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 Free Software Foundation, Inc.
   4
   5 This file is part of GCC.
   6
   7 GCC is free software; you can redistribute it and/or modify it under
   8 the terms of the GNU General Public License as published by the Free
   9 Software Foundation; either version 2, or (at your option) any later
  10 version.
  11
  12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  14 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  15 for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with GCC; see the file COPYING.  If not, write to the Free
  19 Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
  20 02110-1301, USA.  */
  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 "toplev.h"
  29 #include "output.h"
  30 #include "rtl.h"
  31 #include "ggc.h"
  32 #include "tm_p.h"
  33 #include "cpplib.h"
  34 #include "target.h"
  35 #include "langhooks.h"
  36
  37 static void init_attributes (void);
  38
  39 /* Table of the tables of attributes (common, language, format, machine)
  40    searched.  */
  41 static const struct attribute_spec *attribute_tables[4];
  42
  43 static bool attributes_initialized = false;
  44
  45 /* Default empty table of attributes.  */
  46 static const struct attribute_spec empty_attribute_table[] =
  47 {
  48   { NULL, 0, 0, false, false, false, NULL }
  49 };
  50
  51 /* Initialize attribute tables, and make some sanity checks
  52    if --enable-checking.  */
  53
  54 static void
  55 init_attributes (void)
  56 {
  57   size_t i;
  58
  59   attribute_tables[0] = lang_hooks.common_attribute_table;
  60   attribute_tables[1] = lang_hooks.attribute_table;
  61   attribute_tables[2] = lang_hooks.format_attribute_table;
  62   attribute_tables[3] = targetm.attribute_table;
  63
  64   /* Translate NULL pointers to pointers to the empty table.  */
  65   for (i = 0; i < ARRAY_SIZE (attribute_tables); i++)
  66     if (attribute_tables[i] == NULL)
  67       attribute_tables[i] = empty_attribute_table;
  68
  69 #ifdef ENABLE_CHECKING
  70   /* Make some sanity checks on the attribute tables.  */
  71   for (i = 0; i < ARRAY_SIZE (attribute_tables); i++)
  72     {
  73       int j;
  74
  75       for (j = 0; attribute_tables[i][j].name != NULL; j++)
  76         {
  77           /* The name must not begin and end with __.  */
  78           const char *name = attribute_tables[i][j].name;
  79           int len = strlen (name);
  80
  81           gcc_assert (!(name[0] == '_' && name[1] == '_'
  82                         && name[len - 1] == '_' && name[len - 2] == '_'));
  83
  84           /* The minimum and maximum lengths must be consistent.  */
  85           gcc_assert (attribute_tables[i][j].min_length >= 0);
  86
  87           gcc_assert (attribute_tables[i][j].max_length == -1
  88                       || (attribute_tables[i][j].max_length
  89                           >= attribute_tables[i][j].min_length));
  90
  91           /* An attribute cannot require both a DECL and a TYPE.  */
  92           gcc_assert (!attribute_tables[i][j].decl_required
  93                       || !attribute_tables[i][j].type_required);
  94
  95           /* If an attribute requires a function type, in particular
  96              it requires a type.  */
  97           gcc_assert (!attribute_tables[i][j].function_type_required
  98                       || attribute_tables[i][j].type_required);
  99         }
 100     }
 101
 102   /* Check that each name occurs just once in each table.  */
 103   for (i = 0; i < ARRAY_SIZE (attribute_tables); i++)
 104     {
 105       int j, k;
 106       for (j = 0; attribute_tables[i][j].name != NULL; j++)
 107         for (k = j + 1; attribute_tables[i][k].name != NULL; k++)
 108           gcc_assert (strcmp (attribute_tables[i][j].name,
 109                               attribute_tables[i][k].name));
 110     }
 111   /* Check that no name occurs in more than one table.  */
 112   for (i = 0; i < ARRAY_SIZE (attribute_tables); i++)
 113     {
 114       size_t j, k, l;
 115
 116       for (j = i + 1; j < ARRAY_SIZE (attribute_tables); j++)
 117         for (k = 0; attribute_tables[i][k].name != NULL; k++)
 118           for (l = 0; attribute_tables[j][l].name != NULL; l++)
 119             gcc_assert (strcmp (attribute_tables[i][k].name,
 120                                 attribute_tables[j][l].name));
 121     }
 122 #endif
 123
 124   attributes_initialized = true;
 125 }
 126 \f
 127 /* Process the attributes listed in ATTRIBUTES and install them in *NODE,
 128    which is either a DECL (including a TYPE_DECL) or a TYPE.  If a DECL,
 129    it should be modified in place; if a TYPE, a copy should be created
 130    unless ATTR_FLAG_TYPE_IN_PLACE is set in FLAGS.  FLAGS gives further
 131    information, in the form of a bitwise OR of flags in enum attribute_flags
 132    from tree.h.  Depending on these flags, some attributes may be
 133    returned to be applied at a later stage (for example, to apply
 134    a decl attribute to the declaration rather than to its type).  */
 135
 136 tree
 137 decl_attributes (tree *node, tree attributes, int flags)
 138 {
 139   tree a;
 140   tree returned_attrs = NULL_TREE;
 141
 142   if (!attributes_initialized)
 143     init_attributes ();
 144
 145   targetm.insert_attributes (*node, &attributes);
 146
 147   for (a = attributes; a; a = TREE_CHAIN (a))
 148     {
 149       tree name = TREE_PURPOSE (a);
 150       tree args = TREE_VALUE (a);
 151       tree *anode = node;
 152       const struct attribute_spec *spec = NULL;
 153       bool no_add_attrs = 0;
 154       tree fn_ptr_tmp = NULL_TREE;
 155       size_t i;
 156
 157       for (i = 0; i < ARRAY_SIZE (attribute_tables); i++)
 158         {
 159           int j;
 160
 161           for (j = 0; attribute_tables[i][j].name != NULL; j++)
 162             {
 163               if (is_attribute_p (attribute_tables[i][j].name, name))
 164                 {
 165                   spec = &attribute_tables[i][j];
 166                   break;
 167                 }
 168             }
 169           if (spec != NULL)
 170             break;
 171         }
 172
 173       if (spec == NULL)
 174         {
 175           warning (OPT_Wattributes, "%qs attribute directive ignored",
 176                    IDENTIFIER_POINTER (name));
 177           continue;
 178         }
 179       else if (list_length (args) < spec->min_length
 180                || (spec->max_length >= 0
 181                    && list_length (args) > spec->max_length))
 182         {
 183           error ("wrong number of arguments specified for %qs attribute",
 184                  IDENTIFIER_POINTER (name));
 185           continue;
 186         }
 187
 188       if (spec->decl_required && !DECL_P (*anode))
 189         {
 190           if (flags & ((int) ATTR_FLAG_DECL_NEXT
 191                        | (int) ATTR_FLAG_FUNCTION_NEXT
 192                        | (int) ATTR_FLAG_ARRAY_NEXT))
 193             {
 194               /* Pass on this attribute to be tried again.  */
 195               returned_attrs = tree_cons (name, args, returned_attrs);
 196               continue;
 197             }
 198           else
 199             {
 200               warning (OPT_Wattributes, "%qs attribute does not apply to types",
 201                        IDENTIFIER_POINTER (name));
 202               continue;
 203             }
 204         }
 205
 206       /* If we require a type, but were passed a decl, set up to make a
 207          new type and update the one in the decl.  ATTR_FLAG_TYPE_IN_PLACE
 208          would have applied if we'd been passed a type, but we cannot modify
 209          the decl's type in place here.  */
 210       if (spec->type_required && DECL_P (*anode))
 211         {
 212           anode = &TREE_TYPE (*anode);
 213           flags &= ~(int) ATTR_FLAG_TYPE_IN_PLACE;
 214         }
 215
 216       if (spec->function_type_required && TREE_CODE (*anode) != FUNCTION_TYPE
 217           && TREE_CODE (*anode) != METHOD_TYPE)
 218         {
 219           if (TREE_CODE (*anode) == POINTER_TYPE
 220               && (TREE_CODE (TREE_TYPE (*anode)) == FUNCTION_TYPE
 221                   || TREE_CODE (TREE_TYPE (*anode)) == METHOD_TYPE))
 222             {
 223               /* OK, this is a bit convoluted.  We can't just make a copy
 224                  of the pointer type and modify its TREE_TYPE, because if
 225                  we change the attributes of the target type the pointer
 226                  type needs to have a different TYPE_MAIN_VARIANT.  So we
 227                  pull out the target type now, frob it as appropriate, and
 228                  rebuild the pointer type later.
 229
 230                  This would all be simpler if attributes were part of the
 231                  declarator, grumble grumble.  */
 232               fn_ptr_tmp = TREE_TYPE (*anode);
 233               anode = &fn_ptr_tmp;
 234               flags &= ~(int) ATTR_FLAG_TYPE_IN_PLACE;
 235             }
 236           else if (flags & (int) ATTR_FLAG_FUNCTION_NEXT)
 237             {
 238               /* Pass on this attribute to be tried again.  */
 239               returned_attrs = tree_cons (name, args, returned_attrs);
 240               continue;
 241             }
 242
 243           if (TREE_CODE (*anode) != FUNCTION_TYPE
 244               && TREE_CODE (*anode) != METHOD_TYPE)
 245             {
 246               warning (OPT_Wattributes,
 247                        "%qs attribute only applies to function types",
 248                        IDENTIFIER_POINTER (name));
 249               continue;
 250             }
 251         }
 252
 253       if (TYPE_P (*anode)
 254           && (flags & (int) ATTR_FLAG_TYPE_IN_PLACE)
 255           && TYPE_SIZE (*anode) != NULL_TREE)
 256         {
 257           warning (OPT_Wattributes, "type attributes ignored after type is already defined");
 258           continue;
 259         }
 260
 261       if (spec->handler != NULL)
 262         returned_attrs = chainon ((*spec->handler) (anode, name, args,
 263                                                     flags, &no_add_attrs),
 264                                   returned_attrs);
 265
 266       /* Layout the decl in case anything changed.  */
 267       if (spec->type_required && DECL_P (*node)
 268           && (TREE_CODE (*node) == VAR_DECL
 269               || TREE_CODE (*node) == PARM_DECL
 270               || TREE_CODE (*node) == RESULT_DECL))
 271         relayout_decl (*node);
 272
 273       if (!no_add_attrs)
 274         {
 275           tree old_attrs;
 276           tree a;
 277
 278           if (DECL_P (*anode))
 279             old_attrs = DECL_ATTRIBUTES (*anode);
 280           else
 281             old_attrs = TYPE_ATTRIBUTES (*anode);
 282
 283           for (a = lookup_attribute (spec->name, old_attrs);
 284                a != NULL_TREE;
 285                a = lookup_attribute (spec->name, TREE_CHAIN (a)))
 286             {
 287               if (simple_cst_equal (TREE_VALUE (a), args) == 1)
 288                 break;
 289             }
 290
 291           if (a == NULL_TREE)
 292             {
 293               /* This attribute isn't already in the list.  */
 294               if (DECL_P (*anode))
 295                 DECL_ATTRIBUTES (*anode) = tree_cons (name, args, old_attrs);
 296               else if (flags & (int) ATTR_FLAG_TYPE_IN_PLACE)
 297                 {
 298                   TYPE_ATTRIBUTES (*anode) = tree_cons (name, args, old_attrs);
 299                   /* If this is the main variant, also push the attributes
 300                      out to the other variants.  */
 301                   if (*anode == TYPE_MAIN_VARIANT (*anode))
 302                     {
 303                       tree variant;
 304                       for (variant = *anode; variant;
 305                            variant = TYPE_NEXT_VARIANT (variant))
 306                         {
 307                           if (TYPE_ATTRIBUTES (variant) == old_attrs)
 308                             TYPE_ATTRIBUTES (variant)
 309                               = TYPE_ATTRIBUTES (*anode);
 310                           else if (!lookup_attribute
 311                                    (spec->name, TYPE_ATTRIBUTES (variant)))
 312                             TYPE_ATTRIBUTES (variant) = tree_cons
 313                               (name, args, TYPE_ATTRIBUTES (variant));
 314                         }
 315                     }
 316                 }
 317               else
 318                 *anode = build_type_attribute_variant (*anode,
 319                                                        tree_cons (name, args,
 320                                                                   old_attrs));
 321             }
 322         }
 323
 324       if (fn_ptr_tmp)
 325         {
 326           /* Rebuild the function pointer type and put it in the
 327              appropriate place.  */
 328           fn_ptr_tmp = build_pointer_type (fn_ptr_tmp);
 329           if (DECL_P (*node))
 330             TREE_TYPE (*node) = fn_ptr_tmp;
 331           else
 332             {
 333               gcc_assert (TREE_CODE (*node) == POINTER_TYPE);
 334               *node = fn_ptr_tmp;
 335             }
 336         }
 337     }
 338
 339   return returned_attrs;
 340 }