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 a scalar variable (for the purpose of
300      implicit firstprivatization).  */
301   bool (*omp_scalar_p) (tree decl);
302 
303   /* Return a pointer to the tree representing the initializer
304      expression for the non-local variable DECL.  Return NULL if
305      DECL is not initialized.  */
306   tree *(*omp_get_decl_init) (tree decl);
307 
308   /* Free any extra memory used to hold initializer information for
309      variable declarations.  omp_get_decl_init must not be called
310      after calling this.  */
311   void (*omp_finish_decl_inits) (void);
312 };
313 
314 /* Language hooks related to LTO serialization.  */
315 
316 struct lang_hooks_for_lto
317 {
318   /* Begin a new LTO section named NAME.  */
319   void (*begin_section) (const char *name);
320 
321   /* Write DATA of length LEN to the currently open LTO section.  BLOCK is a
322      pointer to the dynamically allocated memory containing DATA.  The
323      append_data function is responsible for freeing it when it is no longer
324      needed.  */
325   void (*append_data) (const void *data, size_t len, void *block);
326 
327   /* End the previously begun LTO section.  */
328   void (*end_section) (void);
329 };
330 
331 /* Language-specific hooks.  See langhooks-def.h for defaults.  */
332 
333 struct lang_hooks
334 {
335   /* String identifying the front end and optionally language standard
336      version, e.g. "GNU C++98".  */
337   const char *name;
338 
339   /* sizeof (struct lang_identifier), so make_node () creates
340      identifier nodes long enough for the language-specific slots.  */
341   size_t identifier_size;
342 
343   /* Remove any parts of the tree that are used only by the FE. */
344   void (*free_lang_data) (tree);
345 
346   /* Determines the size of any language-specific tcc_constant,
347      tcc_exceptional or tcc_type nodes.  Since it is called from
348      make_node, the only information available is the tree code.
349      Expected to die on unrecognized codes.  */
350   size_t (*tree_size) (enum tree_code);
351 
352   /* Return the language mask used for converting argv into a sequence
353      of options.  */
354   unsigned int (*option_lang_mask) (void);
355 
356   /* Initialize variables in an options structure.  */
357   void (*init_options_struct) (struct gcc_options *opts);
358 
359   /* After the initialize_diagnostics hook is called, do any simple
360      initialization needed before any calls to handle_option, other
361      than that done by the init_options_struct hook.  */
362   void (*init_options) (unsigned int decoded_options_count,
363 			struct cl_decoded_option *decoded_options);
364 
365   /* Callback used to perform language-specific initialization for the
366      global diagnostic context structure.  */
367   void (*initialize_diagnostics) (diagnostic_context *);
368 
369   /* Beginning the main source file.  */
370   void (*preprocess_main_file) (cpp_reader *, line_maps *,
371 				const line_map_ordinary *);
372 
373   /* Adjust libcpp options and callbacks.  */
374   void (*preprocess_options) (cpp_reader *);
375 
376   /* Undefining a macro.  */
377   void (*preprocess_undef) (cpp_reader *, location_t, cpp_hashnode *);
378 
379   /* Observer for preprocessing stream.  */
380   uintptr_t (*preprocess_token) (cpp_reader *, const cpp_token *, uintptr_t);
381   /* Various flags it can return about the token.  */
382   enum PT_flags
383     {
384      PT_begin_pragma = 1 << 0
385     };
386 
387   /* Register language-specific dumps.  */
388   void (*register_dumps) (gcc::dump_manager *);
389 
390   /* Return true if a warning should be given about option OPTION,
391      which is for the wrong language, false if it should be quietly
392      ignored.  */
393   bool (*complain_wrong_lang_p) (const struct cl_option *option);
394 
395   /* Handle the switch CODE, which has real type enum opt_code from
396      options.h.  If the switch takes an argument, it is passed in ARG
397      which points to permanent storage.  The handler is responsible for
398      checking whether ARG is NULL, which indicates that no argument
399      was in fact supplied.  For -f and -W switches, VALUE is 1 or 0
400      for the positive and negative forms respectively.  HANDLERS should
401      be passed to any recursive handle_option calls.  LOC is the
402      location of the option.
403 
404      Return true if the switch is valid, false if invalid.  */
405   bool (*handle_option) (size_t code, const char *arg, HOST_WIDE_INT value,
406 			 int kind, location_t loc,
407 			 const struct cl_option_handlers *handlers);
408 
409   /* Called when all command line options have been parsed to allow
410      further processing and initialization
411 
412      Should return true to indicate that a compiler back-end is
413      not required, such as with the -E option.
414 
415      If errorcount is nonzero after this call the compiler exits
416      immediately and the finish hook is not called.  */
417   bool (*post_options) (const char **);
418 
419   /* Called after post_options to initialize the front end.  Return
420      false to indicate that no further compilation be performed, in
421      which case the finish hook is called immediately.  */
422   bool (*init) (void);
423 
424   /* Called at the end of compilation, as a finalizer.  */
425   void (*finish) (void);
426 
427   /* Parses the entire file.  */
428   void (*parse_file) (void);
429 
430   /* Determines if it's ok for a function to have no noreturn attribute.  */
431   bool (*missing_noreturn_ok_p) (tree);
432 
433   /* Called to obtain the alias set to be used for an expression or type.
434      Returns -1 if the language does nothing special for it.  */
435   alias_set_type (*get_alias_set) (tree);
436 
437   /* Function to finish handling an incomplete decl at the end of
438      compilation.  Default hook is does nothing.  */
439   void (*finish_incomplete_decl) (tree);
440 
441   /* Replace the DECL_LANG_SPECIFIC data, which may be NULL, of the
442      DECL_NODE with a newly GC-allocated copy.  */
443   void (*dup_lang_specific_decl) (tree);
444 
445   /* Set the DECL_ASSEMBLER_NAME for a node.  If it is the sort of
446      thing that the assembler should talk about, set
447      DECL_ASSEMBLER_NAME to an appropriate IDENTIFIER_NODE.
448      Otherwise, set it to the ERROR_MARK_NODE to ensure that the
449      assembler does not talk about it.  */
450   void (*set_decl_assembler_name) (tree);
451 
452   /* Overwrite the DECL_ASSEMBLER_NAME for a node.  The name is being
453      changed (including to or from NULL_TREE).  */
454   void (*overwrite_decl_assembler_name) (tree, tree);
455 
456   /* The front end can add its own statistics to -fmem-report with
457      this hook.  It should output to stderr.  */
458   void (*print_statistics) (void);
459 
460   /* Called by print_tree when there is a tree of class tcc_exceptional
461      that it doesn't know how to display.  */
462   lang_print_tree_hook print_xnode;
463 
464   /* Called to print language-dependent parts of tcc_decl, tcc_type,
465      and IDENTIFIER_NODE nodes.  */
466   lang_print_tree_hook print_decl;
467   lang_print_tree_hook print_type;
468   lang_print_tree_hook print_identifier;
469 
470   /* Computes the name to use to print a declaration.  DECL is the
471      non-NULL declaration in question.  VERBOSITY determines what
472      information will be printed: 0: DECL_NAME, demangled as
473      necessary.  1: and scope information.  2: and any other
474      information that might be interesting, such as function parameter
475      types in C++.  The name is in the internal character set and
476      needs to be converted to the locale character set of diagnostics,
477      or to the execution character set for strings such as
478      __PRETTY_FUNCTION__.  */
479   const char *(*decl_printable_name) (tree decl, int verbosity);
480 
481   /* Computes the dwarf-2/3 name for a tree.  VERBOSITY determines what
482      information will be printed: 0: DECL_NAME, demangled as
483      necessary.  1: and scope information.  */
484   const char *(*dwarf_name) (tree, int verbosity);
485 
486   /* This compares two types for equivalence ("compatible" in C-based languages).
487      This routine should only return 1 if it is sure.  It should not be used
488      in contexts where erroneously returning 0 causes problems.  */
489   int (*types_compatible_p) (tree x, tree y);
490 
491   /* Called by report_error_function to print out function name.  */
492   void (*print_error_function) (diagnostic_context *, const char *,
493 				struct diagnostic_info *);
494 
495   /* Convert a character from the host's to the target's character
496      set.  The character should be in what C calls the "basic source
497      character set" (roughly, the set of characters defined by plain
498      old ASCII).  The default is to return the character unchanged,
499      which is correct in most circumstances.  Note that both argument
500      and result should be sign-extended under -fsigned-char,
501      zero-extended under -fno-signed-char.  */
502   HOST_WIDE_INT (*to_target_charset) (HOST_WIDE_INT);
503 
504   /* Pointers to machine-independent attribute tables, for front ends
505      using attribs.c.  If one is NULL, it is ignored.  Respectively, a
506      table of attributes specific to the language, a table of
507      attributes common to two or more languages (to allow easy
508      sharing), and a table of attributes for checking formats.  */
509   const struct attribute_spec *attribute_table;
510   const struct attribute_spec *common_attribute_table;
511   const struct attribute_spec *format_attribute_table;
512 
513   struct lang_hooks_for_tree_inlining tree_inlining;
514 
515   struct lang_hooks_for_tree_dump tree_dump;
516 
517   struct lang_hooks_for_decls decls;
518 
519   struct lang_hooks_for_types types;
520 
521   struct lang_hooks_for_lto lto;
522 
523   /* Returns a TREE_VEC of the generic parameters of an instantiation of
524      a generic type or decl, e.g. C++ template instantiation.  If
525      TREE_CHAIN of the return value is set, it is an INTEGER_CST
526      indicating how many of the elements are non-default.  */
527   tree (*get_innermost_generic_parms) (const_tree);
528 
529   /* Returns the TREE_VEC of arguments of an instantiation
530      of a generic type of decl, e.g. C++ template instantiation.  */
531   tree (*get_innermost_generic_args) (const_tree);
532 
533   /* Determine if a tree is a function parameter pack.  */
534   bool (*function_parameter_pack_p) (const_tree);
535 
536   /* Perform language-specific gimplification on the argument.  Returns an
537      enum gimplify_status, though we can't see that type here.  */
538   int (*gimplify_expr) (tree *, gimple_seq *, gimple_seq *);
539 
540   /* Do language specific processing in the builtin function DECL  */
541   tree (*builtin_function) (tree decl);
542 
543   /* Like builtin_function, but make sure the scope is the external scope.
544      This is used to delay putting in back end builtin functions until the ISA
545      that defines the builtin is declared via function specific target options,
546      which can save memory for machines like the x86_64 that have multiple
547      ISAs.  If this points to the same function as builtin_function, the
548      backend must add all of the builtins at program initialization time.  */
549   tree (*builtin_function_ext_scope) (tree decl);
550 
551   /* Do language-specific processing for target-specific built-in
552      function DECL, so that it is defined in the global scope (only)
553      and is available without needing to be explicitly declared.
554 
555      This is intended for targets that want to inject declarations of
556      built-in functions into the source language (such as in response
557      to a pragma) rather than providing them in the source language itself.  */
558   tree (*simulate_builtin_function_decl) (tree decl);
559 
560   /* Used to set up the tree_contains_structure array for a frontend. */
561   void (*init_ts) (void);
562 
563   /* Called by recompute_tree_invariant_for_addr_expr to go from EXPR
564      to a contained expression or DECL, possibly updating *TC or *SE
565      if in the process TREE_CONSTANT or TREE_SIDE_EFFECTS need updating.  */
566   tree (*expr_to_decl) (tree expr, bool *tc, bool *se);
567 
568   /* The EH personality function decl.  */
569   tree (*eh_personality) (void);
570 
571   /* Map a type to a runtime object to match type.  */
572   tree (*eh_runtime_type) (tree);
573 
574   /* If non-NULL, this is a function that returns a function decl to be
575      executed if an unhandled exception is propagated out of a cleanup
576      region.  For example, in C++, an exception thrown by a destructor
577      during stack unwinding is required to result in a call to
578      `std::terminate', so the C++ version of this function returns a
579      FUNCTION_DECL for `std::terminate'.  */
580   tree (*eh_protect_cleanup_actions) (void);
581 
582   /* Return true if a stmt can fallthru.  Used by block_may_fallthru
583      to possibly handle language trees.  */
584   bool (*block_may_fallthru) (const_tree);
585 
586   /* True if this language uses __cxa_end_cleanup when the ARM EABI
587      is enabled.  */
588   bool eh_use_cxa_end_cleanup;
589 
590   /* True if this language requires deep unsharing of tree nodes prior to
591      gimplification.  */
592   bool deep_unsharing;
593 
594   /* True if this language may use custom descriptors for nested functions
595      instead of trampolines.  */
596   bool custom_function_descriptors;
597 
598   /* True if this language emits begin stmt notes.  */
599   bool emits_begin_stmt;
600 
601   /* Run all lang-specific selftests.  */
602   void (*run_lang_selftests) (void);
603 
604   /* Attempt to determine the source location of the substring.
605      If successful, return NULL and write the source location to *OUT_LOC.
606      Otherwise return an error message.  Error messages are intended
607      for GCC developers (to help debugging) rather than for end-users.  */
608   const char *(*get_substring_location) (const substring_loc &,
609 					 location_t *out_loc);
610 
611   /* Invoked before the early_finish debug hook is invoked.  */
612   void (*finalize_early_debug) (void);
613 
614   /* Whenever you add entries here, make sure you adjust langhooks-def.h
615      and langhooks.c accordingly.  */
616 };
617 
618 /* Each front end provides its own.  */
619 extern struct lang_hooks lang_hooks;
620 
621 extern tree add_builtin_function (const char *name, tree type,
622 				  int function_code, enum built_in_class cl,
623 				  const char *library_name,
624 				  tree attrs);
625 
626 extern tree add_builtin_function_ext_scope (const char *name, tree type,
627 					    int function_code,
628 					    enum built_in_class cl,
629 					    const char *library_name,
630 					    tree attrs);
631 extern tree simulate_builtin_function_decl (location_t, const char *, tree,
632 					    int, const char *, tree);
633 extern tree add_builtin_type (const char *name, tree type);
634 
635 /* Language helper functions.  */
636 
637 extern bool lang_GNU_C (void);
638 extern bool lang_GNU_CXX (void);
639 extern bool lang_GNU_Fortran (void);
640 extern bool lang_GNU_OBJC (void);
641 
642 #endif /* GCC_LANG_HOOKS_H */
643