gcc/attribs.h

   1 /* Declarations and definitions dealing with attribute handling.
   2    Copyright (C) 2013-2021 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
  43 extern struct scoped_attributes* register_scoped_attributes (const struct attribute_spec *,
  44                                                              const char *,
  45                                                              bool = false);
  46
  47 extern char *sorted_attr_string (tree);
  48 extern bool common_function_versions (tree, tree);
  49 extern tree make_dispatcher_decl (const tree);
  50 extern bool is_function_default_version (const tree);
  51 extern void handle_ignored_attributes_option (vec<char *> *);
  52
  53 /* Return a type like TTYPE except that its TYPE_ATTRIBUTES
  54    is ATTRIBUTE.
  55
  56    Such modified types already made are recorded so that duplicates
  57    are not made.  */
  58
  59 extern tree build_type_attribute_variant (tree, tree);
  60 extern tree build_decl_attribute_variant (tree, tree);
  61 extern tree build_type_attribute_qual_variant (tree, tree, int);
  62
  63 extern bool attribute_value_equal (const_tree, const_tree);
  64
  65 /* Return 0 if the attributes for two types are incompatible, 1 if they
  66    are compatible, and 2 if they are nearly compatible (which causes a
  67    warning to be generated).  */
  68 extern int comp_type_attributes (const_tree, const_tree);
  69
  70 extern tree affects_type_identity_attributes (tree, bool = true);
  71 extern tree restrict_type_identity_attributes_to (tree, tree);
  72
  73 /* Default versions of target-overridable functions.  */
  74 extern tree merge_decl_attributes (tree, tree);
  75 extern tree merge_type_attributes (tree, tree);
  76
  77 /* Remove any instances of attribute ATTR_NAME in LIST and return the
  78    modified list.  */
  79
  80 extern tree remove_attribute (const char *, tree);
  81
  82 /* Given two attributes lists, return a list of their union.  */
  83
  84 extern tree merge_attributes (tree, tree);
  85
  86 /* Duplicate all attributes with name NAME in ATTR list to *ATTRS if
  87    they are missing there.  */
  88
  89 extern void duplicate_one_attribute (tree *, tree, const char *);
  90
  91 /* Duplicate all attributes from user DECL to the corresponding
  92    builtin that should be propagated.  */
  93
  94 extern void copy_attributes_to_builtin (tree);
  95
  96 /* Given two Windows decl attributes lists, possibly including
  97    dllimport, return a list of their union .  */
  98 extern tree merge_dllimport_decl_attributes (tree, tree);
  99
 100 /* Handle a "dllimport" or "dllexport" attribute.  */
 101 extern tree handle_dll_attribute (tree *, tree, tree, int, bool *);
 102
 103 extern int attribute_list_equal (const_tree, const_tree);
 104 extern int attribute_list_contained (const_tree, const_tree);
 105
 106 /* The backbone of lookup_attribute().  ATTR_LEN is the string length
 107    of ATTR_NAME, and LIST is not NULL_TREE.
 108
 109    The function is called from lookup_attribute in order to optimize
 110    for size.  */
 111 extern tree private_lookup_attribute (const char *attr_name, size_t attr_len,
 112                                       tree list);
 113
 114 extern unsigned decls_mismatched_attributes (tree, tree, tree,
 115                                              const char* const[],
 116                                              pretty_printer*);
 117
 118 extern void maybe_diag_alias_attributes (tree, tree);
 119
 120 /* For a given string S of length L, strip leading and trailing '_' characters
 121    so that we have a canonical form of attribute names.  NB: This function may
 122    change S and L.  */
 123
 124 template <typename T>
 125 inline bool
 126 canonicalize_attr_name (const char *&s, T &l)
 127 {
 128   if (l > 4 && s[0] == '_' && s[1] == '_' && s[l - 1] == '_' && s[l - 2] == '_')
 129     {
 130       s += 2;
 131       l -= 4;
 132       return true;
 133     }
 134   return false;
 135 }
 136
 137 /* For a given IDENTIFIER_NODE, strip leading and trailing '_' characters
 138    so that we have a canonical form of attribute names.  */
 139
 140 static inline tree
 141 canonicalize_attr_name (tree attr_name)
 142 {
 143   size_t l = IDENTIFIER_LENGTH (attr_name);
 144   const char *s = IDENTIFIER_POINTER (attr_name);
 145
 146   if (canonicalize_attr_name (s, l))
 147     return get_identifier_with_length (s, l);
 148
 149   return attr_name;
 150 }
 151
 152 /* Compare attribute identifiers ATTR1 and ATTR2 with length ATTR1_LEN and
 153    ATTR2_LEN.  */
 154
 155 static inline bool
 156 cmp_attribs (const char *attr1, size_t attr1_len,
 157              const char *attr2, size_t attr2_len)
 158 {
 159   return attr1_len == attr2_len && strncmp (attr1, attr2, attr1_len) == 0;
 160 }
 161
 162 /* Compare attribute identifiers ATTR1 and ATTR2.  */
 163
 164 static inline bool
 165 cmp_attribs (const char *attr1, const char *attr2)
 166 {
 167   return cmp_attribs (attr1, strlen (attr1), attr2, strlen (attr2));
 168 }
 169
 170 /* Given an identifier node IDENT and a string ATTR_NAME, return true
 171    if the identifier node is a valid attribute name for the string.  */
 172
 173 static inline bool
 174 is_attribute_p (const char *attr_name, const_tree ident)
 175 {
 176   return cmp_attribs (attr_name, strlen (attr_name),
 177                       IDENTIFIER_POINTER (ident), IDENTIFIER_LENGTH (ident));
 178 }
 179
 180 /* Given an attribute name ATTR_NAME and a list of attributes LIST,
 181    return a pointer to the attribute's list element if the attribute
 182    is part of the list, or NULL_TREE if not found.  If the attribute
 183    appears more than once, this only returns the first occurrence; the
 184    TREE_CHAIN of the return value should be passed back in if further
 185    occurrences are wanted.  ATTR_NAME must be in the form 'text' (not
 186    '__text__').  */
 187
 188 static inline tree
 189 lookup_attribute (const char *attr_name, tree list)
 190 {
 191   gcc_checking_assert (attr_name[0] != '_');
 192   /* In most cases, list is NULL_TREE.  */
 193   if (list == NULL_TREE)
 194     return NULL_TREE;
 195   else
 196     {
 197       size_t attr_len = strlen (attr_name);
 198       /* Do the strlen() before calling the out-of-line implementation.
 199          In most cases attr_name is a string constant, and the compiler
 200          will optimize the strlen() away.  */
 201       return private_lookup_attribute (attr_name, attr_len, list);
 202     }
 203 }
 204
 205 /* Given an attribute name ATTR_NAME and a list of attributes LIST,
 206    return a pointer to the attribute's list first element if the attribute
 207    starts with ATTR_NAME.  ATTR_NAME must be in the form 'text' (not
 208    '__text__').  */
 209
 210 static inline tree
 211 lookup_attribute_by_prefix (const char *attr_name, tree list)
 212 {
 213   gcc_checking_assert (attr_name[0] != '_');
 214   /* In most cases, list is NULL_TREE.  */
 215   if (list == NULL_TREE)
 216     return NULL_TREE;
 217   else
 218     {
 219       size_t attr_len = strlen (attr_name);
 220       while (list)
 221         {
 222           size_t ident_len = IDENTIFIER_LENGTH (get_attribute_name (list));
 223
 224           if (attr_len > ident_len)
 225             {
 226               list = TREE_CHAIN (list);
 227               continue;
 228             }
 229
 230           const char *p = IDENTIFIER_POINTER (get_attribute_name (list));
 231           gcc_checking_assert (attr_len == 0 || p[0] != '_');
 232
 233           if (strncmp (attr_name, p, attr_len) == 0)
 234             break;
 235
 236           list = TREE_CHAIN (list);
 237         }
 238
 239       return list;
 240     }
 241 }
 242
 243 /* Description of a function argument declared with attribute access.
 244    Used as an "iterator" over all such arguments in a function declaration
 245    or call.  */
 246
 247 struct attr_access
 248 {
 249   /* The beginning and end of the internal string representation.  */
 250   const char *str, *end;
 251   /* The attribute pointer argument.  */
 252   tree ptr;
 253   /* For a declaration, a TREE_CHAIN of VLA bound expressions stored
 254      in TREE_VALUE and their positions in the argument list (stored
 255      in TREE_PURPOSE).  Each expression may be a PARM_DECL or some
 256      other DECL (for ordinary variables), or an EXPR for other
 257      expressions (e.g., funcion calls).  */
 258   tree size;
 259
 260   /* The zero-based position of each of the formal function arguments.
 261      For the optional SIZARG, UINT_MAX when not specified.  For VLAs
 262      with multiple variable bounds, SIZARG is the position corresponding
 263      to the most significant bound in the argument list.  Positions of
 264      subsequent bounds are in the TREE_PURPOSE field of the SIZE chain.  */
 265   unsigned ptrarg;
 266   unsigned sizarg;
 267   /* For internal specifications only, the constant minimum size of
 268      the array, zero if not specified, and HWI_M1U for the unspecified
 269      VLA [*] notation.  Meaningless for external (explicit) access
 270      specifications.  */
 271   unsigned HOST_WIDE_INT minsize;
 272
 273   /* The access mode.  */
 274   access_mode mode;
 275
 276   /* Set for an attribute added internally rather than by an explicit
 277      declaration. */
 278   bool internal_p;
 279   /* Set for the T[static MINSIZE] array notation for nonzero MINSIZE
 280      less than HWI_M1U.  */
 281   bool static_p;
 282
 283   /* Return the number of specified VLA bounds.  */
 284   unsigned vla_bounds (unsigned *) const;
 285
 286   /* Return internal representation as STRING_CST.  */
 287   tree to_internal_string () const;
 288
 289   /* Return the human-readable representation of the external attribute
 290      specification (as it might appear in the source code) as STRING_CST.  */
 291   tree to_external_string () const;
 292
 293   /* Return argument of array type formatted as a readable string.  */
 294   std::string array_as_string (tree) const;
 295
 296   /* Return the access mode corresponding to the character code.  */
 297   static access_mode from_mode_char (char);
 298
 299   /* Reset front end-specific attribute access data from attributes.  */
 300   static void free_lang_data (tree);
 301
 302   /* The character codes corresponding to all the access modes.  */
 303   static constexpr char mode_chars[5] = { '-', 'r', 'w', 'x', '^' };
 304
 305   /* The strings corresponding to just the external access modes.  */
 306   static constexpr char mode_names[4][11] =
 307     {
 308      "none", "read_only", "write_only", "read_write"
 309     };
 310 };
 311
 312 inline access_mode
 313 attr_access::from_mode_char (char c)
 314 {
 315   switch (c)
 316     {
 317     case mode_chars[access_none]: return access_none;
 318     case mode_chars[access_read_only]: return access_read_only;
 319     case mode_chars[access_write_only]: return access_write_only;
 320     case mode_chars[access_read_write]: return access_read_write;
 321     case mode_chars[access_deferred]: return access_deferred;
 322     }
 323   gcc_unreachable ();
 324 }
 325
 326 /* Used to define rdwr_map below.  */
 327 struct rdwr_access_hash: int_hash<int, -1> { };
 328
 329 /* A mapping between argument number corresponding to attribute access
 330    mode (read_only, write_only, or read_write) and operands.  */
 331 struct attr_access;
 332 typedef hash_map<rdwr_access_hash, attr_access> rdwr_map;
 333
 334 extern void init_attr_rdwr_indices (rdwr_map *, tree);
 335 extern attr_access *get_parm_access (rdwr_map &, tree,
 336                                      tree = current_function_decl);
 337
 338 #endif // GCC_ATTRIBS_H