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1 /* Target hook definitions.
2 Copyright (C) 2001-2018 Free Software Foundation, Inc.
4 This program is free software; you can redistribute it and/or modify it
5 under the terms of the GNU General Public License as published by the
6 Free Software Foundation; either version 3, or (at your option) any
7 later version.
9 This program is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 GNU General Public License for more details.
14 You should have received a copy of the GNU General Public License
15 along with this program; see the file COPYING3. If not see
16 <http://www.gnu.org/licenses/>.
18 In other words, you are welcome to use, share and improve this program.
19 You are forbidden to forbid anyone else to use, share and improve
20 what you give them. Help stamp out software-hoarding! */
22 /* See target-hooks-macros.h for details of macros that should be
23 provided by the including file, and how to use them here. */
24 #include "target-hooks-macros.h"
26 #undef HOOK_TYPE
27 #define HOOK_TYPE "Target Hook"
29 HOOK_VECTOR (TARGET_INITIALIZER, gcc_target)
31 /* Functions that output assembler for the target. */
32 #define HOOK_PREFIX "TARGET_ASM_"
33 HOOK_VECTOR (TARGET_ASM_OUT, asm_out)
35 /* Opening and closing parentheses for asm expression grouping. */
36 DEFHOOKPOD
37 (open_paren,
38 "These target hooks are C string constants, describing the syntax in the\n\
39 assembler for grouping arithmetic expressions. If not overridden, they\n\
40 default to normal parentheses, which is correct for most assemblers.",
41 const char *, "(")
42 DEFHOOKPODX (close_paren, const char *, ")")
44 /* Assembler instructions for creating various kinds of integer object. */
45 DEFHOOKPOD
46 (byte_op,
47 "@deftypevrx {Target Hook} {const char *} TARGET_ASM_ALIGNED_HI_OP\n\
48 @deftypevrx {Target Hook} {const char *} TARGET_ASM_ALIGNED_SI_OP\n\
49 @deftypevrx {Target Hook} {const char *} TARGET_ASM_ALIGNED_DI_OP\n\
50 @deftypevrx {Target Hook} {const char *} TARGET_ASM_ALIGNED_TI_OP\n\
51 @deftypevrx {Target Hook} {const char *} TARGET_ASM_UNALIGNED_HI_OP\n\
52 @deftypevrx {Target Hook} {const char *} TARGET_ASM_UNALIGNED_SI_OP\n\
53 @deftypevrx {Target Hook} {const char *} TARGET_ASM_UNALIGNED_DI_OP\n\
54 @deftypevrx {Target Hook} {const char *} TARGET_ASM_UNALIGNED_TI_OP\n\
55 These hooks specify assembly directives for creating certain kinds\n\
56 of integer object. The @code{TARGET_ASM_BYTE_OP} directive creates a\n\
57 byte-sized object, the @code{TARGET_ASM_ALIGNED_HI_OP} one creates an\n\
58 aligned two-byte object, and so on. Any of the hooks may be\n\
59 @code{NULL}, indicating that no suitable directive is available.\n\
60 \n\
61 The compiler will print these strings at the start of a new line,\n\
62 followed immediately by the object's initial value. In most cases,\n\
63 the string should contain a tab, a pseudo-op, and then another tab.",
64 const char *, "\t.byte\t")
65 DEFHOOKPOD (aligned_op, "*", struct asm_int_op, TARGET_ASM_ALIGNED_INT_OP)
66 DEFHOOKPOD (unaligned_op, "*", struct asm_int_op, TARGET_ASM_UNALIGNED_INT_OP)
68 /* Try to output the assembler code for an integer object whose
69 value is given by X. SIZE is the size of the object in bytes and
70 ALIGNED_P indicates whether it is aligned. Return true if
71 successful. Only handles cases for which BYTE_OP, ALIGNED_OP
72 and UNALIGNED_OP are NULL. */
73 DEFHOOK
74 (integer,
75 "The @code{assemble_integer} function uses this hook to output an\n\
76 integer object. @var{x} is the object's value, @var{size} is its size\n\
77 in bytes and @var{aligned_p} indicates whether it is aligned. The\n\
78 function should return @code{true} if it was able to output the\n\
79 object. If it returns false, @code{assemble_integer} will try to\n\
80 split the object into smaller parts.\n\
81 \n\
82 The default implementation of this hook will use the\n\
83 @code{TARGET_ASM_BYTE_OP} family of strings, returning @code{false}\n\
84 when the relevant string is @code{NULL}.",
85 /* Only handles cases for which BYTE_OP, ALIGNED_OP and UNALIGNED_OP are
86 NULL. */
87 bool, (rtx x, unsigned int size, int aligned_p),
88 default_assemble_integer)
90 /* Notify the backend that we have completed emitting the data for a
91 decl. */
92 DEFHOOK
93 (decl_end,
94 "Define this hook if the target assembler requires a special marker to\n\
95 terminate an initialized variable declaration.",
96 void, (void),
97 hook_void_void)
99 /* Output code that will globalize a label. */
100 DEFHOOK
101 (globalize_label,
102 "This target hook is a function to output to the stdio stream\n\
103 @var{stream} some commands that will make the label @var{name} global;\n\
104 that is, available for reference from other files.\n\
106 The default implementation relies on a proper definition of\n\
107 @code{GLOBAL_ASM_OP}.",
108 void, (FILE *stream, const char *name),
109 default_globalize_label)
111 /* Output code that will globalize a declaration. */
112 DEFHOOK
113 (globalize_decl_name,
114 "This target hook is a function to output to the stdio stream\n\
115 @var{stream} some commands that will make the name associated with @var{decl}\n\
116 global; that is, available for reference from other files.\n\
118 The default implementation uses the TARGET_ASM_GLOBALIZE_LABEL target hook.",
119 void, (FILE *stream, tree decl), default_globalize_decl_name)
121 /* Output code that will declare an external variable. */
122 DEFHOOK
123 (assemble_undefined_decl,
124 "This target hook is a function to output to the stdio stream\n\
125 @var{stream} some commands that will declare the name associated with\n\
126 @var{decl} which is not defined in the current translation unit. Most\n\
127 assemblers do not require anything to be output in this case.",
128 void, (FILE *stream, const char *name, const_tree decl),
129 hook_void_FILEptr_constcharptr_const_tree)
131 /* Output code that will emit a label for unwind info, if this
132 target requires such labels. Second argument is the decl the
133 unwind info is associated with, third is a boolean: true if
134 this is for exception handling, fourth is a boolean: true if
135 this is only a placeholder for an omitted FDE. */
136 DEFHOOK
137 (emit_unwind_label,
138 "This target hook emits a label at the beginning of each FDE@. It\n\
139 should be defined on targets where FDEs need special labels, and it\n\
140 should write the appropriate label, for the FDE associated with the\n\
141 function declaration @var{decl}, to the stdio stream @var{stream}.\n\
142 The third argument, @var{for_eh}, is a boolean: true if this is for an\n\
143 exception table. The fourth argument, @var{empty}, is a boolean:\n\
144 true if this is a placeholder label for an omitted FDE@.\n\
146 The default is that FDEs are not given nonlocal labels.",
147 void, (FILE *stream, tree decl, int for_eh, int empty),
148 default_emit_unwind_label)
150 /* Output code that will emit a label to divide up the exception table. */
151 DEFHOOK
152 (emit_except_table_label,
153 "This target hook emits a label at the beginning of the exception table.\n\
154 It should be defined on targets where it is desirable for the table\n\
155 to be broken up according to function.\n\
157 The default is that no label is emitted.",
158 void, (FILE *stream),
159 default_emit_except_table_label)
161 /* Emit a directive for setting the personality for the function. */
162 DEFHOOK
163 (emit_except_personality,
164 "If the target implements @code{TARGET_ASM_UNWIND_EMIT}, this hook may be\
165 used to emit a directive to install a personality hook into the unwind\
166 info. This hook should not be used if dwarf2 unwind info is used.",
167 void, (rtx personality),
168 NULL)
170 /* Emit any directives required to unwind this instruction. */
171 DEFHOOK
172 (unwind_emit,
173 "This target hook emits assembly directives required to unwind the\n\
174 given instruction. This is only used when @code{TARGET_EXCEPT_UNWIND_INFO}\n\
175 returns @code{UI_TARGET}.",
176 void, (FILE *stream, rtx_insn *insn),
177 NULL)
179 DEFHOOKPOD
180 (unwind_emit_before_insn,
181 "True if the @code{TARGET_ASM_UNWIND_EMIT} hook should be called before\
182 the assembly for @var{insn} has been emitted, false if the hook should\
183 be called afterward.",
184 bool, true)
186 /* Generate an internal label.
187 For now this is just a wrapper for ASM_GENERATE_INTERNAL_LABEL. */
188 DEFHOOK_UNDOC
189 (generate_internal_label,
191 void, (char *buf, const char *prefix, unsigned long labelno),
192 default_generate_internal_label)
194 /* Output an internal label. */
195 DEFHOOK
196 (internal_label,
197 "A function to output to the stdio stream @var{stream} a label whose\n\
198 name is made from the string @var{prefix} and the number @var{labelno}.\n\
200 It is absolutely essential that these labels be distinct from the labels\n\
201 used for user-level functions and variables. Otherwise, certain programs\n\
202 will have name conflicts with internal labels.\n\
204 It is desirable to exclude internal labels from the symbol table of the\n\
205 object file. Most assemblers have a naming convention for labels that\n\
206 should be excluded; on many systems, the letter @samp{L} at the\n\
207 beginning of a label has this effect. You should find out what\n\
208 convention your system uses, and follow it.\n\
210 The default version of this function utilizes @code{ASM_GENERATE_INTERNAL_LABEL}.",
211 void, (FILE *stream, const char *prefix, unsigned long labelno),
212 default_internal_label)
214 /* Output label for the constant. */
215 DEFHOOK
216 (declare_constant_name,
217 "A target hook to output to the stdio stream @var{file} any text necessary\n\
218 for declaring the name @var{name} of a constant which is being defined. This\n\
219 target hook is responsible for outputting the label definition (perhaps using\n\
220 @code{assemble_label}). The argument @var{exp} is the value of the constant,\n\
221 and @var{size} is the size of the constant in bytes. The @var{name}\n\
222 will be an internal label.\n\
224 The default version of this target hook, define the @var{name} in the\n\
225 usual manner as a label (by means of @code{assemble_label}).\n\
227 You may wish to use @code{ASM_OUTPUT_TYPE_DIRECTIVE} in this target hook.",
228 void, (FILE *file, const char *name, const_tree expr, HOST_WIDE_INT size),
229 default_asm_declare_constant_name)
231 /* Emit a ttype table reference to a typeinfo object. */
232 DEFHOOK
233 (ttype,
234 "This hook is used to output a reference from a frame unwinding table to\n\
235 the type_info object identified by @var{sym}. It should return @code{true}\n\
236 if the reference was output. Returning @code{false} will cause the\n\
237 reference to be output using the normal Dwarf2 routines.",
238 bool, (rtx sym),
239 hook_bool_rtx_false)
241 /* Emit an assembler directive to set visibility for the symbol
242 associated with the tree decl. */
243 DEFHOOK
244 (assemble_visibility,
245 "This target hook is a function to output to @var{asm_out_file} some\n\
246 commands that will make the symbol(s) associated with @var{decl} have\n\
247 hidden, protected or internal visibility as specified by @var{visibility}.",
248 void, (tree decl, int visibility),
249 default_assemble_visibility)
251 DEFHOOK
252 (print_patchable_function_entry,
253 "Generate a patchable area at the function start, consisting of\n\
254 @var{patch_area_size} NOP instructions. If the target supports named\n\
255 sections and if @var{record_p} is true, insert a pointer to the current\n\
256 location in the table of patchable functions. The default implementation\n\
257 of the hook places the table of pointers in the special section named\n\
258 @code{__patchable_function_entries}.",
259 void, (FILE *file, unsigned HOST_WIDE_INT patch_area_size, bool record_p),
260 default_print_patchable_function_entry)
262 /* Output the assembler code for entry to a function. */
263 DEFHOOK
264 (function_prologue,
265 "If defined, a function that outputs the assembler code for entry to a\n\
266 function. The prologue is responsible for setting up the stack frame,\n\
267 initializing the frame pointer register, saving registers that must be\n\
268 saved, and allocating @var{size} additional bytes of storage for the\n\
269 local variables. @var{file} is a stdio stream to which the assembler\n\
270 code should be output.\n\
272 The label for the beginning of the function need not be output by this\n\
273 macro. That has already been done when the macro is run.\n\
275 @findex regs_ever_live\n\
276 To determine which registers to save, the macro can refer to the array\n\
277 @code{regs_ever_live}: element @var{r} is nonzero if hard register\n\
278 @var{r} is used anywhere within the function. This implies the function\n\
279 prologue should save register @var{r}, provided it is not one of the\n\
280 call-used registers. (@code{TARGET_ASM_FUNCTION_EPILOGUE} must likewise use\n\
281 @code{regs_ever_live}.)\n\
283 On machines that have ``register windows'', the function entry code does\n\
284 not save on the stack the registers that are in the windows, even if\n\
285 they are supposed to be preserved by function calls; instead it takes\n\
286 appropriate steps to ``push'' the register stack, if any non-call-used\n\
287 registers are used in the function.\n\
289 @findex frame_pointer_needed\n\
290 On machines where functions may or may not have frame-pointers, the\n\
291 function entry code must vary accordingly; it must set up the frame\n\
292 pointer if one is wanted, and not otherwise. To determine whether a\n\
293 frame pointer is in wanted, the macro can refer to the variable\n\
294 @code{frame_pointer_needed}. The variable's value will be 1 at run\n\
295 time in a function that needs a frame pointer. @xref{Elimination}.\n\
297 The function entry code is responsible for allocating any stack space\n\
298 required for the function. This stack space consists of the regions\n\
299 listed below. In most cases, these regions are allocated in the\n\
300 order listed, with the last listed region closest to the top of the\n\
301 stack (the lowest address if @code{STACK_GROWS_DOWNWARD} is defined, and\n\
302 the highest address if it is not defined). You can use a different order\n\
303 for a machine if doing so is more convenient or required for\n\
304 compatibility reasons. Except in cases where required by standard\n\
305 or by a debugger, there is no reason why the stack layout used by GCC\n\
306 need agree with that used by other compilers for a machine.",
307 void, (FILE *file),
308 default_function_pro_epilogue)
310 /* Output the assembler code for end of prologue. */
311 DEFHOOK
312 (function_end_prologue,
313 "If defined, a function that outputs assembler code at the end of a\n\
314 prologue. This should be used when the function prologue is being\n\
315 emitted as RTL, and you have some extra assembler that needs to be\n\
316 emitted. @xref{prologue instruction pattern}.",
317 void, (FILE *file),
318 no_asm_to_stream)
320 /* Output the assembler code for start of epilogue. */
321 DEFHOOK
322 (function_begin_epilogue,
323 "If defined, a function that outputs assembler code at the start of an\n\
324 epilogue. This should be used when the function epilogue is being\n\
325 emitted as RTL, and you have some extra assembler that needs to be\n\
326 emitted. @xref{epilogue instruction pattern}.",
327 void, (FILE *file),
328 no_asm_to_stream)
330 /* Output the assembler code for function exit. */
331 DEFHOOK
332 (function_epilogue,
333 "If defined, a function that outputs the assembler code for exit from a\n\
334 function. The epilogue is responsible for restoring the saved\n\
335 registers and stack pointer to their values when the function was\n\
336 called, and returning control to the caller. This macro takes the\n\
337 same argument as the macro @code{TARGET_ASM_FUNCTION_PROLOGUE}, and the\n\
338 registers to restore are determined from @code{regs_ever_live} and\n\
339 @code{CALL_USED_REGISTERS} in the same way.\n\
341 On some machines, there is a single instruction that does all the work\n\
342 of returning from the function. On these machines, give that\n\
343 instruction the name @samp{return} and do not define the macro\n\
344 @code{TARGET_ASM_FUNCTION_EPILOGUE} at all.\n\
346 Do not define a pattern named @samp{return} if you want the\n\
347 @code{TARGET_ASM_FUNCTION_EPILOGUE} to be used. If you want the target\n\
348 switches to control whether return instructions or epilogues are used,\n\
349 define a @samp{return} pattern with a validity condition that tests the\n\
350 target switches appropriately. If the @samp{return} pattern's validity\n\
351 condition is false, epilogues will be used.\n\
353 On machines where functions may or may not have frame-pointers, the\n\
354 function exit code must vary accordingly. Sometimes the code for these\n\
355 two cases is completely different. To determine whether a frame pointer\n\
356 is wanted, the macro can refer to the variable\n\
357 @code{frame_pointer_needed}. The variable's value will be 1 when compiling\n\
358 a function that needs a frame pointer.\n\
360 Normally, @code{TARGET_ASM_FUNCTION_PROLOGUE} and\n\
361 @code{TARGET_ASM_FUNCTION_EPILOGUE} must treat leaf functions specially.\n\
362 The C variable @code{current_function_is_leaf} is nonzero for such a\n\
363 function. @xref{Leaf Functions}.\n\
365 On some machines, some functions pop their arguments on exit while\n\
366 others leave that for the caller to do. For example, the 68020 when\n\
367 given @option{-mrtd} pops arguments in functions that take a fixed\n\
368 number of arguments.\n\
370 @findex pops_args\n\
371 @findex crtl->args.pops_args\n\
372 Your definition of the macro @code{RETURN_POPS_ARGS} decides which\n\
373 functions pop their own arguments. @code{TARGET_ASM_FUNCTION_EPILOGUE}\n\
374 needs to know what was decided. The number of bytes of the current\n\
375 function's arguments that this function should pop is available in\n\
376 @code{crtl->args.pops_args}. @xref{Scalar Return}.",
377 void, (FILE *file),
378 default_function_pro_epilogue)
380 /* Initialize target-specific sections. */
381 DEFHOOK
382 (init_sections,
383 "Define this hook if you need to do something special to set up the\n\
384 @file{varasm.c} sections, or if your target has some special sections\n\
385 of its own that you need to create.\n\
387 GCC calls this hook after processing the command line, but before writing\n\
388 any assembly code, and before calling any of the section-returning hooks\n\
389 described below.",
390 void, (void),
391 hook_void_void)
393 /* Tell assembler to change to section NAME with attributes FLAGS.
394 If DECL is non-NULL, it is the VAR_DECL or FUNCTION_DECL with
395 which this section is associated. */
396 DEFHOOK
397 (named_section,
398 "Output assembly directives to switch to section @var{name}. The section\n\
399 should have attributes as specified by @var{flags}, which is a bit mask\n\
400 of the @code{SECTION_*} flags defined in @file{output.h}. If @var{decl}\n\
401 is non-NULL, it is the @code{VAR_DECL} or @code{FUNCTION_DECL} with which\n\
402 this section is associated.",
403 void, (const char *name, unsigned int flags, tree decl),
404 default_no_named_section)
406 /* Tell assembler what section attributes to assign this elf section
407 declaration, using their numerical value. */
408 DEFHOOK
409 (elf_flags_numeric,
410 "This hook can be used to encode ELF section flags for which no letter\n\
411 code has been defined in the assembler. It is called by\n\
412 @code{default_asm_named_section} whenever the section flags need to be\n\
413 emitted in the assembler output. If the hook returns true, then the\n\
414 numerical value for ELF section flags should be calculated from\n\
415 @var{flags} and saved in @var{*num}; the value is printed out instead of the\n\
416 normal sequence of letter codes. If the hook is not defined, or if it\n\
417 returns false, then @var{num} is ignored and the traditional letter sequence\n\
418 is emitted.",
419 bool, (unsigned int flags, unsigned int *num),
420 hook_bool_uint_uintp_false)
422 /* Return preferred text (sub)section for function DECL.
423 Main purpose of this function is to separate cold, normal and hot
424 functions. STARTUP is true when function is known to be used only
425 at startup (from static constructors or it is main()).
426 EXIT is true when function is known to be used only at exit
427 (from static destructors).
428 Return NULL if function should go to default text section. */
429 DEFHOOK
430 (function_section,
431 "Return preferred text (sub)section for function @var{decl}.\n\
432 Main purpose of this function is to separate cold, normal and hot\n\
433 functions. @var{startup} is true when function is known to be used only\n\
434 at startup (from static constructors or it is @code{main()}).\n\
435 @var{exit} is true when function is known to be used only at exit\n\
436 (from static destructors).\n\
437 Return NULL if function should go to default text section.",
438 section *, (tree decl, enum node_frequency freq, bool startup, bool exit),
439 default_function_section)
441 /* Output the assembler code for function exit. */
442 DEFHOOK
443 (function_switched_text_sections,
444 "Used by the target to emit any assembler directives or additional\
445 labels needed when a function is partitioned between different\
446 sections. Output should be written to @var{file}. The function\
447 decl is available as @var{decl} and the new section is `cold' if\
448 @var{new_is_cold} is @code{true}.",
449 void, (FILE *file, tree decl, bool new_is_cold),
450 default_function_switched_text_sections)
452 /* Return a mask describing how relocations should be treated when
453 selecting sections. Bit 1 should be set if global relocations
454 should be placed in a read-write section; bit 0 should be set if
455 local relocations should be placed in a read-write section. */
456 DEFHOOK
457 (reloc_rw_mask,
458 "Return a mask describing how relocations should be treated when\n\
459 selecting sections. Bit 1 should be set if global relocations\n\
460 should be placed in a read-write section; bit 0 should be set if\n\
461 local relocations should be placed in a read-write section.\n\
463 The default version of this function returns 3 when @option{-fpic}\n\
464 is in effect, and 0 otherwise. The hook is typically redefined\n\
465 when the target cannot support (some kinds of) dynamic relocations\n\
466 in read-only sections even in executables.",
467 int, (void),
468 default_reloc_rw_mask)
470 /* Return a flag for either generating ADDR_DIF_VEC table
471 or ADDR_VEC table for jumps in case of -fPIC/-fPIE. */
472 DEFHOOK
473 (generate_pic_addr_diff_vec,
474 "Return true to generate ADDR_DIF_VEC table\n\
475 or false to generate ADDR_VEC table for jumps in case of -fPIC.\n\
477 The default version of this function returns true if flag_pic\n\
478 equals true and false otherwise",
479 bool, (void),
480 default_generate_pic_addr_diff_vec)
482 /* Return a section for EXP. It may be a DECL or a constant. RELOC
483 is nonzero if runtime relocations must be applied; bit 1 will be
484 set if the runtime relocations require non-local name resolution.
485 ALIGN is the required alignment of the data. */
486 DEFHOOK
487 (select_section,
488 "Return the section into which @var{exp} should be placed. You can\n\
489 assume that @var{exp} is either a @code{VAR_DECL} node or a constant of\n\
490 some sort. @var{reloc} indicates whether the initial value of @var{exp}\n\
491 requires link-time relocations. Bit 0 is set when variable contains\n\
492 local relocations only, while bit 1 is set for global relocations.\n\
493 @var{align} is the constant alignment in bits.\n\
495 The default version of this function takes care of putting read-only\n\
496 variables in @code{readonly_data_section}.\n\
498 See also @var{USE_SELECT_SECTION_FOR_FUNCTIONS}.",
499 section *, (tree exp, int reloc, unsigned HOST_WIDE_INT align),
500 default_select_section)
502 /* Return a section for X. MODE is X's mode and ALIGN is its
503 alignment in bits. */
504 DEFHOOK
505 (select_rtx_section,
506 "Return the section into which a constant @var{x}, of mode @var{mode},\n\
507 should be placed. You can assume that @var{x} is some kind of\n\
508 constant in RTL@. The argument @var{mode} is redundant except in the\n\
509 case of a @code{const_int} rtx. @var{align} is the constant alignment\n\
510 in bits.\n\
512 The default version of this function takes care of putting symbolic\n\
513 constants in @code{flag_pic} mode in @code{data_section} and everything\n\
514 else in @code{readonly_data_section}.",
515 section *, (machine_mode mode, rtx x, unsigned HOST_WIDE_INT align),
516 default_select_rtx_section)
518 /* Select a unique section name for DECL. RELOC is the same as
519 for SELECT_SECTION. */
520 DEFHOOK
521 (unique_section,
522 "Build up a unique section name, expressed as a @code{STRING_CST} node,\n\
523 and assign it to @samp{DECL_SECTION_NAME (@var{decl})}.\n\
524 As with @code{TARGET_ASM_SELECT_SECTION}, @var{reloc} indicates whether\n\
525 the initial value of @var{exp} requires link-time relocations.\n\
527 The default version of this function appends the symbol name to the\n\
528 ELF section name that would normally be used for the symbol. For\n\
529 example, the function @code{foo} would be placed in @code{.text.foo}.\n\
530 Whatever the actual target object format, this is often good enough.",
531 void, (tree decl, int reloc),
532 default_unique_section)
534 /* Return the readonly data section associated with function DECL. */
535 DEFHOOK
536 (function_rodata_section,
537 "Return the readonly data section associated with\n\
538 @samp{DECL_SECTION_NAME (@var{decl})}.\n\
539 The default version of this function selects @code{.gnu.linkonce.r.name} if\n\
540 the function's section is @code{.gnu.linkonce.t.name}, @code{.rodata.name}\n\
541 if function is in @code{.text.name}, and the normal readonly-data section\n\
542 otherwise.",
543 section *, (tree decl),
544 default_function_rodata_section)
546 /* Nonnull if the target wants to override the default ".rodata" prefix
547 for mergeable data sections. */
548 DEFHOOKPOD
549 (mergeable_rodata_prefix,
550 "Usually, the compiler uses the prefix @code{\".rodata\"} to construct\n\
551 section names for mergeable constant data. Define this macro to override\n\
552 the string if a different section name should be used.",
553 const char *, ".rodata")
555 /* Return the section to be used for transactional memory clone tables. */
556 DEFHOOK
557 (tm_clone_table_section,
558 "Return the section that should be used for transactional memory clone\
559 tables.",
560 section *, (void), default_clone_table_section)
562 /* Output a constructor for a symbol with a given priority. */
563 DEFHOOK
564 (constructor,
565 "If defined, a function that outputs assembler code to arrange to call\n\
566 the function referenced by @var{symbol} at initialization time.\n\
568 Assume that @var{symbol} is a @code{SYMBOL_REF} for a function taking\n\
569 no arguments and with no return value. If the target supports initialization\n\
570 priorities, @var{priority} is a value between 0 and @code{MAX_INIT_PRIORITY};\n\
571 otherwise it must be @code{DEFAULT_INIT_PRIORITY}.\n\
573 If this macro is not defined by the target, a suitable default will\n\
574 be chosen if (1) the target supports arbitrary section names, (2) the\n\
575 target defines @code{CTORS_SECTION_ASM_OP}, or (3) @code{USE_COLLECT2}\n\
576 is not defined.",
577 void, (rtx symbol, int priority), NULL)
579 /* Output a destructor for a symbol with a given priority. */
580 DEFHOOK
581 (destructor,
582 "This is like @code{TARGET_ASM_CONSTRUCTOR} but used for termination\n\
583 functions rather than initialization functions.",
584 void, (rtx symbol, int priority), NULL)
586 /* Output the assembler code for a thunk function. THUNK_DECL is the
587 declaration for the thunk function itself, FUNCTION is the decl for
588 the target function. DELTA is an immediate constant offset to be
589 added to THIS. If VCALL_OFFSET is nonzero, the word at
590 *(*this + vcall_offset) should be added to THIS. */
591 DEFHOOK
592 (output_mi_thunk,
593 "A function that outputs the assembler code for a thunk\n\
594 function, used to implement C++ virtual function calls with multiple\n\
595 inheritance. The thunk acts as a wrapper around a virtual function,\n\
596 adjusting the implicit object parameter before handing control off to\n\
597 the real function.\n\
599 First, emit code to add the integer @var{delta} to the location that\n\
600 contains the incoming first argument. Assume that this argument\n\
601 contains a pointer, and is the one used to pass the @code{this} pointer\n\
602 in C++. This is the incoming argument @emph{before} the function prologue,\n\
603 e.g.@: @samp{%o0} on a sparc. The addition must preserve the values of\n\
604 all other incoming arguments.\n\
606 Then, if @var{vcall_offset} is nonzero, an additional adjustment should be\n\
607 made after adding @code{delta}. In particular, if @var{p} is the\n\
608 adjusted pointer, the following adjustment should be made:\n\
610 @smallexample\n\
611 p += (*((ptrdiff_t **)p))[vcall_offset/sizeof(ptrdiff_t)]\n\
612 @end smallexample\n\
614 After the additions, emit code to jump to @var{function}, which is a\n\
615 @code{FUNCTION_DECL}. This is a direct pure jump, not a call, and does\n\
616 not touch the return address. Hence returning from @var{FUNCTION} will\n\
617 return to whoever called the current @samp{thunk}.\n\
619 The effect must be as if @var{function} had been called directly with\n\
620 the adjusted first argument. This macro is responsible for emitting all\n\
621 of the code for a thunk function; @code{TARGET_ASM_FUNCTION_PROLOGUE}\n\
622 and @code{TARGET_ASM_FUNCTION_EPILOGUE} are not invoked.\n\
624 The @var{thunk_fndecl} is redundant. (@var{delta} and @var{function}\n\
625 have already been extracted from it.) It might possibly be useful on\n\
626 some targets, but probably not.\n\
628 If you do not define this macro, the target-independent code in the C++\n\
629 front end will generate a less efficient heavyweight thunk that calls\n\
630 @var{function} instead of jumping to it. The generic approach does\n\
631 not support varargs.",
632 void, (FILE *file, tree thunk_fndecl, HOST_WIDE_INT delta,
633 HOST_WIDE_INT vcall_offset, tree function),
634 NULL)
636 /* Determine whether output_mi_thunk would succeed. */
637 /* ??? Ideally, this hook would not exist, and success or failure
638 would be returned from output_mi_thunk directly. But there's
639 too much undo-able setup involved in invoking output_mi_thunk.
640 Could be fixed by making output_mi_thunk emit rtl instead of
641 text to the output file. */
642 DEFHOOK
643 (can_output_mi_thunk,
644 "A function that returns true if TARGET_ASM_OUTPUT_MI_THUNK would be able\n\
645 to output the assembler code for the thunk function specified by the\n\
646 arguments it is passed, and false otherwise. In the latter case, the\n\
647 generic approach will be used by the C++ front end, with the limitations\n\
648 previously exposed.",
649 bool, (const_tree thunk_fndecl, HOST_WIDE_INT delta,
650 HOST_WIDE_INT vcall_offset, const_tree function),
651 hook_bool_const_tree_hwi_hwi_const_tree_false)
653 /* Output any boilerplate text needed at the beginning of a
654 translation unit. */
655 DEFHOOK
656 (file_start,
657 "Output to @code{asm_out_file} any text which the assembler expects to\n\
658 find at the beginning of a file. The default behavior is controlled\n\
659 by two flags, documented below. Unless your target's assembler is\n\
660 quite unusual, if you override the default, you should call\n\
661 @code{default_file_start} at some point in your target hook. This\n\
662 lets other target files rely on these variables.",
663 void, (void),
664 default_file_start)
666 /* Output any boilerplate text needed at the end of a translation unit. */
667 DEFHOOK
668 (file_end,
669 "Output to @code{asm_out_file} any text which the assembler expects\n\
670 to find at the end of a file. The default is to output nothing.",
671 void, (void),
672 hook_void_void)
674 /* Output any boilerplate text needed at the beginning of an
675 LTO output stream. */
676 DEFHOOK
677 (lto_start,
678 "Output to @code{asm_out_file} any text which the assembler expects\n\
679 to find at the start of an LTO section. The default is to output\n\
680 nothing.",
681 void, (void),
682 hook_void_void)
684 /* Output any boilerplate text needed at the end of an
685 LTO output stream. */
686 DEFHOOK
687 (lto_end,
688 "Output to @code{asm_out_file} any text which the assembler expects\n\
689 to find at the end of an LTO section. The default is to output\n\
690 nothing.",
691 void, (void),
692 hook_void_void)
694 /* Output any boilerplace text needed at the end of a
695 translation unit before debug and unwind info is emitted. */
696 DEFHOOK
697 (code_end,
698 "Output to @code{asm_out_file} any text which is needed before emitting\n\
699 unwind info and debug info at the end of a file. Some targets emit\n\
700 here PIC setup thunks that cannot be emitted at the end of file,\n\
701 because they couldn't have unwind info then. The default is to output\n\
702 nothing.",
703 void, (void),
704 hook_void_void)
706 /* Output an assembler pseudo-op to declare a library function name
707 external. */
708 DEFHOOK
709 (external_libcall,
710 "This target hook is a function to output to @var{asm_out_file} an assembler\n\
711 pseudo-op to declare a library function name external. The name of the\n\
712 library function is given by @var{symref}, which is a @code{symbol_ref}.",
713 void, (rtx symref),
714 default_external_libcall)
716 /* Output an assembler directive to mark decl live. This instructs
717 linker to not dead code strip this symbol. */
718 DEFHOOK
719 (mark_decl_preserved,
720 "This target hook is a function to output to @var{asm_out_file} an assembler\n\
721 directive to annotate @var{symbol} as used. The Darwin target uses the\n\
722 .no_dead_code_strip directive.",
723 void, (const char *symbol),
724 hook_void_constcharptr)
726 /* Output a record of the command line switches that have been passed. */
727 DEFHOOK
728 (record_gcc_switches,
729 "Provides the target with the ability to record the gcc command line\n\
730 switches that have been passed to the compiler, and options that are\n\
731 enabled. The @var{type} argument specifies what is being recorded.\n\
732 It can take the following values:\n\
734 @table @gcctabopt\n\
735 @item SWITCH_TYPE_PASSED\n\
736 @var{text} is a command line switch that has been set by the user.\n\
738 @item SWITCH_TYPE_ENABLED\n\
739 @var{text} is an option which has been enabled. This might be as a\n\
740 direct result of a command line switch, or because it is enabled by\n\
741 default or because it has been enabled as a side effect of a different\n\
742 command line switch. For example, the @option{-O2} switch enables\n\
743 various different individual optimization passes.\n\
745 @item SWITCH_TYPE_DESCRIPTIVE\n\
746 @var{text} is either NULL or some descriptive text which should be\n\
747 ignored. If @var{text} is NULL then it is being used to warn the\n\
748 target hook that either recording is starting or ending. The first\n\
749 time @var{type} is SWITCH_TYPE_DESCRIPTIVE and @var{text} is NULL, the\n\
750 warning is for start up and the second time the warning is for\n\
751 wind down. This feature is to allow the target hook to make any\n\
752 necessary preparations before it starts to record switches and to\n\
753 perform any necessary tidying up after it has finished recording\n\
754 switches.\n\
756 @item SWITCH_TYPE_LINE_START\n\
757 This option can be ignored by this target hook.\n\
759 @item SWITCH_TYPE_LINE_END\n\
760 This option can be ignored by this target hook.\n\
761 @end table\n\
763 The hook's return value must be zero. Other return values may be\n\
764 supported in the future.\n\
766 By default this hook is set to NULL, but an example implementation is\n\
767 provided for ELF based targets. Called @var{elf_record_gcc_switches},\n\
768 it records the switches as ASCII text inside a new, string mergeable\n\
769 section in the assembler output file. The name of the new section is\n\
770 provided by the @code{TARGET_ASM_RECORD_GCC_SWITCHES_SECTION} target\n\
771 hook.",
772 int, (print_switch_type type, const char *text),
773 NULL)
775 /* The name of the section that the example ELF implementation of
776 record_gcc_switches will use to store the information. Target
777 specific versions of record_gcc_switches may or may not use
778 this information. */
779 DEFHOOKPOD
780 (record_gcc_switches_section,
781 "This is the name of the section that will be created by the example\n\
782 ELF implementation of the @code{TARGET_ASM_RECORD_GCC_SWITCHES} target\n\
783 hook.",
784 const char *, ".GCC.command.line")
786 /* Output the definition of a section anchor. */
787 DEFHOOK
788 (output_anchor,
789 "Write the assembly code to define section anchor @var{x}, which is a\n\
790 @code{SYMBOL_REF} for which @samp{SYMBOL_REF_ANCHOR_P (@var{x})} is true.\n\
791 The hook is called with the assembly output position set to the beginning\n\
792 of @code{SYMBOL_REF_BLOCK (@var{x})}.\n\
794 If @code{ASM_OUTPUT_DEF} is available, the hook's default definition uses\n\
795 it to define the symbol as @samp{. + SYMBOL_REF_BLOCK_OFFSET (@var{x})}.\n\
796 If @code{ASM_OUTPUT_DEF} is not available, the hook's default definition\n\
797 is @code{NULL}, which disables the use of section anchors altogether.",
798 void, (rtx x),
799 default_asm_output_anchor)
801 DEFHOOK
802 (output_ident,
803 "Output a string based on @var{name}, suitable for the @samp{#ident} \
804 directive, or the equivalent directive or pragma in non-C-family languages. \
805 If this hook is not defined, nothing is output for the @samp{#ident} \
806 directive.",
807 void, (const char *name),
808 hook_void_constcharptr)
810 /* Output a DTP-relative reference to a TLS symbol. */
811 DEFHOOK
812 (output_dwarf_dtprel,
813 "If defined, this target hook is a function which outputs a DTP-relative\n\
814 reference to the given TLS symbol of the specified size.",
815 void, (FILE *file, int size, rtx x),
816 NULL)
818 /* Some target machines need to postscan each insn after it is output. */
819 DEFHOOK
820 (final_postscan_insn,
821 "If defined, this target hook is a function which is executed just after the\n\
822 output of assembler code for @var{insn}, to change the mode of the assembler\n\
823 if necessary.\n\
825 Here the argument @var{opvec} is the vector containing the operands\n\
826 extracted from @var{insn}, and @var{noperands} is the number of\n\
827 elements of the vector which contain meaningful data for this insn.\n\
828 The contents of this vector are what was used to convert the insn\n\
829 template into assembler code, so you can change the assembler mode\n\
830 by checking the contents of the vector.",
831 void, (FILE *file, rtx_insn *insn, rtx *opvec, int noperands),
832 NULL)
834 /* Emit the trampoline template. This hook may be NULL. */
835 DEFHOOK
836 (trampoline_template,
837 "This hook is called by @code{assemble_trampoline_template} to output,\n\
838 on the stream @var{f}, assembler code for a block of data that contains\n\
839 the constant parts of a trampoline. This code should not include a\n\
840 label---the label is taken care of automatically.\n\
842 If you do not define this hook, it means no template is needed\n\
843 for the target. Do not define this hook on systems where the block move\n\
844 code to copy the trampoline into place would be larger than the code\n\
845 to generate it on the spot.",
846 void, (FILE *f),
847 NULL)
849 DEFHOOK
850 (output_source_filename,
851 "Output DWARF debugging information which indicates that filename\
852 @var{name} is the current source file to the stdio stream @var{file}.\n\
854 This target hook need not be defined if the standard form of output\
855 for the file format in use is appropriate.",
856 void ,(FILE *file, const char *name),
857 default_asm_output_source_filename)
859 DEFHOOK
860 (output_addr_const_extra,
861 "A target hook to recognize @var{rtx} patterns that @code{output_addr_const}\n\
862 can't deal with, and output assembly code to @var{file} corresponding to\n\
863 the pattern @var{x}. This may be used to allow machine-dependent\n\
864 @code{UNSPEC}s to appear within constants.\n\
866 If target hook fails to recognize a pattern, it must return @code{false},\n\
867 so that a standard error message is printed. If it prints an error message\n\
868 itself, by calling, for example, @code{output_operand_lossage}, it may just\n\
869 return @code{true}.",
870 bool, (FILE *file, rtx x),
871 hook_bool_FILEptr_rtx_false)
873 /* ??? The TARGET_PRINT_OPERAND* hooks are part of the asm_out struct,
874 even though that is not reflected in the macro name to override their
875 initializers. */
876 #undef HOOK_PREFIX
877 #define HOOK_PREFIX "TARGET_"
879 /* Emit a machine-specific insn operand. */
880 /* ??? tm.texi only documents the old macro PRINT_OPERAND,
881 not this hook, and uses a different name for the argument FILE. */
882 DEFHOOK_UNDOC
883 (print_operand,
885 void, (FILE *file, rtx x, int code),
886 default_print_operand)
888 /* Emit a machine-specific memory address. */
889 /* ??? tm.texi only documents the old macro PRINT_OPERAND_ADDRESS,
890 not this hook, and uses different argument names. */
891 DEFHOOK_UNDOC
892 (print_operand_address,
894 void, (FILE *file, machine_mode mode, rtx addr),
895 default_print_operand_address)
897 /* Determine whether CODE is a valid punctuation character for the
898 `print_operand' hook. */
899 /* ??? tm.texi only documents the old macro PRINT_OPERAND_PUNCT_VALID_P,
900 not this hook. */
901 DEFHOOK_UNDOC
902 (print_operand_punct_valid_p,
904 bool ,(unsigned char code),
905 default_print_operand_punct_valid_p)
907 /* Given a symbol name, perform same mangling as assemble_name and
908 ASM_OUTPUT_LABELREF, returning result as an IDENTIFIER_NODE. */
909 DEFHOOK
910 (mangle_assembler_name,
911 "Given a symbol @var{name}, perform same mangling as @code{varasm.c}'s\
912 @code{assemble_name}, but in memory rather than to a file stream, returning\
913 result as an @code{IDENTIFIER_NODE}. Required for correct LTO symtabs. The\
914 default implementation calls the @code{TARGET_STRIP_NAME_ENCODING} hook and\
915 then prepends the @code{USER_LABEL_PREFIX}, if any.",
916 tree, (const char *name),
917 default_mangle_assembler_name)
919 HOOK_VECTOR_END (asm_out)
921 /* Functions relating to instruction scheduling. All of these
922 default to null pointers, which haifa-sched.c looks for and handles. */
923 #undef HOOK_PREFIX
924 #define HOOK_PREFIX "TARGET_SCHED_"
925 HOOK_VECTOR (TARGET_SCHED, sched)
927 /* Given the current cost, COST, of an insn, INSN, calculate and
928 return a new cost based on its relationship to DEP_INSN through
929 the dependence LINK. The default is to make no adjustment. */
930 DEFHOOK
931 (adjust_cost,
932 "This function corrects the value of @var{cost} based on the\n\
933 relationship between @var{insn} and @var{dep_insn} through a\n\
934 dependence of type dep_type, and strength @var{dw}. It should return the new\n\
935 value. The default is to make no adjustment to @var{cost}. This can be\n\
936 used for example to specify to the scheduler using the traditional pipeline\n\
937 description that an output- or anti-dependence does not incur the same cost\n\
938 as a data-dependence. If the scheduler using the automaton based pipeline\n\
939 description, the cost of anti-dependence is zero and the cost of\n\
940 output-dependence is maximum of one and the difference of latency\n\
941 times of the first and the second insns. If these values are not\n\
942 acceptable, you could use the hook to modify them too. See also\n\
943 @pxref{Processor pipeline description}.",
944 int, (rtx_insn *insn, int dep_type1, rtx_insn *dep_insn, int cost,
945 unsigned int dw),
946 NULL)
948 /* Adjust the priority of an insn as you see fit. Returns the new priority. */
949 DEFHOOK
950 (adjust_priority,
951 "This hook adjusts the integer scheduling priority @var{priority} of\n\
952 @var{insn}. It should return the new priority. Increase the priority to\n\
953 execute @var{insn} earlier, reduce the priority to execute @var{insn}\n\
954 later. Do not define this hook if you do not need to adjust the\n\
955 scheduling priorities of insns.",
956 int, (rtx_insn *insn, int priority), NULL)
958 /* Function which returns the maximum number of insns that can be
959 scheduled in the same machine cycle. This must be constant
960 over an entire compilation. The default is 1. */
961 DEFHOOK
962 (issue_rate,
963 "This hook returns the maximum number of instructions that can ever\n\
964 issue at the same time on the target machine. The default is one.\n\
965 Although the insn scheduler can define itself the possibility of issue\n\
966 an insn on the same cycle, the value can serve as an additional\n\
967 constraint to issue insns on the same simulated processor cycle (see\n\
968 hooks @samp{TARGET_SCHED_REORDER} and @samp{TARGET_SCHED_REORDER2}).\n\
969 This value must be constant over the entire compilation. If you need\n\
970 it to vary depending on what the instructions are, you must use\n\
971 @samp{TARGET_SCHED_VARIABLE_ISSUE}.",
972 int, (void), NULL)
974 /* Calculate how much this insn affects how many more insns we
975 can emit this cycle. Default is they all cost the same. */
976 DEFHOOK
977 (variable_issue,
978 "This hook is executed by the scheduler after it has scheduled an insn\n\
979 from the ready list. It should return the number of insns which can\n\
980 still be issued in the current cycle. The default is\n\
981 @samp{@w{@var{more} - 1}} for insns other than @code{CLOBBER} and\n\
982 @code{USE}, which normally are not counted against the issue rate.\n\
983 You should define this hook if some insns take more machine resources\n\
984 than others, so that fewer insns can follow them in the same cycle.\n\
985 @var{file} is either a null pointer, or a stdio stream to write any\n\
986 debug output to. @var{verbose} is the verbose level provided by\n\
987 @option{-fsched-verbose-@var{n}}. @var{insn} is the instruction that\n\
988 was scheduled.",
989 int, (FILE *file, int verbose, rtx_insn *insn, int more), NULL)
991 /* Initialize machine-dependent scheduling code. */
992 DEFHOOK
993 (init,
994 "This hook is executed by the scheduler at the beginning of each block of\n\
995 instructions that are to be scheduled. @var{file} is either a null\n\
996 pointer, or a stdio stream to write any debug output to. @var{verbose}\n\
997 is the verbose level provided by @option{-fsched-verbose-@var{n}}.\n\
998 @var{max_ready} is the maximum number of insns in the current scheduling\n\
999 region that can be live at the same time. This can be used to allocate\n\
1000 scratch space if it is needed, e.g.@: by @samp{TARGET_SCHED_REORDER}.",
1001 void, (FILE *file, int verbose, int max_ready), NULL)
1003 /* Finalize machine-dependent scheduling code. */
1004 DEFHOOK
1005 (finish,
1006 "This hook is executed by the scheduler at the end of each block of\n\
1007 instructions that are to be scheduled. It can be used to perform\n\
1008 cleanup of any actions done by the other scheduling hooks. @var{file}\n\
1009 is either a null pointer, or a stdio stream to write any debug output\n\
1010 to. @var{verbose} is the verbose level provided by\n\
1011 @option{-fsched-verbose-@var{n}}.",
1012 void, (FILE *file, int verbose), NULL)
1014 /* Initialize machine-dependent function wide scheduling code. */
1015 DEFHOOK
1016 (init_global,
1017 "This hook is executed by the scheduler after function level initializations.\n\
1018 @var{file} is either a null pointer, or a stdio stream to write any debug output to.\n\
1019 @var{verbose} is the verbose level provided by @option{-fsched-verbose-@var{n}}.\n\
1020 @var{old_max_uid} is the maximum insn uid when scheduling begins.",
1021 void, (FILE *file, int verbose, int old_max_uid), NULL)
1023 /* Finalize machine-dependent function wide scheduling code. */
1024 DEFHOOK
1025 (finish_global,
1026 "This is the cleanup hook corresponding to @code{TARGET_SCHED_INIT_GLOBAL}.\n\
1027 @var{file} is either a null pointer, or a stdio stream to write any debug output to.\n\
1028 @var{verbose} is the verbose level provided by @option{-fsched-verbose-@var{n}}.",
1029 void, (FILE *file, int verbose), NULL)
1031 /* Reorder insns in a machine-dependent fashion, in two different
1032 places. Default does nothing. */
1033 DEFHOOK
1034 (reorder,
1035 "This hook is executed by the scheduler after it has scheduled the ready\n\
1036 list, to allow the machine description to reorder it (for example to\n\
1037 combine two small instructions together on @samp{VLIW} machines).\n\
1038 @var{file} is either a null pointer, or a stdio stream to write any\n\
1039 debug output to. @var{verbose} is the verbose level provided by\n\
1040 @option{-fsched-verbose-@var{n}}. @var{ready} is a pointer to the ready\n\
1041 list of instructions that are ready to be scheduled. @var{n_readyp} is\n\
1042 a pointer to the number of elements in the ready list. The scheduler\n\
1043 reads the ready list in reverse order, starting with\n\
1044 @var{ready}[@var{*n_readyp} @minus{} 1] and going to @var{ready}[0]. @var{clock}\n\
1045 is the timer tick of the scheduler. You may modify the ready list and\n\
1046 the number of ready insns. The return value is the number of insns that\n\
1047 can issue this cycle; normally this is just @code{issue_rate}. See also\n\
1048 @samp{TARGET_SCHED_REORDER2}.",
1049 int, (FILE *file, int verbose, rtx_insn **ready, int *n_readyp, int clock), NULL)
1051 DEFHOOK
1052 (reorder2,
1053 "Like @samp{TARGET_SCHED_REORDER}, but called at a different time. That\n\
1054 function is called whenever the scheduler starts a new cycle. This one\n\
1055 is called once per iteration over a cycle, immediately after\n\
1056 @samp{TARGET_SCHED_VARIABLE_ISSUE}; it can reorder the ready list and\n\
1057 return the number of insns to be scheduled in the same cycle. Defining\n\
1058 this hook can be useful if there are frequent situations where\n\
1059 scheduling one insn causes other insns to become ready in the same\n\
1060 cycle. These other insns can then be taken into account properly.",
1061 int, (FILE *file, int verbose, rtx_insn **ready, int *n_readyp, int clock), NULL)
1063 DEFHOOK
1064 (macro_fusion_p,
1065 "This hook is used to check whether target platform supports macro fusion.",
1066 bool, (void), NULL)
1068 DEFHOOK
1069 (macro_fusion_pair_p,
1070 "This hook is used to check whether two insns should be macro fused for\n\
1071 a target microarchitecture. If this hook returns true for the given insn pair\n\
1072 (@var{prev} and @var{curr}), the scheduler will put them into a sched\n\
1073 group, and they will not be scheduled apart. The two insns will be either\n\
1074 two SET insns or a compare and a conditional jump and this hook should\n\
1075 validate any dependencies needed to fuse the two insns together.",
1076 bool, (rtx_insn *prev, rtx_insn *curr), NULL)
1078 /* The following member value is a pointer to a function called
1079 after evaluation forward dependencies of insns in chain given
1080 by two parameter values (head and tail correspondingly). */
1081 DEFHOOK
1082 (dependencies_evaluation_hook,
1083 "This hook is called after evaluation forward dependencies of insns in\n\
1084 chain given by two parameter values (@var{head} and @var{tail}\n\
1085 correspondingly) but before insns scheduling of the insn chain. For\n\
1086 example, it can be used for better insn classification if it requires\n\
1087 analysis of dependencies. This hook can use backward and forward\n\
1088 dependencies of the insn scheduler because they are already\n\
1089 calculated.",
1090 void, (rtx_insn *head, rtx_insn *tail), NULL)
1092 /* The values of the following four members are pointers to functions
1093 used to simplify the automaton descriptions. dfa_pre_cycle_insn and
1094 dfa_post_cycle_insn give functions returning insns which are used to
1095 change the pipeline hazard recognizer state when the new simulated
1096 processor cycle correspondingly starts and finishes. The function
1097 defined by init_dfa_pre_cycle_insn and init_dfa_post_cycle_insn are
1098 used to initialize the corresponding insns. The default values of
1099 the members result in not changing the automaton state when the
1100 new simulated processor cycle correspondingly starts and finishes. */
1102 DEFHOOK
1103 (init_dfa_pre_cycle_insn,
1104 "The hook can be used to initialize data used by the previous hook.",
1105 void, (void), NULL)
1107 DEFHOOK
1108 (dfa_pre_cycle_insn,
1109 "The hook returns an RTL insn. The automaton state used in the\n\
1110 pipeline hazard recognizer is changed as if the insn were scheduled\n\
1111 when the new simulated processor cycle starts. Usage of the hook may\n\
1112 simplify the automaton pipeline description for some @acronym{VLIW}\n\
1113 processors. If the hook is defined, it is used only for the automaton\n\
1114 based pipeline description. The default is not to change the state\n\
1115 when the new simulated processor cycle starts.",
1116 rtx, (void), NULL)
1118 DEFHOOK
1119 (init_dfa_post_cycle_insn,
1120 "The hook is analogous to @samp{TARGET_SCHED_INIT_DFA_PRE_CYCLE_INSN} but\n\
1121 used to initialize data used by the previous hook.",
1122 void, (void), NULL)
1124 DEFHOOK
1125 (dfa_post_cycle_insn,
1126 "The hook is analogous to @samp{TARGET_SCHED_DFA_PRE_CYCLE_INSN} but used\n\
1127 to changed the state as if the insn were scheduled when the new\n\
1128 simulated processor cycle finishes.",
1129 rtx_insn *, (void), NULL)
1131 /* The values of the following two members are pointers to
1132 functions used to simplify the automaton descriptions.
1133 dfa_pre_advance_cycle and dfa_post_advance_cycle are getting called
1134 immediately before and after cycle is advanced. */
1136 DEFHOOK
1137 (dfa_pre_advance_cycle,
1138 "The hook to notify target that the current simulated cycle is about to finish.\n\
1139 The hook is analogous to @samp{TARGET_SCHED_DFA_PRE_CYCLE_INSN} but used\n\
1140 to change the state in more complicated situations - e.g., when advancing\n\
1141 state on a single insn is not enough.",
1142 void, (void), NULL)
1144 DEFHOOK
1145 (dfa_post_advance_cycle,
1146 "The hook to notify target that new simulated cycle has just started.\n\
1147 The hook is analogous to @samp{TARGET_SCHED_DFA_POST_CYCLE_INSN} but used\n\
1148 to change the state in more complicated situations - e.g., when advancing\n\
1149 state on a single insn is not enough.",
1150 void, (void), NULL)
1152 /* The following member value is a pointer to a function returning value
1153 which defines how many insns in queue `ready' will we try for
1154 multi-pass scheduling. If the member value is nonzero and the
1155 function returns positive value, the DFA based scheduler will make
1156 multi-pass scheduling for the first cycle. In other words, we will
1157 try to choose ready insn which permits to start maximum number of
1158 insns on the same cycle. */
1159 DEFHOOK
1160 (first_cycle_multipass_dfa_lookahead,
1161 "This hook controls better choosing an insn from the ready insn queue\n\
1162 for the @acronym{DFA}-based insn scheduler. Usually the scheduler\n\
1163 chooses the first insn from the queue. If the hook returns a positive\n\
1164 value, an additional scheduler code tries all permutations of\n\
1165 @samp{TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD ()}\n\
1166 subsequent ready insns to choose an insn whose issue will result in\n\
1167 maximal number of issued insns on the same cycle. For the\n\
1168 @acronym{VLIW} processor, the code could actually solve the problem of\n\
1169 packing simple insns into the @acronym{VLIW} insn. Of course, if the\n\
1170 rules of @acronym{VLIW} packing are described in the automaton.\n\
1172 This code also could be used for superscalar @acronym{RISC}\n\
1173 processors. Let us consider a superscalar @acronym{RISC} processor\n\
1174 with 3 pipelines. Some insns can be executed in pipelines @var{A} or\n\
1175 @var{B}, some insns can be executed only in pipelines @var{B} or\n\
1176 @var{C}, and one insn can be executed in pipeline @var{B}. The\n\
1177 processor may issue the 1st insn into @var{A} and the 2nd one into\n\
1178 @var{B}. In this case, the 3rd insn will wait for freeing @var{B}\n\
1179 until the next cycle. If the scheduler issues the 3rd insn the first,\n\
1180 the processor could issue all 3 insns per cycle.\n\
1182 Actually this code demonstrates advantages of the automaton based\n\
1183 pipeline hazard recognizer. We try quickly and easy many insn\n\
1184 schedules to choose the best one.\n\
1186 The default is no multipass scheduling.",
1187 int, (void), NULL)
1189 /* The following member value is pointer to a function controlling
1190 what insns from the ready insn queue will be considered for the
1191 multipass insn scheduling. If the hook returns zero for insn
1192 passed as the parameter, the insn will be not chosen to be issued. */
1193 DEFHOOK
1194 (first_cycle_multipass_dfa_lookahead_guard,
1195 "\n\
1196 This hook controls what insns from the ready insn queue will be\n\
1197 considered for the multipass insn scheduling. If the hook returns\n\
1198 zero for @var{insn}, the insn will be considered in multipass scheduling.\n\
1199 Positive return values will remove @var{insn} from consideration on\n\
1200 the current round of multipass scheduling.\n\
1201 Negative return values will remove @var{insn} from consideration for given\n\
1202 number of cycles.\n\
1203 Backends should be careful about returning non-zero for highest priority\n\
1204 instruction at position 0 in the ready list. @var{ready_index} is passed\n\
1205 to allow backends make correct judgements.\n\
1207 The default is that any ready insns can be chosen to be issued.",
1208 int, (rtx_insn *insn, int ready_index), NULL)
1210 /* This hook prepares the target for a new round of multipass
1211 scheduling.
1212 DATA is a pointer to target-specific data used for multipass scheduling.
1213 READY_TRY and N_READY represent the current state of search in the
1214 optimization space. The target can filter out instructions that
1215 should not be tried during current round by setting corresponding
1216 elements in READY_TRY to non-zero.
1217 FIRST_CYCLE_INSN_P is true if this is the first round of multipass
1218 scheduling on current cycle. */
1219 DEFHOOK
1220 (first_cycle_multipass_begin,
1221 "This hook prepares the target backend for a new round of multipass\n\
1222 scheduling.",
1223 void, (void *data, signed char *ready_try, int n_ready, bool first_cycle_insn_p),
1224 NULL)
1226 /* This hook is called when multipass scheduling evaluates instruction INSN.
1227 DATA is a pointer to target-specific data that can be used to record effects
1228 of INSN on CPU that are not described in DFA.
1229 READY_TRY and N_READY represent the current state of search in the
1230 optimization space. The target can filter out instructions that
1231 should not be tried after issuing INSN by setting corresponding
1232 elements in READY_TRY to non-zero.
1233 INSN is the instruction being evaluated.
1234 PREV_DATA is a pointer to target-specific data corresponding
1235 to a state before issuing INSN. */
1236 DEFHOOK
1237 (first_cycle_multipass_issue,
1238 "This hook is called when multipass scheduling evaluates instruction INSN.",
1239 void, (void *data, signed char *ready_try, int n_ready, rtx_insn *insn,
1240 const void *prev_data), NULL)
1242 /* This hook is called when multipass scheduling backtracks from evaluation of
1243 instruction corresponding to DATA.
1244 DATA is a pointer to target-specific data that stores the effects
1245 of instruction from which the algorithm backtracks on CPU that are not
1246 described in DFA.
1247 READY_TRY and N_READY represent the current state of search in the
1248 optimization space. The target can filter out instructions that
1249 should not be tried after issuing INSN by setting corresponding
1250 elements in READY_TRY to non-zero. */
1251 DEFHOOK
1252 (first_cycle_multipass_backtrack,
1253 "This is called when multipass scheduling backtracks from evaluation of\n\
1254 an instruction.",
1255 void, (const void *data, signed char *ready_try, int n_ready), NULL)
1257 /* This hook notifies the target about the result of the concluded current
1258 round of multipass scheduling.
1259 DATA is a pointer.
1260 If DATA is non-NULL it points to target-specific data used for multipass
1261 scheduling which corresponds to instruction at the start of the chain of
1262 the winning solution. DATA is NULL when multipass scheduling cannot find
1263 a good enough solution on current cycle and decides to retry later,
1264 usually after advancing the cycle count. */
1265 DEFHOOK
1266 (first_cycle_multipass_end,
1267 "This hook notifies the target about the result of the concluded current\n\
1268 round of multipass scheduling.",
1269 void, (const void *data), NULL)
1271 /* This hook is called to initialize target-specific data for multipass
1272 scheduling after it has been allocated.
1273 DATA is a pointer to target-specific data that stores the effects
1274 of instruction from which the algorithm backtracks on CPU that are not
1275 described in DFA. */
1276 DEFHOOK
1277 (first_cycle_multipass_init,
1278 "This hook initializes target-specific data used in multipass scheduling.",
1279 void, (void *data), NULL)
1281 /* This hook is called to finalize target-specific data for multipass
1282 scheduling before it is deallocated.
1283 DATA is a pointer to target-specific data that stores the effects
1284 of instruction from which the algorithm backtracks on CPU that are not
1285 described in DFA. */
1286 DEFHOOK
1287 (first_cycle_multipass_fini,
1288 "This hook finalizes target-specific data used in multipass scheduling.",
1289 void, (void *data), NULL)
1291 /* The following member value is pointer to a function called by
1292 the insn scheduler before issuing insn passed as the third
1293 parameter on given cycle. If the hook returns nonzero, the
1294 insn is not issued on given processors cycle. Instead of that,
1295 the processor cycle is advanced. If the value passed through
1296 the last parameter is zero, the insn ready queue is not sorted
1297 on the new cycle start as usually. The first parameter passes
1298 file for debugging output. The second one passes the scheduler
1299 verbose level of the debugging output. The forth and the fifth
1300 parameter values are correspondingly processor cycle on which
1301 the previous insn has been issued and the current processor cycle. */
1302 DEFHOOK
1303 (dfa_new_cycle,
1304 "This hook is called by the insn scheduler before issuing @var{insn}\n\
1305 on cycle @var{clock}. If the hook returns nonzero,\n\
1306 @var{insn} is not issued on this processor cycle. Instead,\n\
1307 the processor cycle is advanced. If *@var{sort_p}\n\
1308 is zero, the insn ready queue is not sorted on the new cycle\n\
1309 start as usually. @var{dump} and @var{verbose} specify the file and\n\
1310 verbosity level to use for debugging output.\n\
1311 @var{last_clock} and @var{clock} are, respectively, the\n\
1312 processor cycle on which the previous insn has been issued,\n\
1313 and the current processor cycle.",
1314 int, (FILE *dump, int verbose, rtx_insn *insn, int last_clock,
1315 int clock, int *sort_p),
1316 NULL)
1318 /* The following member value is a pointer to a function called by the
1319 insn scheduler. It should return true if there exists a dependence
1320 which is considered costly by the target, between the insn
1321 DEP_PRO (&_DEP), and the insn DEP_CON (&_DEP). The first parameter is
1322 the dep that represents the dependence between the two insns. The
1323 second argument is the cost of the dependence as estimated by
1324 the scheduler. The last argument is the distance in cycles
1325 between the already scheduled insn (first parameter) and the
1326 second insn (second parameter). */
1327 DEFHOOK
1328 (is_costly_dependence,
1329 "This hook is used to define which dependences are considered costly by\n\
1330 the target, so costly that it is not advisable to schedule the insns that\n\
1331 are involved in the dependence too close to one another. The parameters\n\
1332 to this hook are as follows: The first parameter @var{_dep} is the dependence\n\
1333 being evaluated. The second parameter @var{cost} is the cost of the\n\
1334 dependence as estimated by the scheduler, and the third\n\
1335 parameter @var{distance} is the distance in cycles between the two insns.\n\
1336 The hook returns @code{true} if considering the distance between the two\n\
1337 insns the dependence between them is considered costly by the target,\n\
1338 and @code{false} otherwise.\n\
1340 Defining this hook can be useful in multiple-issue out-of-order machines,\n\
1341 where (a) it's practically hopeless to predict the actual data/resource\n\
1342 delays, however: (b) there's a better chance to predict the actual grouping\n\
1343 that will be formed, and (c) correctly emulating the grouping can be very\n\
1344 important. In such targets one may want to allow issuing dependent insns\n\
1345 closer to one another---i.e., closer than the dependence distance; however,\n\
1346 not in cases of ``costly dependences'', which this hooks allows to define.",
1347 bool, (struct _dep *_dep, int cost, int distance), NULL)
1349 /* The following member value is a pointer to a function called
1350 by the insn scheduler. This hook is called to notify the backend
1351 that new instructions were emitted. */
1352 DEFHOOK
1353 (h_i_d_extended,
1354 "This hook is called by the insn scheduler after emitting a new instruction to\n\
1355 the instruction stream. The hook notifies a target backend to extend its\n\
1356 per instruction data structures.",
1357 void, (void), NULL)
1359 /* Next 5 functions are for multi-point scheduling. */
1361 /* Allocate memory for scheduler context. */
1362 DEFHOOK
1363 (alloc_sched_context,
1364 "Return a pointer to a store large enough to hold target scheduling context.",
1365 void *, (void), NULL)
1367 /* Fills the context from the local machine scheduler context. */
1368 DEFHOOK
1369 (init_sched_context,
1370 "Initialize store pointed to by @var{tc} to hold target scheduling context.\n\
1371 It @var{clean_p} is true then initialize @var{tc} as if scheduler is at the\n\
1372 beginning of the block. Otherwise, copy the current context into @var{tc}.",
1373 void, (void *tc, bool clean_p), NULL)
1375 /* Sets local machine scheduler context to a saved value. */
1376 DEFHOOK
1377 (set_sched_context,
1378 "Copy target scheduling context pointed to by @var{tc} to the current context.",
1379 void, (void *tc), NULL)
1381 /* Clears a scheduler context so it becomes like after init. */
1382 DEFHOOK
1383 (clear_sched_context,
1384 "Deallocate internal data in target scheduling context pointed to by @var{tc}.",
1385 void, (void *tc), NULL)
1387 /* Frees the scheduler context. */
1388 DEFHOOK
1389 (free_sched_context,
1390 "Deallocate a store for target scheduling context pointed to by @var{tc}.",
1391 void, (void *tc), NULL)
1393 /* The following member value is a pointer to a function called
1394 by the insn scheduler.
1395 The first parameter is an instruction, the second parameter is the type
1396 of the requested speculation, and the third parameter is a pointer to the
1397 speculative pattern of the corresponding type (set if return value == 1).
1398 It should return
1399 -1, if there is no pattern, that will satisfy the requested speculation type,
1400 0, if current pattern satisfies the requested speculation type,
1401 1, if pattern of the instruction should be changed to the newly
1402 generated one. */
1403 DEFHOOK
1404 (speculate_insn,
1405 "This hook is called by the insn scheduler when @var{insn} has only\n\
1406 speculative dependencies and therefore can be scheduled speculatively.\n\
1407 The hook is used to check if the pattern of @var{insn} has a speculative\n\
1408 version and, in case of successful check, to generate that speculative\n\
1409 pattern. The hook should return 1, if the instruction has a speculative form,\n\
1410 or @minus{}1, if it doesn't. @var{request} describes the type of requested\n\
1411 speculation. If the return value equals 1 then @var{new_pat} is assigned\n\
1412 the generated speculative pattern.",
1413 int, (rtx_insn *insn, unsigned int dep_status, rtx *new_pat), NULL)
1415 /* The following member value is a pointer to a function called
1416 by the insn scheduler. It should return true if the check instruction
1417 passed as the parameter needs a recovery block. */
1418 DEFHOOK
1419 (needs_block_p,
1420 "This hook is called by the insn scheduler during generation of recovery code\n\
1421 for @var{insn}. It should return @code{true}, if the corresponding check\n\
1422 instruction should branch to recovery code, or @code{false} otherwise.",
1423 bool, (unsigned int dep_status), NULL)
1425 /* The following member value is a pointer to a function called
1426 by the insn scheduler. It should return a pattern for the check
1427 instruction.
1428 The first parameter is a speculative instruction, the second parameter
1429 is the label of the corresponding recovery block (or null, if it is a
1430 simple check). The third parameter is the kind of speculation that
1431 is being performed. */
1432 DEFHOOK
1433 (gen_spec_check,
1434 "This hook is called by the insn scheduler to generate a pattern for recovery\n\
1435 check instruction. If @var{mutate_p} is zero, then @var{insn} is a\n\
1436 speculative instruction for which the check should be generated.\n\
1437 @var{label} is either a label of a basic block, where recovery code should\n\
1438 be emitted, or a null pointer, when requested check doesn't branch to\n\
1439 recovery code (a simple check). If @var{mutate_p} is nonzero, then\n\
1440 a pattern for a branchy check corresponding to a simple check denoted by\n\
1441 @var{insn} should be generated. In this case @var{label} can't be null.",
1442 rtx, (rtx_insn *insn, rtx_insn *label, unsigned int ds), NULL)
1444 /* The following member value is a pointer to a function that provides
1445 information about the speculation capabilities of the target.
1446 The parameter is a pointer to spec_info variable. */
1447 DEFHOOK
1448 (set_sched_flags,
1449 "This hook is used by the insn scheduler to find out what features should be\n\
1450 enabled/used.\n\
1451 The structure *@var{spec_info} should be filled in by the target.\n\
1452 The structure describes speculation types that can be used in the scheduler.",
1453 void, (struct spec_info_def *spec_info), NULL)
1455 DEFHOOK_UNDOC
1456 (get_insn_spec_ds,
1457 "Return speculation types of instruction @var{insn}.",
1458 unsigned int, (rtx_insn *insn), NULL)
1460 DEFHOOK_UNDOC
1461 (get_insn_checked_ds,
1462 "Return speculation types that are checked for instruction @var{insn}",
1463 unsigned int, (rtx_insn *insn), NULL)
1465 DEFHOOK
1466 (can_speculate_insn,
1467 "Some instructions should never be speculated by the schedulers, usually\n\
1468 because the instruction is too expensive to get this wrong. Often such\n\
1469 instructions have long latency, and often they are not fully modeled in the\n\
1470 pipeline descriptions. This hook should return @code{false} if @var{insn}\n\
1471 should not be speculated.",
1472 bool, (rtx_insn *insn), hook_bool_rtx_insn_true)
1474 DEFHOOK_UNDOC
1475 (skip_rtx_p,
1476 "Return bool if rtx scanning should just skip current layer and\
1477 advance to the inner rtxes.",
1478 bool, (const_rtx x), NULL)
1480 /* The following member value is a pointer to a function that provides
1481 information about the target resource-based lower bound which is
1482 used by the swing modulo scheduler. The parameter is a pointer
1483 to ddg variable. */
1484 DEFHOOK
1485 (sms_res_mii,
1486 "This hook is called by the swing modulo scheduler to calculate a\n\
1487 resource-based lower bound which is based on the resources available in\n\
1488 the machine and the resources required by each instruction. The target\n\
1489 backend can use @var{g} to calculate such bound. A very simple lower\n\
1490 bound will be used in case this hook is not implemented: the total number\n\
1491 of instructions divided by the issue rate.",
1492 int, (struct ddg *g), NULL)
1494 /* The following member value is a function that initializes dispatch
1495 schedling and adds instructions to dispatch window according to its
1496 parameters. */
1497 DEFHOOK
1498 (dispatch_do,
1499 "This hook is called by Haifa Scheduler. It performs the operation specified\n\
1500 in its second parameter.",
1501 void, (rtx_insn *insn, int x),
1502 hook_void_rtx_insn_int)
1504 /* The following member value is a a function that returns true is
1505 dispatch schedling is supported in hardware and condition passed
1506 as the second parameter is true. */
1507 DEFHOOK
1508 (dispatch,
1509 "This hook is called by Haifa Scheduler. It returns true if dispatch scheduling\n\
1510 is supported in hardware and the condition specified in the parameter is true.",
1511 bool, (rtx_insn *insn, int x),
1512 hook_bool_rtx_insn_int_false)
1514 DEFHOOKPOD
1515 (exposed_pipeline,
1516 "True if the processor has an exposed pipeline, which means that not just\n\
1517 the order of instructions is important for correctness when scheduling, but\n\
1518 also the latencies of operations.",
1519 bool, false)
1521 /* The following member value is a function that returns number
1522 of operations reassociator should try to put in parallel for
1523 statements of the given type. By default 1 is used. */
1524 DEFHOOK
1525 (reassociation_width,
1526 "This hook is called by tree reassociator to determine a level of\n\
1527 parallelism required in output calculations chain.",
1528 int, (unsigned int opc, machine_mode mode),
1529 hook_int_uint_mode_1)
1531 /* The following member value is a function that returns priority for
1532 fusion of each instruction via pointer parameters. */
1533 DEFHOOK
1534 (fusion_priority,
1535 "This hook is called by scheduling fusion pass. It calculates fusion\n\
1536 priorities for each instruction passed in by parameter. The priorities\n\
1537 are returned via pointer parameters.\n\
1539 @var{insn} is the instruction whose priorities need to be calculated.\n\
1540 @var{max_pri} is the maximum priority can be returned in any cases.\n\
1541 @var{fusion_pri} is the pointer parameter through which @var{insn}'s\n\
1542 fusion priority should be calculated and returned.\n\
1543 @var{pri} is the pointer parameter through which @var{insn}'s priority\n\
1544 should be calculated and returned.\n\
1546 Same @var{fusion_pri} should be returned for instructions which should\n\
1547 be scheduled together. Different @var{pri} should be returned for\n\
1548 instructions with same @var{fusion_pri}. @var{fusion_pri} is the major\n\
1549 sort key, @var{pri} is the minor sort key. All instructions will be\n\
1550 scheduled according to the two priorities. All priorities calculated\n\
1551 should be between 0 (exclusive) and @var{max_pri} (inclusive). To avoid\n\
1552 false dependencies, @var{fusion_pri} of instructions which need to be\n\
1553 scheduled together should be smaller than @var{fusion_pri} of irrelevant\n\
1554 instructions.\n\
1556 Given below example:\n\
1558 @smallexample\n\
1559 ldr r10, [r1, 4]\n\
1560 add r4, r4, r10\n\
1561 ldr r15, [r2, 8]\n\
1562 sub r5, r5, r15\n\
1563 ldr r11, [r1, 0]\n\
1564 add r4, r4, r11\n\
1565 ldr r16, [r2, 12]\n\
1566 sub r5, r5, r16\n\
1567 @end smallexample\n\
1569 On targets like ARM/AArch64, the two pairs of consecutive loads should be\n\
1570 merged. Since peephole2 pass can't help in this case unless consecutive\n\
1571 loads are actually next to each other in instruction flow. That's where\n\
1572 this scheduling fusion pass works. This hook calculates priority for each\n\
1573 instruction based on its fustion type, like:\n\
1575 @smallexample\n\
1576 ldr r10, [r1, 4] ; fusion_pri=99, pri=96\n\
1577 add r4, r4, r10 ; fusion_pri=100, pri=100\n\
1578 ldr r15, [r2, 8] ; fusion_pri=98, pri=92\n\
1579 sub r5, r5, r15 ; fusion_pri=100, pri=100\n\
1580 ldr r11, [r1, 0] ; fusion_pri=99, pri=100\n\
1581 add r4, r4, r11 ; fusion_pri=100, pri=100\n\
1582 ldr r16, [r2, 12] ; fusion_pri=98, pri=88\n\
1583 sub r5, r5, r16 ; fusion_pri=100, pri=100\n\
1584 @end smallexample\n\
1586 Scheduling fusion pass then sorts all ready to issue instructions according\n\
1587 to the priorities. As a result, instructions of same fusion type will be\n\
1588 pushed together in instruction flow, like:\n\
1590 @smallexample\n\
1591 ldr r11, [r1, 0]\n\
1592 ldr r10, [r1, 4]\n\
1593 ldr r15, [r2, 8]\n\
1594 ldr r16, [r2, 12]\n\
1595 add r4, r4, r10\n\
1596 sub r5, r5, r15\n\
1597 add r4, r4, r11\n\
1598 sub r5, r5, r16\n\
1599 @end smallexample\n\
1601 Now peephole2 pass can simply merge the two pairs of loads.\n\
1603 Since scheduling fusion pass relies on peephole2 to do real fusion\n\
1604 work, it is only enabled by default when peephole2 is in effect.\n\
1606 This is firstly introduced on ARM/AArch64 targets, please refer to\n\
1607 the hook implementation for how different fusion types are supported.",
1608 void, (rtx_insn *insn, int max_pri, int *fusion_pri, int *pri), NULL)
1610 HOOK_VECTOR_END (sched)
1612 /* Functions relating to OpenMP SIMD and __attribute__((simd)) clones. */
1613 #undef HOOK_PREFIX
1614 #define HOOK_PREFIX "TARGET_SIMD_CLONE_"
1615 HOOK_VECTOR (TARGET_SIMD_CLONE, simd_clone)
1617 DEFHOOK
1618 (compute_vecsize_and_simdlen,
1619 "This hook should set @var{vecsize_mangle}, @var{vecsize_int}, @var{vecsize_float}\n\
1620 fields in @var{simd_clone} structure pointed by @var{clone_info} argument and also\n\
1621 @var{simdlen} field if it was previously 0.\n\
1622 The hook should return 0 if SIMD clones shouldn't be emitted,\n\
1623 or number of @var{vecsize_mangle} variants that should be emitted.",
1624 int, (struct cgraph_node *, struct cgraph_simd_clone *, tree, int), NULL)
1626 DEFHOOK
1627 (adjust,
1628 "This hook should add implicit @code{attribute(target(\"...\"))} attribute\n\
1629 to SIMD clone @var{node} if needed.",
1630 void, (struct cgraph_node *), NULL)
1632 DEFHOOK
1633 (usable,
1634 "This hook should return -1 if SIMD clone @var{node} shouldn't be used\n\
1635 in vectorized loops in current function, or non-negative number if it is\n\
1636 usable. In that case, the smaller the number is, the more desirable it is\n\
1637 to use it.",
1638 int, (struct cgraph_node *), NULL)
1640 HOOK_VECTOR_END (simd_clone)
1642 /* Functions relating to OpenMP SIMT vectorization transform. */
1643 #undef HOOK_PREFIX
1644 #define HOOK_PREFIX "TARGET_SIMT_"
1645 HOOK_VECTOR (TARGET_SIMT, simt)
1647 DEFHOOK
1648 (vf,
1649 "Return number of threads in SIMT thread group on the target.",
1650 int, (void), NULL)
1652 HOOK_VECTOR_END (simt)
1654 /* Functions relating to openacc. */
1655 #undef HOOK_PREFIX
1656 #define HOOK_PREFIX "TARGET_GOACC_"
1657 HOOK_VECTOR (TARGET_GOACC, goacc)
1659 DEFHOOK
1660 (validate_dims,
1661 "This hook should check the launch dimensions provided for an OpenACC\n\
1662 compute region, or routine. Defaulted values are represented as -1\n\
1663 and non-constant values as 0. The @var{fn_level} is negative for the\n\
1664 function corresponding to the compute region. For a routine is is the\n\
1665 outermost level at which partitioned execution may be spawned. The hook\n\
1666 should verify non-default values. If DECL is NULL, global defaults\n\
1667 are being validated and unspecified defaults should be filled in.\n\
1668 Diagnostics should be issued as appropriate. Return\n\
1669 true, if changes have been made. You must override this hook to\n\
1670 provide dimensions larger than 1.",
1671 bool, (tree decl, int *dims, int fn_level),
1672 default_goacc_validate_dims)
1674 DEFHOOK
1675 (dim_limit,
1676 "This hook should return the maximum size of a particular dimension,\n\
1677 or zero if unbounded.",
1678 int, (int axis),
1679 default_goacc_dim_limit)
1681 DEFHOOK
1682 (fork_join,
1683 "This hook can be used to convert IFN_GOACC_FORK and IFN_GOACC_JOIN\n\
1684 function calls to target-specific gimple, or indicate whether they\n\
1685 should be retained. It is executed during the oacc_device_lower pass.\n\
1686 It should return true, if the call should be retained. It should\n\
1687 return false, if it is to be deleted (either because target-specific\n\
1688 gimple has been inserted before it, or there is no need for it).\n\
1689 The default hook returns false, if there are no RTL expanders for them.",
1690 bool, (gcall *call, const int *dims, bool is_fork),
1691 default_goacc_fork_join)
1693 DEFHOOK
1694 (reduction,
1695 "This hook is used by the oacc_transform pass to expand calls to the\n\
1696 @var{GOACC_REDUCTION} internal function, into a sequence of gimple\n\
1697 instructions. @var{call} is gimple statement containing the call to\n\
1698 the function. This hook removes statement @var{call} after the\n\
1699 expanded sequence has been inserted. This hook is also responsible\n\
1700 for allocating any storage for reductions when necessary.",
1701 void, (gcall *call),
1702 default_goacc_reduction)
1704 HOOK_VECTOR_END (goacc)
1706 /* Functions relating to vectorization. */
1707 #undef HOOK_PREFIX
1708 #define HOOK_PREFIX "TARGET_VECTORIZE_"
1709 HOOK_VECTOR (TARGET_VECTORIZE, vectorize)
1711 /* The following member value is a pointer to a function called
1712 by the vectorizer, and return the decl of the target builtin
1713 function. */
1714 DEFHOOK
1715 (builtin_mask_for_load,
1716 "This hook should return the DECL of a function @var{f} that given an\n\
1717 address @var{addr} as an argument returns a mask @var{m} that can be\n\
1718 used to extract from two vectors the relevant data that resides in\n\
1719 @var{addr} in case @var{addr} is not properly aligned.\n\
1721 The autovectorizer, when vectorizing a load operation from an address\n\
1722 @var{addr} that may be unaligned, will generate two vector loads from\n\
1723 the two aligned addresses around @var{addr}. It then generates a\n\
1724 @code{REALIGN_LOAD} operation to extract the relevant data from the\n\
1725 two loaded vectors. The first two arguments to @code{REALIGN_LOAD},\n\
1726 @var{v1} and @var{v2}, are the two vectors, each of size @var{VS}, and\n\
1727 the third argument, @var{OFF}, defines how the data will be extracted\n\
1728 from these two vectors: if @var{OFF} is 0, then the returned vector is\n\
1729 @var{v2}; otherwise, the returned vector is composed from the last\n\
1730 @var{VS}-@var{OFF} elements of @var{v1} concatenated to the first\n\
1731 @var{OFF} elements of @var{v2}.\n\
1733 If this hook is defined, the autovectorizer will generate a call\n\
1734 to @var{f} (using the DECL tree that this hook returns) and will\n\
1735 use the return value of @var{f} as the argument @var{OFF} to\n\
1736 @code{REALIGN_LOAD}. Therefore, the mask @var{m} returned by @var{f}\n\
1737 should comply with the semantics expected by @code{REALIGN_LOAD}\n\
1738 described above.\n\
1739 If this hook is not defined, then @var{addr} will be used as\n\
1740 the argument @var{OFF} to @code{REALIGN_LOAD}, in which case the low\n\
1741 log2(@var{VS}) @minus{} 1 bits of @var{addr} will be considered.",
1742 tree, (void), NULL)
1744 /* Returns a built-in function that realizes the vectorized version of
1745 a target-independent function, or NULL_TREE if not available. */
1746 DEFHOOK
1747 (builtin_vectorized_function,
1748 "This hook should return the decl of a function that implements the\n\
1749 vectorized variant of the function with the @code{combined_fn} code\n\
1750 @var{code} or @code{NULL_TREE} if such a function is not available.\n\
1751 The return type of the vectorized function shall be of vector type\n\
1752 @var{vec_type_out} and the argument types should be @var{vec_type_in}.",
1753 tree, (unsigned code, tree vec_type_out, tree vec_type_in),
1754 default_builtin_vectorized_function)
1756 /* Returns a built-in function that realizes the vectorized version of
1757 a target-specific function, or NULL_TREE if not available. */
1758 DEFHOOK
1759 (builtin_md_vectorized_function,
1760 "This hook should return the decl of a function that implements the\n\
1761 vectorized variant of target built-in function @code{fndecl}. The\n\
1762 return type of the vectorized function shall be of vector type\n\
1763 @var{vec_type_out} and the argument types should be @var{vec_type_in}.",
1764 tree, (tree fndecl, tree vec_type_out, tree vec_type_in),
1765 default_builtin_md_vectorized_function)
1767 /* Returns a function declaration for a builtin that realizes the
1768 vector conversion, or NULL_TREE if not available. */
1769 DEFHOOK
1770 (builtin_conversion,
1771 "This hook should return the DECL of a function that implements conversion of the\n\
1772 input vector of type @var{src_type} to type @var{dest_type}.\n\
1773 The value of @var{code} is one of the enumerators in @code{enum tree_code} and\n\
1774 specifies how the conversion is to be applied\n\
1775 (truncation, rounding, etc.).\n\
1777 If this hook is defined, the autovectorizer will use the\n\
1778 @code{TARGET_VECTORIZE_BUILTIN_CONVERSION} target hook when vectorizing\n\
1779 conversion. Otherwise, it will return @code{NULL_TREE}.",
1780 tree, (unsigned code, tree dest_type, tree src_type),
1781 default_builtin_vectorized_conversion)
1783 /* Cost of different vector/scalar statements in vectorization cost
1784 model. In case of misaligned vector loads and stores the cost depends
1785 on the data type and misalignment value. */
1786 DEFHOOK
1787 (builtin_vectorization_cost,
1788 "Returns cost of different scalar or vector statements for vectorization cost model.\n\
1789 For vector memory operations the cost may depend on type (@var{vectype}) and\n\
1790 misalignment value (@var{misalign}).",
1791 int, (enum vect_cost_for_stmt type_of_cost, tree vectype, int misalign),
1792 default_builtin_vectorization_cost)
1794 DEFHOOK
1795 (preferred_vector_alignment,
1796 "This hook returns the preferred alignment in bits for accesses to\n\
1797 vectors of type @var{type} in vectorized code. This might be less than\n\
1798 or greater than the ABI-defined value returned by\n\
1799 @code{TARGET_VECTOR_ALIGNMENT}. It can be equal to the alignment of\n\
1800 a single element, in which case the vectorizer will not try to optimize\n\
1801 for alignment.\n\
1803 The default hook returns @code{TYPE_ALIGN (@var{type})}, which is\n\
1804 correct for most targets.",
1805 HOST_WIDE_INT, (const_tree type),
1806 default_preferred_vector_alignment)
1808 /* Return true if vector alignment is reachable (by peeling N
1809 iterations) for the given scalar type. */
1810 DEFHOOK
1811 (vector_alignment_reachable,
1812 "Return true if vector alignment is reachable (by peeling N iterations) for the given scalar type @var{type}. @var{is_packed} is false if the scalar access using @var{type} is known to be naturally aligned.",
1813 bool, (const_tree type, bool is_packed),
1814 default_builtin_vector_alignment_reachable)
1816 DEFHOOK
1817 (vec_perm_const,
1818 "This hook is used to test whether the target can permute up to two\n\
1819 vectors of mode @var{mode} using the permutation vector @code{sel}, and\n\
1820 also to emit such a permutation. In the former case @var{in0}, @var{in1}\n\
1821 and @var{out} are all null. In the latter case @var{in0} and @var{in1} are\n\
1822 the source vectors and @var{out} is the destination vector; all three are\n\
1823 registers of mode @var{mode}. @var{in1} is the same as @var{in0} if\n\
1824 @var{sel} describes a permutation on one vector instead of two.\n\
1826 Return true if the operation is possible, emitting instructions for it\n\
1827 if rtxes are provided.\n\
1829 @cindex @code{vec_perm@var{m}} instruction pattern\n\
1830 If the hook returns false for a mode with multibyte elements, GCC will\n\
1831 try the equivalent byte operation. If that also fails, it will try forcing\n\
1832 the selector into a register and using the @var{vec_perm@var{mode}}\n\
1833 instruction pattern. There is no need for the hook to handle these two\n\
1834 implementation approaches itself.",
1835 bool, (machine_mode mode, rtx output, rtx in0, rtx in1,
1836 const vec_perm_indices &sel),
1837 NULL)
1839 /* Return true if the target supports misaligned store/load of a
1840 specific factor denoted in the third parameter. The last parameter
1841 is true if the access is defined in a packed struct. */
1842 DEFHOOK
1843 (support_vector_misalignment,
1844 "This hook should return true if the target supports misaligned vector\n\
1845 store/load of a specific factor denoted in the @var{misalignment}\n\
1846 parameter. The vector store/load should be of machine mode @var{mode} and\n\
1847 the elements in the vectors should be of type @var{type}. @var{is_packed}\n\
1848 parameter is true if the memory access is defined in a packed struct.",
1849 bool,
1850 (machine_mode mode, const_tree type, int misalignment, bool is_packed),
1851 default_builtin_support_vector_misalignment)
1853 /* Returns the preferred mode for SIMD operations for the specified
1854 scalar mode. */
1855 DEFHOOK
1856 (preferred_simd_mode,
1857 "This hook should return the preferred mode for vectorizing scalar\n\
1858 mode @var{mode}. The default is\n\
1859 equal to @code{word_mode}, because the vectorizer can do some\n\
1860 transformations even in absence of specialized @acronym{SIMD} hardware.",
1861 machine_mode,
1862 (scalar_mode mode),
1863 default_preferred_simd_mode)
1865 /* Returns the preferred mode for splitting SIMD reductions to. */
1866 DEFHOOK
1867 (split_reduction,
1868 "This hook should return the preferred mode to split the final reduction\n\
1869 step on @var{mode} to. The reduction is then carried out reducing upper\n\
1870 against lower halves of vectors recursively until the specified mode is\n\
1871 reached. The default is @var{mode} which means no splitting.",
1872 machine_mode,
1873 (machine_mode),
1874 default_split_reduction)
1876 /* Returns a mask of vector sizes to iterate over when auto-vectorizing
1877 after processing the preferred one derived from preferred_simd_mode. */
1878 DEFHOOK
1879 (autovectorize_vector_sizes,
1880 "If the mode returned by @code{TARGET_VECTORIZE_PREFERRED_SIMD_MODE} is not\n\
1881 the only one that is worth considering, this hook should add all suitable\n\
1882 vector sizes to @var{sizes}, in order of decreasing preference. The first\n\
1883 one should be the size of @code{TARGET_VECTORIZE_PREFERRED_SIMD_MODE}.\n\
1885 The hook does not need to do anything if the vector returned by\n\
1886 @code{TARGET_VECTORIZE_PREFERRED_SIMD_MODE} is the only one relevant\n\
1887 for autovectorization. The default implementation does nothing.",
1888 void,
1889 (vector_sizes *sizes),
1890 default_autovectorize_vector_sizes)
1892 /* Function to get a target mode for a vector mask. */
1893 DEFHOOK
1894 (get_mask_mode,
1895 "A vector mask is a value that holds one boolean result for every element\n\
1896 in a vector. This hook returns the machine mode that should be used to\n\
1897 represent such a mask when the vector in question is @var{length} bytes\n\
1898 long and contains @var{nunits} elements. The hook returns an empty\n\
1899 @code{opt_machine_mode} if no such mode exists.\n\
1901 The default implementation returns the mode of an integer vector that\n\
1902 is @var{length} bytes long and that contains @var{nunits} elements,\n\
1903 if such a mode exists.",
1904 opt_machine_mode,
1905 (poly_uint64 nunits, poly_uint64 length),
1906 default_get_mask_mode)
1908 /* Function to say whether a masked operation is expensive when the
1909 mask is all zeros. */
1910 DEFHOOK
1911 (empty_mask_is_expensive,
1912 "This hook returns true if masked internal function @var{ifn} (really of\n\
1913 type @code{internal_fn}) should be considered expensive when the mask is\n\
1914 all zeros. GCC can then try to branch around the instruction instead.",
1915 bool,
1916 (unsigned ifn),
1917 default_empty_mask_is_expensive)
1919 /* Target builtin that implements vector gather operation. */
1920 DEFHOOK
1921 (builtin_gather,
1922 "Target builtin that implements vector gather operation. @var{mem_vectype}\n\
1923 is the vector type of the load and @var{index_type} is scalar type of\n\
1924 the index, scaled by @var{scale}.\n\
1925 The default is @code{NULL_TREE} which means to not vectorize gather\n\
1926 loads.",
1927 tree,
1928 (const_tree mem_vectype, const_tree index_type, int scale),
1929 NULL)
1931 /* Target builtin that implements vector scatter operation. */
1932 DEFHOOK
1933 (builtin_scatter,
1934 "Target builtin that implements vector scatter operation. @var{vectype}\n\
1935 is the vector type of the store and @var{index_type} is scalar type of\n\
1936 the index, scaled by @var{scale}.\n\
1937 The default is @code{NULL_TREE} which means to not vectorize scatter\n\
1938 stores.",
1939 tree,
1940 (const_tree vectype, const_tree index_type, int scale),
1941 NULL)
1943 /* Target function to initialize the cost model for a loop or block. */
1944 DEFHOOK
1945 (init_cost,
1946 "This hook should initialize target-specific data structures in preparation "
1947 "for modeling the costs of vectorizing a loop or basic block. The default "
1948 "allocates three unsigned integers for accumulating costs for the prologue, "
1949 "body, and epilogue of the loop or basic block. If @var{loop_info} is "
1950 "non-NULL, it identifies the loop being vectorized; otherwise a single block "
1951 "is being vectorized.",
1952 void *,
1953 (struct loop *loop_info),
1954 default_init_cost)
1956 /* Target function to record N statements of the given kind using the
1957 given vector type within the cost model data for the current loop or
1958 block. */
1959 DEFHOOK
1960 (add_stmt_cost,
1961 "This hook should update the target-specific @var{data} in response to "
1962 "adding @var{count} copies of the given @var{kind} of statement to a "
1963 "loop or basic block. The default adds the builtin vectorizer cost for "
1964 "the copies of the statement to the accumulator specified by @var{where}, "
1965 "(the prologue, body, or epilogue) and returns the amount added. The "
1966 "return value should be viewed as a tentative cost that may later be "
1967 "revised.",
1968 unsigned,
1969 (void *data, int count, enum vect_cost_for_stmt kind,
1970 struct _stmt_vec_info *stmt_info, int misalign,
1971 enum vect_cost_model_location where),
1972 default_add_stmt_cost)
1974 /* Target function to calculate the total cost of the current vectorized
1975 loop or block. */
1976 DEFHOOK
1977 (finish_cost,
1978 "This hook should complete calculations of the cost of vectorizing a loop "
1979 "or basic block based on @var{data}, and return the prologue, body, and "
1980 "epilogue costs as unsigned integers. The default returns the value of "
1981 "the three accumulators.",
1982 void,
1983 (void *data, unsigned *prologue_cost, unsigned *body_cost,
1984 unsigned *epilogue_cost),
1985 default_finish_cost)
1987 /* Function to delete target-specific cost modeling data. */
1988 DEFHOOK
1989 (destroy_cost_data,
1990 "This hook should release @var{data} and any related data structures "
1991 "allocated by TARGET_VECTORIZE_INIT_COST. The default releases the "
1992 "accumulator.",
1993 void,
1994 (void *data),
1995 default_destroy_cost_data)
1997 HOOK_VECTOR_END (vectorize)
1999 #undef HOOK_PREFIX
2000 #define HOOK_PREFIX "TARGET_"
2002 DEFHOOK
2003 (preferred_else_value,
2004 "This hook returns the target's preferred final argument for a call\n\
2005 to conditional internal function @var{ifn} (really of type\n\
2006 @code{internal_fn}). @var{type} specifies the return type of the\n\
2007 function and @var{ops} are the operands to the conditional operation,\n\
2008 of which there are @var{nops}.\n\
2010 For example, if @var{ifn} is @code{IFN_COND_ADD}, the hook returns\n\
2011 a value of type @var{type} that should be used when @samp{@var{ops}[0]}\n\
2012 and @samp{@var{ops}[1]} are conditionally added together.\n\
2014 This hook is only relevant if the target supports conditional patterns\n\
2015 like @code{cond_add@var{m}}. The default implementation returns a zero\n\
2016 constant of type @var{type}.",
2017 tree,
2018 (unsigned ifn, tree type, unsigned nops, tree *ops),
2019 default_preferred_else_value)
2021 DEFHOOK
2022 (record_offload_symbol,
2023 "Used when offloaded functions are seen in the compilation unit and no named\n\
2024 sections are available. It is called once for each symbol that must be\n\
2025 recorded in the offload function and variable table.",
2026 void, (tree),
2027 hook_void_tree)
2029 DEFHOOKPOD
2030 (absolute_biggest_alignment,
2031 "If defined, this target hook specifies the absolute biggest alignment\n\
2032 that a type or variable can have on this machine, otherwise,\n\
2033 @code{BIGGEST_ALIGNMENT} is used.",
2034 HOST_WIDE_INT, BIGGEST_ALIGNMENT)
2036 /* Allow target specific overriding of option settings after options have
2037 been changed by an attribute or pragma or when it is reset at the
2038 end of the code affected by an attribute or pragma. */
2039 DEFHOOK
2040 (override_options_after_change,
2041 "This target function is similar to the hook @code{TARGET_OPTION_OVERRIDE}\n\
2042 but is called when the optimize level is changed via an attribute or\n\
2043 pragma or when it is reset at the end of the code affected by the\n\
2044 attribute or pragma. It is not called at the beginning of compilation\n\
2045 when @code{TARGET_OPTION_OVERRIDE} is called so if you want to perform these\n\
2046 actions then, you should have @code{TARGET_OPTION_OVERRIDE} call\n\
2047 @code{TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE}.",
2048 void, (void),
2049 hook_void_void)
2051 DEFHOOK
2052 (offload_options,
2053 "Used when writing out the list of options into an LTO file. It should\n\
2054 translate any relevant target-specific options (such as the ABI in use)\n\
2055 into one of the @option{-foffload} options that exist as a common interface\n\
2056 to express such options. It should return a string containing these options,\n\
2057 separated by spaces, which the caller will free.\n",
2058 char *, (void), hook_charptr_void_null)
2060 DEFHOOK_UNDOC
2061 (eh_return_filter_mode,
2062 "Return machine mode for filter value.",
2063 scalar_int_mode, (void),
2064 default_eh_return_filter_mode)
2066 /* Return machine mode for libgcc expanded cmp instructions. */
2067 DEFHOOK
2068 (libgcc_cmp_return_mode,
2069 "This target hook should return the mode to be used for the return value\n\
2070 of compare instructions expanded to libgcc calls. If not defined\n\
2071 @code{word_mode} is returned which is the right choice for a majority of\n\
2072 targets.",
2073 scalar_int_mode, (void),
2074 default_libgcc_cmp_return_mode)
2076 /* Return machine mode for libgcc expanded shift instructions. */
2077 DEFHOOK
2078 (libgcc_shift_count_mode,
2079 "This target hook should return the mode to be used for the shift count operand\n\
2080 of shift instructions expanded to libgcc calls. If not defined\n\
2081 @code{word_mode} is returned which is the right choice for a majority of\n\
2082 targets.",
2083 scalar_int_mode, (void),
2084 default_libgcc_shift_count_mode)
2086 /* Return machine mode to be used for _Unwind_Word type. */
2087 DEFHOOK
2088 (unwind_word_mode,
2089 "Return machine mode to be used for @code{_Unwind_Word} type.\n\
2090 The default is to use @code{word_mode}.",
2091 scalar_int_mode, (void),
2092 default_unwind_word_mode)
2094 /* Given two decls, merge their attributes and return the result. */
2095 DEFHOOK
2096 (merge_decl_attributes,
2097 "Define this target hook if the merging of decl attributes needs special\n\
2098 handling. If defined, the result is a list of the combined\n\
2099 @code{DECL_ATTRIBUTES} of @var{olddecl} and @var{newdecl}.\n\
2100 @var{newdecl} is a duplicate declaration of @var{olddecl}. Examples of\n\
2101 when this is needed are when one attribute overrides another, or when an\n\
2102 attribute is nullified by a subsequent definition. This function may\n\
2103 call @code{merge_attributes} to handle machine-independent merging.\n\
2105 @findex TARGET_DLLIMPORT_DECL_ATTRIBUTES\n\
2106 If the only target-specific handling you require is @samp{dllimport}\n\
2107 for Microsoft Windows targets, you should define the macro\n\
2108 @code{TARGET_DLLIMPORT_DECL_ATTRIBUTES} to @code{1}. The compiler\n\
2109 will then define a function called\n\
2110 @code{merge_dllimport_decl_attributes} which can then be defined as\n\
2111 the expansion of @code{TARGET_MERGE_DECL_ATTRIBUTES}. You can also\n\
2112 add @code{handle_dll_attribute} in the attribute table for your port\n\
2113 to perform initial processing of the @samp{dllimport} and\n\
2114 @samp{dllexport} attributes. This is done in @file{i386/cygwin.h} and\n\
2115 @file{i386/i386.c}, for example.",
2116 tree, (tree olddecl, tree newdecl),
2117 merge_decl_attributes)
2119 /* Given two types, merge their attributes and return the result. */
2120 DEFHOOK
2121 (merge_type_attributes,
2122 "Define this target hook if the merging of type attributes needs special\n\
2123 handling. If defined, the result is a list of the combined\n\
2124 @code{TYPE_ATTRIBUTES} of @var{type1} and @var{type2}. It is assumed\n\
2125 that @code{comptypes} has already been called and returned 1. This\n\
2126 function may call @code{merge_attributes} to handle machine-independent\n\
2127 merging.",
2128 tree, (tree type1, tree type2),
2129 merge_type_attributes)
2131 /* Table of machine attributes and functions to handle them.
2132 Ignored if NULL. */
2133 DEFHOOKPOD
2134 (attribute_table,
2135 "If defined, this target hook points to an array of @samp{struct\n\
2136 attribute_spec} (defined in @file{tree-core.h}) specifying the machine\n\
2137 specific attributes for this target and some of the restrictions on the\n\
2138 entities to which these attributes are applied and the arguments they\n\
2139 take.",
2140 const struct attribute_spec *, NULL)
2142 /* Return true iff attribute NAME expects a plain identifier as its first
2143 argument. */
2144 DEFHOOK
2145 (attribute_takes_identifier_p,
2146 "If defined, this target hook is a function which returns true if the\n\
2147 machine-specific attribute named @var{name} expects an identifier\n\
2148 given as its first argument to be passed on as a plain identifier, not\n\
2149 subjected to name lookup. If this is not defined, the default is\n\
2150 false for all machine-specific attributes.",
2151 bool, (const_tree name),
2152 hook_bool_const_tree_false)
2154 /* Return zero if the attributes on TYPE1 and TYPE2 are incompatible,
2155 one if they are compatible and two if they are nearly compatible
2156 (which causes a warning to be generated). */
2157 DEFHOOK
2158 (comp_type_attributes,
2159 "If defined, this target hook is a function which returns zero if the attributes on\n\
2160 @var{type1} and @var{type2} are incompatible, one if they are compatible,\n\
2161 and two if they are nearly compatible (which causes a warning to be\n\
2162 generated). If this is not defined, machine-specific attributes are\n\
2163 supposed always to be compatible.",
2164 int, (const_tree type1, const_tree type2),
2165 hook_int_const_tree_const_tree_1)
2167 /* Assign default attributes to the newly defined TYPE. */
2168 DEFHOOK
2169 (set_default_type_attributes,
2170 "If defined, this target hook is a function which assigns default attributes to\n\
2171 the newly defined @var{type}.",
2172 void, (tree type),
2173 hook_void_tree)
2175 /* Insert attributes on the newly created DECL. */
2176 DEFHOOK
2177 (insert_attributes,
2178 "Define this target hook if you want to be able to add attributes to a decl\n\
2179 when it is being created. This is normally useful for back ends which\n\
2180 wish to implement a pragma by using the attributes which correspond to\n\
2181 the pragma's effect. The @var{node} argument is the decl which is being\n\
2182 created. The @var{attr_ptr} argument is a pointer to the attribute list\n\
2183 for this decl. The list itself should not be modified, since it may be\n\
2184 shared with other decls, but attributes may be chained on the head of\n\
2185 the list and @code{*@var{attr_ptr}} modified to point to the new\n\
2186 attributes, or a copy of the list may be made if further changes are\n\
2187 needed.",
2188 void, (tree node, tree *attr_ptr),
2189 hook_void_tree_treeptr)
2191 /* Return true if FNDECL (which has at least one machine attribute)
2192 can be inlined despite its machine attributes, false otherwise. */
2193 DEFHOOK
2194 (function_attribute_inlinable_p,
2195 "@cindex inlining\n\
2196 This target hook returns @code{true} if it is OK to inline @var{fndecl}\n\
2197 into the current function, despite its having target-specific\n\
2198 attributes, @code{false} otherwise. By default, if a function has a\n\
2199 target specific attribute attached to it, it will not be inlined.",
2200 bool, (const_tree fndecl),
2201 hook_bool_const_tree_false)
2203 /* Return true if bitfields in RECORD_TYPE should follow the
2204 Microsoft Visual C++ bitfield layout rules. */
2205 DEFHOOK
2206 (ms_bitfield_layout_p,
2207 "This target hook returns @code{true} if bit-fields in the given\n\
2208 @var{record_type} are to be laid out following the rules of Microsoft\n\
2209 Visual C/C++, namely: (i) a bit-field won't share the same storage\n\
2210 unit with the previous bit-field if their underlying types have\n\
2211 different sizes, and the bit-field will be aligned to the highest\n\
2212 alignment of the underlying types of itself and of the previous\n\
2213 bit-field; (ii) a zero-sized bit-field will affect the alignment of\n\
2214 the whole enclosing structure, even if it is unnamed; except that\n\
2215 (iii) a zero-sized bit-field will be disregarded unless it follows\n\
2216 another bit-field of nonzero size. If this hook returns @code{true},\n\
2217 other macros that control bit-field layout are ignored.\n\
2219 When a bit-field is inserted into a packed record, the whole size\n\
2220 of the underlying type is used by one or more same-size adjacent\n\
2221 bit-fields (that is, if its long:3, 32 bits is used in the record,\n\
2222 and any additional adjacent long bit-fields are packed into the same\n\
2223 chunk of 32 bits. However, if the size changes, a new field of that\n\
2224 size is allocated). In an unpacked record, this is the same as using\n\
2225 alignment, but not equivalent when packing.\n\
2227 If both MS bit-fields and @samp{__attribute__((packed))} are used,\n\
2228 the latter will take precedence. If @samp{__attribute__((packed))} is\n\
2229 used on a single field when MS bit-fields are in use, it will take\n\
2230 precedence for that field, but the alignment of the rest of the structure\n\
2231 may affect its placement.",
2232 bool, (const_tree record_type),
2233 hook_bool_const_tree_false)
2235 /* For now this is only an interface to WORDS_BIG_ENDIAN for
2236 target-independent code like the front ends, need performance testing
2237 before switching completely to the target hook. */
2238 DEFHOOK_UNDOC
2239 (words_big_endian,
2241 bool, (void),
2242 targhook_words_big_endian)
2244 /* Likewise for FLOAT_WORDS_BIG_ENDIAN. */
2245 DEFHOOK_UNDOC
2246 (float_words_big_endian,
2248 bool, (void),
2249 targhook_float_words_big_endian)
2251 DEFHOOK
2252 (float_exceptions_rounding_supported_p,
2253 "Returns true if the target supports IEEE 754 floating-point exceptions\
2254 and rounding modes, false otherwise. This is intended to relate to the\
2255 @code{float} and @code{double} types, but not necessarily @code{long double}.\
2256 By default, returns true if the @code{adddf3} instruction pattern is\
2257 available and false otherwise, on the assumption that hardware floating\
2258 point supports exceptions and rounding modes but software floating point\
2259 does not.",
2260 bool, (void),
2261 default_float_exceptions_rounding_supported_p)
2263 /* True if the target supports decimal floating point. */
2264 DEFHOOK
2265 (decimal_float_supported_p,
2266 "Returns true if the target supports decimal floating point.",
2267 bool, (void),
2268 default_decimal_float_supported_p)
2270 /* True if the target supports fixed-point. */
2271 DEFHOOK
2272 (fixed_point_supported_p,
2273 "Returns true if the target supports fixed-point arithmetic.",
2274 bool, (void),
2275 default_fixed_point_supported_p)
2277 /* Return true if anonymous bitfields affect structure alignment. */
2278 DEFHOOK
2279 (align_anon_bitfield,
2280 "When @code{PCC_BITFIELD_TYPE_MATTERS} is true this hook will determine\n\
2281 whether unnamed bitfields affect the alignment of the containing\n\
2282 structure. The hook should return true if the structure should inherit\n\
2283 the alignment requirements of an unnamed bitfield's type.",
2284 bool, (void),
2285 hook_bool_void_false)
2287 /* Return true if volatile bitfields should use the narrowest type possible.
2288 Return false if they should use the container type. */
2289 DEFHOOK
2290 (narrow_volatile_bitfield,
2291 "This target hook should return @code{true} if accesses to volatile bitfields\n\
2292 should use the narrowest mode possible. It should return @code{false} if\n\
2293 these accesses should use the bitfield container type.\n\
2295 The default is @code{false}.",
2296 bool, (void),
2297 hook_bool_void_false)
2299 /* Set up target-specific built-in functions. */
2300 DEFHOOK
2301 (init_builtins,
2302 "Define this hook if you have any machine-specific built-in functions\n\
2303 that need to be defined. It should be a function that performs the\n\
2304 necessary setup.\n\
2306 Machine specific built-in functions can be useful to expand special machine\n\
2307 instructions that would otherwise not normally be generated because\n\
2308 they have no equivalent in the source language (for example, SIMD vector\n\
2309 instructions or prefetch instructions).\n\
2311 To create a built-in function, call the function\n\
2312 @code{lang_hooks.builtin_function}\n\
2313 which is defined by the language front end. You can use any type nodes set\n\
2314 up by @code{build_common_tree_nodes};\n\
2315 only language front ends that use those two functions will call\n\
2316 @samp{TARGET_INIT_BUILTINS}.",
2317 void, (void),
2318 hook_void_void)
2320 /* Initialize (if INITIALIZE_P is true) and return the target-specific
2321 built-in function decl for CODE.
2322 Return NULL if that is not possible. Return error_mark_node if CODE
2323 is outside of the range of valid target builtin function codes. */
2324 DEFHOOK
2325 (builtin_decl,
2326 "Define this hook if you have any machine-specific built-in functions\n\
2327 that need to be defined. It should be a function that returns the\n\
2328 builtin function declaration for the builtin function code @var{code}.\n\
2329 If there is no such builtin and it cannot be initialized at this time\n\
2330 if @var{initialize_p} is true the function should return @code{NULL_TREE}.\n\
2331 If @var{code} is out of range the function should return\n\
2332 @code{error_mark_node}.",
2333 tree, (unsigned code, bool initialize_p), NULL)
2335 /* Expand a target-specific builtin. */
2336 DEFHOOK
2337 (expand_builtin,
2338 "\n\
2339 Expand a call to a machine specific built-in function that was set up by\n\
2340 @samp{TARGET_INIT_BUILTINS}. @var{exp} is the expression for the\n\
2341 function call; the result should go to @var{target} if that is\n\
2342 convenient, and have mode @var{mode} if that is convenient.\n\
2343 @var{subtarget} may be used as the target for computing one of\n\
2344 @var{exp}'s operands. @var{ignore} is nonzero if the value is to be\n\
2345 ignored. This function should return the result of the call to the\n\
2346 built-in function.",
2347 rtx,
2348 (tree exp, rtx target, rtx subtarget, machine_mode mode, int ignore),
2349 default_expand_builtin)
2351 /* Select a replacement for a target-specific builtin. This is done
2352 *before* regular type checking, and so allows the target to
2353 implement a crude form of function overloading. The result is a
2354 complete expression that implements the operation. PARAMS really
2355 has type VEC(tree,gc)*, but we don't want to include tree.h here. */
2356 DEFHOOK
2357 (resolve_overloaded_builtin,
2358 "Select a replacement for a machine specific built-in function that\n\
2359 was set up by @samp{TARGET_INIT_BUILTINS}. This is done\n\
2360 @emph{before} regular type checking, and so allows the target to\n\
2361 implement a crude form of function overloading. @var{fndecl} is the\n\
2362 declaration of the built-in function. @var{arglist} is the list of\n\
2363 arguments passed to the built-in function. The result is a\n\
2364 complete expression that implements the operation, usually\n\
2365 another @code{CALL_EXPR}.\n\
2366 @var{arglist} really has type @samp{VEC(tree,gc)*}",
2367 tree, (unsigned int /*location_t*/ loc, tree fndecl, void *arglist), NULL)
2369 /* Fold a target-specific builtin to a tree valid for both GIMPLE
2370 and GENERIC. */
2371 DEFHOOK
2372 (fold_builtin,
2373 "Fold a call to a machine specific built-in function that was set up by\n\
2374 @samp{TARGET_INIT_BUILTINS}. @var{fndecl} is the declaration of the\n\
2375 built-in function. @var{n_args} is the number of arguments passed to\n\
2376 the function; the arguments themselves are pointed to by @var{argp}.\n\
2377 The result is another tree, valid for both GIMPLE and GENERIC,\n\
2378 containing a simplified expression for the call's result. If\n\
2379 @var{ignore} is true the value will be ignored.",
2380 tree, (tree fndecl, int n_args, tree *argp, bool ignore),
2381 hook_tree_tree_int_treep_bool_null)
2383 /* Fold a target-specific builtin to a valid GIMPLE tree. */
2384 DEFHOOK
2385 (gimple_fold_builtin,
2386 "Fold a call to a machine specific built-in function that was set up\n\
2387 by @samp{TARGET_INIT_BUILTINS}. @var{gsi} points to the gimple\n\
2388 statement holding the function call. Returns true if any change\n\
2389 was made to the GIMPLE stream.",
2390 bool, (gimple_stmt_iterator *gsi),
2391 hook_bool_gsiptr_false)
2393 /* Target hook is used to compare the target attributes in two functions to
2394 determine which function's features get higher priority. This is used
2395 during function multi-versioning to figure out the order in which two
2396 versions must be dispatched. A function version with a higher priority
2397 is checked for dispatching earlier. DECL1 and DECL2 are
2398 the two function decls that will be compared. It returns positive value
2399 if DECL1 is higher priority, negative value if DECL2 is higher priority
2400 and 0 if they are the same. */
2401 DEFHOOK
2402 (compare_version_priority,
2403 "This hook is used to compare the target attributes in two functions to\n\
2404 determine which function's features get higher priority. This is used\n\
2405 during function multi-versioning to figure out the order in which two\n\
2406 versions must be dispatched. A function version with a higher priority\n\
2407 is checked for dispatching earlier. @var{decl1} and @var{decl2} are\n\
2408 the two function decls that will be compared.",
2409 int, (tree decl1, tree decl2), NULL)
2411 /* Target hook is used to generate the dispatcher logic to invoke the right
2412 function version at run-time for a given set of function versions.
2413 ARG points to the callgraph node of the dispatcher function whose body
2414 must be generated. */
2415 DEFHOOK
2416 (generate_version_dispatcher_body,
2417 "This hook is used to generate the dispatcher logic to invoke the right\n\
2418 function version at run-time for a given set of function versions.\n\
2419 @var{arg} points to the callgraph node of the dispatcher function whose\n\
2420 body must be generated.",
2421 tree, (void *arg), NULL)
2423 /* Target hook is used to get the dispatcher function for a set of function
2424 versions. The dispatcher function is called to invoke the right function
2425 version at run-time. DECL is one version from a set of semantically
2426 identical versions. */
2427 DEFHOOK
2428 (get_function_versions_dispatcher,
2429 "This hook is used to get the dispatcher function for a set of function\n\
2430 versions. The dispatcher function is called to invoke the right function\n\
2431 version at run-time. @var{decl} is one version from a set of semantically\n\
2432 identical versions.",
2433 tree, (void *decl), NULL)
2435 /* Returns a code for a target-specific builtin that implements
2436 reciprocal of a target-specific function, or NULL_TREE if not available. */
2437 DEFHOOK
2438 (builtin_reciprocal,
2439 "This hook should return the DECL of a function that implements the\n\
2440 reciprocal of the machine-specific builtin function @var{fndecl}, or\n\
2441 @code{NULL_TREE} if such a function is not available.",
2442 tree, (tree fndecl),
2443 default_builtin_reciprocal)
2445 /* For a vendor-specific TYPE, return a pointer to a statically-allocated
2446 string containing the C++ mangling for TYPE. In all other cases, return
2447 NULL. */
2448 DEFHOOK
2449 (mangle_type,
2450 "If your target defines any fundamental types, or any types your target\n\
2451 uses should be mangled differently from the default, define this hook\n\
2452 to return the appropriate encoding for these types as part of a C++\n\
2453 mangled name. The @var{type} argument is the tree structure representing\n\
2454 the type to be mangled. The hook may be applied to trees which are\n\
2455 not target-specific fundamental types; it should return @code{NULL}\n\
2456 for all such types, as well as arguments it does not recognize. If the\n\
2457 return value is not @code{NULL}, it must point to a statically-allocated\n\
2458 string constant.\n\
2460 Target-specific fundamental types might be new fundamental types or\n\
2461 qualified versions of ordinary fundamental types. Encode new\n\
2462 fundamental types as @samp{@w{u @var{n} @var{name}}}, where @var{name}\n\
2463 is the name used for the type in source code, and @var{n} is the\n\
2464 length of @var{name} in decimal. Encode qualified versions of\n\
2465 ordinary types as @samp{@w{U @var{n} @var{name} @var{code}}}, where\n\
2466 @var{name} is the name used for the type qualifier in source code,\n\
2467 @var{n} is the length of @var{name} as above, and @var{code} is the\n\
2468 code used to represent the unqualified version of this type. (See\n\
2469 @code{write_builtin_type} in @file{cp/mangle.c} for the list of\n\
2470 codes.) In both cases the spaces are for clarity; do not include any\n\
2471 spaces in your string.\n\
2473 This hook is applied to types prior to typedef resolution. If the mangled\n\
2474 name for a particular type depends only on that type's main variant, you\n\
2475 can perform typedef resolution yourself using @code{TYPE_MAIN_VARIANT}\n\
2476 before mangling.\n\
2478 The default version of this hook always returns @code{NULL}, which is\n\
2479 appropriate for a target that does not define any new fundamental\n\
2480 types.",
2481 const char *, (const_tree type),
2482 hook_constcharptr_const_tree_null)
2484 /* Make any adjustments to libfunc names needed for this target. */
2485 DEFHOOK
2486 (init_libfuncs,
2487 "This hook should declare additional library routines or rename\n\
2488 existing ones, using the functions @code{set_optab_libfunc} and\n\
2489 @code{init_one_libfunc} defined in @file{optabs.c}.\n\
2490 @code{init_optabs} calls this macro after initializing all the normal\n\
2491 library routines.\n\
2493 The default is to do nothing. Most ports don't need to define this hook.",
2494 void, (void),
2495 hook_void_void)
2497 /* Add a __gnu_ prefix to library functions rather than just __. */
2498 DEFHOOKPOD
2499 (libfunc_gnu_prefix,
2500 "If false (the default), internal library routines start with two\n\
2501 underscores. If set to true, these routines start with @code{__gnu_}\n\
2502 instead. E.g., @code{__muldi3} changes to @code{__gnu_muldi3}. This\n\
2503 currently only affects functions defined in @file{libgcc2.c}. If this\n\
2504 is set to true, the @file{tm.h} file must also\n\
2505 @code{#define LIBGCC2_GNU_PREFIX}.",
2506 bool, false)
2508 /* Given a decl, a section name, and whether the decl initializer
2509 has relocs, choose attributes for the section. */
2510 /* ??? Should be merged with SELECT_SECTION and UNIQUE_SECTION. */
2511 DEFHOOK
2512 (section_type_flags,
2513 "Choose a set of section attributes for use by @code{TARGET_ASM_NAMED_SECTION}\n\
2514 based on a variable or function decl, a section name, and whether or not the\n\
2515 declaration's initializer may contain runtime relocations. @var{decl} may be\n\
2516 null, in which case read-write data should be assumed.\n\
2518 The default version of this function handles choosing code vs data,\n\
2519 read-only vs read-write data, and @code{flag_pic}. You should only\n\
2520 need to override this if your target has special flags that might be\n\
2521 set via @code{__attribute__}.",
2522 unsigned int, (tree decl, const char *name, int reloc),
2523 default_section_type_flags)
2525 DEFHOOK
2526 (libc_has_function,
2527 "This hook determines whether a function from a class of functions\n\
2528 @var{fn_class} is present at the runtime.",
2529 bool, (enum function_class fn_class),
2530 default_libc_has_function)
2532 /* True if new jumps cannot be created, to replace existing ones or
2533 not, at the current point in the compilation. */
2534 DEFHOOK
2535 (cannot_modify_jumps_p,
2536 "This target hook returns @code{true} past the point in which new jump\n\
2537 instructions could be created. On machines that require a register for\n\
2538 every jump such as the SHmedia ISA of SH5, this point would typically be\n\
2539 reload, so this target hook should be defined to a function such as:\n\
2541 @smallexample\n\
2542 static bool\n\
2543 cannot_modify_jumps_past_reload_p ()\n\
2544 @{\n\
2545 return (reload_completed || reload_in_progress);\n\
2546 @}\n\
2547 @end smallexample",
2548 bool, (void),
2549 hook_bool_void_false)
2551 /* True if FOLLOWER may be modified to follow FOLLOWEE. */
2552 DEFHOOK
2553 (can_follow_jump,
2554 "FOLLOWER and FOLLOWEE are JUMP_INSN instructions;\
2555 return true if FOLLOWER may be modified to follow FOLLOWEE;\
2556 false, if it can't.\
2557 For example, on some targets, certain kinds of branches can't be made to\
2558 follow through a hot/cold partitioning.",
2559 bool, (const rtx_insn *follower, const rtx_insn *followee),
2560 hook_bool_const_rtx_insn_const_rtx_insn_true)
2562 /* Return a register class for which branch target register
2563 optimizations should be applied. */
2564 DEFHOOK
2565 (branch_target_register_class,
2566 "This target hook returns a register class for which branch target register\n\
2567 optimizations should be applied. All registers in this class should be\n\
2568 usable interchangeably. After reload, registers in this class will be\n\
2569 re-allocated and loads will be hoisted out of loops and be subjected\n\
2570 to inter-block scheduling.",
2571 reg_class_t, (void),
2572 default_branch_target_register_class)
2574 /* Return true if branch target register optimizations should include
2575 callee-saved registers that are not already live during the current
2576 function. AFTER_PE_GEN is true if prologues and epilogues have
2577 already been generated. */
2578 DEFHOOK
2579 (branch_target_register_callee_saved,
2580 "Branch target register optimization will by default exclude callee-saved\n\
2581 registers\n\
2582 that are not already live during the current function; if this target hook\n\
2583 returns true, they will be included. The target code must than make sure\n\
2584 that all target registers in the class returned by\n\
2585 @samp{TARGET_BRANCH_TARGET_REGISTER_CLASS} that might need saving are\n\
2586 saved. @var{after_prologue_epilogue_gen} indicates if prologues and\n\
2587 epilogues have already been generated. Note, even if you only return\n\
2588 true when @var{after_prologue_epilogue_gen} is false, you still are likely\n\
2589 to have to make special provisions in @code{INITIAL_ELIMINATION_OFFSET}\n\
2590 to reserve space for caller-saved target registers.",
2591 bool, (bool after_prologue_epilogue_gen),
2592 hook_bool_bool_false)
2594 /* Return true if the target supports conditional execution. */
2595 DEFHOOK
2596 (have_conditional_execution,
2597 "This target hook returns true if the target supports conditional execution.\n\
2598 This target hook is required only when the target has several different\n\
2599 modes and they have different conditional execution capability, such as ARM.",
2600 bool, (void),
2601 default_have_conditional_execution)
2603 DEFHOOK
2604 (gen_ccmp_first,
2605 "This function prepares to emit a comparison insn for the first compare in a\n\
2606 sequence of conditional comparisions. It returns an appropriate comparison\n\
2607 with @code{CC} for passing to @code{gen_ccmp_next} or @code{cbranch_optab}.\n\
2608 The insns to prepare the compare are saved in @var{prep_seq} and the compare\n\
2609 insns are saved in @var{gen_seq}. They will be emitted when all the\n\
2610 compares in the the conditional comparision are generated without error.\n\
2611 @var{code} is the @code{rtx_code} of the compare for @var{op0} and @var{op1}.",
2612 rtx, (rtx_insn **prep_seq, rtx_insn **gen_seq, int code, tree op0, tree op1),
2613 NULL)
2615 DEFHOOK
2616 (gen_ccmp_next,
2617 "This function prepares to emit a conditional comparison within a sequence\n\
2618 of conditional comparisons. It returns an appropriate comparison with\n\
2619 @code{CC} for passing to @code{gen_ccmp_next} or @code{cbranch_optab}.\n\
2620 The insns to prepare the compare are saved in @var{prep_seq} and the compare\n\
2621 insns are saved in @var{gen_seq}. They will be emitted when all the\n\
2622 compares in the conditional comparision are generated without error. The\n\
2623 @var{prev} expression is the result of a prior call to @code{gen_ccmp_first}\n\
2624 or @code{gen_ccmp_next}. It may return @code{NULL} if the combination of\n\
2625 @var{prev} and this comparison is not supported, otherwise the result must\n\
2626 be appropriate for passing to @code{gen_ccmp_next} or @code{cbranch_optab}.\n\
2627 @var{code} is the @code{rtx_code} of the compare for @var{op0} and @var{op1}.\n\
2628 @var{bit_code} is @code{AND} or @code{IOR}, which is the op on the compares.",
2629 rtx, (rtx_insn **prep_seq, rtx_insn **gen_seq, rtx prev, int cmp_code, tree op0, tree op1, int bit_code),
2630 NULL)
2632 /* Return a new value for loop unroll size. */
2633 DEFHOOK
2634 (loop_unroll_adjust,
2635 "This target hook returns a new value for the number of times @var{loop}\n\
2636 should be unrolled. The parameter @var{nunroll} is the number of times\n\
2637 the loop is to be unrolled. The parameter @var{loop} is a pointer to\n\
2638 the loop, which is going to be checked for unrolling. This target hook\n\
2639 is required only when the target has special constraints like maximum\n\
2640 number of memory accesses.",
2641 unsigned, (unsigned nunroll, struct loop *loop),
2642 NULL)
2644 /* True if X is a legitimate MODE-mode immediate operand. */
2645 DEFHOOK
2646 (legitimate_constant_p,
2647 "This hook returns true if @var{x} is a legitimate constant for a\n\
2648 @var{mode}-mode immediate operand on the target machine. You can assume that\n\
2649 @var{x} satisfies @code{CONSTANT_P}, so you need not check this.\n\
2651 The default definition returns true.",
2652 bool, (machine_mode mode, rtx x),
2653 hook_bool_mode_rtx_true)
2655 /* True if the constant X cannot be placed in the constant pool. */
2656 DEFHOOK
2657 (cannot_force_const_mem,
2658 "This hook should return true if @var{x} is of a form that cannot (or\n\
2659 should not) be spilled to the constant pool. @var{mode} is the mode\n\
2660 of @var{x}.\n\
2662 The default version of this hook returns false.\n\
2664 The primary reason to define this hook is to prevent reload from\n\
2665 deciding that a non-legitimate constant would be better reloaded\n\
2666 from the constant pool instead of spilling and reloading a register\n\
2667 holding the constant. This restriction is often true of addresses\n\
2668 of TLS symbols for various targets.",
2669 bool, (machine_mode mode, rtx x),
2670 hook_bool_mode_rtx_false)
2672 DEFHOOK_UNDOC
2673 (cannot_copy_insn_p,
2674 "True if the insn @var{x} cannot be duplicated.",
2675 bool, (rtx_insn *), NULL)
2677 /* True if X is considered to be commutative. */
2678 DEFHOOK
2679 (commutative_p,
2680 "This target hook returns @code{true} if @var{x} is considered to be commutative.\n\
2681 Usually, this is just COMMUTATIVE_P (@var{x}), but the HP PA doesn't consider\n\
2682 PLUS to be commutative inside a MEM@. @var{outer_code} is the rtx code\n\
2683 of the enclosing rtl, if known, otherwise it is UNKNOWN.",
2684 bool, (const_rtx x, int outer_code),
2685 hook_bool_const_rtx_commutative_p)
2687 /* True if ADDR is an address-expression whose effect depends
2688 on the mode of the memory reference it is used in. */
2689 DEFHOOK
2690 (mode_dependent_address_p,
2691 "This hook returns @code{true} if memory address @var{addr} in address\n\
2692 space @var{addrspace} can have\n\
2693 different meanings depending on the machine mode of the memory\n\
2694 reference it is used for or if the address is valid for some modes\n\
2695 but not others.\n\
2697 Autoincrement and autodecrement addresses typically have mode-dependent\n\
2698 effects because the amount of the increment or decrement is the size\n\
2699 of the operand being addressed. Some machines have other mode-dependent\n\
2700 addresses. Many RISC machines have no mode-dependent addresses.\n\
2702 You may assume that @var{addr} is a valid address for the machine.\n\
2704 The default version of this hook returns @code{false}.",
2705 bool, (const_rtx addr, addr_space_t addrspace),
2706 default_mode_dependent_address_p)
2708 /* Given an invalid address X for a given machine mode, try machine-specific
2709 ways to make it legitimate. Return X or an invalid address on failure. */
2710 DEFHOOK
2711 (legitimize_address,
2712 "This hook is given an invalid memory address @var{x} for an\n\
2713 operand of mode @var{mode} and should try to return a valid memory\n\
2714 address.\n\
2716 @findex break_out_memory_refs\n\
2717 @var{x} will always be the result of a call to @code{break_out_memory_refs},\n\
2718 and @var{oldx} will be the operand that was given to that function to produce\n\
2719 @var{x}.\n\
2721 The code of the hook should not alter the substructure of\n\
2722 @var{x}. If it transforms @var{x} into a more legitimate form, it\n\
2723 should return the new @var{x}.\n\
2725 It is not necessary for this hook to come up with a legitimate address,\n\
2726 with the exception of native TLS addresses (@pxref{Emulated TLS}).\n\
2727 The compiler has standard ways of doing so in all cases. In fact, if\n\
2728 the target supports only emulated TLS, it\n\
2729 is safe to omit this hook or make it return @var{x} if it cannot find\n\
2730 a valid way to legitimize the address. But often a machine-dependent\n\
2731 strategy can generate better code.",
2732 rtx, (rtx x, rtx oldx, machine_mode mode),
2733 default_legitimize_address)
2735 /* Given an address RTX, undo the effects of LEGITIMIZE_ADDRESS. */
2736 DEFHOOK
2737 (delegitimize_address,
2738 "This hook is used to undo the possibly obfuscating effects of the\n\
2739 @code{LEGITIMIZE_ADDRESS} and @code{LEGITIMIZE_RELOAD_ADDRESS} target\n\
2740 macros. Some backend implementations of these macros wrap symbol\n\
2741 references inside an @code{UNSPEC} rtx to represent PIC or similar\n\
2742 addressing modes. This target hook allows GCC's optimizers to understand\n\
2743 the semantics of these opaque @code{UNSPEC}s by converting them back\n\
2744 into their original form.",
2745 rtx, (rtx x),
2746 delegitimize_mem_from_attrs)
2748 /* Given an RTX, return true if it is not ok to emit it into debug info
2749 section. */
2750 DEFHOOK
2751 (const_not_ok_for_debug_p,
2752 "This hook should return true if @var{x} should not be emitted into\n\
2753 debug sections.",
2754 bool, (rtx x),
2755 default_const_not_ok_for_debug_p)
2757 /* Given an address RTX, say whether it is valid. */
2758 DEFHOOK
2759 (legitimate_address_p,
2760 "A function that returns whether @var{x} (an RTX) is a legitimate memory\n\
2761 address on the target machine for a memory operand of mode @var{mode}.\n\
2763 Legitimate addresses are defined in two variants: a strict variant and a\n\
2764 non-strict one. The @var{strict} parameter chooses which variant is\n\
2765 desired by the caller.\n\
2767 The strict variant is used in the reload pass. It must be defined so\n\
2768 that any pseudo-register that has not been allocated a hard register is\n\
2769 considered a memory reference. This is because in contexts where some\n\
2770 kind of register is required, a pseudo-register with no hard register\n\
2771 must be rejected. For non-hard registers, the strict variant should look\n\
2772 up the @code{reg_renumber} array; it should then proceed using the hard\n\
2773 register number in the array, or treat the pseudo as a memory reference\n\
2774 if the array holds @code{-1}.\n\
2776 The non-strict variant is used in other passes. It must be defined to\n\
2777 accept all pseudo-registers in every context where some kind of\n\
2778 register is required.\n\
2780 Normally, constant addresses which are the sum of a @code{symbol_ref}\n\
2781 and an integer are stored inside a @code{const} RTX to mark them as\n\
2782 constant. Therefore, there is no need to recognize such sums\n\
2783 specifically as legitimate addresses. Normally you would simply\n\
2784 recognize any @code{const} as legitimate.\n\
2786 Usually @code{PRINT_OPERAND_ADDRESS} is not prepared to handle constant\n\
2787 sums that are not marked with @code{const}. It assumes that a naked\n\
2788 @code{plus} indicates indexing. If so, then you @emph{must} reject such\n\
2789 naked constant sums as illegitimate addresses, so that none of them will\n\
2790 be given to @code{PRINT_OPERAND_ADDRESS}.\n\
2792 @cindex @code{TARGET_ENCODE_SECTION_INFO} and address validation\n\
2793 On some machines, whether a symbolic address is legitimate depends on\n\
2794 the section that the address refers to. On these machines, define the\n\
2795 target hook @code{TARGET_ENCODE_SECTION_INFO} to store the information\n\
2796 into the @code{symbol_ref}, and then check for it here. When you see a\n\
2797 @code{const}, you will have to look inside it to find the\n\
2798 @code{symbol_ref} in order to determine the section. @xref{Assembler\n\
2799 Format}.\n\
2801 @cindex @code{GO_IF_LEGITIMATE_ADDRESS}\n\
2802 Some ports are still using a deprecated legacy substitute for\n\
2803 this hook, the @code{GO_IF_LEGITIMATE_ADDRESS} macro. This macro\n\
2804 has this syntax:\n\
2806 @example\n\
2807 #define GO_IF_LEGITIMATE_ADDRESS (@var{mode}, @var{x}, @var{label})\n\
2808 @end example\n\
2810 @noindent\n\
2811 and should @code{goto @var{label}} if the address @var{x} is a valid\n\
2812 address on the target machine for a memory operand of mode @var{mode}.\n\
2814 @findex REG_OK_STRICT\n\
2815 Compiler source files that want to use the strict variant of this\n\
2816 macro define the macro @code{REG_OK_STRICT}. You should use an\n\
2817 @code{#ifdef REG_OK_STRICT} conditional to define the strict variant in\n\
2818 that case and the non-strict variant otherwise.\n\
2820 Using the hook is usually simpler because it limits the number of\n\
2821 files that are recompiled when changes are made.",
2822 bool, (machine_mode mode, rtx x, bool strict),
2823 default_legitimate_address_p)
2825 /* True if the given constant can be put into an object_block. */
2826 DEFHOOK
2827 (use_blocks_for_constant_p,
2828 "This hook should return true if pool entries for constant @var{x} can\n\
2829 be placed in an @code{object_block} structure. @var{mode} is the mode\n\
2830 of @var{x}.\n\
2832 The default version returns false for all constants.",
2833 bool, (machine_mode mode, const_rtx x),
2834 hook_bool_mode_const_rtx_false)
2836 /* True if the given decl can be put into an object_block. */
2837 DEFHOOK
2838 (use_blocks_for_decl_p,
2839 "This hook should return true if pool entries for @var{decl} should\n\
2840 be placed in an @code{object_block} structure.\n\
2842 The default version returns true for all decls.",
2843 bool, (const_tree decl),
2844 hook_bool_const_tree_true)
2846 /* The minimum and maximum byte offsets for anchored addresses. */
2847 DEFHOOKPOD
2848 (min_anchor_offset,
2849 "The minimum offset that should be applied to a section anchor.\n\
2850 On most targets, it should be the smallest offset that can be\n\
2851 applied to a base register while still giving a legitimate address\n\
2852 for every mode. The default value is 0.",
2853 HOST_WIDE_INT, 0)
2855 DEFHOOKPOD
2856 (max_anchor_offset,
2857 "Like @code{TARGET_MIN_ANCHOR_OFFSET}, but the maximum (inclusive)\n\
2858 offset that should be applied to section anchors. The default\n\
2859 value is 0.",
2860 HOST_WIDE_INT, 0)
2862 /* True if section anchors can be used to access the given symbol. */
2863 DEFHOOK
2864 (use_anchors_for_symbol_p,
2865 "Return true if GCC should attempt to use anchors to access @code{SYMBOL_REF}\n\
2866 @var{x}. You can assume @samp{SYMBOL_REF_HAS_BLOCK_INFO_P (@var{x})} and\n\
2867 @samp{!SYMBOL_REF_ANCHOR_P (@var{x})}.\n\
2869 The default version is correct for most targets, but you might need to\n\
2870 intercept this hook to handle things like target-specific attributes\n\
2871 or target-specific sections.",
2872 bool, (const_rtx x),
2873 default_use_anchors_for_symbol_p)
2875 /* True if target supports indirect functions. */
2876 DEFHOOK
2877 (has_ifunc_p,
2878 "It returns true if the target supports GNU indirect functions.\n\
2879 The support includes the assembler, linker and dynamic linker.\n\
2880 The default value of this hook is based on target's libc.",
2881 bool, (void),
2882 default_has_ifunc_p)
2884 /* True if it is OK to do sibling call optimization for the specified
2885 call expression EXP. DECL will be the called function, or NULL if
2886 this is an indirect call. */
2887 DEFHOOK
2888 (function_ok_for_sibcall,
2889 "True if it is OK to do sibling call optimization for the specified\n\
2890 call expression @var{exp}. @var{decl} will be the called function,\n\
2891 or @code{NULL} if this is an indirect call.\n\
2893 It is not uncommon for limitations of calling conventions to prevent\n\
2894 tail calls to functions outside the current unit of translation, or\n\
2895 during PIC compilation. The hook is used to enforce these restrictions,\n\
2896 as the @code{sibcall} md pattern can not fail, or fall over to a\n\
2897 ``normal'' call. The criteria for successful sibling call optimization\n\
2898 may vary greatly between different architectures.",
2899 bool, (tree decl, tree exp),
2900 hook_bool_tree_tree_false)
2902 /* Establish appropriate back-end context for processing the function
2903 FNDECL. The argument might be NULL to indicate processing at top
2904 level, outside of any function scope. */
2905 DEFHOOK
2906 (set_current_function,
2907 "The compiler invokes this hook whenever it changes its current function\n\
2908 context (@code{cfun}). You can define this function if\n\
2909 the back end needs to perform any initialization or reset actions on a\n\
2910 per-function basis. For example, it may be used to implement function\n\
2911 attributes that affect register usage or code generation patterns.\n\
2912 The argument @var{decl} is the declaration for the new function context,\n\
2913 and may be null to indicate that the compiler has left a function context\n\
2914 and is returning to processing at the top level.\n\
2915 The default hook function does nothing.\n\
2917 GCC sets @code{cfun} to a dummy function context during initialization of\n\
2918 some parts of the back end. The hook function is not invoked in this\n\
2919 situation; you need not worry about the hook being invoked recursively,\n\
2920 or when the back end is in a partially-initialized state.\n\
2921 @code{cfun} might be @code{NULL} to indicate processing at top level,\n\
2922 outside of any function scope.",
2923 void, (tree decl), hook_void_tree)
2925 /* True if EXP should be placed in a "small data" section. */
2926 DEFHOOK
2927 (in_small_data_p,
2928 "Returns true if @var{exp} should be placed into a ``small data'' section.\n\
2929 The default version of this hook always returns false.",
2930 bool, (const_tree exp),
2931 hook_bool_const_tree_false)
2933 /* True if EXP names an object for which name resolution must resolve
2934 to the current executable or shared library. */
2935 DEFHOOK
2936 (binds_local_p,
2937 "Returns true if @var{exp} names an object for which name resolution\n\
2938 rules must resolve to the current ``module'' (dynamic shared library\n\
2939 or executable image).\n\
2941 The default version of this hook implements the name resolution rules\n\
2942 for ELF, which has a looser model of global name binding than other\n\
2943 currently supported object file formats.",
2944 bool, (const_tree exp),
2945 default_binds_local_p)
2947 /* Check if profiling code is before or after prologue. */
2948 DEFHOOK
2949 (profile_before_prologue,
2950 "It returns true if target wants profile code emitted before prologue.\n\n\
2951 The default version of this hook use the target macro\n\
2952 @code{PROFILE_BEFORE_PROLOGUE}.",
2953 bool, (void),
2954 default_profile_before_prologue)
2956 /* Return true if a leaf function should stay leaf even with profiling
2957 enabled. */
2958 DEFHOOK
2959 (keep_leaf_when_profiled,
2960 "This target hook returns true if the target wants the leaf flag for\
2961 the current function to stay true even if it calls mcount. This might\
2962 make sense for targets using the leaf flag only to determine whether a\
2963 stack frame needs to be generated or not and for which the call to\
2964 mcount is generated before the function prologue.",
2965 bool, (void),
2966 default_keep_leaf_when_profiled)
2968 /* Modify and return the identifier of a DECL's external name,
2969 originally identified by ID, as required by the target,
2970 (eg, append @nn to windows32 stdcall function names).
2971 The default is to return ID without modification. */
2972 DEFHOOK
2973 (mangle_decl_assembler_name,
2974 "Define this hook if you need to postprocess the assembler name generated\n\
2975 by target-independent code. The @var{id} provided to this hook will be\n\
2976 the computed name (e.g., the macro @code{DECL_NAME} of the @var{decl} in C,\n\
2977 or the mangled name of the @var{decl} in C++). The return value of the\n\
2978 hook is an @code{IDENTIFIER_NODE} for the appropriate mangled name on\n\
2979 your target system. The default implementation of this hook just\n\
2980 returns the @var{id} provided.",
2981 tree, (tree decl, tree id),
2982 default_mangle_decl_assembler_name)
2984 /* Do something target-specific to record properties of the DECL into
2985 the associated SYMBOL_REF. */
2986 DEFHOOK
2987 (encode_section_info,
2988 "Define this hook if references to a symbol or a constant must be\n\
2989 treated differently depending on something about the variable or\n\
2990 function named by the symbol (such as what section it is in).\n\
2992 The hook is executed immediately after rtl has been created for\n\
2993 @var{decl}, which may be a variable or function declaration or\n\
2994 an entry in the constant pool. In either case, @var{rtl} is the\n\
2995 rtl in question. Do @emph{not} use @code{DECL_RTL (@var{decl})}\n\
2996 in this hook; that field may not have been initialized yet.\n\
2998 In the case of a constant, it is safe to assume that the rtl is\n\
2999 a @code{mem} whose address is a @code{symbol_ref}. Most decls\n\
3000 will also have this form, but that is not guaranteed. Global\n\
3001 register variables, for instance, will have a @code{reg} for their\n\
3002 rtl. (Normally the right thing to do with such unusual rtl is\n\
3003 leave it alone.)\n\
3005 The @var{new_decl_p} argument will be true if this is the first time\n\
3006 that @code{TARGET_ENCODE_SECTION_INFO} has been invoked on this decl. It will\n\
3007 be false for subsequent invocations, which will happen for duplicate\n\
3008 declarations. Whether or not anything must be done for the duplicate\n\
3009 declaration depends on whether the hook examines @code{DECL_ATTRIBUTES}.\n\
3010 @var{new_decl_p} is always true when the hook is called for a constant.\n\
3012 @cindex @code{SYMBOL_REF_FLAG}, in @code{TARGET_ENCODE_SECTION_INFO}\n\
3013 The usual thing for this hook to do is to record flags in the\n\
3014 @code{symbol_ref}, using @code{SYMBOL_REF_FLAG} or @code{SYMBOL_REF_FLAGS}.\n\
3015 Historically, the name string was modified if it was necessary to\n\
3016 encode more than one bit of information, but this practice is now\n\
3017 discouraged; use @code{SYMBOL_REF_FLAGS}.\n\
3019 The default definition of this hook, @code{default_encode_section_info}\n\
3020 in @file{varasm.c}, sets a number of commonly-useful bits in\n\
3021 @code{SYMBOL_REF_FLAGS}. Check whether the default does what you need\n\
3022 before overriding it.",
3023 void, (tree decl, rtx rtl, int new_decl_p),
3024 default_encode_section_info)
3026 /* Undo the effects of encode_section_info on the symbol string. */
3027 DEFHOOK
3028 (strip_name_encoding,
3029 "Decode @var{name} and return the real name part, sans\n\
3030 the characters that @code{TARGET_ENCODE_SECTION_INFO}\n\
3031 may have added.",
3032 const char *, (const char *name),
3033 default_strip_name_encoding)
3035 /* If shift optabs for MODE are known to always truncate the shift count,
3036 return the mask that they apply. Return 0 otherwise. */
3037 DEFHOOK
3038 (shift_truncation_mask,
3039 "This function describes how the standard shift patterns for @var{mode}\n\
3040 deal with shifts by negative amounts or by more than the width of the mode.\n\
3041 @xref{shift patterns}.\n\
3043 On many machines, the shift patterns will apply a mask @var{m} to the\n\
3044 shift count, meaning that a fixed-width shift of @var{x} by @var{y} is\n\
3045 equivalent to an arbitrary-width shift of @var{x} by @var{y & m}. If\n\
3046 this is true for mode @var{mode}, the function should return @var{m},\n\
3047 otherwise it should return 0. A return value of 0 indicates that no\n\
3048 particular behavior is guaranteed.\n\
3050 Note that, unlike @code{SHIFT_COUNT_TRUNCATED}, this function does\n\
3051 @emph{not} apply to general shift rtxes; it applies only to instructions\n\
3052 that are generated by the named shift patterns.\n\
3054 The default implementation of this function returns\n\
3055 @code{GET_MODE_BITSIZE (@var{mode}) - 1} if @code{SHIFT_COUNT_TRUNCATED}\n\
3056 and 0 otherwise. This definition is always safe, but if\n\
3057 @code{SHIFT_COUNT_TRUNCATED} is false, and some shift patterns\n\
3058 nevertheless truncate the shift count, you may get better code\n\
3059 by overriding it.",
3060 unsigned HOST_WIDE_INT, (machine_mode mode),
3061 default_shift_truncation_mask)
3063 /* Return the number of divisions in the given MODE that should be present,
3064 so that it is profitable to turn the division into a multiplication by
3065 the reciprocal. */
3066 DEFHOOK
3067 (min_divisions_for_recip_mul,
3068 "When @option{-ffast-math} is in effect, GCC tries to optimize\n\
3069 divisions by the same divisor, by turning them into multiplications by\n\
3070 the reciprocal. This target hook specifies the minimum number of divisions\n\
3071 that should be there for GCC to perform the optimization for a variable\n\
3072 of mode @var{mode}. The default implementation returns 3 if the machine\n\
3073 has an instruction for the division, and 2 if it does not.",
3074 unsigned int, (machine_mode mode),
3075 default_min_divisions_for_recip_mul)
3077 DEFHOOK
3078 (truly_noop_truncation,
3079 "This hook returns true if it is safe to ``convert'' a value of\n\
3080 @var{inprec} bits to one of @var{outprec} bits (where @var{outprec} is\n\
3081 smaller than @var{inprec}) by merely operating on it as if it had only\n\
3082 @var{outprec} bits. The default returns true unconditionally, which\n\
3083 is correct for most machines.\n\
3085 If @code{TARGET_MODES_TIEABLE_P} returns false for a pair of modes,\n\
3086 suboptimal code can result if this hook returns true for the corresponding\n\
3087 mode sizes. Making this hook return false in such cases may improve things.",
3088 bool, (poly_uint64 outprec, poly_uint64 inprec),
3089 hook_bool_puint64_puint64_true)
3091 /* If the representation of integral MODE is such that values are
3092 always sign-extended to a wider mode MODE_REP then return
3093 SIGN_EXTEND. Return UNKNOWN otherwise. */
3094 /* Note that the return type ought to be RTX_CODE, but that's not
3095 necessarily defined at this point. */
3096 DEFHOOK
3097 (mode_rep_extended,
3098 "The representation of an integral mode can be such that the values\n\
3099 are always extended to a wider integral mode. Return\n\
3100 @code{SIGN_EXTEND} if values of @var{mode} are represented in\n\
3101 sign-extended form to @var{rep_mode}. Return @code{UNKNOWN}\n\
3102 otherwise. (Currently, none of the targets use zero-extended\n\
3103 representation this way so unlike @code{LOAD_EXTEND_OP},\n\
3104 @code{TARGET_MODE_REP_EXTENDED} is expected to return either\n\
3105 @code{SIGN_EXTEND} or @code{UNKNOWN}. Also no target extends\n\
3106 @var{mode} to @var{rep_mode} so that @var{rep_mode} is not the next\n\
3107 widest integral mode and currently we take advantage of this fact.)\n\
3109 Similarly to @code{LOAD_EXTEND_OP} you may return a non-@code{UNKNOWN}\n\
3110 value even if the extension is not performed on certain hard registers\n\
3111 as long as for the @code{REGNO_REG_CLASS} of these hard registers\n\
3112 @code{TARGET_CAN_CHANGE_MODE_CLASS} returns false.\n\
3114 Note that @code{TARGET_MODE_REP_EXTENDED} and @code{LOAD_EXTEND_OP}\n\
3115 describe two related properties. If you define\n\
3116 @code{TARGET_MODE_REP_EXTENDED (mode, word_mode)} you probably also want\n\
3117 to define @code{LOAD_EXTEND_OP (mode)} to return the same type of\n\
3118 extension.\n\
3120 In order to enforce the representation of @code{mode},\n\
3121 @code{TARGET_TRULY_NOOP_TRUNCATION} should return false when truncating to\n\
3122 @code{mode}.",
3123 int, (scalar_int_mode mode, scalar_int_mode rep_mode),
3124 default_mode_rep_extended)
3126 /* True if MODE is valid for a pointer in __attribute__((mode("MODE"))). */
3127 DEFHOOK
3128 (valid_pointer_mode,
3129 "Define this to return nonzero if the port can handle pointers\n\
3130 with machine mode @var{mode}. The default version of this\n\
3131 hook returns true for both @code{ptr_mode} and @code{Pmode}.",
3132 bool, (scalar_int_mode mode),
3133 default_valid_pointer_mode)
3135 /* Disambiguate with errno. */
3136 DEFHOOK
3137 (ref_may_alias_errno,
3138 "Define this to return nonzero if the memory reference @var{ref}\
3139 may alias with the system C library errno location. The default\
3140 version of this hook assumes the system C library errno location\
3141 is either a declaration of type int or accessed by dereferencing\
3142 a pointer to int.",
3143 bool, (struct ao_ref *ref),
3144 default_ref_may_alias_errno)
3146 /* Support for named address spaces. */
3147 #undef HOOK_PREFIX
3148 #define HOOK_PREFIX "TARGET_ADDR_SPACE_"
3149 HOOK_VECTOR (TARGET_ADDR_SPACE_HOOKS, addr_space)
3151 /* MODE to use for a pointer into another address space. */
3152 DEFHOOK
3153 (pointer_mode,
3154 "Define this to return the machine mode to use for pointers to\n\
3155 @var{address_space} if the target supports named address spaces.\n\
3156 The default version of this hook returns @code{ptr_mode}.",
3157 scalar_int_mode, (addr_space_t address_space),
3158 default_addr_space_pointer_mode)
3160 /* MODE to use for an address in another address space. */
3161 DEFHOOK
3162 (address_mode,
3163 "Define this to return the machine mode to use for addresses in\n\
3164 @var{address_space} if the target supports named address spaces.\n\
3165 The default version of this hook returns @code{Pmode}.",
3166 scalar_int_mode, (addr_space_t address_space),
3167 default_addr_space_address_mode)
3169 /* True if MODE is valid for a pointer in __attribute__((mode("MODE")))
3170 in another address space. */
3171 DEFHOOK
3172 (valid_pointer_mode,
3173 "Define this to return nonzero if the port can handle pointers\n\
3174 with machine mode @var{mode} to address space @var{as}. This target\n\
3175 hook is the same as the @code{TARGET_VALID_POINTER_MODE} target hook,\n\
3176 except that it includes explicit named address space support. The default\n\
3177 version of this hook returns true for the modes returned by either the\n\
3178 @code{TARGET_ADDR_SPACE_POINTER_MODE} or @code{TARGET_ADDR_SPACE_ADDRESS_MODE}\n\
3179 target hooks for the given address space.",
3180 bool, (scalar_int_mode mode, addr_space_t as),
3181 default_addr_space_valid_pointer_mode)
3183 /* True if an address is a valid memory address to a given named address
3184 space for a given mode. */
3185 DEFHOOK
3186 (legitimate_address_p,
3187 "Define this to return true if @var{exp} is a valid address for mode\n\
3188 @var{mode} in the named address space @var{as}. The @var{strict}\n\
3189 parameter says whether strict addressing is in effect after reload has\n\
3190 finished. This target hook is the same as the\n\
3191 @code{TARGET_LEGITIMATE_ADDRESS_P} target hook, except that it includes\n\
3192 explicit named address space support.",
3193 bool, (machine_mode mode, rtx exp, bool strict, addr_space_t as),
3194 default_addr_space_legitimate_address_p)
3196 /* Return an updated address to convert an invalid pointer to a named
3197 address space to a valid one. If NULL_RTX is returned use machine
3198 independent methods to make the address valid. */
3199 DEFHOOK
3200 (legitimize_address,
3201 "Define this to modify an invalid address @var{x} to be a valid address\n\
3202 with mode @var{mode} in the named address space @var{as}. This target\n\
3203 hook is the same as the @code{TARGET_LEGITIMIZE_ADDRESS} target hook,\n\
3204 except that it includes explicit named address space support.",
3205 rtx, (rtx x, rtx oldx, machine_mode mode, addr_space_t as),
3206 default_addr_space_legitimize_address)
3208 /* True if one named address space is a subset of another named address. */
3209 DEFHOOK
3210 (subset_p,
3211 "Define this to return whether the @var{subset} named address space is\n\
3212 contained within the @var{superset} named address space. Pointers to\n\
3213 a named address space that is a subset of another named address space\n\
3214 will be converted automatically without a cast if used together in\n\
3215 arithmetic operations. Pointers to a superset address space can be\n\
3216 converted to pointers to a subset address space via explicit casts.",
3217 bool, (addr_space_t subset, addr_space_t superset),
3218 default_addr_space_subset_p)
3220 /* True if 0 is a valid address in the address space, or false if
3221 0 is a NULL in the address space. */
3222 DEFHOOK
3223 (zero_address_valid,
3224 "Define this to modify the default handling of address 0 for the\n\
3225 address space. Return true if 0 should be considered a valid address.",
3226 bool, (addr_space_t as),
3227 default_addr_space_zero_address_valid)
3229 /* Function to convert an rtl expression from one address space to another. */
3230 DEFHOOK
3231 (convert,
3232 "Define this to convert the pointer expression represented by the RTL\n\
3233 @var{op} with type @var{from_type} that points to a named address\n\
3234 space to a new pointer expression with type @var{to_type} that points\n\
3235 to a different named address space. When this hook it called, it is\n\
3236 guaranteed that one of the two address spaces is a subset of the other,\n\
3237 as determined by the @code{TARGET_ADDR_SPACE_SUBSET_P} target hook.",
3238 rtx, (rtx op, tree from_type, tree to_type),
3239 default_addr_space_convert)
3241 /* Function to encode an address space into dwarf. */
3242 DEFHOOK
3243 (debug,
3244 "Define this to define how the address space is encoded in dwarf.\n\
3245 The result is the value to be used with @code{DW_AT_address_class}.",
3246 int, (addr_space_t as),
3247 default_addr_space_debug)
3249 /* Function to emit custom diagnostic if an address space is used. */
3250 DEFHOOK
3251 (diagnose_usage,
3252 "Define this hook if the availability of an address space depends on\n\
3253 command line options and some diagnostics should be printed when the\n\
3254 address space is used. This hook is called during parsing and allows\n\
3255 to emit a better diagnostic compared to the case where the address space\n\
3256 was not registered with @code{c_register_addr_space}. @var{as} is\n\
3257 the address space as registered with @code{c_register_addr_space}.\n\
3258 @var{loc} is the location of the address space qualifier token.\n\
3259 The default implementation does nothing.",
3260 void, (addr_space_t as, location_t loc),
3261 default_addr_space_diagnose_usage)
3263 HOOK_VECTOR_END (addr_space)
3265 #undef HOOK_PREFIX
3266 #define HOOK_PREFIX "TARGET_"
3268 DEFHOOK
3269 (static_rtx_alignment,
3270 "This hook returns the preferred alignment in bits for a\n\
3271 statically-allocated rtx, such as a constant pool entry. @var{mode}\n\
3272 is the mode of the rtx. The default implementation returns\n\
3273 @samp{GET_MODE_ALIGNMENT (@var{mode})}.",
3274 HOST_WIDE_INT, (machine_mode mode),
3275 default_static_rtx_alignment)
3277 DEFHOOK
3278 (constant_alignment,
3279 "This hook returns the alignment in bits of a constant that is being\n\
3280 placed in memory. @var{constant} is the constant and @var{basic_align}\n\
3281 is the alignment that the object would ordinarily have.\n\
3283 The default definition just returns @var{basic_align}.\n\
3285 The typical use of this hook is to increase alignment for string\n\
3286 constants to be word aligned so that @code{strcpy} calls that copy\n\
3287 constants can be done inline. The function\n\
3288 @code{constant_alignment_word_strings} provides such a definition.",
3289 HOST_WIDE_INT, (const_tree constant, HOST_WIDE_INT basic_align),
3290 default_constant_alignment)
3292 DEFHOOK
3293 (translate_mode_attribute,
3294 "Define this hook if during mode attribute processing, the port should\n\
3295 translate machine_mode @var{mode} to another mode. For example, rs6000's\n\
3296 @code{KFmode}, when it is the same as @code{TFmode}.\n\
3298 The default version of the hook returns that mode that was passed in.",
3299 machine_mode, (machine_mode mode),
3300 default_translate_mode_attribute)
3302 /* True if MODE is valid for the target. By "valid", we mean able to
3303 be manipulated in non-trivial ways. In particular, this means all
3304 the arithmetic is supported. */
3305 DEFHOOK
3306 (scalar_mode_supported_p,
3307 "Define this to return nonzero if the port is prepared to handle\n\
3308 insns involving scalar mode @var{mode}. For a scalar mode to be\n\
3309 considered supported, all the basic arithmetic and comparisons\n\
3310 must work.\n\
3312 The default version of this hook returns true for any mode\n\
3313 required to handle the basic C types (as defined by the port).\n\
3314 Included here are the double-word arithmetic supported by the\n\
3315 code in @file{optabs.c}.",
3316 bool, (scalar_mode mode),
3317 default_scalar_mode_supported_p)
3319 /* Similarly for vector modes. "Supported" here is less strict. At
3320 least some operations are supported; need to check optabs or builtins
3321 for further details. */
3322 DEFHOOK
3323 (vector_mode_supported_p,
3324 "Define this to return nonzero if the port is prepared to handle\n\
3325 insns involving vector mode @var{mode}. At the very least, it\n\
3326 must have move patterns for this mode.",
3327 bool, (machine_mode mode),
3328 hook_bool_mode_false)
3330 DEFHOOK
3331 (vector_alignment,
3332 "This hook can be used to define the alignment for a vector of type\n\
3333 @var{type}, in order to comply with a platform ABI. The default is to\n\
3334 require natural alignment for vector types. The alignment returned by\n\
3335 this hook must be a power-of-two multiple of the default alignment of\n\
3336 the vector element type.",
3337 HOST_WIDE_INT, (const_tree type),
3338 default_vector_alignment)
3340 DEFHOOK
3341 (array_mode,
3342 "Return the mode that GCC should use for an array that has\n\
3343 @var{nelems} elements, with each element having mode @var{mode}.\n\
3344 Return no mode if the target has no special requirements. In the\n\
3345 latter case, GCC looks for an integer mode of the appropriate size\n\
3346 if available and uses BLKmode otherwise. Usually the search for the\n\
3347 integer mode is limited to @code{MAX_FIXED_MODE_SIZE}, but the\n\
3348 @code{TARGET_ARRAY_MODE_SUPPORTED_P} hook allows a larger mode to be\n\
3349 used in specific cases.\n\
3351 The main use of this hook is to specify that an array of vectors should\n\
3352 also have a vector mode. The default implementation returns no mode.",
3353 opt_machine_mode, (machine_mode mode, unsigned HOST_WIDE_INT nelems),
3354 hook_optmode_mode_uhwi_none)
3356 /* True if we should try to use a scalar mode to represent an array,
3357 overriding the usual MAX_FIXED_MODE limit. */
3358 DEFHOOK
3359 (array_mode_supported_p,
3360 "Return true if GCC should try to use a scalar mode to store an array\n\
3361 of @var{nelems} elements, given that each element has mode @var{mode}.\n\
3362 Returning true here overrides the usual @code{MAX_FIXED_MODE} limit\n\
3363 and allows GCC to use any defined integer mode.\n\
3365 One use of this hook is to support vector load and store operations\n\
3366 that operate on several homogeneous vectors. For example, ARM NEON\n\
3367 has operations like:\n\
3369 @smallexample\n\
3370 int8x8x3_t vld3_s8 (const int8_t *)\n\
3371 @end smallexample\n\
3373 where the return type is defined as:\n\
3375 @smallexample\n\
3376 typedef struct int8x8x3_t\n\
3377 @{\n\
3378 int8x8_t val[3];\n\
3379 @} int8x8x3_t;\n\
3380 @end smallexample\n\
3382 If this hook allows @code{val} to have a scalar mode, then\n\
3383 @code{int8x8x3_t} can have the same mode. GCC can then store\n\
3384 @code{int8x8x3_t}s in registers rather than forcing them onto the stack.",
3385 bool, (machine_mode mode, unsigned HOST_WIDE_INT nelems),
3386 hook_bool_mode_uhwi_false)
3388 DEFHOOK
3389 (libgcc_floating_mode_supported_p,
3390 "Define this to return nonzero if libgcc provides support for the \n\
3391 floating-point mode @var{mode}, which is known to pass \n\
3392 @code{TARGET_SCALAR_MODE_SUPPORTED_P}. The default version of this \n\
3393 hook returns true for all of @code{SFmode}, @code{DFmode}, \n\
3394 @code{XFmode} and @code{TFmode}, if such modes exist.",
3395 bool, (scalar_float_mode mode),
3396 default_libgcc_floating_mode_supported_p)
3398 DEFHOOK
3399 (floatn_mode,
3400 "Define this to return the machine mode to use for the type \n\
3401 @code{_Float@var{n}}, if @var{extended} is false, or the type \n\
3402 @code{_Float@var{n}x}, if @var{extended} is true. If such a type is not\n\
3403 supported, return @code{opt_scalar_float_mode ()}. The default version of\n\
3404 this hook returns @code{SFmode} for @code{_Float32}, @code{DFmode} for\n\
3405 @code{_Float64} and @code{_Float32x} and @code{TFmode} for \n\
3406 @code{_Float128}, if those modes exist and satisfy the requirements for \n\
3407 those types and pass @code{TARGET_SCALAR_MODE_SUPPORTED_P} and \n\
3408 @code{TARGET_LIBGCC_FLOATING_MODE_SUPPORTED_P}; for @code{_Float64x}, it \n\
3409 returns the first of @code{XFmode} and @code{TFmode} that exists and \n\
3410 satisfies the same requirements; for other types, it returns \n\
3411 @code{opt_scalar_float_mode ()}. The hook is only called for values\n\
3412 of @var{n} and @var{extended} that are valid according to\n\
3413 ISO/IEC TS 18661-3:2015; that is, @var{n} is one of 32, 64, 128, or,\n\
3414 if @var{extended} is false, 16 or greater than 128 and a multiple of 32.",
3415 opt_scalar_float_mode, (int n, bool extended),
3416 default_floatn_mode)
3418 DEFHOOK
3419 (floatn_builtin_p,
3420 "Define this to return true if the @code{_Float@var{n}} and\n\
3421 @code{_Float@var{n}x} built-in functions should implicitly enable the\n\
3422 built-in function without the @code{__builtin_} prefix in addition to the\n\
3423 normal built-in function with the @code{__builtin_} prefix. The default is\n\
3424 to only enable built-in functions without the @code{__builtin_} prefix for\n\
3425 the GNU C langauge. In strict ANSI/ISO mode, the built-in function without\n\
3426 the @code{__builtin_} prefix is not enabled. The argument @code{FUNC} is the\n\
3427 @code{enum built_in_function} id of the function to be enabled.",
3428 bool, (int func),
3429 default_floatn_builtin_p)
3431 /* Compute cost of moving data from a register of class FROM to one of
3432 TO, using MODE. */
3433 DEFHOOK
3434 (register_move_cost,
3435 "This target hook should return the cost of moving data of mode @var{mode}\n\
3436 from a register in class @var{from} to one in class @var{to}. The classes\n\
3437 are expressed using the enumeration values such as @code{GENERAL_REGS}.\n\
3438 A value of 2 is the default; other values are interpreted relative to\n\
3439 that.\n\
3441 It is not required that the cost always equal 2 when @var{from} is the\n\
3442 same as @var{to}; on some machines it is expensive to move between\n\
3443 registers if they are not general registers.\n\
3445 If reload sees an insn consisting of a single @code{set} between two\n\
3446 hard registers, and if @code{TARGET_REGISTER_MOVE_COST} applied to their\n\
3447 classes returns a value of 2, reload does not check to ensure that the\n\
3448 constraints of the insn are met. Setting a cost of other than 2 will\n\
3449 allow reload to verify that the constraints are met. You should do this\n\
3450 if the @samp{mov@var{m}} pattern's constraints do not allow such copying.\n\
3452 The default version of this function returns 2.",
3453 int, (machine_mode mode, reg_class_t from, reg_class_t to),
3454 default_register_move_cost)
3456 /* Compute cost of moving registers to/from memory. */
3457 /* ??? Documenting the argument types for this hook requires a GFDL
3458 license grant. Also, the documentation uses a different name for RCLASS. */
3459 DEFHOOK
3460 (memory_move_cost,
3461 "This target hook should return the cost of moving data of mode @var{mode}\n\
3462 between a register of class @var{rclass} and memory; @var{in} is @code{false}\n\
3463 if the value is to be written to memory, @code{true} if it is to be read in.\n\
3464 This cost is relative to those in @code{TARGET_REGISTER_MOVE_COST}.\n\
3465 If moving between registers and memory is more expensive than between two\n\
3466 registers, you should add this target hook to express the relative cost.\n\
3468 If you do not add this target hook, GCC uses a default cost of 4 plus\n\
3469 the cost of copying via a secondary reload register, if one is\n\
3470 needed. If your machine requires a secondary reload register to copy\n\
3471 between memory and a register of @var{rclass} but the reload mechanism is\n\
3472 more complex than copying via an intermediate, use this target hook to\n\
3473 reflect the actual cost of the move.\n\
3475 GCC defines the function @code{memory_move_secondary_cost} if\n\
3476 secondary reloads are needed. It computes the costs due to copying via\n\
3477 a secondary register. If your machine copies from memory using a\n\
3478 secondary register in the conventional way but the default base value of\n\
3479 4 is not correct for your machine, use this target hook to add some other\n\
3480 value to the result of that function. The arguments to that function\n\
3481 are the same as to this target hook.",
3482 int, (machine_mode mode, reg_class_t rclass, bool in),
3483 default_memory_move_cost)
3485 DEFHOOK
3486 (use_by_pieces_infrastructure_p,
3487 "GCC will attempt several strategies when asked to copy between\n\
3488 two areas of memory, or to set, clear or store to memory, for example\n\
3489 when copying a @code{struct}. The @code{by_pieces} infrastructure\n\
3490 implements such memory operations as a sequence of load, store or move\n\
3491 insns. Alternate strategies are to expand the\n\
3492 @code{movmem} or @code{setmem} optabs, to emit a library call, or to emit\n\
3493 unit-by-unit, loop-based operations.\n\
3495 This target hook should return true if, for a memory operation with a\n\
3496 given @var{size} and @var{alignment}, using the @code{by_pieces}\n\
3497 infrastructure is expected to result in better code generation.\n\
3498 Both @var{size} and @var{alignment} are measured in terms of storage\n\
3499 units.\n\
3501 The parameter @var{op} is one of: @code{CLEAR_BY_PIECES},\n\
3502 @code{MOVE_BY_PIECES}, @code{SET_BY_PIECES}, @code{STORE_BY_PIECES} or\n\
3503 @code{COMPARE_BY_PIECES}. These describe the type of memory operation\n\
3504 under consideration.\n\
3506 The parameter @var{speed_p} is true if the code is currently being\n\
3507 optimized for speed rather than size.\n\
3509 Returning true for higher values of @var{size} can improve code generation\n\
3510 for speed if the target does not provide an implementation of the\n\
3511 @code{movmem} or @code{setmem} standard names, if the @code{movmem} or\n\
3512 @code{setmem} implementation would be more expensive than a sequence of\n\
3513 insns, or if the overhead of a library call would dominate that of\n\
3514 the body of the memory operation.\n\
3516 Returning true for higher values of @code{size} may also cause an increase\n\
3517 in code size, for example where the number of insns emitted to perform a\n\
3518 move would be greater than that of a library call.",
3519 bool, (unsigned HOST_WIDE_INT size, unsigned int alignment,
3520 enum by_pieces_operation op, bool speed_p),
3521 default_use_by_pieces_infrastructure_p)
3523 DEFHOOK
3524 (compare_by_pieces_branch_ratio,
3525 "When expanding a block comparison in MODE, gcc can try to reduce the\n\
3526 number of branches at the expense of more memory operations. This hook\n\
3527 allows the target to override the default choice. It should return the\n\
3528 factor by which branches should be reduced over the plain expansion with\n\
3529 one comparison per @var{mode}-sized piece. A port can also prevent a\n\
3530 particular mode from being used for block comparisons by returning a\n\
3531 negative number from this hook.",
3532 int, (machine_mode mode),
3533 default_compare_by_pieces_branch_ratio)
3535 DEFHOOK
3536 (slow_unaligned_access,
3537 "This hook returns true if memory accesses described by the\n\
3538 @var{mode} and @var{alignment} parameters have a cost many times greater\n\
3539 than aligned accesses, for example if they are emulated in a trap handler.\n\
3540 This hook is invoked only for unaligned accesses, i.e. when\n\
3541 @code{@var{alignment} < GET_MODE_ALIGNMENT (@var{mode})}.\n\
3543 When this hook returns true, the compiler will act as if\n\
3544 @code{STRICT_ALIGNMENT} were true when generating code for block\n\
3545 moves. This can cause significantly more instructions to be produced.\n\
3546 Therefore, do not make this hook return true if unaligned accesses only\n\
3547 add a cycle or two to the time for a memory access.\n\
3549 The hook must return true whenever @code{STRICT_ALIGNMENT} is true.\n\
3550 The default implementation returns @code{STRICT_ALIGNMENT}.",
3551 bool, (machine_mode mode, unsigned int align),
3552 default_slow_unaligned_access)
3554 DEFHOOK
3555 (optab_supported_p,
3556 "Return true if the optimizers should use optab @var{op} with\n\
3557 modes @var{mode1} and @var{mode2} for optimization type @var{opt_type}.\n\
3558 The optab is known to have an associated @file{.md} instruction\n\
3559 whose C condition is true. @var{mode2} is only meaningful for conversion\n\
3560 optabs; for direct optabs it is a copy of @var{mode1}.\n\
3562 For example, when called with @var{op} equal to @code{rint_optab} and\n\
3563 @var{mode1} equal to @code{DFmode}, the hook should say whether the\n\
3564 optimizers should use optab @code{rintdf2}.\n\
3566 The default hook returns true for all inputs.",
3567 bool, (int op, machine_mode mode1, machine_mode mode2,
3568 optimization_type opt_type),
3569 default_optab_supported_p)
3571 /* True for MODE if the target expects that registers in this mode will
3572 be allocated to registers in a small register class. The compiler is
3573 allowed to use registers explicitly used in the rtl as spill registers
3574 but it should prevent extending the lifetime of these registers. */
3575 DEFHOOK
3576 (small_register_classes_for_mode_p,
3577 "Define this to return nonzero for machine modes for which the port has\n\
3578 small register classes. If this target hook returns nonzero for a given\n\
3579 @var{mode}, the compiler will try to minimize the lifetime of registers\n\
3580 in @var{mode}. The hook may be called with @code{VOIDmode} as argument.\n\
3581 In this case, the hook is expected to return nonzero if it returns nonzero\n\
3582 for any mode.\n\
3584 On some machines, it is risky to let hard registers live across arbitrary\n\
3585 insns. Typically, these machines have instructions that require values\n\
3586 to be in specific registers (like an accumulator), and reload will fail\n\
3587 if the required hard register is used for another purpose across such an\n\
3588 insn.\n\
3590 Passes before reload do not know which hard registers will be used\n\
3591 in an instruction, but the machine modes of the registers set or used in\n\
3592 the instruction are already known. And for some machines, register\n\
3593 classes are small for, say, integer registers but not for floating point\n\
3594 registers. For example, the AMD x86-64 architecture requires specific\n\
3595 registers for the legacy x86 integer instructions, but there are many\n\
3596 SSE registers for floating point operations. On such targets, a good\n\
3597 strategy may be to return nonzero from this hook for @code{INTEGRAL_MODE_P}\n\
3598 machine modes but zero for the SSE register classes.\n\
3600 The default version of this hook returns false for any mode. It is always\n\
3601 safe to redefine this hook to return with a nonzero value. But if you\n\
3602 unnecessarily define it, you will reduce the amount of optimizations\n\
3603 that can be performed in some cases. If you do not define this hook\n\
3604 to return a nonzero value when it is required, the compiler will run out\n\
3605 of spill registers and print a fatal error message.",
3606 bool, (machine_mode mode),
3607 hook_bool_mode_false)
3609 /* Register number for a flags register. Only needs to be defined if the
3610 target is constrainted to use post-reload comparison elimination. */
3611 DEFHOOKPOD
3612 (flags_regnum,
3613 "If the target has a dedicated flags register, and it needs to use the\
3614 post-reload comparison elimination pass, then this value should be set\
3615 appropriately.",
3616 unsigned int, INVALID_REGNUM)
3618 /* Compute a (partial) cost for rtx X. Return true if the complete
3619 cost has been computed, and false if subexpressions should be
3620 scanned. In either case, *TOTAL contains the cost result. */
3621 /* Note that OUTER_CODE ought to be RTX_CODE, but that's
3622 not necessarily defined at this point. */
3623 DEFHOOK
3624 (rtx_costs,
3625 "This target hook describes the relative costs of RTL expressions.\n\
3627 The cost may depend on the precise form of the expression, which is\n\
3628 available for examination in @var{x}, and the fact that @var{x} appears\n\
3629 as operand @var{opno} of an expression with rtx code @var{outer_code}.\n\
3630 That is, the hook can assume that there is some rtx @var{y} such\n\
3631 that @samp{GET_CODE (@var{y}) == @var{outer_code}} and such that\n\
3632 either (a) @samp{XEXP (@var{y}, @var{opno}) == @var{x}} or\n\
3633 (b) @samp{XVEC (@var{y}, @var{opno})} contains @var{x}.\n\
3635 @var{mode} is @var{x}'s machine mode, or for cases like @code{const_int} that\n\
3636 do not have a mode, the mode in which @var{x} is used.\n\
3638 In implementing this hook, you can use the construct\n\
3639 @code{COSTS_N_INSNS (@var{n})} to specify a cost equal to @var{n} fast\n\
3640 instructions.\n\
3642 On entry to the hook, @code{*@var{total}} contains a default estimate\n\
3643 for the cost of the expression. The hook should modify this value as\n\
3644 necessary. Traditionally, the default costs are @code{COSTS_N_INSNS (5)}\n\
3645 for multiplications, @code{COSTS_N_INSNS (7)} for division and modulus\n\
3646 operations, and @code{COSTS_N_INSNS (1)} for all other operations.\n\
3648 When optimizing for code size, i.e.@: when @code{speed} is\n\
3649 false, this target hook should be used to estimate the relative\n\
3650 size cost of an expression, again relative to @code{COSTS_N_INSNS}.\n\
3652 The hook returns true when all subexpressions of @var{x} have been\n\
3653 processed, and false when @code{rtx_cost} should recurse.",
3654 bool, (rtx x, machine_mode mode, int outer_code, int opno, int *total, bool speed),
3655 hook_bool_rtx_mode_int_int_intp_bool_false)
3657 /* Compute the cost of X, used as an address. Never called with
3658 invalid addresses. */
3659 DEFHOOK
3660 (address_cost,
3661 "This hook computes the cost of an addressing mode that contains\n\
3662 @var{address}. If not defined, the cost is computed from\n\
3663 the @var{address} expression and the @code{TARGET_RTX_COST} hook.\n\
3665 For most CISC machines, the default cost is a good approximation of the\n\
3666 true cost of the addressing mode. However, on RISC machines, all\n\
3667 instructions normally have the same length and execution time. Hence\n\
3668 all addresses will have equal costs.\n\
3670 In cases where more than one form of an address is known, the form with\n\
3671 the lowest cost will be used. If multiple forms have the same, lowest,\n\
3672 cost, the one that is the most complex will be used.\n\
3674 For example, suppose an address that is equal to the sum of a register\n\
3675 and a constant is used twice in the same basic block. When this macro\n\
3676 is not defined, the address will be computed in a register and memory\n\
3677 references will be indirect through that register. On machines where\n\
3678 the cost of the addressing mode containing the sum is no higher than\n\
3679 that of a simple indirect reference, this will produce an additional\n\
3680 instruction and possibly require an additional register. Proper\n\
3681 specification of this macro eliminates this overhead for such machines.\n\
3683 This hook is never called with an invalid address.\n\
3685 On machines where an address involving more than one register is as\n\
3686 cheap as an address computation involving only one register, defining\n\
3687 @code{TARGET_ADDRESS_COST} to reflect this can cause two registers to\n\
3688 be live over a region of code where only one would have been if\n\
3689 @code{TARGET_ADDRESS_COST} were not defined in that manner. This effect\n\
3690 should be considered in the definition of this macro. Equivalent costs\n\
3691 should probably only be given to addresses with different numbers of\n\
3692 registers on machines with lots of registers.",
3693 int, (rtx address, machine_mode mode, addr_space_t as, bool speed),
3694 default_address_cost)
3696 /* Compute a cost for INSN. */
3697 DEFHOOK
3698 (insn_cost,
3699 "This target hook describes the relative costs of RTL instructions.\n\
3701 In implementing this hook, you can use the construct\n\
3702 @code{COSTS_N_INSNS (@var{n})} to specify a cost equal to @var{n} fast\n\
3703 instructions.\n\
3705 When optimizing for code size, i.e.@: when @code{speed} is\n\
3706 false, this target hook should be used to estimate the relative\n\
3707 size cost of an expression, again relative to @code{COSTS_N_INSNS}.",
3708 int, (rtx_insn *insn, bool speed), NULL)
3710 /* Give a cost, in RTX Costs units, for an edge. Like BRANCH_COST, but with
3711 well defined units. */
3712 DEFHOOK
3713 (max_noce_ifcvt_seq_cost,
3714 "This hook returns a value in the same units as @code{TARGET_RTX_COSTS},\n\
3715 giving the maximum acceptable cost for a sequence generated by the RTL\n\
3716 if-conversion pass when conditional execution is not available.\n\
3717 The RTL if-conversion pass attempts to convert conditional operations\n\
3718 that would require a branch to a series of unconditional operations and\n\
3719 @code{mov@var{mode}cc} insns. This hook returns the maximum cost of the\n\
3720 unconditional instructions and the @code{mov@var{mode}cc} insns.\n\
3721 RTL if-conversion is cancelled if the cost of the converted sequence\n\
3722 is greater than the value returned by this hook.\n\
3724 @code{e} is the edge between the basic block containing the conditional\n\
3725 branch to the basic block which would be executed if the condition\n\
3726 were true.\n\
3728 The default implementation of this hook uses the\n\
3729 @code{max-rtl-if-conversion-[un]predictable} parameters if they are set,\n\
3730 and uses a multiple of @code{BRANCH_COST} otherwise.",
3731 unsigned int, (edge e),
3732 default_max_noce_ifcvt_seq_cost)
3734 /* Return true if the given instruction sequence is a good candidate
3735 as a replacement for the if-convertible sequence. */
3736 DEFHOOK
3737 (noce_conversion_profitable_p,
3738 "This hook returns true if the instruction sequence @code{seq} is a good\n\
3739 candidate as a replacement for the if-convertible sequence described in\n\
3740 @code{if_info}.",
3741 bool, (rtx_insn *seq, struct noce_if_info *if_info),
3742 default_noce_conversion_profitable_p)
3744 DEFHOOK
3745 (estimated_poly_value,
3746 "Return an estimate of the runtime value of @var{val}, for use in\n\
3747 things like cost calculations or profiling frequencies. The default\n\
3748 implementation returns the lowest possible value of @var{val}.",
3749 HOST_WIDE_INT, (poly_int64 val),
3750 default_estimated_poly_value)
3752 /* Permit speculative instructions in delay slots during delayed-branch
3753 scheduling. */
3754 DEFHOOK
3755 (no_speculation_in_delay_slots_p,
3756 "This predicate controls the use of the eager delay slot filler to disallow\n\
3757 speculatively executed instructions being placed in delay slots. Targets\n\
3758 such as certain MIPS architectures possess both branches with and without\n\
3759 delay slots. As the eager delay slot filler can decrease performance,\n\
3760 disabling it is beneficial when ordinary branches are available. Use of\n\
3761 delay slot branches filled using the basic filler is often still desirable\n\
3762 as the delay slot can hide a pipeline bubble.", bool, (void),
3763 hook_bool_void_false)
3765 /* Return where to allocate pseudo for a given hard register initial value. */
3766 DEFHOOK
3767 (allocate_initial_value,
3768 "\n\
3769 When the initial value of a hard register has been copied in a pseudo\n\
3770 register, it is often not necessary to actually allocate another register\n\
3771 to this pseudo register, because the original hard register or a stack slot\n\
3772 it has been saved into can be used. @code{TARGET_ALLOCATE_INITIAL_VALUE}\n\
3773 is called at the start of register allocation once for each hard register\n\
3774 that had its initial value copied by using\n\
3775 @code{get_func_hard_reg_initial_val} or @code{get_hard_reg_initial_val}.\n\
3776 Possible values are @code{NULL_RTX}, if you don't want\n\
3777 to do any special allocation, a @code{REG} rtx---that would typically be\n\
3778 the hard register itself, if it is known not to be clobbered---or a\n\
3779 @code{MEM}.\n\
3780 If you are returning a @code{MEM}, this is only a hint for the allocator;\n\
3781 it might decide to use another register anyways.\n\
3782 You may use @code{current_function_is_leaf} or \n\
3783 @code{REG_N_SETS} in the hook to determine if the hard\n\
3784 register in question will not be clobbered.\n\
3785 The default value of this hook is @code{NULL}, which disables any special\n\
3786 allocation.",
3787 rtx, (rtx hard_reg), NULL)
3789 /* Return nonzero if evaluating UNSPEC X might cause a trap.
3790 FLAGS has the same meaning as in rtlanal.c: may_trap_p_1. */
3791 DEFHOOK
3792 (unspec_may_trap_p,
3793 "This target hook returns nonzero if @var{x}, an @code{unspec} or\n\
3794 @code{unspec_volatile} operation, might cause a trap. Targets can use\n\
3795 this hook to enhance precision of analysis for @code{unspec} and\n\
3796 @code{unspec_volatile} operations. You may call @code{may_trap_p_1}\n\
3797 to analyze inner elements of @var{x} in which case @var{flags} should be\n\
3798 passed along.",
3799 int, (const_rtx x, unsigned flags),
3800 default_unspec_may_trap_p)
3802 /* Given a register, this hook should return a parallel of registers
3803 to represent where to find the register pieces. Define this hook
3804 if the register and its mode are represented in Dwarf in
3805 non-contiguous locations, or if the register should be
3806 represented in more than one register in Dwarf. Otherwise, this
3807 hook should return NULL_RTX. */
3808 DEFHOOK
3809 (dwarf_register_span,
3810 "Given a register, this hook should return a parallel of registers to\n\
3811 represent where to find the register pieces. Define this hook if the\n\
3812 register and its mode are represented in Dwarf in non-contiguous\n\
3813 locations, or if the register should be represented in more than one\n\
3814 register in Dwarf. Otherwise, this hook should return @code{NULL_RTX}.\n\
3815 If not defined, the default is to return @code{NULL_RTX}.",
3816 rtx, (rtx reg),
3817 hook_rtx_rtx_null)
3819 /* Given a register return the mode of the corresponding DWARF frame
3820 register. */
3821 DEFHOOK
3822 (dwarf_frame_reg_mode,
3823 "Given a register, this hook should return the mode which the\n\
3824 corresponding Dwarf frame register should have. This is normally\n\
3825 used to return a smaller mode than the raw mode to prevent call\n\
3826 clobbered parts of a register altering the frame register size",
3827 machine_mode, (int regno),
3828 default_dwarf_frame_reg_mode)
3830 /* If expand_builtin_init_dwarf_reg_sizes needs to fill in table
3831 entries not corresponding directly to registers below
3832 FIRST_PSEUDO_REGISTER, this hook should generate the necessary
3833 code, given the address of the table. */
3834 DEFHOOK
3835 (init_dwarf_reg_sizes_extra,
3836 "If some registers are represented in Dwarf-2 unwind information in\n\
3837 multiple pieces, define this hook to fill in information about the\n\
3838 sizes of those pieces in the table used by the unwinder at runtime.\n\
3839 It will be called by @code{expand_builtin_init_dwarf_reg_sizes} after\n\
3840 filling in a single size corresponding to each hard register;\n\
3841 @var{address} is the address of the table.",
3842 void, (tree address),
3843 hook_void_tree)
3845 /* Fetch the fixed register(s) which hold condition codes, for
3846 targets where it makes sense to look for duplicate assignments to
3847 the condition codes. This should return true if there is such a
3848 register, false otherwise. The arguments should be set to the
3849 fixed register numbers. Up to two condition code registers are
3850 supported. If there is only one for this target, the int pointed
3851 at by the second argument should be set to -1. */
3852 DEFHOOK
3853 (fixed_condition_code_regs,
3854 "On targets which do not use @code{(cc0)}, and which use a hard\n\
3855 register rather than a pseudo-register to hold condition codes, the\n\
3856 regular CSE passes are often not able to identify cases in which the\n\
3857 hard register is set to a common value. Use this hook to enable a\n\
3858 small pass which optimizes such cases. This hook should return true\n\
3859 to enable this pass, and it should set the integers to which its\n\
3860 arguments point to the hard register numbers used for condition codes.\n\
3861 When there is only one such register, as is true on most systems, the\n\
3862 integer pointed to by @var{p2} should be set to\n\
3863 @code{INVALID_REGNUM}.\n\
3865 The default version of this hook returns false.",
3866 bool, (unsigned int *p1, unsigned int *p2),
3867 hook_bool_uintp_uintp_false)
3869 /* If two condition code modes are compatible, return a condition
3870 code mode which is compatible with both, such that a comparison
3871 done in the returned mode will work for both of the original
3872 modes. If the condition code modes are not compatible, return
3873 VOIDmode. */
3874 DEFHOOK
3875 (cc_modes_compatible,
3876 "On targets which use multiple condition code modes in class\n\
3877 @code{MODE_CC}, it is sometimes the case that a comparison can be\n\
3878 validly done in more than one mode. On such a system, define this\n\
3879 target hook to take two mode arguments and to return a mode in which\n\
3880 both comparisons may be validly done. If there is no such mode,\n\
3881 return @code{VOIDmode}.\n\
3883 The default version of this hook checks whether the modes are the\n\
3884 same. If they are, it returns that mode. If they are different, it\n\
3885 returns @code{VOIDmode}.",
3886 machine_mode, (machine_mode m1, machine_mode m2),
3887 default_cc_modes_compatible)
3889 /* Do machine-dependent code transformations. Called just before
3890 delayed-branch scheduling. */
3891 DEFHOOK
3892 (machine_dependent_reorg,
3893 "If non-null, this hook performs a target-specific pass over the\n\
3894 instruction stream. The compiler will run it at all optimization levels,\n\
3895 just before the point at which it normally does delayed-branch scheduling.\n\
3897 The exact purpose of the hook varies from target to target. Some use\n\
3898 it to do transformations that are necessary for correctness, such as\n\
3899 laying out in-function constant pools or avoiding hardware hazards.\n\
3900 Others use it as an opportunity to do some machine-dependent optimizations.\n\
3902 You need not implement the hook if it has nothing to do. The default\n\
3903 definition is null.",
3904 void, (void), NULL)
3906 /* Create the __builtin_va_list type. */
3907 DEFHOOK
3908 (build_builtin_va_list,
3909 "This hook returns a type node for @code{va_list} for the target.\n\
3910 The default version of the hook returns @code{void*}.",
3911 tree, (void),
3912 std_build_builtin_va_list)
3914 /* Enumerate the va list variants. */
3915 DEFHOOK
3916 (enum_va_list_p,
3917 "This target hook is used in function @code{c_common_nodes_and_builtins}\n\
3918 to iterate through the target specific builtin types for va_list. The\n\
3919 variable @var{idx} is used as iterator. @var{pname} has to be a pointer\n\
3920 to a @code{const char *} and @var{ptree} a pointer to a @code{tree} typed\n\
3921 variable.\n\
3922 The arguments @var{pname} and @var{ptree} are used to store the result of\n\
3923 this macro and are set to the name of the va_list builtin type and its\n\
3924 internal type.\n\
3925 If the return value of this macro is zero, then there is no more element.\n\
3926 Otherwise the @var{IDX} should be increased for the next call of this\n\
3927 macro to iterate through all types.",
3928 int, (int idx, const char **pname, tree *ptree),
3929 NULL)
3931 /* Get the cfun/fndecl calling abi __builtin_va_list type. */
3932 DEFHOOK
3933 (fn_abi_va_list,
3934 "This hook returns the va_list type of the calling convention specified by\n\
3935 @var{fndecl}.\n\
3936 The default version of this hook returns @code{va_list_type_node}.",
3937 tree, (tree fndecl),
3938 std_fn_abi_va_list)
3940 /* Get the __builtin_va_list type dependent on input type. */
3941 DEFHOOK
3942 (canonical_va_list_type,
3943 "This hook returns the va_list type of the calling convention specified by the\n\
3944 type of @var{type}. If @var{type} is not a valid va_list type, it returns\n\
3945 @code{NULL_TREE}.",
3946 tree, (tree type),
3947 std_canonical_va_list_type)
3949 /* ??? Documenting this hook requires a GFDL license grant. */
3950 DEFHOOK_UNDOC
3951 (expand_builtin_va_start,
3952 "Expand the @code{__builtin_va_start} builtin.",
3953 void, (tree valist, rtx nextarg), NULL)
3955 /* Gimplifies a VA_ARG_EXPR. */
3956 DEFHOOK
3957 (gimplify_va_arg_expr,
3958 "This hook performs target-specific gimplification of\n\
3959 @code{VA_ARG_EXPR}. The first two parameters correspond to the\n\
3960 arguments to @code{va_arg}; the latter two are as in\n\
3961 @code{gimplify.c:gimplify_expr}.",
3962 tree, (tree valist, tree type, gimple_seq *pre_p, gimple_seq *post_p),
3963 std_gimplify_va_arg_expr)
3965 /* Validity-checking routines for PCH files, target-specific.
3966 get_pch_validity returns a pointer to the data to be stored,
3967 and stores the size in its argument. pch_valid_p gets the same
3968 information back and returns NULL if the PCH is valid,
3969 or an error message if not. */
3970 DEFHOOK
3971 (get_pch_validity,
3972 "This hook returns a pointer to the data needed by\n\
3973 @code{TARGET_PCH_VALID_P} and sets\n\
3974 @samp{*@var{sz}} to the size of the data in bytes.",
3975 void *, (size_t *sz),
3976 default_get_pch_validity)
3978 DEFHOOK
3979 (pch_valid_p,
3980 "This hook checks whether the options used to create a PCH file are\n\
3981 compatible with the current settings. It returns @code{NULL}\n\
3982 if so and a suitable error message if not. Error messages will\n\
3983 be presented to the user and must be localized using @samp{_(@var{msg})}.\n\
3985 @var{data} is the data that was returned by @code{TARGET_GET_PCH_VALIDITY}\n\
3986 when the PCH file was created and @var{sz} is the size of that data in bytes.\n\
3987 It's safe to assume that the data was created by the same version of the\n\
3988 compiler, so no format checking is needed.\n\
3990 The default definition of @code{default_pch_valid_p} should be\n\
3991 suitable for most targets.",
3992 const char *, (const void *data, size_t sz),
3993 default_pch_valid_p)
3995 DEFHOOK
3996 (prepare_pch_save,
3997 "Called before writing out a PCH file. If the target has some\n\
3998 garbage-collected data that needs to be in a particular state on PCH loads,\n\
3999 it can use this hook to enforce that state. Very few targets need\n\
4000 to do anything here.",
4001 void, (void),
4002 hook_void_void)
4004 /* If nonnull, this function checks whether a PCH file with the
4005 given set of target flags can be used. It returns NULL if so,
4006 otherwise it returns an error message. */
4007 DEFHOOK
4008 (check_pch_target_flags,
4009 "If this hook is nonnull, the default implementation of\n\
4010 @code{TARGET_PCH_VALID_P} will use it to check for compatible values\n\
4011 of @code{target_flags}. @var{pch_flags} specifies the value that\n\
4012 @code{target_flags} had when the PCH file was created. The return\n\
4013 value is the same as for @code{TARGET_PCH_VALID_P}.",
4014 const char *, (int pch_flags), NULL)
4016 /* True if the compiler should give an enum type only as many
4017 bytes as it takes to represent the range of possible values of
4018 that type. */
4019 DEFHOOK
4020 (default_short_enums,
4021 "This target hook should return true if the compiler should give an\n\
4022 @code{enum} type only as many bytes as it takes to represent the range\n\
4023 of possible values of that type. It should return false if all\n\
4024 @code{enum} types should be allocated like @code{int}.\n\
4026 The default is to return false.",
4027 bool, (void),
4028 hook_bool_void_false)
4030 /* This target hook returns an rtx that is used to store the address
4031 of the current frame into the built-in setjmp buffer. */
4032 DEFHOOK
4033 (builtin_setjmp_frame_value,
4034 "This target hook should return an rtx that is used to store\n\
4035 the address of the current frame into the built in @code{setjmp} buffer.\n\
4036 The default value, @code{virtual_stack_vars_rtx}, is correct for most\n\
4037 machines. One reason you may need to define this target hook is if\n\
4038 @code{hard_frame_pointer_rtx} is the appropriate value on your machine.",
4039 rtx, (void),
4040 default_builtin_setjmp_frame_value)
4042 /* This target hook should manipulate the outputs, inputs, constraints,
4043 and clobbers the port wishes for pre-processing the asm. */
4044 DEFHOOK
4045 (md_asm_adjust,
4046 "This target hook may add @dfn{clobbers} to @var{clobbers} and\n\
4047 @var{clobbered_regs} for any hard regs the port wishes to automatically\n\
4048 clobber for an asm. The @var{outputs} and @var{inputs} may be inspected\n\
4049 to avoid clobbering a register that is already used by the asm.\n\
4051 It may modify the @var{outputs}, @var{inputs}, and @var{constraints}\n\
4052 as necessary for other pre-processing. In this case the return value is\n\
4053 a sequence of insns to emit after the asm.",
4054 rtx_insn *,
4055 (vec<rtx>& outputs, vec<rtx>& inputs, vec<const char *>& constraints,
4056 vec<rtx>& clobbers, HARD_REG_SET& clobbered_regs),
4057 NULL)
4059 /* This target hook allows the backend to specify a calling convention
4060 in the debug information. This function actually returns an
4061 enum dwarf_calling_convention, but because of forward declarations
4062 and not wanting to include dwarf2.h everywhere target.h is included
4063 the function is being declared as an int. */
4064 DEFHOOK
4065 (dwarf_calling_convention,
4066 "Define this to enable the dwarf attribute @code{DW_AT_calling_convention} to\n\
4067 be emitted for each function. Instead of an integer return the enum\n\
4068 value for the @code{DW_CC_} tag.",
4069 int, (const_tree function),
4070 hook_int_const_tree_0)
4072 /* This target hook allows the backend to emit frame-related insns that
4073 contain UNSPECs or UNSPEC_VOLATILEs. The call frame debugging info
4074 engine will invoke it on insns of the form
4075 (set (reg) (unspec [...] UNSPEC_INDEX))
4077 (set (reg) (unspec_volatile [...] UNSPECV_INDEX))
4078 to let the backend emit the call frame instructions. */
4079 DEFHOOK
4080 (dwarf_handle_frame_unspec,
4081 "This target hook allows the backend to emit frame-related insns that\n\
4082 contain UNSPECs or UNSPEC_VOLATILEs. The DWARF 2 call frame debugging\n\
4083 info engine will invoke it on insns of the form\n\
4084 @smallexample\n\
4085 (set (reg) (unspec [@dots{}] UNSPEC_INDEX))\n\
4086 @end smallexample\n\
4087 and\n\
4088 @smallexample\n\
4089 (set (reg) (unspec_volatile [@dots{}] UNSPECV_INDEX)).\n\
4090 @end smallexample\n\
4091 to let the backend emit the call frame instructions. @var{label} is\n\
4092 the CFI label attached to the insn, @var{pattern} is the pattern of\n\
4093 the insn and @var{index} is @code{UNSPEC_INDEX} or @code{UNSPECV_INDEX}.",
4094 void, (const char *label, rtx pattern, int index), NULL)
4096 DEFHOOK
4097 (dwarf_poly_indeterminate_value,
4098 "Express the value of @code{poly_int} indeterminate @var{i} as a DWARF\n\
4099 expression, with @var{i} counting from 1. Return the number of a DWARF\n\
4100 register @var{R} and set @samp{*@var{factor}} and @samp{*@var{offset}} such\n\
4101 that the value of the indeterminate is:\n\
4102 @smallexample\n\
4103 value_of(@var{R}) / @var{factor} - @var{offset}\n\
4104 @end smallexample\n\
4106 A target only needs to define this hook if it sets\n\
4107 @samp{NUM_POLY_INT_COEFFS} to a value greater than 1.",
4108 unsigned int, (unsigned int i, unsigned int *factor, int *offset),
4109 default_dwarf_poly_indeterminate_value)
4111 /* ??? Documenting this hook requires a GFDL license grant. */
4112 DEFHOOK_UNDOC
4113 (stdarg_optimize_hook,
4114 "Perform architecture specific checking of statements gimplified\
4115 from @code{VA_ARG_EXPR}. @var{stmt} is the statement. Returns true if\
4116 the statement doesn't need to be checked for @code{va_list} references.",
4117 bool, (struct stdarg_info *ai, const gimple *stmt), NULL)
4119 /* This target hook allows the operating system to override the DECL
4120 that represents the external variable that contains the stack
4121 protection guard variable. The type of this DECL is ptr_type_node. */
4122 DEFHOOK
4123 (stack_protect_guard,
4124 "This hook returns a @code{DECL} node for the external variable to use\n\
4125 for the stack protection guard. This variable is initialized by the\n\
4126 runtime to some random value and is used to initialize the guard value\n\
4127 that is placed at the top of the local stack frame. The type of this\n\
4128 variable must be @code{ptr_type_node}.\n\
4130 The default version of this hook creates a variable called\n\
4131 @samp{__stack_chk_guard}, which is normally defined in @file{libgcc2.c}.",
4132 tree, (void),
4133 default_stack_protect_guard)
4135 /* This target hook allows the operating system to override the CALL_EXPR
4136 that is invoked when a check vs the guard variable fails. */
4137 DEFHOOK
4138 (stack_protect_fail,
4139 "This hook returns a @code{CALL_EXPR} that alerts the runtime that the\n\
4140 stack protect guard variable has been modified. This expression should\n\
4141 involve a call to a @code{noreturn} function.\n\
4143 The default version of this hook invokes a function called\n\
4144 @samp{__stack_chk_fail}, taking no arguments. This function is\n\
4145 normally defined in @file{libgcc2.c}.",
4146 tree, (void),
4147 default_external_stack_protect_fail)
4149 /* This target hook allows the operating system to disable the default stack
4150 protector runtime support. */
4151 DEFHOOK
4152 (stack_protect_runtime_enabled_p,
4153 "Returns true if the target wants GCC's default stack protect runtime support,\
4154 otherwise return false. The default implementation always returns true.",
4155 bool, (void),
4156 hook_bool_void_true)
4158 DEFHOOK
4159 (have_speculation_safe_value,
4160 "This hook is used to determine the level of target support for\n\
4161 @code{__builtin_speculation_safe_value}. If called with an argument\n\
4162 of false, it returns true if the target has been modified to support\n\
4163 this builtin. If called with an argument of true, it returns true\n\
4164 if the target requires active mitigation execution might be speculative.\n\
4166 The default implementation returns false if the target does not define\n\
4167 a pattern named @code{speculation_barrier}. Else it returns true\n\
4168 for the first case and whether the pattern is enabled for the current\n\
4169 compilation for the second case.\n\
4171 For targets that have no processors that can execute instructions\n\
4172 speculatively an alternative implemenation of this hook is available:\n\
4173 simply redefine this hook to @code{speculation_safe_value_not_needed}\n\
4174 along with your other target hooks.",
4175 bool, (bool active), default_have_speculation_safe_value)
4177 DEFHOOK
4178 (speculation_safe_value,
4179 "This target hook can be used to generate a target-specific code\n\
4180 sequence that implements the @code{__builtin_speculation_safe_value}\n\
4181 built-in function. The function must always return @var{val} in\n\
4182 @var{result} in mode @var{mode} when the cpu is not executing\n\
4183 speculatively, but must never return that when speculating until it\n\
4184 is known that the speculation will not be unwound. The hook supports\n\
4185 two primary mechanisms for implementing the requirements. The first\n\
4186 is to emit a speculation barrier which forces the processor to wait\n\
4187 until all prior speculative operations have been resolved; the second\n\
4188 is to use a target-specific mechanism that can track the speculation\n\
4189 state and to return @var{failval} if it can determine that\n\
4190 speculation must be unwound at a later time.\n\
4192 The default implementation simply copies @var{val} to @var{result} and\n\
4193 emits a @code{speculation_barrier} instruction if that is defined.",
4194 rtx, (machine_mode mode, rtx result, rtx val, rtx failval),
4195 default_speculation_safe_value)
4198 DEFHOOK
4199 (can_use_doloop_p,
4200 "Return true if it is possible to use low-overhead loops (@code{doloop_end}\n\
4201 and @code{doloop_begin}) for a particular loop. @var{iterations} gives the\n\
4202 exact number of iterations, or 0 if not known. @var{iterations_max} gives\n\
4203 the maximum number of iterations, or 0 if not known. @var{loop_depth} is\n\
4204 the nesting depth of the loop, with 1 for innermost loops, 2 for loops that\n\
4205 contain innermost loops, and so on. @var{entered_at_top} is true if the\n\
4206 loop is only entered from the top.\n\
4208 This hook is only used if @code{doloop_end} is available. The default\n\
4209 implementation returns true. You can use @code{can_use_doloop_if_innermost}\n\
4210 if the loop must be the innermost, and if there are no other restrictions.",
4211 bool, (const widest_int &iterations, const widest_int &iterations_max,
4212 unsigned int loop_depth, bool entered_at_top),
4213 hook_bool_wint_wint_uint_bool_true)
4215 /* Returns NULL if target supports the insn within a doloop block,
4216 otherwise it returns an error message. */
4217 DEFHOOK
4218 (invalid_within_doloop,
4219 "\n\
4220 Take an instruction in @var{insn} and return NULL if it is valid within a\n\
4221 low-overhead loop, otherwise return a string explaining why doloop\n\
4222 could not be applied.\n\
4224 Many targets use special registers for low-overhead looping. For any\n\
4225 instruction that clobbers these this function should return a string indicating\n\
4226 the reason why the doloop could not be applied.\n\
4227 By default, the RTL loop optimizer does not use a present doloop pattern for\n\
4228 loops containing function calls or branch on table instructions.",
4229 const char *, (const rtx_insn *insn),
4230 default_invalid_within_doloop)
4232 /* Returns true for a legitimate combined insn. */
4233 DEFHOOK
4234 (legitimate_combined_insn,
4235 "Take an instruction in @var{insn} and return @code{false} if the instruction\
4236 is not appropriate as a combination of two or more instructions. The\
4237 default is to accept all instructions.",
4238 bool, (rtx_insn *insn),
4239 hook_bool_rtx_insn_true)
4241 DEFHOOK
4242 (valid_dllimport_attribute_p,
4243 "@var{decl} is a variable or function with @code{__attribute__((dllimport))}\
4244 specified. Use this hook if the target needs to add extra validation\
4245 checks to @code{handle_dll_attribute}.",
4246 bool, (const_tree decl),
4247 hook_bool_const_tree_true)
4249 /* If non-zero, align constant anchors in CSE to a multiple of this
4250 value. */
4251 DEFHOOKPOD
4252 (const_anchor,
4253 "On some architectures it can take multiple instructions to synthesize\n\
4254 a constant. If there is another constant already in a register that\n\
4255 is close enough in value then it is preferable that the new constant\n\
4256 is computed from this register using immediate addition or\n\
4257 subtraction. We accomplish this through CSE. Besides the value of\n\
4258 the constant we also add a lower and an upper constant anchor to the\n\
4259 available expressions. These are then queried when encountering new\n\
4260 constants. The anchors are computed by rounding the constant up and\n\
4261 down to a multiple of the value of @code{TARGET_CONST_ANCHOR}.\n\
4262 @code{TARGET_CONST_ANCHOR} should be the maximum positive value\n\
4263 accepted by immediate-add plus one. We currently assume that the\n\
4264 value of @code{TARGET_CONST_ANCHOR} is a power of 2. For example, on\n\
4265 MIPS, where add-immediate takes a 16-bit signed value,\n\
4266 @code{TARGET_CONST_ANCHOR} is set to @samp{0x8000}. The default value\n\
4267 is zero, which disables this optimization.",
4268 unsigned HOST_WIDE_INT, 0)
4270 /* Defines, which target-dependent bits (upper 16) are used by port */
4271 DEFHOOK
4272 (memmodel_check,
4273 "Validate target specific memory model mask bits. When NULL no target specific\n\
4274 memory model bits are allowed.",
4275 unsigned HOST_WIDE_INT, (unsigned HOST_WIDE_INT val), NULL)
4277 /* Defines an offset bitwise ored into shifted address to get corresponding
4278 Address Sanitizer shadow address, or -1 if Address Sanitizer is not
4279 supported by the target. */
4280 DEFHOOK
4281 (asan_shadow_offset,
4282 "Return the offset bitwise ored into shifted address to get corresponding\n\
4283 Address Sanitizer shadow memory address. NULL if Address Sanitizer is not\n\
4284 supported by the target.",
4285 unsigned HOST_WIDE_INT, (void),
4286 NULL)
4288 /* Functions relating to calls - argument passing, returns, etc. */
4289 /* Members of struct call have no special macro prefix. */
4290 HOOK_VECTOR (TARGET_CALLS, calls)
4292 DEFHOOK
4293 (promote_function_mode,
4294 "Like @code{PROMOTE_MODE}, but it is applied to outgoing function arguments or\n\
4295 function return values. The target hook should return the new mode\n\
4296 and possibly change @code{*@var{punsignedp}} if the promotion should\n\
4297 change signedness. This function is called only for scalar @emph{or\n\
4298 pointer} types.\n\
4300 @var{for_return} allows to distinguish the promotion of arguments and\n\
4301 return values. If it is @code{1}, a return value is being promoted and\n\
4302 @code{TARGET_FUNCTION_VALUE} must perform the same promotions done here.\n\
4303 If it is @code{2}, the returned mode should be that of the register in\n\
4304 which an incoming parameter is copied, or the outgoing result is computed;\n\
4305 then the hook should return the same mode as @code{promote_mode}, though\n\
4306 the signedness may be different.\n\
4308 @var{type} can be NULL when promoting function arguments of libcalls.\n\
4310 The default is to not promote arguments and return values. You can\n\
4311 also define the hook to @code{default_promote_function_mode_always_promote}\n\
4312 if you would like to apply the same rules given by @code{PROMOTE_MODE}.",
4313 machine_mode, (const_tree type, machine_mode mode, int *punsignedp,
4314 const_tree funtype, int for_return),
4315 default_promote_function_mode)
4317 DEFHOOK
4318 (promote_prototypes,
4319 "This target hook returns @code{true} if an argument declared in a\n\
4320 prototype as an integral type smaller than @code{int} should actually be\n\
4321 passed as an @code{int}. In addition to avoiding errors in certain\n\
4322 cases of mismatch, it also makes for better code on certain machines.\n\
4323 The default is to not promote prototypes.",
4324 bool, (const_tree fntype),
4325 hook_bool_const_tree_false)
4327 DEFHOOK
4328 (struct_value_rtx,
4329 "This target hook should return the location of the structure value\n\
4330 address (normally a @code{mem} or @code{reg}), or 0 if the address is\n\
4331 passed as an ``invisible'' first argument. Note that @var{fndecl} may\n\
4332 be @code{NULL}, for libcalls. You do not need to define this target\n\
4333 hook if the address is always passed as an ``invisible'' first\n\
4334 argument.\n\
4336 On some architectures the place where the structure value address\n\
4337 is found by the called function is not the same place that the\n\
4338 caller put it. This can be due to register windows, or it could\n\
4339 be because the function prologue moves it to a different place.\n\
4340 @var{incoming} is @code{1} or @code{2} when the location is needed in\n\
4341 the context of the called function, and @code{0} in the context of\n\
4342 the caller.\n\
4344 If @var{incoming} is nonzero and the address is to be found on the\n\
4345 stack, return a @code{mem} which refers to the frame pointer. If\n\
4346 @var{incoming} is @code{2}, the result is being used to fetch the\n\
4347 structure value address at the beginning of a function. If you need\n\
4348 to emit adjusting code, you should do it at this point.",
4349 rtx, (tree fndecl, int incoming),
4350 hook_rtx_tree_int_null)
4352 DEFHOOKPOD
4353 (omit_struct_return_reg,
4354 "Normally, when a function returns a structure by memory, the address\n\
4355 is passed as an invisible pointer argument, but the compiler also\n\
4356 arranges to return the address from the function like it would a normal\n\
4357 pointer return value. Define this to true if that behavior is\n\
4358 undesirable on your target.",
4359 bool, false)
4361 DEFHOOK
4362 (return_in_memory,
4363 "This target hook should return a nonzero value to say to return the\n\
4364 function value in memory, just as large structures are always returned.\n\
4365 Here @var{type} will be the data type of the value, and @var{fntype}\n\
4366 will be the type of the function doing the returning, or @code{NULL} for\n\
4367 libcalls.\n\
4369 Note that values of mode @code{BLKmode} must be explicitly handled\n\
4370 by this function. Also, the option @option{-fpcc-struct-return}\n\
4371 takes effect regardless of this macro. On most systems, it is\n\
4372 possible to leave the hook undefined; this causes a default\n\
4373 definition to be used, whose value is the constant 1 for @code{BLKmode}\n\
4374 values, and 0 otherwise.\n\
4376 Do not use this hook to indicate that structures and unions should always\n\
4377 be returned in memory. You should instead use @code{DEFAULT_PCC_STRUCT_RETURN}\n\
4378 to indicate this.",
4379 bool, (const_tree type, const_tree fntype),
4380 default_return_in_memory)
4382 DEFHOOK
4383 (return_in_msb,
4384 "This hook should return true if values of type @var{type} are returned\n\
4385 at the most significant end of a register (in other words, if they are\n\
4386 padded at the least significant end). You can assume that @var{type}\n\
4387 is returned in a register; the caller is required to check this.\n\
4389 Note that the register provided by @code{TARGET_FUNCTION_VALUE} must\n\
4390 be able to hold the complete return value. For example, if a 1-, 2-\n\
4391 or 3-byte structure is returned at the most significant end of a\n\
4392 4-byte register, @code{TARGET_FUNCTION_VALUE} should provide an\n\
4393 @code{SImode} rtx.",
4394 bool, (const_tree type),
4395 hook_bool_const_tree_false)
4397 /* Return true if a parameter must be passed by reference. TYPE may
4398 be null if this is a libcall. CA may be null if this query is
4399 from __builtin_va_arg. */
4400 DEFHOOK
4401 (pass_by_reference,
4402 "This target hook should return @code{true} if an argument at the\n\
4403 position indicated by @var{cum} should be passed by reference. This\n\
4404 predicate is queried after target independent reasons for being\n\
4405 passed by reference, such as @code{TREE_ADDRESSABLE (type)}.\n\
4407 If the hook returns true, a copy of that argument is made in memory and a\n\
4408 pointer to the argument is passed instead of the argument itself.\n\
4409 The pointer is passed in whatever way is appropriate for passing a pointer\n\
4410 to that type.",
4411 bool,
4412 (cumulative_args_t cum, machine_mode mode, const_tree type, bool named),
4413 hook_bool_CUMULATIVE_ARGS_mode_tree_bool_false)
4415 DEFHOOK
4416 (expand_builtin_saveregs,
4417 "If defined, this hook produces the machine-specific code for a call to\n\
4418 @code{__builtin_saveregs}. This code will be moved to the very\n\
4419 beginning of the function, before any parameter access are made. The\n\
4420 return value of this function should be an RTX that contains the value\n\
4421 to use as the return of @code{__builtin_saveregs}.",
4422 rtx, (void),
4423 default_expand_builtin_saveregs)
4425 /* Returns pretend_argument_size. */
4426 DEFHOOK
4427 (setup_incoming_varargs,
4428 "This target hook offers an alternative to using\n\
4429 @code{__builtin_saveregs} and defining the hook\n\
4430 @code{TARGET_EXPAND_BUILTIN_SAVEREGS}. Use it to store the anonymous\n\
4431 register arguments into the stack so that all the arguments appear to\n\
4432 have been passed consecutively on the stack. Once this is done, you can\n\
4433 use the standard implementation of varargs that works for machines that\n\
4434 pass all their arguments on the stack.\n\
4436 The argument @var{args_so_far} points to the @code{CUMULATIVE_ARGS} data\n\
4437 structure, containing the values that are obtained after processing the\n\
4438 named arguments. The arguments @var{mode} and @var{type} describe the\n\
4439 last named argument---its machine mode and its data type as a tree node.\n\
4441 The target hook should do two things: first, push onto the stack all the\n\
4442 argument registers @emph{not} used for the named arguments, and second,\n\
4443 store the size of the data thus pushed into the @code{int}-valued\n\
4444 variable pointed to by @var{pretend_args_size}. The value that you\n\
4445 store here will serve as additional offset for setting up the stack\n\
4446 frame.\n\
4448 Because you must generate code to push the anonymous arguments at\n\
4449 compile time without knowing their data types,\n\
4450 @code{TARGET_SETUP_INCOMING_VARARGS} is only useful on machines that\n\
4451 have just a single category of argument register and use it uniformly\n\
4452 for all data types.\n\
4454 If the argument @var{second_time} is nonzero, it means that the\n\
4455 arguments of the function are being analyzed for the second time. This\n\
4456 happens for an inline function, which is not actually compiled until the\n\
4457 end of the source file. The hook @code{TARGET_SETUP_INCOMING_VARARGS} should\n\
4458 not generate any instructions in this case.",
4459 void, (cumulative_args_t args_so_far, machine_mode mode, tree type,
4460 int *pretend_args_size, int second_time),
4461 default_setup_incoming_varargs)
4463 DEFHOOK
4464 (load_bounds_for_arg,
4465 "This hook is used by expand pass to emit insn to load bounds of\n\
4466 @var{arg} passed in @var{slot}. Expand pass uses this hook in case\n\
4467 bounds of @var{arg} are not passed in register. If @var{slot} is a\n\
4468 memory, then bounds are loaded as for regular pointer loaded from\n\
4469 memory. If @var{slot} is not a memory then @var{slot_no} is an integer\n\
4470 constant holding number of the target dependent special slot which\n\
4471 should be used to obtain bounds. Hook returns RTX holding loaded bounds.",
4472 rtx, (rtx slot, rtx arg, rtx slot_no),
4473 default_load_bounds_for_arg)
4475 DEFHOOK
4476 (store_bounds_for_arg,
4477 "This hook is used by expand pass to emit insns to store @var{bounds} of\n\
4478 @var{arg} passed in @var{slot}. Expand pass uses this hook in case\n\
4479 @var{bounds} of @var{arg} are not passed in register. If @var{slot} is a\n\
4480 memory, then @var{bounds} are stored as for regular pointer stored in\n\
4481 memory. If @var{slot} is not a memory then @var{slot_no} is an integer\n\
4482 constant holding number of the target dependent special slot which\n\
4483 should be used to store @var{bounds}.",
4484 void, (rtx arg, rtx slot, rtx bounds, rtx slot_no),
4485 default_store_bounds_for_arg)
4487 DEFHOOK
4488 (load_returned_bounds,
4489 "This hook is used by expand pass to emit insn to load bounds\n\
4490 returned by function call in @var{slot}. Hook returns RTX holding\n\
4491 loaded bounds.",
4492 rtx, (rtx slot),
4493 default_load_returned_bounds)
4495 DEFHOOK
4496 (store_returned_bounds,
4497 "This hook is used by expand pass to emit insn to store @var{bounds}\n\
4498 returned by function call into @var{slot}.",
4499 void, (rtx slot, rtx bounds),
4500 default_store_returned_bounds)
4502 DEFHOOK
4503 (setup_incoming_vararg_bounds,
4504 "Use it to store bounds for anonymous register arguments stored\n\
4505 into the stack. Arguments meaning is similar to\n\
4506 @code{TARGET_SETUP_INCOMING_VARARGS}.",
4507 void, (cumulative_args_t args_so_far, machine_mode mode, tree type,
4508 int *pretend_args_size, int second_time),
4509 default_setup_incoming_vararg_bounds)
4511 DEFHOOK
4512 (call_args,
4513 "While generating RTL for a function call, this target hook is invoked once\n\
4514 for each argument passed to the function, either a register returned by\n\
4515 @code{TARGET_FUNCTION_ARG} or a memory location. It is called just\n\
4516 before the point where argument registers are stored. The type of the\n\
4517 function to be called is also passed as the second argument; it is\n\
4518 @code{NULL_TREE} for libcalls. The @code{TARGET_END_CALL_ARGS} hook is\n\
4519 invoked just after the code to copy the return reg has been emitted.\n\
4520 This functionality can be used to perform special setup of call argument\n\
4521 registers if a target needs it.\n\
4522 For functions without arguments, the hook is called once with @code{pc_rtx}\n\
4523 passed instead of an argument register.\n\
4524 Most ports do not need to implement anything for this hook.",
4525 void, (rtx, tree),
4526 hook_void_rtx_tree)
4528 DEFHOOK
4529 (end_call_args,
4530 "This target hook is invoked while generating RTL for a function call,\n\
4531 just after the point where the return reg is copied into a pseudo. It\n\
4532 signals that all the call argument and return registers for the just\n\
4533 emitted call are now no longer in use.\n\
4534 Most ports do not need to implement anything for this hook.",
4535 void, (void),
4536 hook_void_void)
4538 DEFHOOK
4539 (strict_argument_naming,
4540 "Define this hook to return @code{true} if the location where a function\n\
4541 argument is passed depends on whether or not it is a named argument.\n\
4543 This hook controls how the @var{named} argument to @code{TARGET_FUNCTION_ARG}\n\
4544 is set for varargs and stdarg functions. If this hook returns\n\
4545 @code{true}, the @var{named} argument is always true for named\n\
4546 arguments, and false for unnamed arguments. If it returns @code{false},\n\
4547 but @code{TARGET_PRETEND_OUTGOING_VARARGS_NAMED} returns @code{true},\n\
4548 then all arguments are treated as named. Otherwise, all named arguments\n\
4549 except the last are treated as named.\n\
4551 You need not define this hook if it always returns @code{false}.",
4552 bool, (cumulative_args_t ca),
4553 hook_bool_CUMULATIVE_ARGS_false)
4555 /* Returns true if we should use
4556 targetm.calls.setup_incoming_varargs() and/or
4557 targetm.calls.strict_argument_naming(). */
4558 DEFHOOK
4559 (pretend_outgoing_varargs_named,
4560 "If you need to conditionally change ABIs so that one works with\n\
4561 @code{TARGET_SETUP_INCOMING_VARARGS}, but the other works like neither\n\
4562 @code{TARGET_SETUP_INCOMING_VARARGS} nor @code{TARGET_STRICT_ARGUMENT_NAMING} was\n\
4563 defined, then define this hook to return @code{true} if\n\
4564 @code{TARGET_SETUP_INCOMING_VARARGS} is used, @code{false} otherwise.\n\
4565 Otherwise, you should not define this hook.",
4566 bool, (cumulative_args_t ca),
4567 default_pretend_outgoing_varargs_named)
4569 /* Given a complex type T, return true if a parameter of type T
4570 should be passed as two scalars. */
4571 DEFHOOK
4572 (split_complex_arg,
4573 "This hook should return true if parameter of type @var{type} are passed\n\
4574 as two scalar parameters. By default, GCC will attempt to pack complex\n\
4575 arguments into the target's word size. Some ABIs require complex arguments\n\
4576 to be split and treated as their individual components. For example, on\n\
4577 AIX64, complex floats should be passed in a pair of floating point\n\
4578 registers, even though a complex float would fit in one 64-bit floating\n\
4579 point register.\n\
4581 The default value of this hook is @code{NULL}, which is treated as always\n\
4582 false.",
4583 bool, (const_tree type), NULL)
4585 /* Return true if type T, mode MODE, may not be passed in registers,
4586 but must be passed on the stack. */
4587 /* ??? This predicate should be applied strictly after pass-by-reference.
4588 Need audit to verify that this is the case. */
4589 DEFHOOK
4590 (must_pass_in_stack,
4591 "This target hook should return @code{true} if we should not pass @var{type}\n\
4592 solely in registers. The file @file{expr.h} defines a\n\
4593 definition that is usually appropriate, refer to @file{expr.h} for additional\n\
4594 documentation.",
4595 bool, (machine_mode mode, const_tree type),
4596 must_pass_in_stack_var_size_or_pad)
4598 /* Return true if type TYPE, mode MODE, which is passed by reference,
4599 should have the object copy generated by the callee rather than
4600 the caller. It is never called for TYPE requiring constructors. */
4601 DEFHOOK
4602 (callee_copies,
4603 "The function argument described by the parameters to this hook is\n\
4604 known to be passed by reference. The hook should return true if the\n\
4605 function argument should be copied by the callee instead of copied\n\
4606 by the caller.\n\
4608 For any argument for which the hook returns true, if it can be\n\
4609 determined that the argument is not modified, then a copy need\n\
4610 not be generated.\n\
4612 The default version of this hook always returns false.",
4613 bool,
4614 (cumulative_args_t cum, machine_mode mode, const_tree type, bool named),
4615 hook_bool_CUMULATIVE_ARGS_mode_tree_bool_false)
4617 /* Return zero for arguments passed entirely on the stack or entirely
4618 in registers. If passed in both, return the number of bytes passed
4619 in registers; the balance is therefore passed on the stack. */
4620 DEFHOOK
4621 (arg_partial_bytes,
4622 "This target hook returns the number of bytes at the beginning of an\n\
4623 argument that must be put in registers. The value must be zero for\n\
4624 arguments that are passed entirely in registers or that are entirely\n\
4625 pushed on the stack.\n\
4627 On some machines, certain arguments must be passed partially in\n\
4628 registers and partially in memory. On these machines, typically the\n\
4629 first few words of arguments are passed in registers, and the rest\n\
4630 on the stack. If a multi-word argument (a @code{double} or a\n\
4631 structure) crosses that boundary, its first few words must be passed\n\
4632 in registers and the rest must be pushed. This macro tells the\n\
4633 compiler when this occurs, and how many bytes should go in registers.\n\
4635 @code{TARGET_FUNCTION_ARG} for these arguments should return the first\n\
4636 register to be used by the caller for this argument; likewise\n\
4637 @code{TARGET_FUNCTION_INCOMING_ARG}, for the called function.",
4638 int, (cumulative_args_t cum, machine_mode mode, tree type, bool named),
4639 hook_int_CUMULATIVE_ARGS_mode_tree_bool_0)
4641 /* Update the state in CA to advance past an argument in the
4642 argument list. The values MODE, TYPE, and NAMED describe that
4643 argument. */
4644 DEFHOOK
4645 (function_arg_advance,
4646 "This hook updates the summarizer variable pointed to by @var{ca} to\n\
4647 advance past an argument in the argument list. The values @var{mode},\n\
4648 @var{type} and @var{named} describe that argument. Once this is done,\n\
4649 the variable @var{cum} is suitable for analyzing the @emph{following}\n\
4650 argument with @code{TARGET_FUNCTION_ARG}, etc.\n\
4652 This hook need not do anything if the argument in question was passed\n\
4653 on the stack. The compiler knows how to track the amount of stack space\n\
4654 used for arguments without any special help.",
4655 void,
4656 (cumulative_args_t ca, machine_mode mode, const_tree type, bool named),
4657 default_function_arg_advance)
4659 DEFHOOK
4660 (function_arg_offset,
4661 "This hook returns the number of bytes to add to the offset of an\n\
4662 argument of type @var{type} and mode @var{mode} when passed in memory.\n\
4663 This is needed for the SPU, which passes @code{char} and @code{short}\n\
4664 arguments in the preferred slot that is in the middle of the quad word\n\
4665 instead of starting at the top. The default implementation returns 0.",
4666 HOST_WIDE_INT, (machine_mode mode, const_tree type),
4667 default_function_arg_offset)
4669 DEFHOOK
4670 (function_arg_padding,
4671 "This hook determines whether, and in which direction, to pad out\n\
4672 an argument of mode @var{mode} and type @var{type}. It returns\n\
4673 @code{PAD_UPWARD} to insert padding above the argument, @code{PAD_DOWNWARD}\n\
4674 to insert padding below the argument, or @code{PAD_NONE} to inhibit padding.\n\
4676 The @emph{amount} of padding is not controlled by this hook, but by\n\
4677 @code{TARGET_FUNCTION_ARG_ROUND_BOUNDARY}. It is always just enough\n\
4678 to reach the next multiple of that boundary.\n\
4680 This hook has a default definition that is right for most systems.\n\
4681 For little-endian machines, the default is to pad upward. For\n\
4682 big-endian machines, the default is to pad downward for an argument of\n\
4683 constant size shorter than an @code{int}, and upward otherwise.",
4684 pad_direction, (machine_mode mode, const_tree type),
4685 default_function_arg_padding)
4687 /* Return zero if the argument described by the state of CA should
4688 be placed on a stack, or a hard register in which to store the
4689 argument. The values MODE, TYPE, and NAMED describe that
4690 argument. */
4691 DEFHOOK
4692 (function_arg,
4693 "Return an RTX indicating whether a function argument is passed in a\n\
4694 register and if so, which register.\n\
4696 The arguments are @var{ca}, which summarizes all the previous\n\
4697 arguments; @var{mode}, the machine mode of the argument; @var{type},\n\
4698 the data type of the argument as a tree node or 0 if that is not known\n\
4699 (which happens for C support library functions); and @var{named},\n\
4700 which is @code{true} for an ordinary argument and @code{false} for\n\
4701 nameless arguments that correspond to @samp{@dots{}} in the called\n\
4702 function's prototype. @var{type} can be an incomplete type if a\n\
4703 syntax error has previously occurred.\n\
4705 The return value is usually either a @code{reg} RTX for the hard\n\
4706 register in which to pass the argument, or zero to pass the argument\n\
4707 on the stack.\n\
4709 The return value can be a @code{const_int} which means argument is\n\
4710 passed in a target specific slot with specified number. Target hooks\n\
4711 should be used to store or load argument in such case. See\n\
4712 @code{TARGET_STORE_BOUNDS_FOR_ARG} and @code{TARGET_LOAD_BOUNDS_FOR_ARG}\n\
4713 for more information.\n\
4715 The value of the expression can also be a @code{parallel} RTX@. This is\n\
4716 used when an argument is passed in multiple locations. The mode of the\n\
4717 @code{parallel} should be the mode of the entire argument. The\n\
4718 @code{parallel} holds any number of @code{expr_list} pairs; each one\n\
4719 describes where part of the argument is passed. In each\n\
4720 @code{expr_list} the first operand must be a @code{reg} RTX for the hard\n\
4721 register in which to pass this part of the argument, and the mode of the\n\
4722 register RTX indicates how large this part of the argument is. The\n\
4723 second operand of the @code{expr_list} is a @code{const_int} which gives\n\
4724 the offset in bytes into the entire argument of where this part starts.\n\
4725 As a special exception the first @code{expr_list} in the @code{parallel}\n\
4726 RTX may have a first operand of zero. This indicates that the entire\n\
4727 argument is also stored on the stack.\n\
4729 The last time this hook is called, it is called with @code{MODE ==\n\
4730 VOIDmode}, and its result is passed to the @code{call} or @code{call_value}\n\
4731 pattern as operands 2 and 3 respectively.\n\
4733 @cindex @file{stdarg.h} and register arguments\n\
4734 The usual way to make the ISO library @file{stdarg.h} work on a\n\
4735 machine where some arguments are usually passed in registers, is to\n\
4736 cause nameless arguments to be passed on the stack instead. This is\n\
4737 done by making @code{TARGET_FUNCTION_ARG} return 0 whenever\n\
4738 @var{named} is @code{false}.\n\
4740 @cindex @code{TARGET_MUST_PASS_IN_STACK}, and @code{TARGET_FUNCTION_ARG}\n\
4741 @cindex @code{REG_PARM_STACK_SPACE}, and @code{TARGET_FUNCTION_ARG}\n\
4742 You may use the hook @code{targetm.calls.must_pass_in_stack}\n\
4743 in the definition of this macro to determine if this argument is of a\n\
4744 type that must be passed in the stack. If @code{REG_PARM_STACK_SPACE}\n\
4745 is not defined and @code{TARGET_FUNCTION_ARG} returns nonzero for such an\n\
4746 argument, the compiler will abort. If @code{REG_PARM_STACK_SPACE} is\n\
4747 defined, the argument will be computed in the stack and then loaded into\n\
4748 a register.",
4749 rtx, (cumulative_args_t ca, machine_mode mode, const_tree type,
4750 bool named),
4751 default_function_arg)
4753 DEFHOOK
4754 (function_incoming_arg,
4755 "Define this hook if the caller and callee on the target have different\n\
4756 views of where arguments are passed. Also define this hook if there are\n\
4757 functions that are never directly called, but are invoked by the hardware\n\
4758 and which have nonstandard calling conventions.\n\
4760 In this case @code{TARGET_FUNCTION_ARG} computes the register in\n\
4761 which the caller passes the value, and\n\
4762 @code{TARGET_FUNCTION_INCOMING_ARG} should be defined in a similar\n\
4763 fashion to tell the function being called where the arguments will\n\
4764 arrive.\n\
4766 @code{TARGET_FUNCTION_INCOMING_ARG} can also return arbitrary address\n\
4767 computation using hard register, which can be forced into a register,\n\
4768 so that it can be used to pass special arguments.\n\
4770 If @code{TARGET_FUNCTION_INCOMING_ARG} is not defined,\n\
4771 @code{TARGET_FUNCTION_ARG} serves both purposes.",
4772 rtx, (cumulative_args_t ca, machine_mode mode, const_tree type,
4773 bool named),
4774 default_function_incoming_arg)
4776 DEFHOOK
4777 (function_arg_boundary,
4778 "This hook returns the alignment boundary, in bits, of an argument\n\
4779 with the specified mode and type. The default hook returns\n\
4780 @code{PARM_BOUNDARY} for all arguments.",
4781 unsigned int, (machine_mode mode, const_tree type),
4782 default_function_arg_boundary)
4784 DEFHOOK
4785 (function_arg_round_boundary,
4786 "Normally, the size of an argument is rounded up to @code{PARM_BOUNDARY},\n\
4787 which is the default value for this hook. You can define this hook to\n\
4788 return a different value if an argument size must be rounded to a larger\n\
4789 value.",
4790 unsigned int, (machine_mode mode, const_tree type),
4791 default_function_arg_round_boundary)
4793 /* Return the diagnostic message string if function without a prototype
4794 is not allowed for this 'val' argument; NULL otherwise. */
4795 DEFHOOK
4796 (invalid_arg_for_unprototyped_fn,
4797 "If defined, this macro returns the diagnostic message when it is\n\
4798 illegal to pass argument @var{val} to function @var{funcdecl}\n\
4799 with prototype @var{typelist}.",
4800 const char *, (const_tree typelist, const_tree funcdecl, const_tree val),
4801 hook_invalid_arg_for_unprototyped_fn)
4803 /* Return an rtx for the return value location of the function
4804 specified by FN_DECL_OR_TYPE with a return type of RET_TYPE. */
4805 DEFHOOK
4806 (function_value,
4807 "\n\
4808 Define this to return an RTX representing the place where a function\n\
4809 returns or receives a value of data type @var{ret_type}, a tree node\n\
4810 representing a data type. @var{fn_decl_or_type} is a tree node\n\
4811 representing @code{FUNCTION_DECL} or @code{FUNCTION_TYPE} of a\n\
4812 function being called. If @var{outgoing} is false, the hook should\n\
4813 compute the register in which the caller will see the return value.\n\
4814 Otherwise, the hook should return an RTX representing the place where\n\
4815 a function returns a value.\n\
4817 On many machines, only @code{TYPE_MODE (@var{ret_type})} is relevant.\n\
4818 (Actually, on most machines, scalar values are returned in the same\n\
4819 place regardless of mode.) The value of the expression is usually a\n\
4820 @code{reg} RTX for the hard register where the return value is stored.\n\
4821 The value can also be a @code{parallel} RTX, if the return value is in\n\
4822 multiple places. See @code{TARGET_FUNCTION_ARG} for an explanation of the\n\
4823 @code{parallel} form. Note that the callee will populate every\n\
4824 location specified in the @code{parallel}, but if the first element of\n\
4825 the @code{parallel} contains the whole return value, callers will use\n\
4826 that element as the canonical location and ignore the others. The m68k\n\
4827 port uses this type of @code{parallel} to return pointers in both\n\
4828 @samp{%a0} (the canonical location) and @samp{%d0}.\n\
4830 If @code{TARGET_PROMOTE_FUNCTION_RETURN} returns true, you must apply\n\
4831 the same promotion rules specified in @code{PROMOTE_MODE} if\n\
4832 @var{valtype} is a scalar type.\n\
4834 If the precise function being called is known, @var{func} is a tree\n\
4835 node (@code{FUNCTION_DECL}) for it; otherwise, @var{func} is a null\n\
4836 pointer. This makes it possible to use a different value-returning\n\
4837 convention for specific functions when all their calls are\n\
4838 known.\n\
4840 Some target machines have ``register windows'' so that the register in\n\
4841 which a function returns its value is not the same as the one in which\n\
4842 the caller sees the value. For such machines, you should return\n\
4843 different RTX depending on @var{outgoing}.\n\
4845 @code{TARGET_FUNCTION_VALUE} is not used for return values with\n\
4846 aggregate data types, because these are returned in another way. See\n\
4847 @code{TARGET_STRUCT_VALUE_RTX} and related macros, below.",
4848 rtx, (const_tree ret_type, const_tree fn_decl_or_type, bool outgoing),
4849 default_function_value)
4851 /* Return the rtx for the result of a libcall of mode MODE,
4852 calling the function FN_NAME. */
4853 DEFHOOK
4854 (libcall_value,
4855 "Define this hook if the back-end needs to know the name of the libcall\n\
4856 function in order to determine where the result should be returned.\n\
4858 The mode of the result is given by @var{mode} and the name of the called\n\
4859 library function is given by @var{fun}. The hook should return an RTX\n\
4860 representing the place where the library function result will be returned.\n\
4862 If this hook is not defined, then LIBCALL_VALUE will be used.",
4863 rtx, (machine_mode mode, const_rtx fun),
4864 default_libcall_value)
4866 /* Return true if REGNO is a possible register number for
4867 a function value as seen by the caller. */
4868 DEFHOOK
4869 (function_value_regno_p,
4870 "A target hook that return @code{true} if @var{regno} is the number of a hard\n\
4871 register in which the values of called function may come back.\n\
4873 A register whose use for returning values is limited to serving as the\n\
4874 second of a pair (for a value of type @code{double}, say) need not be\n\
4875 recognized by this target hook.\n\
4877 If the machine has register windows, so that the caller and the called\n\
4878 function use different registers for the return value, this target hook\n\
4879 should recognize only the caller's register numbers.\n\
4881 If this hook is not defined, then FUNCTION_VALUE_REGNO_P will be used.",
4882 bool, (const unsigned int regno),
4883 default_function_value_regno_p)
4885 /* ??? Documenting this hook requires a GFDL license grant. */
4886 DEFHOOK_UNDOC
4887 (internal_arg_pointer,
4888 "Return an rtx for the argument pointer incoming to the\
4889 current function.",
4890 rtx, (void),
4891 default_internal_arg_pointer)
4893 /* Update the current function stack boundary if needed. */
4894 DEFHOOK
4895 (update_stack_boundary,
4896 "Define this macro to update the current function stack boundary if\n\
4897 necessary.",
4898 void, (void), NULL)
4900 /* Handle stack alignment and return an rtx for Dynamic Realign
4901 Argument Pointer if necessary. */
4902 DEFHOOK
4903 (get_drap_rtx,
4904 "This hook should return an rtx for Dynamic Realign Argument Pointer (DRAP) if a\n\
4905 different argument pointer register is needed to access the function's\n\
4906 argument list due to stack realignment. Return @code{NULL} if no DRAP\n\
4907 is needed.",
4908 rtx, (void), NULL)
4910 /* Return true if all function parameters should be spilled to the
4911 stack. */
4912 DEFHOOK
4913 (allocate_stack_slots_for_args,
4914 "When optimization is disabled, this hook indicates whether or not\n\
4915 arguments should be allocated to stack slots. Normally, GCC allocates\n\
4916 stacks slots for arguments when not optimizing in order to make\n\
4917 debugging easier. However, when a function is declared with\n\
4918 @code{__attribute__((naked))}, there is no stack frame, and the compiler\n\
4919 cannot safely move arguments from the registers in which they are passed\n\
4920 to the stack. Therefore, this hook should return true in general, but\n\
4921 false for naked functions. The default implementation always returns true.",
4922 bool, (void),
4923 hook_bool_void_true)
4925 /* Return an rtx for the static chain for FNDECL_OR_TYPE. If INCOMING_P
4926 is true, then it should be for the callee; otherwise for the caller. */
4927 DEFHOOK
4928 (static_chain,
4929 "This hook replaces the use of @code{STATIC_CHAIN_REGNUM} et al for\n\
4930 targets that may use different static chain locations for different\n\
4931 nested functions. This may be required if the target has function\n\
4932 attributes that affect the calling conventions of the function and\n\
4933 those calling conventions use different static chain locations.\n\
4935 The default version of this hook uses @code{STATIC_CHAIN_REGNUM} et al.\n\
4937 If the static chain is passed in memory, this hook should be used to\n\
4938 provide rtx giving @code{mem} expressions that denote where they are stored.\n\
4939 Often the @code{mem} expression as seen by the caller will be at an offset\n\
4940 from the stack pointer and the @code{mem} expression as seen by the callee\n\
4941 will be at an offset from the frame pointer.\n\
4942 @findex stack_pointer_rtx\n\
4943 @findex frame_pointer_rtx\n\
4944 @findex arg_pointer_rtx\n\
4945 The variables @code{stack_pointer_rtx}, @code{frame_pointer_rtx}, and\n\
4946 @code{arg_pointer_rtx} will have been initialized and should be used\n\
4947 to refer to those items.",
4948 rtx, (const_tree fndecl_or_type, bool incoming_p),
4949 default_static_chain)
4951 /* Fill in the trampoline at MEM with a call to FNDECL and a
4952 static chain value of CHAIN. */
4953 DEFHOOK
4954 (trampoline_init,
4955 "This hook is called to initialize a trampoline.\n\
4956 @var{m_tramp} is an RTX for the memory block for the trampoline; @var{fndecl}\n\
4957 is the @code{FUNCTION_DECL} for the nested function; @var{static_chain} is an\n\
4958 RTX for the static chain value that should be passed to the function\n\
4959 when it is called.\n\
4961 If the target defines @code{TARGET_ASM_TRAMPOLINE_TEMPLATE}, then the\n\
4962 first thing this hook should do is emit a block move into @var{m_tramp}\n\
4963 from the memory block returned by @code{assemble_trampoline_template}.\n\
4964 Note that the block move need only cover the constant parts of the\n\
4965 trampoline. If the target isolates the variable parts of the trampoline\n\
4966 to the end, not all @code{TRAMPOLINE_SIZE} bytes need be copied.\n\
4968 If the target requires any other actions, such as flushing caches or\n\
4969 enabling stack execution, these actions should be performed after\n\
4970 initializing the trampoline proper.",
4971 void, (rtx m_tramp, tree fndecl, rtx static_chain),
4972 default_trampoline_init)
4974 /* Adjust the address of the trampoline in a target-specific way. */
4975 DEFHOOK
4976 (trampoline_adjust_address,
4977 "This hook should perform any machine-specific adjustment in\n\
4978 the address of the trampoline. Its argument contains the address of the\n\
4979 memory block that was passed to @code{TARGET_TRAMPOLINE_INIT}. In case\n\
4980 the address to be used for a function call should be different from the\n\
4981 address at which the template was stored, the different address should\n\
4982 be returned; otherwise @var{addr} should be returned unchanged.\n\
4983 If this hook is not defined, @var{addr} will be used for function calls.",
4984 rtx, (rtx addr), NULL)
4986 DEFHOOKPOD
4987 (custom_function_descriptors,
4988 "If the target can use GCC's generic descriptor mechanism for nested\n\
4989 functions, define this hook to a power of 2 representing an unused bit\n\
4990 in function pointers which can be used to differentiate descriptors at\n\
4991 run time. This value gives the number of bytes by which descriptor\n\
4992 pointers are misaligned compared to function pointers. For example, on\n\
4993 targets that require functions to be aligned to a 4-byte boundary, a\n\
4994 value of either 1 or 2 is appropriate unless the architecture already\n\
4995 reserves the bit for another purpose, such as on ARM.\n\
4997 Define this hook to 0 if the target implements ABI support for\n\
4998 function descriptors in its standard calling sequence, like for example\n\
4999 HPPA or IA-64.\n\
5001 Using descriptors for nested functions\n\
5002 eliminates the need for trampolines that reside on the stack and require\n\
5003 it to be made executable.",\
5004 int, -1)
5006 /* Return the number of bytes of its own arguments that a function
5007 pops on returning, or 0 if the function pops no arguments and the
5008 caller must therefore pop them all after the function returns. */
5009 /* ??? tm.texi has no types for the parameters. */
5010 DEFHOOK
5011 (return_pops_args,
5012 "This target hook returns the number of bytes of its own arguments that\n\
5013 a function pops on returning, or 0 if the function pops no arguments\n\
5014 and the caller must therefore pop them all after the function returns.\n\
5016 @var{fundecl} is a C variable whose value is a tree node that describes\n\
5017 the function in question. Normally it is a node of type\n\
5018 @code{FUNCTION_DECL} that describes the declaration of the function.\n\
5019 From this you can obtain the @code{DECL_ATTRIBUTES} of the function.\n\
5021 @var{funtype} is a C variable whose value is a tree node that\n\
5022 describes the function in question. Normally it is a node of type\n\
5023 @code{FUNCTION_TYPE} that describes the data type of the function.\n\
5024 From this it is possible to obtain the data types of the value and\n\
5025 arguments (if known).\n\
5027 When a call to a library function is being considered, @var{fundecl}\n\
5028 will contain an identifier node for the library function. Thus, if\n\
5029 you need to distinguish among various library functions, you can do so\n\
5030 by their names. Note that ``library function'' in this context means\n\
5031 a function used to perform arithmetic, whose name is known specially\n\
5032 in the compiler and was not mentioned in the C code being compiled.\n\
5034 @var{size} is the number of bytes of arguments passed on the\n\
5035 stack. If a variable number of bytes is passed, it is zero, and\n\
5036 argument popping will always be the responsibility of the calling function.\n\
5038 On the VAX, all functions always pop their arguments, so the definition\n\
5039 of this macro is @var{size}. On the 68000, using the standard\n\
5040 calling convention, no functions pop their arguments, so the value of\n\
5041 the macro is always 0 in this case. But an alternative calling\n\
5042 convention is available in which functions that take a fixed number of\n\
5043 arguments pop them but other functions (such as @code{printf}) pop\n\
5044 nothing (the caller pops all). When this convention is in use,\n\
5045 @var{funtype} is examined to determine whether a function takes a fixed\n\
5046 number of arguments.",
5047 poly_int64, (tree fundecl, tree funtype, poly_int64 size),
5048 default_return_pops_args)
5050 /* Return a mode wide enough to copy any function value that might be
5051 returned. */
5052 DEFHOOK
5053 (get_raw_result_mode,
5054 "This target hook returns the mode to be used when accessing raw return\
5055 registers in @code{__builtin_return}. Define this macro if the value\
5056 in @var{reg_raw_mode} is not correct.",
5057 fixed_size_mode, (int regno),
5058 default_get_reg_raw_mode)
5060 /* Return a mode wide enough to copy any argument value that might be
5061 passed. */
5062 DEFHOOK
5063 (get_raw_arg_mode,
5064 "This target hook returns the mode to be used when accessing raw argument\
5065 registers in @code{__builtin_apply_args}. Define this macro if the value\
5066 in @var{reg_raw_mode} is not correct.",
5067 fixed_size_mode, (int regno),
5068 default_get_reg_raw_mode)
5070 /* Return true if a type is an empty record. */
5071 DEFHOOK
5072 (empty_record_p,
5073 "This target hook returns true if the type is an empty record. The default\n\
5074 is to return @code{false}.",
5075 bool, (const_tree type),
5076 hook_bool_const_tree_false)
5078 /* Warn about the change in empty class parameter passing ABI. */
5079 DEFHOOK
5080 (warn_parameter_passing_abi,
5081 "This target hook warns about the change in empty class parameter passing\n\
5082 ABI.",
5083 void, (cumulative_args_t ca, tree type),
5084 hook_void_CUMULATIVE_ARGS_tree)
5086 HOOK_VECTOR_END (calls)
5088 DEFHOOK
5089 (use_pseudo_pic_reg,
5090 "This hook should return 1 in case pseudo register should be created\n\
5091 for pic_offset_table_rtx during function expand.",
5092 bool, (void),
5093 hook_bool_void_false)
5095 DEFHOOK
5096 (init_pic_reg,
5097 "Perform a target dependent initialization of pic_offset_table_rtx.\n\
5098 This hook is called at the start of register allocation.",
5099 void, (void),
5100 hook_void_void)
5102 /* Return the diagnostic message string if conversion from FROMTYPE
5103 to TOTYPE is not allowed, NULL otherwise. */
5104 DEFHOOK
5105 (invalid_conversion,
5106 "If defined, this macro returns the diagnostic message when it is\n\
5107 invalid to convert from @var{fromtype} to @var{totype}, or @code{NULL}\n\
5108 if validity should be determined by the front end.",
5109 const char *, (const_tree fromtype, const_tree totype),
5110 hook_constcharptr_const_tree_const_tree_null)
5112 /* Return the diagnostic message string if the unary operation OP is
5113 not permitted on TYPE, NULL otherwise. */
5114 DEFHOOK
5115 (invalid_unary_op,
5116 "If defined, this macro returns the diagnostic message when it is\n\
5117 invalid to apply operation @var{op} (where unary plus is denoted by\n\
5118 @code{CONVERT_EXPR}) to an operand of type @var{type}, or @code{NULL}\n\
5119 if validity should be determined by the front end.",
5120 const char *, (int op, const_tree type),
5121 hook_constcharptr_int_const_tree_null)
5123 /* Return the diagnostic message string if the binary operation OP
5124 is not permitted on TYPE1 and TYPE2, NULL otherwise. */
5125 DEFHOOK
5126 (invalid_binary_op,
5127 "If defined, this macro returns the diagnostic message when it is\n\
5128 invalid to apply operation @var{op} to operands of types @var{type1}\n\
5129 and @var{type2}, or @code{NULL} if validity should be determined by\n\
5130 the front end.",
5131 const char *, (int op, const_tree type1, const_tree type2),
5132 hook_constcharptr_int_const_tree_const_tree_null)
5134 /* If values of TYPE are promoted to some other type when used in
5135 expressions (analogous to the integer promotions), return that type,
5136 or NULL_TREE otherwise. */
5137 DEFHOOK
5138 (promoted_type,
5139 "If defined, this target hook returns the type to which values of\n\
5140 @var{type} should be promoted when they appear in expressions,\n\
5141 analogous to the integer promotions, or @code{NULL_TREE} to use the\n\
5142 front end's normal promotion rules. This hook is useful when there are\n\
5143 target-specific types with special promotion rules.\n\
5144 This is currently used only by the C and C++ front ends.",
5145 tree, (const_tree type),
5146 hook_tree_const_tree_null)
5148 /* Convert EXPR to TYPE, if target-specific types with special conversion
5149 rules are involved. Return the converted expression, or NULL to apply
5150 the standard conversion rules. */
5151 DEFHOOK
5152 (convert_to_type,
5153 "If defined, this hook returns the result of converting @var{expr} to\n\
5154 @var{type}. It should return the converted expression,\n\
5155 or @code{NULL_TREE} to apply the front end's normal conversion rules.\n\
5156 This hook is useful when there are target-specific types with special\n\
5157 conversion rules.\n\
5158 This is currently used only by the C and C++ front ends.",
5159 tree, (tree type, tree expr),
5160 hook_tree_tree_tree_null)
5162 DEFHOOK
5163 (can_change_mode_class,
5164 "This hook returns true if it is possible to bitcast values held in\n\
5165 registers of class @var{rclass} from mode @var{from} to mode @var{to}\n\
5166 and if doing so preserves the low-order bits that are common to both modes.\n\
5167 The result is only meaningful if @var{rclass} has registers that can hold\n\
5168 both @code{from} and @code{to}. The default implementation returns true.\n\
5170 As an example of when such bitcasting is invalid, loading 32-bit integer or\n\
5171 floating-point objects into floating-point registers on Alpha extends them\n\
5172 to 64 bits. Therefore loading a 64-bit object and then storing it as a\n\
5173 32-bit object does not store the low-order 32 bits, as would be the case\n\
5174 for a normal register. Therefore, @file{alpha.h} defines\n\
5175 @code{TARGET_CAN_CHANGE_MODE_CLASS} to return:\n\
5177 @smallexample\n\
5178 (GET_MODE_SIZE (from) == GET_MODE_SIZE (to)\n\
5179 || !reg_classes_intersect_p (FLOAT_REGS, rclass))\n\
5180 @end smallexample\n\
5182 Even if storing from a register in mode @var{to} would be valid,\n\
5183 if both @var{from} and @code{raw_reg_mode} for @var{rclass} are wider\n\
5184 than @code{word_mode}, then we must prevent @var{to} narrowing the\n\
5185 mode. This happens when the middle-end assumes that it can load\n\
5186 or store pieces of an @var{N}-word pseudo, and that the pseudo will\n\
5187 eventually be allocated to @var{N} @code{word_mode} hard registers.\n\
5188 Failure to prevent this kind of mode change will result in the\n\
5189 entire @code{raw_reg_mode} being modified instead of the partial\n\
5190 value that the middle-end intended.",
5191 bool, (machine_mode from, machine_mode to, reg_class_t rclass),
5192 hook_bool_mode_mode_reg_class_t_true)
5194 /* Change pseudo allocno class calculated by IRA. */
5195 DEFHOOK
5196 (ira_change_pseudo_allocno_class,
5197 "A target hook which can change allocno class for given pseudo from\n\
5198 allocno and best class calculated by IRA.\n\
5200 The default version of this target hook always returns given class.",
5201 reg_class_t, (int, reg_class_t, reg_class_t),
5202 default_ira_change_pseudo_allocno_class)
5204 /* Return true if we use LRA instead of reload. */
5205 DEFHOOK
5206 (lra_p,
5207 "A target hook which returns true if we use LRA instead of reload pass.\
5209 The default version of this target hook returns true. New ports\
5210 should use LRA, and existing ports are encouraged to convert.",
5211 bool, (void),
5212 default_lra_p)
5214 /* Return register priority of given hard regno for the current target. */
5215 DEFHOOK
5216 (register_priority,
5217 "A target hook which returns the register priority number to which the\
5218 register @var{hard_regno} belongs to. The bigger the number, the\
5219 more preferable the hard register usage (when all other conditions are\
5220 the same). This hook can be used to prefer some hard register over\
5221 others in LRA. For example, some x86-64 register usage needs\
5222 additional prefix which makes instructions longer. The hook can\
5223 return lower priority number for such registers make them less favorable\
5224 and as result making the generated code smaller.\
5226 The default version of this target hook returns always zero.",
5227 int, (int),
5228 default_register_priority)
5230 /* Return true if we need register usage leveling. */
5231 DEFHOOK
5232 (register_usage_leveling_p,
5233 "A target hook which returns true if we need register usage leveling.\
5234 That means if a few hard registers are equally good for the\
5235 assignment, we choose the least used hard register. The register\
5236 usage leveling may be profitable for some targets. Don't use the\
5237 usage leveling for targets with conditional execution or targets\
5238 with big register files as it hurts if-conversion and cross-jumping\
5239 optimizations.\
5241 The default version of this target hook returns always false.",
5242 bool, (void),
5243 default_register_usage_leveling_p)
5245 /* Return true if maximal address displacement can be different. */
5246 DEFHOOK
5247 (different_addr_displacement_p,
5248 "A target hook which returns true if an address with the same structure\
5249 can have different maximal legitimate displacement. For example, the\
5250 displacement can depend on memory mode or on operand combinations in\
5251 the insn.\
5253 The default version of this target hook returns always false.",
5254 bool, (void),
5255 default_different_addr_displacement_p)
5257 /* Determine class for spilling pseudos of given mode into registers
5258 instead of memory. */
5259 DEFHOOK
5260 (spill_class,
5261 "This hook defines a class of registers which could be used for spilling\
5262 pseudos of the given mode and class, or @code{NO_REGS} if only memory\
5263 should be used. Not defining this hook is equivalent to returning\
5264 @code{NO_REGS} for all inputs.",
5265 reg_class_t, (reg_class_t, machine_mode),
5266 NULL)
5268 /* Determine an additional allocno class. */
5269 DEFHOOK
5270 (additional_allocno_class_p,
5271 "This hook should return @code{true} if given class of registers should\
5272 be an allocno class in any way. Usually RA uses only one register\
5273 class from all classes containing the same register set. In some\
5274 complicated cases, you need to have two or more such classes as\
5275 allocno ones for RA correct work. Not defining this hook is\
5276 equivalent to returning @code{false} for all inputs.",
5277 bool, (reg_class_t),
5278 hook_bool_reg_class_t_false)
5280 DEFHOOK
5281 (cstore_mode,
5282 "This hook defines the machine mode to use for the boolean result of\
5283 conditional store patterns. The ICODE argument is the instruction code\
5284 for the cstore being performed. Not definiting this hook is the same\
5285 as accepting the mode encoded into operand 0 of the cstore expander\
5286 patterns.",
5287 scalar_int_mode, (enum insn_code icode),
5288 default_cstore_mode)
5290 /* This target hook allows the backend to compute the register pressure
5291 classes to use. */
5292 DEFHOOK
5293 (compute_pressure_classes,
5294 "A target hook which lets a backend compute the set of pressure classes to\
5295 be used by those optimization passes which take register pressure into\
5296 account, as opposed to letting IRA compute them. It returns the number of\
5297 register classes stored in the array @var{pressure_classes}.",
5298 int, (enum reg_class *pressure_classes), NULL)
5300 /* True if a structure, union or array with MODE containing FIELD should
5301 be accessed using BLKmode. */
5302 DEFHOOK
5303 (member_type_forces_blk,
5304 "Return true if a structure, union or array containing @var{field} should\n\
5305 be accessed using @code{BLKMODE}.\n\
5307 If @var{field} is the only field in the structure, @var{mode} is its\n\
5308 mode, otherwise @var{mode} is VOIDmode. @var{mode} is provided in the\n\
5309 case where structures of one field would require the structure's mode to\n\
5310 retain the field's mode.\n\
5312 Normally, this is not needed.",
5313 bool, (const_tree field, machine_mode mode),
5314 default_member_type_forces_blk)
5316 /* See tree-ssa-math-opts.c:divmod_candidate_p for conditions
5317 that gate the divod transform. */
5318 DEFHOOK
5319 (expand_divmod_libfunc,
5320 "Define this hook for enabling divmod transform if the port does not have\n\
5321 hardware divmod insn but defines target-specific divmod libfuncs.",
5322 void, (rtx libfunc, machine_mode mode, rtx op0, rtx op1, rtx *quot, rtx *rem),
5323 NULL)
5325 /* Return the class for a secondary reload, and fill in extra information. */
5326 DEFHOOK
5327 (secondary_reload,
5328 "Many machines have some registers that cannot be copied directly to or\n\
5329 from memory or even from other types of registers. An example is the\n\
5330 @samp{MQ} register, which on most machines, can only be copied to or\n\
5331 from general registers, but not memory. Below, we shall be using the\n\
5332 term 'intermediate register' when a move operation cannot be performed\n\
5333 directly, but has to be done by copying the source into the intermediate\n\
5334 register first, and then copying the intermediate register to the\n\
5335 destination. An intermediate register always has the same mode as\n\
5336 source and destination. Since it holds the actual value being copied,\n\
5337 reload might apply optimizations to re-use an intermediate register\n\
5338 and eliding the copy from the source when it can determine that the\n\
5339 intermediate register still holds the required value.\n\
5341 Another kind of secondary reload is required on some machines which\n\
5342 allow copying all registers to and from memory, but require a scratch\n\
5343 register for stores to some memory locations (e.g., those with symbolic\n\
5344 address on the RT, and those with certain symbolic address on the SPARC\n\
5345 when compiling PIC)@. Scratch registers need not have the same mode\n\
5346 as the value being copied, and usually hold a different value than\n\
5347 that being copied. Special patterns in the md file are needed to\n\
5348 describe how the copy is performed with the help of the scratch register;\n\
5349 these patterns also describe the number, register class(es) and mode(s)\n\
5350 of the scratch register(s).\n\
5352 In some cases, both an intermediate and a scratch register are required.\n\
5354 For input reloads, this target hook is called with nonzero @var{in_p},\n\
5355 and @var{x} is an rtx that needs to be copied to a register of class\n\
5356 @var{reload_class} in @var{reload_mode}. For output reloads, this target\n\
5357 hook is called with zero @var{in_p}, and a register of class @var{reload_class}\n\
5358 needs to be copied to rtx @var{x} in @var{reload_mode}.\n\
5360 If copying a register of @var{reload_class} from/to @var{x} requires\n\
5361 an intermediate register, the hook @code{secondary_reload} should\n\
5362 return the register class required for this intermediate register.\n\
5363 If no intermediate register is required, it should return NO_REGS.\n\
5364 If more than one intermediate register is required, describe the one\n\
5365 that is closest in the copy chain to the reload register.\n\
5367 If scratch registers are needed, you also have to describe how to\n\
5368 perform the copy from/to the reload register to/from this\n\
5369 closest intermediate register. Or if no intermediate register is\n\
5370 required, but still a scratch register is needed, describe the\n\
5371 copy from/to the reload register to/from the reload operand @var{x}.\n\
5373 You do this by setting @code{sri->icode} to the instruction code of a pattern\n\
5374 in the md file which performs the move. Operands 0 and 1 are the output\n\
5375 and input of this copy, respectively. Operands from operand 2 onward are\n\
5376 for scratch operands. These scratch operands must have a mode, and a\n\
5377 single-register-class\n\
5378 @c [later: or memory]\n\
5379 output constraint.\n\
5381 When an intermediate register is used, the @code{secondary_reload}\n\
5382 hook will be called again to determine how to copy the intermediate\n\
5383 register to/from the reload operand @var{x}, so your hook must also\n\
5384 have code to handle the register class of the intermediate operand.\n\
5386 @c [For later: maybe we'll allow multi-alternative reload patterns -\n\
5387 @c the port maintainer could name a mov<mode> pattern that has clobbers -\n\
5388 @c and match the constraints of input and output to determine the required\n\
5389 @c alternative. A restriction would be that constraints used to match\n\
5390 @c against reloads registers would have to be written as register class\n\
5391 @c constraints, or we need a new target macro / hook that tells us if an\n\
5392 @c arbitrary constraint can match an unknown register of a given class.\n\
5393 @c Such a macro / hook would also be useful in other places.]\n\
5396 @var{x} might be a pseudo-register or a @code{subreg} of a\n\
5397 pseudo-register, which could either be in a hard register or in memory.\n\
5398 Use @code{true_regnum} to find out; it will return @minus{}1 if the pseudo is\n\
5399 in memory and the hard register number if it is in a register.\n\
5401 Scratch operands in memory (constraint @code{\"=m\"} / @code{\"=&m\"}) are\n\
5402 currently not supported. For the time being, you will have to continue\n\
5403 to use @code{TARGET_SECONDARY_MEMORY_NEEDED} for that purpose.\n\
5405 @code{copy_cost} also uses this target hook to find out how values are\n\
5406 copied. If you want it to include some extra cost for the need to allocate\n\
5407 (a) scratch register(s), set @code{sri->extra_cost} to the additional cost.\n\
5408 Or if two dependent moves are supposed to have a lower cost than the sum\n\
5409 of the individual moves due to expected fortuitous scheduling and/or special\n\
5410 forwarding logic, you can set @code{sri->extra_cost} to a negative amount.",
5411 reg_class_t,
5412 (bool in_p, rtx x, reg_class_t reload_class, machine_mode reload_mode,
5413 secondary_reload_info *sri),
5414 default_secondary_reload)
5416 DEFHOOK
5417 (secondary_memory_needed,
5418 "Certain machines have the property that some registers cannot be copied\n\
5419 to some other registers without using memory. Define this hook on\n\
5420 those machines to return true if objects of mode @var{m} in registers\n\
5421 of @var{class1} can only be copied to registers of class @var{class2} by\n\
5422 storing a register of @var{class1} into memory and loading that memory\n\
5423 location into a register of @var{class2}. The default definition returns\n\
5424 false for all inputs.",
5425 bool, (machine_mode mode, reg_class_t class1, reg_class_t class2),
5426 hook_bool_mode_reg_class_t_reg_class_t_false)
5428 DEFHOOK
5429 (secondary_memory_needed_mode,
5430 "If @code{TARGET_SECONDARY_MEMORY_NEEDED} tells the compiler to use memory\n\
5431 when moving between two particular registers of mode @var{mode},\n\
5432 this hook specifies the mode that the memory should have.\n\
5434 The default depends on @code{TARGET_LRA_P}. Without LRA, the default\n\
5435 is to use a word-sized mode for integral modes that are smaller than a\n\
5436 a word. This is right thing to do on most machines because it ensures\n\
5437 that all bits of the register are copied and prevents accesses to the\n\
5438 registers in a narrower mode, which some machines prohibit for\n\
5439 floating-point registers.\n\
5441 However, this default behavior is not correct on some machines, such as\n\
5442 the DEC Alpha, that store short integers in floating-point registers\n\
5443 differently than in integer registers. On those machines, the default\n\
5444 widening will not work correctly and you must define this hook to\n\
5445 suppress that widening in some cases. See the file @file{alpha.c} for\n\
5446 details.\n\
5448 With LRA, the default is to use @var{mode} unmodified.",
5449 machine_mode, (machine_mode mode),
5450 default_secondary_memory_needed_mode)
5452 /* Given an rtx X being reloaded into a reg required to be in class CLASS,
5453 return the class of reg to actually use. */
5454 DEFHOOK
5455 (preferred_reload_class,
5456 "A target hook that places additional restrictions on the register class\n\
5457 to use when it is necessary to copy value @var{x} into a register in class\n\
5458 @var{rclass}. The value is a register class; perhaps @var{rclass}, or perhaps\n\
5459 another, smaller class.\n\
5461 The default version of this hook always returns value of @code{rclass} argument.\n\
5463 Sometimes returning a more restrictive class makes better code. For\n\
5464 example, on the 68000, when @var{x} is an integer constant that is in range\n\
5465 for a @samp{moveq} instruction, the value of this macro is always\n\
5466 @code{DATA_REGS} as long as @var{rclass} includes the data registers.\n\
5467 Requiring a data register guarantees that a @samp{moveq} will be used.\n\
5469 One case where @code{TARGET_PREFERRED_RELOAD_CLASS} must not return\n\
5470 @var{rclass} is if @var{x} is a legitimate constant which cannot be\n\
5471 loaded into some register class. By returning @code{NO_REGS} you can\n\
5472 force @var{x} into a memory location. For example, rs6000 can load\n\
5473 immediate values into general-purpose registers, but does not have an\n\
5474 instruction for loading an immediate value into a floating-point\n\
5475 register, so @code{TARGET_PREFERRED_RELOAD_CLASS} returns @code{NO_REGS} when\n\
5476 @var{x} is a floating-point constant. If the constant can't be loaded\n\
5477 into any kind of register, code generation will be better if\n\
5478 @code{TARGET_LEGITIMATE_CONSTANT_P} makes the constant illegitimate instead\n\
5479 of using @code{TARGET_PREFERRED_RELOAD_CLASS}.\n\
5481 If an insn has pseudos in it after register allocation, reload will go\n\
5482 through the alternatives and call repeatedly @code{TARGET_PREFERRED_RELOAD_CLASS}\n\
5483 to find the best one. Returning @code{NO_REGS}, in this case, makes\n\
5484 reload add a @code{!} in front of the constraint: the x86 back-end uses\n\
5485 this feature to discourage usage of 387 registers when math is done in\n\
5486 the SSE registers (and vice versa).",
5487 reg_class_t,
5488 (rtx x, reg_class_t rclass),
5489 default_preferred_reload_class)
5491 /* Like TARGET_PREFERRED_RELOAD_CLASS, but for output reloads instead of
5492 input reloads. */
5493 DEFHOOK
5494 (preferred_output_reload_class,
5495 "Like @code{TARGET_PREFERRED_RELOAD_CLASS}, but for output reloads instead of\n\
5496 input reloads.\n\
5498 The default version of this hook always returns value of @code{rclass}\n\
5499 argument.\n\
5501 You can also use @code{TARGET_PREFERRED_OUTPUT_RELOAD_CLASS} to discourage\n\
5502 reload from using some alternatives, like @code{TARGET_PREFERRED_RELOAD_CLASS}.",
5503 reg_class_t,
5504 (rtx x, reg_class_t rclass),
5505 default_preferred_output_reload_class)
5507 DEFHOOK
5508 (select_early_remat_modes,
5509 "On some targets, certain modes cannot be held in registers around a\n\
5510 standard ABI call and are relatively expensive to spill to the stack.\n\
5511 The early rematerialization pass can help in such cases by aggressively\n\
5512 recomputing values after calls, so that they don't need to be spilled.\n\
5514 This hook returns the set of such modes by setting the associated bits\n\
5515 in @var{modes}. The default implementation selects no modes, which has\n\
5516 the effect of disabling the early rematerialization pass.",
5517 void, (sbitmap modes),
5518 default_select_early_remat_modes)
5520 DEFHOOK
5521 (class_likely_spilled_p,
5522 "A target hook which returns @code{true} if pseudos that have been assigned\n\
5523 to registers of class @var{rclass} would likely be spilled because\n\
5524 registers of @var{rclass} are needed for spill registers.\n\
5526 The default version of this target hook returns @code{true} if @var{rclass}\n\
5527 has exactly one register and @code{false} otherwise. On most machines, this\n\
5528 default should be used. For generally register-starved machines, such as\n\
5529 i386, or machines with right register constraints, such as SH, this hook\n\
5530 can be used to avoid excessive spilling.\n\
5532 This hook is also used by some of the global intra-procedural code\n\
5533 transformations to throtle code motion, to avoid increasing register\n\
5534 pressure.",
5535 bool, (reg_class_t rclass),
5536 default_class_likely_spilled_p)
5538 /* Return the maximum number of consecutive registers
5539 needed to represent mode MODE in a register of class RCLASS. */
5540 DEFHOOK
5541 (class_max_nregs,
5542 "A target hook returns the maximum number of consecutive registers\n\
5543 of class @var{rclass} needed to hold a value of mode @var{mode}.\n\
5545 This is closely related to the macro @code{TARGET_HARD_REGNO_NREGS}.\n\
5546 In fact, the value returned by @code{TARGET_CLASS_MAX_NREGS (@var{rclass},\n\
5547 @var{mode})} target hook should be the maximum value of\n\
5548 @code{TARGET_HARD_REGNO_NREGS (@var{regno}, @var{mode})} for all @var{regno}\n\
5549 values in the class @var{rclass}.\n\
5551 This target hook helps control the handling of multiple-word values\n\
5552 in the reload pass.\n\
5554 The default version of this target hook returns the size of @var{mode}\n\
5555 in words.",
5556 unsigned char, (reg_class_t rclass, machine_mode mode),
5557 default_class_max_nregs)
5559 DEFHOOK
5560 (preferred_rename_class,
5561 "A target hook that places additional preference on the register\
5562 class to use when it is necessary to rename a register in class\
5563 @var{rclass} to another class, or perhaps @var{NO_REGS}, if no\
5564 preferred register class is found or hook @code{preferred_rename_class}\
5565 is not implemented.\
5566 Sometimes returning a more restrictive class makes better code. For\
5567 example, on ARM, thumb-2 instructions using @code{LO_REGS} may be\
5568 smaller than instructions using @code{GENERIC_REGS}. By returning\
5569 @code{LO_REGS} from @code{preferred_rename_class}, code size can\
5570 be reduced.",
5571 reg_class_t, (reg_class_t rclass),
5572 default_preferred_rename_class)
5574 /* This target hook allows the backend to avoid unsafe substitution
5575 during register allocation. */
5576 DEFHOOK
5577 (cannot_substitute_mem_equiv_p,
5578 "A target hook which returns @code{true} if @var{subst} can't\n\
5579 substitute safely pseudos with equivalent memory values during\n\
5580 register allocation.\n\
5581 The default version of this target hook returns @code{false}.\n\
5582 On most machines, this default should be used. For generally\n\
5583 machines with non orthogonal register usage for addressing, such\n\
5584 as SH, this hook can be used to avoid excessive spilling.",
5585 bool, (rtx subst),
5586 hook_bool_rtx_false)
5588 /* This target hook allows the backend to legitimize base plus
5589 displacement addressing. */
5590 DEFHOOK
5591 (legitimize_address_displacement,
5592 "This hook tries to split address offset @var{orig_offset} into\n\
5593 two parts: one that should be added to the base address to create\n\
5594 a local anchor point, and an additional offset that can be applied\n\
5595 to the anchor to address a value of mode @var{mode}. The idea is that\n\
5596 the local anchor could be shared by other accesses to nearby locations.\n\
5598 The hook returns true if it succeeds, storing the offset of the\n\
5599 anchor from the base in @var{offset1} and the offset of the final address\n\
5600 from the anchor in @var{offset2}. The default implementation returns false.",
5601 bool, (rtx *offset1, rtx *offset2, poly_int64 orig_offset, machine_mode mode),
5602 default_legitimize_address_displacement)
5604 /* This target hook allows the backend to perform additional
5605 processing while initializing for variable expansion. */
5606 DEFHOOK
5607 (expand_to_rtl_hook,
5608 "This hook is called just before expansion into rtl, allowing the target\n\
5609 to perform additional initializations or analysis before the expansion.\n\
5610 For example, the rs6000 port uses it to allocate a scratch stack slot\n\
5611 for use in copying SDmode values between memory and floating point\n\
5612 registers whenever the function being expanded has any SDmode\n\
5613 usage.",
5614 void, (void),
5615 hook_void_void)
5617 /* This target hook allows the backend to perform additional
5618 instantiations on rtx that are not actually in insns yet,
5619 but will be later. */
5620 DEFHOOK
5621 (instantiate_decls,
5622 "This hook allows the backend to perform additional instantiations on rtl\n\
5623 that are not actually in any insns yet, but will be later.",
5624 void, (void),
5625 hook_void_void)
5627 DEFHOOK
5628 (hard_regno_nregs,
5629 "This hook returns the number of consecutive hard registers, starting\n\
5630 at register number @var{regno}, required to hold a value of mode\n\
5631 @var{mode}. This hook must never return zero, even if a register\n\
5632 cannot hold the requested mode - indicate that with\n\
5633 @code{TARGET_HARD_REGNO_MODE_OK} and/or\n\
5634 @code{TARGET_CAN_CHANGE_MODE_CLASS} instead.\n\
5636 The default definition returns the number of words in @var{mode}.",
5637 unsigned int, (unsigned int regno, machine_mode mode),
5638 default_hard_regno_nregs)
5640 DEFHOOK
5641 (hard_regno_mode_ok,
5642 "This hook returns true if it is permissible to store a value\n\
5643 of mode @var{mode} in hard register number @var{regno} (or in several\n\
5644 registers starting with that one). The default definition returns true\n\
5645 unconditionally.\n\
5647 You need not include code to check for the numbers of fixed registers,\n\
5648 because the allocation mechanism considers them to be always occupied.\n\
5650 @cindex register pairs\n\
5651 On some machines, double-precision values must be kept in even/odd\n\
5652 register pairs. You can implement that by defining this hook to reject\n\
5653 odd register numbers for such modes.\n\
5655 The minimum requirement for a mode to be OK in a register is that the\n\
5656 @samp{mov@var{mode}} instruction pattern support moves between the\n\
5657 register and other hard register in the same class and that moving a\n\
5658 value into the register and back out not alter it.\n\
5660 Since the same instruction used to move @code{word_mode} will work for\n\
5661 all narrower integer modes, it is not necessary on any machine for\n\
5662 this hook to distinguish between these modes, provided you define\n\
5663 patterns @samp{movhi}, etc., to take advantage of this. This is\n\
5664 useful because of the interaction between @code{TARGET_HARD_REGNO_MODE_OK}\n\
5665 and @code{TARGET_MODES_TIEABLE_P}; it is very desirable for all integer\n\
5666 modes to be tieable.\n\
5668 Many machines have special registers for floating point arithmetic.\n\
5669 Often people assume that floating point machine modes are allowed only\n\
5670 in floating point registers. This is not true. Any registers that\n\
5671 can hold integers can safely @emph{hold} a floating point machine\n\
5672 mode, whether or not floating arithmetic can be done on it in those\n\
5673 registers. Integer move instructions can be used to move the values.\n\
5675 On some machines, though, the converse is true: fixed-point machine\n\
5676 modes may not go in floating registers. This is true if the floating\n\
5677 registers normalize any value stored in them, because storing a\n\
5678 non-floating value there would garble it. In this case,\n\
5679 @code{TARGET_HARD_REGNO_MODE_OK} should reject fixed-point machine modes in\n\
5680 floating registers. But if the floating registers do not automatically\n\
5681 normalize, if you can store any bit pattern in one and retrieve it\n\
5682 unchanged without a trap, then any machine mode may go in a floating\n\
5683 register, so you can define this hook to say so.\n\
5685 The primary significance of special floating registers is rather that\n\
5686 they are the registers acceptable in floating point arithmetic\n\
5687 instructions. However, this is of no concern to\n\
5688 @code{TARGET_HARD_REGNO_MODE_OK}. You handle it by writing the proper\n\
5689 constraints for those instructions.\n\
5691 On some machines, the floating registers are especially slow to access,\n\
5692 so that it is better to store a value in a stack frame than in such a\n\
5693 register if floating point arithmetic is not being done. As long as the\n\
5694 floating registers are not in class @code{GENERAL_REGS}, they will not\n\
5695 be used unless some pattern's constraint asks for one.",
5696 bool, (unsigned int regno, machine_mode mode),
5697 hook_bool_uint_mode_true)
5699 DEFHOOK
5700 (modes_tieable_p,
5701 "This hook returns true if a value of mode @var{mode1} is accessible\n\
5702 in mode @var{mode2} without copying.\n\
5704 If @code{TARGET_HARD_REGNO_MODE_OK (@var{r}, @var{mode1})} and\n\
5705 @code{TARGET_HARD_REGNO_MODE_OK (@var{r}, @var{mode2})} are always\n\
5706 the same for any @var{r}, then\n\
5707 @code{TARGET_MODES_TIEABLE_P (@var{mode1}, @var{mode2})}\n\
5708 should be true. If they differ for any @var{r}, you should define\n\
5709 this hook to return false unless some other mechanism ensures the\n\
5710 accessibility of the value in a narrower mode.\n\
5712 You should define this hook to return true in as many cases as\n\
5713 possible since doing so will allow GCC to perform better register\n\
5714 allocation. The default definition returns true unconditionally.",
5715 bool, (machine_mode mode1, machine_mode mode2),
5716 hook_bool_mode_mode_true)
5718 /* Return true if is OK to use a hard register REGNO as scratch register
5719 in peephole2. */
5720 DEFHOOK
5721 (hard_regno_scratch_ok,
5722 "This target hook should return @code{true} if it is OK to use a hard register\n\
5723 @var{regno} as scratch reg in peephole2.\n\
5725 One common use of this macro is to prevent using of a register that\n\
5726 is not saved by a prologue in an interrupt handler.\n\
5728 The default version of this hook always returns @code{true}.",
5729 bool, (unsigned int regno),
5730 default_hard_regno_scratch_ok)
5732 DEFHOOK
5733 (hard_regno_call_part_clobbered,
5734 "This hook should return true if @var{regno} is partly call-saved and\n\
5735 partly call-clobbered, and if a value of mode @var{mode} would be partly\n\
5736 clobbered by a call. For example, if the low 32 bits of @var{regno} are\n\
5737 preserved across a call but higher bits are clobbered, this hook should\n\
5738 return true for a 64-bit mode but false for a 32-bit mode.\n\
5740 The default implementation returns false, which is correct\n\
5741 for targets that don't have partly call-clobbered registers.",
5742 bool, (unsigned int regno, machine_mode mode),
5743 hook_bool_uint_mode_false)
5745 /* Return the smallest number of different values for which it is best to
5746 use a jump-table instead of a tree of conditional branches. */
5747 DEFHOOK
5748 (case_values_threshold,
5749 "This function return the smallest number of different values for which it\n\
5750 is best to use a jump-table instead of a tree of conditional branches.\n\
5751 The default is four for machines with a @code{casesi} instruction and\n\
5752 five otherwise. This is best for most machines.",
5753 unsigned int, (void),
5754 default_case_values_threshold)
5756 DEFHOOK
5757 (starting_frame_offset,
5758 "This hook returns the offset from the frame pointer to the first local\n\
5759 variable slot to be allocated. If @code{FRAME_GROWS_DOWNWARD}, it is the\n\
5760 offset to @emph{end} of the first slot allocated, otherwise it is the\n\
5761 offset to @emph{beginning} of the first slot allocated. The default\n\
5762 implementation returns 0.",
5763 HOST_WIDE_INT, (void),
5764 hook_hwi_void_0)
5766 /* Optional callback to advise the target to compute the frame layout. */
5767 DEFHOOK
5768 (compute_frame_layout,
5769 "This target hook is called once each time the frame layout needs to be\n\
5770 recalculated. The calculations can be cached by the target and can then\n\
5771 be used by @code{INITIAL_ELIMINATION_OFFSET} instead of re-computing the\n\
5772 layout on every invocation of that hook. This is particularly useful\n\
5773 for targets that have an expensive frame layout function. Implementing\n\
5774 this callback is optional.",
5775 void, (void),
5776 hook_void_void)
5778 /* Return true if a function must have and use a frame pointer. */
5779 DEFHOOK
5780 (frame_pointer_required,
5781 "This target hook should return @code{true} if a function must have and use\n\
5782 a frame pointer. This target hook is called in the reload pass. If its return\n\
5783 value is @code{true} the function will have a frame pointer.\n\
5785 This target hook can in principle examine the current function and decide\n\
5786 according to the facts, but on most machines the constant @code{false} or the\n\
5787 constant @code{true} suffices. Use @code{false} when the machine allows code\n\
5788 to be generated with no frame pointer, and doing so saves some time or space.\n\
5789 Use @code{true} when there is no possible advantage to avoiding a frame\n\
5790 pointer.\n\
5792 In certain cases, the compiler does not know how to produce valid code\n\
5793 without a frame pointer. The compiler recognizes those cases and\n\
5794 automatically gives the function a frame pointer regardless of what\n\
5795 @code{targetm.frame_pointer_required} returns. You don't need to worry about\n\
5796 them.\n\
5798 In a function that does not require a frame pointer, the frame pointer\n\
5799 register can be allocated for ordinary usage, unless you mark it as a\n\
5800 fixed register. See @code{FIXED_REGISTERS} for more information.\n\
5802 Default return value is @code{false}.",
5803 bool, (void),
5804 hook_bool_void_false)
5806 /* Returns true if the compiler is allowed to try to replace register number
5807 from-reg with register number to-reg. */
5808 DEFHOOK
5809 (can_eliminate,
5810 "This target hook should return @code{true} if the compiler is allowed to\n\
5811 try to replace register number @var{from_reg} with register number\n\
5812 @var{to_reg}. This target hook will usually be @code{true}, since most of the\n\
5813 cases preventing register elimination are things that the compiler already\n\
5814 knows about.\n\
5816 Default return value is @code{true}.",
5817 bool, (const int from_reg, const int to_reg),
5818 hook_bool_const_int_const_int_true)
5820 /* Modify any or all of fixed_regs, call_used_regs, global_regs,
5821 reg_names, and reg_class_contents to account of the vagaries of the
5822 target. */
5823 DEFHOOK
5824 (conditional_register_usage,
5825 "This hook may conditionally modify five variables\n\
5826 @code{fixed_regs}, @code{call_used_regs}, @code{global_regs},\n\
5827 @code{reg_names}, and @code{reg_class_contents}, to take into account\n\
5828 any dependence of these register sets on target flags. The first three\n\
5829 of these are of type @code{char []} (interpreted as boolean vectors).\n\
5830 @code{global_regs} is a @code{const char *[]}, and\n\
5831 @code{reg_class_contents} is a @code{HARD_REG_SET}. Before the macro is\n\
5832 called, @code{fixed_regs}, @code{call_used_regs},\n\
5833 @code{reg_class_contents}, and @code{reg_names} have been initialized\n\
5834 from @code{FIXED_REGISTERS}, @code{CALL_USED_REGISTERS},\n\
5835 @code{REG_CLASS_CONTENTS}, and @code{REGISTER_NAMES}, respectively.\n\
5836 @code{global_regs} has been cleared, and any @option{-ffixed-@var{reg}},\n\
5837 @option{-fcall-used-@var{reg}} and @option{-fcall-saved-@var{reg}}\n\
5838 command options have been applied.\n\
5840 @cindex disabling certain registers\n\
5841 @cindex controlling register usage\n\
5842 If the usage of an entire class of registers depends on the target\n\
5843 flags, you may indicate this to GCC by using this macro to modify\n\
5844 @code{fixed_regs} and @code{call_used_regs} to 1 for each of the\n\
5845 registers in the classes which should not be used by GCC@. Also make\n\
5846 @code{define_register_constraint}s return @code{NO_REGS} for constraints\n\
5847 that shouldn't be used.\n\
5849 (However, if this class is not included in @code{GENERAL_REGS} and all\n\
5850 of the insn patterns whose constraints permit this class are\n\
5851 controlled by target switches, then GCC will automatically avoid using\n\
5852 these registers when the target switches are opposed to them.)",
5853 void, (void),
5854 hook_void_void)
5856 DEFHOOK
5857 (stack_clash_protection_final_dynamic_probe,
5858 "Some targets make optimistic assumptions about the state of stack probing when they emit their prologues. On such targets a probe into the end of any dynamically allocated space is likely required for safety against stack clash style attacks. Define this variable to return nonzero if such a probe is required or zero otherwise. You need not define this macro if it would always have the value zero.",
5859 bool, (rtx residual),
5860 default_stack_clash_protection_final_dynamic_probe)
5863 /* Functions specific to the C family of frontends. */
5864 #undef HOOK_PREFIX
5865 #define HOOK_PREFIX "TARGET_C_"
5866 HOOK_VECTOR (TARGET_C, c)
5868 /* ??? Documenting this hook requires a GFDL license grant. */
5869 DEFHOOK_UNDOC
5870 (mode_for_suffix,
5871 "Return machine mode for non-standard constant literal suffix @var{c},\
5872 or VOIDmode if non-standard suffixes are unsupported.",
5873 machine_mode, (char c),
5874 default_mode_for_suffix)
5876 DEFHOOK
5877 (excess_precision,
5878 "Return a value, with the same meaning as the C99 macro\
5879 @code{FLT_EVAL_METHOD} that describes which excess precision should be\
5880 applied. @var{type} is either @code{EXCESS_PRECISION_TYPE_IMPLICIT},\
5881 @code{EXCESS_PRECISION_TYPE_FAST}, or\
5882 @code{EXCESS_PRECISION_TYPE_STANDARD}. For\
5883 @code{EXCESS_PRECISION_TYPE_IMPLICIT}, the target should return which\
5884 precision and range operations will be implictly evaluated in regardless\
5885 of the excess precision explicitly added. For\
5886 @code{EXCESS_PRECISION_TYPE_STANDARD} and\
5887 @code{EXCESS_PRECISION_TYPE_FAST}, the target should return the\
5888 explicit excess precision that should be added depending on the\
5889 value set for @option{-fexcess-precision=@r{[}standard@r{|}fast@r{]}}.\
5890 Note that unpredictable explicit excess precision does not make sense,\
5891 so a target should never return @code{FLT_EVAL_METHOD_UNPREDICTABLE}\
5892 when @var{type} is @code{EXCESS_PRECISION_TYPE_STANDARD} or\
5893 @code{EXCESS_PRECISION_TYPE_FAST}.",
5894 enum flt_eval_method, (enum excess_precision_type type),
5895 default_excess_precision)
5897 HOOK_VECTOR_END (c)
5899 /* Functions specific to the C++ frontend. */
5900 #undef HOOK_PREFIX
5901 #define HOOK_PREFIX "TARGET_CXX_"
5902 HOOK_VECTOR (TARGET_CXX, cxx)
5904 /* Return the integer type used for guard variables. */
5905 DEFHOOK
5906 (guard_type,
5907 "Define this hook to override the integer type used for guard variables.\n\
5908 These are used to implement one-time construction of static objects. The\n\
5909 default is long_long_integer_type_node.",
5910 tree, (void),
5911 default_cxx_guard_type)
5913 /* Return true if only the low bit of the guard should be tested. */
5914 DEFHOOK
5915 (guard_mask_bit,
5916 "This hook determines how guard variables are used. It should return\n\
5917 @code{false} (the default) if the first byte should be used. A return value of\n\
5918 @code{true} indicates that only the least significant bit should be used.",
5919 bool, (void),
5920 hook_bool_void_false)
5922 /* Returns the size of the array cookie for an array of type. */
5923 DEFHOOK
5924 (get_cookie_size,
5925 "This hook returns the size of the cookie to use when allocating an array\n\
5926 whose elements have the indicated @var{type}. Assumes that it is already\n\
5927 known that a cookie is needed. The default is\n\
5928 @code{max(sizeof (size_t), alignof(type))}, as defined in section 2.7 of the\n\
5929 IA64/Generic C++ ABI@.",
5930 tree, (tree type),
5931 default_cxx_get_cookie_size)
5933 /* Returns true if the element size should be stored in the array cookie. */
5934 DEFHOOK
5935 (cookie_has_size,
5936 "This hook should return @code{true} if the element size should be stored in\n\
5937 array cookies. The default is to return @code{false}.",
5938 bool, (void),
5939 hook_bool_void_false)
5941 /* Allows backends to perform additional processing when
5942 deciding if a class should be exported or imported. */
5943 DEFHOOK
5944 (import_export_class,
5945 "If defined by a backend this hook allows the decision made to export\n\
5946 class @var{type} to be overruled. Upon entry @var{import_export}\n\
5947 will contain 1 if the class is going to be exported, @minus{}1 if it is going\n\
5948 to be imported and 0 otherwise. This function should return the\n\
5949 modified value and perform any other actions necessary to support the\n\
5950 backend's targeted operating system.",
5951 int, (tree type, int import_export), NULL)
5953 /* Returns true if constructors and destructors return "this". */
5954 DEFHOOK
5955 (cdtor_returns_this,
5956 "This hook should return @code{true} if constructors and destructors return\n\
5957 the address of the object created/destroyed. The default is to return\n\
5958 @code{false}.",
5959 bool, (void),
5960 hook_bool_void_false)
5962 /* Returns true if the key method for a class can be an inline
5963 function, so long as it is not declared inline in the class
5964 itself. Returning true is the behavior required by the Itanium C++ ABI. */
5965 DEFHOOK
5966 (key_method_may_be_inline,
5967 "This hook returns true if the key method for a class (i.e., the method\n\
5968 which, if defined in the current translation unit, causes the virtual\n\
5969 table to be emitted) may be an inline function. Under the standard\n\
5970 Itanium C++ ABI the key method may be an inline function so long as\n\
5971 the function is not declared inline in the class definition. Under\n\
5972 some variants of the ABI, an inline function can never be the key\n\
5973 method. The default is to return @code{true}.",
5974 bool, (void),
5975 hook_bool_void_true)
5977 DEFHOOK
5978 (determine_class_data_visibility,
5979 "@var{decl} is a virtual table, virtual table table, typeinfo object,\
5980 or other similar implicit class data object that will be emitted with\
5981 external linkage in this translation unit. No ELF visibility has been\
5982 explicitly specified. If the target needs to specify a visibility\
5983 other than that of the containing class, use this hook to set\
5984 @code{DECL_VISIBILITY} and @code{DECL_VISIBILITY_SPECIFIED}.",
5985 void, (tree decl),
5986 hook_void_tree)
5988 /* Returns true (the default) if virtual tables and other
5989 similar implicit class data objects are always COMDAT if they
5990 have external linkage. If this hook returns false, then
5991 class data for classes whose virtual table will be emitted in
5992 only one translation unit will not be COMDAT. */
5993 DEFHOOK
5994 (class_data_always_comdat,
5995 "This hook returns true (the default) if virtual tables and other\n\
5996 similar implicit class data objects are always COMDAT if they have\n\
5997 external linkage. If this hook returns false, then class data for\n\
5998 classes whose virtual table will be emitted in only one translation\n\
5999 unit will not be COMDAT.",
6000 bool, (void),
6001 hook_bool_void_true)
6003 /* Returns true (the default) if the RTTI for the basic types,
6004 which is always defined in the C++ runtime, should be COMDAT;
6005 false if it should not be COMDAT. */
6006 DEFHOOK
6007 (library_rtti_comdat,
6008 "This hook returns true (the default) if the RTTI information for\n\
6009 the basic types which is defined in the C++ runtime should always\n\
6010 be COMDAT, false if it should not be COMDAT.",
6011 bool, (void),
6012 hook_bool_void_true)
6014 /* Returns true if __aeabi_atexit should be used to register static
6015 destructors. */
6016 DEFHOOK
6017 (use_aeabi_atexit,
6018 "This hook returns true if @code{__aeabi_atexit} (as defined by the ARM EABI)\n\
6019 should be used to register static destructors when @option{-fuse-cxa-atexit}\n\
6020 is in effect. The default is to return false to use @code{__cxa_atexit}.",
6021 bool, (void),
6022 hook_bool_void_false)
6024 /* Returns true if target may use atexit in the same manner as
6025 __cxa_atexit to register static destructors. */
6026 DEFHOOK
6027 (use_atexit_for_cxa_atexit,
6028 "This hook returns true if the target @code{atexit} function can be used\n\
6029 in the same manner as @code{__cxa_atexit} to register C++ static\n\
6030 destructors. This requires that @code{atexit}-registered functions in\n\
6031 shared libraries are run in the correct order when the libraries are\n\
6032 unloaded. The default is to return false.",
6033 bool, (void),
6034 hook_bool_void_false)
6036 DEFHOOK
6037 (adjust_class_at_definition,
6038 "@var{type} is a C++ class (i.e., RECORD_TYPE or UNION_TYPE) that has just\
6039 been defined. Use this hook to make adjustments to the class (eg, tweak\
6040 visibility or perform any other required target modifications).",
6041 void, (tree type),
6042 hook_void_tree)
6044 DEFHOOK
6045 (decl_mangling_context,
6046 "Return target-specific mangling context of @var{decl} or @code{NULL_TREE}.",
6047 tree, (const_tree decl),
6048 hook_tree_const_tree_null)
6050 HOOK_VECTOR_END (cxx)
6052 /* Functions and data for emulated TLS support. */
6053 #undef HOOK_PREFIX
6054 #define HOOK_PREFIX "TARGET_EMUTLS_"
6055 HOOK_VECTOR (TARGET_EMUTLS, emutls)
6057 /* Name of the address and common functions. */
6058 DEFHOOKPOD
6059 (get_address,
6060 "Contains the name of the helper function that uses a TLS control\n\
6061 object to locate a TLS instance. The default causes libgcc's\n\
6062 emulated TLS helper function to be used.",
6063 const char *, "__builtin___emutls_get_address")
6065 DEFHOOKPOD
6066 (register_common,
6067 "Contains the name of the helper function that should be used at\n\
6068 program startup to register TLS objects that are implicitly\n\
6069 initialized to zero. If this is @code{NULL}, all TLS objects will\n\
6070 have explicit initializers. The default causes libgcc's emulated TLS\n\
6071 registration function to be used.",
6072 const char *, "__builtin___emutls_register_common")
6074 /* Prefixes for proxy variable and template. */
6075 DEFHOOKPOD
6076 (var_section,
6077 "Contains the name of the section in which TLS control variables should\n\
6078 be placed. The default of @code{NULL} allows these to be placed in\n\
6079 any section.",
6080 const char *, NULL)
6082 DEFHOOKPOD
6083 (tmpl_section,
6084 "Contains the name of the section in which TLS initializers should be\n\
6085 placed. The default of @code{NULL} allows these to be placed in any\n\
6086 section.",
6087 const char *, NULL)
6089 /* Prefixes for proxy variable and template. */
6090 DEFHOOKPOD
6091 (var_prefix,
6092 "Contains the prefix to be prepended to TLS control variable names.\n\
6093 The default of @code{NULL} uses a target-specific prefix.",
6094 const char *, NULL)
6096 DEFHOOKPOD
6097 (tmpl_prefix,
6098 "Contains the prefix to be prepended to TLS initializer objects. The\n\
6099 default of @code{NULL} uses a target-specific prefix.",
6100 const char *, NULL)
6102 /* Function to generate field definitions of the proxy variable. */
6103 DEFHOOK
6104 (var_fields,
6105 "Specifies a function that generates the FIELD_DECLs for a TLS control\n\
6106 object type. @var{type} is the RECORD_TYPE the fields are for and\n\
6107 @var{name} should be filled with the structure tag, if the default of\n\
6108 @code{__emutls_object} is unsuitable. The default creates a type suitable\n\
6109 for libgcc's emulated TLS function.",
6110 tree, (tree type, tree *name),
6111 default_emutls_var_fields)
6113 /* Function to initialize a proxy variable. */
6114 DEFHOOK
6115 (var_init,
6116 "Specifies a function that generates the CONSTRUCTOR to initialize a\n\
6117 TLS control object. @var{var} is the TLS control object, @var{decl}\n\
6118 is the TLS object and @var{tmpl_addr} is the address of the\n\
6119 initializer. The default initializes libgcc's emulated TLS control object.",
6120 tree, (tree var, tree decl, tree tmpl_addr),
6121 default_emutls_var_init)
6123 /* Whether we are allowed to alter the usual alignment of the
6124 proxy variable. */
6125 DEFHOOKPOD
6126 (var_align_fixed,
6127 "Specifies whether the alignment of TLS control variable objects is\n\
6128 fixed and should not be increased as some backends may do to optimize\n\
6129 single objects. The default is false.",
6130 bool, false)
6132 /* Whether we can emit debug information for TLS vars. */
6133 DEFHOOKPOD
6134 (debug_form_tls_address,
6135 "Specifies whether a DWARF @code{DW_OP_form_tls_address} location descriptor\n\
6136 may be used to describe emulated TLS control objects.",
6137 bool, false)
6139 HOOK_VECTOR_END (emutls)
6141 #undef HOOK_PREFIX
6142 #define HOOK_PREFIX "TARGET_OPTION_"
6143 HOOK_VECTOR (TARGET_OPTION_HOOKS, target_option_hooks)
6145 /* Function to validate the attribute((target(...))) strings. If
6146 the option is validated, the hook should also fill in
6147 DECL_FUNCTION_SPECIFIC_TARGET in the function decl node. */
6148 DEFHOOK
6149 (valid_attribute_p,
6150 "This hook is called to parse @code{attribute(target(\"...\"))}, which\n\
6151 allows setting target-specific options on individual functions.\n\
6152 These function-specific options may differ\n\
6153 from the options specified on the command line. The hook should return\n\
6154 @code{true} if the options are valid.\n\
6156 The hook should set the @code{DECL_FUNCTION_SPECIFIC_TARGET} field in\n\
6157 the function declaration to hold a pointer to a target-specific\n\
6158 @code{struct cl_target_option} structure.",
6159 bool, (tree fndecl, tree name, tree args, int flags),
6160 default_target_option_valid_attribute_p)
6162 /* Function to save any extra target state in the target options structure. */
6163 DEFHOOK
6164 (save,
6165 "This hook is called to save any additional target-specific information\n\
6166 in the @code{struct cl_target_option} structure for function-specific\n\
6167 options from the @code{struct gcc_options} structure.\n\
6168 @xref{Option file format}.",
6169 void, (struct cl_target_option *ptr, struct gcc_options *opts), NULL)
6171 /* Function to restore any extra target state from the target options
6172 structure. */
6173 DEFHOOK
6174 (restore,
6175 "This hook is called to restore any additional target-specific\n\
6176 information in the @code{struct cl_target_option} structure for\n\
6177 function-specific options to the @code{struct gcc_options} structure.",
6178 void, (struct gcc_options *opts, struct cl_target_option *ptr), NULL)
6180 /* Function to update target-specific option information after being
6181 streamed in. */
6182 DEFHOOK
6183 (post_stream_in,
6184 "This hook is called to update target-specific information in the\n\
6185 @code{struct cl_target_option} structure after it is streamed in from\n\
6186 LTO bytecode.",
6187 void, (struct cl_target_option *ptr), NULL)
6189 /* Function to print any extra target state from the target options
6190 structure. */
6191 DEFHOOK
6192 (print,
6193 "This hook is called to print any additional target-specific\n\
6194 information in the @code{struct cl_target_option} structure for\n\
6195 function-specific options.",
6196 void, (FILE *file, int indent, struct cl_target_option *ptr), NULL)
6198 /* Function to parse arguments to be validated for #pragma target, and to
6199 change the state if the options are valid. If the first argument is
6200 NULL, the second argument specifies the default options to use. Return
6201 true if the options are valid, and set the current state. */
6202 DEFHOOK
6203 (pragma_parse,
6204 "This target hook parses the options for @code{#pragma GCC target}, which\n\
6205 sets the target-specific options for functions that occur later in the\n\
6206 input stream. The options accepted should be the same as those handled by the\n\
6207 @code{TARGET_OPTION_VALID_ATTRIBUTE_P} hook.",
6208 bool, (tree args, tree pop_target),
6209 default_target_option_pragma_parse)
6211 /* Do option overrides for the target. */
6212 DEFHOOK
6213 (override,
6214 "Sometimes certain combinations of command options do not make sense on\n\
6215 a particular target machine. You can override the hook\n\
6216 @code{TARGET_OPTION_OVERRIDE} to take account of this. This hooks is called\n\
6217 once just after all the command options have been parsed.\n\
6219 Don't use this hook to turn on various extra optimizations for\n\
6220 @option{-O}. That is what @code{TARGET_OPTION_OPTIMIZATION} is for.\n\
6222 If you need to do something whenever the optimization level is\n\
6223 changed via the optimize attribute or pragma, see\n\
6224 @code{TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE}",
6225 void, (void),
6226 hook_void_void)
6228 /* This function returns true if DECL1 and DECL2 are versions of the same
6229 function. DECL1 and DECL2 are function versions if and only if they
6230 have the same function signature and different target specific attributes,
6231 that is, they are compiled for different target machines. */
6232 DEFHOOK
6233 (function_versions,
6234 "This target hook returns @code{true} if @var{DECL1} and @var{DECL2} are\n\
6235 versions of the same function. @var{DECL1} and @var{DECL2} are function\n\
6236 versions if and only if they have the same function signature and\n\
6237 different target specific attributes, that is, they are compiled for\n\
6238 different target machines.",
6239 bool, (tree decl1, tree decl2),
6240 hook_bool_tree_tree_false)
6242 /* Function to determine if one function can inline another function. */
6243 #undef HOOK_PREFIX
6244 #define HOOK_PREFIX "TARGET_"
6245 DEFHOOK
6246 (can_inline_p,
6247 "This target hook returns @code{false} if the @var{caller} function\n\
6248 cannot inline @var{callee}, based on target specific information. By\n\
6249 default, inlining is not allowed if the callee function has function\n\
6250 specific target options and the caller does not use the same options.",
6251 bool, (tree caller, tree callee),
6252 default_target_can_inline_p)
6254 DEFHOOK
6255 (relayout_function,
6256 "This target hook fixes function @var{fndecl} after attributes are processed. Default does nothing. On ARM, the default function's alignment is updated with the attribute target.",
6257 void, (tree fndecl),
6258 hook_void_tree)
6260 HOOK_VECTOR_END (target_option)
6262 /* For targets that need to mark extra registers as live on entry to
6263 the function, they should define this target hook and set their
6264 bits in the bitmap passed in. */
6265 DEFHOOK
6266 (extra_live_on_entry,
6267 "Add any hard registers to @var{regs} that are live on entry to the\n\
6268 function. This hook only needs to be defined to provide registers that\n\
6269 cannot be found by examination of FUNCTION_ARG_REGNO_P, the callee saved\n\
6270 registers, STATIC_CHAIN_INCOMING_REGNUM, STATIC_CHAIN_REGNUM,\n\
6271 TARGET_STRUCT_VALUE_RTX, FRAME_POINTER_REGNUM, EH_USES,\n\
6272 FRAME_POINTER_REGNUM, ARG_POINTER_REGNUM, and the PIC_OFFSET_TABLE_REGNUM.",
6273 void, (bitmap regs),
6274 hook_void_bitmap)
6276 /* Targets should define this target hook to mark that non-callee clobbers are
6277 present in CALL_INSN_FUNCTION_USAGE for all the calls that bind to a local
6278 definition. */
6279 DEFHOOKPOD
6280 (call_fusage_contains_non_callee_clobbers,
6281 "Set to true if each call that binds to a local definition explicitly\n\
6282 clobbers or sets all non-fixed registers modified by performing the call.\n\
6283 That is, by the call pattern itself, or by code that might be inserted by the\n\
6284 linker (e.g. stubs, veneers, branch islands), but not including those\n\
6285 modifiable by the callee. The affected registers may be mentioned explicitly\n\
6286 in the call pattern, or included as clobbers in CALL_INSN_FUNCTION_USAGE.\n\
6287 The default version of this hook is set to false. The purpose of this hook\n\
6288 is to enable the fipa-ra optimization.",
6289 bool,
6290 false)
6292 /* Fill in additional registers set up by prologue into a regset. */
6293 DEFHOOK
6294 (set_up_by_prologue,
6295 "This hook should add additional registers that are computed by the prologue\
6296 to the hard regset for shrink-wrapping optimization purposes.",
6297 void, (struct hard_reg_set_container *),
6298 NULL)
6300 /* For targets that have attributes that can affect whether a
6301 function's return statements need checking. For instance a 'naked'
6302 function attribute. */
6303 DEFHOOK
6304 (warn_func_return,
6305 "True if a function's return statements should be checked for matching the function's return type. This includes checking for falling off the end of a non-void function. Return false if no such check should be made.",
6306 bool, (tree),
6307 hook_bool_tree_true)
6309 #undef HOOK_PREFIX
6310 #define HOOK_PREFIX "TARGET_SHRINK_WRAP_"
6311 HOOK_VECTOR (TARGET_SHRINK_WRAP_HOOKS, shrink_wrap)
6313 DEFHOOK
6314 (get_separate_components,
6315 "This hook should return an @code{sbitmap} with the bits set for those\n\
6316 components that can be separately shrink-wrapped in the current function.\n\
6317 Return @code{NULL} if the current function should not get any separate\n\
6318 shrink-wrapping.\n\
6319 Don't define this hook if it would always return @code{NULL}.\n\
6320 If it is defined, the other hooks in this group have to be defined as well.",
6321 sbitmap, (void),
6322 NULL)
6324 DEFHOOK
6325 (components_for_bb,
6326 "This hook should return an @code{sbitmap} with the bits set for those\n\
6327 components where either the prologue component has to be executed before\n\
6328 the @code{basic_block}, or the epilogue component after it, or both.",
6329 sbitmap, (basic_block),
6330 NULL)
6332 DEFHOOK
6333 (disqualify_components,
6334 "This hook should clear the bits in the @var{components} bitmap for those\n\
6335 components in @var{edge_components} that the target cannot handle on edge\n\
6336 @var{e}, where @var{is_prologue} says if this is for a prologue or an\n\
6337 epilogue instead.",
6338 void, (sbitmap components, edge e, sbitmap edge_components, bool is_prologue),
6339 NULL)
6341 DEFHOOK
6342 (emit_prologue_components,
6343 "Emit prologue insns for the components indicated by the parameter.",
6344 void, (sbitmap),
6345 NULL)
6347 DEFHOOK
6348 (emit_epilogue_components,
6349 "Emit epilogue insns for the components indicated by the parameter.",
6350 void, (sbitmap),
6351 NULL)
6353 DEFHOOK
6354 (set_handled_components,
6355 "Mark the components in the parameter as handled, so that the\n\
6356 @code{prologue} and @code{epilogue} named patterns know to ignore those\n\
6357 components. The target code should not hang on to the @code{sbitmap}, it\n\
6358 will be deleted after this call.",
6359 void, (sbitmap),
6360 NULL)
6362 HOOK_VECTOR_END (shrink_wrap)
6363 #undef HOOK_PREFIX
6364 #define HOOK_PREFIX "TARGET_"
6366 /* Determine the type of unwind info to emit for debugging. */
6367 DEFHOOK
6368 (debug_unwind_info,
6369 "This hook defines the mechanism that will be used for describing frame\n\
6370 unwind information to the debugger. Normally the hook will return\n\
6371 @code{UI_DWARF2} if DWARF 2 debug information is enabled, and\n\
6372 return @code{UI_NONE} otherwise.\n\
6374 A target may return @code{UI_DWARF2} even when DWARF 2 debug information\n\
6375 is disabled in order to always output DWARF 2 frame information.\n\
6377 A target may return @code{UI_TARGET} if it has ABI specified unwind tables.\n\
6378 This will suppress generation of the normal debug frame unwind information.",
6379 enum unwind_info_type, (void),
6380 default_debug_unwind_info)
6382 DEFHOOK
6383 (reset_location_view, "\
6384 This hook, if defined, enables -ginternal-reset-location-views, and\n\
6385 uses its result to override cases in which the estimated min insn\n\
6386 length might be nonzero even when a PC advance (i.e., a view reset)\n\
6387 cannot be taken for granted.\n\
6389 If the hook is defined, it must return a positive value to indicate\n\
6390 the insn definitely advances the PC, and so the view number can be\n\
6391 safely assumed to be reset; a negative value to mean the insn\n\
6392 definitely does not advance the PC, and os the view number must not\n\
6393 be reset; or zero to decide based on the estimated insn length.\n\
6395 If insn length is to be regarded as reliable, set the hook to\n\
6396 @code{hook_int_rtx_insn_0}.",
6397 int, (rtx_insn *), NULL)
6399 /* The code parameter should be of type enum rtx_code but this is not
6400 defined at this time. */
6401 DEFHOOK
6402 (canonicalize_comparison,
6403 "On some machines not all possible comparisons are defined, but you can\n\
6404 convert an invalid comparison into a valid one. For example, the Alpha\n\
6405 does not have a @code{GT} comparison, but you can use an @code{LT}\n\
6406 comparison instead and swap the order of the operands.\n\
6408 On such machines, implement this hook to do any required conversions.\n\
6409 @var{code} is the initial comparison code and @var{op0} and @var{op1}\n\
6410 are the left and right operands of the comparison, respectively. If\n\
6411 @var{op0_preserve_value} is @code{true} the implementation is not\n\
6412 allowed to change the value of @var{op0} since the value might be used\n\
6413 in RTXs which aren't comparisons. E.g. the implementation is not\n\
6414 allowed to swap operands in that case.\n\
6416 GCC will not assume that the comparison resulting from this macro is\n\
6417 valid but will see if the resulting insn matches a pattern in the\n\
6418 @file{md} file.\n\
6420 You need not to implement this hook if it would never change the\n\
6421 comparison code or operands.",
6422 void, (int *code, rtx *op0, rtx *op1, bool op0_preserve_value),
6423 default_canonicalize_comparison)
6425 DEFHOOK
6426 (min_arithmetic_precision,
6427 "On some RISC architectures with 64-bit registers, the processor also\n\
6428 maintains 32-bit condition codes that make it possible to do real 32-bit\n\
6429 arithmetic, although the operations are performed on the full registers.\n\
6431 On such architectures, defining this hook to 32 tells the compiler to try\n\
6432 using 32-bit arithmetical operations setting the condition codes instead\n\
6433 of doing full 64-bit arithmetic.\n\
6435 More generally, define this hook on RISC architectures if you want the\n\
6436 compiler to try using arithmetical operations setting the condition codes\n\
6437 with a precision lower than the word precision.\n\
6439 You need not define this hook if @code{WORD_REGISTER_OPERATIONS} is not\n\
6440 defined to 1.",
6441 unsigned int, (void), default_min_arithmetic_precision)
6443 DEFHOOKPOD
6444 (atomic_test_and_set_trueval,
6445 "This value should be set if the result written by\
6446 @code{atomic_test_and_set} is not exactly 1, i.e. the\
6447 @code{bool} @code{true}.",
6448 unsigned char, 1)
6450 /* Return an unsigned int representing the alignment (in bits) of the atomic
6451 type which maps to machine MODE. This allows alignment to be overridden
6452 as needed. */
6453 DEFHOOK
6454 (atomic_align_for_mode,
6455 "If defined, this function returns an appropriate alignment in bits for an\
6456 atomic object of machine_mode @var{mode}. If 0 is returned then the\
6457 default alignment for the specified mode is used. ",
6458 unsigned int, (machine_mode mode),
6459 hook_uint_mode_0)
6461 DEFHOOK
6462 (atomic_assign_expand_fenv,
6463 "ISO C11 requires atomic compound assignments that may raise floating-point\
6464 exceptions to raise exceptions corresponding to the arithmetic operation\
6465 whose result was successfully stored in a compare-and-exchange sequence. \
6466 This requires code equivalent to calls to @code{feholdexcept},\
6467 @code{feclearexcept} and @code{feupdateenv} to be generated at\
6468 appropriate points in the compare-and-exchange sequence. This hook should\
6469 set @code{*@var{hold}} to an expression equivalent to the call to\
6470 @code{feholdexcept}, @code{*@var{clear}} to an expression equivalent to\
6471 the call to @code{feclearexcept} and @code{*@var{update}} to an expression\
6472 equivalent to the call to @code{feupdateenv}. The three expressions are\
6473 @code{NULL_TREE} on entry to the hook and may be left as @code{NULL_TREE}\
6474 if no code is required in a particular place. The default implementation\
6475 leaves all three expressions as @code{NULL_TREE}. The\
6476 @code{__atomic_feraiseexcept} function from @code{libatomic} may be of use\
6477 as part of the code generated in @code{*@var{update}}.",
6478 void, (tree *hold, tree *clear, tree *update),
6479 default_atomic_assign_expand_fenv)
6481 /* Leave the boolean fields at the end. */
6483 /* True if we can create zeroed data by switching to a BSS section
6484 and then using ASM_OUTPUT_SKIP to allocate the space. */
6485 DEFHOOKPOD
6486 (have_switchable_bss_sections,
6487 "This flag is true if we can create zeroed data by switching to a BSS\n\
6488 section and then using @code{ASM_OUTPUT_SKIP} to allocate the space.\n\
6489 This is true on most ELF targets.",
6490 bool, false)
6492 /* True if "native" constructors and destructors are supported,
6493 false if we're using collect2 for the job. */
6494 DEFHOOKPOD
6495 (have_ctors_dtors,
6496 "This value is true if the target supports some ``native'' method of\n\
6497 collecting constructors and destructors to be run at startup and exit.\n\
6498 It is false if we must use @command{collect2}.",
6499 bool, false)
6501 /* True if thread-local storage is supported. */
6502 DEFHOOKPOD
6503 (have_tls,
6504 "Contains the value true if the target supports thread-local storage.\n\
6505 The default value is false.",
6506 bool, false)
6508 /* True if a small readonly data section is supported. */
6509 DEFHOOKPOD
6510 (have_srodata_section,
6511 "Contains the value true if the target places read-only\n\
6512 ``small data'' into a separate section. The default value is false.",
6513 bool, false)
6515 /* True if EH frame info sections should be zero-terminated. */
6516 DEFHOOKPOD
6517 (terminate_dw2_eh_frame_info,
6518 "Contains the value true if the target should add a zero word onto the\n\
6519 end of a Dwarf-2 frame info section when used for exception handling.\n\
6520 Default value is false if @code{EH_FRAME_SECTION_NAME} is defined, and\n\
6521 true otherwise.",
6522 bool, true)
6524 /* True if #NO_APP should be emitted at the beginning of assembly output. */
6525 DEFHOOKPOD
6526 (asm_file_start_app_off,
6527 "If this flag is true, the text of the macro @code{ASM_APP_OFF} will be\n\
6528 printed as the very first line in the assembly file, unless\n\
6529 @option{-fverbose-asm} is in effect. (If that macro has been defined\n\
6530 to the empty string, this variable has no effect.) With the normal\n\
6531 definition of @code{ASM_APP_OFF}, the effect is to notify the GNU\n\
6532 assembler that it need not bother stripping comments or extra\n\
6533 whitespace from its input. This allows it to work a bit faster.\n\
6535 The default is false. You should not set it to true unless you have\n\
6536 verified that your port does not generate any extra whitespace or\n\
6537 comments that will cause GAS to issue errors in NO_APP mode.",
6538 bool, false)
6540 /* True if output_file_directive should be called for main_input_filename
6541 at the beginning of assembly output. */
6542 DEFHOOKPOD
6543 (asm_file_start_file_directive,
6544 "If this flag is true, @code{output_file_directive} will be called\n\
6545 for the primary source file, immediately after printing\n\
6546 @code{ASM_APP_OFF} (if that is enabled). Most ELF assemblers expect\n\
6547 this to be done. The default is false.",
6548 bool, false)
6550 /* Returns true if we should generate exception tables for use with the
6551 ARM EABI. The effects the encoding of function exception specifications. */
6552 DEFHOOKPOD
6553 (arm_eabi_unwinder,
6554 "This flag should be set to @code{true} on targets that use an ARM EABI\n\
6555 based unwinding library, and @code{false} on other targets. This effects\n\
6556 the format of unwinding tables, and how the unwinder in entered after\n\
6557 running a cleanup. The default is @code{false}.",
6558 bool, false)
6560 DEFHOOKPOD
6561 (want_debug_pub_sections,
6562 "True if the @code{.debug_pubtypes} and @code{.debug_pubnames} sections\
6563 should be emitted. These sections are not used on most platforms, and\
6564 in particular GDB does not use them.",
6565 bool, false)
6567 DEFHOOKPOD
6568 (delay_sched2, "True if sched2 is not to be run at its normal place.\n\
6569 This usually means it will be run as part of machine-specific reorg.",
6570 bool, false)
6572 DEFHOOKPOD
6573 (delay_vartrack, "True if vartrack is not to be run at its normal place.\n\
6574 This usually means it will be run as part of machine-specific reorg.",
6575 bool, false)
6577 DEFHOOKPOD
6578 (no_register_allocation, "True if register allocation and the passes\n\
6579 following it should not be run. Usually true only for virtual assembler\n\
6580 targets.",
6581 bool, false)
6583 /* Leave the boolean fields at the end. */
6585 /* Functions related to mode switching. */
6586 #undef HOOK_PREFIX
6587 #define HOOK_PREFIX "TARGET_MODE_"
6588 HOOK_VECTOR (TARGET_TOGGLE_, mode_switching)
6590 DEFHOOK
6591 (emit,
6592 "Generate one or more insns to set @var{entity} to @var{mode}. @var{hard_reg_live} is the set of hard registers live at the point where the insn(s) are to be inserted. @var{prev_moxde} indicates the mode to switch from. Sets of a lower numbered entity will be emitted before sets of a higher numbered entity to a mode of the same or lower priority.",
6593 void, (int entity, int mode, int prev_mode, HARD_REG_SET regs_live), NULL)
6595 DEFHOOK
6596 (needed,
6597 "@var{entity} is an integer specifying a mode-switched entity. If @code{OPTIMIZE_MODE_SWITCHING} is defined, you must define this macro to return an integer value not larger than the corresponding element in @code{NUM_MODES_FOR_MODE_SWITCHING}, to denote the mode that @var{entity} must be switched into prior to the execution of @var{insn}.",
6598 int, (int entity, rtx_insn *insn), NULL)
6600 DEFHOOK
6601 (after,
6602 "@var{entity} is an integer specifying a mode-switched entity. If this macro is defined, it is evaluated for every @var{insn} during mode switching. It determines the mode that an insn results in (if different from the incoming mode).",
6603 int, (int entity, int mode, rtx_insn *insn), NULL)
6605 DEFHOOK
6606 (entry,
6607 "If this macro is defined, it is evaluated for every @var{entity} that needs mode switching. It should evaluate to an integer, which is a mode that @var{entity} is assumed to be switched to at function entry. If @code{TARGET_MODE_ENTRY} is defined then @code{TARGET_MODE_EXIT} must be defined.",
6608 int, (int entity), NULL)
6610 DEFHOOK
6611 (exit,
6612 "If this macro is defined, it is evaluated for every @var{entity} that needs mode switching. It should evaluate to an integer, which is a mode that @var{entity} is assumed to be switched to at function exit. If @code{TARGET_MODE_EXIT} is defined then @code{TARGET_MODE_ENTRY} must be defined.",
6613 int, (int entity), NULL)
6615 DEFHOOK
6616 (priority,
6617 "This macro specifies the order in which modes for @var{entity} are processed. 0 is the highest priority, @code{NUM_MODES_FOR_MODE_SWITCHING[@var{entity}] - 1} the lowest. The value of the macro should be an integer designating a mode for @var{entity}. For any fixed @var{entity}, @code{mode_priority} (@var{entity}, @var{n}) shall be a bijection in 0 @dots{} @code{num_modes_for_mode_switching[@var{entity}] - 1}.",
6618 int, (int entity, int n), NULL)
6620 HOOK_VECTOR_END (mode_switching)
6622 #undef HOOK_PREFIX
6623 #define HOOK_PREFIX "TARGET_"
6625 #define DEF_TARGET_INSN(NAME, PROTO) \
6626 DEFHOOK_UNDOC (have_##NAME, "", bool, (void), false)
6627 #include "target-insns.def"
6628 #undef DEF_TARGET_INSN
6630 #define DEF_TARGET_INSN(NAME, PROTO) \
6631 DEFHOOK_UNDOC (gen_##NAME, "", rtx_insn *, PROTO, NULL)
6632 #include "target-insns.def"
6633 #undef DEF_TARGET_INSN
6635 #define DEF_TARGET_INSN(NAME, PROTO) \
6636 DEFHOOKPOD (code_for_##NAME, "*", enum insn_code, CODE_FOR_nothing)
6637 #include "target-insns.def"
6638 #undef DEF_TARGET_INSN
6640 DEFHOOK
6641 (run_target_selftests,
6642 "If selftests are enabled, run any selftests for this target.",
6643 void, (void),
6644 NULL)
6646 /* Close the 'struct gcc_target' definition. */
6647 HOOK_VECTOR_END (C90_EMPTY_HACK)