gcc/attribs.h

   1 /* Declarations and definitions dealing with attribute handling.
   2    Copyright (C) 2013-2022 Free Software Foundation, Inc.
   3
   4 This file is part of GCC.
   5
   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
   9 version.
  10
  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
  14 for more details.
  15
  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/>.  */
  19
  20 #ifndef GCC_ATTRIBS_H
  21 #define GCC_ATTRIBS_H
  22
  23 extern const struct attribute_spec *lookup_attribute_spec (const_tree);
  24 extern void free_attr_data ();
  25 extern void init_attributes (void);
  26
  27 /* Process the attributes listed in ATTRIBUTES and install them in *NODE,
  28    which is either a DECL (including a TYPE_DECL) or a TYPE.  If a DECL,
  29    it should be modified in place; if a TYPE, a copy should be created
  30    unless ATTR_FLAG_TYPE_IN_PLACE is set in FLAGS.  FLAGS gives further
  31    information, in the form of a bitwise OR of flags in enum attribute_flags
  32    from tree.h.  Depending on these flags, some attributes may be
  33    returned to be applied at a later stage (for example, to apply
  34    a decl attribute to the declaration rather than to its type).  */
  35 extern tree decl_attributes (tree *, tree, int, tree = NULL_TREE);
  36
  37 extern bool cxx11_attribute_p (const_tree);
  38 extern tree get_attribute_name (const_tree);
  39 extern tree get_attribute_namespace (const_tree);
  40 extern void apply_tm_attr (tree, tree);
  41 extern tree make_attribute (const char *, const char *, tree);
  42 extern bool attribute_ignored_p (tree);
  43 extern bool attribute_ignored_p (const attribute_spec *const);
  44
  45 extern struct scoped_attributes* register_scoped_attributes (const struct attribute_spec *,
  46                                                              const char *,
  47                                                              bool = false);
  48
  49 extern char *sorted_attr_string (tree);
  50 extern bool common_function_versions (tree, tree);
  51 extern tree make_dispatcher_decl (const tree);
  52 extern bool is_function_default_version (const tree);
  53 extern void handle_ignored_attributes_option (vec<char *> *);
  54
  55 /* Return a type like TTYPE except that its TYPE_ATTRIBUTES
  56    is ATTRIBUTE.
  57
  58    Such modified types already made are recorded so that duplicates
  59    are not made.  */
  60
  61 extern tree build_type_attribute_variant (tree, tree);
  62 extern tree build_decl_attribute_variant (tree, tree);
  63 extern tree build_type_attribute_qual_variant (tree, tree, int);
  64
  65 extern bool simple_cst_list_equal (const_tree, const_tree);
  66 extern bool attribute_value_equal (const_tree, const_tree);
  67
  68 /* Return 0 if the attributes for two types are incompatible, 1 if they
  69    are compatible, and 2 if they are nearly compatible (which causes a
  70    warning to be generated).  */
  71 extern int comp_type_attributes (const_tree, const_tree);
  72
  73 extern tree affects_type_identity_attributes (tree, bool = true);
  74 extern tree restrict_type_identity_attributes_to (tree, tree);
  75
  76 /* Default versions of target-overridable functions.  */
  77 extern tree merge_decl_attributes (tree, tree);
  78 extern tree merge_type_attributes (tree, tree);
  79
  80 /* Remove any instances of attribute ATTR_NAME in LIST and return the
  81    modified list.  */
  82
  83 extern tree remove_attribute (const char *, tree);
  84
  85 /* Similarly but also with specific attribute namespace.  */
  86
  87 extern tree remove_attribute (const char *, const char *, tree);
  88
  89 /* Given two attributes lists, return a list of their union.  */
  90
  91 extern tree merge_attributes (tree, tree);
  92
  93 /* Duplicate all attributes with name NAME in ATTR list to *ATTRS if
  94    they are missing there.  */
  95
  96 extern void duplicate_one_attribute (tree *, tree, const char *);
  97
  98 /* Duplicate all attributes from user DECL to the corresponding
  99    builtin that should be propagated.  */
 100
 101 extern void copy_attributes_to_builtin (tree);
 102
 103 /* Given two Windows decl attributes lists, possibly including
 104    dllimport, return a list of their union .  */
 105 extern tree merge_dllimport_decl_attributes (tree, tree);
 106
 107 /* Handle a "dllimport" or "dllexport" attribute.  */
 108 extern tree handle_dll_attribute (tree *, tree, tree, int, bool *);
 109
 110 extern int attribute_list_equal (const_tree, const_tree);
 111 extern int attribute_list_contained (const_tree, const_tree);
 112
 113 /* The backbone of lookup_attribute().  ATTR_LEN is the string length
 114    of ATTR_NAME, and LIST is not NULL_TREE.
 115
 116    The function is called from lookup_attribute in order to optimize
 117    for size.  */
 118 extern tree private_lookup_attribute (const char *attr_name, size_t attr_len,
 119                                       tree list);
 120 extern tree private_lookup_attribute (const char *attr_ns,
 121                                       const char *attr_name,
 122                                       size_t attr_ns_len, size_t attr_len,
 123                                       tree list);
 124
 125 extern unsigned decls_mismatched_attributes (tree, tree, tree,
 126                                              const char* const[],
 127                                              pretty_printer*);
 128
 129 extern void maybe_diag_alias_attributes (tree, tree);
 130
 131 /* For a given string S of length L, strip leading and trailing '_' characters
 132    so that we have a canonical form of attribute names.  NB: This function may
 133    change S and L.  */
 134
 135 template <typename T>
 136 inline bool
 137 canonicalize_attr_name (const char *&s, T &l)
 138 {
 139   if (l > 4 && s[0] == '_' && s[1] == '_' && s[l - 1] == '_' && s[l - 2] == '_')
 140     {
 141       s += 2;
 142       l -= 4;
 143       return true;
 144     }
 145   return false;
 146 }
 147
 148 /* For a given IDENTIFIER_NODE, strip leading and trailing '_' characters
 149    so that we have a canonical form of attribute names.  */
 150
 151 static inline tree
 152 canonicalize_attr_name (tree attr_name)
 153 {
 154   size_t l = IDENTIFIER_LENGTH (attr_name);
 155   const char *s = IDENTIFIER_POINTER (attr_name);
 156
 157   if (canonicalize_attr_name (s, l))
 158     return get_identifier_with_length (s, l);
 159
 160   return attr_name;
 161 }
 162
 163 /* Compare attribute identifiers ATTR1 and ATTR2 with length ATTR1_LEN and
 164    ATTR2_LEN.  */
 165
 166 static inline bool
 167 cmp_attribs (const char *attr1, size_t attr1_len,
 168              const char *attr2, size_t attr2_len)
 169 {
 170   return attr1_len == attr2_len && strncmp (attr1, attr2, attr1_len) == 0;
 171 }
 172
 173 /* Compare attribute identifiers ATTR1 and ATTR2.  */
 174
 175 static inline bool
 176 cmp_attribs (const char *attr1, const char *attr2)
 177 {
 178   return cmp_attribs (attr1, strlen (attr1), attr2, strlen (attr2));
 179 }
 180
 181 /* Given an identifier node IDENT and a string ATTR_NAME, return true
 182    if the identifier node is a valid attribute name for the string.  */
 183
 184 static inline bool
 185 is_attribute_p (const char *attr_name, const_tree ident)
 186 {
 187   return cmp_attribs (attr_name, strlen (attr_name),
 188                       IDENTIFIER_POINTER (ident), IDENTIFIER_LENGTH (ident));
 189 }
 190
 191 /* Given an attribute ATTR and a string ATTR_NS, return true
 192    if the attribute namespace is valid for the string.  ATTR_NS "" stands
 193    for standard attribute (NULL get_attribute_namespace) or "gnu"
 194    namespace.  */
 195
 196 static inline bool
 197 is_attribute_namespace_p (const char *attr_ns, const_tree attr)
 198 {
 199   tree ident = get_attribute_namespace (attr);
 200   if (attr_ns == NULL)
 201     return ident == NULL_TREE;
 202   if (attr_ns[0])
 203     return ident && is_attribute_p (attr_ns, ident);
 204   return ident == NULL_TREE || is_attribute_p ("gnu", ident);
 205 }
 206
 207 /* Given an attribute name ATTR_NAME and a list of attributes LIST,
 208    return a pointer to the attribute's list element if the attribute
 209    is part of the list, or NULL_TREE if not found.  If the attribute
 210    appears more than once, this only returns the first occurrence; the
 211    TREE_CHAIN of the return value should be passed back in if further
 212    occurrences are wanted.  ATTR_NAME must be in the form 'text' (not
 213    '__text__').  */
 214
 215 static inline tree
 216 lookup_attribute (const char *attr_name, tree list)
 217 {
 218   if (CHECKING_P && attr_name[0] != '_')
 219     {
 220       size_t attr_len = strlen (attr_name);
 221       gcc_checking_assert (!canonicalize_attr_name (attr_name, attr_len));
 222     }
 223   /* In most cases, list is NULL_TREE.  */
 224   if (list == NULL_TREE)
 225     return NULL_TREE;
 226   else
 227     {
 228       size_t attr_len = strlen (attr_name);
 229       /* Do the strlen() before calling the out-of-line implementation.
 230          In most cases attr_name is a string constant, and the compiler
 231          will optimize the strlen() away.  */
 232       return private_lookup_attribute (attr_name, attr_len, list);
 233     }
 234 }
 235
 236 /* Similar to lookup_attribute, but also match the attribute namespace.
 237    ATTR_NS "" stands for either standard attribute or "gnu" namespace.  */
 238
 239 static inline tree
 240 lookup_attribute (const char *attr_ns, const char *attr_name, tree list)
 241 {
 242   if (CHECKING_P && attr_name[0] != '_')
 243     {
 244       size_t attr_len = strlen (attr_name);
 245       gcc_checking_assert (!canonicalize_attr_name (attr_name, attr_len));
 246     }
 247   if (CHECKING_P && attr_ns && attr_ns[0] != '_')
 248     {
 249       size_t attr_ns_len = strlen (attr_ns);
 250       gcc_checking_assert (!canonicalize_attr_name (attr_ns, attr_ns_len));
 251     }
 252   /* In most cases, list is NULL_TREE.  */
 253   if (list == NULL_TREE)
 254     return NULL_TREE;
 255   else
 256     {
 257       size_t attr_ns_len = attr_ns ? strlen (attr_ns) : 0;
 258       size_t attr_len = strlen (attr_name);
 259       /* Do the strlen() before calling the out-of-line implementation.
 260          In most cases attr_name is a string constant, and the compiler
 261          will optimize the strlen() away.  */
 262       return private_lookup_attribute (attr_ns, attr_name,
 263                                        attr_ns_len, attr_len, list);
 264     }
 265 }
 266
 267 /* Given an attribute name ATTR_NAME and a list of attributes LIST,
 268    return a pointer to the attribute's list first element if the attribute
 269    starts with ATTR_NAME.  ATTR_NAME must be in the form 'text' (not
 270    '__text__').  */
 271
 272 static inline tree
 273 lookup_attribute_by_prefix (const char *attr_name, tree list)
 274 {
 275   gcc_checking_assert (attr_name[0] != '_');
 276   /* In most cases, list is NULL_TREE.  */
 277   if (list == NULL_TREE)
 278     return NULL_TREE;
 279   else
 280     {
 281       size_t attr_len = strlen (attr_name);
 282       while (list)
 283         {
 284           tree name = get_attribute_name (list);
 285           size_t ident_len = IDENTIFIER_LENGTH (name);
 286
 287           if (attr_len > ident_len)
 288             {
 289               list = TREE_CHAIN (list);
 290               continue;
 291             }
 292
 293           const char *p = IDENTIFIER_POINTER (name);
 294           gcc_checking_assert (attr_len == 0 || p[0] != '_'
 295                                || (ident_len > 1 && p[1] != '_'));
 296           if (strncmp (attr_name, p, attr_len) == 0)
 297             break;
 298
 299           list = TREE_CHAIN (list);
 300         }
 301
 302       return list;
 303     }
 304 }
 305
 306 /* Description of a function argument declared with attribute access.
 307    Used as an "iterator" over all such arguments in a function declaration
 308    or call.  */
 309
 310 struct attr_access
 311 {
 312   /* The beginning and end of the internal string representation.  */
 313   const char *str, *end;
 314   /* The attribute pointer argument.  */
 315   tree ptr;
 316   /* For a declaration, a TREE_CHAIN of VLA bound expressions stored
 317      in TREE_VALUE and their positions in the argument list (stored
 318      in TREE_PURPOSE).  Each expression may be a PARM_DECL or some
 319      other DECL (for ordinary variables), or an EXPR for other
 320      expressions (e.g., funcion calls).  */
 321   tree size;
 322
 323   /* The zero-based position of each of the formal function arguments.
 324      For the optional SIZARG, UINT_MAX when not specified.  For VLAs
 325      with multiple variable bounds, SIZARG is the position corresponding
 326      to the most significant bound in the argument list.  Positions of
 327      subsequent bounds are in the TREE_PURPOSE field of the SIZE chain.  */
 328   unsigned ptrarg;
 329   unsigned sizarg;
 330   /* For internal specifications only, the constant minimum size of
 331      the array, zero if not specified, and HWI_M1U for the unspecified
 332      VLA [*] notation.  Meaningless for external (explicit) access
 333      specifications.  */
 334   unsigned HOST_WIDE_INT minsize;
 335
 336   /* The access mode.  */
 337   access_mode mode;
 338
 339   /* Set for an attribute added internally rather than by an explicit
 340      declaration. */
 341   bool internal_p;
 342   /* Set for the T[static MINSIZE] array notation for nonzero MINSIZE
 343      less than HWI_M1U.  */
 344   bool static_p;
 345
 346   /* Return the number of specified VLA bounds.  */
 347   unsigned vla_bounds (unsigned *) const;
 348
 349   /* Return internal representation as STRING_CST.  */
 350   tree to_internal_string () const;
 351
 352   /* Return the human-readable representation of the external attribute
 353      specification (as it might appear in the source code) as STRING_CST.  */
 354   tree to_external_string () const;
 355
 356   /* Return argument of array type formatted as a readable string.  */
 357   std::string array_as_string (tree) const;
 358
 359   /* Return the access mode corresponding to the character code.  */
 360   static access_mode from_mode_char (char);
 361
 362   /* Reset front end-specific attribute access data from attributes.  */
 363   static void free_lang_data (tree);
 364
 365   /* The character codes corresponding to all the access modes.  */
 366   static constexpr char mode_chars[5] = { '-', 'r', 'w', 'x', '^' };
 367
 368   /* The strings corresponding to just the external access modes.  */
 369   static constexpr char mode_names[4][11] =
 370     {
 371      "none", "read_only", "write_only", "read_write"
 372     };
 373 };
 374
 375 inline access_mode
 376 attr_access::from_mode_char (char c)
 377 {
 378   switch (c)
 379     {
 380     case mode_chars[access_none]: return access_none;
 381     case mode_chars[access_read_only]: return access_read_only;
 382     case mode_chars[access_write_only]: return access_write_only;
 383     case mode_chars[access_read_write]: return access_read_write;
 384     case mode_chars[access_deferred]: return access_deferred;
 385     }
 386   gcc_unreachable ();
 387 }
 388
 389 /* Used to define rdwr_map below.  */
 390 struct rdwr_access_hash: int_hash<int, -1> { };
 391
 392 /* A mapping between argument number corresponding to attribute access
 393    mode (read_only, write_only, or read_write) and operands.  */
 394 struct attr_access;
 395 typedef hash_map<rdwr_access_hash, attr_access> rdwr_map;
 396
 397 extern void init_attr_rdwr_indices (rdwr_map *, tree);
 398 extern attr_access *get_parm_access (rdwr_map &, tree,
 399                                      tree = current_function_decl);
 400
 401 #endif // GCC_ATTRIBS_H