gcc/attribs.c

   1 /* Functions dealing with attribute handling, used by most front ends.
   2    Copyright (C) 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001,
   3    2002, 2003, 2004, 2005, 2007, 2008, 2009, 2010
   4    Free Software Foundation, Inc.
   5
   6 This file is part of GCC.
   7
   8 GCC is free software; you can redistribute it and/or modify it under
   9 the terms of the GNU General Public License as published by the Free
  10 Software Foundation; either version 3, or (at your option) any later
  11 version.
  12
  13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  15 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  16 for more details.
  17
  18 You should have received a copy of the GNU General Public License
  19 along with GCC; see the file COPYING3.  If not see
  20 <http://www.gnu.org/licenses/>.  */
  21
  22 #include "config.h"
  23 #include "system.h"
  24 #include "coretypes.h"
  25 #include "tm.h"
  26 #include "tree.h"
  27 #include "flags.h"
  28 #include "diagnostic-core.h"
  29 #include "ggc.h"
  30 #include "tm_p.h"
  31 #include "cpplib.h"
  32 #include "target.h"
  33 #include "langhooks.h"
  34 #include "hashtab.h"
  35 #include "plugin.h"
  36
  37 /* Table of the tables of attributes (common, language, format, machine)
  38    searched.  */
  39 static const struct attribute_spec *attribute_tables[4];
  40
  41 /* Substring representation.  */
  42
  43 struct substring
  44 {
  45   const char *str;
  46   int length;
  47 };
  48
  49 /* Scoped attribute name representation.  */
  50
  51 struct scoped_attributes
  52 {
  53   const char *ns;
  54   vec<attribute_spec> attributes;
  55   htab_t attribute_hash;
  56 };
  57
  58 /* The table of scope attributes.  */
  59 static vec<scoped_attributes> attributes_table;
  60
  61 static scoped_attributes* find_attribute_namespace (const char*);
  62 static void register_scoped_attribute (const struct attribute_spec *,
  63                                        scoped_attributes *);
  64
  65 static bool attributes_initialized = false;
  66
  67 /* Default empty table of attributes.  */
  68
  69 static const struct attribute_spec empty_attribute_table[] =
  70 {
  71   { NULL, 0, 0, false, false, false, NULL, false }
  72 };
  73
  74 /* Return base name of the attribute.  Ie '__attr__' is turned into 'attr'.
  75    To avoid need for copying, we simply return length of the string.  */
  76
  77 static void
  78 extract_attribute_substring (struct substring *str)
  79 {
  80   if (str->length > 4 && str->str[0] == '_' && str->str[1] == '_'
  81       && str->str[str->length - 1] == '_' && str->str[str->length - 2] == '_')
  82     {
  83       str->length -= 4;
  84       str->str += 2;
  85     }
  86 }
  87
  88 /* Simple hash function to avoid need to scan whole string.  */
  89
  90 static inline hashval_t
  91 substring_hash (const char *str, int l)
  92 {
  93   return str[0] + str[l - 1] * 256 + l * 65536;
  94 }
  95
  96 /* Used for attribute_hash.  */
  97
  98 static hashval_t
  99 hash_attr (const void *p)
 100 {
 101   const struct attribute_spec *const spec = (const struct attribute_spec *) p;
 102   const int l = strlen (spec->name);
 103
 104   return substring_hash (spec->name, l);
 105 }
 106
 107 /* Used for attribute_hash.  */
 108
 109 static int
 110 eq_attr (const void *p, const void *q)
 111 {
 112   const struct attribute_spec *const spec = (const struct attribute_spec *) p;
 113   const struct substring *const str = (const struct substring *) q;
 114
 115   return (!strncmp (spec->name, str->str, str->length) && !spec->name[str->length]);
 116 }
 117
 118 /* Insert an array of attributes ATTRIBUTES into a namespace.  This
 119    array must be NULL terminated.  NS is the name of attribute
 120    namespace.  The function returns the namespace into which the
 121    attributes have been registered.  */
 122
 123 scoped_attributes*
 124 register_scoped_attributes (const struct attribute_spec * attributes,
 125                             const char* ns)
 126 {
 127   scoped_attributes *result = NULL;
 128
 129   /* See if we already have attributes in the namespace NS.  */
 130   result = find_attribute_namespace (ns);
 131
 132   if (result == NULL)
 133     {
 134       /* We don't have any namespace NS yet.  Create one.  */
 135       scoped_attributes sa;
 136
 137       if (!attributes_table.is_empty ())
 138         attributes_table.create (64);
 139
 140       memset (&sa, 0, sizeof (sa));
 141       sa.ns = ns;
 142       sa.attributes.create (64);
 143       result = attributes_table.safe_push (sa);
 144       result->attribute_hash = htab_create (200, hash_attr, eq_attr, NULL);
 145     }
 146
 147   /* Really add the attributes to their namespace now.  */
 148   for (unsigned i = 0; attributes[i].name != NULL; ++i)
 149     {
 150       result->attributes.safe_push (attributes[i]);
 151       register_scoped_attribute (&attributes[i], result);
 152     }
 153
 154   gcc_assert (result != NULL);
 155
 156   return result;
 157 }
 158
 159 /* Return the namespace which name is NS, NULL if none exist.  */
 160
 161 static scoped_attributes*
 162 find_attribute_namespace (const char* ns)
 163 {
 164   unsigned ix;
 165   scoped_attributes *iter;
 166
 167   FOR_EACH_VEC_ELT (attributes_table, ix, iter)
 168     if (ns == iter->ns
 169         || (iter->ns != NULL
 170             && ns != NULL
 171             && !strcmp (iter->ns, ns)))
 172       return iter;
 173   return NULL;
 174 }
 175
 176 /* Initialize attribute tables, and make some sanity checks
 177    if --enable-checking.  */
 178
 179 void
 180 init_attributes (void)
 181 {
 182   size_t i;
 183
 184   if (attributes_initialized)
 185     return;
 186
 187   attribute_tables[0] = lang_hooks.common_attribute_table;
 188   attribute_tables[1] = lang_hooks.attribute_table;
 189   attribute_tables[2] = lang_hooks.format_attribute_table;
 190   attribute_tables[3] = targetm.attribute_table;
 191
 192   /* Translate NULL pointers to pointers to the empty table.  */
 193   for (i = 0; i < ARRAY_SIZE (attribute_tables); i++)
 194     if (attribute_tables[i] == NULL)
 195       attribute_tables[i] = empty_attribute_table;
 196
 197 #ifdef ENABLE_CHECKING
 198   /* Make some sanity checks on the attribute tables.  */
 199   for (i = 0; i < ARRAY_SIZE (attribute_tables); i++)
 200     {
 201       int j;
 202
 203       for (j = 0; attribute_tables[i][j].name != NULL; j++)
 204         {
 205           /* The name must not begin and end with __.  */
 206           const char *name = attribute_tables[i][j].name;
 207           int len = strlen (name);
 208
 209           gcc_assert (!(name[0] == '_' && name[1] == '_'
 210                         && name[len - 1] == '_' && name[len - 2] == '_'));
 211
 212           /* The minimum and maximum lengths must be consistent.  */
 213           gcc_assert (attribute_tables[i][j].min_length >= 0);
 214
 215           gcc_assert (attribute_tables[i][j].max_length == -1
 216                       || (attribute_tables[i][j].max_length
 217                           >= attribute_tables[i][j].min_length));
 218
 219           /* An attribute cannot require both a DECL and a TYPE.  */
 220           gcc_assert (!attribute_tables[i][j].decl_required
 221                       || !attribute_tables[i][j].type_required);
 222
 223           /* If an attribute requires a function type, in particular
 224              it requires a type.  */
 225           gcc_assert (!attribute_tables[i][j].function_type_required
 226                       || attribute_tables[i][j].type_required);
 227         }
 228     }
 229
 230   /* Check that each name occurs just once in each table.  */
 231   for (i = 0; i < ARRAY_SIZE (attribute_tables); i++)
 232     {
 233       int j, k;
 234       for (j = 0; attribute_tables[i][j].name != NULL; j++)
 235         for (k = j + 1; attribute_tables[i][k].name != NULL; k++)
 236           gcc_assert (strcmp (attribute_tables[i][j].name,
 237                               attribute_tables[i][k].name));
 238     }
 239   /* Check that no name occurs in more than one table.  Names that
 240      begin with '*' are exempt, and may be overridden.  */
 241   for (i = 0; i < ARRAY_SIZE (attribute_tables); i++)
 242     {
 243       size_t j, k, l;
 244
 245       for (j = i + 1; j < ARRAY_SIZE (attribute_tables); j++)
 246         for (k = 0; attribute_tables[i][k].name != NULL; k++)
 247           for (l = 0; attribute_tables[j][l].name != NULL; l++)
 248             gcc_assert (attribute_tables[i][k].name[0] == '*'
 249                         || strcmp (attribute_tables[i][k].name,
 250                                    attribute_tables[j][l].name));
 251     }
 252 #endif
 253
 254   for (i = 0; i < ARRAY_SIZE (attribute_tables); ++i)
 255     /* Put all the GNU attributes into the "gnu" namespace.  */
 256     register_scoped_attributes (attribute_tables[i], "gnu");
 257
 258   invoke_plugin_callbacks (PLUGIN_ATTRIBUTES, NULL);
 259   attributes_initialized = true;
 260 }
 261
 262 /* Insert a single ATTR into the attribute table.  */
 263
 264 void
 265 register_attribute (const struct attribute_spec *attr)
 266 {
 267   register_scoped_attribute (attr, find_attribute_namespace ("gnu"));
 268 }
 269
 270 /* Insert a single attribute ATTR into a namespace of attributes.  */
 271
 272 static void
 273 register_scoped_attribute (const struct attribute_spec *attr,
 274                            scoped_attributes *name_space)
 275 {
 276   struct substring str;
 277   void **slot;
 278
 279   gcc_assert (attr != NULL && name_space != NULL);
 280
 281   gcc_assert (name_space->attribute_hash != NULL);
 282
 283   str.str = attr->name;
 284   str.length = strlen (str.str);
 285
 286   /* Attribute names in the table must be in the form 'text' and not
 287      in the form '__text__'.  */
 288   gcc_assert (str.length > 0 && str.str[0] != '_');
 289
 290   slot = htab_find_slot_with_hash (name_space->attribute_hash, &str,
 291                                    substring_hash (str.str, str.length),
 292                                    INSERT);
 293   gcc_assert (!*slot || attr->name[0] == '*');
 294   *slot = (void *) CONST_CAST (struct attribute_spec *, attr);
 295 }
 296
 297 /* Return the spec for the scoped attribute with namespace NS and
 298    name NAME.   */
 299
 300 const struct attribute_spec *
 301 lookup_scoped_attribute_spec (const_tree ns, const_tree name)
 302 {
 303   struct substring attr;
 304   scoped_attributes *attrs;
 305
 306   const char *ns_str = (ns != NULL_TREE) ? IDENTIFIER_POINTER (ns): NULL;
 307
 308   attrs = find_attribute_namespace (ns_str);
 309
 310   if (attrs == NULL)
 311     return NULL;
 312
 313   attr.str = IDENTIFIER_POINTER (name);
 314   attr.length = IDENTIFIER_LENGTH (name);
 315   extract_attribute_substring (&attr);
 316   return (const struct attribute_spec *)
 317     htab_find_with_hash (attrs->attribute_hash, &attr,
 318                          substring_hash (attr.str, attr.length));
 319 }
 320
 321 /* Return the spec for the attribute named NAME.  If NAME is a TREE_LIST,
 322    it also specifies the attribute namespace.  */
 323
 324 const struct attribute_spec *
 325 lookup_attribute_spec (const_tree name)
 326 {
 327   tree ns;
 328   if (TREE_CODE (name) == TREE_LIST)
 329     {
 330       ns = TREE_PURPOSE (name);
 331       name = TREE_VALUE (name);
 332     }
 333   else
 334     ns = get_identifier ("gnu");
 335   return lookup_scoped_attribute_spec (ns, name);
 336 }
 337
 338 \f
 339 /* Process the attributes listed in ATTRIBUTES and install them in *NODE,
 340    which is either a DECL (including a TYPE_DECL) or a TYPE.  If a DECL,
 341    it should be modified in place; if a TYPE, a copy should be created
 342    unless ATTR_FLAG_TYPE_IN_PLACE is set in FLAGS.  FLAGS gives further
 343    information, in the form of a bitwise OR of flags in enum attribute_flags
 344    from tree.h.  Depending on these flags, some attributes may be
 345    returned to be applied at a later stage (for example, to apply
 346    a decl attribute to the declaration rather than to its type).  */
 347
 348 tree
 349 decl_attributes (tree *node, tree attributes, int flags)
 350 {
 351   tree a;
 352   tree returned_attrs = NULL_TREE;
 353
 354   if (TREE_TYPE (*node) == error_mark_node || attributes == error_mark_node)
 355     return NULL_TREE;
 356
 357   if (!attributes_initialized)
 358     init_attributes ();
 359
 360   /* If this is a function and the user used #pragma GCC optimize, add the
 361      options to the attribute((optimize(...))) list.  */
 362   if (TREE_CODE (*node) == FUNCTION_DECL && current_optimize_pragma)
 363     {
 364       tree cur_attr = lookup_attribute ("optimize", attributes);
 365       tree opts = copy_list (current_optimize_pragma);
 366
 367       if (! cur_attr)
 368         attributes
 369           = tree_cons (get_identifier ("optimize"), opts, attributes);
 370       else
 371         TREE_VALUE (cur_attr) = chainon (opts, TREE_VALUE (cur_attr));
 372     }
 373
 374   if (TREE_CODE (*node) == FUNCTION_DECL
 375       && optimization_current_node != optimization_default_node
 376       && !DECL_FUNCTION_SPECIFIC_OPTIMIZATION (*node))
 377     DECL_FUNCTION_SPECIFIC_OPTIMIZATION (*node) = optimization_current_node;
 378
 379   /* If this is a function and the user used #pragma GCC target, add the
 380      options to the attribute((target(...))) list.  */
 381   if (TREE_CODE (*node) == FUNCTION_DECL
 382       && current_target_pragma
 383       && targetm.target_option.valid_attribute_p (*node, NULL_TREE,
 384                                                   current_target_pragma, 0))
 385     {
 386       tree cur_attr = lookup_attribute ("target", attributes);
 387       tree opts = copy_list (current_target_pragma);
 388
 389       if (! cur_attr)
 390         attributes = tree_cons (get_identifier ("target"), opts, attributes);
 391       else
 392         TREE_VALUE (cur_attr) = chainon (opts, TREE_VALUE (cur_attr));
 393     }
 394
 395   /* A "naked" function attribute implies "noinline" and "noclone" for
 396      those targets that support it.  */
 397   if (TREE_CODE (*node) == FUNCTION_DECL
 398       && attributes
 399       && lookup_attribute_spec (get_identifier ("naked"))
 400       && lookup_attribute ("naked", attributes) != NULL)
 401     {
 402       if (lookup_attribute ("noinline", attributes) == NULL)
 403         attributes = tree_cons (get_identifier ("noinline"), NULL, attributes);
 404
 405       if (lookup_attribute ("noclone", attributes) == NULL)
 406         attributes = tree_cons (get_identifier ("noclone"),  NULL, attributes);
 407     }
 408
 409   targetm.insert_attributes (*node, &attributes);
 410
 411   for (a = attributes; a; a = TREE_CHAIN (a))
 412     {
 413       tree ns = get_attribute_namespace (a);
 414       tree name = get_attribute_name (a);
 415       tree args = TREE_VALUE (a);
 416       tree *anode = node;
 417       const struct attribute_spec *spec =
 418         lookup_scoped_attribute_spec (ns, name);
 419       bool no_add_attrs = 0;
 420       int fn_ptr_quals = 0;
 421       tree fn_ptr_tmp = NULL_TREE;
 422
 423       if (spec == NULL)
 424         {
 425           if (!(flags & (int) ATTR_FLAG_BUILT_IN))
 426             {
 427               if (ns == NULL_TREE || !cxx11_attribute_p (a))
 428                 warning (OPT_Wattributes, "%qE attribute directive ignored",
 429                          name);
 430               else
 431                 warning (OPT_Wattributes,
 432                          "%<%E::%E%> scoped attribute directive ignored",
 433                          ns, name);
 434             }
 435           continue;
 436         }
 437       else if (list_length (args) < spec->min_length
 438                || (spec->max_length >= 0
 439                    && list_length (args) > spec->max_length))
 440         {
 441           error ("wrong number of arguments specified for %qE attribute",
 442                  name);
 443           continue;
 444         }
 445       gcc_assert (is_attribute_p (spec->name, name));
 446
 447       if (TYPE_P (*node)
 448           && cxx11_attribute_p (a)
 449           && !(flags & ATTR_FLAG_TYPE_IN_PLACE))
 450         {
 451           /* This is a c++11 attribute that appertains to a
 452              type-specifier, outside of the definition of, a class
 453              type.  Ignore it.  */
 454           warning (OPT_Wattributes, "attribute ignored");
 455           inform (input_location,
 456                   "an attribute that appertains to a type-specifier "
 457                   "is ignored");
 458           continue;
 459         }
 460
 461       if (spec->decl_required && !DECL_P (*anode))
 462         {
 463           if (flags & ((int) ATTR_FLAG_DECL_NEXT
 464                        | (int) ATTR_FLAG_FUNCTION_NEXT
 465                        | (int) ATTR_FLAG_ARRAY_NEXT))
 466             {
 467               /* Pass on this attribute to be tried again.  */
 468               returned_attrs = tree_cons (name, args, returned_attrs);
 469               continue;
 470             }
 471           else
 472             {
 473               warning (OPT_Wattributes, "%qE attribute does not apply to types",
 474                        name);
 475               continue;
 476             }
 477         }
 478
 479       /* If we require a type, but were passed a decl, set up to make a
 480          new type and update the one in the decl.  ATTR_FLAG_TYPE_IN_PLACE
 481          would have applied if we'd been passed a type, but we cannot modify
 482          the decl's type in place here.  */
 483       if (spec->type_required && DECL_P (*anode))
 484         {
 485           anode = &TREE_TYPE (*anode);
 486           /* Allow ATTR_FLAG_TYPE_IN_PLACE for the type's naming decl.  */
 487           if (!(TREE_CODE (*anode) == TYPE_DECL
 488                 && *anode == TYPE_NAME (TYPE_MAIN_VARIANT
 489                                         (TREE_TYPE (*anode)))))
 490             flags &= ~(int) ATTR_FLAG_TYPE_IN_PLACE;
 491         }
 492
 493       if (spec->function_type_required && TREE_CODE (*anode) != FUNCTION_TYPE
 494           && TREE_CODE (*anode) != METHOD_TYPE)
 495         {
 496           if (TREE_CODE (*anode) == POINTER_TYPE
 497               && (TREE_CODE (TREE_TYPE (*anode)) == FUNCTION_TYPE
 498                   || TREE_CODE (TREE_TYPE (*anode)) == METHOD_TYPE))
 499             {
 500               /* OK, this is a bit convoluted.  We can't just make a copy
 501                  of the pointer type and modify its TREE_TYPE, because if
 502                  we change the attributes of the target type the pointer
 503                  type needs to have a different TYPE_MAIN_VARIANT.  So we
 504                  pull out the target type now, frob it as appropriate, and
 505                  rebuild the pointer type later.
 506
 507                  This would all be simpler if attributes were part of the
 508                  declarator, grumble grumble.  */
 509               fn_ptr_tmp = TREE_TYPE (*anode);
 510               fn_ptr_quals = TYPE_QUALS (*anode);
 511               anode = &fn_ptr_tmp;
 512               flags &= ~(int) ATTR_FLAG_TYPE_IN_PLACE;
 513             }
 514           else if (flags & (int) ATTR_FLAG_FUNCTION_NEXT)
 515             {
 516               /* Pass on this attribute to be tried again.  */
 517               returned_attrs = tree_cons (name, args, returned_attrs);
 518               continue;
 519             }
 520
 521           if (TREE_CODE (*anode) != FUNCTION_TYPE
 522               && TREE_CODE (*anode) != METHOD_TYPE)
 523             {
 524               warning (OPT_Wattributes,
 525                        "%qE attribute only applies to function types",
 526                        name);
 527               continue;
 528             }
 529         }
 530
 531       if (TYPE_P (*anode)
 532           && (flags & (int) ATTR_FLAG_TYPE_IN_PLACE)
 533           && TYPE_SIZE (*anode) != NULL_TREE)
 534         {
 535           warning (OPT_Wattributes, "type attributes ignored after type is already defined");
 536           continue;
 537         }
 538
 539       if (spec->handler != NULL)
 540         {
 541           int cxx11_flag =
 542             cxx11_attribute_p (a) ? ATTR_FLAG_CXX11 : 0;
 543
 544           returned_attrs = chainon ((*spec->handler) (anode, name, args,
 545                                                       flags|cxx11_flag,
 546                                                       &no_add_attrs),
 547                                     returned_attrs);
 548         }
 549
 550       /* Layout the decl in case anything changed.  */
 551       if (spec->type_required && DECL_P (*node)
 552           && (TREE_CODE (*node) == VAR_DECL
 553               || TREE_CODE (*node) == PARM_DECL
 554               || TREE_CODE (*node) == RESULT_DECL))
 555         relayout_decl (*node);
 556
 557       if (!no_add_attrs)
 558         {
 559           tree old_attrs;
 560           tree a;
 561
 562           if (DECL_P (*anode))
 563             old_attrs = DECL_ATTRIBUTES (*anode);
 564           else
 565             old_attrs = TYPE_ATTRIBUTES (*anode);
 566
 567           for (a = lookup_attribute (spec->name, old_attrs);
 568                a != NULL_TREE;
 569                a = lookup_attribute (spec->name, TREE_CHAIN (a)))
 570             {
 571               if (simple_cst_equal (TREE_VALUE (a), args) == 1)
 572                 break;
 573             }
 574
 575           if (a == NULL_TREE)
 576             {
 577               /* This attribute isn't already in the list.  */
 578               if (DECL_P (*anode))
 579                 DECL_ATTRIBUTES (*anode) = tree_cons (name, args, old_attrs);
 580               else if (flags & (int) ATTR_FLAG_TYPE_IN_PLACE)
 581                 {
 582                   TYPE_ATTRIBUTES (*anode) = tree_cons (name, args, old_attrs);
 583                   /* If this is the main variant, also push the attributes
 584                      out to the other variants.  */
 585                   if (*anode == TYPE_MAIN_VARIANT (*anode))
 586                     {
 587                       tree variant;
 588                       for (variant = *anode; variant;
 589                            variant = TYPE_NEXT_VARIANT (variant))
 590                         {
 591                           if (TYPE_ATTRIBUTES (variant) == old_attrs)
 592                             TYPE_ATTRIBUTES (variant)
 593                               = TYPE_ATTRIBUTES (*anode);
 594                           else if (!lookup_attribute
 595                                    (spec->name, TYPE_ATTRIBUTES (variant)))
 596                             TYPE_ATTRIBUTES (variant) = tree_cons
 597                               (name, args, TYPE_ATTRIBUTES (variant));
 598                         }
 599                     }
 600                 }
 601               else
 602                 *anode = build_type_attribute_variant (*anode,
 603                                                        tree_cons (name, args,
 604                                                                   old_attrs));
 605             }
 606         }
 607
 608       if (fn_ptr_tmp)
 609         {
 610           /* Rebuild the function pointer type and put it in the
 611              appropriate place.  */
 612           fn_ptr_tmp = build_pointer_type (fn_ptr_tmp);
 613           if (fn_ptr_quals)
 614             fn_ptr_tmp = build_qualified_type (fn_ptr_tmp, fn_ptr_quals);
 615           if (DECL_P (*node))
 616             TREE_TYPE (*node) = fn_ptr_tmp;
 617           else
 618             {
 619               gcc_assert (TREE_CODE (*node) == POINTER_TYPE);
 620               *node = fn_ptr_tmp;
 621             }
 622         }
 623     }
 624
 625   return returned_attrs;
 626 }
 627
 628 /* Return TRUE iff ATTR has been parsed by the front-end as a C++-11
 629    attribute.
 630
 631    When G++ parses a C++11 attribute, it is represented as
 632    a TREE_LIST which TREE_PURPOSE is itself a TREE_LIST.  TREE_PURPOSE
 633    (TREE_PURPOSE (ATTR)) is the namespace of the attribute, and the
 634    TREE_VALUE (TREE_PURPOSE (ATTR)) is its non-qualified name.  Please
 635    use get_attribute_namespace and get_attribute_name to retrieve the
 636    namespace and name of the attribute, as these accessors work with
 637    GNU attributes as well.  */
 638
 639 bool
 640 cxx11_attribute_p (const_tree attr)
 641 {
 642   if (attr == NULL_TREE
 643       || TREE_CODE (attr) != TREE_LIST)
 644     return false;
 645
 646   return (TREE_CODE (TREE_PURPOSE (attr)) == TREE_LIST);
 647 }
 648
 649 /* Return the name of the attribute ATTR.  This accessor works on GNU
 650    and C++11 (scoped) attributes.
 651
 652    Please read the comments of cxx11_attribute_p to understand the
 653    format of attributes.  */
 654
 655 tree
 656 get_attribute_name (const_tree attr)
 657 {
 658   if (cxx11_attribute_p (attr))
 659     return TREE_VALUE (TREE_PURPOSE (attr));
 660   return TREE_PURPOSE (attr);
 661 }
 662
 663 /* Return the namespace of the attribute ATTR.  This accessor works on
 664    GNU and C++11 (scoped) attributes.  On GNU attributes,
 665    it returns an identifier tree for the string "gnu".
 666
 667    Please read the comments of cxx11_attribute_p to understand the
 668    format of attributes.  */
 669
 670 tree
 671 get_attribute_namespace (const_tree attr)
 672 {
 673   if (cxx11_attribute_p (attr))
 674     return TREE_PURPOSE (TREE_PURPOSE (attr));
 675   return get_identifier ("gnu");
 676 }
 677
 678 /* Subroutine of set_method_tm_attributes.  Apply TM attribute ATTR
 679    to the method FNDECL.  */
 680
 681 void
 682 apply_tm_attr (tree fndecl, tree attr)
 683 {
 684   decl_attributes (&TREE_TYPE (fndecl), tree_cons (attr, NULL, NULL), 0);
 685 }