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