1	/* Target hook definitions.
2	Copyright (C) 2001-2026 Free Software Foundation, Inc.
3
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.
8
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.
13
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/>.
17
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! */
21
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"
25
26	#undef HOOK_TYPE
27	#define HOOK_TYPE "Target Hook"
28
29	HOOK_VECTOR (TARGET_INITIALIZER, gcc_target)
30
31	/* Functions that output assembler for the target. */
32	#define HOOK_PREFIX "TARGET_ASM_"
33	HOOK_VECTOR (TARGET_ASM_OUT, asm_out)
34
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 *, ")")
43
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_PSI_OP\n\
49	@deftypevrx {Target Hook} {const char *} TARGET_ASM_ALIGNED_SI_OP\n\
50	@deftypevrx {Target Hook} {const char *} TARGET_ASM_ALIGNED_PDI_OP\n\
51	@deftypevrx {Target Hook} {const char *} TARGET_ASM_ALIGNED_DI_OP\n\
52	@deftypevrx {Target Hook} {const char *} TARGET_ASM_ALIGNED_PTI_OP\n\
53	@deftypevrx {Target Hook} {const char *} TARGET_ASM_ALIGNED_TI_OP\n\
54	@deftypevrx {Target Hook} {const char *} TARGET_ASM_UNALIGNED_HI_OP\n\
55	@deftypevrx {Target Hook} {const char *} TARGET_ASM_UNALIGNED_PSI_OP\n\
56	@deftypevrx {Target Hook} {const char *} TARGET_ASM_UNALIGNED_SI_OP\n\
57	@deftypevrx {Target Hook} {const char *} TARGET_ASM_UNALIGNED_PDI_OP\n\
58	@deftypevrx {Target Hook} {const char *} TARGET_ASM_UNALIGNED_DI_OP\n\
59	@deftypevrx {Target Hook} {const char *} TARGET_ASM_UNALIGNED_PTI_OP\n\
60	@deftypevrx {Target Hook} {const char *} TARGET_ASM_UNALIGNED_TI_OP\n\
61	These hooks specify assembly directives for creating certain kinds\n\
62	of integer object. The @code{TARGET_ASM_BYTE_OP} directive creates a\n\
63	byte-sized object, the @code{TARGET_ASM_ALIGNED_HI_OP} one creates an\n\
64	aligned two-byte object, and so on. Any of the hooks may be\n\
65	@code{NULL}, indicating that no suitable directive is available.\n\
66	\n\
67	The compiler will print these strings at the start of a new line,\n\
68	followed immediately by the object's initial value. In most cases,\n\
69	the string should contain a tab, a pseudo-op, and then another tab.",
70	const char *, "\t.byte\t")
71	DEFHOOKPOD (aligned_op, "*", struct asm_int_op, TARGET_ASM_ALIGNED_INT_OP)
72	DEFHOOKPOD (unaligned_op, "*", struct asm_int_op, TARGET_ASM_UNALIGNED_INT_OP)
73
74	/* Try to output the assembler code for an integer object whose
75	value is given by X. SIZE is the size of the object in bytes and
76	ALIGNED_P indicates whether it is aligned. Return true if
77	successful. Only handles cases for which BYTE_OP, ALIGNED_OP
78	and UNALIGNED_OP are NULL. */
79	DEFHOOK
80	(integer,
81	"The @code{assemble_integer} function uses this hook to output an\n\
82	integer object. @var{x} is the object's value, @var{size} is its size\n\
83	in bytes and @var{aligned_p} indicates whether it is aligned. The\n\
84	function should return @code{true} if it was able to output the\n\
85	object. If it returns false, @code{assemble_integer} will try to\n\
86	split the object into smaller parts.\n\
87	\n\
88	The default implementation of this hook will use the\n\
89	@code{TARGET_ASM_BYTE_OP} family of strings, returning @code{false}\n\
90	when the relevant string is @code{NULL}.",
91	/* Only handles cases for which BYTE_OP, ALIGNED_OP and UNALIGNED_OP are
92	NULL. */
93	bool, (rtx x, unsigned int size, int aligned_p),
94	default_assemble_integer)
95
96	/* Assembly strings required after the .cfi_startproc label. */
97	DEFHOOK
98	(post_cfi_startproc,
99	"This target hook is used to emit assembly strings required by the target\n\
100	after the .cfi_startproc directive. The first argument is the file stream to\n\
101	write the strings to and the second argument is the function\'s declaration. The\n\
102	expected use is to add more .cfi_* directives.\n\
103	\n\
104	The default is to not output any assembly strings.",
105	void, (FILE *, tree),
106	hook_void_FILEptr_tree)
107
108	/* Notify the backend that we have completed emitting the data for a
109	decl. */
110	DEFHOOK
111	(decl_end,
112	"Define this hook if the target assembler requires a special marker to\n\
113	terminate an initialized variable declaration.",
114	void, (void),
115	hook_void_void)
116
117	/* Output code that will globalize a label. */
118	DEFHOOK
119	(globalize_label,
120	"This target hook is a function to output to the stdio stream\n\
121	@var{stream} some commands that will make the label @var{name} global;\n\
122	that is, available for reference from other files.\n\
123	\n\
124	The default implementation relies on a proper definition of\n\
125	@code{GLOBAL_ASM_OP}.",
126	void, (FILE *stream, const char *name),
127	default_globalize_label)
128
129	/* Output code that will globalize a declaration. */
130	DEFHOOK
131	(globalize_decl_name,
132	"This target hook is a function to output to the stdio stream\n\
133	@var{stream} some commands that will make the name associated with @var{decl}\n\
134	global; that is, available for reference from other files.\n\
135	\n\
136	The default implementation uses the TARGET_ASM_GLOBALIZE_LABEL target hook.",
137	void, (FILE *stream, tree decl), default_globalize_decl_name)
138
139	/* Output code that will declare an external variable. */
140	DEFHOOK
141	(assemble_undefined_decl,
142	"This target hook is a function to output to the stdio stream\n\
143	@var{stream} some commands that will declare the name associated with\n\
144	@var{decl} which is not defined in the current translation unit. Most\n\
145	assemblers do not require anything to be output in this case.",
146	void, (FILE *stream, const char *name, const_tree decl),
147	hook_void_FILEptr_constcharptr_const_tree)
148
149	/* Output code that will emit a label for unwind info, if this
150	target requires such labels. Second argument is the decl the
151	unwind info is associated with, third is a boolean: true if
152	this is for exception handling, fourth is a boolean: true if
153	this is only a placeholder for an omitted FDE. */
154	DEFHOOK
155	(emit_unwind_label,
156	"This target hook emits a label at the beginning of each FDE@. It\n\
157	should be defined on targets where FDEs need special labels, and it\n\
158	should write the appropriate label, for the FDE associated with the\n\
159	function declaration @var{decl}, to the stdio stream @var{stream}.\n\
160	The third argument, @var{for_eh}, is a boolean: true if this is for an\n\
161	exception table. The fourth argument, @var{empty}, is a boolean:\n\
162	true if this is a placeholder label for an omitted FDE@.\n\
163	\n\
164	The default is that FDEs are not given nonlocal labels.",
165	void, (FILE *stream, tree decl, int for_eh, int empty),
166	default_emit_unwind_label)
167
168	/* Output code that will emit a label to divide up the exception table. */
169	DEFHOOK
170	(emit_except_table_label,
171	"This target hook emits a label at the beginning of the exception table.\n\
172	It should be defined on targets where it is desirable for the table\n\
173	to be broken up according to function.\n\
174	\n\
175	The default is that no label is emitted.",
176	void, (FILE *stream),
177	default_emit_except_table_label)
178
179	/* Emit a directive for setting the personality for the function. */
180	DEFHOOK
181	(emit_except_personality,
182	"If the target implements @code{TARGET_ASM_UNWIND_EMIT}, this hook may be\n\
183	used to emit a directive to install a personality hook into the unwind\n\
184	info. This hook should not be used if dwarf2 unwind info is used.",
185	void, (rtx personality),
186	NULL)
187
188	/* If necessary, modify personality and LSDA references to handle
189	indirection. This is used when the assembler supports CFI directives. */
190	DEFHOOK
191	(make_eh_symbol_indirect,
192	"If necessary, modify personality and LSDA references to handle indirection.\n\
193	The original symbol is in @code{origsymbol} and if @code{pubvis} is true\n\
194	the symbol is visible outside the TU.",
195	rtx, (rtx origsymbol, bool pubvis),
196	NULL)
197
198	/* Emit any directives required to unwind this instruction. */
199	DEFHOOK
200	(unwind_emit,
201	"This target hook emits assembly directives required to unwind the\n\
202	given instruction. This is only used when @code{TARGET_EXCEPT_UNWIND_INFO}\n\
203	returns @code{UI_TARGET}.",
204	void, (FILE *stream, rtx_insn *insn),
205	NULL)
206
207	DEFHOOKPOD
208	(unwind_emit_before_insn,
209	"True if the @code{TARGET_ASM_UNWIND_EMIT} hook should be called before\n\
210	the assembly for @var{insn} has been emitted, false if the hook should\n\
211	be called afterward.",
212	bool, true)
213
214	/* Return true if the target needs extra instructions to restore the current
215	frame address after a DW_CFA_restore_state opcode. */
216	DEFHOOK
217	(should_restore_cfa_state,
218	"For DWARF-based unwind frames, two CFI instructions provide for save and\n\
219	restore of register state. GCC maintains the current frame address (CFA)\n\
220	separately from the register bank but the unwinder in libgcc preserves this\n\
221	state along with the registers (and this is expected by the code that writes\n\
222	the unwind frames). This hook allows the target to specify that the CFA data\n\
223	is not saved/restored along with the registers by the target unwinder so that\n\
224	suitable additional instructions should be emitted to restore it.",
225	bool, (void),
226	hook_bool_void_false)
227
228	/* Generate an internal label.
229	For now this is just a wrapper for ASM_GENERATE_INTERNAL_LABEL. */
230	DEFHOOK_UNDOC
231	(generate_internal_label,
232	"",
233	void, (char *buf, const char *prefix, unsigned long labelno),
234	default_generate_internal_label)
235
236	/* Output an internal label. */
237	DEFHOOK
238	(internal_label,
239	"A function to output to the stdio stream @var{stream} a label whose\n\
240	name is made from the string @var{prefix} and the number @var{labelno}.\n\
241	\n\
242	It is absolutely essential that these labels be distinct from the labels\n\
243	used for user-level functions and variables. Otherwise, certain programs\n\
244	will have name conflicts with internal labels.\n\
245	\n\
246	It is desirable to exclude internal labels from the symbol table of the\n\
247	object file. Most assemblers have a naming convention for labels that\n\
248	should be excluded; on many systems, the letter @samp{L} at the\n\
249	beginning of a label has this effect. You should find out what\n\
250	convention your system uses, and follow it.\n\
251	\n\
252	The default version of this function utilizes @code{ASM_GENERATE_INTERNAL_LABEL}.",
253	void, (FILE *stream, const char *prefix, unsigned long labelno),
254	default_internal_label)
255
256	/* Output label for the constant. */
257	DEFHOOK
258	(declare_constant_name,
259	"A target hook to output to the stdio stream @var{file} any text necessary\n\
260	for declaring the name @var{name} of a constant which is being defined. This\n\
261	target hook is responsible for outputting the label definition (perhaps using\n\
262	@code{assemble_label}). The argument @var{exp} is the value of the constant,\n\
263	and @var{size} is the size of the constant in bytes. The @var{name}\n\
264	will be an internal label.\n\
265	\n\
266	The default version of this target hook, define the @var{name} in the\n\
267	usual manner as a label (by means of @code{assemble_label}).\n\
268	\n\
269	You may wish to use @code{ASM_OUTPUT_TYPE_DIRECTIVE} in this target hook.",
270	void, (FILE *file, const char *name, const_tree expr, HOST_WIDE_INT size),
271	default_asm_declare_constant_name)
272
273	/* Emit a ttype table reference to a typeinfo object. */
274	DEFHOOK
275	(ttype,
276	"This hook is used to output a reference from a frame unwinding table to\n\
277	the type_info object identified by @var{sym}. It should return @code{true}\n\
278	if the reference was output. Returning @code{false} will cause the\n\
279	reference to be output using the normal Dwarf2 routines.",
280	bool, (rtx sym),
281	hook_bool_rtx_false)
282
283	/* Emit an assembler directive to set visibility for the symbol
284	associated with the tree decl. */
285	DEFHOOK
286	(assemble_visibility,
287	"This target hook is a function to output to @var{asm_out_file} some\n\
288	commands that will make the symbol(s) associated with @var{decl} have\n\
289	hidden, protected or internal visibility as specified by @var{visibility}.",
290	void, (tree decl, int visibility),
291	default_assemble_visibility)
292
293	DEFHOOK
294	(print_patchable_function_entry,
295	"Generate a patchable area at the function start, consisting of\n\
296	@var{patch_area_size} NOP instructions. If the target supports named\n\
297	sections and if @var{record_p} is true, insert a pointer to the current\n\
298	location in the table of patchable functions. The default implementation\n\
299	of the hook places the table of pointers in the special section named\n\
300	@code{__patchable_function_entries}.",
301	void, (FILE *file, unsigned HOST_WIDE_INT patch_area_size, bool record_p),
302	default_print_patchable_function_entry)
303
304	/* Output the assembler code for entry to a function. */
305	DEFHOOK
306	(function_prologue,
307	"If defined, a function that outputs the assembler code for entry to a\n\
308	function. The prologue is responsible for setting up the stack frame,\n\
309	initializing the frame pointer register, saving registers that must be\n\
310	saved, and allocating @var{size} additional bytes of storage for the\n\
311	local variables. @var{file} is a stdio stream to which the assembler\n\
312	code should be output.\n\
313	\n\
314	The label for the beginning of the function need not be output by this\n\
315	macro. That has already been done when the macro is run.\n\
316	\n\
317	@findex regs_ever_live\n\
318	To determine which registers to save, the macro can refer to the array\n\
319	@code{regs_ever_live}: element @var{r} is nonzero if hard register\n\
320	@var{r} is used anywhere within the function. This implies the function\n\
321	prologue should save register @var{r}, provided it is not one of the\n\
322	call-used registers. (@code{TARGET_ASM_FUNCTION_EPILOGUE} must likewise use\n\
323	@code{regs_ever_live}.)\n\
324	\n\
325	On machines that have ``register windows'', the function entry code does\n\
326	not save on the stack the registers that are in the windows, even if\n\
327	they are supposed to be preserved by function calls; instead it takes\n\
328	appropriate steps to ``push'' the register stack, if any non-call-used\n\
329	registers are used in the function.\n\
330	\n\
331	@findex frame_pointer_needed\n\
332	On machines where functions may or may not have frame-pointers, the\n\
333	function entry code must vary accordingly; it must set up the frame\n\
334	pointer if one is wanted, and not otherwise. To determine whether a\n\
335	frame pointer is in wanted, the macro can refer to the variable\n\
336	@code{frame_pointer_needed}. The variable's value will be 1 at run\n\
337	time in a function that needs a frame pointer. @xref{Elimination}.\n\
338	\n\
339	The function entry code is responsible for allocating any stack space\n\
340	required for the function. This stack space consists of the regions\n\
341	listed below. In most cases, these regions are allocated in the\n\
342	order listed, with the last listed region closest to the top of the\n\
343	stack (the lowest address if @code{STACK_GROWS_DOWNWARD} is defined, and\n\
344	the highest address if it is not defined). You can use a different order\n\
345	for a machine if doing so is more convenient or required for\n\
346	compatibility reasons. Except in cases where required by standard\n\
347	or by a debugger, there is no reason why the stack layout used by GCC\n\
348	need agree with that used by other compilers for a machine.",
349	void, (FILE *file),
350	default_function_pro_epilogue)
351
352	/* Output the assembler code for end of prologue. */
353	DEFHOOK
354	(function_end_prologue,
355	"If defined, a function that outputs assembler code at the end of a\n\
356	prologue. This should be used when the function prologue is being\n\
357	emitted as RTL, and you have some extra assembler that needs to be\n\
358	emitted. @xref{prologue instruction pattern}.",
359	void, (FILE *file),
360	no_asm_to_stream)
361
362	/* Output the assembler code for start of epilogue. */
363	DEFHOOK
364	(function_begin_epilogue,
365	"If defined, a function that outputs assembler code at the start of an\n\
366	epilogue. This should be used when the function epilogue is being\n\
367	emitted as RTL, and you have some extra assembler that needs to be\n\
368	emitted. @xref{epilogue instruction pattern}.",
369	void, (FILE *file),
370	no_asm_to_stream)
371
372	/* Output the assembler code for function exit. */
373	DEFHOOK
374	(function_epilogue,
375	"If defined, a function that outputs the assembler code for exit from a\n\
376	function. The epilogue is responsible for restoring the saved\n\
377	registers and stack pointer to their values when the function was\n\
378	called, and returning control to the caller. This macro takes the\n\
379	same argument as the macro @code{TARGET_ASM_FUNCTION_PROLOGUE}, and the\n\
380	registers to restore are determined from @code{regs_ever_live} and\n\
381	@code{CALL_USED_REGISTERS} in the same way.\n\
382	\n\
383	On some machines, there is a single instruction that does all the work\n\
384	of returning from the function. On these machines, give that\n\
385	instruction the name @samp{return} and do not define the macro\n\
386	@code{TARGET_ASM_FUNCTION_EPILOGUE} at all.\n\
387	\n\
388	Do not define a pattern named @samp{return} if you want the\n\
389	@code{TARGET_ASM_FUNCTION_EPILOGUE} to be used. If you want the target\n\
390	switches to control whether return instructions or epilogues are used,\n\
391	define a @samp{return} pattern with a validity condition that tests the\n\
392	target switches appropriately. If the @samp{return} pattern's validity\n\
393	condition is false, epilogues will be used.\n\
394	\n\
395	On machines where functions may or may not have frame-pointers, the\n\
396	function exit code must vary accordingly. Sometimes the code for these\n\
397	two cases is completely different. To determine whether a frame pointer\n\
398	is wanted, the macro can refer to the variable\n\
399	@code{frame_pointer_needed}. The variable's value will be 1 when compiling\n\
400	a function that needs a frame pointer.\n\
401	\n\
402	Normally, @code{TARGET_ASM_FUNCTION_PROLOGUE} and\n\
403	@code{TARGET_ASM_FUNCTION_EPILOGUE} must treat leaf functions specially.\n\
404	The C variable @code{current_function_is_leaf} is nonzero for such a\n\
405	function. @xref{Leaf Functions}.\n\
406	\n\
407	On some machines, some functions pop their arguments on exit while\n\
408	others leave that for the caller to do. For example, the 68020 when\n\
409	given @option{-mrtd} pops arguments in functions that take a fixed\n\
410	number of arguments.\n\
411	\n\
412	@findex pops_args\n\
413	@findex crtl->args.pops_args\n\
414	Your definition of the macro @code{RETURN_POPS_ARGS} decides which\n\
415	functions pop their own arguments. @code{TARGET_ASM_FUNCTION_EPILOGUE}\n\
416	needs to know what was decided. The number of bytes of the current\n\
417	function's arguments that this function should pop is available in\n\
418	@code{crtl->args.pops_args}. @xref{Scalar Return}.",
419	void, (FILE *file),
420	default_function_pro_epilogue)
421
422	/* Initialize target-specific sections. */
423	DEFHOOK
424	(init_sections,
425	"Define this hook if you need to do something special to set up the\n\
426	@file{varasm.cc} sections, or if your target has some special sections\n\
427	of its own that you need to create.\n\
428	\n\
429	GCC calls this hook after processing the command line, but before writing\n\
430	any assembly code, and before calling any of the section-returning hooks\n\
431	described below.",
432	void, (void),
433	hook_void_void)
434
435	/* Tell assembler to change to section NAME with attributes FLAGS.
436	If DECL is non-NULL, it is the VAR_DECL or FUNCTION_DECL with
437	which this section is associated. */
438	DEFHOOK
439	(named_section,
440	"Output assembly directives to switch to section @var{name}. The section\n\
441	should have attributes as specified by @var{flags}, which is a bit mask\n\
442	of the @code{SECTION_*} flags defined in @file{output.h}. If @var{decl}\n\
443	is non-NULL, it is the @code{VAR_DECL} or @code{FUNCTION_DECL} with which\n\
444	this section is associated.",
445	void, (const char *name, unsigned int flags, tree decl),
446	default_no_named_section)
447
448	/* Tell assembler what section attributes to assign this elf section
449	declaration, using their numerical value. */
450	DEFHOOK
451	(elf_flags_numeric,
452	"This hook can be used to encode ELF section flags for which no letter\n\
453	code has been defined in the assembler. It is called by\n\
454	@code{default_asm_named_section} whenever the section flags need to be\n\
455	emitted in the assembler output. If the hook returns true, then the\n\
456	numerical value for ELF section flags should be calculated from\n\
457	@var{flags} and saved in @var{*num}; the value is printed out instead of the\n\
458	normal sequence of letter codes. If the hook is not defined, or if it\n\
459	returns false, then @var{num} is ignored and the traditional letter sequence\n\
460	is emitted.",
461	bool, (unsigned int flags, unsigned int *num),
462	hook_bool_uint_uintp_false)
463
464	/* Return preferred text (sub)section for function DECL.
465	Main purpose of this function is to separate cold, normal and hot
466	functions. STARTUP is true when function is known to be used only
467	at startup (from static constructors or it is main()).
468	EXIT is true when function is known to be used only at exit
469	(from static destructors).
470	Return NULL if function should go to default text section. */
471	DEFHOOK
472	(function_section,
473	"Return preferred text (sub)section for function @var{decl}.\n\
474	Main purpose of this function is to separate cold, normal and hot\n\
475	functions. @var{startup} is true when function is known to be used only\n\
476	at startup (from static constructors or it is @code{main()}).\n\
477	@var{exit} is true when function is known to be used only at exit\n\
478	(from static destructors).\n\
479	Return NULL if function should go to default text section.",
480	section *, (tree decl, enum node_frequency freq, bool startup, bool exit),
481	default_function_section)
482
483	/* Output the assembler code for function exit. */
484	DEFHOOK
485	(function_switched_text_sections,
486	"Used by the target to emit any assembler directives or additional\n\
487	labels needed when a function is partitioned between different\n\
488	sections. Output should be written to @var{file}. The function\n\
489	decl is available as @var{decl} and the new section is `cold' if\n\
490	@var{new_is_cold} is @code{true}.",
491	void, (FILE *file, tree decl, bool new_is_cold),
492	default_function_switched_text_sections)
493
494	/* Return a mask describing how relocations should be treated when
495	selecting sections. Bit 1 should be set if global relocations
496	should be placed in a read-write section; bit 0 should be set if
497	local relocations should be placed in a read-write section. */
498	DEFHOOK
499	(reloc_rw_mask,
500	"Return a mask describing how relocations should be treated when\n\
501	selecting sections. Bit 1 should be set if global relocations\n\
502	should be placed in a read-write section; bit 0 should be set if\n\
503	local relocations should be placed in a read-write section.\n\
504	\n\
505	The default version of this function returns 3 when @option{-fpic}\n\
506	is in effect, and 0 otherwise. The hook is typically redefined\n\
507	when the target cannot support (some kinds of) dynamic relocations\n\
508	in read-only sections even in executables.",
509	int, (void),
510	default_reloc_rw_mask)
511
512	/* Return a flag for either generating ADDR_DIF_VEC table
513	or ADDR_VEC table for jumps in case of -fPIC/-fPIE. */
514	DEFHOOK
515	(generate_pic_addr_diff_vec,
516	"Return true to generate ADDR_DIF_VEC table\n\
517	or false to generate ADDR_VEC table for jumps in case of -fPIC.\n\
518	\n\
519	The default version of this function returns true if flag_pic\n\
520	equals true and false otherwise",
521	bool, (void),
522	default_generate_pic_addr_diff_vec)
523
524	/* Return a section for EXP. It may be a DECL or a constant. RELOC
525	is nonzero if runtime relocations must be applied; bit 1 will be
526	set if the runtime relocations require non-local name resolution.
527	ALIGN is the required alignment of the data. */
528	DEFHOOK
529	(select_section,
530	"Return the section into which @var{exp} should be placed. You can\n\
531	assume that @var{exp} is either a @code{VAR_DECL} node or a constant of\n\
532	some sort. @var{reloc} indicates whether the initial value of @var{exp}\n\
533	requires link-time relocations. Bit 0 is set when variable contains\n\
534	local relocations only, while bit 1 is set for global relocations.\n\
535	@var{align} is the constant alignment in bits.\n\
536	\n\
537	The default version of this function takes care of putting read-only\n\
538	variables in @code{readonly_data_section}.\n\
539	\n\
540	See also @var{USE_SELECT_SECTION_FOR_FUNCTIONS}.",
541	section *, (tree exp, int reloc, unsigned HOST_WIDE_INT align),
542	default_select_section)
543
544	/* Return a section for X. MODE is X's mode and ALIGN is its
545	alignment in bits. */
546	DEFHOOK
547	(select_rtx_section,
548	"Return the section into which a constant @var{x}, of mode @var{mode},\n\
549	should be placed. You can assume that @var{x} is some kind of\n\
550	constant in RTL@. The argument @var{mode} is redundant except in the\n\
551	case of a @code{const_int} rtx. @var{align} is the constant alignment\n\
552	in bits.\n\
553	\n\
554	The default version of this function takes care of putting symbolic\n\
555	constants in @code{flag_pic} mode in @code{data_section} and everything\n\
556	else in @code{readonly_data_section}.",
557	section *, (machine_mode mode, rtx x, unsigned HOST_WIDE_INT align),
558	default_select_rtx_section)
559
560	/* Select a unique section name for DECL. RELOC is the same as
561	for SELECT_SECTION. */
562	DEFHOOK
563	(unique_section,
564	"Build up a unique section name, expressed as a @code{STRING_CST} node,\n\
565	and assign it to @samp{DECL_SECTION_NAME (@var{decl})}.\n\
566	As with @code{TARGET_ASM_SELECT_SECTION}, @var{reloc} indicates whether\n\
567	the initial value of @var{exp} requires link-time relocations.\n\
568	\n\
569	The default version of this function appends the symbol name to the\n\
570	ELF section name that would normally be used for the symbol. For\n\
571	example, the function @code{foo} would be placed in @code{.text.foo}.\n\
572	Whatever the actual target object format, this is often good enough.",
573	void, (tree decl, int reloc),
574	default_unique_section)
575
576	/* Return the readonly data or relocated readonly data section
577	associated with function DECL. */
578	DEFHOOK
579	(function_rodata_section,
580	"Return the readonly data or reloc readonly data section associated with\n\
581	@samp{DECL_SECTION_NAME (@var{decl})}. @var{relocatable} selects the latter\n\
582	over the former.\n\
583	The default version of this function selects @code{.gnu.linkonce.r.name} if\n\
584	the function's section is @code{.gnu.linkonce.t.name}, @code{.rodata.name}\n\
585	or @code{.data.rel.ro.name} if function is in @code{.text.name}, and\n\
586	the normal readonly-data or reloc readonly data section otherwise.",
587	section *, (tree decl, bool relocatable),
588	default_function_rodata_section)
589
590	/* Nonnull if the target wants to override the default ".rodata" prefix
591	for mergeable data sections. */
592	DEFHOOKPOD
593	(mergeable_rodata_prefix,
594	"Usually, the compiler uses the prefix @code{\".rodata\"} to construct\n\
595	section names for mergeable constant data. Define this macro to override\n\
596	the string if a different section name should be used.",
597	const char *, ".rodata")
598
599	/* Return the section to be used for transactional memory clone tables. */
600	DEFHOOK
601	(tm_clone_table_section,
602	"Return the section that should be used for transactional memory clone\n\
603	tables.",
604	section *, (void), default_clone_table_section)
605
606	/* Output a constructor for a symbol with a given priority. */
607	DEFHOOK
608	(constructor,
609	"If defined, a function that outputs assembler code to arrange to call\n\
610	the function referenced by @var{symbol} at initialization time.\n\
611	\n\
612	Assume that @var{symbol} is a @code{SYMBOL_REF} for a function taking\n\
613	no arguments and with no return value. If the target supports initialization\n\
614	priorities, @var{priority} is a value between 0 and @code{MAX_INIT_PRIORITY};\n\
615	otherwise it must be @code{DEFAULT_INIT_PRIORITY}.\n\
616	\n\
617	If this macro is not defined by the target, a suitable default will\n\
618	be chosen if (1) the target supports arbitrary section names, (2) the\n\
619	target defines @code{CTORS_SECTION_ASM_OP}, or (3) @code{USE_COLLECT2}\n\
620	is not defined.",
621	void, (rtx symbol, int priority), NULL)
622
623	/* Output a destructor for a symbol with a given priority. */
624	DEFHOOK
625	(destructor,
626	"This is like @code{TARGET_ASM_CONSTRUCTOR} but used for termination\n\
627	functions rather than initialization functions.",
628	void, (rtx symbol, int priority), NULL)
629
630	/* Output the assembler code for a thunk function. THUNK_DECL is the
631	declaration for the thunk function itself, FUNCTION is the decl for
632	the target function. DELTA is an immediate constant offset to be
633	added to THIS. If VCALL_OFFSET is nonzero, the word at
634	*(*this + vcall_offset) should be added to THIS. */
635	DEFHOOK
636	(output_mi_thunk,
637	"A function that outputs the assembler code for a thunk\n\
638	function, used to implement C++ virtual function calls with multiple\n\
639	inheritance. The thunk acts as a wrapper around a virtual function,\n\
640	adjusting the implicit object parameter before handing control off to\n\
641	the real function.\n\
642	\n\
643	First, emit code to add the integer @var{delta} to the location that\n\
644	contains the incoming first argument. Assume that this argument\n\
645	contains a pointer, and is the one used to pass the @code{this} pointer\n\
646	in C++. This is the incoming argument @emph{before} the function prologue,\n\
647	e.g.@: @samp{%o0} on a sparc. The addition must preserve the values of\n\
648	all other incoming arguments.\n\
649	\n\
650	Then, if @var{vcall_offset} is nonzero, an additional adjustment should be\n\
651	made after adding @code{delta}. In particular, if @var{p} is the\n\
652	adjusted pointer, the following adjustment should be made:\n\
653	\n\
654	@smallexample\n\
655	p += (*((ptrdiff_t **)p))[vcall_offset/sizeof(ptrdiff_t)]\n\
656	@end smallexample\n\
657	\n\
658	After the additions, emit code to jump to @var{function}, which is a\n\
659	@code{FUNCTION_DECL}. This is a direct pure jump, not a call, and does\n\
660	not touch the return address. Hence returning from @var{FUNCTION} will\n\
661	return to whoever called the current @samp{thunk}.\n\
662	\n\
663	The effect must be as if @var{function} had been called directly with\n\
664	the adjusted first argument. This macro is responsible for emitting all\n\
665	of the code for a thunk function; @code{TARGET_ASM_FUNCTION_PROLOGUE}\n\
666	and @code{TARGET_ASM_FUNCTION_EPILOGUE} are not invoked.\n\
667	\n\
668	The @var{thunk_fndecl} is redundant. (@var{delta} and @var{function}\n\
669	have already been extracted from it.) It might possibly be useful on\n\
670	some targets, but probably not.\n\
671	\n\
672	If you do not define this macro, the target-independent code in the C++\n\
673	front end will generate a less efficient heavyweight thunk that calls\n\
674	@var{function} instead of jumping to it. The generic approach does\n\
675	not support varargs.",
676	void, (FILE *file, tree thunk_fndecl, HOST_WIDE_INT delta,
677	HOST_WIDE_INT vcall_offset, tree function),
678	NULL)
679
680	/* Determine whether output_mi_thunk would succeed. */
681	/* ??? Ideally, this hook would not exist, and success or failure
682	would be returned from output_mi_thunk directly. But there's
683	too much undo-able setup involved in invoking output_mi_thunk.
684	Could be fixed by making output_mi_thunk emit rtl instead of
685	text to the output file. */
686	DEFHOOK
687	(can_output_mi_thunk,
688	"A function that returns true if TARGET_ASM_OUTPUT_MI_THUNK would be able\n\
689	to output the assembler code for the thunk function specified by the\n\
690	arguments it is passed, and false otherwise. In the latter case, the\n\
691	generic approach will be used by the C++ front end, with the limitations\n\
692	previously exposed.",
693	bool, (const_tree thunk_fndecl, HOST_WIDE_INT delta,
694	HOST_WIDE_INT vcall_offset, const_tree function),
695	hook_bool_const_tree_hwi_hwi_const_tree_false)
696
697	/* Output any boilerplate text needed at the beginning of a
698	translation unit. */
699	DEFHOOK
700	(file_start,
701	"Output to @code{asm_out_file} any text which the assembler expects to\n\
702	find at the beginning of a file. The default behavior is controlled\n\
703	by two flags, documented below. Unless your target's assembler is\n\
704	quite unusual, if you override the default, you should call\n\
705	@code{default_file_start} at some point in your target hook. This\n\
706	lets other target files rely on these variables.",
707	void, (void),
708	default_file_start)
709
710	/* Output any boilerplate text needed at the end of a translation unit. */
711	DEFHOOK
712	(file_end,
713	"Output to @code{asm_out_file} any text which the assembler expects\n\
714	to find at the end of a file. The default is to output nothing.",
715	void, (void),
716	hook_void_void)
717
718	/* Output any boilerplate text needed at the beginning of an
719	LTO output stream. */
720	DEFHOOK
721	(lto_start,
722	"Output to @code{asm_out_file} any text which the assembler expects\n\
723	to find at the start of an LTO section. The default is to output\n\
724	nothing.",
725	void, (void),
726	hook_void_void)
727
728	/* Output any boilerplate text needed at the end of an
729	LTO output stream. */
730	DEFHOOK
731	(lto_end,
732	"Output to @code{asm_out_file} any text which the assembler expects\n\
733	to find at the end of an LTO section. The default is to output\n\
734	nothing.",
735	void, (void),
736	hook_void_void)
737
738	/* Output any boilerplace text needed at the end of a
739	translation unit before debug and unwind info is emitted. */
740	DEFHOOK
741	(code_end,
742	"Output to @code{asm_out_file} any text which is needed before emitting\n\
743	unwind info and debug info at the end of a file. Some targets emit\n\
744	here PIC setup thunks that cannot be emitted at the end of file,\n\
745	because they couldn't have unwind info then. The default is to output\n\
746	nothing.",
747	void, (void),
748	hook_void_void)
749
750	/* Output an assembler pseudo-op to declare a library function name
751	external. */
752	DEFHOOK
753	(external_libcall,
754	"This target hook is a function to output to @var{asm_out_file} an assembler\n\
755	pseudo-op to declare a library function name external. The name of the\n\
756	library function is given by @var{symref}, which is a @code{symbol_ref}.",
757	void, (rtx symref),
758	default_external_libcall)
759
760	/* Output an assembler directive to mark decl live. This instructs
761	linker to not dead code strip this symbol. */
762	DEFHOOK
763	(mark_decl_preserved,
764	"This target hook is a function to output to @var{asm_out_file} an assembler\n\
765	directive to annotate @var{symbol} as used. The Darwin target uses the\n\
766	.no_dead_code_strip directive.",
767	void, (const char *symbol),
768	hook_void_constcharptr)
769
770	/* Output a record of the command line switches that have been passed. */
771	DEFHOOK
772	(record_gcc_switches,
773	"Provides the target with the ability to record the gcc command line\n\
774	switches provided as argument.\n\
775	\n\
776	By default this hook is set to NULL, but an example implementation is\n\
777	provided for ELF based targets. Called @var{elf_record_gcc_switches},\n\
778	it records the switches as ASCII text inside a new, string mergeable\n\
779	section in the assembler output file. The name of the new section is\n\
780	provided by the @code{TARGET_ASM_RECORD_GCC_SWITCHES_SECTION} target\n\
781	hook.",
782	void, (const char *),
783	NULL)
784
785	/* The name of the section that the example ELF implementation of
786	record_gcc_switches will use to store the information. Target
787	specific versions of record_gcc_switches may or may not use
788	this information. */
789	DEFHOOKPOD
790	(record_gcc_switches_section,
791	"This is the name of the section that will be created by the example\n\
792	ELF implementation of the @code{TARGET_ASM_RECORD_GCC_SWITCHES} target\n\
793	hook.",
794	const char *, ".GCC.command.line")
795
796	/* Output the definition of a section anchor. */
797	DEFHOOK
798	(output_anchor,
799	"Write the assembly code to define section anchor @var{x}, which is a\n\
800	@code{SYMBOL_REF} for which @samp{SYMBOL_REF_ANCHOR_P (@var{x})} is true.\n\
801	The hook is called with the assembly output position set to the beginning\n\
802	of @code{SYMBOL_REF_BLOCK (@var{x})}.\n\
803	\n\
804	If @code{ASM_OUTPUT_DEF} is available, the hook's default definition uses\n\
805	it to define the symbol as @samp{. + SYMBOL_REF_BLOCK_OFFSET (@var{x})}.\n\
806	If @code{ASM_OUTPUT_DEF} is not available, the hook's default definition\n\
807	is @code{NULL}, which disables the use of section anchors altogether.",
808	void, (rtx x),
809	default_asm_output_anchor)
810
811	DEFHOOK
812	(output_ident,
813	"Output a string based on @var{name}, suitable for the @samp{#ident}\n\
814	directive, or the equivalent directive or pragma in non-C-family languages.\n\
815	If this hook is not defined, nothing is output for the @samp{#ident}\n\
816	directive.",
817	void, (const char *name),
818	hook_void_constcharptr)
819
820	/* Output a DTP-relative reference to a TLS symbol. */
821	DEFHOOK
822	(output_dwarf_dtprel,
823	"If defined, this target hook is a function which outputs a DTP-relative\n\
824	reference to the given TLS symbol of the specified size.",
825	void, (FILE *file, int size, rtx x),
826	NULL)
827
828	/* Some target machines need to postscan each insn after it is output. */
829	DEFHOOK
830	(final_postscan_insn,
831	"If defined, this target hook is a function which is executed just after the\n\
832	output of assembler code for @var{insn}, to change the mode of the assembler\n\
833	if necessary.\n\
834	\n\
835	Here the argument @var{opvec} is the vector containing the operands\n\
836	extracted from @var{insn}, and @var{noperands} is the number of\n\
837	elements of the vector which contain meaningful data for this insn.\n\
838	The contents of this vector are what was used to convert the insn\n\
839	template into assembler code, so you can change the assembler mode\n\
840	by checking the contents of the vector.",
841	void, (FILE *file, rtx_insn *insn, rtx *opvec, int noperands),
842	NULL)
843
844	/* Emit the trampoline template. This hook may be NULL. */
845	DEFHOOK
846	(trampoline_template,
847	"This hook is called by @code{assemble_trampoline_template} to output,\n\
848	on the stream @var{f}, assembler code for a block of data that contains\n\
849	the constant parts of a trampoline. This code should not include a\n\
850	label---the label is taken care of automatically.\n\
851	\n\
852	If you do not define this hook, it means no template is needed\n\
853	for the target. Do not define this hook on systems where the block move\n\
854	code to copy the trampoline into place would be larger than the code\n\
855	to generate it on the spot.",
856	void, (FILE *f),
857	NULL)
858
859	DEFHOOK
860	(output_source_filename,
861	"Output DWARF debugging information which indicates that filename\n\
862	@var{name} is the current source file to the stdio stream @var{file}.\n\
863	\n\
864	This target hook need not be defined if the standard form of output\n\
865	for the file format in use is appropriate.",
866	void ,(FILE *file, const char *name),
867	default_asm_output_source_filename)
868
869	DEFHOOK
870	(output_addr_const_extra,
871	"A target hook to recognize @var{rtx} patterns that @code{output_addr_const}\n\
872	can't deal with, and output assembly code to @var{file} corresponding to\n\
873	the pattern @var{x}. This may be used to allow machine-dependent\n\
874	@code{UNSPEC}s to appear within constants.\n\
875	\n\
876	If target hook fails to recognize a pattern, it must return @code{false},\n\
877	so that a standard error message is printed. If it prints an error message\n\
878	itself, by calling, for example, @code{output_operand_lossage}, it may just\n\
879	return @code{true}.",
880	bool, (FILE *file, rtx x),
881	hook_bool_FILEptr_rtx_false)
882
883	/* ??? The TARGET_PRINT_OPERAND* hooks are part of the asm_out struct,
884	even though that is not reflected in the macro name to override their
885	initializers. */
886	#undef HOOK_PREFIX
887	#define HOOK_PREFIX "TARGET_"
888
889	/* Emit a machine-specific insn operand. */
890	/* ??? tm.texi only documents the old macro PRINT_OPERAND,
891	not this hook, and uses a different name for the argument FILE. */
892	DEFHOOK_UNDOC
893	(print_operand,
894	"",
895	void, (FILE *file, rtx x, int code),
896	default_print_operand)
897
898	/* Emit a machine-specific memory address. */
899	/* ??? tm.texi only documents the old macro PRINT_OPERAND_ADDRESS,
900	not this hook, and uses different argument names. */
901	DEFHOOK_UNDOC
902	(print_operand_address,
903	"",
904	void, (FILE *file, machine_mode mode, rtx addr),
905	default_print_operand_address)
906
907	/* Determine whether CODE is a valid punctuation character for the
908	`print_operand' hook. */
909	/* ??? tm.texi only documents the old macro PRINT_OPERAND_PUNCT_VALID_P,
910	not this hook. */
911	DEFHOOK_UNDOC
912	(print_operand_punct_valid_p,
913	"",
914	bool ,(unsigned char code),
915	default_print_operand_punct_valid_p)
916
917	/* Given a symbol name, perform same mangling as assemble_name and
918	ASM_OUTPUT_LABELREF, returning result as an IDENTIFIER_NODE. */
919	DEFHOOK
920	(mangle_assembler_name,
921	"Given a symbol @var{name}, perform same mangling as @code{varasm.cc}'s\n\
922	@code{assemble_name}, but in memory rather than to a file stream, returning\n\
923	result as an @code{IDENTIFIER_NODE}. Required for correct LTO symtabs. The\n\
924	default implementation calls the @code{TARGET_STRIP_NAME_ENCODING} hook and\n\
925	then prepends the @code{USER_LABEL_PREFIX}, if any.",
926	tree, (const char *name),
927	default_mangle_assembler_name)
928
929	HOOK_VECTOR_END (asm_out)
930
931	/* Functions relating to instruction scheduling. All of these
932	default to null pointers, which haifa-sched.cc looks for and handles. */
933	#undef HOOK_PREFIX
934	#define HOOK_PREFIX "TARGET_SCHED_"
935	HOOK_VECTOR (TARGET_SCHED, sched)
936
937	/* Given the current cost, COST, of an insn, INSN, calculate and
938	return a new cost based on its relationship to DEP_INSN through
939	the dependence LINK. The default is to make no adjustment. */
940	DEFHOOK
941	(adjust_cost,
942	"This function corrects the value of @var{cost} based on the\n\
943	relationship between @var{insn} and @var{dep_insn} through a\n\
944	dependence of type dep_type, and strength @var{dw}. It should return the new\n\
945	value. The default is to make no adjustment to @var{cost}. This can be\n\
946	used for example to specify to the scheduler using the traditional pipeline\n\
947	description that an output- or anti-dependence does not incur the same cost\n\
948	as a data-dependence. If the scheduler using the automaton based pipeline\n\
949	description, the cost of anti-dependence is zero and the cost of\n\
950	output-dependence is maximum of one and the difference of latency\n\
951	times of the first and the second insns. If these values are not\n\
952	acceptable, you could use the hook to modify them too. See also\n\
953	@pxref{Processor pipeline description}.",
954	int, (rtx_insn *insn, int dep_type1, rtx_insn *dep_insn, int cost,
955	unsigned int dw),
956	NULL)
957
958	/* Adjust the priority of an insn as you see fit. Returns the new priority. */
959	DEFHOOK
960	(adjust_priority,
961	"This hook adjusts the integer scheduling priority @var{priority} of\n\
962	@var{insn}. It should return the new priority. Increase the priority to\n\
963	execute @var{insn} earlier, reduce the priority to execute @var{insn}\n\
964	later. Do not define this hook if you do not need to adjust the\n\
965	scheduling priorities of insns.",
966	int, (rtx_insn *insn, int priority), NULL)
967
968	/* Function which returns the maximum number of insns that can be
969	scheduled in the same machine cycle. This must be constant
970	over an entire compilation. The default is 1. */
971	DEFHOOK
972	(issue_rate,
973	"This hook returns the maximum number of instructions that can ever\n\
974	issue at the same time on the target machine. The default is one.\n\
975	Although the insn scheduler can define itself the possibility of issue\n\
976	an insn on the same cycle, the value can serve as an additional\n\
977	constraint to issue insns on the same simulated processor cycle (see\n\
978	hooks @samp{TARGET_SCHED_REORDER} and @samp{TARGET_SCHED_REORDER2}).\n\
979	This value must be constant over the entire compilation. If you need\n\
980	it to vary depending on what the instructions are, you must use\n\
981	@samp{TARGET_SCHED_VARIABLE_ISSUE}.",
982	int, (void), NULL)
983
984	/* Calculate how much this insn affects how many more insns we
985	can emit this cycle. Default is they all cost the same. */
986	DEFHOOK
987	(variable_issue,
988	"This hook is executed by the scheduler after it has scheduled an insn\n\
989	from the ready list. It should return the number of insns which can\n\
990	still be issued in the current cycle. The default is\n\
991	@samp{@w{@var{more} - 1}} for insns other than @code{CLOBBER} and\n\
992	@code{USE}, which normally are not counted against the issue rate.\n\
993	You should define this hook if some insns take more machine resources\n\
994	than others, so that fewer insns can follow them in the same cycle.\n\
995	@var{file} is either a null pointer, or a stdio stream to write any\n\
996	debug output to. @var{verbose} is the verbose level provided by\n\
997	@option{-fsched-verbose-@var{n}}. @var{insn} is the instruction that\n\
998	was scheduled.",
999	int, (FILE *file, int verbose, rtx_insn *insn, int more), NULL)
1000
1001	/* Initialize machine-dependent scheduling code. */
1002	DEFHOOK
1003	(init,
1004	"This hook is executed by the scheduler at the beginning of each block of\n\
1005	instructions that are to be scheduled. @var{file} is either a null\n\
1006	pointer, or a stdio stream to write any debug output to. @var{verbose}\n\
1007	is the verbose level provided by @option{-fsched-verbose-@var{n}}.\n\
1008	@var{max_ready} is the maximum number of insns in the current scheduling\n\
1009	region that can be live at the same time. This can be used to allocate\n\
1010	scratch space if it is needed, e.g.@: by @samp{TARGET_SCHED_REORDER}.",
1011	void, (FILE *file, int verbose, int max_ready), NULL)
1012
1013	/* Finalize machine-dependent scheduling code. */
1014	DEFHOOK
1015	(finish,
1016	"This hook is executed by the scheduler at the end of each block of\n\
1017	instructions that are to be scheduled. It can be used to perform\n\
1018	cleanup of any actions done by the other scheduling hooks. @var{file}\n\
1019	is either a null pointer, or a stdio stream to write any debug output\n\
1020	to. @var{verbose} is the verbose level provided by\n\
1021	@option{-fsched-verbose-@var{n}}.",
1022	void, (FILE *file, int verbose), NULL)
1023
1024	/* Initialize machine-dependent function wide scheduling code. */
1025	DEFHOOK
1026	(init_global,
1027	"This hook is executed by the scheduler after function level initializations.\n\
1028	@var{file} is either a null pointer, or a stdio stream to write any debug output to.\n\
1029	@var{verbose} is the verbose level provided by @option{-fsched-verbose-@var{n}}.\n\
1030	@var{old_max_uid} is the maximum insn uid when scheduling begins.",
1031	void, (FILE *file, int verbose, int old_max_uid), NULL)
1032
1033	/* Finalize machine-dependent function wide scheduling code. */
1034	DEFHOOK
1035	(finish_global,
1036	"This is the cleanup hook corresponding to @code{TARGET_SCHED_INIT_GLOBAL}.\n\
1037	@var{file} is either a null pointer, or a stdio stream to write any debug output to.\n\
1038	@var{verbose} is the verbose level provided by @option{-fsched-verbose-@var{n}}.",
1039	void, (FILE *file, int verbose), NULL)
1040
1041	/* Reorder insns in a machine-dependent fashion, in two different
1042	places. Default does nothing. */
1043	DEFHOOK
1044	(reorder,
1045	"This hook is executed by the scheduler after it has scheduled the ready\n\
1046	list, to allow the machine description to reorder it (for example to\n\
1047	combine two small instructions together on @samp{VLIW} machines).\n\
1048	@var{file} is either a null pointer, or a stdio stream to write any\n\
1049	debug output to. @var{verbose} is the verbose level provided by\n\
1050	@option{-fsched-verbose-@var{n}}. @var{ready} is a pointer to the ready\n\
1051	list of instructions that are ready to be scheduled. @var{n_readyp} is\n\
1052	a pointer to the number of elements in the ready list. The scheduler\n\
1053	reads the ready list in reverse order, starting with\n\
1054	@var{ready}[@var{*n_readyp} @minus{} 1] and going to @var{ready}[0]. @var{clock}\n\
1055	is the timer tick of the scheduler. You may modify the ready list and\n\
1056	the number of ready insns. The return value is the number of insns that\n\
1057	can issue this cycle; normally this is just @code{issue_rate}. See also\n\
1058	@samp{TARGET_SCHED_REORDER2}.",
1059	int, (FILE *file, int verbose, rtx_insn **ready, int *n_readyp, int clock), NULL)
1060
1061	DEFHOOK
1062	(reorder2,
1063	"Like @samp{TARGET_SCHED_REORDER}, but called at a different time. That\n\
1064	function is called whenever the scheduler starts a new cycle. This one\n\
1065	is called once per iteration over a cycle, immediately after\n\
1066	@samp{TARGET_SCHED_VARIABLE_ISSUE}; it can reorder the ready list and\n\
1067	return the number of insns to be scheduled in the same cycle. Defining\n\
1068	this hook can be useful if there are frequent situations where\n\
1069	scheduling one insn causes other insns to become ready in the same\n\
1070	cycle. These other insns can then be taken into account properly.",
1071	int, (FILE *file, int verbose, rtx_insn **ready, int *n_readyp, int clock), NULL)
1072
1073	DEFHOOK
1074	(macro_fusion_p,
1075	"This hook is used to check whether target platform supports macro fusion.",
1076	bool, (void), NULL)
1077
1078	DEFHOOK
1079	(macro_fusion_pair_p,
1080	"This hook is used to check whether two insns should be macro fused for\n\
1081	a target microarchitecture. If this hook returns true for the given insn pair\n\
1082	(@var{prev} and @var{curr}), the scheduler will put them into a sched\n\
1083	group, and they will not be scheduled apart. The two insns will be either\n\
1084	two SET insns or a compare and a conditional jump and this hook should\n\
1085	validate any dependencies needed to fuse the two insns together.",
1086	bool, (rtx_insn *prev, rtx_insn *curr), NULL)
1087
1088	/* The following member value is a pointer to a function called
1089	after evaluation forward dependencies of insns in chain given
1090	by two parameter values (head and tail correspondingly). */
1091	DEFHOOK
1092	(dependencies_evaluation_hook,
1093	"This hook is called after evaluation forward dependencies of insns in\n\
1094	chain given by two parameter values (@var{head} and @var{tail}\n\
1095	correspondingly) but before insns scheduling of the insn chain. For\n\
1096	example, it can be used for better insn classification if it requires\n\
1097	analysis of dependencies. This hook can use backward and forward\n\
1098	dependencies of the insn scheduler because they are already\n\
1099	calculated.",
1100	void, (rtx_insn *head, rtx_insn *tail), NULL)
1101
1102	/* The values of the following four members are pointers to functions
1103	used to simplify the automaton descriptions. dfa_pre_cycle_insn and
1104	dfa_post_cycle_insn give functions returning insns which are used to
1105	change the pipeline hazard recognizer state when the new simulated
1106	processor cycle correspondingly starts and finishes. The function
1107	defined by init_dfa_pre_cycle_insn and init_dfa_post_cycle_insn are
1108	used to initialize the corresponding insns. The default values of
1109	the members result in not changing the automaton state when the
1110	new simulated processor cycle correspondingly starts and finishes. */
1111
1112	DEFHOOK
1113	(init_dfa_pre_cycle_insn,
1114	"The hook can be used to initialize data used by the previous hook.",
1115	void, (void), NULL)
1116
1117	DEFHOOK
1118	(dfa_pre_cycle_insn,
1119	"The hook returns an RTL insn. The automaton state used in the\n\
1120	pipeline hazard recognizer is changed as if the insn were scheduled\n\
1121	when the new simulated processor cycle starts. Usage of the hook may\n\
1122	simplify the automaton pipeline description for some @acronym{VLIW}\n\
1123	processors. If the hook is defined, it is used only for the automaton\n\
1124	based pipeline description. The default is not to change the state\n\
1125	when the new simulated processor cycle starts.",
1126	rtx, (void), NULL)
1127
1128	DEFHOOK
1129	(init_dfa_post_cycle_insn,
1130	"The hook is analogous to @samp{TARGET_SCHED_INIT_DFA_PRE_CYCLE_INSN} but\n\
1131	used to initialize data used by the previous hook.",
1132	void, (void), NULL)
1133
1134	DEFHOOK
1135	(dfa_post_cycle_insn,
1136	"The hook is analogous to @samp{TARGET_SCHED_DFA_PRE_CYCLE_INSN} but used\n\
1137	to changed the state as if the insn were scheduled when the new\n\
1138	simulated processor cycle finishes.",
1139	rtx_insn *, (void), NULL)
1140
1141	/* The values of the following two members are pointers to
1142	functions used to simplify the automaton descriptions.
1143	dfa_pre_advance_cycle and dfa_post_advance_cycle are getting called
1144	immediately before and after cycle is advanced. */
1145
1146	DEFHOOK
1147	(dfa_pre_advance_cycle,
1148	"The hook to notify target that the current simulated cycle is about to finish.\n\
1149	The hook is analogous to @samp{TARGET_SCHED_DFA_PRE_CYCLE_INSN} but used\n\
1150	to change the state in more complicated situations - e.g., when advancing\n\
1151	state on a single insn is not enough.",
1152	void, (void), NULL)
1153
1154	DEFHOOK
1155	(dfa_post_advance_cycle,
1156	"The hook to notify target that new simulated cycle has just started.\n\
1157	The hook is analogous to @samp{TARGET_SCHED_DFA_POST_CYCLE_INSN} but used\n\
1158	to change the state in more complicated situations - e.g., when advancing\n\
1159	state on a single insn is not enough.",
1160	void, (void), NULL)
1161
1162	/* The following member value is a pointer to a function returning value
1163	which defines how many insns in queue `ready' will we try for
1164	multi-pass scheduling. If the member value is nonzero and the
1165	function returns positive value, the DFA based scheduler will make
1166	multi-pass scheduling for the first cycle. In other words, we will
1167	try to choose ready insn which permits to start maximum number of
1168	insns on the same cycle. */
1169	DEFHOOK
1170	(first_cycle_multipass_dfa_lookahead,
1171	"This hook controls better choosing an insn from the ready insn queue\n\
1172	for the @acronym{DFA}-based insn scheduler. Usually the scheduler\n\
1173	chooses the first insn from the queue. If the hook returns a positive\n\
1174	value, an additional scheduler code tries all permutations of\n\
1175	@samp{TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD ()}\n\
1176	subsequent ready insns to choose an insn whose issue will result in\n\
1177	maximal number of issued insns on the same cycle. For the\n\
1178	@acronym{VLIW} processor, the code could actually solve the problem of\n\
1179	packing simple insns into the @acronym{VLIW} insn. Of course, if the\n\
1180	rules of @acronym{VLIW} packing are described in the automaton.\n\
1181	\n\
1182	This code also could be used for superscalar @acronym{RISC}\n\
1183	processors. Let us consider a superscalar @acronym{RISC} processor\n\
1184	with 3 pipelines. Some insns can be executed in pipelines @var{A} or\n\
1185	@var{B}, some insns can be executed only in pipelines @var{B} or\n\
1186	@var{C}, and one insn can be executed in pipeline @var{B}. The\n\
1187	processor may issue the 1st insn into @var{A} and the 2nd one into\n\
1188	@var{B}. In this case, the 3rd insn will wait for freeing @var{B}\n\
1189	until the next cycle. If the scheduler issues the 3rd insn the first,\n\
1190	the processor could issue all 3 insns per cycle.\n\
1191	\n\
1192	Actually this code demonstrates advantages of the automaton based\n\
1193	pipeline hazard recognizer. We try quickly and easy many insn\n\
1194	schedules to choose the best one.\n\
1195	\n\
1196	The default is no multipass scheduling.",
1197	int, (void), NULL)
1198
1199	/* The following member value is pointer to a function controlling
1200	what insns from the ready insn queue will be considered for the
1201	multipass insn scheduling. If the hook returns zero for insn
1202	passed as the parameter, the insn will be not chosen to be issued. */
1203	DEFHOOK
1204	(first_cycle_multipass_dfa_lookahead_guard,
1205	"\n\
1206	This hook controls what insns from the ready insn queue will be\n\
1207	considered for the multipass insn scheduling. If the hook returns\n\
1208	zero for @var{insn}, the insn will be considered in multipass scheduling.\n\
1209	Positive return values will remove @var{insn} from consideration on\n\
1210	the current round of multipass scheduling.\n\
1211	Negative return values will remove @var{insn} from consideration for given\n\
1212	number of cycles.\n\
1213	Backends should be careful about returning non-zero for highest priority\n\
1214	instruction at position 0 in the ready list. @var{ready_index} is passed\n\
1215	to allow backends make correct judgements.\n\
1216	\n\
1217	The default is that any ready insns can be chosen to be issued.",
1218	int, (rtx_insn *insn, int ready_index), NULL)
1219
1220	/* This hook prepares the target for a new round of multipass
1221	scheduling.
1222	DATA is a pointer to target-specific data used for multipass scheduling.
1223	READY_TRY and N_READY represent the current state of search in the
1224	optimization space. The target can filter out instructions that
1225	should not be tried during current round by setting corresponding
1226	elements in READY_TRY to non-zero.
1227	FIRST_CYCLE_INSN_P is true if this is the first round of multipass
1228	scheduling on current cycle. */
1229	DEFHOOK
1230	(first_cycle_multipass_begin,
1231	"This hook prepares the target backend for a new round of multipass\n\
1232	scheduling.",
1233	void, (void *data, signed char *ready_try, int n_ready, bool first_cycle_insn_p),
1234	NULL)
1235
1236	/* This hook is called when multipass scheduling evaluates instruction INSN.
1237	DATA is a pointer to target-specific data that can be used to record effects
1238	of INSN on CPU that are not described in DFA.
1239	READY_TRY and N_READY represent the current state of search in the
1240	optimization space. The target can filter out instructions that
1241	should not be tried after issuing INSN by setting corresponding
1242	elements in READY_TRY to non-zero.
1243	INSN is the instruction being evaluated.
1244	PREV_DATA is a pointer to target-specific data corresponding
1245	to a state before issuing INSN. */
1246	DEFHOOK
1247	(first_cycle_multipass_issue,
1248	"This hook is called when multipass scheduling evaluates instruction INSN.",
1249	void, (void *data, signed char *ready_try, int n_ready, rtx_insn *insn,
1250	const void *prev_data), NULL)
1251
1252	/* This hook is called when multipass scheduling backtracks from evaluation of
1253	instruction corresponding to DATA.
1254	DATA is a pointer to target-specific data that stores the effects
1255	of instruction from which the algorithm backtracks on CPU that are not
1256	described in DFA.
1257	READY_TRY and N_READY represent the current state of search in the
1258	optimization space. The target can filter out instructions that
1259	should not be tried after issuing INSN by setting corresponding
1260	elements in READY_TRY to non-zero. */
1261	DEFHOOK
1262	(first_cycle_multipass_backtrack,
1263	"This is called when multipass scheduling backtracks from evaluation of\n\
1264	an instruction.",
1265	void, (const void *data, signed char *ready_try, int n_ready), NULL)
1266
1267	/* This hook notifies the target about the result of the concluded current
1268	round of multipass scheduling.
1269	DATA is a pointer.
1270	If DATA is non-NULL it points to target-specific data used for multipass
1271	scheduling which corresponds to instruction at the start of the chain of
1272	the winning solution. DATA is NULL when multipass scheduling cannot find
1273	a good enough solution on current cycle and decides to retry later,
1274	usually after advancing the cycle count. */
1275	DEFHOOK
1276	(first_cycle_multipass_end,
1277	"This hook notifies the target about the result of the concluded current\n\
1278	round of multipass scheduling.",
1279	void, (const void *data), NULL)
1280
1281	/* This hook is called to initialize target-specific data for multipass
1282	scheduling after it has been allocated.
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_init,
1288	"This hook initializes target-specific data used in multipass scheduling.",
1289	void, (void *data), NULL)
1290
1291	/* This hook is called to finalize target-specific data for multipass
1292	scheduling before it is deallocated.
1293	DATA is a pointer to target-specific data that stores the effects
1294	of instruction from which the algorithm backtracks on CPU that are not
1295	described in DFA. */
1296	DEFHOOK
1297	(first_cycle_multipass_fini,
1298	"This hook finalizes target-specific data used in multipass scheduling.",
1299	void, (void *data), NULL)
1300
1301	/* The following member value is pointer to a function called by
1302	the insn scheduler before issuing insn passed as the third
1303	parameter on given cycle. If the hook returns nonzero, the
1304	insn is not issued on given processors cycle. Instead of that,
1305	the processor cycle is advanced. If the value passed through
1306	the last parameter is zero, the insn ready queue is not sorted
1307	on the new cycle start as usually. The first parameter passes
1308	file for debugging output. The second one passes the scheduler
1309	verbose level of the debugging output. The forth and the fifth
1310	parameter values are correspondingly processor cycle on which
1311	the previous insn has been issued and the current processor cycle. */
1312	DEFHOOK
1313	(dfa_new_cycle,
1314	"This hook is called by the insn scheduler before issuing @var{insn}\n\
1315	on cycle @var{clock}. If the hook returns nonzero,\n\
1316	@var{insn} is not issued on this processor cycle. Instead,\n\
1317	the processor cycle is advanced. If *@var{sort_p}\n\
1318	is zero, the insn ready queue is not sorted on the new cycle\n\
1319	start as usually. @var{dump} and @var{verbose} specify the file and\n\
1320	verbosity level to use for debugging output.\n\
1321	@var{last_clock} and @var{clock} are, respectively, the\n\
1322	processor cycle on which the previous insn has been issued,\n\
1323	and the current processor cycle.",
1324	int, (FILE *dump, int verbose, rtx_insn *insn, int last_clock,
1325	int clock, int *sort_p),
1326	NULL)
1327
1328	/* The following member value is a pointer to a function called by the
1329	insn scheduler. It should return true if there exists a dependence
1330	which is considered costly by the target, between the insn
1331	DEP_PRO (&_DEP), and the insn DEP_CON (&_DEP). The first parameter is
1332	the dep that represents the dependence between the two insns. The
1333	second argument is the cost of the dependence as estimated by
1334	the scheduler. The last argument is the distance in cycles
1335	between the already scheduled insn (first parameter) and the
1336	second insn (second parameter). */
1337	DEFHOOK
1338	(is_costly_dependence,
1339	"This hook is used to define which dependences are considered costly by\n\
1340	the target, so costly that it is not advisable to schedule the insns that\n\
1341	are involved in the dependence too close to one another. The parameters\n\
1342	to this hook are as follows: The first parameter @var{_dep} is the dependence\n\
1343	being evaluated. The second parameter @var{cost} is the cost of the\n\
1344	dependence as estimated by the scheduler, and the third\n\
1345	parameter @var{distance} is the distance in cycles between the two insns.\n\
1346	The hook returns @code{true} if considering the distance between the two\n\
1347	insns the dependence between them is considered costly by the target,\n\
1348	and @code{false} otherwise.\n\
1349	\n\
1350	Defining this hook can be useful in multiple-issue out-of-order machines,\n\
1351	where (a) it's practically hopeless to predict the actual data/resource\n\
1352	delays, however: (b) there's a better chance to predict the actual grouping\n\
1353	that will be formed, and (c) correctly emulating the grouping can be very\n\
1354	important. In such targets one may want to allow issuing dependent insns\n\
1355	closer to one another---i.e., closer than the dependence distance; however,\n\
1356	not in cases of ``costly dependences'', which this hooks allows to define.",
1357	bool, (struct _dep *_dep, int cost, int distance), NULL)
1358
1359	/* The following member value is a pointer to a function called
1360	by the insn scheduler. This hook is called to notify the backend
1361	that new instructions were emitted. */
1362	DEFHOOK
1363	(h_i_d_extended,
1364	"This hook is called by the insn scheduler after emitting a new instruction to\n\
1365	the instruction stream. The hook notifies a target backend to extend its\n\
1366	per instruction data structures.",
1367	void, (void), NULL)
1368
1369	/* Next 5 functions are for multi-point scheduling. */
1370
1371	/* Allocate memory for scheduler context. */
1372	DEFHOOK
1373	(alloc_sched_context,
1374	"Return a pointer to a store large enough to hold target scheduling context.",
1375	void *, (void), NULL)
1376
1377	/* Fills the context from the local machine scheduler context. */
1378	DEFHOOK
1379	(init_sched_context,
1380	"Initialize store pointed to by @var{tc} to hold target scheduling context.\n\
1381	It @var{clean_p} is true then initialize @var{tc} as if scheduler is at the\n\
1382	beginning of the block. Otherwise, copy the current context into @var{tc}.",
1383	void, (void *tc, bool clean_p), NULL)
1384
1385	/* Sets local machine scheduler context to a saved value. */
1386	DEFHOOK
1387	(set_sched_context,
1388	"Copy target scheduling context pointed to by @var{tc} to the current context.",
1389	void, (void *tc), NULL)
1390
1391	/* Clears a scheduler context so it becomes like after init. */
1392	DEFHOOK
1393	(clear_sched_context,
1394	"Deallocate internal data in target scheduling context pointed to by @var{tc}.",
1395	void, (void *tc), NULL)
1396
1397	/* Frees the scheduler context. */
1398	DEFHOOK
1399	(free_sched_context,
1400	"Deallocate a store for target scheduling context pointed to by @var{tc}.",
1401	void, (void *tc), NULL)
1402
1403	/* The following member value is a pointer to a function called
1404	by the insn scheduler.
1405	The first parameter is an instruction, the second parameter is the type
1406	of the requested speculation, and the third parameter is a pointer to the
1407	speculative pattern of the corresponding type (set if return value == 1).
1408	It should return
1409	-1, if there is no pattern, that will satisfy the requested speculation type,
1410	0, if current pattern satisfies the requested speculation type,
1411	1, if pattern of the instruction should be changed to the newly
1412	generated one. */
1413	DEFHOOK
1414	(speculate_insn,
1415	"This hook is called by the insn scheduler when @var{insn} has only\n\
1416	speculative dependencies and therefore can be scheduled speculatively.\n\
1417	The hook is used to check if the pattern of @var{insn} has a speculative\n\
1418	version and, in case of successful check, to generate that speculative\n\
1419	pattern. The hook should return 1, if the instruction has a speculative form,\n\
1420	or @minus{}1, if it doesn't. @var{request} describes the type of requested\n\
1421	speculation. If the return value equals 1 then @var{new_pat} is assigned\n\
1422	the generated speculative pattern.",
1423	int, (rtx_insn *insn, unsigned int dep_status, rtx *new_pat), NULL)
1424
1425	/* The following member value is a pointer to a function called
1426	by the insn scheduler. It should return true if the check instruction
1427	passed as the parameter needs a recovery block. */
1428	DEFHOOK
1429	(needs_block_p,
1430	"This hook is called by the insn scheduler during generation of recovery code\n\
1431	for @var{insn}. It should return @code{true}, if the corresponding check\n\
1432	instruction should branch to recovery code, or @code{false} otherwise.",
1433	bool, (unsigned int dep_status), NULL)
1434
1435	/* The following member value is a pointer to a function called
1436	by the insn scheduler. It should return a pattern for the check
1437	instruction.
1438	The first parameter is a speculative instruction, the second parameter
1439	is the label of the corresponding recovery block (or null, if it is a
1440	simple check). The third parameter is the kind of speculation that
1441	is being performed. */
1442	DEFHOOK
1443	(gen_spec_check,
1444	"This hook is called by the insn scheduler to generate a pattern for recovery\n\
1445	check instruction. If @var{mutate_p} is zero, then @var{insn} is a\n\
1446	speculative instruction for which the check should be generated.\n\
1447	@var{label} is either a label of a basic block, where recovery code should\n\
1448	be emitted, or a null pointer, when requested check doesn't branch to\n\
1449	recovery code (a simple check). If @var{mutate_p} is nonzero, then\n\
1450	a pattern for a branchy check corresponding to a simple check denoted by\n\
1451	@var{insn} should be generated. In this case @var{label} can't be null.",
1452	rtx, (rtx_insn *insn, rtx_insn *label, unsigned int ds), NULL)
1453
1454	/* The following member value is a pointer to a function that provides
1455	information about the speculation capabilities of the target.
1456	The parameter is a pointer to spec_info variable. */
1457	DEFHOOK
1458	(set_sched_flags,
1459	"This hook is used by the insn scheduler to find out what features should be\n\
1460	enabled/used.\n\
1461	The structure *@var{spec_info} should be filled in by the target.\n\
1462	The structure describes speculation types that can be used in the scheduler.",
1463	void, (struct spec_info_def *spec_info), NULL)
1464
1465	DEFHOOK_UNDOC
1466	(get_insn_spec_ds,
1467	"Return speculation types of instruction @var{insn}.",
1468	unsigned int, (rtx_insn *insn), NULL)
1469
1470	DEFHOOK_UNDOC
1471	(get_insn_checked_ds,
1472	"Return speculation types that are checked for instruction @var{insn}",
1473	unsigned int, (rtx_insn *insn), NULL)
1474
1475	DEFHOOK
1476	(can_speculate_insn,
1477	"Some instructions should never be speculated by the schedulers, usually\n\
1478	because the instruction is too expensive to get this wrong. Often such\n\
1479	instructions have long latency, and often they are not fully modeled in the\n\
1480	pipeline descriptions. This hook should return @code{false} if @var{insn}\n\
1481	should not be speculated.",
1482	bool, (rtx_insn *insn), hook_bool_rtx_insn_true)
1483
1484	DEFHOOK_UNDOC
1485	(skip_rtx_p,
1486	"Return bool if rtx scanning should just skip current layer and\
1487	advance to the inner rtxes.",
1488	bool, (const_rtx x), NULL)
1489
1490	/* The following member value is a pointer to a function that provides
1491	information about the target resource-based lower bound which is
1492	used by the swing modulo scheduler. The parameter is a pointer
1493	to ddg variable. */
1494	DEFHOOK
1495	(sms_res_mii,
1496	"This hook is called by the swing modulo scheduler to calculate a\n\
1497	resource-based lower bound which is based on the resources available in\n\
1498	the machine and the resources required by each instruction. The target\n\
1499	backend can use @var{g} to calculate such bound. A very simple lower\n\
1500	bound will be used in case this hook is not implemented: the total number\n\
1501	of instructions divided by the issue rate.",
1502	int, (struct ddg *g), NULL)
1503
1504	/* The following member value is a function that initializes dispatch
1505	schedling and adds instructions to dispatch window according to its
1506	parameters. */
1507	DEFHOOK
1508	(dispatch_do,
1509	"This hook is called by Haifa Scheduler. It performs the operation specified\n\
1510	in its second parameter.",
1511	void, (rtx_insn *insn, int x),
1512	hook_void_rtx_insn_int)
1513
1514	/* The following member value is a function that returns true is
1515	dispatch schedling is supported in hardware and condition passed
1516	as the second parameter is true. */
1517	DEFHOOK
1518	(dispatch,
1519	"This hook is called by Haifa Scheduler. It returns true if dispatch scheduling\n\
1520	is supported in hardware and the condition specified in the parameter is true.",
1521	bool, (rtx_insn *insn, int x),
1522	hook_bool_rtx_insn_int_false)
1523
1524	DEFHOOKPOD
1525	(exposed_pipeline,
1526	"True if the processor has an exposed pipeline, which means that not just\n\
1527	the order of instructions is important for correctness when scheduling, but\n\
1528	also the latencies of operations.",
1529	bool, false)
1530
1531	/* The following member value is a function that returns number
1532	of operations reassociator should try to put in parallel for
1533	statements of the given type. By default 1 is used. */
1534	DEFHOOK
1535	(reassociation_width,
1536	"This hook is called by tree reassociator to determine a level of\n\
1537	parallelism required in output calculations chain.",
1538	int, (unsigned int opc, machine_mode mode),
1539	hook_int_uint_mode_1)
1540
1541	/* The following member value is a function that returns priority for
1542	fusion of each instruction via pointer parameters. */
1543	DEFHOOK
1544	(fusion_priority,
1545	"This hook is called by scheduling fusion pass. It calculates fusion\n\
1546	priorities for each instruction passed in by parameter. The priorities\n\
1547	are returned via pointer parameters.\n\
1548	\n\
1549	@var{insn} is the instruction whose priorities need to be calculated.\n\
1550	@var{max_pri} is the maximum priority can be returned in any cases.\n\
1551	@var{fusion_pri} is the pointer parameter through which @var{insn}'s\n\
1552	fusion priority should be calculated and returned.\n\
1553	@var{pri} is the pointer parameter through which @var{insn}'s priority\n\
1554	should be calculated and returned.\n\
1555	\n\
1556	Same @var{fusion_pri} should be returned for instructions which should\n\
1557	be scheduled together. Different @var{pri} should be returned for\n\
1558	instructions with same @var{fusion_pri}. @var{fusion_pri} is the major\n\
1559	sort key, @var{pri} is the minor sort key. All instructions will be\n\
1560	scheduled according to the two priorities. All priorities calculated\n\
1561	should be between 0 (exclusive) and @var{max_pri} (inclusive). To avoid\n\
1562	false dependencies, @var{fusion_pri} of instructions which need to be\n\
1563	scheduled together should be smaller than @var{fusion_pri} of irrelevant\n\
1564	instructions.\n\
1565	\n\
1566	Given below example:\n\
1567	\n\
1568	@smallexample\n\
1569	ldr r10, [r1, 4]\n\
1570	add r4, r4, r10\n\
1571	ldr r15, [r2, 8]\n\
1572	sub r5, r5, r15\n\
1573	ldr r11, [r1, 0]\n\
1574	add r4, r4, r11\n\
1575	ldr r16, [r2, 12]\n\
1576	sub r5, r5, r16\n\
1577	@end smallexample\n\
1578	\n\
1579	On targets like ARM/AArch64, the two pairs of consecutive loads should be\n\
1580	merged. Since peephole2 pass can't help in this case unless consecutive\n\
1581	loads are actually next to each other in instruction flow. That's where\n\
1582	this scheduling fusion pass works. This hook calculates priority for each\n\
1583	instruction based on its fustion type, like:\n\
1584	\n\
1585	@smallexample\n\
1586	ldr r10, [r1, 4] ; fusion_pri=99, pri=96\n\
1587	add r4, r4, r10 ; fusion_pri=100, pri=100\n\
1588	ldr r15, [r2, 8] ; fusion_pri=98, pri=92\n\
1589	sub r5, r5, r15 ; fusion_pri=100, pri=100\n\
1590	ldr r11, [r1, 0] ; fusion_pri=99, pri=100\n\
1591	add r4, r4, r11 ; fusion_pri=100, pri=100\n\
1592	ldr r16, [r2, 12] ; fusion_pri=98, pri=88\n\
1593	sub r5, r5, r16 ; fusion_pri=100, pri=100\n\
1594	@end smallexample\n\
1595	\n\
1596	Scheduling fusion pass then sorts all ready to issue instructions according\n\
1597	to the priorities. As a result, instructions of same fusion type will be\n\
1598	pushed together in instruction flow, like:\n\
1599	\n\
1600	@smallexample\n\
1601	ldr r11, [r1, 0]\n\
1602	ldr r10, [r1, 4]\n\
1603	ldr r15, [r2, 8]\n\
1604	ldr r16, [r2, 12]\n\
1605	add r4, r4, r10\n\
1606	sub r5, r5, r15\n\
1607	add r4, r4, r11\n\
1608	sub r5, r5, r16\n\
1609	@end smallexample\n\
1610	\n\
1611	Now peephole2 pass can simply merge the two pairs of loads.\n\
1612	\n\
1613	Since scheduling fusion pass relies on peephole2 to do real fusion\n\
1614	work, it is only enabled by default when peephole2 is in effect.\n\
1615	\n\
1616	This is firstly introduced on ARM/AArch64 targets, please refer to\n\
1617	the hook implementation for how different fusion types are supported.",
1618	void, (rtx_insn *insn, int max_pri, int *fusion_pri, int *pri), NULL)
1619
1620	HOOK_VECTOR_END (sched)
1621
1622	/* Functions relating to OpenMP SIMD and __attribute__((simd)) clones. */
1623	#undef HOOK_PREFIX
1624	#define HOOK_PREFIX "TARGET_SIMD_CLONE_"
1625	HOOK_VECTOR (TARGET_SIMD_CLONE, simd_clone)
1626
1627	DEFHOOK
1628	(compute_vecsize_and_simdlen,
1629	"This hook should set @var{vecsize_mangle}, @var{vecsize_int}, @var{vecsize_float}\n\
1630	fields in @var{simd_clone} structure pointed by @var{clone_info} argument and also\n\
1631	@var{simdlen} field if it was previously 0.\n\
1632	@var{vecsize_mangle} is a marker for the backend only. @var{vecsize_int} and\n\
1633	@var{vecsize_float} should be left zero on targets where the number of lanes is\n\
1634	not determined by the bitsize (in which case @var{simdlen} is always used).\n\
1635	The hook should return 0 if SIMD clones shouldn't be emitted,\n\
1636	or number of @var{vecsize_mangle} variants that should be emitted.",
1637	int, (struct cgraph_node *, struct cgraph_simd_clone *, tree, int, bool), NULL)
1638
1639	DEFHOOK
1640	(adjust,
1641	"This hook should add implicit @code{attribute(target(\"...\"))} attribute\n\
1642	to SIMD clone @var{node} if needed.",
1643	void, (struct cgraph_node *), NULL)
1644
1645	DEFHOOK
1646	(usable,
1647	"This hook should return -1 if SIMD clone @var{node} shouldn't be used\n\
1648	in vectorized loops in current function with @var{vector_mode}, or\n\
1649	non-negative number if it is usable. In that case, the smaller the number\n\
1650	is, the more desirable it is to use it.",
1651	int, (struct cgraph_node *, machine_mode), NULL)
1652
1653	HOOK_VECTOR_END (simd_clone)
1654
1655	/* Functions relating to OpenMP SIMT vectorization transform. */
1656	#undef HOOK_PREFIX
1657	#define HOOK_PREFIX "TARGET_SIMT_"
1658	HOOK_VECTOR (TARGET_SIMT, simt)
1659
1660	DEFHOOK
1661	(vf,
1662	"Return number of threads in SIMT thread group on the target.",
1663	int, (void), NULL)
1664
1665	HOOK_VECTOR_END (simt)
1666
1667	/* Functions relating to OpenMP. */
1668	#undef HOOK_PREFIX
1669	#define HOOK_PREFIX "TARGET_OMP_"
1670	HOOK_VECTOR (TARGET_OMP, omp)
1671
1672	DEFHOOK
1673	(device_kind_arch_isa,
1674	"Return 1 if @var{trait} @var{name} is present in the OpenMP context's\n\
1675	device trait set, return 0 if not present in any OpenMP context in the\n\
1676	whole translation unit, or -1 if not present in the current OpenMP context\n\
1677	but might be present in another OpenMP context in the same TU.",
1678	int, (enum omp_device_kind_arch_isa trait, const char *name), NULL)
1679
1680	HOOK_VECTOR_END (omp)
1681
1682	/* Functions relating to openacc. */
1683	#undef HOOK_PREFIX
1684	#define HOOK_PREFIX "TARGET_GOACC_"
1685	HOOK_VECTOR (TARGET_GOACC, goacc)
1686
1687	DEFHOOK
1688	(validate_dims,
1689	"This hook should check the launch dimensions provided for an OpenACC\n\
1690	compute region, or routine. Defaulted values are represented as -1\n\
1691	and non-constant values as 0. The @var{fn_level} is negative for the\n\
1692	function corresponding to the compute region. For a routine it is the\n\
1693	outermost level at which partitioned execution may be spawned. The hook\n\
1694	should verify non-default values. If DECL is NULL, global defaults\n\
1695	are being validated and unspecified defaults should be filled in.\n\
1696	Diagnostics should be issued as appropriate. Return\n\
1697	true, if changes have been made. You must override this hook to\n\
1698	provide dimensions larger than 1.",
1699	bool, (tree decl, int *dims, int fn_level, unsigned used),
1700	default_goacc_validate_dims)
1701
1702	DEFHOOK
1703	(dim_limit,
1704	"This hook should return the maximum size of a particular dimension,\n\
1705	or zero if unbounded.",
1706	int, (int axis),
1707	default_goacc_dim_limit)
1708
1709	DEFHOOK
1710	(fork_join,
1711	"This hook can be used to convert IFN_GOACC_FORK and IFN_GOACC_JOIN\n\
1712	function calls to target-specific gimple, or indicate whether they\n\
1713	should be retained. It is executed during the oacc_device_lower pass.\n\
1714	It should return true, if the call should be retained. It should\n\
1715	return false, if it is to be deleted (either because target-specific\n\
1716	gimple has been inserted before it, or there is no need for it).\n\
1717	The default hook returns false, if there are no RTL expanders for them.",
1718	bool, (gcall *call, const int *dims, bool is_fork),
1719	default_goacc_fork_join)
1720
1721	DEFHOOK
1722	(reduction,
1723	"This hook is used by the oacc_transform pass to expand calls to the\n\
1724	@var{GOACC_REDUCTION} internal function, into a sequence of gimple\n\
1725	instructions. @var{call} is gimple statement containing the call to\n\
1726	the function. This hook removes statement @var{call} after the\n\
1727	expanded sequence has been inserted. This hook is also responsible\n\
1728	for allocating any storage for reductions when necessary.",
1729	void, (gcall *call),
1730	default_goacc_reduction)
1731
1732	DEFHOOK
1733	(adjust_private_decl,
1734	"This hook, if defined, is used by accelerator target back-ends to adjust\n\
1735	OpenACC variable declarations that should be made private to the given\n\
1736	parallelism level (i.e. @code{GOMP_DIM_GANG}, @code{GOMP_DIM_WORKER} or\n\
1737	@code{GOMP_DIM_VECTOR}). A typical use for this hook is to force variable\n\
1738	declarations at the @code{gang} level to reside in GPU shared memory.\n\
1739	@var{loc} may be used for diagnostic purposes.\n\
1740	\n\
1741	You may also use the @code{TARGET_GOACC_EXPAND_VAR_DECL} hook if the\n\
1742	adjusted variable declaration needs to be expanded to RTL in a non-standard\n\
1743	way.",
1744	tree, (location_t loc, tree var, int level),
1745	NULL)
1746
1747	DEFHOOK
1748	(expand_var_decl,
1749	"This hook, if defined, is used by accelerator target back-ends to expand\n\
1750	specially handled kinds of @code{VAR_DECL} expressions. A particular use is\n\
1751	to place variables with specific attributes inside special accelarator\n\
1752	memories. A return value of @code{NULL} indicates that the target does not\n\
1753	handle this @code{VAR_DECL}, and normal RTL expanding is resumed.\n\
1754	\n\
1755	Only define this hook if your accelerator target needs to expand certain\n\
1756	@code{VAR_DECL} nodes in a way that differs from the default. You can also adjust\n\
1757	private variables at OpenACC device-lowering time using the\n\
1758	@code{TARGET_GOACC_ADJUST_PRIVATE_DECL} target hook.",
1759	rtx, (tree var),
1760	NULL)
1761
1762	DEFHOOK
1763	(create_worker_broadcast_record,
1764	"Create a record used to propagate local-variable state from an active\n\
1765	worker to other workers. A possible implementation might adjust the type\n\
1766	of REC to place the new variable in shared GPU memory.\n\
1767	\n\
1768	Presence of this target hook indicates that middle end neutering/broadcasting\n\
1769	be used.",
1770	tree, (tree rec, bool sender, const char *name, unsigned HOST_WIDE_INT offset),
1771	NULL)
1772
1773	DEFHOOK
1774	(shared_mem_layout,
1775	"Lay out a fixed shared-memory region on the target. The LO and HI\n\
1776	arguments should be set to a range of addresses that can be used for worker\n\
1777	broadcasting. The dimensions, reduction size and gang-private size\n\
1778	arguments are for the current offload region.",
1779	void, (unsigned HOST_WIDE_INT *, unsigned HOST_WIDE_INT *, int[],
1780	unsigned HOST_WIDE_INT[], unsigned HOST_WIDE_INT[]),
1781	NULL)
1782
1783	HOOK_VECTOR_END (goacc)
1784
1785	/* Functions relating to vectorization. */
1786	#undef HOOK_PREFIX
1787	#define HOOK_PREFIX "TARGET_VECTORIZE_"
1788	HOOK_VECTOR (TARGET_VECTORIZE, vectorize)
1789
1790	/* The following member value is a pointer to a function called
1791	by the vectorizer, and return the decl of the target builtin
1792	function. */
1793	DEFHOOK
1794	(builtin_mask_for_load,
1795	"This hook should return the DECL of a function @var{f} that given an\n\
1796	address @var{addr} as an argument returns a mask @var{m} that can be\n\
1797	used to extract from two vectors the relevant data that resides in\n\
1798	@var{addr} in case @var{addr} is not properly aligned.\n\
1799	\n\
1800	The autovectorizer, when vectorizing a load operation from an address\n\
1801	@var{addr} that may be unaligned, will generate two vector loads from\n\
1802	the two aligned addresses around @var{addr}. It then generates a\n\
1803	@code{REALIGN_LOAD} operation to extract the relevant data from the\n\
1804	two loaded vectors. The first two arguments to @code{REALIGN_LOAD},\n\
1805	@var{v1} and @var{v2}, are the two vectors, each of size @var{VS}, and\n\
1806	the third argument, @var{OFF}, defines how the data will be extracted\n\
1807	from these two vectors: if @var{OFF} is 0, then the returned vector is\n\
1808	@var{v2}; otherwise, the returned vector is composed from the last\n\
1809	@var{VS}-@var{OFF} elements of @var{v1} concatenated to the first\n\
1810	@var{OFF} elements of @var{v2}.\n\
1811	\n\
1812	If this hook is defined, the autovectorizer will generate a call\n\
1813	to @var{f} (using the DECL tree that this hook returns) and will\n\
1814	use the return value of @var{f} as the argument @var{OFF} to\n\
1815	@code{REALIGN_LOAD}. Therefore, the mask @var{m} returned by @var{f}\n\
1816	should comply with the semantics expected by @code{REALIGN_LOAD}\n\
1817	described above.\n\
1818	If this hook is not defined, then @var{addr} will be used as\n\
1819	the argument @var{OFF} to @code{REALIGN_LOAD}, in which case the low\n\
1820	log2(@var{VS}) @minus{} 1 bits of @var{addr} will be considered.",
1821	tree, (void), NULL)
1822
1823	/* Returns a built-in function that realizes the vectorized version of
1824	a target-independent function, or NULL_TREE if not available. */
1825	DEFHOOK
1826	(builtin_vectorized_function,
1827	"This hook should return the decl of a function that implements the\n\
1828	vectorized variant of the function with the @code{combined_fn} code\n\
1829	@var{code} or @code{NULL_TREE} if such a function is not available.\n\
1830	The return type of the vectorized function shall be of vector type\n\
1831	@var{vec_type_out} and the argument types should be @var{vec_type_in}.",
1832	tree, (unsigned code, tree vec_type_out, tree vec_type_in),
1833	default_builtin_vectorized_function)
1834
1835	/* Returns a built-in function that realizes the vectorized version of
1836	a target-specific function, or NULL_TREE if not available. */
1837	DEFHOOK
1838	(builtin_md_vectorized_function,
1839	"This hook should return the decl of a function that implements the\n\
1840	vectorized variant of target built-in function @code{fndecl}. The\n\
1841	return type of the vectorized function shall be of vector type\n\
1842	@var{vec_type_out} and the argument types should be @var{vec_type_in}.",
1843	tree, (tree fndecl, tree vec_type_out, tree vec_type_in),
1844	default_builtin_md_vectorized_function)
1845
1846	/* Cost of different vector/scalar statements in vectorization cost
1847	model. In case of misaligned vector loads and stores the cost depends
1848	on the data type and misalignment value. */
1849	DEFHOOK
1850	(builtin_vectorization_cost,
1851	"Returns cost of different scalar or vector statements for vectorization cost model.\n\
1852	For vector memory operations the cost may depend on type (@var{vectype}) and\n\
1853	misalignment value (@var{misalign}).",
1854	int, (enum vect_cost_for_stmt type_of_cost, tree vectype, int misalign),
1855	default_builtin_vectorization_cost)
1856
1857	DEFHOOK
1858	(preferred_vector_alignment,
1859	"This hook returns the preferred alignment in bits for accesses to\n\
1860	vectors of type @var{type} in vectorized code. This might be less than\n\
1861	or greater than the ABI-defined value returned by\n\
1862	@code{TARGET_VECTOR_ALIGNMENT}. It can be equal to the alignment of\n\
1863	a single element, in which case the vectorizer will not try to optimize\n\
1864	for alignment.\n\
1865	\n\
1866	The default hook returns @code{TYPE_ALIGN (@var{type})}, which is\n\
1867	correct for most targets.",
1868	poly_uint64, (const_tree type),
1869	default_preferred_vector_alignment)
1870
1871	/* Returns whether the target has a preference for decomposing divisions using
1872	shifts rather than multiplies. */
1873	DEFHOOK
1874	(preferred_div_as_shifts_over_mult,
1875	"Sometimes it is possible to implement a vector division using a sequence\n\
1876	of two addition-shift pairs, giving four instructions in total.\n\
1877	Return true if taking this approach for @var{vectype} is likely\n\
1878	to be better than using a sequence involving highpart multiplication.\n\
1879	Default is false if @code{can_mult_highpart_p}, otherwise true.",
1880	bool, (const_tree type),
1881	default_preferred_div_as_shifts_over_mult)
1882
1883	/* Return true if vector alignment is reachable (by peeling N
1884	iterations) for the given scalar type. */
1885	DEFHOOK
1886	(vector_alignment_reachable,
1887	"Return true if vector alignment is reachable (by peeling N iterations)\n\
1888	for the given scalar type @var{type}. @var{is_packed} is false if the scalar\n\
1889	access using @var{type} is known to be naturally aligned.",
1890	bool, (const_tree type, bool is_packed),
1891	default_builtin_vector_alignment_reachable)
1892
1893	DEFHOOK
1894	(vec_perm_const,
1895	"This hook is used to test whether the target can permute up to two\n\
1896	vectors of mode @var{op_mode} using the permutation vector @code{sel},\n\
1897	producing a vector of mode @var{mode}. The hook is also used to emit such\n\
1898	a permutation.\n\
1899	\n\
1900	When the hook is being used to test whether the target supports a permutation,\n\
1901	@var{in0}, @var{in1}, and @var{out} are all null. When the hook is being used\n\
1902	to emit a permutation, @var{in0} and @var{in1} are the source vectors of mode\n\
1903	@var{op_mode} and @var{out} is the destination vector of mode @var{mode}.\n\
1904	@var{in1} is the same as @var{in0} if @var{sel} describes a permutation on one\n\
1905	vector instead of two.\n\
1906	\n\
1907	Return true if the operation is possible, emitting instructions for it\n\
1908	if rtxes are provided.\n\
1909	\n\
1910	@cindex @code{vec_perm@var{m}} instruction pattern\n\
1911	If the hook returns false for a mode with multibyte elements, GCC will\n\
1912	try the equivalent byte operation. If that also fails, it will try forcing\n\
1913	the selector into a register and using the @var{vec_perm@var{mode}}\n\
1914	instruction pattern. There is no need for the hook to handle these two\n\
1915	implementation approaches itself.",
1916	bool, (machine_mode mode, machine_mode op_mode, rtx output, rtx in0, rtx in1,
1917	const vec_perm_indices &sel),
1918	NULL)
1919
1920	/* Return true if the target supports misaligned store/load of a
1921	specific factor denoted in the third parameter. The second to the last
1922	parameter is true if the access is defined in a packed struct and
1923	the last parameter is true if the access is a gather/scatter. */
1924	DEFHOOK
1925	(support_vector_misalignment,
1926	"This hook should return true if the target supports misaligned vector\n\
1927	store/load of a specific factor denoted in the @var{misalignment}\n\
1928	parameter. The vector store/load should be of machine mode @var{mode}.\n\
1929	The @var{is_packed} parameter is true if the original memory access is\n\
1930	not naturally aligned. @var{is_gather_scatter} is true if the\n\
1931	load/store is a gather or scatter. In that case misalignment\n\
1932	denotes the misalignment of @var{mode}'s element mode.",
1933	bool,
1934	(machine_mode mode, int misalignment, bool is_packed,
1935	bool is_gather_scatter),
1936	default_builtin_support_vector_misalignment)
1937
1938	/* Returns the preferred mode for SIMD operations for the specified
1939	scalar mode. */
1940	DEFHOOK
1941	(preferred_simd_mode,
1942	"This hook should return the preferred mode for vectorizing scalar\n\
1943	mode @var{mode}. The default is\n\
1944	equal to @code{word_mode}, because the vectorizer can do some\n\
1945	transformations even in absence of specialized @acronym{SIMD} hardware.",
1946	machine_mode,
1947	(scalar_mode mode),
1948	default_preferred_simd_mode)
1949
1950	/* Returns the preferred mode for splitting SIMD reductions to. */
1951	DEFHOOK
1952	(split_reduction,
1953	"This hook should return the preferred mode to split the final reduction\n\
1954	step on @var{mode} to. The reduction is then carried out reducing upper\n\
1955	against lower halves of vectors recursively until the specified mode is\n\
1956	reached. The default is @var{mode} which means no splitting.",
1957	machine_mode,
1958	(machine_mode),
1959	default_split_reduction)
1960
1961	/* Returns a mask of vector sizes to iterate over when auto-vectorizing
1962	after processing the preferred one derived from preferred_simd_mode. */
1963	DEFHOOK
1964	(autovectorize_vector_modes,
1965	"If using the mode returned by @code{TARGET_VECTORIZE_PREFERRED_SIMD_MODE}\n\
1966	is not the only approach worth considering, this hook should add one mode to\n\
1967	@var{modes} for each useful alternative approach. These modes are then\n\
1968	passed to @code{TARGET_VECTORIZE_RELATED_MODE} to obtain the vector mode\n\
1969	for a given element mode.\n\
1970	\n\
1971	The modes returned in @var{modes} should use the smallest element mode\n\
1972	possible for the vectorization approach that they represent, preferring\n\
1973	integer modes over floating-poing modes in the event of a tie. The first\n\
1974	mode should be the @code{TARGET_VECTORIZE_PREFERRED_SIMD_MODE} for its\n\
1975	element mode.\n\
1976	\n\
1977	If @var{all} is true, add suitable vector modes even when they are generally\n\
1978	not expected to be worthwhile.\n\
1979	\n\
1980	The hook returns a bitmask of flags that control how the modes in\n\
1981	@var{modes} are used. The flags are:\n\
1982	@table @code\n\
1983	@item VECT_COMPARE_COSTS\n\
1984	Tells the loop vectorizer to try all the provided modes and pick the one\n\
1985	with the lowest cost. By default the vectorizer will choose the first\n\
1986	mode that works.\n\
1987	@end table\n\
1988	\n\
1989	The hook does not need to do anything if the vector returned by\n\
1990	@code{TARGET_VECTORIZE_PREFERRED_SIMD_MODE} is the only one relevant\n\
1991	for autovectorization. The default implementation adds no modes and\n\
1992	returns 0.",
1993	unsigned int,
1994	(vector_modes *modes, bool all),
1995	default_autovectorize_vector_modes)
1996
1997	DEFHOOK
1998	(related_mode,
1999	"If a piece of code is using vector mode @var{vector_mode} and also wants\n\
2000	to operate on elements of mode @var{element_mode}, return the vector mode\n\
2001	it should use for those elements. If @var{nunits} is nonzero, ensure that\n\
2002	the mode has exactly @var{nunits} elements, otherwise pick whichever vector\n\
2003	size pairs the most naturally with @var{vector_mode}. Return an empty\n\
2004	@code{opt_machine_mode} if there is no supported vector mode with the\n\
2005	required properties.\n\
2006	\n\
2007	There is no prescribed way of handling the case in which @var{nunits}\n\
2008	is zero. One common choice is to pick a vector mode with the same size\n\
2009	as @var{vector_mode}; this is the natural choice if the target has a\n\
2010	fixed vector size. Another option is to choose a vector mode with the\n\
2011	same number of elements as @var{vector_mode}; this is the natural choice\n\
2012	if the target has a fixed number of elements. Alternatively, the hook\n\
2013	might choose a middle ground, such as trying to keep the number of\n\
2014	elements as similar as possible while applying maximum and minimum\n\
2015	vector sizes.\n\
2016	\n\
2017	The default implementation uses @code{mode_for_vector} to find the\n\
2018	requested mode, returning a mode with the same size as @var{vector_mode}\n\
2019	when @var{nunits} is zero. This is the correct behavior for most targets.",
2020	opt_machine_mode,
2021	(machine_mode vector_mode, scalar_mode element_mode, poly_uint64 nunits),
2022	default_vectorize_related_mode)
2023
2024	/* Function to get a target mode for a vector mask. */
2025	DEFHOOK
2026	(get_mask_mode,
2027	"Return the mode to use for a vector mask that holds one boolean\n\
2028	result for each element of vector mode @var{mode}. The returned mask mode\n\
2029	can be a vector of integers (class @code{MODE_VECTOR_INT}), a vector of\n\
2030	booleans (class @code{MODE_VECTOR_BOOL}) or a scalar integer (class\n\
2031	@code{MODE_INT}). Return an empty @code{opt_machine_mode} if no such\n\
2032	mask mode exists.\n\
2033	\n\
2034	The default implementation returns a @code{MODE_VECTOR_INT} with the\n\
2035	same size and number of elements as @var{mode}, if such a mode exists.",
2036	opt_machine_mode,
2037	(machine_mode mode),
2038	default_get_mask_mode)
2039
2040	/* Function to say whether a conditional operation is expensive when
2041	compared to non-masked operations. */
2042	DEFHOOK
2043	(conditional_operation_is_expensive,
2044	"This hook returns true if masked operation @var{ifn} (really of\n\
2045	type @code{internal_fn}) should be considered more expensive to use than\n\
2046	implementing the same operation without masking. GCC can then try to use\n\
2047	unconditional operations instead with extra selects.",
2048	bool,
2049	(unsigned ifn),
2050	default_conditional_operation_is_expensive)
2051
2052	/* Function to say whether a masked operation is expensive when the
2053	mask is all zeros. */
2054	DEFHOOK
2055	(empty_mask_is_expensive,
2056	"This hook returns true if masked internal function @var{ifn} (really of\n\
2057	type @code{internal_fn}) should be considered expensive when the mask is\n\
2058	all zeros. GCC can then try to branch around the instruction instead.",
2059	bool,
2060	(unsigned ifn),
2061	default_empty_mask_is_expensive)
2062
2063	/* Prefer gather/scatter loads/stores to e.g. elementwise accesses if\n\
2064	we cannot use a contiguous access. */
2065	DEFHOOK
2066	(prefer_gather_scatter,
2067	"This hook returns TRUE if gather loads or scatter stores are cheaper on\n\
2068	this target than a sequence of elementwise loads or stores. The @var{mode}\n\
2069	and @var{scale} correspond to the @code{gather_load} and\n\
2070	@code{scatter_store} instruction patterns. The @var{group_size} is the\n\
2071	number of scalar elements in each scalar loop iteration that are to be\n\
2072	combined into the vector.",
2073	bool,
2074	(machine_mode mode, int scale, unsigned int group_size),
2075	hook_bool_mode_int_unsigned_false)
2076
2077	/* Target builtin that implements vector gather operation. */
2078	DEFHOOK
2079	(builtin_gather,
2080	"Target builtin that implements vector gather operation. @var{mem_vectype}\n\
2081	is the vector type of the load and @var{index_type} is scalar type of\n\
2082	the index, scaled by @var{scale}.\n\
2083	The default is @code{NULL_TREE} which means to not vectorize gather\n\
2084	loads.",
2085	tree,
2086	(const_tree mem_vectype, const_tree index_type, int scale),
2087	NULL)
2088
2089	/* Target builtin that implements vector scatter operation. */
2090	DEFHOOK
2091	(builtin_scatter,
2092	"Target builtin that implements vector scatter operation. @var{vectype}\n\
2093	is the vector type of the store and @var{index_type} is scalar type of\n\
2094	the index, scaled by @var{scale}.\n\
2095	The default is @code{NULL_TREE} which means to not vectorize scatter\n\
2096	stores.",
2097	tree,
2098	(const_tree vectype, const_tree index_type, int scale),
2099	NULL)
2100
2101	/* Target function to initialize the cost model for a loop or block. */
2102	DEFHOOK
2103	(create_costs,
2104	"This hook should initialize target-specific data structures in preparation\n\
2105	for modeling the costs of vectorizing a loop or basic block. The default\n\
2106	allocates three unsigned integers for accumulating costs for the prologue,\n\
2107	body, and epilogue of the loop or basic block. If @var{loop_info} is\n\
2108	non-NULL, it identifies the loop being vectorized; otherwise a single block\n\
2109	is being vectorized. If @var{costing_for_scalar} is true, it indicates the\n\
2110	current cost model is for the scalar version of a loop or block; otherwise\n\
2111	it is for the vector version.",
2112	class vector_costs *,
2113	(vec_info *vinfo, bool costing_for_scalar),
2114	default_vectorize_create_costs)
2115
2116	HOOK_VECTOR_END (vectorize)
2117
2118	#undef HOOK_PREFIX
2119	#define HOOK_PREFIX "TARGET_"
2120
2121	DEFHOOK
2122	(preferred_else_value,
2123	"This hook returns the target's preferred final argument for a call\n\
2124	to conditional internal function @var{ifn} (really of type\n\
2125	@code{internal_fn}). @var{type} specifies the return type of the\n\
2126	function and @var{ops} are the operands to the conditional operation,\n\
2127	of which there are @var{nops}.\n\
2128	\n\
2129	For example, if @var{ifn} is @code{IFN_COND_ADD}, the hook returns\n\
2130	a value of type @var{type} that should be used when @samp{@var{ops}[0]}\n\
2131	and @samp{@var{ops}[1]} are conditionally added together.\n\
2132	\n\
2133	This hook is only relevant if the target supports conditional patterns\n\
2134	like @code{cond_add@var{m}}. The default implementation returns a zero\n\
2135	constant of type @var{type}.",
2136	tree,
2137	(unsigned ifn, tree type, unsigned nops, tree *ops),
2138	default_preferred_else_value)
2139
2140	DEFHOOK
2141	(instruction_selection,
2142	"This hook allows a target to perform custom instruction selection for an\n\
2143	instruction or sequence of instructions before expand to allow expansion to\n\
2144	generate more efficient code.\n\
2145	\n\
2146	@var{fun} is the current function being considered and @var{gsi} is the\n\
2147	iterator pointing to the current instruction being optimized. The default\n\
2148	implementation does not do any rewriting and returns false. The result of\n\
2149	the function should be whether any changes were made to the CFG or not. If a\n\
2150	change was made then the @var{gsi} should be left at the same position as at\n\
2151	the function start. The caller is allowed to change the CFG at any point\n\
2152	before the current statement @var{gsi} is pointing to but not afterwards.",
2153	bool,
2154	(function *fun, gimple_stmt_iterator *gsi),
2155	default_instruction_selection)
2156
2157	DEFHOOK
2158	(record_offload_symbol,
2159	"Used when offloaded functions are seen in the compilation unit and no named\n\
2160	sections are available. It is called once for each symbol that must be\n\
2161	recorded in the offload function and variable table.",
2162	void, (tree),
2163	hook_void_tree)
2164
2165	DEFHOOKPOD
2166	(absolute_biggest_alignment,
2167	"If defined, this target hook specifies the absolute biggest alignment\n\
2168	that a type or variable can have on this machine, otherwise,\n\
2169	@code{BIGGEST_ALIGNMENT} is used.",
2170	HOST_WIDE_INT, BIGGEST_ALIGNMENT)
2171
2172	/* Allow target specific overriding of option settings after options have
2173	been changed by an attribute or pragma or when it is reset at the
2174	end of the code affected by an attribute or pragma. */
2175	DEFHOOK
2176	(override_options_after_change,
2177	"This target function is similar to the hook @code{TARGET_OPTION_OVERRIDE}\n\
2178	but is called when the optimize level is changed via an attribute or\n\
2179	pragma or when it is reset at the end of the code affected by the\n\
2180	attribute or pragma. It is not called at the beginning of compilation\n\
2181	when @code{TARGET_OPTION_OVERRIDE} is called so if you want to perform these\n\
2182	actions then, you should have @code{TARGET_OPTION_OVERRIDE} call\n\
2183	@code{TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE}.",
2184	void, (void),
2185	hook_void_void)
2186
2187	DEFHOOK
2188	(offload_options,
2189	"Used when writing out the list of options into an LTO file. It should\n\
2190	translate any relevant target-specific options (such as the ABI in use)\n\
2191	into one of the @option{-foffload} options that exist as a common interface\n\
2192	to express such options. It should return a string containing these options,\n\
2193	separated by spaces, which the caller will free.\n",
2194	char *, (void), hook_charptr_void_null)
2195
2196	DEFHOOK_UNDOC
2197	(eh_return_filter_mode,
2198	"Return machine mode for filter value.",
2199	scalar_int_mode, (void),
2200	default_eh_return_filter_mode)
2201
2202	/* Return machine mode for libgcc expanded cmp instructions. */
2203	DEFHOOK
2204	(libgcc_cmp_return_mode,
2205	"This target hook should return the mode to be used for the return value\n\
2206	of compare instructions expanded to libgcc calls. If not defined\n\
2207	@code{word_mode} is returned which is the right choice for a majority of\n\
2208	targets.",
2209	scalar_int_mode, (void),
2210	default_libgcc_cmp_return_mode)
2211
2212	/* Return machine mode for libgcc expanded shift instructions. */
2213	DEFHOOK
2214	(libgcc_shift_count_mode,
2215	"This target hook should return the mode to be used for the shift count operand\n\
2216	of shift instructions expanded to libgcc calls. If not defined\n\
2217	@code{word_mode} is returned which is the right choice for a majority of\n\
2218	targets.",
2219	scalar_int_mode, (void),
2220	default_libgcc_shift_count_mode)
2221
2222	/* Return machine mode to be used for _Unwind_Word type. */
2223	DEFHOOK
2224	(unwind_word_mode,
2225	"Return machine mode to be used for @code{_Unwind_Word} type.\n\
2226	The default is to use @code{word_mode}.",
2227	scalar_int_mode, (void),
2228	default_unwind_word_mode)
2229
2230	/* Given two decls, merge their attributes and return the result. */
2231	DEFHOOK
2232	(merge_decl_attributes,
2233	"Define this target hook if the merging of decl attributes needs special\n\
2234	handling. If defined, the result is a list of the combined\n\
2235	@code{DECL_ATTRIBUTES} of @var{olddecl} and @var{newdecl}.\n\
2236	@var{newdecl} is a duplicate declaration of @var{olddecl}. Examples of\n\
2237	when this is needed are when one attribute overrides another, or when an\n\
2238	attribute is nullified by a subsequent definition. This function may\n\
2239	call @code{merge_attributes} to handle machine-independent merging.\n\
2240	\n\
2241	@findex TARGET_DLLIMPORT_DECL_ATTRIBUTES\n\
2242	If the only target-specific handling you require is @samp{dllimport}\n\
2243	for Microsoft Windows targets, you should define the macro\n\
2244	@code{TARGET_DLLIMPORT_DECL_ATTRIBUTES} to @code{1}. The compiler\n\
2245	will then define a function called\n\
2246	@code{merge_dllimport_decl_attributes} which can then be defined as\n\
2247	the expansion of @code{TARGET_MERGE_DECL_ATTRIBUTES}. You can also\n\
2248	add @code{handle_dll_attribute} in the attribute table for your port\n\
2249	to perform initial processing of the @samp{dllimport} and\n\
2250	@samp{dllexport} attributes. This is done in @file{i386/cygwin.h} and\n\
2251	@file{i386/i386.cc}, for example.",
2252	tree, (tree olddecl, tree newdecl),
2253	merge_decl_attributes)
2254
2255	/* Given two types, merge their attributes and return the result. */
2256	DEFHOOK
2257	(merge_type_attributes,
2258	"Define this target hook if the merging of type attributes needs special\n\
2259	handling. If defined, the result is a list of the combined\n\
2260	@code{TYPE_ATTRIBUTES} of @var{type1} and @var{type2}. It is assumed\n\
2261	that @code{comptypes} has already been called and returned 1. This\n\
2262	function may call @code{merge_attributes} to handle machine-independent\n\
2263	merging.",
2264	tree, (tree type1, tree type2),
2265	merge_type_attributes)
2266
2267	/* Table of machine attributes and functions to handle them.
2268	Ignored if empty. */
2269	DEFHOOKPOD
2270	(attribute_table,
2271	"If defined, this target hook provides an array of\n\
2272	@samp{scoped_attribute_spec}s (defined in @file{attribs.h}) that specify the\n\
2273	machine-specific attributes for this target. The information includes some\n\
2274	of the restrictions on the entities to which these attributes are applied\n\
2275	and the arguments that the attributes take.\n\
2276	\n\
2277	In C and C++, these attributes are associated with two syntaxes:\n\
2278	the traditional GNU @code{__attribute__} syntax and the standard\n\
2279	@samp{[[]]} syntax. Attributes that support the GNU syntax must be\n\
2280	placed in the @code{gnu} namespace. Such attributes can then also be\n\
2281	written @samp{[[gnu::@dots{}]]}. Attributes that use only the standard\n\
2282	syntax should be placed in whichever namespace the attribute specification\n\
2283	requires. For example, a target might choose to support vendor-specific\n\
2284	@samp{[[]]} attributes that the vendor places in their own namespace.\n\
2285	\n\
2286	Targets that only define attributes in the @code{gnu} namespace\n\
2287	can uase the following shorthand to define the table:\n\
2288	\n\
2289	@smallexample\n\
2290	TARGET_GNU_ATTRIBUTES (@var{cpu_attribute_table}, @{\n\
2291	@{ \"@var{attribute1}\", @dots{} @},\n\
2292	@{ \"@var{attribute2}\", @dots{} @},\n\
2293	@dots{},\n\
2294	@{ \"@var{attributen}\", @dots{} @},\n\
2295	@});\n\
2296	@end smallexample",
2297	array_slice<const struct scoped_attribute_specs *const>,)
2298
2299	/* Return true iff attribute NAME expects a plain identifier as its first
2300	argument. */
2301	DEFHOOK
2302	(attribute_takes_identifier_p,
2303	"If defined, this target hook is a function which returns true if the\n\
2304	machine-specific attribute named @var{name} expects an identifier\n\
2305	given as its first argument to be passed on as a plain identifier, not\n\
2306	subjected to name lookup. If this is not defined, the default is\n\
2307	false for all machine-specific attributes.",
2308	bool, (const_tree name),
2309	hook_bool_const_tree_false)
2310
2311	/* Return zero if the attributes on TYPE1 and TYPE2 are incompatible,
2312	one if they are compatible and two if they are nearly compatible
2313	(which causes a warning to be generated). */
2314	DEFHOOK
2315	(comp_type_attributes,
2316	"If defined, this target hook is a function which returns zero if the attributes on\n\
2317	@var{type1} and @var{type2} are incompatible, one if they are compatible,\n\
2318	and two if they are nearly compatible (which causes a warning to be\n\
2319	generated). If this is not defined, machine-specific attributes are\n\
2320	supposed always to be compatible.",
2321	int, (const_tree type1, const_tree type2),
2322	hook_int_const_tree_const_tree_1)
2323
2324	/* Assign default attributes to the newly defined TYPE. */
2325	DEFHOOK
2326	(set_default_type_attributes,
2327	"If defined, this target hook is a function which assigns default attributes to\n\
2328	the newly defined @var{type}.",
2329	void, (tree type),
2330	hook_void_tree)
2331
2332	/* Insert attributes on the newly created DECL. */
2333	DEFHOOK
2334	(insert_attributes,
2335	"Define this target hook if you want to be able to add attributes to a decl\n\
2336	when it is being created. This is normally useful for back ends which\n\
2337	wish to implement a pragma by using the attributes which correspond to\n\
2338	the pragma's effect. The @var{node} argument is the decl which is being\n\
2339	created. The @var{attr_ptr} argument is a pointer to the attribute list\n\
2340	for this decl. The list itself should not be modified, since it may be\n\
2341	shared with other decls, but attributes may be chained on the head of\n\
2342	the list and @code{*@var{attr_ptr}} modified to point to the new\n\
2343	attributes, or a copy of the list may be made if further changes are\n\
2344	needed.",
2345	void, (tree node, tree *attr_ptr),
2346	hook_void_tree_treeptr)
2347
2348	/* Perform additional target-specific processing of generic attributes. */
2349	DEFHOOK
2350	(handle_generic_attribute,
2351	"Define this target hook if you want to be able to perform additional\n\
2352	target-specific processing of an attribute which is handled generically\n\
2353	by a front end. The arguments are the same as those which are passed to\n\
2354	attribute handlers. So far this only affects the @var{noinit} and\n\
2355	@var{section} attribute.",
2356	tree, (tree *node, tree name, tree args, int flags, bool *no_add_attrs),
2357	hook_tree_treeptr_tree_tree_int_boolptr_null)
2358
2359	/* Return true if FNDECL (which has at least one machine attribute)
2360	can be inlined despite its machine attributes, false otherwise. */
2361	DEFHOOK
2362	(function_attribute_inlinable_p,
2363	"@cindex inlining\n\
2364	This target hook returns @code{false} if the target-specific attributes on\n\
2365	@var{fndecl} always block it getting inlined, @code{true} otherwise. By\n\
2366	default, if a function has a target specific attribute attached to it, it\n\
2367	will not be inlined.",
2368	bool, (const_tree fndecl),
2369	hook_bool_const_tree_false)
2370
2371	/* Return true if bitfields in RECORD_TYPE should follow the
2372	Microsoft Visual C++ bitfield layout rules. */
2373	DEFHOOK
2374	(ms_bitfield_layout_p,
2375	"This target hook returns @code{true} if bit-fields in the given\n\
2376	@var{record_type} are to be laid out following the rules of Microsoft\n\
2377	Visual C/C++, namely: (i) a bit-field won't share the same storage\n\
2378	unit with the previous bit-field if their underlying types have\n\
2379	different sizes, and the bit-field will be aligned to the highest\n\
2380	alignment of the underlying types of itself and of the previous\n\
2381	bit-field; (ii) a zero-sized bit-field will affect the alignment of\n\
2382	the whole enclosing structure, even if it is unnamed; except that\n\
2383	(iii) a zero-sized bit-field will be disregarded unless it follows\n\
2384	another bit-field of nonzero size. If this hook returns @code{true},\n\
2385	other macros that control bit-field layout are ignored.\n\
2386	\n\
2387	When a bit-field is inserted into a packed record, the whole size\n\
2388	of the underlying type is used by one or more same-size adjacent\n\
2389	bit-fields (that is, if its long:3, 32 bits is used in the record,\n\
2390	and any additional adjacent long bit-fields are packed into the same\n\
2391	chunk of 32 bits. However, if the size changes, a new field of that\n\
2392	size is allocated). In an unpacked record, this is the same as using\n\
2393	alignment, but not equivalent when packing.\n\
2394	\n\
2395	If both MS bit-fields and @samp{__attribute__((packed))} are used,\n\
2396	the latter will take precedence. If @samp{__attribute__((packed))} is\n\
2397	used on a single field when MS bit-fields are in use, it will take\n\
2398	precedence for that field, but the alignment of the rest of the structure\n\
2399	may affect its placement.",
2400	bool, (const_tree record_type),
2401	hook_bool_const_tree_false)
2402
2403	/* For now this is only an interface to WORDS_BIG_ENDIAN for
2404	target-independent code like the front ends, need performance testing
2405	before switching completely to the target hook. */
2406	DEFHOOK_UNDOC
2407	(words_big_endian,
2408	"",
2409	bool, (void),
2410	targhook_words_big_endian)
2411
2412	/* Likewise for FLOAT_WORDS_BIG_ENDIAN. */
2413	DEFHOOK_UNDOC
2414	(float_words_big_endian,
2415	"",
2416	bool, (void),
2417	targhook_float_words_big_endian)
2418
2419	DEFHOOK
2420	(float_exceptions_rounding_supported_p,
2421	"Returns true if the target supports IEEE 754 floating-point exceptions\n\
2422	and rounding modes, false otherwise. This is intended to relate to the\n\
2423	@code{float} and @code{double} types, but not necessarily @code{long double}.\n\
2424	By default, returns true if the @code{adddf3} instruction pattern is\n\
2425	available and false otherwise, on the assumption that hardware floating\n\
2426	point supports exceptions and rounding modes but software floating point\n\
2427	does not.",
2428	bool, (void),
2429	default_float_exceptions_rounding_supported_p)
2430
2431	/* True if the target supports decimal floating point. */
2432	DEFHOOK
2433	(decimal_float_supported_p,
2434	"Returns true if the target supports decimal floating point.",
2435	bool, (void),
2436	default_decimal_float_supported_p)
2437
2438	/* True if the target supports fixed-point. */
2439	DEFHOOK
2440	(fixed_point_supported_p,
2441	"Returns true if the target supports fixed-point arithmetic.",
2442	bool, (void),
2443	default_fixed_point_supported_p)
2444
2445	/* Return true if anonymous bitfields affect structure alignment. */
2446	DEFHOOK
2447	(align_anon_bitfield,
2448	"When @code{PCC_BITFIELD_TYPE_MATTERS} is true this hook will determine\n\
2449	whether unnamed bitfields affect the alignment of the containing\n\
2450	structure. The hook should return true if the structure should inherit\n\
2451	the alignment requirements of an unnamed bitfield's type.",
2452	bool, (void),
2453	hook_bool_void_false)
2454
2455	/* Return true if volatile bitfields should use the narrowest type possible.
2456	Return false if they should use the container type. */
2457	DEFHOOK
2458	(narrow_volatile_bitfield,
2459	"This target hook should return @code{true} if accesses to volatile bitfields\n\
2460	should use the narrowest mode possible. It should return @code{false} if\n\
2461	these accesses should use the bitfield container type.\n\
2462	\n\
2463	The default is @code{false}.",
2464	bool, (void),
2465	hook_bool_void_false)
2466
2467	/* Set up target-specific built-in functions. */
2468	DEFHOOK
2469	(init_builtins,
2470	"Define this hook if you have any machine-specific built-in functions\n\
2471	that need to be defined. It should be a function that performs the\n\
2472	necessary setup.\n\
2473	\n\
2474	Machine specific built-in functions can be useful to expand special machine\n\
2475	instructions that would otherwise not normally be generated because\n\
2476	they have no equivalent in the source language (for example, SIMD vector\n\
2477	instructions or prefetch instructions).\n\
2478	\n\
2479	To create a built-in function, call the function\n\
2480	@code{lang_hooks.builtin_function}\n\
2481	which is defined by the language front end. You can use any type nodes set\n\
2482	up by @code{build_common_tree_nodes};\n\
2483	only language front ends that use those two functions will call\n\
2484	@samp{TARGET_INIT_BUILTINS}.",
2485	void, (void),
2486	hook_void_void)
2487
2488	/* Initialize (if INITIALIZE_P is true) and return the target-specific
2489	built-in function decl for CODE.
2490	Return NULL if that is not possible. Return error_mark_node if CODE
2491	is outside of the range of valid target builtin function codes. */
2492	DEFHOOK
2493	(builtin_decl,
2494	"Define this hook if you have any machine-specific built-in functions\n\
2495	that need to be defined. It should be a function that returns the\n\
2496	builtin function declaration for the builtin function code @var{code}.\n\
2497	If there is no such builtin and it cannot be initialized at this time\n\
2498	if @var{initialize_p} is true the function should return @code{NULL_TREE}.\n\
2499	If @var{code} is out of range the function should return\n\
2500	@code{error_mark_node}.",
2501	tree, (unsigned code, bool initialize_p), NULL)
2502
2503	/* Expand a target-specific builtin. */
2504	DEFHOOK
2505	(expand_builtin,
2506	"\n\
2507	Expand a call to a machine specific built-in function that was set up by\n\
2508	@samp{TARGET_INIT_BUILTINS}. @var{exp} is the expression for the\n\
2509	function call; the result should go to @var{target} if that is\n\
2510	convenient, and have mode @var{mode} if that is convenient.\n\
2511	@var{subtarget} may be used as the target for computing one of\n\
2512	@var{exp}'s operands. @var{ignore} is nonzero if the value is to be\n\
2513	ignored. This function should return the result of the call to the\n\
2514	built-in function.",
2515	rtx,
2516	(tree exp, rtx target, rtx subtarget, machine_mode mode, int ignore),
2517	default_expand_builtin)
2518
2519	/* Select a replacement for a target-specific builtin. This is done
2520	*before* regular type checking, and so allows the target to
2521	implement a crude form of function overloading. The result is a
2522	complete expression that implements the operation. PARAMS really
2523	has type VEC(tree,gc)*, but we don't want to include tree.h here. */
2524	DEFHOOK
2525	(resolve_overloaded_builtin,
2526	"Select a replacement for a machine specific built-in function that\n\
2527	was set up by @samp{TARGET_INIT_BUILTINS}. This is done\n\
2528	@emph{before} regular type checking, and so allows the target to\n\
2529	implement a crude form of function overloading. @var{fndecl} is the\n\
2530	declaration of the built-in function. @var{arglist} is the list of\n\
2531	arguments passed to the built-in function. The result is a\n\
2532	complete expression that implements the operation, usually\n\
2533	another @code{CALL_EXPR}.\n\
2534	@var{arglist} really has type @samp{VEC(tree,gc)*}\n\
2535	@var{complain} is a boolean indicating whether invalid operations\n\
2536	should emit errors. This is set to @code{false} when the C++ templating\n\
2537	context expects that errors should not be emitted (i.e. SFINAE).",
2538	tree, (location_t loc, tree fndecl, void *arglist, bool complain), NULL)
2539
2540	DEFHOOK
2541	(check_builtin_call,
2542	"Perform semantic checking on a call to a machine-specific built-in\n\
2543	function after its arguments have been constrained to the function\n\
2544	signature. Return true if the call is valid, otherwise report an error\n\
2545	and return false.\n\
2546	\n\
2547	This hook is called after @code{TARGET_RESOLVE_OVERLOADED_BUILTIN}.\n\
2548	The call was originally to built-in function @var{orig_fndecl},\n\
2549	but after the optional @code{TARGET_RESOLVE_OVERLOADED_BUILTIN}\n\
2550	step is now to built-in function @var{fndecl}. @var{loc} is the\n\
2551	location of the call and @var{args} is an array of function arguments,\n\
2552	of which there are @var{nargs}. @var{arg_loc} specifies the location\n\
2553	of each argument. @var{complain} is a boolean indicating whether invalid\n\
2554	arguments should emitm errors. This is set to @code{false} when the C++\n\
2555	templating context expects that errors should not be emitted (i.e. SFINAE).",
2556	bool, (location_t loc, vec<location_t> arg_loc, tree fndecl,
2557	tree orig_fndecl, unsigned int nargs, tree *args, bool complain),
2558	NULL)
2559
2560	/* Fold a target-specific builtin to a tree valid for both GIMPLE
2561	and GENERIC. */
2562	DEFHOOK
2563	(fold_builtin,
2564	"Fold a call to a machine specific built-in function that was set up by\n\
2565	@samp{TARGET_INIT_BUILTINS}. @var{fndecl} is the declaration of the\n\
2566	built-in function. @var{n_args} is the number of arguments passed to\n\
2567	the function; the arguments themselves are pointed to by @var{argp}.\n\
2568	The result is another tree, valid for both GIMPLE and GENERIC,\n\
2569	containing a simplified expression for the call's result. If\n\
2570	@var{ignore} is true the value will be ignored.",
2571	tree, (tree fndecl, int n_args, tree *argp, bool ignore),
2572	hook_tree_tree_int_treep_bool_null)
2573
2574	/* Fold a target-specific builtin to a valid GIMPLE tree. */
2575	DEFHOOK
2576	(gimple_fold_builtin,
2577	"Fold a call to a machine specific built-in function that was set up\n\
2578	by @samp{TARGET_INIT_BUILTINS}. @var{gsi} points to the gimple\n\
2579	statement holding the function call. Returns true if any change\n\
2580	was made to the GIMPLE stream.",
2581	bool, (gimple_stmt_iterator *gsi),
2582	hook_bool_gsiptr_false)
2583
2584	/* Target hook is used to compare the target attributes in two functions to
2585	determine which function's features get higher priority. This is used
2586	during function multi-versioning to figure out the order in which two
2587	versions must be dispatched. A function version with a higher priority
2588	is checked for dispatching earlier. DECL1 and DECL2 are
2589	the two function decls that will be compared. It returns positive value
2590	if DECL1 is higher priority, negative value if DECL2 is higher priority
2591	and 0 if they are the same. */
2592	DEFHOOK
2593	(compare_version_priority,
2594	"This hook is used to compare the target attributes in two functions to\n\
2595	determine which function's features get higher priority. This is used\n\
2596	during function multi-versioning to figure out the order in which two\n\
2597	versions must be dispatched. A function version with a higher priority\n\
2598	is checked for dispatching earlier. @var{decl1} and @var{decl2} are\n\
2599	the two function decls that will be compared.",
2600	int, (tree decl1, tree decl2), NULL)
2601
2602	/* Target hook is used to generate the dispatcher logic to invoke the right
2603	function version at run-time for a given set of function versions.
2604	ARG points to the callgraph node of the dispatcher function whose body
2605	must be generated. */
2606	DEFHOOK
2607	(generate_version_dispatcher_body,
2608	"This hook is used to generate the dispatcher logic to invoke the right\n\
2609	function version at run-time for a given set of function versions.\n\
2610	@var{arg} points to the callgraph node of the dispatcher function whose\n\
2611	body must be generated.",
2612	tree, (void *arg), NULL)
2613
2614	/* Target hook is used to get the dispatcher function for a set of function
2615	versions. The dispatcher function is called to invoke the right function
2616	version at run-time. DECL is one version from a set of semantically
2617	identical versions. */
2618	DEFHOOK
2619	(get_function_versions_dispatcher,
2620	"This hook is used to get the dispatcher function for a set of function\n\
2621	versions. The dispatcher function is called to invoke the right function\n\
2622	version at run-time. @var{decl} is one version from a set of semantically\n\
2623	identical versions.",
2624	tree, (void *decl), NULL)
2625
2626	/* Target hook is used to ignore certain versions specified in a target_clones
2627	annoration. STR is the version to be considered. */
2628	DEFHOOK
2629	(check_target_clone_version ,
2630	"This hook is used to check if a version specified in a @code{target_clones}\n\
2631	annotation is valid. @var{str} is the version to be considered.\n\
2632	If @var{loc} is not @code{NULL} then emit warnings for invalid versions at\n\
2633	that location. Otherwise emit no diagnostics.\n\
2634	Returns @code{true} if @var{str} is a valid version string, and @code{false}\n\
2635	otherwise",
2636	bool, (string_slice str, location_t *loc),
2637	hook_stringslice_locationtptr_true)
2638
2639	/* Returns a code for a target-specific builtin that implements
2640	reciprocal of a target-specific function, or NULL_TREE if not available. */
2641	DEFHOOK
2642	(builtin_reciprocal,
2643	"This hook should return the DECL of a function that implements the\n\
2644	reciprocal of the machine-specific builtin function @var{fndecl}, or\n\
2645	@code{NULL_TREE} if such a function is not available.",
2646	tree, (tree fndecl),
2647	default_builtin_reciprocal)
2648
2649	/* For a vendor-specific TYPE, return a pointer to a statically-allocated
2650	string containing the C++ mangling for TYPE. In all other cases, return
2651	NULL. */
2652	DEFHOOK
2653	(mangle_type,
2654	"If your target defines any fundamental types, or any types your target\n\
2655	uses should be mangled differently from the default, define this hook\n\
2656	to return the appropriate encoding for these types as part of a C++\n\
2657	mangled name. The @var{type} argument is the tree structure representing\n\
2658	the type to be mangled. The hook may be applied to trees which are\n\
2659	not target-specific fundamental types; it should return @code{NULL}\n\
2660	for all such types, as well as arguments it does not recognize. If the\n\
2661	return value is not @code{NULL}, it must point to a statically-allocated\n\
2662	string constant.\n\
2663	\n\
2664	Target-specific fundamental types might be new fundamental types or\n\
2665	qualified versions of ordinary fundamental types. Encode new\n\
2666	fundamental types as @samp{@w{u @var{n} @var{name}}}, where @var{name}\n\
2667	is the name used for the type in source code, and @var{n} is the\n\
2668	length of @var{name} in decimal. Encode qualified versions of\n\
2669	ordinary types as @samp{@w{U @var{n} @var{name} @var{code}}}, where\n\
2670	@var{name} is the name used for the type qualifier in source code,\n\
2671	@var{n} is the length of @var{name} as above, and @var{code} is the\n\
2672	code used to represent the unqualified version of this type. (See\n\
2673	@code{write_builtin_type} in @file{cp/mangle.cc} for the list of\n\
2674	codes.) In both cases the spaces are for clarity; do not include any\n\
2675	spaces in your string.\n\
2676	\n\
2677	This hook is applied to types prior to typedef resolution. If the mangled\n\
2678	name for a particular type depends only on that type's main variant, you\n\
2679	can perform typedef resolution yourself using @code{TYPE_MAIN_VARIANT}\n\
2680	before mangling.\n\
2681	\n\
2682	The default version of this hook always returns @code{NULL}, which is\n\
2683	appropriate for a target that does not define any new fundamental\n\
2684	types.",
2685	const char *, (const_tree type),
2686	hook_constcharptr_const_tree_null)
2687
2688	/* Temporarily add conditional target specific types for the purpose of
2689	emitting C++ fundamental type tinfos. */
2690	DEFHOOK
2691	(emit_support_tinfos,
2692	"If your target defines any fundamental types which depend on ISA flags,\n\
2693	they might need C++ tinfo symbols in libsupc++/libstdc++ regardless of\n\
2694	ISA flags the library is compiled with.\n\
2695	This hook allows creating tinfo symbols even for those cases, by temporarily\n\
2696	creating each corresponding fundamental type trees, calling the\n\
2697	@var{callback} function on it and setting the type back to @code{nullptr}.",
2698	void, (emit_support_tinfos_callback callback),
2699	default_emit_support_tinfos)
2700
2701	/* Make any adjustments to libfunc names needed for this target. */
2702	DEFHOOK
2703	(init_libfuncs,
2704	"This hook should declare additional library routines or rename\n\
2705	existing ones, using the functions @code{set_optab_libfunc} and\n\
2706	@code{init_one_libfunc} defined in @file{optabs.cc}.\n\
2707	@code{init_optabs} calls this macro after initializing all the normal\n\
2708	library routines.\n\
2709	\n\
2710	The default is to do nothing. Most ports don't need to define this hook.",
2711	void, (void),
2712	hook_void_void)
2713
2714	/* Add a __gnu_ prefix to library functions rather than just __. */
2715	DEFHOOKPOD
2716	(libfunc_gnu_prefix,
2717	"If false (the default), internal library routines start with two\n\
2718	underscores. If set to true, these routines start with @code{__gnu_}\n\
2719	instead. E.g., @code{__muldi3} changes to @code{__gnu_muldi3}. This\n\
2720	currently only affects functions defined in @file{libgcc2.c}. If this\n\
2721	is set to true, the @file{tm.h} file must also\n\
2722	@code{#define LIBGCC2_GNU_PREFIX}.",
2723	bool, false)
2724
2725	/* Given a decl, a section name, and whether the decl initializer
2726	has relocs, choose attributes for the section. */
2727	/* ??? Should be merged with SELECT_SECTION and UNIQUE_SECTION. */
2728	DEFHOOK
2729	(section_type_flags,
2730	"Choose a set of section attributes for use by @code{TARGET_ASM_NAMED_SECTION}\n\
2731	based on a variable or function decl, a section name, and whether or not the\n\
2732	declaration's initializer may contain runtime relocations. @var{decl} may be\n\
2733	null, in which case read-write data should be assumed.\n\
2734	\n\
2735	The default version of this function handles choosing code vs data,\n\
2736	read-only vs read-write data, and @code{flag_pic}. You should only\n\
2737	need to override this if your target has special flags that might be\n\
2738	set via @code{__attribute__}.",
2739	unsigned int, (tree decl, const char *name, int reloc),
2740	default_section_type_flags)
2741
2742	DEFHOOK
2743	(libc_has_function,
2744	"This hook determines whether a function from a class of functions\n\
2745	@var{fn_class} is present in the target C library. If @var{type} is NULL,\n\
2746	the caller asks for support for all standard (float, double, long double)\n\
2747	types. If @var{type} is non-NULL, the caller asks for support for a\n\
2748	specific type.",
2749	bool, (enum function_class fn_class, tree type),
2750	default_libc_has_function)
2751
2752	DEFHOOK
2753	(libc_has_fast_function,
2754	"This hook determines whether a function from a class of functions\n\
2755	@code{(enum function_class)}@var{fcode} has a fast implementation.",
2756	bool, (int fcode),
2757	default_libc_has_fast_function)
2758
2759	DEFHOOK
2760	(fortify_source_default_level,
2761	"This hook determines what value _FORTIFY_SOURCE will be set to when using\n\
2762	the command-line option -fhardened.",
2763	unsigned, (void),
2764	default_fortify_source_default_level)
2765
2766	DEFHOOK
2767	(libm_function_max_error,
2768	"This hook determines expected maximum errors for math functions measured\n\
2769	in ulps (units of the last place). 0 means 0.5ulps precision (correctly\n\
2770	rounded). ~0U means unknown errors. The @code{combined_fn} @var{cfn}\n\
2771	argument should identify just which math built-in function it is rather than\n\
2772	its variant, @var{mode} the variant in terms of floating-point machine mode.\n\
2773	The hook should also take into account @code{flag_rounding_math} whether it\n\
2774	is maximum error just in default rounding mode, or in all possible rounding\n\
2775	modes. @var{boundary_p} is @code{true} for maximum errors on intrinsic math\n\
2776	boundaries of functions rather than errors inside of the usual result ranges\n\
2777	of the functions. E.g.@ the sin/cos function finite result is in between\n\
2778	-1.0 and 1.0 inclusive, with @var{boundary_p} true the function returns how\n\
2779	many ulps below or above those boundaries result could be.",
2780	unsigned, (unsigned cfn, machine_mode mode, bool boundary_p),
2781	default_libm_function_max_error)
2782
2783	/* True if new jumps cannot be created, to replace existing ones or
2784	not, at the current point in the compilation. */
2785	DEFHOOK
2786	(cannot_modify_jumps_p,
2787	"This target hook returns @code{true} past the point in which new jump\n\
2788	instructions could be created. On machines that require a register for\n\
2789	every jump such as the SHmedia ISA of SH5, this point would typically be\n\
2790	reload, so this target hook should be defined to a function such as:\n\
2791	\n\
2792	@smallexample\n\
2793	static bool\n\
2794	cannot_modify_jumps_past_reload_p ()\n\
2795	@{\n\
2796	return (reload_completed || reload_in_progress);\n\
2797	@}\n\
2798	@end smallexample",
2799	bool, (void),
2800	hook_bool_void_false)
2801
2802	/* True if FOLLOWER may be modified to follow FOLLOWEE. */
2803	DEFHOOK
2804	(can_follow_jump,
2805	"FOLLOWER and FOLLOWEE are JUMP_INSN instructions;\n\
2806	return true if FOLLOWER may be modified to follow FOLLOWEE;\n\
2807	false, if it can't.\n\
2808	For example, on some targets, certain kinds of branches can't be made to\n\
2809	follow through a hot/cold partitioning.",
2810	bool, (const rtx_insn *follower, const rtx_insn *followee),
2811	hook_bool_const_rtx_insn_const_rtx_insn_true)
2812
2813	/* Return true if the target supports conditional execution. */
2814	DEFHOOK
2815	(have_conditional_execution,
2816	"This target hook returns true if the target supports conditional execution.\n\
2817	This target hook is required only when the target has several different\n\
2818	modes and they have different conditional execution capability, such as ARM.",
2819	bool, (void),
2820	default_have_conditional_execution)
2821
2822	DEFHOOK
2823	(gen_ccmp_first,
2824	"This function prepares to emit a comparison insn for the first compare in a\n\
2825	sequence of conditional comparisions. It returns an appropriate comparison\n\
2826	with @code{CC} for passing to @code{gen_ccmp_next} or @code{cbranch_optab}.\n\
2827	The insns to prepare the compare are saved in @var{prep_seq} and the compare\n\
2828	insns are saved in @var{gen_seq}. They will be emitted when all the\n\
2829	compares in the conditional comparision are generated without error.\n\
2830	@var{code} is the @code{rtx_code} of the compare for @var{op0} and @var{op1}.",
2831	rtx, (rtx_insn **prep_seq, rtx_insn **gen_seq, rtx_code code, tree op0, tree op1),
2832	NULL)
2833
2834	DEFHOOK
2835	(gen_ccmp_next,
2836	"This function prepares to emit a conditional comparison within a sequence\n\
2837	of conditional comparisons. It returns an appropriate comparison with\n\
2838	@code{CC} for passing to @code{gen_ccmp_next} or @code{cbranch_optab}.\n\
2839	The insns to prepare the compare are saved in @var{prep_seq} and the compare\n\
2840	insns are saved in @var{gen_seq}. They will be emitted when all the\n\
2841	compares in the conditional comparision are generated without error. The\n\
2842	@var{prev} expression is the result of a prior call to @code{gen_ccmp_first}\n\
2843	or @code{gen_ccmp_next}. It may return @code{NULL} if the combination of\n\
2844	@var{prev} and this comparison is not supported, otherwise the result must\n\
2845	be appropriate for passing to @code{gen_ccmp_next} or @code{cbranch_optab}.\n\
2846	@var{code} is the @code{rtx_code} of the compare for @var{op0} and @var{op1}.\n\
2847	@var{bit_code} is @code{AND} or @code{IOR}, which is the op on the compares.",
2848	rtx, (rtx_insn **prep_seq, rtx_insn **gen_seq, rtx prev, rtx_code cmp_code, tree op0, tree op1, rtx_code bit_code),
2849	NULL)
2850
2851	/* Return true if the target supports conditional compare. */
2852	DEFHOOK
2853	(have_ccmp,
2854	"This target hook returns true if the target supports conditional compare.\n\
2855	This target hook is required only when the ccmp support is conditionally\n\
2856	enabled, such as in response to command-line flags. The default implementation\n\
2857	returns true iff @code{TARGET_GEN_CCMP_FIRST} is defined.",
2858	bool, (void),
2859	default_have_ccmp)
2860
2861	/* Return a new value for loop unroll size. */
2862	DEFHOOK
2863	(loop_unroll_adjust,
2864	"This target hook returns a new value for the number of times @var{loop}\n\
2865	should be unrolled. The parameter @var{nunroll} is the number of times\n\
2866	the loop is to be unrolled. The parameter @var{loop} is a pointer to\n\
2867	the loop, which is going to be checked for unrolling. This target hook\n\
2868	is required only when the target has special constraints like maximum\n\
2869	number of memory accesses.",
2870	unsigned, (unsigned nunroll, class loop *loop),
2871	NULL)
2872
2873	/* True if X is a legitimate MODE-mode immediate operand. */
2874	DEFHOOK
2875	(legitimate_constant_p,
2876	"This hook returns true if @var{x} is a legitimate constant for a\n\
2877	@var{mode}-mode immediate operand on the target machine. You can assume that\n\
2878	@var{x} satisfies @code{CONSTANT_P}, so you need not check this.\n\
2879	\n\
2880	The default definition returns true.",
2881	bool, (machine_mode mode, rtx x),
2882	hook_bool_mode_rtx_true)
2883
2884	/* True if X is a TLS operand whose value should be pre-computed. */
2885	DEFHOOK
2886	(precompute_tls_p,
2887	"This hook returns true if @var{x} is a TLS operand on the target\n\
2888	machine that should be pre-computed when used as the argument in a call.\n\
2889	You can assume that @var{x} satisfies @code{CONSTANT_P}, so you need not \n\
2890	check this.\n\
2891	\n\
2892	The default definition returns false.",
2893	bool, (machine_mode mode, rtx x),
2894	hook_bool_mode_rtx_false)
2895
2896	/* True if the constant X cannot be placed in the constant pool. */
2897	DEFHOOK
2898	(cannot_force_const_mem,
2899	"This hook should return true if @var{x} is of a form that cannot (or\n\
2900	should not) be spilled to the constant pool. @var{mode} is the mode\n\
2901	of @var{x}.\n\
2902	\n\
2903	The default version of this hook returns false.\n\
2904	\n\
2905	The primary reason to define this hook is to prevent reload from\n\
2906	deciding that a non-legitimate constant would be better reloaded\n\
2907	from the constant pool instead of spilling and reloading a register\n\
2908	holding the constant. This restriction is often true of addresses\n\
2909	of TLS symbols for various targets.",
2910	bool, (machine_mode mode, rtx x),
2911	hook_bool_mode_rtx_false)
2912
2913	DEFHOOK_UNDOC
2914	(cannot_copy_insn_p,
2915	"True if the insn @var{x} cannot be duplicated.",
2916	bool, (rtx_insn *), NULL)
2917
2918	/* True if X is considered to be commutative. */
2919	DEFHOOK
2920	(commutative_p,
2921	"This target hook returns @code{true} if @var{x} is considered to be commutative.\n\
2922	Usually, this is just COMMUTATIVE_P (@var{x}), but the HP PA doesn't consider\n\
2923	PLUS to be commutative inside a MEM@. @var{outer_code} is the rtx code\n\
2924	of the enclosing rtl, if known, otherwise it is UNKNOWN.",
2925	bool, (const_rtx x, int outer_code),
2926	hook_bool_const_rtx_commutative_p)
2927
2928	/* True if ADDR is an address-expression whose effect depends
2929	on the mode of the memory reference it is used in. */
2930	DEFHOOK
2931	(mode_dependent_address_p,
2932	"This hook returns @code{true} if memory address @var{addr} in address\n\
2933	space @var{addrspace} can have\n\
2934	different meanings depending on the machine mode of the memory\n\
2935	reference it is used for or if the address is valid for some modes\n\
2936	but not others.\n\
2937	\n\
2938	Autoincrement and autodecrement addresses typically have mode-dependent\n\
2939	effects because the amount of the increment or decrement is the size\n\
2940	of the operand being addressed. Some machines have other mode-dependent\n\
2941	addresses. Many RISC machines have no mode-dependent addresses.\n\
2942	\n\
2943	You may assume that @var{addr} is a valid address for the machine.\n\
2944	\n\
2945	The default version of this hook returns @code{false}.",
2946	bool, (const_rtx addr, addr_space_t addrspace),
2947	default_mode_dependent_address_p)
2948
2949	/* Given an invalid address X for a given machine mode, try machine-specific
2950	ways to make it legitimate. Return X or an invalid address on failure. */
2951	DEFHOOK
2952	(legitimize_address,
2953	"This hook is given an invalid memory address @var{x} for an\n\
2954	operand of mode @var{mode} and should try to return a valid memory\n\
2955	address.\n\
2956	\n\
2957	@findex break_out_memory_refs\n\
2958	@var{x} will always be the result of a call to @code{break_out_memory_refs},\n\
2959	and @var{oldx} will be the operand that was given to that function to produce\n\
2960	@var{x}.\n\
2961	\n\
2962	The code of the hook should not alter the substructure of\n\
2963	@var{x}. If it transforms @var{x} into a more legitimate form, it\n\
2964	should return the new @var{x}.\n\
2965	\n\
2966	It is not necessary for this hook to come up with a legitimate address,\n\
2967	with the exception of native TLS addresses (@pxref{Emulated TLS}).\n\
2968	The compiler has standard ways of doing so in all cases. In fact, if\n\
2969	the target supports only emulated TLS, it\n\
2970	is safe to omit this hook or make it return @var{x} if it cannot find\n\
2971	a valid way to legitimize the address. But often a machine-dependent\n\
2972	strategy can generate better code.",
2973	rtx, (rtx x, rtx oldx, machine_mode mode),
2974	default_legitimize_address)
2975
2976	/* Given an address RTX, undo the effects of LEGITIMIZE_ADDRESS. */
2977	DEFHOOK
2978	(delegitimize_address,
2979	"This hook is used to undo the possibly obfuscating effects of the\n\
2980	@code{LEGITIMIZE_ADDRESS} and @code{LEGITIMIZE_RELOAD_ADDRESS} target\n\
2981	macros. Some backend implementations of these macros wrap symbol\n\
2982	references inside an @code{UNSPEC} rtx to represent PIC or similar\n\
2983	addressing modes. This target hook allows GCC's optimizers to understand\n\
2984	the semantics of these opaque @code{UNSPEC}s by converting them back\n\
2985	into their original form.",
2986	rtx, (rtx x),
2987	delegitimize_mem_from_attrs)
2988
2989	/* Given an RTX, return true if it is not ok to emit it into debug info
2990	section. */
2991	DEFHOOK
2992	(const_not_ok_for_debug_p,
2993	"This hook should return true if @var{x} should not be emitted into\n\
2994	debug sections.",
2995	bool, (rtx x),
2996	default_const_not_ok_for_debug_p)
2997
2998	/* Given an address RTX, say whether it is valid. */
2999	DEFHOOK
3000	(legitimate_address_p,
3001	"A function that returns whether @var{x} (an RTX) is a legitimate memory\n\
3002	address on the target machine for a memory operand of mode @var{mode}.\n\
3003	If @var{ch} is not @code{ERROR_MARK}, it can be called from middle-end to\n\
3004	determine if it is valid to use @var{x} as a memory operand for RTX insn\n\
3005	which is generated for the given code_helper @var{ch}. For example,\n\
3006	assuming the given @var{ch} is IFN_LEN_LOAD, on some target its underlying\n\
3007	hardware instructions support fewer addressing modes than what are for the\n\
3008	normal vector load and store, then with this @var{ch} target can know the\n\
3009	actual use context and return more exact result.\n\
3010	\n\
3011	Legitimate addresses are defined in two variants: a strict variant and a\n\
3012	non-strict one. The @var{strict} parameter chooses which variant is\n\
3013	desired by the caller.\n\
3014	\n\
3015	The strict variant is used in the reload pass. It must be defined so\n\
3016	that any pseudo-register that has not been allocated a hard register is\n\
3017	considered a memory reference. This is because in contexts where some\n\
3018	kind of register is required, a pseudo-register with no hard register\n\
3019	must be rejected. For non-hard registers, the strict variant should look\n\
3020	up the @code{reg_renumber} array; it should then proceed using the hard\n\
3021	register number in the array, or treat the pseudo as a memory reference\n\
3022	if the array holds @code{-1}.\n\
3023	\n\
3024	The non-strict variant is used in other passes. It must be defined to\n\
3025	accept all pseudo-registers in every context where some kind of\n\
3026	register is required.\n\
3027	\n\
3028	Normally, constant addresses which are the sum of a @code{symbol_ref}\n\
3029	and an integer are stored inside a @code{const} RTX to mark them as\n\
3030	constant. Therefore, there is no need to recognize such sums\n\
3031	specifically as legitimate addresses. Normally you would simply\n\
3032	recognize any @code{const} as legitimate.\n\
3033	\n\
3034	Usually @code{PRINT_OPERAND_ADDRESS} is not prepared to handle constant\n\
3035	sums that are not marked with @code{const}. It assumes that a naked\n\
3036	@code{plus} indicates indexing. If so, then you @emph{must} reject such\n\
3037	naked constant sums as illegitimate addresses, so that none of them will\n\
3038	be given to @code{PRINT_OPERAND_ADDRESS}.\n\
3039	\n\
3040	@cindex @code{TARGET_ENCODE_SECTION_INFO} and address validation\n\
3041	On some machines, whether a symbolic address is legitimate depends on\n\
3042	the section that the address refers to. On these machines, define the\n\
3043	target hook @code{TARGET_ENCODE_SECTION_INFO} to store the information\n\
3044	into the @code{symbol_ref}, and then check for it here. When you see a\n\
3045	@code{const}, you will have to look inside it to find the\n\
3046	@code{symbol_ref} in order to determine the section. @xref{Assembler\n\
3047	Format}.\n\
3048	\n\
3049	@cindex @code{GO_IF_LEGITIMATE_ADDRESS}\n\
3050	Some ports are still using a deprecated legacy substitute for\n\
3051	this hook, the @code{GO_IF_LEGITIMATE_ADDRESS} macro. This macro\n\
3052	has this syntax:\n\
3053	\n\
3054	@example\n\
3055	#define GO_IF_LEGITIMATE_ADDRESS (@var{mode}, @var{x}, @var{label})\n\
3056	@end example\n\
3057	\n\
3058	@noindent\n\
3059	and should @code{goto @var{label}} if the address @var{x} is a valid\n\
3060	address on the target machine for a memory operand of mode @var{mode}.\n\
3061	\n\
3062	@findex REG_OK_STRICT\n\
3063	Compiler source files that want to use the strict variant of this\n\
3064	macro define the macro @code{REG_OK_STRICT}. You should use an\n\
3065	@code{#ifdef REG_OK_STRICT} conditional to define the strict variant in\n\
3066	that case and the non-strict variant otherwise.\n\
3067	\n\
3068	Using the hook is usually simpler because it limits the number of\n\
3069	files that are recompiled when changes are made.",
3070	bool, (machine_mode mode, rtx x, bool strict, code_helper ch),
3071	default_legitimate_address_p)
3072
3073	/* True if the given constant can be put into an object_block. */
3074	DEFHOOK
3075	(use_blocks_for_constant_p,
3076	"This hook should return true if pool entries for constant @var{x} can\n\
3077	be placed in an @code{object_block} structure. @var{mode} is the mode\n\
3078	of @var{x}.\n\
3079	\n\
3080	The default version returns false for all constants.",
3081	bool, (machine_mode mode, const_rtx x),
3082	hook_bool_mode_const_rtx_false)
3083
3084	/* True if the given decl can be put into an object_block. */
3085	DEFHOOK
3086	(use_blocks_for_decl_p,
3087	"This hook should return true if pool entries for @var{decl} should\n\
3088	be placed in an @code{object_block} structure.\n\
3089	\n\
3090	The default version returns true for all decls.",
3091	bool, (const_tree decl),
3092	hook_bool_const_tree_true)
3093
3094	/* The minimum and maximum byte offsets for anchored addresses. */
3095	DEFHOOKPOD
3096	(min_anchor_offset,
3097	"The minimum offset that should be applied to a section anchor.\n\
3098	On most targets, it should be the smallest offset that can be\n\
3099	applied to a base register while still giving a legitimate address\n\
3100	for every mode. The default value is 0.",
3101	HOST_WIDE_INT, 0)
3102
3103	DEFHOOKPOD
3104	(max_anchor_offset,
3105	"Like @code{TARGET_MIN_ANCHOR_OFFSET}, but the maximum (inclusive)\n\
3106	offset that should be applied to section anchors. The default\n\
3107	value is 0.",
3108	HOST_WIDE_INT, 0)
3109
3110	/* True if section anchors can be used to access the given symbol. */
3111	DEFHOOK
3112	(use_anchors_for_symbol_p,
3113	"Return true if GCC should attempt to use anchors to access @code{SYMBOL_REF}\n\
3114	@var{x}. You can assume @samp{SYMBOL_REF_HAS_BLOCK_INFO_P (@var{x})} and\n\
3115	@samp{!SYMBOL_REF_ANCHOR_P (@var{x})}.\n\
3116	\n\
3117	The default version is correct for most targets, but you might need to\n\
3118	intercept this hook to handle things like target-specific attributes\n\
3119	or target-specific sections.",
3120	bool, (const_rtx x),
3121	default_use_anchors_for_symbol_p)
3122
3123	/* True if target supports indirect functions. */
3124	DEFHOOK
3125	(has_ifunc_p,
3126	"It returns true if the target supports GNU indirect functions.\n\
3127	The support includes the assembler, linker and dynamic linker.\n\
3128	The default value of this hook is based on target's libc.",
3129	bool, (void),
3130	default_has_ifunc_p)
3131
3132	/* True if it is OK to reference indirect function resolvers locally. */
3133	DEFHOOK
3134	(ifunc_ref_local_ok,
3135	"Return true if it is OK to reference indirect function resolvers\n\
3136	locally. The default is to return false.",
3137	bool, (void),
3138	hook_bool_void_false)
3139
3140	/* True if it is OK to do sibling call optimization for the specified
3141	call expression EXP. DECL will be the called function, or NULL if
3142	this is an indirect call. */
3143	DEFHOOK
3144	(function_ok_for_sibcall,
3145	"True if it is OK to do sibling call optimization for the specified\n\
3146	call expression @var{exp}. @var{decl} will be the called function,\n\
3147	or @code{NULL} if this is an indirect call.\n\
3148	\n\
3149	It is not uncommon for limitations of calling conventions to prevent\n\
3150	tail calls to functions outside the current unit of translation, or\n\
3151	during PIC compilation. The hook is used to enforce these restrictions,\n\
3152	as the @code{sibcall} md pattern cannot fail, or fall over to a\n\
3153	``normal'' call. The criteria for successful sibling call optimization\n\
3154	may vary greatly between different architectures.",
3155	bool, (tree decl, tree exp),
3156	hook_bool_tree_tree_false)
3157
3158	/* Establish appropriate back-end context for processing the function
3159	FNDECL. The argument might be NULL to indicate processing at top
3160	level, outside of any function scope. */
3161	DEFHOOK
3162	(set_current_function,
3163	"The compiler invokes this hook whenever it changes its current function\n\
3164	context (@code{cfun}). You can define this function if\n\
3165	the back end needs to perform any initialization or reset actions on a\n\
3166	per-function basis. For example, it may be used to implement function\n\
3167	attributes that affect register usage or code generation patterns.\n\
3168	The argument @var{decl} is the declaration for the new function context,\n\
3169	and may be null to indicate that the compiler has left a function context\n\
3170	and is returning to processing at the top level.\n\
3171	The default hook function does nothing.\n\
3172	\n\
3173	GCC sets @code{cfun} to a dummy function context during initialization of\n\
3174	some parts of the back end. The hook function is not invoked in this\n\
3175	situation; you need not worry about the hook being invoked recursively,\n\
3176	or when the back end is in a partially-initialized state.\n\
3177	@code{cfun} might be @code{NULL} to indicate processing at top level,\n\
3178	outside of any function scope.",
3179	void, (tree decl), hook_void_tree)
3180
3181	/* True if EXP should be placed in a "small data" section. */
3182	DEFHOOK
3183	(in_small_data_p,
3184	"Returns true if @var{exp} should be placed into a ``small data'' section.\n\
3185	The default version of this hook always returns false.",
3186	bool, (const_tree exp),
3187	hook_bool_const_tree_false)
3188
3189	/* True if EXP names an object for which name resolution must resolve
3190	to the current executable or shared library. */
3191	DEFHOOK
3192	(binds_local_p,
3193	"Returns true if @var{exp} names an object for which name resolution\n\
3194	rules must resolve to the current ``module'' (dynamic shared library\n\
3195	or executable image).\n\
3196	\n\
3197	The default version of this hook implements the name resolution rules\n\
3198	for ELF, which has a looser model of global name binding than other\n\
3199	currently supported object file formats.",
3200	bool, (const_tree exp),
3201	default_binds_local_p)
3202
3203	/* Check if profiling code is before or after prologue. */
3204	DEFHOOK
3205	(profile_before_prologue,
3206	"It returns true if target wants profile code emitted before prologue.\n\n\
3207	The default version of this hook use the target macro\n\
3208	@code{PROFILE_BEFORE_PROLOGUE}.",
3209	bool, (void),
3210	default_profile_before_prologue)
3211
3212	/* Return true if a leaf function should stay leaf even with profiling
3213	enabled. */
3214	DEFHOOK
3215	(keep_leaf_when_profiled,
3216	"This target hook returns true if the target wants the leaf flag for\n\
3217	the current function to stay true even if it calls mcount. This might\n\
3218	make sense for targets using the leaf flag only to determine whether a\n\
3219	stack frame needs to be generated or not and for which the call to\n\
3220	mcount is generated before the function prologue.",
3221	bool, (void),
3222	default_keep_leaf_when_profiled)
3223
3224	/* Modify and return the identifier of a DECL's external name,
3225	originally identified by ID, as required by the target,
3226	(eg, append @nn to windows32 stdcall function names).
3227	The default is to return ID without modification. */
3228	DEFHOOK
3229	(mangle_decl_assembler_name,
3230	"Define this hook if you need to postprocess the assembler name generated\n\
3231	by target-independent code. The @var{id} provided to this hook will be\n\
3232	the computed name (e.g., the macro @code{DECL_NAME} of the @var{decl} in C,\n\
3233	or the mangled name of the @var{decl} in C++). The return value of the\n\
3234	hook is an @code{IDENTIFIER_NODE} for the appropriate mangled name on\n\
3235	your target system. The default implementation of this hook just\n\
3236	returns the @var{id} provided.",
3237	tree, (tree decl, tree id),
3238	default_mangle_decl_assembler_name)
3239
3240	/* Do something target-specific to record properties of the DECL into
3241	the associated SYMBOL_REF. */
3242	DEFHOOK
3243	(encode_section_info,
3244	"Define this hook if references to a symbol or a constant must be\n\
3245	treated differently depending on something about the variable or\n\
3246	function named by the symbol (such as what section it is in).\n\
3247	\n\
3248	The hook is executed immediately after rtl has been created for\n\
3249	@var{decl}, which may be a variable or function declaration or\n\
3250	an entry in the constant pool. In either case, @var{rtl} is the\n\
3251	rtl in question. Do @emph{not} use @code{DECL_RTL (@var{decl})}\n\
3252	in this hook; that field may not have been initialized yet.\n\
3253	\n\
3254	In the case of a constant, it is safe to assume that the rtl is\n\
3255	a @code{mem} whose address is a @code{symbol_ref}. Most decls\n\
3256	will also have this form, but that is not guaranteed. Global\n\
3257	register variables, for instance, will have a @code{reg} for their\n\
3258	rtl. (Normally the right thing to do with such unusual rtl is\n\
3259	leave it alone.)\n\
3260	\n\
3261	The @var{new_decl_p} argument will be true if this is the first time\n\
3262	that @code{TARGET_ENCODE_SECTION_INFO} has been invoked on this decl. It will\n\
3263	be false for subsequent invocations, which will happen for duplicate\n\
3264	declarations. Whether or not anything must be done for the duplicate\n\
3265	declaration depends on whether the hook examines @code{DECL_ATTRIBUTES}.\n\
3266	@var{new_decl_p} is always true when the hook is called for a constant.\n\
3267	\n\
3268	@cindex @code{SYMBOL_REF_FLAG}, in @code{TARGET_ENCODE_SECTION_INFO}\n\
3269	The usual thing for this hook to do is to record flags in the\n\
3270	@code{symbol_ref}, using @code{SYMBOL_REF_FLAG} or @code{SYMBOL_REF_FLAGS}.\n\
3271	Historically, the name string was modified if it was necessary to\n\
3272	encode more than one bit of information, but this practice is now\n\
3273	discouraged; use @code{SYMBOL_REF_FLAGS}.\n\
3274	\n\
3275	The default definition of this hook, @code{default_encode_section_info}\n\
3276	in @file{varasm.cc}, sets a number of commonly-useful bits in\n\
3277	@code{SYMBOL_REF_FLAGS}. Check whether the default does what you need\n\
3278	before overriding it.",
3279	void, (tree decl, rtx rtl, int new_decl_p),
3280	default_encode_section_info)
3281
3282	/* Undo the effects of encode_section_info on the symbol string. */
3283	DEFHOOK
3284	(strip_name_encoding,
3285	"Decode @var{name} and return the real name part, sans\n\
3286	the characters that @code{TARGET_ENCODE_SECTION_INFO}\n\
3287	may have added.",
3288	const char *, (const char *name),
3289	default_strip_name_encoding)
3290
3291	/* If shift optabs for MODE are known to always truncate the shift count,
3292	return the mask that they apply. Return 0 otherwise. */
3293	DEFHOOK
3294	(shift_truncation_mask,
3295	"This function describes how the standard shift patterns for @var{mode}\n\
3296	deal with shifts by negative amounts or by more than the width of the mode.\n\
3297	@xref{shift patterns}.\n\
3298	\n\
3299	On many machines, the shift patterns will apply a mask @var{m} to the\n\
3300	shift count, meaning that a fixed-width shift of @var{x} by @var{y} is\n\
3301	equivalent to an arbitrary-width shift of @var{x} by @var{y & m}. If\n\
3302	this is true for mode @var{mode}, the function should return @var{m},\n\
3303	otherwise it should return 0. A return value of 0 indicates that no\n\
3304	particular behavior is guaranteed.\n\
3305	\n\
3306	Note that, unlike @code{SHIFT_COUNT_TRUNCATED}, this function does\n\
3307	@emph{not} apply to general shift rtxes; it applies only to instructions\n\
3308	that are generated by the named shift patterns.\n\
3309	\n\
3310	The default implementation of this function returns\n\
3311	@code{GET_MODE_BITSIZE (@var{mode}) - 1} if @code{SHIFT_COUNT_TRUNCATED}\n\
3312	and 0 otherwise. This definition is always safe, but if\n\
3313	@code{SHIFT_COUNT_TRUNCATED} is false, and some shift patterns\n\
3314	nevertheless truncate the shift count, you may get better code\n\
3315	by overriding it.",
3316	unsigned HOST_WIDE_INT, (machine_mode mode),
3317	default_shift_truncation_mask)
3318
3319	/* Return the number of divisions in the given MODE that should be present,
3320	so that it is profitable to turn the division into a multiplication by
3321	the reciprocal. */
3322	DEFHOOK
3323	(min_divisions_for_recip_mul,
3324	"When @option{-ffast-math} is in effect, GCC tries to optimize\n\
3325	divisions by the same divisor, by turning them into multiplications by\n\
3326	the reciprocal. This target hook specifies the minimum number of divisions\n\
3327	that should be there for GCC to perform the optimization for a variable\n\
3328	of mode @var{mode}. The default implementation returns 3 if the machine\n\
3329	has an instruction for the division, and 2 if it does not.",
3330	unsigned int, (machine_mode mode),
3331	default_min_divisions_for_recip_mul)
3332
3333	DEFHOOK
3334	(truly_noop_truncation,
3335	"This hook returns true if it is safe to ``convert'' a value of\n\
3336	@var{inprec} bits to one of @var{outprec} bits (where @var{outprec} is\n\
3337	smaller than @var{inprec}) by merely operating on it as if it had only\n\
3338	@var{outprec} bits. The default returns true unconditionally, which\n\
3339	is correct for most machines. When @code{TARGET_TRULY_NOOP_TRUNCATION}\n\
3340	returns false, the machine description should provide a @code{trunc}\n\
3341	optab to specify the RTL that performs the required truncation.\n\
3342	\n\
3343	If @code{TARGET_MODES_TIEABLE_P} returns false for a pair of modes,\n\
3344	suboptimal code can result if this hook returns true for the corresponding\n\
3345	mode sizes. Making this hook return false in such cases may improve things.",
3346	bool, (poly_uint64 outprec, poly_uint64 inprec),
3347	hook_bool_puint64_puint64_true)
3348
3349	/* If the representation of integral MODE is such that values are
3350	always sign-extended to a wider mode MODE_REP then return
3351	SIGN_EXTEND. Return UNKNOWN otherwise. */
3352	/* Note that the return type ought to be RTX_CODE, but that's not
3353	necessarily defined at this point. */
3354	DEFHOOK
3355	(mode_rep_extended,
3356	"The representation of an integral mode can be such that the values\n\
3357	are always extended to a wider integral mode. Return\n\
3358	@code{SIGN_EXTEND} if values of @var{mode} are represented in\n\
3359	sign-extended form to @var{rep_mode}. Return @code{UNKNOWN}\n\
3360	otherwise. (Currently, none of the targets use zero-extended\n\
3361	representation this way so unlike @code{LOAD_EXTEND_OP},\n\
3362	@code{TARGET_MODE_REP_EXTENDED} is expected to return either\n\
3363	@code{SIGN_EXTEND} or @code{UNKNOWN}. Also no target extends\n\
3364	@var{mode} to @var{rep_mode} so that @var{rep_mode} is not the next\n\
3365	widest integral mode and currently we take advantage of this fact.)\n\
3366	\n\
3367	Similarly to @code{LOAD_EXTEND_OP} you may return a non-@code{UNKNOWN}\n\
3368	value even if the extension is not performed on certain hard registers\n\
3369	as long as for the @code{REGNO_REG_CLASS} of these hard registers\n\
3370	@code{TARGET_CAN_CHANGE_MODE_CLASS} returns false.\n\
3371	\n\
3372	Note that @code{TARGET_MODE_REP_EXTENDED} and @code{LOAD_EXTEND_OP}\n\
3373	describe two related properties. If you define\n\
3374	@code{TARGET_MODE_REP_EXTENDED (mode, word_mode)} you probably also want\n\
3375	to define @code{LOAD_EXTEND_OP (mode)} to return the same type of\n\
3376	extension.\n\
3377	\n\
3378	In order to enforce the representation of @code{mode},\n\
3379	@code{TARGET_TRULY_NOOP_TRUNCATION} should return false when truncating to\n\
3380	@code{mode}.",
3381	int, (scalar_int_mode mode, scalar_int_mode rep_mode),
3382	default_mode_rep_extended)
3383
3384	DEFHOOK
3385	(setjmp_preserves_nonvolatile_regs_p,
3386	"On some targets, it is assumed that the compiler will spill all pseudos\n\
3387	that are live across a call to @code{setjmp}, while other targets treat\n\
3388	@code{setjmp} calls as normal function calls.\n\
3389	\n\
3390	This hook returns false if @code{setjmp} calls do not preserve all\n\
3391	non-volatile registers so that gcc that must spill all pseudos that are\n\
3392	live across @code{setjmp} calls. Define this to return true if the\n\
3393	target does not need to spill all pseudos live across @code{setjmp} calls.\n\
3394	The default implementation conservatively assumes all pseudos must be\n\
3395	spilled across @code{setjmp} calls.",
3396	bool, (void),
3397	hook_bool_void_false)
3398
3399	/* True if MODE is valid for a pointer in __attribute__((mode("MODE"))). */
3400	DEFHOOK
3401	(valid_pointer_mode,
3402	"Define this to return nonzero if the port can handle pointers\n\
3403	with machine mode @var{mode}. The default version of this\n\
3404	hook returns true for both @code{ptr_mode} and @code{Pmode}.",
3405	bool, (scalar_int_mode mode),
3406	default_valid_pointer_mode)
3407
3408	/* Disambiguate with errno. */
3409	DEFHOOK
3410	(ref_may_alias_errno,
3411	"Define this to return nonzero if the memory reference @var{ref}\n\
3412	may alias with the system C library errno location. The default\n\
3413	version of this hook assumes the system C library errno location\n\
3414	is either a declaration of type int or accessed by dereferencing\n\
3415	a pointer to int.",
3416	bool, (ao_ref *ref),
3417	default_ref_may_alias_errno)
3418
3419	DEFHOOK
3420	(mode_can_transfer_bits,
3421	"Define this to return false if the mode @var{mode} cannot be used\n\
3422	for memory copying of @code{GET_MODE_SIZE (mode)} units. This might be\n\
3423	because a register class allowed for @var{mode} has registers that do\n\
3424	not transparently transfer every bit pattern or because the load or\n\
3425	store patterns available for @var{mode} have this issue.\n\
3426	\n\
3427	The default is to assume modes with the same precision as size are fine\n\
3428	to be used.",
3429	bool, (machine_mode mode),
3430	NULL)
3431
3432	DEFHOOK
3433	(redzone_clobber,
3434	"Define this to return some RTL for the @code{redzone} @code{asm} clobber\n\
3435	if target has a red zone and wants to support the @code{redzone} clobber\n\
3436	or return NULL if the clobber should be ignored.\n\
3437	\n\
3438	The default is to ignore the @code{redzone} clobber.",
3439	rtx, (),
3440	NULL)
3441
3442	/* Support for named address spaces. */
3443	#undef HOOK_PREFIX
3444	#define HOOK_PREFIX "TARGET_ADDR_SPACE_"
3445	HOOK_VECTOR (TARGET_ADDR_SPACE_HOOKS, addr_space)
3446
3447	/* MODE to use for a pointer into another address space. */
3448	DEFHOOK
3449	(pointer_mode,
3450	"Define this to return the machine mode to use for pointers to\n\
3451	@var{address_space} if the target supports named address spaces.\n\
3452	The default version of this hook returns @code{ptr_mode}.",
3453	scalar_int_mode, (addr_space_t address_space),
3454	default_addr_space_pointer_mode)
3455
3456	/* MODE to use for an address in another address space. */
3457	DEFHOOK
3458	(address_mode,
3459	"Define this to return the machine mode to use for addresses in\n\
3460	@var{address_space} if the target supports named address spaces.\n\
3461	The default version of this hook returns @code{Pmode}.",
3462	scalar_int_mode, (addr_space_t address_space),
3463	default_addr_space_address_mode)
3464
3465	/* True if MODE is valid for a pointer in __attribute__((mode("MODE")))
3466	in another address space. */
3467	DEFHOOK
3468	(valid_pointer_mode,
3469	"Define this to return nonzero if the port can handle pointers\n\
3470	with machine mode @var{mode} to address space @var{as}. This target\n\
3471	hook is the same as the @code{TARGET_VALID_POINTER_MODE} target hook,\n\
3472	except that it includes explicit named address space support. The default\n\
3473	version of this hook returns true for the modes returned by either the\n\
3474	@code{TARGET_ADDR_SPACE_POINTER_MODE} or @code{TARGET_ADDR_SPACE_ADDRESS_MODE}\n\
3475	target hooks for the given address space.",
3476	bool, (scalar_int_mode mode, addr_space_t as),
3477	default_addr_space_valid_pointer_mode)
3478
3479	/* True if an address is a valid memory address to a given named address
3480	space for a given mode. */
3481	DEFHOOK
3482	(legitimate_address_p,
3483	"Define this to return true if @var{exp} is a valid address for mode\n\
3484	@var{mode} in the named address space @var{as} with the use context\n\
3485	@var{ch}. The @var{strict} parameter says whether strict addressing\n\
3486	is in effect after reload has finished. The @var{ch} indicates what\n\
3487	context @var{exp} will be used for. This target hook is the same as the\n\
3488	@code{TARGET_LEGITIMATE_ADDRESS_P} target hook, except that it includes\n\
3489	explicit named address space support.",
3490	bool, (machine_mode mode, rtx exp, bool strict, addr_space_t as, code_helper ch),
3491	default_addr_space_legitimate_address_p)
3492
3493	/* Return an updated address to convert an invalid pointer to a named
3494	address space to a valid one. If NULL_RTX is returned use machine
3495	independent methods to make the address valid. */
3496	DEFHOOK
3497	(legitimize_address,
3498	"Define this to modify an invalid address @var{x} to be a valid address\n\
3499	with mode @var{mode} in the named address space @var{as}. This target\n\
3500	hook is the same as the @code{TARGET_LEGITIMIZE_ADDRESS} target hook,\n\
3501	except that it includes explicit named address space support.",
3502	rtx, (rtx x, rtx oldx, machine_mode mode, addr_space_t as),
3503	default_addr_space_legitimize_address)
3504
3505	/* True if one named address space is a subset of another named address. */
3506	DEFHOOK
3507	(subset_p,
3508	"Define this to return whether the @var{subset} named address space is\n\
3509	contained within the @var{superset} named address space. Pointers to\n\
3510	a named address space that is a subset of another named address space\n\
3511	will be converted automatically without a cast if used together in\n\
3512	arithmetic operations. Pointers to a superset address space can be\n\
3513	converted to pointers to a subset address space via explicit casts.",
3514	bool, (addr_space_t subset, addr_space_t superset),
3515	default_addr_space_subset_p)
3516
3517	/* True if 0 is a valid address in the address space, or false if
3518	0 is a NULL in the address space. */
3519	DEFHOOK
3520	(zero_address_valid,
3521	"Define this to modify the default handling of address 0 for the\n\
3522	address space. Return true if 0 should be considered a valid address.",
3523	bool, (addr_space_t as),
3524	default_addr_space_zero_address_valid)
3525
3526	/* Function to convert an rtl expression from one address space to another. */
3527	DEFHOOK
3528	(convert,
3529	"Define this to convert the pointer expression represented by the RTL\n\
3530	@var{op} with type @var{from_type} that points to a named address\n\
3531	space to a new pointer expression with type @var{to_type} that points\n\
3532	to a different named address space. When this hook it called, it is\n\
3533	guaranteed that one of the two address spaces is a subset of the other,\n\
3534	as determined by the @code{TARGET_ADDR_SPACE_SUBSET_P} target hook.",
3535	rtx, (rtx op, tree from_type, tree to_type),
3536	default_addr_space_convert)
3537
3538	/* Function to encode an address space into dwarf. */
3539	DEFHOOK
3540	(debug,
3541	"Define this to define how the address space is encoded in dwarf.\n\
3542	The result is the value to be used with @code{DW_AT_address_class}.",
3543	int, (addr_space_t as),
3544	default_addr_space_debug)
3545
3546	/* Function to emit custom diagnostic if an address space is used. */
3547	DEFHOOK
3548	(diagnose_usage,
3549	"Define this hook if the availability of an address space depends on\n\
3550	command line options and some diagnostics should be printed when the\n\
3551	address space is used. This hook is called during parsing and allows\n\
3552	to emit a better diagnostic compared to the case where the address space\n\
3553	was not registered with @code{c_register_addr_space}. @var{as} is\n\
3554	the address space as registered with @code{c_register_addr_space}.\n\
3555	@var{loc} is the location of the address space qualifier token.\n\
3556	The default implementation does nothing.",
3557	void, (addr_space_t as, location_t loc),
3558	default_addr_space_diagnose_usage)
3559
3560	/* Function to patch the address space of some compiler-generated
3561	read-only data. Used for optimization purposes only. */
3562	DEFHOOK
3563	(for_artificial_rodata,
3564	"Define this hook to return a named address space to be used for\n\
3565	@var{type}, usually the type of an artificial lookup-table that would\n\
3566	reside in @code{.rodata} and in the generic address space.\n\
3567	\n\
3568	The hook can be used to put compiler-generated, artificial lookup tables in\n\
3569	static storage into a non-generic address space when it is better suited\n\
3570	than the generic address space.\n\
3571	The compiler will generate all accesses to the respective data\n\
3572	so that all associated accesses will also use the specified address space\n\
3573	and pointer mode.\n\
3574	\n\
3575	@var{type} is the type of the lookup table. @var{purpose} specifies\n\
3576	the purpose of the lookup table. It is one of:\n\
3577	@table @code\n\
3578	@item ARTIFICIAL_RODATA_CSWITCH\n\
3579	@file{tree-switch-conversion.cc} lowered a GIMPLE_SWITCH expressions\n\
3580	to something more efficient than a jump table.\n\
3581	@item ARTIFICIAL_RODATA_CRC\n\
3582	@file{gimple-crc-optimization.cc} optimized a CRC computation by\n\
3583	using a polynomial lookup table.\n\
3584	@end table\n\
3585	The default implementation of the hook returns @code{ADDR_SPACE_GENERIC}.",
3586	addr_space_t, (tree type, enum artificial_rodata purpose),
3587	default_addr_space_for_artificial_rodata)
3588
3589	HOOK_VECTOR_END (addr_space)
3590
3591	#undef HOOK_PREFIX
3592	#define HOOK_PREFIX "TARGET_"
3593
3594	DEFHOOK
3595	(lower_local_decl_alignment,
3596	"Define this hook to lower alignment of local, parm or result\n\
3597	decl @samp{(@var{decl})}.",
3598	void, (tree decl),
3599	hook_void_tree)
3600
3601	DEFHOOK
3602	(static_rtx_alignment,
3603	"This hook returns the preferred alignment in bits for a\n\
3604	statically-allocated rtx, such as a constant pool entry. @var{mode}\n\
3605	is the mode of the rtx. The default implementation returns\n\
3606	@samp{GET_MODE_ALIGNMENT (@var{mode})}.",
3607	HOST_WIDE_INT, (machine_mode mode),
3608	default_static_rtx_alignment)
3609
3610	DEFHOOK
3611	(constant_alignment,
3612	"This hook returns the alignment in bits of a constant that is being\n\
3613	placed in memory. @var{constant} is the constant and @var{basic_align}\n\
3614	is the alignment that the object would ordinarily have.\n\
3615	\n\
3616	The default definition just returns @var{basic_align}.\n\
3617	\n\
3618	The typical use of this hook is to increase alignment for string\n\
3619	constants to be word aligned so that @code{strcpy} calls that copy\n\
3620	constants can be done inline. The function\n\
3621	@code{constant_alignment_word_strings} provides such a definition.",
3622	HOST_WIDE_INT, (const_tree constant, HOST_WIDE_INT basic_align),
3623	default_constant_alignment)
3624
3625	DEFHOOK
3626	(translate_mode_attribute,
3627	"Define this hook if during mode attribute processing, the port should\n\
3628	translate machine_mode @var{mode} to another mode. For example, rs6000's\n\
3629	@code{KFmode}, when it is the same as @code{TFmode}.\n\
3630	\n\
3631	The default version of the hook returns that mode that was passed in.",
3632	machine_mode, (machine_mode mode),
3633	default_translate_mode_attribute)
3634
3635	/* True if MODE is valid for the target. By "valid", we mean able to
3636	be manipulated in non-trivial ways. In particular, this means all
3637	the arithmetic is supported. */
3638	DEFHOOK
3639	(scalar_mode_supported_p,
3640	"Define this to return nonzero if the port is prepared to handle\n\
3641	insns involving scalar mode @var{mode}. For a scalar mode to be\n\
3642	considered supported, all the basic arithmetic and comparisons\n\
3643	must work.\n\
3644	\n\
3645	The default version of this hook returns true for any mode\n\
3646	required to handle the basic C types (as defined by the port).\n\
3647	Included here are the double-word arithmetic supported by the\n\
3648	code in @file{optabs.cc}.",
3649	bool, (scalar_mode mode),
3650	default_scalar_mode_supported_p)
3651
3652	/* Similarly for vector modes. "Supported" here is less strict. At
3653	least some operations are supported; need to check optabs or builtins
3654	for further details. */
3655	DEFHOOK
3656	(vector_mode_supported_p,
3657	"Define this to return nonzero if the current target is prepared to handle\n\
3658	insns involving vector mode @var{mode}. At the very least, it\n\
3659	must have move patterns for this mode.",
3660	bool, (machine_mode mode),
3661	hook_bool_mode_false)
3662
3663	DEFHOOK
3664	(vector_mode_supported_any_target_p,
3665	"Define this to return nonzero if the port is prepared to handle\n\
3666	insns involving vector mode @var{mode} in any target configuration.\n\
3667	Returning @var{true} means that the mode can be used as the @samp{TYPE_MODE}\n\
3668	for vector types.\n\
3669	\n\
3670	The default version of this hook returns true. The final mode assigned to\n\
3671	@samp{TYPE_MODE} will also be checked against\n\
3672	@code{TARGET_VECTOR_MODE_SUPPORTED_P} to take target configuration into\n\
3673	account.",
3674	bool, (machine_mode mode),
3675	hook_bool_mode_true)
3676
3677	DEFHOOK
3678	(compatible_vector_types_p,
3679	"Return true if there is no target-specific reason for treating\n\
3680	vector types @var{type1} and @var{type2} as distinct types. The caller\n\
3681	has already checked for target-independent reasons, meaning that the\n\
3682	types are known to have the same mode, to have the same number of elements,\n\
3683	and to have what the caller considers to be compatible element types.\n\
3684	\n\
3685	The main reason for defining this hook is to reject pairs of types\n\
3686	that are handled differently by the target's calling convention.\n\
3687	For example, when a new @var{N}-bit vector architecture is added\n\
3688	to a target, the target may want to handle normal @var{N}-bit\n\
3689	@code{VECTOR_TYPE} arguments and return values in the same way as\n\
3690	before, to maintain backwards compatibility. However, it may also\n\
3691	provide new, architecture-specific @code{VECTOR_TYPE}s that are passed\n\
3692	and returned in a more efficient way. It is then important to maintain\n\
3693	a distinction between the ``normal'' @code{VECTOR_TYPE}s and the new\n\
3694	architecture-specific ones.\n\
3695	\n\
3696	The default implementation returns true, which is correct for most targets.",
3697	bool, (const_tree type1, const_tree type2),
3698	hook_bool_const_tree_const_tree_true)
3699
3700	DEFHOOK
3701	(vector_alignment,
3702	"This hook can be used to define the alignment for a vector of type\n\
3703	@var{type}, in order to comply with a platform ABI. The default is to\n\
3704	require natural alignment for vector types. The alignment returned by\n\
3705	this hook must be a power-of-two multiple of the default alignment of\n\
3706	the vector element type.",
3707	HOST_WIDE_INT, (const_tree type),
3708	default_vector_alignment)
3709
3710	DEFHOOK
3711	(array_mode,
3712	"Return the mode that GCC should use for an array that has\n\
3713	@var{nelems} elements, with each element having mode @var{mode}.\n\
3714	Return no mode if the target has no special requirements. In the\n\
3715	latter case, GCC looks for an integer mode of the appropriate size\n\
3716	if available and uses BLKmode otherwise. Usually the search for the\n\
3717	integer mode is limited to @code{MAX_FIXED_MODE_SIZE}, but the\n\
3718	@code{TARGET_ARRAY_MODE_SUPPORTED_P} hook allows a larger mode to be\n\
3719	used in specific cases.\n\
3720	\n\
3721	The main use of this hook is to specify that an array of vectors should\n\
3722	also have a vector mode. The default implementation returns no mode.",
3723	opt_machine_mode, (machine_mode mode, unsigned HOST_WIDE_INT nelems),
3724	hook_optmode_mode_uhwi_none)
3725
3726	/* True if we should try to use a scalar mode to represent an array,
3727	overriding the usual MAX_FIXED_MODE limit. */
3728	DEFHOOK
3729	(array_mode_supported_p,
3730	"Return true if GCC should try to use a scalar mode to store an array\n\
3731	of @var{nelems} elements, given that each element has mode @var{mode}.\n\
3732	Returning true here overrides the usual @code{MAX_FIXED_MODE} limit\n\
3733	and allows GCC to use any defined integer mode.\n\
3734	\n\
3735	One use of this hook is to support vector load and store operations\n\
3736	that operate on several homogeneous vectors. For example, ARM NEON\n\
3737	has operations like:\n\
3738	\n\
3739	@smallexample\n\
3740	int8x8x3_t vld3_s8 (const int8_t *)\n\
3741	@end smallexample\n\
3742	\n\
3743	where the return type is defined as:\n\
3744	\n\
3745	@smallexample\n\
3746	typedef struct int8x8x3_t\n\
3747	@{\n\
3748	int8x8_t val[3];\n\
3749	@} int8x8x3_t;\n\
3750	@end smallexample\n\
3751	\n\
3752	If this hook allows @code{val} to have a scalar mode, then\n\
3753	@code{int8x8x3_t} can have the same mode. GCC can then store\n\
3754	@code{int8x8x3_t}s in registers rather than forcing them onto the stack.",
3755	bool, (machine_mode mode, unsigned HOST_WIDE_INT nelems),
3756	hook_bool_mode_uhwi_false)
3757
3758	DEFHOOK
3759	(libgcc_floating_mode_supported_p,
3760	"Define this to return nonzero if libgcc provides support for the \n\
3761	floating-point mode @var{mode}, which is known to pass \n\
3762	@code{TARGET_SCALAR_MODE_SUPPORTED_P}. The default version of this \n\
3763	hook returns true for all of @code{SFmode}, @code{DFmode}, \n\
3764	@code{XFmode} and @code{TFmode}, if such modes exist.",
3765	bool, (scalar_float_mode mode),
3766	default_libgcc_floating_mode_supported_p)
3767
3768	DEFHOOK
3769	(floatn_mode,
3770	"Define this to return the machine mode to use for the type \n\
3771	@code{_Float@var{n}}, if @var{extended} is false, or the type \n\
3772	@code{_Float@var{n}x}, if @var{extended} is true. If such a type is not\n\
3773	supported, return @code{opt_scalar_float_mode ()}. The default version of\n\
3774	this hook returns @code{SFmode} for @code{_Float32}, @code{DFmode} for\n\
3775	@code{_Float64} and @code{_Float32x} and @code{TFmode} for \n\
3776	@code{_Float128}, if those modes exist and satisfy the requirements for \n\
3777	those types and pass @code{TARGET_SCALAR_MODE_SUPPORTED_P} and \n\
3778	@code{TARGET_LIBGCC_FLOATING_MODE_SUPPORTED_P}; for @code{_Float64x}, it \n\
3779	returns the first of @code{XFmode} and @code{TFmode} that exists and \n\
3780	satisfies the same requirements; for other types, it returns \n\
3781	@code{opt_scalar_float_mode ()}. The hook is only called for values\n\
3782	of @var{n} and @var{extended} that are valid according to\n\
3783	ISO/IEC TS 18661-3:2015; that is, @var{n} is one of 32, 64, 128, or,\n\
3784	if @var{extended} is false, 16 or greater than 128 and a multiple of 32.",
3785	opt_scalar_float_mode, (int n, bool extended),
3786	default_floatn_mode)
3787
3788	DEFHOOK
3789	(floatn_builtin_p,
3790	"Define this to return true if the @code{_Float@var{n}} and\n\
3791	@code{_Float@var{n}x} built-in functions should implicitly enable the\n\
3792	built-in function without the @code{__builtin_} prefix in addition to the\n\
3793	normal built-in function with the @code{__builtin_} prefix. The default is\n\
3794	to only enable built-in functions without the @code{__builtin_} prefix for\n\
3795	the GNU C langauge. In strict ANSI/ISO mode, the built-in function without\n\
3796	the @code{__builtin_} prefix is not enabled. The argument @code{FUNC} is the\n\
3797	@code{enum built_in_function} id of the function to be enabled.",
3798	bool, (int func),
3799	default_floatn_builtin_p)
3800
3801	/* Compute cost of moving data from a register of class FROM to one of
3802	TO, using MODE. */
3803	DEFHOOK
3804	(register_move_cost,
3805	"This target hook should return the cost of moving data of mode @var{mode}\n\
3806	from a register in class @var{from} to one in class @var{to}. The classes\n\
3807	are expressed using the enumeration values such as @code{GENERAL_REGS}.\n\
3808	A value of 2 is the default; other values are interpreted relative to\n\
3809	that.\n\
3810	\n\
3811	It is not required that the cost always equal 2 when @var{from} is the\n\
3812	same as @var{to}; on some machines it is expensive to move between\n\
3813	registers if they are not general registers.\n\
3814	\n\
3815	If reload sees an insn consisting of a single @code{set} between two\n\
3816	hard registers, and if @code{TARGET_REGISTER_MOVE_COST} applied to their\n\
3817	classes returns a value of 2, reload does not check to ensure that the\n\
3818	constraints of the insn are met. Setting a cost of other than 2 will\n\
3819	allow reload to verify that the constraints are met. You should do this\n\
3820	if the @samp{mov@var{m}} pattern's constraints do not allow such copying.\n\
3821	\n\
3822	The default version of this function returns 2.",
3823	int, (machine_mode mode, reg_class_t from, reg_class_t to),
3824	default_register_move_cost)
3825
3826	/* Compute cost of moving registers to/from memory. */
3827	/* ??? Documenting the argument types for this hook requires a GFDL
3828	license grant. Also, the documentation uses a different name for RCLASS. */
3829	DEFHOOK
3830	(memory_move_cost,
3831	"This target hook should return the cost of moving data of mode @var{mode}\n\
3832	between a register of class @var{rclass} and memory; @var{in} is @code{false}\n\
3833	if the value is to be written to memory, @code{true} if it is to be read in.\n\
3834	This cost is relative to those in @code{TARGET_REGISTER_MOVE_COST}.\n\
3835	If moving between registers and memory is more expensive than between two\n\
3836	registers, you should add this target hook to express the relative cost.\n\
3837	\n\
3838	If you do not add this target hook, GCC uses a default cost of 4 plus\n\
3839	the cost of copying via a secondary reload register, if one is\n\
3840	needed. If your machine requires a secondary reload register to copy\n\
3841	between memory and a register of @var{rclass} but the reload mechanism is\n\
3842	more complex than copying via an intermediate, use this target hook to\n\
3843	reflect the actual cost of the move.\n\
3844	\n\
3845	GCC defines the function @code{memory_move_secondary_cost} if\n\
3846	secondary reloads are needed. It computes the costs due to copying via\n\
3847	a secondary register. If your machine copies from memory using a\n\
3848	secondary register in the conventional way but the default base value of\n\
3849	4 is not correct for your machine, use this target hook to add some other\n\
3850	value to the result of that function. The arguments to that function\n\
3851	are the same as to this target hook.",
3852	int, (machine_mode mode, reg_class_t rclass, bool in),
3853	default_memory_move_cost)
3854
3855	DEFHOOK
3856	(callee_save_cost,
3857	"Return the one-off cost of saving or restoring callee-saved registers\n\
3858	(also known as call-preserved registers or non-volatile registers).\n\
3859	The parameters are as follows:\n\
3860	\n\
3861	@itemize\n\
3862	@item\n\
3863	@var{cost_type} is @samp{spill_cost_type::SAVE} for saving a register\n\
3864	and @samp{spill_cost_type::RESTORE} for restoring a register.\n\
3865	\n\
3866	@item\n\
3867	@var{hard_regno} and @var{mode} represent the whole register that\n\
3868	the register allocator is considering using; of these,\n\
3869	@var{nregs} registers are fully or partially callee-saved.\n\
3870	\n\
3871	@item\n\
3872	@var{mem_cost} is the normal cost for storing (for saves)\n\
3873	or loading (for restores) the @var{nregs} registers.\n\
3874	\n\
3875	@item\n\
3876	@var{allocated_callee_regs} is the set of callee-saved registers\n\
3877	that are already in use.\n\
3878	\n\
3879	@item\n\
3880	@var{existing_spills_p} is true if the register allocator has\n\
3881	already decided to spill registers to memory.\n\
3882	@end itemize\n\
3883	\n\
3884	If @var{existing_spills_p} is false, the cost of a save should account\n\
3885	for frame allocations in a way that is consistent with\n\
3886	@code{TARGET_FRAME_ALLOCATION_COST}'s handling of allocations for spills.\n\
3887	Similarly, the cost of a restore should then account for frame deallocations\n\
3888	in a way that is consistent with @code{TARGET_FRAME_ALLOCATION_COST}'s\n\
3889	handling of deallocations.\n\
3890	\n\
3891	Note that this hook should not attempt to apply a frequency scale\n\
3892	to the cost: it is the caller's responsibility to do that where\n\
3893	appropriate.\n\
3894	\n\
3895	The default implementation returns @var{mem_cost}, plus the allocation\n\
3896	or deallocation cost returned by @code{TARGET_FRAME_ALLOCATION_COST},\n\
3897	where appropriate.",
3898	int, (spill_cost_type cost_type, unsigned int hard_regno,
3899	machine_mode mode, unsigned int nregs, int mem_cost,
3900	const HARD_REG_SET &allocated_callee_regs, bool existing_spills_p),
3901	default_callee_save_cost)
3902
3903	DEFHOOK
3904	(frame_allocation_cost,
3905	"Return the cost of allocating or deallocating a frame for the sake of\n\
3906	a spill; @var{cost_type} chooses between allocation and deallocation.\n\
3907	The term ``spill'' here includes both forcing a pseudo register to memory\n\
3908	and using caller-saved registers for pseudo registers that are live across\n\
3909	a call.\n\
3910	\n\
3911	This hook is only called if the register allocator has not so far\n\
3912	decided to spill. The allocator may have decided to use callee-saved\n\
3913	registers; if so, @var{allocated_callee_regs} is the set of callee-saved\n\
3914	registers that the allocator has used. There might also be other reasons\n\
3915	why a stack frame is already needed; for example, @samp{get_frame_size ()}\n\
3916	might be nonzero, or the target might already require a frame for\n\
3917	target-specific reasons.\n\
3918	\n\
3919	When the register allocator uses this hook to cost spills, it also uses\n\
3920	@code{TARGET_CALLEE_SAVE_COST} to cost new callee-saved registers, passing\n\
3921	@samp{false} as the @var{existing_spills_p} argument. The intention is to\n\
3922	allow the target to apply an apples-for-apples comparison between the\n\
3923	cost of using callee-saved registers and using spills in cases where the\n\
3924	allocator has not yet committed to using both strategies.\n\
3925	\n\
3926	The default implementation returns 0.",
3927	int, (frame_cost_type cost_type, const HARD_REG_SET &allocated_callee_regs),
3928	default_frame_allocation_cost)
3929
3930	DEFHOOK
3931	(use_by_pieces_infrastructure_p,
3932	"GCC will attempt several strategies when asked to copy between\n\
3933	two areas of memory, or to set, clear or store to memory, for example\n\
3934	when copying a @code{struct}. The @code{by_pieces} infrastructure\n\
3935	implements such memory operations as a sequence of load, store or move\n\
3936	insns. Alternate strategies are to expand the\n\
3937	@code{cpymem} or @code{setmem} optabs, to emit a library call, or to emit\n\
3938	unit-by-unit, loop-based operations.\n\
3939	\n\
3940	This target hook should return true if, for a memory operation with a\n\
3941	given @var{size} and @var{alignment}, using the @code{by_pieces}\n\
3942	infrastructure is expected to result in better code generation.\n\
3943	Both @var{size} and @var{alignment} are measured in terms of storage\n\
3944	units.\n\
3945	\n\
3946	The parameter @var{op} is one of: @code{CLEAR_BY_PIECES},\n\
3947	@code{MOVE_BY_PIECES}, @code{SET_BY_PIECES}, @code{STORE_BY_PIECES} or\n\
3948	@code{COMPARE_BY_PIECES}. These describe the type of memory operation\n\
3949	under consideration.\n\
3950	\n\
3951	The parameter @var{speed_p} is true if the code is currently being\n\
3952	optimized for speed rather than size.\n\
3953	\n\
3954	Returning true for higher values of @var{size} can improve code generation\n\
3955	for speed if the target does not provide an implementation of the\n\
3956	@code{cpymem} or @code{setmem} standard names, if the @code{cpymem} or\n\
3957	@code{setmem} implementation would be more expensive than a sequence of\n\
3958	insns, or if the overhead of a library call would dominate that of\n\
3959	the body of the memory operation.\n\
3960	\n\
3961	Returning true for higher values of @code{size} may also cause an increase\n\
3962	in code size, for example where the number of insns emitted to perform a\n\
3963	move would be greater than that of a library call.",
3964	bool, (unsigned HOST_WIDE_INT size, unsigned int alignment,
3965	enum by_pieces_operation op, bool speed_p),
3966	default_use_by_pieces_infrastructure_p)
3967
3968	DEFHOOK
3969	(overlap_op_by_pieces_p,
3970	"This target hook should return true if when the @code{by_pieces}\n\
3971	infrastructure is used, an offset adjusted unaligned memory operation\n\
3972	in the smallest integer mode for the last piece operation of a memory\n\
3973	region can be generated to avoid doing more than one smaller operations.",
3974	bool, (void),
3975	hook_bool_void_false)
3976
3977	DEFHOOK
3978	(compare_by_pieces_branch_ratio,
3979	"When expanding a block comparison in MODE, gcc can try to reduce the\n\
3980	number of branches at the expense of more memory operations. This hook\n\
3981	allows the target to override the default choice. It should return the\n\
3982	factor by which branches should be reduced over the plain expansion with\n\
3983	one comparison per @var{mode}-sized piece. A port can also prevent a\n\
3984	particular mode from being used for block comparisons by returning a\n\
3985	negative number from this hook.",
3986	int, (machine_mode mode),
3987	default_compare_by_pieces_branch_ratio)
3988
3989	DEFHOOK
3990	(slow_unaligned_access,
3991	"This hook returns true if memory accesses described by the\n\
3992	@var{mode} and @var{alignment} parameters have a cost many times greater\n\
3993	than aligned accesses, for example if they are emulated in a trap handler.\n\
3994	This hook is invoked only for unaligned accesses, i.e.@: when\n\
3995	@code{@var{alignment} < GET_MODE_ALIGNMENT (@var{mode})}.\n\
3996	\n\
3997	When this hook returns true, the compiler will act as if\n\
3998	@code{STRICT_ALIGNMENT} were true when generating code for block\n\
3999	moves. This can cause significantly more instructions to be produced.\n\
4000	Therefore, do not make this hook return true if unaligned accesses only\n\
4001	add a cycle or two to the time for a memory access.\n\
4002	\n\
4003	The hook must return true whenever @code{STRICT_ALIGNMENT} is true.\n\
4004	The default implementation returns @code{STRICT_ALIGNMENT}.",
4005	bool, (machine_mode mode, unsigned int align),
4006	default_slow_unaligned_access)
4007
4008	DEFHOOK
4009	(optab_supported_p,
4010	"Return true if the optimizers should use optab @var{op} with\n\
4011	modes @var{mode1} and @var{mode2} for optimization type @var{opt_type}.\n\
4012	The optab is known to have an associated @file{.md} instruction\n\
4013	whose C condition is true. @var{mode2} is only meaningful for conversion\n\
4014	optabs; for direct optabs it is a copy of @var{mode1}.\n\
4015	\n\
4016	For example, when called with @var{op} equal to @code{rint_optab} and\n\
4017	@var{mode1} equal to @code{DFmode}, the hook should say whether the\n\
4018	optimizers should use optab @code{rintdf2}.\n\
4019	\n\
4020	The default hook returns true for all inputs.",
4021	bool, (int op, machine_mode mode1, machine_mode mode2,
4022	optimization_type opt_type),
4023	default_optab_supported_p)
4024
4025	/* True for MODE if the target expects that registers in this mode will
4026	be allocated to registers in a small register class. The compiler is
4027	allowed to use registers explicitly used in the rtl as spill registers
4028	but it should prevent extending the lifetime of these registers. */
4029	DEFHOOK
4030	(small_register_classes_for_mode_p,
4031	"Define this to return nonzero for machine modes for which the port has\n\
4032	small register classes. If this target hook returns nonzero for a given\n\
4033	@var{mode}, the compiler will try to minimize the lifetime of registers\n\
4034	in @var{mode}. The hook may be called with @code{VOIDmode} as argument.\n\
4035	In this case, the hook is expected to return nonzero if it returns nonzero\n\
4036	for any mode.\n\
4037	\n\
4038	On some machines, it is risky to let hard registers live across arbitrary\n\
4039	insns. Typically, these machines have instructions that require values\n\
4040	to be in specific registers (like an accumulator), and reload will fail\n\
4041	if the required hard register is used for another purpose across such an\n\
4042	insn.\n\
4043	\n\
4044	Passes before reload do not know which hard registers will be used\n\
4045	in an instruction, but the machine modes of the registers set or used in\n\
4046	the instruction are already known. And for some machines, register\n\
4047	classes are small for, say, integer registers but not for floating point\n\
4048	registers. For example, the AMD x86-64 architecture requires specific\n\
4049	registers for the legacy x86 integer instructions, but there are many\n\
4050	SSE registers for floating point operations. On such targets, a good\n\
4051	strategy may be to return nonzero from this hook for @code{INTEGRAL_MODE_P}\n\
4052	machine modes but zero for the SSE register classes.\n\
4053	\n\
4054	The default version of this hook returns false for any mode. It is always\n\
4055	safe to redefine this hook to return with a nonzero value. But if you\n\
4056	unnecessarily define it, you will reduce the amount of optimizations\n\
4057	that can be performed in some cases. If you do not define this hook\n\
4058	to return a nonzero value when it is required, the compiler will run out\n\
4059	of spill registers and print a fatal error message.",
4060	bool, (machine_mode mode),
4061	hook_bool_mode_false)
4062
4063	/* Register number for a flags register. Only needs to be defined if the
4064	target is constrainted to use post-reload comparison elimination. */
4065	DEFHOOKPOD
4066	(flags_regnum,
4067	"If the target has a dedicated flags register, and it needs to use the\n\
4068	post-reload comparison elimination pass, or the delay slot filler pass,\n\
4069	then this value should be set appropriately.",
4070	unsigned int, INVALID_REGNUM)
4071
4072	/* Compute a (partial) cost for rtx X. Return true if the complete
4073	cost has been computed, and false if subexpressions should be
4074	scanned. In either case, *TOTAL contains the cost result. */
4075	/* Note that OUTER_CODE ought to be RTX_CODE, but that's
4076	not necessarily defined at this point. */
4077	DEFHOOK
4078	(rtx_costs,
4079	"This target hook describes the relative costs of RTL expressions.\n\
4080	\n\
4081	The cost may depend on the precise form of the expression, which is\n\
4082	available for examination in @var{x}, and the fact that @var{x} appears\n\
4083	as operand @var{opno} of an expression with rtx code @var{outer_code}.\n\
4084	That is, the hook can assume that there is some rtx @var{y} such\n\
4085	that @samp{GET_CODE (@var{y}) == @var{outer_code}} and such that\n\
4086	either (a) @samp{XEXP (@var{y}, @var{opno}) == @var{x}} or\n\
4087	(b) @samp{XVEC (@var{y}, @var{opno})} contains @var{x}.\n\
4088	\n\
4089	@var{mode} is @var{x}'s machine mode, or for cases like @code{const_int} that\n\
4090	do not have a mode, the mode in which @var{x} is used.\n\
4091	\n\
4092	In implementing this hook, you can use the construct\n\
4093	@code{COSTS_N_INSNS (@var{n})} to specify a cost equal to @var{n} fast\n\
4094	instructions.\n\
4095	\n\
4096	On entry to the hook, @code{*@var{total}} contains a default estimate\n\
4097	for the cost of the expression. The hook should modify this value as\n\
4098	necessary. Traditionally, the default costs are @code{COSTS_N_INSNS (5)}\n\
4099	for multiplications, @code{COSTS_N_INSNS (7)} for division and modulus\n\
4100	operations, and @code{COSTS_N_INSNS (1)} for all other operations.\n\
4101	\n\
4102	When optimizing for code size, i.e.@: when @code{speed} is\n\
4103	false, this target hook should be used to estimate the relative\n\
4104	size cost of an expression, again relative to @code{COSTS_N_INSNS}.\n\
4105	\n\
4106	The hook returns true when all subexpressions of @var{x} have been\n\
4107	processed, and false when @code{rtx_cost} should recurse.",
4108	bool, (rtx x, machine_mode mode, int outer_code, int opno, int *total, bool speed),
4109	hook_bool_rtx_mode_int_int_intp_bool_false)
4110
4111	/* Compute the cost of X, used as an address. Never called with
4112	invalid addresses. */
4113	DEFHOOK
4114	(address_cost,
4115	"This hook computes the cost of an addressing mode that contains\n\
4116	@var{address}. If not defined, the cost is computed from\n\
4117	the @var{address} expression and the @code{TARGET_RTX_COST} hook.\n\
4118	\n\
4119	For most CISC machines, the default cost is a good approximation of the\n\
4120	true cost of the addressing mode. However, on RISC machines, all\n\
4121	instructions normally have the same length and execution time. Hence\n\
4122	all addresses will have equal costs.\n\
4123	\n\
4124	In cases where more than one form of an address is known, the form with\n\
4125	the lowest cost will be used. If multiple forms have the same, lowest,\n\
4126	cost, the one that is the most complex will be used.\n\
4127	\n\
4128	For example, suppose an address that is equal to the sum of a register\n\
4129	and a constant is used twice in the same basic block. When this macro\n\
4130	is not defined, the address will be computed in a register and memory\n\
4131	references will be indirect through that register. On machines where\n\
4132	the cost of the addressing mode containing the sum is no higher than\n\
4133	that of a simple indirect reference, this will produce an additional\n\
4134	instruction and possibly require an additional register. Proper\n\
4135	specification of this macro eliminates this overhead for such machines.\n\
4136	\n\
4137	This hook is never called with an invalid address.\n\
4138	\n\
4139	On machines where an address involving more than one register is as\n\
4140	cheap as an address computation involving only one register, defining\n\
4141	@code{TARGET_ADDRESS_COST} to reflect this can cause two registers to\n\
4142	be live over a region of code where only one would have been if\n\
4143	@code{TARGET_ADDRESS_COST} were not defined in that manner. This effect\n\
4144	should be considered in the definition of this macro. Equivalent costs\n\
4145	should probably only be given to addresses with different numbers of\n\
4146	registers on machines with lots of registers.",
4147	int, (rtx address, machine_mode mode, addr_space_t as, bool speed),
4148	default_address_cost)
4149
4150	/* Compute a cost for INSN. */
4151	DEFHOOK
4152	(insn_cost,
4153	"This target hook describes the relative costs of RTL instructions.\n\
4154	\n\
4155	In implementing this hook, you can use the construct\n\
4156	@code{COSTS_N_INSNS (@var{n})} to specify a cost equal to @var{n} fast\n\
4157	instructions.\n\
4158	\n\
4159	When optimizing for code size, i.e.@: when @code{speed} is\n\
4160	false, this target hook should be used to estimate the relative\n\
4161	size cost of an expression, again relative to @code{COSTS_N_INSNS}.",
4162	int, (rtx_insn *insn, bool speed), NULL)
4163
4164	/* Give a cost, in RTX Costs units, for an edge. Like BRANCH_COST, but with
4165	well defined units. */
4166	DEFHOOK
4167	(max_noce_ifcvt_seq_cost,
4168	"This hook returns a value in the same units as @code{TARGET_RTX_COSTS},\n\
4169	giving the maximum acceptable cost for a sequence generated by the RTL\n\
4170	if-conversion pass when conditional execution is not available.\n\
4171	The RTL if-conversion pass attempts to convert conditional operations\n\
4172	that would require a branch to a series of unconditional operations and\n\
4173	@code{mov@var{mode}cc} insns. This hook returns the maximum cost of the\n\
4174	unconditional instructions and the @code{mov@var{mode}cc} insns.\n\
4175	RTL if-conversion is cancelled if the cost of the converted sequence\n\
4176	is greater than the value returned by this hook.\n\
4177	\n\
4178	@code{e} is the edge between the basic block containing the conditional\n\
4179	branch to the basic block which would be executed if the condition\n\
4180	were true.\n\
4181	\n\
4182	The default implementation of this hook uses the\n\
4183	@code{max-rtl-if-conversion-[un]predictable} parameters if they are set,\n\
4184	and uses a multiple of @code{BRANCH_COST} otherwise.",
4185	unsigned int, (edge e),
4186	default_max_noce_ifcvt_seq_cost)
4187
4188	/* Return true if the given instruction sequence is a good candidate
4189	as a replacement for the if-convertible sequence. */
4190	DEFHOOK
4191	(noce_conversion_profitable_p,
4192	"This hook returns true if the instruction sequence @code{seq} is a good\n\
4193	candidate as a replacement for the if-convertible sequence described in\n\
4194	@code{if_info}.",
4195	bool, (rtx_insn *seq, struct noce_if_info *if_info),
4196	default_noce_conversion_profitable_p)
4197
4198	/* Return true if new_addr should be preferred over the existing address used by
4199	memref in insn. */
4200	DEFHOOK
4201	(new_address_profitable_p,
4202	"Return @code{true} if it is profitable to replace the address in\n\
4203	@var{memref} with @var{new_addr}. This allows targets to prevent the\n\
4204	scheduler from undoing address optimizations. The instruction containing the\n\
4205	memref is @var{insn}. The default implementation returns @code{true}.",
4206	bool, (rtx memref, rtx_insn * insn, rtx new_addr),
4207	default_new_address_profitable_p)
4208
4209	DEFHOOK
4210	(estimated_poly_value,
4211	"Return an estimate of the runtime value of @var{val}, for use in\n\
4212	things like cost calculations or profiling frequencies. @var{kind} is used\n\
4213	to ask for the minimum, maximum, and likely estimates of the value through\n\
4214	the @code{POLY_VALUE_MIN}, @code{POLY_VALUE_MAX} and\n\
4215	@code{POLY_VALUE_LIKELY} values. The default\n\
4216	implementation returns the lowest possible value of @var{val}.",
4217	HOST_WIDE_INT, (poly_int64 val, poly_value_estimate_kind kind),
4218	default_estimated_poly_value)
4219
4220	/* Permit speculative instructions in delay slots during delayed-branch
4221	scheduling. */
4222	DEFHOOK
4223	(no_speculation_in_delay_slots_p,
4224	"This predicate controls the use of the eager delay slot filler to disallow\n\
4225	speculatively executed instructions being placed in delay slots. Targets\n\
4226	such as certain MIPS architectures possess both branches with and without\n\
4227	delay slots. As the eager delay slot filler can decrease performance,\n\
4228	disabling it is beneficial when ordinary branches are available. Use of\n\
4229	delay slot branches filled using the basic filler is often still desirable\n\
4230	as the delay slot can hide a pipeline bubble.",
4231	bool, (void),
4232	hook_bool_void_false)
4233
4234	/* Return where to allocate pseudo for a given hard register initial value. */
4235	DEFHOOK
4236	(allocate_initial_value,
4237	"\n\
4238	When the initial value of a hard register has been copied in a pseudo\n\
4239	register, it is often not necessary to actually allocate another register\n\
4240	to this pseudo register, because the original hard register or a stack slot\n\
4241	it has been saved into can be used. @code{TARGET_ALLOCATE_INITIAL_VALUE}\n\
4242	is called at the start of register allocation once for each hard register\n\
4243	that had its initial value copied by using\n\
4244	@code{get_func_hard_reg_initial_val} or @code{get_hard_reg_initial_val}.\n\
4245	Possible values are @code{NULL_RTX}, if you don't want\n\
4246	to do any special allocation, a @code{REG} rtx---that would typically be\n\
4247	the hard register itself, if it is known not to be clobbered---or a\n\
4248	@code{MEM}.\n\
4249	If you are returning a @code{MEM}, this is only a hint for the allocator;\n\
4250	it might decide to use another register anyways.\n\
4251	You may use @code{current_function_is_leaf} or \n\
4252	@code{REG_N_SETS} in the hook to determine if the hard\n\
4253	register in question will not be clobbered.\n\
4254	The default value of this hook is @code{NULL}, which disables any special\n\
4255	allocation.",
4256	rtx, (rtx hard_reg), NULL)
4257
4258	/* Return nonzero if evaluating UNSPEC X might cause a trap.
4259	FLAGS has the same meaning as in rtlanal.cc: may_trap_p_1. */
4260	DEFHOOK
4261	(unspec_may_trap_p,
4262	"This target hook returns nonzero if @var{x}, an @code{unspec} might cause\n\
4263	a trap. Targets can use this hook to enhance precision of analysis for\n\
4264	@code{unspec} operations. You may call @code{may_trap_p_1} to analyze inner\n\
4265	elements of @var{x} in which case @var{flags} should be passed along.",
4266	int, (const_rtx x, unsigned flags),
4267	default_unspec_may_trap_p)
4268
4269	/* Given a register, this hook should return a parallel of registers
4270	to represent where to find the register pieces. Define this hook
4271	if the register and its mode are represented in Dwarf in
4272	non-contiguous locations, or if the register should be
4273	represented in more than one register in Dwarf. Otherwise, this
4274	hook should return NULL_RTX. */
4275	DEFHOOK
4276	(dwarf_register_span,
4277	"Given a register, this hook should return a parallel of registers to\n\
4278	represent where to find the register pieces. Define this hook if the\n\
4279	register and its mode are represented in Dwarf in non-contiguous\n\
4280	locations, or if the register should be represented in more than one\n\
4281	register in Dwarf. Otherwise, this hook should return @code{NULL_RTX}.\n\
4282	If not defined, the default is to return @code{NULL_RTX}.",
4283	rtx, (rtx reg),
4284	hook_rtx_rtx_null)
4285
4286	/* Given a register return the mode of the corresponding DWARF frame
4287	register. */
4288	DEFHOOK
4289	(dwarf_frame_reg_mode,
4290	"Given a register, this hook should return the mode which the\n\
4291	corresponding Dwarf frame register should have. This is normally\n\
4292	used to return a smaller mode than the raw mode to prevent call\n\
4293	clobbered parts of a register altering the frame register size",
4294	machine_mode, (int regno),
4295	default_dwarf_frame_reg_mode)
4296
4297	/* Print out architecture-specific CFI directives to the assembly file. */
4298	DEFHOOK
4299	(output_cfi_directive,
4300	"This hook handles architecture-specific CFI directives and prints\n\
4301	them out to the assembly file @var{f}.\n\
4302	Return true if a architecture-specific directive was found, false\n\
4303	otherwise.",
4304	bool, (FILE * f, dw_cfi_ref cfi),
4305	hook_bool_FILEptr_dwcfiptr_false)
4306
4307	DEFHOOK
4308	(dw_cfi_oprnd1_desc,
4309	"This hook informs the caller what the architecture-specific directives\n\
4310	takes as a first operand.\n\
4311	Return true if a architecture-specific directive was found and\n\
4312	@var{oprnd_type} is set, false otherwise and @var{oprnd_type} is not\n\
4313	modified.",
4314	bool, (dwarf_call_frame_info cfi_opc, dw_cfi_oprnd_type & oprnd_type),
4315	hook_bool_dwcfi_dwcfioprndtyperef_false)
4316
4317	/* If expand_builtin_init_dwarf_reg_sizes needs to fill in table
4318	entries not corresponding directly to registers below
4319	FIRST_PSEUDO_REGISTER, this hook should generate the necessary
4320	code, given the address of the table. */
4321	DEFHOOK
4322	(init_dwarf_reg_sizes_extra,
4323	"If some registers are represented in Dwarf-2 unwind information in\n\
4324	multiple pieces, define this hook to fill in information about the\n\
4325	sizes of those pieces in the table used by the unwinder at runtime.\n\
4326	It will be called by @code{expand_builtin_init_dwarf_reg_sizes} after\n\
4327	filling in a single size corresponding to each hard register;\n\
4328	@var{address} is the address of the table.",
4329	void, (tree address),
4330	hook_void_tree)
4331
4332	/* Fetch the fixed register(s) which hold condition codes, for
4333	targets where it makes sense to look for duplicate assignments to
4334	the condition codes. This should return true if there is such a
4335	register, false otherwise. The arguments should be set to the
4336	fixed register numbers. Up to two condition code registers are
4337	supported. If there is only one for this target, the int pointed
4338	at by the second argument should be set to -1. */
4339	DEFHOOK
4340	(fixed_condition_code_regs,
4341	"On targets which use a hard\n\
4342	register rather than a pseudo-register to hold condition codes, the\n\
4343	regular CSE passes are often not able to identify cases in which the\n\
4344	hard register is set to a common value. Use this hook to enable a\n\
4345	small pass which optimizes such cases. This hook should return true\n\
4346	to enable this pass, and it should set the integers to which its\n\
4347	arguments point to the hard register numbers used for condition codes.\n\
4348	When there is only one such register, as is true on most systems, the\n\
4349	integer pointed to by @var{p2} should be set to\n\
4350	@code{INVALID_REGNUM}.\n\
4351	\n\
4352	The default version of this hook returns false.",
4353	bool, (unsigned int *p1, unsigned int *p2),
4354	hook_bool_uintp_uintp_false)
4355
4356	/* If two condition code modes are compatible, return a condition
4357	code mode which is compatible with both, such that a comparison
4358	done in the returned mode will work for both of the original
4359	modes. If the condition code modes are not compatible, return
4360	VOIDmode. */
4361	DEFHOOK
4362	(cc_modes_compatible,
4363	"On targets which use multiple condition code modes in class\n\
4364	@code{MODE_CC}, it is sometimes the case that a comparison can be\n\
4365	validly done in more than one mode. On such a system, define this\n\
4366	target hook to take two mode arguments and to return a mode in which\n\
4367	both comparisons may be validly done. If there is no such mode,\n\
4368	return @code{VOIDmode}.\n\
4369	\n\
4370	The default version of this hook checks whether the modes are the\n\
4371	same. If they are, it returns that mode. If they are different, it\n\
4372	returns @code{VOIDmode}.",
4373	machine_mode, (machine_mode m1, machine_mode m2),
4374	default_cc_modes_compatible)
4375
4376	DEFHOOK
4377	(use_late_prologue_epilogue,
4378	"Return true if the current function's prologue and epilogue should\n\
4379	be emitted late in the pass pipeline, instead of at the usual point.\n\
4380	\n\
4381	Normally, the prologue and epilogue sequences are introduced soon after\n\
4382	register allocation is complete. The advantage of this approach is that\n\
4383	it allows the prologue and epilogue instructions to be optimized and\n\
4384	scheduled with other code in the function. However, some targets\n\
4385	require the prologue and epilogue to be the first and last sequences\n\
4386	executed by the function, with no variation allowed. This hook should\n\
4387	return true on such targets.\n\
4388	\n\
4389	The default implementation returns false, which is correct for most\n\
4390	targets. The hook should only return true if there is a specific\n\
4391	target limitation that cannot be described in RTL. For example,\n\
4392	the hook might return true if the prologue and epilogue need to switch\n\
4393	between instruction sets.",
4394	bool, (),
4395	hook_bool_void_false)
4396
4397	DEFHOOK
4398	(emit_epilogue_for_sibcall,
4399	"If defined, this hook emits an epilogue sequence for sibling (tail)\n\
4400	call instruction @var{call}. Another way of providing epilogues\n\
4401	for sibling calls is to define the @code{sibcall_epilogue} instruction\n\
4402	pattern; the main advantage of this hook over the pattern is that it\n\
4403	has access to the call instruction.",
4404	void, (rtx_call_insn *call), NULL)
4405
4406	/* Do machine-dependent code transformations. Called just before
4407	delayed-branch scheduling. */
4408	DEFHOOK
4409	(machine_dependent_reorg,
4410	"If non-null, this hook performs a target-specific pass over the\n\
4411	instruction stream. The compiler will run it at all optimization levels,\n\
4412	just before the point at which it normally does delayed-branch scheduling.\n\
4413	\n\
4414	The exact purpose of the hook varies from target to target. Some use\n\
4415	it to do transformations that are necessary for correctness, such as\n\
4416	laying out in-function constant pools or avoiding hardware hazards.\n\
4417	Others use it as an opportunity to do some machine-dependent optimizations.\n\
4418	\n\
4419	You need not implement the hook if it has nothing to do. The default\n\
4420	definition is null.",
4421	void, (void), NULL)
4422
4423	/* Create the __builtin_va_list type. */
4424	DEFHOOK
4425	(build_builtin_va_list,
4426	"This hook returns a type node for @code{va_list} for the target.\n\
4427	The default version of the hook returns @code{void*}.",
4428	tree, (void),
4429	std_build_builtin_va_list)
4430
4431	/* Enumerate the va list variants. */
4432	DEFHOOK
4433	(enum_va_list_p,
4434	"This target hook is used in function @code{c_common_nodes_and_builtins}\n\
4435	to iterate through the target specific builtin types for va_list. The\n\
4436	variable @var{idx} is used as iterator. @var{pname} has to be a pointer\n\
4437	to a @code{const char *} and @var{ptree} a pointer to a @code{tree} typed\n\
4438	variable.\n\
4439	The arguments @var{pname} and @var{ptree} are used to store the result of\n\
4440	this macro and are set to the name of the va_list builtin type and its\n\
4441	internal type.\n\
4442	If the return value of this macro is zero, then there is no more element.\n\
4443	Otherwise the @var{IDX} should be increased for the next call of this\n\
4444	macro to iterate through all types.",
4445	int, (int idx, const char **pname, tree *ptree),
4446	NULL)
4447
4448	/* Get the cfun/fndecl calling abi __builtin_va_list type. */
4449	DEFHOOK
4450	(fn_abi_va_list,
4451	"This hook returns the va_list type of the calling convention specified by\n\
4452	@var{fndecl}.\n\
4453	The default version of this hook returns @code{va_list_type_node}.",
4454	tree, (tree fndecl),
4455	std_fn_abi_va_list)
4456
4457	/* Get the __builtin_va_list type dependent on input type. */
4458	DEFHOOK
4459	(canonical_va_list_type,
4460	"This hook returns the va_list type of the calling convention specified by the\n\
4461	type of @var{type}. If @var{type} is not a valid va_list type, it returns\n\
4462	@code{NULL_TREE}.",
4463	tree, (tree type),
4464	std_canonical_va_list_type)
4465
4466	/* ??? Documenting this hook requires a GFDL license grant. */
4467	DEFHOOK_UNDOC
4468	(expand_builtin_va_start,
4469	"Expand the @code{__builtin_va_start} builtin.",
4470	void, (tree valist, rtx nextarg), NULL)
4471
4472	/* Gimplifies a VA_ARG_EXPR. */
4473	DEFHOOK
4474	(gimplify_va_arg_expr,
4475	"This hook performs target-specific gimplification of\n\
4476	@code{VA_ARG_EXPR}. The first two parameters correspond to the\n\
4477	arguments to @code{va_arg}; the latter two are as in\n\
4478	@code{gimplify.cc:gimplify_expr}.",
4479	tree, (tree valist, tree type, gimple_seq *pre_p, gimple_seq *post_p),
4480	std_gimplify_va_arg_expr)
4481
4482	/* Validity-checking routines for PCH files, target-specific.
4483	get_pch_validity returns a pointer to the data to be stored,
4484	and stores the size in its argument. pch_valid_p gets the same
4485	information back and returns NULL if the PCH is valid,
4486	or an error message if not. */
4487	DEFHOOK
4488	(get_pch_validity,
4489	"This hook returns a pointer to the data needed by\n\
4490	@code{TARGET_PCH_VALID_P} and sets\n\
4491	@samp{*@var{sz}} to the size of the data in bytes.",
4492	void *, (size_t *sz),
4493	default_get_pch_validity)
4494
4495	DEFHOOK
4496	(pch_valid_p,
4497	"This hook checks whether the options used to create a PCH file are\n\
4498	compatible with the current settings. It returns @code{NULL}\n\
4499	if so and a suitable error message if not. Error messages will\n\
4500	be presented to the user and must be localized using @samp{_(@var{msg})}.\n\
4501	\n\
4502	@var{data} is the data that was returned by @code{TARGET_GET_PCH_VALIDITY}\n\
4503	when the PCH file was created and @var{sz} is the size of that data in bytes.\n\
4504	It's safe to assume that the data was created by the same version of the\n\
4505	compiler, so no format checking is needed.\n\
4506	\n\
4507	The default definition of @code{default_pch_valid_p} should be\n\
4508	suitable for most targets.",
4509	const char *, (const void *data, size_t sz),
4510	default_pch_valid_p)
4511
4512	DEFHOOK
4513	(prepare_pch_save,
4514	"Called before writing out a PCH file. If the target has some\n\
4515	garbage-collected data that needs to be in a particular state on PCH loads,\n\
4516	it can use this hook to enforce that state. Very few targets need\n\
4517	to do anything here.",
4518	void, (void),
4519	hook_void_void)
4520
4521	/* If nonnull, this function checks whether a PCH file with the
4522	given set of target flags can be used. It returns NULL if so,
4523	otherwise it returns an error message. */
4524	DEFHOOK
4525	(check_pch_target_flags,
4526	"If this hook is nonnull, the default implementation of\n\
4527	@code{TARGET_PCH_VALID_P} will use it to check for compatible values\n\
4528	of @code{target_flags}. @var{pch_flags} specifies the value that\n\
4529	@code{target_flags} had when the PCH file was created. The return\n\
4530	value is the same as for @code{TARGET_PCH_VALID_P}.",
4531	const char *, (int pch_flags), NULL)
4532
4533	/* True if the compiler should give an enum type only as many
4534	bytes as it takes to represent the range of possible values of
4535	that type. */
4536	DEFHOOK
4537	(default_short_enums,
4538	"This target hook should return true if the compiler should give an\n\
4539	@code{enum} type only as many bytes as it takes to represent the range\n\
4540	of possible values of that type. It should return false if all\n\
4541	@code{enum} types should be allocated like @code{int}.\n\
4542	\n\
4543	The default is to return false.",
4544	bool, (void),
4545	hook_bool_void_false)
4546
4547	/* This target hook returns an rtx that is used to store the address
4548	of the current frame into the built-in setjmp buffer. */
4549	DEFHOOK
4550	(builtin_setjmp_frame_value,
4551	"This target hook should return an rtx that is used to store\n\
4552	the address of the current frame into the built in @code{setjmp} buffer.\n\
4553	The default value, @code{virtual_stack_vars_rtx}, is correct for most\n\
4554	machines. One reason you may need to define this target hook is if\n\
4555	@code{hard_frame_pointer_rtx} is the appropriate value on your machine.",
4556	rtx, (void),
4557	default_builtin_setjmp_frame_value)
4558
4559	/* This target hook should manipulate the outputs, inputs, constraints,
4560	and clobbers the port wishes for pre-processing the asm. */
4561	DEFHOOK
4562	(md_asm_adjust,
4563	"This target hook may add @dfn{clobbers} to @var{clobbers} and\n\
4564	@var{clobbered_regs} for any hard regs the port wishes to automatically\n\
4565	clobber for an asm. It can also add hard registers that are used by the\n\
4566	asm to @var{uses}. The @var{outputs} and @var{inputs} may be inspected\n\
4567	to avoid clobbering a register that is already used by the asm. @var{loc}\n\
4568	is the source location of the asm.\n\
4569	\n\
4570	It may modify the @var{outputs}, @var{inputs}, @var{input_modes}, and\n\
4571	@var{constraints} as necessary for other pre-processing. In this case the\n\
4572	return value is a sequence of insns to emit after the asm. Note that\n\
4573	changes to @var{inputs} must be accompanied by the corresponding changes\n\
4574	to @var{input_modes}.",
4575	rtx_insn *,
4576	(vec<rtx>& outputs, vec<rtx>& inputs, vec<machine_mode>& input_modes,
4577	vec<const char *>& constraints, vec<rtx>& usess, vec<rtx>& clobbers,
4578	HARD_REG_SET& clobbered_regs, location_t loc),
4579	NULL)
4580
4581	/* This target hook allows the backend to specify a calling convention
4582	in the debug information. This function actually returns an
4583	enum dwarf_calling_convention, but because of forward declarations
4584	and not wanting to include dwarf2.h everywhere target.h is included
4585	the function is being declared as an int. */
4586	DEFHOOK
4587	(dwarf_calling_convention,
4588	"Define this to enable the dwarf attribute @code{DW_AT_calling_convention} to\n\
4589	be emitted for each function. Instead of an integer return the enum\n\
4590	value for the @code{DW_CC_} tag.",
4591	int, (const_tree function),
4592	hook_int_const_tree_0)
4593
4594	/* This target hook allows the backend to emit frame-related insns that
4595	contain UNSPECs or UNSPEC_VOLATILEs. The call frame debugging info
4596	engine will invoke it on insns of the form
4597	(set (reg) (unspec [...] UNSPEC_INDEX))
4598	and
4599	(set (reg) (unspec_volatile [...] UNSPECV_INDEX))
4600	to let the backend emit the call frame instructions. */
4601	DEFHOOK
4602	(dwarf_handle_frame_unspec,
4603	"This target hook allows the backend to emit frame-related insns that\n\
4604	contain UNSPECs or UNSPEC_VOLATILEs. The DWARF 2 call frame debugging\n\
4605	info engine will invoke it on insns of the form\n\
4606	@smallexample\n\
4607	(set (reg) (unspec [@dots{}] UNSPEC_INDEX))\n\
4608	@end smallexample\n\
4609	and\n\
4610	@smallexample\n\
4611	(set (reg) (unspec_volatile [@dots{}] UNSPECV_INDEX)).\n\
4612	@end smallexample\n\
4613	to let the backend emit the call frame instructions. @var{label} is\n\
4614	the CFI label attached to the insn, @var{pattern} is the pattern of\n\
4615	the insn and @var{index} is @code{UNSPEC_INDEX} or @code{UNSPECV_INDEX}.",
4616	void, (const char *label, rtx pattern, int index), NULL)
4617
4618	DEFHOOK
4619	(dwarf_poly_indeterminate_value,
4620	"Express the value of @code{poly_int} indeterminate @var{i} as a DWARF\n\
4621	expression, with @var{i} counting from 1. Return the number of a DWARF\n\
4622	register @var{R} and set @samp{*@var{factor}} and @samp{*@var{offset}} such\n\
4623	that the value of the indeterminate is:\n\
4624	@smallexample\n\
4625	value_of(@var{R}) / @var{factor} - @var{offset}\n\
4626	@end smallexample\n\
4627	\n\
4628	A target only needs to define this hook if it sets\n\
4629	@samp{NUM_POLY_INT_COEFFS} to a value greater than 1.",
4630	unsigned int, (unsigned int i, unsigned int *factor, int *offset),
4631	default_dwarf_poly_indeterminate_value)
4632
4633	/* ??? Documenting this hook requires a GFDL license grant. */
4634	DEFHOOK_UNDOC
4635	(stdarg_optimize_hook,
4636	"Perform architecture specific checking of statements gimplified\
4637	from @code{VA_ARG_EXPR}. @var{stmt} is the statement. Returns true if\
4638	the statement doesn't need to be checked for @code{va_list} references.",
4639	bool, (struct stdarg_info *ai, const gimple *stmt), NULL)
4640
4641	/* This target hook allows the operating system to override the DECL
4642	that represents the external variable that contains the stack
4643	protection guard variable. The type of this DECL is ptr_type_node. */
4644	DEFHOOK
4645	(stack_protect_guard,
4646	"This hook returns a @code{DECL} node for the external variable to use\n\
4647	for the stack protection guard. This variable is initialized by the\n\
4648	runtime to some random value and is used to initialize the guard value\n\
4649	that is placed at the top of the local stack frame. The type of this\n\
4650	variable must be @code{ptr_type_node}.\n\
4651	\n\
4652	The default version of this hook creates a variable called\n\
4653	@samp{__stack_chk_guard}, which is normally defined in @file{libgcc2.c}.",
4654	tree, (void),
4655	default_stack_protect_guard)
4656
4657	/* This target hook allows the operating system to override the CALL_EXPR
4658	that is invoked when a check vs the guard variable fails. */
4659	DEFHOOK
4660	(stack_protect_fail,
4661	"This hook returns a @code{CALL_EXPR} that alerts the runtime that the\n\
4662	stack protect guard variable has been modified. This expression should\n\
4663	involve a call to a @code{noreturn} function.\n\
4664	\n\
4665	The default version of this hook invokes a function called\n\
4666	@samp{__stack_chk_fail}, taking no arguments. This function is\n\
4667	normally defined in @file{libgcc2.c}.",
4668	tree, (void),
4669	default_external_stack_protect_fail)
4670
4671	/* This target hook allows the operating system to disable the default stack
4672	protector runtime support. */
4673	DEFHOOK
4674	(stack_protect_runtime_enabled_p,
4675	"Returns true if the target wants GCC's default stack protect runtime support,\n\
4676	otherwise return false. The default implementation always returns true.",
4677	bool, (void),
4678	hook_bool_void_true)
4679
4680	DEFHOOK
4681	(have_strub_support_for,
4682	"Returns true if the target supports stack scrubbing for the given function\n\
4683	or type, otherwise return false. The default implementation always returns\n\
4684	true.",
4685	bool, (tree),
4686	hook_bool_tree_true)
4687
4688	DEFHOOK
4689	(have_speculation_safe_value,
4690	"This hook is used to determine the level of target support for\n\
4691	@code{__builtin_speculation_safe_value}. If called with an argument\n\
4692	of false, it returns true if the target has been modified to support\n\
4693	this builtin. If called with an argument of true, it returns true\n\
4694	if the target requires active mitigation execution might be speculative.\n\
4695	\n\
4696	The default implementation returns false if the target does not define\n\
4697	a pattern named @code{speculation_barrier}. Else it returns true\n\
4698	for the first case and whether the pattern is enabled for the current\n\
4699	compilation for the second case.\n\
4700	\n\
4701	For targets that have no processors that can execute instructions\n\
4702	speculatively an alternative implemenation of this hook is available:\n\
4703	simply redefine this hook to @code{speculation_safe_value_not_needed}\n\
4704	along with your other target hooks.",
4705	bool, (bool active), default_have_speculation_safe_value)
4706
4707	DEFHOOK
4708	(speculation_safe_value,
4709	"This target hook can be used to generate a target-specific code\n\
4710	sequence that implements the @code{__builtin_speculation_safe_value}\n\
4711	built-in function. The function must always return @var{val} in\n\
4712	@var{result} in mode @var{mode} when the cpu is not executing\n\
4713	speculatively, but must never return that when speculating until it\n\
4714	is known that the speculation will not be unwound. The hook supports\n\
4715	two primary mechanisms for implementing the requirements. The first\n\
4716	is to emit a speculation barrier which forces the processor to wait\n\
4717	until all prior speculative operations have been resolved; the second\n\
4718	is to use a target-specific mechanism that can track the speculation\n\
4719	state and to return @var{failval} if it can determine that\n\
4720	speculation must be unwound at a later time.\n\
4721	\n\
4722	The default implementation simply copies @var{val} to @var{result} and\n\
4723	emits a @code{speculation_barrier} instruction if that is defined.",
4724	rtx, (machine_mode mode, rtx result, rtx val, rtx failval),
4725	default_speculation_safe_value)
4726
4727	DEFHOOK
4728	(predict_doloop_p,
4729	"Return true if we can predict it is possible to use a low-overhead loop\n\
4730	for a particular loop. The parameter @var{loop} is a pointer to the loop.\n\
4731	This target hook is required only when the target supports low-overhead\n\
4732	loops, and will help ivopts to make some decisions.\n\
4733	The default version of this hook returns false.",
4734	bool, (class loop *loop),
4735	default_predict_doloop_p)
4736
4737	DEFHOOKPOD
4738	(have_count_reg_decr_p,
4739	"Return true if the target supports hardware count register for decrement\n\
4740	and branch.\n\
4741	The default value is false.",
4742	bool, false)
4743
4744	DEFHOOKPOD
4745	(doloop_cost_for_generic,
4746	"One IV candidate dedicated for doloop is introduced in IVOPTs, we can\n\
4747	calculate the computation cost of adopting it to any generic IV use by\n\
4748	function get_computation_cost as before. But for targets which have\n\
4749	hardware count register support for decrement and branch, it may have to\n\
4750	move IV value from hardware count register to general purpose register\n\
4751	while doloop IV candidate is used for generic IV uses. It probably takes\n\
4752	expensive penalty. This hook allows target owners to define the cost for\n\
4753	this especially for generic IV uses.\n\
4754	The default value is zero.",
4755	int64_t, 0)
4756
4757	DEFHOOKPOD
4758	(doloop_cost_for_address,
4759	"One IV candidate dedicated for doloop is introduced in IVOPTs, we can\n\
4760	calculate the computation cost of adopting it to any address IV use by\n\
4761	function get_computation_cost as before. But for targets which have\n\
4762	hardware count register support for decrement and branch, it may have to\n\
4763	move IV value from hardware count register to general purpose register\n\
4764	while doloop IV candidate is used for address IV uses. It probably takes\n\
4765	expensive penalty. This hook allows target owners to define the cost for\n\
4766	this escpecially for address IV uses.\n\
4767	The default value is zero.",
4768	int64_t, 0)
4769
4770	DEFHOOK
4771	(can_use_doloop_p,
4772	"Return true if it is possible to use low-overhead loops (@code{doloop_end}\n\
4773	and @code{doloop_begin}) for a particular loop. @var{iterations} gives the\n\
4774	exact number of iterations, or 0 if not known. @var{iterations_max} gives\n\
4775	the maximum number of iterations, or 0 if not known. @var{loop_depth} is\n\
4776	the nesting depth of the loop, with 1 for innermost loops, 2 for loops that\n\
4777	contain innermost loops, and so on. @var{entered_at_top} is true if the\n\
4778	loop is only entered from the top.\n\
4779	\n\
4780	This hook is only used if @code{doloop_end} is available. The default\n\
4781	implementation returns true. You can use @code{can_use_doloop_if_innermost}\n\
4782	if the loop must be the innermost, and if there are no other restrictions.",
4783	bool, (const widest_int &iterations, const widest_int &iterations_max,
4784	unsigned int loop_depth, bool entered_at_top),
4785	hook_bool_wint_wint_uint_bool_true)
4786
4787	/* Returns NULL if target supports the insn within a doloop block,
4788	otherwise it returns an error message. */
4789	DEFHOOK
4790	(invalid_within_doloop,
4791	"\n\
4792	Take an instruction in @var{insn} and return NULL if it is valid within a\n\
4793	low-overhead loop, otherwise return a string explaining why doloop\n\
4794	could not be applied.\n\
4795	\n\
4796	Many targets use special registers for low-overhead looping. For any\n\
4797	instruction that clobbers these this function should return a string indicating\n\
4798	the reason why the doloop could not be applied.\n\
4799	By default, the RTL loop optimizer does not use a present doloop pattern for\n\
4800	loops containing function calls or branch on table instructions.",
4801	const char *, (const rtx_insn *insn),
4802	default_invalid_within_doloop)
4803
4804	/* Returns the machine mode which the target prefers for doloop IV. */
4805	DEFHOOK
4806	(preferred_doloop_mode,
4807	"This hook takes a @var{mode} for a doloop IV, where @code{mode} is the\n\
4808	original mode for the operation. If the target prefers an alternate\n\
4809	@code{mode} for the operation, then this hook should return that mode;\n\
4810	otherwise the original @code{mode} should be returned. For example, on a\n\
4811	64-bit target, @code{DImode} might be preferred over @code{SImode}. Both the\n\
4812	original and the returned modes should be @code{MODE_INT}.",
4813	machine_mode,
4814	(machine_mode mode),
4815	default_preferred_doloop_mode)
4816
4817	/* Returns true for a legitimate combined insn. */
4818	DEFHOOK
4819	(legitimate_combined_insn,
4820	"Take an instruction in @var{insn} and return @code{false} if the instruction\n\
4821	is not appropriate as a combination of two or more instructions. The\n\
4822	default is to accept all instructions.",
4823	bool, (rtx_insn *insn),
4824	hook_bool_rtx_insn_true)
4825
4826	DEFHOOK
4827	(valid_dllimport_attribute_p,
4828	"@var{decl} is a variable or function with @code{__attribute__((dllimport))}\n\
4829	specified. Use this hook if the target needs to add extra validation\n\
4830	checks to @code{handle_dll_attribute}.",
4831	bool, (const_tree decl),
4832	hook_bool_const_tree_true)
4833
4834	/* If non-zero, align constant anchors in CSE to a multiple of this
4835	value. */
4836	DEFHOOKPOD
4837	(const_anchor,
4838	"On some architectures it can take multiple instructions to synthesize\n\
4839	a constant. If there is another constant already in a register that\n\
4840	is close enough in value then it is preferable that the new constant\n\
4841	is computed from this register using immediate addition or\n\
4842	subtraction. We accomplish this through CSE. Besides the value of\n\
4843	the constant we also add a lower and an upper constant anchor to the\n\
4844	available expressions. These are then queried when encountering new\n\
4845	constants. The anchors are computed by rounding the constant up and\n\
4846	down to a multiple of the value of @code{TARGET_CONST_ANCHOR}.\n\
4847	@code{TARGET_CONST_ANCHOR} should be the maximum positive value\n\
4848	accepted by immediate-add plus one. We currently assume that the\n\
4849	value of @code{TARGET_CONST_ANCHOR} is a power of 2. For example, on\n\
4850	MIPS, where add-immediate takes a 16-bit signed value,\n\
4851	@code{TARGET_CONST_ANCHOR} is set to @samp{0x8000}. The default value\n\
4852	is zero, which disables this optimization.",
4853	unsigned HOST_WIDE_INT, 0)
4854
4855	/* Defines, which target-dependent bits (upper 16) are used by port */
4856	DEFHOOK
4857	(memmodel_check,
4858	"Validate target specific memory model mask bits. When NULL no target specific\n\
4859	memory model bits are allowed.",
4860	unsigned HOST_WIDE_INT, (unsigned HOST_WIDE_INT val), NULL)
4861
4862	/* Defines an offset bitwise ored into shifted address to get corresponding
4863	Address Sanitizer shadow address, or -1 if Address Sanitizer is not
4864	supported by the target. */
4865	DEFHOOK
4866	(asan_shadow_offset,
4867	"Return the offset bitwise ored into shifted address to get corresponding\n\
4868	Address Sanitizer shadow memory address. NULL if Address Sanitizer is not\n\
4869	supported by the target. May return 0 if Address Sanitizer is not supported\n\
4870	or using dynamic shadow offset by a subtarget.",
4871	unsigned HOST_WIDE_INT, (void),
4872	NULL)
4873
4874	DEFHOOK
4875	(asan_dynamic_shadow_offset_p,
4876	"Return true if asan should use dynamic shadow offset.",
4877	bool, (void),
4878	hook_bool_void_false)
4879
4880	/* Functions relating to calls - argument passing, returns, etc. */
4881	/* Members of struct call have no special macro prefix. */
4882	HOOK_VECTOR (TARGET_CALLS, calls)
4883
4884	DEFHOOK
4885	(promote_function_mode,
4886	"Like @code{PROMOTE_MODE}, but it is applied to outgoing function arguments or\n\
4887	function return values. The target hook should return the new mode\n\
4888	and possibly change @code{*@var{punsignedp}} if the promotion should\n\
4889	change signedness. This function is called only for scalar @emph{or\n\
4890	pointer} types.\n\
4891	\n\
4892	@var{for_return} allows to distinguish the promotion of arguments and\n\
4893	return values. If it is @code{1}, a return value is being promoted and\n\
4894	@code{TARGET_FUNCTION_VALUE} must perform the same promotions done here.\n\
4895	If it is @code{2}, the returned mode should be that of the register in\n\
4896	which an incoming parameter is copied, or the outgoing result is computed;\n\
4897	then the hook should return the same mode as @code{promote_mode}, though\n\
4898	the signedness may be different.\n\
4899	\n\
4900	@var{type} can be NULL when promoting function arguments of libcalls.\n\
4901	\n\
4902	The default is to not promote arguments and return values. You can\n\
4903	also define the hook to @code{default_promote_function_mode_always_promote}\n\
4904	if you would like to apply the same rules given by @code{PROMOTE_MODE}.",
4905	machine_mode, (const_tree type, machine_mode mode, int *punsignedp,
4906	const_tree funtype, int for_return),
4907	default_promote_function_mode)
4908
4909	DEFHOOK
4910	(promote_prototypes,
4911	"This target hook returns @code{true} if an argument declared in a\n\
4912	prototype as an integral type smaller than @code{int} should actually be\n\
4913	passed as an @code{int}. In addition to avoiding errors in certain\n\
4914	cases of mismatch, it also makes for better code on certain machines.\n\
4915	The default is to not promote prototypes.",
4916	bool, (const_tree fntype),
4917	hook_bool_const_tree_false)
4918
4919	DEFHOOK
4920	(struct_value_rtx,
4921	"This target hook should return the location of the structure value\n\
4922	address (normally a @code{mem} or @code{reg}), or 0 if the address is\n\
4923	passed as an ``invisible'' first argument. Note that @var{fndecl} may\n\
4924	be @code{NULL}, for libcalls. You do not need to define this target\n\
4925	hook if the address is always passed as an ``invisible'' first\n\
4926	argument.\n\
4927	\n\
4928	On some architectures the place where the structure value address\n\
4929	is found by the called function is not the same place that the\n\
4930	caller put it. This can be due to register windows, or it could\n\
4931	be because the function prologue moves it to a different place.\n\
4932	@var{incoming} is @code{1} or @code{2} when the location is needed in\n\
4933	the context of the called function, and @code{0} in the context of\n\
4934	the caller.\n\
4935	\n\
4936	If @var{incoming} is nonzero and the address is to be found on the\n\
4937	stack, return a @code{mem} which refers to the frame pointer. If\n\
4938	@var{incoming} is @code{2}, the result is being used to fetch the\n\
4939	structure value address at the beginning of a function. If you need\n\
4940	to emit adjusting code, you should do it at this point.",
4941	rtx, (tree fndecl, int incoming),
4942	hook_rtx_tree_int_null)
4943
4944	DEFHOOKPOD
4945	(omit_struct_return_reg,
4946	"Normally, when a function returns a structure by memory, the address\n\
4947	is passed as an invisible pointer argument, but the compiler also\n\
4948	arranges to return the address from the function like it would a normal\n\
4949	pointer return value. Define this to true if that behavior is\n\
4950	undesirable on your target.",
4951	bool, false)
4952
4953	DEFHOOK
4954	(return_in_memory,
4955	"This target hook should return a nonzero value to say to return the\n\
4956	function value in memory, just as large structures are always returned.\n\
4957	Here @var{type} will be the data type of the value, and @var{fntype}\n\
4958	will be the type of the function doing the returning, or @code{NULL} for\n\
4959	libcalls.\n\
4960	\n\
4961	Note that values of mode @code{BLKmode} must be explicitly handled\n\
4962	by this function. Also, the option @option{-fpcc-struct-return}\n\
4963	takes effect regardless of this macro. On most systems, it is\n\
4964	possible to leave the hook undefined; this causes a default\n\
4965	definition to be used, whose value is the constant 1 for @code{BLKmode}\n\
4966	values, and 0 otherwise.\n\
4967	\n\
4968	Do not use this hook to indicate that structures and unions should always\n\
4969	be returned in memory. You should instead use @code{DEFAULT_PCC_STRUCT_RETURN}\n\
4970	to indicate this.",
4971	bool, (const_tree type, const_tree fntype),
4972	default_return_in_memory)
4973
4974	DEFHOOK
4975	(return_in_msb,
4976	"This hook should return true if values of type @var{type} are returned\n\
4977	at the most significant end of a register (in other words, if they are\n\
4978	padded at the least significant end). You can assume that @var{type}\n\
4979	is returned in a register; the caller is required to check this.\n\
4980	\n\
4981	Note that the register provided by @code{TARGET_FUNCTION_VALUE} must\n\
4982	be able to hold the complete return value. For example, if a 1-, 2-\n\
4983	or 3-byte structure is returned at the most significant end of a\n\
4984	4-byte register, @code{TARGET_FUNCTION_VALUE} should provide an\n\
4985	@code{SImode} rtx.",
4986	bool, (const_tree type),
4987	hook_bool_const_tree_false)
4988
4989	/* Return true if a parameter must be passed by reference. TYPE may
4990	be null if this is a libcall. CA may be null if this query is
4991	from __builtin_va_arg. */
4992	DEFHOOK
4993	(pass_by_reference,
4994	"This target hook should return @code{true} if argument @var{arg} at the\n\
4995	position indicated by @var{cum} should be passed by reference. This\n\
4996	predicate is queried after target independent reasons for being\n\
4997	passed by reference, such as @code{TREE_ADDRESSABLE (@var{arg}.type)}.\n\
4998	\n\
4999	If the hook returns true, a copy of that argument is made in memory and a\n\
5000	pointer to the argument is passed instead of the argument itself.\n\
5001	The pointer is passed in whatever way is appropriate for passing a pointer\n\
5002	to that type.",
5003	bool,
5004	(cumulative_args_t cum, const function_arg_info &arg),
5005	hook_bool_CUMULATIVE_ARGS_arg_info_false)
5006
5007	DEFHOOK
5008	(expand_builtin_saveregs,
5009	"If defined, this hook produces the machine-specific code for a call to\n\
5010	@code{__builtin_saveregs}. This code will be moved to the very\n\
5011	beginning of the function, before any parameter access are made. The\n\
5012	return value of this function should be an RTX that contains the value\n\
5013	to use as the return of @code{__builtin_saveregs}.",
5014	rtx, (void),
5015	default_expand_builtin_saveregs)
5016
5017	/* Returns pretend_argument_size. */
5018	DEFHOOK
5019	(setup_incoming_varargs,
5020	"This target hook offers an alternative to using\n\
5021	@code{__builtin_saveregs} and defining the hook\n\
5022	@code{TARGET_EXPAND_BUILTIN_SAVEREGS}. Use it to store the anonymous\n\
5023	register arguments into the stack so that all the arguments appear to\n\
5024	have been passed consecutively on the stack. Once this is done, you can\n\
5025	use the standard implementation of varargs that works for machines that\n\
5026	pass all their arguments on the stack.\n\
5027	\n\
5028	The argument @var{args_so_far} points to the @code{CUMULATIVE_ARGS} data\n\
5029	structure, containing the values that are obtained after processing the\n\
5030	named arguments. The argument @var{arg} describes the last of these named\n\
5031	arguments. The argument @var{arg} should not be used if the function type\n\
5032	satisfies @code{TYPE_NO_NAMED_ARGS_STDARG_P}, since in that case there are\n\
5033	no named arguments and all arguments are accessed with @code{va_arg}.\n\
5034	\n\
5035	The target hook should do two things: first, push onto the stack all the\n\
5036	argument registers @emph{not} used for the named arguments, and second,\n\
5037	store the size of the data thus pushed into the @code{int}-valued\n\
5038	variable pointed to by @var{pretend_args_size}. The value that you\n\
5039	store here will serve as additional offset for setting up the stack\n\
5040	frame.\n\
5041	\n\
5042	Because you must generate code to push the anonymous arguments at\n\
5043	compile time without knowing their data types,\n\
5044	@code{TARGET_SETUP_INCOMING_VARARGS} is only useful on machines that\n\
5045	have just a single category of argument register and use it uniformly\n\
5046	for all data types.\n\
5047	\n\
5048	If the argument @var{second_time} is nonzero, it means that the\n\
5049	arguments of the function are being analyzed for the second time. This\n\
5050	happens for an inline function, which is not actually compiled until the\n\
5051	end of the source file. The hook @code{TARGET_SETUP_INCOMING_VARARGS} should\n\
5052	not generate any instructions in this case.",
5053	void, (cumulative_args_t args_so_far, const function_arg_info &arg,
5054	int *pretend_args_size, int second_time),
5055	default_setup_incoming_varargs)
5056
5057	DEFHOOK
5058	(start_call_args,
5059	"This target hook is invoked while generating RTL for a function call,\n\
5060	after the argument values have been computed, and after stack arguments\n\
5061	have been initialized, but before register arguments have been moved into\n\
5062	their ABI-defined hard register locations. It precedes calls to the related\n\
5063	hooks @code{TARGET_CALL_ARGS} and @code{TARGET_END_CALL_ARGS}.\n\
5064	The significance of this position in the call expansion is that:\n\
5065	\n\
5066	@itemize @bullet\n\
5067	@item\n\
5068	No argument registers are live.\n\
5069	@item\n\
5070	Although a call sequence can in general involve subcalls (such as using\n\
5071	@code{memcpy} to copy large arguments), no such subcall will occur between\n\
5072	the call to this hook and the generation of the main call instruction.\n\
5073	@end itemize\n\
5074	\n\
5075	The single argument @var{complete_args} is the state of the target\n\
5076	function's cumulative argument information after the final call to\n\
5077	@code{TARGET_FUNCTION_ARG}.\n\
5078	\n\
5079	The hook can be used for things like switching processor mode, in cases\n\
5080	where different calls need different processor modes. Most ports do not\n\
5081	need to implement anything for this hook.",
5082	void, (cumulative_args_t complete_args),
5083	hook_void_CUMULATIVE_ARGS)
5084
5085	DEFHOOK
5086	(call_args,
5087	"While generating RTL for a function call, this target hook is invoked once\n\
5088	for each argument passed to the function, either a register returned by\n\
5089	@code{TARGET_FUNCTION_ARG} or a memory location. It is called just\n\
5090	before the point where argument registers are stored.\n\
5091	\n\
5092	@var{complete_args} is the state of the target function's cumulative\n\
5093	argument information after the final call to @code{TARGET_FUNCTION_ARG}.\n\
5094	@var{loc} is the location of the argument. @var{type} is the type of\n\
5095	the function being called, or @code{NULL_TREE} for libcalls.\n\
5096	\n\
5097	For functions without arguments, the hook is called once with @code{pc_rtx}\n\
5098	passed instead of an argument register.\n\
5099	\n\
5100	This functionality can be used to perform special setup of call argument\n\
5101	registers, if a target needs it. Most ports do not need to implement\n\
5102	anything for this hook.",
5103	void, (cumulative_args_t complete_args, rtx loc, tree type),
5104	hook_void_CUMULATIVE_ARGS_rtx_tree)
5105
5106	DEFHOOK
5107	(end_call_args,
5108	"This target hook is invoked while generating RTL for a function call,\n\
5109	just after the point where the return reg is copied into a pseudo. It\n\
5110	signals that all the call argument and return registers for the just\n\
5111	emitted call are now no longer in use. @var{complete_args} is the\n\
5112	state of the target function's cumulative argument information after\n\
5113	the final call to @code{TARGET_FUNCTION_ARG}.\n\
5114	\n\
5115	Most ports do not need to implement anything for this hook.",
5116	void, (cumulative_args_t complete_args),
5117	hook_void_CUMULATIVE_ARGS)
5118
5119	DEFHOOK
5120	(call_offset_return_label,
5121	"While generating call-site debug info for a CALL insn, or a SEQUENCE\n\
5122	insn starting with a CALL, this target hook is invoked to compute the\n\
5123	offset to be added to the debug label emitted after the call to obtain\n\
5124	the return address that should be recorded as the return PC.",
5125	int, (rtx_insn *call_insn),
5126	hook_int_rtx_insn_0)
5127
5128	DEFHOOK
5129	(push_argument,
5130	"This target hook returns @code{true} if push instructions will be\n\
5131	used to pass outgoing arguments. When the push instruction usage is\n\
5132	optional, @var{npush} is nonzero to indicate the number of bytes to\n\
5133	push. Otherwise, @var{npush} is zero. If the target machine does not\n\
5134	have a push instruction or push instruction should be avoided,\n\
5135	@code{false} should be returned. That directs GCC to use an alternate\n\
5136	strategy: to allocate the entire argument block and then store the\n\
5137	arguments into it. If this target hook may return @code{true},\n\
5138	@code{PUSH_ROUNDING} must be defined.",
5139	bool, (unsigned int npush),
5140	default_push_argument)
5141
5142	DEFHOOK
5143	(strict_argument_naming,
5144	"Define this hook to return @code{true} if the location where a function\n\
5145	argument is passed depends on whether or not it is a named argument.\n\
5146	\n\
5147	This hook controls how the @var{named} argument to @code{TARGET_FUNCTION_ARG}\n\
5148	is set for varargs and stdarg functions. If this hook returns\n\
5149	@code{true}, the @var{named} argument is always true for named\n\
5150	arguments, and false for unnamed arguments. If it returns @code{false},\n\
5151	but @code{TARGET_PRETEND_OUTGOING_VARARGS_NAMED} returns @code{true},\n\
5152	then all arguments are treated as named. Otherwise, all named arguments\n\
5153	except the last are treated as named.\n\
5154	\n\
5155	You need not define this hook if it always returns @code{false}.",
5156	bool, (cumulative_args_t ca),
5157	hook_bool_CUMULATIVE_ARGS_false)
5158
5159	/* Returns true if we should use
5160	targetm.calls.setup_incoming_varargs() and/or
5161	targetm.calls.strict_argument_naming(). */
5162	DEFHOOK
5163	(pretend_outgoing_varargs_named,
5164	"If you need to conditionally change ABIs so that one works with\n\
5165	@code{TARGET_SETUP_INCOMING_VARARGS}, but the other works like neither\n\
5166	@code{TARGET_SETUP_INCOMING_VARARGS} nor @code{TARGET_STRICT_ARGUMENT_NAMING} was\n\
5167	defined, then define this hook to return @code{true} if\n\
5168	@code{TARGET_SETUP_INCOMING_VARARGS} is used, @code{false} otherwise.\n\
5169	Otherwise, you should not define this hook.",
5170	bool, (cumulative_args_t ca),
5171	default_pretend_outgoing_varargs_named)
5172
5173	/* Given a complex type T, return true if a parameter of type T
5174	should be passed as two scalars. */
5175	DEFHOOK
5176	(split_complex_arg,
5177	"This hook should return true if parameter of type @var{type} are passed\n\
5178	as two scalar parameters. By default, GCC will attempt to pack complex\n\
5179	arguments into the target's word size. Some ABIs require complex arguments\n\
5180	to be split and treated as their individual components. For example, on\n\
5181	AIX64, complex floats should be passed in a pair of floating point\n\
5182	registers, even though a complex float would fit in one 64-bit floating\n\
5183	point register.\n\
5184	\n\
5185	The default value of this hook is @code{NULL}, which is treated as always\n\
5186	false.",
5187	bool, (const_tree type), NULL)
5188
5189	/* Return true if type T, mode MODE, may not be passed in registers,
5190	but must be passed on the stack. */
5191	/* ??? This predicate should be applied strictly after pass-by-reference.
5192	Need audit to verify that this is the case. */
5193	DEFHOOK
5194	(must_pass_in_stack,
5195	"This target hook should return @code{true} if we should not pass @var{arg}\n\
5196	solely in registers. The file @file{expr.h} defines a\n\
5197	definition that is usually appropriate, refer to @file{expr.h} for additional\n\
5198	documentation.",
5199	bool, (const function_arg_info &arg),
5200	must_pass_in_stack_var_size_or_pad)
5201
5202	/* Return true if type TYPE, mode MODE, which is passed by reference,
5203	should have the object copy generated by the callee rather than
5204	the caller. It is never called for TYPE requiring constructors. */
5205	DEFHOOK
5206	(callee_copies,
5207	"The function argument described by the parameters to this hook is\n\
5208	known to be passed by reference. The hook should return true if the\n\
5209	function argument should be copied by the callee instead of copied\n\
5210	by the caller.\n\
5211	\n\
5212	For any argument for which the hook returns true, if it can be\n\
5213	determined that the argument is not modified, then a copy need\n\
5214	not be generated.\n\
5215	\n\
5216	The default version of this hook always returns false.",
5217	bool,
5218	(cumulative_args_t cum, const function_arg_info &arg),
5219	hook_bool_CUMULATIVE_ARGS_arg_info_false)
5220
5221	/* Return zero for arguments passed entirely on the stack or entirely
5222	in registers. If passed in both, return the number of bytes passed
5223	in registers; the balance is therefore passed on the stack. */
5224	DEFHOOK
5225	(arg_partial_bytes,
5226	"This target hook returns the number of bytes at the beginning of an\n\
5227	argument that must be put in registers. The value must be zero for\n\
5228	arguments that are passed entirely in registers or that are entirely\n\
5229	pushed on the stack.\n\
5230	\n\
5231	On some machines, certain arguments must be passed partially in\n\
5232	registers and partially in memory. On these machines, typically the\n\
5233	first few words of arguments are passed in registers, and the rest\n\
5234	on the stack. If a multi-word argument (a @code{double} or a\n\
5235	structure) crosses that boundary, its first few words must be passed\n\
5236	in registers and the rest must be pushed. This macro tells the\n\
5237	compiler when this occurs, and how many bytes should go in registers.\n\
5238	\n\
5239	@code{TARGET_FUNCTION_ARG} for these arguments should return the first\n\
5240	register to be used by the caller for this argument; likewise\n\
5241	@code{TARGET_FUNCTION_INCOMING_ARG}, for the called function.",
5242	int, (cumulative_args_t cum, const function_arg_info &arg),
5243	hook_int_CUMULATIVE_ARGS_arg_info_0)
5244
5245	/* Update the state in CA to advance past an argument in the
5246	argument list. The values MODE, TYPE, and NAMED describe that
5247	argument. */
5248	DEFHOOK
5249	(function_arg_advance,
5250	"This hook updates the summarizer variable pointed to by @var{ca} to\n\
5251	advance past argument @var{arg} in the argument list. Once this is done,\n\
5252	the variable @var{cum} is suitable for analyzing the @emph{following}\n\
5253	argument with @code{TARGET_FUNCTION_ARG}, etc.\n\
5254	\n\
5255	This hook need not do anything if the argument in question was passed\n\
5256	on the stack. The compiler knows how to track the amount of stack space\n\
5257	used for arguments without any special help.",
5258	void,
5259	(cumulative_args_t ca, const function_arg_info &arg),
5260	default_function_arg_advance)
5261
5262	DEFHOOK
5263	(function_arg_offset,
5264	"This hook returns the number of bytes to add to the offset of an\n\
5265	argument of type @var{type} and mode @var{mode} when passed in memory.\n\
5266	This is needed for the SPU, which passes @code{char} and @code{short}\n\
5267	arguments in the preferred slot that is in the middle of the quad word\n\
5268	instead of starting at the top. The default implementation returns 0.",
5269	HOST_WIDE_INT, (machine_mode mode, const_tree type),
5270	default_function_arg_offset)
5271
5272	DEFHOOK
5273	(function_arg_padding,
5274	"This hook determines whether, and in which direction, to pad out\n\
5275	an argument of mode @var{mode} and type @var{type}. It returns\n\
5276	@code{PAD_UPWARD} to insert padding above the argument, @code{PAD_DOWNWARD}\n\
5277	to insert padding below the argument, or @code{PAD_NONE} to inhibit padding.\n\
5278	\n\
5279	The @emph{amount} of padding is not controlled by this hook, but by\n\
5280	@code{TARGET_FUNCTION_ARG_ROUND_BOUNDARY}. It is always just enough\n\
5281	to reach the next multiple of that boundary.\n\
5282	\n\
5283	This hook has a default definition that is right for most systems.\n\
5284	For little-endian machines, the default is to pad upward. For\n\
5285	big-endian machines, the default is to pad downward for an argument of\n\
5286	constant size shorter than an @code{int}, and upward otherwise.",
5287	pad_direction, (machine_mode mode, const_tree type),
5288	default_function_arg_padding)
5289
5290	/* Return zero if the argument described by the state of CA should
5291	be placed on a stack, or a hard register in which to store the
5292	argument. The values MODE, TYPE, and NAMED describe that
5293	argument. */
5294	DEFHOOK
5295	(function_arg,
5296	"Return an RTX indicating whether function argument @var{arg} is passed\n\
5297	in a register and if so, which register. Argument @var{ca} summarizes all\n\
5298	the previous arguments.\n\
5299	\n\
5300	The return value is usually either a @code{reg} RTX for the hard\n\
5301	register in which to pass the argument, or zero to pass the argument\n\
5302	on the stack.\n\
5303	\n\
5304	The value of the expression can also be a @code{parallel} RTX@. This is\n\
5305	used when an argument is passed in multiple locations. The mode of the\n\
5306	@code{parallel} should be the mode of the entire argument. The\n\
5307	@code{parallel} holds any number of @code{expr_list} pairs; each one\n\
5308	describes where part of the argument is passed. In each\n\
5309	@code{expr_list} the first operand must be a @code{reg} RTX for the hard\n\
5310	register in which to pass this part of the argument, and the mode of the\n\
5311	register RTX indicates how large this part of the argument is. The\n\
5312	second operand of the @code{expr_list} is a @code{const_int} which gives\n\
5313	the offset in bytes into the entire argument of where this part starts.\n\
5314	As a special exception the first @code{expr_list} in the @code{parallel}\n\
5315	RTX may have a first operand of zero. This indicates that the entire\n\
5316	argument is also stored on the stack.\n\
5317	\n\
5318	The last time this hook is called, it is called with @code{MODE ==\n\
5319	VOIDmode}, and its result is passed to the @code{call} or @code{call_value}\n\
5320	pattern as operands 2 and 3 respectively.\n\
5321	\n\
5322	@cindex @file{stdarg.h} and register arguments\n\
5323	The usual way to make the ISO library @file{stdarg.h} work on a\n\
5324	machine where some arguments are usually passed in registers, is to\n\
5325	cause nameless arguments to be passed on the stack instead. This is\n\
5326	done by making @code{TARGET_FUNCTION_ARG} return 0 whenever\n\
5327	@var{named} is @code{false}.\n\
5328	\n\
5329	@cindex @code{TARGET_MUST_PASS_IN_STACK}, and @code{TARGET_FUNCTION_ARG}\n\
5330	@cindex @code{REG_PARM_STACK_SPACE}, and @code{TARGET_FUNCTION_ARG}\n\
5331	You may use the hook @code{targetm.calls.must_pass_in_stack}\n\
5332	in the definition of this macro to determine if this argument is of a\n\
5333	type that must be passed in the stack. If @code{REG_PARM_STACK_SPACE}\n\
5334	is not defined and @code{TARGET_FUNCTION_ARG} returns nonzero for such an\n\
5335	argument, the compiler will abort. If @code{REG_PARM_STACK_SPACE} is\n\
5336	defined, the argument will be computed in the stack and then loaded into\n\
5337	a register.",
5338	rtx, (cumulative_args_t ca, const function_arg_info &arg),
5339	default_function_arg)
5340
5341	DEFHOOK
5342	(function_incoming_arg,
5343	"Define this hook if the caller and callee on the target have different\n\
5344	views of where arguments are passed. Also define this hook if there are\n\
5345	functions that are never directly called, but are invoked by the hardware\n\
5346	and which have nonstandard calling conventions.\n\
5347	\n\
5348	In this case @code{TARGET_FUNCTION_ARG} computes the register in\n\
5349	which the caller passes the value, and\n\
5350	@code{TARGET_FUNCTION_INCOMING_ARG} should be defined in a similar\n\
5351	fashion to tell the function being called where the arguments will\n\
5352	arrive.\n\
5353	\n\
5354	@code{TARGET_FUNCTION_INCOMING_ARG} can also return arbitrary address\n\
5355	computation using hard register, which can be forced into a register,\n\
5356	so that it can be used to pass special arguments.\n\
5357	\n\
5358	If @code{TARGET_FUNCTION_INCOMING_ARG} is not defined,\n\
5359	@code{TARGET_FUNCTION_ARG} serves both purposes.",
5360	rtx, (cumulative_args_t ca, const function_arg_info &arg),
5361	default_function_incoming_arg)
5362
5363	DEFHOOK
5364	(function_arg_boundary,
5365	"This hook returns the alignment boundary, in bits, of an argument\n\
5366	with the specified mode and type. The default hook returns\n\
5367	@code{PARM_BOUNDARY} for all arguments.",
5368	unsigned int, (machine_mode mode, const_tree type),
5369	default_function_arg_boundary)
5370
5371	DEFHOOK
5372	(function_arg_round_boundary,
5373	"Normally, the size of an argument is rounded up to @code{PARM_BOUNDARY},\n\
5374	which is the default value for this hook. You can define this hook to\n\
5375	return a different value if an argument size must be rounded to a larger\n\
5376	value.",
5377	unsigned int, (machine_mode mode, const_tree type),
5378	default_function_arg_round_boundary)
5379
5380	/* Return the diagnostic message string if function without a prototype
5381	is not allowed for this 'val' argument; NULL otherwise. */
5382	DEFHOOK
5383	(invalid_arg_for_unprototyped_fn,
5384	"If defined, this macro returns the diagnostic message when it is\n\
5385	illegal to pass argument @var{val} to function @var{funcdecl}\n\
5386	with prototype @var{typelist}.",
5387	const char *, (const_tree typelist, const_tree funcdecl, const_tree val),
5388	hook_invalid_arg_for_unprototyped_fn)
5389
5390	/* Return an rtx for the return value location of the function
5391	specified by FN_DECL_OR_TYPE with a return type of RET_TYPE. */
5392	DEFHOOK
5393	(function_value,
5394	"\n\
5395	Define this to return an RTX representing the place where a function\n\
5396	returns or receives a value of data type @var{ret_type}, a tree node\n\
5397	representing a data type. @var{fn_decl_or_type} is a tree node\n\
5398	representing @code{FUNCTION_DECL} or @code{FUNCTION_TYPE} of a\n\
5399	function being called. If @var{outgoing} is false, the hook should\n\
5400	compute the register in which the caller will see the return value.\n\
5401	Otherwise, the hook should return an RTX representing the place where\n\
5402	a function returns a value.\n\
5403	\n\
5404	On many machines, only @code{TYPE_MODE (@var{ret_type})} is relevant.\n\
5405	(Actually, on most machines, scalar values are returned in the same\n\
5406	place regardless of mode.) The value of the expression is usually a\n\
5407	@code{reg} RTX for the hard register where the return value is stored.\n\
5408	The value can also be a @code{parallel} RTX, if the return value is in\n\
5409	multiple places. See @code{TARGET_FUNCTION_ARG} for an explanation of the\n\
5410	@code{parallel} form. Note that the callee will populate every\n\
5411	location specified in the @code{parallel}, but if the first element of\n\
5412	the @code{parallel} contains the whole return value, callers will use\n\
5413	that element as the canonical location and ignore the others. The m68k\n\
5414	port uses this type of @code{parallel} to return pointers in both\n\
5415	@samp{%a0} (the canonical location) and @samp{%d0}.\n\
5416	\n\
5417	If the precise function being called is known, @var{func} is a tree\n\
5418	node (@code{FUNCTION_DECL}) for it; otherwise, @var{func} is a null\n\
5419	pointer. This makes it possible to use a different value-returning\n\
5420	convention for specific functions when all their calls are\n\
5421	known.\n\
5422	\n\
5423	Some target machines have ``register windows'' so that the register in\n\
5424	which a function returns its value is not the same as the one in which\n\
5425	the caller sees the value. For such machines, you should return\n\
5426	different RTX depending on @var{outgoing}.\n\
5427	\n\
5428	@code{TARGET_FUNCTION_VALUE} is not used for return values with\n\
5429	aggregate data types, because these are returned in another way. See\n\
5430	@code{TARGET_STRUCT_VALUE_RTX} and related macros, below.",
5431	rtx, (const_tree ret_type, const_tree fn_decl_or_type, bool outgoing),
5432	default_function_value)
5433
5434	/* Return the rtx for the result of a libcall of mode MODE,
5435	calling the function FN_NAME. */
5436	DEFHOOK
5437	(libcall_value,
5438	"Define this hook if the back-end needs to know the name of the libcall\n\
5439	function in order to determine where the result should be returned.\n\
5440	\n\
5441	The mode of the result is given by @var{mode} and the name of the called\n\
5442	library function is given by @var{fun}. The hook should return an RTX\n\
5443	representing the place where the library function result will be returned.\n\
5444	\n\
5445	If this hook is not defined, then LIBCALL_VALUE will be used.",
5446	rtx, (machine_mode mode, const_rtx fun),
5447	default_libcall_value)
5448
5449	/* Return true if REGNO is a possible register number for
5450	a function value as seen by the caller. */
5451	DEFHOOK
5452	(function_value_regno_p,
5453	"A target hook that return @code{true} if @var{regno} is the number of a hard\n\
5454	register in which the values of called function may come back.\n\
5455	\n\
5456	A register whose use for returning values is limited to serving as the\n\
5457	second of a pair (for a value of type @code{double}, say) need not be\n\
5458	recognized by this target hook.\n\
5459	\n\
5460	If the machine has register windows, so that the caller and the called\n\
5461	function use different registers for the return value, this target hook\n\
5462	should recognize only the caller's register numbers.\n\
5463	\n\
5464	If this hook is not defined, then FUNCTION_VALUE_REGNO_P will be used.",
5465	bool, (const unsigned int regno),
5466	default_function_value_regno_p)
5467
5468	DEFHOOK
5469	(fntype_abi,
5470	"Return the ABI used by a function with type @var{type}; see the\n\
5471	definition of @code{predefined_function_abi} for details of the ABI\n\
5472	descriptor. Targets only need to define this hook if they support\n\
5473	interoperability between several ABIs in the same translation unit.",
5474	const predefined_function_abi &, (const_tree type),
5475	NULL)
5476
5477	DEFHOOK
5478	(insn_callee_abi,
5479	"This hook returns a description of the ABI used by the target of\n\
5480	call instruction @var{insn}; see the definition of\n\
5481	@code{predefined_function_abi} for details of the ABI descriptor.\n\
5482	Only the global function @code{insn_callee_abi} should call this hook\n\
5483	directly.\n\
5484	\n\
5485	Targets only need to define this hook if they support\n\
5486	interoperability between several ABIs in the same translation unit.",
5487	const predefined_function_abi &, (const rtx_insn *insn),
5488	NULL)
5489
5490	/* ??? Documenting this hook requires a GFDL license grant. */
5491	DEFHOOK_UNDOC
5492	(internal_arg_pointer,
5493	"Return an rtx for the argument pointer incoming to the\
5494	current function.",
5495	rtx, (void),
5496	default_internal_arg_pointer)
5497
5498	/* Update the current function stack boundary if needed. */
5499	DEFHOOK
5500	(update_stack_boundary,
5501	"Define this macro to update the current function stack boundary if\n\
5502	necessary.",
5503	void, (void), NULL)
5504
5505	/* Handle stack alignment and return an rtx for Dynamic Realign
5506	Argument Pointer if necessary. */
5507	DEFHOOK
5508	(get_drap_rtx,
5509	"This hook should return an rtx for Dynamic Realign Argument Pointer (DRAP) if a\n\
5510	different argument pointer register is needed to access the function's\n\
5511	argument list due to stack realignment. Return @code{NULL} if no DRAP\n\
5512	is needed.",
5513	rtx, (void), NULL)
5514
5515	/* Generate instruction sequence to zero call used registers. */
5516	DEFHOOK
5517	(zero_call_used_regs,
5518	"This target hook emits instructions to zero the subset of @var{selected_regs}\n\
5519	that could conceivably contain values that are useful to an attacker.\n\
5520	Return the set of registers that were actually cleared.\n\
5521	\n\
5522	For most targets, the returned set of registers is a subset of\n\
5523	@var{selected_regs}, however, for some of the targets (for example MIPS),\n\
5524	clearing some registers that are in the @var{selected_regs} requires\n\
5525	clearing other call used registers that are not in the @var{selected_regs},\n\
5526	under such situation, the returned set of registers must be a subset of all\n\
5527	call used registers.\n\
5528	\n\
5529	The default implementation uses normal move instructions to zero\n\
5530	all the registers in @var{selected_regs}. Define this hook if the\n\
5531	target has more efficient ways of zeroing certain registers,\n\
5532	or if you believe that certain registers would never contain\n\
5533	values that are useful to an attacker.",
5534	HARD_REG_SET, (HARD_REG_SET selected_regs),
5535	default_zero_call_used_regs)
5536
5537	/* Return true if all function parameters should be spilled to the
5538	stack. */
5539	DEFHOOK
5540	(allocate_stack_slots_for_args,
5541	"When optimization is disabled, this hook indicates whether or not\n\
5542	arguments should be allocated to stack slots. Normally, GCC allocates\n\
5543	stacks slots for arguments when not optimizing in order to make\n\
5544	debugging easier. However, when a function is declared with\n\
5545	@code{__attribute__((naked))}, there is no stack frame, and the compiler\n\
5546	cannot safely move arguments from the registers in which they are passed\n\
5547	to the stack. Therefore, this hook should return true in general, but\n\
5548	false for naked functions. The default implementation always returns true.",
5549	bool, (void),
5550	hook_bool_void_true)
5551
5552	/* Return an rtx for the static chain for FNDECL_OR_TYPE. If INCOMING_P
5553	is true, then it should be for the callee; otherwise for the caller. */
5554	DEFHOOK
5555	(static_chain,
5556	"This hook replaces the use of @code{STATIC_CHAIN_REGNUM} et al for\n\
5557	targets that may use different static chain locations for different\n\
5558	nested functions. This may be required if the target has function\n\
5559	attributes that affect the calling conventions of the function and\n\
5560	those calling conventions use different static chain locations.\n\
5561	\n\
5562	The default version of this hook uses @code{STATIC_CHAIN_REGNUM} et al.\n\
5563	\n\
5564	If the static chain is passed in memory, this hook should be used to\n\
5565	provide rtx giving @code{mem} expressions that denote where they are stored.\n\
5566	Often the @code{mem} expression as seen by the caller will be at an offset\n\
5567	from the stack pointer and the @code{mem} expression as seen by the callee\n\
5568	will be at an offset from the frame pointer.\n\
5569	@findex stack_pointer_rtx\n\
5570	@findex frame_pointer_rtx\n\
5571	@findex arg_pointer_rtx\n\
5572	The variables @code{stack_pointer_rtx}, @code{frame_pointer_rtx}, and\n\
5573	@code{arg_pointer_rtx} will have been initialized and should be used\n\
5574	to refer to those items.",
5575	rtx, (const_tree fndecl_or_type, bool incoming_p),
5576	default_static_chain)
5577
5578	/* Fill in the trampoline at MEM with a call to FNDECL and a
5579	static chain value of CHAIN. */
5580	DEFHOOK
5581	(trampoline_init,
5582	"This hook is called to initialize a trampoline.\n\
5583	@var{m_tramp} is an RTX for the memory block for the trampoline; @var{fndecl}\n\
5584	is the @code{FUNCTION_DECL} for the nested function; @var{static_chain} is an\n\
5585	RTX for the static chain value that should be passed to the function\n\
5586	when it is called.\n\
5587	\n\
5588	If the target defines @code{TARGET_ASM_TRAMPOLINE_TEMPLATE}, then the\n\
5589	first thing this hook should do is emit a block move into @var{m_tramp}\n\
5590	from the memory block returned by @code{assemble_trampoline_template}.\n\
5591	Note that the block move need only cover the constant parts of the\n\
5592	trampoline. If the target isolates the variable parts of the trampoline\n\
5593	to the end, not all @code{TRAMPOLINE_SIZE} bytes need be copied.\n\
5594	\n\
5595	If the target requires any other actions, such as flushing caches\n\
5596	(possibly calling function maybe_emit_call_builtin___clear_cache) or\n\
5597	enabling stack execution, these actions should be performed after\n\
5598	initializing the trampoline proper.",
5599	void, (rtx m_tramp, tree fndecl, rtx static_chain),
5600	default_trampoline_init)
5601
5602	/* Emit a call to a function to clear the instruction cache. */
5603	DEFHOOK
5604	(emit_call_builtin___clear_cache,
5605	"On targets that do not define a @code{clear_cache} insn expander,\n\
5606	but that define the @code{CLEAR_CACHE_INSN} macro,\n\
5607	maybe_emit_call_builtin___clear_cache relies on this target hook\n\
5608	to clear an address range in the instruction cache.\n\
5609	\n\
5610	The default implementation calls the @code{__clear_cache} builtin,\n\
5611	taking the assembler name from the builtin declaration. Overriding\n\
5612	definitions may call alternate functions, with alternate calling\n\
5613	conventions, or emit alternate RTX to perform the job.",
5614	void, (rtx begin, rtx end),
5615	default_emit_call_builtin___clear_cache)
5616
5617	/* Adjust the address of the trampoline in a target-specific way. */
5618	DEFHOOK
5619	(trampoline_adjust_address,
5620	"This hook should perform any machine-specific adjustment in\n\
5621	the address of the trampoline. Its argument contains the address of the\n\
5622	memory block that was passed to @code{TARGET_TRAMPOLINE_INIT}. In case\n\
5623	the address to be used for a function call should be different from the\n\
5624	address at which the template was stored, the different address should\n\
5625	be returned; otherwise @var{addr} should be returned unchanged.\n\
5626	If this hook is not defined, @var{addr} will be used for function calls.",
5627	rtx, (rtx addr), NULL)
5628
5629	DEFHOOKPOD
5630	(custom_function_descriptors,
5631	"If the target can use GCC's generic descriptor mechanism for nested\n\
5632	functions, define this hook to a power of 2 representing an unused bit\n\
5633	in function pointers which can be used to differentiate descriptors at\n\
5634	run time. This value gives the number of bytes by which descriptor\n\
5635	pointers are misaligned compared to function pointers. For example, on\n\
5636	targets that require functions to be aligned to a 4-byte boundary, a\n\
5637	value of either 1 or 2 is appropriate unless the architecture already\n\
5638	reserves the bit for another purpose, such as on ARM.\n\
5639	\n\
5640	Define this hook to 0 if the target implements ABI support for\n\
5641	function descriptors in its standard calling sequence, like for example\n\
5642	HPPA or IA-64.\n\
5643	\n\
5644	Using descriptors for nested functions\n\
5645	eliminates the need for trampolines that reside on the stack and require\n\
5646	it to be made executable.",
5647	int, -1)
5648
5649	/* Return the number of bytes of its own arguments that a function
5650	pops on returning, or 0 if the function pops no arguments and the
5651	caller must therefore pop them all after the function returns. */
5652	/* ??? tm.texi has no types for the parameters. */
5653	DEFHOOK
5654	(return_pops_args,
5655	"This target hook returns the number of bytes of its own arguments that\n\
5656	a function pops on returning, or 0 if the function pops no arguments\n\
5657	and the caller must therefore pop them all after the function returns.\n\
5658	\n\
5659	@var{fundecl} is a C variable whose value is a tree node that describes\n\
5660	the function in question. Normally it is a node of type\n\
5661	@code{FUNCTION_DECL} that describes the declaration of the function.\n\
5662	From this you can obtain the @code{DECL_ATTRIBUTES} of the function.\n\
5663	\n\
5664	@var{funtype} is a C variable whose value is a tree node that\n\
5665	describes the function in question. Normally it is a node of type\n\
5666	@code{FUNCTION_TYPE} that describes the data type of the function.\n\
5667	From this it is possible to obtain the data types of the value and\n\
5668	arguments (if known).\n\
5669	\n\
5670	When a call to a library function is being considered, @var{fundecl}\n\
5671	will contain an identifier node for the library function. Thus, if\n\
5672	you need to distinguish among various library functions, you can do so\n\
5673	by their names. Note that ``library function'' in this context means\n\
5674	a function used to perform arithmetic, whose name is known specially\n\
5675	in the compiler and was not mentioned in the C code being compiled.\n\
5676	\n\
5677	@var{size} is the number of bytes of arguments passed on the\n\
5678	stack. If a variable number of bytes is passed, it is zero, and\n\
5679	argument popping will always be the responsibility of the calling function.\n\
5680	\n\
5681	On the VAX, all functions always pop their arguments, so the definition\n\
5682	of this macro is @var{size}. On the 68000, using the standard\n\
5683	calling convention, no functions pop their arguments, so the value of\n\
5684	the macro is always 0 in this case. But an alternative calling\n\
5685	convention is available in which functions that take a fixed number of\n\
5686	arguments pop them but other functions (such as @code{printf}) pop\n\
5687	nothing (the caller pops all). When this convention is in use,\n\
5688	@var{funtype} is examined to determine whether a function takes a fixed\n\
5689	number of arguments.",
5690	poly_int64, (tree fundecl, tree funtype, poly_int64 size),
5691	default_return_pops_args)
5692
5693	/* Return a mode wide enough to copy any function value that might be
5694	returned. */
5695	DEFHOOK
5696	(get_raw_result_mode,
5697	"This target hook returns the mode to be used when accessing raw return\n\
5698	registers in @code{__builtin_return}. Define this macro if the value\n\
5699	in @var{reg_raw_mode} is not correct. Use @code{VOIDmode} if a register\n\
5700	should be ignored for @code{__builtin_return} purposes.",
5701	fixed_size_mode, (int regno),
5702	default_get_reg_raw_mode)
5703
5704	/* Return a mode wide enough to copy any argument value that might be
5705	passed. */
5706	DEFHOOK
5707	(get_raw_arg_mode,
5708	"This target hook returns the mode to be used when accessing raw argument\n\
5709	registers in @code{__builtin_apply_args}. Define this macro if the value\n\
5710	in @var{reg_raw_mode} is not correct. Use @code{VOIDmode} if a register\n\
5711	should be ignored for @code{__builtin_apply_args} purposes.",
5712	fixed_size_mode, (int regno),
5713	default_get_reg_raw_mode)
5714
5715	/* Return true if a type is an empty record. */
5716	DEFHOOK
5717	(empty_record_p,
5718	"This target hook returns true if the type is an empty record. The default\n\
5719	is to return @code{false}.",
5720	bool, (const_tree type),
5721	hook_bool_const_tree_false)
5722
5723	/* Warn about the change in empty class parameter passing ABI. */
5724	DEFHOOK
5725	(warn_parameter_passing_abi,
5726	"This target hook warns about the change in empty class parameter passing\n\
5727	ABI.",
5728	void, (cumulative_args_t ca, tree type),
5729	hook_void_CUMULATIVE_ARGS_tree)
5730
5731	HOOK_VECTOR_END (calls)
5732
5733	DEFHOOK
5734	(use_pseudo_pic_reg,
5735	"This hook should return 1 in case pseudo register should be created\n\
5736	for pic_offset_table_rtx during function expand.",
5737	bool, (void),
5738	hook_bool_void_false)
5739
5740	DEFHOOK
5741	(init_pic_reg,
5742	"Perform a target dependent initialization of pic_offset_table_rtx.\n\
5743	This hook is called at the start of register allocation.",
5744	void, (void),
5745	hook_void_void)
5746
5747	/* Return the diagnostic message string if conversion from FROMTYPE
5748	to TOTYPE is not allowed, NULL otherwise. */
5749	DEFHOOK
5750	(invalid_conversion,
5751	"If defined, this macro returns the diagnostic message when it is\n\
5752	invalid to convert from @var{fromtype} to @var{totype}, or @code{NULL}\n\
5753	if validity should be determined by the front end.",
5754	const char *, (const_tree fromtype, const_tree totype),
5755	hook_constcharptr_const_tree_const_tree_null)
5756
5757	/* Return the diagnostic message string if the unary operation OP is
5758	not permitted on TYPE, NULL otherwise. */
5759	DEFHOOK
5760	(invalid_unary_op,
5761	"If defined, this macro returns the diagnostic message when it is\n\
5762	invalid to apply operation @var{op} (where unary plus is denoted by\n\
5763	@code{CONVERT_EXPR}) to an operand of type @var{type}, or @code{NULL}\n\
5764	if validity should be determined by the front end.",
5765	const char *, (int op, const_tree type),
5766	hook_constcharptr_int_const_tree_null)
5767
5768	/* Return the diagnostic message string if the binary operation OP
5769	is not permitted on TYPE1 and TYPE2, NULL otherwise. */
5770	DEFHOOK
5771	(invalid_binary_op,
5772	"If defined, this macro returns the diagnostic message when it is\n\
5773	invalid to apply operation @var{op} to operands of types @var{type1}\n\
5774	and @var{type2}, or @code{NULL} if validity should be determined by\n\
5775	the front end.",
5776	const char *, (int op, const_tree type1, const_tree type2),
5777	hook_constcharptr_int_const_tree_const_tree_null)
5778
5779	/* If values of TYPE are promoted to some other type when used in
5780	expressions (analogous to the integer promotions), return that type,
5781	or NULL_TREE otherwise. */
5782	DEFHOOK
5783	(promoted_type,
5784	"If defined, this target hook returns the type to which values of\n\
5785	@var{type} should be promoted when they appear in expressions,\n\
5786	analogous to the integer promotions, or @code{NULL_TREE} to use the\n\
5787	front end's normal promotion rules. This hook is useful when there are\n\
5788	target-specific types with special promotion rules.\n\
5789	This is currently used only by the C and C++ front ends.",
5790	tree, (const_tree type),
5791	hook_tree_const_tree_null)
5792
5793	/* Convert EXPR to TYPE, if target-specific types with special conversion
5794	rules are involved. Return the converted expression, or NULL to apply
5795	the standard conversion rules. */
5796	DEFHOOK
5797	(convert_to_type,
5798	"If defined, this hook returns the result of converting @var{expr} to\n\
5799	@var{type}. It should return the converted expression,\n\
5800	or @code{NULL_TREE} to apply the front end's normal conversion rules.\n\
5801	This hook is useful when there are target-specific types with special\n\
5802	conversion rules.\n\
5803	This is currently used only by the C and C++ front ends.",
5804	tree, (tree type, tree expr),
5805	hook_tree_tree_tree_null)
5806
5807	DEFHOOK
5808	(verify_type_context,
5809	"If defined, this hook returns false if there is a target-specific reason\n\
5810	why type @var{type} cannot be used in the source language context described\n\
5811	by @var{context}. When @var{silent_p} is false, the hook also reports an\n\
5812	error against @var{loc} for invalid uses of @var{type}.\n\
5813	\n\
5814	Calls to this hook should be made through the global function\n\
5815	@code{verify_type_context}, which makes the @var{silent_p} parameter\n\
5816	default to false and also handles @code{error_mark_node}.\n\
5817	\n\
5818	The default implementation always returns true.",
5819	bool, (location_t loc, type_context_kind context, const_tree type,
5820	bool silent_p),
5821	NULL)
5822
5823	DEFHOOK
5824	(can_change_mode_class,
5825	"This hook returns true if it is possible to bitcast values held in\n\
5826	registers of class @var{rclass} from mode @var{from} to mode @var{to}\n\
5827	and if doing so preserves the low-order bits that are common to both modes.\n\
5828	The result is only meaningful if @var{rclass} has registers that can hold\n\
5829	both @code{from} and @code{to}. The default implementation returns true.\n\
5830	\n\
5831	As an example of when such bitcasting is invalid, loading 32-bit integer or\n\
5832	floating-point objects into floating-point registers on Alpha extends them\n\
5833	to 64 bits. Therefore loading a 64-bit object and then storing it as a\n\
5834	32-bit object does not store the low-order 32 bits, as would be the case\n\
5835	for a normal register. Therefore, @file{alpha.h} defines\n\
5836	@code{TARGET_CAN_CHANGE_MODE_CLASS} to return:\n\
5837	\n\
5838	@smallexample\n\
5839	(GET_MODE_SIZE (from) == GET_MODE_SIZE (to)\n\
5840	|| !reg_classes_intersect_p (FLOAT_REGS, rclass))\n\
5841	@end smallexample\n\
5842	\n\
5843	Even if storing from a register in mode @var{to} would be valid,\n\
5844	if both @var{from} and @code{raw_reg_mode} for @var{rclass} are wider\n\
5845	than @code{word_mode}, then we must prevent @var{to} narrowing the\n\
5846	mode. This happens when the middle-end assumes that it can load\n\
5847	or store pieces of an @var{N}-word pseudo, and that the pseudo will\n\
5848	eventually be allocated to @var{N} @code{word_mode} hard registers.\n\
5849	Failure to prevent this kind of mode change will result in the\n\
5850	entire @code{raw_reg_mode} being modified instead of the partial\n\
5851	value that the middle-end intended.",
5852	bool, (machine_mode from, machine_mode to, reg_class_t rclass),
5853	hook_bool_mode_mode_reg_class_t_true)
5854
5855	/* Change pseudo allocno class calculated by IRA. */
5856	DEFHOOK
5857	(ira_change_pseudo_allocno_class,
5858	"A target hook which can change allocno class for given pseudo from\n\
5859	allocno and best class calculated by IRA.\n\
5860	\n\
5861	The default version of this target hook always returns given class.",
5862	reg_class_t, (int, reg_class_t, reg_class_t),
5863	default_ira_change_pseudo_allocno_class)
5864
5865	/* Return true if we use LRA instead of reload. */
5866	DEFHOOK
5867	(lra_p,
5868	"A target hook which returns true if we use LRA instead of reload pass.\n\
5869	\n\
5870	The default version of this target hook returns true. New ports\n\
5871	should use LRA, and existing ports are encouraged to convert.",
5872	bool, (void),
5873	default_lra_p)
5874
5875	/* Return register priority of given hard regno for the current target. */
5876	DEFHOOK
5877	(register_priority,
5878	"A target hook which returns the register priority number to which the\n\
5879	register @var{hard_regno} belongs to. The bigger the number, the\n\
5880	more preferable the hard register usage (when all other conditions are\n\
5881	the same). This hook can be used to prefer some hard register over\n\
5882	others in LRA. For example, some x86-64 register usage needs\n\
5883	additional prefix which makes instructions longer. The hook can\n\
5884	return lower priority number for such registers make them less favorable\n\
5885	and as result making the generated code smaller.\n\
5886	\n\
5887	The default version of this target hook returns always zero.",
5888	int, (int),
5889	default_register_priority)
5890
5891	/* Return true if we need register usage leveling. */
5892	DEFHOOK
5893	(register_usage_leveling_p,
5894	"A target hook which returns true if we need register usage leveling.\n\
5895	That means if a few hard registers are equally good for the\n\
5896	assignment, we choose the least used hard register. The register\n\
5897	usage leveling may be profitable for some targets. Don't use the\n\
5898	usage leveling for targets with conditional execution or targets\n\
5899	with big register files as it hurts if-conversion and cross-jumping\n\
5900	optimizations.\n\
5901	\n\
5902	The default version of this target hook returns always false.",
5903	bool, (void),
5904	default_register_usage_leveling_p)
5905
5906	/* Return true if maximal address displacement can be different. */
5907	DEFHOOK
5908	(different_addr_displacement_p,
5909	"A target hook which returns true if an address with the same structure\n\
5910	can have different maximal legitimate displacement. For example, the\n\
5911	displacement can depend on memory mode or on operand combinations in\n\
5912	the insn.\n\
5913	\n\
5914	The default version of this target hook returns always false.",
5915	bool, (void),
5916	default_different_addr_displacement_p)
5917
5918	/* Determine class for spilling pseudos of given mode into registers
5919	instead of memory. */
5920	DEFHOOK
5921	(spill_class,
5922	"This hook defines a class of registers which could be used for spilling\n\
5923	pseudos of the given mode and class, or @code{NO_REGS} if only memory\n\
5924	should be used. Not defining this hook is equivalent to returning\n\
5925	@code{NO_REGS} for all inputs.",
5926	reg_class_t, (reg_class_t, machine_mode),
5927	NULL)
5928
5929	/* Determine an additional allocno class. */
5930	DEFHOOK
5931	(additional_allocno_class_p,
5932	"This hook should return @code{true} if given class of registers should\n\
5933	be an allocno class in any way. Usually RA uses only one register\n\
5934	class from all classes containing the same register set. In some\n\
5935	complicated cases, you need to have two or more such classes as\n\
5936	allocno ones for RA correct work. Not defining this hook is\n\
5937	equivalent to returning @code{false} for all inputs.",
5938	bool, (reg_class_t),
5939	hook_bool_reg_class_t_false)
5940
5941	DEFHOOK
5942	(cstore_mode,
5943	"This hook defines the machine mode to use for the boolean result of\n\
5944	conditional store patterns. The ICODE argument is the instruction code\n\
5945	for the cstore being performed. Not definiting this hook is the same\n\
5946	as accepting the mode encoded into operand 0 of the cstore expander\n\
5947	patterns.",
5948	scalar_int_mode, (enum insn_code icode),
5949	default_cstore_mode)
5950
5951	/* This target hook allows the backend to compute the register pressure
5952	classes to use. */
5953	DEFHOOK
5954	(compute_pressure_classes,
5955	"A target hook which lets a backend compute the set of pressure classes to\n\
5956	be used by those optimization passes which take register pressure into\n\
5957	account, as opposed to letting IRA compute them. It returns the number of\n\
5958	register classes stored in the array @var{pressure_classes}.",
5959	int, (enum reg_class *pressure_classes), NULL)
5960
5961	/* True if a structure, union or array with MODE containing FIELD should
5962	be accessed using BLKmode. */
5963	DEFHOOK
5964	(member_type_forces_blk,
5965	"Return true if a structure, union or array containing @var{field} should\n\
5966	be accessed using @code{BLKMODE}.\n\
5967	\n\
5968	If @var{field} is the only field in the structure, @var{mode} is its\n\
5969	mode, otherwise @var{mode} is VOIDmode. @var{mode} is provided in the\n\
5970	case where structures of one field would require the structure's mode to\n\
5971	retain the field's mode.\n\
5972	\n\
5973	Normally, this is not needed.",
5974	bool, (const_tree field, machine_mode mode),
5975	default_member_type_forces_blk)
5976
5977	/* See tree-ssa-math-opts.cc:divmod_candidate_p for conditions
5978	that gate the divod transform. */
5979	DEFHOOK
5980	(expand_divmod_libfunc,
5981	"Define this hook for enabling divmod transform if the port does not have\n\
5982	hardware divmod insn but defines target-specific divmod libfuncs.",
5983	void, (rtx libfunc, machine_mode mode, rtx op0, rtx op1, rtx *quot, rtx *rem),
5984	NULL)
5985
5986	/* Return the class for a secondary reload, and fill in extra information. */
5987	DEFHOOK
5988	(secondary_reload,
5989	"Many machines have some registers that cannot be copied directly to or\n\
5990	from memory or even from other types of registers. An example is the\n\
5991	@samp{MQ} register, which on most machines, can only be copied to or\n\
5992	from general registers, but not memory. Below, we shall be using the\n\
5993	term 'intermediate register' when a move operation cannot be performed\n\
5994	directly, but has to be done by copying the source into the intermediate\n\
5995	register first, and then copying the intermediate register to the\n\
5996	destination. An intermediate register always has the same mode as\n\
5997	source and destination. Since it holds the actual value being copied,\n\
5998	reload might apply optimizations to re-use an intermediate register\n\
5999	and eliding the copy from the source when it can determine that the\n\
6000	intermediate register still holds the required value.\n\
6001	\n\
6002	Another kind of secondary reload is required on some machines which\n\
6003	allow copying all registers to and from memory, but require a scratch\n\
6004	register for stores to some memory locations (e.g., those with symbolic\n\
6005	address on the RT, and those with certain symbolic address on the SPARC\n\
6006	when compiling PIC)@. Scratch registers need not have the same mode\n\
6007	as the value being copied, and usually hold a different value than\n\
6008	that being copied. Special patterns in the md file are needed to\n\
6009	describe how the copy is performed with the help of the scratch register;\n\
6010	these patterns also describe the number, register class(es) and mode(s)\n\
6011	of the scratch register(s).\n\
6012	\n\
6013	In some cases, both an intermediate and a scratch register are required.\n\
6014	\n\
6015	For input reloads, this target hook is called with nonzero @var{in_p},\n\
6016	and @var{x} is an rtx that needs to be copied to a register of class\n\
6017	@var{reload_class} in @var{reload_mode}. For output reloads, this target\n\
6018	hook is called with zero @var{in_p}, and a register of class @var{reload_class}\n\
6019	needs to be copied to rtx @var{x} in @var{reload_mode}.\n\
6020	\n\
6021	If copying a register of @var{reload_class} from/to @var{x} requires\n\
6022	an intermediate register, the hook @code{secondary_reload} should\n\
6023	return the register class required for this intermediate register.\n\
6024	If no intermediate register is required, it should return NO_REGS.\n\
6025	If more than one intermediate register is required, describe the one\n\
6026	that is closest in the copy chain to the reload register.\n\
6027	\n\
6028	If scratch registers are needed, you also have to describe how to\n\
6029	perform the copy from/to the reload register to/from this\n\
6030	closest intermediate register. Or if no intermediate register is\n\
6031	required, but still a scratch register is needed, describe the\n\
6032	copy from/to the reload register to/from the reload operand @var{x}.\n\
6033	\n\
6034	You do this by setting @code{sri->icode} to the instruction code of a pattern\n\
6035	in the md file which performs the move. Operands 0 and 1 are the output\n\
6036	and input of this copy, respectively. Operands from operand 2 onward are\n\
6037	for scratch operands. These scratch operands must have a mode, and a\n\
6038	single-register-class\n\
6039	@c [later: or memory]\n\
6040	output constraint.\n\
6041	\n\
6042	When an intermediate register is used, the @code{secondary_reload}\n\
6043	hook will be called again to determine how to copy the intermediate\n\
6044	register to/from the reload operand @var{x}, so your hook must also\n\
6045	have code to handle the register class of the intermediate operand.\n\
6046	\n\
6047	@c [For later: maybe we'll allow multi-alternative reload patterns -\n\
6048	@c the port maintainer could name a mov<mode> pattern that has clobbers -\n\
6049	@c and match the constraints of input and output to determine the required\n\
6050	@c alternative. A restriction would be that constraints used to match\n\
6051	@c against reloads registers would have to be written as register class\n\
6052	@c constraints, or we need a new target macro / hook that tells us if an\n\
6053	@c arbitrary constraint can match an unknown register of a given class.\n\
6054	@c Such a macro / hook would also be useful in other places.]\n\
6055	\n\
6056	\n\
6057	@var{x} might be a pseudo-register or a @code{subreg} of a\n\
6058	pseudo-register, which could either be in a hard register or in memory.\n\
6059	Use @code{true_regnum} to find out; it will return @minus{}1 if the pseudo is\n\
6060	in memory and the hard register number if it is in a register.\n\
6061	\n\
6062	Scratch operands in memory (constraint @code{\"=m\"} / @code{\"=&m\"}) are\n\
6063	currently not supported. For the time being, you will have to continue\n\
6064	to use @code{TARGET_SECONDARY_MEMORY_NEEDED} for that purpose.\n\
6065	\n\
6066	@code{copy_cost} also uses this target hook to find out how values are\n\
6067	copied. If you want it to include some extra cost for the need to allocate\n\
6068	(a) scratch register(s), set @code{sri->extra_cost} to the additional cost.\n\
6069	Or if two dependent moves are supposed to have a lower cost than the sum\n\
6070	of the individual moves due to expected fortuitous scheduling and/or special\n\
6071	forwarding logic, you can set @code{sri->extra_cost} to a negative amount.",
6072	reg_class_t,
6073	(bool in_p, rtx x, reg_class_t reload_class, machine_mode reload_mode,
6074	secondary_reload_info *sri),
6075	default_secondary_reload)
6076
6077	DEFHOOK
6078	(secondary_memory_needed,
6079	"Certain machines have the property that some registers cannot be copied\n\
6080	to some other registers without using memory. Define this hook on\n\
6081	those machines to return true if objects of mode @var{m} in registers\n\
6082	of @var{class1} can only be copied to registers of class @var{class2} by\n\
6083	storing a register of @var{class1} into memory and loading that memory\n\
6084	location into a register of @var{class2}. The default definition returns\n\
6085	false for all inputs.",
6086	bool, (machine_mode mode, reg_class_t class1, reg_class_t class2),
6087	hook_bool_mode_reg_class_t_reg_class_t_false)
6088
6089	DEFHOOK
6090	(secondary_memory_needed_mode,
6091	"If @code{TARGET_SECONDARY_MEMORY_NEEDED} tells the compiler to use memory\n\
6092	when moving between two particular registers of mode @var{mode},\n\
6093	this hook specifies the mode that the memory should have.\n\
6094	\n\
6095	The default depends on @code{TARGET_LRA_P}. Without LRA, the default\n\
6096	is to use a word-sized mode for integral modes that are smaller than a\n\
6097	a word. This is right thing to do on most machines because it ensures\n\
6098	that all bits of the register are copied and prevents accesses to the\n\
6099	registers in a narrower mode, which some machines prohibit for\n\
6100	floating-point registers.\n\
6101	\n\
6102	However, this default behavior is not correct on some machines, such as\n\
6103	the DEC Alpha, that store short integers in floating-point registers\n\
6104	differently than in integer registers. On those machines, the default\n\
6105	widening will not work correctly and you must define this hook to\n\
6106	suppress that widening in some cases. See the file @file{alpha.cc} for\n\
6107	details.\n\
6108	\n\
6109	With LRA, the default is to use @var{mode} unmodified.",
6110	machine_mode, (machine_mode mode),
6111	default_secondary_memory_needed_mode)
6112
6113	/* Given an rtx X being reloaded into a reg required to be in class CLASS,
6114	return the class of reg to actually use. */
6115	DEFHOOK
6116	(preferred_reload_class,
6117	"A target hook that places additional restrictions on the register class\n\
6118	to use when it is necessary to copy value @var{x} into a register in class\n\
6119	@var{rclass}. The value is a register class; perhaps @var{rclass}, or perhaps\n\
6120	another, smaller class.\n\
6121	\n\
6122	The default version of this hook always returns value of @code{rclass} argument.\n\
6123	\n\
6124	Sometimes returning a more restrictive class makes better code. For\n\
6125	example, on the 68000, when @var{x} is an integer constant that is in range\n\
6126	for a @samp{moveq} instruction, the value of this macro is always\n\
6127	@code{DATA_REGS} as long as @var{rclass} includes the data registers.\n\
6128	Requiring a data register guarantees that a @samp{moveq} will be used.\n\
6129	\n\
6130	One case where @code{TARGET_PREFERRED_RELOAD_CLASS} must not return\n\
6131	@var{rclass} is if @var{x} is a legitimate constant which cannot be\n\
6132	loaded into some register class. By returning @code{NO_REGS} you can\n\
6133	force @var{x} into a memory location. For example, rs6000 can load\n\
6134	immediate values into general-purpose registers, but does not have an\n\
6135	instruction for loading an immediate value into a floating-point\n\
6136	register, so @code{TARGET_PREFERRED_RELOAD_CLASS} returns @code{NO_REGS} when\n\
6137	@var{x} is a floating-point constant. If the constant can't be loaded\n\
6138	into any kind of register, code generation will be better if\n\
6139	@code{TARGET_LEGITIMATE_CONSTANT_P} makes the constant illegitimate instead\n\
6140	of using @code{TARGET_PREFERRED_RELOAD_CLASS}.\n\
6141	\n\
6142	If an insn has pseudos in it after register allocation, reload will go\n\
6143	through the alternatives and call repeatedly @code{TARGET_PREFERRED_RELOAD_CLASS}\n\
6144	to find the best one. Returning @code{NO_REGS}, in this case, makes\n\
6145	reload add a @code{!} in front of the constraint: the x86 back-end uses\n\
6146	this feature to discourage usage of 387 registers when math is done in\n\
6147	the SSE registers (and vice versa).",
6148	reg_class_t,
6149	(rtx x, reg_class_t rclass),
6150	default_preferred_reload_class)
6151
6152	/* Like TARGET_PREFERRED_RELOAD_CLASS, but for output reloads instead of
6153	input reloads. */
6154	DEFHOOK
6155	(preferred_output_reload_class,
6156	"Like @code{TARGET_PREFERRED_RELOAD_CLASS}, but for output reloads instead of\n\
6157	input reloads.\n\
6158	\n\
6159	The default version of this hook always returns value of @code{rclass}\n\
6160	argument.\n\
6161	\n\
6162	You can also use @code{TARGET_PREFERRED_OUTPUT_RELOAD_CLASS} to discourage\n\
6163	reload from using some alternatives, like @code{TARGET_PREFERRED_RELOAD_CLASS}.",
6164	reg_class_t,
6165	(rtx x, reg_class_t rclass),
6166	default_preferred_output_reload_class)
6167
6168	DEFHOOK
6169	(select_early_remat_modes,
6170	"On some targets, certain modes cannot be held in registers around a\n\
6171	standard ABI call and are relatively expensive to spill to the stack.\n\
6172	The early rematerialization pass can help in such cases by aggressively\n\
6173	recomputing values after calls, so that they don't need to be spilled.\n\
6174	\n\
6175	This hook returns the set of such modes by setting the associated bits\n\
6176	in @var{modes}. The default implementation selects no modes, which has\n\
6177	the effect of disabling the early rematerialization pass.",
6178	void, (sbitmap modes),
6179	default_select_early_remat_modes)
6180
6181	DEFHOOK
6182	(class_likely_spilled_p,
6183	"A target hook which returns @code{true} if pseudos that have been assigned\n\
6184	to registers of class @var{rclass} would likely be spilled because\n\
6185	registers of @var{rclass} are needed for spill registers.\n\
6186	\n\
6187	The default version of this target hook returns @code{true} if @var{rclass}\n\
6188	has exactly one register and @code{false} otherwise. On most machines, this\n\
6189	default should be used. For generally register-starved machines, such as\n\
6190	i386, or machines with right register constraints, such as SH, this hook\n\
6191	can be used to avoid excessive spilling.\n\
6192	\n\
6193	This hook is also used by some of the global intra-procedural code\n\
6194	transformations to throtle code motion, to avoid increasing register\n\
6195	pressure.",
6196	bool, (reg_class_t rclass),
6197	default_class_likely_spilled_p)
6198
6199	/* Return the maximum number of consecutive registers
6200	needed to represent mode MODE in a register of class RCLASS. */
6201	DEFHOOK
6202	(class_max_nregs,
6203	"A target hook returns the maximum number of consecutive registers\n\
6204	of class @var{rclass} needed to hold a value of mode @var{mode}.\n\
6205	\n\
6206	This is closely related to the macro @code{TARGET_HARD_REGNO_NREGS}.\n\
6207	In fact, the value returned by @code{TARGET_CLASS_MAX_NREGS (@var{rclass},\n\
6208	@var{mode})} target hook should be the maximum value of\n\
6209	@code{TARGET_HARD_REGNO_NREGS (@var{regno}, @var{mode})} for all @var{regno}\n\
6210	values in the class @var{rclass}.\n\
6211	\n\
6212	This target hook helps control the handling of multiple-word values\n\
6213	in the reload pass.\n\
6214	\n\
6215	The default version of this target hook returns the size of @var{mode}\n\
6216	in words.",
6217	unsigned char, (reg_class_t rclass, machine_mode mode),
6218	default_class_max_nregs)
6219
6220	DEFHOOK
6221	(preferred_rename_class,
6222	"A target hook that places additional preference on the register\n\
6223	class to use when it is necessary to rename a register in class\n\
6224	@var{rclass} to another class, or perhaps @var{NO_REGS}, if no\n\
6225	preferred register class is found or hook @code{preferred_rename_class}\n\
6226	is not implemented.\n\
6227	Sometimes returning a more restrictive class makes better code. For\n\
6228	example, on ARM, thumb-2 instructions using @code{LO_REGS} may be\n\
6229	smaller than instructions using @code{GENERIC_REGS}. By returning\n\
6230	@code{LO_REGS} from @code{preferred_rename_class}, code size can\n\
6231	be reduced.",
6232	reg_class_t, (reg_class_t rclass),
6233	default_preferred_rename_class)
6234
6235	/* This target hook allows the backend to avoid unsafe substitution
6236	during register allocation. */
6237	DEFHOOK
6238	(cannot_substitute_mem_equiv_p,
6239	"A target hook which returns @code{true} if @var{subst} can't\n\
6240	substitute safely pseudos with equivalent memory values during\n\
6241	register allocation.\n\
6242	The default version of this target hook returns @code{false}.\n\
6243	On most machines, this default should be used. For generally\n\
6244	machines with non orthogonal register usage for addressing, such\n\
6245	as SH, this hook can be used to avoid excessive spilling.",
6246	bool, (rtx subst),
6247	hook_bool_rtx_false)
6248
6249	/* This target hook allows the backend to legitimize base plus
6250	displacement addressing. */
6251	DEFHOOK
6252	(legitimize_address_displacement,
6253	"This hook tries to split address offset @var{orig_offset} into\n\
6254	two parts: one that should be added to the base address to create\n\
6255	a local anchor point, and an additional offset that can be applied\n\
6256	to the anchor to address a value of mode @var{mode}. The idea is that\n\
6257	the local anchor could be shared by other accesses to nearby locations.\n\
6258	\n\
6259	The hook returns true if it succeeds, storing the offset of the\n\
6260	anchor from the base in @var{offset1} and the offset of the final address\n\
6261	from the anchor in @var{offset2}. The default implementation returns false.",
6262	bool, (rtx *offset1, rtx *offset2, poly_int64 orig_offset, machine_mode mode),
6263	default_legitimize_address_displacement)
6264
6265	/* This target hook allows the backend to perform additional
6266	processing while initializing for variable expansion. */
6267	DEFHOOK
6268	(expand_to_rtl_hook,
6269	"This hook is called just before expansion into rtl, allowing the target\n\
6270	to perform additional initializations or analysis before the expansion.\n\
6271	For example, the rs6000 port uses it to allocate a scratch stack slot\n\
6272	for use in copying SDmode values between memory and floating point\n\
6273	registers whenever the function being expanded has any SDmode\n\
6274	usage.",
6275	void, (void),
6276	hook_void_void)
6277
6278	/* This target hook allows the backend to perform additional
6279	instantiations on rtx that are not actually in insns yet,
6280	but will be later. */
6281	DEFHOOK
6282	(instantiate_decls,
6283	"This hook allows the backend to perform additional instantiations on rtl\n\
6284	that are not actually in any insns yet, but will be later.",
6285	void, (void),
6286	hook_void_void)
6287
6288	DEFHOOK
6289	(hard_regno_nregs,
6290	"This hook returns the number of consecutive hard registers, starting\n\
6291	at register number @var{regno}, required to hold a value of mode\n\
6292	@var{mode}. This hook must never return zero, even if a register\n\
6293	cannot hold the requested mode - indicate that with\n\
6294	@code{TARGET_HARD_REGNO_MODE_OK} and/or\n\
6295	@code{TARGET_CAN_CHANGE_MODE_CLASS} instead.\n\
6296	\n\
6297	The default definition returns the number of words in @var{mode}.",
6298	unsigned int, (unsigned int regno, machine_mode mode),
6299	default_hard_regno_nregs)
6300
6301	DEFHOOK
6302	(hard_regno_mode_ok,
6303	"This hook returns true if it is permissible to store a value\n\
6304	of mode @var{mode} in hard register number @var{regno} (or in several\n\
6305	registers starting with that one). The default definition returns true\n\
6306	unconditionally.\n\
6307	\n\
6308	You need not include code to check for the numbers of fixed registers,\n\
6309	because the allocation mechanism considers them to be always occupied.\n\
6310	\n\
6311	@cindex register pairs\n\
6312	On some machines, double-precision values must be kept in even/odd\n\
6313	register pairs. You can implement that by defining this hook to reject\n\
6314	odd register numbers for such modes.\n\
6315	\n\
6316	The minimum requirement for a mode to be OK in a register is that the\n\
6317	@samp{mov@var{mode}} instruction pattern support moves between the\n\
6318	register and other hard register in the same class and that moving a\n\
6319	value into the register and back out not alter it.\n\
6320	\n\
6321	Since the same instruction used to move @code{word_mode} will work for\n\
6322	all narrower integer modes, it is not necessary on any machine for\n\
6323	this hook to distinguish between these modes, provided you define\n\
6324	patterns @samp{movhi}, etc., to take advantage of this. This is\n\
6325	useful because of the interaction between @code{TARGET_HARD_REGNO_MODE_OK}\n\
6326	and @code{TARGET_MODES_TIEABLE_P}; it is very desirable for all integer\n\
6327	modes to be tieable.\n\
6328	\n\
6329	Many machines have special registers for floating point arithmetic.\n\
6330	Often people assume that floating point machine modes are allowed only\n\
6331	in floating point registers. This is not true. Any registers that\n\
6332	can hold integers can safely @emph{hold} a floating point machine\n\
6333	mode, whether or not floating arithmetic can be done on it in those\n\
6334	registers. Integer move instructions can be used to move the values.\n\
6335	\n\
6336	On some machines, though, the converse is true: fixed-point machine\n\
6337	modes may not go in floating registers. This is true if the floating\n\
6338	registers normalize any value stored in them, because storing a\n\
6339	non-floating value there would garble it. In this case,\n\
6340	@code{TARGET_HARD_REGNO_MODE_OK} should reject fixed-point machine modes in\n\
6341	floating registers. But if the floating registers do not automatically\n\
6342	normalize, if you can store any bit pattern in one and retrieve it\n\
6343	unchanged without a trap, then any machine mode may go in a floating\n\
6344	register, so you can define this hook to say so.\n\
6345	\n\
6346	The primary significance of special floating registers is rather that\n\
6347	they are the registers acceptable in floating point arithmetic\n\
6348	instructions. However, this is of no concern to\n\
6349	@code{TARGET_HARD_REGNO_MODE_OK}. You handle it by writing the proper\n\
6350	constraints for those instructions.\n\
6351	\n\
6352	On some machines, the floating registers are especially slow to access,\n\
6353	so that it is better to store a value in a stack frame than in such a\n\
6354	register if floating point arithmetic is not being done. As long as the\n\
6355	floating registers are not in class @code{GENERAL_REGS}, they will not\n\
6356	be used unless some pattern's constraint asks for one.",
6357	bool, (unsigned int regno, machine_mode mode),
6358	hook_bool_uint_mode_true)
6359
6360	DEFHOOK
6361	(modes_tieable_p,
6362	"This hook returns true if a value of mode @var{mode1} is accessible\n\
6363	in mode @var{mode2} without copying.\n\
6364	\n\
6365	If @code{TARGET_HARD_REGNO_MODE_OK (@var{r}, @var{mode1})} and\n\
6366	@code{TARGET_HARD_REGNO_MODE_OK (@var{r}, @var{mode2})} are always\n\
6367	the same for any @var{r}, then\n\
6368	@code{TARGET_MODES_TIEABLE_P (@var{mode1}, @var{mode2})}\n\
6369	should be true. If they differ for any @var{r}, you should define\n\
6370	this hook to return false unless some other mechanism ensures the\n\
6371	accessibility of the value in a narrower mode.\n\
6372	\n\
6373	You should define this hook to return true in as many cases as\n\
6374	possible since doing so will allow GCC to perform better register\n\
6375	allocation. The default definition returns true unconditionally.",
6376	bool, (machine_mode mode1, machine_mode mode2),
6377	hook_bool_mode_mode_true)
6378
6379	/* Return true if is OK to use a hard register REGNO as scratch register
6380	in peephole2. */
6381	DEFHOOK
6382	(hard_regno_scratch_ok,
6383	"This target hook should return @code{true} if it is OK to use a hard register\n\
6384	@var{regno} as scratch reg in peephole2.\n\
6385	\n\
6386	One common use of this macro is to prevent using of a register that\n\
6387	is not saved by a prologue in an interrupt handler.\n\
6388	\n\
6389	The default version of this hook always returns @code{true}.",
6390	bool, (unsigned int regno),
6391	default_hard_regno_scratch_ok)
6392
6393	DEFHOOK
6394	(hard_regno_call_part_clobbered,
6395	"ABIs usually specify that calls must preserve the full contents\n\
6396	of a particular register, or that calls can alter any part of a\n\
6397	particular register. This information is captured by the target macro\n\
6398	@code{CALL_REALLY_USED_REGISTERS}. However, some ABIs specify that calls\n\
6399	must preserve certain bits of a particular register but can alter others.\n\
6400	This hook should return true if this applies to at least one of the\n\
6401	registers in @samp{(reg:@var{mode} @var{regno})}, and if as a result the\n\
6402	call would alter part of the @var{mode} value. For example, if a call\n\
6403	preserves the low 32 bits of a 64-bit hard register @var{regno} but can\n\
6404	clobber the upper 32 bits, this hook should return true for a 64-bit mode\n\
6405	but false for a 32-bit mode.\n\
6406	\n\
6407	The value of @var{abi_id} comes from the @code{predefined_function_abi}\n\
6408	structure that describes the ABI of the call; see the definition of the\n\
6409	structure for more details. If (as is usual) the target uses the same ABI\n\
6410	for all functions in a translation unit, @var{abi_id} is always 0.\n\
6411	\n\
6412	The default implementation returns false, which is correct\n\
6413	for targets that don't have partly call-clobbered registers.",
6414	bool, (unsigned int abi_id, unsigned int regno, machine_mode mode),
6415	hook_bool_uint_uint_mode_false)
6416
6417	DEFHOOK
6418	(get_multilib_abi_name,
6419	"This hook returns name of multilib ABI name.",
6420	const char *, (void),
6421	hook_constcharptr_void_null)
6422
6423	/* Return the smallest number of different values for which it is best to
6424	use a jump-table instead of a tree of conditional branches. */
6425	DEFHOOK
6426	(case_values_threshold,
6427	"This function return the smallest number of different values for which it\n\
6428	is best to use a jump-table instead of a tree of conditional branches.\n\
6429	The default is four for machines with a @code{casesi} instruction and\n\
6430	five otherwise. This is best for most machines.",
6431	unsigned int, (void),
6432	default_case_values_threshold)
6433
6434	DEFHOOK
6435	(starting_frame_offset,
6436	"This hook returns the offset from the frame pointer to the first local\n\
6437	variable slot to be allocated. If @code{FRAME_GROWS_DOWNWARD}, it is the\n\
6438	offset to @emph{end} of the first slot allocated, otherwise it is the\n\
6439	offset to @emph{beginning} of the first slot allocated. The default\n\
6440	implementation returns 0.",
6441	HOST_WIDE_INT, (void),
6442	hook_hwi_void_0)
6443
6444	/* Optional callback to advise the target to compute the frame layout. */
6445	DEFHOOK
6446	(compute_frame_layout,
6447	"This target hook is called once each time the frame layout needs to be\n\
6448	recalculated. The calculations can be cached by the target and can then\n\
6449	be used by @code{INITIAL_ELIMINATION_OFFSET} instead of re-computing the\n\
6450	layout on every invocation of that hook. This is particularly useful\n\
6451	for targets that have an expensive frame layout function. Implementing\n\
6452	this callback is optional.",
6453	void, (void),
6454	hook_void_void)
6455
6456	/* Return true if a function must have and use a frame pointer. */
6457	DEFHOOK
6458	(frame_pointer_required,
6459	"This target hook should return @code{true} if a function must have and use\n\
6460	a frame pointer. This target hook is called in the reload pass. If its return\n\
6461	value is @code{true} the function will have a frame pointer.\n\
6462	\n\
6463	This target hook can in principle examine the current function and decide\n\
6464	according to the facts, but on most machines the constant @code{false} or the\n\
6465	constant @code{true} suffices. Use @code{false} when the machine allows code\n\
6466	to be generated with no frame pointer, and doing so saves some time or space.\n\
6467	Use @code{true} when there is no possible advantage to avoiding a frame\n\
6468	pointer.\n\
6469	\n\
6470	In certain cases, the compiler does not know how to produce valid code\n\
6471	without a frame pointer. The compiler recognizes those cases and\n\
6472	automatically gives the function a frame pointer regardless of what\n\
6473	@code{targetm.frame_pointer_required} returns. You don't need to worry about\n\
6474	them.\n\
6475	\n\
6476	In a function that does not require a frame pointer, the frame pointer\n\
6477	register can be allocated for ordinary usage, unless you mark it as a\n\
6478	fixed register. See @code{FIXED_REGISTERS} for more information.\n\
6479	\n\
6480	Default return value is @code{false}.",
6481	bool, (void),
6482	hook_bool_void_false)
6483
6484	/* Returns true if the compiler is allowed to try to replace register number
6485	from-reg with register number to-reg. */
6486	DEFHOOK
6487	(can_eliminate,
6488	"This target hook should return @code{true} if the compiler is allowed to\n\
6489	try to replace register number @var{from_reg} with register number\n\
6490	@var{to_reg}. This target hook will usually be @code{true}, since most of the\n\
6491	cases preventing register elimination are things that the compiler already\n\
6492	knows about.\n\
6493	\n\
6494	Default return value is @code{true}.",
6495	bool, (const int from_reg, const int to_reg),
6496	hook_bool_const_int_const_int_true)
6497
6498	/* Modify any or all of fixed_regs, call_used_regs, global_regs,
6499	reg_names, and reg_class_contents to account of the vagaries of the
6500	target. */
6501	DEFHOOK
6502	(conditional_register_usage,
6503	"This hook may conditionally modify five variables\n\
6504	@code{fixed_regs}, @code{call_used_regs}, @code{global_regs},\n\
6505	@code{reg_names}, and @code{reg_class_contents}, to take into account\n\
6506	any dependence of these register sets on target flags. The first three\n\
6507	of these are of type @code{char []} (interpreted as boolean vectors).\n\
6508	@code{global_regs} is a @code{const char *[]}, and\n\
6509	@code{reg_class_contents} is a @code{HARD_REG_SET}. Before the macro is\n\
6510	called, @code{fixed_regs}, @code{call_used_regs},\n\
6511	@code{reg_class_contents}, and @code{reg_names} have been initialized\n\
6512	from @code{FIXED_REGISTERS}, @code{CALL_USED_REGISTERS},\n\
6513	@code{REG_CLASS_CONTENTS}, and @code{REGISTER_NAMES}, respectively.\n\
6514	@code{global_regs} has been cleared, and any @option{-ffixed-@var{reg}},\n\
6515	@option{-fcall-used-@var{reg}} and @option{-fcall-saved-@var{reg}}\n\
6516	command options have been applied.\n\
6517	\n\
6518	@cindex disabling certain registers\n\
6519	@cindex controlling register usage\n\
6520	If the usage of an entire class of registers depends on the target\n\
6521	flags, you may indicate this to GCC by using this macro to modify\n\
6522	@code{fixed_regs} and @code{call_used_regs} to 1 for each of the\n\
6523	registers in the classes which should not be used by GCC@. Also make\n\
6524	@code{define_register_constraint}s return @code{NO_REGS} for constraints\n\
6525	that shouldn't be used.\n\
6526	\n\
6527	(However, if this class is not included in @code{GENERAL_REGS} and all\n\
6528	of the insn patterns whose constraints permit this class are\n\
6529	controlled by target switches, then GCC will automatically avoid using\n\
6530	these registers when the target switches are opposed to them.)",
6531	void, (void),
6532	hook_void_void)
6533
6534	DEFHOOK
6535	(stack_clash_protection_alloca_probe_range,
6536	"Some targets have an ABI defined interval for which no probing needs to be done.\n\
6537	When a probe does need to be done this same interval is used as the probe distance\n\
6538	up when doing stack clash protection for alloca.\n\
6539	On such targets this value can be set to override the default probing up interval.\n\
6540	Define this variable to return nonzero if such a probe range is required or zero otherwise.\n\
6541	Defining this hook also requires your functions which make use of alloca to have at least 8 byes\n\
6542	of outgoing arguments. If this is not the case the stack will be corrupted.\n\
6543	You need not define this macro if it would always have the value zero.",
6544	HOST_WIDE_INT, (void),
6545	default_stack_clash_protection_alloca_probe_range)
6546
6547
6548	/* Functions specific to the C family of frontends. */
6549	#undef HOOK_PREFIX
6550	#define HOOK_PREFIX "TARGET_C_"
6551	HOOK_VECTOR (TARGET_C, c)
6552
6553	/* ??? Documenting this hook requires a GFDL license grant. */
6554	DEFHOOK_UNDOC
6555	(mode_for_suffix,
6556	"Return machine mode for non-standard constant literal suffix @var{c},\
6557	or VOIDmode if non-standard suffixes are unsupported.",
6558	machine_mode, (char c),
6559	default_mode_for_suffix)
6560
6561	DEFHOOK
6562	(excess_precision,
6563	"Return a value, with the same meaning as the C99 macro\n\
6564	@code{FLT_EVAL_METHOD} that describes which excess precision should be\n\
6565	applied. @var{type} is either @code{EXCESS_PRECISION_TYPE_IMPLICIT},\n\
6566	@code{EXCESS_PRECISION_TYPE_FAST},\n\
6567	@code{EXCESS_PRECISION_TYPE_STANDARD}, or\n\
6568	@code{EXCESS_PRECISION_TYPE_FLOAT16}. For\n\
6569	@code{EXCESS_PRECISION_TYPE_IMPLICIT}, the target should return which\n\
6570	precision and range operations will be implictly evaluated in regardless\n\
6571	of the excess precision explicitly added. For\n\
6572	@code{EXCESS_PRECISION_TYPE_STANDARD}, \n\
6573	@code{EXCESS_PRECISION_TYPE_FLOAT16}, and\n\
6574	@code{EXCESS_PRECISION_TYPE_FAST}, the target should return the\n\
6575	explicit excess precision that should be added depending on the\n\
6576	value set for @option{-fexcess-precision=@r{[}standard@r{|}fast@r{|}16@r{]}}.\n\
6577	Note that unpredictable explicit excess precision does not make sense,\n\
6578	so a target should never return @code{FLT_EVAL_METHOD_UNPREDICTABLE}\n\
6579	when @var{type} is @code{EXCESS_PRECISION_TYPE_STANDARD},\n\
6580	@code{EXCESS_PRECISION_TYPE_FLOAT16} or\n\
6581	@code{EXCESS_PRECISION_TYPE_FAST}.",
6582	enum flt_eval_method, (enum excess_precision_type type),
6583	default_excess_precision)
6584
6585	/* Return true if _BitInt(N) is supported and fill details about it into
6586	*INFO. */
6587	DEFHOOK
6588	(bitint_type_info,
6589	"This target hook returns true if @code{_BitInt(@var{N})} is supported and\n\
6590	provides details on it. @code{_BitInt(@var{N})} is to be represented as\n\
6591	series of @code{info->abi_limb_mode}\n\
6592	@code{CEIL (@var{N}, GET_MODE_PRECISION (info->abi_limb_mode))} limbs,\n\
6593	ordered from least significant to most significant if\n\
6594	@code{!info->big_endian}, otherwise from most significant to least\n\
6595	significant. If @code{info->extended} is false, the bits above or equal to\n\
6596	@var{N} are undefined when stored in a register or memory, otherwise they\n\
6597	are zero or sign extended depending on if it is\n\
6598	@code{unsigned _BitInt(@var{N})} or one of @code{_BitInt(@var{N})} or\n\
6599	@code{signed _BitInt(@var{N})}. Alignment of the type is\n\
6600	@code{GET_MODE_ALIGNMENT (info->limb_mode)}.",
6601	bool, (int n, struct bitint_info *info),
6602	default_bitint_type_info)
6603
6604	DEFHOOK
6605	(mode_for_floating_type,
6606	"Return machine mode for a C floating point type which is indicated by\n\
6607	a given @code{enum tree_index} @var{ti}, @var{ti} should be\n\
6608	@code{TI_FLOAT_TYPE}, @code{TI_DOUBLE_TYPE} or @code{TI_LONG_DOUBLE_TYPE}.\n\
6609	The default implementation returns @code{SFmode} for @code{TI_FLOAT_TYPE},\n\
6610	and @code{DFmode} for @code{TI_DOUBLE_TYPE} or @code{TI_LONG_DOUBLE_TYPE}.",
6611	machine_mode, (enum tree_index ti), default_mode_for_floating_type)
6612
6613	HOOK_VECTOR_END (c)
6614
6615	/* Functions specific to the C++ frontend. */
6616	#undef HOOK_PREFIX
6617	#define HOOK_PREFIX "TARGET_CXX_"
6618	HOOK_VECTOR (TARGET_CXX, cxx)
6619
6620	/* Return the integer type used for guard variables. */
6621	DEFHOOK
6622	(guard_type,
6623	"Define this hook to override the integer type used for guard variables.\n\
6624	These are used to implement one-time construction of static objects. The\n\
6625	default is long_long_integer_type_node.",
6626	tree, (void),
6627	default_cxx_guard_type)
6628
6629	/* Return true if only the low bit of the guard should be tested. */
6630	DEFHOOK
6631	(guard_mask_bit,
6632	"This hook determines how guard variables are used. It should return\n\
6633	@code{false} (the default) if the first byte should be used. A return value of\n\
6634	@code{true} indicates that only the least significant bit should be used.",
6635	bool, (void),
6636	hook_bool_void_false)
6637
6638	/* Returns the size of the array cookie for an array of type. */
6639	DEFHOOK
6640	(get_cookie_size,
6641	"This hook returns the size of the cookie to use when allocating an array\n\
6642	whose elements have the indicated @var{type}. Assumes that it is already\n\
6643	known that a cookie is needed. The default is\n\
6644	@code{max(sizeof (size_t), alignof(type))}, as defined in section 2.7 of the\n\
6645	IA64/Generic C++ ABI@.",
6646	tree, (tree type),
6647	default_cxx_get_cookie_size)
6648
6649	/* Returns true if the element size should be stored in the array cookie. */
6650	DEFHOOK
6651	(cookie_has_size,
6652	"This hook should return @code{true} if the element size should be stored in\n\
6653	array cookies. The default is to return @code{false}.",
6654	bool, (void),
6655	hook_bool_void_false)
6656
6657	/* Allows backends to perform additional processing when
6658	deciding if a class should be exported or imported. */
6659	DEFHOOK
6660	(import_export_class,
6661	"If defined by a backend this hook allows the decision made to export\n\
6662	class @var{type} to be overruled. Upon entry @var{import_export}\n\
6663	will contain 1 if the class is going to be exported, @minus{}1 if it is going\n\
6664	to be imported and 0 otherwise. This function should return the\n\
6665	modified value and perform any other actions necessary to support the\n\
6666	backend's targeted operating system.",
6667	int, (tree type, int import_export), NULL)
6668
6669	/* Returns true if constructors and destructors return "this". */
6670	DEFHOOK
6671	(cdtor_returns_this,
6672	"This hook should return @code{true} if constructors and destructors return\n\
6673	the address of the object created/destroyed. The default is to return\n\
6674	@code{false}.",
6675	bool, (void),
6676	hook_bool_void_false)
6677
6678	/* Returns true if the key method for a class can be an inline
6679	function, so long as it is not declared inline in the class
6680	itself. Returning true is the behavior required by the Itanium C++ ABI. */
6681	DEFHOOK
6682	(key_method_may_be_inline,
6683	"This hook returns true if the key method for a class (i.e., the method\n\
6684	which, if defined in the current translation unit, causes the virtual\n\
6685	table to be emitted) may be an inline function. Under the standard\n\
6686	Itanium C++ ABI the key method may be an inline function so long as\n\
6687	the function is not declared inline in the class definition. Under\n\
6688	some variants of the ABI, an inline function can never be the key\n\
6689	method. The default is to return @code{true}.",
6690	bool, (void),
6691	hook_bool_void_true)
6692
6693	DEFHOOK
6694	(determine_class_data_visibility,
6695	"@var{decl} is a virtual table, virtual table table, typeinfo object,\n\
6696	or other similar implicit class data object that will be emitted with\n\
6697	external linkage in this translation unit. No ELF visibility has been\n\
6698	explicitly specified. If the target needs to specify a visibility\n\
6699	other than that of the containing class, use this hook to set\n\
6700	@code{DECL_VISIBILITY} and @code{DECL_VISIBILITY_SPECIFIED}.",
6701	void, (tree decl),
6702	hook_void_tree)
6703
6704	/* Returns true (the default) if virtual tables and other
6705	similar implicit class data objects are always COMDAT if they
6706	have external linkage. If this hook returns false, then
6707	class data for classes whose virtual table will be emitted in
6708	only one translation unit will not be COMDAT. */
6709	DEFHOOK
6710	(class_data_always_comdat,
6711	"This hook returns true (the default) if virtual tables and other\n\
6712	similar implicit class data objects are always COMDAT if they have\n\
6713	external linkage. If this hook returns false, then class data for\n\
6714	classes whose virtual table will be emitted in only one translation\n\
6715	unit will not be COMDAT.",
6716	bool, (void),
6717	hook_bool_void_true)
6718
6719	/* Returns true (the default) if the RTTI for the basic types,
6720	which is always defined in the C++ runtime, should be COMDAT;
6721	false if it should not be COMDAT. */
6722	DEFHOOK
6723	(library_rtti_comdat,
6724	"This hook returns true (the default) if the RTTI information for\n\
6725	the basic types which is defined in the C++ runtime should always\n\
6726	be COMDAT, false if it should not be COMDAT.",
6727	bool, (void),
6728	hook_bool_void_true)
6729
6730	/* Returns true if __aeabi_atexit should be used to register static
6731	destructors. */
6732	DEFHOOK
6733	(use_aeabi_atexit,
6734	"This hook returns true if @code{__aeabi_atexit} (as defined by the ARM EABI)\n\
6735	should be used to register static destructors when @option{-fuse-cxa-atexit}\n\
6736	is in effect. The default is to return false to use @code{__cxa_atexit}.",
6737	bool, (void),
6738	hook_bool_void_false)
6739
6740	/* Returns true if target may use atexit in the same manner as
6741	__cxa_atexit to register static destructors. */
6742	DEFHOOK
6743	(use_atexit_for_cxa_atexit,
6744	"This hook returns true if the target @code{atexit} function can be used\n\
6745	in the same manner as @code{__cxa_atexit} to register C++ static\n\
6746	destructors. This requires that @code{atexit}-registered functions in\n\
6747	shared libraries are run in the correct order when the libraries are\n\
6748	unloaded. The default is to return false.",
6749	bool, (void),
6750	hook_bool_void_false)
6751
6752	/* Returns modified FUNCTION_TYPE for cdtor callabi. */
6753	DEFHOOK
6754	(adjust_cdtor_callabi_fntype,
6755	"This hook returns a possibly modified @code{FUNCTION_TYPE} for arguments\n\
6756	to @code{__cxa_atexit}, @code{__cxa_thread_atexit} or @code{__cxa_throw}\n\
6757	function pointers. ABIs like mingw32 require special attributes to be added\n\
6758	to function types pointed to by arguments of these functions.\n\
6759	The default is to return the passed argument unmodified.",
6760	tree, (tree fntype),
6761	default_cxx_adjust_cdtor_callabi_fntype)
6762
6763	DEFHOOK
6764	(adjust_class_at_definition,
6765	"@var{type} is a C++ class (i.e., RECORD_TYPE or UNION_TYPE) that has just\n\
6766	been defined. Use this hook to make adjustments to the class (eg, tweak\n\
6767	visibility or perform any other required target modifications).",
6768	void, (tree type),
6769	hook_void_tree)
6770
6771	DEFHOOK
6772	(decl_mangling_context,
6773	"Return target-specific mangling context of @var{decl} or @code{NULL_TREE}.",
6774	tree, (const_tree decl),
6775	hook_tree_const_tree_null)
6776
6777	HOOK_VECTOR_END (cxx)
6778
6779	/* Functions and data for emulated TLS support. */
6780	#undef HOOK_PREFIX
6781	#define HOOK_PREFIX "TARGET_EMUTLS_"
6782	HOOK_VECTOR (TARGET_EMUTLS, emutls)
6783
6784	/* Name of the address and common functions. */
6785	DEFHOOKPOD
6786	(get_address,
6787	"Contains the name of the helper function that uses a TLS control\n\
6788	object to locate a TLS instance. The default causes libgcc's\n\
6789	emulated TLS helper function to be used.",
6790	const char *, "__builtin___emutls_get_address")
6791
6792	DEFHOOKPOD
6793	(register_common,
6794	"Contains the name of the helper function that should be used at\n\
6795	program startup to register TLS objects that are implicitly\n\
6796	initialized to zero. If this is @code{NULL}, all TLS objects will\n\
6797	have explicit initializers. The default causes libgcc's emulated TLS\n\
6798	registration function to be used.",
6799	const char *, "__builtin___emutls_register_common")
6800
6801	/* Prefixes for proxy variable and template. */
6802	DEFHOOKPOD
6803	(var_section,
6804	"Contains the name of the section in which TLS control variables should\n\
6805	be placed. The default of @code{NULL} allows these to be placed in\n\
6806	any section.",
6807	const char *, NULL)
6808
6809	DEFHOOKPOD
6810	(tmpl_section,
6811	"Contains the name of the section in which TLS initializers should be\n\
6812	placed. The default of @code{NULL} allows these to be placed in any\n\
6813	section.",
6814	const char *, NULL)
6815
6816	/* Prefixes for proxy variable and template. */
6817	DEFHOOKPOD
6818	(var_prefix,
6819	"Contains the prefix to be prepended to TLS control variable names.\n\
6820	The default of @code{NULL} uses a target-specific prefix.",
6821	const char *, NULL)
6822
6823	DEFHOOKPOD
6824	(tmpl_prefix,
6825	"Contains the prefix to be prepended to TLS initializer objects. The\n\
6826	default of @code{NULL} uses a target-specific prefix.",
6827	const char *, NULL)
6828
6829	/* Function to generate field definitions of the proxy variable. */
6830	DEFHOOK
6831	(var_fields,
6832	"Specifies a function that generates the FIELD_DECLs for a TLS control\n\
6833	object type. @var{type} is the RECORD_TYPE the fields are for and\n\
6834	@var{name} should be filled with the structure tag, if the default of\n\
6835	@code{__emutls_object} is unsuitable. The default creates a type suitable\n\
6836	for libgcc's emulated TLS function.",
6837	tree, (tree type, tree *name),
6838	default_emutls_var_fields)
6839
6840	/* Function to initialize a proxy variable. */
6841	DEFHOOK
6842	(var_init,
6843	"Specifies a function that generates the CONSTRUCTOR to initialize a\n\
6844	TLS control object. @var{var} is the TLS control object, @var{decl}\n\
6845	is the TLS object and @var{tmpl_addr} is the address of the\n\
6846	initializer. The default initializes libgcc's emulated TLS control object.",
6847	tree, (tree var, tree decl, tree tmpl_addr),
6848	default_emutls_var_init)
6849
6850	/* Whether we are allowed to alter the usual alignment of the
6851	proxy variable. */
6852	DEFHOOKPOD
6853	(var_align_fixed,
6854	"Specifies whether the alignment of TLS control variable objects is\n\
6855	fixed and should not be increased as some backends may do to optimize\n\
6856	single objects. The default is false.",
6857	bool, false)
6858
6859	/* Whether we can emit debug information for TLS vars. */
6860	DEFHOOKPOD
6861	(debug_form_tls_address,
6862	"Specifies whether a DWARF @code{DW_OP_form_tls_address} location descriptor\n\
6863	may be used to describe emulated TLS control objects.",
6864	bool, false)
6865
6866	HOOK_VECTOR_END (emutls)
6867
6868	#undef HOOK_PREFIX
6869	#define HOOK_PREFIX "TARGET_OPTION_"
6870	HOOK_VECTOR (TARGET_OPTION_HOOKS, target_option_hooks)
6871
6872	/* Function to validate the attribute((target(...))) strings. If
6873	the option is validated, the hook should also fill in
6874	DECL_FUNCTION_SPECIFIC_TARGET in the function decl node. */
6875	DEFHOOK
6876	(valid_attribute_p,
6877	"This hook is called to parse @code{attribute(target(\"...\"))}, which\n\
6878	allows setting target-specific options on individual functions.\n\
6879	These function-specific options may differ\n\
6880	from the options specified on the command line. The hook should return\n\
6881	@code{true} if the options are valid.\n\
6882	\n\
6883	The hook should set the @code{DECL_FUNCTION_SPECIFIC_TARGET} field in\n\
6884	the function declaration to hold a pointer to a target-specific\n\
6885	@code{struct cl_target_option} structure.",
6886	bool, (tree fndecl, tree name, tree args, int flags),
6887	default_target_option_valid_attribute_p)
6888
6889	/* Function to validate the attribute((target_version(...))) strings. If
6890	the option is validated, the hook should also fill in
6891	DECL_FUNCTION_SPECIFIC_TARGET in the function decl node. */
6892	DEFHOOK
6893	(valid_version_attribute_p,
6894	"This hook is called to parse @code{attribute(target_version(\"...\"))},\n\
6895	which allows setting target-specific options on individual function versions.\n\
6896	These function-specific options may differ\n\
6897	from the options specified on the command line. The hook should return\n\
6898	@code{true} if the options are valid.\n\
6899	\n\
6900	The hook should set the @code{DECL_FUNCTION_SPECIFIC_TARGET} field in\n\
6901	the function declaration to hold a pointer to a target-specific\n\
6902	@code{struct cl_target_option} structure.",
6903	bool, (tree fndecl, tree name, tree args, int flags),
6904	default_target_option_valid_version_attribute_p)
6905
6906	/* Function to save any extra target state in the target options structure. */
6907	DEFHOOK
6908	(save,
6909	"This hook is called to save any additional target-specific information\n\
6910	in the @code{struct cl_target_option} structure for function-specific\n\
6911	options from the @code{struct gcc_options} structure.\n\
6912	@xref{Option file format}.",
6913	void, (struct cl_target_option *ptr, struct gcc_options *opts,
6914	struct gcc_options *opts_set), NULL)
6915
6916	/* Function to restore any extra target state from the target options
6917	structure. */
6918	DEFHOOK
6919	(restore,
6920	"This hook is called to restore any additional target-specific\n\
6921	information in the @code{struct cl_target_option} structure for\n\
6922	function-specific options to the @code{struct gcc_options} structure.",
6923	void, (struct gcc_options *opts, struct gcc_options *opts_set,
6924	struct cl_target_option *ptr), NULL)
6925
6926	/* Function to update target-specific option information after being
6927	streamed in. */
6928	DEFHOOK
6929	(post_stream_in,
6930	"This hook is called to update target-specific information in the\n\
6931	@code{struct cl_target_option} structure after it is streamed in from\n\
6932	LTO bytecode.",
6933	void, (struct cl_target_option *ptr), NULL)
6934
6935	/* Function to print any extra target state from the target options
6936	structure. */
6937	DEFHOOK
6938	(print,
6939	"This hook is called to print any additional target-specific\n\
6940	information in the @code{struct cl_target_option} structure for\n\
6941	function-specific options.",
6942	void, (FILE *file, int indent, struct cl_target_option *ptr), NULL)
6943
6944	/* Function to parse arguments to be validated for #pragma target, and to
6945	change the state if the options are valid. If the first argument is
6946	NULL, the second argument specifies the default options to use. Return
6947	true if the options are valid, and set the current state. */
6948	DEFHOOK
6949	(pragma_parse,
6950	"This target hook parses the options for @code{#pragma GCC target}, which\n\
6951	sets the target-specific options for functions that occur later in the\n\
6952	input stream. The options accepted should be the same as those handled by the\n\
6953	@code{TARGET_OPTION_VALID_ATTRIBUTE_P} hook.",
6954	bool, (tree args, tree pop_target),
6955	default_target_option_pragma_parse)
6956
6957	/* Do option overrides for the target. */
6958	DEFHOOK
6959	(override,
6960	"Sometimes certain combinations of command options do not make sense on\n\
6961	a particular target machine. You can override the hook\n\
6962	@code{TARGET_OPTION_OVERRIDE} to take account of this. This hooks is called\n\
6963	once just after all the command options have been parsed.\n\
6964	\n\
6965	Don't use this hook to turn on various extra optimizations for\n\
6966	@option{-O}. That is what @code{TARGET_OPTION_OPTIMIZATION} is for.\n\
6967	\n\
6968	If you need to do something whenever the optimization level is\n\
6969	changed via the optimize attribute or pragma, see\n\
6970	@code{TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE}",
6971	void, (void),
6972	hook_void_void)
6973
6974	/* This function returns true if FN1 and FN2 define the same version
6975	of a function.
6976	If DECL1 and DECL2 is not-null then emit a diagnostic if the versions do
6977	imply the same version, but are not mergeable. */
6978	DEFHOOK
6979	(same_function_versions,
6980	"This target hook returns @code{true} if the target/target-version strings\n\
6981	@var{fn1} and @var{fn2} imply the same function version.\n\
6982	\n\
6983	If @var{decl1} and @var{decl2} are non @code{NULL} then @var{fn1} and\n\
6984	@var{fn2} are from an earlier and a later declaration respectively, and the\n\
6985	hook diagnoses any version string incompatibility for these decls.\n\
6986	If the version strings are incompatible and the declarations can not be\n\
6987	merged, then hook emits an error.",
6988	bool, (string_slice fn1, const_tree decl1, string_slice fn2, const_tree decl2),
6989	hook_stringslice_consttree_stringslice_consttree_unreachable)
6990
6991	/* Checks if we can be certain that function DECL_A could resolve DECL_B. */
6992	DEFHOOK
6993	(functions_b_resolvable_from_a,
6994	"@var{decl_b} is a function declaration with a function multi-versioning\n\
6995	(FMV) attribute; this attribute is either @code{target} or\n\
6996	@code{target_version}, depending on @code{TARGET_HAS_FMV_TARGET_ATTRIBUTE}.\n\
6997	@var{decl_a} is a function declaration that may or may not have an FMV\n\
6998	attribute.\n\
6999	\n\
7000	Return true if we have enough information to determine that the\n\
7001	requirements of @var{decl_b}'s FMV attribute are met whenever @var{decl_a}\n\
7002	is executed, given that the target supports all features required by\n\
7003	function declaration @var{base}.\n\
7004	\n\
7005	The default implementation just checks whether @var{decl_a} has the same\n\
7006	FMV attribute as @var{decl_b}. This is conservatively correct,\n\
7007	but ports can do better by taking the relationships between architecture\n\
7008	features into account. For example, on AArch64, @code{sve} is present\n\
7009	whenever @code{sve2} is present.",
7010	bool, (tree decl_a, tree decl_v, tree base),
7011	functions_b_resolvable_from_a)
7012
7013	/* Function to determine if one function can inline another function. */
7014	#undef HOOK_PREFIX
7015	#define HOOK_PREFIX "TARGET_"
7016	DEFHOOK
7017	(can_inline_p,
7018	"This target hook returns @code{false} if the @var{caller} function\n\
7019	cannot inline @var{callee}, based on target specific information. By\n\
7020	default, inlining is not allowed if the callee function has function\n\
7021	specific target options and the caller does not use the same options.",
7022	bool, (tree caller, tree callee),
7023	default_target_can_inline_p)
7024
7025	DEFHOOK
7026	(update_ipa_fn_target_info,
7027	"Allow target to analyze all gimple statements for the given function to\n\
7028	record and update some target specific information for inlining. A typical\n\
7029	example is that a caller with one isa feature disabled is normally not\n\
7030	allowed to inline a callee with that same isa feature enabled even which is\n\
7031	attributed by always_inline, but with the conservative analysis on all\n\
7032	statements of the callee if we are able to guarantee the callee does not\n\
7033	exploit any instructions from the mismatch isa feature, it would be safe to\n\
7034	allow the caller to inline the callee.\n\
7035	@var{info} is one @code{unsigned int} value to record information in which\n\
7036	one set bit indicates one corresponding feature is detected in the analysis,\n\
7037	@var{stmt} is the statement being analyzed. Return true if target still\n\
7038	need to analyze the subsequent statements, otherwise return false to stop\n\
7039	subsequent analysis.\n\
7040	The default version of this hook returns false.",
7041	bool, (unsigned int& info, const gimple* stmt),
7042	default_update_ipa_fn_target_info)
7043
7044	DEFHOOK
7045	(need_ipa_fn_target_info,
7046	"Allow target to check early whether it is necessary to analyze all gimple\n\
7047	statements in the given function to update target specific information for\n\
7048	inlining. See hook @code{update_ipa_fn_target_info} for usage example of\n\
7049	target specific information. This hook is expected to be invoked ahead of\n\
7050	the iterating with hook @code{update_ipa_fn_target_info}.\n\
7051	@var{decl} is the function being analyzed, @var{info} is the same as what\n\
7052	in hook @code{update_ipa_fn_target_info}, target can do one time update\n\
7053	into @var{info} without iterating for some case. Return true if target\n\
7054	decides to analyze all gimple statements to collect information, otherwise\n\
7055	return false.\n\
7056	The default version of this hook returns false.",
7057	bool, (const_tree decl, unsigned int& info),
7058	default_need_ipa_fn_target_info)
7059
7060	DEFHOOK
7061	(relayout_function,
7062	"This target hook fixes function @var{fndecl} after attributes are processed.\n\
7063	Default does nothing. On ARM, the default function's alignment is updated\n\
7064	with the attribute target.",
7065	void, (tree fndecl),
7066	hook_void_tree)
7067
7068	HOOK_VECTOR_END (target_option)
7069
7070	/* For targets that need to mark extra registers as live on entry to
7071	the function, they should define this target hook and set their
7072	bits in the bitmap passed in. */
7073	DEFHOOK
7074	(extra_live_on_entry,
7075	"Add any hard registers to @var{regs} that are live on entry to the\n\
7076	function. This hook only needs to be defined to provide registers that\n\
7077	cannot be found by examination of FUNCTION_ARG_REGNO_P, the callee saved\n\
7078	registers, STATIC_CHAIN_INCOMING_REGNUM, STATIC_CHAIN_REGNUM,\n\
7079	TARGET_STRUCT_VALUE_RTX, FRAME_POINTER_REGNUM, EH_USES,\n\
7080	FRAME_POINTER_REGNUM, ARG_POINTER_REGNUM, and the PIC_OFFSET_TABLE_REGNUM.",
7081	void, (bitmap regs),
7082	hook_void_bitmap)
7083
7084	/* Targets should define this target hook to mark that non-callee clobbers are
7085	present in CALL_INSN_FUNCTION_USAGE for all the calls that bind to a local
7086	definition. */
7087	DEFHOOKPOD
7088	(call_fusage_contains_non_callee_clobbers,
7089	"Set to true if each call that binds to a local definition explicitly\n\
7090	clobbers or sets all non-fixed registers modified by performing the call.\n\
7091	That is, by the call pattern itself, or by code that might be inserted by the\n\
7092	linker (e.g.@: stubs, veneers, branch islands), but not including those\n\
7093	modifiable by the callee. The affected registers may be mentioned explicitly\n\
7094	in the call pattern, or included as clobbers in CALL_INSN_FUNCTION_USAGE.\n\
7095	The default version of this hook is set to false. The purpose of this hook\n\
7096	is to enable the fipa-ra optimization.",
7097	bool,
7098	false)
7099
7100	/* Fill in additional registers set up by prologue into a regset. */
7101	DEFHOOK
7102	(set_up_by_prologue,
7103	"This hook should add additional registers that are computed by the prologue\n\
7104	to the hard regset for shrink-wrapping optimization purposes.",
7105	void, (struct hard_reg_set_container *),
7106	NULL)
7107
7108	/* For targets that have attributes that can affect whether a
7109	function's return statements need checking. For instance a 'naked'
7110	function attribute. */
7111	DEFHOOK
7112	(warn_func_return,
7113	"True if a function's return statements should be checked for matching\n\
7114	the function's return type. This includes checking for falling off the end\n\
7115	of a non-void function. Return false if no such check should be made.",
7116	bool, (tree),
7117	hook_bool_tree_true)
7118
7119	#undef HOOK_PREFIX
7120	#define HOOK_PREFIX "TARGET_SHRINK_WRAP_"
7121	HOOK_VECTOR (TARGET_SHRINK_WRAP_HOOKS, shrink_wrap)
7122
7123	DEFHOOK
7124	(get_separate_components,
7125	"This hook should return an @code{sbitmap} with the bits set for those\n\
7126	components that can be separately shrink-wrapped in the current function.\n\
7127	Return @code{NULL} if the current function should not get any separate\n\
7128	shrink-wrapping.\n\
7129	Don't define this hook if it would always return @code{NULL}.\n\
7130	If it is defined, the other hooks in this group have to be defined as well.",
7131	sbitmap, (void),
7132	NULL)
7133
7134	DEFHOOK
7135	(components_for_bb,
7136	"This hook should return an @code{sbitmap} with the bits set for those\n\
7137	components where either the prologue component has to be executed before\n\
7138	the @code{basic_block}, or the epilogue component after it, or both.",
7139	sbitmap, (basic_block),
7140	NULL)
7141
7142	DEFHOOK
7143	(disqualify_components,
7144	"This hook should clear the bits in the @var{components} bitmap for those\n\
7145	components in @var{edge_components} that the target cannot handle on edge\n\
7146	@var{e}, where @var{is_prologue} says if this is for a prologue or an\n\
7147	epilogue instead.",
7148	void, (sbitmap components, edge e, sbitmap edge_components, bool is_prologue),
7149	NULL)
7150
7151	DEFHOOK
7152	(emit_prologue_components,
7153	"Emit prologue insns for the components indicated by the parameter.",
7154	void, (sbitmap),
7155	NULL)
7156
7157	DEFHOOK
7158	(emit_epilogue_components,
7159	"Emit epilogue insns for the components indicated by the parameter.",
7160	void, (sbitmap),
7161	NULL)
7162
7163	DEFHOOK
7164	(set_handled_components,
7165	"Mark the components in the parameter as handled, so that the\n\
7166	@code{prologue} and @code{epilogue} named patterns know to ignore those\n\
7167	components. The target code should not hang on to the @code{sbitmap}, it\n\
7168	will be deleted after this call.",
7169	void, (sbitmap),
7170	NULL)
7171
7172	HOOK_VECTOR_END (shrink_wrap)
7173	#undef HOOK_PREFIX
7174	#define HOOK_PREFIX "TARGET_"
7175
7176	DEFHOOK
7177	(avoid_store_forwarding_p,
7178	"Given a list of stores and a load instruction that reads from the location\n\
7179	of the stores, this hook decides if it's profitable to emit additional code\n\
7180	to avoid a potential store forwarding stall. The additional instructions\n\
7181	needed, the sequence cost and additional relevant information is given in\n\
7182	the arguments so that the target can make an informed decision.",
7183	bool, (vec<store_fwd_info>, rtx, int, bool),
7184	default_avoid_store_forwarding_p)
7185
7186	/* Determine the type of unwind info to emit for debugging. */
7187	DEFHOOK
7188	(debug_unwind_info,
7189	"This hook defines the mechanism that will be used for describing frame\n\
7190	unwind information to the debugger. Normally the hook will return\n\
7191	@code{UI_DWARF2} if DWARF 2 debug information is enabled, and\n\
7192	return @code{UI_NONE} otherwise.\n\
7193	\n\
7194	A target may return @code{UI_DWARF2} even when DWARF 2 debug information\n\
7195	is disabled in order to always output DWARF 2 frame information.\n\
7196	\n\
7197	A target may return @code{UI_TARGET} if it has ABI specified unwind tables.\n\
7198	This will suppress generation of the normal debug frame unwind information.",
7199	enum unwind_info_type, (void),
7200	default_debug_unwind_info)
7201
7202	DEFHOOK
7203	(reset_location_view,
7204	"This hook, if defined, enables -ginternal-reset-location-views, and\n\
7205	uses its result to override cases in which the estimated min insn\n\
7206	length might be nonzero even when a PC advance (i.e., a view reset)\n\
7207	cannot be taken for granted.\n\
7208	\n\
7209	If the hook is defined, it must return a positive value to indicate\n\
7210	the insn definitely advances the PC, and so the view number can be\n\
7211	safely assumed to be reset; a negative value to mean the insn\n\
7212	definitely does not advance the PC, and os the view number must not\n\
7213	be reset; or zero to decide based on the estimated insn length.\n\
7214	\n\
7215	If insn length is to be regarded as reliable, set the hook to\n\
7216	@code{hook_int_rtx_insn_0}.",
7217	int, (rtx_insn *), NULL)
7218
7219	/* The code parameter should be of type enum rtx_code but this is not
7220	defined at this time. */
7221	DEFHOOK
7222	(canonicalize_comparison,
7223	"On some machines not all possible comparisons are defined, but you can\n\
7224	convert an invalid comparison into a valid one. For example, the Alpha\n\
7225	does not have a @code{GT} comparison, but you can use an @code{LT}\n\
7226	comparison instead and swap the order of the operands.\n\
7227	\n\
7228	On such machines, implement this hook to do any required conversions.\n\
7229	@var{code} is the initial comparison code and @var{op0} and @var{op1}\n\
7230	are the left and right operands of the comparison, respectively. If\n\
7231	@var{op0_preserve_value} is @code{true} the implementation is not\n\
7232	allowed to change the value of @var{op0} since the value might be used\n\
7233	in RTXs which aren't comparisons. E.g. the implementation is not\n\
7234	allowed to swap operands in that case.\n\
7235	\n\
7236	GCC will not assume that the comparison resulting from this macro is\n\
7237	valid but will see if the resulting insn matches a pattern in the\n\
7238	@file{md} file.\n\
7239	\n\
7240	You need not to implement this hook if it would never change the\n\
7241	comparison code or operands.",
7242	void, (int *code, rtx *op0, rtx *op1, bool op0_preserve_value),
7243	default_canonicalize_comparison)
7244
7245	DEFHOOK
7246	(min_arithmetic_precision,
7247	"On some RISC architectures with 64-bit registers, the processor also\n\
7248	maintains 32-bit condition codes that make it possible to do real 32-bit\n\
7249	arithmetic, although the operations are performed on the full registers.\n\
7250	\n\
7251	On such architectures, defining this hook to 32 tells the compiler to try\n\
7252	using 32-bit arithmetical operations setting the condition codes instead\n\
7253	of doing full 64-bit arithmetic.\n\
7254	\n\
7255	More generally, define this hook on RISC architectures if you want the\n\
7256	compiler to try using arithmetical operations setting the condition codes\n\
7257	with a precision lower than the word precision.\n\
7258	\n\
7259	You need not define this hook if @code{WORD_REGISTER_OPERATIONS} is not\n\
7260	defined to 1.",
7261	unsigned int, (void), default_min_arithmetic_precision)
7262
7263	DEFHOOKPOD
7264	(atomic_test_and_set_trueval,
7265	"This value should be set if the result written by\n\
7266	@code{atomic_test_and_set} is not exactly 1, i.e.@: the\n\
7267	@code{bool} @code{true}.",
7268	unsigned char, 1)
7269
7270	/* Return an unsigned int representing the alignment (in bits) of the atomic
7271	type which maps to machine MODE. This allows alignment to be overridden
7272	as needed. */
7273	DEFHOOK
7274	(atomic_align_for_mode,
7275	"If defined, this function returns an appropriate alignment in bits for an\n\
7276	atomic object of machine_mode @var{mode}. If 0 is returned then the\n\
7277	default alignment for the specified mode is used.",
7278	unsigned int, (machine_mode mode),
7279	hook_uint_mode_0)
7280
7281	DEFHOOK
7282	(atomic_assign_expand_fenv,
7283	"ISO C11 requires atomic compound assignments that may raise floating-point\n\
7284	exceptions to raise exceptions corresponding to the arithmetic operation\n\
7285	whose result was successfully stored in a compare-and-exchange sequence.\n\
7286	This requires code equivalent to calls to @code{feholdexcept},\n\
7287	@code{feclearexcept} and @code{feupdateenv} to be generated at\n\
7288	appropriate points in the compare-and-exchange sequence. This hook should\n\
7289	set @code{*@var{hold}} to an expression equivalent to the call to\n\
7290	@code{feholdexcept}, @code{*@var{clear}} to an expression equivalent to\n\
7291	the call to @code{feclearexcept} and @code{*@var{update}} to an expression\n\
7292	equivalent to the call to @code{feupdateenv}. The three expressions are\n\
7293	@code{NULL_TREE} on entry to the hook and may be left as @code{NULL_TREE}\n\
7294	if no code is required in a particular place. The default implementation\n\
7295	leaves all three expressions as @code{NULL_TREE}. The\n\
7296	@code{__atomic_feraiseexcept} function from @code{libatomic} may be of use\n\
7297	as part of the code generated in @code{*@var{update}}.",
7298	void, (tree *hold, tree *clear, tree *update),
7299	default_atomic_assign_expand_fenv)
7300
7301	/* Leave the boolean fields at the end. */
7302
7303	/* True if we can create zeroed data by switching to a BSS section
7304	and then using ASM_OUTPUT_SKIP to allocate the space. */
7305	DEFHOOKPOD
7306	(have_switchable_bss_sections,
7307	"This flag is true if we can create zeroed data by switching to a BSS\n\
7308	section and then using @code{ASM_OUTPUT_SKIP} to allocate the space.\n\
7309	This is true on most ELF targets.",
7310	bool, false)
7311
7312	/* True if "native" constructors and destructors are supported,
7313	false if we're using collect2 for the job. */
7314	DEFHOOKPOD
7315	(have_ctors_dtors,
7316	"This value is true if the target supports some ``native'' method of\n\
7317	collecting constructors and destructors to be run at startup and exit.\n\
7318	It is false if we must use @command{collect2}.",
7319	bool, false)
7320
7321	/* True if the target wants DTORs to be run from cxa_atexit. */
7322	DEFHOOKPOD
7323	(dtors_from_cxa_atexit,
7324	"This value is true if the target wants destructors to be queued to be\n\
7325	run from @code{__cxa_atexit}. If this is the case then, for each\n\
7326	priority level, a new constructor will be entered that registers the\n\
7327	destructors for that level with @code{__cxa_atexit} (and there will be\n\
7328	no destructors emitted).\n\
7329	It is false the method implied by @code{have_ctors_dtors} is used.",
7330	bool, false)
7331
7332	/* True if thread-local storage is supported. */
7333	DEFHOOKPOD
7334	(have_tls,
7335	"Contains the value true if the target supports thread-local storage.\n\
7336	The default value is false.",
7337	bool, false)
7338
7339	/* True if a small readonly data section is supported. */
7340	DEFHOOKPOD
7341	(have_srodata_section,
7342	"Contains the value true if the target places read-only\n\
7343	``small data'' into a separate section. The default value is false.",
7344	bool, false)
7345
7346	/* True if EH frame info sections should be zero-terminated. */
7347	DEFHOOKPOD
7348	(terminate_dw2_eh_frame_info,
7349	"Contains the value true if the target should add a zero word onto the\n\
7350	end of a Dwarf-2 frame info section when used for exception handling.\n\
7351	Default value is false if @code{EH_FRAME_SECTION_NAME} is defined, and\n\
7352	true otherwise.",
7353	bool, true)
7354
7355	/* True if #NO_APP should be emitted at the beginning of assembly output. */
7356	DEFHOOKPOD
7357	(asm_file_start_app_off,
7358	"If this flag is true, the text of the macro @code{ASM_APP_OFF} will be\n\
7359	printed as the very first line in the assembly file, unless\n\
7360	@option{-fverbose-asm} is in effect. (If that macro has been defined\n\
7361	to the empty string, this variable has no effect.) With the normal\n\
7362	definition of @code{ASM_APP_OFF}, the effect is to notify the GNU\n\
7363	assembler that it need not bother stripping comments or extra\n\
7364	whitespace from its input. This allows it to work a bit faster.\n\
7365	\n\
7366	The default is false. You should not set it to true unless you have\n\
7367	verified that your port does not generate any extra whitespace or\n\
7368	comments that will cause GAS to issue errors in NO_APP mode.",
7369	bool, false)
7370
7371	/* True if output_file_directive should be called for main_input_filename
7372	at the beginning of assembly output. */
7373	DEFHOOKPOD
7374	(asm_file_start_file_directive,
7375	"If this flag is true, @code{output_file_directive} will be called\n\
7376	for the primary source file, immediately after printing\n\
7377	@code{ASM_APP_OFF} (if that is enabled). Most ELF assemblers expect\n\
7378	this to be done. The default is false.",
7379	bool, false)
7380
7381	/* Returns true if we should generate exception tables for use with the
7382	ARM EABI. The effects the encoding of function exception specifications. */
7383	DEFHOOKPOD
7384	(arm_eabi_unwinder,
7385	"This flag should be set to @code{true} on targets that use an ARM EABI\n\
7386	based unwinding library, and @code{false} on other targets. This effects\n\
7387	the format of unwinding tables, and how the unwinder in entered after\n\
7388	running a cleanup. The default is @code{false}.",
7389	bool, false)
7390
7391	DEFHOOKPOD
7392	(want_debug_pub_sections,
7393	"True if the @code{.debug_pubtypes} and @code{.debug_pubnames} sections\n\
7394	should be emitted. These sections are not used on most platforms, and\n\
7395	in particular GDB does not use them.",
7396	bool, false)
7397
7398	DEFHOOKPOD
7399	(delay_sched2,
7400	"True if sched2 is not to be run at its normal place.\n\
7401	This usually means it will be run as part of machine-specific reorg.",
7402	bool, false)
7403
7404	DEFHOOKPOD
7405	(delay_vartrack,
7406	"True if vartrack is not to be run at its normal place.\n\
7407	This usually means it will be run as part of machine-specific reorg.",
7408	bool, false)
7409
7410	DEFHOOKPOD
7411	(no_register_allocation,
7412	"True if register allocation and the passes\n\
7413	following it should not be run. Usually true only for virtual assembler\n\
7414	targets.",
7415	bool, false)
7416
7417	/* Leave the boolean fields at the end. */
7418
7419	/* Functions related to mode switching. */
7420	#undef HOOK_PREFIX
7421	#define HOOK_PREFIX "TARGET_MODE_"
7422	HOOK_VECTOR (TARGET_TOGGLE_, mode_switching)
7423
7424	DEFHOOK
7425	(emit,
7426	"Generate one or more insns to set @var{entity} to @var{mode}.\n\
7427	@var{hard_reg_live} is the set of hard registers live at the point where\n\
7428	the insn(s) are to be inserted. @var{prev_moxde} indicates the mode\n\
7429	to switch from, or is the number of modes if the previous mode is not\n\
7430	known. Sets of a lower numbered entity will be emitted before\n\
7431	sets of a higher numbered entity to a mode of the same or lower priority.",
7432	void, (int entity, int mode, int prev_mode, HARD_REG_SET regs_live), NULL)
7433
7434	DEFHOOK
7435	(needed,
7436	"@var{entity} is an integer specifying a mode-switched entity.\n\
7437	If @code{OPTIMIZE_MODE_SWITCHING} is defined, you must define this hook\n\
7438	to return the mode that @var{entity} must be switched into prior to the\n\
7439	execution of @var{insn}, or the number of modes if @var{insn} has no\n\
7440	such requirement. @var{regs_live} contains the set of hard registers\n\
7441	that are live before @var{insn}.",
7442	int, (int entity, rtx_insn *insn, HARD_REG_SET regs_live), NULL)
7443
7444	DEFHOOK
7445	(after,
7446	"@var{entity} is an integer specifying a mode-switched entity.\n\
7447	If this hook is defined, it is evaluated for every @var{insn} during mode\n\
7448	switching. It returns the mode that @var{entity} is in after @var{insn}\n\
7449	has been executed. @var{mode} is the mode that @var{entity} was in\n\
7450	before @var{insn} was executed, taking account of @var{TARGET_MODE_NEEDED}.\n\
7451	@var{regs_live} is the set of hard registers that are live after @var{insn}\n\
7452	has been executed.\n\
7453	\n\
7454	@var{mode} is equal to the number of modes defined for @var{entity}\n\
7455	if the mode before @var{insn} is unknown. The hook should likewise return\n\
7456	the number of modes if it does not know what mode @var{entity} has after\n\
7457	@var{insn}.\n\
7458	\n\
7459	Not defining the hook is equivalent to returning @var{mode}.",
7460	int, (int entity, int mode, rtx_insn *insn, HARD_REG_SET regs_live), NULL)
7461
7462	DEFHOOK
7463	(confluence,
7464	"By default, the mode-switching pass assumes that a given entity's modes\n\
7465	are mutually exclusive. This means that the pass can only tell\n\
7466	@code{TARGET_MODE_EMIT} about an entity's previous mode if all\n\
7467	incoming paths of execution leave the entity in the same state.\n\
7468	\n\
7469	However, some entities might have overlapping, non-exclusive modes,\n\
7470	so that it is sometimes possible to represent ``mode @var{mode1} or mode\n\
7471	@var{mode2}'' with something more specific than ``mode not known''.\n\
7472	If this is true for at least one entity, you should define this hook\n\
7473	and make it return a mode that includes @var{mode1} and @var{mode2}\n\
7474	as possibilities. (The mode can include other possibilities too.)\n\
7475	The hook should return the number of modes if no suitable mode exists\n\
7476	for the given arguments.",
7477	int, (int entity, int mode1, int mode2), NULL)
7478
7479	DEFHOOK
7480	(backprop,
7481	"If defined, the mode-switching pass uses this hook to back-propagate mode\n\
7482	requirements through blocks that have no mode requirements of their own.\n\
7483	Specifically, @var{mode1} is the mode that @var{entity} has on exit\n\
7484	from a block B1 (say) and @var{mode2} is the mode that the next block\n\
7485	requires @var{entity} to have. B1 does not have any mode requirements\n\
7486	of its own.\n\
7487	\n\
7488	The hook should return the mode that it prefers or requires @var{entity}\n\
7489	to have in B1, or the number of modes if there is no such requirement.\n\
7490	If the hook returns a required mode for more than one of B1's outgoing\n\
7491	edges, those modes are combined as for @code{TARGET_MODE_CONFLUENCE}.\n\
7492	\n\
7493	For example, suppose there is a ``one-shot'' entity that,\n\
7494	for a given execution of a function, either stays off or makes exactly\n\
7495	one transition from off to on. It is safe to make the transition at any\n\
7496	time, but it is better not to do so unnecessarily. This hook allows the\n\
7497	function to manage such an entity without having to track its state at\n\
7498	runtime. Specifically. the entity would have two modes, 0 for off and\n\
7499	1 for on, with 2 representing ``don't know''. The system is forbidden from\n\
7500	transitioning from 2 to 1, since 2 represents the possibility that the\n\
7501	entity is already on (and the aim is to avoid having to emit code to\n\
7502	check for that case). This hook would therefore return 1 when @var{mode1}\n\
7503	is 2 and @var{mode2} is 1, which would force the entity to be on in the\n\
7504	source block. Applying this inductively would remove all transitions\n\
7505	in which the previous state is unknown.",
7506	int, (int entity, int mode1, int mode2), NULL)
7507
7508	DEFHOOK
7509	(entry,
7510	"If this hook is defined, it is evaluated for every @var{entity} that\n\
7511	needs mode switching. It should return the mode that @var{entity} is\n\
7512	guaranteed to be in on entry to the function, or the number of modes\n\
7513	if there is no such guarantee.\n\
7514	If @code{TARGET_MODE_ENTRY} is defined then @code{TARGET_MODE_EXIT}\n\
7515	must be defined.",
7516	int, (int entity), NULL)
7517
7518	DEFHOOK
7519	(exit,
7520	"If this hook is defined, it is evaluated for every @var{entity} that\n\
7521	needs mode switching. It should return the mode that @var{entity} must\n\
7522	be in on return from the function, or the number of modes if there is no\n\
7523	such requirement.\n\
7524	If @code{TARGET_MODE_EXIT} is defined then @code{TARGET_MODE_ENTRY}\n\
7525	must be defined.",
7526	int, (int entity), NULL)
7527
7528	DEFHOOK
7529	(eh_handler,
7530	"If this hook is defined, it should return the mode that @var{entity} is\n\
7531	guaranteed to be in on entry to an exception handler, or the number of modes\n\
7532	if there is no such guarantee.",
7533	int, (int entity), NULL)
7534
7535	DEFHOOK
7536	(priority,
7537	"This hook specifies the order in which modes for @var{entity}\n\
7538	are processed. 0 is the highest priority,\n\
7539	@code{NUM_MODES_FOR_MODE_SWITCHING[@var{entity}] - 1} the lowest.\n\
7540	The hook returns an integer designating a mode\n\
7541	for @var{entity}. For any fixed @var{entity}, @code{mode_priority}\n\
7542	(@var{entity}, @var{n}) shall be a bijection in 0 @dots{}\n\
7543	@code{num_modes_for_mode_switching[@var{entity}] - 1}.",
7544	int, (int entity, int n), NULL)
7545
7546	HOOK_VECTOR_END (mode_switching)
7547
7548	#undef HOOK_PREFIX
7549	#define HOOK_PREFIX "TARGET_MEMTAG_"
7550	HOOK_VECTOR (TARGET_MEMTAG_, memtag)
7551
7552	DEFHOOK
7553	(can_tag_addresses,
7554	"True if the backend architecture naturally supports ignoring some region\n\
7555	of pointers. This feature means that @option{-fsanitize=hwaddress} can\n\
7556	work.\n\
7557	\n\
7558	At preset, this feature does not support address spaces. It also requires\n\
7559	@code{Pmode} to be the same as @code{ptr_mode}.",
7560	bool, (), default_memtag_can_tag_addresses)
7561
7562	DEFHOOK
7563	(tag_bitsize,
7564	"Return the size of a tag (in bits) for this platform.\n\
7565	\n\
7566	The default returns 8.",
7567	uint8_t, (), default_memtag_tag_bitsize)
7568
7569	DEFHOOK
7570	(granule_size,
7571	"Return the size in real memory that each byte in shadow memory refers to.\n\
7572	I.e. if a variable is @var{X} bytes long in memory, then this hook should\n\
7573	return the value @var{Y} such that the tag in shadow memory spans\n\
7574	@var{X}/@var{Y} bytes.\n\
7575	\n\
7576	Most variables will need to be aligned to this amount since two variables\n\
7577	that are neighbors in memory and share a tag granule would need to share\n\
7578	the same tag.\n\
7579	\n\
7580	The default returns 16.",
7581	uint8_t, (), default_memtag_granule_size)
7582
7583	DEFHOOK
7584	(insert_random_tag,
7585	"Return an RTX representing the value of @var{untagged} but with a\n\
7586	(possibly) random tag in it.\n\
7587	Put that value into @var{target} if it is convenient to do so.\n\
7588	This function is used to generate a tagged base for the current stack frame.\n\
7589	It is also used by memtag-stack sanitizer to emit specific memory tagging\n\
7590	instructions.",
7591	rtx, (rtx untagged, rtx target), default_memtag_insert_random_tag)
7592
7593	DEFHOOK
7594	(add_tag,
7595	"Return an RTX that represents the result of adding @var{addr_offset} to\n\
7596	the address in pointer @var{base} and @var{tag_offset} to the tag in pointer\n\
7597	@var{base}.\n\
7598	The resulting RTX must either be a valid memory address or be able to get\n\
7599	put into an operand with @code{force_operand}.\n\
7600	\n\
7601	Unlike other memtag hooks, this must return an expression and not emit any\n\
7602	RTL. In the case of memtag-stack sanitizer, this constraint is not enforced.",
7603	rtx, (rtx base, poly_int64 addr_offset, uint8_t tag_offset),
7604	default_memtag_add_tag)
7605
7606	DEFHOOK
7607	(set_tag,
7608	"Return an RTX representing @var{untagged_base} but with the tag @var{tag}.\n\
7609	Try and store this in @var{target} if convenient.\n\
7610	@var{untagged_base} is required to have a zero tag when this hook is called.\n\
7611	The default of this hook is to set the top byte of @var{untagged_base} to\n\
7612	@var{tag}.",
7613	rtx, (rtx untagged_base, rtx tag, rtx target), default_memtag_set_tag)
7614
7615	DEFHOOK
7616	(extract_tag,
7617	"Return an RTX representing the tag stored in @var{tagged_pointer}.\n\
7618	Store the result in @var{target} if it is convenient.\n\
7619	The default represents the top byte of the original pointer.\n\
7620	In the case of memtag-stack sanitizer for targets that can process\n\
7621	tagged pointers (i.e. AArch64), this hook can return a tagged pointer.",
7622	rtx, (rtx tagged_pointer, rtx target), default_memtag_extract_tag)
7623
7624	DEFHOOK
7625	(untagged_pointer,
7626	"Return an RTX representing @var{tagged_pointer} with its tag set to zero.\n\
7627	Store the result in @var{target} if convenient.\n\
7628	The default clears the top byte of the original pointer.",
7629	rtx, (rtx tagged_pointer, rtx target), default_memtag_untagged_pointer)
7630
7631	HOOK_VECTOR_END (memtag)
7632	#undef HOOK_PREFIX
7633	#define HOOK_PREFIX "TARGET_"
7634
7635	#define DEF_TARGET_INSN(NAME, PROTO) \
7636	DEFHOOK_UNDOC (have_##NAME, "", bool, (void), false)
7637	#include "target-insns.def"
7638	#undef DEF_TARGET_INSN
7639
7640	#define DEF_TARGET_INSN(NAME, PROTO) \
7641	DEFHOOK_UNDOC (gen_##NAME, "", rtx_insn *, PROTO, NULL)
7642	#include "target-insns.def"
7643	#undef DEF_TARGET_INSN
7644
7645	#define DEF_TARGET_INSN(NAME, PROTO) \
7646	DEFHOOKPOD (code_for_##NAME, "*", enum insn_code, CODE_FOR_nothing)
7647	#include "target-insns.def"
7648	#undef DEF_TARGET_INSN
7649
7650	DEFHOOK
7651	(run_target_selftests,
7652	"If selftests are enabled, run any selftests for this target.",
7653	void, (void),
7654	NULL)
7655
7656	/* This value represents whether the shadow call stack is implemented on
7657	the target platform. */
7658	DEFHOOKPOD
7659	(have_shadow_call_stack,
7660	"This value is true if the target platform supports\n\
7661	@option{-fsanitize=shadow-call-stack}. The default value is false.",
7662	bool, false)
7663
7664	/* This value represents whether libatomic is available on
7665	the target platform. */
7666	DEFHOOKPOD
7667	(have_libatomic,
7668	"This value is true if the target platform supports\n\
7669	libatomic. The default value is false.",
7670	bool, false)
7671
7672	/* This value represents whether libatomic is available on
7673	the target platform. */
7674	DEFHOOKPOD
7675	(documentation_name,
7676	"If non-NULL, this value is a string used for locating target-specific\
7677	documentation for this target.\n\
7678	The default value is NULL.",
7679	const char *, NULL)
7680
7681	/* Close the 'struct gcc_target' definition. */
7682	HOOK_VECTOR_END (C90_EMPTY_HACK)
7683
7684