gcc/langhooks.h

   1 /* The lang_hooks data structure.
   2    Copyright (C) 2001-2021 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
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation; either version 3, or (at your option)
   9 any later version.
  10
  11 GCC is distributed in the hope that it will be useful,
  12 but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 GNU General Public License 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_LANG_HOOKS_H
  21 #define GCC_LANG_HOOKS_H
  22
  23 /* FIXME: This file should be #include-d after tree.h (for enum tree_code).  */
  24
  25 struct diagnostic_info;
  26
  27 struct gimplify_omp_ctx;
  28
  29 struct array_descr_info;
  30
  31 /* A print hook for print_tree ().  */
  32 typedef void (*lang_print_tree_hook) (FILE *, tree, int indent);
  33
  34 enum classify_record
  35   { RECORD_IS_STRUCT, RECORD_IS_CLASS, RECORD_IS_INTERFACE };
  36
  37 class substring_loc;
  38
  39 /* The following hooks are documented in langhooks.c.  Must not be
  40    NULL.  */
  41
  42 struct lang_hooks_for_tree_inlining
  43 {
  44   bool (*var_mod_type_p) (tree, tree);
  45 };
  46
  47 /* The following hooks are used by tree-dump.c.  */
  48
  49 struct lang_hooks_for_tree_dump
  50 {
  51   /* Dump language-specific parts of tree nodes.  Returns nonzero if it
  52      does not want the usual dumping of the second argument.  */
  53   bool (*dump_tree) (void *, tree);
  54
  55   /* Determine type qualifiers in a language-specific way.  */
  56   int (*type_quals) (const_tree);
  57 };
  58
  59 /* Hooks related to types.  */
  60
  61 struct lang_hooks_for_types
  62 {
  63   /* Return a new type (with the indicated CODE), doing whatever
  64      language-specific processing is required.  */
  65   tree (*make_type) (enum tree_code);
  66
  67   /* Make an enum type with the given name and values, associating
  68      them all with the given source location.  */
  69   tree (*simulate_enum_decl) (location_t, const char *, vec<string_int_pair> *);
  70
  71   /* Return what kind of RECORD_TYPE this is, mainly for purposes of
  72      debug information.  If not defined, record types are assumed to
  73      be structures.  */
  74   enum classify_record (*classify_record) (tree);
  75
  76   /* Given MODE and UNSIGNEDP, return a suitable type-tree with that
  77      mode.  */
  78   tree (*type_for_mode) (machine_mode, int);
  79
  80   /* Given PRECISION and UNSIGNEDP, return a suitable type-tree for an
  81      integer type with at least that precision.  */
  82   tree (*type_for_size) (unsigned, int);
  83
  84   /* True if the type is an instantiation of a generic type,
  85      e.g. C++ template implicit specializations.  */
  86   bool (*generic_p) (const_tree);
  87
  88   /* Returns the TREE_VEC of elements of a given generic argument pack.  */
  89   tree (*get_argument_pack_elems) (const_tree);
  90
  91   /* Given a type, apply default promotions to unnamed function
  92      arguments and return the new type.  Return the same type if no
  93      change.  Required by any language that supports variadic
  94      arguments.  The default hook dies.  */
  95   tree (*type_promotes_to) (tree);
  96
  97   /* Register TYPE as a builtin type with the indicated NAME.  The
  98      TYPE is placed in the outermost lexical scope.  The semantics
  99      should be analogous to:
 100
 101        typedef TYPE NAME;
 102
 103      in C.  The default hook ignores the declaration.  */
 104   void (*register_builtin_type) (tree, const char *);
 105
 106   /* This routine is called in tree.c to print an error message for
 107      invalid use of an incomplete type.  VALUE is the expression that
 108      was used (or 0 if that isn't known) and TYPE is the type that was
 109      invalid.  LOC is the location of the use.  */
 110   void (*incomplete_type_error) (location_t loc, const_tree value,
 111                                  const_tree type);
 112
 113   /* Called from assign_temp to return the maximum size, if there is one,
 114      for a type.  */
 115   tree (*max_size) (const_tree);
 116
 117   /* Register language specific type size variables as potentially OpenMP
 118      firstprivate variables.  */
 119   void (*omp_firstprivatize_type_sizes) (struct gimplify_omp_ctx *, tree);
 120
 121   /* Return true if TYPE is a mappable type.  */
 122   bool (*omp_mappable_type) (tree type);
 123
 124   /* Return TRUE if TYPE1 and TYPE2 are identical for type hashing purposes.
 125      Called only after doing all language independent checks.
 126      At present, this function is only called when both TYPE1 and TYPE2 are
 127      FUNCTION_TYPE or METHOD_TYPE.  */
 128   bool (*type_hash_eq) (const_tree, const_tree);
 129
 130   /* If non-NULL, return TYPE1 with any language-specific modifiers copied from
 131      TYPE2.  */
 132   tree (*copy_lang_qualifiers) (const_tree, const_tree);
 133
 134   /* Return TRUE if TYPE uses a hidden descriptor and fills in information
 135      for the debugger about the array bounds, strides, etc.  */
 136   bool (*get_array_descr_info) (const_tree, struct array_descr_info *);
 137
 138   /* Fill in information for the debugger about the bounds of TYPE.  */
 139   void (*get_subrange_bounds) (const_tree, tree *, tree *);
 140
 141   /* Called on INTEGER_TYPEs.  Return NULL_TREE for non-biased types.  For
 142      biased types, return as an INTEGER_CST node the value that is represented
 143      by a physical zero.  */
 144   tree (*get_type_bias) (const_tree);
 145
 146   /* A type descriptive of TYPE's complex layout generated to help the
 147      debugger to decode variable-length or self-referential constructs.
 148      This is only used for the AT_GNAT_descriptive_type DWARF attribute.  */
 149   tree (*descriptive_type) (const_tree);
 150
 151   /* If we requested a pointer to a vector, build up the pointers that
 152      we stripped off while looking for the inner type.  Similarly for
 153      return values from functions.  The argument TYPE is the top of the
 154      chain, and BOTTOM is the new type which we will point to.  */
 155   tree (*reconstruct_complex_type) (tree, tree);
 156
 157   /* Returns the tree that represents the underlying data type used to
 158      implement the enumeration.  The default implementation will just use
 159      type_for_size.  Used in dwarf2out.c to add a DW_AT_type base type
 160      reference to a DW_TAG_enumeration.  */
 161   tree (*enum_underlying_base_type) (const_tree);
 162
 163   /* Return a type to use in the debug info instead of TYPE, or NULL_TREE to
 164      keep TYPE.  This is useful to keep a single "source type" when the
 165      middle-end uses specialized types, for instance constrained discriminated
 166      types in Ada.  */
 167   tree (*get_debug_type) (const_tree);
 168
 169   /* Return TRUE if TYPE implements a fixed point type and fills in information
 170      for the debugger about scale factor, etc.  */
 171   bool (*get_fixed_point_type_info) (const_tree,
 172                                      struct fixed_point_type_info *);
 173
 174   /* Returns -1 if dwarf ATTR shouldn't be added for TYPE, or the attribute
 175      value otherwise.  */
 176   int (*type_dwarf_attribute) (const_tree, int);
 177
 178   /* Returns a tree for the unit size of T excluding tail padding that
 179      might be used by objects inheriting from T.  */
 180   tree (*unit_size_without_reusable_padding) (tree);
 181 };
 182
 183 /* Language hooks related to decls and the symbol table.  */
 184
 185 struct lang_hooks_for_decls
 186 {
 187   /* Return true if we are in the global binding level.  This hook is really
 188      needed only if the language supports variable-sized types at the global
 189      level, i.e. declared outside subprograms.  */
 190   bool (*global_bindings_p) (void);
 191
 192   /* Function to add a decl to the current scope level.  Takes one
 193      argument, a decl to add.  Returns that decl, or, if the same
 194      symbol is already declared, may return a different decl for that
 195      name.  */
 196   tree (*pushdecl) (tree);
 197
 198   /* Returns the chain of decls so far in the current scope level.  */
 199   tree (*getdecls) (void);
 200
 201   /* Returns -1 if dwarf ATTR shouldn't be added for DECL, or the attribute
 202      value otherwise.  */
 203   int (*decl_dwarf_attribute) (const_tree, int);
 204
 205   /* Returns True if the parameter is a generic parameter decl
 206      of a generic type, e.g a template template parameter for the C++ FE.  */
 207   bool (*generic_generic_parameter_decl_p) (const_tree);
 208
 209   /* Determine if a function parameter got expanded from a
 210      function parameter pack.  */
 211   bool (*function_parm_expanded_from_pack_p) (tree, tree);
 212
 213   /* Returns the generic declaration of a generic function instantiations.  */
 214   tree (*get_generic_function_decl) (const_tree);
 215
 216   /* Returns true when we should warn for an unused global DECL.
 217      We will already have checked that it has static binding.  */
 218   bool (*warn_unused_global) (const_tree);
 219
 220   /* Perform any post compilation-proper parser cleanups and
 221      processing.  This is currently only needed for the C++ parser,
 222      which hopefully can be cleaned up so this hook is no longer
 223      necessary.  */
 224   void (*post_compilation_parsing_cleanups) (void);
 225
 226   /* True if this decl may be called via a sibcall.  */
 227   bool (*ok_for_sibcall) (const_tree);
 228
 229   /* Return a tree for the actual data of an array descriptor - or NULL_TREE
 230      if original tree is not an array descriptor.  If the second argument
 231      is true, only the TREE_TYPE is returned without generating a new tree.  */
 232   tree (*omp_array_data) (tree, bool);
 233
 234   /* True if OpenMP should regard this DECL as being a scalar which has Fortran's
 235      allocatable or pointer attribute.  */
 236   bool (*omp_is_allocatable_or_ptr) (const_tree);
 237
 238   /* Check whether this DECL belongs to a Fortran optional argument.
 239      With 'for_present_check' set to false, decls which are optional parameters
 240      themselve are returned as tree - or a NULL_TREE otherwise. Those decls are
 241      always pointers.  With 'for_present_check' set to true, the decl for
 242      checking whether an argument is present is returned; for arguments with
 243      value attribute this is the hidden argument and of BOOLEAN_TYPE.  If the
 244      decl is unrelated to optional arguments, NULL_TREE is returned.  */
 245   tree (*omp_check_optional_argument) (tree, bool);
 246
 247   /* True if OpenMP should privatize what this DECL points to rather
 248      than the DECL itself.  */
 249   bool (*omp_privatize_by_reference) (const_tree);
 250
 251   /* Return sharing kind if OpenMP sharing attribute of DECL is
 252      predetermined, OMP_CLAUSE_DEFAULT_UNSPECIFIED otherwise.  */
 253   enum omp_clause_default_kind (*omp_predetermined_sharing) (tree);
 254
 255   /* Return mapping kind if OpenMP mapping attribute of DECL is
 256      predetermined, OMP_CLAUSE_DEFAULTMAP_CATEGORY_UNSPECIFIED otherwise.  */
 257   enum omp_clause_defaultmap_kind (*omp_predetermined_mapping) (tree);
 258
 259   /* Return decl that should be reported for DEFAULT(NONE) failure
 260      diagnostics.  Usually the DECL passed in.  */
 261   tree (*omp_report_decl) (tree);
 262
 263   /* Return true if DECL's DECL_VALUE_EXPR (if any) should be
 264      disregarded in OpenMP construct, because it is going to be
 265      remapped during OpenMP lowering.  SHARED is true if DECL
 266      is going to be shared, false if it is going to be privatized.  */
 267   bool (*omp_disregard_value_expr) (tree, bool);
 268
 269   /* Return true if DECL that is shared iff SHARED is true should
 270      be put into OMP_CLAUSE_PRIVATE_DEBUG.  */
 271   bool (*omp_private_debug_clause) (tree, bool);
 272
 273   /* Return true if DECL in private clause needs
 274      OMP_CLAUSE_PRIVATE_OUTER_REF on the private clause.  */
 275   bool (*omp_private_outer_ref) (tree);
 276
 277   /* Build and return code for a default constructor for DECL in
 278      response to CLAUSE.  OUTER is corresponding outer region's
 279      variable if needed.  Return NULL if nothing to be done.  */
 280   tree (*omp_clause_default_ctor) (tree clause, tree decl, tree outer);
 281
 282   /* Build and return code for a copy constructor from SRC to DST.  */
 283   tree (*omp_clause_copy_ctor) (tree clause, tree dst, tree src);
 284
 285   /* Similarly, except use an assignment operator instead.  */
 286   tree (*omp_clause_assign_op) (tree clause, tree dst, tree src);
 287
 288   /* Build and return code for a constructor of DST that sets it to
 289      SRC + ADD.  */
 290   tree (*omp_clause_linear_ctor) (tree clause, tree dst, tree src, tree add);
 291
 292   /* Build and return code destructing DECL.  Return NULL if nothing
 293      to be done.  */
 294   tree (*omp_clause_dtor) (tree clause, tree decl);
 295
 296   /* Do language specific checking on an implicitly determined clause.  */
 297   void (*omp_finish_clause) (tree clause, gimple_seq *pre_p, bool);
 298
 299   /* Return true if DECL is an allocatable variable (for the purpose of
 300      implicit mapping).  */
 301   bool (*omp_allocatable_p) (tree decl);
 302
 303   /* Return true if DECL is a scalar variable (for the purpose of
 304      implicit firstprivatization). If 'ptr_or', pointers and
 305      allocatables are also permitted.  */
 306   bool (*omp_scalar_p) (tree decl, bool ptr_ok);
 307
 308   /* Return true if DECL is a scalar variable with Fortran target but not
 309      allocatable or pointer attribute (for the purpose of implicit mapping).  */
 310   bool (*omp_scalar_target_p) (tree decl);
 311
 312   /* Return a pointer to the tree representing the initializer
 313      expression for the non-local variable DECL.  Return NULL if
 314      DECL is not initialized.  */
 315   tree *(*omp_get_decl_init) (tree decl);
 316
 317   /* Free any extra memory used to hold initializer information for
 318      variable declarations.  omp_get_decl_init must not be called
 319      after calling this.  */
 320   void (*omp_finish_decl_inits) (void);
 321 };
 322
 323 /* Language hooks related to LTO serialization.  */
 324
 325 struct lang_hooks_for_lto
 326 {
 327   /* Begin a new LTO section named NAME.  */
 328   void (*begin_section) (const char *name);
 329
 330   /* Write DATA of length LEN to the currently open LTO section.  BLOCK is a
 331      pointer to the dynamically allocated memory containing DATA.  The
 332      append_data function is responsible for freeing it when it is no longer
 333      needed.  */
 334   void (*append_data) (const void *data, size_t len, void *block);
 335
 336   /* End the previously begun LTO section.  */
 337   void (*end_section) (void);
 338 };
 339
 340 /* Language-specific hooks.  See langhooks-def.h for defaults.  */
 341
 342 struct lang_hooks
 343 {
 344   /* String identifying the front end and optionally language standard
 345      version, e.g. "GNU C++98".  */
 346   const char *name;
 347
 348   /* sizeof (struct lang_identifier), so make_node () creates
 349      identifier nodes long enough for the language-specific slots.  */
 350   size_t identifier_size;
 351
 352   /* Remove any parts of the tree that are used only by the FE. */
 353   void (*free_lang_data) (tree);
 354
 355   /* Determines the size of any language-specific tcc_constant,
 356      tcc_exceptional or tcc_type nodes.  Since it is called from
 357      make_node, the only information available is the tree code.
 358      Expected to die on unrecognized codes.  */
 359   size_t (*tree_size) (enum tree_code);
 360
 361   /* Return the language mask used for converting argv into a sequence
 362      of options.  */
 363   unsigned int (*option_lang_mask) (void);
 364
 365   /* Initialize variables in an options structure.  */
 366   void (*init_options_struct) (struct gcc_options *opts);
 367
 368   /* After the initialize_diagnostics hook is called, do any simple
 369      initialization needed before any calls to handle_option, other
 370      than that done by the init_options_struct hook.  */
 371   void (*init_options) (unsigned int decoded_options_count,
 372                         struct cl_decoded_option *decoded_options);
 373
 374   /* Callback used to perform language-specific initialization for the
 375      global diagnostic context structure.  */
 376   void (*initialize_diagnostics) (diagnostic_context *);
 377
 378   /* Beginning the main source file.  */
 379   void (*preprocess_main_file) (cpp_reader *, line_maps *,
 380                                 const line_map_ordinary *);
 381
 382   /* Adjust libcpp options and callbacks.  */
 383   void (*preprocess_options) (cpp_reader *);
 384
 385   /* Undefining a macro.  */
 386   void (*preprocess_undef) (cpp_reader *, location_t, cpp_hashnode *);
 387
 388   /* Observer for preprocessing stream.  */
 389   uintptr_t (*preprocess_token) (cpp_reader *, const cpp_token *, uintptr_t);
 390   /* Various flags it can return about the token.  */
 391   enum PT_flags
 392     {
 393      PT_begin_pragma = 1 << 0
 394     };
 395
 396   /* Register language-specific dumps.  */
 397   void (*register_dumps) (gcc::dump_manager *);
 398
 399   /* Return true if a warning should be given about option OPTION,
 400      which is for the wrong language, false if it should be quietly
 401      ignored.  */
 402   bool (*complain_wrong_lang_p) (const struct cl_option *option);
 403
 404   /* Handle the switch CODE, which has real type enum opt_code from
 405      options.h.  If the switch takes an argument, it is passed in ARG
 406      which points to permanent storage.  The handler is responsible for
 407      checking whether ARG is NULL, which indicates that no argument
 408      was in fact supplied.  For -f and -W switches, VALUE is 1 or 0
 409      for the positive and negative forms respectively.  HANDLERS should
 410      be passed to any recursive handle_option calls.  LOC is the
 411      location of the option.
 412
 413      Return true if the switch is valid, false if invalid.  */
 414   bool (*handle_option) (size_t code, const char *arg, HOST_WIDE_INT value,
 415                          int kind, location_t loc,
 416                          const struct cl_option_handlers *handlers);
 417
 418   /* Called when all command line options have been parsed to allow
 419      further processing and initialization
 420
 421      Should return true to indicate that a compiler back-end is
 422      not required, such as with the -E option.
 423
 424      If errorcount is nonzero after this call the compiler exits
 425      immediately and the finish hook is not called.  */
 426   bool (*post_options) (const char **);
 427
 428   /* Called after post_options to initialize the front end.  Return
 429      false to indicate that no further compilation be performed, in
 430      which case the finish hook is called immediately.  */
 431   bool (*init) (void);
 432
 433   /* Called at the end of compilation, as a finalizer.  */
 434   void (*finish) (void);
 435
 436   /* Parses the entire file.  */
 437   void (*parse_file) (void);
 438
 439   /* Determines if it's ok for a function to have no noreturn attribute.  */
 440   bool (*missing_noreturn_ok_p) (tree);
 441
 442   /* Called to obtain the alias set to be used for an expression or type.
 443      Returns -1 if the language does nothing special for it.  */
 444   alias_set_type (*get_alias_set) (tree);
 445
 446   /* Function to finish handling an incomplete decl at the end of
 447      compilation.  Default hook is does nothing.  */
 448   void (*finish_incomplete_decl) (tree);
 449
 450   /* Replace the DECL_LANG_SPECIFIC data, which may be NULL, of the
 451      DECL_NODE with a newly GC-allocated copy.  */
 452   void (*dup_lang_specific_decl) (tree);
 453
 454   /* Set the DECL_ASSEMBLER_NAME for a node.  If it is the sort of
 455      thing that the assembler should talk about, set
 456      DECL_ASSEMBLER_NAME to an appropriate IDENTIFIER_NODE.
 457      Otherwise, set it to the ERROR_MARK_NODE to ensure that the
 458      assembler does not talk about it.  */
 459   void (*set_decl_assembler_name) (tree);
 460
 461   /* Overwrite the DECL_ASSEMBLER_NAME for a node.  The name is being
 462      changed (including to or from NULL_TREE).  */
 463   void (*overwrite_decl_assembler_name) (tree, tree);
 464
 465   /* The front end can add its own statistics to -fmem-report with
 466      this hook.  It should output to stderr.  */
 467   void (*print_statistics) (void);
 468
 469   /* Called by print_tree when there is a tree of class tcc_exceptional
 470      that it doesn't know how to display.  */
 471   lang_print_tree_hook print_xnode;
 472
 473   /* Called to print language-dependent parts of tcc_decl, tcc_type,
 474      and IDENTIFIER_NODE nodes.  */
 475   lang_print_tree_hook print_decl;
 476   lang_print_tree_hook print_type;
 477   lang_print_tree_hook print_identifier;
 478
 479   /* Computes the name to use to print a declaration.  DECL is the
 480      non-NULL declaration in question.  VERBOSITY determines what
 481      information will be printed: 0: DECL_NAME, demangled as
 482      necessary.  1: and scope information.  2: and any other
 483      information that might be interesting, such as function parameter
 484      types in C++.  The name is in the internal character set and
 485      needs to be converted to the locale character set of diagnostics,
 486      or to the execution character set for strings such as
 487      __PRETTY_FUNCTION__.  */
 488   const char *(*decl_printable_name) (tree decl, int verbosity);
 489
 490   /* Computes the dwarf-2/3 name for a tree.  VERBOSITY determines what
 491      information will be printed: 0: DECL_NAME, demangled as
 492      necessary.  1: and scope information.  */
 493   const char *(*dwarf_name) (tree, int verbosity);
 494
 495   /* This compares two types for equivalence ("compatible" in C-based languages).
 496      This routine should only return 1 if it is sure.  It should not be used
 497      in contexts where erroneously returning 0 causes problems.  */
 498   int (*types_compatible_p) (tree x, tree y);
 499
 500   /* Called by report_error_function to print out function name.  */
 501   void (*print_error_function) (diagnostic_context *, const char *,
 502                                 struct diagnostic_info *);
 503
 504   /* Convert a character from the host's to the target's character
 505      set.  The character should be in what C calls the "basic source
 506      character set" (roughly, the set of characters defined by plain
 507      old ASCII).  The default is to return the character unchanged,
 508      which is correct in most circumstances.  Note that both argument
 509      and result should be sign-extended under -fsigned-char,
 510      zero-extended under -fno-signed-char.  */
 511   HOST_WIDE_INT (*to_target_charset) (HOST_WIDE_INT);
 512
 513   /* Pointers to machine-independent attribute tables, for front ends
 514      using attribs.c.  If one is NULL, it is ignored.  Respectively, a
 515      table of attributes specific to the language, a table of
 516      attributes common to two or more languages (to allow easy
 517      sharing), and a table of attributes for checking formats.  */
 518   const struct attribute_spec *attribute_table;
 519   const struct attribute_spec *common_attribute_table;
 520   const struct attribute_spec *format_attribute_table;
 521
 522   struct lang_hooks_for_tree_inlining tree_inlining;
 523
 524   struct lang_hooks_for_tree_dump tree_dump;
 525
 526   struct lang_hooks_for_decls decls;
 527
 528   struct lang_hooks_for_types types;
 529
 530   struct lang_hooks_for_lto lto;
 531
 532   /* Returns a TREE_VEC of the generic parameters of an instantiation of
 533      a generic type or decl, e.g. C++ template instantiation.  If
 534      TREE_CHAIN of the return value is set, it is an INTEGER_CST
 535      indicating how many of the elements are non-default.  */
 536   tree (*get_innermost_generic_parms) (const_tree);
 537
 538   /* Returns the TREE_VEC of arguments of an instantiation
 539      of a generic type of decl, e.g. C++ template instantiation.  */
 540   tree (*get_innermost_generic_args) (const_tree);
 541
 542   /* Determine if a tree is a function parameter pack.  */
 543   bool (*function_parameter_pack_p) (const_tree);
 544
 545   /* Perform language-specific gimplification on the argument.  Returns an
 546      enum gimplify_status, though we can't see that type here.  */
 547   int (*gimplify_expr) (tree *, gimple_seq *, gimple_seq *);
 548
 549   /* Do language specific processing in the builtin function DECL  */
 550   tree (*builtin_function) (tree decl);
 551
 552   /* Like builtin_function, but make sure the scope is the external scope.
 553      This is used to delay putting in back end builtin functions until the ISA
 554      that defines the builtin is declared via function specific target options,
 555      which can save memory for machines like the x86_64 that have multiple
 556      ISAs.  If this points to the same function as builtin_function, the
 557      backend must add all of the builtins at program initialization time.  */
 558   tree (*builtin_function_ext_scope) (tree decl);
 559
 560   /* Do language-specific processing for target-specific built-in
 561      function DECL, so that it is defined in the global scope (only)
 562      and is available without needing to be explicitly declared.
 563
 564      This is intended for targets that want to inject declarations of
 565      built-in functions into the source language (such as in response
 566      to a pragma) rather than providing them in the source language itself.  */
 567   tree (*simulate_builtin_function_decl) (tree decl);
 568
 569   /* Used to set up the tree_contains_structure array for a frontend. */
 570   void (*init_ts) (void);
 571
 572   /* Called by recompute_tree_invariant_for_addr_expr to go from EXPR
 573      to a contained expression or DECL, possibly updating *TC or *SE
 574      if in the process TREE_CONSTANT or TREE_SIDE_EFFECTS need updating.  */
 575   tree (*expr_to_decl) (tree expr, bool *tc, bool *se);
 576
 577   /* The EH personality function decl.  */
 578   tree (*eh_personality) (void);
 579
 580   /* Map a type to a runtime object to match type.  */
 581   tree (*eh_runtime_type) (tree);
 582
 583   /* If non-NULL, this is a function that returns a function decl to be
 584      executed if an unhandled exception is propagated out of a cleanup
 585      region.  For example, in C++, an exception thrown by a destructor
 586      during stack unwinding is required to result in a call to
 587      `std::terminate', so the C++ version of this function returns a
 588      FUNCTION_DECL for `std::terminate'.  */
 589   tree (*eh_protect_cleanup_actions) (void);
 590
 591   /* Return true if a stmt can fallthru.  Used by block_may_fallthru
 592      to possibly handle language trees.  */
 593   bool (*block_may_fallthru) (const_tree);
 594
 595   /* True if this language uses __cxa_end_cleanup when the ARM EABI
 596      is enabled.  */
 597   bool eh_use_cxa_end_cleanup;
 598
 599   /* True if this language requires deep unsharing of tree nodes prior to
 600      gimplification.  */
 601   bool deep_unsharing;
 602
 603   /* True if this language may use custom descriptors for nested functions
 604      instead of trampolines.  */
 605   bool custom_function_descriptors;
 606
 607   /* True if this language emits begin stmt notes.  */
 608   bool emits_begin_stmt;
 609
 610   /* Run all lang-specific selftests.  */
 611   void (*run_lang_selftests) (void);
 612
 613   /* Attempt to determine the source location of the substring.
 614      If successful, return NULL and write the source location to *OUT_LOC.
 615      Otherwise return an error message.  Error messages are intended
 616      for GCC developers (to help debugging) rather than for end-users.  */
 617   const char *(*get_substring_location) (const substring_loc &,
 618                                          location_t *out_loc);
 619
 620   /* Invoked before the early_finish debug hook is invoked.  */
 621   void (*finalize_early_debug) (void);
 622
 623   /* Whenever you add entries here, make sure you adjust langhooks-def.h
 624      and langhooks.c accordingly.  */
 625 };
 626
 627 /* Each front end provides its own.  */
 628 extern struct lang_hooks lang_hooks;
 629
 630 extern tree add_builtin_function (const char *name, tree type,
 631                                   int function_code, enum built_in_class cl,
 632                                   const char *library_name,
 633                                   tree attrs);
 634
 635 extern tree add_builtin_function_ext_scope (const char *name, tree type,
 636                                             int function_code,
 637                                             enum built_in_class cl,
 638                                             const char *library_name,
 639                                             tree attrs);
 640 extern tree simulate_builtin_function_decl (location_t, const char *, tree,
 641                                             int, const char *, tree);
 642 extern tree add_builtin_type (const char *name, tree type);
 643
 644 /* Language helper functions.  */
 645
 646 extern bool lang_GNU_C (void);
 647 extern bool lang_GNU_CXX (void);
 648 extern bool lang_GNU_Fortran (void);
 649 extern bool lang_GNU_OBJC (void);
 650
 651 #endif /* GCC_LANG_HOOKS_H */