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