gcc/langhooks.h

   1 /* The lang_hooks data structure.
   2    Copyright (C) 2001-2022 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
   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.cc.  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.cc.  */
  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   /* Do the equivalent of:
  72
  73        typedef struct NAME { FIELDS; } NAME;
  74
  75      associating it with location LOC.  Return the associated RECORD_TYPE.
  76
  77      FIELDS is a list of FIELD_DECLs, in layout order.  */
  78   tree (*simulate_record_decl) (location_t loc, const char *name,
  79                                 array_slice<const tree> fields);
  80
  81   /* Return what kind of RECORD_TYPE this is, mainly for purposes of
  82      debug information.  If not defined, record types are assumed to
  83      be structures.  */
  84   enum classify_record (*classify_record) (tree);
  85
  86   /* Given MODE and UNSIGNEDP, return a suitable type-tree with that
  87      mode.  */
  88   tree (*type_for_mode) (machine_mode, int);
  89
  90   /* Given PRECISION and UNSIGNEDP, return a suitable type-tree for an
  91      integer type with at least that precision.  */
  92   tree (*type_for_size) (unsigned, int);
  93
  94   /* True if the type is an instantiation of a generic type,
  95      e.g. C++ template implicit specializations.  */
  96   bool (*generic_p) (const_tree);
  97
  98   /* Returns the TREE_VEC of elements of a given generic argument pack.  */
  99   tree (*get_argument_pack_elems) (const_tree);
 100
 101   /* Given a type, apply default promotions to unnamed function
 102      arguments and return the new type.  Return the same type if no
 103      change.  Required by any language that supports variadic
 104      arguments.  The default hook dies.  */
 105   tree (*type_promotes_to) (tree);
 106
 107   /* Register TYPE as a builtin type with the indicated NAME.  The
 108      TYPE is placed in the outermost lexical scope.  The semantics
 109      should be analogous to:
 110
 111        typedef TYPE NAME;
 112
 113      in C.  The default hook ignores the declaration.  */
 114   void (*register_builtin_type) (tree, const char *);
 115
 116   /* This routine is called in tree.cc to print an error message for
 117      invalid use of an incomplete type.  VALUE is the expression that
 118      was used (or 0 if that isn't known) and TYPE is the type that was
 119      invalid.  LOC is the location of the use.  */
 120   void (*incomplete_type_error) (location_t loc, const_tree value,
 121                                  const_tree type);
 122
 123   /* Called from assign_temp to return the maximum size, if there is one,
 124      for a type.  */
 125   tree (*max_size) (const_tree);
 126
 127   /* Register language specific type size variables as potentially OpenMP
 128      firstprivate variables.  */
 129   void (*omp_firstprivatize_type_sizes) (struct gimplify_omp_ctx *, tree);
 130
 131   /* Return true if TYPE is a mappable type.  */
 132   bool (*omp_mappable_type) (tree type);
 133
 134   /* Return TRUE if TYPE1 and TYPE2 are identical for type hashing purposes.
 135      Called only after doing all language independent checks.
 136      At present, this function is only called when both TYPE1 and TYPE2 are
 137      FUNCTION_TYPE or METHOD_TYPE.  */
 138   bool (*type_hash_eq) (const_tree, const_tree);
 139
 140   /* If non-NULL, return TYPE1 with any language-specific modifiers copied from
 141      TYPE2.  */
 142   tree (*copy_lang_qualifiers) (const_tree, const_tree);
 143
 144   /* Return TRUE if TYPE uses a hidden descriptor and fills in information
 145      for the debugger about the array bounds, strides, etc.  */
 146   bool (*get_array_descr_info) (const_tree, struct array_descr_info *);
 147
 148   /* Fill in information for the debugger about the bounds of TYPE.  */
 149   void (*get_subrange_bounds) (const_tree, tree *, tree *);
 150
 151   /* Called on INTEGER_TYPEs.  Return NULL_TREE for non-biased types.  For
 152      biased types, return as an INTEGER_CST node the value that is represented
 153      by a physical zero.  */
 154   tree (*get_type_bias) (const_tree);
 155
 156   /* A type descriptive of TYPE's complex layout generated to help the
 157      debugger to decode variable-length or self-referential constructs.
 158      This is only used for the AT_GNAT_descriptive_type DWARF attribute.  */
 159   tree (*descriptive_type) (const_tree);
 160
 161   /* If we requested a pointer to a vector, build up the pointers that
 162      we stripped off while looking for the inner type.  Similarly for
 163      return values from functions.  The argument TYPE is the top of the
 164      chain, and BOTTOM is the new type which we will point to.  */
 165   tree (*reconstruct_complex_type) (tree, tree);
 166
 167   /* Returns the tree that represents the underlying data type used to
 168      implement the enumeration.  The default implementation will just use
 169      type_for_size.  Used in dwarf2out.cc to add a DW_AT_type base type
 170      reference to a DW_TAG_enumeration.  */
 171   tree (*enum_underlying_base_type) (const_tree);
 172
 173   /* Return a type to use in the debug info instead of TYPE, or NULL_TREE to
 174      keep TYPE.  This is useful to keep a single "source type" when the
 175      middle-end uses specialized types, for instance constrained discriminated
 176      types in Ada.  */
 177   tree (*get_debug_type) (const_tree);
 178
 179   /* Return TRUE if TYPE implements a fixed point type and fills in information
 180      for the debugger about scale factor, etc.  */
 181   bool (*get_fixed_point_type_info) (const_tree,
 182                                      struct fixed_point_type_info *);
 183
 184   /* Returns -1 if dwarf ATTR shouldn't be added for TYPE, or the attribute
 185      value otherwise.  */
 186   int (*type_dwarf_attribute) (const_tree, int);
 187
 188   /* Returns a tree for the unit size of T excluding tail padding that
 189      might be used by objects inheriting from T.  */
 190   tree (*unit_size_without_reusable_padding) (tree);
 191
 192   /* Returns type corresponding to FIELD's type when FIELD is a C++ base class
 193      i.e., type without virtual base classes or tail padding.  Returns
 194      NULL_TREE otherwise.  */
 195   tree (*classtype_as_base) (const_tree);
 196 };
 197
 198 /* Language hooks related to decls and the symbol table.  */
 199
 200 struct lang_hooks_for_decls
 201 {
 202   /* Return true if we are in the global binding level.  This hook is really
 203      needed only if the language supports variable-sized types at the global
 204      level, i.e. declared outside subprograms.  */
 205   bool (*global_bindings_p) (void);
 206
 207   /* Function to add a decl to the current scope level.  Takes one
 208      argument, a decl to add.  Returns that decl, or, if the same
 209      symbol is already declared, may return a different decl for that
 210      name.  */
 211   tree (*pushdecl) (tree);
 212
 213   /* Returns the chain of decls so far in the current scope level.  */
 214   tree (*getdecls) (void);
 215
 216   /* Returns -1 if dwarf ATTR shouldn't be added for DECL, or the attribute
 217      value otherwise.  */
 218   int (*decl_dwarf_attribute) (const_tree, int);
 219
 220   /* Returns True if the parameter is a generic parameter decl
 221      of a generic type, e.g a template template parameter for the C++ FE.  */
 222   bool (*generic_generic_parameter_decl_p) (const_tree);
 223
 224   /* Determine if a function parameter got expanded from a
 225      function parameter pack.  */
 226   bool (*function_parm_expanded_from_pack_p) (tree, tree);
 227
 228   /* Returns the generic declaration of a generic function instantiations.  */
 229   tree (*get_generic_function_decl) (const_tree);
 230
 231   /* Returns true when we should warn for an unused global DECL.
 232      We will already have checked that it has static binding.  */
 233   bool (*warn_unused_global) (const_tree);
 234
 235   /* Perform any post compilation-proper parser cleanups and
 236      processing.  This is currently only needed for the C++ parser,
 237      which hopefully can be cleaned up so this hook is no longer
 238      necessary.  */
 239   void (*post_compilation_parsing_cleanups) (void);
 240
 241   /* True if this decl may be called via a sibcall.  */
 242   bool (*ok_for_sibcall) (const_tree);
 243
 244   /* Return a tree for the actual data of an array descriptor - or NULL_TREE
 245      if original tree is not an array descriptor.  If the second argument
 246      is true, only the TREE_TYPE is returned without generating a new tree.  */
 247   tree (*omp_array_data) (tree, bool);
 248
 249   /* True if OpenMP should regard this DECL as being a scalar which has Fortran's
 250      allocatable or pointer attribute.  */
 251   bool (*omp_is_allocatable_or_ptr) (const_tree);
 252
 253   /* Check whether this DECL belongs to a Fortran optional argument.
 254      With 'for_present_check' set to false, decls which are optional parameters
 255      themselve are returned as tree - or a NULL_TREE otherwise. Those decls are
 256      always pointers.  With 'for_present_check' set to true, the decl for
 257      checking whether an argument is present is returned; for arguments with
 258      value attribute this is the hidden argument and of BOOLEAN_TYPE.  If the
 259      decl is unrelated to optional arguments, NULL_TREE is returned.  */
 260   tree (*omp_check_optional_argument) (tree, bool);
 261
 262   /* True if OpenMP should privatize what this DECL points to rather
 263      than the DECL itself.  */
 264   bool (*omp_privatize_by_reference) (const_tree);
 265
 266   /* Return sharing kind if OpenMP sharing attribute of DECL is
 267      predetermined, OMP_CLAUSE_DEFAULT_UNSPECIFIED otherwise.  */
 268   enum omp_clause_default_kind (*omp_predetermined_sharing) (tree);
 269
 270   /* Return mapping kind if OpenMP mapping attribute of DECL is
 271      predetermined, OMP_CLAUSE_DEFAULTMAP_CATEGORY_UNSPECIFIED otherwise.  */
 272   enum omp_clause_defaultmap_kind (*omp_predetermined_mapping) (tree);
 273
 274   /* Return decl that should be reported for DEFAULT(NONE) failure
 275      diagnostics.  Usually the DECL passed in.  */
 276   tree (*omp_report_decl) (tree);
 277
 278   /* Return true if DECL's DECL_VALUE_EXPR (if any) should be
 279      disregarded in OpenMP construct, because it is going to be
 280      remapped during OpenMP lowering.  SHARED is true if DECL
 281      is going to be shared, false if it is going to be privatized.  */
 282   bool (*omp_disregard_value_expr) (tree, bool);
 283
 284   /* Return true if DECL that is shared iff SHARED is true should
 285      be put into OMP_CLAUSE_PRIVATE_DEBUG.  */
 286   bool (*omp_private_debug_clause) (tree, bool);
 287
 288   /* Return true if DECL in private clause needs
 289      OMP_CLAUSE_PRIVATE_OUTER_REF on the private clause.  */
 290   bool (*omp_private_outer_ref) (tree);
 291
 292   /* Build and return code for a default constructor for DECL in
 293      response to CLAUSE.  OUTER is corresponding outer region's
 294      variable if needed.  Return NULL if nothing to be done.  */
 295   tree (*omp_clause_default_ctor) (tree clause, tree decl, tree outer);
 296
 297   /* Build and return code for a copy constructor from SRC to DST.  */
 298   tree (*omp_clause_copy_ctor) (tree clause, tree dst, tree src);
 299
 300   /* Similarly, except use an assignment operator instead.  */
 301   tree (*omp_clause_assign_op) (tree clause, tree dst, tree src);
 302
 303   /* Build and return code for a constructor of DST that sets it to
 304      SRC + ADD.  */
 305   tree (*omp_clause_linear_ctor) (tree clause, tree dst, tree src, tree add);
 306
 307   /* Build and return code destructing DECL.  Return NULL if nothing
 308      to be done.  */
 309   tree (*omp_clause_dtor) (tree clause, tree decl);
 310
 311   /* Do language specific checking on an implicitly determined clause.  */
 312   void (*omp_finish_clause) (tree clause, gimple_seq *pre_p, bool);
 313
 314   /* Return true if DECL is an allocatable variable (for the purpose of
 315      implicit mapping).  */
 316   bool (*omp_allocatable_p) (tree decl);
 317
 318   /* Return true if DECL is a scalar variable (for the purpose of
 319      implicit firstprivatization). If 'ptr_or', pointers and
 320      allocatables are also permitted.  */
 321   bool (*omp_scalar_p) (tree decl, bool ptr_ok);
 322
 323   /* Return true if DECL is a scalar variable with Fortran target but not
 324      allocatable or pointer attribute (for the purpose of implicit mapping).  */
 325   bool (*omp_scalar_target_p) (tree decl);
 326
 327   /* Return a pointer to the tree representing the initializer
 328      expression for the non-local variable DECL.  Return NULL if
 329      DECL is not initialized.  */
 330   tree *(*omp_get_decl_init) (tree decl);
 331
 332   /* Free any extra memory used to hold initializer information for
 333      variable declarations.  omp_get_decl_init must not be called
 334      after calling this.  */
 335   void (*omp_finish_decl_inits) (void);
 336 };
 337
 338 /* Language hooks related to LTO serialization.  */
 339
 340 struct lang_hooks_for_lto
 341 {
 342   /* Begin a new LTO section named NAME.  */
 343   void (*begin_section) (const char *name);
 344
 345   /* Write DATA of length LEN to the currently open LTO section.  BLOCK is a
 346      pointer to the dynamically allocated memory containing DATA.  The
 347      append_data function is responsible for freeing it when it is no longer
 348      needed.  */
 349   void (*append_data) (const void *data, size_t len, void *block);
 350
 351   /* End the previously begun LTO section.  */
 352   void (*end_section) (void);
 353 };
 354
 355 /* Language-specific hooks.  See langhooks-def.h for defaults.  */
 356
 357 struct lang_hooks
 358 {
 359   /* String identifying the front end and optionally language standard
 360      version, e.g. "GNU C++98".  */
 361   const char *name;
 362
 363   /* sizeof (struct lang_identifier), so make_node () creates
 364      identifier nodes long enough for the language-specific slots.  */
 365   size_t identifier_size;
 366
 367   /* Remove any parts of the tree that are used only by the FE. */
 368   void (*free_lang_data) (tree);
 369
 370   /* Determines the size of any language-specific tcc_constant,
 371      tcc_exceptional or tcc_type nodes.  Since it is called from
 372      make_node, the only information available is the tree code.
 373      Expected to die on unrecognized codes.  */
 374   size_t (*tree_size) (enum tree_code);
 375
 376   /* Return the language mask used for converting argv into a sequence
 377      of options.  */
 378   unsigned int (*option_lang_mask) (void);
 379
 380   /* Initialize variables in an options structure.  */
 381   void (*init_options_struct) (struct gcc_options *opts);
 382
 383   /* After the initialize_diagnostics hook is called, do any simple
 384      initialization needed before any calls to handle_option, other
 385      than that done by the init_options_struct hook.  */
 386   void (*init_options) (unsigned int decoded_options_count,
 387                         struct cl_decoded_option *decoded_options);
 388
 389   /* Callback used to perform language-specific initialization for the
 390      global diagnostic context structure.  */
 391   void (*initialize_diagnostics) (diagnostic_context *);
 392
 393   /* Beginning the main source file.  */
 394   void (*preprocess_main_file) (cpp_reader *, line_maps *,
 395                                 const line_map_ordinary *);
 396
 397   /* Adjust libcpp options and callbacks.  */
 398   void (*preprocess_options) (cpp_reader *);
 399
 400   /* Undefining a macro.  */
 401   void (*preprocess_undef) (cpp_reader *, location_t, cpp_hashnode *);
 402
 403   /* Observer for preprocessing stream.  */
 404   uintptr_t (*preprocess_token) (cpp_reader *, const cpp_token *, uintptr_t);
 405   /* Various flags it can return about the token.  */
 406   enum PT_flags
 407     {
 408      PT_begin_pragma = 1 << 0
 409     };
 410
 411   /* Register language-specific dumps.  */
 412   void (*register_dumps) (gcc::dump_manager *);
 413
 414   /* Return true if a warning should be given about option OPTION,
 415      which is for the wrong language, false if it should be quietly
 416      ignored.  */
 417   bool (*complain_wrong_lang_p) (const struct cl_option *option);
 418
 419   /* Handle the switch CODE, which has real type enum opt_code from
 420      options.h.  If the switch takes an argument, it is passed in ARG
 421      which points to permanent storage.  The handler is responsible for
 422      checking whether ARG is NULL, which indicates that no argument
 423      was in fact supplied.  For -f and -W switches, VALUE is 1 or 0
 424      for the positive and negative forms respectively.  HANDLERS should
 425      be passed to any recursive handle_option calls.  LOC is the
 426      location of the option.
 427
 428      Return true if the switch is valid, false if invalid.  */
 429   bool (*handle_option) (size_t code, const char *arg, HOST_WIDE_INT value,
 430                          int kind, location_t loc,
 431                          const struct cl_option_handlers *handlers);
 432
 433   /* Called when all command line options have been parsed to allow
 434      further processing and initialization
 435
 436      Should return true to indicate that a compiler back-end is
 437      not required, such as with the -E option.
 438
 439      If errorcount is nonzero after this call the compiler exits
 440      immediately and the finish hook is not called.  */
 441   bool (*post_options) (const char **);
 442
 443   /* Called after post_options to initialize the front end.  Return
 444      false to indicate that no further compilation be performed, in
 445      which case the finish hook is called immediately.  */
 446   bool (*init) (void);
 447
 448   /* Called at the end of compilation, as a finalizer.  */
 449   void (*finish) (void);
 450
 451   /* Parses the entire file.  */
 452   void (*parse_file) (void);
 453
 454   /* Determines if it's ok for a function to have no noreturn attribute.  */
 455   bool (*missing_noreturn_ok_p) (tree);
 456
 457   /* Called to obtain the alias set to be used for an expression or type.
 458      Returns -1 if the language does nothing special for it.  */
 459   alias_set_type (*get_alias_set) (tree);
 460
 461   /* Function to finish handling an incomplete decl at the end of
 462      compilation.  Default hook is does nothing.  */
 463   void (*finish_incomplete_decl) (tree);
 464
 465   /* Replace the DECL_LANG_SPECIFIC data, which may be NULL, of the
 466      DECL_NODE with a newly GC-allocated copy.  */
 467   void (*dup_lang_specific_decl) (tree);
 468
 469   /* Set the DECL_ASSEMBLER_NAME for a node.  If it is the sort of
 470      thing that the assembler should talk about, set
 471      DECL_ASSEMBLER_NAME to an appropriate IDENTIFIER_NODE.
 472      Otherwise, set it to the ERROR_MARK_NODE to ensure that the
 473      assembler does not talk about it.  */
 474   void (*set_decl_assembler_name) (tree);
 475
 476   /* Overwrite the DECL_ASSEMBLER_NAME for a node.  The name is being
 477      changed (including to or from NULL_TREE).  */
 478   void (*overwrite_decl_assembler_name) (tree, tree);
 479
 480   /* The front end can add its own statistics to -fmem-report with
 481      this hook.  It should output to stderr.  */
 482   void (*print_statistics) (void);
 483
 484   /* Called by print_tree when there is a tree of class tcc_exceptional
 485      or tcc_constant that it doesn't know how to display.  */
 486   lang_print_tree_hook print_xnode;
 487
 488   /* Called to print language-dependent parts of tcc_decl, tcc_type,
 489      and IDENTIFIER_NODE nodes.  */
 490   lang_print_tree_hook print_decl;
 491   lang_print_tree_hook print_type;
 492   lang_print_tree_hook print_identifier;
 493
 494   /* Computes the name to use to print a declaration.  DECL is the
 495      non-NULL declaration in question.  VERBOSITY determines what
 496      information will be printed: 0: DECL_NAME, demangled as
 497      necessary.  1: and scope information.  2: and any other
 498      information that might be interesting, such as function parameter
 499      types in C++.  The name is in the internal character set and
 500      needs to be converted to the locale character set of diagnostics,
 501      or to the execution character set for strings such as
 502      __PRETTY_FUNCTION__.  */
 503   const char *(*decl_printable_name) (tree decl, int verbosity);
 504
 505   /* Computes the dwarf-2/3 name for a tree.  VERBOSITY determines what
 506      information will be printed: 0: DECL_NAME, demangled as
 507      necessary.  1: and scope information.  */
 508   const char *(*dwarf_name) (tree, int verbosity);
 509
 510   /* This compares two types for equivalence ("compatible" in C-based languages).
 511      This routine should only return 1 if it is sure.  It should not be used
 512      in contexts where erroneously returning 0 causes problems.  */
 513   int (*types_compatible_p) (tree x, tree y);
 514
 515   /* Called by report_error_function to print out function name.  */
 516   void (*print_error_function) (diagnostic_context *, const char *,
 517                                 struct diagnostic_info *);
 518
 519   /* Convert a character from the host's to the target's character
 520      set.  The character should be in what C calls the "basic source
 521      character set" (roughly, the set of characters defined by plain
 522      old ASCII).  The default is to return the character unchanged,
 523      which is correct in most circumstances.  Note that both argument
 524      and result should be sign-extended under -fsigned-char,
 525      zero-extended under -fno-signed-char.  */
 526   HOST_WIDE_INT (*to_target_charset) (HOST_WIDE_INT);
 527
 528   /* Pointers to machine-independent attribute tables, for front ends
 529      using attribs.cc.  If one is NULL, it is ignored.  Respectively, a
 530      table of attributes specific to the language, a table of
 531      attributes common to two or more languages (to allow easy
 532      sharing), and a table of attributes for checking formats.  */
 533   const struct attribute_spec *attribute_table;
 534   const struct attribute_spec *common_attribute_table;
 535   const struct attribute_spec *format_attribute_table;
 536
 537   struct lang_hooks_for_tree_inlining tree_inlining;
 538
 539   struct lang_hooks_for_tree_dump tree_dump;
 540
 541   struct lang_hooks_for_decls decls;
 542
 543   struct lang_hooks_for_types types;
 544
 545   struct lang_hooks_for_lto lto;
 546
 547   /* Returns a TREE_VEC of the generic parameters of an instantiation of
 548      a generic type or decl, e.g. C++ template instantiation.  If
 549      TREE_CHAIN of the return value is set, it is an INTEGER_CST
 550      indicating how many of the elements are non-default.  */
 551   tree (*get_innermost_generic_parms) (const_tree);
 552
 553   /* Returns the TREE_VEC of arguments of an instantiation
 554      of a generic type of decl, e.g. C++ template instantiation.  */
 555   tree (*get_innermost_generic_args) (const_tree);
 556
 557   /* Determine if a tree is a function parameter pack.  */
 558   bool (*function_parameter_pack_p) (const_tree);
 559
 560   /* Perform language-specific gimplification on the argument.  Returns an
 561      enum gimplify_status, though we can't see that type here.  */
 562   int (*gimplify_expr) (tree *, gimple_seq *, gimple_seq *);
 563
 564   /* Do language specific processing in the builtin function DECL  */
 565   tree (*builtin_function) (tree decl);
 566
 567   /* Like builtin_function, but make sure the scope is the external scope.
 568      This is used to delay putting in back end builtin functions until the ISA
 569      that defines the builtin is declared via function specific target options,
 570      which can save memory for machines like the x86_64 that have multiple
 571      ISAs.  If this points to the same function as builtin_function, the
 572      backend must add all of the builtins at program initialization time.  */
 573   tree (*builtin_function_ext_scope) (tree decl);
 574
 575   /* Do language-specific processing for target-specific built-in
 576      function DECL, so that it is defined in the global scope (only)
 577      and is available without needing to be explicitly declared.
 578
 579      This is intended for targets that want to inject declarations of
 580      built-in functions into the source language (such as in response
 581      to a pragma) rather than providing them in the source language itself.  */
 582   tree (*simulate_builtin_function_decl) (tree decl);
 583
 584   /* Used to set up the tree_contains_structure array for a frontend. */
 585   void (*init_ts) (void);
 586
 587   /* Called by recompute_tree_invariant_for_addr_expr to go from EXPR
 588      to a contained expression or DECL, possibly updating *TC or *SE
 589      if in the process TREE_CONSTANT or TREE_SIDE_EFFECTS need updating.  */
 590   tree (*expr_to_decl) (tree expr, bool *tc, bool *se);
 591
 592   /* The EH personality function decl.  */
 593   tree (*eh_personality) (void);
 594
 595   /* Map a type to a runtime object to match type.  */
 596   tree (*eh_runtime_type) (tree);
 597
 598   /* If non-NULL, this is a function that returns a function decl to be
 599      executed if an unhandled exception is propagated out of a cleanup
 600      region.  For example, in C++, an exception thrown by a destructor
 601      during stack unwinding is required to result in a call to
 602      `std::terminate', so the C++ version of this function returns a
 603      FUNCTION_DECL for `std::terminate'.  */
 604   tree (*eh_protect_cleanup_actions) (void);
 605
 606   /* Return true if a stmt can fallthru.  Used by block_may_fallthru
 607      to possibly handle language trees.  */
 608   bool (*block_may_fallthru) (const_tree);
 609
 610   /* True if this language uses __cxa_end_cleanup when the ARM EABI
 611      is enabled.  */
 612   bool eh_use_cxa_end_cleanup;
 613
 614   /* True if this language requires deep unsharing of tree nodes prior to
 615      gimplification.  */
 616   bool deep_unsharing;
 617
 618   /* True if this language may use custom descriptors for nested functions
 619      instead of trampolines.  */
 620   bool custom_function_descriptors;
 621
 622   /* True if this language emits begin stmt notes.  */
 623   bool emits_begin_stmt;
 624
 625   /* Run all lang-specific selftests.  */
 626   void (*run_lang_selftests) (void);
 627
 628   /* Attempt to determine the source location of the substring.
 629      If successful, return NULL and write the source location to *OUT_LOC.
 630      Otherwise return an error message.  Error messages are intended
 631      for GCC developers (to help debugging) rather than for end-users.  */
 632   const char *(*get_substring_location) (const substring_loc &,
 633                                          location_t *out_loc);
 634
 635   /* Invoked before the early_finish debug hook is invoked.  */
 636   void (*finalize_early_debug) (void);
 637
 638   /* Whenever you add entries here, make sure you adjust langhooks-def.h
 639      and langhooks.cc accordingly.  */
 640 };
 641
 642 /* Each front end provides its own.  */
 643 extern struct lang_hooks lang_hooks;
 644
 645 extern tree add_builtin_function (const char *name, tree type,
 646                                   int function_code, enum built_in_class cl,
 647                                   const char *library_name,
 648                                   tree attrs);
 649
 650 extern tree add_builtin_function_ext_scope (const char *name, tree type,
 651                                             int function_code,
 652                                             enum built_in_class cl,
 653                                             const char *library_name,
 654                                             tree attrs);
 655 extern tree simulate_builtin_function_decl (location_t, const char *, tree,
 656                                             int, const char *, tree);
 657 extern tree add_builtin_type (const char *name, tree type);
 658
 659 /* Language helper functions.  */
 660
 661 extern bool lang_GNU_C (void);
 662 extern bool lang_GNU_CXX (void);
 663 extern bool lang_GNU_Fortran (void);
 664 extern bool lang_GNU_OBJC (void);
 665
 666 #endif /* GCC_LANG_HOOKS_H */