1 /* Target hook definitions.
2 Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010
3 Free Software Foundation, Inc.
5 This program is free software; you can redistribute it and/or modify it
6 under the terms of the GNU General Public License as published by the
7 Free Software Foundation; either version 3, or (at your option) any
10 This program is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 GNU General Public License for more details.
15 You should have received a copy of the GNU General Public License
16 along with this program; see the file COPYING3. If not see
17 <http://www.gnu.org/licenses/>.
19 In other words, you are welcome to use, share and improve this program.
20 You are forbidden to forbid anyone else to use, share and improve
21 what you give them. Help stamp out software-hoarding! */
23 /* The following macros should be provided by the including file:
25 DEFHOOK(NAME, DOC, TYPE, PARAMS, INIT): Define a function-valued hook.
26 DEFHOOKPOD(DOC, TYPE, NAME, INIT): Define a piece-of-data 'hook'. */
28 /* Defaults for optional macros:
29 DEFHOOKPODX(NAME, TYPE, INIT): Like DEFHOOKPOD, but share documentation
30 with the previous 'hook'. */
32 #define DEFHOOKPODX(NAME, TYPE, INIT) DEFHOOKPOD (NAME, 0, TYPE, INIT)
35 /* HOOKSTRUCT(FRAGMENT): Declarator fragments to encapsulate all the
36 members into a struct gcc_target, which in turn contains several
39 #define HOOKSTRUCT(FRAGMENT)
41 /* HOOK_VECTOR: Start a struct declaration, which then gets its own initializer.
42 HOOK_VECTOR_END: Close a struct declaration, providing a member declarator
43 name for nested use. */
45 #define HOOK_VECTOR_1(NAME, FRAGMENT) HOOKSTRUCT(FRAGMENT)
47 #define HOOK_VECTOR(INIT_NAME, SNAME) HOOK_VECTOR_1 (INIT_NAME, struct SNAME {)
48 #define HOOK_VECTOR_END(DECL_NAME) HOOK_VECTOR_1(,} DECL_NAME ;)
50 HOOK_VECTOR (TARGET_INITIALIZER, gcc_target)
52 /* FIXME: For pre-existing hooks, we can't place the documentation in the
53 documentation field here till we get permission from the FSF to include
54 it in GPLed software - the target hook documentation is so far only
55 available under the GFDL. */
57 /* A hook should generally be documented by a string in the DOC parameter,
58 which should contain texinfo markup. If the documentation is only available
59 under the GPL, but not under the GFDL, put it in a comment above the hook
60 definition. If the function declaration is available both under GPL and
61 GFDL, but the documentation is only available under the GFDL, put the
62 documentaton in tm.texi.in, heading with @hook <hookname> and closing
63 the paragraph with @end deftypefn / deftypevr as appropriate, and marking
64 the next autogenerated hook with @hook <hookname>.
65 In both these cases, leave the DOC string empty, i.e. "".
66 Sometimes, for some historic reason the function declaration
67 has to be documented differently
68 than what it is. In that case, use DEFHOOK_UNDOC to supress auto-generation
69 of documentation. DEFHOOK_UNDOC takes a DOC string which it ignores, so
70 you can put GPLed documentation string there if you have hopes that you
71 can clear the declaration & documentation for GFDL distribution later,
72 in which case you can then simply change the DEFHOOK_UNDOC to DEFHOOK
73 to turn on the autogeneration of the documentation.
75 A documentation string of "*" means not to emit any documentation at all,
76 and is mainly used internally for DEFHOOK_UNDOC. It should generally not
77 be used otherwise, but it has its use for exceptional cases where automatic
78 documentation is not wanted, and the real documentation is elsewere, like
79 for TARGET_ASM_{,UN}ALIGNED_INT_OP, which are hooks only for implementation
80 purposes; they refer to structs, the components of which are documented as
81 separate hooks TARGET_ASM_{,UN}ALIGNED_[HSDT]I_OP.
82 A DOC string of 0 is for internal use of DEFHOOKPODX and special table
85 /* Functions that output assembler for the target. */
86 #define HOOK_PREFIX "TARGET_ASM_"
87 HOOK_VECTOR (TARGET_ASM_OUT, asm_out)
89 /* Opening and closing parentheses for asm expression grouping. */
94 DEFHOOKPODX (close_paren, const char *, ")")
96 /* Assembler instructions for creating various kinds of integer object. */
100 const char *, "\t.byte\t")
101 DEFHOOKPOD (aligned_op, "*", struct asm_int_op, TARGET_ASM_ALIGNED_INT_OP)
102 DEFHOOKPOD (unaligned_op, "*", struct asm_int_op, TARGET_ASM_UNALIGNED_INT_OP)
104 /* The maximum number of bytes to skip when applying
105 LABEL_ALIGN_AFTER_BARRIER. */
107 (label_align_after_barrier_max_skip,
110 default_label_align_after_barrier_max_skip)
112 /* The maximum number of bytes to skip when applying
115 (loop_align_max_skip,
118 default_loop_align_max_skip)
120 /* The maximum number of bytes to skip when applying
123 (label_align_max_skip,
126 default_label_align_max_skip)
128 /* The maximum number of bytes to skip when applying
131 (jump_align_max_skip,
134 default_jump_align_max_skip)
136 /* Try to output the assembler code for an integer object whose
137 value is given by X. SIZE is the size of the object in bytes and
138 ALIGNED_P indicates whether it is aligned. Return true if
139 successful. Only handles cases for which BYTE_OP, ALIGNED_OP
140 and UNALIGNED_OP are NULL. */
144 /* Only handles cases for which BYTE_OP, ALIGNED_OP and UNALIGNED_OP are
146 bool, (rtx x, unsigned int size, int aligned_p),
147 default_assemble_integer)
149 /* Output code that will globalize a label. */
153 void, (FILE *stream, const char *name),
154 default_globalize_label)
156 /* Output code that will globalize a declaration. */
158 (globalize_decl_name,
160 void, (FILE *stream, tree decl), default_globalize_decl_name)
162 /* Output code that will emit a label for unwind info, if this
163 target requires such labels. Second argument is the decl the
164 unwind info is associated with, third is a boolean: true if
165 this is for exception handling, fourth is a boolean: true if
166 this is only a placeholder for an omitted FDE. */
170 void, (FILE *stream, tree decl, int for_eh, int empty),
171 default_emit_unwind_label)
173 /* Output code that will emit a label to divide up the exception table. */
175 (emit_except_table_label,
177 void, (FILE *stream),
178 default_emit_except_table_label)
180 /* Emit a directive for setting the personality for the function. */
182 (emit_except_personality,
183 "If the target implements @code{TARGET_ASM_UNWIND_EMIT}, this hook may be\
184 used to emit a directive to install a personality hook into the unwind\
185 info. This hook should not be used if dwarf2 unwind info is used.",
186 void, (rtx personality),
189 /* Emit any directives required to unwind this instruction. */
193 void, (FILE *stream, rtx insn),
197 (unwind_emit_before_insn,
198 "True if the @code{TARGET_ASM_UNWIND_EMIT} hook should be called before\
199 the assembly for @var{insn} has been emitted, false if the hook should\
200 be called afterward.",
203 /* Generate an internal label.
204 For now this is just a wrapper for ASM_GENERATE_INTERNAL_LABEL. */
206 (generate_internal_label,
208 void, (char *buf, const char *prefix, unsigned long labelno),
209 default_generate_internal_label)
211 /* Output an internal label. */
215 void, (FILE *stream, const char *prefix, unsigned long labelno),
216 default_internal_label)
218 /* Output label for the constant. */
220 (declare_constant_name,
222 void, (FILE *file, const char *name, const_tree expr, HOST_WIDE_INT size),
223 default_asm_declare_constant_name)
225 /* Emit a ttype table reference to a typeinfo object. */
232 /* Emit an assembler directive to set visibility for the symbol
233 associated with the tree decl. */
235 (assemble_visibility,
237 void, (tree decl, int visibility),
238 default_assemble_visibility)
240 /* Output the assembler code for entry to a function. */
244 void, (FILE *file, HOST_WIDE_INT size),
245 default_function_pro_epilogue)
247 /* Output the assembler code for end of prologue. */
249 (function_end_prologue,
254 /* Output the assembler code for start of epilogue. */
256 (function_begin_epilogue,
261 /* Output the assembler code for function exit. */
265 void, (FILE *file, HOST_WIDE_INT size),
266 default_function_pro_epilogue)
268 /* Initialize target-specific sections. */
275 /* Tell assembler to change to section NAME with attributes FLAGS.
276 If DECL is non-NULL, it is the VAR_DECL or FUNCTION_DECL with
277 which this section is associated. */
281 void, (const char *name, unsigned int flags, tree decl),
282 default_no_named_section)
284 /* Return preferred text (sub)section for function DECL.
285 Main purpose of this function is to separate cold, normal and hot
286 functions. STARTUP is true when function is known to be used only
287 at startup (from static constructors or it is main()).
288 EXIT is true when function is known to be used only at exit
289 (from static destructors).
290 Return NULL if function should go to default text section. */
294 section *, (tree decl, enum node_frequency freq, bool startup, bool exit),
295 default_function_section)
297 /* Output the assembler code for function exit. */
299 (function_switched_text_sections,
300 "Used by the target to emit any assembler directives or additional\
301 labels needed when a function is partitioned between different\
302 sections. Output should be written to @var{file}. The function\
303 decl is available as @var{decl} and the new section is `cold' if\
304 @var{new_is_cold} is @code{true}.",
305 void, (FILE *file, tree decl, bool new_is_cold),
306 default_function_switched_text_sections)
308 /* Return a mask describing how relocations should be treated when
309 selecting sections. Bit 1 should be set if global relocations
310 should be placed in a read-write section; bit 0 should be set if
311 local relocations should be placed in a read-write section. */
316 default_reloc_rw_mask)
318 /* Return a section for EXP. It may be a DECL or a constant. RELOC
319 is nonzero if runtime relocations must be applied; bit 1 will be
320 set if the runtime relocations require non-local name resolution.
321 ALIGN is the required alignment of the data. */
325 section *, (tree exp, int reloc, unsigned HOST_WIDE_INT align),
326 default_select_section)
328 /* Return a section for X. MODE is X's mode and ALIGN is its
329 alignment in bits. */
333 section *, (enum machine_mode mode, rtx x, unsigned HOST_WIDE_INT align),
334 default_select_rtx_section)
336 /* Select a unique section name for DECL. RELOC is the same as
337 for SELECT_SECTION. */
341 void, (tree decl, int reloc),
342 default_unique_section)
344 /* Return the readonly data section associated with function DECL. */
346 (function_rodata_section,
348 section *, (tree decl),
349 default_function_rodata_section)
351 /* Output a constructor for a symbol with a given priority. */
355 void, (rtx symbol, int priority), NULL)
357 /* Output a destructor for a symbol with a given priority. */
361 void, (rtx symbol, int priority), NULL)
363 /* Output the assembler code for a thunk function. THUNK_DECL is the
364 declaration for the thunk function itself, FUNCTION is the decl for
365 the target function. DELTA is an immediate constant offset to be
366 added to THIS. If VCALL_OFFSET is nonzero, the word at
367 *(*this + vcall_offset) should be added to THIS. */
371 void, (FILE *file, tree thunk_fndecl, HOST_WIDE_INT delta,
372 HOST_WIDE_INT vcall_offset, tree function),
375 /* Determine whether output_mi_thunk would succeed. */
376 /* ??? Ideally, this hook would not exist, and success or failure
377 would be returned from output_mi_thunk directly. But there's
378 too much undo-able setup involved in invoking output_mi_thunk.
379 Could be fixed by making output_mi_thunk emit rtl instead of
380 text to the output file. */
382 (can_output_mi_thunk,
384 bool, (const_tree thunk_fndecl, HOST_WIDE_INT delta,
385 HOST_WIDE_INT vcall_offset, const_tree function),
386 hook_bool_const_tree_hwi_hwi_const_tree_false)
388 /* Output any boilerplate text needed at the beginning of a
396 /* Output any boilerplate text needed at the end of a translation unit. */
403 /* Output any boilerplate text needed at the beginning of an
404 LTO output stream. */
411 /* Output any boilerplate text needed at the end of an
412 LTO output stream. */
419 /* Output any boilerplace text needed at the end of a
420 translation unit before debug and unwind info is emitted. */
427 /* Output an assembler pseudo-op to declare a library function name
433 default_external_libcall)
435 /* Output an assembler directive to mark decl live. This instructs
436 linker to not dead code strip this symbol. */
438 (mark_decl_preserved,
440 void, (const char *symbol),
441 hook_void_constcharptr)
443 /* Output a record of the command line switches that have been passed. */
445 (record_gcc_switches,
447 int, (print_switch_type type, const char *text),
450 /* The name of the section that the example ELF implementation of
451 record_gcc_switches will use to store the information. Target
452 specific versions of record_gcc_switches may or may not use
455 (record_gcc_switches_section,
457 const char *, ".GCC.command.line")
459 /* Output the definition of a section anchor. */
464 default_asm_output_anchor)
466 /* Output a DTP-relative reference to a TLS symbol. */
468 (output_dwarf_dtprel,
470 void, (FILE *file, int size, rtx x),
473 /* Some target machines need to postscan each insn after it is output. */
475 (final_postscan_insn,
477 void, (FILE *file, rtx insn, rtx *opvec, int noperands),
480 /* Emit the trampoline template. This hook may be NULL. */
482 (trampoline_template,
488 (output_source_filename,
489 "Output COFF information or DWARF debugging information which indicates\
490 that filename @var{name} is the current source file to the stdio\
491 stream @var{file}.\n\
493 This target hook need not be defined if the standard form of output\
494 for the file format in use is appropriate.",
495 void ,(FILE *file, const char *name),
496 default_asm_output_source_filename)
499 (output_addr_const_extra,
501 bool, (FILE *file, rtx x),
502 default_asm_output_addr_const_extra)
504 /* ??? The TARGET_PRINT_OPERAND* hooks are part of the asm_out struct,
505 even though that is not reflected in the macro name to override their
508 #define HOOK_PREFIX "TARGET_"
510 /* Emit a machine-specific insn operand. */
511 /* ??? tm.texi only documents the old macro PRINT_OPERAND,
512 not this hook, and uses a different name for the argument FILE. */
516 void, (FILE *file, rtx x, int code),
517 default_print_operand)
519 /* Emit a machine-specific memory address. */
520 /* ??? tm.texi only documents the old macro PRINT_OPERAND_ADDRESS,
521 not this hook, and uses different argument names. */
523 (print_operand_address,
525 void, (FILE *file, rtx addr),
526 default_print_operand_address)
528 /* Determine whether CODE is a valid punctuation character for the
529 `print_operand' hook. */
530 /* ??? tm.texi only documents the old macro PRINT_OPERAND_PUNCT_VALID_P,
533 (print_operand_punct_valid_p,
535 bool ,(unsigned char code),
536 default_print_operand_punct_valid_p)
538 /* Given a symbol name, perform same mangling as assemble_name and
539 ASM_OUTPUT_LABELREF, returning result as an IDENTIFIER_NODE. */
541 (mangle_assembler_name,
542 "Given a symbol @var{name}, perform same mangling as @code{varasm.c}'s\
543 @code{assemble_name}, but in memory rather than to a file stream, returning\
544 result as an @code{IDENTIFIER_NODE}. Required for correct LTO symtabs. The\
545 default implementation calls the @code{TARGET_STRIP_NAME_ENCODING} hook and\
546 then prepends the @code{USER_LABEL_PREFIX}, if any.",
547 tree, (const char *name),
548 default_mangle_assembler_name)
550 HOOK_VECTOR_END (asm_out)
552 /* Functions relating to instruction scheduling. All of these
553 default to null pointers, which haifa-sched.c looks for and handles. */
555 #define HOOK_PREFIX "TARGET_SCHED_"
556 HOOK_VECTOR (TARGET_SCHED, sched)
558 /* Given the current cost, COST, of an insn, INSN, calculate and
559 return a new cost based on its relationship to DEP_INSN through
560 the dependence LINK. The default is to make no adjustment. */
564 int, (rtx insn, rtx link, rtx dep_insn, int cost), NULL)
566 /* Adjust the priority of an insn as you see fit. Returns the new priority. */
570 int, (rtx insn, int priority), NULL)
572 /* Function which returns the maximum number of insns that can be
573 scheduled in the same machine cycle. This must be constant
574 over an entire compilation. The default is 1. */
580 /* Calculate how much this insn affects how many more insns we
581 can emit this cycle. Default is they all cost the same. */
585 int, (FILE *file, int verbose, rtx insn, int more), NULL)
587 /* Initialize machine-dependent scheduling code. */
591 void, (FILE *file, int verbose, int max_ready), NULL)
593 /* Finalize machine-dependent scheduling code. */
597 void, (FILE *file, int verbose), NULL)
599 /* Initialize machine-dependent function wide scheduling code. */
603 void, (FILE *file, int verbose, int old_max_uid), NULL)
605 /* Finalize machine-dependent function wide scheduling code. */
609 void, (FILE *file, int verbose), NULL)
611 /* Reorder insns in a machine-dependent fashion, in two different
612 places. Default does nothing. */
616 int, (FILE *file, int verbose, rtx *ready, int *n_readyp, int clock), NULL)
621 int, (FILE *file, int verbose, rtx *ready, int *n_readyp, int clock), NULL)
623 /* The following member value is a pointer to a function called
624 after evaluation forward dependencies of insns in chain given
625 by two parameter values (head and tail correspondingly). */
627 (dependencies_evaluation_hook,
629 void, (rtx head, rtx tail), NULL)
631 /* The values of the following four members are pointers to functions
632 used to simplify the automaton descriptions. dfa_pre_cycle_insn and
633 dfa_post_cycle_insn give functions returning insns which are used to
634 change the pipeline hazard recognizer state when the new simulated
635 processor cycle correspondingly starts and finishes. The function
636 defined by init_dfa_pre_cycle_insn and init_dfa_post_cycle_insn are
637 used to initialize the corresponding insns. The default values of
638 the members result in not changing the automaton state when the
639 new simulated processor cycle correspondingly starts and finishes. */
642 (init_dfa_pre_cycle_insn,
652 (init_dfa_post_cycle_insn,
657 (dfa_post_cycle_insn,
661 /* The values of the following two members are pointers to
662 functions used to simplify the automaton descriptions.
663 dfa_pre_advance_cycle and dfa_post_advance_cycle are getting called
664 immediately before and after cycle is advanced. */
667 (dfa_pre_advance_cycle,
672 (dfa_post_advance_cycle,
676 /* The following member value is a pointer to a function returning value
677 which defines how many insns in queue `ready' will we try for
678 multi-pass scheduling. If the member value is nonzero and the
679 function returns positive value, the DFA based scheduler will make
680 multi-pass scheduling for the first cycle. In other words, we will
681 try to choose ready insn which permits to start maximum number of
682 insns on the same cycle. */
684 (first_cycle_multipass_dfa_lookahead,
688 /* The following member value is pointer to a function controlling
689 what insns from the ready insn queue will be considered for the
690 multipass insn scheduling. If the hook returns zero for insn
691 passed as the parameter, the insn will be not chosen to be issued. */
693 (first_cycle_multipass_dfa_lookahead_guard,
695 int, (rtx insn), NULL)
697 /* This hook prepares the target for a new round of multipass
699 DATA is a pointer to target-specific data used for multipass scheduling.
700 READY_TRY and N_READY represent the current state of search in the
701 optimization space. The target can filter out instructions that
702 should not be tried during current round by setting corresponding
703 elements in READY_TRY to non-zero.
704 FIRST_CYCLE_INSN_P is true if this is the first round of multipass
705 scheduling on current cycle. */
707 (first_cycle_multipass_begin,
709 void, (void *data, char *ready_try, int n_ready, bool first_cycle_insn_p),
712 /* This hook is called when multipass scheduling evaluates instruction INSN.
713 DATA is a pointer to target-specific data that can be used to record effects
714 of INSN on CPU that are not described in DFA.
715 READY_TRY and N_READY represent the current state of search in the
716 optimization space. The target can filter out instructions that
717 should not be tried after issueing INSN by setting corresponding
718 elements in READY_TRY to non-zero.
719 INSN is the instruction being evaluated.
720 PREV_DATA is a pointer to target-specific data corresponding
721 to a state before issueing INSN. */
723 (first_cycle_multipass_issue,
725 void, (void *data, char *ready_try, int n_ready, rtx insn,
726 const void *prev_data), NULL)
728 /* This hook is called when multipass scheduling backtracks from evaluation of
729 instruction corresponding to DATA.
730 DATA is a pointer to target-specific data that stores the effects
731 of instruction from which the algorithm backtracks on CPU that are not
733 READY_TRY and N_READY represent the current state of search in the
734 optimization space. The target can filter out instructions that
735 should not be tried after issueing INSN by setting corresponding
736 elements in READY_TRY to non-zero. */
738 (first_cycle_multipass_backtrack,
740 void, (const void *data, char *ready_try, int n_ready), NULL)
742 /* This hook notifies the target about the result of the concluded current
743 round of multipass scheduling.
745 If DATA is non-NULL it points to target-specific data used for multipass
746 scheduling which corresponds to instruction at the start of the chain of
747 the winning solution. DATA is NULL when multipass scheduling cannot find
748 a good enough solution on current cycle and decides to retry later,
749 usually after advancing the cycle count. */
751 (first_cycle_multipass_end,
753 void, (const void *data), NULL)
755 /* This hook is called to initialize target-specific data for multipass
756 scheduling after it has been allocated.
757 DATA is a pointer to target-specific data that stores the effects
758 of instruction from which the algorithm backtracks on CPU that are not
761 (first_cycle_multipass_init,
763 void, (void *data), NULL)
765 /* This hook is called to finalize target-specific data for multipass
766 scheduling before it is deallocated.
767 DATA is a pointer to target-specific data that stores the effects
768 of instruction from which the algorithm backtracks on CPU that are not
771 (first_cycle_multipass_fini,
773 void, (void *data), NULL)
775 /* The following member value is pointer to a function called by
776 the insn scheduler before issuing insn passed as the third
777 parameter on given cycle. If the hook returns nonzero, the
778 insn is not issued on given processors cycle. Instead of that,
779 the processor cycle is advanced. If the value passed through
780 the last parameter is zero, the insn ready queue is not sorted
781 on the new cycle start as usually. The first parameter passes
782 file for debugging output. The second one passes the scheduler
783 verbose level of the debugging output. The forth and the fifth
784 parameter values are correspondingly processor cycle on which
785 the previous insn has been issued and the current processor cycle. */
789 int, (FILE *dump, int verbose, rtx insn, int last_clock,
790 int clock, int *sort_p),
793 /* The following member value is a pointer to a function called by the
794 insn scheduler. It should return true if there exists a dependence
795 which is considered costly by the target, between the insn
796 DEP_PRO (&_DEP), and the insn DEP_CON (&_DEP). The first parameter is
797 the dep that represents the dependence between the two insns. The
798 second argument is the cost of the dependence as estimated by
799 the scheduler. The last argument is the distance in cycles
800 between the already scheduled insn (first parameter) and the
801 second insn (second parameter). */
803 (is_costly_dependence,
805 bool, (struct _dep *_dep, int cost, int distance), NULL)
809 "Given the current cost, @var{cost}, of an insn, @var{insn}, calculate and\
810 return a new cost based on its relationship to @var{dep_insn} through the\
811 dependence of weakness @var{dw}. The default is to make no adjustment.",
812 int, (rtx insn, int dep_type1, rtx dep_insn, int cost, int dw), NULL)
814 /* The following member value is a pointer to a function called
815 by the insn scheduler. This hook is called to notify the backend
816 that new instructions were emitted. */
822 /* Next 5 functions are for multi-point scheduling. */
824 /* Allocate memory for scheduler context. */
826 (alloc_sched_context,
828 void *, (void), NULL)
830 /* Fills the context from the local machine scheduler context. */
834 void, (void *tc, bool clean_p), NULL)
836 /* Sets local machine scheduler context to a saved value. */
840 void, (void *tc), NULL)
842 /* Clears a scheduler context so it becomes like after init. */
844 (clear_sched_context,
846 void, (void *tc), NULL)
848 /* Frees the scheduler context. */
852 void, (void *tc), NULL)
854 /* The following member value is a pointer to a function called
855 by the insn scheduler.
856 The first parameter is an instruction, the second parameter is the type
857 of the requested speculation, and the third parameter is a pointer to the
858 speculative pattern of the corresponding type (set if return value == 1).
860 -1, if there is no pattern, that will satisfy the requested speculation type,
861 0, if current pattern satisfies the requested speculation type,
862 1, if pattern of the instruction should be changed to the newly
867 int, (rtx insn, int request, rtx *new_pat), NULL)
869 /* The following member value is a pointer to a function called
870 by the insn scheduler. It should return true if the check instruction
871 passed as the parameter needs a recovery block. */
875 bool, (int dep_status), NULL)
877 /* The following member value is a pointer to a function called
878 by the insn scheduler. It should return a pattern for the check
880 The first parameter is a speculative instruction, the second parameter
881 is the label of the corresponding recovery block (or null, if it is a
882 simple check). If the mutation of the check is requested (e.g. from
883 ld.c to chk.a), the third parameter is true - in this case the first
884 parameter is the previous check. */
888 rtx, (rtx insn, rtx label, int mutate_p), NULL)
890 /* The following member value is a pointer to a function controlling
891 what insns from the ready insn queue will be considered for the
892 multipass insn scheduling. If the hook returns zero for the insn
893 passed as the parameter, the insn will not be chosen to be
894 issued. This hook is used to discard speculative instructions,
895 that stand at the first position of the ready list. */
897 (first_cycle_multipass_dfa_lookahead_guard_spec,
899 bool, (const_rtx insn), NULL)
901 /* The following member value is a pointer to a function that provides
902 information about the speculation capabilities of the target.
903 The parameter is a pointer to spec_info variable. */
907 void, (struct spec_info_def *spec_info), NULL)
911 "Return speculation types of instruction @var{insn}.",
912 int, (rtx insn), NULL)
915 (get_insn_checked_ds,
916 "Return speculation types that are checked for instruction @var{insn}",
917 int, (rtx insn), NULL)
921 "Return bool if rtx scanning should just skip current layer and\
922 advance to the inner rtxes.",
923 bool, (const_rtx x), NULL)
925 /* The following member value is a pointer to a function that provides
926 information about the target resource-based lower bound which is
927 used by the swing modulo scheduler. The parameter is a pointer
932 int, (struct ddg *g), NULL)
934 /* The following member value is a function that initializes dispatch
935 schedling and adds instructions to dispatch window according to its
940 void, (rtx insn, int x),
943 /* The following member value is a a function that returns true is
944 dispatch schedling is supported in hardware and condition passed
945 as the second parameter is true. */
949 bool, (rtx insn, int x),
950 hook_bool_rtx_int_false)
952 HOOK_VECTOR_END (sched)
954 /* Functions relating to vectorization. */
956 #define HOOK_PREFIX "TARGET_VECTORIZE_"
957 HOOK_VECTOR (TARGET_VECTORIZE, vectorize)
959 /* The following member value is a pointer to a function called
960 by the vectorizer, and return the decl of the target builtin
963 (builtin_mask_for_load,
967 /* Returns a code for builtin that realizes vectorized version of
968 function, or NULL_TREE if not available. */
970 (builtin_vectorized_function,
972 tree, (tree fndecl, tree vec_type_out, tree vec_type_in),
973 default_builtin_vectorized_function)
975 /* Returns a function declaration for a builtin that realizes the
976 vector conversion, or NULL_TREE if not available. */
980 tree, (unsigned code, tree dest_type, tree src_type),
981 default_builtin_vectorized_conversion)
983 /* Target builtin that implements vector widening multiplication.
984 builtin_mul_widen_eve computes the element-by-element products
985 for the even elements, and builtin_mul_widen_odd computes the
986 element-by-element products for the odd elements. */
988 (builtin_mul_widen_even,
990 tree, (tree x), NULL)
993 (builtin_mul_widen_odd,
995 tree, (tree x), NULL)
997 /* Cost of different vector/scalar statements in vectorization cost
998 model. In case of misaligned vector loads and stores the cost depends
999 on the data type and misalignment value. */
1001 (builtin_vectorization_cost,
1003 int, (enum vect_cost_for_stmt type_of_cost, tree vectype, int misalign),
1004 default_builtin_vectorization_cost)
1006 /* Return true if vector alignment is reachable (by peeling N
1007 iterations) for the given type. */
1009 (vector_alignment_reachable,
1011 bool, (const_tree type, bool is_packed),
1012 default_builtin_vector_alignment_reachable)
1014 /* Target builtin that implements vector permute. */
1018 tree, (tree type, tree *mask_element_type), NULL)
1020 /* Return true if a vector created for builtin_vec_perm is valid. */
1022 (builtin_vec_perm_ok,
1024 bool, (tree vec_type, tree mask),
1025 hook_bool_tree_tree_true)
1027 /* Return true if the target supports misaligned store/load of a
1028 specific factor denoted in the third parameter. The last parameter
1029 is true if the access is defined in a packed struct. */
1031 (support_vector_misalignment,
1034 (enum machine_mode mode, const_tree type, int misalignment, bool is_packed),
1035 default_builtin_support_vector_misalignment)
1037 /* Returns the preferred mode for SIMD operations for the specified
1040 (preferred_simd_mode,
1043 (enum machine_mode mode),
1044 default_preferred_simd_mode)
1046 /* Returns a mask of vector sizes to iterate over when auto-vectorizing
1047 after processing the preferred one derived from preferred_simd_mode. */
1049 (autovectorize_vector_sizes,
1053 default_autovectorize_vector_sizes)
1055 HOOK_VECTOR_END (vectorize)
1058 #define HOOK_PREFIX "TARGET_"
1060 /* The initial value of target_flags. */
1062 (default_target_flags,
1066 /* Allow target specific overriding of option settings after options have
1067 been changed by an attribute or pragma or when it is reset at the
1068 end of the code affected by an attribute or pragma. */
1070 (override_options_after_change,
1075 /* Handle target switch CODE (an OPT_* value). ARG is the argument
1076 passed to the switch; it is NULL if no argument was. VALUE is the
1077 value of ARG if CODE specifies a UInteger option, otherwise it is
1078 1 if the positive form of the switch was used and 0 if the negative
1079 form was. Return true if the switch was valid. */
1083 bool, (size_t code, const char *arg, int value),
1084 hook_bool_size_t_constcharptr_int_true)
1086 /* Display extra, target specific information in response to a
1087 --target-help switch. */
1094 (eh_return_filter_mode,
1095 "Return machine mode for filter value.",
1096 enum machine_mode, (void),
1097 default_eh_return_filter_mode)
1099 /* Return machine mode for libgcc expanded cmp instructions. */
1101 (libgcc_cmp_return_mode,
1103 enum machine_mode, (void),
1104 default_libgcc_cmp_return_mode)
1106 /* Return machine mode for libgcc expanded shift instructions. */
1108 (libgcc_shift_count_mode,
1110 enum machine_mode, (void),
1111 default_libgcc_shift_count_mode)
1113 /* Return machine mode to be used for _Unwind_Word type. */
1117 enum machine_mode, (void),
1118 default_unwind_word_mode)
1120 /* Given two decls, merge their attributes and return the result. */
1122 (merge_decl_attributes,
1124 tree, (tree olddecl, tree newdecl),
1125 merge_decl_attributes)
1127 /* Given two types, merge their attributes and return the result. */
1129 (merge_type_attributes,
1131 tree, (tree type1, tree type2),
1132 merge_type_attributes)
1134 /* Table of machine attributes and functions to handle them.
1139 const struct attribute_spec *, NULL)
1141 /* Return true iff attribute NAME expects a plain identifier as its first
1144 (attribute_takes_identifier_p,
1146 bool, (const_tree name),
1147 hook_bool_const_tree_false)
1149 /* Return zero if the attributes on TYPE1 and TYPE2 are incompatible,
1150 one if they are compatible and two if they are nearly compatible
1151 (which causes a warning to be generated). */
1153 (comp_type_attributes,
1155 int, (const_tree type1, const_tree type2),
1156 hook_int_const_tree_const_tree_1)
1158 /* Assign default attributes to the newly defined TYPE. */
1160 (set_default_type_attributes,
1165 /* Insert attributes on the newly created DECL. */
1169 void, (tree node, tree *attr_ptr),
1170 hook_void_tree_treeptr)
1172 /* Return true if FNDECL (which has at least one machine attribute)
1173 can be inlined despite its machine attributes, false otherwise. */
1175 (function_attribute_inlinable_p,
1177 bool, (const_tree fndecl),
1178 hook_bool_const_tree_false)
1180 /* Return true if bitfields in RECORD_TYPE should follow the
1181 Microsoft Visual C++ bitfield layout rules. */
1183 (ms_bitfield_layout_p,
1185 bool, (const_tree record_type),
1186 hook_bool_const_tree_false)
1188 /* For now this is only an interface to WORDS_BIG_ENDIAN for
1189 target-independent code like the front ends, need performance testing
1190 before switching completely to the target hook. */
1195 targhook_words_big_endian)
1197 /* Likewise for FLOAT_WORDS_BIG_ENDIAN. */
1199 (float_words_big_endian,
1202 targhook_float_words_big_endian)
1204 /* True if the target supports decimal floating point. */
1206 (decimal_float_supported_p,
1209 default_decimal_float_supported_p)
1211 /* True if the target supports fixed-point. */
1213 (fixed_point_supported_p,
1216 default_fixed_point_supported_p)
1218 /* Return true if anonymous bitfields affect structure alignment. */
1220 (align_anon_bitfield,
1223 hook_bool_void_false)
1225 /* Return true if volatile bitfields should use the narrowest type possible.
1226 Return false if they should use the container type. */
1228 (narrow_volatile_bitfield,
1231 hook_bool_void_false)
1233 /* Set up target-specific built-in functions. */
1240 /* Initialize (if INITIALIZE_P is true) and return the target-specific
1241 built-in function decl for CODE.
1242 Return NULL if that is not possible. Return error_mark_node if CODE
1243 is outside of the range of valid target builtin function codes. */
1247 tree, (unsigned code, bool initialize_p), NULL)
1249 /* Expand a target-specific builtin. */
1254 (tree exp, rtx target, rtx subtarget, enum machine_mode mode, int ignore),
1255 default_expand_builtin)
1257 /* Select a replacement for a target-specific builtin. This is done
1258 *before* regular type checking, and so allows the target to
1259 implement a crude form of function overloading. The result is a
1260 complete expression that implements the operation. PARAMS really
1261 has type VEC(tree,gc)*, but we don't want to include tree.h here. */
1263 (resolve_overloaded_builtin,
1265 tree, (unsigned int /*location_t*/ loc, tree fndecl, void *arglist), NULL)
1267 /* Fold a target-specific builtin. */
1271 tree, (tree fndecl, int n_args, tree *argp, bool ignore),
1272 hook_tree_tree_int_treep_bool_null)
1274 /* Returns a code for a target-specific builtin that implements
1275 reciprocal of the function, or NULL_TREE if not available. */
1277 (builtin_reciprocal,
1279 tree, (unsigned fn, bool md_fn, bool sqrt),
1280 default_builtin_reciprocal)
1282 /* For a vendor-specific TYPE, return a pointer to a statically-allocated
1283 string containing the C++ mangling for TYPE. In all other cases, return
1288 const char *, (const_tree type),
1289 hook_constcharptr_const_tree_null)
1291 /* Make any adjustments to libfunc names needed for this target. */
1298 /* Given a decl, a section name, and whether the decl initializer
1299 has relocs, choose attributes for the section. */
1300 /* ??? Should be merged with SELECT_SECTION and UNIQUE_SECTION. */
1302 (section_type_flags,
1304 unsigned int, (tree decl, const char *name, int reloc),
1305 default_section_type_flags)
1307 /* True if new jumps cannot be created, to replace existing ones or
1308 not, at the current point in the compilation. */
1310 (cannot_modify_jumps_p,
1313 hook_bool_void_false)
1315 /* Return a register class for which branch target register
1316 optimizations should be applied. */
1318 (branch_target_register_class,
1320 reg_class_t, (void),
1321 default_branch_target_register_class)
1323 /* Return true if branch target register optimizations should include
1324 callee-saved registers that are not already live during the current
1325 function. AFTER_PE_GEN is true if prologues and epilogues have
1326 already been generated. */
1328 (branch_target_register_callee_saved,
1330 bool, (bool after_prologue_epilogue_gen),
1331 hook_bool_bool_false)
1333 /* Return true if the target supports conditional execution. */
1335 (have_conditional_execution,
1338 default_have_conditional_execution)
1340 /* Return a new value for loop unroll size. */
1342 (loop_unroll_adjust,
1344 unsigned, (unsigned nunroll, struct loop *loop),
1347 /* True if the constant X cannot be placed in the constant pool. */
1349 (cannot_force_const_mem,
1352 hook_bool_rtx_false)
1355 (cannot_copy_insn_p,
1356 "True if the insn @var{x} cannot be duplicated.",
1359 /* True if X is considered to be commutative. */
1363 bool, (const_rtx x, int outer_code),
1364 hook_bool_const_rtx_commutative_p)
1366 /* True if ADDR is an address-expression whose effect depends
1367 on the mode of the memory reference it is used in. */
1369 (mode_dependent_address_p,
1371 bool, (const_rtx addr),
1372 default_mode_dependent_address_p)
1374 /* Given an invalid address X for a given machine mode, try machine-specific
1375 ways to make it legitimate. Return X or an invalid address on failure. */
1377 (legitimize_address,
1379 rtx, (rtx x, rtx oldx, enum machine_mode mode),
1380 default_legitimize_address)
1382 /* Given an address RTX, undo the effects of LEGITIMIZE_ADDRESS. */
1384 (delegitimize_address,
1387 delegitimize_mem_from_attrs)
1389 /* Given an address RTX, say whether it is valid. */
1391 (legitimate_address_p,
1393 bool, (enum machine_mode mode, rtx x, bool strict),
1394 default_legitimate_address_p)
1396 /* True if the given constant can be put into an object_block. */
1398 (use_blocks_for_constant_p,
1400 bool, (enum machine_mode mode, const_rtx x),
1401 hook_bool_mode_const_rtx_false)
1403 /* The minimum and maximum byte offsets for anchored addresses. */
1414 /* True if section anchors can be used to access the given symbol. */
1416 (use_anchors_for_symbol_p,
1418 bool, (const_rtx x),
1419 default_use_anchors_for_symbol_p)
1421 /* True if it is OK to do sibling call optimization for the specified
1422 call expression EXP. DECL will be the called function, or NULL if
1423 this is an indirect call. */
1425 (function_ok_for_sibcall,
1427 bool, (tree decl, tree exp),
1428 hook_bool_tree_tree_false)
1430 /* Establish appropriate back-end context for processing the function
1431 FNDECL. The argument might be NULL to indicate processing at top
1432 level, outside of any function scope. */
1434 (set_current_function,
1436 void, (tree decl), hook_void_tree)
1438 /* True if EXP should be placed in a "small data" section. */
1442 bool, (const_tree exp),
1443 hook_bool_const_tree_false)
1445 /* True if EXP names an object for which name resolution must resolve
1446 to the current executable or shared library. */
1450 bool, (const_tree exp),
1451 default_binds_local_p)
1453 /* Check if profiling code is before or after prologue. */
1455 (profile_before_prologue,
1456 "It returns true if target wants profile code emitted before prologue.\n\n\
1457 The default version of this hook use the target macro\n\
1458 @code{PROFILE_BEFORE_PROLOGUE}.",
1460 default_profile_before_prologue)
1462 /* Modify and return the identifier of a DECL's external name,
1463 originally identified by ID, as required by the target,
1464 (eg, append @nn to windows32 stdcall function names).
1465 The default is to return ID without modification. */
1467 (mangle_decl_assembler_name,
1469 tree, (tree decl, tree id),
1470 default_mangle_decl_assembler_name)
1472 /* Do something target-specific to record properties of the DECL into
1473 the associated SYMBOL_REF. */
1475 (encode_section_info,
1477 void, (tree decl, rtx rtl, int new_decl_p),
1478 default_encode_section_info)
1480 /* Undo the effects of encode_section_info on the symbol string. */
1482 (strip_name_encoding,
1484 const char *, (const char *name),
1485 default_strip_name_encoding)
1487 /* If shift optabs for MODE are known to always truncate the shift count,
1488 return the mask that they apply. Return 0 otherwise. */
1490 (shift_truncation_mask,
1492 unsigned HOST_WIDE_INT, (enum machine_mode mode),
1493 default_shift_truncation_mask)
1495 /* Return the number of divisions in the given MODE that should be present,
1496 so that it is profitable to turn the division into a multiplication by
1499 (min_divisions_for_recip_mul,
1501 unsigned int, (enum machine_mode mode),
1502 default_min_divisions_for_recip_mul)
1504 /* If the representation of integral MODE is such that values are
1505 always sign-extended to a wider mode MODE_REP then return
1506 SIGN_EXTEND. Return UNKNOWN otherwise. */
1507 /* Note that the return type ought to be RTX_CODE, but that's not
1508 necessarily defined at this point. */
1512 int, (enum machine_mode mode, enum machine_mode rep_mode),
1513 default_mode_rep_extended)
1515 /* True if MODE is valid for a pointer in __attribute__((mode("MODE"))). */
1517 (valid_pointer_mode,
1519 bool, (enum machine_mode mode),
1520 default_valid_pointer_mode)
1522 /* Disambiguate with errno. */
1524 (ref_may_alias_errno,
1525 "Define this to return nonzero if the memory reference @var{ref}\
1526 may alias with the system C library errno location. The default\
1527 version of this hook assumes the system C library errno location\
1528 is either a declaration of type int or accessed by dereferencing\
1530 bool, (struct ao_ref_s *ref),
1531 default_ref_may_alias_errno)
1533 /* Support for named address spaces. */
1535 #define HOOK_PREFIX "TARGET_ADDR_SPACE_"
1536 HOOK_VECTOR (TARGET_ADDR_SPACE_HOOKS, addr_space)
1538 /* MODE to use for a pointer into another address space. */
1542 enum machine_mode, (addr_space_t address_space),
1543 default_addr_space_pointer_mode)
1545 /* MODE to use for an address in another address space. */
1549 enum machine_mode, (addr_space_t address_space),
1550 default_addr_space_address_mode)
1552 /* True if MODE is valid for a pointer in __attribute__((mode("MODE")))
1553 in another address space. */
1555 (valid_pointer_mode,
1557 bool, (enum machine_mode mode, addr_space_t as),
1558 default_addr_space_valid_pointer_mode)
1560 /* True if an address is a valid memory address to a given named address
1561 space for a given mode. */
1563 (legitimate_address_p,
1565 bool, (enum machine_mode mode, rtx exp, bool strict, addr_space_t as),
1566 default_addr_space_legitimate_address_p)
1568 /* Return an updated address to convert an invalid pointer to a named
1569 address space to a valid one. If NULL_RTX is returned use machine
1570 independent methods to make the address valid. */
1572 (legitimize_address,
1574 rtx, (rtx x, rtx oldx, enum machine_mode mode, addr_space_t as),
1575 default_addr_space_legitimize_address)
1577 /* True if one named address space is a subset of another named address. */
1581 bool, (addr_space_t superset, addr_space_t subset),
1582 default_addr_space_subset_p)
1584 /* Function to convert an rtl expression from one address space to another. */
1588 rtx, (rtx op, tree from_type, tree to_type),
1589 default_addr_space_convert)
1591 HOOK_VECTOR_END (addr_space)
1594 #define HOOK_PREFIX "TARGET_"
1596 /* True if MODE is valid for the target. By "valid", we mean able to
1597 be manipulated in non-trivial ways. In particular, this means all
1598 the arithmetic is supported. */
1600 (scalar_mode_supported_p,
1602 bool, (enum machine_mode mode),
1603 default_scalar_mode_supported_p)
1605 /* Similarly for vector modes. "Supported" here is less strict. At
1606 least some operations are supported; need to check optabs or builtins
1607 for further details. */
1609 (vector_mode_supported_p,
1611 bool, (enum machine_mode mode),
1612 hook_bool_mode_false)
1614 /* Compute cost of moving data from a register of class FROM to one of
1617 (register_move_cost,
1619 int, (enum machine_mode mode, reg_class_t from, reg_class_t to),
1620 default_register_move_cost)
1622 /* Compute cost of moving registers to/from memory. */
1623 /* ??? Documenting the argument types for this hook requires a GFDL
1624 license grant. Also, the documentation uses a different name for RCLASS. */
1628 int, (enum machine_mode mode, reg_class_t rclass, bool in),
1629 default_memory_move_cost)
1631 /* True for MODE if the target expects that registers in this mode will
1632 be allocated to registers in a small register class. The compiler is
1633 allowed to use registers explicitly used in the rtl as spill registers
1634 but it should prevent extending the lifetime of these registers. */
1636 (small_register_classes_for_mode_p,
1638 bool, (enum machine_mode mode),
1639 hook_bool_mode_false)
1641 /* Register number for a flags register. Only needs to be defined if the
1642 target is constrainted to use post-reload comparison elimination. */
1645 "If the target has a dedicated flags register, and it needs to use the\
1646 post-reload comparison elimination pass, then this value should be set\
1648 unsigned int, INVALID_REGNUM)
1650 /* Compute a (partial) cost for rtx X. Return true if the complete
1651 cost has been computed, and false if subexpressions should be
1652 scanned. In either case, *TOTAL contains the cost result. */
1653 /* Note that CODE and OUTER_CODE ought to be RTX_CODE, but that's
1654 not necessarily defined at this point. */
1658 bool, (rtx x, int code, int outer_code, int *total, bool speed),
1659 hook_bool_rtx_int_int_intp_bool_false)
1661 /* Compute the cost of X, used as an address. Never called with
1662 invalid addresses. */
1666 int, (rtx address, bool speed),
1667 default_address_cost)
1669 /* Return where to allocate pseudo for a given hard register initial value. */
1671 (allocate_initial_value,
1673 rtx, (rtx hard_reg), NULL)
1675 /* Return nonzero if evaluating UNSPEC[_VOLATILE] X might cause a trap.
1676 FLAGS has the same meaning as in rtlanal.c: may_trap_p_1. */
1680 int, (const_rtx x, unsigned flags),
1681 default_unspec_may_trap_p)
1683 /* Given a register, this hook should return a parallel of registers
1684 to represent where to find the register pieces. Define this hook
1685 if the register and its mode are represented in Dwarf in
1686 non-contiguous locations, or if the register should be
1687 represented in more than one register in Dwarf. Otherwise, this
1688 hook should return NULL_RTX. */
1690 (dwarf_register_span,
1695 /* If expand_builtin_init_dwarf_reg_sizes needs to fill in table
1696 entries not corresponding directly to registers below
1697 FIRST_PSEUDO_REGISTER, this hook should generate the necessary
1698 code, given the address of the table. */
1700 (init_dwarf_reg_sizes_extra,
1702 void, (tree address),
1705 /* Fetch the fixed register(s) which hold condition codes, for
1706 targets where it makes sense to look for duplicate assignments to
1707 the condition codes. This should return true if there is such a
1708 register, false otherwise. The arguments should be set to the
1709 fixed register numbers. Up to two condition code registers are
1710 supported. If there is only one for this target, the int pointed
1711 at by the second argument should be set to -1. */
1713 (fixed_condition_code_regs,
1715 bool, (unsigned int *p1, unsigned int *p2),
1716 hook_bool_uintp_uintp_false)
1718 /* If two condition code modes are compatible, return a condition
1719 code mode which is compatible with both, such that a comparison
1720 done in the returned mode will work for both of the original
1721 modes. If the condition code modes are not compatible, return
1724 (cc_modes_compatible,
1726 enum machine_mode, (enum machine_mode m1, enum machine_mode m2),
1727 default_cc_modes_compatible)
1729 /* Do machine-dependent code transformations. Called just before
1730 delayed-branch scheduling. */
1732 (machine_dependent_reorg,
1736 /* Create the __builtin_va_list type. */
1738 (build_builtin_va_list,
1741 std_build_builtin_va_list)
1743 /* Enumerate the va list variants. */
1747 int, (int idx, const char **pname, tree *ptree),
1750 /* Get the cfun/fndecl calling abi __builtin_va_list type. */
1754 tree, (tree fndecl),
1757 /* Get the __builtin_va_list type dependent on input type. */
1759 (canonical_va_list_type,
1762 std_canonical_va_list_type)
1764 /* ??? Documenting this hook requires a GFDL license grant. */
1766 (expand_builtin_va_start,
1767 "Expand the @code{__builtin_va_start} builtin.",
1768 void, (tree valist, rtx nextarg), NULL)
1770 /* Gimplifies a VA_ARG_EXPR. */
1772 (gimplify_va_arg_expr,
1774 tree, (tree valist, tree type, gimple_seq *pre_p, gimple_seq *post_p),
1775 std_gimplify_va_arg_expr)
1777 /* Validity-checking routines for PCH files, target-specific.
1778 get_pch_validity returns a pointer to the data to be stored,
1779 and stores the size in its argument. pch_valid_p gets the same
1780 information back and returns NULL if the PCH is valid,
1781 or an error message if not. */
1785 void *, (size_t *sz),
1786 default_get_pch_validity)
1791 const char *, (const void *data, size_t sz),
1792 default_pch_valid_p)
1794 /* If nonnull, this function checks whether a PCH file with the
1795 given set of target flags can be used. It returns NULL if so,
1796 otherwise it returns an error message. */
1798 (check_pch_target_flags,
1800 const char *, (int pch_flags), NULL)
1802 /* True if the compiler should give an enum type only as many
1803 bytes as it takes to represent the range of possible values of
1806 (default_short_enums,
1809 hook_bool_void_false)
1811 /* This target hook returns an rtx that is used to store the address
1812 of the current frame into the built-in setjmp buffer. */
1814 (builtin_setjmp_frame_value,
1817 default_builtin_setjmp_frame_value)
1819 /* This target hook should add STRING_CST trees for any hard regs
1820 the port wishes to automatically clobber for an asm. */
1824 tree, (tree outputs, tree inputs, tree clobbers),
1825 hook_tree_tree_tree_tree_3rd_identity)
1827 /* This target hook allows the backend to specify a calling convention
1828 in the debug information. This function actually returns an
1829 enum dwarf_calling_convention, but because of forward declarations
1830 and not wanting to include dwarf2.h everywhere target.h is included
1831 the function is being declared as an int. */
1833 (dwarf_calling_convention,
1835 int, (const_tree function),
1836 hook_int_const_tree_0)
1838 /* This target hook allows the backend to emit frame-related insns that
1839 contain UNSPECs or UNSPEC_VOLATILEs. The call frame debugging info
1840 engine will invoke it on insns of the form
1841 (set (reg) (unspec [...] UNSPEC_INDEX))
1843 (set (reg) (unspec_volatile [...] UNSPECV_INDEX))
1844 to let the backend emit the call frame instructions. */
1846 (dwarf_handle_frame_unspec,
1848 void, (const char *label, rtx pattern, int index), NULL)
1850 /* ??? Documenting this hook requires a GFDL license grant. */
1852 (stdarg_optimize_hook,
1853 "Perform architecture specific checking of statements gimplified\
1854 from @code{VA_ARG_EXPR}. @var{stmt} is the statement. Returns true if\
1855 the statement doesn't need to be checked for @code{va_list} references.",
1856 bool, (struct stdarg_info *ai, const_gimple stmt), NULL)
1858 /* This target hook allows the operating system to override the DECL
1859 that represents the external variable that contains the stack
1860 protection guard variable. The type of this DECL is ptr_type_node. */
1862 (stack_protect_guard,
1865 default_stack_protect_guard)
1867 /* This target hook allows the operating system to override the CALL_EXPR
1868 that is invoked when a check vs the guard variable fails. */
1870 (stack_protect_fail,
1873 default_external_stack_protect_fail)
1876 (supports_split_stack,
1877 "Whether this target supports splitting the stack when the options\
1878 described in @var{opts} have been passed. This is called\
1879 after options have been parsed, so the target may reject splitting\
1880 the stack in some configurations. The default version of this hook\
1881 returns false. If @var{report} is true, this function may issue a warning\
1882 or error; if @var{report} is false, it must simply return a value",
1883 bool, (bool report, struct gcc_options *opts),
1884 hook_bool_bool_gcc_optionsp_false)
1886 /* Returns NULL if target supports the insn within a doloop block,
1887 otherwise it returns an error message. */
1889 (invalid_within_doloop,
1891 const char *, (const_rtx insn),
1892 default_invalid_within_doloop)
1895 (valid_dllimport_attribute_p,
1896 "@var{decl} is a variable or function with @code{__attribute__((dllimport))}\
1897 specified. Use this hook if the target needs to add extra validation\
1898 checks to @code{handle_dll_attribute}.",
1899 bool, (const_tree decl),
1900 hook_bool_const_tree_true)
1902 /* If non-zero, align constant anchors in CSE to a multiple of this
1907 unsigned HOST_WIDE_INT, 0)
1909 /* Functions relating to calls - argument passing, returns, etc. */
1910 /* Members of struct call have no special macro prefix. */
1911 HOOK_VECTOR (TARGET_CALLS, calls)
1914 (promote_function_mode,
1916 enum machine_mode, (const_tree type, enum machine_mode mode, int *punsignedp,
1917 const_tree funtype, int for_return),
1918 default_promote_function_mode)
1921 (promote_prototypes,
1923 bool, (const_tree fntype),
1924 hook_bool_const_tree_false)
1929 rtx, (tree fndecl, int incoming),
1930 hook_rtx_tree_int_null)
1934 bool, (const_tree type, const_tree fntype),
1935 default_return_in_memory)
1940 bool, (const_tree type),
1941 hook_bool_const_tree_false)
1943 /* Return true if a parameter must be passed by reference. TYPE may
1944 be null if this is a libcall. CA may be null if this query is
1945 from __builtin_va_arg. */
1950 (CUMULATIVE_ARGS *cum, enum machine_mode mode, const_tree type, bool named),
1951 hook_bool_CUMULATIVE_ARGS_mode_tree_bool_false)
1954 (expand_builtin_saveregs,
1957 default_expand_builtin_saveregs)
1959 /* Returns pretend_argument_size. */
1961 (setup_incoming_varargs,
1963 void, (CUMULATIVE_ARGS *args_so_far, enum machine_mode mode, tree type,
1964 int *pretend_args_size, int second_time),
1965 default_setup_incoming_varargs)
1968 (strict_argument_naming,
1970 bool, (CUMULATIVE_ARGS *ca),
1971 hook_bool_CUMULATIVE_ARGS_false)
1973 /* Returns true if we should use
1974 targetm.calls.setup_incoming_varargs() and/or
1975 targetm.calls.strict_argument_naming(). */
1977 (pretend_outgoing_varargs_named,
1979 bool, (CUMULATIVE_ARGS *ca),
1980 default_pretend_outgoing_varargs_named)
1982 /* Given a complex type T, return true if a parameter of type T
1983 should be passed as two scalars. */
1987 bool, (const_tree type), NULL)
1989 /* Return true if type T, mode MODE, may not be passed in registers,
1990 but must be passed on the stack. */
1991 /* ??? This predicate should be applied strictly after pass-by-reference.
1992 Need audit to verify that this is the case. */
1994 (must_pass_in_stack,
1996 bool, (enum machine_mode mode, const_tree type),
1997 must_pass_in_stack_var_size_or_pad)
1999 /* Return true if type TYPE, mode MODE, which is passed by reference,
2000 should have the object copy generated by the callee rather than
2001 the caller. It is never called for TYPE requiring constructors. */
2006 (CUMULATIVE_ARGS *cum, enum machine_mode mode, const_tree type, bool named),
2007 hook_bool_CUMULATIVE_ARGS_mode_tree_bool_false)
2009 /* Return zero for arguments passed entirely on the stack or entirely
2010 in registers. If passed in both, return the number of bytes passed
2011 in registers; the balance is therefore passed on the stack. */
2015 int, (CUMULATIVE_ARGS *cum, enum machine_mode mode, tree type, bool named),
2016 hook_int_CUMULATIVE_ARGS_mode_tree_bool_0)
2018 /* Update the state in CA to advance past an argument in the
2019 argument list. The values MODE, TYPE, and NAMED describe that
2021 /* ??? tm.texi still only describes the old macro. */
2023 (function_arg_advance,
2026 (CUMULATIVE_ARGS *ca, enum machine_mode mode, const_tree type, bool named),
2027 default_function_arg_advance)
2029 /* Return zero if the argument described by the state of CA should
2030 be placed on a stack, or a hard register in which to store the
2031 argument. The values MODE, TYPE, and NAMED describe that
2033 /* ??? tm.texi still only describes the old macro. */
2037 rtx, (CUMULATIVE_ARGS *ca, enum machine_mode mode, const_tree type,
2039 default_function_arg)
2041 /* Likewise, but for machines with register windows. Return the
2042 location where the argument will appear to the callee. */
2043 /* ??? tm.texi still only describes the old macro. */
2045 (function_incoming_arg,
2047 rtx, (CUMULATIVE_ARGS *ca, enum machine_mode mode, const_tree type,
2049 default_function_incoming_arg)
2052 (function_arg_boundary,
2054 unsigned int, (enum machine_mode mode, const_tree type),
2055 default_function_arg_boundary)
2057 /* Return the diagnostic message string if function without a prototype
2058 is not allowed for this 'val' argument; NULL otherwise. */
2060 (invalid_arg_for_unprototyped_fn,
2062 const char *, (const_tree typelist, const_tree funcdecl, const_tree val),
2063 hook_invalid_arg_for_unprototyped_fn)
2065 /* Return an rtx for the return value location of the function
2066 specified by FN_DECL_OR_TYPE with a return type of RET_TYPE. */
2070 rtx, (const_tree ret_type, const_tree fn_decl_or_type, bool outgoing),
2071 default_function_value)
2073 /* Return the rtx for the result of a libcall of mode MODE,
2074 calling the function FN_NAME. */
2078 rtx, (enum machine_mode mode, const_rtx fun),
2079 default_libcall_value)
2081 /* Return true if REGNO is a possible register number for
2082 a function value as seen by the caller. */
2084 (function_value_regno_p,
2086 bool, (const unsigned int regno),
2087 default_function_value_regno_p)
2089 /* ??? Documenting this hook requires a GFDL license grant. */
2091 (internal_arg_pointer,
2092 "Return an rtx for the argument pointer incoming to the\
2095 default_internal_arg_pointer)
2097 /* Update the current function stack boundary if needed. */
2099 (update_stack_boundary,
2103 /* Handle stack alignment and return an rtx for Dynamic Realign
2104 Argument Pointer if necessary. */
2110 /* Return true if all function parameters should be spilled to the
2113 (allocate_stack_slots_for_args,
2116 hook_bool_void_true)
2118 /* Return an rtx for the static chain for FNDECL. If INCOMING_P is true,
2119 then it should be for the callee; otherwise for the caller. */
2123 rtx, (const_tree fndecl, bool incoming_p),
2124 default_static_chain)
2126 /* Fill in the trampoline at MEM with a call to FNDECL and a
2127 static chain value of CHAIN. */
2131 void, (rtx m_tramp, tree fndecl, rtx static_chain),
2132 default_trampoline_init)
2134 /* Adjust the address of the trampoline in a target-specific way. */
2136 (trampoline_adjust_address,
2138 rtx, (rtx addr), NULL)
2140 /* Return the number of bytes of its own arguments that a function
2141 pops on returning, or 0 if the function pops no arguments and the
2142 caller must therefore pop them all after the function returns. */
2143 /* ??? tm.texi has no types for the parameters. */
2147 int, (tree fundecl, tree funtype, int size),
2148 default_return_pops_args)
2150 /* Return a mode wide enough to copy any function value that might be
2153 (get_raw_result_mode,
2154 "This target hook returns the mode to be used when accessing raw return\
2155 registers in @code{__builtin_return}. Define this macro if the value\
2156 in @var{reg_raw_mode} is not correct.",
2157 enum machine_mode, (int regno),
2158 default_get_reg_raw_mode)
2160 /* Return a mode wide enough to copy any argument value that might be
2164 "This target hook returns the mode to be used when accessing raw argument\
2165 registers in @code{__builtin_apply_args}. Define this macro if the value\
2166 in @var{reg_raw_mode} is not correct.",
2167 enum machine_mode, (int regno),
2168 default_get_reg_raw_mode)
2170 HOOK_VECTOR_END (calls)
2172 /* Return the diagnostic message string if conversion from FROMTYPE
2173 to TOTYPE is not allowed, NULL otherwise. */
2175 (invalid_conversion,
2177 const char *, (const_tree fromtype, const_tree totype),
2178 hook_constcharptr_const_tree_const_tree_null)
2180 /* Return the diagnostic message string if the unary operation OP is
2181 not permitted on TYPE, NULL otherwise. */
2185 const char *, (int op, const_tree type),
2186 hook_constcharptr_int_const_tree_null)
2188 /* Return the diagnostic message string if the binary operation OP
2189 is not permitted on TYPE1 and TYPE2, NULL otherwise. */
2193 const char *, (int op, const_tree type1, const_tree type2),
2194 hook_constcharptr_int_const_tree_const_tree_null)
2196 /* Return the diagnostic message string if TYPE is not valid as a
2197 function parameter type, NULL otherwise. */
2199 (invalid_parameter_type,
2201 const char *, (const_tree type),
2202 hook_constcharptr_const_tree_null)
2204 /* Return the diagnostic message string if TYPE is not valid as a
2205 function return type, NULL otherwise. */
2207 (invalid_return_type,
2209 const char *, (const_tree type),
2210 hook_constcharptr_const_tree_null)
2212 /* If values of TYPE are promoted to some other type when used in
2213 expressions (analogous to the integer promotions), return that type,
2214 or NULL_TREE otherwise. */
2218 tree, (const_tree type),
2219 hook_tree_const_tree_null)
2221 /* Convert EXPR to TYPE, if target-specific types with special conversion
2222 rules are involved. Return the converted expression, or NULL to apply
2223 the standard conversion rules. */
2227 tree, (tree type, tree expr),
2228 hook_tree_tree_tree_null)
2230 /* Return the array of IRA cover classes for the current target. */
2234 const reg_class_t *, (void),
2235 default_ira_cover_classes)
2237 /* Return the class for a secondary reload, and fill in extra information. */
2242 (bool in_p, rtx x, reg_class_t reload_class, enum machine_mode reload_mode,
2243 secondary_reload_info *sri),
2244 default_secondary_reload)
2246 /* Given an rtx X being reloaded into a reg required to be in class CLASS,
2247 return the class of reg to actually use. */
2249 (preferred_reload_class,
2252 (rtx x, reg_class_t rclass),
2253 default_preferred_reload_class)
2255 /* Like TARGET_PREFERRED_RELOAD_CLASS, but for output reloads instead of
2258 (preferred_output_reload_class,
2261 (rtx x, reg_class_t rclass),
2262 default_preferred_output_reload_class)
2265 (class_likely_spilled_p,
2267 bool, (reg_class_t rclass),
2268 default_class_likely_spilled_p)
2271 (preferred_rename_class,
2272 "A target hook that places additional preference on the register\
2273 class to use when it is necessary to rename a register in class\
2274 @var{rclass} to another class, or perhaps @var{NO_REGS}, if no\
2275 preferred register class is found or hook @code{preferred_rename_class}\
2276 is not implemented.\
2277 Sometimes returning a more restrictive class makes better code. For\
2278 example, on ARM, thumb-2 instructions using @code{LO_REGS} may be\
2279 smaller than instructions using @code{GENERIC_REGS}. By returning\
2280 @code{LO_REGS} from @code{preferred_rename_class}, code size can\
2282 reg_class_t, (reg_class_t rclass),
2283 default_preferred_rename_class)
2285 /* This target hook allows the backend to perform additional
2286 processing while initializing for variable expansion. */
2288 (expand_to_rtl_hook,
2293 /* This target hook allows the backend to perform additional
2294 instantiations on rtx that are not actually in insns yet,
2295 but will be later. */
2302 /* Return true if is OK to use a hard register REGNO as scratch register
2305 (hard_regno_scratch_ok,
2307 bool, (unsigned int regno),
2308 default_hard_regno_scratch_ok)
2310 /* Return the smallest number of different values for which it is best to
2311 use a jump-table instead of a tree of conditional branches. */
2313 (case_values_threshold,
2315 unsigned int, (void),
2316 default_case_values_threshold)
2318 /* Retutn true if a function must have and use a frame pointer. */
2320 (frame_pointer_required,
2323 hook_bool_void_false)
2325 /* Returns true if the compiler is allowed to try to replace register number
2326 from-reg with register number to-reg. */
2330 bool, (const int from_reg, const int to_reg),
2331 hook_bool_const_int_const_int_true)
2333 /* Modify any or all of fixed_regs, call_used_regs, global_regs,
2334 reg_names, and reg_class_contents to account of the vagaries of the
2337 (conditional_register_usage,
2342 /* Functions specific to the C family of frontends. */
2344 #define HOOK_PREFIX "TARGET_C_"
2345 HOOK_VECTOR (TARGET_C, c)
2347 /* ??? Documenting this hook requires a GFDL license grant. */
2350 "Return machine mode for non-standard constant literal suffix @var{c},\
2351 or VOIDmode if non-standard suffixes are unsupported.",
2352 enum machine_mode, (char c),
2353 default_mode_for_suffix)
2357 /* Functions specific to the C++ frontend. */
2359 #define HOOK_PREFIX "TARGET_CXX_"
2360 HOOK_VECTOR (TARGET_CXX, cxx)
2362 /* Return the integer type used for guard variables. */
2367 default_cxx_guard_type)
2369 /* Return true if only the low bit of the guard should be tested. */
2374 hook_bool_void_false)
2376 /* Returns the size of the array cookie for an array of type. */
2381 default_cxx_get_cookie_size)
2383 /* Returns true if the element size should be stored in the array cookie. */
2388 hook_bool_void_false)
2390 /* Allows backends to perform additional processing when
2391 deciding if a class should be exported or imported. */
2393 (import_export_class,
2395 int, (tree type, int import_export), NULL)
2397 /* Returns true if constructors and destructors return "this". */
2399 (cdtor_returns_this,
2402 hook_bool_void_false)
2404 /* Returns true if the key method for a class can be an inline
2405 function, so long as it is not declared inline in the class
2406 itself. Returning true is the behavior required by the Itanium C++ ABI. */
2408 (key_method_may_be_inline,
2411 hook_bool_void_true)
2414 (determine_class_data_visibility,
2415 "@var{decl} is a virtual table, virtual table table, typeinfo object,\
2416 or other similar implicit class data object that will be emitted with\
2417 external linkage in this translation unit. No ELF visibility has been\
2418 explicitly specified. If the target needs to specify a visibility\
2419 other than that of the containing class, use this hook to set\
2420 @code{DECL_VISIBILITY} and @code{DECL_VISIBILITY_SPECIFIED}.",
2424 /* Returns true (the default) if virtual tables and other
2425 similar implicit class data objects are always COMDAT if they
2426 have external linkage. If this hook returns false, then
2427 class data for classes whose virtual table will be emitted in
2428 only one translation unit will not be COMDAT. */
2430 (class_data_always_comdat,
2433 hook_bool_void_true)
2435 /* Returns true (the default) if the RTTI for the basic types,
2436 which is always defined in the C++ runtime, should be COMDAT;
2437 false if it should not be COMDAT. */
2439 (library_rtti_comdat,
2442 hook_bool_void_true)
2444 /* Returns true if __aeabi_atexit should be used to register static
2450 hook_bool_void_false)
2452 /* Returns true if target may use atexit in the same manner as
2453 __cxa_atexit to register static destructors. */
2455 (use_atexit_for_cxa_atexit,
2458 hook_bool_void_false)
2461 (adjust_class_at_definition,
2462 "@var{type} is a C++ class (i.e., RECORD_TYPE or UNION_TYPE) that has just\
2463 been defined. Use this hook to make adjustments to the class (eg, tweak\
2464 visibility or perform any other required target modifications).",
2468 HOOK_VECTOR_END (cxx)
2470 /* Functions and data for emulated TLS support. */
2472 #define HOOK_PREFIX "TARGET_EMUTLS_"
2473 HOOK_VECTOR (TARGET_EMUTLS, emutls)
2475 /* Name of the address and common functions. */
2479 const char *, "__builtin___emutls_get_address")
2484 const char *, "__builtin___emutls_register_common")
2486 /* Prefixes for proxy variable and template. */
2497 /* Prefixes for proxy variable and template. */
2508 /* Function to generate field definitions of the proxy variable. */
2512 tree, (tree type, tree *name),
2513 default_emutls_var_fields)
2515 /* Function to initialize a proxy variable. */
2519 tree, (tree var, tree decl, tree tmpl_addr),
2520 default_emutls_var_init)
2522 /* Whether we are allowed to alter the usual alignment of the
2529 /* Whether we can emit debug information for TLS vars. */
2531 (debug_form_tls_address,
2535 HOOK_VECTOR_END (emutls)
2538 #define HOOK_PREFIX "TARGET_OPTION_"
2539 HOOK_VECTOR (TARGET_OPTION_HOOKS, target_option_hooks)
2541 /* Function to validate the attribute((option(...))) strings or NULL. If
2542 the option is validated, it is assumed that DECL_FUNCTION_SPECIFIC will
2543 be filled in in the function decl node. */
2547 bool, (tree fndecl, tree name, tree args, int flags),
2548 default_target_option_valid_attribute_p)
2550 /* Function to save any extra target state in the target options structure. */
2554 void, (struct cl_target_option *ptr), NULL)
2556 /* Function to restore any extra target state from the target options
2561 void, (struct cl_target_option *ptr), NULL)
2563 /* Function to print any extra target state from the target options
2568 void, (FILE *file, int indent, struct cl_target_option *ptr), NULL)
2570 /* Function to parse arguments to be validated for #pragma option, and to
2571 change the state if the options are valid. If the first argument is
2572 NULL, the second argument specifies the default options to use. Return
2573 true if the options are valid, and set the current state. */
2574 /* ??? The documentation in tm.texi is incomplete. */
2578 bool, (tree args, tree pop_target),
2579 default_target_option_pragma_parse)
2581 /* Do option overrides for the target. */
2588 /* Set default optimizations for the target. */
2590 (optimization_table,
2592 const struct default_options *, empty_optimization_table)
2596 "Set target-dependent default values for @option{--param} settings, using\
2597 calls to @code{set_default_param_value}.",
2603 "Set target-dependent initial values of fields in @var{opts}.",
2604 void, (struct gcc_options *opts),
2605 hook_void_gcc_optionsp)
2607 /* Function to determine if one function can inline another function. */
2609 #define HOOK_PREFIX "TARGET_"
2613 bool, (tree caller, tree callee),
2614 default_target_can_inline_p)
2616 HOOK_VECTOR_END (target_option)
2618 /* For targets that need to mark extra registers as live on entry to
2619 the function, they should define this target hook and set their
2620 bits in the bitmap passed in. */
2622 (extra_live_on_entry,
2624 void, (bitmap regs),
2627 /* Determine the type of unwind info to emit for debugging. */
2631 enum unwind_info_type, (void),
2632 default_debug_unwind_info)
2634 /* Determine the type of unwind info to emit for exceptions. */
2636 (except_unwind_info,
2638 enum unwind_info_type, (struct gcc_options *opts),
2639 default_except_unwind_info)
2641 /* Leave the boolean fields at the end. */
2643 /* True if unwinding tables should be generated by default. */
2645 (unwind_tables_default,
2649 /* True if arbitrary sections are supported. */
2651 (have_named_sections,
2655 /* True if we can create zeroed data by switching to a BSS section
2656 and then using ASM_OUTPUT_SKIP to allocate the space. */
2658 (have_switchable_bss_sections,
2662 /* True if "native" constructors and destructors are supported,
2663 false if we're using collect2 for the job. */
2669 /* True if thread-local storage is supported. */
2675 /* True if a small readonly data section is supported. */
2677 (have_srodata_section,
2681 /* True if EH frame info sections should be zero-terminated. */
2683 (terminate_dw2_eh_frame_info,
2687 /* True if #NO_APP should be emitted at the beginning of assembly output. */
2689 (asm_file_start_app_off,
2693 /* True if output_file_directive should be called for main_input_filename
2694 at the beginning of assembly output. */
2696 (asm_file_start_file_directive,
2701 (handle_pragma_extern_prefix,
2702 "True if @code{#pragma extern_prefix} is to be supported.",
2705 /* True if the target is allowed to reorder memory accesses unless
2706 synchronization is explicitly requested. */
2712 /* Returns true if we should generate exception tables for use with the
2713 ARM EABI. The effects the encoding of function exception specifications. */
2720 (want_debug_pub_sections,
2721 "True if the @code{.debug_pubtypes} and @code{.debug_pubnames} sections\
2722 should be emitted. These sections are not used on most platforms, and\
2723 in particular GDB does not use them.",
2726 /* Leave the boolean fields at the end. */
2728 /* Empty macro arguments are undefined in C90, so use an empty macro. */
2729 #define C90_EMPTY_HACK
2730 /* Close the 'struct gcc_target' definition. */
2731 HOOK_VECTOR_END (C90_EMPTY_HACK)
2733 HOOK_VECTOR (TARGETCM_INITIALIZER, gcc_targetcm)
2735 /* Handle target switch CODE (an OPT_* value). ARG is the argument
2736 passed to the switch; it is NULL if no argument was. VALUE is the
2737 value of ARG if CODE specifies a UInteger option, otherwise it is
2738 1 if the positive form of the switch was used and 0 if the negative
2739 form was. Return true if the switch was valid. */
2743 bool, (size_t code, const char *arg, int value),
2744 default_handle_c_option)
2746 /* Targets may provide a string object type that can be used within
2747 and between C, C++, and Objective-C dialects. */
2750 (objc_construct_string_object,
2751 "Targets may provide a string object type that can be used within\
2752 and between C, C++ and their respective Objective-C dialects.\
2753 A string object might, for example, embed encoding and length information.\
2754 These objects are considered opaque to the compiler and handled as references.\
2755 An ideal implementation makes the composition of the string object\
2756 match that of the Objective-C @code{NSString} (@code{NXString} for GNUStep),\
2757 allowing efficient interworking between C-only and Objective-C code.\
2758 If a target implements string objects then this hook should return a\
2759 reference to such an object constructed from the normal `C' string\
2760 representation provided in @var{string}.\
2761 At present, the hook is used by Objective-C only, to obtain a\
2762 common-format string object when the target provides one.",
2763 tree, (tree string),
2767 (string_object_ref_type_p,
2768 "If a target implements string objects then this hook should return\
2769 @code{true} if @var{stringref} is a valid reference to such an object.",
2770 bool, (const_tree stringref),
2771 hook_bool_const_tree_false)
2774 (check_string_object_format_arg,
2775 "If a target implements string objects then this hook should should\
2776 provide a facility to check the function arguments in @var{args_list}\
2777 against the format specifiers in @var{format_arg} where the type of\
2778 @var{format_arg} is one recognized as a valid string reference type.",
2779 void, (tree format_arg, tree args_list),
2782 HOOK_VECTOR_END (C90_EMPTY_HACK)
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