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