attributes = tree_cons (get_identifier ("noinline"), NULL, attributes);
430 if (lookup_attribute ("noclone", attributes) == NULL)
431 attributes = tree_cons (get_identifier ("noclone"), NULL, attributes);
434 targetm.insert_attributes (*node, &attributes);
436 for (a = attributes; a; a = TREE_CHAIN (a))
438 tree ns = get_attribute_namespace (a);
439 tree name = get_attribute_name (a);
440 tree args = TREE_VALUE (a);
442 const struct attribute_spec *spec =
443 lookup_scoped_attribute_spec (ns, name);
444 bool no_add_attrs = 0;
445 int fn_ptr_quals = 0;
446 tree fn_ptr_tmp = NULL_TREE;
450 if (!(flags & (int) ATTR_FLAG_BUILT_IN))
452 if (ns == NULL_TREE || !cxx11_attribute_p (a))
453 warning (OPT_Wattributes, "%qE attribute directive ignored",
456 warning (OPT_Wattributes,
457 "%<%E::%E%> scoped attribute directive ignored",
462 else if (list_length (args) < spec->min_length
463 || (spec->max_length >= 0
464 && list_length (args) > spec->max_length))
466 error ("wrong number of arguments specified for %qE attribute",
470 gcc_assert (is_attribute_p (spec->name, name));
473 && cxx11_attribute_p (a)
474 && !(flags & ATTR_FLAG_TYPE_IN_PLACE))
476 /* This is a c++11 attribute that appertains to a
477 type-specifier, outside of the definition of, a class
479 warning (OPT_Wattributes, "attribute ignored");
480 inform (input_location,
481 "an attribute that appertains to a type-specifier "
486 if (spec->decl_required && !DECL_P (*anode))
488 if (flags & ((int) ATTR_FLAG_DECL_NEXT
489 | (int) ATTR_FLAG_FUNCTION_NEXT
490 | (int) ATTR_FLAG_ARRAY_NEXT))
492 /* Pass on this attribute to be tried again. */
493 returned_attrs = tree_cons (name, args, returned_attrs);
498 warning (OPT_Wattributes, "%qE attribute does not apply to types",
504 /* If we require a type, but were passed a decl, set up to make a
505 new type and update the one in the decl. ATTR_FLAG_TYPE_IN_PLACE
506 would have applied if we'd been passed a type, but we cannot modify
507 the decl's type in place here. */
508 if (spec->type_required && DECL_P (*anode))
510 anode = &TREE_TYPE (*anode);
511 flags &= ~(int) ATTR_FLAG_TYPE_IN_PLACE;
514 if (spec->function_type_required && TREE_CODE (*anode) != FUNCTION_TYPE
515 && TREE_CODE (*anode) != METHOD_TYPE)
517 if (TREE_CODE (*anode) == POINTER_TYPE
518 && (TREE_CODE (TREE_TYPE (*anode)) == FUNCTION_TYPE
519 || TREE_CODE (TREE_TYPE (*anode)) == METHOD_TYPE))
521 /* OK, this is a bit convoluted. We can't just make a copy
522 of the pointer type and modify its TREE_TYPE, because if
523 we change the attributes of the target type the pointer
524 type needs to have a different TYPE_MAIN_VARIANT. So we
525 pull out the target type now, frob it as appropriate, and
526 rebuild the pointer type later.
528 This would all be simpler if attributes were part of the
529 declarator, grumble grumble. */
530 fn_ptr_tmp = TREE_TYPE (*anode);
531 fn_ptr_quals = TYPE_QUALS (*anode);
533 flags &= ~(int) ATTR_FLAG_TYPE_IN_PLACE;
535 else if (flags & (int) ATTR_FLAG_FUNCTION_NEXT)
537 /* Pass on this attribute to be tried again. */
538 returned_attrs = tree_cons (name, args, returned_attrs);
542 if (TREE_CODE (*anode) != FUNCTION_TYPE
543 && TREE_CODE (*anode) != METHOD_TYPE)
545 warning (OPT_Wattributes,
546 "%qE attribute only applies to function types",
553 && (flags & (int) ATTR_FLAG_TYPE_IN_PLACE)
554 && TYPE_SIZE (*anode) != NULL_TREE)
556 warning (OPT_Wattributes, "type attributes ignored after type is already defined");
560 if (spec->handler != NULL)
563 cxx11_attribute_p (a) ? ATTR_FLAG_CXX11 : 0;
565 returned_attrs = chainon ((*spec->handler) (anode, name, args,
571 /* Layout the decl in case anything changed. */
572 if (spec->type_required && DECL_P (*node)
573 && (TREE_CODE (*node) == VAR_DECL
574 || TREE_CODE (*node) == PARM_DECL
575 || TREE_CODE (*node) == RESULT_DECL))
576 relayout_decl (*node);
584 old_attrs = DECL_ATTRIBUTES (*anode);
586 old_attrs = TYPE_ATTRIBUTES (*anode);
588 for (a = lookup_attribute (spec->name, old_attrs);
590 a = lookup_attribute (spec->name, TREE_CHAIN (a)))
592 if (simple_cst_equal (TREE_VALUE (a), args) == 1)
598 /* This attribute isn't already in the list. */
600 DECL_ATTRIBUTES (*anode) = tree_cons (name, args, old_attrs);
601 else if (flags & (int) ATTR_FLAG_TYPE_IN_PLACE)
603 TYPE_ATTRIBUTES (*anode) = tree_cons (name, args, old_attrs);
604 /* If this is the main variant, also push the attributes
605 out to the other variants. */
606 if (*anode == TYPE_MAIN_VARIANT (*anode))
609 for (variant = *anode; variant;
610 variant = TYPE_NEXT_VARIANT (variant))
612 if (TYPE_ATTRIBUTES (variant) == old_attrs)
613 TYPE_ATTRIBUTES (variant)
614 = TYPE_ATTRIBUTES (*anode);
615 else if (!lookup_attribute
616 (spec->name, TYPE_ATTRIBUTES (variant)))
617 TYPE_ATTRIBUTES (variant) = tree_cons
618 (name, args, TYPE_ATTRIBUTES (variant));
623 *anode = build_type_attribute_variant (*anode,
624 tree_cons (name, args,
631 /* Rebuild the function pointer type and put it in the
632 appropriate place. */
633 fn_ptr_tmp = build_pointer_type (fn_ptr_tmp);
635 fn_ptr_tmp = build_qualified_type (fn_ptr_tmp, fn_ptr_quals);
637 TREE_TYPE (*node) = fn_ptr_tmp;
640 gcc_assert (TREE_CODE (*node) == POINTER_TYPE);
646 return returned_attrs;
649 /* Return TRUE iff ATTR has been parsed by the front-end as a C++-11
652 When G++ parses a C++11 attribute, it is represented as
653 a TREE_LIST which TREE_PURPOSE is itself a TREE_LIST. TREE_PURPOSE
654 (TREE_PURPOSE (ATTR)) is the namespace of the attribute, and the
655 TREE_VALUE (TREE_PURPOSE (ATTR)) is its non-qualified name. Please
656 use get_attribute_namespace and get_attribute_name to retrieve the
657 namespace and name of the attribute, as these accessors work with
658 GNU attributes as well. */
661 cxx11_attribute_p (const_tree attr)
663 if (attr == NULL_TREE
664 || TREE_CODE (attr) != TREE_LIST)
667 return (TREE_CODE (TREE_PURPOSE (attr)) == TREE_LIST);
670 /* Return the name of the attribute ATTR. This accessor works on GNU
671 and C++11 (scoped) attributes.
673 Please read the comments of cxx11_attribute_p to understand the
674 format of attributes. */
677 get_attribute_name (const_tree attr)
679 if (cxx11_attribute_p (attr))
680 return TREE_VALUE (TREE_PURPOSE (attr));
681 return TREE_PURPOSE (attr);
684 /* Subroutine of set_method_tm_attributes. Apply TM attribute ATTR
685 to the method FNDECL. */
688 apply_tm_attr (tree fndecl, tree attr)
690 decl_attributes (&TREE_TYPE (fndecl), tree_cons (attr, NULL, NULL), 0);